JP3001050B2 - Photoinjection photosensitive resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive resin composition for casting used for producing a duplicate model by casting.

[0002]

2. Description of the Related Art A small number of prototype models and small-scale production of duplicate models are obtained by taking a silicone rubber mold from a master model, injecting a thermosetting resin into the mold in a vacuum, and then heating and curing. Has been done in However, thermosetting resins are usually of two-part type, and the mixing of the two parts takes a short time until the start of curing. However, depending on the case, there is a problem in that curing may start during the pouring operation, resulting in a defective product.
Furthermore, the container used for mixing and casting must be washed each time before the resin is cured, which is troublesome. In addition, this method requires a long time of about two hours for heat curing, and requires one day. There was also a disadvantage that the number that could be copied was limited.

[0003] On the other hand, Japanese Patent Application Laid-Open No. 58-80587 discloses a method in which a one-part UV curable synthetic resin is injected into a transparent silicone rubber mold and irradiated with UV light under reduced pressure. A method of replicating a plastic watch case is shown. As a resin which is cured by ultraviolet rays, a resin obtained by adding benzophenone as a sensitizer to a synthetic resin for casting such as a spirane resin, or an unsaturated polyester resin containing a reaction accelerator is used.

Japanese Patent Application Laid-Open No. 3-114711 discloses a method of injecting a photosensitive resin into a transparent silicone rubber mold and curing the resin by irradiating ultraviolet rays, wherein a diacrylate of an ethylene oxide adduct of bisphenol A is used as the photosensitive resin. And a mixture of phenyl glycidyl ether and an acrylic acid ester to which a photopolymerization initiator is added.

Further, JP-A-7-124962 discloses a urethane poly (meth) acrylate having two or more (meth) acryloyloxy groups, a specific diallyl compound, and an aliphatic polythiol compound having two or more thiol groups. , An active energy ray-curable liquid resin composition obtained by adding an active energy ray polymerization initiator is injected into a transparent silicone rubber mold, and then irradiated with active energy rays to cure the resin molded article. Have been. Further, the present applicant has disclosed a photosensitive resin composition in which the disadvantage that the photosensitive resin is easily broken is improved as disclosed in
No. 244,044 and Japanese Patent Application Laid-Open No. 8-323778.

[0006] A high quality dimensional accuracy is required for a duplicate product obtained by casting, but the photosensitive resin shrinks when cured by ultraviolet rays, so that the size of the duplicate product obtained is smaller than that of the master model. There was a problem that it would be. Although it is possible to correct the shrinkage by making the master model large, it is inefficient to make a prototype model for initial shape evaluation and a master model for duplication separately, and the range of use is limited I had to become something.

It is desired that some of the replica models of the prototype be colored in an opaque color such as milky white, such as ABS, depending on the application. However, in order to make the photosensitive resin opaque, for example, titanium oxide or carbon is used. It was difficult to color opaquely, for example, when black was added, the sensitivity was lowered and the thickness that could be cured was limited. Coloring of the duplicates has been carried out, for example, by applying a coating treatment. However, in addition to an increase in the number of coating steps, there have been problems such as being unsightly when the coating is peeled off.

Further, in order to inject the photosensitive resin composition into the silicone rubber mold and to irradiate and cure it with ultraviolet rays, an exposing machine having a vertically arranged light source as used in printing plate manufacturing is used. Exposure to light does not sufficiently cure the side surface of the model, resulting in a defective product. To make a mold with silicone rubber requires a long time of 10 hours or more to cure, so from the user's request to evaluate a replicated product within the shortest possible time after designing a model shape, There has also been a desire for use in combination with time-curable silicone rubber.

[0009]

SUMMARY OF THE INVENTION A method for producing a replica model by preparing a mold from an ultraviolet-permeable silicone rubber based on a master model, injecting a photosensitive resin composition into the mold and irradiating the mold with ultraviolet rays. In the present invention, to provide a duplicate model with high dimensional accuracy, to provide a photosensitive resin composition from which a duplicate model having the property of being hard and resistant to cracking can be obtained, and further, that the duplicate to be produced is colored in an opaque color Another object of the present invention is to provide a photosensitive resin composition for casting that can be cured with ultraviolet light even in a model having a large wall thickness, and is suitable for obtaining a duplicate product in a short period of time with a simple operation. It is an object of the present invention to provide a photosensitive resin composition for casting.

