Source: http://www.patentsencyclopedia.com/app/20090239965
Timestamp: 2016-12-10 13:20:15
Document Index: 319761502

Matched Legal Cases: ['art) 50', 'art) 30', 'art) 20', 'art) 20', 'art) 10', 'art) 55', 'art) 25', 'art) 10', 'art) 10', 'art) 12', 'art) 13', 'art) 25', 'art) 12']

RUBBER COMPOSITION FOR SHOE SOLE AND RUBBER FOAM COMPOSITION - Patent application
Patent application title: RUBBER COMPOSITION FOR SHOE SOLE AND RUBBER FOAM COMPOSITION
Takashi Wada (Chiba, JP)
Yukio Nakamura (Chiba, JP)
Naomi Okamoto (Chiba, JP)
Patent application number: 20090239965
Provided is a rubber composition for shoe soles prepared by blending 100
mass parts of a polymer component comprising 10 to 90 mass % of a
vinyl/cis-polybutadiene rubber (A) comprising 1,4-cis-polybutadiene (a)
and 1,2-polybutadiene crystalline fibers (b) in which the crystalline
fibers have an average fiber length of 200 nm or less and an average
aspect ratio of 10 or less, in which the number of the crystalline fibers
having a fiber length of 200 nm or less is 90 fibers or more per 25
μm2 and in which a melting point is 170° C. or higher, 10
to 50 mass % of a diene base rubber (B) other than the polybutadiene
rubber (A) and 2 to 50 mass % of a thermoplastic polymer (C) with 2 to 50
mass parts of a rubber reinforcing material (D).
The above rubber composition for shoe soles has a light weight and an
appropriate hardness and is excellent in a tensile strength, a tear
strength, an abrasion resistance and a gripping property and excellent as
well in a dimensional stability after foaming, and it is suited as an
outsole for shoes.Claims:
1. A rubber composition for shoe soles prepared by blending 100 mass parts
of a polymer component comprising 10 to 90 mass % of a
μm2 and in which a melting point is 170.degree. C. or higher, 10
to 50 mass % of a diene base rubber (B) other than the
vinyl/cis-polybutadiene rubber (A) and 2 to 50 mass % of a thermoplastic
polymer (C) with 2 to 50 mass parts of a rubber reinforcing material (D).
2. The rubber composition for shoe soles as described in claim 1, wherein
the vinyl/cis-polybutadiene rubber (A) is obtained by:(1) subjecting a
mixture comprising 1,3-butadiene and a hydrocarbon base solvent as
principal components to cis-1,4-polymerization with 1,3-butadiene in the
presence of a catalyst comprising an organic aluminum compound and a
soluble cobalt compound to produce 1,4-cis-polybutadiene (a) and(2)
polymerizing the polymerization reaction mixture thus obtained with
1,3-butadiene in the presence of a catalyst comprising an organic
aluminum compound and carbon disulfide and in the presence of an
unsaturated high molecular compound comprising at least one selected from
polyisoprene, crystalline polybutadiene having a melting point of
150.degree. C. or lower, liquid polybutadiene and derivatives thereof
after further adding 1,3-butadiene to the above polymerization reaction
mixture or without adding 1,3-butadiene thereto to produce
1,2-polybutadiene crystalline fibers (b) having a melting point of
170.degree. C. or higher,(3) wherein the 1,2-polybutadiene crystalline
fibers (b) and the unsaturated high molecular compound are dispersed in a
matrix comprising the 1,4-cis-polybutadiene (a).
3. The rubber composition for shoe soles as described in claim 1, wherein
the vinyl/cis-polybutadiene rubber (A) is obtained by:(1) adding a
catalyst comprising an organic aluminum compound and a soluble cobalt
compound to a mixture comprising 1,3-butadiene and a hydrocarbon base
solvent having a solubility parameter (SP value) of 8.5 or less as
principal components to subject 1,3-butadiene to cis-1,4-polymerization
to thereby produce 1,4-cis-polybutadiene (a), wherein an organic aluminum
compound represented by a formula AlRnX3-n (wherein R is an
alkyl group having 1 to 6 carbon atoms, a phenyl group or a cycloalkyl
group; X is a halogen element; and n is a number of 1.5 to 2) is used as
the organic aluminum compound and(2) then subjecting the polymerization
reaction mixture thus obtained to 1,2-polymerization with 1,3-butadiene
in the presence of a catalyst comprising a soluble cobalt compound, an
organic aluminum compound represented by a formula AlR3 (wherein R
is an alkyl group having 1 to 6 carbon atoms, a phenyl group or a
cycloalkyl group) and carbon disulfide after adding 1,3-butadiene to the
above polymerization reaction mixture or without adding 1,3-butadiene
thereto to produce 1,2-polybutadiene crystalline fibers (b) having a
melting point of 170.degree. C. or higher.
4. The rubber composition for shoe soles as described in claim 1, wherein
solvent as principal components to subject 1,3-butadiene to
cis-1,4-polymerization to thereby produce 1,4-cis-polybutadiene (a),(2)
subjecting the polymerization reaction mixture thus obtained to
1,2-polymerization with 1,3-butadiene in the presence of a catalyst
comprising a soluble cobalt compound, an organic aluminum compound
represented by a formula AlR3 (wherein R is an alkyl group having 1
to 6 carbon atoms, a phenyl group or a cycloalkyl group) and carbon
disulfide after adding 1,3-butadiene to the above polymerization reaction
170.degree. C. or higher and(3) thereby obtaining vinyl/cis-polybutadiene
(A-4) in which the 1,2-polybutadiene crystalline fibers (b) are dispersed
in a matrix comprising the 1,4-cis-polybutadiene (a) and solution-mixing
the vinyl/cis-polybutadiene (A-4) with 1,4-cis-polybutadiene (a-4).
5. The rubber composition for shoe soles as described in claim 4, wherein
the 1,4-cis-polybutadiene mixed in the step (3) has a smaller Mooney
viscosity than that of the 1,4-cis-polybutadiene (a) obtained in the step
6. The rubber composition for shoe soles as described in claim 1, wherein
the 1,4-cis-polybutadiene (a) has the following characteristics:(1) a
1,4-cis structure content is 80 mol % or more;(2) a ratio (toluene
solution viscosity/Mooney viscosity) of a toluene solution viscosity
(T-cp) to a Mooney viscosity (ML1+4, 100.degree. C.) is 1 or more; and(3)
an intrinsic viscosity [α] is 1.0 to 5.0 dl/g.
7. The rubber composition for shoe soles as described in claim 1, wherein
the diene base rubber (B) other than the vinyl/cis-polybutadiene rubber
(A) is natural rubber and/or polyisoprene.
8. The rubber composition for shoe soles as described in claim 1, wherein
the rubber reinforcing material is silica and/or carbon black.
9. An outsole for shoes characterized by using the rubber composition for
shoe soles as described in claim 1.
10. A rubber foam composition for shoe soles prepared by foaming the
rubber composition for shoe soles as described in claim 1.
11. An outsole for shoes characterized by using the rubber foam
composition as described in claim 10.Description:
[0001]The present invention relates to a rubber composition for shoe soles
which is lightweight and has an appropriate hardness and which is
excellent in a tensile strength, a tear strength, an abrasion resistance
and a gripping property and a rubber foam composition for shoe soles
which is excellent as well in a dimensional stability of a shoe sole
after foaming.
[0002]A strength which supports a weight of a wearer and which endures a
load and an impact force brought about by exercise, a foot comfort of
shoes, a reduction in a weight for enhancing a safety and a gripping
property are required to a rubber composition for shoe soles, and various
proposals have been made (refer to, for example, patent documents 1 to
[0003]A rubber composition which is reinforced by blending a
1,2-polybutadiene, polyisoprene rubber and the like with a styrene
butadiene rubber and an inorganic reinforcing material is disclosed in
the patent document 1. However, an increase in an amount of the inorganic
reinforcing material involves the problems that the viscosity is elevated
though the composition is reduced in swell or the product is increased in
a weight and that the abrasion resistance and the tear strength are not
satisfactory due to the blended styrene butadiene rubber.
[0004]An outsole for shoes comprising a vulcanized molded material of a
rubber composition in which a mixture of a solution-polymerized
styrene-butadiene rubber having a specific loss factor peak temperature
with a butadiene rubber is blended with hydrated silica in order to
enhance an abrasion resistance and a gripping property is disclosed in
the patent document 2. However, an effect of improving an abrasion
resistance and a gripping property thereof as a shoe sole material has
[0005]A shoe sole composed of a laminate of an intermediate sole formed by
a cushioned foam and an outside sole formed by a semi-hard rubber having
a hardness of 50 to 70 degree in order to improve an impact absorption is
disclosed in the patent document 3. However, the semi-hard rubber having
a hardness of 50 to 70 degree involves the problems that it is hard and
exerts a large load onto a knee and that it is slippy since it is less
liable to be brought into tight contact with the ground, so that falling
is likely to take place on a wet road.
[0006]An outsole in which a base material rubber comprises bromide of a
copolymer of isobutylene and paramethylstyrene is disclosed in the patent
document 4. It is shown therein that the above base material rubber is
improved in a gripping property to some extent but deteriorated in an
abrasion resistance, so that a large amount of carbon black is blended as
a reinforcing filler, and the problem that a reduction in the weight is
unsatisfactory is involved therein.
[0007]A shoe sole material obtained by foaming and curing a composition
prepared by blending a polymer with syndiotactic 1,2-polybutadiene having
a hardness of 98 or more and a melting point of 110° C. or higher
and cis 1,4-polybutadiene is disclosed in the patent document 5. Further,
a composition for a foam comprising 1,2-polybutadiene, a
vinyl/cis-butadiene rubber, a thermoplastic polymer, a foaming agent and
a cross-linking agent is disclosed in the patent document 6, and it is
described therein that the above composition is useful as a composition
for shoe soles. However, a strength and an abrasion resistance of the
above foaming materials do not stay at a satisfactory level and are
required to be further improved.
Patent document 1: Japanese Patent Application Laid-Open No.Patent
document 2: Japanese Patent Application Laid-Open No.Patent document 3:
Japanese Patent Application Laid-Open No.Patent document 4: Japanese
Patent Application Laid-Open No.Patent document 5: Japanese Patent
Application Laid-Open No.Patent document 6: Japanese Patent Application
Laid-Open No.
[0008]An object of the present invention is to provide a rubber
composition for shoe soles which is lightweight and has an appropriate
hardness and which is excellent in a tensile strength, a tear strength,
an abrasion resistance and a gripping property and a rubber foam
composition for shoe soles which is excellent as well in a dimensional
stability after foaming.
[0009]The present inventors have found that a rubber composition obtained
by blending specific vinyl/cis-polybutadiene containing fibrous
1,2-polybutadiene with a diene base rubber other than the above rubber, a
thermoplastic polymer and a rubber reinforcing material in specific
amounts can achieve the object described above, and thus they have
completed the present invention.
[0010]That is, the present invention provides the following matters
described in items [1] to [4].
[1] A rubber composition for shoe soles prepared by blending 100 mass
parts of a polymer component comprising 10 to 90 mass % of a
mass parts of a rubber reinforcing material (D).[2] An outsole for shoes
characterized by using the rubber composition for shoe soles as described
in the above item [1].[3] A rubber foam composition for shoe soles
prepared by foaming the rubber composition as described in the above item
[1].[4] An outsole for shoes characterized by using the rubber foam
composition as described in the above item [3].
[0011]The rubber composition for shoe soles according to the present
invention is lightweight and has an appropriate hardness, and it is
and a gripping property. The rubber foam composition for shoe soles
according to the present invention is excellent, in addition to the
characteristics described above, in a dimensional stability after
foaming. An outsole for shoes prepared by using the rubber composition or
the rubber foam composition according to the present invention as a
rubber base material is suited as an outsole for shoes such as men's
shoes, ladies' shoes, sport shoes and the like.
[0012]FIG. 1 (A) is a schematic drawing of a transmission type electron
micrograph obtained in Production Example 1, and (B) is a schematic
drawing of a transmission type electron micrograph obtained in
Comparative Production Example 1.
