Method for producing polyurethane-based composite material

Abstract

To produce, through cast polymerization of a raw material composition including a radical-polymerizable polyurethane component (A) having a number average molecular weight of 1500 to 20000, an excellent molded body composed of a polyurethane-based composite material in which inorganic particulate matter is dispersed in a matrix of a polyurethane-based resin having a crosslinked structure, without the need for heating at the time of casting.SOLUTION: A method in which a primary raw material composition that serves as a raw material of the raw material composition and contains a diol component is dried so that a moisture content falls within a predetermined range and is then mixed with a diisocyanate component, casting and defoaming being performed in a low-viscosity state at a stage where a low-molecular-weight radical-polymerizable polyurethane component (A') having a number average molecular weight of 500 to 1000 has been formed by polyaddition of part of the two components, after which polyaddition is carried out under a predetermined pressure to grow the (A') to obtain the raw material composition, and polymerization curing is subsequently performed.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a polyurethane composite material. [Background technology]

[0002] In dental treatment, a method using a dental CAD / CAM system has recently attracted attention as a method for fabricating dental prostheses such as inlays, onlays, crowns, bridges, and implant superstructures. This method fabricates a dental prosthesis by cutting a dental processing blank (also called a "mill blank") using a computer-controlled cutting machine based on three-dimensional coordinate data of the dental prosthesis designed by CAD, and can significantly reduce the time and effort required for fabrication compared to conventional methods.

[0003] A dental machining blank (mill blank) is a block- or disk-shaped molded body made of dental cutting material, which is used to make dental prostheses, and has a holding part that allows it to be attached to a cutting machine.Various materials such as glass ceramics, zirconia, titanium, and resin are used for dental cutting depending on the application and characteristics.

[0004] Resin-based materials for dental cutting are generally known to be hardened products of hardenable compositions containing inorganic fillers made of inorganic powders such as silica, polymerizable monomers such as (meth)acrylates, polymerization initiators, etc. However, conventional resin-based materials for dental cutting that are based on (meth)acrylic resins have limitations in their strength, and there is a demand for materials that can also be used for dental prostheses that require high strength, such as molar crowns and bridges.

[0005] To meet such demands, materials using polyurethane resins that have higher strength than (meth)acrylic resins have been proposed. For example, Patent Document 1 describes a polyurethane composite material that can be suitably used as a cutting processing material, in which a crosslinked structure formed by polymerization of radically polymerizable groups is introduced into the polyurethane resin, thereby making use of the high strength characteristic of polyurethane resins while improving its drawback of low water resistance, and a method for producing the same.

[0006] That is, Patent Document 1 describes that "a polyurethane composite material produced by using a raw material composition containing, as raw materials, a diol compound (A2) having one or more radically polymerizable groups; a diisocyanate compound (A1); 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 (A2) or the diisocyanate compound (A1); a radical polymerization initiator (C); and a filler (D), polyadding A2 and A1 to form a polyurethane component (A) having a molecular weight of 1500 to 5000, and then reacting the radically polymerizable groups contained in (A) with (B) to introduce a crosslinked structure" is uniform throughout, has excellent strength and water resistance, and is suitable as a material for dental cutting processing.

[0007] According to Patent Document 1, when the radical polymerizable group contained in (A) is reacted with (B), it is preferable to control the temperature so as not to exceed 150° C., and the 10-hour half-life temperature of the radical polymerization initiator: T 10 Temperature 10°C lower than the lower limit temperature (L) to T 10 It is particularly preferable to carry out the treatment at a temperature 25°C higher than the upper limit temperature H.

[0008] Furthermore, according to Patent Document 1, in a molding step for obtaining a polyurethane composite material molded article, a secondary raw material composition containing the polyurethane component (A), the polymerizable monomer (B); a thermal radical polymerization initiator (C); and a filler (D), which may contain unreacted diol compound (a1) and / or unreacted diisocyanate compound (a2), is heated at 40° C. or higher and at a temperature of 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 It is particularly preferred to carry out radical polymerization by heating to a temperature 25°C higher than the temperature at which the polymerization is carried out. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2023-077975 Summary of the Invention [Problem to be solved by the invention]

[0010] In Patent Document 1, a molding step must be provided in which the secondary raw material composition is heated and filled, but in that case, production requires waiting until the entire paste is heated uniformly, and further requires changing the heating conditions each time depending on differences in the paste properties due to molecular weight and structure.The present invention aims to provide a method for efficiently producing a good molded article made of the above-mentioned polyurethane composite material, omitting the heating step when filling the secondary raw material composition into a mold. [Means for solving the problem]