[0010]

Means for Solving the Problems The present inventors have set forth the above object as an object of the present invention is to provide a molecule having an ethylenically unsaturated bond in a molecule.
Amount of 800-9000 polymer, and ethylenically unsaturated
Ethylenic desaturation having a molecular weight of less than 800 having a sum bond
Compound and the UV transmittance at a thickness of 1 mm is 0.0
5 to 5% for UV-curable casting
The present inventors have found that the problem can be solved by using a photosensitive resin composition, and have completed the present invention.

Hereinafter, the present invention will be described in detail. The photosensitive resin composition for casting used in the present invention is a photosensitive resin composition having a UV transmittance of 0.05 to 5% at a thickness of 1 mm. The ultraviolet transmittance referred to in the present invention is 360 to 370 n
of ultraviolet light emitted from an ultraviolet fluorescent lamp centered on m
It is determined from the intensity ratio before and after the light enters the photosensitive resin composition for casting molded to a thickness of 1 mm. That is, assuming that the UV intensity before incidence of the photosensitive resin composition for casting having an optical path length of 1 mm is A ′ and the UV intensity after transmission is B ′, it is obtained from the formula of B ′ ÷ A ′ × 100. .

In the actual measurement, the photosensitive resin composition for casting was sandwiched at a thickness of 1 mm between two soda glass plates laminated with a polyester film, the ultraviolet intensity B after transmission was measured, and the polyester film was laminated. It can be obtained from the intensity A of the ultraviolet light transmitted through the laminated two soda glasses by the formula B ÷ A × 100. The ultraviolet absorber added to the photosensitive resin composition for adjusting the ultraviolet transmittance may be any as long as it has absorption in the ultraviolet region, and is used by being dissolved or dispersed in the photosensitive resin composition for casting. Even those having a small absorption of ultraviolet rays exist in the photosensitive resin composition in a dispersed state and reflect and scatter ultraviolet rays, so that those which lower the ultraviolet transmittance as a result can be used.

Examples of UV absorbers include benzotriazole UV absorbers, benzophenone UV absorbers,
Examples include cyanoacrylate-based ultraviolet absorbers. Specifically, 2- (2'-hydroxy-5'-
Methylphenyl) benzotriazole, 2- (2′-hydroxy-5′-tert-butylphenyl) benzotriazole, 2- (2′-hydroxy-3′-tert)
-Butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3 ', 5'-
Di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-amylphenyl) benzotriazole,
2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2-dihydroxy-4,4'-dimethoxybenzophenone, 2-ethylhexyl-2-cyano- 3,3′-diphenyl acrylate and the like can be exemplified.

In addition, commercially available dyes and pigments can be used as long as they have absorption in the ultraviolet region. In addition, it is often necessary that the color of the replicated product by light casting be colored milky white or black rather than colorless. In order to meet such demands, it is convenient to use a UV-ray transmittance adjusting agent which gives coloring or opacity.

[0015] Examples of those which have the effect of imparting opacity or coloring to the obtained duplicates include inorganic fillers such as calcium carbonate, magnesium hydroxide, magnesium carbonate, magnesium oxide and zinc oxide. . Titanium oxide and carbon black can also be used as an ultraviolet transmittance adjuster, but since they have a large ultraviolet absorption effect, it is not possible to add an amount sufficient to give a sufficient opacity or color. For the purpose, it is necessary to use in combination with other dyes.

Calcium carbonate is most preferred as the milky white ultraviolet ray transmittance adjusting agent. Since there is a strong demand for beige or milky white as the color of the replicated product by light casting, it is particularly useful to color the replicated product by using calcium carbonate as an ultraviolet transmittance controlling agent.

The shape of the inorganic filler such as calcium carbonate is not particularly limited as long as it can be dispersed in the photosensitive resin composition, and a granular or fibrous material can be used. In the case of granular materials, those having a particle size of 10 μm or less are usually used. If the particle size is large, it becomes easy to separate and settle during storage after being added to and mixed with the photosensitive resin composition.
Below, more preferably 2 μm or less is suitable. In the case of a fibrous material, a photosensitive resin composition for casting to which a resin having a thickness of 1 μm or less and a length of 5 μm or more has been added and mixed is preferably not easily separated and settled when stored for a long time. In this respect, those having a thickness of 0.2 μm or less and a length of 15 μm or more are more preferable.

