Resin composition and resin composition for three-dimensional molding

Abstract

To provide a resin composition that is in a liquid state at normal temperature and normal pressure, a cured product of which has excellent biodegradability, and a resin composition for three-dimensional molding.SOLUTION: The present invention discloses a resin composition, and a resin composition for three-dimensional molding, each containing a polyfunctional methacryl monomer having a polycaprolactone skeleton with a molecular weight of 1,000 or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin composition and a resin composition for three-dimensional object fabrication. [Background technology]

[0002] In recent years, many products using resin have been developed, such as 3D printing technology, which uses resin to produce three-dimensional objects. 3D printers using 3D printing technology allow anyone to easily create three-dimensional objects, and are expected to be used by many people around the world. Therefore, disposal of the resin used is an important issue. From the perspective of environmental conservation, it is preferable that the resin used in 3D printers is biodegradable.

[0003] For example, it has been proposed to produce a three-dimensional object using a biodegradable photocurable resin (see, for example, Patent Documents 1 and 2).

[0004] However, resins used to manufacture three-dimensional objects by stereolithography must be liquid at room temperature, but no resins that are liquid at room temperature and biodegradable have yet been put into practical use. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 9-31183 [Patent Document 2] Japanese Patent Application Publication No. 6-157603 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention aims to solve the above-mentioned problems of the prior art and to achieve the following object: That is, the present invention aims to provide a resin composition and a resin composition for three-dimensional modeling that are liquid at room temperature and normal pressure and that produce cured products with excellent biodegradability. [Means for solving the problem]

[0007] As a result of extensive research, the present inventors have found that by incorporating a polyfunctional (meth)acrylic monomer having a polycaprolactone skeleton with a molecular weight of 1,000 or less, it is possible to obtain a resin composition and a resin composition for three-dimensional modeling that are liquid at room temperature and normal pressure and that can improve the biodegradability of the cured product.

[0008] The means for solving the above problems are as follows: <1> The resin composition is characterized by containing a polyfunctional (meth)acrylic monomer having a polycaprolactone skeleton with a molecular weight of 1,000 or less. <2> The polyfunctional (meth)acrylic monomer has a hydroxyl group. <1> The resin composition is as described in the above. <3> the abundance (%) of hydroxyl groups in the polyfunctional (meth)acrylic monomer is 10% or more and 33% or less relative to the monomer having a polycaprolactone skeleton before (meth)acrylation; <2> The resin composition is as described in the above. <4> The content of the polyfunctional (meth)acrylic monomer having a polycaprolactone skeleton is 30% by mass or more and 100% by mass or less based on the total amount of the composition. <1> from <3> The resin composition according to any one of the above items. <5> The above-mentioned composition further contains a monofunctional (meth)acrylate. <1> from <4> The resin composition according to any one of the above items. <6> The glass transition temperature (Tg) is equal to or higher than room temperature. <1> from <5> The resin composition according to any one of the above items. <7> The monofunctional (meth)acrylate is at least one of isobornyl (meth)acrylate and acryloylmorpholine. <5> from <6> The resin composition according to any one of the above items. <8> The resin composition for three-dimensional modeling is characterized by containing a polyfunctional (meth)acrylic monomer having a polycaprolactone skeleton with a molecular weight of 1,000 or less. [Effects of the Invention]

[0009] According to the present invention, it is possible to solve the above-mentioned problems in the prior art, achieve the above-mentioned object, and provide a resin composition and a resin composition for three-dimensional modeling that are in a liquid state at room temperature and normal pressure and have excellent biodegradability when cured. DETAILED DESCRIPTION OF THE INVENTION

[0010] (Resin composition) The resin composition of the present invention contains a polyfunctional (meth)acrylic monomer having a polycaprolactone skeleton with a molecular weight of 1,000 or less, and further contains other components as required.

[0011] <Polyfunctional (meth)acrylic monomer> The polyfunctional (meth)acrylic monomer has a polycaprolactone skeleton with a molecular weight of 1,000 or less. The polyfunctional (meth)acrylic monomer having a polycaprolactone skeleton as the main skeleton can impart biodegradability to the resulting cured resin composition, enabling it to be decomposed by enzymes. The polyfunctional (meth)acrylic monomer having a polycaprolactone skeleton as the main skeleton can cause the cured resin composition to contain a large number of ester bonds derived from the polycaprolactone skeleton, allowing it to be decomposed by an enzymatic reaction. In the present invention, "biodegradable" means decomposability by lipase enzymes, which are widely present in nature. More specifically, "biodegradable" means that when a substance is reacted with an enzyme or contacted with a microorganism at 30°C and atmospheric pressure for 4 days, the weight of the substance changes from the weight before the reaction or contact, and the rate of change is greater than that of a substance without the addition of lipase enzymes.

