Mold of a photocured resin containing a reinforcing agent

A mold having a cavity for shaping a three-dimensional object, which comprises a photocured resin of a photocurable resin composition comprising PA1 (A) a liquid photocurable resin, and PA1 (B) at least one reinforcing agent selected from the group consisting of inorganic solid particles having an average particle diameter of 3 to 70 .mu.m and a whisker having an average diameter of 0.3 to 1.0 .mu.m, a length of 10 to 70 .mu.m and an aspect ratio of 10 to 100 and optionally, in which the inner surface of the cavity is covered by a solid film having a thickness of 5 to 1000 .mu.m.

BRIEF DESCRIPTION OF THE INVENTION 
This invention relates to a mold of a photocured resin having a cavity for 
shaping a three-dimensional object. More specifically, it relates to a 
mold of a photocured resin which is suitable for the production of a 
three-dimensional object as a trial product. 
BACKGROUND OF THE INVENTION 
A method for optically shaping a product master model is known (see JP-A 
56-144478 (the term "JP-A" as used herein means an "unexamined published 
Japanese patent application") and JP-B 2-38422 (the term "JP-B" as used 
herein means a "Japanese patent publication")). It is also known that a 
mold (such as a simple mold) is produced by a resin molding method using 
this model. 
The prior art process of producing a mold by a resin molding method will be 
explained with reference to FIG. 2. FIG. 2(A) shows a state that a model 
101 and a parting line jig 103 are to be combined and FIG. 2(B) shows a 
state that they are combined. This model 101 is optically shaped. The 
parting line jig 103 is formed by machining, hand finishing or the like. 
Thereafter, as shown in FIGS. 2(C) and 2(D), the combined model 101 and 
parting line jig 103 are surrounded by a frame 105 (such as an acrylic 
plate), and a cavity mold 107 is formed on the parting surface 111 of the 
model 101 and the parting surface 131 of the parting line jig 103 by a 
resin molding method (using, as a resin, epoxy resin containing aluminum 
powder or the like), and cured. Then, as shown in FIG. 2(E), the frame is 
removed, the combination is turned upside down, and the parting line jig 
103 is removed. Thereafter, a drill hole (dowel hole 175) for aligning a 
core mold with a cavity mold is formed in the parting surface 171 of the 
cavity mold 107. 
Subsequently, as shown in FIGS. 2(F) and 2(G), an assembly of the model 101 
and the cavity mold 107 is surrounded by a frame 105, a release agent is 
applied to the inner surface 115 and parting surface 111 of the model 101, 
and a core mold 108 is formed on these surfaces by a resin molding method, 
and cured. Thereafter, the core mold 108 and the cavity mold 107 are 
separated from each other to remove the model 101. As shown in FIG. 2(H), 
both molds are combined, bound together by a constraint jig 109 and heated 
to complete a mold. 
In the prior art process of producing a mold, it is only a master model 
which is optically shaped, and a mold is fabricated through a process for 
transcribing a model, such as gypsum casting, spray depositing or the like 
in addition to the above-described resin molding. Heretofore, no 
photocured resin is available which has satisfactory properties as a mold 
material and hence, it has been considered that it is impossible to 
fabricate a mold itself by an optical shaping process. 
The prior art method for producing a mold by a transcription process 
involves the following problems. 
(1) The preparation of a master model is required and it takes time and 
labor. 
(2) When a mold is fabricated by transcribing a master model, dimensional 
accuracy and shape accuracy are deteriorated by transfer. 
(3) The transcription of a master model takes time and labor. 
(4) The transcription of a master model requires the skills of an expert. 
For example, the skills are required for determining the parting surface, 
manufacturing a parting line jig, controlling the temperature of a resin, 
mixing and defoaming. 
(5) The mold manufacturing process is needed additional steps due to 
preparation of a master model and the transcription works. 
SUMMARY OF THE INVENTION 
The inventors of the present invention have conducted intensive studies to 
provide a simple mold which can be produced with high accuracy in a small 
number of steps and at a low cost in a short period of time and as a 
result, have succeeded in creating a new technical basic concept which 
breaks down the conventional technical common knowledge that what is 
manufactured by an optical shaping process is a master model and not a 
mold itself. 