From the viewpoint that inorganic fillers such as calcium carbonate hardly separate and settle during storage of the photosensitive resin composition for casting, fibrous ones are superior to spherical ones. Further, even when separated during storage, it can be used by stirring again.

The inorganic filler such as calcium carbonate is added in a range of 3 to 20 parts by weight based on 100 parts by weight of the photosensitive resin composition so that the ultraviolet transmittance falls within a predetermined range. If less than this, sufficient opacity cannot be obtained,
If the amount is too large, the elongation at break of the duplicated product becomes small, so that the duplicated product becomes liable to be broken or a portion having a large thickness is hardly cured, which is not preferable. It is more preferably in the range of 5 to 15 parts by weight.
A dye or the like can be used in addition to an inorganic filler such as calcium carbonate in order to adjust the color of the obtained duplicate.

The method of obtaining the photosensitive resin composition for casting of the present invention by adding and mixing an inorganic additive to the photosensitive resin composition includes adding an inorganic filler to the photosensitive resin composition and stirring and dispersing the mixture. Alternatively, when the constituent components of the photosensitive resin composition are mixed, an inorganic additive may be added and stirred and mixed at the same time.
At this time, heating may be performed to lower the viscosity of the photosensitive resin composition to facilitate mixing.

The inorganic additive hardly dissolves in the photosensitive resin composition and makes the photosensitive resin composition opaque because it reflects and scatters incident light. Calcium carbonate, magnesium carbonate, magnesium hydroxide, magnesium oxide, etc. also absorb a small amount of ultraviolet light, so they can reduce the ultraviolet transmittance by scattering in the resin to achieve a predetermined ultraviolet transmittance. Because it is absorbed by the photoinitiator in the resin composition and used to initiate the curing reaction, it is possible to cure even a thick part, and it is opaque,
It is preferable because it can satisfy the contradictory characteristics of being able to cure a thick material. In particular, calcium carbonate is preferable because it can be completely opaque and can have a predetermined ultraviolet transmittance.

The thickness of the duplicate model is usually 2 to 3 mm, but sometimes from 4 mm to 6 mm. With the photosensitive resin composition for casting of the present invention, the thickness in this range can be cured. I can do it.

Surprisingly, the photosensitive resin composition for casting having an ultraviolet transmittance of 0.05 to 5% at a thickness of 1 mm has an effect of improving the dimensional accuracy of a duplicate product prepared using the same. are doing. This is because the difference in ultraviolet intensity between the light incident surface and the inside of the photosensitive resin composition for casting is large, so the difference in time required for each part to be cured is large, and the peripheral part is cured first. Since the resin that is shrunk by curing shrinkage is supplied through the uncured central portion, the completed model retains the original dimensions, and such an effect is exhibited.

The dimensions of the duplicate are ±
It is required to be within 0.3%, but this can be achieved by the method of the present invention. The ultraviolet transmittance of the photosensitive resin composition for casting of the present invention is 0.05 to 5
% In the range of 0.2 to 3 in that the dimensional accuracy is secured and a thick material can be cured in a short time.
% Is more preferable. The ultraviolet transmittance is represented by the ultraviolet transmittance of the photosensitive resin composition for casting molded to a thickness of 1 mm.

In the present invention, the composition of the photosensitive resin composition used for adjusting the ultraviolet transmittance to 0.05 to 5% to obtain a photosensitive resin composition for casting is required for producing a duplicate product. Considering the balance with other properties such as hardness and resistance to cracking, a photosensitive composition comprising an ethylenically unsaturated compound having a molecular weight of 800 to 9000 having an ethylenically unsaturated bond in the molecule and having a molecular weight of less than 800 as an essential component the resin composition Ru used. The photosensitive resin composition usually contains a photopolymerization initiator.

Examples of the polymer having a molecular weight of 800 to 9000 and having an ethylenically unsaturated bond in the molecule include unsaturated polyurethane and unsaturated polyester. From the viewpoint of the balance between hardness and resistance to cracking, unsaturated polyurethane is more preferable. The unsaturated polyester is obtained by a dehydration condensation reaction between a diol compound and a dicarboxylic acid compound having at least one kind having an unsaturated bond. The unsaturated polyurethane is obtained by reacting a diol compound and a diisocyanate compound, and then reacting a compound having an ethylenically unsaturated bond with a hydroxyl group or an amino group or a compound having an ethylenically unsaturated bond with an isocyanate group.

