Method for producing polyurethane composite molded body

Abstract

To provide a method for producing a polyurethane composite molded body, which is uniform, has excellent strength and water-resistance, and can be divided into small portions and filled into a mold in powder form.SOLUTION: A raw material powder consisting of a solid powder consisting of a raw material composition containing a radically polymerizable polyurethane component (A) having a number average molecular weight of 1500 to 5000 and liquefied at 40 to 80°C, a thermal radical polymerization initiator (B) having a 10-hour half-life temperature: T10 of 90 150°C, and an inorganic filler (C) is filled into a mold, heated to a temperature equal to or higher than the liquefying temperature of the polyurethane component (A) and not exceeding the T10 of the thermal radical polymerization initiator, and then heated to a temperature equal to or higher than 5°C higher than the T10 of the thermal radical polymerization initiator and not exceeding 200°C to polymerize and harden the material.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a polyurethane-based composite material molded body.

Background Art

[0002] In dental treatment, in recent years, a method using a dental CAD / CAM system has been attracting attention as a technique for producing dental prostheses such as inlays, onlays, crowns, bridges, and implant superstructures. This method produces a dental prosthesis by cutting a dental blank (also called a "mill blank") with a computer-controlled cutting machine based on the three-dimensional coordinate data of the dental prosthesis designed by CAD, and can significantly reduce the time and labor required for production compared to conventional methods.

[0003] A dental blank (mill blank) is a molded body in the form of a block or disk made of a dental cutting material that serves as the material for a dental prosthesis, and has a cutting portion and a holding portion for attaching it to a cutting machine. As dental cutting materials, various materials such as glass ceramics, zirconia, titanium, and resin are used appropriately according to the application and characteristics.

[0004] As a resin-based material for dental cutting, a cured body of a curable composition containing an inorganic filler such as silica, a polymerizable monomer such as methacrylate, a polymerization initiator, etc. is generally used and known. However, conventional resin-based materials for dental cutting based on (meth)acrylic resin have limitations in their strength, and there is a need for a material that can also be used for dental prostheses that require high strength such as molar crowns and bridges.

[0005] In response to such requirements, materials using polyurethane resins having higher strength than (meth)acrylic resins have been proposed. For example, Patent Document 1 and Patent Document 2 describe that, as a polyurethane-based composite material excellent in strength and water resistance, a molded body composed of "a polyurethane-based composite material in which a filler is dispersed in a matrix composed of a polyurethane-based resin having a crosslinked structure formed by radical polymerization of the radical-polymerizable group of a radical-polymerizable polyurethane component (A) having a number average molecular weight of 1500 to 5000 and a radical-polymerizable monomer (B)" is uniform throughout, excellent in strength and water resistance, and suitable as a material for dental cutting.

[0006] Also, Patent Document 1 and 2 describe that the radical-polymerizable polyurethane component (A) can be obtained by polyaddition reaction of a radical-polymerizable diol (a1) and a diisocyanate (a2), and that the polyurethane-based composite material can be obtained by adding the diisocyanate (a2) to a first raw material composition containing a radical-polymerizable diol (a1), a non-additive radical-polymerizable monomer, a thermal polymerization initiator, and a filler, performing a polyaddition reaction, and then thermally polymerizing a second raw material composition containing the radical-polymerizable polyurethane component (A), the polymerizable monomer, the thermal radical polymerization initiator, and the filler.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] Incidentally, in the polyurethane-based composite materials disclosed in Patent Documents 1 and 2, the content of the radically polymerizable polyurethane component (A) in the polyurethane-based resin is 25 to 95% by mass. According to Patent Document 2, when the content exceeds 95% by mass, it is said that it becomes very difficult to obtain a polyurethane-based composite material with a uniform crosslinked structure introduced.

[0009] Also, as described in Patent Document 2, in order to obtain a molded body of a polyurethane-based composite material using a polyurethane-based resin having a radically polymerizable polyurethane component content of 80 to 95% by mass (expected to have high strength) by casting polymerization, since the fluidity of the second raw material composition at room temperature is extremely low, a thermal polymerization initiator with a 10-hour half-life temperature: T 10 of 60°C or higher is used, and before filling the second raw material composition into the mold, it is necessary to hold (preheat) it at 40°C or higher and at a temperature 15°C lower than T 10 is required.

[0010] However, in order to efficiently mass-produce the molded body, when a large amount of the second raw material composition is preheated at once and then filled into the mold in small portions, not only does the energy required for heating increase due to the lengthening of the preheating time, but radical polymerization may proceed during preheating, making it difficult to fill the mold.

[0011] Therefore, an object of the present invention is to provide a method capable of efficiently and stably producing a molded body having desired properties even when the production amount is increased when producing a molded body made of a polyurethane-based composite material in which a filler is dispersed in a matrix in a polyurethane-based resin having a high content of a radically polymerizable polyurethane component (A) by casting polymerization.

Means for Solving the Problems

[0012] The present invention solves the above problems, and a first aspect of the present invention is a method for producing a molded body of a polyurethane-based composite material in which a filler is dispersed in a matrix made of a polyurethane-based resin having a crosslinked structure, A radical-polymerizable polyurethane component (A) composed of a polyurethane oligomer having a number-average molecular weight of 1,500 to 5,000 and liquefying at 40 to 80°C and having a radical-polymerizable group in the molecule, with a half-life temperature of 10 hours: T 10 A raw material powder preparation step of preparing a raw material powder composed of a powder body composed of a raw material composition containing a thermal radical polymerization initiator (B) having a half-life temperature of 90 to 150°C for 10 hours and an inorganic filler (C) and liquefying at 40 to 80°C; After filling the raw material powder into a mold, heating it to a temperature equal to or higher than the temperature at which the raw material composition liquefies and lower than or equal to a temperature 10°C lower than the T of the thermal radical polymerization initiator to make the raw material powder into a paste state and holding it in a preliminary heating step; 10 After filling the raw material powder into a mold, heating it to a temperature equal to or higher than the melting point of the radical-polymerizable polyurethane component (A) and lower than or equal to a temperature 10°C lower than the T of the thermal radical polymerization initiator (T -10°C) or lower to make the raw material powder into a paste state and holding it in a preliminary heating step; and 10 After the preliminary heating step, heating the raw material powder to a temperature equal to or higher than a temperature 5°C higher than the T of the thermal radical polymerization initiator (T 10 +5°C) and heating it to a temperature of 200°C or lower to polymerize and cure it in a main heating step; Including 10 A method for producing a polyurethane-based composite material molded body, characterized in that 10 After the preliminary heating step, heating the raw material powder to a temperature equal to or higher than a temperature 5°C higher than the T of the thermal radical polymerization initiator (T Including This is a method for producing a polyurethane-based composite material molded body, characterized by the above.