Rubber Composition for Shoe Soles
[0013]The rubber composition for shoe soles according to the present
invention is prepared by blending 100 mass parts of a polymer component
comprising 10 to 90 mass % of a vinyl/cis-polybutadiene rubber (A)
comprising 1,4-cis-polybutadiene (a) and 1,2-polybutadiene crystalline
fibers (b) in which the crystalline fibers have an average fiber length
of 200 nm or less and an average aspect ratio of 10 or less and in which
the number of the crystalline fibers having a fiber length of 200 nm or
less is 90 fibers or more per 25 μm2 and a melting point is
170° C. or higher, 10 to 50 mass % of a diene base rubber (B)
other than the vinyl/cis-polybutadiene rubber (A) and 2 to 50 mass % of a
thermoplastic polymer (C) with 2 to 50 mass parts of a rubber reinforcing
material (D).
[0014]The rubber composition for shoe soles according to the present
invention has three embodiments depending on a difference in the
vinyl/cis-polybutadiene rubber (A). The details of the first embodiment
to the third embodiment shall be explained below in order.
Rubber Composition for Shoe Soles According to the First Embodiment
[0015]In the first embodiment of the present invention, the
vinyl/cis-polybutadiene rubber (A) in the rubber composition for shoe
soles described above is a vinyl/cis-polybutadiene rubber (A-1) obtained
(1) subjecting a mixture comprising 1,3-butadiene and a hydrocarbon base
solvent as principal components to cis-1,4-polymerization with
aluminum compound and a soluble cobalt compound to produce
1,4-cis-polybutadiene (a) and(2) polymerizing the polymerization reaction
mixture thus obtained with 1,3-butadiene in the presence of a catalyst
comprising an organic aluminum compound and carbon disulfide and in the
presence of an unsaturated high molecular compound comprising at least
one selected from polyisoprene, crystalline polybutadiene having a
melting point of 150° C. or lower, liquid polybutadiene and
derivatives thereof after further adding 1,3-butadiene to the above
polymerization reaction mixture or without adding 1,3-butadiene thereto
to produce 1,2-polybutadiene crystalline fibers (b) having a melting
point of 170° C. or higher,(3) wherein the 1,2-polybutadiene
crystalline fibers (b) and the unsaturated high molecular compound are
dispersed in a matrix comprising the 1,4-cis-polybutadiene (a).
Vinyl/cis-Polybutadiene Rubber (A-1)
[0016]The vinyl/cis-polybutadiene rubber (A-1) used in the first
embodiment of the present invention is produced through the steps (1) to
(3) described above, whereby it is provided with excellent mechanical
[0017]An appropriate example of a production process for the
vinyl/cis-polybutadiene rubber (A-1) shall be explained below.
[0018]The unsaturated high molecular compound can be added in the step
(2), but from the viewpoint of evenly dispersing the unsaturated high
molecular compound in the matrix comprising the 1,4-cis-polybutadiene
(a), the unsaturated high molecular compound can be added as well in
advance in the step (1).
[0019]Further, from the viewpoint of efficiently promoting a continuous
polymerization reaction, carbon disulfide which is used as the catalyst
in the step (2) can be added as well in advance in the step (1).
[0020]First, 1,3-butadiene is mixed with a hydrocarbon base solvent, and
1,3-butadiene is subjected to cis-1,4-polymerization in the presence of a
compound to produce 1,4-cis-polybutadiene (a) having a 1,4-cis structure
content of preferably 80 mol % or more.
[0021]The hydrocarbon base solvent includes aromatic hydrocarbons such as
benzene, toluene, xylene and the like, aliphatic hydrocarbons such as
n-hexane, butane, heptane, pentane and the like, alicyclic hydrocarbons
such as cyclopentane, cyclohexane and the like, olefin base hydrocarbons
such as olefin compounds of the hydrocarbons described above,
cis-2-butene, trans-2-butene and the like, hydrocarbon base solvents such
as mineral spirits, solvent naphtha, kerosene and the like and
halogenated hydrocarbon base solvents such as methylene chloride and the
like. A 1,3-butadiene monomer (SP value: 6.8) itself also can be used as
the polymerization solvent.
[0022]Among them, the solvents having a solubility parameter (SP value) of
9.0 or less are preferred. The hydrocarbon base solvents can be used
alone or in combination of two or more kinds thereof so as to control an
SP value to 9.0 or less. The hydrocarbon base solvents having a
solubility parameter of 9.0 or less shall be described in details in the
explanations of the second embodiment.
[0023]The mixture comprising 1,3-butadiene and the hydrocarbon base
solvent as principal components which is obtained by mixing both
components is preferably controlled in a concentration of a moisture
thereof before brought into contact with the organic aluminum compound
which is one of the catalyst components. The moisture concentration can
be controlled by a publicly known method, for example, a method in which
the mixture is added and dispersed by passing through a porous filtering
material (refer to Japanese Patent Application Laid-Open No. 85304/1992).
[0024]The moisture concentration falls in a range of preferably 0.1 to 1.0
mole, particularly preferably 0.2 to 1.0 mole per mole of the organic
aluminum compound contained in the mixture described above. The moisture
concentration falling in the above range makes it possible to effectively
inhibit a reduction in the catalyst activity, a reduction in the cis-1,4
structure content, an abnormal variation in the molecular weight, gel
produced in the polymerization and the like to make it possible to carry
out continuous polymerization over a long period of time.
[0025]The organic aluminum compound and the soluble cobalt compound are
added as a catalyst to the mixture described above in which a moisture
concentration is controlled to carry out cis-1,4-polymerization. An
addition order of the organic aluminum compound and the soluble cobalt
compound shall not specifically be restricted, and the soluble cobalt
compound is added preferably after adding the organic aluminum compound.
[0026]The organic aluminum compound shall not specifically be restricted,
and it is preferably at least one selected from (I) trialkylaluminum
compounds and triphenylaluminum compounds, (II) organic aluminum halogen
compounds and (III) hydrogenated organic aluminum compounds.
[0027]The trialkylaluminum compounds (I) include trialkylaluminum
compounds having an alkyl group having 1 to 10 carbon atoms, preferably 1
to 6 carbon atoms such as trimethylaluminum, triethylaluminum,
triisobutylaluminum, trihexylaluminum, trioctylaluminum, tridecylaluminum
[0028]The organic aluminum halogen compounds (II) include organic aluminum
halogen compounds having an alkyl group having 1 to 6 carbon atoms such
as (i) dialkylaluminum monohalides, (ii) alkylaluminum dihalides and
(iii) alkylaluminum sesquihalides and in addition thereto,
dicyclohexylaluminum monochloride, diphenylaluminum monochloride and the
[0029]The dialkylaluminum monohalides (i) include dialkylaluminum
monochlorides such as dimethylaluminum monochloride, diethylaluminum
monochloride and dibutylaluminum monochloride, diethylaluminum
monobromide and the like.
[0030]The alkylaluminum dihalides (ii) include alkylaluminum dichlorides
such as ethylaluminum dichloride and the like, alkylaluminum dibromide
[0031]The alkylaluminum sesquihalides (iii) include alkylaluminum
sesquichloride such as ethylaluminum sesquichloride and the like,
alkylaluminum sesquibromide and the like.
[0032]The hydrogenated organic aluminum compounds (III) include
diethylaluminum hydride, diisobutylaluminum hydride, sesquiethylaluminum
hydride and the like.
[0033]Among them, the organic aluminum halogen compounds (II) are
preferred, and dialkylaluminum monohalides are more preferred.
Dialkylaluminum monochlorides having an alkyl group having 1 to 6 carbon
[0034]The organic aluminum compounds described above can be used alone or
in combination of two or more kinds thereof.
[0035]A use amount of the organic aluminum compounds is preferably 0.1
millimole or more, particularly preferably 0.5 to 50 millimole per mole
of the whole amount of 1,3-butadiene.
Soluble Cobalt Compound
[0036]The soluble cobalt compound is preferably a compound which is
soluble or can homogeneously be dispersed in an inert medium comprising a
hydrocarbon base solvent as a principal component or liquid
1,3-butadiene. To be specific, it includes, for example, β-diketone
complexes of cobalt such as cobalt (II) acetylacetonate, cobalt (III)
acetylacetonate and the like, β-keto acid ester complexes of cobalt
such as cobalt acetoacetic acid ethyl ester complexes and the like,
cobalt salts of organic carboxylic acids having 6 or more carbon atoms
such as cobalt octoate, cobalt naphthenate, cobalt benzoate and the like
and halogenated cobalt complexes such as cobalt chloride pyridine
complexes, cobalt chloride ethyl alcohol complexes and the like.
[0037]A use amount of the soluble cobalt compound is preferably 0.001
millimole or more, particularly preferably 0.005 to 0.1 millimole per
mole of 1,3-butadiene.
[0038]A mole ratio (Al/Co) of the organic aluminum chloride to the soluble
cobalt compound is preferably 10 or more, particularly preferably 50 or
[0039]A reaction temperature for carrying out the cis-1,4-polymerization
is preferably over 0° C. and 100° C. or lower, more
preferably 10 to 100° C. and particularly preferably 20 to
100° C. The polymerization time (average residence time) is
preferably 10 minutes to 2 hours. The cis-1,4-polymerization is
preferably carried out so that the polymer concentration after the
polymerization is 5 to 26 mass %.
[0040]A single bath or a bath obtained by connecting two or more baths can
be used for the polymerization bath (polymerization vessel). The
polymerization can be carried out by stirring and mixing the
polymerization solution using a polymerization bath equipped with a high
viscosity liquid stirring device, for example, an apparatus described in
Japanese Patent Publication No. 2645/1965.
[0041]In the cis-1,4-polymerization, capable of being used are publicly
known molecular weight controlling agents, for example, non-conjugate
dienes such as cyclooctadiene, allene, methylallene (1,2-butadiene) and
the like, α-olefins such as ethylene, propylene, butene-1 and the
like and publicly known gelation inhibitors for inhibiting production of
gels in polymerization.
[0042]The 1,4-cis-polybutadiene (a) thus obtained has preferably the
following characteristics from the viewpoint of a processability, a
strength and an abrasion resistance.
(1) The 1,4-cis structure content is preferably 80 mol % or more, more
preferably 90 mol % or more and particularly preferably 95 to 100 mol %.
The cis structure content is a value calculated from an absorption
intensity ratio of a peak 740 cm-1 in a cis structure determined by
infrared absorption spectral analysis.(2) The Mooney viscosity (ML1+4,
100° C.) is preferably 10 to 130, more preferably 15 to 80. This
enhances the workability in blending and the dispersibility. The Mooney
viscosity is a value measured at 100° C. according to JIS
K6300.(3) The 5 mass % toluene solution viscosity (T-cp) at 25° C.
is preferably 10 to 300 centipoise (cp), more preferably 20 to 200 cp and
particularly preferably 30 to 200 cp.(4) A ratio (toluene solution
viscosity/Mooney viscosity) of the toluene solution viscosity (T-cp) to
the Mooney viscosity (ML1+4, 100° C.) is 1 or more, preferably 1
to 4.(5) The intrinsic viscosity [77] is 1.0 to 5.0 dl/g, preferably 1.0
to 4.0 dl/g.
[0043]The intrinsic viscosity [η] is a value determined by the
following equation by putting 0.1 g of the sample rubber and 100 ml of
toluene into a conical flask to completely dissolve the sample at
30° C. and then putting 10 ml of the solution prepared above into
a Canon Fenske kinetic viscometer in a constant temperature water bath
controlled to 30° C. to measure a falling time (T) of the
solution. [0044]Specific viscosity (ηsp)=T/T-1 (falling time
of toluene only) [0045]Molecular weight index
(ηsp/c)=[η]+k'[η]2c [0046](k': Huggins constant
(0.37), c: sample concentration (g/ml))(6) A toluene-insoluble content is
0.5 mass % or less, and a gel is not substantially contained.
