Stereolithography resin composition and its use

Abstract

Providing a stereolithography resin composition and its use 【Solution means】A liquid photocurable resin composition comprising 1) At least a mixture of an isocyanurate ring-containing radically polymerizable compound (A) represented by the following formula (I), In the above formula, the mixture contains more than 0 and up to a maximum of 3 or 3 equivalents of X (0 < (1 + m + n) ≦ 3), Y is independently selected from a hydroxy group or a (meth)acryloyl group, at least one Y is a (meth)acryloyl group, R1 is selected from hydrogen or methyl, and X is selected from a linear short-chain or medium-chain fatty acid ester, 2) Optionally, one kind of radically polymerizable organic compound (B) different from compound (A), 3) At least a radical polymerization initiator (c), and characterized by having, in the cured form, a heat distortion temperature (HDT) measured by ISO75 higher than 70°C, preferably higher than 80°C, more preferably higher than 100°C, and an impact strength measured by ISO180 higher than 35 J / m, preferably higher than 45 J / m, more preferably higher than 55 J / m, A composition characterized by having these properties. ​

Description

Technical Field

[0005] , ,

[0006]

[0001] This application claims the priority of Italian Patent Application No. 102024000025017 filed on November 7, 2024, the content of which is hereby incorporated by reference in its entirety.

[0002] This application relates to a stereolithography resin composition and its use.

Background Art

[0003] In 1980, Hideaki Kodama, a Japanese, proposed a stereolithography technique in which a 3D model can be obtained by laminating a photocurable resin by irradiating a desired area with light energy at the same time. This led to the development and practical application of various methods of 3D additive manufacturing (AM).

[0004] Initially, it was used for the creation of model designs by CAD systems and for the creation of prototypes based on data. In recent years, it has been developed to provide not only prototypes but also final products. With the digital transformation (DX) supported by today's industry, there is high expectation for "new manufacturing technologies using digital data", that is, direct manufacturing methods using 3D additive manufacturing.

[0005] <00000!8>In the liquid bath photopolymerization method, in order to obtain a desired pattern, it is known to selectively irradiate a liquid photocurable resin with computer-controlled ultraviolet light. It cures to a predetermined thickness, and then a layer of the liquid resin is supplied onto the cured layer, and the same ultraviolet light is irradiated and cured in the same manner as above. This is a method of finally obtaining a 3D object by repeating the lamination operation to obtain continuous cured layers.

[0006] This stereolithography method can obtain a 3D object with high precision and in a relatively short time even if the shape of the object is extremely complex, so it is used in a wide range of applications for prototype industrial products such as household appliances.

[0007] Conventionally, the following photocurable resins have been used for stereolithography applications in the large-size free-liquid surface method (conventional stereolithography) using 355nm ultraviolet laser light. Hybrid types using photocationic and photoradical reactions are mainly composed of alicyclic diexope compounds, and polyfunctional acrylates are commonly used. In addition, the small liquid level regulated method is widely used to perform 3D modeling while raising the model by irradiating it with 405nm laser light from LED light dispersed by a bottom surface or DLP or LCD. Since a combination of hybrid types of diexope compounds and polyfunctional acrylate types suitable as photoinitiators has not been developed for this liquid level regulated method, photocurable compositions using urethane (meth)acrylate, oligoester acrylate, epoxy acrylate, etc., are used.

[0008] There is a need for the development of a liquid stereolithography resin that possesses both heat resistance and high impact strength.

[0009] In recent years, a product marketed as a resin produced using 3D systems, specifically the product name "HI TEMP 300-AMB," utilizes an acrylate compound containing tris(2-acryloxyethyl) isocyanurate to achieve heat resistance (>80°C). While its heat distortion temperature (HDT) under a 1.82 MPa load exceeds 300°C, its impact strength is only 10 J / m, requiring extreme caution during handling. Even a simple impact can cause it to break.

[0010] Japanese Patent Application No. 2020-128526 proposes the use of a composition in which tris(2-acryloxyethyl) isocyanurate, an acrylate compound having an isocyanurate ring, is added together with rubber microparticles, for the purpose of improving impact strength in addition to heat resistance. However, this application is limited in that the viscosity of the resin increases, the cleaning properties are impaired, and transparency cannot be achieved. Despite considerable efforts to meet these requirements, it has not been possible to obtain a product that possesses both impact strength and heat resistance, as exemplified by ABS resin. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Japanese Patent Application No. 2020-128526 [Overview of the project] [Problems that the invention aims to solve]

[0012] The object of the present invention is to provide a liquid photocurable resin composition that has excellent impact strength (impact strength > 35 J / m) and excellent heat resistance (heat distortion temperature (HDT) > 70°C) while maintaining handling, modeling speed, modeling accuracy, etc., for stereolithography.