In a method of first synthesizing a polyurethane polymer having isocyanate groups at both ends and reacting it with a compound having both a hydroxyl group and an ethylenically unsaturated bond, the compound having both a hydroxyl group and an ethylenically unsaturated bond is not reacted with both ends. In order to facilitate the reaction with the polyurethane polymer having an isocyanate group and to terminate the reaction in a short time by suppressing side reactions, the reaction is performed by adding the number of hydroxyl groups to the number of isocyanate groups in excess. Is preferred. Usually, an excess of about 2 to 5 times is added. The result is a mixture of a polyurethane polymer having ethylenically unsaturated bonds and an excess of hydroxyl-containing ethylenically unsaturated compounds.

In a method of first synthesizing a polyurethane polymer having hydroxyl groups at both ends and reacting it with a compound having an isocyanate group and an ethylenically unsaturated bond simultaneously, the compound having both an isocyanate group and an ethylenically unsaturated bond is a polyurethane polymer. It is generally added in the same or less range as the number of hydroxyl groups of the polymer, but in this case, in order to facilitate stirring and suppress side reactions,
It is preferable to reduce the viscosity of the reaction system by using a component not involved in the urethanization reaction as a diluent. When a compound having both an isocyanate group and an ethylenically unsaturated bond is excessively added, it is necessary to eliminate the isocyanate group by adding a compound having active hydrogen such as a hydroxyl group after the reaction.

As the diol compound, compounds having two hydroxyl groups in one molecule, for example, polyester glycol such as polypropylene glycol adipate diol, polyneopentyl glycol adipate diol, polycaprolactone diol, polyvalerolactone diol, polyethylene glycol, polypropylene Examples thereof include polyether diols such as glycol and polytetramethylene glycol. The molecular weight of the diol compound is usually about 400 to 2,000, but from the viewpoint of obtaining a stronger one,
It is preferable to use one having a molecular weight of about 100 to 1,000.

Examples of the diisocyanate compound include compounds having two isocyanate groups, such as tolylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, and isophorone diisocyanate. Among these, tolylene diisocyanate is preferable because it does not increase the viscosity so much and a hard and tough product is easily obtained.

Examples of the compound having both a hydroxyl group and an ethylenically unsaturated group include hydroxyethyl methacrylate,
Hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, N-
Examples include methylol acrylamide, polyoxyethylene glycol monomethacrylate, polyoxypropylene glycol monomethacrylate, and the like. Among these, hydroxyethyl methacrylate and hydroxypropyl methacrylate are preferred from the viewpoint of hardness and toughness, and hydroxypropyl methacrylate from which higher hardness is obtained is most preferred. As a compound having both an isocyanate group and an ethylenically unsaturated group, for example, a compound obtained by adding a diisocyanate compound one-to-one to a compound having a hydroxyl group and an ethylenically unsaturated group at the same time can be mentioned.

The unsaturated polyurethane obtained as described above preferably has a number average molecular weight of 800 to 9000 determined by GPC measurement using polystyrene as a standard. Although having the advantage that the viscosity of the obtained photosensitive resin composition can be lowered as the molecular weight is smaller, when the molecular weight is smaller than this, the cured product becomes hard and brittle and loses toughness, and when cutting and removing unnecessary portions of a duplicated product, It is not preferable because cracks easily occur. If the molecular weight is large, the toughness of the cured product is easy to secure, but if it is larger than this, the viscosity of the obtained photosensitive resin composition increases, making it difficult to spread the photosensitive resin to every corner of the mold in the casting process In addition to the above, there are unfavorable aspects of the properties of the duplicated product, such as softening of the obtained cured product.

