Method for manufacture of polybutadiene-modified unsaturated polyester

A method for the manufacture of a polybutadiene-modified unsaturated polyester, comprising the steps of: (I) reacting (A) an .alpha.,.beta.-unsaturated dicarboxylic acid or anhydride with (B) at least one compound selected from the group consisting of (i) air-drying allyl compounds, (ii) animal and vegetable oils or derivatives thereof and (iii) dicyclopentadiene or derivatives thereof at a (B)/(A) molar ratio within the range of from 0.8 to 1.2, and (II) reacting the resultant reaction product with (C) at least one compound selected from the group consisting of .alpha.,.omega.-polybutadiene glycol and .alpha.,.omega.-hydrogenated polybutadiene glycol. A polybutadiene-modified unsaturated polyester comprising said polybutadiene-modified unsaturated polyester and a polymerizable monomer possessing at least one double bond.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a method for the manufacture of 
polybutadiene-modified polyesters, to polybutadiene-modified unsaturated 
polyester resin compositions and to a method for the manufacture of these 
resin compositions. 
2. Description of Prior Arts 
Heretofore, polybutadiene-modified unsaturated polyester resin compositions 
have been manufactured by reacting unsaturated acids including polybasic 
acids with a liquid hydrogenated polybutadiene having a hydroxy group at 
an end thereby forming polybutadiene-modified unsaturated polyesters and 
incorporating therein a polymerizable monomer possessing at least one 
double bond (Japanese Patent Publication No. 10672/1971). While these 
polybutadiene-modified unsaturated polyester resin compositions, on 
setting, give products which excel in water resistance, flexibility, 
bending property, etc., they have a disadvantage that they set slowly and 
exhibit poor miscibility with other unsaturated polyester resin 
compositions. When such compositions are applied to substrates, therefore, 
they dry slowly and require long standing before they become ready for 
polishing. Thus, they are hardly usable as cold setting paints. Moreover, 
they are not readily modified because they have poor miscibility with 
other unsaturated polyester resin compositions of the kind frequently used 
as agents for modifying workability and physical properties of other 
polymers. The excellent properties exhibited by cured products of these 
polybutadiene-modified unsaturated polyester resin compositions have not 
been utilized to advantage. 
An object of this invention, therefore, is to provide a novel 
polybutadiene-modified unsaturated polyester, and a method for the 
manufacture thereof. 
Another object of this invention is to provide polybutadiene-modified 
unsaturated polyester resin compositions which in themselves possess 
excellent setting property and drying property at room temperature and 
which are capable of producing set coats excelling in water resistance, 
flexibility and bending property. 
A further object of this invention is to provide a method for the 
manufacture of polybutadiene-modified unsaturated polyester resin 
compositions of excellent properties as mentioned above. 
SUMMARY OF THE INVENTION 
The objects described above are attained according to this invention by a 
method for the manufacture of polybutadiene-modified unsaturated 
polyesters which comprises (I) reacting (A) .alpha.,.beta.-unsaturated 
dicarboxylic acids or anhydrides with (B) at least one compound selected 
from the group consisting of (i) air-drying allyl compounds, (ii) animal 
and vegetable oils or derivatives thereof and (iii) dicyclopentadiene or 
derivatives thereof in a (B)/(A) molar ratio within the range of from 0.8 
to 1.2 and (II) subsequently causing the resultant reaction products to be 
reacted upon by (C) at least one compound selected from the group 
consisting of .alpha.,.omega.-polybutadiene glycol and 
.alpha.,.omega.-hydrogenated polybutadiene glycol. 
The objects are further attained by the polybutadiene-modified unsaturated 
polyester resin compositions which are formed by incorporating into the 
polybutadiene-modified unsaturated polyesters mentioned above (III) a 
polymerizable monomer possessing at least one double bond. 
When the polybutadiene-modified unsaturated polyesters obtained by the 
method of this invention incorporate a polymerizable monomer possessing at 
least one double bond, they can be used as polybutadiene-modified 
unsaturated polyester resin compositions. 