[0013] The above-mentioned objectives are achieved by the liquid photocurable resin composition described in claim 1, and by the use thereof described in claims 14 and 15.

[0014] Hereinafter, short-chain and medium-chain fatty acids refer to fatty acids having between 2 and 12 carbon atoms.

[0015] The mixture of isocyanurate ring-containing radical polymerizable compounds (A) represents a mixture of compounds of formula (I), obtained by reacting a cyclic ester of a desired fatty acid in up to 3, preferably between 1 and 3, more preferably 1, 2, or 3 equivalents, with 1 equivalent of tris(2-acryloxyethyl) isocyanurate, wherein the desired acrylic acid derivative (Y) is preferably in 3 equivalents. The mixture of compounds of formula (I) contains up to 1, 2, or 3 equivalents of the desired fatty acid, depending on the reaction rate.

[0016] A polymerization initiator refers to any chemical species that react with one or more monomers and / or oligomers to initiate polymerization.

[0017] "Filler" refers to a substance added to a base material to improve various properties, or an inert substance added to increase its volume. [Modes for carrying out the invention]

[0018] The selection of compound (A) of formula (I) used in the following examples is commercialized by Shin Nakamura Chemical Industry Co., Ltd. in Japan under the following name. ―NK―A-9300-1CL:1+m+n=1 and R1=H, ―NK-A-9300-2CL:1+m+n=2 and R1=H, ―NK-A-9300-3CL:1+m+n=3 and R1=H, In the following examples, we refer to these compounds using their trade names.

[0019] The commercially available compound NK-A-9300 from Shin Nakamura Chemical Industry Co., Ltd. in Japan, used in Comparative Examples 1 to 3, is a compound of formula (I) having 1+m+n=0 and R1=H.

[0020] A liquid photocurable resin composition for stereolithography, provided in a first embodiment of the present invention, 1) A mixture of at least an isocyanurate ring-containing radical polymerizable compound (A) represented by the following formula (I), 2) Optionally, one radical-polymerizable organic compound (B) different from the compound (A), and 3) at least a radical polymerization initiator (C), is included.

[0021]

Chemical formula

[0022] The mixture of the isocyanurate ring-containing radical-polymerizable compound (A) is a mixture of (meth)acrylate oligomers having an isocyanurate ring modified with a fatty acid ester of the formula (I),

Chemical formula

[0029] In further embodiments, the amount of compound (A) in the resin composition used is 15 to 99.9% by mass.

[0030] Preferably, the amount of compound (A) in the resin composition used is 20 to 99.9% by mass, and more preferably 30 to 99.9% by mass.

[0031] In further embodiments, the amount of compound (A) in the resin composition used is 15 to 96% by mass. Preferably, the amount of compound (A) in the resin composition used is 20 to 96% by mass, and more preferably 30 to 96% by mass.

[0032] If the composition ratio of compound (A) is less than 15% by mass, the desired technical effect will not be achieved. Therefore, the effective composition ratio of compound (A) in this invention is at least 15% by mass.

[0033] When the composition ratio exceeds 96% by mass, the viscosity makes handling the composition more difficult, but the desired properties are maintained.

[0034] In another embodiment, the mixture of compound (A) contains up to 1 (0 < (1 + m + n) ≤ 1) equivalents of X.

[0035] A radically polymerizable organic compound (B), distinct from compound (A), is a polymerizable vinyl compound, and monofunctional and / or polyfunctional monomers and / or oligomers are used alone or in mixtures thereof.

[0036] Preferably, monofunctional and / or polyfunctional monomers and oligomers include isobornyl acrylate, isobornyl methacrylate, dicyclopentenyl acrylate, dicyclopentenyl methacrylate, 2-hydroxyethyl methacrylate, polypropylene glycol acrylate, polypropylene glycol methacrylate, phenoxyethylene glycol methacrylate, N-vinylpyrrolidone, dimethylacrylamide, acryloylmorpholine, vinyl acetate, styrene, trimethylolpropane triacrylate, and ethylene oxide (EO) modified trimethylolpropane triacrylate. Selected from the group consisting of pan, pentaerythritol tetraacrylate, ethylene oxide (EO)-modified pentaerythritol tetraacrylate, tris-(2-acryloxyethyl) isocyanurate, propylene oxide (PO)-modified trimethylolpropane triacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, dichloropentenyl diacrylate, polyester diacrylate, bis-(2-acryloxyethyl) isocyanurate, EO-modified bisphenol A diacrylate, tricyclodecanedimethanol diacrylate, penta or hexaacrylic acid or dipentaerythritol dimethacrylate, triallyl isocyanurate (TAIC), diallyl phthalate, and mixtures thereof.