[0047]In this respect, the toluene-insoluble content is a gel content
obtained by putting 10 g of the sample rubber and 400 ml of toluene into
a conical flask to completely dissolve the sample at room temperature
(25° C.) and then filtering the solution through a filter equipped
with a metal gauze of 200 mesh to obtain a gel adhered on the metal gauze
after filtering. The metal gauze on which the gel is adhered is dried
under vacuum to measure an adhered amount thereof, and the
toluene-insoluble content is shown by a percentage based on the sample
(7) The polystyrene-reduced weight average molecular weight is 300,000 to
800,000, preferably 300,000 to 600,000.
[0048]Further, capable of being used for the 1,4-cis-polybutadiene (a) is
cis-polybutadiene alone synthesized using a cobalt catalyst such as a
soluble cobalt compound and the like, a nickel catalyst such as organic
carboxylic acid salts of nickel and the like, an organic lithium
compound, an organic carboxylic acid salt of neodymium or a lanthanoid
catalyst such as organic complex salts and the like, or cis-polybutadiene
obtained by blending two or more kinds of the above cis-polybutadienes.
When the above 1,4-cis-polybutadiene is used, the hydrocarbon base
solvent used, the conditions of controlling the moisture concentration,
the 1,2-polymerization conditions and the like are the same as described
above. A concentration of the 1,4-cis-polybutadiene (a) in the mixture
controlled in a moisture concentration which comprises 1,3-butadiene and
the hydrocarbon base organic solvent as principal components is
preferably 1 to 30 mass %.
[0049]The polymerization reaction mixture containing 1,4-cis-polybutadiene
which is obtained in the step (1) described above is subjected to
comprising an organic aluminum compound represented preferably by a
formula AlR3 (wherein R is an alkyl group having 1 to 6 carbon
atoms, a phenyl group or a cycloalkyl group) and carbon disulfide and, if
necessary, a catalyst comprising the soluble cobalt compound described
above and in the presence of an unsaturated high molecular compound
comprising at least one selected from polyisoprene, crystalline
polybutadiene having a melting point of 150° C. or lower, liquid
polybutadiene and derivatives thereof after further adding 1,3-butadiene
to the above polymerization reaction mixture or without adding
1,3-butadiene thereto to produce the 1,2-polybutadiene crystalline fibers
(b) having a melting point of 170° C. or higher.
[0050]In the above case, the vinyl/cis-polybutadiene rubber (A-1) in which
1 to 40 mass % of the 1,2-polybutadiene crystalline fibers (b) having a
melting point of 170° C. or higher and 0.1 to 30 mass % of the
unsaturated high molecular compound (c) are dispersed in a matrix
comprising the 1,4-cis-polybutadiene (a) can be produced by adding the
unsaturated high molecular compound to the reaction system before
starting the 1,2-polymerization and then carrying out the polymerization
Unsaturated High Molecular Compound
[0051]The unsaturated high molecular compound used in the first embodiment
of the present invention is at least one selected from polyisoprene,
liquid polybutadiene, crystalline polybutadiene having a melting point of
150° C. or lower and derivatives thereof, and it is a high
molecular substance having at least one unsaturated double bond per a
repetitive unit.
[0052]The polyisoprene includes ordinary synthesized polyisoprene
(cis-1,4-polyisoprene having a cis structure of 90 mol % or more and the
like), liquid polyisoprene, trans-polyisoprene, other modified
polyisoprenes and the like.
[0053]The liquid polybutadiene includes polybutadiene of a very low
molecular weight having an intrinsic viscosity [η] of 1 or less. The
crystalline polybutadiene having a melting point of lower than
170° C. is preferably crystalline polybutadiene having a melting
point of 0 to 150° C., and it includes, for example,
1,2-polybutadiene having a low melting point, trans-polybutadiene and the
[0054]The derivatives thereof include, for example, isoprene/isobutylene
copolymers, isoprene/styrene copolymers, styrene/isoprene/styrene block
copolymers, liquid epoxidized polybutadiene, carboxy group-modified
liquid polybutadiene, hydrogenated derivatives thereof and the like.
[0055]Among them, polyisoprene, the styrene/isoprene/styrene block
copolymers and 1,2-polybutadiene having a melting point of 70 to
110° C. are particularly preferred.
[0056]The unsaturated high molecular compound can be used alone or in
[0057]If the unsaturated high molecular compound is added in the manner
described above, a dispersibility of the 1,2-polybutadiene crystalline
fibers (b) into the 1,4-cis-polybutadiene (a) which is the matrix
component is notably improved in the vinyl/cis-polybutadiene rubber (A-1)
due to a compatibility effect of the unsaturated high molecular compound,
and as a result thereof, the vinyl/cis-polybutadiene rubber (A-1)
obtained is provided with excellent characteristics.
[0058]An addition amount of the unsaturated high molecular compound is
preferably 0.1 to 30 mass %, more preferably 1 to 20 mass % based on the
vinyl/cis-polybutadiene rubber (A-1) obtained. In adding at any point of
time, stirring is carried out preferably for 10 minutes to 3 hours, more
preferably 10 to 30 minutes after added.
[0059]The organic aluminum compound represented by the formula AlR3
described above which is one component of the catalyst used in the step
(2) includes trimethylaluminum, triethylaluminum, triisobutylaluminum,
tri-n-hexylaluminum, triphenylaluminum, tricyclohexylaluminum and the
[0060]A use amount of the organic aluminum compound is preferably 0.1
of 1,3-butadiene.
[0061]Carbon disulfide shall not specifically be restricted and does not
preferably contain moisture. A concentration of carbon disulfide is
preferably 20 millimole/L or less, particularly preferably 0.01 to 10
millimole/L. Publicly known phenyl isothiocyanate and xanthogenic acid
compounds can be used as an alternative for carbon disulfide.
[0062]Further, organic carboxylic acid salts of nickel, organic complex
salts of nickel, organic lithium compounds, organic carboxylic acid salts
of neodymium and organic complex salts of neodymium can be used in
combination as one component of the catalyst.
[0063]The reaction temperature for carrying out the 1,2-polymerization is
preferably -5 to 100° C., particularly preferably -5 to 50°
C. A yield of 1,2-polybutadiene in carrying out the 1,2-polymerization
can be increased by adding 1,3-butadiene to the polymerization reaction
system in an amount of 1 to 50 mass parts, preferably 1 to 20 mass parts
per 100 mass parts of the cis-1,4-polymerization reaction mixture
described above. The polymerization time (average residence time) is
preferably 10 minutes to 2 hours.
[0064]The 1,2-polymerization is preferably carried out so that the polymer
concentration after the polymerization is 9 to 29 mass %.
[0065]A single bath or a bath obtained by connecting two or more baths can
polymerization reaction system is further increased in a viscosity during
the 1,2-polymerization, and therefore the polymerization can be carried
out by stirring and mixing the polymerization solution using a
polymerization bath equipped with a high viscous liquid stirring device,
for example, an equipment described in Japanese Patent Publication No.
2645/1965.
[0066]A publicly known antioxidant (described later) can be added
according to an ordinary method after the 1,2-polymerization reaction
reaches a prescribed polymerization rate. An addition amount of the
antioxidant is preferably 0.001 to 5 mass parts per 100 mass parts of the
vinyl/cis-polybutadiene rubber (A-1).
[0067]Next, a polymerization terminating agent is added to the
polymerization reaction system to terminate the polymerization. The
termination can be carried out, for example, by a publicly known method
such as a method in which a polar solvent including alcohol such as
methanol, ethanol and the like or water is added to the polymerization
reaction solution after the polymerization reaction is finished and a
method in which an inorganic acid such as hydrochloric acid, sulfuric
acid and the like, an organic acid such as acetic acid, benzoic acid and
the like or hydrogen chloride gas is added to the polymerization reaction
solution. Then, the vinyl/cis-polybutadiene rubber (A-1) produced is
separated, washed and dried by conventional methods.
[0068]1,3-Butadiene, the hydrocarbon base organic solvent and the like can
be separated and recovered from a mixture containing unreacted
1,3-butadiene, the hydrocarbon base organic solvent and, in a certain
case, carbon disulfide in a remnant left after separating and obtaining
the vinyl/cis-polybutadiene rubber (A-1) by distilling, adsorption
separating treatment and the like.
[0069]According to the above method, the catalyst components are provided
with an excellent operability, and the vinyl/cis-polybutadiene rubber
(A-1) can be produced industrially advantageously at a high catalyst
efficiency. In particular, the rubber component is not adhered onto an
inner wall of the polymerization bath, the stirring blades and other
parts in which stirring is slow, and continuous production can be carried
out industrially advantageously at a high conversion rate over a long
[0070]The vinyl/cis-polybutadiene rubber (A-1) has a Mooney viscosity
(ML1+4, 100° C.) of preferably 20 to 150, more preferably 30 to
100 and particularly preferably 30 to 80.
[0071]The vinyl/cis-polybutadiene rubber (A-1) thus obtained has a
structure in which 1 to 40 mass % of the 1,2-polybutadiene crystalline
fibers (b) having a melting point of 170° C. or higher and 0.1 to
30 mass %, preferably 1 to 20 mass % of the unsaturated high molecular
compound are dispersed in an adsorbed state in the matrix comprising the
1,4-cis-polybutadiene (a) having a 1,4-cis structure content of 80 mol %
or more. A boiling n-hexane-insoluble part of the vinyl/cis-polybutadiene
rubber (A-1) is a part or all of the 1,2-polybutadiene crystalline fibers
(b) and the unsaturated high molecular compound, and an adsorption rate
(graft rate) of the unsaturated high molecular compound onto the
1,2-polybutadiene crystalline fibers (b) can be calculated by an infrared
absorption spectral analysis. The above adsorption rate (graft rate) is
preferably 5 to 200 mass %, more preferably 10 to 120 mass %, further
preferably 20 to 90 mass % and particularly preferably 30 to 80 mass %.
[0072]The boiling n-hexane-insoluble part is a value obtained by boiling
and extracting 2 g of the vinyl/cis-polybutadiene rubber (A-1) in 200 ml
of n-hexane for 4 hours by a Soxhlet method and showing the extract
remnant by mass %.
[0073]A dispersion mode of the 1,2-polybutadiene (b-1) and the unsaturated
high molecular compound in the vinyl/cis-polybutadiene rubber (A-1)
includes, in observation under a transmission type electron microscope, a
mode in which the crystalline fibers of the 1,2-polybutadiene (b-1) and
the fine particles of the unsaturated high molecular compound each are
dispersed separately in the matrix comprising the 1,4-cis-polybutadiene
(a), a mode in which they are dispersed in the state that the fine
particles of the unsaturated high molecular compound are adhered onto the
1,2-polybutadiene crystalline fibers (b), a mode in which they are
dispersed in the state that the 1,2-polybutadiene crystalline fibers (b)
are adhered onto the fine particles of the unsaturated high molecular
compound, a mode in which they are dispersed in the state that the
1,2-polybutadiene crystalline fibers (b) are included and dispersed in
the fine particles of the unsaturated high molecular compound and a mode
in which the modes described above are present in a mixture.
[0074]In the 1,2-polybutadiene crystalline fibers (b), the crystalline
aspect ratio of 10 or less; the number of the crystalline fibers having
an average fiber length of 200 nm or less is 90 fibers or more per 25
μm2; and the melting point is 170° C. or higher.
[0075]An average fiber length of the 1,2-polybutadiene crystalline fibers
(b) in a monodispersion state is preferably 180 nm or less, more
preferably 160 nm or less and particularly preferably 10 to 150 nm.
[0076]A thickness (diameter) of the 1,2-polybutadiene crystalline fibers
(b) is preferably 100 nm or less, and an average aspect ratio
(length/diameter) thereof is preferably 10 or less, more preferably 4 or
less, further preferably 3 to 0.5 and particularly preferably 3 to 1.