[0012] The polyfunctional (meth)acrylic monomer is not particularly limited as long as it is a (meth)acrylic monomer having two or more acrylic or methacrylic groups, and can be appropriately selected depending on the purpose.

[0013] The resin composition of the present invention contains the polyfunctional (meth)acrylic monomer, and therefore can be cured by heat or light.

[0014] The polyfunctional (meth)acrylic monomer is not particularly limited as long as it has a molecular weight of 1,000 or less and a polycaprolactone skeleton as the main skeleton, and examples thereof include those represented by the following structural formulas (1) and (2).

[0015] [ka] In the structural formula (1), R is a branched alkyl group, and the sum of X, Y, and Z is an integer of 1 or more and 9 or less.

[0016] [ka] In the structural formula (2), R is a linear alkyl group or a linear alkyl ether, and the sum of m and n is an integer of 1 or more and 9 or less.

[0017] The molecular weight of the polyfunctional (meth)acrylic monomer is 1,000 or less, preferably 300 to 1,000, and more preferably 500 to 1,000. When the molecular weight of the polyfunctional (meth)acrylic monomer is 1,000 or less, the resin composition can be made liquid at room temperature and normal pressure. Furthermore, when the molecular weight of the polyfunctional (meth)acrylic monomer is 300 to 1,000, the resin composition can have an appropriate viscosity that is easy to handle. The method for measuring the molecular weight is not particularly limited, and any conventionally known method can be used, and can be appropriately selected depending on the purpose. The molecular weight can be calculated, for example, by using the hydroxyl value OH A , the number of hydroxyl groups in the molecule OH B One method is to calculate the hydroxyl value using the following formula from the molecular weight of potassium hydroxide (56.1). The hydroxyl value can be measured in accordance with JIS K 0070:1992. The number of hydroxyl groups in a molecule can be measured by titrating a potassium hydroxide-ethanol solution.

number

[0018] The content of the polyfunctional (meth)acrylic monomer is preferably 30% by mass or more and 100% by mass or less, and more preferably 30% by mass or more and 70% by mass or less, based on the total amount of the composition.

[0019] The polyfunctional (meth)acrylic monomer may have a functional group different from the (meth)acrylic group in its structure. The functional group is not particularly limited and can be appropriately selected depending on the purpose. Examples of the functional group include a hydrophilic group. Examples of the hydrophilic group include a hydroxyl group, a carboxyl group, an amino group, etc. These may be used alone or in combination of two or more. Among these, it is preferable that the polyfunctional (meth)acrylic monomer has the hydroxyl group. When the polyfunctional (meth)acrylic monomer has the hydroxyl group, the enzyme can easily act on the cured product, and decomposition by the enzyme can be promoted. This is thought to be because the polycaprolactone skeleton, which has poor hydrophilicity, has a hydroxyl group, which improves the hydrophilicity of the polymer (cured product) of the polyfunctional (meth)acrylic monomer, making it easier for the enzyme to act on the cured product. Therefore, it is preferable that a large number of hydroxyl groups remain.

[0020] Examples of the polyfunctional (meth)acrylic monomer having a hydroxyl group include those represented by the following structural formula (1′).

[0021] [ka] In the structural formula (1′), R is a branched alkyl group, and the sum of X, Y, and Z is an integer of 1 or more and 9 or less.

[0022] The abundance (%) of the functional groups in the polyfunctional (meth)acrylic monomer is preferably 10% or more and 50% or less, more preferably 10% or more and 33% or less, and even more preferably 20% or more and 33% or less, relative to the monomer having a polycaprolactone skeleton before (meth)acrylation.

