Method for producing molded article, set of slurry and release mold, release mold, molded article, and optical member

Abstract

To provide a method for manufacturing a molded body, a set of a slurry and a release mold, a release mold, a molded body, and an optical member, in which occurrence of cracks in a cured body after demolding is suppressed when the molded body is formed using the cured body obtained by demolding from the release mold.SOLUTION: The method for producing a green body of the present invention is a method for producing a green body by filling a resin-containing release mold with a resin-containing slurry, curing the slurry in the release mold to form a cured body, then removing the cured body from the release mold, and drying and firing the removed cured body to obtain a green body, wherein the absolute difference between the solubility parameter of the slurry in the cured body and the solubility parameter of the slurry in the release mold is more than 0.90 (cal / cm3) 1 / 2 and less than 2.70 (cal / cm3) 1 / 2.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for producing a molded body, a set of a slurry and a release mold, a release mold, a molded body, and an optical member. [Background technology]

[0002] Gel casting is known as a method for obtaining a ceramic molded body of a desired shape. For example, Patent Document 1 discloses a method in which a slurry containing ceramic powder, resin, a dispersion medium, etc. is filled into a mold (release mold), the slurry in the mold is hardened by gelling, and the hardened slurry is then demolded (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-77143 Summary of the Invention [Problem to be solved by the invention]

[0004] The present inventors, referring to the method described in Patent Document 1, filled a release mold with a slurry to form a hardened body, but found that cracks sometimes occurred in the hardened body after it was released from the release mold, and that there was room for improvement.

[0005] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a method for manufacturing a molded body, which, when a molded body is formed using a hardened body obtained by demolding from a demolding mold, suppresses the occurrence of cracks in the hardened body after demolding. Another object of the present invention is to provide a set of a slurry and a release mold, a release mold, a molded body, and an optical member. [Means for solving the problem]

[0006] As a result of intensive research into the above-mentioned problems, the inventors discovered that if the absolute value of the difference between the solubility parameter of the resin in the cured body and the solubility parameter of the resin in the release mold is within a specific range, the occurrence of cracks in the cured body after demolding can be suppressed, and thus arrived at the present invention.

[0007] That is, the inventors have found that the above problems can be solved by the following configuration. [1] A method for producing a molded body, comprising filling a release mold containing a slurry containing a resin, curing the resin in the slurry in the release mold to form a hardened body, and then releasing the hardened body from the release mold, drying and firing the hardened body released from the release mold, The absolute value of the difference between the solubility parameter of the resin in the cured body and the solubility parameter of the resin in the release mold is 0.90 (cal / cm 3 ) 1 / 2 Super, 2.70(cal / cm 3 ) 1 / 2 A method for producing a molded body, characterized in that [2] The method for producing a molded body according to [1], wherein the release mold has an upper mold, a lower mold arranged to face the upper mold, and a spacer arranged between the upper mold and the lower mold. [3] Repeating the step of obtaining the molded body, The method for producing a molded article according to [1] or [2], comprising: removing the cured article from the release mold and then cleaning the release mold. [4] The method for producing a molded article according to any one of [1] to [3], wherein the slurry contains the resin, an inorganic material, a crosslinking agent, and a solvent. [5] the inorganic material comprises silica particles; The method for producing a molded body according to [4], wherein the content of the silica particles is 50% by mass or more based on the total mass of the slurry. [6] The method for producing a molded article according to any one of [1] to [5], wherein the glass transition temperature of the resin in the slurry is 50 to 200°C. [7] The method for producing a molded article according to any one of [1] to [6], wherein the resin in the slurry contains an epoxy resin. [8] The method for producing a molded article according to any one of [1] to [7], wherein the cured article is demolded in a liquid. [9] a slurry containing a resin; A set of a slurry and a release mold, which is used to obtain a molded body by filling the slurry with the release mold and contains a resin, The absolute value of the difference between the solubility parameter of the resin in the slurry after curing and the solubility parameter of the resin in the release mold is 0.90 (cal / cm 3 ) 1 / 2 Super, 2.70(cal / cm 3 ) 1 / 2 A set of a slurry and a release mold, characterized in that

[10] The set of the slurry and release mold according to [9], wherein the release mold has a tensile modulus of elasticity of 1.5 GPa or more.

[11] The set of the slurry and release mold according to [9] or

[10] , wherein the water absorption rate of the release mold is less than 0.1%.

[12] The set of the slurry and release mold according to any one of [9] to

[11] , wherein the content of the resin in the release mold is 60 mass % or more with respect to the total mass of the release mold.

[13] The set of the slurry and release mold according to any one of [9] to

[12] , wherein the resin in the release mold contains a cyclic olefin resin.

[14] the release mold has a recess for filling with the slurry, The set of the slurry and release mold according to any one of [9] to

[13] , wherein the aspect ratio, which is the ratio of the depth to the diameter of the recess, is 0.1 or more.

[15] The set of a slurry and a release mold according to any one of [9] to

[14] , wherein the surface roughness (Ra) of the portion of the release mold that comes into contact with the slurry is 10 μm or less.

[16] The set of a slurry and a release mold according to any one of [9] to

[15] , wherein the release mold has an upper mold and a lower mold used in a position opposite to the upper mold.

[17] The set of the slurry and the release mold according to

[16] , wherein the release mold has a spacer that is used by being placed between the upper mold and the lower mold.

[18] The set of the slurry and release mold according to

[17] , wherein at least one part selected from the group consisting of the upper mold, the lower mold, and the spacer contains a cyclic olefin resin.

[19] A release mold containing a resin, which is used to obtain a molded body by filling a slurry containing a resin, The absolute value of the difference between the solubility parameter of the resin in the slurry after curing and the solubility parameter of the resin in the release mold is 0.90 (cal / cm 3 ) 1 / 2 Super, 2.70(cal / cm 3 ) 1 / 2 Less than, release type.

