Polyurethane composite material, method for producing molded article made of said polyurethane composite material, and material for dental cutting

Abstract

To provide a polyurethane-based composite material in which fillers are dispersed in a matrix composed of a polyurethane-based resin having a content of a polyurethane component of more than 80 mass% and having a crosslinked structure, and which is uniform and excellent in strength and water resistance, and to provide a method of producing the molded article.SOLUTION: A diisocyanate (a2) is added to a first raw material composition containing a radically polymerizable diol (a1), a non-polyaddition-type radically polymerizable monomer (B), a thermal polymerization initiator (C) having a 10 hour half-life temperature: T10 of 60°C or more and a filler (D) to obtain a radically polymerizable group-containing polyurethane component (A) having a number average molecular weight of 1500 to 5000, which is a polyadduct of (a1) and (a2). A second raw material composition containing the radically polymerizable group-containing polyurethane component (A) content ratio of which is more than 80 mass% in the organic component is prepared and is filled in a mold in a state where the composition is maintained at a temperature of 40 to (T10-15)°C, and is subsequently cured by radical polymerization at (T10-10) to (T10+25)°C.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polyurethane composite material, a method for producing a molded article made of the polyurethane composite material, and a material for dental cutting. [Background technology]

[0002] In dental treatment, one method for fabricating dental prostheses, such as inlays, onlays, crowns, bridges, and implant superstructures, is to use a dental CAD / CAM system for machining. A dental CAD / CAM system uses a computer to design dental prostheses based on three-dimensional coordinate data, and then fabricates the crown restoration using a machining machine. Various materials, including glass ceramics, zirconia, titanium, and resin, are used for machining. Resin-based dental machining materials include curable compositions containing inorganic fillers such as silica, polymerizable monomers such as methacrylate, and polymerization initiators, which are cured into block or disk shapes. Machining materials using computer systems has attracted increasing interest due to their improved workability, resulting from the reduced number of steps compared to conventional dental prosthesis fabrication methods, as well as the aesthetic and strength properties of the cured products.

[0003] Such cutting materials are mainly used for dental crowns, and higher strength is required when they are used for molar crowns or bridges. However, current cutting materials are based on (meth)acrylic resins, and the strength limitations are an issue.

[0004] In contrast, polyurethane resins are generally known to have high strength, and their use as dental materials has been considered. For example, Patent Document 1 describes a polyurethane composite material that takes advantage of the "high strength" characteristic of polyurethane resins while improving their drawback of low water resistance by introducing a crosslinked structure formed by polymerization of radically polymerizable groups into the polyurethane resin (hereinafter, a polyurethane composite material into which a crosslinked structure has been introduced in this way will also be referred to as a "crosslinked structure-introduced polyurethane composite material"), and a method for producing the same.

[0005] That is, Patent Document 1 describes that a raw material composition containing as raw materials a diol compound (a1) having one or more radically polymerizable groups; a diisocyanate compound (a2); a polymerizable monomer (B) having one or more radically polymerizable groups in the molecule and not undergoing a polyaddition reaction with either the diol compound (a1) or the diisocyanate compound (a2) (hereinafter also referred to as a “non-polyaddition radically polymerizable monomer”); a radical polymerization initiator (C); and a filler (D), and that a1 and a2 are polyadded to form a polyurethane component (A) of a specific molecular weight, and then the radically polymerizable groups contained in (A) are reacted with (B) to introduce a crosslinked structure, thereby producing a polyurethane composite material that is uniform throughout, has excellent strength and water resistance, and is suitable as a material for dental cutting processing. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] WO2021 / 153446 issue Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the polyurethane composite material described in Patent Document 1, in order to maintain good uniformity, the proportion of the polyurethane component in the resin component cannot be increased beyond 80 mass%. Specifically, the "polymerizable monomer blending ratio Rr," defined as the proportion (mass%) of the mass of B to the total mass of the monomer components in the raw material composition {total mass of a1, a2, and B}, must be 20 to 80 mass% ("100-Rr," which represents the proportion of the polyurethane component, is 80 to 20 mass%).

[0008] For this reason, it was unclear what properties a crosslinked polyurethane composite material would have in a region where the polyurethane component content exceeds 80% by mass, or whether it would have the same characteristics as the polyurethane composite material described in Patent Document 1, such as uniformity throughout and excellent strength and water resistance. By increasing the polyurethane component content in a crosslinked polyurethane composite material, not only can increased strength (derived from the polyurethane structure) be expected, but if it becomes possible to produce a crosslinked polyurethane composite material with a polyurethane component content exceeding 80% by mass and the existence of a region where uniformity and water resistance are well maintained is confirmed, a new crosslinked polyurethane composite material with properties similar to those of the polyurethane composite material described in Patent Document 1 will become available.

[0009] Therefore, an object of the present invention is to provide a method for producing a crosslinked polyurethane composite material having a polyurethane component content of more than 80% by mass, and further to provide a crosslinked polyurethane composite material having a polyurethane component content of more than 80% by mass, which is uniform and has excellent strength and water resistance. [Means for solving the problem]

[0010] The present invention solves the above problems, Po A polyurethane composite material in which a filler is dispersed in a matrix made of a polyurethane resin, The polyurethane resin has a number average molecular weight of 1500 to 5000 and has a crosslinked structure formed by radical polymerization of a polyurethane component having a radical polymerizable group (hereinafter also referred to as a "radical polymerizable polyurethane component") with a radical polymerizable monomer; The proportion of the polyurethane component in the polyurethane-based resin is more than 80% by mass and 95% by mass or less. The polyurethane composite material (hereinafter also referred to as "the polyurethane composite material of the present invention") The present invention relates to a method for producing a molded body comprising the above-mentioned do.

[0011] That is, The present invention shape The attitude is 1 a diol compound (a1) having one or more radically polymerizable groups; a polymerizable monomer (B) having one or more radically polymerizable groups in the molecule and not undergoing a polyaddition reaction with either the diol compound (a1) or a diisocyanate compound; and a 10-hour half-life temperature: T 10 a first raw material composition preparation step of preparing a first raw material composition containing a thermal radical polymerization initiator (C) having a temperature of 60°C or higher; and a filler (D); a second raw material composition preparation step of mixing the first raw material composition with a diisocyanate compound (a2) to cause a polyaddition reaction between the diol compound (a1) and the diisocyanate compound (a2) to form a polyurethane component (A) having a number average molecular weight of 1500 to 5000 and having a radically polymerizable group, thereby preparing a second raw material composition comprising the polyurethane component (A), the polymerizable monomer (B); a thermal radical polymerization initiator (C); and a filler (D), and which may contain unreacted diol compound (a1) and / or unreacted diisocyanate compound (a2); The temperature of the second raw material composition is 40° C. or higher and the T 10 The mixture is filled into a mold while being kept at a temperature 15°C lower than the temperature of the thermal radical polymerization initiator (C). 10 Temperature 10°C lower than T 10By heating to a temperature 25°C higher than the The filler (D) is dispersed in a matrix made of a polyurethane resin having a crosslinked structure formed by radical polymerization of the radically polymerizable group of the polyurethane component (A) and the polymerizable monomer (B). Polyurethane composite materials of a molding step of obtaining a molded body, When the contents (parts by mass) of the respective components contained in the second raw material composition are respectively defined as the content of the polyurethane component (A): Ar, the content of the polymerizable monomer (B): Br, the content of the diol compound (a1): a1r, and the content of the diisocyanate compound (a2): a2r, Formula: Rr=100×Br / [a1r+a2r+Ar+Br] The polymerizable monomer blending ratio Rr defined by is 5% by mass or more and less than 20% by mass. By doing so, the proportion of the polyurethane component in the polyurethane-based resin is made to be more than 80 mass % and 95 mass % or less. , The present invention relates to a method for producing a polyurethane composite material molded article. In this method, the molding step is carried out with the blending ratio of the polymerizable monomer in the second raw material composition within the above range, and therefore the polyurethane composite material constituting the obtained molded body is the polyurethane composite material of the present invention.