The setting property and drying property which these resin compositions 
exhibit at room temperatures are comparable with those exhibited by the 
conventional air drying unsaturated polyesters. The set coats which are 
formed of these resin compositions excel in water resistance, flexibility 
and bending property. In terms of water resistance and abradability, these 
set coats far excel the set coats of vinyl ester type, bisphenol type and 
isophthalic acid type unsaturated polyester resin compositions. Further, 
the resin compositions of the present invention are compatible with 
dicyclopentadiene-modified unsaturated polyesters. The 
polybutadiene-modified unsaturated polyester resin compositions mixed with 
dicyclopentadiene-modified unsaturated polyesters give set coats which 
excel in fast adhesion to metal substrates. 
PREFERRED EMBODIMENT OF THE INVENTION 
According to this invention, the polybutadiene-modified unsaturated 
polyesters are produced by (I) reacting as component (A) 
.alpha.,.beta.-unsaturated dicarboxylic acids or anhydrides with as 
component (B) at least one compound selected from the group consisting of 
(i) air drying allyl compounds, (ii) unsaturated animal and vegetable oils 
or derivatives thereof, for example, the fatty acids thereof and the 
transesters thereof with polyols, and (iii) dicyclopentadiene or 
derivatives thereof, for example, a hydrozylated dicyclopentadiene, in a 
(B)/(A) molar ratio within the range of from 0.8 to 1.2 and (II) 
subsequently causing the resultant reaction products to be reacted upon by 
as component (C) at least one compound selected from the group consisting 
of .alpha.,.omega.-polybutadiene glycol and .alpha.,.omega.-hydrogenated 
polybutadiene glycol. In the step (II), when the reaction product (I) from 
the step (I) is reacted with component (C), as component (D) either (i) a 
polyhydric alcohol or (ii) a polybasic acid or both may be incorporated in 
the reactants. 
Typical example of the .alpha.,.beta.-unsaturated dicarboxylic acids or 
anhydrides usable for the present invention include maleic acid, maleic 
anhydride, fumaric acid, itaconic acid, and citraconic acid. 
Typical examples of the air drying allyl compounds include ethylene glycol 
monoallyl ether, propylene glycol monoallyl ether, butylene glycol 
monoallyl ether, neopentyl glycol monoallyl ether, glycerol diallyl ether, 
trimethylol propane diallyl ether and pentaerythritol triallyl ether which 
are invariably allyl compounds possessing one hydroxy group. 
Typical examples of the animal and vegetable oils include castor oil, 
soybean oil, linseed oil, cottonseed oil, rice bran oil, tung oil and 
whale oil. Typical examples of the derivatives thereof include castor oil 
fatty acid, soybean oil fatty acid, linseed oil fatty acid, cottonseed oil 
fatty acid, rice bran oil fatty acid and tung oil fatty acid, and 
transesterified oils obtained by transesterifying the aforementioned 
animal and vegetable oils with polyols such as ethylene glycol, propylene 
glycol, glycerol, trimethylol ethane, trimethylol propane, pentaerythritol 
and neopentyl glycol. 
Typical examples of the dicyclopentadiene or derivatives thereof include 
dicyclopentadiene (tricyclo-[5.2.1.0.sup.2,6 ]-decadiene-4,8), 
hydroxylated dicyclopentadiene (tricyclo-[5.2.1.0.sup.2,6 
]-deca-4-en-8-ol, tricyclo-[5.2.1.0.sup.2,6 ]-deca-4-en-9-ol) and 
tricyclodecane dimethylol. 
Typical examples of the .alpha.,.omega.-polybutadiene glycol are 
.alpha.,.omega.-polybutadiene glycols having number-averaged molecular 
weights in the range of from 1,000 to 3,000, preferably from 1,000 to 
2,000. Concrete examples are Arco Chemical Company's Polybd grades R-45, 
CS-15 and CN-15 and Nippon Soda Co., Ltd.'s Nisso PB-G grade represented 
by the following formula (1): 
##STR1## 
wherein, n is an integer having the value of 15 to 54. 