[20] A release mold used to obtain a molded body, A release mold comprising a cyclic olefin resin. [twenty one] A molded body obtained by a gel casting method using a slurry, A molded article characterized in that the surface roughness (Ra) of the molded article is 10 μm or less. [twenty two] The molded body according to

[21] , wherein the ratio of the maximum thickness to the minimum thickness of the molded body is greater than 1. [twenty three] the slurry contains a resin, an inorganic material, a crosslinking agent, and a solvent; The molded article according to

[21] or

[22] , wherein the mass ratio of the inorganic material to the resin in the slurry is 50:50 to 99:1. [twenty four] An optical member obtained by using the molded article according to any one of

[21] to

[23] . [Effects of the Invention]

[0008] According to the present invention, a method for producing a molded body can be provided in which, when a molded body is formed using a hardened body obtained by demolding from a release mold, the occurrence of cracks in the hardened body after demolding is suppressed. Furthermore, the present invention can also provide a set of a slurry and a release mold, a release mold, a molded body, and an optical member. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a plan view schematically illustrating an example of a release mold used in a method for producing a molded article of the present invention. [Figure 2] FIG. 2 is a cross-sectional schematic view of a release mold for explaining an example of a method for forming a cured body in the method for producing a molded body of the present invention. [Figure 3] 2 is a cross-sectional view showing an example of a cured body after demolding in the method for producing a molded body of the present invention. FIG. [Figure 4] 1 is a cross-sectional view showing an example of a molded body obtained by the molded body manufacturing method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] The terms used in the present invention have the following meanings. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. In the present specification, in the numerical ranges described in stages, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in the present specification, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the examples. As used herein, a combination of two or more preferred embodiments is a more preferred embodiment.

[0011] [Method of manufacturing molded body] The method for producing a molded body of the present invention (hereinafter also referred to as "the present production method") comprises filling a resin-containing slurry into a release mold containing resin, curing the resin in the slurry in the release mold to form a cured body, and then releasing the cured body from the release mold, drying the released cured body, and firing the cured body to obtain a molded body, wherein the absolute value of the difference between the solubility parameter of the resin in the cured body and the solubility parameter of the resin in the release mold is 0.90 (cal / cm 3 ) 1 / 2 Super, 2.70(cal / cm 3 ) 1 / 2 is less than. According to this manufacturing method, when a molded body is formed using the cured body obtained by demolding from the release mold, the occurrence of cracks in the cured body after demolding is suppressed. The reason for this is presumably that the solubility parameters of the resins in the cured body and the release mold are within a specific range, which makes it difficult for the cured body to adhere to the release mold, improving the demoldability of the cured body.

[0012] Hereinafter, one embodiment of the present manufacturing method will be described with reference to the drawings. However, the following embodiment is an example for explaining the present invention, and the present invention is not limited to the following embodiment. Note that various modifications and substitutions can be made to the following embodiment without departing from the scope of the present invention.

[0013] [Releasable type] FIG. 1 is a schematic plan view showing an example of a release mold used in the present manufacturing method, specifically showing the configuration of each member included in the release mold when viewed from above.

[0014] The release mold 100 has an upper mold 10 , a lower mold 30 arranged so as to face the upper mold 10 , and a spacer 20 arranged between the upper mold 10 and the lower mold 30 .

[0015] The slurry contact area 14 on one surface 10a of the upper mold 10 is an area that comes into contact with the slurry 40 (described later) when the release mold 100 is filled with the slurry 40. A plurality of recesses 12 are provided in the slurry contact area 14 on the surface 10a. The recesses 12 are filled with a slurry 40.

[0016] In the example of Figure 1, a case is shown in which a plurality of recesses 12, each having a circular shape when viewed in a plane, are provided in the upper mold 10, but this is not limited to this, and when the release mold has recesses, the shape, number, arrangement, etc. of the recesses can be changed appropriately depending on the shape of the molded body.

[0017] The diameter 12d of the recess 12 (see FIG. 2 described later) is preferably 1 to 100 mm, more preferably 10 to 80 mm. The depth 12h of the recess 12 (see FIG. 2 described later) is preferably 1 to 80 mm, more preferably 10 to 50 mm. The aspect ratio (depth / diameter), which is the ratio of the depth 12h of the recess 12 to the diameter 12d, is preferably 0.1 or more, more preferably 0.3 or more, and even more preferably 0.5 or more. According to this manufacturing method, even when a release mold having recesses with an aspect ratio of 0.1 or more is used, it is possible to suppress the occurrence of cracks in the cured body after demolding. The upper limit of the aspect ratio of the recesses 12 is preferably 5.0 or less, more preferably 4.0 or less, and even more preferably 3.0 or less, in order to further prevent cracks from occurring in the cured body after demolding. Here, when the shape of the recess when viewed from above is not circular, the diameter of the recess means the circle-equivalent diameter calculated from the projected area of ​​the shape of the recess when viewed from above. The depth 12h of the recess 12 means the maximum depth of the recess 12. The diameter 12d and depth 12h of the recess 12 can be measured using, for example, a one-shot 3D shape measuring machine VR-6000 manufactured by KEYENCE Corporation.

[0018] In the example of FIG. 1, the upper mold 10 has a rectangular shape when viewed from above, but is not limited to this and may have a polygonal shape (excluding a rectangle), a circle, an ellipse, or the like. The thickness of the upper mold 10 is not particularly limited, but is preferably 10 to 150 mm.

[0019] The slurry contact area 34 on one surface 30a of the lower mold 30 is an area that comes into contact with the slurry 40 (described later) when the release mold 100 is filled with the slurry 40. In the example of FIG. 1, a mode in which no recess is provided in the lower mold 30 is shown, but the present invention is not limited to this, and the lower mold 30 may have a recess.

[0020] In the example of FIG. 1, the lower mold 30 has a rectangular shape when viewed from above, but is not limited to this and may have a polygonal shape (excluding a rectangle), a circle, an ellipse, or the like. The thickness of the lower mold 30 is not particularly limited, but is preferably 2 to 150 mm.

[0021] The spacer 20 has a spacer body 22 and a filling port 23 for filling the inside of the release mold 100 with the slurry 40 . The release mold 100 has the spacer 20, which has the advantage of making it easy to release from the mold.

[0022] When filling the inside of the release mold 100 with the slurry 40, one surface 20a of the spacer body 22 is positioned so as to contact the surface 10a of the upper mold 10, and the other surface 20b of the spacer body 22 is positioned so as to contact the surface 30a of the lower mold 30 (see Figure 2 described below). In the example of Figure 1, the shape of the spacer body 22 when viewed in a plane is shown as a circular ring with a cutout in the portion corresponding to the filling port 23, but this is not limited to this and can be changed as appropriate depending on the shape of the molded body. The thickness of the spacer 20 (spacer body 22) is not particularly limited and can be set appropriately.