[0012] In the manufacturing method of the above embodiment (hereinafter also referred to as "the manufacturing method of the present invention"), the content of the filler (D) in the second raw material composition is preferably 60% by mass to 80% by mass.

[0013] The non-polyaddition radically polymerizable monomer (B) preferably contains a polymerizable monomer represented by the following structural formula (1).

[0014] [ka]

[0015] [In the above structural formula (1), R 11 and R 12 is a hydrogen atom or a methyl group, and n1 is an integer of 1 to 10. Furthermore, the radically polymerizable diol compound (a1) is preferably a diol compound in which the number of atoms constituting the main chain in the divalent organic residue intervening between two hydroxyl groups contained in the diol compound is 2 to 8. [Effects of the Invention]

[0017] According to the present invention, there is provided a polyurethane composite material that can be suitably used as a material for dental cutting, which is excellent in strength, water resistance, and uniformity, similar to the polyurethane composite material described in Patent Document 1. Furthermore, according to the production method of the present invention, a molded article of the polyurethane composite material of the present invention having the above-mentioned characteristics can be efficiently produced. DETAILED DESCRIPTION OF THE INVENTION

[0018] As mentioned above, in the polyurethane composite material described in Patent Document 1, the proportion of the polyurethane component in the resin component cannot exceed 80% by mass in order to maintain good homogeneity, but Patent Document 1 does not specifically disclose the reason for this. Therefore, in order to solve the above problem, the present inventors first investigated the reason. As a result, they discovered that crosslinked polyurethane composite materials are typically produced by radically polymerizing and curing a raw material composition (corresponding to the second raw material composition in the production method of the present invention) containing the radical-polymerizable polyurethane component (A), the polymerizable monomer (non-polyaddition-reactive radically polymerizable monomer) (B), a radical polymerization initiator (C), and a filler (D) to obtain a molded product of a desired shape, which is then processed as needed for use. However, when the proportion exceeds 80% by mass, the raw material composition becomes very hard and has almost no fluidity, and in some cases, the non-polyaddition-reactive monomer may be unevenly distributed (rather than uniformly distributed) in the composition.

[0019] Based on the above findings, the inventors of the present invention believed that if the fluidity of the (second) raw material composition could be increased to homogenize the components, a molded article of the homogenous raw material composition could be obtained even when the above ratio exceeds 80% by mass, and its physical properties could be evaluated. As a result of further investigation, they found that (1) a molded article of a homogenous crosslinked polyurethane composite material can be obtained by heating the (second) raw material composition to a temperature at which radical polymerization does not substantially occur, and (2) high water resistance can be maintained if the above ratio is 95% by mass or less, and thus completed the present invention.

[0020] With regard to the above (1), it is not entirely clear why a molded article of a uniform crosslinked polyurethane composite material can be obtained by heating the (second) raw material composition to a relatively low temperature, and the present invention is not bound by any logic. However, the inventors of the present invention presume that, since many of the radical polymerizable polyurethane components (A) obtained by polyaddition reaction using only the radical polymerizable diol compound (a1) and the diisocyanate compound (a2) had glass transition points of about 35 to 50°C, heating the radical polymerizable polyurethane component (A) even at a relatively low temperature where radical polymerization does not substantially occur increases the fluidity, improves uniformity, and enables molding.

[0021] The polyurethane composite material of the present invention is a polyurethane composite material having a filler dispersed in a matrix made of a polyurethane resin, the polyurethane resin having a crosslinked structure formed by radical polymerization of a radically polymerizable group of a polyurethane component having a number-average molecular weight of 1500 to 5000 with a radically polymerizable monomer, and the proportion of the polyurethane component in the polyurethane resin is more than 80% by mass but not more than 95% by mass. However, the microstructure depends on the production method, and is difficult to identify by analysis, etc. Because the polyurethane composite material of the present invention is a material for constituting a molded article produced by the production method of the present invention, the production method of the present invention will be described in detail below.

[0022] In this specification, unless otherwise specified, the expression "x to y" using numerical values ​​x and y means "greater than or equal to x and less than or equal to y." In such an expression, when a unit is assigned only to the numerical value y, the unit also applies to the numerical value x. Furthermore, in this specification, the term "(meth)acrylic" means both "acrylic" and "methacrylic."

[0023] 1. Manufacturing method of the present invention The production method of the present invention is a method for producing a molded article made of the polyurethane composite material of the present invention, comprising the steps of: a first raw material composition preparation step of preparing a first raw material composition containing a radically polymerizable diol compound (a1); a non-polyaddition-type radically polymerizable monomer (B); a thermal radical polymerization initiator (C); and a filler (D); The first raw material composition is mixed with a diisocyanate compound (a2) to cause a polyaddition reaction between the radical polymerizable diol compound (a1) and the diisocyanate compound (a2), thereby forming a radical polymerizable polyurethane component (A), and the radical polymerizable polyurethane component (A), the non-polyaddition-type radical polymerizable monomer (B); and a 10-hour half-life temperature: T 10 a second raw material composition preparation step of preparing a second raw material composition comprising a thermal radical polymerization initiator (C) having a temperature of 60°C or higher; and a filler (D), the second raw material composition optionally containing unreacted radical polymerizable diol compound (a1) and / or unreacted diisocyanate compound (a2); The temperature of the second raw material composition is 40° C. or higher and the T 10 The mixture is filled into a mold while being kept at a temperature 15°C lower than the temperature of the thermal radical polymerization initiator (C). 10 Temperature 10°C lower than T 10 a molding step of heating the mixture to a temperature 25°C higher than the temperature at which the mixture is heated to carry out radical polymerization to obtain a polyurethane composite material molded product, When the contents (parts by mass) of the respective components contained in the second raw material composition are respectively defined as the content of the radical polymerizable polyurethane component (A): Ar, the content of the non-polyaddition polymerizable monomer (B): Br, the content of the radical polymerizable diol compound (a1): a1r, and the content of the diisocyanate compound (a2): a2r, Formula: Rr=100×Br / [a1r+a2r+Ar+Br] The polymerizable monomer blending ratio Rr defined by the following formula is set to 5% by mass or more and less than 20% by mass. Note that, because the effects of the present invention are significant, it is preferable that the Rr is set to 5 to 15% by mass.

[0024] The various raw materials and steps used in the production method of the present invention will be described in detail below.

[0025] 2. Regarding raw materials 2-1. Radical polymerizable diol compound (a1) The radically polymerizable diol compound (a1) is a compound that serves as a raw material for forming the radically polymerizable polyurethane component (A). The two hydroxyl groups of the radically polymerizable diol compound (a1) and the isocyanate groups of the diisocyanate compound (a2), which is the other polyurethane precursor component, undergo a polyaddition reaction in the second raw material composition preparation step, thereby forming the radically polymerizable polyurethane component (A).

[0026] The radically polymerizable diol compound (a1) can be any compound having at least one radically polymerizable group and two hydroxyl groups in the molecule, without any particular limitation. Here, the radically polymerizable group refers to a functional group that reacts with an initiator that generates radicals and polymerizes, specifically, a group having a radically polymerizable carbon-carbon double bond, such as a vinyl group, a (meth)acrylate group, or a styryl group.