[0077]In observation under a transmission type electron microscope, the
number of the crystalline fibers having a fiber length of 200 nm or less
is preferably 95 fibers or more per 25 μm2, more preferably 100
to 200 fibers per 25 μm2, and they have preferably a short fiber
[0078]The 1,2-polybutadiene crystalline fibers (b) has a melting point of
preferably 190 to 220° C., and the molecular weight index
(ηsp/c) described above is preferably 0.5 to 4, more preferably
Diene Base Rubber (B-1)
[0079]The diene base rubber (B-1) other than the (A-1) component includes
natural rubber (NR), polyisoprene rubber (IR), high cis-polybutadiene
rubber (high cis-BR), low cis-polybutadiene rubber (low cis-BR),
1,2-polybutadiene (1,2-BR), emulsion-polymerized or solution-polymerized
styrene butadiene rubber (SBR), ethylene-propylene-diene rubber (EPDM),
nitrile rubber (NBR), butyl rubber (IIR), chloroprene rubber (CR) and the
like. Further, capable of being used as well are derivatives of the above
rubbers, for example, polybutadiene rubbers modified with tin compounds
and rubbers obtained by modifying the rubbers described above with epoxy,
silane and maleic acid.
[0080]Among them, natural rubber and/or polyisoprene rubber are
[0081]The above diene base rubbers (B) can be used alone or in combination
Thermoplastic Polymer (C)
[0082]The thermoplastic polymer (C) includes styrene base resins, ABS
resins, AES resins, AAS resins, styrene base thermoplastic elastomers,
ethylene-vinyl acetate copolymers, 1,2-polybutadiene resins and the like.
[0083]Among them, preferred are polystyrene, styrene-butadiene copolymers,
acrylonitrile-styrene copolymers, styrene-butadiene-styrene block
copolymers (SBS), styrene-isoprene-styrene block copolymers (SIS),
styrene-ethylene-butylene-styrene block copolymers (SEBS), ethylene-vinyl
acetate copolymers and 1,2-polybutadiene resins. Among them, particularly
preferred is at least one selected from the styrene-butadiene copolymers
having a styrene unit content of 30 to 90 mass %, preferably 35 to 80
mass %, the ethylene-vinyl acetate copolymers having a vinyl acetate unit
content of 5 to 30 mass %, preferably 10 to 25 mass % and the
1,2-polybutadiene resins having a melting point of 70 to 150° C.
The above thermoplastic polymer (C) added in a suitable amount makes it
possible to provide the rubber composition with a suitable hardness and a
suitable impact resistance.
Rubber Reinforcing Material (D)
[0084]The rubber reinforcing material (D) includes inorganic reinforcing
materials such as silica, carbon black, activated calcium carbonate,
ultrafine particle magnesium silicate and the like and organic
reinforcing materials such as polyolefin resins including polyethylene
resins, polypropylene resins and the like, phenol resins, lignin,
modified melamine resins, coumarone indene resins and petroleum resins.
[0085]Among them, silica and/or carbon black are preferred. Among them,
preferred are silicas having an average primary particle diameter of 5 to
100 nm such as silicic anhydride prepared by a dry method, silicic acid
hydrate prepared by a wet method, synthesized silicates and the like and
carbon blacks having a particle diameter of 90 nm or less and a dibutyl
phthalate (DBP) absorption of 70 ml/100 g or more. The carbon black
includes furnace black, channel black, thermal black and the like, and to
be specific, it includes ASTM code No. N110, S212, N242, S315, N330,
N550, N660, N765 and the like.
[0086]In the rubber composition for shoe soles according to the present
invention, 100 mass parts of the polymer component comprising 10 to 90
mass %, preferably 20 to 80 mass % of the vinyl/cis-polybutadiene rubber
(A-1), 10 to 50 mass %, preferably 10 to 40 mass % of the diene base
rubber (B) other than the component (A-1) and 2 to 50 mass %, preferably
5 to 40 mass % of the thermoplastic polymer (C) is blended with 2 to 50
mass parts, preferably 5 to 40 mass % of the rubber reinforcing material
[0087]If the blend proportions of the respective components described
above fall in the ranges described above, capable of being prepared is
the rubber composition for shoe soles which is lightweight and has an
appropriate hardness and which is excellent in a tear strength, an
abrasion resistance and a gripping property, and the problem that a
viscosity of the composition is too large and makes kneading difficult to
deteriorate the molding property is not brought about.
[0088]A vulcanizing agent and a vulcanization accelerating agent can be
added to the composition of the present invention.
[0089]The vulcanizing agent includes sulfur, compounds which produce
sulfur by heating, organic peroxides, metal oxides such as magnesium
oxide and the like, multifunctional monomers, silanol compounds and the
like. The compounds which produce sulfur by heating include
tetramethylthiuram disulfide, tetraethylthiuram disulfide and the like.
[0090]The vulcanization accelerating agent includes, for example,
aldehydes, ammonias, amines, guanidines, thioureas, thiazoles, thiurams,
dithiocarbamates, xanthates and the like and to be more specific, it
includes tetramethylthiuram disulfide (TMTD),
N-oxydiethylene-2-benzothiazolylsulfenamide (OBS),
N-cyclohexyl-2-benzothiazylsulfenamide (CBS), dibenzothiazyl disulfide
(MBTS), 2-mercaptobenzothiazole (MBT), zinc di-n-butyldithiocarbamate
(ZnBDC), zinc dimethyldithiocarbamate (ZnMDC) and the like.
[0091]In addition to the above compounds, publicly known additives which
are usually used for rubber compositions such as antioxidants, fillers,
process oils, zinc oxide, stearic acid and the like can be used if
[0092]The antioxidants include amine/ketone base antioxidants, imidazole
base antioxidants, amine base antioxidants, phenol base antioxidants,
sulfur base antioxidants, phosphorus base antioxidants and the like. To
be more specific, the antioxidants include 2,6-di-t-butyl-p-cresol (BHT)
of a phenol base, trinonylphenyl phosphite (TNP) of a phosphorus base,
4,6-bis(octylthiomethyl)-o-cresol and dilauryl-3,3'-thiodipropionate
(TPL) of a sulfur base and the like.
[0093]The fillers include inorganic fillers such as calcium carbonate,
basic magnesium carbonate, clay, litharge, diatomaceous earth and the
like and organic fillers such as regenerated rubbers, powder rubbers and
the like, and the process oils include process oils of an aromatic base,
a naphthene base and a paraffin base.
[0094]The composition of the present invention can be obtained by kneading
the respective components described above by means of a Banbury mixer, an
open roll, a kneader, a double shaft kneading machine and the like which
are usually used. The kneading temperature has to be lower than a melting
point of the 1,2-polybutadiene crystalline fibers contained in the above
vinyl/cis-polybutadiene. If the composition is kneaded at a higher
temperature than a melting point of the 1,2-polybutadiene crystalline
fibers, fine short fibers contained in the vinyl/cis-polybutadiene are
molten and transformed into spherical particles and the like, and
therefore it is not preferred.
Rubber Composition for Shoe Soles According to the Second Embodiment
[0095]In the second embodiment of the present invention, the
soles described above is a vinyl/cis-polybutadiene rubber (A-2) obtained
(1) adding a catalyst comprising an organic aluminum compound and a
soluble cobalt compound to a mixture comprising 1,3-butadiene and a
hydrocarbon base solvent having a solubility parameter (SP value) of 9.0
or less as principal components to subject 1,3-butadiene to
cis-1,4-polymerization to thereby produce 1,4-cis-polybutadiene (a),
wherein an organic aluminum compound represented by a formula
AlRnX3-n (wherein R is an alkyl group having 1 to 6 carbon
atoms, a phenyl group or a cycloalkyl group; X is a halogen element; and
n is a number of 1.5 to 2) is used as the organic aluminum compound
and(2) then subjecting the polymerization reaction mixture thus obtained
to 1,2-polymerization with 1,3-butadiene in the presence of a catalyst
170° C. or higher.
Vinyl/Cis-Polybutadiene Rubber (A-2)
[0096]The vinyl/cis-polybutadiene rubber (A-2) used in the second
embodiment of the present invention comprises the 1,4-cis-polybutadiene
(a) and the specific 1,2-polybutadiene crystalline fibers (b).
[0097]The 1,2-polybutadiene crystalline fibers (b) in the
vinyl/cis-polybutadiene rubber (A-2) are partially dispersed in a form in
which they are monodispersed as fine crystals in the cis-polybutadiene
(a) as a matrix of the vinyl/cis-polybutadiene rubber (A-2), and they are
coexistent with large crystalline fibers having an aggregation structure.
The above monodispersed fine crystalline short fibers enhance an
interfacial affinity with the matrix rubber components.
[0098]The vinyl/cis-polybutadiene rubber (A-2) has a Mooney viscosity of
20 to 150, preferably 30 to 80, and a content of the 1,2-polybutadiene
crystalline fibers (b) is 1 to 40 mass parts, preferably 1 to 30 mass
parts. If they fall in the ranges described above, the crystalline short
fibers of the 1,2-polybutadiene crystalline fibers (b) in the
1,4-cis-polybutadiene (a) do not grow large, and the high elastic modulus
can be developed. In addition thereto, the problem that the
processability is deteriorated is not brought about.
[0099]The 1,4-cis-polybutadiene (a) is preferably the same as described in
the first embodiment from the viewpoint of the processability, the
abrasion resistance and the like, and the values thereof fall preferably
in the suited ranges since a balance between various physical properties
such as the high elastic modulus, the excellent processability and the
like can be held.
[0100]The 1,2-polybutadiene crystalline fibers (b) also are preferably the
same as described in the first embodiment. Almost all part of
conventional vinyl/cis-polybutadiene rubbers comprises crystalline fibers
having a large aggregation structure, and the number of the crystalline
fibers having a fiber length of 200 nm or less is 70 fibers or less per
25 μm2.
[0101]The vinyl/cis-polybutadiene rubber (A-2) described above can
suitably be obtained, for example, by the following production process.
[0102]First, 1,3-butadiene is mixed with a hydrocarbon base solvent having
a solubility parameter (SP value) of 9.0 or less, preferably 8.5 or less
to subject 1,3-butadiene to cis-1,4-polymerization.
[0103]Use of the solvent having an SP value smaller than 9.0 improves the
dispersion of the 1,2-polybutadiene crystalline fibers (b) into the
1,4-cis-polybutadiene (a) and makes it possible to develop the excellent
tear strength and the excellent abrasion resistance. On the other hand,
if a solvent having an SP value exceeding 9.0 is used, it is difficult to
form a dispersion state of the 1,2-polybutadiene crystalline fibers (b)
into the 1,4-cis-polybutadiene (a) as is the case with the present
invention. Accordingly, a balance between various physical properties
like is broken in a certain case, and it is not necessarily preferred.
[0104]The solvent having an SP value of 9.0 or less includes, for example,
n-hexane (SP value: 7.2), n-pentane (SP value: 7.0), n-octane (SP value:
7.5), cyclohexane (SP value: 8.1), n-butane (SP value: 6.6) and the like.
Among them, cyclohexane and n-hexane are particularly preferred.
[0105]The solubility parameter (SP value) is shown by a square root
((cal/cm3)1/2) of evaporation heat required for evaporating a
liquid of 1 molar volume, and it is publicly known by documents such as
Rubber Industry Handbook (4th edition, edited by the Society of Rubber
Industry, Japan on Jan. 20, 1994, p. 720 to 721) and the like. The above
hydrocarbon base solvents can be used alone or in combination of two or
more kinds thereof, and a solvent obtained by combining two or more kinds
of the solvents can be provided with an SP value of 9.0 or less.
[0106]The mixture comprising 1,3-butadiene and the hydrocarbon base
solvent described above as principal components which is obtained by
mixing both components is preferably controlled, as described in the
first embodiment, in a concentration of moisture contained in the mixed
medium before brought into contact with the halogen-containing organic
aluminum compound which is the catalyst component.
[0107]The moisture falls in a range of preferably 0.1 to 1.0 mole,
particularly preferably 0.2 to 1.0 mole per mole of the organic aluminum
halogen compound (for example, organic aluminum chloride) which is the
catalyst component in the mixed medium described above.
[0108]The moisture falling in the above range makes it possible to
effectively control a reduction in the catalyst activity, a reduction in
the cis-1,4 structure content, an abnormal variation in the molecular
weight, gel produced in the polymerization and the like, and no gel is
adhered onto the polymerization bath, so that the continuous
polymerization time can be extended.
[0109]The organic aluminum halogen compound is added to the solution
obtained after controlling a concentration of moisture.