[0037] (Meth)acrylate compounds containing oligo components can be added as compound (B), but the application of oligomers containing flexible components, such as urethane (meth)acrylates with a polyoxyalkylene structure, leads to a decrease in thermal deformation properties.

[0038] The radical polymerization initiator (C) contains at least a photopolymerization initiator.

[0039] Preferably, the photopolymerization initiator is selected from the group consisting of trimethylolpropane triacrylate-2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenyl ketone, acetophenone, benzophenone, xanthone, fluorenone, benzaldehyde, anthraquinone, triphenylamine, carbazole, 3-methylacetophenone, Michler's ketone, diphenyl(2,4,6-triethylbenzoyl)phosphine oxide (TPO), phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO), ethylphenyl(2,4,6-trimethylbenzoyl)phosphine phosphate (TPO-L), and mixtures thereof.

[0040] Sensitizers such as amine-based compounds can be used in combination with photopolymerization initiators.

[0041] In addition to photopolymerization initiators, thermal radical polymerization initiators may be part of compound (C).

[0042] Preferably, the thermal radical polymerization initiator is selected from the group consisting of benzoyl peroxide, t-butyl peroxybenzoate, dicumyl peroxide, diisopropyl peroxydicarbonate, tert-butyl peroxide, azobisisobutyronitrile, and mixtures thereof.

[0043] In one embodiment, the amount of polymerization initiator (C) used is 0.1 to 10% by mass, preferably 1 to 5% by mass, relative to compound (A) + (B).

[0044] Additives may be optionally added to the liquid photocurable resin composition. Typical additives include leveling agents, surfactants, polyethylene beads, organic plasticizers, inorganic fillers, and, if necessary, modifying resins.

[0045] As fillers, inorganic particles such as silica, glass, alumina, ceramics, and metals in the form of beads, powders, or whiskers may be used. Preferably, the fillers are selected from the group consisting of silica particles, glass powder / particles, ceramic powder / particles, and mixtures thereof. The size of these particles can be freely selected, as long as the size is smaller than the thickness of the layer.

[0046] Preferably, the modified resin is selected from the group consisting of thermoplastic resins, thermosetting resins, rubber resins, elastomer resins, and mixtures thereof.

[0047] Preferably, the liquid photocurable resin composition has an impact strength (notched) measured by ISO 180 that is higher than 35 J / m, preferably higher than 45 J / m, and more preferably higher than 55 J / m, in its cured form.

[0048] Preferably, the liquid photocurable resin composition has a heat distortion temperature (HDT) measured according to ISO 75, which is higher than 70°C, preferably higher than 80°C, and more preferably higher than 100°C, in its cured form.

[0049] In a further embodiment of the present invention, the liquid photocurable resin composition is used in a method for stereolithography or for manufacturing 3D printed products with excellent heat resistance and impact strength.

[0050] In a further embodiment of the present invention, a 3D product printing method includes a step of selectively solidifying the liquid photocurable resin composition in order to form a 3D product.

[0051] The following describes details of preferred non-limiting embodiments of the present invention. In particular, Examples 1 to 6 describe formulations of the liquid photocurable resin composition for stereolithography according to the present invention. Example 7 describes a method using the resin composition for the manufacture of active energy ray curable 3D products with excellent heat resistance and impact strength. Finally, Comparative Examples 1 to 3 were prepared using NK-A-9300 (1+m+n=0) or carried out with a compound (A) content of less than 15%. The present invention is not limited to the following embodiments.

[0052] Example 1 A 5 L three-necked flask equipped with a stirrer, a cooling channel, and a dropping funnel with a side tube containing acryloylmorpholine (ACMO, 300 g) (manufactured by KJ Chemical) was filled with NK-A-9300-1CL (700 g). During the addition of ACMO, the dropping funnel was replaced with degassed nitrogen under reduced pressure. The reaction mixture was heated to 50°C and stirred. After about 1 hour, TPO-L (50 g) was added in an environment where ultraviolet light was blocked, and the mixture was stirred until it was completely dissolved. The resulting resin composition was a colorless, transparent, viscous liquid containing 66.67% by mass of compound (A) (NK-A-9300-1CL) and had a viscosity of 306 mPa·s at 25°C.