[0023] The filling port 23 is used when filling the inside of the release mold 100 with the slurry 40 . The diameter (circle equivalent diameter) of the filling port 23 is preferably 0.2 to 3 mm.

[0024] The slurry contact area 24 of the spacer 20 is composed of the inner wall surface 24a of the spacer body 22 and the inner wall surface 24b of the filling port 23, and is the area that comes into contact with the slurry 40 when the slurry 40 is filled into the release mold 100.

[0025] In the example of FIG. 1, an embodiment in which the release mold 100 has the spacer 20 is shown, but the present invention is not limited to this, and the release mold used in the present manufacturing method does not necessarily have to have a spacer. Furthermore, although the embodiment in which the release mold 100 is composed of multiple parts, namely the upper mold 10, the spacer 20, and the lower mold 30, is shown, the present invention is not limited to this, and the release mold used in the present manufacturing method may be composed of a single part.

[0026] The surface roughness (Ra) of the parts of the release mold that come into contact with the slurry (in the example of FIG. 1, the surfaces of the slurry contact areas 14, 24, and 34) is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 1 μm or less, in order to further suppress the occurrence of cracks in the hardened body after demolding. The lower limit of the surface roughness (Ra) is usually 0.001 μm. The surface roughness (Ra) means the arithmetic mean roughness and is measured by a method conforming to JIS B 0601:2013.

[0027] The release mold includes a resin. Specific examples of resins that can be contained in the release mold include cyclic olefin resins, polystyrene, and vinyl chloride resins, with cyclic olefin resins being preferred in terms of providing better effects for the present invention. The release mold may contain one type of resin alone or two or more types of resin.

[0028] A cyclic olefin resin (cycloolefin polymer) is a polymer of a cyclic olefin (cycloolefin), and may be a homopolymer of a cyclic olefin, a copolymer of multiple cyclic olefins, or a copolymer of a cyclic olefin and another olefin. The cyclic olefin resin may be a polymer obtained by hydrogenating at least a portion of the carbon-carbon unsaturated bonds of a cyclic olefin polymer. Specific examples of cyclic olefins include norbornene, cyclopentadiene, dicyclopentadiene, cyclohexadiene, methanotetrahydrofluorene, tetracyclododecene, and derivatives thereof. The cyclic olefin may have at least one group selected from the group consisting of an alkyl group, an alkylene group, a vinyl group, an alkoxycarbonyl group, and an alkylidene group. Specific examples of other olefins include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, and derivatives thereof. The cyclic olefin resin can be obtained by addition polymerization, metathesis polymerization, etc. of these cycloolefins. The cyclic olefin resin may also be a cyclized polymer of a conjugated diene. As the cyclic olefin resin, commercially available products may be used, and examples thereof include Zeonor (manufactured by Zeon Corporation), Zeonex (manufactured by Zeon Corporation), and Apel (manufactured by Mitsui Chemicals, Inc.).

[0029] As shown in FIG. 1, when a release mold 100 having an upper mold 10, a lower mold 30, and a spacer 20 is used, it is preferable that at least one part selected from the group consisting of the upper mold 10, the lower mold 30, and the spacer 20 contains a resin, and it is preferable that it contains a cyclic olefin resin. In order to obtain a more excellent effect of the present invention, it is preferable that the part having the recess (upper mold 10 in the example of FIG. 1) in the release mold contains a resin, and it is more preferable that it contains a cyclic olefin resin.

[0030] The solubility parameter (Sp value) of the resin in the release mold is 8.00 to 9.99 (cal / cm 3 ) 1 / 2 is preferable, and 8.20 to 9.80 (cal / cm 3 ) 1 / 2 More preferably, 8.30 to 9.70 (cal / cm 3 ) 1 / 2 More preferably, 8.40 to 9.50 (cal / cm 3 ) 1 / 2 is particularly preferred. The Sp value of the resin in the release mold means the solubility parameter δ calculated by the following formula (1) using the ΔF and Δv values ​​of various atomic groups by Okitsu Toshinao, as described in "Adhesion," Polymer Publishing Association, 1996, Vol. 40, No. 8, pp. 342-350. In addition, in the case of a mixture of two or more resins or when the resin is a copolymer, the solubility parameter δ is calculated by the following formula (2): mix means. δ=ΣΔF / ΣΔv (1) δ mix =φ1δ1+φ2δ2+ φ n δ n (2) In formula (1), ΔF and Δv respectively represent the ΔF (molar gravitational constant) and Δv (molar volume) of various atomic groups according to Okitsu. In formula (2), φ represents the volume fraction or mole fraction, and is given by φ1 + φ2 + φ. n =1.

[0031] The release mold may contain rubber. In this case, it is preferable that at least one of the components constituting the release mold contains rubber. Specifically, as shown in FIG. 1, when a release mold 100 having an upper mold 10, a lower mold 30, and a spacer 20 is used, an embodiment in which the spacer 20 contains rubber can be mentioned. Specific examples of rubber that can be contained in the release mold include silicone rubber, fluorine-based rubber, styrene-butadiene rubber, and chloroprene rubber, with silicone rubber being preferred because of its excellent chemical stability. The spacer 20 is not limited to a configuration containing rubber, and may contain a resin such as a fluororesin (for example, polytetrafluoroethylene).

[0032] The release mold may contain glass. In this case, it is preferable that at least one of the components constituting the release mold contains glass. Specifically, as shown in FIG. 1, when a release mold 100 having an upper mold 10, a lower mold 30, and a spacer 20 is used, it is preferable that the lower mold 30 contains glass. The lower mold 30 is not limited to an embodiment in which it contains glass, but may contain a resin such as the above-mentioned cyclic olefin resin, polystyrene, or vinyl chloride resin.

[0033] When the release mold contains a resin, the content of the resin contained in the release mold is preferably 60% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, based on the total mass of the release mold, in order to obtain better effects of the present invention. The upper limit of the content of the resin contained in the release mold is preferably 100% by mass, more preferably 99% by mass or less, and even more preferably 98% by mass or less. In order to obtain a more excellent effect of the present invention, it is preferable that the content of the resin contained in at least the part provided with the recess (upper mold 10 in the example of FIG. 1) in the release mold satisfies the above value.

