A flame-retardant olefinic resin composition comprising (1) 100 parts by weight of an ethylenic polymer resin mixture having an average density of 0.890 to 0.915 g/cm.sup.3, of (a) an ethylenic polymer consisting mainly of an ethylene-alpha-olefin copolymer and (b) a silane-grafted polymer obtained by grafting a silane to at least one component of said ethylenic polymer (a), and (2) 50 to 300 parts by weight of a hydrated metal compound.

The present invention relates to flame-retardant olefinic resin 
compositions which have excellent shape retention at high temperatures, 
which have been improved in drip prevention during burning as well as in 
mechanical characteristics such as whitening on bending, wear resistance, 
etc., which generate no hazardous and corrosive gas of halogen type during 
burning due to fire outbreak and which have excellent extrusion 
moldability. 
Imparting flame retardancy to polyolefin compositions extensively used as 
an insulating material for electric wires, cables and electric appliances 
have conventionally been achieved by adding a halogen compound and 
antimony trioxide to a polyolefin. However, the resulting compositions 
contain a halogen, and therefore generate, during burning, a halide gas 
which is harmful to the human body and corrodes metals. Moreover, these 
compositions produce, during burning, a large amount of fume making the 
visibility poor. This has imposed a significant restriction with respect 
to evacuation of people and fire fighting activity during fire. 
In order for conventional flame-retardant resin compositions to 
additionally have improved thermo-formability, a large equipment for 
effecting crosslinking such as chemical crosslinking, electron ray 
crosslinking or the like is required, which induces increase in facility 
investment cost, operational and maintenance expenses of facility, etc. 
This has led to an increase in the cost of such compositions. 
Japanese Patent Application Laid-Open No. 101129/1985 discloses production 
of a flame-retardant crosslinked resin composition, characterized by 
subjecting a silane-grafted polyolefin resin to crosslinking. I this 
production, the crosslinking reaction can be accelerated by, for example, 
catalyst addition, but kneading is conducted to form siloxane 
crosslinkages between silane-grafted polymer molecules. 
Japanese Patent Application Laid-Open No. 147463/1985 discloses production 
of a flame-retardant polyolefin composition containing a silane-grafted 
polyolefin resin as a base component. In this production, magnesium 
hydroxide is used because magnesium hydroxide has a higher dehydration 
temperature than other hydrated metal compounds such as aluminum hydroxide 
and crosslinking by water is less likely to occur. To avoid crosslinking 
by water, magnesium hydroxide is kneaded with a part of a non-crosslinked 
polyolefin resin to prepare a master batch of a high concentration. Prior 
to molding, the master batch is mixed with the rest of the non-crosslinked 
polyolefin resin and the mixture is subjected to extrusion molding, etc. 
Siloxane crosslinkages between silane-grafted polymer molecules are formed 
lastly. 
Silane-grafted polymers are obtained by grafting a silane (e.g. 
vinylalkoxysilane) to a polyolefin resin in the presence of a 
radical-generating agent (e.g. a peroxide). They have a number of branches 
each containing a hydrolyzable silanol group, bonded to the respective 
olefin chains. These silanol groups hydrolyze in the presence of water 
(hot water or steam) and a tin type catalyst to form strong siloxane 
(.fwdarw.Si--O--) linkages between silane-grafted polymer molecules. This 
can be viewed as a condensation reaction between silanol groups via water 
molecules. 
The above reaction, when taking place during kneading of a flame-retardant 
resin composition, strikingly reduces the moldability of the final 
product, deteriorates its appearance and, in some cases, makes its 
extrusion molding impossible. Therefore, in the production of a 
flame-retardant resin composition using a water-containing additive, there 
have been carried out various measures to avoid as much as possible the 
contact between a silane-grafted polymer and a hydrate, for example, (a) 
using a hydrate having a high dehydration-starting temperature and (b) 
preparing two separate systems, one containing a silane-grafted polymer 
and the other containing a hydrate and mixing the two systems at a final 
molding step to obtain a flame-retardant resin composition. 
In the present invention, as shown in Japanese Patent Publication Nos. 
24373/1982 and 26620/1982, a number of silanol groups (.fwdarw.Si--OH) 
possessed by the molecular chain of a silane-grafted polymer cause 
hydrolysis with a small amount of water present on the surfaces of a 
hydrated metal compound, an inorganic filler, and the like because of the 
frictional heat generated during kneading. As a result, condensation 
reaction takes place between the silanol groups and the hydroxyl groups of 
said water, whereby strong siloxane linkages are formed. This reaction 
mechanism is quite different from those in the above mentioned Laid-Open 
Patent Applications wherein a silane-grafted polymer is subjected to 
crosslinking by water (hot water or steam) using a catalyst as an 
accelerator to obtain a flame-retardant resin composition. 
Conventional flame-retardant resin compositions have been provided with 
flame retardancy by using a hydrated metal compound and not by using a 
halogen. However, as seen in Japanese Patent Publication No. 10898/1982, 
these compositions contain, as a base resin, not only crystalline 
polyolefin resin but also other thermoplastic resins such as polystyrene, 
ABS, nylon or the like and accordingly, upon burning, generate fume 
containing a considerable amount of a hazardous gas derived from the 
polystyrene or amide type resin. 
As seen in Japanese Patent Publication No. 10898/1982, self-extinguishing 
resin compositions using a combination of a thermoplastic resin, magnesium 
hydroxide and carbon powders and developed for a primary purpose of flame 
retardancy improvement have not been practically satisfactory at all 
because of the presence of carbon powders, since multi-color (e.g. eight 
colors) indication has been required in certain applications such as an 
insulated wire and an jacket in communication lines. 
In Japanese Patent Publication No. 38260/1984, since a polyolefin has no 
polarity and accordingly has no affinity with a filler, the base resin 
itself is grafted with a silane to impart polarity, in place of subjecting 
the filler to surface treatment with a coupling agent or the like, whereby 
an affinity between the base resin and the filler is improved. This 
additionally improves the reinforcement effect of the filler and increases 
the mechanical properties of the resulting resin composition including its 
surface hardness. However, no mention is made of flame retardancy and the 
resin composition is quite different from the flame-retardant resin 
composition of the present invention. Said patent publication states that 
the affinity between the base resin and the filler is improved only by the 
polarity imparted to the base resin, and no explanation is given as to the 
detailed bonding mechanism between the base resin and the filler. 
The concept of the invention of Japanese Patent Publication No. 24373/1982 
is close to that of the present invention. In the former invention, 
however, a halogen type flame retardant is used. Further in the former 
invention, the silanol groups of a silane-grafted polymer capture an 
inorganic filler and thereby a strong capture effect is obtained, but the 
detailed bonding mechanism between the silanol groups and the filler is 
nothing but presumption, and any concrete explanation is given to neither 
siloxane crosslinkage structure derived from the use of a metal hydrate 
nor the resulting gel fraction residue. Furthermore, in the composition of 
the above patent publication, the range of the inorganic filler, 10 to 150 
parts by weight is narrower and accordingly the composition has a 
different component ratio compared with the present composition wherein a 
hydrated metal compound is used in a larger amount to provide high flame 
retardancy. 