[0023] The abundance ratio (%) of the functional group contained in the polyfunctional (meth)acrylic monomer can be obtained by the following method, which shows an example in which the functional group is a hydroxyl group. First, the monomer having the polycaprolactone skeleton used to prepare the sample to be measured before (meth)acrylation was measured using a Fourier transform infrared spectrophotometer (FT-IR, device name: Nicolet iS20, manufactured by Thermo). -1 ~3600cm -1 The peak intensity of the hydroxyl group (OH) is measured. The measurement result is taken as peak intensity α. Next, the sample (resin composition) to be measured was measured at 3100 cm using a Fourier transform infrared spectrophotometer (FT-IR, device name: Nicolet iS20, manufactured by Thermo). -1 ~3600cm -1 The peak intensity of the hydroxyl group (OH) is measured. The measurement result is taken as peak intensity X. The abundance (%) of the functional groups contained in the polyfunctional (meth)acrylic monomer can be calculated using the measured peak intensities according to the following formula 1. Presence rate (%) of functional groups in polyfunctional (meth)acrylic monomers = {(Peak intensity X) / (Peak intensity α)} × 100 Formula 1 Furthermore, by changing the range of peak intensity to be measured depending on the type of the functional group, the abundance ratio (%) of the functional group contained in the polyfunctional (meth)acrylic monomer can be measured.

[0024] The method for converting the polyfunctional (meth)acrylic monomer into a polyfunctional (meth)acrylic monomer having a functional group other than a (meth)acrylic group in its structure is not particularly limited and can be appropriately selected depending on the purpose. For example, when converting into a polyfunctional (meth)acrylic monomer having a hydroxyl group, a method can be used in which the amount of acrylic acid chloride (methacrylic acid chloride) to be (meth)acrylic-added to the monomer having a polycaprolactone skeleton before (meth)acrylation is added in an amount equal to or less than the amount of the monomer having a polycaprolactone skeleton before (meth)acrylation. By doing so, a portion of the hydroxyl groups in the monomer having a polycaprolactone skeleton before (meth)acrylation can be left as unreacted hydroxyl groups without being converted to (meth)acrylation.

[0025] The polyfunctional (meth)acrylic monomer preferably does not have a urethane bond or an epoxy group in its structure, which allows the molecular weight of the polyfunctional (meth)acrylic monomer to be reduced, thereby reducing the viscosity of the resin composition of the present invention.

[0026] <Other ingredients> The other components are not particularly limited as long as they are compatible with the polyfunctional (meth)acrylate having a caprolactone skeleton, and can be appropriately selected depending on the purpose. Examples of the other components include monofunctional (meth)acrylates, polyfunctional (meth)acrylates, porous materials, foaming agents, colorants, pigments, inorganic fillers, biodegradable resin particles, and polymerization inhibitors. Here, "compatible with the polyfunctional (meth)acrylate having a caprolactone skeleton" means that the appearance when visually inspected is transparent without layer separation and without cloudiness.

[0027] <<Monofunctional (meth)acrylate>> The monofunctional (meth)acrylate is not particularly limited, and may be a monomer or an oligomer, which can be appropriately selected depending on the purpose. If the crosslink density of the cured product of the resin composition is too high, the cured product will become brittle. By including the monofunctional (meth)acrylate, it is possible to prevent the crosslink density of the cured product of the resin composition from becoming too high. Since the polycaprolactone skeleton has many ester bonds and is a soft segment, by appropriately adjusting the crosslink density, it is possible to improve the flexibility of the cured product of the resin composition of the present invention.

[0028] Examples of the monofunctional acrylate include benzyl acrylate (Tg: 6°C), phenoxyethyl acrylate (Tg: 2°C), tetrahydrofurfuryl acrylate (Tg: -12°C), cyclohexyl acrylate (Tg: 15°C), isobornyl acrylate (Tg: 94°C), acryloylmorpholine (Tg: 145°C), 2-ethylhexyl acrylate (Tg: -70°C), octyl acrylate (Tg: -65°C), n-butyl acrylate (Tg: -55°C), and ethyl acrylate (Tg: -20°C). Examples of the monofunctional methacrylate include benzyl methacrylate (Tg: 54°C), phenoxyethyl methacrylate (Tg: 2°C), tetrahydrofurfuryl methacrylate (Tg: 60°C), cyclohexyl methacrylate (Tg: 83°C), isobornyl methacrylate (Tg: 155°C), 2-ethylhexyl methacrylate (Tg: -10°C), octyl methacrylate (Tg: -65°C), n-butyl methacrylate (Tg: 20°C), and ethyl methacrylate (Tg: 65°C). Among these, those having a glass transition temperature (Tg, °C) under normal pressure of at least room temperature (5°C or higher and 35°C or lower) are preferred, and more preferably at least 50°C. When the glass transition temperature (Tg, °C) under normal pressure is at least room temperature (5°C or higher and 35°C or lower), sufficient hardness can be obtained to maintain the shape of the cured product. That is, the monofunctional (meth)acrylate is preferably isobornyl acrylate (Tg: 94° C.), (meth)acryloylmorpholine (Tg: 145° C.), or isobornyl methacrylate (Tg: 155° C.).