Typical examples of the .alpha.,.omega.-hydrogenated polybutadiene glycol 
are .alpha.,.omega.-hydrogenated polybutadiene glycols having 
number-average molecular weights in the range of from 1,000 to 3,000, 
preferably from 1,000 to 2,000. Concrete examples are Shin-Nippon Rika 
Co., Ltd.'s HPBG grades represented by the formula (2): 
##STR2## 
wherein, n is an integer having the value of 15 to 54. 
Typical examples of the polyhydric alcohol optionally usable in this 
invention include ethylene glycol, diethylene glycol, triethylene glycol, 
propylene glycol, dipropylene glycol, butanediol-1,3, butanediol-1,4, 
butanediol-2,3, neopentyl glycol, pentanediol-1,5, hexanediol-1,6, 
2,2,4-trimethyl pentanediol-1,3, hydrogenated bis-phenol, glycerol, 
trimethylolethane, trimethylolpropane and adduct of one mol of Bis-phenol 
A and 2 moles of ethylene oxide or propylene oxide. 
Typical examples of the polybasic acid optionally usable in this invention 
include phthalic anhydride, isophthalic acid, terephthalic acid, 
tetrahydrophthalic anhydride, hexahydrophthalic anhydride Himic anhydride 
(trademark designation used for 3,6-endomethylenetetrahydrophthalic 
anhydride produced by Hitachi Chemical Industry Co., Ltd.), 
tetrachlorophthalic anhydride, succinic acid, succinic anhydride, adipic 
acid and sebacic acid. 
The reaction of the .alpha.,.beta.-unsaturated dicarboxylic acid or 
anhydride (Component A) with at least one compound selected from the group 
consisting of (i) air drying allyl compound, (ii) unsaturated animal and 
vegetable oils or derivatives thereof and (ii) dicyclopentadiene or 
derivatives thereof (Component B) is carried out in a (B)/(A) molar ratio 
within the range of from 0.8 to 1.2 under the atmosphere of an inert gas 
such as nitrogen or carbon dioxide gas at temperatures falling within the 
range of from 100.degree. to 220.degree. C., preferably from 120.degree. 
to 170.degree. C. This reaction is terminated at the time that the acid 
number of the reaction product reaches a level within the range of from 
120 to 240, preferably from 150 to 200. When the molar ratio is less than 
0.8, the reaction system suffers from excess acid and the reaction does 
not readily proceed and, worse still, the resin compositions containing 
the unsaturated polyesters, obtained by this reaction suffer from impaired 
stability. When the molar ratio exceeds 1.2, the resin compositions 
suffer from impaired setting property. This (B)/(A) molar ratio is 
preferred to fall in the range of from 0.95 to 1.1. 
The reaction of the compound resulting from the reaction of Component A and 
Component B in the preceding step (Compound I) with the 
.alpha.,.omega.-polybutadiene and/or .alpha.,.omega.-hydrogenated 
polybutadiene (Component C) and the polyhydric alcohol and/or polybasic 
acid (Component D) optionally used can be performed by an ordinary method 
adopted for the production of unsaturated polyesters. No specific limit is 
placed on the proportion of the components involved in the reaction. In 
this reaction, it is naturally permissible to use the 
.alpha.,.omega.-polybutadiene glycol and the .alpha.,.omega.-hydrogenated 
polybutadiene glycol in combination as Component C. This reaction is 
carried out by heating the reactants at temperatures in the range of from 
150.degree. to 220.degree. C., preferably from 170.degree. to 200.degree. 
C., under the atmosphere of an inert gas such as air or carbon dioxide gas 
in the presence or absence of a solvent such as toluene or xylene, with 
continued removal of the water of condensation. This reaction is 
terminated optionally by the addition of a polymerization inhibitor at the 
time that the acid number of the reaction product reaches a level in the 
range of from 5 to 60, preferably from 10 to 30. Consequently, a 
polybutadiene-modified unsaturated polyester is produced. 