It is therefore an object of the present invention to provide a mold for 
shaping a three-dimensional object which is optically shaped from a 
specific resin composition. 
It is another object of the present invention to provide a shaping mold 
which can be used to shape a three-dimensional object a large number of 
times, that is, can provide a large number of completely shaped 
three-dimensional objects, and has improved service life. 
It is still another object of the present invention to provide a shaping 
mold which can provide almost the same number of completely shaped 
three-dimensional objects. 
Other objects and advantages of the present invention will become apparent 
from the following description. 
According to the present invention, the above objects and advantages are 
attained, firstly, by a mold having a cavity for shaping a 
three-dimensional object, which comprises a photocured resin of a 
photocurable resin composition comprising: 
(A) a liquid photocurable resin, and 
(B) at least one reinforcing agent selected from the group consisting of 
inorganic solid particles having an average particle diameter of 3 to 70 
.mu.m and a whisker having an average diameter of 0.3 to 1.0 .mu.m, a 
length of 10 to 70 .mu.m and an aspect ratio of 10 to 100.

The term "optical shaping" as used in this specification refers to, in a 
narrow sense, an optical shaping for obtaining a predetermined shape by 
curing a photocurable resin by irradiation of light (such as a visible 
ray, laser beam and ultraviolet ray) and further to a shaping system which 
uses an appropriate fluid medium which is photocured by a reactive energy 
ray such as an electron beam or high-energy particle beam. Further, it 
also refers to a shaping system which uses a lithography technique for 
projecting the above energy or a substance through a mask. 
As an unsaturated compound for the liquid photocurable resin used in the 
present invention, a polymerizable vinyl compound and an epoxy compound 
are preferably used. 
The unsaturated compound may be either monofunctional or polyfunctional and 
either a monomer or an oligomer. 
Illustrative examples of the oligomer include monofunctional and 
polyfunctional urethane acrylate oligomers, epoxy acrylate oligomers and 
ester acrylate oligomers. 
Illustrative examples of the monofunctional monomer include acrylic 
compounds such as isobornyl acrylate, isobornyl methacrylate, 
dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, 
dicyclopentenyloxyethyl methacrylate, dicyclopetanyl acrylate, 
dicyclopetanyl methacrylate, bornyl acrylate, bornyl methacrylate, 
2-hydroxyethyl acrylate, cyclohexyl acrylate, 2-hydroxypropyl acrylate, 
morpholine acrylamide, morpholine methacrylamide and phenoxyethyl 
acrylate; and other monofunctional vinyl monomers such as N-vinyl 
pyrrolidone, N-vinyl caprolactam, acrylamide, vinyl acetate and styrene. 
Illustrative examples of the polyfunctional monomer include 
trimethylolpropane triacrylate, ethylene-oxide modified trimethylolpropane 
triacrylate, ethylene glycol diacrylate, tetraethylene glcol diacrylate, 
polyethylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol 
diacrylate, neopentyl glycol diacrylate, dicyclopentanyl diacrylate, 
polyester diacrylate, ethylene-oxide modified bisphenol A diacrylate, 
pentaerythritol triacrylate, pentaerythritol tetraacrylate, 
propylene-oxide modified trimethylolpropane triacrylate, propylene-oxide 
modified bisphenol A diacrylate, tris(acryloxyethyl)isocyanurate and the 
like. 
Further, illustrative examples of the epoxy compound include hydrogenated 
bisphenol A diglycidyl ether, 
3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate, 
2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy)cyclohexane-metha-dioxane, 
bis(3,4-epoxycyclohexylmethyl)adipate and the like. 
These unsaturated compounds may be used alone or in combination of two or 
more. 
The liquid photocurable resin may contain a photopolymerization initiator 
or a thermal polymerization initiator in addition to the unsaturated 
compound. 
Typical examples of the photopolymerization initiator include 
2,2-dimethoxy-2-phenyl acetophenone, 1-hydroxycyclohexylphenyl ketone, 
acetophenone, benzophenone, xanthone, fluorenone, benzaldehyde, fluorene, 
anthraquinone, triphenylamine, carbazole, 3-methyl acetophenone, Michler's 
ketone and the like. These initiators may be used alone or in combination 
of two or more. Further, they can be used in combination with an 
sensitizer such as an amine compound as required. 