The present invention has been attained in view of the above situation and 
has developed a hazard free, flame retardant resin composition which is 
very safe to the human body and does not corrode metals, etc. during 
burning due to fire outbreak. The object of the present invention is to 
provide a flame-retardant resin composition which requires no special 
equipment for effecting crosslinking, which is inexpensive, which is 
excellent in shape retention at high temperatures, drip prevention during 
burning and fuming tendency, which is improved in mechanical properties 
(e.g. tensile strength, mar resistance, whitening on bending, wear 
resistance), low temperature properties, chemical resistance, etc. and 
accordingly has balanced properties, and which has good processability. 
The flame-retardant resin composition of the present invention contains no 
halogen and, upon burning, generates harmful gas. The present composition 
is based on the reaction mechanism wherein a silane-grafted polymer and a 
hydrated metal compound contained therein form strong linkages. 
In the present invention, the ethylenic polymer resin mixture of an 
ethylenic polymer and a silane-grafted polymer is specified to have an 
average density of 0.890 to 0.915 g/cm.sup.3, whereby the resin mixture is 
low crystalline and has a flexibility comparable to that of an elastomer 
and can be filled with a large amount of a hydrated metal compound. 
Moreover, the present composition is remarkably improved in mechanical 
characteristics such as elongation, embrittlement at low temperatures and 
oxygen index as well as in flame retardancy. 
As well known, silane-grafted polymers are called "a water-crosslinkable 
resin" and, when placed together with a crosslinking accelerator 
(catalyst) in a certain environmental condition wherein a certain amount 
or more of water and a certain level or higher of heat are present, form 
siloxane linkages between silane-grafted polymer molecules, finally 
leading to the formation of a silane-crosslinked polyethylene. In this 
reaction, there is required, as the accelerator (catalyst), an organic 
metal compound such as dibutyltin dilaurate. 
However, when a silane-grafted polymer is kneaded with a hydrated metal 
compound as a flame retardant, even if no crosslinking accelerator is 
present, the silanol groups (.fwdarw.SiOH) of the silane-grafted polymer 
and the hydroxyl groups (--OH) of the surface of the hydrated metal 
compound cause hydrolytic condensation reaction by the actions of (1) a 
slight amount of water present on the surface of the hydrated metal 
compound and (2) the metal compound (this latter action is similar to the 
catalytic action of organic metal compounds) and also by the help of 
frictional heat generated by kneading, whereby strong siloxane linkages 
(--Si--O--M.sub.m O.sub.n wherein M is a metal) are formed. In this 
reaction, no catalyst is required. 
Accordingly, the flame-retardant resin composition of the present 
invention, upon burning, exhibits (a) cooling effect that the heat 
generated is abosrbed by the heat of gasification of water generated by 
the decomposition of the hydrated metal compound and (b) drip prevention 
effect due to the fact that the thermal decomposition of the resin 
composition is suppressed by the strong linkages (these linkages 
characterizes the present invention) between the silane-grafted polymer 
and the hydrated metal compound. The flame-retardant resin composition of 
the present invention, leaving hard cinders upon burning owing to the 
strong linkages, further exhibits effect of prevention of flame spreading. 
Also owing to the strong linkages, the present composition furthermore 
exhibits effect of strikingly reducing the amount of fume generated. 
Thus, the burning suppression effect of the present composition is quite 
different from that of conventional flame-retardant resin compositions 
relying on carbon powders. The present composition can exhibit burning 
suppression effect even when various coloring agents including carbon 
black as a pigment are incorporated depending upon uses and therefore can 
be tinted as desired and used in extensive applications. In the 
flame-retardant resin composition of the present invention, the amounts of 
the hydrated metal compound and the silane-grafted polymer can be varied 
depending upon the level of flame retardancy required. 
The hydrated metal compound used in the present composition can be 
subjected to surface treatment with a surface-treating agent, whereby the 
present composition not only can have improved flexibility and moldability 
but also can contain a larger amount of a hydrated metal compound. 
The ethylene-alpha-olefin copolymer used in the present composition is a 
copolymer of ethylene and an alpha-olefin (e.g., propylene, butene-1, 
pentene-1, 4-methylpentene-1, hexene, or octene) or a mixture of such 
copolymers. Copolymers of ethylene and butene-1, pentene-1 or 
4-methylpentene-1 are preferred. Of these, linear low density polyethylene 
(LLDPE) and very low density polyethylene (VLDPE) which are both low 
crystalline, are particularly effective. 
As well known, the density of a polyethylene is determined by its 
crystallinity, and the crystallinity is governed by the degree of 
branching in the polyethylene molecules. 
Polyethylenes are classified into the following three types by their 
densities. 
(1) Low density polyethylene (LDPE) produced according to a high pressure 
radical polymerization process. Density: 0.915 to 0.930 g/cm.sup.3 
(2) Medium density polyethylene (MDPE) produced according to a medium to 
low pressure metal catalyst process. Density: 0.930 to 0.940 g/cm.sup.3 
(3) High density polyethylene (HDPE) produced according to a low pressure 
metal catalyst process. Density: 0.940 g/cm.sup.3 or more 
Around 1980, there was developed an ethylene-alpha-olefin copolymer which 
is produced according to a low pressure process using a metal catalyst, 
which has a straight chain molecular structure of low branching similarly 
to HDPE and which has a lower density than LDPE. This polymer is called a 
linear low density polyethylene (Linear-LDPE or L-LDPE), because it has a 
straight chain molecular structure similarly to HDPE and a lower density 
than LDPE. 
Around 1985, a very low density polyethylene (Very-LDPE or V-LDPE) was put 
on sale and joined the market of EVA and elastomers. V-LDPE is an 
ethylene-alpha-olefin copolymer which was developed by using, as the 
alpha-olefin, butene-1, pentene-1, 4-methylpentene-1 or the like and 
employing an appropriate ethylene-alpha-olefin ratio to adjust the 
density. 
These two low density polyethylene (L-LDPE and V-LDPE) each having a 
straight chain molecular structure are produced according to processes 
quite different from the conventional process (high pressure radical 
polymerization process) of LDPE which is highly branched and which is low 
crystalline. They have the following densities. 
(4) L-LDPE 0.910 to 0.935 g/cm.sup.3 
(5) V-LDPE 0.890 to 0.910 g/cm.sup.3 
These low density polyethylenes, each having a straight chain molecular 
structure, are different from conventional polyethylenes in solid 
characteristics and melt characteristics and quite different in 
moldability and accordingly are new ethylene-alpha-olefin copolymers. 