Examples of the ethylenically unsaturated compound include N-methylol acrylamide, diacetone acrylamide,
N-substituted acrylamides such as N, N-dimethylacrylamide, N- (2-methoxyethyl) acrylamide, N-methylol methacrylamide, N, N-dimethylmethacrylamide, N-substituted methacrylamides, hydroxyethyl methacrylate and acrylate, hydroxy Hydroxyalkyl methacrylates and acrylates such as propyl methacrylate and acrylate, ethylene glycol dimethacrylate and acrylate, diethylene glycol dimethacrylate and diacrylate, tetraethylene glycol dimethacrylate and diacrylate such as polyoxyethylene glycol dimethacrylate and diacrylate,

Polyoxypropylene glycol dimethacrylate and diacrylate such as propylene glycol dimethacrylate and diacrylate, dipropylene glycol dimethacrylate and diacrylate, tripropylene glycol dimethacrylate and diacrylate, butanediol dimethacrylate and diacrylate, hexanediol Examples thereof include dimethacrylate and diacrylate, nonanediol dimethacrylate and diacrylate, trimethylolpropane trimethacrylate and triacrylate, and diacrylate and dimethacrylate having a bisphenol A skeleton.

Among these, N-methylolacrylamide and methacrylamide are preferred from the viewpoint of increasing the hardness and heat resistance without significantly lowering the toughness, and from the viewpoint of increasing the toughness without significantly lowering the hardness and heat resistance. Diacetone acrylamide is preferred. Further, from the viewpoint of lowering the viscosity of the photosensitive resin composition and increasing the elongation properties and hardness, etc., hydroxyethyl methacrylate, hydroxypropyl methacrylate, trimethylolpropane trimethacrylate, etc., while further maintaining toughness From the viewpoint of increasing hardness and heat resistance, diacrylate and dimethacrylate having a bisphenol A skeleton are suitable. Usually, these are used in combination.

Usually, an ethylenically unsaturated compound is used in an amount of 60 to 200 parts by weight based on 100 parts by weight of a polymer having an ethylenically unsaturated bond in a molecule and having a molecular weight of 800 to 9000.

As the photopolymerization initiator used in the photosensitive resin composition, a photopolymerization initiator capable of absorbing ultraviolet rays having a wavelength of 300 to 400 nm and initiating polymerization, and a known one is used. For example, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin-n
Benzoin derivatives such as -butyl ether, α-methylol benzoin methyl ether, α-methoxy benzoin methyl ether, α-ethoxy benzoin ethyl ether, 1-hydroxycyclohexylphenylacetophenone, 1-benzyl-1-dimethylaminopropyl-p-morpholinoketone And the like.
Among them, α-methoxybenzoin methyl ether is particularly preferable because it can be cured to a material having a high curing rate and a large thickness.

The photopolymerization initiator may be used in any amount as long as it is an effective amount for initiating polymerization, but is usually used in the range of 0.1 to 10% by weight based on the total weight of the photosensitive resin composition. If the amount is less than this, the photopolymerization initiation efficiency becomes poor, and in particular, the curing on the surface in contact with the silicone rubber becomes poor, and the adhesiveness may remain on the surface of the duplicate product, which is not preferable. Conversely, if the amount is too large, the mechanical properties of the cured product are undesirably reduced. A preferred range is 0.5 to 4% by weight, and a more preferred range is 1 to 4% by weight.
~ 2.5% by weight.

In addition, a stabilizer such as a known thermal polymerization inhibitor can be added in order to secure the stability during the production or storage of the photosensitive resin. Examples of such stabilizers are p-methoxyphenol, 2,6-di-t-
Butyl-p-cresol and the like can be mentioned.

The viscosity of the photosensitive resin composition at 20 ° C. is preferably 300 P or less, more preferably 200 P or less, in order to make it easy for air bubbles mixed during the work to escape and to spread to every corner of the silicone rubber mold. Is 150P
It is desirable that: The viscosity of the photosensitive resin composition can be reduced by increasing the blending ratio of the ethylenically unsaturated compound, particularly the liquid ethylenically unsaturated compound. Among the liquid ethylenically unsaturated compounds, those having a small molecular weight are particularly effective in lowering the viscosity. It is also effective to add a liquid plasticizer, such as silicone oil, in a range that does not significantly affect other properties, in order to reduce the viscosity.

When the viscosity of the photosensitive resin composition for casting is high, the viscosity during use can be lowered by increasing the temperature of the photosensitive resin composition at the time of casting. Must be used in a temperature range where such deterioration does not occur.

The silicone rubber used as a mold in the present invention may be of any type as long as it has a property of transmitting ultraviolet rays. Normally, a commercially available RTV transparent silicone rubber which is curable at room temperature is used. A silicone rubber or an ultraviolet-curable type can be used as long as it can transmit ultraviolet rays to a degree necessary for curing the photosensitive resin for casting.