Typical examples of the thermal polymerization initiator include benzoyl 
peroxide, t-butyl peroxybenzoate, dicumyl peroxide, diisopropyl 
peroxydicarbonate, t-butyl peroxide, azobisisobutyronitrile and the like. 
When an epoxy compound is used, an energy active cation initiator such as 
triphenyl sulfonium hexafluoroantimonate may be used advantageously. 
The resin composition of the present invention comprises either an 
inorganic solid particle or whisker, or both, as a reinforcing agent. 
The inorganic solid particle needs to have an average particle diameter of 
3 to 70 .mu.m. If the average particle diameter is less than 3 .mu.m, the 
viscosity of the resin composition becomes too high, thereby making it 
difficult not only to blend a predetermined amount of the inorganic solid 
particles but also to handle during optical shaping. If the average 
particle diameter is more than 70 .mu.m, though an increase in the 
viscosity of the resin composition is not so large, the diffusion of 
irradiation energy (light, for example) for curing occurs, thereby not 
only deteriorating shaping accuracy but also leading to a reduction in the 
accuracy of a shaped article due to restriction on the film thickness of 
each layer to be laminated, both of which are not preferred. 
The average particle diameter of the inorganic solid particle is preferably 
in the range of 10 to 60 .mu.m, more preferably 15 to 50 .mu.m. When the 
average particle diameter is within the above range, a resin composition 
having good balance between shapability and accuracy can be obtained 
depending on the proportion of a reinforcing agent. 
The inorganic solid particle is used as the sole reinforcing agent in the 
resin composition in an amount of 5 to 70% by volume based on the total 
volume of the liquid curable resin and the inorganic solid particle. 
If the proportion of the inorganic solid particle is less than 5% by 
volume, the characteristic properties of the inorganic solid particle are 
not developed fully. Particularly, a cured product obtained by curing the 
resin composition does not meet requirements for the mechanical properties 
of a simple mold and hence, is not put to use. If the proportion is more 
than 70% by volume, the average particle diameter of the inorganic solid 
particle usable is limited and the viscosity of the resulting resin 
composition is extremely high, thereby making it difficult to use it for 
shaping. 
The proportion of the inorganic solid particle in the resin composition is 
preferably 20 to 65% by volume, more preferably 30 to 60% by volume. This 
range is advantageously used to achieve shapability and the characteristic 
properties of a simple mold. 
Although the inorganic solid particle used in the present invention may be 
transparent or opaque, it is preferably spherical in shape, more 
preferably exactly spherical. When the inorganic solid particle is not 
spherical, the irregular reflection of irradiation energy (light, for 
example) occurs and the accuracy of a three-dimensional object obtained by 
curing the resin composition may be lost. In addition, the viscosity of 
the resin composition tends to increase. As for the sphericity of the 
inorganic solid particle, it is desired to use an inorganic solid particle 
which has a relative standard deviation defined by the following formula 
of less than 0.5. 
##EQU1## 
wherein D.sub.i (.mu.m) is a diameter of the area circle of each particle, 
D (.mu.m) is an average value of the diameter of the area circle defined 
by the following formula 
##EQU2## 
and n is the number of particles. 
Preferred examples of the inorganic solid particle include a glass particle 
(bead), talc particle and silica particle. They may be used alone or in 
combination of two or more. 
The inorganic solid particle treated with a silane coupling agent can be 
used preferably. Preferred examples of the silane coupling agent include 
amino silane, epoxy silane, vinyl silane, acryl silane and the like. 
Specific examples of the amino silane coupling agent include 
.gamma.-aminopropyltriethoxysilane, N-.beta. (aminoethyl) 
.gamma.-aminopropyltrimethoxysilane and N-.beta. (aminoethyl) 
.gamma.-aminopropylmethyldimethoxysilane. 
Specific examples of the epoxy silane coupling agent include 
.beta.-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and 
.gamma.-glycidoxypropyltrimethoxysilane. 
Specific examples of the vinyl silane coupling agent include vinyl 
trichlorosilane, vinyltriethoxysilane and 
vinyltris(.beta.-methoxyethoxysilane). 