[0013] Note that the half-life temperature of 10 hours: T 10 Is a generally used index to represent the reactivity of a thermal polymerization initiator, and means the temperature at which the amount of the thermal polymerization initiator decreases to half of the initial amount after 10 hours from the initial stage.

[0014] In the manufacturing method of the above-described form (hereinafter, also referred to as "the manufacturing method of the present invention"), in the raw material powder preparation step, a first raw material composition containing a radically polymerizable diol compound (a1), a thermal radical polymerization initiator (B), and an inorganic filler (C), and optionally containing a non-additive radically polymerizable monomer (D), and a diisocyanate compound (a2) in an amount of 0.8 to 1.2 mol per 1 mol of the (a1) are mixed to cause polyaddition of the (a1) and the (a2), thereby including a polyaddition step of generating the radically polymerizable polyurethane component (A). When the first raw material composition contains the (D), the amount of the (D) used in the total mass of the (A), the (a1), the (a2), and the (D) used in the polyaddition step (hereinafter, also referred to as "polymerizable monomer blending ratio: Rr") is made less than 5% by mass, whereby a raw material powder composed of solid powder particles composed of a raw material composition that may contain the (D) is prepared, which is preferable. Note that the above Rr is also represented by the following formulas when the content of (A) contained in the raw material composition is Ar (parts by mass), the content of (D) is Dr (parts by mass), the content of unreacted (a1) is a1r (parts by mass), and the content of unreacted (a2) is a2r (parts by mass).

[0015] Formula: Rr = {Dr / (a1r + a2r + Ar + Dr)} × 100 Further, in the above preferable aspect, it is preferable that the radically polymerizable diol compound (a1) and the diisocyanate compound (a2) are a compound represented by the following general formula (1) and a compound represented by the following general formula (2), respectively.

[0016] General formula (1): HO-L-(A) x -(L) x -OH {In the above general formula (1), when "-L-" represents an acryloyloxy group or a methacryloyloxy group as "-X-", -CH2-CH(CH2-X)- or -CH2-(CH-X)-CH2- is a divalent group represented by, in the above formula, "-A-" is, -O-CH2-CH2-O- is a divalent group represented by, and x is 0 or 1.} General formula (2): O=C=N-CH2-R-CH2-N=C=O In the above general formula (2), "-R-" is -CH(CH3)-CH2―C(CH3)2-CH2- or -C(CH3)2-CH2―CH(CH3)-CH2- is a group represented by or an m-phenylene group.}

Advantages of the Invention

[0017] In the production method of the present invention, when producing a "polyurethane-based composite material molded body using a polyurethane-based resin with a high content of polyurethane component", which is known to be excellent in strength, water resistance, and uniformity, by casting polymerization, it is not necessary to set it to a predetermined heating state before filling the (second) raw material composition into the mold (molding die). And even when mass-producing using a large number of molds, it is possible to make the heating conditions (thermal history) of the (second) raw material composition before, during, and after filling each mold uniform and constant. For this reason, it becomes possible to efficiently and stably produce (mass-produce) a molded body having the desired characteristics.

Modes for Carrying Out the Invention

[0018] 1. Background of the Invention and Outline of the Invention The inventors considered that the above problems could be solved by making the (second) raw material composition into a powder form, filling it directly into a mold without liquefying it, and then performing polymerization after liquefying it by heating, and conducted studies. As a result, by setting the blending amount of the non-additive polymerizable monomer amount (D), which is determined by the polymerizable monomer blending ratio Rr, in the second raw material composition to less than 10% by mass (including the case of 0% by mass: not blending), preferably less than 5% by mass, the (second) raw material composition may be in a powder state. In that case, it can be filled into a mold as it is in a powder state, and by performing polymerization through a two-step heating process (i.e., a preliminary heating process and a main heating process) that satisfies specific conditions after filling, a molded article having the desired properties can be stably obtained, and thus the present invention has been completed.

[0019] In addition, when performing heat polymerization without going through the above two-step heating process during heat polymerization, it is very difficult to obtain a molded article having good physical properties. For example, as shown in Comparative Examples 1 and 2 described later, when directly performing the main heating process without going through the preliminary heating process, it is impossible to obtain a polyurethane-based composite material molded article excellent in strength and water resistance. In the production method of the present invention, by going through the preliminary heating process, after homogenizing the powder-like (second) raw material composition with a very low liquid component content in the mold, radical polymerization is performed at a high temperature all at once, so that the formation of crosslinking points by radical polymerization proceeds uniformly, and it is considered that a polyurethane-based composite material molded article having the desired physical properties can be obtained.

[0020] The production method of the polyurethane-based composite material molded article of the present invention will be described in detail below.

[0021] In the present specification, unless otherwise specified, the notation "x to y" using numerical values x and y means "x or more and y or less". When a unit is attached only to the numerical value y in such notation, the unit shall also apply to the numerical value x. Further, in the present specification, the "radical polymerizable group" means a functional group that reacts with an initiator that generates radicals and polymerizes, and specifically means a group having a radical polymerizable carbon-carbon double bond such as a vinyl group, a (meth)acrylate group, a (meth)acryloyloxy group, and a styryl group. Furthermore, the term "(meth)acrylic" means both "acrylic" and "methacrylic". Similarly, the term "(meth)acrylate" means both "acrylate" and "methacrylate", the term "(meth)acryloyl" means both "acryloyl" and "methacryloyl", and the term "(meth)acryloyloxy" means both "acryloyloxy" and "methacryloyloxy". 2. Manufacturing method of the present invention The manufacturing method of the present invention is a method for manufacturing the polyurethane-based composite material molded body of the present invention, a radical polymerizable polyurethane component (A) composed of a polyurethane oligomer having a radical polymerizable group in the molecule, having a number average molecular weight of 1500 to 5000 and liquefying at 40 to 80°C, 10-hour half-life temperature: T 10 a raw material powder preparation step of preparing a raw material powder composed of a granular body composed of a raw material composition that liquefies at 40 to 80°C, containing a thermal radical polymerization initiator (B) having a T of 90 to 150°C and an inorganic filler (C); after filling the raw material powder into a mold, heating at a temperature equal to or higher than the temperature at which the raw material composition liquefies and at a temperature equal to or lower than a temperature 10°C lower than the T of the thermal radical polymerization initiator to make the raw material powder into a paste state and holding it; a preheating step; and 10 after the preheating step, a main heating step of heating the raw material powder at a temperature higher than a temperature 5°C higher than the T of the thermal radical polymerization initiator and at a temperature of 200°C or lower to polymerize and cure it. The present invention is characterized by including the above steps. Hereinafter, each step will be described in detail. 10 The present invention is characterized by including the above steps. Hereinafter, each step will be described in detail.