[0011] The present invention solves the above-mentioned problems, and a first aspect of the present invention is a method for producing a molded article made of a polyurethane-based composite material in which (C) is dispersed in a matrix made of a polyurethane-based resin having a crosslinked structure, by radically polymerizing in a mold a raw material composition which includes a radically polymerizable polyurethane component (A) made of a polyurethane having a radically polymerizable group, inorganic powder and particles (C), and a thermal radical polymerization initiator (D), and which may also include a non-polyaddition monomer (B) made of a polymerizable monomer which does not undergo a polyaddition reaction with either an alcohol compound or a diisocyanate compound, thereby crosslinking (A), the method comprising: a primary raw material composition preparation step of preparing a primary raw material composition comprising a composition comprising a radically polymerizable alcohol (a1) consisting of an alcohol compound having a radically polymerizable group in the molecule, 90 mol % or more of which is a diol having a radically polymerizable group in the molecule, and (C), and optionally containing (B) and / or (D), wherein the composition has a water content of (1) 15,000 ppm or less relative to the total mass of (a1) when the composition does not contain (B), and (2) 15,000 ppm or less relative to the total mass of (a1) and (B) when the composition contains (B); a first polyaddition step of mixing the primary raw material composition with a diisocyanate compound (a2) and, if necessary, the (B) and / or the (D) blended therein, to partially polyaddition-react the (a1) in the primary raw material composition with the (a2) to form a low-molecular-weight radically polymerizable polyurethane component (A') having a number-average molecular weight of 500 to 1000, and preparing a secondary raw material composition containing the (A'), unreacted (a1), unreacted (a2), (B), (C), and (D); a filling step of filling the secondary raw material composition into a mold; a second polyaddition step in which the secondary raw material composition filled in the mold is further subjected to a polyaddition reaction under a pressurized gas of 0.2 to 10 MPa to grow (A') and form a radically polymerizable polyurethane component having a number average molecular weight of 1,500 to 20,000, which becomes (A), thereby obtaining a raw material composition; and a polymerization and curing step of heating the raw material composition filled in the mold to carry out the radical polymerization; Including, In the first raw material composition preparation step and the first polyaddition step, the amounts of (B), (C), and (D) used are set so that (C) is 150 to 550 parts by mass and (D) is 0.01 to 2.0 parts by mass relative to 100 parts by mass of the total of (a1) and (a2), a degassing treatment of the composition between the end of the first polyaddition step and the start of the polymerization and curing step; and When the degassing treatment is carried out before the filling step, the number average molecular weight of (A') is kept not to exceed 1,000 until the filling step is started, and when the degassing treatment is carried out after the filling step, the number average molecular weight of (A') is kept not to exceed 1,000 until the degassing step is started. The present invention relates to a method for producing a polyurethane composite material molded article.

[0012] In the manufacturing method of the above embodiment (hereinafter also referred to as the "manufacturing method of the present invention"), the primary raw material composition preparation step includes a step of mixing the (a1) and the (C), and the (B) and / or the (D) blended as necessary, to obtain an untreated primary raw material composition having the same blending ratio of these components as the primary raw material composition and a higher water content than the primary raw material composition; and a step of mixing the untreated primary raw material composition in a temperature range of 0.1 to 6.0 (g / m 3 a dehydration step of contacting the primary raw material composition with an atmosphere maintained at 20°C (122°F) to dehydrate the primary raw material composition, thereby obtaining the primary raw material composition.

[0013] Furthermore, 50 to 100 mass % of the (a1) is glycerol monomethacrylate, The diisocyanate (a2) is a compound represented by the following general formula (1):

[0014] [ka]

[0015] [X in the above general formula (1) is a group represented by the following general formula (2)]

[0016] [ka]

[0017] {In the above general formula (2), each R1 is independently a hydrogen atom or a methyl group.} A compound represented by the formula: The non-polyaddition monomer (B) may be a monomer represented by the following general formula (3):

[0018] [ka]

[0019] {In the above general formula (3), R2's are each independently a hydrogen atom or a methyl group, R3's are a hydrogen atom, a methyl group, an ethyl group, or a propyl group, and Y's are an integer of 1 to 10.} It is preferable to use a compound represented by the formula:

[0020] Furthermore, it is preferable that the (a1) contains 50 to 900 mass ppm of alkali metal and / or alkaline earth metal based on the mass of the (a1). DETAILED DESCRIPTION OF THE INVENTION

[0021] 1. Overview of the manufacturing method of the present invention In Patent Document 1, the reason why heating is required at the filling and molding stage is due to the paste properties of the secondary raw material composition, specifically its high viscosity. To perform a method that does not require heating, it is necessary to achieve an appropriate paste property without heating, which was thought to be difficult to achieve after the polyaddition reaction, as in Patent Document 1. Therefore, a manufacturing method was investigated that employs degassing molding in the highly fluid state immediately after mixing the primary raw material composition with diisocyanate, and it was found that air bubbles were present in the resulting molded product.