[0110]The organic aluminum halogen compound includes a compound
represented by a formula AlRnX3-n (wherein R is an alkyl group
having 1 to 6 carbon atoms, a phenyl group or a cycloalkyl group; X is a
halogen element; and n is a number of 1 to 2). The specific examples of
the organic aluminum halogen compound and a use amount thereof are the
same as those of the organic aluminum halogen compound (II) described in
[0111]Next, a soluble cobalt compound is added to the mixed medium to
which organic aluminum chloride is added, and cis-1,4-polymerization is
carried out. The soluble cobalt compound is preferably a compound which
is soluble or can homogeneously be dispersed in an inactive medium
comprising a hydrocarbon base solvent having an SP value of 8.5 or less
as a principal component or liquid 1,3-butadiene. The soluble cobalt
compound and a use amount thereof are the same as described in the first
[0112]Further, organic carboxylic acid salts of nickel, organic complex
of neodymium and organic complex salts of neodymium can be used as well
in addition to the soluble cobalt compound.
[0113]The reaction conditions for carrying out the cis-1,4-polymerization,
the polymerization bath and a molecular weight controlling agent and a
gelation inhibitor which can be used are the same as described in the
[0114]The 1,4-cis-polybutadiene (a) thus obtained has the same cis-1,4
structure content, Mooney viscosity (ML1+4, 100° C.) and the like
as described in the first embodiment, and it does not substantially
contain a toluene-insoluble part (gel).
[0115]An organic aluminum compound represented by a formula AlR3
(wherein R is the same as described above) and carbon disulfide and, if
necessary, the soluble cobalt compound described above are added after
adding 1,3-butadiene to the polymerization reaction mixture obtained in
the manner described above or without adding 1,3-butadiene to subject the
above polymerization reaction mixture to 1,2-polymerization with
1,3-butadiene, whereby a vinyl/cis-polybutadiene rubber (A-2) in which 1
to 40 mass % of the 1,2-polybutadiene crystalline fibers (b) having a
melting point of 170° C. or higher are dispersed in a matrix
comprising the 1,4-cis-polybutadiene (a) can be produced.
[0116]The organic aluminum compound represented by the formula AlR3
and a use amount thereof are the same as described in the first
[0117]Carbon disulfide which can be used in combination with the organic
aluminum compound shall not specifically be restricted and does not
preferably 20 mmol/L or less, particularly preferably 0.01 to 10 mmol/L.
Publicly known phenyl isothiocyanate and xanthogenic acid compounds may
be used as an alternative for carbon disulfide.
[0118]A temperature at which 1,3-butadiene is subjected to
1,2-polymerization is preferably 100° C. or lower, more preferably
-5 to 80° C. and particularly preferably -5 to 50° C.
[0119]A yield of the 1,2-polybutadiene in the 1,2-polymerization can be
increased by adding 1,3-butadiene to the polymerization reaction system
in carrying out the 1,2-polymerization in an amount of 1 to 50 mass
parts, preferably 1 to 20 mass parts per 100 mass parts of the cis
polymerization liquid described above.
[0120]The polymerization time (average residence time) falls in a range of
preferably 10 minutes to 2 hours. The 1,2-polymerization is preferably
carried out so that the polymer concentration after the
1,2-polymerization is 9 to 29 mass %. A single bath or a bath obtained by
connecting two or more baths can be used for the polymerization bath. The
polymerization is carried out by stirring and mixing the polymerization
solution in the polymerization bath (polymerization vessel). The
polymerization solution is further increased in a viscosity during the
1,2-polymerization, and the polymer is liable to be adhered, so that a
polymerization bath equipped with a high viscosity liquid stirring
device, for example, an equipment described in Japanese Patent
Publication No. 2645/1965 can be used as the polymerization bath used for
the 1,2-polymerization.
[0121]A publicly known antioxidant can be added according to an ordinary
method after the polymerization reaction reaches a prescribed
polymerization rate. The usable antioxidants are the same as described in
the first embodiment. An addition amount of the antioxidant is 0.001 to 5
mass parts per 100 mass parts of the vinyl/cis-polybutadiene rubber.
[0122]Next, a polymerization terminating agent is added to the
polymerization system to terminate the polymerization. The termination
can be carried out, for example, by a publicly known method such as a
method in which a polymerization reaction solution is supplied to a
polymerization terminating bath after the polymerization reaction is
finished and in which a large amount of a polar solvent such as alcohol
including methanol, ethanol and the like or water is added to the above
polymerization reaction solution and a method in which an inorganic acid
such as hydrochloric acid, sulfuric acid and the like, an organic acid
such as acetic acid, benzoic acid and the like or hydrogen chloride gas
is introduced into a polymerization solution. Then, the
vinyl/cis-polybutadiene rubber (A-2) produced is obtained by separating,
washing and drying by conventional methods.
[0123]1,3-Butadiene and the inactive medium are separated by distillation
from a mixture containing unreacted 1,3-butadiene, the inactive medium
and carbon disulfide in a remnant left after separating and obtaining the
vinyl/cis-polybutadiene rubber (A-2). On the other hand, carbon disulfide
is separated and removed by adsorption separating treatment of carbon
disulfide or separating treatment of a carbon disulfide adduct to recover
1,3-butadiene and the inactive medium which do not substantially contain
[0124]Further, 1,3-butadiene and the inactive medium which do not
substantially contain carbon disulfide can be recovered as well by
recovering three components from the mixture described above by
distillation and separating and removing carbon disulfide from this
distillate by the adsorption separating treatment of carbon disulfide or
the separating treatment of a carbon disulfide adduct each described
above. The carbon disulfide and the inactive medium recovered in the
manner described above are used after mixing 1,3-butadiene newly
[0125]Continuous production carried out according to the above method
provides the catalyst components with an excellent operability and makes
it possible to continuously produce the vinyl/cis-polybutadiene rubber
(A-2) industrially advantageously at a high catalyst efficiency. In
particular, the rubber component is not adhered onto an inner wall of the
polymerization bath, the stirring blades and other parts in which
stirring is slow, and the continuous production can be carried out
industrially advantageously at a high conversion rate.
[0126]However, the polymerization process shall not specifically be
restricted, and the production can be carried out by either continuous
polymerization or batch polymerization.
[0127]In the rubber composition for shoe soles according to the second
embodiment of the present invention, the vinyl/cis-polybutadiene rubber
(A-2) is used in place of the vinyl/cis-polybutadiene rubber (A-1) in the
rubber composition for shoe soles according to the first embodiment. The
diene base rubber (B) other than the component (A-2), the thermoplastic
polymer (C), the rubber reinforcing material (D) and a vulcanizing agent,
a vulcanization accelerating agent, an antioxidant, a filler, a process
oil, zinc oxide, stearic acid and the like which are optional components
are the same as described in the first embodiment.
[0128]If the blend proportions of the respective components described
appropriate hardness and which is excellent in a tensile strength, a tear
strength, an abrasion resistance and a gripping property, and the
problems that a viscosity of the composition is too large to make
kneading difficult and that the molding property is deteriorated are not
Rubber Composition for Shoe Soles According to the Third Embodiment
[0129]In the third embodiment of the present invention, the
soles described above is a vinyl/cis-polybutadiene rubber (A-3) obtained
hydrocarbon base solvent as principal components to subject 1,3-butadiene
to cis-1,4-polymerization to thereby produce 1,4-cis-polybutadiene
(a),(2) subjecting the polymerization reaction mixture thus obtained to
170° C. or higher and(3) thereby obtaining vinyl/cis-polybutadiene
Vinyl/Cis-Polybutadiene Rubber (A-3)
[0130]The vinyl/cis-polybutadiene rubber (A-3) used in the third
embodiment of the present invention is produced through the step
described above, whereby it is provided with excellent mechanical
[0131]First, 1,3-butadiene is mixed with a hydrocarbon base solvent to
subject 1,3-butadiene to cis-1,4-polymerization.
[0132]The hydrocarbon base solvent is the same as described in the first
[0133]The mixture comprising 1,3-butadiene and the hydrocarbon base
components is preferably controlled, as described in the first
embodiment, in a concentration of moisture contained in the mixture
before brought into contact with the organic aluminum compound which is
the catalyst component.
[0134]Controlling of the moisture concentration, the organic aluminum
compound which can be used, the soluble cobalt compound and the use
amounts thereof are the same as described in the first embodiment.
[0135]The organic carboxylic acid salts of nickel, the organic complex
salts of nickel, the organic lithium compounds, the organic carboxylic
acid salts of neodymium and the organic complex salts of neodymium each
described above can be used as well in combination as one component of
[0136]The reaction conditions for carrying out the cis-1,4-polymerization,
the polymerization bath and the molecular weight controlling agent and
the gelation inhibitor which can be used are the same as described in the
[0137]The 1,4-cis-polybutadiene (a) obtained above has the same cis-1,4
as described in the first embodiment. The 5 mass % toluene solution has a
viscosity of preferably 30 to 250 centipoise (cp), more preferably 50 to
200 cp and particularly preferably 100 to 200 cp from the viewpoint of
the strength, the abrasion resistance and the like, and a
toluene-insoluble part (gel) is not substantially contained.
[0138]Then, the catalyst comprising the organic aluminum compound
disulfide and, if necessary, the soluble cobalt compound described above
are added after adding 1,3-butadiene to the polymerization reaction
mixture containing the cis-1,4-polymer described above or without adding
1,3-butadiene thereto to subject the above polymerization reaction
mixture to 1,2-polymerization with 1,3-butadiene, whereby the
vinyl/cis-polybutadiene rubber (A-4) in which the 1,2-polybutadiene
crystalline fibers (b) having a melting point of 170° C. or higher
are dispersed in a matrix comprising the 1,4-cis-polybutadiene (a) can be
[0139]The organic aluminum compound represented by a formula AlR3,
carbon disulfide, the alternative for carbon disulfide and the use
[0140]The reaction conditions for carrying out the 1,2-polymerization and
the polymerization bath also are the same as described in the first
[0141]When producing the vinyl/cis-polybutadiene (A-4), a step in which an
unsaturated high molecular compound is added to the mixture comprising
1,3-butadiene and the hydrocarbon base solvent as principal components
and stirred to dissolve it can be added before the cis-1,4-polymerization
or the 1,2-polymerization.
[0142]The unsaturated high molecular compound is the same as described in
the first embodiment. In particular, polyisoprene,
styrene/isoprene/styrene block copolymers and 1,2-polybutadiene having a
melting point of 70 to 110° C. are preferred.
[0143]An addition amount of the unsaturated high molecular compound is
vinyl/cis-polybutadiene rubber (A-3) obtained.
[0144]The publicly known antioxidant described above can be added by a
conventional method after the 1,2-polymerization reaction reaches a
prescribed polymerization rate. An addition amount of the antioxidant is
0.001 to 5 mass parts per 100 mass parts of the vinyl/cis-polybutadiene
rubber (A-4).
[0145]Next, a polymerization terminating agent is added, as described in
the first embodiment, to the polymerization reaction system to terminate
the polymerization. Then, the vinyl/cis-polybutadiene rubber (A-4)
produced is obtained by separating, washing and drying by conventional
methods, and unreacted 1,3-butadiene, the hydrocarbon base organic
solvent and, in certain case, carbon disulfide in the remnant can be
recovered by distilling, adsorbing and separating treatments.
[0146]According to the above method, and the vinyl/cis-polybutadiene
rubber (A-4) can be produced industrially advantageously at a high
catalyst efficiency with an excellent operability of the catalyst
components. In particular, the rubber component is not adhered onto an
out industrially advantageously at a high conversion rate.
[0147]A proportion of a boiling n-hexane-insoluble part (1,2-polybutadiene
crystalline fibers (b)) of the vinyl/cis-polybutadiene rubber (A-4) thus
obtained is preferably 10 to 60 mass %, more preferably 20 to 50 mass %
and particularly preferably 20 to 40 mass % from the viewpoint of the
productivity. The boiling n-hexane-insoluble part comprises syndiotactic
1,2-polybutadiene and is a value obtained by boiling and extracting 2 g
of the vinyl/cis-polybutadiene rubber in 200 ml of n-hexane for 4 hours
by a Soxhlet extractor and showing the extract remnant by mass part.