In the present invention, a focus was put on the fact that L-LDPE and 
V-LDPE are very flexible and, even after having been filled with a large 
amount of a metal hydrate, do not deteriorate their physical properties 
such as mechanical strength and elongation, and an ethylenic polymer 
consisting mainly of L-LDPE or V-LDPE was used as a base material. 
In the present invention, the silane-grafted polymer is a silane-grafted 
modified resin which is obtained by reacting at least one component of the 
above ethylenic polymer consisting mainly of a ethylene-alpha-olefin 
copolymer with an organic silane represented by the general formula 
RR'SiY.sub.2 (wherein R is a monovalent, olefinically unsaturated 
hydrocarbon group, Y is a hydrolyzable organic group, and R' is a 
monovalent hydrocarbon group other than unsaturated aliphatic hydrocarbon 
groups or is same as Y) in the presence of a free-radical-generating 
compound. The silane-grafted polymer can be obtained according to one of 
the known processes disclosed in Japanese Patent Publication Nos. 
24373/1982, 1711/1973, Japanese Patent Application Laid-Open No. 
24342/1975, etc. and can be produced specifically by reacting, for 
example, a polyolefin resin and vinyltrimethoxysilane in the presence of 
an organic peroxide having a strong activity as a polymerization 
initiator, such as dicumyl peroxide (DCP). 
The change of density of the ethylenic polymer by the addition of the 
silane-grafted polymer is less than 0.001 g/cm.sup.3 and can be regarded 
as virtually none. 
The resin portion in the flame-retardant olefinic resin composition of the 
present invention is an ethylenic polymer mixture having an average 
density of 0.890 to 0.915 g/cm.sup.3, of (a) the above mentioned ethylenic 
polymer consisting mainly of an ethylene-alpha-olefin copolymer and (b) 
the above mentioned silane-grafted polymer obtained by grafting a silane 
to at least one component of the ethylenic polymer (a). The ethylenic 
polymer specifically consists mainly of L-LDPE or V-LDPE which is an 
ethylene-.alpha.-olefin copolymer. The ethylenic polymer can additionally 
contain conventional polymers such as high density polyethylene, medium 
density polyethylene, low density polyethylene, ethylene-vinyl acetate 
copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), ethylene-maleic 
anhydride-ethyl acrylate copolymer and the like for improvements of 
mechanical properties, surface adhesion, etc. as long as the average 
density of the ethylenic polymer is kept at 0.890 to 0.915 g/cm.sup.3. The 
ethylene-alpha-olefin copolymer as a main component of the ethylenic 
polymer (a) can also be, besides L-LDPE or V-LDPE, ethylene-propylene 
copolymer, ethylene-hexene copolymer, or ethylene-octene copolymer. 
The flame-retardant olefinic resin composition of the present invention 
use, as a base component, an ethylenic polymer mixture having an average 
density of 0.890 to 0.915 g/cm.sup.3, of (a) an ethylenic polymer 
consisting mainly of an ethylene-alpha-olefin polymer and (b) a 
silane-grafted polymer obtained by grafting a silane to at least one 
component of the ethylenic polymer (a). This ethylenic polymer mixture has 
good balance in various physical properties and processability as long as 
it has an average density of 0.890 to 0.915 g/cm.sup.3. However, when the 
density is outside the range, the balance is lost. For instance, when the 
density is smaller than 0.890 g/cm.sup.3, the mixture is too low in 
crystallinity and its thermal characteristics such as heat resistance in 
oven test and heat deformation deteriorate noticeably. When the density is 
larger than 0.915 g/cm.sup.3, the mixture is highly crystalline and cannot 
be filled with a large amount of a hydrated metal compound. Further, the 
mixture filled with a hydrated metal compound is very hard. As the 
ethylene-alpha-olefin copolymer used in the ethylenic polymer mixture, 
LLDPE and VLDPE are particularly effective for achieving the specified 
density range of the ethylenic polymer mixture. 
The amount of the silane-grafted polymer used is preferred to be 2% by 
weight or more, because the amount less than 2% by weight provides no 
sufficient effect for the shape retention at high temperatures and drip 
prevention during burning, of the flame-retardant resin composition of the 
present invention. The crosslinking degree of the silane-grafted polymer 
is preferred to be 20 to 80% by weight when expressed in terms of gel 
fraction as a xylene insoluble portion. When the gel fraction is smaller 
than 20% by weight, there is obtained no sufficient effect for the shape 
retention at high temperatures and drip prevention during burning. When 
the gel fraction is larger than 80% by weight, the moldability of the 
present flame-retardant resin composition is poor. A number of 
combinations of the ethylenic polymer (a) and the silane-grafted polymer 
(b) are possible to meet various requirements for their mixture in surface 
hardness, low temperature resistance, stress cracking resistance, 
adhesivity, etc. All of the combinations can be easily kneaded and molten. 
The hydrated metal compound used in the present invention is a compound 
having a decomposition starting temperature of 150.degree. to 450.degree. 
C. and represented by the general formula M.sub.m O.sub.n.XH.sub.2 O 
(wherein M is a metal; m and n are each an integer of 1 or more determined 
by the valency of the metal; and X is the number of molecules of bound 
water), or a double salt containing said compound. Specific examples of 
the hydrated metal compound are aluminum hydroxide [Al.sub.2 
O.sub.3.3H.sub.2 O or Al(OH).sub.3 ], magnesium hydroxide [MgO.H.sub.2 O 
or Mg(OH).sub.2 ], calcium hydroxide [CaO.H.sub.2 O or Ca(OH).sub.2 ], 
barium hydroxide [BaO.H.sub.2 O or BaO.9H.sub.2 O], zirconium oxide 
hydrate (ZrO.nH.sub.2 O), tin oxide hydrate (SnO.H.sub.2 O), basic 
magnesium carbonate [3MgCO.sub.3 Mg.(OH).sub.2.3H.sub.2 O], hydrotalcite 
(6MgO.Al.sub.2 O.sub.3.H.sub.2 O), dawsonite (Na.sub.2 CO.sub.3.Al.sub.2 
O.sub.3.nH.sub.2 O), borax (Na.sub.2 O.B.sub.2 O.sub.5 .5H.sub.2 O) and 
zinc borate (ZnB.sub.4 O.sub.7.2H.sub.2 O). 