[0053] Example 2 A compound prepared according to the method of Example 1, comprising acryloylmorpholine (ACMO, 300 g) (manufactured by KJ Chemical) and NK-A-9300-2CL (700 g). The resulting resin composition was a colorless, transparent, viscous liquid containing 66.67% by mass of compound (A) (NK-A-9300-2CL) and having a viscosity of 282 mPa·s at 25°C.

[0054] Example 3 A compound prepared according to the method of Example 1, comprising acryloylmorpholine (ACMO, 300 g) (manufactured by KJ Chemical), NK-A-9300-1CL (350 g), and NK-A-9300 (350 g). The resulting resin composition was a colorless, transparent, viscous liquid containing 33.33% by mass of compound (A) (NK-A-9300-1CL) and having a viscosity of 294 mPa·s at 25°C.

[0055] Example 4 A compound prepared according to the method of Example 1, comprising acryloylmorpholine (ACMO, 300 g) (manufactured by KJ Chemical), NK-A-9300-2CL (350 g), and NK-A-9300 (350 g). The resulting resin composition was a colorless, transparent, viscous liquid containing 33.33% by mass of compound (A) (NK-A-9300-2CL) and having a viscosity of 279 mPa·s at 25°C.

[0056] Example 5 A compound prepared according to the method of Example 1, comprising NK-A-9300-1CL (1000g) and TPO-L (50g). The resulting resin composition was a colorless, transparent, viscous liquid containing 95.24% by mass of compound (A) (NK-A-9300-1CL) and having a viscosity of 3512 mPa·s at 25°C.

[0057] Example 6 A compound prepared according to the method of Example 1, comprising NK-A-9300-2CL (1000 g) and TPO-L (50 g). The resulting resin composition was a colorless, transparent, viscous liquid containing 95.24% by mass of compound (A) (NK-A-9300-2CL) and having a viscosity of 2788 mPa·s at 25°C.

[0058] Example 7 Test specimens for measuring the bending strength, tensile strength, impact strength, and thermal distortion temperature of cured 3D products were obtained using a focused laser beam with a diameter of 20 μm (output 40 mW, wavelength 405 nm) and DW-029 manufactured by DWS in Italy, which had the resin compositions formulated in Examples 1 to 6 or Comparative Examples 1 to 3.

[0059] After washing and removing the liquid resin adhering to the resulting cured product with isopropyl alcohol, post-curing was performed using a 20W 405nm LED light for 60 minutes, followed by heat treatment in a 120°C oven for 120 minutes. The bending strength, tensile properties, notch impact strength, and load deformation temperature of the obtained specimens were measured according to ISO standards. The results are shown in Table 1 (Examples 1 to 6) and Table 2 (Comparative Examples 1 to 3).

[0060] Table 1 Examples [Table 1]

[0061] Comparative Example 1 A formulation according to the method of Example 1, comprising acryloylmorpholine (ACMO, 300 g) (manufactured by KJ Chemical) and NK-A-9300 (700 g). The resulting resin composition was a colorless, transparent, viscous liquid containing 70% by mass of NK-A-9300 and having a viscosity of 276 mPa·s at 25°C.

[0062] Comparative Example 2 A compound prepared according to the method of Example 1, comprising acryloylmorpholine (ACMO, 300 g) (manufactured by KJ Chemical), NK-A-9300-1CL (100 g), and NK-A-9300 (600 g). The resulting resin composition was a colorless, transparent, viscous liquid containing 9.52% by mass of compound (A) (NK-A-9300-1CL) and having a viscosity of 276 mPa·s at 25°C.

[0063] Comparative Example 3 A compound prepared according to the method of Example 1, comprising acryloylmorpholine (ACMO, 300 g) (manufactured by KJ Chemical), NK-A-9300-2CL (100 g), and NK-A-9300 (600 g). The resulting resin composition was a colorless, transparent, viscous liquid containing 9.52% by mass of compound (A) (NK-A-9300-2CL) and having a viscosity of 275 mPa·s at 25°C.