[0027] The radical polymerizable groups in the diol compound are introduced into the main chain of the polyurethane molecule formed by the polyaddition reaction. Furthermore, during the radical polymerization process in the molding process, the radical polymerizable groups in the radical polymerizable polyurethane component (A) react with each other, or with the radical polymerizable groups in the radical polymerizable polyurethane component (A) and the non-polyaddition radical polymerizable monomer (B) react to form bonds, resulting in crosslinks. This improves the water resistance of the cured polyurethane composite material.

[0028] From the viewpoint of the strength and water resistance of the polyurethane composite material that is the product, the number of radically polymerizable groups contained in the molecule of the radically polymerizable diol compound (a1) is preferably 1 to 4, and particularly preferably 1 to 2. When the number of radically polymerizable groups is 4 or less, it becomes easier to suppress shrinkage of the cured body formed during the radical polymerization reaction.

[0029] Furthermore, the number of atoms constituting the main chain in the divalent organic residue interposed between two hydroxyl groups contained in the molecule of the radically polymerizable diol compound (a1) (hereinafter, sometimes referred to as the "OH distance") is preferably 2 to 8, more preferably 2 to 6, and particularly preferably 2 to 4. By adjusting the OH distance of the radically polymerizable diol compound (a1) to fall within the above range, it is possible to introduce radically polymerizable groups and urethane bonds at a high density into the molecules of the radically polymerizable polyurethane component (A) obtained by the polyaddition reaction, and it is possible to increase the strength of the polyurethane composite material.

[0030] When two or more radical polymerizable diol compounds (a1) are used, the OH distance refers to a value calculated as the average value of the two or more radical polymerizable diol compounds (a1). Here, when n types of radical polymerizable diol compounds (a1), where n is an integer of 2 or more, are used, the average OH distance refers to a value calculated as the sum of the products obtained by multiplying the OH distance: Dx of each radical polymerizable diol compound by the molar fraction (mol / mol): Mx of each radical polymerizable diol compound, which is defined as the number of moles of each radical polymerizable diol compound in the total number of moles of the radical polymerizable diol compounds.

[0031] Examples of compounds that can be suitably used as the radically polymerizable diol compound (a1) include trimethylolpropane mono(meth)acrylate, glycerol mono(meth)acrylate, erythritol di(meth)acrylate, pentaerythritol di(meth)acrylate, and ring-opened products of ethylene glycol diglycidyl ether with acids ((meth)acrylic acid and vinylbenzoic acid). These can be used alone or in combination of different types.

[0032] 2-2. Diisocyanate compound (a2) The diisocyanate compound (a2) is the other polyurethane precursor component for forming the radically polymerizable polyurethane component (A), and any known compound having two isocyanate groups in one molecule can be used without any particular limitation.

[0033] Examples of compounds that can be suitably used as the diisocyanate compound (a2) include 1,3-bis(2-isocyanato-2-propyl)benzene, 2,2-bis(4-isocyanatophenyl)hexafluoropropane, 1,3-bis(isocyanatomethyl)cyclohexane, 4,4'-methylenediphenyldiisocyanate, 3,3'-dichloro-4,4'-diisocyanatobiphenyl, 4,4'-diisocyanato-3,3'-dimethylbiphenyl, diisocyanato-4,4'-diisocyanato ... Examples include cyclohexylmethane 4,4'-diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, norbornane diisocyanate, isophorone diisocyanate, 1,5-diisocyanatonaphthalene, 1,3-phenylene diisocyanate, trimethylhexamethylene diisocyanate, tolylene-2,4-diisocyanate, tolylene-2,6-diisocyanate, and m-xylylene diisocyanate.

[0034] Among these, the diisocyanate compound (a2) is preferably a diisocyanate compound (a2) having a phenyl group in the molecule from the viewpoint of the fluidity of the resulting second raw material composition and the strength of the resulting polyurethane composite material.

[0035] The amounts of the radically polymerizable diol compound (a1) and the diisocyanate compound (a2) used in the second raw material composition preparation step are not particularly limited as long as the molar ratio [amount of diisocyanate compound (a2) used / amount of radically polymerizable diol compound (a1) used] is about 1 mol / mol, but generally, a molar ratio of about 0.9 to 1.2 mol / mol is preferred. Note that, from the viewpoint of quantitatively reacting the radically polymerizable diol compound (a1) and the diisocyanate compound (a2) in the second raw material composition preparation step to form the radically polymerizable polyurethane component (A) and minimizing unreacted materials, the molar ratio is preferably 1.0 to 1.1 mol / mol.

[0036] 2-3. Radical polymerizable polyurethane component (A) The radical polymerizable polyurethane component (A) is a component formed by a polyaddition reaction between a radical polymerizable diol compound (a1) and a diisocyanate compound (a2) in the second raw material composition preparation step. The structure of the radical polymerizable polyurethane component (A) is almost uniquely determined by the radical polymerizable diol compound (a1) used in the first raw material composition preparation step and the diisocyanate compound (a2) used in the second raw material composition preparation step.

[0037] The radically polymerizable polyurethane component (A) also constitutes the polyurethane resin matrix in the final polyurethane composite material by radical polymerization with the non-polyaddition-type radically polymerizable monomer (B) under the catalytic action of the thermal radical polymerization initiator (C). Therefore, the remaining components of the second raw material composition, excluding the filler (D), i.e., the components primarily comprising the radically polymerizable polyurethane component (A), the non-polyaddition-type radically polymerizable monomer (B), and the thermal radical polymerization initiator (C), can be referred to as the matrix raw material composition. If the second raw material composition further contains a fifth component in addition to components A through D, and the fifth component dissolves in the radically polymerizable polyurethane component (A) and / or the non-polyaddition-type radically polymerizable monomer (B), the fifth component also constitutes the matrix raw material composition.

[0038] The radically polymerizable polyurethane component (A) contained in the second raw material composition must have a number-average molecular weight of 1500 to 5000. A number-average molecular weight of 1500 or more allows for the production of a polyurethane-based composite material with sufficient strength. Furthermore, according to the inventors' studies, it is virtually impossible or extremely difficult to obtain a radically polymerizable polyurethane component (A) with a number-average molecular weight exceeding 5000 in a coexistence system of the five components. Furthermore, within the range of 1500 to 5000, a smaller number-average molecular weight more reliably suppresses the precipitation of the radically polymerizable polyurethane component (A) in the matrix raw material composition, facilitating uniform radical polymerization. From the viewpoint of achieving a good balance between the fluidity of the second raw material composition and the strength of the polyurethane-based composite material, the number-average molecular weight is preferably 1500 to 3500, more preferably 2000 to 3000.

[0039] The number-average molecular weight of the radically polymerizable polyurethane component (A) refers to the polystyrene-equivalent number-average molecular weight determined by GPC (gel permeation chromatography) measurement. The number-average molecular weight of the radically polymerizable polyurethane component (A) in the second raw material composition can be determined by adding a solvent such as THF (tetrahydrofuran) to the second raw material composition as needed, removing insoluble components such as the filler (D) by filtration, centrifugation, or the like, and then performing GPC measurement on the resulting solution (i.e., the matrix raw material composition or a solution consisting of a mixture of the matrix raw material composition and an optional solvent). Measurement can be performed using Advanced Polymer Chromatography (manufactured by Nihon Waters) under the following measurement conditions.