[0029] The content of the monofunctional (meth)acrylate is preferably 10% by mass or more and 50% by mass or less, and more preferably 10% by mass or more and 30% by mass or less, based on the total amount of the composition. When the content of the monofunctional (meth)acrylate is 50% by mass or less, based on the total amount of the composition, the biodegradability of the cured product of the resin composition can be ensured.

[0030] <<Polyfunctional (meth)acrylate>> The polyfunctional (meth)acrylate may be a monomer or an oligomer, and is not particularly limited and can be appropriately selected depending on the purpose. Examples of the polyfunctional (meth)acrylate include 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, polyethylene di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, dimethyloltricyclodecane di(meth)acrylate, ethylene oxide (EO) adduct di(meth)acrylate of bisphenol A, ethylene oxide (EO)-modified trimethylolpropane tri(meth)acrylate, and pentaerythritol tetra(meth)acrylate.

[0031] The content of the polyfunctional (meth)acrylate is preferably from 1 to 30% by mass, more preferably from 5 to 20% by mass, based on the total amount of the composition. When the content of the polyfunctional (meth)acrylate is from 1 to 30% by mass, the hardness of the cured product can be appropriately controlled.

[0032] <<Porous materials>> The porous material is not particularly limited as long as it is a porous material that can be used as a filler, and can be appropriately selected depending on the purpose. By containing the porous material, the hardness of the cured product can be improved, and during decomposition, enzymes can easily act from the porous region, thereby improving biodegradability. Examples of the porous material include diatomaceous earth, zeolite, and activated carbon. The content of the porous material is not particularly limited and can be appropriately selected depending on the purpose.

[0033] <<Foaming agent>> The foaming agent is a material that can be contained in the resin composition of the present invention and foamed during curing to make the cured product porous. By making the cured product porous with the foaming agent, the biodegradability of the cured product can be improved. Examples of the foaming agent include azodicarbonamide, N,N'-dinitropentamethylenetetramine, 4,4'-oxybisbenzenesulfonylhydrazide, hydrogen carbonates, and carbonates. The content of the foaming agent is not particularly limited and can be appropriately selected depending on the purpose.

[0034] <<Biodegradable resin particles>> The biodegradable resin microparticles are not particularly limited as long as they are microparticles made of a resin that exhibits biodegradability, and can be appropriately selected depending on the purpose. By incorporating the biodegradable resin microparticles into the resin composition of the present invention, it is possible to easily fragment the cured product during decomposition. That is, by incorporating biodegradable microparticles, they can act as starting points for decomposition, fragment the cured product, increase its surface area, and improve biodegradability. Furthermore, by fragmenting the lumps of the cured product, biodegradable particles (e.g., beads used in model guns) can be produced. Examples of the material for the biodegradable resin particles include polylactic acid. The volume average particle size of the biodegradable resin fine particles is preferably 5 μm or more and 1 mm or less. The content of the biodegradable resin fine particles is not particularly limited and can be appropriately selected depending on the purpose.

[0035] The viscosity (cP) of the resin composition of the present invention is preferably 20 cP to 1,000 cP, more preferably 50 cP to 500 cP, at 25° C. If the viscosity (cP) of the resin composition of the present invention is 50 cP to 500 cP, there is a problem that, for example, it is not possible to use the resin composition of the present invention to produce a fine structure that takes advantage of the advantages of stereolithography.

[0036] The glass transition temperature (Tg, °C) of the resin composition of the present invention is preferably equal to or higher than room temperature (5°C or higher and 35°C or lower) under normal pressure, and more preferably equal to or higher than 50°C. When the glass transition temperature (Tg, °C) is equal to or higher than room temperature (5°C or higher and 35°C or lower) under normal pressure, a hardness sufficient to maintain the shape of the cured product can be obtained. The glass transition temperature (Tg, °C) of the resin composition of the present invention can be measured using a dynamic viscoelasticity measuring device (DMA: Dynamic Mechanical Analysis, product name: RSA-3, manufactured by TA Instruments). Specifically, the glass transition temperature (Tg, °C) is determined as the temperature at the maximum point of tan δ (loss modulus / storage modulus) obtained under measurement conditions of a sample size of 5 mm width × 20 mm length and a frequency of 1 MHz.