RTV silicone rubber which is a room temperature curing type is a two-part composition, and is difficult to handle and requires one night to cure. An ultraviolet curing type is usually one-part and easy to handle, and cures 10 to 20 times. Since it takes only a short time of the order of minutes, it is also suitable from the viewpoint of creating a mold in a short time.

Silicone rubbers are classified according to their curing mechanism into addition type and condensation type. However, the condensation type is not preferred in terms of dimensional accuracy because the low molecular weight compound produced during condensation shrinks when it goes out of the system. An additional type without such a thing is suitable.

By using the photosensitive resin for casting of the present invention, a resin having a high dimensional accuracy of 0.3% or less can be obtained, but a resin having a higher dimensional accuracy can be obtained depending on the shape and use of the model. If required, set the temperature of the silicone rubber mold at the time of injecting the casting resin into the mold and irradiating it with ultraviolet light, rather than the temperature at which the silicone rubber is cured to form the mold. It is also effective to increase the temperature up to 50 ° C. Since the thermal expansion of the silicone rubber is several steps larger than that of the photosensitive resin composition for casting, the photosensitive resin composition for casting is cured in a state where the silicone rubber mold is swollen from the size of the master model. Even when the temperature of the cured photosensitive resin for casting decreases, the shrinkage due to the temperature difference is small, so that the amount of shrinkage during curing is corrected, and a duplicate product with better dimensional accuracy can be obtained.

The point that it is easy to keep the curing temperature constant is 2
In general, the silicone rubber is cured at 5 to 40 ° C., and the temperature of the silicone rubber mold is desirably 80 ° C. or less in consideration of the ease of handling of the silicone rubber mold during the casting operation. In addition, if the temperature difference between the silicone rubber at the time of mold production and casting is too large, the size of the duplicate product obtained will be larger than the master model and may worsen, so it is necessary to keep the temperature difference within an appropriate range. There is.

The light source used for photocuring is 300 to 400.
Anything that emits ultraviolet light having a wavelength of nm may be used, and an ultraviolet fluorescent lamp, a high-pressure mercury lamp, a metal halide lamp, a xenon lamp, or the like that is usually used for curing a photosensitive resin can be used.

Unlike the case of making a printing plate or baking a resist, the production of a duplicate model requires that ultraviolet rays be irradiated from the up, down, left, right, front, rear, left, right, front and rear directions during photocuring, and is used for that purpose. It is desirable that the light sources are arranged in six directions, that is, up, down, left, right, front and rear. Although the number of light source arrangements can be reduced by using a reflector, it is necessary to determine the shape and arrangement of the reflectors so that light is emitted from six directions even in such a case. If light irradiation is performed only from the same vertical direction as that for preparing the printing plate, the portion corresponding to the side surface is insufficiently cured, resulting in a defective product, which is not preferable. In order to cure a large-sized object, it is preferable to perform exposure while moving the inside of the light source arranged in a cylindrical exposure machine in which light sources are arranged vertically and horizontally by a conveyor or the like.

[0049]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these. The measurement of the ultraviolet transmittance in the present example was performed as follows. Thickness 1
Two pieces of soda glass having a thickness of 4 mm to which a 2 μm polyester film is adhered are prepared. 37
A 60 W ultraviolet fluorescent lamp (Philips 10R) having a center wavelength of 0 nm is placed under a light source in which ten tubes are arranged, and an ultraviolet intensity meter (UV manufactured by ORC) is placed under these two glasses.
LIGHT MEASURE, MODEL UV-MO
When the sensor of 2) was placed and the ultraviolet intensity A was measured, it was 4.9 mW / cm ² .

Next, a Teflon spacer having a thickness of 1 mm is placed on the polyester film of one glass plate, the photosensitive resin for casting to be measured is poured into the inside thereof, and the other glass plate is poured with the polyester film. It was laminated so as to be in contact with the photosensitive resin composition for a mold and molded to a thickness of 1 mm. In this state, the ultraviolet light intensity B passing through the laminate was placed under the light source, and the ultraviolet light transmittance was calculated as B ÷ A × 100.