Specific examples of the acryl silane coupling agent include 
trimethoxysilanemethacrylate. 
When the inorganic solid particle treated with such a silane coupling agent 
is used, a cured product having greatly improved mechanical strength, in 
particular, is obtained from the resulting resin composition. The silane 
coupling agent develops different degrees of curability depending on a 
liquid photocurable resin used. For instance, when an unsaturated vinyl 
compound is used as the liquid photocurable resin, an inorganic solid 
particle treated with an acryl silane coupling agent Is preferably used, 
and, when an epoxy compound is used, an inorganic solid particle treated 
with an epoxy silane coupling agent is preferably used. 
The resin composition in the present invention can use a whisker as a 
reinforcing agent in place of or in combination with the inorganic solid 
particle. 
The whisker used in the present invention needs to have an average diameter 
of 0.3 to 1.0 .mu.m, a length of 10 to 70 .mu.m and an aspect ratio of 10 
to 100. 
The preferable average diameter is 0.3 to 0.7 .mu.m, the preferable length 
is 20 to 50 .mu.m and the preferable aspect ratio is 20 to 70. 
If the aspect ratio of the whisker in use is less than 10, the effects of 
improving the mechanical strength and reducing the volume shrinkage of the 
resulting cured product cannot be obtained, and the viscosity of the resin 
composition increases disadvantageously. If the aspect ratio of the 
whisker is large, the effects of improving the mechanical strength and 
reducing the volume shrinkage of the resulting cured product are expected. 
However, if the aspect ratio is too large, the viscosity and fluid 
elasticity of the resin composition become high, resulting in a difficult 
shaping operation, a large length of the whisker and deteriorated accuracy 
of the side surface of the resulting cured product. 
The whisker is used as the sole reinforcing agent in the resin composition 
in an amount of 5 to 30% by volume based on the total volume of the liquid 
photocurable resin and the whisker. 
If the proportion of the whisker is less than 5% by volume, the 
characteristic properties of the whisker are not developed fully, and a 
cured product obtained by curing the resin composition does not exhibit 
sufficient mechanical strength. If the proportion is more than 30% by 
volume, the viscosity of the resulting resin composition becomes extremely 
high, thereby making it difficult to use it for shaping. 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
As the whisker, what has been treated with a silane coupling agent can be 
used preferably. 
Illustrative examples of the silane coupling agent are the same as those 
provided in connection with the inorganic solid particle. 
Preferred examples of the whisker include whisker of aluminum borate and 
derivatives thereof, whisker of hydroxy magnesium sulfate and derivatives 
thereof, whisker of aluminum oxide and whisker of silicon oxide. They may 
be used alone or in combination of two or more. 
When the resin Composition comprises a combination of an inorganic solid 
particle and a whisker as a reinforcing agent, the reinforcing agent is 
used in an amount of 5 to 70% by volume based on the total volume of the 
liquid curable resin and the reinforcing agent. 
Illustrative examples of the inorganic solid particle and the whisker are 
the same as those provided hereinbefore. 
Since the resin composition comprises a combination of an inorganic solid 
particle and a whisker as a reinforcing agent, the mechanical properties 
and heat resistance of the resulting cured product are significantly 
improved and the volume shrinkage of the product is greatly reduced by the 
synergism of the inorganic solid particle and whisker. 
The ratio of the volume amount of the inorganic solid particle to the 
volume amount of the whisker is preferably between 7:3 and 1:1. 
Within this range of the ratio, it is more preferred to set the proportion 
of the inorganic solid particle to 5 to 65% by volume, that of the whisker 
to 5 to 30% by volume and the total of both to 10 to 70% by volume. It is 
the most preferred to set the proportion of the inorganic solid particle 
to 10 to 50% by volume, that of the whisker to 5 to 20% by volume and the 
total of both to 20 to 60% by volume. 
The photocurable resin composition used in the present invention may 
contain a leveling agent, surfactant, organic polymer compound, organic 
plasticizer, organic filler other than those provided hereinbefore, 
inorganic filler other than those provided hereinbefore, and the like as 
required. 