[0022] (1) Raw material powder preparation process The raw material composition, which is the constituent material of the raw material powder prepared in the raw material powder preparation process, belongs to the category of the second raw material composition in Patent Documents 1 and 2, and is solid at a temperature below 40°C and exhibits a melting property of liquefying when heated to 40 - 80°C. And the raw material powder composed of such a raw material composition (naturally solid because it is a powder) is handled in a state below 40°C.

[0023] Here, among the components (A) - (C) that constitute the raw material composition, as component (A) that constitutes the resin matrix and determines the melting characteristics of the raw material composition, among those that can be used as components of the second raw material composition in Patent Documents 1 and 2, those that exhibit a melting property of liquefying when heated to 40 - 80°C are used. Regarding component (B), among the thermal radical polymerization initiators that can be used as components of the second raw material composition in Patent Documents 1 and 2, those with T 10 of 90 - 150°C can be used without particular limitation. Further, regarding component (C), the inorganic fillers that can be used as components of the second raw material composition in Patent Documents 1 and 2 can be used without particular limitation.

[0024] It should be noted that the fact that component (A) has such melting characteristics can be confirmed by the fact that the raw material powder obtained in the raw material powder preparation process becomes a uniform paste state when maintained at a temperature within the range of 40 - 80°C. If the temperature at which it liquefies and becomes a uniform paste state when heating a solid (so that the overall temperature becomes constant) is defined as the "liquefaction temperature", it can be said that the liquefaction temperatures of the radical polymerizable polyurethane component (A), the raw material composition, and the raw material powder are 40 - 80°C.

[0025] In addition, the fact that the radically polymerizable polyurethane component (A) has a radically polymerizable group in the molecule can be confirmed, for example, by the presence of an absorption attributed to the radically polymerizable group in infrared spectroscopic measurement. These amounts can also be analyzed from the absorption amount.

[0026] The number average molecular weight of the radically polymerizable polyurethane component (A) used in the production method of the present invention needs to be 1,500 to 5,000, similar to the radically polymerizable polyurethane component (A) described in Patent Documents 1 and 2. By setting the number average molecular weight to 1,500 or more, a polyurethane-based composite material molded body having sufficient strength can be obtained. Further, it is substantially impossible or very difficult to obtain a radically polymerizable polyurethane component (A) having a number average molecular weight exceeding 5,000.

[0027] Here, it means the number average molecular weight in terms of polystyrene determined by GPC (gel permeation chromatography) measurement. The number average molecular weight of the radically polymerizable polyurethane component (A) in the raw material composition can be determined by adding a solvent such as THF (tetrahydrofuran) to the raw material composition as needed, removing insoluble components such as fillers by operations such as filtration and centrifugation, and performing GPC measurement on the obtained solution. The measurement can be carried out under the following measurement conditions using ADVANCED POLYMER CHROMATOGRAPHY (manufactured by Waters Japan).

[0028] [Measurement Conditions] Measuring device: ADVANCED POLYMER CHROMATOGRAPHY (manufactured by Waters Japan) · Column: ACQUITY APC TM XT 45 1.7μm ACQUITY APC TM XT 125 2.5μm · Column temperature: 40°C · Developing solvent: THF (flow rate: 0.5 ml / min) · Detector: Photodiode array detector 254 nm (PDA detector).

[0029] In the preliminary heating step described below, from the viewpoint that the raw material powder particles are likely to become a paste-like property, more uniform radical polymerization is facilitated, and a uniform and high-strength polyurethane-based composite material molded body is easily obtained, the above number average molecular weight is preferably 1500 to 3500, and more preferably 2000 to 3000.

[0030] Incidentally, the radically polymerizable polyurethane component (A) having an average molecular weight of 1500 to 5000 can be obtained by subjecting a radically polymerizable diol (a1) and a diisocyanate (a2) to a polyaddition reaction as described in Patent Documents 1 and 2. However, from the viewpoint of the efficiency of preparing the (second) raw material composition, the polyaddition reaction is carried out during the preparation of the (second) raw material composition, and the preparation of the (second) raw material composition and the preparation of the radically polymerizable polyurethane component (A) are carried out simultaneously. That is, by adding a diisocyanate (a2) to a first raw material composition containing a radically polymerizable diol (a1), a non-additive radically polymerizable monomer, a thermal polymerization initiator, and a filler and carrying out a polyaddition reaction, both are prepared simultaneously. Also in the present invention, a raw material composition having the above-described melting characteristics is prepared in the same manner, and then the obtained raw material composition is pulverized (a pulverization step is performed) after being cooled to a temperature lower than the liquefaction temperature if necessary) to a solid state to prepare raw material powder particles. Therefore, a method for suitably preparing a raw material composition and making it into raw material powder particles will be described below.

[0031] (2) Method for preparing suitable raw material composition and raw material powder particles From the perspective of efficiently obtaining the radically polymerizable polyurethane component (A) having the number average molecular weight and melting characteristics as described above and being able to reliably use such a component (A), the raw material composition contains a radically polymerizable diol compound (a1), the thermal radical polymerization initiator (B), and the inorganic filler (C), and does not contain the non-additive radically polymerizable monomer (D), or contains (D) in an amount such that the polymerizable monomer blending ratio: Rr is less than 5% by mass. A first raw material composition is prepared, and the diisocyanate compound (a2) is mixed with (a1) in an amount of 0.8 to 1.2 moles per 1 mole of (a1), and (a1) and (a2) are subjected to polyaddition to produce the radically polymerizable polyurethane component (A). It is preferably prepared by a method including a polyaddition step. According to such a method, the obtained raw material composition does not contain (D) or contains (D) with Rr less than 5% by mass, and a composition having the melting characteristics as described above can be obtained almost certainly.

[0032] (2-1) Raw materials At this time, as the radically polymerizable diol compound (a1), the diisocyanate compound (a2), the inorganic filler (C), and the non-additive radically polymerizable monomer (D) used as necessary, in principle, those that can be used as components of the second raw material composition in Patent Documents 1 and 2 can be used.

[0033] However, from the perspective of the strength of the finally obtained molded body, as the radically polymerizable diol compound (a1) and the diisocyanate compound (a2), a compound represented by the following general formula (1) and a compound represented by the following general formula (2) are used respectively, and it is preferable to prepare a raw material composition containing a radically polymerizable polyurethane component (A) containing a repeating unit represented by the following general formula (3).