[0034] The release mold may contain other components in addition to those described above, such as inorganic fillers and metals. The content of other components that may be contained in the release mold is preferably 2% by mass or less, and more preferably 1% by mass or less, based on the total mass of the release mold.

[0035] The tensile modulus of elasticity of the release mold is preferably 1.5 GPa or more, more preferably 2.0 GPa or more, and even more preferably 2.5 GPa or more, from the viewpoint of the shape stability of the cured product. The tensile modulus of elasticity of the release mold is preferably 3.5 GPa or less, more preferably 3.3 GPa or less, and even more preferably 3.0 GPa or less, from the viewpoint of the risk of breakage. In order to obtain better effects of the present invention, it is preferable that the tensile modulus of elasticity of at least the resin-containing part in the release mold satisfies the above value. The tensile modulus of elasticity of the release mold is measured by a method conforming to JIS K 7161-1:2014.

[0036] The water absorption of the release mold is preferably less than 0.1%, more preferably 0.05% or less, and even more preferably 0.03% or less. When the water absorption of the release mold is less than 0.1%, a molded product with excellent precision can be obtained. Furthermore, when the hardened product is demolded in a liquid (particularly in water), swelling of the release mold is suppressed, making it easier to reuse the release mold in the production of hardened products. The lower limit of the water absorption rate of the release mold is usually 0.01%. In order to obtain a more excellent effect of the present invention, it is preferable that the water absorption rate of at least the resin-containing part of the release mold satisfies the above value. The water absorption rate of the release mold is measured by a method in accordance with JIS K 7209:2000.

[0037] The method for producing the release mold can be any known method and is not particularly limited. For example, when a release mold containing a resin is to be obtained, an injection molding method or the like can be used.

[0038] 〔slurry〕 The slurry preferably contains a resin, and further contains an inorganic material, a crosslinking agent, and a solvent.

[0039] <Resin> The resin in the slurry is preferably a curable resin. The curable resin is a resin that begins to harden upon heating or upon reaction with a crosslinking agent, etc., and is preferably a resin having a curable group. Specific examples of the curable group include an epoxy group (oxiranyl group), a hydroxy group, a carboxy group, an amino group, an alkoxy group, and an isocyanate group.

[0040] Specific examples of the resin include melamine resin, phenol resin, epoxy resin, acrylic resin, urethane resin, etc. Among them, epoxy resin is preferred in that it provides a molded product with high shape retention and cures in the air. Specific examples of epoxy resins include diglycidyl ether type epoxy resins of bisphenols such as bisphenol A type and bisphenol F type, phenol novolac type epoxy resins, cresol novolac type epoxy resins, glycidyl amine type epoxy resins, glycidyl ether type epoxy resins such as aliphatic epoxy resins, glycidyl ester type epoxy resins, methyl glycidyl ether type epoxy resins, cyclohexene oxide type epoxy resins, and rubber-modified epoxy resins. Examples of monomers that react to form acrylic resins include acrylic monomers such as acrylic acid, methacrylic acid amide, methacrylic acid, methoxy(polyethylene glycol) monomethacrylate, alkyl acrylate, alkyl methacrylate, dimethylaminoethyl methacrylate, hydroxyalkyl acrylate, hydroxyalkyl methacrylate, methacrylatoethyltrimethylammonium chloride, etc. These acrylic monomers may be used alone or in combination of two or more. The acrylic resin may also be a copolymer of the above acrylic monomer with other monomers, such as n-vinylpyrrolidone, acrylamide, alkylacrylamide, alkylmethacrylamide, dimethylaminopropylmethacrylamide, hydroxyalkylacrylamide, hydroxyalkylmethacrylamide, methacrylamidepropyltrimethylammonium chloride, p-styrenesulfonic acid, and p-styrenesulfonate salts.

[0041] When an epoxy resin is used as the resin, the average molecular weight is preferably 20 to 30,000. The average number of epoxy functional groups in the epoxy resin is preferably 2 to 10. This ensures a certain level of strength when demolded and also ensures a sufficient usable time when cast.

[0042] The glass transition temperature (Tg) of the resin in the slurry is preferably from 50 to 200°C, more preferably from 60 to 190°C, and even more preferably from 70 to 180°C, from the viewpoint of ease of handling. The Tg of the resin is the midpoint glass transition temperature measured by differential scanning calorimetry (DSC) in accordance with JIS K 7121:2012.

[0043] The content of the resin in the slurry is preferably 0.1 to 30% by mass, more preferably 0.5 to 20% by mass, and even more preferably 1 to 15% by mass, based on the total mass of the slurry.

[0044] <Inorganic materials> The slurry preferably contains an inorganic material, and the inorganic material is preferably in particulate (powder) form. Specific examples of inorganic materials include silica, silicon nitride, aluminum nitride, titanium nitride, silicon carbide, aluminum oxide, and zirconium oxide, and among these, silica is preferred because it provides better effects of the present invention.

[0045] From the viewpoint of shape stability, the content of the inorganic material (preferably silica particles) is preferably 50% by mass or more, more preferably 55% by mass or more, and even more preferably 60% by mass or more, based on the total mass of the slurry. From the viewpoint of handling of the slurry, the content of the inorganic material (preferably silica particles) is preferably 98 mass % or less, more preferably 95 mass % or less, and even more preferably 90 mass % or less, based on the total mass of the slurry.

[0046] The mass ratio of the inorganic material (preferably silica particles) to the resin (inorganic material:resin) in the slurry is preferably 50:50 to 99:1, more preferably 82:18 to 98:2, and even more preferably 87:13 to 94:6, in order to satisfactorily form a molded body.

[0047] <Crosslinking agent> The slurry preferably contains a cross-linking agent. The crosslinking agent cures the resin by crosslinking, and may be selected depending on the resin to be used. For example, examples of crosslinking agents (curing agents) for epoxy resins include amine-based curing agents, acid anhydride-based curing agents, polyamide-based curing agents, etc. Amine-based curing agents are preferred because they react quickly, and acid anhydride-based curing agents are preferred because they can give cured products with excellent thermal shock resistance. Examples of the amine-based curing agent include aliphatic amines, alicyclic amines, aromatic amines, modified polyaminoamides, and modified aliphatic polyamines, and any of monoamines, diamines, triamines, and polyamines can be used. Examples of the acid anhydride curing agent include methyltetrahydrophthalic anhydride and dibasic acid polyanhydride.