When 50 to 300 parts by weight of the hydrated metal compound is mixed and 
kneaded with 100 parts of the ethylenic polymer mixture of an ethylenic 
polymer (a) and a silane-grafted polymer (b), the silanol groups 
(.fwdarw.Si--OH) of the silane-grafted polymer cause hydrolysis by the 
action of a slight amount of water present on the surface of the hydrated 
metal compound and also by the help of frictional heat generated during 
kneading and, as a result, cause condensation reaction with the hydroxyl 
groups of the surface of the hydrated metal compound to form strong 
siloxane linkages. Owing to the strong linkages, the resulting composition 
has sufficient shape retention at high temperatures and exhibits drip 
prevention during burning, and is improved in mechanical properties such 
as tensile strength, mar resistance, whitening on bending and wear 
resistance, and furthermore is improved in chemical resistance and low 
temperature characteristics, and accordingly is balanced in various 
properties and further has good processability. When the amount of the 
hydrated metal compound is less than 50 parts by weight, it is difficult 
to obtain flame retardancy as desired. When the amount is more than 300 
parts by weight, the composition is low in mechanical properties such as 
tensile strength and poor in extrudability. 
The hydrated metal compound used in the present invention need not be 
subjected to surface treatment in advance. However, the hydrated metal 
compound subjected to surface treatment with at least one silane coupling 
agent, silicone derivative, fatty acid or fatty acid metal salt can 
improve the mechanical properties and processability of the composition. 
The silane coupling agent is represented by the general formula 
RR'SiY.sub.2 (wherein R is an organic functional group; Y is a 
hydrolyzable organic group; and R' is a monovalent hydrocarbon group other 
than unsaturated aliphatic hydrocarbon groups or is same as Y). 
Specifically explaining, the silane coupling agent has, at one terminal of 
the molecule, a reactive group capable of reacting with inorganic 
substances, such as methoxy group, ethoxy group, carboxyl group, 
cellosolve group or the like. The reactive group ordinarily is a 
trifunctional group but may be a di- or monofunctional group. The silane 
coupling agent has, at the other terminal of the molecule, a reactive 
group capable of reacting with organic substances, such as vinyl group, 
epoxy group, methacryl group, amino group, mercapto group or the like. The 
silane coupling agent has an alkoxy oligomer as the main chain skelton of 
the molecule. 
The silicone derivative is a modified organopolysiloxane obtained by 
substituting some of the methyl groups of dimethylpolysiloxane with an 
organic group such as a functional group, a hydrolyzable group or the 
like. As the organic group, there can be cited a number of modifier 
groups. They are, for example, modifier groups for improving 
compatibility, hydrophilicity, lubricity, moldability, water repellency, 
etc. such as alpha-methylstyrene group, alpha-olefin group, polyether 
group, alcohol group, fluoroalkyl group and the like; modifier groups for 
imparting reactivity and adsorbability, such as amine group, mercapto 
group, epoxy group, carboxyl group and the like; modifier groups 
substituted with a higher fatty acid, carnauba or an amide, for imparting 
releasability and lustering; reactive modifier groups having a 
methacryloxypropyl group; and modifier groups having hydroxyl group or 
amine group at one terminal. 
The fatty acid is a monobasic carboxylic acid represented by the general 
formula RCOOH wherein R has a saturated or unsaturated chain structure of 
3 to 40 carbon atoms. Ordinary fatty acids for general use such as stearic 
acid (saturated) and oleic acid (unsaturated) can exhibit sufficient 
effects. When a hydrated metal compound such as magnesium hydroxide is 
formed in a slurry state and successively surface-treated with a fatty 
acid, it is possible that the fatty acid which is hydrophobic be added 
together with a surfactant, then emulsified by the surfactant and used for 
the surface treatment of the hydrated metal compound. The hydrated metal 
compound thus treated is then dried. In this case, the surfactant can be 
used in an amount not adversely affecting the physical properties of the 
final composition. 
The fatty acid metal salt is an alkali metal salt of the above mentioned 
fatty acid and is represented by the general formula RCOOM wherein R has 
the same definition as above and M is an alkali metal atom. Specific 
examples of the salt include sodium stearate, potassium stearate, sodium 
oleate and potassium oleate. The fatty acid portion can be not only 
straight chain saturated or unsaturated fatty acids but also fatty acids 
bonded to a metal at the side chains. 
The flame-retardant resin composition of the present invention can further 
contain, if necessary, various additives conventionally used, such as 
antioxidant, neutralizing agent, UV absorber, antistatic, pigment, 
dispersing agent, lubricant, thickener, foaming agent, metal deterioration 
inhibitor, flow control agent, flame retardant of phosphorus or phosphine 
derivative type, other inorganic filler, crosslinking agent, crosslinking 
aid and the like. The present composition can be subjected to crosslinking 
by electron rays. 
For improvements of strength, impact strength and moldability, the 
flame-retardant olefinic resin composition of the present invention can 
furthermore contain, if necessary, an alpha-olefin homopolymer or 
copolymer having a density lower than 0.890 g/cm.sup.3 or higher than 
0.915 g/cm.sup.3, a copolymer (which may be grafted) between an 
alpha-olefin (major component) and a polar monomer (e.g. vinyl acetate, 
maleic anhydride, acrylic acid), or their mixture. The addition amount of 
such a polymer basically has no restriction as long as the resin density 
of the present composition is kept at 0.890 to 0.915 g/cm.sup.3. 
The surface treatment of the hydrated metal compound can sufficiently be 
conducted by ordinary mechanical stirring using a Henschel mixer, a 
blender or the like. The stirring time differs depending on the type of 
the equipment used but no special equipment is required. 
The addition of the surface treating agent to the hydrated metal compound 
must be made in a method best suited to that particular treating agent, 
such as dropwise method, one lump addition method or the like. Some 
treating agents can be added after being diluted with water, an alcohol, a 
solvent or the like, or after being emulsified with a surfactant or the 
like. It is also possible that a surface treating agent be added during 
the production process of, for example, magnesium hydroxide. That is, it 
is possible that (1) a surface treating agent be added in one lump at a 
step of magnesium hydroxide production process wherein magnesium hydroxide 
has been formed in slurry state, then (2) thorough stirring be conducted 
for surface treatment and lastly (3) the hydrated metal compound thus 
treated be dried. Or, it is possible that magnesium hydroxide which has 
been dried be surface-treated with a surface treating agent. 
Each of the above mentioned components of the present composition can be 
metered, mixed and kneaded using the same conventional equipments as used 
for rubbers and plastics. No special equipment is required. That is, the 
components are uniformly mixed using a mixer such as ribbon blender, 
Henschel mixer or the like and then kneaded using a melt kneader such as 
Banbury roll, extruder or the like to obtain a desired product. 
The pellets obtained by the above kneading are extruded into a desired 
shape such as tube, tape or the like using an appropriate die. In this 
case, no means for accelerating the crosslinking of the silane-grafted 
polymer is required such as crosslinking acceleration catalyst (e.g. a tin 
type) or hot water or steam treatment after extruding. 