[0034] · General formula (1) showing the structure of the radically polymerizable diol compound (a1): HO-L-(A) x -(L) x -OH · General formula (2) showing the structure of the diisocyanate compound (a2): O=C=N-CH2-R-CH2-N=C=O · General formula (3) representing the structural unit of the radically polymerizable polyurethane component (A): -[-O-L-(A) x -(L) x -O-C(=O)-NH-CH2-R-NH-C(=O)-]- 。

[0035] In the general formulas (1) and (3) above, "-L-" is acryloyloxy group: CH2=CH-C(=O)-O- or methacryloyloxy group:: CH3-CH=CH-C(=O)-O- When represented by "X-", -CH2-CH(CH2-X)- or -CH2-(CH-X)-CH2- means a divalent group represented by

[0036] Also, "-A-" in the general formulas (1) and (3) is -O-CH2-CH2-O- means a divalent group represented by, and x means 0 or 1.

[0037] Furthermore, "-R-" in the general formulas (2) and (3) is -CH(CH3)-CH2―C(CH3)2-CH2- or -C(CH3)2-CH2―CH(CH3)-CH2- means a group represented by or an m-phenylene group.

[0038] Examples of the compound represented by the general formula (1) that can be preferably used as the radically polymerizable diol compound (a1) include ethylene glycol diglycidyl methacrylate, glycerol monomethacrylate, etc. Among these, glycerol monomethacrylate is particularly preferably used because the polyurethane-based composite material molded body is likely to form a uniform crosslinked structure.

[0039] Examples of the compound represented by the general formula (2) that can be preferably used as the diisocyanate compound (a2) include m-xylylene diisocyanate, trimethylhexamethylene diisocyanate (2,2,4-, 2,4,4-mixture), and the like. Among these, it is particularly preferable to use m-xylylene diisocyanate for the reason of the strength of the polyurethane-based composite material molded body.

[0040] Also, for the thermal radical polymerization initiator (B) where T 10 is 90 to 150°C, from the viewpoint of suppressing radical generation in the preheating step and the viewpoint of facilitating radical generation in the main heating step, T 10 is preferably 95°C to 140°C, particularly preferably 98°C to 130°C. Examples of the compounds that can be preferably used include t-butyl peroxy laurate (T 10 : 98°C), t-butyl cumyl peroxide (T 10 : 120°C), and the like.

[0041] As described above, as the inorganic filler (C), those that can be used as components of the second raw material composition in Patent Documents 1 and 2 can be used without particular limitation, but it is preferable to use powder particles composed of silica, titania, zirconia, or their composite oxide particles, and it is particularly preferable to be silica or its composite oxide. From the viewpoint of easily improving the content of the filler (C) in the polyurethane-based composite material, it is preferable that the above powder particles are a mixture of a plurality of powder particles having different average particle diameters. The average particle diameter of the above powder particles means the average particle diameter determined by image analysis using a scanning electron microscope (SEM) image. When the powder sample is observed at a magnification of 5000 to 100000 times with a scanning electron microscope so that 100 or more spherical particles whose overall shape can be confirmed are included in the field of view, based on the image (or photograph) obtained, the maximum diameter (nm) of each of 30 or more arbitrarily selected particles is measured, and the value obtained by dividing the sum by the number: n (a natural number of ≧ 30) is meant. That is, the maximum diameter of each particle is represented by x i (i is a natural number from 1 to n.), and the average particle diameter is xAV When expressed as x AV =(Σx i ), it means the value defined by / n.

[0042] Specifically, it is preferably a mixture containing 5 to 95% by mass, preferably 10 to 90% by mass of powder particles with an average particle size of 0.001 μm or more and less than 0.1 μm, and the remainder being powder particles with an average particle size of 0.1 to 100 μm. More preferably, it is a mixture containing 15 to 85% by mass, preferably 25 to 80% by mass of powder particles with an average particle size of 0.01 μm or more and less than 0.1 μm, and the remainder being powder particles with an average particle size of 0.2 to 50 μm. Further, from the viewpoints of the abrasion resistance, surface lubricity, and gloss persistence of the molded article as the target product, the particles constituting the powder particles with an average particle size of 0.1 μm to 100 μm are preferably spherical with an average uniformity of 0.6 or more, particularly 0.8 or more. Here, the average uniformity can be calculated by measuring the major axis (L), which is the maximum diameter, and the minor axis (B) orthogonal to the major axis (L) for each of n particles (usually 40 or more, preferably 100 or more) in the image analysis of the captured image of a scanning or transmission electron microscope, obtaining the ratio (B / L), and dividing the sum (ΣB / L) by n. Furthermore, as the filler (C), in order to improve the compatibility with the matrix made of a polyurethane-based resin and improve the mechanical strength and water resistance of the polyurethane-based composite material molded article, it is preferable to use powder particles surface-treated with a silane coupling agent or the like.

[0043] As the non-additive radical polymerizable monomer (D) used as needed, similar to Patent Documents 1 and 2, a compound having at least one radical polymerizable group and not undergoing an addition polymerization reaction with either the radical polymerizable diol compound (a1) or the diisocyanate compound (a2) can be used without particular limitation. Since the raw material composition is solid at 25°C and has a melting property that does not liquefy even when heated to at least 40°C, and in this heating step, an effect of facilitating the uniform occurrence of the polymerization reaction can be obtained, the raw material composition preferably contains a compound represented by the following general formula (4) as the non-additive radical polymerizable monomer (D) with Rr being 0.5% by mass or more and less than 5.0% by mass, particularly 1.0 to 4.0% by mass.

[0044] [Chemical formula]

[0045] In the formula, R 11 and R 12 mean a hydrogen atom or a methyl group, and n1 means an integer of 1 to 10, preferably an integer of 1 to 3.

[0046] Examples of the compound represented by the above general formula (4) include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, pentaethylene glycol di(meth)acrylate, hexaethylene glycol di(meth)acrylate, heptaethylene glycol dimethacrylate, octaethylene glycol dimethacrylate, nonaethylene glycol dimethacrylate, decaethylene glycol dimethacrylate, and the like.

[0047] From the viewpoint of the highness of the above effects, among these compounds, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, and triethylene glycol di(meth)acrylate having a viscosity of 1 mPa·s to 1000 mPa·s, particularly 1 mPa·s to 100 mPa·s at normal temperature are particularly preferably used.

[0048] In addition to the essential components described above, various other additives may be blended in the raw material composition. Examples of the various additives include a polymerization inhibitor, a fluorescent agent, an ultraviolet absorber, an antioxidant, a pigment, an antibacterial material, an X-ray contrast agent, and the like.