[0048] The content of the crosslinking agent is preferably 1 to 50 parts by mass, more preferably 5 to 20 parts by mass, relative to 100 parts by mass of the resin in the slurry.

[0049] <Solvent> The slurry preferably contains a solvent. By using a solvent, the viscosity of the mixture of raw materials used can be adjusted to form a slurry, which can facilitate filling of the slurry into the release mold. Specific examples of the solvent include pure water such as ion-exchanged water and distilled water, alcohols, and other organic solvents. Among these, it is preferable to use an aqueous solvent from the viewpoint of production costs and environmental impact.

[0050] The content of the solvent is preferably from 5 to 39 mass %, more preferably from 10 to 45 mass %, and even more preferably from 15 to 40 mass %, based on the total mass of the slurry.

[0051] <Other ingredients> The slurry may contain components other than those mentioned above (hereinafter also referred to as "other components"). Specific examples of other components include curing catalysts, dispersants, pH adjusters, sintering aids, surfactants, viscosity adjusters, etc. These may be added in the required amounts as needed.

[0052] <Method of preparing slurry> The method for preparing the slurry is not particularly limited, but for example, a method may be used in which a dispersion containing an inorganic material and a solvent is obtained, and then components other than the inorganic material are mixed with the dispersion.

[0053] [Process] In this manufacturing method, a slurry containing a resin is filled into a release mold containing the resin, the resin in the slurry is cured in the release mold to form a hardened body, and the hardened body is then released from the release mold, dried, and fired to obtain a molded body. Preferably, the present production method further includes a step of degreasing the dried hardened body after drying the demolded hardened body and before firing. As an example of a preferred embodiment of the present production method, an embodiment including the following steps 1 to 5 will be described below. Step 1: A step in which a resin-containing slurry is filled into a resin-containing mold, and the resin in the slurry is cured within the mold to form a cured body. Step 2: Removing the hardened body from the release mold Step 3: Drying the demolded hardened body Step 4: Degreasing the hardened body after drying Step 5: A step of firing the degreased hardened body to obtain a molded body.

[0054] <Process 1> Step 1 is a step of filling a resin-containing slurry into a resin-containing release mold, and curing the resin in the slurry within the release mold to form a cured body. 2 is a schematic cross-sectional view of a release mold 100 for explaining an example of a method for forming a cured body 42 in this manufacturing method, and is a cross-sectional view taken along line A-A' of the release mold 100 in FIG. 1. Step 1 will be described with reference to FIG. 2.

[0055] 2, the spacer body 22 is placed so that one surface 20a thereof contacts the surface 10a of the upper mold 10, and the other surface 20b thereof contacts the surface 30a of the lower mold 30. This creates a space defined by the upper mold 10, the spacer 20, and the lower mold 30. Next, the slurry 40 is poured into the spacer 20 through the filling port 23 (see FIG. 1) so that the space generated inside the release mold 40 is filled with the slurry 40. The method for pouring the slurry is not particularly limited, and examples thereof include a method using a known pump or the like.

[0056] Next, the resin in the slurry 40 is cured to obtain a cured body 42. Here, depending on the type of resin in the slurry and the type of crosslinking agent, the resin may be cured at room temperature (18 to 25°C) or under heat (for example, 40 to 80°C). For example, when the above-mentioned epoxy resin is used as the resin in the slurry 40, the resin can be cured at room temperature. Here, since the release mold 100 contains a resin, when the resin is cured at room temperature, deterioration of the release mold 100 due to heat can be suppressed. When the resin in the slurry is cured at room temperature, the curing time is preferably, for example, 5 to 48 hours. When the resin in the slurry is cured under heating, the curing time is preferably, for example, 1 to 24 hours.

[0057] The solubility parameter (SP value) of the resin contained in the cured body (i.e., the resin after curing) is 8.00 to 12.00 (cal / cm 3 ) 1 / 2 is preferable, and 9.00 to 11.50 (cal / cm 3 ) 1 / 2 More preferably, 9.50 to 11.00 (cal / cm 3 ) 1 / 2 is more preferred. The SP value of the resin contained in the cured body (that is, the resin after curing) is calculated in the same manner as the Sp value of the resin in the release mold described above.

[0058] (Difference in SP value) The absolute value of the difference between the SP value of the resin in the hardened body and the SP value of the resin in the release mold is 0.90 (cal / cm 3 ) 1 / 2 Super, 2.70(cal / cm 3 ) 1 / 2 and the effect of the present invention is more excellent, it is 1.00 to 2.60 (cal / cm3 ) 1 / 2 is preferable, and 1.50 to 2.50 (cal / cm 3 ) 1 / 2 is more preferred.

[0059] <Process 2> Step 2 is a step of releasing the hardened body from the release mold. 2, the cured body 42 can be released, for example, by separating the upper mold 10, the lower mold 30, and the release mold 100 along the thickness direction, and then removing the spacer 20. In this way, the cured body 42 after release is obtained (see FIG. 3).

[0060] The demolding of the cured body may be carried out in the air, but is preferably carried out in a liquid. When the demolding of the cured body is carried out in a liquid, the liquid penetrates between the cured body and the release mold, making it easier to demold the cured body, and as a result, the occurrence of cracks in the cured body is further suppressed. Examples of the liquid include water and ethanol, with water being preferred. The temperature of the liquid is preferably 18 to 30°C. The time for immersing the cured body in the liquid is preferably 1 to 30 minutes.

[0061] <Process 3> Step 3 is the process of drying the demolded hardened body. This removes volatile components such as the solvent contained in the hardened body, as well as moisture adhering to the surface of the hardened body. By going through step 3, the hardened body can be densified.

[0062] In step 3, it is preferable to carry out drying under conditions that do not cause cracks in the cured product. In this case, the drying temperature in step 3 is preferably 18 to 90° C. Furthermore, the relative humidity during drying of the cured product after demolding is preferably 50 to 99%. The drying time may be adjusted as appropriate.