As stated in Japanese Patent Publication No. 26620/1982, the reason for no 
requirement for catalyst or hot water or steam treatment is that the 
silanol groups of the silane-grafted polymer and the filler having good 
compatibility with said silanol groups bond with each other strongly and 
no crosslinking reaction between the silanol-grafted polymer molecules is 
required. 
Silane-grafted polymers, when stored as a material, are required to be kept 
in a bag having an aluminum lining, in order to prevent undesirable 
crosslinking before use due to water absorption. According to our 
confirmation, however, once a silanol-grafted polymer has been mixed into 
the composition of the present invention and the composition has been 
kneaded according to a method as mentioned above, the resulting 
composition has no worry of water absorption and, even after having been 
allowed to stand in air for 3 days or in a sealed dry container for 3 
months, has no problem in extrudability. 
The present invention has the following meritorious effects. 
(1) The flame-retardant olefinic resin composition of the present 
invention, upon burning due to fire outbreak, generates no harmful and 
corrosive gas of halogen type and accordingly causes no public hazzard. 
(2) Unlike conventional flame-retardant compositions, the present 
composition requires no facility for effecting crosslinking. This makes 
unnecessary facility investment and the operational and maintenance 
expenses for the facility, whereby the present composition can be produced 
economically at a low cost. 
(3) The above advantages (1) and (2) are attributed to the use of a 
hydrated metal compound as a filler. That is, the silanol groups 
(.fwdarw.Si--OH) of a silane-grafted polymer and the hydroxyl groups 
(--OH) of the surface of a hydrated metal compound cause hydrolytic 
condensation reaction by the actions of (a) a slight amount of water 
present on the surface of the hydrated metal compound and (b) the hydrated 
metal compound (this latter action is similar to the catalytic action of 
organic metal compounds) and also by the help of frictional heat generated 
during kneading, whereby strong siloxane linkages (--Si--O--M.sub.m 
O.sub.n where M is a metal) are formed. In this formation of siloxane 
linkages, any conventional means such as catalyst, hot water treatment or 
the like is not required. 
(4) The strong siloxane linkages between the silane-grafted polymer and the 
hydrated metal compound allows the present composition to exhibit, upon 
burning, cooling effect wherein the heat of combustion generated is 
absorbed by the heat of gasification of the water generated due to the 
thermal decomposition of the hydrated metal compound, as well as drip 
prevention effect wherein said strong siloxane linkages suppress the 
thermal decomposition of the present composition. The strong siloxane 
linkages make cinders hard and allow the present composition to further 
exhibit the effect of preventing flame spreading. The linkages furthermore 
exhibit the effect of remarkably suppressing the amount of fume generated. 
(5) In the present composition, the ethylenic polymer mixture between (a) 
an ethylenic polymer and (b) a silane-grafted polymer is specified to have 
an average density of 0.890 to 0.915 g/cm.sup.3. This imparts to the 
mixture low crystallinity and flexibility comparable to those of 
elastomers, enabling filling with a large amount of a hydrated metal 
compound. It also achieves remarkable improvements in elongation, 
embrittlement at low temperatures, oxygen index, mechanical strength and 
flame retardancy. As a result, the present composition can be made 
balanced in flame retardancy and mechanical properties. 
(6) The present composition, by using a hydrated metal compound subjected 
to surfacte treatment, can be further improved in the flexibility, 
moldability, etc. 
(7) The present composition, exhibiting burning suppression effects quite 
different from those of conventional flame-retardant compositions using 
carbon powders, still exhibits said effects even when various pigments 
(including carbon black) are incorporated as a coloring agent in order to 
enable identification depending upon its application purposes. Hence, the 
present composition can be tinted in any desired color.

Next, the present invention will be explained specifically by way of 
Examples. 
EXPERIMENT I 
First, four silane-grafted polymers A, B, C and D were prepared from three 
low crystalline polyethylenes (1), (2) and (3) shown in Table 1 (all of 
which are ethylene-alpha-olefin copolymers) according to the formulations 
also shown in Table 1 and the following procedures. 
Dicumyl peroxide (DCP) was dissolved in vinyltrimethoxysilane. The solution 
was mixed with the low crystalline polyethylenes (1), (2) and (3) under 
agitation according to the formulations shown in Table 1, and each mixture 
obtained was extruded using a 50 mm.phi. monoaxial extruder at an 
extrusion temperature of 150.degree.-200.degree. C. to obtain 
silane-grafted polymer resins A, B, C and D in pellets. These pellets A to 
D were then stored separately in a sealed aluminum-laminated bag to 
isolate from external moisture. They were taken out from the respective 
bags when necessary, in required amounts. 
TABLE 1 
______________________________________ 
Silane-grafted polymer 
Components used 
A B C D 
______________________________________ 
(1) TPE-821 100 50 
(2) D-9052 100 50 50 
(3) A-4085 50 
DCP 0.2 0.2 0.2 0.2 
Vinyltrimethoxysilane 
3 3 3 3 
______________________________________ 
(1) TPE (trade name), a low crystalline polyolefin 
elastomer manufactured by Sumitomo Chemical Co., 
Ltd. 
Density: 0.910 g/cm.sup.3 
(2) Softlex (trade name), a VLDPE manufactured by 
Nippon Petrochemicals Co., Ltd. 
Density: 0.905 g/cm.sup.3 
(3) Tafmer A (trade name), an ethylene-alpha-olefin 
copolymer manufactured by Mitsui Petrochemical 
Industries Ltd. 
Density: 0.880 g/cm.sup.3 
Next, the components shown in Table 2 were placed in a container and 
kneaded using a Banbury roll to obtain compositions each in pellets. 
Each composition was again subjected to roll pressing to prepare pieces for 
various tests. For each composition, by using these test pieces, there 
were determined the degree of linkage between a silane-grafted polymer and 
a hydrated metal compound by gel fraction expressed in terms of xylene 
insoluble; mechanical characteristics by tensile strength, elongation and 
embrittlement temperature; surface characteristics by mar resistance, 
whitening on bending and wear resistance; thermal characteristics by heat 
deformation percentage and heat resistance; other characteristics by 
chemical resistance, oxygen index and amount of fume generated; and 
burning characteristics by drip prevention, hardness of cinders and 
prevention of flame spreading. The processability when made into a final 
product was examined using a 50 mm.phi. extruder. Furthermore, the overall 
rating of each composition as a flame-retardant material was made. The 
results are shown in Table 3. 
The flame-retardant compositions containing silane-grafted polymers 
(Examples 1 to 10) are satisfactory in all of the items evaluated. In 
these compositions, the burning characteristics are good irrelevantly to 
their colors, namely, natural colors or black. As seen in Example 10, even 
if a composition contains a polymer having a density of 0.933 g/cm.sup.3, 
the composition shows satisfactory mechanical characteristics as along as 
the composition has an average resin density of 0.915 g/cm.sup.3 or lower. 