[0049] (2-2) Polyaddition step and pulverization step In the polyaddition step, the first raw material composition and the diisocyanate compound (a2) in an amount of 0.8 to 1.2 moles per 1 mole of the (a1) are mixed to cause polyaddition of the (a1) and the (a2).

[0050] The first raw material composition contains a radically polymerizable diol compound (a1), a thermal radical polymerization initiator (B), and an inorganic filler (C). The blending ratio of each component is such that the radical polymerization initiator is preferably in the range of 0.01 to 15.0 parts by mass, more preferably 0.05 to 10.0 parts by mass, based on 100 parts by mass of the radically polymerizable diol compound (a1). Also, the amount of the filler (C) used may be appropriately determined according to the physical properties such as the strength of the target polyurethane-based composite material molded body. From the viewpoint of high strength etc. when used as a dental cutting material, it is preferably 60 to 80% by mass, more preferably 65 to 75% by mass, expressed as mass% based on the mass of the raw material composition (hereinafter sometimes simply referred to as "filling rate"). Further, when the (second) raw material composition contains other additives, it is preferably blended into the first raw material composition. The addition amount may be appropriately determined according to the desired purpose. Also, if necessary, as other additives, a catalyst that promotes the polyaddition reaction such as tin octylate or dibutyltin diacetate may be added. The first raw material composition can be prepared by mixing these raw materials. The mixing method when mixing each component is not particularly limited, and methods using a magnetic stirrer, a Lycra machine, a planetary mixer, a centrifugal mixer, etc. are appropriately used.

[0051] After preparing the first raw material composition, the diisocyanate compound (a2) is mixed, and the (a1) and the (a2) are polyadded to produce the polyurethane component (A), thereby preparing the raw material composition. When adding the diisocyanate compound (a2) to the first raw material composition, it may be added all at once, but it is added in multiple portions to form a polyurethane oligomer (also referred to as a prepolyurethane component) having a small number average molecular weight, and then the diisocyanate compound is further added to form a radically polymerizable polyurethane component (A), so that the polyurethane component in the raw material composition is likely to be uniformly dispersed. On the other hand, when forming a prepolyurethane component, the diisocyanate compound (a2) is preferably 0.5 mol or less, more preferably 0.3 mol or less, per 1 mol of the radically polymerizable diol compound (a1).

[0052] The polyaddition reaction is carried out such that 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, it is carried out until the degree of progress of the polyaddition reaction approaches the maximum value (saturation value). At this time, the reaction temperature of the thermal radical polymerization initiator (B) used is preferably lower than T 10 and the polyaddition reaction is more preferably carried out while maintaining a temperature 80°C to 20°C lower than T 10 , particularly 70°C to 30°C lower. Note that the radical polymerization reaction that inevitably occurs to a slight extent even when the above-described method is adopted is acceptable. The reaction time varies depending on the reaction temperature. For example, (1) if the reaction temperature is 30°C or higher and less than 50°C, 60 hours or more is preferable, and 72 hours or more is more preferable; (2) if the heating temperature is 50°C or higher and less than 80°C, 24 hours or more is preferable, and 36 hours or more is more preferable; (3) if the heating temperature is 80°C or higher, 15 hours or more is preferable, and 24 hours or more is more preferable. In the cases shown in (1) to (3) above, the upper limit value of the heating time is not particularly limited, but from a practical viewpoint such as productivity, it is preferably 120 hours or less.

[0053] After the polyaddition step, the raw material composition is cooled to make it solid, and then a pulverization step is carried out. The pulverization method is not particularly limited, and a known pulverization method is used. For example, a method using a mortar, jaw crusher, gyratory crusher, roll crusher, cutter mill, roller mill, jet mill, etc. is appropriately used. Also, the pulverization particle size is not particularly limited, but from the viewpoint of facilitating the subdivision of the raw material powder particles, it is preferably pulverized to about 1 mm, and more preferably pulverized to 1 mm to 0.01 mm. If necessary, coarse particle cutting, classification, etc. are carried out to obtain the raw material powder particles.

[0054] The smaller the average particle diameter of the raw material powder particles, the easier it is to perform sizing. However, if it is too small, the inorganic filler (C) and the radically polymerizable polyurethane component (A) contained in the raw material powder particles may be separated. Therefore, it is preferably 0.01 to 1500 μm, and particularly preferably 0.02 to 1000 μm. Here, the average particle diameter means the average particle diameter determined by image analysis using an optical microscope or a scanning electron microscope (SEM) image, and is based on an image (or photograph) obtained when observing the raw material powder particles. The maximum diameter (μm) of each of 100 or more arbitrarily selected particles is measured, and the value obtained by dividing the sum by the number: n (a natural number of ≧ 100) is meant. That is, the maximum diameter of each particle is represented by x i (where i is a natural number from 1 to n.), and the average particle diameter is represented by x AV . When represented by, x AV =(Σx i ) / n means the value defined by.

[0055] (3) Preheating step In the preheating step, after filling the raw material powder particles into the molding die, the raw material powder particles are heated to a temperature equal to or higher than the liquefaction temperature of the raw material composition and 10 °C lower than the T 10 of the thermal radical polymerization initiator (B) and held in a paste state.

[0056] As the molding die for filling the raw material powder particles, one having a cavity corresponding to the shape of the target molded body can be appropriately used. The material thereof is not particularly limited as long as it can withstand the temperature and pressure during radical polymerization, and materials such as metal, ceramics, and resin can be used. Specifically, those made of SUS, polypropylene, polyacetal, polytetrafluoroethylene, etc. can be preferably used.

[0057] The method for filling the raw material powder particles in the molding die is not particularly limited. For example, after sizing in the molding die using a powder filling machine, the raw material powder particles can be filled into the molding die using a press machine.

[0058] The temperature during filling is not particularly limited as long as the raw material powder can maintain its powder state, but it is usually carried out at room temperature.

[0059] The heating time can be 1 hour or more, but from the perspective of productivity, it is preferably heated for 1 to 72 hours, and more preferably heated for 1 to 24 hours. Also, in order to suppress the formation of voids caused by bubbles in the raw material composition during heating, the raw material composition may be pressurized during heating. There is no limitation on the method of pressurization, and it may be mechanically pressurized or pressurized by bubbles such as nitrogen.