[0063] Step 3 is preferably carried out until the ratio of the mass of the solvent in the cured body after drying to the mass of the solvent in the cured body before drying (after drying / before drying) becomes 10% or less.

[0064] <Step 4> Step 4 is a step of degreasing the dried cured body. This allows the resin, non-volatile solvent, etc. to be removed from the dried cured body. In step 4, it is preferable to almost completely remove components that inhibit the firing in step 5. By carrying out step 4, the occurrence of voids, etc. in the molded body obtained in step 5 can be suppressed.

[0065] The degreasing method in step 4 is preferably a method in which the cured body after drying is heated. In this case, the heating temperature is preferably 200 to 800° C. The heating time is preferably 5 to 96 hours.

[0066] Step 4 is preferably carried out until the ratio of the mass of resin in the cured body after degreasing to the mass of resin in the cured body before degreasing (after degreasing / before degreasing) becomes 1% or less.

[0067] <Process 5> Step 5 is a step of firing the degreased hardened body to obtain a molded body. When the hardened body contains an inorganic material, firing results in a sintered body in which the inorganic material in the hardened body is sintered together. For example, when silica particles are used as the inorganic material, firing results in the silica particles being sintered together to obtain a quartz glass molded body.

[0068] The firing method in step 5 can be any known method and is not particularly limited. For example, the firing temperature in step 5 is preferably 1000 to 1500° C. The firing time is preferably 0.1 to 48 hours.

[0069] The shape, size, thickness, etc. of the molded body obtained in step 5 are not particularly limited and are designed appropriately depending on the application. An example of the molded body obtained in step 5 is the molded body 44 shown in FIG. In the molded body 44, the ratio (H1 / H2) of the maximum thickness H1 to the minimum thickness H2 is preferably greater than 1, more preferably 1.2 or greater, and even more preferably 1.3 or greater. According to the present manufacturing method, even in the case of a molded body having unevenness like this, the occurrence of cracks and the like is suppressed, and a molded body with high precision can be obtained. The upper limit of the ratio (H1 / H2) is preferably 80 or less, more preferably 60 or less, and even more preferably 50 or less.

[0070] The surface roughness (Ra) of the molded body obtained in step 5 is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 1 μm or less. The lower limit of the surface roughness (Ra) of the molded body obtained in step 5 is usually 0.001 μm. The surface roughness (Ra) of the molded body obtained in step 5 means the arithmetic mean roughness, and is measured by the method described above. As a method for obtaining a molded article having a surface roughness (Ra) of 10 μm or less, for example, a method using a release mold having a surface roughness Ra of 10 μm or less can be mentioned.

[0071] <Other processes> In the present production method, the step of obtaining a molded body (specifically, the series of steps 1 to 5 above) may be repeated. In this case, the present production method preferably includes a step of cleaning the release mold after releasing the cured body from the release mold. This allows the release mold to be reused and also prevents cracks in the cured body obtained using the cleaned release mold. The method for cleaning the release mold is not particularly limited, and examples thereof include a method of cleaning with water or the like.

[0072] [Slurry and release mold set] The set of a slurry and a release mold of the present invention (hereinafter also referred to as "this set") is a set of a slurry and a release mold having a slurry containing a resin and a release mold containing a resin, which is used to obtain a molded body by filling the slurry, and the absolute value of the difference between the solubility parameter of the resin after curing and the solubility parameter of the resin in the release mold is 0.90 (cal / cm3 ) 1 / 2 Super, 2.70(cal / cm 3 ) 1 / 2 is less than. When this set is used, when a molded article is formed using the hardened body obtained by removing it from the release mold, the hardened body is prevented from cracking after being removed from the mold. The slurry and release mold in this set are the same as those shown in the above-described production method, including the preferred embodiments, and therefore a description thereof will be omitted.

[0073] [Releasable type] One embodiment of the release mold of the present invention (hereinafter also referred to as "the release mold of the first embodiment") is a release mold containing a resin, which is used to obtain a molded body by filling a slurry containing a resin, and the absolute value of the difference between the solubility parameter of the resin after curing and the solubility parameter of the resin in the release mold is 0.90 (cal / cm 3 ) 1 / 2 Super, 2.70(cal / cm 3 ) 1 / 2 is less than. By using the release mold of the first embodiment, when a molded body is formed using a hardened body obtained by demolding from the release mold, the occurrence of cracks in the hardened body after demolding is suppressed. In the release mold of the first embodiment, the release mold and slurry are the same as those shown in the present manufacturing method described above, including the preferred embodiments, and therefore a description thereof will be omitted.

[0074] Another embodiment of the release mold of the present invention (hereinafter also referred to as "a release mold of a second embodiment") is a release mold used to obtain a molded article, and contains a cyclic olefin resin. By using the release mold of the second embodiment, when a molded body is formed using the hardened body obtained by demolding from the release mold, the occurrence of cracks in the hardened body after demolding is suppressed. The details of the release mold of the second embodiment are the same as those of the release mold shown in the present manufacturing method described above, including the preferred embodiments, and therefore the description thereof will be omitted. Examples of the hardened body and molded body that can be formed using the release mold of the second embodiment include the hardened body and molded body shown in the present manufacturing method described above.

[0075] [Molded body] The molded article of the present invention (hereinafter also referred to as "the molded article") is a molded article obtained by a gel casting method using a slurry, and has a surface roughness (Ra) of 10 μm or less.

[0076] The present molded article is preferably a molded article obtained by the above-described present manufacturing method, and therefore the above-described present manufacturing method can be adopted for the gel casting method using a slurry.

[0077] The surface roughness (Ra) of the present molded article is 10 μm or less, preferably 5 μm or less, and more preferably 1 μm or less. The lower limit of the surface roughness (Ra) of the present molded product is usually 0.001 μm. The surface roughness (Ra) of the present molded body means the arithmetic mean roughness, and is measured by the method described above. A method for obtaining a molded article having a surface roughness (Ra) of 10 μm or less may be, for example, a method using a release mold used in the present production method, which has a surface roughness Ra of 10 μm or less.

[0078] The shape, size, thickness, etc. of the present molded product are not particularly limited and are designed appropriately depending on the intended use. One example of the present molded product is molded product 44 shown in FIG.