In contrast, as seen in Comparative Example 3, when a composition has an 
average resin density higher than 0.915 g/cm.sup.3, the elongation 
decreases noticeably and the embrittlement temperature and extrudability 
are deteriorated. As seen from Comparative Examples 1 and 4, even when a 
composition has an average resin density lower than 0.915 g/cm.sup.3, if 
the composition contains no silane-grafted polymer, the composition is 
very inferior in surface characteristics (mar resistance and whitening on 
bending), although its burning characteristics can be improved by carbon 
addition, and accordingly such a composition has a problem in actual 
application. 
As seen in Comparative Examples 3 and 5, even when a composition contains a 
silane-grafted polymer, if the composition has an average resin density of 
0.922 g/cm.sup.3, the elongation is very low at 50% and the embrittlement 
temperature is poor. If the composition has an average resin density of 
0.885 g/cm.sup.3, the heat deformation percentage and heat resistance at 
200.degree. C. are very poor. 
As appreciated from Examples 6, 7, 8, 9 and 10, each of the ethylenic 
polymer, the silane-grafted polymer and the hydrated metal compound can be 
used as a combination of two or more kinds. 
EXPERIMENT II 
The compositions shown in Table 4 were prepared and evaluated in the same 
manners as in Experiment I. The results are shown in Table 5. 
As seen in Examples 12 to 20, surface treatment for magnesium oxide 
dihydrate gives better elongation and better tube extrudability than no 
surface treatment. With respect to the addition amount of magnesium oxide 
dihydrate, as seen in Comparative Examples 6 and 7, addition of 30 parts 
by weight gives poor burning characteristics and addition of 330 parts by 
weight gives very poor results in elongation, embrittlement temperature 
and extrudability. As seen in Examples 17 to 20, the difference in the 
colors of compositions gives no substantial difference in the 
characteristics of the compositions as long as each composition contains a 
silane-grafted polymer. As seen in Examples 14, 15 and 16, even when a 
composition contains a resin having a density of 0.933 or 0.950 
g/cm.sup.3, the composition has satisfactory characteristics if it has an 
average resin density not higher than 0.915 g/cm.sup.3. On the other hand, 
as seen in Comparative Example 8, if a composition has an average resin 
density higher than 0.915 g/cm.sup.3, the composition shows a remarkably 
reduced elongation. Furthermore, as seen in Comparative Example 9, if a 
composition has an average resin density lower than 0.890 g/cm.sup.3, the 
composition exhibits significantly deteriorated thermal characteristics. 
TABLE 2 
__________________________________________________________________________ 
Their representative 
Examples 
Components of composition 
properties 
1 2 3 4 5 6 7 
__________________________________________________________________________ 
*2 
D-9052 Density 0.905 g/cm.sup.3 
50 90 50 50 50 50 
*1 
821 Density 0.910 g/cm.sup.3 
*3 
A-4085 Density 0.880 g/cm.sup.3 
*4 
A-270 Density 0.933 g/cm.sup.3 
Silane-grafted polymer 
Density 0.910 g/cm.sup.3 
50 30 
resin A 
Silane-grafted polymer 
Density 0.905 g/cm.sup.3 
10 100 50 50 50 20 
resin B 
*5 
Aluminum oxide 
Average particle 
100 100 100 100 100 100 
trihydrate diameter 1.0 .mu.m 
*6 
Magnesium oxide 
Average particle 200 150 150 
dihydrate diameter 0.6 .mu.m 
*7 
Lubricant and 
-- 1.6 1.6 1.6 1.6 1.6 1.6 1.6 
stabilizer 
*8 
Pigment Color Natural 
Natural 
Natural 
Natural 
Natural 
Natural 
Natural 
color 
color color 
color color 
color color 
Gel fraction (degree of bonding between 
72 35 85 75 78 77 83 
silane-grafted polymer and hydrated metal 
compound) wt. % (*9) 
__________________________________________________________________________ 
Their representative 
Examples Comparative Examples 
Components of composition 
properties 
8 9 **10 1 2 **3 4 **5 
__________________________________________________________________________ 
*2 
D-9052 Density 0.905 g/cm.sup.3 
50 50 30 100 100 
*1 
821 Density 0.910 g/cm.sup.3 
20 20 20 
*3 
A-4085 Density 0.880 g/cm.sup.3 80 
*4 
A-270 Density 0.933 g/cm.sup.3 
20 100 60 
Silane-grafted polymer 
Density 0.910 g/cm.sup.3 
30 30 30 40 
resin A 
Silane-grafted polymer 
Density 0.905 g/cm.sup.3 20 
resin B 
*5 
Aluminum oxide 
Average particle 
200 200 200 200 200 250 
trihydrate diameter 1.0 .mu.m 
*6 
Magnesium oxide 
Average particle 
200 200 
dihydrate diameter 0.6 .mu.m 
*7 
Lubricant and 
-- 1.6 1.6 1.6 1.6 1.6 1.6 1.6 1.6 
stabilizer 
*8 
Pigment Color Natural 
Black 
Natural 
Natural 
Natural 
Gray Black 
Black 
color color 
color 
color 
Gel fraction (degree of bonding between 
58 55 49 0 0 58 0 42 
silane-grafted polymer and hydrated metal 
compound) wt. % (*9) 
__________________________________________________________________________ 
*4 A copolymer EEA, manufactured by Nippon Petrochemical 
Co., Ltd. 
*5 Higilite H-42M, untreated, manufactured by Showa Keikinzoku K.K. 
*6 #200-06, manufactured by Asahi Glass Co., Ltd. 
*7 Sanwax 171P, manufactured by Sanyo Kasei Kogyo K.K. 
0.1 
Irganox 1076, manufactured by Ciba Geigy K.K. 
0.3 
Sumilizer WXR, manufactured by Sumitomo Chemical Co., 
0.3. 
*8 Black; carbon black VALCUN 9A-32 
3.0 
*9 Residual weight after immersing in xylene for 
20 hours at 120.degree. C. and drying for 4 hours at 140.degree. C. 
**10 
Average resin density 0.913 g/cm.sup.3 
**3 
Average resin density 0.922 g/cm.sup.3 
**5 
Average resin density 0.885 g/cm.sup.3 
3 TABLE 3 
Evaluation Examples Evaluation item method 1 2 3 4 5 6 7 8 9 
**10 
Mechanical Tensile strength kg/cm.sup.2 ASTM D 638 1.3 1.5 2.4 1.8 1.4 
1.6 1.2 1.4 1.5 1.3 character- Elongation % ASTM D 638 510 670 
420 580 550 570 530 620 630 690 istics Embrittlement temperature 
.degree.C. ASTM D 746 -66 -66 -70 -64 -66 -66 -66 -66 -66 -64 
Surface Mar resistance *10 Excellent Good Excellent Excellent Excellent 
Excellent Excellent Excellent Good Good character- Whitening on bending 
*11 Excellent Good Excellent Excellent Excellent Excellent Excellent 
Excellent Excellent Excellent istics Abrasion resistance *12 Excellent 
Good Excellent Excellent Excellent Excellent Excellent Excellent 
Excellent Excellent Thermal Hot deformation degree % JIS K 6723 12 25 3 
10 8 7 11 8 8 14 character- Heat resistance 200.degree. C. .times. 