A polybutadiene-modified unsaturated polyester resin composition is 
produced by dissolving a polymerizable monomer possessing at least one 
double bond (Vinyl Monomer III) in the polybutadiene-modified unsaturated 
polyester (Polyester II) obtained as described above. 
Typical examples of the polymerizable monomer (Vinyl Monomer III) include 
styrene, chlorostyrene, methyl (meth)acrylate (signifying "methyl acrylate 
and/or methyl methacrylate," applicable similarly hereinafter), 
ethyl(meth)acrylate, isopropyl(meth)acrylate, vinyl toluene, 
.alpha.-methylstyrene, ethylene glycol di(meth)acrylate, propylene glycol 
di-(meth)acrylte, diallyl phthalate, vinyl acetate, tert-butylstyrene and 
triallyl cyanurate. Although the amount of the polymerizable monomer 
(Vinyl Monomer III) to be mixed with the polybutadiene-modified 
unsaturated polyester (Polyester II) is not specifically limited, it is 
desired to fall within the range of from 40 to 100 parts by weight, 
preferably from 50 to 70 parts by weight, based on 100 parts by weight of 
Polyester II, in due consideration of setting property, drying property, 
water resistance, flexibility, bending property, etc. 
To the polybutadiene-modified unsaturated polyester resin composition, a 
polymerization inhibitor is added in an amount within the range of from 
0.001 to 0.1% by weight, preferably from 0.01 to 0.05% by weight, based on 
the total amount of Polyester (II) and Vinyl Monomer (III). Examples of 
the polymerization inhibitor usable herein include hydroquinone, 
p-benzoquinone, tert-butyl catechol, di-tert-butyl catechol, 
mono-tert-butyl hydroquinone and di-tert-butyl-4-methyl phenol. 
The polybutadiene-modified unsaturated polyester resin compositions of the 
present invention can be blended with dicyclopentadiene-modified 
unsaturated polyesters (IV) to give products which are further improved in 
air drying property, setting property and capacity for fast adhesion to 
metal substrates. 
The dicyclopentadiene-modified unsaturated polyester is a resin which is 
obtained by using dicyclopentadiene or derivatives thereof in addition to 
components usually adopted for the production of unsaturated polyesters. 
For example, it may be synthesized by mixing 1 mol of hydroxylated 
dicyclopentadiene with 0.5 mol of propylene glycol and subjecting the 
resultant mixture to a treatment usually followed in the production of 
unsaturated polyesters. 
When the polymerizable monomer, the polybutadiene-modified and the 
dicyclopentadiene-modified unsaturated polyester are mixed, no specific 
limit is placed to their proportions. They can be mixed in amounts 
suitably selected to suit the properties the final product is expected to 
acquire. Preferably, the mixing of the components may be effected by 
preparatorily dissolving the polybutadiene-modified unsaturated polyester 
and the dicyclopentadiene-modified unsaturated polyester separately in 
portions of the polymerizable monomer and subsequently blending the 
solutions. In this case, the amount of the polymerizable monomer (III) to 
be used in the mixing is desired to fall in the range of from 40 to 100 
parts, preferably from 50 to 100 parts, based on 100 parts by weight of 
the total of the polybutadiene-modified unsaturated polyester and the 
dicyclopentadiene-modified unsaturated polyester. 