Preferred examples of the organic filler include organic polymer solid 
particles having an average particle diameter of 3 to 70 .mu.m, such as 
crosslinked polystyrene polymer particles, crosslinked polymethacrylate 
polymer particles, polyethylene polymer particles and polypropylene 
polymer particles. The total amount of the organic filler and the 
inorganic solid particle is 70% by volume based on the resin composition. 
Preferably, a material constituting the mold of the present invention has a 
hardness in terms of a Rockwell surface hardness index of M-30 or more and 
a flexural modulus of 400 kg/mm.sup.2 ore more. It is possible to obtain 
these properties from a photocurable resin which is blended with the above 
reinforcing agent. When the material has such mechanical physical 
properties, it is satisfactorily usable as a material for a simple mold 
which undergoes a relatively small load. Illustrative examples of the 
simple mold include aluminum plate press molds, plastic injection molding 
molds, foaming molding molds, RIM (reaction injection molding) molds and 
vacuum casting molds. Further, to improve the durability and molding 
accuracy of a mold, it is desirable that the hardness in terms of the 
Rockwell surface hardness index be M-50 or more and the flexural modulus 
be 600 kg/mm.sup.2 or more. It is possible to obtain these properties from 
a photocurable resin blended with the above reinforcing agent and a 
special inorganic reinforcing agent. 
Preferably, the material constituting the mold of the present invention has 
a heat conductivity of 0.3 Kcal/m.multidot.Hr.multidot..degree. C. or 
more. Especially, when heat must be let escape from the inside of the mold 
to the outside like an injection mold, it is desirable that such heat 
conductivity be provided to a mold. Further, to increase the molding rate, 
the heat conductivity is preferably 0.4 
Kcal/m.multidot.Hr.multidot..degree. C. or more. 
The preferred mold in the present invention is such that the inner surface 
of the cavity for shaping a three-dimensional object is covered by a solid 
film having a thickness of 5 to 1,000 .mu.m. Due to this solid film formed 
on the inner surface, i.e., on the shaping surface of the cavity, the 
number of times of shaping a three-dimensional object in the cavity can be 
increased, that is, the service life of the mold can be drastically 
improved. 
In other words, according to the present invention, there is also provided 
a mold having a cavity for shaping a three-dimensional object, which 
comprises a photocured resin of a photocurable resin composition 
comprising: 
(A) a liquid photocurable resin, and 
(B) at least one reinforcing agent selected from the group consisting of 
inorganic solid particles having an average particle diameter of 3 to 70 
.mu.m and a whisker having an average diameter of 0.3 to 1.0 .mu.m, a 
length of 10 to 70 .mu.m and an aspect ratio of 10 to 100, and in which 
the inner surface of the cavity is covered by a film having a thickness of 
5 to 1,000 .mu.m. 
When the thickness of the solid film is less than 5 .mu.m, an effect 
obtained by forming the solid film is not satisfactory and a releasing 
effect and the extension of service life of the mold are not satisfactory. 
On the other hand, when the thickness of the solid film is more than 1,000 
.mu.m, there may occur a tendency that the effect obtained by forming the 
solid film reaches saturation, the service life of the mold is shortened 
and the molding accuracy of the mold is lowered. 
The material of the solid film may be an organic polymer, metal or metal 
oxide, for example. 
Illustrative examples of the organic polymer include a polyamide resin, a 
polyamidimide resin, a polyimide resin, a polyacrylic resin, a 
polyurethane resin, a silicon resin, a fluorinated resin, an epoxy resin, 
a polystyrene resin, a polyurethaneacrylate resin and the like. They may 
be used alone or in combination of two or more. 
Of these, a polyamidimide resin which may be liquid, a fluorinated acrylic 
resin such as a copolymer of an alkyl acrylate such as methyl methacrylate 
and a perfluoroalkyl (meth)acrylate such as perfluorooctyl (meth)acrylate 
or perfluoroisopropyl (meth)acrylate, which, is a resin soluble in an 
organic solvent having a relatively low boiling point, and a polyurethane 
acrylate resin are particularly preferred. 
These organic polymers are preferably applied to the inner surface of the 
cavity of a mold as a solution or liquid in an organic solvent, 
evaporated/dried or cured to form a solid film on the inner surface of the 
cavity. 