[0040] [Measurement conditions] Column: ACQUITY APCTMXT45 1.7μm ACQUITY APCTMXT125 2.5μm Column temperature: 40℃ Developing solvent: THF ·Flow rate: 0.5ml / min Detector: Photodiode array detector 254nm (PDA detector)

[0041] 2-4. Non-polyaddition radical polymerizable monomer (B) The non-polyaddition radically polymerizable monomer (B) is a compound that has at least one radically polymerizable group in its molecule and does not undergo polyaddition reactions with either the radically polymerizable diol compound (a1) or the diisocyanate compound (a2). Here, "does not undergo polyaddition reactions with either the radically polymerizable diol compound (a1) or the diisocyanate compound (a2)" means that the monomer does not contain both a group that undergoes polyaddition reactions with the radically polymerizable diol compound (a1) and a group that undergoes polyaddition reactions with the diisocyanate compound (a2). Specifically, this means that the monomer does not contain hydroxyl groups, amino groups, carboxy groups, isocyanate groups, or mercapto groups. Among these functional groups, the group that can undergo polyaddition reactions with the radically polymerizable diol compound (a1) is an isocyanate group, and the group that can undergo polyaddition reactions with the diisocyanate compound (a2) is a hydroxyl group, amino group, carboxyl group, or mercapto group. Therefore, the non-polyaddition radically polymerizable monomer (B) does not contain a hydroxyl group, an amino group, a carboxy group, an isocyanate group, or a mercapto group in the molecule. Furthermore, the radically polymerizable group may be the same as the radically polymerizable group contained in the radically polymerizable diol compound (a1). Suitable radically polymerizable groups are preferably (meth)acrylate groups and / or (meth)acrylamide groups, or groups having the same molecular structure as the radically polymerizable group contained in the radically polymerizable diol compound (a1). From the viewpoint of ease of crosslink formation, the number of radically polymerizable groups contained in the molecule of the non-polyaddition radically polymerizable monomer (B) is preferably 2 to 6, more preferably 2 to 4. By having two or more radically polymerizable groups, the crosslink density can be increased, making it easier to obtain a cured product with sufficient strength. Furthermore, by having six or fewer radically polymerizable groups, it is easier to suppress shrinkage during curing. Furthermore, the non-polyaddition radically polymerizable monomer (B) is preferably liquid at room temperature (i.e., 25°C).

[0042] Furthermore, it is preferable that the non-polyaddition radically polymerizable monomer (B) does not contain a functional group that strongly interacts (especially hydrogen bonds) with the radically polymerizable polyurethane component (A). Examples of functional groups that strongly interact with the polyurethane component (A) include amide groups, urethane groups, and urea groups. If such functional groups are contained, it may be difficult to obtain sufficient fluidity and uniformity unless the molding process is performed at a higher temperature.

[0043] The viscosity of the non-polyaddition radical polymerizable monomer (B) is not particularly limited, but is preferably in the range of 1 mPa·s to 1000 mPa·s at room temperature, and more preferably in the range of 1 mPa·s to 100 mPa·s. By using a non-polyaddition radical polymerizable monomer in this range, the effect of heating in the molding step is increased.

[0044] From the viewpoint of facilitating dispersion of the radically polymerizable polyurethane component (A), the non-polyaddition radically polymerizable monomer (B) preferably contains a polymerizable monomer represented by the following structural formula (1).

[0045] [ka]

[0046] In addition, in structural formula (1), R 11 and R 12 represents a hydrogen atom or a methyl group, and n1 represents an integer of 1 to 10, preferably an integer of 1 to 3.

[0047] Examples of compounds that can be suitably used as the non-polyaddition radically polymerizable monomer (B) include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tricyclodecanol (meth)acrylate, trimethylolpropane (meth)acrylate, pentaerythritol (meth)acrylate, ditrimethylolpropane (meth)acrylate, dipentaerythritol (meth)acrylate, etc. Among these, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, and triethylene glycol di(meth)acrylate are particularly preferred.

[0048] The content of the non-polyaddition type radical polymerizable monomer (B) in the second raw material composition is expressed as follows, when the contents (parts by mass) of the respective components contained in the second raw material composition are defined as Ar, Br, a1r, a2r, and a2r, respectively: Formula: Rr=100×Br / [a1r+a2r+Ar+Br] The polymerizable monomer blending ratio Rr defined as: is an amount that is 5% by mass or more and less than 20% by mass. If it is less than 5% by mass, it becomes very difficult to obtain a polyurethane composite material in which a uniform crosslinked structure has been introduced.

[0049] 2-5. Thermal radical polymerization initiator (C) The thermal radical polymerization initiator (C) has the function of initiating a radical polymerization reaction in the molding step, and by reacting and bonding radically polymerizable groups together, polymerizes and hardens the second raw material composition and forms crosslinking points. In the manufacturing method of the present invention, the second raw material composition filled in the mold (forming tool) is heated and polymerized, so the thermal radical polymerization initiator (C) is used as the radical polymerization initiator. Furthermore, in order to prevent radical polymerization from occurring in the second raw material composition heated to a predetermined temperature before and during filling into the mold, the thermal polymerization initiator has a 10-hour half-life temperature: T 10 Use a product with a temperature of 60°C or higher. 10 The upper limit of the temperature is not particularly limited, but is usually 150°C. 10 It is preferable to use a solvent having a temperature in the range of 70 to 120°C, particularly 80 to 100°C. Here, the 10-hour half-life temperature: T 10 The thermal polymerization initiator concentration is the temperature at which the amount of the thermal polymerization initiator decreases to half of the initial amount after 10 hours from the initial time point, and is used as an index of the reactivity of the thermal polymerization initiator. Specific examples of suitable thermal radical polymerization initiators include peroxide initiators such as benzoyl peroxide and tert-butyl peroxylaurate, and azo-based initiators such as azobisbutyronitrile. These thermal polymerization initiators may be used alone or in combination of two or more.

[0050] The amount of radical polymerization initiator (C) used may be determined appropriately depending on the type of initiator, but is generally preferably in the range of 0.005% by mass to 2.0% by mass, and more preferably in the range of 0.01% by mass to 1.0% by mass, based on the mass of the matrix raw material composition. The filler (D) disperses in the polyurethane resin matrix and forms a composite with the polyurethane resin matrix, thereby improving the physical properties of the polyurethane resin composite material, such as mechanical strength, abrasion resistance, and water resistance.

[0051] As the filler (D), inorganic fillers such as silica, alumina, titania, zirconia, or composite oxides thereof, glass, etc. are preferably used. Specific examples of such inorganic fillers include spherical or irregularly shaped particles such as amorphous silica, silica-zirconia, silica-titania, silica-titania-zirconia, quartz, and alumina. When the polyurethane composite material molded article produced by the production method of the present invention is used as a dental material, silica, titania, zirconia, or composite oxides thereof is preferably used as the filler (D), with silica or composite oxides thereof being particularly preferred. These inorganic fillers are unlikely to dissolve in the oral environment, and the refractive index difference with the polyurethane resin matrix can be easily adjusted, making it easy to control transparency and aesthetics.

[0052] The shape of the filler (D) is not particularly limited and can be selected appropriately depending on the intended use of the polyurethane composite material. However, a spherical shape is preferable, for example, from the viewpoint of obtaining a polyurethane composite material that is particularly excellent in abrasion resistance, surface smoothness, and gloss retention. Polyurethane composite materials containing dispersed spherical fillers (D) are also particularly suitable for dental applications. Here, "spherical" means that the average uniformity index determined by image analysis of images taken with a scanning or transmission electron microscope is 0.6 or greater. The average uniformity index is more preferably 0.7 or greater, and even more preferably 0.8 or greater. The average uniformity index can be calculated by measuring the longest diameter (L) and the shortest diameter (B) perpendicular to the longest diameter (L) for each of n particles (usually 40 or more, preferably 100 or more) in image analysis of images taken with a scanning or transmission electron microscope, determining the ratio (B / L), and then dividing the sum (ΣB / L) by n.