The polybutadiene-modified unsaturated polyester resin composition 
according to this invention may be set by using, as the curing agent, an 
organic peroxide such as benzoyl peroxide, methylethylketone peroxide, 
cyclohexanone peroxide, cumene hydroperoxide, acetylacetone peroxide, 
lauroyl peroxide and tert-butyl hydroperoxide, in an amount desirably 
within the range of 0.5 to 5% by weight, preferably 1 to 2% by weight, 
based on the weight of the composition. Optionally, one or more members 
selected from the group consisting of naphthenates, octenates and other 
metal soaps including, for example, cobalt naphthenate, cobalt octenate, 
magneses naphthenate, iron naphthenate, copper naphthenate, zinc 
naphthenate, zirconium naphthenate and lead naphthenate, may be used as 
the promoter and dimethyl aniline, diethyl aniline, acetyl acetone, 
dimethyl acetamide or quaternary ammonium salts may be used as an aid to 
the promoter. 
Optionally, the polybutadiene-modified unsaturated polyester resin 
composition of the present invention may incorporate, to suit the intended 
use, an inorganic filler such as calcium carbonate, magnesium carbonate, 
calcium sulfate, alumina, clay, talc, silica, diatomaceous earth or 
powdered mica, an ultraviolet ray absorbent such as phenyl salicylate, 
1-(2'-hydroxyl-5-methylphenyl)benzotriazole, 
2-hydroxy-4-methoxy-benzophenone or 2,2'-dihydroxy-4-methoxy-benzophenone, 
a thermoplastic resin such as polystyrene, polyetheylene, polyvinyl 
acetate, polymethyl methacrylate or saturated polyester, a dye or a 
pigment. 
Again, optionally, the resin composition of this invention may be set under 
a light source such as, for example, a mercury vapor lamp, a tungsten lamp 
or a xenone lamp in the presence of an ultraviolet ray curing agent such 
as, for example, benzoin, benzoin methyl ether, benzoin ethyl ether, 
benzoin isopropyl ether, diphenyl disulfide, di-.beta.-naphthyl sulfide, 
4,4'-dimethyl disulfide or 2,2', 4,4'-tetrachloro-disulfide which is added 
in an amount within the range of 0.5 to 5% by weight based on the weight 
of the resin composition. 
The polybentadiene-modified unsaturated polyester resin composition of the 
present invention forms a coat of excellent adhesiveness on the surface of 
a metal substrate such as steel plate or tin plate when it is applied to 
the metal substrate by the technique of spray coating, electrostatic 
coating, brush coating, flow coating or roll coating and then left to set 
under the atmosphere of air at a varying temperature to be selected 
depending on the kind of the catalyst in use, generally within the range 
of 5.degree. to 150.degree. C. 
Now, the present invention will be described specifically with reference to 
working examples. Wherever parts and percents are mentioned, they are 
meant parts and percents by weight unless otherwise specified.

EXAMPLE 1 
Under an atmosphere of nitrogen gas, 2 mols of maleic anhydride was caused 
to react upon 2 mols of trimethylol propane diallyl ether to produce a 
compound having an acid number of 180. This compound was cooled to 
70.degree. C. and 0.5 mol of .alpha.,.omega.-polybutadiene glycol (a 
product having a number-averaged molecular weight of 2,000, made by Nippon 
Soda Co., Ltd. and marketed under trademark designation of Nisso 
PB-G-2,000) and 0.5 mol of .alpha.,.omega.-hydrogenated polybutadiene 
glycol (a product having a number-averaged molecular weight of 2,000 and 
made by Shin-Nippon Rika Co., Ltd.) were added thereto and made to react 
thereon at 170.degree. C., to produce a polybutadiene-modified unsaturated 
polyester having an acid number of 20. In 70 parts of this resin, 30 parts 
of styrene and 0.03 part of hydroquinone were dissolved to produce a resin 
compound (A). 
The resin composition (A), with 1.0% of cobalt naphthenate (having a metal 
content of 6%) and 1.0% of Permeck N (55% methylethyl ketone peroxide made 
by Nippon Oils and Fats Co., Ltd.) incorporated therein, was applied with 
a powered spray gun (2.5 mm in nozzle diameter, made by Iwata Coater Co., 
Ltd. and marketed under trademark designation of Wider 60) at 25.degree. 
C. to a cold-drawn steel sheet 0.8 mm in thickness abraded in advance with 
a water-resistant paper, #150, to form thereon a film of 20 g/60 
mm.times.150 mm. 