[0064] Table 2 Comparative Examples [Table 2]

Claims

1. A liquid photocurable resin composition, 1) A mixture of at least an isocyanurate ring-containing radical polymerizable compound (A) represented by the following formula (I), 【Chemistry 1】 In the above formula, the mixture contains X in amounts greater than 0 and less than or equal to 3 equivalents (0 < (1 + m + n) ≤ 3), Y is independently selected from a hydroxyl group or a (meth)acryloyl group, at least one Y is a (meth)acryloyl group, R1 is selected from hydrogen or methyl, and X is selected from linear short-chain or medium-chain fatty acid esters. 2) Optionally, one radical polymerizable organic compound (B) different from compound (A), 3) At least a radical polymerization initiator (C), Includes, In the hardened form, A heat distortion temperature (HDT) measured according to ISO 75, higher than 70°C, preferably higher than 80°C, more preferably higher than 100°C, and Impact strength measured according to ISO 180, higher than 35 J / m, preferably higher than 45 J / m, more preferably higher than 55 J / m. A composition characterized by having [a certain characteristic].

2. The liquid photocurable resin composition according to claim 1, characterized by containing one radical polymerizable organic compound (B) different from compound (A).

3. The liquid photocurable resin composition according to claim 1, characterized in that the mixture of isocyanurate ring-containing radical polymerizable compounds (A) of formula (I) has at least two (meth)acryloyl groups.

4. The liquid photocurable resin composition according to claim 1, characterized in that X is selected from the group consisting of linear esters of butyric acid, valeric acid, caproic acid, heptanoic acid, and caprylic acid, and preferably a linear ester of caproic acid.

5. The liquid photocurable resin composition according to claim 1, characterized in that R1 is a hydrogen atom.

6. The liquid photocurable resin composition according to claim 1, characterized in that the mixture of compound (A) is at least 15% by mass, preferably 15% to 99.9% by mass, more preferably 20% to 99.9% by mass, and even more preferably 30% to 99.9% by mass, based on the total mass of compounds (A), (B), and (C).

7. The liquid photocurable resin composition according to claim 1, characterized in that the radical polymerizable organic compound (B), which is different from compound (A), is a polymerizable vinyl compound, and monofunctional and / or polyfunctional monomers and / or oligomers are used alone or in mixtures thereof.

8. The monofunctional and / or polyfunctional monomers and oligomers include isobornyl acrylate, isobornyl methacrylate, dicyclopentenyl acrylate, dicyclopentenyl methacrylate, 2-hydroxyethyl methacrylate, polypropylene glycol acrylate, polypropylene glycol methacrylate, phenoxyethylene glycol methacrylate, N-vinylpyrrolidone, dimethylacrylamide, acryloylmorpholine, vinyl acetate, styrene, trimethylolpropane triacrylate, ethylene oxide (EO) modified trimethylolpropane triacrylate. The liquid photocurable resin composition according to claim 7, characterized by being selected from the group consisting of pentaerythritol tetraacrylate, ethylene oxide (EO)-modified pentaerythritol tetraacrylate, tris-(2-acryloxyethyl) isocyanurate, propylene oxide (PO)-modified trimethylolpropane triacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, diclopentenyl diacrylate, polyester diacrylate, bis-(2-acryloxyethyl) isocyanurate, EO-modified bisphenol A diacrylate, tricyclodecanedimethanol diacrylate, pentaerythritol or hexaacrylate, or their dimethacrylate compounds, triallyl isocyanurate (TAIC), diallyl phthalate, and mixtures thereof.

9. The liquid photocurable resin composition according to claim 1, characterized in that the radical polymerization initiator (C) contains at least a photopolymerization initiator and optionally a thermal radical polymerization initiator.

10. The liquid photocurable resin composition according to claim 9, characterized in that the photopolymerization initiator is selected from the group consisting of trimethylolpropane-2,2-dimethoxy-2-phenylacetophenone triacrylate, 1-hydroxycyclohexylphenyl ketone, acetophenone, benzophenone, xanthone, fluorenone, benzaldehyde, anthraquinone, triphenylamine, carbazole, 3-methylacetophenone, Michler's ketone, diphenyl(2,4,6-triethylbenzoyl)phosphine oxide (TPO), phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO), ethylphenyl(2,4,6-trimethylbenzoyl) phosphine, and mixtures thereof.

11. The liquid photocurable resin composition according to claim 1, characterized in that the mixture of compound (A) has 0 < (1 + m + n) ≤ 2.

12. Use of the liquid photocurable resin composition according to claim 1 as a resin composition for stereolithography.

13. A method for printing a 3D product, comprising the steps of providing a liquid photocurable resin composition according to claim 1, and selectively solidifying a layer of the liquid photocurable resin composition to form a 3D product.

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