[0053] The average particle size of the filler (D) is preferably 0.001 μm to 100 μm, more preferably 0.01 μm to 10 μm, from the viewpoints of abrasion resistance, surface smoothness, and gloss durability. Furthermore, it is preferable to use fillers (D) having multiple particle sizes, since this facilitates increasing the content of the filler (D) in the polyurethane composite material. Specifically, it is preferable to combine particle sizes of 0.001 μm to 0.1 μm with particle sizes of 0.1 μm to 100 μm, and more preferably to combine particle sizes of 0.01 μm to 0.1 μm with particle sizes of 0.1 μm to 10 μm.

[0054] It is preferable to use a filler (D) that has been surface-treated to improve compatibility with the polyurethane resin matrix and the mechanical strength and water resistance of the polyurethane composite material. Silane coupling agents are generally used as surface treatment agents, and surface treatment with silane coupling agents is particularly effective for silica-based inorganic particle fillers (D). Suitable silane coupling agents include methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

[0055] The amount of filler (D) used may be determined appropriately depending on the physical properties such as the strength of the target polyurethane composite material, but from the viewpoint of increasing the strength of the polyurethane composite material, the amount is preferably 60% by mass to 80% by mass, more preferably 65% ​​by mass to 75% by mass, expressed in mass % based on the mass of the second raw material composition (hereinafter sometimes simply referred to as "filling rate"). Furthermore, when the polyurethane composite material produced by the production method for a polyurethane composite material of this embodiment is used as a dental cutting material, the filling rate is more preferably 65% ​​by mass to 75% by mass.

[0056] 2-7. Other additives In addition to the essential components described above, the first raw material composition or the second raw material composition may contain various other additives, such as polymerization inhibitors, fluorescent agents, ultraviolet absorbers, antioxidants, pigments, antibacterial agents, and X-ray contrast agents, and the amounts of these additives may be determined appropriately depending on the desired purpose.

[0057] 3.About each process The manufacturing method of the present invention includes a first raw material composition preparation step, a second raw material composition preparation step, and a molding step. Each step will be described in detail below.

[0058] 3-1. First raw material composition preparation step and second raw material composition preparation step In the first raw material composition preparation step, a first raw material composition is prepared containing a radically polymerizable diol compound (a1); a non-polyaddition type radically polymerizable monomer (B); a thermal radical polymerization initiator (C); and a filler (D). In the second raw material composition preparation step, the first raw material composition is mixed with a diisocyanate compound (a2) to cause a polyaddition reaction between the radically polymerizable diol compound (a1) and the diisocyanate compound (a2), thereby forming a radically polymerizable polyurethane component (A). The radically polymerizable polyurethane component (A), the non-polyaddition type radically polymerizable monomer (B); and a 10-hour half-life temperature: T 10 A second raw material composition is prepared, which comprises a thermal radical polymerization initiator (C) having a temperature of 60°C or higher; and a filler (D), and which may also contain unreacted radically polymerizable diol compound (a1) and / or unreacted diisocyanate compound (a2).

[0059] The amounts of each component used in these steps are determined as follows: The composition of the first raw material composition is determined based on the composition of the second raw material composition to be obtained. Specifically, assuming that equimolar amounts of radically polymerizable diol compound (a1) and diisocyanate compound (a2) undergo a quantitative polyaddition reaction to produce radically polymerizable polyurethane component (A), the amounts of radically polymerizable diol compound (a1) and diisocyanate compound (a2) used in the second raw material composition preparation step are adjusted so that the molar ratio [amount of diisocyanate compound (a2) used / amount of radically polymerizable diol compound (a1) used] is approximately 1 mol / mole, generally about 0.9 to 1.2 mol / mole, and preferably 1.0 to 1.1 mol / mole, and further so that the polymerizable monomer blending ratio: Rr is a predetermined value (% by mass) in the range of 5% by mass or more but less than 20% by mass. This determines the amounts of (a1) and (B) in the first raw material composition and the amount of (a2) used in the second raw material composition preparation step, and the amounts of (A), (B), remaining (a1), and remaining (a2) in the second raw material composition are automatically determined by these blending amounts. The amounts of (C) and (D) to be blended may be set to the preferred amounts based on the above-mentioned standards.

[0060] The first raw material composition may be prepared by mixing all of the components constituting the first raw material composition at once, or by preparing a mixture by mixing some of the components constituting the first raw material composition and then adding and mixing the remaining components constituting the first raw material composition. The mixing method for mixing the components in the preparation of the first raw material composition is not particularly limited, and methods using a magnetic stirrer, a mortar and pestle mixer, a planetary mixer, a centrifugal mixer, or the like may be appropriately used. Furthermore, because it is easier to uniformly disperse the filler (D), it is preferable to first mix the radically polymerizable diol compound (a1) and the non-polyaddition-type radically polymerizable monomer (B) to prepare a mixed composition, and then add the filler (D) to this mixed composition and mix it to prepare the first raw material composition. Furthermore, because it is easier to suppress side reactions and facilitate dispersion, it is preferable to add the radical polymerization initiator (C) to the first raw material composition. Similarly, it is preferable to add other additives to the first raw material composition. The first raw material composition prepared in this manner is preferably subjected to a degassing treatment to remove any air bubbles contained therein. As the defoaming method, a known method can be used, and any method such as pressure defoaming, vacuum defoaming, centrifugal defoaming, etc. can be used.

[0061] The first raw material composition may further contain, as other additives, a catalyst that promotes the polyaddition reaction, if necessary, but it is not necessary to contain a catalyst that promotes the polyaddition reaction. Examples of catalysts that promote the polyaddition reaction include tin octoate and dibutyltin diacetate.

[0062] In the second raw material composition preparation step, the radically polymerizable polyurethane component (A) is formed by polyaddition reaction of the radically polymerizable diol compound (a1) and the diisocyanate compound (a2) contained in the first raw material composition. The polyaddition reaction is initiated by mixing the first raw material composition with the diisocyanate compound (a2) simultaneously, or by heating the mixture as needed after mixing the first raw material composition with the diisocyanate compound (a2). The polyaddition reaction is carried out until at least one of the radically polymerizable diol compound (a1) and the diisocyanate compound (a2) is substantially consumed by the polyaddition reaction; in other words, until the progress of the polyaddition reaction approaches its maximum value (saturation value). At this time, the first raw material composition has a 10-hour half-life temperature: T 10 Since the thermal radical polymerization initiator (C) has a temperature of 60°C or higher, the T 10 The polyaddition reaction must be carried out at a temperature lower than T 10 It is preferable to carry out the polyaddition reaction at a temperature maintained at 80° C. to 20° C. lower than the temperature at which the polymerization reaction is carried out, particularly at a temperature maintained at 70° C. to 30° C. lower than the temperature at which the polymerization reaction is carried out. In the production method of the present invention, even if the above-mentioned method is adopted, a small amount of radical polymerization reaction is allowed to inevitably occur.