EXAMPLE 2 
Under an atmosphere of nitrogen gas, 1 mol of glycerol and 3 mols of 
linseed oil fatty acid were subjected to esterification at 200.degree. C. 
to produce linseed oil fatty acid glyceride. Then under an atmosphere of 
nitrogen gas, 2 mols of this linseed oil fatty acid glyceride was made to 
react with 2 mols of maleic anhydride at 150.degree. C. to produce a 
compound having an acid number of 120. This compound was cooled to 
70.degree. C. and 1 mol of the same .alpha.,.omega.-polybutadiene glycol 
(PB-G-2,000) as used in Example 1 was made to react thereon, to produce a 
polybutadiene-modified unsaturated polyester having an acid number of 17. 
In 70 parts of this resin were dissolved 30 parts of styrene and 0.03 part 
of hydroquinone, to produce a resin composition (B). 
The resin composition (B), with the hardening promoter and the hardening 
agent of Example 1 similarly incorporated, was applied to a steel sheet to 
form a film thereon. 
EXAMPLE 3 
Under an atmosphere of nitrogen gas, 2 mols of maleic anhydride was made to 
react upon 2.2 mols of hydroxylated dicyclopentadiene to produce a 
compound having an acid number of 200. This compound was cooled to 
50.degree. C. and 1 mol of the same .alpha.,.omega.-polybutadiene glycol 
(Nisso PB-G-2,000) as used in Example 1 was made to react thereon to 
produce a polybutadiene-modified unsaturated polyester having an acid 
number of 15. In 70 parts of this resin were dissolved 30 parts of styrene 
and 0.03 part of hydroquinone to produce a resin composition (C). 
The resin composition (C), with the hardening promotor and the hardening 
agent of Example 1 similarly incorporated, was applied to a steel sheet to 
form a film thereon. 
EXAMPLE 4 
Under an atmosphere of nitrogen gas, 2 mols of maleic anhydride was made to 
react upon 2 mols of hydroxylated dicyclopentadiene at 100.degree. C., to 
produce a compound having an acid number of 200. This compound was cooled 
to 50.degree. C. and 0.5 mol of .alpha.,.omega.-polybutadiene glycol (a 
product having a number-averaged molecular weight of 1,000, made by Nippon 
Soda Co., Ltd. and marketed under trademark designation of Nisso 
PB-G-1,000) and 0.6 mol of dipropylene glycol were made to react thereon 
at 180.degree. C., to produce a polybutadiene-modified unsaturated 
polyester having an acid number of 25. In 70 parts of this resin were 
dissolved 30 parts of styrene and 0.03 part of hydroquinone to produce a 
resin composition (D). 
With the hardening promoter and the hardening agent of Example 1 similarly 
incorporated, this resin composition (D) was applied to a steel sheet to 
form a film thereon. 
EXAMPLE 5 
Under an atmosphere of nitrogen gas, 0.9 mol of maleic anhydride, 0.1 mol 
of adipic acid, 0.9 mol of propylene glycol and 0.4 mol of hydroxylated 
dicyclopentadiene were made to react at 170.degree. C., to produce a 
dicyclopentadiene-modified unsaturated polyester having an acid number of 
30. In 70 parts of this resin were dissolved 30 parts of styrene and 0.03 
part of hydroquinone. The resultant solution was blended with 100 parts of 
the resin composition (D) to prepare a resin composition (E). 
This resin composition (E), with the hardening promoter and the hardening 
agent similarly incorporated, was applied to a steel sheet to form a film 
thereon. 
Control 1 
One mol of maleic anhydride was reacted upon by 1 mol of 
.alpha.,.omega.-hydrogenated polybutadiene glycol (a product having a 
number-averaged molecular weight of 2,000, made by Shin-Nippon Rika Co., 
Ltd.) at 160.degree. C., to produce a polybutadiene-modified unsaturated 
polyester having an acid number of 25. In 70 parts of this resin were 
dissolved 30 parts of styrene and 0.03 part of hydroquinone, to produce a 
resin composition (F). 