[0148]On the other hand, in the boiling n-hexane-soluble part
(1,4-cis-polybutadiene (a)) of the vinyl/cis-polybutadiene rubber (A-4),
a micro structure thereof comprises the 1,4-cis-polybutadiene having a
1,4-cis structure content of preferably 80 mol % or more, more preferably
90 mol % or more.
[0149]In the step (3), the vinyl/cis-polybutadiene (A-4) in which the
1,2-polybutadiene crystalline fibers (b) are dispersed in a matrix
comprising the cis-polybutadiene (a) is solution-mixed with the
1,4-cis-polybutadiene (a-4) to produce the vinyl/cis-polybutadiene rubber
(A-3). A mass ratio (vinyl/cis-polybutadiene (A-4)/1,4-cis-polybutadiene
(a-4)) of the vinyl/cis-polybutadiene (A-4) to the 1,4-cis-polybutadiene
(a-4) is preferably 10 to 50/90 to 50.
[0150]The 1,4-cis-polybutadiene (a-4) can be produced by adding a
cis-1,4-polymerization catalyst to subject 1,3-butadiene to
cis-1,4-polymerization in the same manner as in the precedent step in the
production process for the vinyl/cis-polybutadiene (A-4). Also, the
cis-polybutadiene solution obtained in the precedent step in the
production process for the vinyl/cis-polybutadiene (A-4) may be used as
it is. Further, cis-polybutadiene obtained by using a catalyst other than
the catalyst (the catalyst comprising the organic aluminum compound and
the soluble cobalt compound) used in the step (1) can be used as well.
[0151]The 1,4-cis-polybutadiene mixed in the step (3) has preferably a
smaller Mooney viscosity than that of the 1,4-cis-polybutadiene (a)
obtained in the step (1). That is, the 1,4-cis-polybutadiene (a) obtained
in the step (1) has a Mooney viscosity (ML1+4, 100° C.) of
preferably 10 to 130, more preferably 15 to 80, but the
1,4-cis-polybutadiene mixed in the step (3) has a Mooney viscosity
(ML1+4, 100° C.) which is smaller than a Mooney viscosity (ML1+4,
100° C.) of the 1,4-cis-polybutadiene (a) obtained in the step (1)
by preferably 5 or more, more preferably 10 or more and particularly
preferably 15 or more.
[0152]When using the above 1,4-cis-polybutadiene (a-4), the hydrocarbon
base solvent used, the controlling condition of the moisture
concentration, the 1,2-polymerization conditions and the like are the
same as described above. A concentration of the 1,4-cis-polybutadiene
(a-4) in the mixture controlled in a moisture concentration comprising
1,3-butadiene and the hydrocarbon base solvent as principal components is
[0153]The vinyl/cis-polybutadiene (A-3) obtained above comprises a
structure in which the 1,2-polybutadiene crystalline fibers (b) (boiling
n-hexane-insoluble part) are dispersed in a proportion of preferably 1 to
40 mass %, more preferably 1 to 30 mass % and particularly preferably 1
to 20 mass % in a matrix comprising the 1,4-cis-polybutadiene (a) having
a 1,4-cis structure content of 80 mol % or more obtained in the step (1)
and the 1,4-cis-polybutadiene (a-4) obtained in the step (3).
[0154]In the rubber composition for shoe soles according to the third
(A-3) is used in place of the vinyl/cis-polybutadiene rubber (A-1) in the
diene base rubber (B) other than the component (A-3), the thermoplastic
polymer (C), the rubber reinforcing material (D) and the vulcanizing
agent, the vulcanization accelerating agent, the antioxidant, the filler,
the process oil, zinc oxide, stearic acid and the like which are optional
components are the same as described in the first embodiment.
Rubber Foam Composition for Shoe Soles
[0155]The rubber foam composition for shoe soles according to the present
invention is obtained by foaming the rubber compositions for shoe soles
according to the first embodiment to the third embodiment of the present
invention. A production process for the foam shall not specifically be
restricted, and any of a chemical foaming method and a physical foaming
method can be employed.
[0156]Publicly known inorganic foaming agents and organic foaming agents
can be used for the foaming agent. They include, for example, sodium
bicarbonate, ammonium bicarbonate, sodium carbonate, ammonium carbonate,
azodicarbonamide (ADCA), dinitrosopentamethylenetetramine (DNPT),
p,p'-oxybisbenzenesulfonylhydrazine (OBSH), dinitrosoterephtalamide,
azobisisobutyronitrile, barium azodicarboxylate, sulfonylhydrazides such
as toluenesulfonylhydrazid and the like. Among them, azodicarbonamide
(ADCA), dinitrosopentamethylenetetramine (DNPT) and
p,p'-oxybisbenzenesulfonylhydrazine (OBSH) are preferred. The above
foaming agents may be used in combination with publicly known foaming
auxiliary agents such as urea, urea derivatives and the like.
[0157]An addition amount of the foaming agent is varied depending on the
kind of the polymers, and it is 0.5 to 20 mass parts, preferably 1 to 15
mass parts per 100 mass parts of the rubber composition. The foaming
auxiliary agent can be used in an amount of 10 to 200% of the foaming
[0158]The rubber foam composition for shoe soles according to the present
invention can be blended with publicly known additives which are usually
used for rubber foam compositions such as vulcanizing agents,
vulcanization accelerating agents, antioxidants, fillers, process oils,
zinc oxide, stearic acid and the like which are the same as described
[0159]The composition can be blended and molded by conventional methods.
Outsole for Shoes
[0160]The present invention provides as well outsoles for shoes
characterized by using the rubber compositions for shoe soles according
to the first embodiment to the third embodiment and the rubber foam
compositions for shoe soles obtained by foaming the above rubber
[0161]A shoe is constituted by an outsole, an upper, an insole and the
like. The outsole has to grip the ground in movements of landing and
kicking, and therefore the mechanical strength and the gripping property
are important. The rubber composition for shoe soles according to the
present invention and the rubber foam composition for shoe soles obtained
by foaming the above rubber composition have an appropriate hardness and
are excellent in a tensile strength, a tear strength, an abrasion
resistance and a gripping property, and therefore they are particularly
preferably used for outsoles.
[0162]Shoes to which they can be applied include men's shoes, ladies'
shoes and in addition thereto, sport shoes such as golf shoes, tennis
shoes, soccer shoes, jogging shoes, trekking shoes, town shoes and the
[0163]The outsole can be produced by a publicly known method using a
molding die equipped with an upper mold and a lower mold. For example, an
upper mold is moved down to a lower mold filled with the composition of
the present invention, pressed and heated, whereby the outsole can be
[0164]The present invention shall be explained in further details below
with reference to production examples, examples and comparative examples,
but the present invention shall not be restricted to them. In the
following examples, "%" and "parts" are "mass %" and "mass parts" unless
Production Example of the First Embodiment
Production of Vinyl/Cis-Polybutadiene Rubber (A-1):
[0165]A stainless-made reaction bath equipped with a stirrer having an
inner content of 5 L which was substituted with nitrogen gas was charged
with 3.5 L of a polymerization solution (1,3-butadiene: 30%, cyclohexane:
70%), and 5.3 mmol of water, 10.5 mmol of diethylaluminum chloride, 1.8
mmol of carbon disulfide, 32 mmol of cyclooctadiene and 0.03 mmol of
cobalt octoate were added thereto and stirred at 50° C. for 30
minutes to subject 1,3-butadiene to cis-1,4-polymerization, whereby
cis-polybutadiene (a-1) was produced.
[0166]Added to the polymerization product liquid obtained was 10 mass %
(percentage to the vinyl/cis-polybutadiene rubber obtained) of
polyisoprene (IR) (Mooney viscosity (ML1+4, 100° C.): 87, cis-1,4
structure content: 98 mol %), and the liquid was stirred at 50° C.
for one hour. Then, 560 ml of 1,3-butadiene, 4.5 mmol of water, 13.4 mmol
of triethylaluminum chloride and 0.07 mmol of cobalt octoate were added
thereto, and the liquid was stirred at 50° C. for 30 minutes to
produce 1,2-polybutadiene crystalline fibers (b-1). A methanol solution
of 4,6-bis(octylthiomethyl)-o-cresol as an antioxidant was added thereto,
and the polymerization was terminated. Then, unreacted butadiene and
2-butenes were removed by vaporization, and the residue was dried under
vacuum at 105° C. for 60 minutes to obtain a
vinyl/cis-polybutadiene rubber (A-1). An adsorption proportion (graft
rate) of polyisoprene onto the 1,2-polybutadiene crystalline fibers (b-1)
which was calculated from infrared absorption spectral analysis of a
boiling n-hexane-insoluble part of the vinyl/cis-polybutadiene rubber
(A-1) thus obtained was 67%. The physical properties thereof are shown in
Production Example of the Second Embodiment
Production of Vinyl/Cis-Polybutadiene Rubber (A-2):
[0167]A vinyl/cis-polybutadiene rubber (A-2) was obtained in the same
manner as in Production Example 1, except that in Production Example 1,
the polymerization solution was changed to (butadiene: 31%, 2-butenes:
29% and cyclohexane: 40%) and that the unsaturated high molecular
compound (polyisoprene) was not added. The physical properties thereof
are shown in Table I-1.
Production Example of the Third Embodiment
Production of Vinyl/Cis-Polybutadiene Rubber (A-3):
(i) Production of Vinyl/Cis-Polybutadiene (A-4):
[0168]A stainless-made reaction bath equipped with a stirrer having an
inner content of 1.5 L which was substituted with nitrogen gas was
charged with 1.0 L of a polymerization solution (1,3-butadiene: 31%,
2-butenes: 29% and cyclohexane: 40%), and 1.7 mmol of water, 2.9 mmol of
diethylaluminum chloride, 0.3 mmol of carbon disulfide, 6 mmol of
cyclooctadiene and 0.008 mmol of cobalt octoate were added thereto and
stirred at 40° C. for 20 minutes to subject 1,3-butadiene to
cis-1,4-polymerization, whereby 1,4-cis-polybutadiene (a-3) was produced.
Then, a small amount of the cis-polybutadiene polymerization liquid was
taken out from the reaction bath, and a viscosity of a toluene solution
of the cis-polybutadiene rubber obtained after drying the polymerization
liquid was measured to find that it was 175 cp.
[0169]Added to the polymerization product liquid obtained were 150 ml of
butadiene, 1.1 mmol of water, 3.5 mmol of triethylaluminum chloride and
0.02 mmol of cobalt octoate, and the liquid was stirred at 40° C.
for 20 minutes to subject butadiene to 1,2-polymerization, whereby
1,2-polybutadiene crystalline fibers (b-3) was produced. A methanol
solution of 4,6-bis(octylthiomethyl)-o-cresol as an antioxidant was added
thereto, and the polymerization was terminated. Then, unreacted butadiene
and 2-butenes were removed by vaporization to obtain a
vinyl/cis-polybutadiene (A-4) having a boiling n-hexane-insoluble part of
40.5%. The vinyl/cis-polybutadiene (A-4) 60 g was dissolved in
cyclohexane to prepare a vinyl/cis-polybutadiene solution.
(ii) Production of 1,4-Cis-Polybutadiene (a-4)
[0170]A stainless-made reaction bath equipped with a stirrer having an
with 3.5 L of a polymerization solution (1,3-butadiene: 31%, 2-butenes:
29% and cyclohexane: 40%), and 5.3 mmol of water, 10.5 mmol of
diethylaluminum chloride, 1.8 mmol of carbon disulfide, 32 mmol of
cyclooctadiene and 0.03 mmol of cobalt octoate were added thereto and
stirred at 50° C. for 30 minutes to subject 1,3-butadiene to
1,4-polymerization, whereby 1,4-cis-polybutadiene (a-4) was produced. A
methanol solution of 4,6-bis(octylthiomethyl)-o-cresol as an antioxidant
was added thereto, and the polymerization was terminated. Then, unreacted
butadiene and 2-butenes were removed by vaporization to obtain
1,4-cis-polybutadiene (a-4). The 1,4-cis-polybutadiene (a-4) 140 g was
dissolved in cyclohexane to prepare a 1,4-cis-polybutadiene
(a-4)/cyclohexane solution.