[0063] The reaction time varies depending on the reaction temperature, for example, (1) if the reaction temperature is 30°C or higher but lower than 50°C, it is preferably 60 hours or longer, more preferably 72 hours or longer, (2) if the heating temperature is 50°C or higher but lower than 80°C, it is preferably 24 hours or longer, more preferably 36 hours or longer, and (3) if the heating temperature is 80°C or higher, it is preferably 15 hours or longer, more preferably 24 hours or longer. In the cases shown in (1) to (3) above, the upper limit of the heating time is not particularly limited, but from the practical viewpoint of productivity and the like, 120 hours or shorter is preferred.

[0064] When preparing the second raw material composition, the mixing means used to mix the components is not particularly limited, and any known mixing means can be used as appropriate. Examples of such mixing means include a magnetic stirrer, a mortar and pestle mixer, a planetary mixer, and a centrifugal mixer. Furthermore, to prevent air bubbles from being mixed into the composition during mixing, the components may be mixed under pressure and / or under vacuum.

[0065] 3-2. Molding process In the molding step, the temperature of the second raw material composition is 40° C. or higher and the 10-hour half-life temperature of the thermal radical polymerization initiator (C): T 10 The mixture is filled into a mold while being kept at a temperature 15°C lower than the temperature of the thermal radical polymerization initiator (C). 10 Temperature 10°C lower than T 10 The mixture is heated to a temperature 25°C higher than the above temperature to carry out radical polymerization, thereby obtaining a polyurethane composite material molded article.

[0066] Of the four essential components that make up the second raw material composition, the primary components in terms of content are the radically polymerizable polyurethane component (A), the non-polyaddition radically polymerizable monomer (B), and the filler (D). The non-polyaddition radically polymerizable monomer (B) is a low-molecular-weight substance that is liquid at room temperature. On the other hand, although the radically polymerizable polyurethane component (A) is a polymer, its number-average molecular weight is relatively small, ranging from 1,500 to 5,000 (i.e., its molecular size is quite small). Therefore, when the non-polyaddition radically polymerizable monomer (B) is present in the second raw material composition in an amount such that the polymerizable monomer blending ratio (Rr) is 20% by mass or greater, some of the non-polyaddition radically polymerizable monomer (B) dissolves or swells, resulting in a homogeneous, fluid paste-like second raw material composition at room temperature. However, when Rr is less than 20% by mass, particularly 15% by mass or less, the second raw material composition loses fluidity and assumes a solid-like state, and in some cases, the non-polyaddition-type radically polymerizable monomer (B), which is a liquid component, separates and becomes unevenly distributed, resulting in a decrease in uniformity.

[0067] In the production method of the present invention, before radical polymerization, the second raw material composition is heated to a predetermined temperature, specifically, 40° C. or higher and the 10-hour half-life temperature of the thermal radical polymerization initiator (C): T 10 By heating the mixture to a temperature 15°C lower than the temperature at which the mixture is heated, the mixture is converted into a uniform, fluid paste, which is then molded into a desired shape. Radical polymerization is then carried out while maintaining the uniformity, making it possible to efficiently obtain molded articles made of a uniform crosslinked polyurethane composite material.

[0068] From the viewpoint of being able to change it into a more uniform paste state, it is preferable to use a thermal radical polymerization initiator (C) with a 10-hour half-life temperature: T 10 The temperature at which the second raw material composition is maintained (heated) before filling into the mold is set to 45°C to 120°C, particularly 80°C to 100°C. 10 Temperatures 15°C lower than 50°C, especially 10 A temperature 20°C lower than this is preferred.

[0069] As a method for maintaining the second raw material composition at a temperature (heating temperature) before mold filling, methods such as placing the container holding the second raw material composition in an atmosphere maintained at a predetermined temperature or contacting it with a heat transfer medium (a liquid, a solid such as a plate) maintained at a predetermined temperature are suitable to avoid localized high temperatures. The time required to maintain the predetermined temperature is sufficient as long as it does not adversely affect mold filling (due to radical polymerization during the maintenance period), and is typically 5 minutes to several hours, preferably 10 to 60 minutes, after the predetermined temperature is reached. By maintaining the second raw material composition at the aforementioned temperature, the second raw material composition becomes homogeneous without any special stirring or other operations, but stirring may be performed as long as no air bubbles or the like remain inside.

[0070] The mold (forming tool) used in the molding process can be any mold having a cavity corresponding to the shape of the desired molded product. There are no particular restrictions on the material, as long as it can withstand the temperature and pressure during radical polymerization, and metal, ceramic, or resin materials can be used. Specifically, materials made of SUS, polypropylene, polyacetal, polytetrafluoroethylene, etc. are preferably used.

[0071] The filling of the second raw material composition into the mold is not particularly limited, as long as it is carried out in a heated state within the above-mentioned temperature range, and known methods can be used. This can be suitably carried out by pressure casting or vacuum casting. Pressure casting is particularly preferred, as it ensures reliable heat transfer to the second raw material composition. There are no limitations on the pressurization method, and mechanical pressurization or air pressurization can be used.

[0072] The second raw material composition filled in the mold is heated to a temperature of 10 hours half-life of the thermal radical polymerization initiator (C): T 10 Temperature 10°C lower than T 10 The heating temperature is preferably controlled so as not to exceed 150°C. 10 By setting the heating temperature to a temperature 10°C lower than the upper limit temperature (T 10By setting the heating temperature to a temperature not higher than 25°C above the temperature above, rapid radical polymerization can be suppressed. Controlling the heating temperature within the above-mentioned temperature range allows polymerization and curing to proceed at an industrially acceptable reaction rate, suppresses the occurrence of distortion and cracks in the cured product due to rapid reaction progress, and also makes it extremely easy to suppress deterioration of the non-polyaddition radically polymerizable monomer (B). Furthermore, when radical polymerization is performed by heating, the second raw material composition may be pressurized during radical polymerization to suppress the formation of voids due to bubbles in the cured product. There are no limitations on the pressurization method, and mechanical pressurization or pressurization with a gas such as nitrogen may be used.

[0073] By carrying out the radical polymerization step in this manner, a molded article made of a polyurethane composite material in which the filler (D) is dispersed in a polyurethane resin matrix can be obtained.

[0074] 4. Application example of the manufacturing method of the present invention (manufacturing of materials for dental cutting) The polyurethane composite material of the present invention maintains high strength and is water-resistant even in a hydrophilic environment such as the oral cavity. Because of this high water resistance, the manufacturing method of the present invention is particularly suitable for use in manufacturing a material for dental cutting, particularly when a dental prosthesis is produced by cutting the material for dental cutting using a dental CAD / CAM system. Below, we will explain a specific example of the manufacturing method of the present invention, which is suitable for use in manufacturing a material for dental cutting.

[0075] First, a second raw material composition is prepared in the same manner as in the manufacturing method of the present invention. Next, the second raw material composition is heated to 40°C to 10 After heating to -15℃, the mixture is poured into a mold. 10 Temperature 10°C lower than T 10The mold is heated to a temperature 25°C higher than the initial temperature to carry out radical polymerization (molding process). There are no particular limitations on the mold used for molding, and a rectangular pillar, cylinder, square plate, or disk shape may be used as appropriate depending on the shape envisioned for each product form. The dimensions of the mold may be such that they approximately match the dimensions of the cured body after radical polymerization, taking into account factors such as the shrinkage rate during radical polymerization. Alternatively, if the cured body obtained by radical polymerization is to be processed in a subsequent process, the dimensions may be larger than the dimensions of the resulting cured body, taking into account processing allowances.