This resin composition (F), with the hardening promotor and the hardening 
agent of Example 1 similarly incorporated, was applied to a steel sheet to 
form a film thereon. 
Control 2 
Under an atmosphere of nitrogen gas, 0.8 mol of maleic anhydride, 0.2 mol 
of phthalic anhydride, 0.7 mol of ethyelene glycol, 0.1 mol of the same 
linseed oil fatty acid glyceride as used in Example 2 and 0.4 mol of 
dicyclopentadiene were made to react at 200.degree. C., to produce a 
dicyclopentadiene-modified unsaturated polyester. In 70 parts of this 
resin were dissolved 30 parts of styrene and 0.03 part of hydroquinone to 
produce a resin composition (G). 
This resin composition (G), with the hardening promoter and the hardening 
agent of Example 1 similarly incorporated, was applied to a steel sheet to 
form a film thereon. 
Control 3 
Under an atmosphere of nitrogen gas, 0.8 mol of fumaric acid, 0.2 mol of 
isophthalic acid and 1.1 mols of hydrogenated Bisphenol A were made to 
react at 210.degree. C., to produce an unsaturated polyester having an 
acid number of 30. In 70 parts of this resin were dissolved 30 parts of 
styrene and 0.03 part of hydroquinone to produce a resin composition (H). 
This resin composition (H), with the hardening promoter and the hardening 
agent of Example 1 similarly incorporated, was applied to a steel sheet to 
form a film thereon. 
The films obtained were tested for various properties. The results are 
shown in Table 1. 
TABLE 1 
__________________________________________________________________________ 
Coated film property 
Resin composition 
Items A B C D E F G H 
__________________________________________________________________________ 
Track free time.sup.1 (min.) 
60 90 60 30 30 -- 50 -- 
Dry surface time.sup.2 (min.) 
120 
160 
110 
90 60 unmea- 
120 about 1,500 
surable 
Surface hardness.sup.3 
50 40 60 70 80 5 60 90 
Fast adhesion to steel sheet.sup.4 
.DELTA. 
.DELTA. 
o o o o o x 
Flexibility.sup.5 
o o o o o o Crack 
crack 
Blistering property.sup.6 (days) 
&gt;10 
&gt;10 
&gt;10 
&gt;10 
&gt;10 
5 3 8 
__________________________________________________________________________ 
Note: 
.sup.1 Tack free time Time elapsing before the applied film ceased to 
stick to the finger tip brought into light contact with the film. 
.sup.2 Dry surface time Time elapsing before the applied film lost its 
viscosity so that light pressure applied thereto by the finger tip ceased 
to leave a fingerprint mark on the film surface. 
.sup.3 Surface hardness Measured with a durometer 24 hours after 
formation of the film. 
.sup.4 Fast adhesion to steel sheet Measured by bending the sheet 24 
hours after the formation of the film and rated on the scale (o denoting 
high adhesion, .DELTA. fast adhesion in about 50% of contact surface and 
substantial absence of adhesion). 
.sup.5 Flexibility Measured by bending the sheet 24 hours after the 
formation of the film (180.degree.). 
.sup.6 Blistering property Length of time (in days) of the film's 
standing under water at 40.degree. C. until blisters were formed in the 
interface between the film and the steel sheet. 
The resin compositions obtained by mixing polybutadiene-modified 
unsaturated polyesters produced by the method of this invention with 
polymerizable monomers possessing at least one double bond possessed the 
same degrees of hardening property and drying property as those of 
ordinary air-drying unsaturated polyester resins even under room 
temperature, and they exhibited resistance to water, fast adhesion to 
metal substrates, flexibility and blistering property at improved levels. 
The resin compositions additionally incorporating 
dicyclopentadiene-modified unsaturated polyesters exhibited the same 
degrees of properties.