(iii) Production of Vinyl/Cis-Polybutadiene Rubber (A-3):
[0171]A stainless-made reaction bath equipped with a stirrer having an
inner content of 5.0 L which was substituted with nitrogen gas was
charged with the cis-polybutadiene (a-4)/cyclohexane solution in which
140 g of the 1,4-cis-polybutadiene (a-4) was dissolved, and the
vinyl/cis-polybutadiene/cyclohexane solution containing 60 g of the
vinyl/cis-polybutadiene (A-4) was added thereto while stirring. After
stirring for one hour, the solution was dried under vacuum at 105°
C. for 60 minutes to obtain 200 g of a vinyl/cis-polybutadiene rubber
(A-3) which was a mixture of the vinyl/cis-polybutadiene (A-4) and the
1,4-cis-polybutadiene (a-4).
[0172]The physical properties of the vinyl/cis-polybutadiene rubber (A-3)
and the vinyl/cis-polybutadiene (A-4) are shown in Table I-1 and Table
Production of Vinyl/Cis-Polybutadiene Rubber (A-5)
[0173]A vinyl/cis-polybutadiene rubber (A-5) was obtained in the same
the solvent was changed from cyclohexane to benzene and that the
unsaturated high molecular compound (polyisoprene) was not added. The
physical properties thereof are shown in Table I-1.
Production Example Production
Main solvent (kind) cyclohexane cyclohexane cyclohexane Benzene
(SP value) 8.1 8.1 or less 8.1 or less 9.1
Vinyl/cis-polybutadiene (kind) A-1 A-2 A-3 A-5
Mooney viscosity (ML1 + 65 63 68 52
4, 100° C.)
1,2-polybutadiene (mass %) 12.3 12.1 12.2 12.1
crystalline fiber (b)
Polyisoprene (mass %) 10 -- -- --
1,4-cis-polybutadiene (a) a-1 a-2 a-3 + a-4 a-5
Mooney viscosity (ML1 + 31 32 38 31
Intrinsic viscosity (dl/g) 1.8 1.8 2.1 1.8
Weight average molecular 43 43 48 43
weight (Mw) ×104
Toluene solution (cp) 56 58 72 57
Cis-1,4-structure (mol %) 98.2 98.2 98.2 98.1
Trans-1,4-structure (mol %) 0.9 0.9 0.9 1.0
1,2-structure (mol %) 0.9 0.9 0.9 0.9
1,2-polybutadiene b-1 b-2 b-3 b-5
ηsp/c 1.8 1.6 1.7 1.5
Melting point of (° C.) 202 202 203 201
Average fiber length of (nm) 121 192 156 434
Number of crystalline 137 105 123 61
fibers *1 fibers/25 μm2
Average aspect ratio of 2.1 3.4 2.8 4.1
*1: Number of crystalline fibers having a fiber length of 200 nm or less
Vinyl/cis-polybutadiene (kind) A-4
1,2-polybutadiene crystalline fiber (b-3) (mass %) 40.5
1,4-cis-polybutadiene in (A-4) (kind) a-3
Mooney viscosity (ML1 + 4, 100° C.) 65
Intrinsic viscosity [η] (dl/g) 2.8
Toluene solution viscosity (cp) 175
Cis-1,4-structure (mol %) 98.3
Trans-1,4-structure (mol %) 0.9
1,2-structure (mol %) 0.8
1,4-cis-polybutadiene (kind) a-4
Mooney viscosity (ML1 + 4, 100° C.) 30
Intrinsic viscosity [η] (dl/g) 1.7
Toluene solution viscosity (cp) 55
Cis-1,4-structure (mol %) 98.1
Trans-1,4-structure (mol %) 1.0
1,2-structure (mol %) 0.9
[0174]Measuring methods of the physical properties are shown below.
[0175]Measured at 100° C. according to JIS K6300.
[0176]Measured according to the method described above.
[0177]The weight average molecular weight (Mw) was determined in a
tetrahydrofuran solution at 40° C. based on a calibration curve
using standard polystyrene by means of a gel permeation chromatography
(GPC, HCL-802A, manufactured by Tosoh Corp.).
(4) Toluene Solution Viscosity
[0178]A viscosity of a 5 mass % toluene solution of the
1,4-cis-polybutadiene (a) at 25° C. was measured and shown by
(5) Micro Structure of 1,4-Cis-Polybutadiene (a)
[0179]Determined by infrared absorption spectral analysis of the rubber
part. The micro structure was calculated from an absorption intensity
ratio of an absorption peak of a 1,4-cis structure: 740 cm-1, an
absorption peak of a 1,4-trans structure: 967 cm-1 and an absorption
peak of a vinyl structure: 910 cm-1.
(6) Content and Melting Point of 1,2-Polybutadiene Crystalline Fiber (b)
[0180]A differential scanning calorimeter (DSC-50, manufactured by
Shimadzu Corporation) was used to determine an endothermic curve at a
heating speed of 10° C./minute, wherein a peak temperature thereof
was set as the melting point, and the content was calculated from a heat
absorbing amount thereof.
(7) Fiber Form of Crystalline Fibers
[0181]The vinyl/cis-polybutadiene rubber was vulcanized in a mixed
solution of sulfur monochloride and carbon disulfide, and a ultra thin
section was cut out from the vulcanizate thereof by means of
Ultramicrotome (manufactured by Leica AG.). The section was observed
under a transmission type electron microscope (model H-7100FA,
manufactured by Hitachi, Ltd.), and the photograph of 5000 magnifications
[0182]The photograph was binarized in a range of 25 μm2 using an
image analysis soft (Win ROOF, manufactured by Mitani Corporation) to
determine a fiber length, an aspect ratio and an area of the crystalline
fibers. Next, the average fiber lengths and the aspect ratios were
averaged by multiplying the values of the respective crystalline fibers
by an area ratio.
[0183]The number of the crystalline fibers was determined by calculating
less per 1 mass % of the 1,2-polybutadiene crystalline fibers.
Examples and Comparative Examples in the First Embodiment Examples I-1 to
I-3 and Comparative Examples I-1 to I-3
[0184]The vinyl/cis-polybutadiene rubbers A-1 and A-5 obtained in
Production Example 1 and Comparative Production Example 1 were used, and
the blending materials excluding the vulcanization accelerating agent and
sulfur out of the compositions shown in Table I-3 were kneaded at a
maximum temperature controlled to 170 to 180° C. by means of a
Banbury mixer of 1.7 L for test. Then, the vulcanization accelerating
agent and sulfur were added to the above kneaded material and kneaded on
a 10 inch roll, and this was rolled out in a sheet form, followed by
putting the sheet into a die and vulcanizing to obtain a vulcanizate. The
vulcanization was carried out at 155° C. for 10 minutes. The
results thereof are shown in Table I-3.
[0185]In Table I-3, the 300% tensile elastic modulus, the tensile
strength, the breaking elongation, the tear strength and the Akron
abrasion are relative values to the values obtained in Comparative
Example I-2. In Comparative Example I-2, the 300% tensile elastic modulus
was 5.3 MPa; the tensile strength was 15.2 MPa; the breaking elongation
was 580%; the tear strength was 55 N/mm; the Akron abrasion was 0.42
cc/3000 cycles; and the wet skid resistance was 27.
[0186]The details of symbols shown in Table I-3 are described below.
[0187]SMR-L: natural rubber (standard Malaysian rubber) [0188]S-SBR:
styrene-butadiene copolymer (block SBR, trade name: Asaprene 303,
manufactured by Asahi Kasei Chemicals Corporation, styrene unit content:
46 mass %, Mooney viscosity (ML1+4, 100° C.): 45) [0189]EVA:
ethylene-vinyl acetate copolymer (trade name: V218, manufactured by Ube
Industries, Ltd., vinyl acetate unit content: 18%) [0190]Silica: (trade
name: Nipsil VN3, manufactured by Tosoh Silica Corporation, average
particle diameter: 16 nm) [0191]Other additives: polyethylene glycol
(trade name: PEG #4000, manufactured by Sanyo Kasei Kogyo Co., Ltd.) 1.5
part by weight, activated zinc oxide 2.5 parts by weight, an antioxidant
(styrenated phenol, trade name: Nocrac SP, manufactured by Ouchi Shinko
Chemical Industrial Co., Ltd.) 1 part by weight, a tackifier 2 parts by
weight, a vulcanization accelerating agent (dibenzothiazyl disulfide,
trade name: Nocceler DM, manufactured by Ouchi Shinko Chemical Industrial
Co., Ltd.) 1.2 part by weight, a vulcanization accelerating agent
(tetramethylthiuram monosulfide, trade name: Nocceler TS, manufactured by
Ouchi Shinko Chemical Industrial Co., Ltd.) 0.3 part by weight and sulfur
1.8 part by weight.
[0192]The physical properties of the rubber compositions were measured in
the following manners.
(1) Specific gravity (density): measured by an A method according to JIS
K6268.(2) Hardness: measured at room temperature by means of a type A
durometer according to JIS K6253.(3) Tensile elastic modulus, tensile
strength and breaking elongation: measured according to JIS K6251.
Further, the indices were calculated by setting the values obtained in
Comparative Example I-2 to 100. It is shown that the larger the numerical
values are, the higher the tensile elastic modulus and the tensile
strength are, and the larger the breaking elongation is.(4) Tear
strength: measured according to JIS K6252. Further, the index was
calculated by setting the value obtained in Comparative Example I-2 to
100. It is shown that the larger the numerical value is, the higher the
tear strength is.(5) Akron abrasion: an abrasion weight loss was measured
according to JIS K6264. Further, the index was calculated by setting the
value obtained in Comparative Example I-2 to 100. It is shown that the
larger the numerical value is, the higher the Akron abrasion performance
is, and the better the physical properties are.(6) Wet skid resistance: a
skid resistance was measured on frosted glass wetted with water by means
of a portable skid tester prescribed in ASTM-E303. Further, the index was
gripping performance is.
Blend table I-1 I-2 I-3 I-1 I-2 I-3
Vinyl/cis-poly- (kind) A-1 A-1 A-1 A-1 A-5 A-5
butadiene rubber (mass part) 50 50 50 50 50 50
SMR-L (mass part) 30 30 30 49 30 30
S-SBR (Asaprene 303) (mass part) 20 20 10 1 20 20
EVA (V218) (mass part) -- -- 10 -- -- --
Silica (Nipsil VN3) (mass part) 20 7 7 1 20 7
Other additives (mass part) 10.3 10.3 10.3 10.3 10.3 10.3
Specific gravity 1.04 0.98 0.97 0.95 1.04 0.98
Hardness 63 58 59 50 60 54
300% tensile elastic (index) 121 107 115 79 100 91
Tensile strength (index) 113 97 100 73 100 90
Breaking elongation (index) 98 96 100 68 100 87
Tear strength (index) 108 104 106 82 100 90
Akron abrasion (index) 105 98 98 81 100 91
Wet skid resistance (index) 115 110 110 94 100 96
[0193]It can be found from the results shown in Table I-3 that the rubber
compositions prepared in Examples I-1 to I-3 are excellent in a tensile
elastic modulus, a tensile strength, an abrasion resistance and the like
as compared with the rubber compositions prepared in Comparative Examples
I-1 to I-3 when the specific gravities thereof stay at the same level and
that they are excellent in a balance of a reduction in a weight to a
hardness and mechanical characteristics. Further, the rubber compositions
prepared in Examples I-1 to I-3 are excellent as well in a gripping
property in a wet state.
Examples I-4 to I-5 and Comparative Examples I-4 to I-5
[0194]The vinyl/cis-polybutadiene rubbers A-1 and A-5 obtained in
sulfur out of the compositions shown in Table I-4 were kneaded by means
of a Banbury mixer of 1.7 L for test to obtain a kneaded material which
was a rubber composition for shoe soles. In this case, the maximum
kneading temperature was controlled to 170 to 180° C. Then, a
foaming agent and a cross-linking agent were kneaded into the above
kneaded material on a 10 inch roll, and this was rolled out in a sheet
form, followed by putting the sheet into a die and vulcanizing to obtain
a vulcanizate. The vulcanization was carried out at 160° C. for 10
minutes. The results thereof are shown in Table I-4.