[0037] The resin composition of the present invention is liquid at room temperature and pressure, and its cured product has excellent biodegradability. Therefore, for example, in the case of objects made using the resin, i.e., two-dimensional or three-dimensional objects, the molding accuracy can be improved and the material can be environmentally friendly. Therefore, the resin composition of the present invention can be suitably used exclusively for producing three-dimensional objects. The method for producing a three-dimensional object using the resin composition of the present invention is not particularly limited and can be appropriately selected depending on the purpose. For example, a method in which the resin composition is filled into a mold and cured by heat or light can be mentioned.

[0038] (Resin composition for three-dimensional modeling) The resin composition for three-dimensional object fabrication of the present invention contains a polyfunctional (meth)acrylic monomer having a polycaprolactone skeleton with a molecular weight of 1,000 or less, and further contains other components as required. The resin composition for three-dimensional object production of the present invention is the same as the resin composition of the present invention. The resin composition for three-dimensional object fabrication of the present invention can be suitably used exclusively for the production of three-dimensional objects. [Example]

[0039] Examples of the present invention will be described below, but the present invention is not limited to these examples.

[0040] Example 1 A 300 mL three-necked flask was charged with 11 g (0.02 mol) of Plaxel 305 (triol of caprolactone, molecular weight: 550, manufactured by Daicel Corporation) and 4.0 g (0.04 mol, molar equivalent relative to the raw materials: 0.67) of triethylamine (molecular weight: 101.2), and 100 mL of dichloromethane was added. A reflux condenser and a dropping funnel were attached, and the mixture was stirred in an ice bath to completely dissolve the mixture, yielding Solution A1. Next, 3.6 g (0.04 mol, molar equivalent of 0.67 relative to the raw material) of acrylic acid chloride (molecular weight 90.51) was diluted with 30 mL of dichloromethane and slowly added to Solution A1 using a dropping funnel to obtain Solution A2. The mixture was stirred for 2 hours and then stirred at reflux temperature for 30 minutes. Triethylamine hydrochloride was removed from Solution A2 by suction filtration, and then the solution was washed three times with water using a separatory funnel, and the solvent was removed using an evaporator to obtain a colorless, transparent liquid 1 (yield: 90%). Liquid 1 was analyzed using a Fourier transform infrared spectrophotometer (FT-IR, device name: Nicolet iS2, manufactured by Thermo). -1 The peak of the acrylic double bond is observed around 3100 cm -1 ~3600cm -1 It was confirmed that the peak of the hydroxyl group (OH) remained.

[0041] Example 2 A pale yellow, transparent liquid 2 was obtained (yield: 95%) in the same manner as in Example 1, except that the amount of acrylic acid chloride (molecular weight 90.51) was changed to 4.9 g (0.054 mol, molar equivalent to the raw material: 0.9) per 11 g (0.02 mol) of Plaxel 305.

[0042] Example 3 A pale yellow, transparent liquid 3 was obtained (yield: 90%) in the same manner as in Example 1, except that the amount of acrylic acid chloride (molecular weight 90.51) was changed to 5.4 g (0.06 mol) per 11 g (0.02 mol) of Plaxel 305.

[0043] Example 4 A 300 mL three-necked flask was charged with 11 g (0.02 mol) of Plaxel 205 (diol of caprolactone, molecular weight: 550, manufactured by Daicel Corporation) and 4.0 g (0.04 mol, molar equivalent of 1 relative to the raw materials) of triethylamine (molecular weight 101.2), and 100 mL of dichloromethane was added. A reflux condenser and a dropping funnel were attached, and the mixture was stirred in an ice bath to completely dissolve, yielding Solution B1. Next, 3.6 g (0.04 mol) of acrylic acid chloride (molecular weight 90.51) was diluted in 30 mL of dichloromethane and slowly added to solution B1 using a dropping funnel to obtain solution B2. The mixture was stirred for 2 hours and then stirred at reflux temperature for 30 minutes. Triethylamine hydrochloride was removed from Solution B2 by suction filtration, and the solution was washed three times with water using a separatory funnel, and the solvent was removed using an evaporator to obtain a colorless, transparent liquid 4 (yield: 91%). Liquid 4 was analyzed using a Fourier transform infrared spectrophotometer (FT-IR, Nicolet iS20, manufactured by Thermo). -1 The peak of the acrylic double bond around 3100 cm -1 ~3600cm -1 It was confirmed that the peak of the hydroxyl group (OH) disappeared.