[0022] The inventors believed that the bubbles were due to residual carbon dioxide gas generated when water contained in the primary raw material composition reacted with diisocyanate, and investigated the effect of the water content in the primary raw material composition. As a result, they found that while it was not possible to completely remove the water from the primary raw material composition by dehydration treatment, and it was not possible to completely suppress the generation of bubbles, it was possible to remove the bubbles by degassing treatment if the water content was reduced to a certain level or below and the raw material composition and polyaddition reaction were controlled to ensure the composition had sufficient fluidity (enough for casting), and then by completing the polyaddition reaction in a mold and then polymerizing and curing, a polyurethane composite material with excellent strength and no internal bubbles was obtained, which led to the completion of the present invention.

[0023] Thus, the manufacturing method of the present invention relates to a method for producing a molded article made of a polyurethane composite material described in Patent Document 1. The manufacturing method of the present invention is also similar to the method described in Patent Document 1 in that a raw material composition which includes a radically polymerizable polyurethane component made of polyurethane having a radically polymerizable group, inorganic powder and particles, and a thermal radical polymerization initiator and which may also include a non-polyaddition monomer made of a polymerizable monomer which does not undergo a polyaddition reaction with either an alcohol compound or a diisocyanate compound is radically polymerized in a mold.

[0024] In the method described in Patent Document 1, a "second raw material composition" corresponding to the raw material composition obtained in the double addition step in the manufacturing method of the present invention is cast into a mold and then polymerized and cured, whereas in the manufacturing method of the present invention, a composition (primary raw material composition) with a controlled composition and water content, prior to becoming the raw material composition (second raw material composition in Patent Document 1), is cast into a mold, and then degassing and polyaddition are performed to form the raw material composition (second raw material composition in Patent Document 1) in the mold, which is then polymerized and cured, thereby solving the above-mentioned problem.

[0025] Therefore, although the various raw materials and polymerization / curing steps used in the manufacturing method of the present invention are not particularly different from those described in Patent Document 1, these points will be included and each step of the manufacturing method of the present invention will be described in detail below. In this specification, unless otherwise specified, the notation "x to y" using the numerical values ​​x and y means "greater than or equal to x and less than or equal to y." In such notations, when a unit is added 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." Similarly, the term "(meth)acrylate" means both "acrylate" and "methacrylate," and the term "(meth)acryloyl" means both "acryloyl" and "methacryloyl."

[0026] 2. Raw material composition and its raw materials In the manufacturing method of the present invention, a raw material composition is radically polymerized in a mold to produce a molded article made of a polyurethane composite material. First, the raw material composition will be described. As described above, the raw material composition corresponds to the second raw material composition in Patent Document 1. In Patent Document 1, the radically polymerizable alcohol (a1) is a diol compound (hereinafter also referred to as "radical polymerizable diol compound"). However, in the manufacturing method of the present invention, other radically polymerizable alcohols such as monools or triols may be contained as long as the content of the radically polymerizable diol compound is 90 mol% or more, preferably 95 mol% or more.

[0027] The radically polymerizable polyurethane component (A) is basically formed by a quantitative (1 mole to 1 mole) polyaddition reaction between a radically polymerizable diol compound and a diisocyanate compound (a2). However, if the content of monool or triol is less than 10 mol %, preferably less than 5 mol %, only the partial structure of the resulting (A) changes slightly, and the physical properties of the polyurethane composite material molded product finally obtained are not significantly affected.

[0028] The ratio of the amount of the radically polymerizable alcohol (a1) to the amount of the diisocyanate compound (a2) used to form the radically polymerizable polyurethane component (A): [amount of diisocyanate compound (a2) used / amount of radically polymerizable alcohol (a1) used] is generally about 0.9 to 1.2, and preferably 0.95 to 1.1, expressed as a molar ratio.