[0195]In Table I-4, the shrinkage rate after foaming, the 300% tensile
elastic modulus, the tensile strength, the breaking elongation, the tear
strength and the Akron abrasion are shown by relative values to the
values obtained in Comparative Example I-5.
[0196]The shrinkage rate after foaming was obtained by measuring a
shrinkage rate in 24 hours or later of the sheet vulcanized and foamed in
a die of 150×150×4 mm. Further, the indices thereof were
calculated by setting the value obtained in Comparative Example I-5 to
100. The smaller the index is, the smaller the shrinkage rate is, and the
more excellent the dimensional stability is.
[0197]In Comparative Example I-5, the shrinkage rate after foaming was
1.1%; the 300% tensile elastic modulus was 6.2 MPa; the tensile strength
was 11.5 MPa; the breaking elongation was 560%; the tear strength was 39
N/mm; the Akron abrasion was 0.25 cc/3000 cycles; and the wet skid
resistance was 25.
[0198]The details of symbols shown in Table I-4 are described below.
[0199]1,2-Polybutadiene resin: trade name: JSR RB820, melting point:
95° C., manufactured by JSR Co., Ltd. [0200]SMR-L, S-SBR and EVA:
the same as described above [0201]Other additives: polyethylene glycol
(trade name: PEG #4000, manufactured by Sanyo Kasei Kogyo Co., Ltd.) 1
part by weight, zinc oxide 3 parts by weight, stearic acid (manufactured
by Asahi Denka Co., Ltd.) 1 part by weight, titanium oxide (anatase type)
4 parts by weight, a foaming agent (p,p'-oxybisbenzenesulfonylhydrazine
(OBSH)) 2 parts by weight, a foaming agent (azodicarbonamide (ADCA)) 1
part by weight, a foaming auxiliary agent (urea derivative, trade name:
Selton NF, manufactured by Sankyo Chemical Co., Ltd.) 1 part by weight,
DCP (98% dicumyl peroxide, trade name: Percumyl D, manufactured by NOF
Corporation) and sulfur 0.05 part by weight.
[0201] TABLE I-4
I-4 I-5 I-4 I-5
Vinyl/cis-poly- (kind) A-1 A-1 A-1 A-5
butadiene rubber (mass part) 55 55 55 55
1,2-polybutadiene (mass part) 25 25 34 25
SMR-L (mass part) 10 10 10 10
S-SBR (Asaprene (mass part) 10 -- 1 10
EVA (V218) (mass part) -- 10 -- --
Silica (Nipsil VN3) (mass part) 12 12 1 10
Other additives (mass part) 13.75 13.75 13.75 13.75
Specific gravity 0.94 0.88 0.90 0.93
Hardness 71 71 74 67
Shrinkage rate after (index) 88 85 103 100
300% tensile elastic (index) 120 115 102 100
Tensile strength (index) 116 105 94 100
Breaking elongation (index) 101 97 88 100
Tear strength (index) 115 110 92 100
Akron abrasion (index) 102 99 83 100
Wet skid resistance (index) 114 110 78 100
[0202]It can be found from the results shown in Table I-4 that the rubber
compositions prepared in Examples I-4 to I-5 have a smaller shrinkage
rate after foaming as compared with the rubber compositions prepared in
Comparative Examples I-4 to I-5 and that they are excellent in a
dimensional stability, and it can be found that they are improved in a
tensile elastic modulus, a tensile strength, an abrasion resistance and
the like when the specific gravities thereof stay at the same level and
prepared in Examples I-4 to I-5 are excellent as well in a gripping
Examples and Comparative Examples in the Second Embodiment Examples II-1
to II-3 and Comparative Example II-1
[0203]The vinyl/cis-polybutadiene rubbers A-2 and A-5 obtained in
Production Example 2 and Comparative Production Example 1 were used, and
sulfur out of the compositions shown in Table II-1 were kneaded at a
a 10 inch roll in a sheet form, followed by putting the sheet into a die
and vulcanizing to obtain a vulcanizate. The vulcanization was carried
out at 155° C. for 10 minutes. The results thereof are shown in
Table II-1 together with the results obtained in Comparative Examples I-2
and I-3.
[0204]Symbols and the like shown in Table II-1 are the same as in Table
I-3 described above, and measuring methods for the physical properties
are the same as described above.
[0205]In Table II-1, the 300% tensile elastic modulus, the tensile
strength, the breaking elongation, the tear strength, the Akron abrasion
and the wet skid resistance were shown by indices which were calculated
by setting the values obtained in Comparative Example I-2 to 100. The
measured values of the physical properties in Comparative Example I-2 are
the same as described above.
Blend table II-1 II-2 II-3 II-1 II-2 II-3
Vinyl/cis-poly- (kind) A-2 A-2 A-2 A-2 A-5 A-5
EVA (mass part) -- -- 10 -- -- --
Hardness 60 55 58 48 60 54
300% tensile elastic (index) 116 103 113 78 100 91
Tensile strength (index) 112 95 101 72 100 90
Breaking elongation (index) 99 92 100 67 100 87
Tear strength (index) 105 101 102 80 100 90
Akron abrasion (index) 101 96 98 82 100 91
Wet skid resistance (index) 114 108 110 96 100 96
[0206]It can be found from the results shown in Table II-1 that the rubber
compositions prepared in Examples II-1 to II-3 are excellent in a tensile
as compared with the rubber compositions prepared in Comparative Example
II-1 and Comparative Examples I-2 to I-3 when the specific gravities
thereof stay at the same level and that they are excellent in a balance
of a reduction in a weight to a hardness and mechanical characteristics.
Further, the rubber compositions prepared in Examples II-1 to II-3 are
excellent as well in a gripping property in a wet state.
Examples II-4 to II-5 and Comparative Example II-4
[0207]The vinyl/cis-polybutadiene rubbers A-2 and A-5 obtained in
sulfur out of the compositions shown in Table II-2 were kneaded by means
of a Banbury mixer of 1.7 L for test to obtain a kneaded matter which was
a rubber composition for shoe soles. In this case, the maximum kneading
temperature was controlled to 170 to 180° C. Then, a foaming agent
and a cross-linking agent were kneaded into the above kneaded material on
vulcanization was carried out at 160° C. for 10 minutes. The
results thereof are shown in Table II-2 together with the results
obtained in Comparative Example I-5.
[0208]Symbols and the like shown in Table II-2 are the same as in Table
I-4 described above, and measuring methods for the physical properties
[0209]In Table II-2, the shrinkage rate after foaming, the 300% tensile
strength, the Akron abrasion and the wet skid resistance are relative
values to the values obtained in Comparative Example I-5. The measured
values of the physical properties in Comparative Example I-5 are the same
II-4 II-5 II-4 I-5
Vinyl/cis-poly- (kind) A-2 A-2 A-2 A-5
JSR RB820 (mass part) 25 25 34 25
EVA (mass part) -- 10 -- --
Silica (Nipsil VN3) (mass part) 12 12 1 12
Hardness 68 68 72 67
Shrinkage rate after (index) 92 90 102 100
300% tensile elastic (index) 117 111 103 100
Tensile strength (index) 111 103 92 100
Breaking elongation (index) 98 96 89 100
Tear strength (index) 112 107 91 100
Akron abrasion (index) 102 98 82 100
Wet skid resistance (index) 115 110 81 100
[0210]It can be found from the results shown in Table II-2 that the rubber
foam compositions prepared in Examples II-4 to II-5 have a smaller
shrinkage rate after foaming as compared with the rubber foam
compositions prepared in Comparative Example II-4 and Comparative Example
I-5 and that they are excellent in a dimensional stability, and it can be
found that they are improved in a tensile elastic modulus, a tensile
strength, an abrasion resistance and the like when the specific gravities
Further, the rubber compositions prepared in Examples II-4 to II-5 are
Examples and Comparative Examples in the Third Embodiment Examples III-1
to III-3 and Comparative Example III-1
[0211]The vinyl/cis-polybutadiene rubbers A-3 and A-5 obtained in
Production Example 3 and Comparative Production Example 1 were used, and
sulfur out of the compositions shown in Table III-1 were kneaded at a
results thereof are shown in Table III-1 together with the results
obtained in Comparative Examples I-2 and I-3.
[0212]Symbols and the like shown in Table III-1 are the same as in Table
[0213]In Table III-1, the 300% tensile elastic modulus, the tensile
Blend table III-1 III-2 III-3 III-1 I-2 I-3
Vinyl/cis-poly- (kind) A-3 A-3 A-3 A-3 A-5 A-5
Hardness 62 57 59 49 60 54
300% tensile elastic modulus (index) 120 105 110 80 100 91
Tensile strength (index) 115 96 100 75 100 90
Breaking elongation (index) 99 95 99 70 100 87
Tear strength (index) 106 102 105 80 100 90
Akron abrasion (index) 104 97 97 80 100 91
Wet skid resistance (index) 112 108 108 95 100 96
[0214]It can be found from the results shown in Table III-1 that the
rubber compositions prepared in Examples III-1 to III-3 are improved in a
tensile elastic modulus, a tensile strength, an abrasion resistance, a
gripping property in a wet state and the like as compared with the rubber
compositions prepared in Comparative Example III-1 and Comparative
Examples I-2 to I-3 when the specific gravities thereof stay at the same
level and that they are excellent in a balance of a reduction in a weight
to a hardness and mechanical characteristics.
Examples III-4 to III-5 and Comparative Examples III-4 and I-5
[0215]The vinyl/cis-polybutadiene rubbers A-3 and A-5 obtained in
sulfur out of the compositions shown in Table III-2 were kneaded by means
kneaded matter on a 10 inch roll, and this was rolled out in a sheet
minutes. The results thereof are shown in Table III-2 together with the
results obtained in Comparative Example I-5.
[0216]Symbols and the like shown in Table III-2 are the same as in Table
[0217]In Table III-2, the shrinkage rate after foaming, the 300% tensile
strength, the Akron abrasion and the wet skid resistance were shown by
indices which were calculated by setting the value obtained in
Comparative Example I-5 to 100. The measured values of the physical
properties in Comparative Example I-5 are the same as described above.
III-4 III-5 III-4 I-5
Vinyl/cis-poly- (kind) A-3 A-3 A-3 A-5
Specific gravity 0.94 0.88 0.9 0.93
Hardness 70 70 73 67
Shrinkage rate after (index) 89 87 102 100
300% tensile elastic (index) 118 112 102 100
Tensile strength (index) 114 102 95 100
Breaking elongation (index) 100 95 90 100
Tear strength (index) 113 108 90 100
Akron abrasion (index) 103 100 85 100
Wet skid resistance (index) 112 108 80 100
[0218]It can be found from the results shown in Table III-2 that the
rubber compositions prepared in Examples III-4 to III-5 have a smaller
shrinkage rate after foaming as compared with the rubber compositions
prepared in Comparative Example III-4 and Comparative Example I-5 and
that they are excellent in a dimensional stability, and it can be found
that they are improved in a tensile elastic modulus, a tensile strength,
an abrasion resistance, a gripping property in a wet state and the like
when the specific gravities thereof stay at the same level and that they
are excellent in a balance of a reduction in a weight to a hardness and
[0219]The rubber composition for shoe soles according to the present
foaming. Accordingly, an outsole for shoes prepared by using the rubber
composition or the rubber foam composition according to the present
invention as a rubber base material is suited as an outsole for shoes
such as men's shoes, ladies' shoes, sport shoes and the like. The above
rubber composition or rubber foam composition can be used as well for car
parts such as tires, rubber vibration isolators and the like, industrial
products such as belts, hoses, rubber vibration isolators and the like,
toys and parts for miscellaneous goods
Patent applications by Naomi Okamoto, Chiba JP
Patent applications by Takashi Wada, Chiba JP
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