[0044] Example 5 A pale yellow, transparent liquid 5 was obtained (yield: 92%) in the same manner as in Example 1, except that 11 g (0.02 mol) of Plaxel 305 in Example 1 was changed to 6 g of Plaxel 303 (caprolactone triol, molecular weight: 300, 0.02 mol, manufactured by Daicel Corporation).

[0045] (Comparative Example 1) A pale yellow wax 6 was obtained (yield: 90%) in the same manner as in Example 1, except that 11 g (0.02 mol) of Placcel 205 in Example 4 was changed to 22 g of Placcel 210 (diol of caprolactone, molecular weight: 1,100, 0.02 mol, manufactured by Daicel Corporation).

[0046] (Comparative Example 2) Plaxel FA2D (monofunctional acrylate of caprolactone, molecular weight: 340, manufactured by Daicel Corporation).

[0047] (Comparative Example 3) EBECRY3708 (modified epoxy acrylate, molecular weight: 3,000, manufactured by Daicel Ornex Co., Ltd.).

[0048] Comparative Example 4 EBECRY8402 (urethane acrylate, molecular weight: 2,000, manufactured by Daicel Ornex Co., Ltd.).

[0049] Next, the "hydroxyl group abundance (%)" and "viscosity (cP)" of the obtained liquids 1 to 9 were measured as follows.

[0050] -Hydroxyl group abundance (%)- The monomers having a polycaprolactone skeleton (PLACCEL 305, PLACCEL 205, PLACCEL 303, PLACCEL 210, PLACCEL FA2D) before (meth)acrylation, which were used to prepare the samples (liquids) to be measured, were measured for 3100 cm using a Fourier transform infrared spectrophotometer (FT-IR, device name: Nicolet iS20, manufactured by Thermo). -1 ~3600cm -1 The peak intensity of the hydroxyl group (OH) was measured. The measurement result is taken as peak intensity α. Next, each of the samples to be measured (resin compositions, liquids 1 to 9) was measured using a Fourier transform infrared spectrophotometer (FT-IR, device name: Nicolet iS20, manufactured by Thermo). -1 ~3600cm -1The peak intensity of the hydroxyl group (OH) was measured. The measurement result is taken as peak intensity X. The hydroxyl group abundance (%) (the abundance (%) of the hydroxyl groups in the polyfunctional (meth)acrylic monomer) was calculated by the following formula 1 using the measured peak intensities. Hydroxyl group abundance rate (%) = {(Peak intensity X) / (Peak intensity α)} × 100 Formula 1

[0051] -Viscosity (cP)- The viscosity of each of the samples to be measured (resin compositions, liquids 1 to 9) was measured at 25°C using a rotational rheometer (device name: G3, manufactured by TA Instruments).

[0052] Next, cured products were prepared using the obtained liquids 1 to 9, and the "weight loss rate (%) of the cured product (degradability)" of the prepared cured products was evaluated as follows.

[0053] -Weight loss rate of cured product (%) (degradability)- [Preparation of cured product] To prepare a modeling liquid, 1 part by mass of the photopolymerization initiator Irgacure 1173 (manufactured by BASF) was added to 100 parts by mass of each of the obtained liquids 1 to 9. Each of the prepared modeling liquids was sandwiched between two PET films and coated, and then irradiated with UV (1 J / cm) using a UV conveyor. 2 ) to obtain cured products measuring 3 cm length x 3 cm width x 0.5 mm thickness. The weight of each of the obtained cured products was measured (weight A). [Biodegradability evaluation] First, lipase PS (manufactured by Amano Enzyme Inc.) was added as an enzyme to 20 mL of water (solvent) so that the amount of lipase PS was 5 U per 1 mg of the cured product, to prepare an enzyme solution. The obtained cured product was placed in a glass container large enough to accommodate the entire cured product, and completely immersed in the enzyme solution. The glass container was then sealed and left to stand at 30°C for 4 days. After standing, the enzyme solution and the hardened product were separated by filtration, and the hardened product was completely dried and then weighed (weight B). The ratio of the weight after enzyme treatment (weight B) to the weight before enzyme treatment (weight A) was defined as the weight loss rate (%), which was used as an index of biodegradability. As a control experiment, a sample containing only water without any enzyme was prepared and evaluated in the same manner.