[0051]

【Example】

Example 1 Using a master model made of ABS having a thickness of 2 mm and having a shape shown in Fig. 1, a transparent silicone rubber KE-1606 (manufactured by Shin-Etsu Chemical Co., Ltd.) of room temperature curing type which was previously defoamed under vacuum was cured at 40C. To prepare a casting mold. A 2-L separable flask was charged with 1000 g of polycaprolactone diol having a molecular weight of 500, and 410 g of tolylene diisocyanate was added thereto to carry out a urethanization reaction to obtain a polymer having both ends having isocyanate groups. Then 2
-410 g of hydroxypropyl methacrylate (of which 30
(7 g was added in excess as a diluent monomer) and reacted with an isocyanate group of the polymer to obtain a urethane polymer having a methacrylate group at both terminals and a number average molecular weight of 8,000.

120 g of this polymer (including 20 g of 2-hydroxypropyl methacrylate as a diluent monomer), 20 g of N-methylolacrylamide, 20 g of methacrylamide, 40 g of 2-hydroxypropyl methacrylate, and α-methoxybenzoin methyl ether 5 g
g, 2,6-di-t-butyl-p-cresol 0.2
g, and 20.5 g of calcium carbonate having an average particle size of 0.7 μm (trade name: Softon 3200, manufactured by Bihoku Powder Chemical Industry Co., Ltd.)
Was mixed to obtain a photosensitive resin composition for casting having a viscosity at 20 ° C. of 80P. The UV transmittance of this photosensitive resin composition for casting at a thickness of 1 mm was 0.57%.

This photosensitive resin composition for casting, which has been heated to 40 ° C. in advance, is stirred and defoamed under reduced pressure, poured into the silicone rubber mold heated to 65 ° C., and then has a center wavelength of 370 nm. The silicone rubber mold was placed in an exposing machine in which 40 W ultraviolet fluorescent lamps having the above-mentioned structure were arranged in six directions, up, down, left, right, front and rear, and ultraviolet irradiation was performed for 10 minutes. Thereafter, the mold was opened and a duplicate made of the cured photosensitive resin was taken out. The resulting replica showed a slightly yellowish milky white color and was opaque. The Shore D hardness at 20 ° C. of the duplicate was 83 degrees, and no cracking occurred even when cut with a nipper. The dimensions of each location of this duplicate were measured using calipers. Table 1 shows the results.

Examples 2-A and B A photosensitive resin composition for casting was obtained in which the amount of calcium carbonate added to the photosensitive resin composition of Example 1 was changed. Casting was performed in the same manner as in Example 1 using these. In each case, opaque duplicates were obtained. Table 1 shows the results of measuring the dimensions of the obtained duplicate using calipers.

Example 3 A silicone rubber mold was prepared from an ABS plate having a thickness of 6 mm and a length of 50 mm and a width of 20 mm in the same manner as in Example 1, and the photosensitive resin composition of Example 1 was used. After pouring into a mold and irradiating with ultraviolet rays in the same manner as described above, a completely cured opaque plate-like replica was obtained.

EXAMPLE 4 300 g of poly-1,4-butylene glycol adipate diol having a molecular weight of 510, 52.5 g of polypropylene glycol also having a molecular weight of 960, and 173 g of tolylene diisocyanate were reacted with each other to obtain isocyanate groups at both ends. The obtained polymer was obtained. Then 2-
303 g of hydroxypropyl methacrylate (of which 202
g was added in excess as a diluent monomer) and reacted with the isocyanate group of the polymer to obtain a urethane prepolymer having a methacrylate group at both terminals and having a number average molecular weight of 2300.

124 g of this prepolymer (24 g of 2-hydroxypropyl methacrylate as diluent monomer)
), 2-hydroxypropyl methacrylate 26
g, 7 g of tetraethylene glycol dimethacrylate,
15 g of a reaction product of propylene oxide adduct of bisphenol A and glycidyl methacrylate (trade name 3002M, manufactured by Kyoeisha Yushi Co., Ltd.), 2,2-dimethoxy-2-
3 g of phenylacetophenone and 0.2 g of 2,6-di-tert-butyl-p-cresol were mixed and dissolved to obtain a photosensitive resin composition. Then, 17 g of fibrous calcium carbonate (trade name: Wiscal A, manufactured by Maruo Calcium Co., Ltd.) was added and mixed to obtain a photosensitive resin composition for casting having a viscosity of 100P at 20 ° C. The ultraviolet transmittance of this photosensitive resin composition for casting was 1.2%.