[0079] [Optical components] The optical member of the present invention (hereinafter also referred to as "the present optical member") is obtained using the present molded article described above. Specific examples of the optical component include light guides, filters, and lenses used in wearable devices (e.g., projector-equipped glasses, eyeglass-type displays, goggle-type displays, virtual reality and augmented reality display devices, virtual image display devices, etc.); and lenses and cover glasses used in LED light sources for in-vehicle cameras, robot visual sensors, analytical instruments, etc. The optical member can also be used as a glass substrate for organic EL, a substrate for wafer-level lens arrays, a substrate for lens units, a substrate for lens formation by etching, an optical waveguide, and the like. [Example]

[0080] The present invention will be described in detail below with reference to examples. Examples 1 to 3 are working examples, and Examples 4 and 5 are comparative examples. However, the present invention is not limited to these examples.

[0081] [Water absorption rate of release mold] Test pieces for measuring water absorption were prepared in the same manner as in the manufacturing method of the release molds of each example described below. The water absorption (%) of the prepared test piece was determined by a method in accordance with JIS K 7209:2000 (Method A). The results are shown in Table 1.

[0082] [Release mold tensile modulus] Test pieces for measuring the tensile modulus were prepared in the same manner as in the manufacturing method of the release molds of each example described below. The tensile modulus (GPa) of the prepared test specimen was determined according to the method of JIS K 7161-1:2014. The results are shown in Table 1.

[0083] [SP value] The SP value of the resin in the release mold and the SP value of the resin in the cured body (that is, the SP value of the resin in the slurry after curing) were calculated using the above-mentioned formula (1). The SP values ​​of the resin in the release mold are shown in Table 1. The absolute value of the difference between the SP value of the resin in the cured body and the SP value of the resin in the release mold is also shown in Table 1 (difference in SP values).

[0084] [Demolding test] [Mold removal test 1] In the manufacturing method of each molded body in each example described below, when a hardened body formed using the release mold for demolding test 1 was demolded from the demolding mold, the hardened body was evaluated according to the following criteria based on the number of convex portions (shapes corresponding to the concave portions of the release mold) formed on the demolded hardened body that could be demolded without cracking. The results are shown in Table 1. A rating of B or higher can be said to have suppressed the occurrence of cracks in the hardened body after demolding. A: The number of protrusions that could be removed without cracking was 20 to 25. B: The number of protrusions that could be removed without cracking was 10 to 19. C: The number of protrusions that could be removed without cracking was 1 to 9. D: The number of protrusions that could be removed without cracking was 0

[0085] [Demolding test 2] In the manufacturing method of the molded body of each example described below, when a hardened body formed using the release mold for demolding test 2 was demolded from the demolding mold, the hardened body was evaluated according to the following criteria based on the number of convex portions (shapes corresponding to the concave portions of the release mold) formed on the demolded hardened body that could be demolded without cracking. The results are shown in Table 1. A rating of C or higher can be said to have suppressed the occurrence of cracks in the hardened body after demolding. A: The number of protrusions that could be removed without cracking was 15 to 20. B: The number of protrusions that could be removed without cracking was 7 to 14. C: The number of protrusions that could be removed without cracking was 1 to 6. D: The number of protrusions that could be removed without cracking was 0

[0086] [Example 1] [Preparation of release mold for demolding test 1] A rectangular injection-molded resin plate (100 mm long, 100 mm wide, and 10 mm thick) was obtained by injection molding a cyclic olefin resin (trade name "ZEONEX" manufactured by Zeon Corporation). Next, using a drill with a diameter of 5.5 mm, 25 recesses (diameter 5.5 mm, depth 1.5 mm, aspect ratio 0.27) were formed in the injection-molded resin plate at intervals of 10 mm, to obtain an upper mold for a release mold (see upper mold 10 in Figure 1). Also, a glass plate (length 100 mm, width 100 mm, thickness 2 mm) with no recesses on the surface was prepared as the lower mold of the release mold (see lower mold 30 in FIG. 1). Furthermore, a ring-shaped silicone rubber (outer diameter 100 mm, inner diameter 74 mm, thickness 2 mm) was provided with a 3 mm diameter notch to serve as a slurry filling port, to obtain a release type spacer (see spacer 20 in Figure 1). The obtained upper mold, spacer, and lower mold were stacked in this order to form a release mold for demolding test 1 (see release mold 100 in FIG. 2).

[0087] [Preparation of release mold for demolding test 2] A rectangular injection-molded resin plate (150 mm long, 150 mm wide, and 10 mm thick) was obtained by injection molding a cyclic olefin resin (trade name "ZEONEX" manufactured by Zeon Corporation). Next, using a drill with a diameter of 3 mm, 20 recesses (3 mm diameter, 6 mm deep, aspect ratio 2) were formed in the injection-molded resin plate at intervals of 10 mm, to obtain an upper mold for a release mold. Also, a cyclic olefin resin was injection molded to obtain a rectangular injection molded resin plate (150 mm long, 150 mm wide, 10 mm thick) with no recesses on the surface, which was used as the lower mold of the release mold. In addition, a PTFE (polytetrafluoroethylene) resin plate (thickness 1.5 mm) was processed to obtain a ring-shaped resin plate (outer diameter 150 mm, inner diameter 120 mm, thickness 1.5 mm), and then a cutout with a diameter of 2 mm was made in part of the ring-shaped resin plate to serve as a slurry filling port, thereby obtaining a release-type spacer. The obtained upper mold, spacer, and lower mold were stacked in this order to form a release mold for demolding test 2.

[0088] [Preparation of Slurry] A dispersion was obtained by dispersing raw silica powder (purity 99.9% or more, average particle size 100 nm) (62.9 parts by mass) and a solvent (37.1 parts by mass) in which a pH adjuster was added to water to adjust the pH to 13 using an ultrasonic homogenizer. The obtained dispersion (94.1 parts by mass), a water-soluble epoxy resin (Tg: 168°C, SP value after curing: 10.90) (5.0 parts by mass), and an aliphatic amine curing agent (0.9 parts by mass) were mixed and degassed using a planetary centrifugal mixer equipped with a vacuum pump to obtain slurry 1.