[0060] In the preliminary heating after filling, if the temperature is lower than the liquefaction temperature of the raw material composition, the raw material powder will not become paste-like, and a uniform polyurethane-based composite material molded body cannot be obtained after the main heating process. Also, the T of the thermal radical polymerization initiator 10 If heating is carried out at a temperature exceeding 10°C lower than that, radicals will be generated in the raw material powder, and radical polymerization will proceed, so a uniform polyurethane-based composite material molded body cannot be obtained. From the perspective of obtaining a uniform polyurethane-based composite material molded body, the preliminary heating process is preferably carried out at a temperature (1) 10°C higher than the liquefaction temperature of the raw material composition to a temperature lower than 15°C lower than the T 10 and more preferably at a temperature (2) 15°C higher than the liquefaction temperature of the raw material composition to a temperature lower than 30°C lower than the T 10

[0061] (4) The main heating process In this main heating process, the raw material powder is heated to a temperature of +5°C or higher and 200°C or lower than the T of the thermal radical polymerization initiator to carry out polymerization curing. At this time, by continuously performing this main heating process from the preliminary heating process, the raw material powder can carry out radical polymerization in a paste-like state, so it is easier to obtain a uniform polyurethane-based composite material molded body without curing unevenness. 10

[0062] The heating temperature is the T of the thermal radical polymerization initiator 10 ​​By setting it to 5°C or higher, the radical polymerization rate can be made sufficiently large. Further, by setting the heating temperature to 200°C or lower, it becomes easy to suppress the occurrence of unintended coloring of the cured body. By controlling the heating temperature within the above-described temperature range, polymerization curing can proceed at an industrially acceptable reaction rate. From the viewpoints of accelerating the polymerization rate and suppressing the coloring of the cured body, (T 10 + 10)°C to 190°C is preferable, and (T 10 + 20)°C to 180°C is more preferable. Further, when radical polymerization is carried out by heating, in order to suppress the formation of voids caused by bubbles in the cured body, pressure may be applied during radical polymerization. There is no limitation on the method of applying pressure, and pressure may be applied mechanically or by a gas such as nitrogen.

[0063] By performing the radical polymerization step in this way, a molded body made of a polyurethane-based composite material in which the filler (C) is dispersed in a polyurethane-based resin matrix can be obtained.

[0064] 3. Application example of the production method of the present invention (production of dental cutting material) The polyurethane-based composite material molded body obtained by the production method of the present invention has water resistance while maintaining high strength even in a hydrophilic environment such as in the oral cavity. Because of having such high water resistance, the production method of the present invention is particularly suitable for use as a production method of a dental cutting material when a dental prosthesis is produced by cutting a dental cutting material using a dental CAD / CAM system. When producing a dental cutting material, it is used for a prismatic, cylindrical, angular plate, or disc-shaped mold according to the shape assumed in advance for each product form. The dimensional shape of the mold may be a dimensional shape that substantially matches the dimensional shape of the cured body after radical polymerization in consideration of the shrinkage rate during radical polymerization, etc., or when the cured body obtained by radical polymerization is processed in a subsequent process, it may be a dimensional shape larger than the dimensional shape of the obtained cured body in anticipation of machining allowance.

[0065] After the curing body obtained after this heating process is taken out of the mold, if necessary, post-treatments and post-processings such as heat treatment for relaxing residual stress, shape correction by cutting, and polishing are performed. Subsequently, by joining fixtures such as pins for holding in a CAD / CAM device to the cured body that has undergone these post-treatments and post-processings, a material for dental cutting can be obtained.

Example

[0066] Hereinafter, the present invention will be described with reference to examples and comparative examples, but the present invention is not limited only to these examples.

[0067] The respective components and their abbreviations used in each of the examples and comparative examples are shown below.

[0068] (1) Radical polymerizable diol compound (a1) GLM: Glycerol monomethacrylate BMOHE: Ethylene glycol diglycidyl methacrylate.

[0069] (2) Diisocyanate compound (a2) XDI: m-Xylylene diisocyanate TMHMDI: Trimethylhexamethylene diisocyanate (2,2,4-, 2,4,4- mixture).

[0070] (3) Radical polymerization initiator (B) PBL: t-Butyl peroxy laurate (10-hour half-life temperature 98 °C) PBC: t-Butyl cumyl peroxide (10-hour half-life temperature 120 °C).

[0071] (4) Filler (C) 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) (5) Radical polymerizable monomer (D) 3G: Triethylene glycol dimethacrylate 9G: Polyethylene glycol #400 dimethacrylate Example 1 (1) Raw material powder preparation process First, a mixed composition was prepared by mixing GLM (1.44 parts by mass), which is a radically polymerizable diol compound (a1), and PBC (0.01 parts by mass), which is a radical polymerization initiator (B). Next, F1 (4.80 parts by mass) and F2 (2.06 parts by mass), which are fillers (C), were added to this mixture composition and kneaded to obtain a first raw material composition. The total amount of the first raw material composition and XDI (1.70 parts by mass), which is a diisocyanate compound, were added into a rotation revolution mixer and kneaded. Then, the mixture of the first raw material composition and the diisocyanate compound was heated at 60 °C for 24 hours to carry out a polyaddition reaction to form a radically polymerizable polyurethane component (A) and obtain a raw material composition. The obtained raw material composition was pulverized using a mortar to obtain raw material powder particles. The following evaluations were performed on the obtained composition and raw material powder particles.

[0072] (1-1) Measurement of the number average molecular weight of the radically polymerizable polyurethane component (A) (GPC measurement) 1 g of the obtained raw material powder particles was weighed into a screw tube bottle, 3.5 ml of THF was added and stirred, and the obtained THF solution was centrifuged at 10,000 rpm for 10 minutes using a centrifuge (manufactured by AS ONE Corporation). Next, the supernatant obtained by centrifugation was filtered through a membrane filter (PORE SIZE 20 μm, manufactured by ADVANTEC Co., Ltd.) to obtain a filtrate. Then, for this filtrate, GPC measurement was performed under the GPC measurement conditions shown below to determine the number average molecular weight in terms of polystyrene of the radically polymerizable polyurethane component (A) obtained by the polyaddition reaction. As a result, the number average molecular weight was 1900.

[0073] [GPC measurement conditions] Measuring device: Advanced Polymer Chromatography (manufactured by Waters Japan) · Column: ACQUITY APC TM XT45 1.7 μm ACQUITY APC™ XT125 2.5 μm · Column temperature: 40 °C · Developing solvent: THF (flow rate: 0.5 ml / min) · Detector: Photodiode array detector at 254 nm (PDA detector) (1-2) Confirmation of the state of the raw material composition at 23 °C The obtained raw material composition was weighed into a 1 g mortar and pulverized at 23 °C for 10 minutes. After 10 minutes, if the raw material composition was in a lump shape, it was determined to be in a paste state rather than a solid state. If it had fluidity as a powder, the raw material composition was a solid, and the obtained powder particles were used as the raw material powder particles. For the raw material composition of Example 1, it had fluidity as a powder and was a (solid) raw material powder at 23 °C.