A transparent silicone rubber mold prepared in the same manner as in Example 1 heated to 65 ° C.
The above-mentioned photosensitive resin composition for casting, which had been heated and defoamed under reduced pressure, was poured under reduced pressure. After returning to normal pressure, a 10 mm thick UV-free polymethyl methacrylate plate (Delaglass K, color number 3 manufactured by Asahi Kasei Kogyo Co., Ltd.)
002) and fixed using a transparent tape, and a silicone rubber mold supported by a polymethyl methacrylate plate was placed in an exposing machine in which 40 W ultraviolet fluorescent lamps were arranged in six directions, up, down, left, right, front and rear, and ultraviolet irradiation was performed for 10 minutes. .

After the irradiation, the mold was opened, and a duplicate made of the cured photosensitive resin was taken out. The resulting replica showed a slightly yellowish milky white color and was opaque. The Shore D hardness of the duplicate at 20 ° C. was 84 degrees, and no cracking occurred even when cut with a nipper.
When the dimensions of each location of the duplicate were measured, the shrinkage was 0.08 to 0.2%, which was almost the same as that in Example 1.

Example 5 Instead of 20.5 g of calcium carbonate of Example 1, an ultraviolet absorber 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl-)-5-chlorobenzotriazole was used. The same photosensitive resin composition for casting as in Example 1 was obtained except that 041 g was added and mixed. The ultraviolet transmittance of this photosensitive resin composition was 0.92%. The photosensitive resin composition for casting heated to 50 ° C. was stirred and defoamed under reduced pressure, and then poured into the same silicone rubber mold as in Example 1 heated to 65 ° C., and the same as in Example 1. UV irradiation was performed. Table 2 shows the measurement results of the dimensions of each of the obtained duplicates. In addition, the Shore D hardness at 20 ° C. of this duplicate was 82 degrees, and no cracking occurred even when cut with a nipper.

Comparative Example 1 A duplicate was produced in the same manner as in Example 5 except that the same photosensitive resin composition for casting was used as in Example 1 except that calcium carbonate was not added. Table 1 shows the measurement results of the dimensions at each location of the duplicate. The ultraviolet transmittance of this photosensitive resin composition was 6.7%.

Examples 6-a and b The ultraviolet absorbent 2- (2'-hydroxy-3'-tert-butyl-) in the photosensitive resin composition for casting of Example 5 was used.
5'-methylphenyl) -5-chlorobenzotriazole was added in an amount of 0.082 g (Example 6-a) and 0.1%.
By changing 123 g (Example 6-b), photosensitive resin compositions for casting having different ultraviolet transmittances were obtained. Using this photosensitive resin composition for casting, duplicates were produced in the same manner as in Example 5, and the dimensions at each location were measured. Table 2 shows the results.

[0063]

[Table 1]

[0064]

[Table 2]

[0065]

By using the photosensitive resin composition for casting of the present invention, a duplicate model having high dimensional accuracy can be obtained. In addition, even opaque and thick replicas can be obtained with high dimensional accuracy. Furthermore, a hard and hard-to-break duplicate model can be created in a defect-free form.

[Brief description of the drawings]

FIG. 1 is an example of a plan view showing a shape of a master model used in Embodiment 1 of the present invention.

Continuation of the front page (56) References JP-A-2-14207 (JP, A) JP-A-7-26060 (JP, A) JP-A-59-91111 (JP, A) JP-B-48-44931 (JP, A) , B1) (58) Field surveyed (Int. Cl. ⁷ , DB name) C08F 2/46-2/50

Claims (4)

(57) [Claims] 1. The compound has an ethylenically unsaturated bond in the molecule.
Polymer having a molecular weight of 800 to 9000, and ethylene
Ethylenic having a molecular weight of less than 800 and having an unsaturated bond
An ultraviolet curable composition containing an unsaturated compound and having an ultraviolet transmittance of 0.05 to 5% at a thickness of 1 mm .
A photosensitive resin composition for casting. 2. A tree fat composition according to claim 1, characterized by containing an ultraviolet absorber. 3. A tree fat composition according to claim 1, characterized by containing an inorganic filler. 4. A calcium carbonate, magnesium carbonate, magnesium hydroxide, tree fat composition according to claim 3, characterized in that it contains at least one compound selected from magnesium oxide.