[0076] The method of injecting the second raw material composition into the mold is not particularly limited, as long as it is heated to a temperature within the above-mentioned temperature range, and any known method can be used. However, it is preferable to use pressure casting or vacuum casting. By using such an injection method, it is possible to prevent the incorporation of air bubbles and the formation of voids in the resulting cured product (polyurethane composite material), resulting in a dental cutting material with excellent strength and aesthetics. In the case of pressure casting, there is no limitation on the pressurizing method, and mechanical pressure or pressure using a gas such as nitrogen can be used.

[0077] After the hardened body is removed from the mold, it is subjected to post-treatments and processing such as heat treatment to relieve residual stress, shape correction by cutting, polishing, etc. After these post-treatments and processings, the hardened body is then attached with fixing devices such as pins to hold it in the CAD / CAM device, to obtain a dental cutting material. [Example]

[0078] EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0079] 1. Raw materials The components used in each of the examples and comparative examples and their abbreviations are shown below.

[0080] (1) Radical polymerizable diol compound (a1) GLM: glycerol monomethacrylate (OH distance: 2) EGDGMA: Ethylene glycol diglycidyl methacrylate (OH distance: 8) (2) Diisocyanate compound (a2) XDI: m-xylylene diisocyanate (3) Non-polyaddition radical polymerizable monomer (B) TEGDMA: Triethylene glycol dimethacrylate UDMA: A mixture of 1,6-bis(methacrylethyloxycarbonylamino)-2,2,4-trimethylhexane and 1,6-bis(methacrylethyloxycarbonylamino)-2,4,4-trimethylhexane (4) Radical polymerization initiator (C) PBL: t-butyl peroxylaurate (10-hour half-life temperature 98°C) PBC: t-butylcumyl peroxide (10-hour half-life temperature 120°C) (5) Filler (D) F1: Silica-zirconia (average particle size: 0.4 μm, surface treated with 3-(trimethoxysilyl)propyl methacrylate) F2: Silica-titania (average particle size: 0.08 μm, surface treated with 3-(trimethoxysilyl)propyl methacrylate) 2. Manufacturing method for polyurethane composite materials Examples of the method for producing a polyurethane composite material of the present invention will be described below together with comparative examples.

[0081] Example 1 (1) First raw material composition preparation step First, a mixed composition was prepared by mixing GLM (12.5 parts by mass) as the radical polymerizable diol compound (a1), TEGDMA (2.7 parts by mass) as the non-polyaddition radical polymerizable monomer (B), and PBL (0.1 parts by mass) as the radical polymerization initiator (C). Next, F1 (49.0 parts by mass) and F2 (20.9 parts by mass) as the filler (D) were added to this mixed composition and kneaded to prepare a first raw material composition.

[0082] (2) Second raw material composition preparation process A polyaddition-reactive raw material composition was prepared by adding XDI (14.7 parts by mass), a diisocyanate compound (a2), to a planetary centrifugal mixer containing the entire first raw material composition obtained and kneading the mixture. The polyaddition-reactive raw material composition obtained was then left to stand in an incubator at 37°C for 72 hours to carry out a polyaddition reaction, forming a radically polymerizable polyurethane component (A) and preparing a second raw material composition.

[0083] In this example, the molar ratio of the diisocyanate compound (a2) to the radically polymerizable diol compound (a1) (hereinafter sometimes referred to as the "a2 / a1 molar ratio") is 1.0. The polymerizable monomer blending ratio Rr is 9 mass%. The mass ratio (filling rate) of the filler (D) to the mass of the second raw material composition is 70 mass%. All compositions were prepared at room temperature (25°C) except for the case where the composition was heated to 37°C during the polyaddition reaction.

[0084] (3) Evaluation of the second raw material composition (3-1) Measurement of Number Average Molecular Weight of Radical Polymerizable Polyurethane Component (A) (GPC Measurement) 1 g of the resulting second raw material composition was weighed into a screw cap tube, 3.5 ml of THF was added, and the resulting THF solution was centrifuged at 10,000 rpm for 10 minutes in a centrifuge (manufactured by AS ONE Corporation). The supernatant obtained by centrifugation was then filtered through a membrane filter (pore size 20 μm, manufactured by ADVANTEC Corporation) to obtain a filtrate. This filtrate was then subjected to GPC measurement under the GPC measurement conditions shown below to determine the polystyrene-equivalent number average molecular weight of the radically polymerizable polyurethane component (A) obtained by the polyaddition reaction. The resulting number average molecular weight was 2,500.

[0085] [GPC measurement conditions] Measurement equipment: Advanced Polymer Chromatography (manufactured by Japan Waters) Column: ACQUITY APCTMXT45 1.7μm ACQUITY APCTMXT125 2.5μm Column temperature: 40℃ ·Developing solvent: THF (flow rate: 0.5ml / min) Detector: Photodiode array detector 254nm (PDA detector)

[0086] (3-2) Liquidity Assessment The fluidity of the second raw material composition at room temperature (23°C) and at 45°C, the holding temperature (heating temperature) during mold filling, was evaluated by measuring the maximum load when a 5 mm diameter stainless steel (SUS) rod was pressed to a predetermined depth at a predetermined speed, using the following procedure. First, the second raw material composition was loaded into a SUS nut-shaped mold, the surface was smoothed, and the mold was left at the measurement temperature (23°C or the holding temperature) for 5 minutes. Next, the SUS nut-shaped mold filled with the second raw material composition and a 5 mm SUS rod as a pressure-sensitive shaft were attached to a Sun Rheometer CR-150 (manufactured by Sun Scientific Co., Ltd.). The pressure-sensitive shaft was then compressed into the second raw material composition at a speed of 120 mm / min to a depth of 2 mm at 23°C and the holding temperature. The maximum load [kg] at this time was measured. The maximum load at 23°C exceeded the upper limit of measurement, 10.0 [kg], and the maximum load at 45°C was 9.4 [kg].

[0087] If the maximum load measured above exceeds 10 kg, the fluidity is significantly low, making it impossible to fill the second raw material composition into the mold (frame) without leaving any gaps.

[0088] (3-3) Evaluation of the glass transition temperature of polyurethane component (A) For reference, the glass transition temperature of a polyurethane component obtained by polyaddition reaction of a radical polymerizable diol compound (a1) and a diisocyanate compound (a2) in the same quantitative ratio as in Example 1 was evaluated as follows.

[0089] That is, using a DSC8230 (manufactured by Rigaku), the temperature was raised from 20°C to 100°C at a heating rate of 10°C / min under a nitrogen atmosphere, then lowered, and from the point where it reached 20°C, the temperature was raised again to 100°C at a heating rate of 10°C / min. A DSC curve was obtained for the polyurethane component obtained through this process, and the glass transition temperature was determined as 43°C, as the temperature at which a straight line extending the low-temperature baseline in the curve obtained when the temperature was raised again intersects with a tangent to the stepwise change in the curve.

[0090] (4) Molding process The obtained second raw material composition was left to stand for 5 minutes on a heating press (manufactured by Imoto Machinery Co., Ltd.) heated to 45°C, and the second raw material composition was heated to 45°C (heating temperature: 45°C). It was poured into a mold (length 12 mm × width 18 mm × thickness 14 mm), pressed under a load of 2 MPa, and held for 5 minutes to fill the mold.

[0091] (5) Radical polymerization process (curing process) The second raw material composition filled into the mold was subjected to radical polymerization at 120°C for 15 hours under nitrogen pressure (0.3 MPa), resulting in a polyurethane composite material with filler dispersed in a polyurethane resin matrix. The appearance of the cured product obtained by radical polymerization was uniform, with no areas that were partially insufficiently cured.