[0074] (1-3) Measurement of the liquefaction temperature of the radical polymerizable group polyurethane 1 g of the obtained raw material powder particles was weighed and heated on a hot plate set at 40 °C for 10 minutes. After heating, since the raw material powder particles were not in a paste state, the hot plate was then set at 50 °C and heated for 10 minutes. After visual confirmation after heating, it was confirmed that the raw material powder particles, which were in a powder state, had become in a paste state, and it was found that the liquefaction temperature of the radical polymerizable group polyurethane of Example 1 was 50 °C.

[0075] (2) Preheating step The obtained raw material powder particles were divided into small portions and filled into a molding die (12 mm in length × 18 mm in width × 14 mm in thickness), and then left standing on a heating press (manufactured by Imoto Seisakusho) heated to 80 °C for 5 minutes. Then, a load of 2 MPa was applied and pressed, and held for 30 minutes.

[0076] The raw material powder particles after pressing were heated at 70 °C for 2 hours under nitrogen pressure (0.3 MPa) for preheating.

[0077] (3) Main heating step After the preliminary heating process, the raw material powder was heated at 150°C for 2 hours under nitrogen pressure (0.3 MPa) to perform the main heating process, allowing radical polymerization to proceed to obtain a polyurethane-based composite material molded body. The appearance of the obtained polyurethane-based composite material molded body showed no partially insufficient curing, and a uniform polyurethane-based composite material molded body was obtained.

[0078] (4) Evaluation of the polyurethane-based composite material molded body (cured body) Regarding the obtained polyurethane-based composite material molded body, the flexural strength, flexural strength in water, retention rate (water resistance), uniformity, and radical polymerizable group consumption rate were evaluated. The evaluation methods and results are shown below.

[0079] (4-1) [Flexural strength BS d After cutting out the obtained polyurethane-based composite material (cured body) with a low-speed diamond cutter (manufactured by Buehler), it was polished using #2000 water-resistant abrasive paper to prepare five prismatic test pieces (thickness: approximately 1.2 mm × width: approximately 4.0 mm × length: 14.0 mm). Next, a three-point bending test was performed on each test piece using an autograph (manufactured by Shimadzu Corporation) to measure the bending load at the maximum point. Then, the flexural strength BS was determined based on the following formula (1). The bending load at the maximum point was measured with the distance between the supports set at 12.0 mm and the crosshead speed set at 1.0 mm / min. As a result, the average value of the flexural strength BS of the five test pieces (flexural strength BS d ) was 298 MPa. · Formula (1) BS = 3PS / 2WB 2 〔In formula (1), BS represents the flexural strength (MPa), P represents the bending load at the maximum point (N), S represents the distance between the supports (12.0 mm), W represents the width of the test piece (measured value, mm), and B represents the thickness of the test piece (measured value, mm).〕 (4-2) [Flexural strength BS in water W ​​Five test pieces were prepared in the same manner as described in the column of [Flexural strength], and all the test pieces were stored in ion-exchanged water at 37 °C for one week. Thereafter, for the test pieces taken out from the ion-exchanged water, after removing the moisture adhering to the surface, a three-point bending test was conducted under the same test conditions as described in the column of [Flexural strength], and the bending load at the maximum point of the test pieces after storage in water was measured. Thereafter, the flexural strength BS was determined for each of the test pieces after storage in water based on Equation (1). As a result, the average value of the flexural strength BS of the five test pieces after storage in water (flexural strength BS in water w ) was 260 MPa.

[0080] (4-3) [Retention rate (water resistance)] The retention rate, which is an index indicating the water resistance of the cured body, was calculated based on the following Equation (2). In this example, the retention rate was 87%, and it was confirmed that the cured body had high water resistance. · Equation (2) Retention rate (%) = 100 × BS W / BS d 〔In Equation (2), BS W is the average value (MPa) of the flexural strength BS of 10 test pieces after storage in water, and BS d represents the average value (MPa) of the flexural strength BS of 10 test pieces.〕 (4-4) [Uniformity] The uniformity of the obtained cured body was evaluated by visually observing the appearance of the cured body and the cut surface obtained by dividing the cured body approximately in half. Here, whether the cured body has uniformity or not is determined by whether there is curing unevenness or cracks on the surface and cut surface of the cured body. If neither curing unevenness nor cracks are confirmed, it is determined to be uniform, and if at least one of curing unevenness and cracks is confirmed, it is determined to be non-uniform. For the cured body of Example 1, neither curing unevenness nor cracks were confirmed, and it was found to be uniform.

[0081] (4-5) [Radical polymerizable group consumption rate (%)] The raw material powder was filled into a PTFE mold having holes of φ10 mm × 1 mm, heated at the same temperature as in the preheating step, and pressure-bonded with a PET film to obtain a sample before polymerization. Another sample was prepared in the same manner, and the preheating step and the main heating step were performed to obtain a sample after polymerization. The radical polymerizable group consumption rate can be calculated based on the peak areas at specific wavelengths obtained by measuring the samples before polymerization and the samples after polymerization (urethane-based composite material molded bodies) by Fourier transform infrared spectroscopy (FT-IR). In this case, the radical polymerizable group consumption rate is calculated based on the following formula. · Formula Radical polymerizable group residual rate (%) = [1 - (r1 / r0)] × 100 〔In the formula, r0 means the normalized peak area ratio (ν6170 / ν4920) obtained by normalizing the peak area (ν6170) by dividing it by the peak area (ν4920) for two peak areas (ν6170 and ν4920) obtained by FT-IR measurement of the sample before polymerization, and r1 means the normalized peak area ratio (ν6170 / ν4920) obtained by normalizing the peak area (ν6170) by dividing it by the peak area (ν4920) for two peak areas (ν6170 and ν4920) obtained by FT-IR measurement of the sample after polymerization (urethane-based composite material molded body). Here, the peak area (ν6170) means the peak area of the absorption peak observed around 6170 cm -1 due to the carbon-carbon double bond of the radical polymerizable group, and the peak area (ν4920) means the peak area of the absorption peak observed around 4920 cm -1 due to the carbonyl group of the urethane bond.〕 As a result of the measurement, it was found that the radical polymerizable group consumption rate of Example 1 was 85%.