Illustrative examples of the metal and metal oxide include chromium metal, 
nickel metal, iron metal, zirconium metal, zinc metal, aluminum metal, 
copper metal, and oxides thereof and alloys thereof. 
The solid film formed of one of these materials can be formed on the inner 
surface of the cavity of a mold by a plating or vapor deposition method. 
A method for producing a mold of the present invention from the 
photocurable composition comprises the steps of: 
producing data representing the sections of a mold to be formed, 
forming a layer of the photocurable resin on a working surface designated 
to be exposed to light for curing generated based on the data, 
exposing the layer to light for curing to form a first sectional layer, 
applying the photocurable resin to this first sectional layer, and 
exposing the photocurable resin to light for curing to form a second 
sectional layer and bonding together the first sectional layer and the 
second sectional layer at the same time. 
These operations are repeated several times to produce a desired mold. 
The following examples are provided for the purpose of further illustrating 
the present invention, but are in no way to be taken as limiting. 
(Production of urethanated acrylic compound) 
888 Grams of isophorone diisocyanate, 906 g of morphgline acrylamide and 
1.0 g of dibutyltin laurate were charged into a 5-liter three-mouthed 
flask equipped with a stirrer, a dropping funnel with a side pipe and a 
cooling pipe, and the inside temperature was elevated to 80 to 90.degree. 
C. by an oil bath. A solution prepared by dissolving 0.7 g of methyl 
hydroquinone in 856 g of glycerine monomethacrylate monoacrylate and 
mixing them uniformly was charged into the dropping funnel having the side 
pipe which was maintained at 50.degree. C. in advance, and the contents 
were stirred to carry out a reaction for 2 hours under agitation while the 
temperature of the contents of the flask was maintained at 80 to 
90.degree. C. in a nitrogen atmosphere. After the temperature of the 
contents of the flask was reduced to 60.degree. C., 366 g of an adduct of 
pentaerythritol with 4 moles of propylene oxide which has been charged 
into the dropping funnel was dropped quickly and a reaction was further 
carried out at a content temperature of 80 to 90.degree. C. for 4 hours. 
The thus obtained urethane acrylate oligomer was taken out of the flask 
while the contents were still hot. 
(Preparation of a photocurable composition) 
2,020 Grams of urethane acrylate oligomer prepared in the above production, 
454 g of morpholine acrylamide and 1,060 g of dicyclopentanyl diacrylate 
were charged into a 5-liter three-mouthed flask equipped with a stirrer, 
cooling pipe and dropping funnel with a side pipe, which was then vacuum 
deaerated and substituted with nitrogen. 118 Grams of 
1-hydroxycyclohexylphenyl ketone (IRGACURE 184 manufactured by Chiba 
Geigy) was added under closed environment and mixed and stirred until it 
was completely dissolved. The thus obtained resin composition was a 
colorless, transparent viscous liquid. The viscosity of this liquid at 
normal temperature was 2,100 cps. 
The resulting resin composition was transferred to a 10-liter universal 
stirrer manufactured by Dalton Co. Ltd., and 27 g of SUPERDINE V201 
(manufactured of Takemoto Oil & Fat Co. Ltd.) as a leveling agent, 4,169 g 
(32%, by volume) of glass beads having an average particle diameter of 15 
.mu.m and a relative standard deviation value indicative of sphericity of 
0.3, which were treated with an acryl silane coupling agent, and 1,251 g 
(8% by volume) of an aluminum borate whisker (diameter: 0.5 to 0.7 .mu.m, 
aspect ratio: 50 to 70) (ALBOREX YS-4, manufactured by Shikoku Kasei Kogyo 
K.K.) treated with an acryl silane coupling agent were added, stirred and 
defoamed for 1 day. The thus obtained resin composition for optical 
shaping had a viscosity at 25.degree. C. of 40,000 cps. 