[0092] (6) Evaluation of polyurethane composite materials (cured bodies) The resulting polyurethane composite material was evaluated for flexural strength, underwater flexural strength, water resistance, and uniformity. The evaluation methods and results are shown below.

[0093] [Flexural strength BS d ] The obtained polyurethane composite material (cured body) was cut using a low-speed diamond cutter (manufactured by Buehler) and then polished with #2000 waterproof abrasive paper to prepare five rectangular columnar test pieces (thickness: approximately 1.2 mm x width: approximately 4.0 mm x length: 14.0 mm). Next, a three-point bending test was performed on each test piece using an autograph (manufactured by Shimadzu Corporation), and the bending load at the maximum point was measured. The bending strength BS was then calculated based on the following formula (1). The bending load at the maximum point was measured with a support distance of 12.0 mm and a crosshead speed of 1.0 mm / min. As a result, the average value of the bending strength BS of the five test pieces (Bending strength BS d ) was 249 MPa. ·Formula (1) BS=3PS / 2WB 2 (In formula (1), BS is the bending strength (MPa), P is the bending load at the maximum point (N), S is the distance between supports (12.0 mm), W is the width of the test piece (actual measurement, mm), and B is the thickness of the test piece (actual measurement, mm).)

[0094] [Underwater bending strength BS W ] Five test pieces were prepared in the same manner as described in the [Flexural strength] section, and all test pieces were stored in ion-exchanged water at 37°C for one week. After that, the test pieces were taken out of the ion-exchanged water, and after removing the moisture adhering to the surface, a three-point bending test was carried out under the same test conditions as described in the [Flexural strength] section, and the bending load at the maximum point of the test piece after underwater storage was measured. Then, the bending strength BS of each test piece after underwater storage was calculated based on formula (1). As a result, the average value of the bending strength BS of the five test pieces after underwater storage (underwater bending strength BS w ) was 207 MPa.

[0095] [Retention rate (water resistance)] The retention rate, which is an index showing the water resistance of the cured body, was calculated based on the following formula (2). In this example, the retention rate was 83%, confirming high water resistance. ·Formula (2) Retention rate (%)=100×BS W / BS d [In formula (2), BS W is the average value of the bending strength BS of 10 test specimens after storage in water (MPa), BS d represents the average value (MPa) of the bending strength BS of 10 test pieces.

[0096] [Uniformity] The uniformity of the cured body was evaluated by visually observing the appearance of the cured body and the cut surface obtained by dividing the cured body into approximately two equal parts. Here, whether the cured body had uniformity was determined by whether or not there were curing irregularities and cracks on the surface and cut surface of the cured body. If neither curing irregularities nor cracks were observed, the cured body was judged to be uniform, and if at least one of curing irregularities and cracks was observed, the cured body was judged to be non-uniform. For the cured body of Example 1, neither curing irregularities nor cracks were observed, and it was found to be uniform.

[0097] Examples 2 and 3 The holding temperature (heating temperature) during mold filling in the molding step was changed as shown in Table 2, and the second raw material composition obtained in Example 1 was filled into the mold, followed by a radical polymerization step, to produce a polyurethane composite material. The fluidity of the second raw material composition at the heating temperature during the molding step and the resulting polyurethane composite material were evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0098] Comparative Examples 1-2 The holding temperature (heating temperature) during mold filling in the molding step was changed as shown in Table 2, and the second raw material composition obtained in Example 1 was filled into the mold, followed by a radical polymerization step, to produce a polyurethane composite material. The fluidity of the second raw material composition at the heating temperature during the molding step and the resulting polyurethane composite material were evaluated in the same manner as in Example 1. The results are shown in Table 2. Note that "non-uniform" in the uniformity evaluation means that there was uneven curing.

[0099] Examples 4 to 8 A second raw material composition was prepared in the same manner as in Example 1, except that the raw materials, a2 / a1 molar ratio, polymerizable monomer blending ratio Rr, and filling rate used in Example 1 were changed as shown in Table 1, and the holding temperature (heating temperature) during mold filling in the molding step was changed as shown in Table 2. The resulting second raw material composition was filled into a mold and then radical polymerization was carried out to produce a polyurethane composite material. The fluidity of the second raw material composition at the heating temperature during the molding step and the resulting polyurethane composite material were evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0100] Comparative Example 3 The holding temperature (heating temperature) during mold filling in the molding step was changed as shown in Table 2, and the second raw material composition obtained in Example 4 was filled into the mold and then radical polymerization was carried out to produce a polyurethane composite material. The fluidity of the second raw material composition at the heating temperature during the molding step and the resulting polyurethane composite material were evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0101] [Table 1]

[0102] [Table 2]

Claims

1. A diol compound (a1) having one or more radically polymerizable groups; a polymerizable monomer (B) having one or more radically polymerizable groups in the molecule and not undergoing a polyaddition reaction with either the diol compound (a1) or a diisocyanate compound; a 10-hour half-life temperature: T １０ a first raw material composition preparation step of preparing a first raw material composition containing a thermal radical polymerization initiator (C) having a temperature of 60°C or higher; and a filler (D); a second raw material composition preparation step of mixing the first raw material composition with a diisocyanate compound (a2) to cause a polyaddition reaction between the diol compound (a1) and the diisocyanate compound (a2) to form a polyurethane component (A) having a number average molecular weight of 1,500 to 5,000 and having a radically polymerizable group, thereby preparing a second raw material composition comprising the polyurethane component (A), the polymerizable monomer (B); a thermal radical polymerization initiator (C); and a filler (D), and which may contain unreacted diol compound (a1) and / or unreacted diisocyanate compound (a2); The temperature of the second raw material composition is 40° C. or higher and the T １０ The mixture is filled into a mold while being kept at a temperature 15° C. lower than the temperature at which the T １０ Temperature 10℃ lower than T １０ a molding step of heating the mixture to a temperature 25°C higher than the temperature at which the mixture was heated to perform radical polymerization, thereby obtaining a molded article of a polyurethane composite material in which the filler (D) is dispersed in a matrix made of a polyurethane resin having a crosslinked structure formed by radical polymerization of the radically polymerizable groups of the polyurethane component (A) and the polymerizable monomer (B); Including, When the contents (parts by mass) of the respective components contained in the second raw material composition are respectively defined as the content of the polyurethane component (A): Ar, the content of the polymerizable monomer (B): Br, the content of the diol compound (a1): a1r, and the content of the diisocyanate compound (a2): a2r, Formula: Rr=100×Br / [a1r+a2r+Ar+Br] By setting the polymerizable monomer blending ratio Rr defined by the formula (1) to 5% by mass or more and less than 20% by mass, the proportion of the polyurethane component in the polyurethane-based resin is more than 80% by mass and 95% by mass or less. A method for producing a polyurethane composite material molded article, comprising:

2. 2. The method for producing a polyurethane composite material molded article according to claim 1, wherein the content of the filler (D) in the second raw material composition is 60% by mass to 80% by mass.

3. 3. The method for producing a polyurethane composite material molded article according to claim 1, wherein the polymerizable monomer (B) comprises a polymerizable monomer represented by the following structural formula (1): 【Chemical 1】 [In the above structural formula (1), R １１ and R １２ is a hydrogen atom or a methyl group, and n １ is an integer from 1 to 10.

4. The method for producing a polyurethane composite material molded article according to any one of claims 1 to 3, wherein the diol compound (a1) is a diol compound in which the number of atoms constituting the main chain in the divalent organic residue intervening between the two hydroxyl groups contained in the diol compound is 2 to 8.

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