60 min. *13 Excellent Good Excellent Excellent Excellent Excellent 
Excellent Excellent Excellent Excellent istics Other Chemical resistance 
*14 Excellent Excellent Excellent Excellent Excellent Excellent Excellent 
Excellent Excellent Excellent character- Oxygen index ASTM D 2863 27 26 
30 29 35 36 34 35 36 33 istics Amount of fume generated (Dm) NBS 
nonflaming 72 78 54 62 64 60 72 69 54 65 Burning Drip prevention 
Excellent Good Excellent Excellent Excellent Excellent Excellent 
Excellent Excellent Excellent character- Hardness of cinders Excellent 
Good Excellent Excellent Excellent Excellent Excellent Excellent 
Excellent Excellent istics Prevention of flame spreading UL-94 (1/16") 
Excellent Good Excellent Excellent Excellent Excellent Excellent 
Excellent Excellent Excellent Rating V-1 V-2 V-1 V-1 V-0 V-0 V-0 V-0 
V-0 V-0 Tube extrudability *15 Excellent Excellent Good Excellent Good 
Good Good Good Good Good (appearance/extrusion torque) Overall rating -- 
Pass Pass Pass Pass Pass Pass Pass Pass Pass Pass 
Evaluation Comparative Examples Evaluation item method 1 2 **3 4 
**5 
Mechanical Tensile strength kg/cm.sup.2 ASTM D 638 0.9 0.6 0.8 0.9 
1.0 character- Elongation % ASTM D 638 640 120 50 600 510 istics 
Embrittlement temperature .degree.C. ASTM D 746 -62 -22 -32 -62 -54 
Surface Mar resistance *10 Unacceptable Unacceptable Excellent Unacceptab 
le Excellent character- Whitening on bending *11 Unacceptable Unacceptabl 
e Excellent Unacceptable Excellent istics Abrasion resistance *12 
Unacceptable Unacceptable Excellent Unacceptable Excellent Thermal Hot 
deformation degree % JIS K 6723 35 100 74 32 98 character- Heat 
resistance 200.degree. C. .times. 60 min. *13 Unacceptable Unacceptable 
Good Unacceptable Unacceptable istics Other Chemical resistance *14 
Unacceptable Unacceptable Excellent Unacceptable Excellent character- 
Oxygen index ASTM D 2863 32 32 34 33 37 istics Amount of fume generated 
(Dm) NBS nonflaming 115 122 84 125 92 Burning Drip prevention 
Unacceptable Unacceptable Good Acceptable Excellent character- Hardness 
of cinders Unacceptable Unacceptable Excellent Acceptable Excellent 
istics Prevention of flame spreading UL-94 (1/16") Unacceptable 
Unacceptable Excellent Acceptable Excellent Rating HB HB V-0 V-2 V-0 
Tube extrudability *15 Good good Acceptable Good Good (appearance/extrusi 
on torque) Overall rating -- Not pass Not pass Not pass Not pass Not 
*10 Pencil HB hardness, visual check for scratching. 
*11 Visual check for whitening on 180.degree. bending of 2 mm t sheet. 
*12 JIS K 7204 
*13 Shape retention when an extruded tube of 15 mm (inside diameter) and 
18 mm (outside diameter) has been cut into pieces of 10 cm in length and 
allowed to stand in an oven at 200.degree. C. for 60 minutes. 
*14 Weight reduction ratio when dipped in 10% hydrochloric acid for 1 
week. Evaluation based on TS,E retention. 
*15 50 mm monoaxial extruder, 150-160-170-180.degree. C., L/D 25, CR 3.5, 
extruded tube 15 mm (inside diameter) 18 mm (outside diameter). 
Evaluation: Excellent &gt; Good &gt; Acceptable &gt; Unacceptable 
TABLE 4 
__________________________________________________________________________ 
Their representative 
Examples 
Components of composition 
properties 11 12 13 **14 **15 **16 17 
__________________________________________________________________________ 
*16 
108 J Density 0.917 g/cm.sup.3 
20 20 70 
*2 D-9052 Density 0.905 g/cm.sup.3 
30 30 30 50 50 50 
*3 A-4085 Density 0.880 g/cm.sup.3 
*17 
5050 Density 0.950 g/cm.sup.3 10 
*4 A-270 Density 0.933 g/cm.sup.3 20 
*18 
EV-270 Density 0.950 g/cm.sup.3 10 
Silane-grafted polymer 
Density 0.905 g/cm.sup.3 
50 50 
resin B 
Silane-grafted polymer 
Density 0.908 g/cm.sup.3 
50 40 
resin C 
Silane-grafted polymer 
Density 0.898 g/cm.sup.3 
20 30 40 30 
resin D 
*19 
Magnesium oxide 
Untreated 150 
dihydrate 
*20 
Magnesium oxide 
Treated with 2% of a 
150 50 
dihydrate silane coupling agent 
*21 
Magnesium oxide 
Treated with 2% of 150 100 150 150 150 
dihydrate oleic acid 
*22 
Magnesium oxide 
Treated with 2% of a 
dihydrate titanate coupling agent 
*23 
UV absorbent 0.2 0.2 0.2 0.2 0.2 0.2 0.2 
*24 
Calcium carbonate 20 
*25 
Lubricant and stabilizer 
1.8 1.8 1.8 1.8 1.8 1.8 1.8 
*8 Pigment Color Natural 
Natural 
Natural 
Natural 
Natural 
Natural 
Gray 
color color 
color 
color color 
color 
Gel fraction (degree of bonding between silane-grafted 
68 75 83 63 67 60 54 
polymer and hydrated metal compound) Wt. % (*9) 
__________________________________________________________________________ 
Their representative 
Examples Comparative Examples 
Components of composition 
properties 18 19 20 6 7 **8 **9 
__________________________________________________________________________ 
*16 
108 J Density 0.917 g/cm.sup.3 
30 20 20 30 
*2 D-9052 Density 0.905 g/cm.sup.3 
70 40 70 30 30 
*3 A-4085 Density 0.880 g/cm.sup.3 30 
*17 
5050 Density 0.950 g/cm.sup.3 50 
*4 A-270 Density 0.933 g/cm.sup.3 
*18 
EV-270 Density 0.950 g/cm.sup.3 
Silane-grafted polymer 
Density 0.905 g/cm.sup.3 
50 50 
resin B 
Silane-grafted polymer 
Density 0.908 g/cm.sup.3 20 
resin C 
Silane-grafted polymer 
Density 0.898 g/cm.sup.3 
30 30 30 70 
resin D 
*19 
Magnesium oxide 
Untreated 
dihydrate 
*20 
Magnesium oxide 
Treated with 2% of a 
150 30 330 
dihydrate silane coupling agent 
*21 
Magnesium oxide 
Treated with 2% of 
150 100 200 200 
dihydrate oleic acid 
*22 
Magnesium oxide 
Treated with 2% of a 
50 
dihydrate titanate coupling agent 
*23 
UV absorbent 0.2 0.2 0.2 0.2 0.2 0.2 0.2 
*24 
Calcium carbonate 
*25 
Lubricant and stabilizer 
1.8 1.8 1.8 1.8 1.8 1.8 1.8 
*8 Pigment Color Beige 
Blue 
Black 
Natural 
Natural 
Black 
Black 
color 
color 
Gel fraction (degree of bonding between silane-grafted 
58 51 55 30 88 72 85 
polymer and hydrated metal compound) Wt. % (*9) 
__________________________________________________________________________ 
*16 
Showrex LLDPE, manufactured by Showa Denko K.K. 