[0054] [Table 1]

[0055] The cured product of Comparative Example 1 has a structure in which caprolactone is pendant on the side chain of a linear acrylic polymer. This cured product (polymer) does not exhibit biodegradability. Thus, the cured product (main chain structure) does not collapse (decompose) simply because the linear polymer has a caprolactone skeleton on the side chain. Examples 1 to 5 demonstrate biodegradability. The cured products of Examples 1 to 5 are composed of bifunctional or higher acrylates, and therefore have a three-dimensional crosslinked structure. The crosslinked sites contain biodegradable polycaprolactone, which is hydrolyzed by enzymes, causing the cured products to disintegrate (decompose). In other words, unless the main skeleton has many ester bonds, biodegradability by enzymes cannot be achieved. For example, alkyl glycol chains, alkyl chains, etc. are not decomposed by enzymes. Furthermore, as shown in Examples 1 to 3, it was confirmed that the higher the proportion (%) of hydroxyl groups contained in the resin composition, the more improved the biodegradability effect. In Comparative Examples 1, 3 and 4, the molecular weight is 1,000 or more, the monomer is waxy or a viscous liquid, the substance before curing has no fluidity, and the problem of the present invention cannot be solved. Furthermore, as shown in Comparative Examples 3 and 4, when epoxy acrylate or urethane acrylate is used, the molecular weight increases and the liquid tends to become viscous. Such high monomer viscosity makes the material unsuitable for use in three-dimensional modeling, which requires low viscosity. On the other hand, in the resin composition of the present invention, the monomer is acrylated with acrylic acid chloride, so the molecular weight of the monomer is the molecular weight of the raw material plus the molecular weight of the acrylic group (55) according to the number of acrylic groups. In other words, the molecular weight after synthesis is limited, which is excellent for controlling the melting point and viscosity. When comparing samples with and without lipase enzyme, the sample with lipase showed a greater weight loss than the sample without lipase.

[0056] (Examples 6 to 7 and Comparative Example 5) Next, as shown in Table 2 below, resin compositions of Examples 6 to 7 and Comparative Example 5 were prepared, and the "viscosity (cP)" was measured and the "weight loss rate (%) of the cured product (degradability)" was evaluated in the same manner as in Examples 1 to 5 and Comparative Examples 1 to 4.

[0057] [Table 2] [Industrial Applicability]

[0058] The resin composition and the resin composition for three-dimensional object fabrication of the present invention are in a liquid state at room temperature and normal pressure, and the cured product exhibits excellent biodegradability, and therefore can be suitably used, for example, for the production of three-dimensional objects.

Claims

1. A resin composition comprising a polyfunctional (meth)acrylic monomer having a polycaprolactone skeleton with a molecular weight of 1,000 or less and a hydroxyl group.

2. The resin composition according to claim 1, wherein the polyfunctional (meth)acrylic monomer is represented by the following structural formula (1'): 【Chemical 1】 In the structural formula (1′), R represents a branched alkyl group, and the sum of X, Y, and Z represents an integer of 1 or more and 9 or less.

3. 3. The resin composition according to claim 1, wherein the abundance (%) of hydroxyl groups in the polyfunctional (meth)acrylic monomer is 10% or more and 33% or less relative to the monomer having a polycaprolactone skeleton before (meth)acrylation.

4. The resin composition according to claim 1 , wherein the content of the polyfunctional (meth)acrylic monomer is 30% by mass or more and 100% by mass or less based on the total amount of the composition.

5. The resin composition according to claim 1 , further comprising a monofunctional (meth)acrylate.

6. The resin composition according to claim 1 , which has a glass transition temperature (Tg) of room temperature or higher.

7. The resin composition according to claim 5 , wherein the monofunctional (meth)acrylate is at least one of isobornyl (meth)acrylate and acryloylmorpholine.

8. A resin composition for three-dimensional modeling, comprising a polyfunctional (meth)acrylic monomer having a polycaprolactone skeleton with a molecular weight of 1,000 or less and a hydroxyl group.

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