[0082] Examples 2 to 8 In the raw material powder granulation process, the amount of filler was changed as shown in Tables 1 and 2, and as shown in Table 1, the addition of the diisocyanate compound was carried out in two steps. After forming the prepolymerized urethane component in the first step, the second step addition was carried out to prepare the raw material powder granule. Thereafter, the preheating process and the main heating process were changed as shown in Table 3. The raw material powder granule and the polyurethane-based composite material molded body were evaluated in the same manner as in Example 1. The results are shown in Tables 1, 2, and 3.

[0083] Examples 9 to 12 In the raw material powder granulation process, the raw material powder granule was prepared in the same manner as in Example 8 except that the amount of filler, the addition amount and type of the diisocyanate compound when forming the prepolymerized urethane component were changed as shown in Table 1. Thereafter, the preheating process and the main heating process were carried out in the same manner as in Example 1. The raw material powder granule and the polyurethane-based composite material molded body were evaluated in the same manner as in Example 1. The results are shown in Tables 1, 2, and 3.

[0084] Examples 13 to 17 In the raw material powder granulation process, the raw material powder granule was prepared in the same manner as in Example 1 except that the radically polymerizable diol compound, the diisocyanate compound, the amount of filler, and the radically polymerizable monomer were changed as shown in Tables 1 and 2, and the preheating process and the main heating process were carried out. The raw material powder granule and the polyurethane-based composite material molded body were evaluated in the same manner as in Example 1. The results are shown in Tables 1, 2, and 3.

[0085] Examples 18, 19 In the raw material powder granulation process, the raw material powder granule was prepared in the same manner as in Example 1 except that the radically polymerizable diol compound, the diisocyanate compound, the amount and type of the thermal radical polymerization initiator were changed as shown in Tables 1 and 2, and the preheating process and the main heating process were carried out. The raw material powder granule and the polyurethane-based composite material molded body were evaluated in the same manner as in Example 1. The results are shown in Tables 1, 2, and 3.

[0086] Comparative Examples 1, 2 In the raw material powder preparation step, the raw material powder was prepared in the same manner as in Example 1 except that the diisocyanate compound was changed as shown in Tables 1 and 2. Thereafter, the preheating step was not performed, and the main heating step was carried out. The evaluation of the raw material powder and the polyurethane-based composite material molded body was carried out in the same manner as in Example 1. The results are shown in Tables 1, 2, and 3.

[0087] Comparative Example 3 The raw material powder was prepared and the main heating step was carried out in the same manner as in Comparative Example 2 except that the preheating step was carried out at 30°C for 2 hours. The raw material powder and the polyurethane-based composite material molded body were evaluated in the same manner as in Example 1. The results are shown in Tables 1, Table 2, and Table 3.

[0088] Comparative Example 4 In the raw material powder preparation step, the raw material composition was prepared in the same manner as in Comparative Example 3 except that the amount of the diisocyanate compound was changed and a radically polymerizable monomer was added. As a result of evaluating the powder of the obtained raw material composition, it was found that it was in a paste state and the raw material powder could not be obtained. Therefore, the subsequent steps were not carried out.

[0089] Comparative Example 5 The raw material powder and the polyurethane-based composite material molded body were prepared in the same manner as in Comparative Example 1 except that the preheating step was carried out. The raw material powder and the polyurethane-based composite material molded body were evaluated in the same manner as in Example 1. The results are shown in Tables 1, Table 2, and Table 3.

[0090]

Table 1

[0091]

Table 2

[0092]

Table 3

Claims

1. A method for manufacturing a molded body of a polyurethane-based composite material in which a filler is dispersed in a matrix made of a polyurethane-based resin having a crosslinked structure, A radical-polymerizable polyurethane component (A) comprising a polyurethane oligomer having a radical-polymerizable group in the molecule, which has a number average molecular weight of 1,500 to 5,000 and liquefies at 40 to 80°C, a thermal radical polymerization initiator (B) having a half-life temperature: T １０ which is 90 to 150°C, and an inorganic filler (C), and a raw material powder preparation step of preparing a raw material powder composed of a powder composed of a raw material composition that liquefies at 40 to 80°C; After filling the raw material powder particles into a molding die, heating is performed at a temperature equal to or higher than the temperature at which the raw material composition becomes liquid and at a temperature equal to or lower than a temperature 10 °C lower than T of the thermal radical polymerization initiator to make the raw material powder particles into a paste state and hold them; and １０ a preheating step; and After the preliminary heating step, the raw material powder is heated to a temperature equal to or higher than a temperature 5 °C higher than T of the thermal radical polymerization initiator and lower than or equal to 200 °C to cause polymerization and curing in the main heating step; １０ The main heating step of heating and polymerizing and curing at a temperature equal to or higher than a temperature 5 °C higher than T of the thermal radical polymerization initiator and lower than or equal to 200 °C; including A method for manufacturing a molded body of a polyurethane-based composite material, characterized in that.

2. The raw material powder preparation step is A first raw material composition containing a radically polymerizable diol compound (a1), a thermal radical polymerization initiator (B), and an inorganic filler (C), and optionally containing a non-additive radically polymerizable monomer (D), and a diisocyanate compound (a2): an amount of 0.8 to 1.2 moles per 1 mole of the (a1), and mixing to cause polyaddition of the (a1) and the (a2), thereby generating the radically polymerizable polyurethane component (A). The polyaddition step, When the first raw material composition contains the (D), the amount of the (D) used in the total mass of the (A), the (a1), the (a2), and the (D) used in the polyaddition step is less than 5% by mass, The raw material powder is prepared from solid powder particles composed of a raw material composition that may contain the (D). The method for manufacturing a molded body of a polyurethane-based composite material according to claim 1.

3. The radically polymerizable diol compound (a1) is General formula (1): HO-L-(A) ｘ -(L) ｘ -OH {In the above general formula (1), when "-L-" represents an acryloyloxy group or a methacryloyloxy group as "-X-", -CH ２ -CH(CH ２ -X)- or -CH ２ -(CH-X)-CH ２ - A divalent group represented by In the above formula, "-A-" is -O-CH ２ -CH ２ -O- A divalent group represented by, and x is 0 or 1.} Consisting of a compound represented by The diisocyanate compound (a2) is General formula (2): O═C═N—CH ２ —R—CH ２ —N═C═O {In the above general formula (2), "-R-" is -CH(CH ３ )-CH ２ ―C(CH ３ ) ２ -CH ２ - or -C(CH ３ ) ２ -CH ２ -CH(CH ３ )-CH ２ - A group represented by or an m-phenylene group.} Consisting of a compound represented by The method for manufacturing a molded body of a polyurethane-based composite material according to claim 2.

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