*17 
Showrex HDPE, manufactured by Showa Denko K.K. 
*18 
Evaflex, manufactured by Mitsui Du Pont Polychemical K.K. Vinyl 
acetate content 28 wt. % 
*19 
KISUMA 5, manufactured by Kyowa Kagaku Kogyo K.K. Average particle 
diameter 0.6 .mu.m 
*20 
KISUMA 5, manufactured by Kyowa Kagaku Kogyo K.K. Surface-treated with 
2% of KBM-503 manufactured by Shin-Etsu Chemical 
Co., Ltd. 
*21 
KISUMA 5B, manufactured by Kyowa Kagaku Kogyo K.K. Surface-treated 
with 2% of oleic acid. 
*22 
KISUMA 5, manufactured by Kyowa Kagaku Kogyo K.K. Surface-treated with 
2% of plenact TTS manufactured by Ajinomoto Co., Ltd. 
*23 
TINUVIN P, manufactured by Ciba Geigy K.K. 
*24 
White P-30, manufactured by Shiraishi Kogyo Kaisha, Ltd. 
*25 
Sanwax 171P, manufactured by Sanyo Kasei Kogyo K.K. 
1.0 
CDA-1, manufactured by Adeka Argus Kagaku K.K. 
0.2 
Irganox 1076, manufactured by Ciba Geigy K.K. 
0.3 
Sumilizer WXR, manufactured by Sumitomo Chemical Co., 
0.3. 
**14 
Average resin density 0.910 g/cm.sup.3 
**15 
Average resin density 0.906 g/cm.sup.3 
**16 
Average resin density 0.904 g/cm.sup.3 
**8 
Average resin density 0.931 g/cm.sup.3 
**9 
Average resin density 0.888 g/cm.sup.3 
3 TABLE 5 
Evaluation Examples Evaluation item method 11 12 13 *14 *15 **16 17 
18 19 20 
Mechanical Tensile strength kg/cm.sup.2 ASTM D 638 1.4 1.5 1.6 1.7 1 
.5 1.3 1.6 1.6 1.6 1.5 character- Elongation % ASTM D 638 510 720 
730 690 690 620 710 670 720 660 
istics Embrittlement temperature .degree.C. ASTM D 746 -62 -64 -64 
-66 -66 -66 -66 -66 -66 -66 Surface Mar resistance *10 Excellent 
Excellent Excellent Excellent Excellent Excellent Excellent Excellent 
Excellent Excellent character- Whitening on bending *11 Excellent 
Excellent Excellent Excellent Excellent Excellent Excellent Excellent 
Excellent Excellent istics Abrasion resistance *12 Excellent Excellent 
Excellent Excellent Excellent Excellent Excellent Excellent Excellent 
Excellent Thermal Hot deformation degree % JIS K 6723 15 12 7 9 8 6 
7 8 8 7 character- Heat resistance 200.degree. C. .times. 60 min. 
*13 Excellent Excellent Excellent Excellent Excellent Excellent Excellent 
Excellent Excellent Excellent istics Other Chemical resistance *14 
Excellent Excellent Excellent Excellent Excellent Excellent Excellent 
Excellent Excellent Excellent character- Oxygen index ASTM D 2863 34 33 
34 34 34 34 35 34 35 36 istics Amount of fume generated (Dm) NBS 
nonflaming 75 70 67 69 70 68 68 70 73 75 Burning Drip prevention 
Excellent Excellent Excellent Excellent Excellent Excellent Excellent 
Excellent Excellent Excellent character- Hardness of cinders Excellent 
Excellent Excellent Excellent Excellent Excellent Excellent Excellent 
Excellent Excellent istics Prevention of flame spreading UL-94 (1/16") 
Excellent Excellent Excellent Excellent Excellent Excellent Excellent 
Excellent Excellent Excellent Rating V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 
V-0 V-0 Tube extrudability (appearance/extrusion *15 Excellent Excellent E 
xcellent Excellent Excellent Excellent Excellent Excellent Excellent 
Excellent torque) Overall rating -- Pass Pass Pass Pass Pass Pass Pass 
Pass Pass Pass 
Evaluation Comparative Examples Evaluation item method 6 7 **8 **9 
Mechanical Tensile strength kg/cm.sup.2 ASTM D 638 2.4 1.1 1.3 1.4 
character- Elongation % ASTM D 638 870 60 90 580 istics Embrittlement 
temperature .degree.C. ASTM D 746 -70 -28 -34 -57 Surface Mar 
resistance *10 Excellent Good Excellent Excellent character- Whitening 
on bending *11 Excellent Acceptable Excellent Excellent istics Abrasion 
resistance *12 Excellent Acceptable Excellent Excellent Thermal Hot 
deformation degree % JIS K 6723 24 2 11 -94 character- Heat resistance 
200.degree. C. .times. 60 min. *13 Excellent Excellent Excellent 
Unacceptable istics Other Chemical resistance *14 Excellent Acceptable 
Excellent Excellent character- Oxygen index ASTM D 2863 21 42 34 36 
istics Amount of fume generated (Dm) NBS nonflaming 121 95 85 77 
Burning Drip prevention Unacceptable Excellent Excellent Excellent 
character- Hardness of cinders Unacceptable Excellent Excellent 
Excellent istics Prevention of flame spreading UL-94 (1/16 ") Unacceptab 
le Excellent Excellent Excellent Rating HB V-0 V-0 V-0 Tube extrudabil 
ity (appearance/extrusion *15 Excellent Unacceptable Excellent Excellent 
torque) Overall rating -- Not pass Not pass Not pass Not pass