(Production of a mold by an optical stereoshaping method) 
Using the above obtained photocurable resin composition and an ultra high 
speed ,optical shaping system (SOLIFORM 500, manufactured by Teijin Seiki 
Co. Ltd), a water-cooled Ar laser beam (output: 500 mW, wavelength: 333, 
351, 364 m.mu.) was irradiated perpendicular to the surface of an object 
to carry out optical shaping with an irradiation energy of 20 to 30 
mJ/cm.sup.2 at a slice pitch (thickness of a laminate) of 0.05 mm in an 
average shaping time of 2 minutes per layer to form a cavity/core mold 
shown in FIG. 1. The thus obtained mold was washed with isopropyl alcohol 
to remove the resin solution adhered to the mold and post cured with an 
ultraviolet ray of 3 KW for 10 minutes and then at 150.degree. C. for 30 
minutes. 
A dumbbell test piece in conformity of JIS standard 7113 was stereoshaped 
similarly. The thus obtained test piece was measured for its tensile 
property in accordance with JIS standard K7113 and the results are as 
follows. 
tensile strength 6.3 kg/mm.sup.2 
tensile elongation 1.4% 
elastic modulus in tension 1,450 kg/mm.sup.2 
heat conductivity 0.43 Kcal/m.multidot.Hr.multidot..degree. C. 
EXAMPLE 1 
The above optically stereoshaped cavity/core mold was machined to form an 
extrusion pin, gate hole and the like and a solution of 30 parts by weight 
of a copolymer of methyl methacrylate, perfluoropentyl acrylate and butyl 
acrylate in a ratio of 6/2/2 dissolved in 70 parts by weight of a mixture 
solvent consisting of methyl cellosolve, methyl ethyl ketone and isopropyl 
alcohol in a ratio of 60/10/30 was uniformly coated onto the molding 
surface by a gun spray. One hour after coating, the mold was dried in air 
and heated in an oven at 80.degree. C. for 30 minutes to obtain a molding 
mold. The thickness of the polymer film was 30 .mu.m. The molding mold was 
set on a die-set in an injection molding machine with a pressure of 50 
tons and the injection molding was carried out, using an ABS resin as a 
resin, under conditions of an injection temperature of 200.degree. C. and 
an injection pressure of 95 Kgf/cm.sup.2 while a release agent KF96 
manufactured by Shin-Etsu Chemical Co. Ltd. was sprayed onto the molding 
surface to produce a mold at intervals of 1 minute. No damage to the mold 
was seen at all after 385 shaped products were obtained. 
EXAMPLE 2 
In place of the fluorine-based acrylate polymer film used in Example 1, a 
mixture of 60 parts by weight of the above synthesized photocurable resin 
composition and 40 parts by weight of isopropyl alcohol was sprayed onto 
the molding surface with a gun spray in the same manner as in Example 1. 
After coating, the mold was dried under heat in the oven at 80.degree. C. 
for 30 minutes to remove isopropyl alcohol and post-cured with a 3 KW 
ultraviolet ray for 10 minutes and then 150.degree. C. for 30 minutes. 
The thickness of the polymer film on the molding surface of the thus 
obtained mold was 40 .mu.m. When an ABS resin was injection molded in the 
same manner as in Example 1, 250 shaped products were obtained. 
EXAMPLE 3 
In place of the fluorine-based acrylate polymer film as used in Example 1, 
a dilute solution prepared by diluting 60 parts by weight of the Coronate 
L manufactured by Nippon Polyurethane Co. Ltd. with 40 parts by weight of 
xylene was coated onto the molding surface by a gun spray in the same 
manner as in Example 1. After coating, the mold was heated in an oven at 
80.degree. C. for 30 minutes and then 150.degree. C. for 30 minutes. 
The thickness of the polymer film on the molding surface of the thus 
obtained mold was 60 .mu.m. When an ABS resin was injection molded in the 
same manner as in Example 1, 230 shaped products could be obtained. 
EXAMPLE 4 
An ABS resin was injection molded in the same manner as in Example without 
forming a polymer film. When 10 shaped products were obtained, damage to 
part of the mold was observed and when a 16th shaped product was molded, 
the shaped product was adhered to the mold and experiments could not be 
continued any longer. 
EXAMPLE 5 
A very thin polymer film was formed in Example 1. The thickness of the film 
was 3 .mu.m. When injection molding was carried out in the same manner, 17 
shaped products were obtained. However, when 15 or more shaped products 
had been molded, damage to part of the mold was observed and when an 18th 
shaped product was molded, the complete destruction of the mold was 
observed.