[0089] [Production of Molded Product] <Production of a molded body using a demolding mold for demolding test 1> First, the slurry 1 was filled into a demolding mold for demolding test 1, and then left to stand at 23° C. for 48 hours to harden the resin in the slurry 1 in the demolding mold, thereby forming a hardened body. Next, the cured body was demolded from the demolding mold. Specifically, after removing the lower mold, the spacer and the upper mold were removed from the cured body. The state of the cured body after demolding was evaluated based on the demolding test 1 described above. The demolded hardened body was then dried at 60°C and 80% RH for 24 hours. The dried hardened body was then degreased by holding it in an electric furnace at 550°C for 24 hours. The degreased molded body was then fired at 1125°C in a vacuum to obtain a quartz glass molded body.

[0090] <Production of a molded body using a demolding mold for demolding test 2> A quartz glass molded body was obtained in the same manner as in "Production of a molded body using a release mold for demolding test 1" above, except that a release mold for demolding test 2 was used. The state of the hardened body after demolding was evaluated based on the demolding test 2 described above.

[0091] [Examples 2 to 5] Molded articles in Examples 2 to 5 were obtained in the same manner as in Example 1, except that the resins listed in Table 1 were used instead of the cyclic olefin resin as the resin constituting the upper mold of the release mold. The state of the cured article after demolding was evaluated based on the demolding test 1 and demolding test 2 described above.

[0092] [Table 1]

[0093] As shown in Table 1, the absolute value of the difference between the SP value of the resin in the hardened body and the SP value of the resin in the release mold is 0.90 (cal / cm 3 ) 1 / 2 Super, 2.70(cal / cm 3 ) 1 / 2 It was confirmed that when the temperature was less than 100°C, the occurrence of cracks in the hardened body after demolding was suppressed (Examples 1 to 3). [Explanation of symbols]

[0094] 10 Upper mold 10a surface 12 recess 12d diameter 12h depth 14 Slurry contact area 20 spacers 20a surface 20b surface 22 Spacer body 23 Filling port 24 Slurry contact area 24a Inner wall 24b Inner wall 30 Lower mold 30a surface 34 Slurry contact area 40 Slurry 42 Hardened body 44 Molded body 100 Release mold H1 Maximum thickness H2 minimum thickness

Claims

1. A method for producing a molded body, comprising filling a release mold containing a resin with a slurry, curing the resin in the slurry in the release mold to form a hardened body, and then releasing the hardened body from the release mold, drying and firing the hardened body released from the release mold, The absolute value of the difference between the solubility parameter of the resin in the cured body and the solubility parameter of the resin in the release mold is 0.90 (cal / cm ３ ) １／２ Super, 2.70 (cal / cm ３ ) １／２ A method for producing a molded body, characterized in that

2. The method for producing a molded body according to claim 1 , wherein the release mold has an upper mold, a lower mold arranged to face the upper mold, and a spacer arranged between the upper mold and the lower mold.

3. Repeating the step of obtaining the molded body, The method for producing a molded article according to claim 1 or 2, further comprising cleaning the release mold after releasing the cured article from the release mold.

4. The method for producing a molded article according to claim 1 or 2, wherein the slurry contains the resin, an inorganic material, a crosslinking agent, and a solvent.

5. the inorganic material comprises silica particles; The method for producing a molded article according to claim 4, wherein the content of the silica particles is 50% by mass or more based on the total mass of the slurry.

6. The method for producing a molded article according to claim 1 or 2, wherein the glass transition temperature of the resin in the slurry is 50 to 200°C.

7. The method for producing a molded article according to claim 1 or 2, wherein the resin in the slurry includes an epoxy resin.

8. The method for producing a molded article according to claim 1 or 2, wherein the hardened body is demolded in a liquid.

9. a slurry containing a resin; A set of a slurry and a release mold, which is used to fill the slurry to obtain a molded body, and which includes a release mold containing a resin, The absolute value of the difference between the solubility parameter of the resin in the slurry after curing and the solubility parameter of the resin in the release mold is 0.90 (cal / cm ３ ) １／２ Super, 2.70 (cal / cm ３ ) １／２ A set of a slurry and a release mold, characterized in that

10. The set of slurry and release mold according to claim 9, wherein the release mold has a tensile modulus of elasticity of 1.5 GPa or more.

11. The set of slurry and release mold according to claim 9 or 10, wherein the release mold has a water absorption rate of less than 0.1%.

12. The set of slurry and release mold according to claim 9 or 10, wherein the content of the resin in the release mold is 60 mass % or more with respect to the total mass of the release mold.

13. The set of slurry and release mold according to claim 9 or 10, wherein the resin in the release mold comprises a cyclic olefin resin.

14. the release mold has a recess for filling with the slurry, The set of slurry and release mold according to claim 9 or 10, wherein an aspect ratio, which is a ratio of the depth to the diameter of the recess, is 0.1 or more.

15. The surface roughness (Ra) of the portion of the release mold that comes into contact with the slurry is 10 μm or less. The set of the slurry and the release mold according to claim 9 or 10.

16. The release mold has an upper mold and a lower mold used at a position facing the upper mold. The set of the slurry and the release mold according to claim 9 or 10.

17. The release mold has a spacer disposed between the upper mold and the lower mold. The set of the slurry and the release mold according to claim 16.

18. At least one component selected from the group consisting of the upper mold, the lower mold, and the spacer contains a cyclic olefin resin. The set of the slurry and the release mold according to claim 17.

19. A release mold used to obtain a molded body by filling a slurry containing a resin, the release mold containing a resin. The absolute value of the difference between the solubility parameter of the resin in the slurry after curing and the solubility parameter of the resin in the release mold is 0.90 (cal / cm ３ ) １／２ Super, 2.70 (cal / cm ３ ) １／２ Less than, release type.

20. A release mold used to obtain a molded body. A release mold characterized by containing a cyclic olefin resin.

21. A molded body obtained by a gel casting method using a slurry, The surface roughness (Ra) of the molded body is 10 μm or less. The molded body.

22. The ratio of the maximum thickness to the minimum thickness of the molded body is greater than 1. The molded body according to claim 21.

23. The slurry contains a resin, an inorganic material, a crosslinking agent, and a solvent. The mass ratio of the inorganic material to the resin in the slurry is 50:50 to 99:%. The molded body according to claim 21 or 22.

24. An optical member characterized by being obtained using the molded body according to claim 21.

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