[0029] The amount of the non-polyaddition monomer (B) used is preferably 2 to 30 parts by mass, more preferably 3 to 20 parts by mass, per 100 parts by mass of the total of the radical polymerizable alcohol (a1) and the diisocyanate compound (a2).

[0030] The amount of inorganic powder (C) used is 150 to 550 parts by mass, preferably 180 to 500 parts by mass, per 100 parts by mass of the total of the radical polymerizable alcohol (a1) and the diisocyanate compound (a2).

[0031] Furthermore, the amount of the thermal radical polymerization initiator (D) used is 0.01 to 2.0 parts by mass, and preferably 0.1 to 1.0 part by mass, per 100 parts by mass of the total of the radical polymerizable alcohol (a1) and the diisocyanate compound (a2).

[0032] Next, each raw material will be described.

[0033] (1) Alcohol compound (a1) having a radical polymerizable group in the molecule The radically polymerizable alcohol (a1) is a compound used as a raw material for forming the radically polymerizable polyurethane component (A), and is composed of an alcohol compound having a radically polymerizable group in the molecule, of which 90 mol % or more, preferably 95 to 100 mol %, is a radically polymerizable diol. In the production method of the present invention, the low-molecular-weight radically polymerizable polyurethane component (A') is formed by partial polyaddition with the diisocyanate compound (a2) in the first polyaddition step, and the polyaddition is further carried out in the second polyaddition step to grow the component and form the radically polymerizable polyurethane component (A).

[0034] The radically polymerizable group present in at least one molecule of the radically polymerizable alcohol (a1) means a group having a radically polymerizable carbon-carbon double bond, such as a vinyl group, a (meth)acrylate group, or a styryl group.

[0035] As the radical polymerizable group diol in the radical polymerizable alcohol (a1), any diol compound having at least one radical polymerizable group in the molecule can be used without particular limitation, and as the compound other than the radical polymerizable group diol, any monol having at least one radical polymerizable group in the molecule or a compound having three or more hydroxy groups in the molecule can be used without particular limitation. These can be used alone or in combination of different types.

[0036] The radically polymerizable alcohol (a1) preferably has 1 to 3 hydroxy groups, because this makes it easier to form a low-molecular-weight radically polymerizable polyurethane component (A') by partial polyaddition in the first polyaddition step, and then grow the (A') in the second addition step to form a radically polymerizable polyurethane component (A) having a number-average molecular weight of 1,500 to 20,000.

[0037] Specific examples of compounds that can be suitably used as the radical polymerizable group diol include trimethylolpropane mono(meth)acrylate, glycerol mono(meth)acrylate, erythritol di(meth)acrylate, pentaerythritol di(meth)acrylate, etc. Specific examples of compounds that can be suitably used as the radical polymerizable alcohol (a1) other than the radical polymerizable group diol include ethylene glycol mono(meth)acrylate, glycerol di(meth)acrylate, hydroxypropyl (meth)acrylate, erythritol mono(meth)acrylate, etc.

[0038] (2) Diisocyanate compound (a2) Diisocyanate compound (a2) is a compound having two isocyanate groups (—N═C═O groups) per molecule, and as described above, forms low-molecular-weight radically polymerizable polyurethane component (A′) and radically polymerizable polyurethane component (A) by polyaddition with radically polymerizable alcohol (a1). In the first polyaddition step, a partial polyaddition reaction is performed to form low-molecular-weight radically polymerizable polyurethane component (A′), and then in the second polyaddition step, this (A′) is propagated to form radically polymerizable polyurethane component (A) having a number-average molecular weight of 1,500 to 20,000. Furthermore, from the viewpoints of the fluidity of the resulting secondary raw material composition and the strength of the resulting polyurethane composite material, it is preferable to use a compound represented by the following general formula (1) having a phenyl group or cyclohexyl group in the molecule as diisocyanate compound (a2).

[0039] [ka]

[0040] Here, X in the above general formula (1) is any divalent group represented by the following general formula (2).

[0041] [ka]

[0042] In the general formula (2), R1's are each independently a hydrogen atom or a methyl group.

[0043] Specific examples of compounds represented by the above general formula that can be suitably used as the diisocyanate compound (a2) in the present invention include 1,3-bis(2-isocyanato-2-propyl)benzene, m-xylylene diisocyanate, p-xylylene diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, and 1,4-diisocyanatocyclohexane.

[0044] (3) Non-polyaddition monomer (B) The non-polyaddition monomer (B), which is used optionally, is a compound that has at least one radically polymerizable group in the molecule and does not undergo a polyaddition reaction with either the radically polymerizable alcohol (a1) or the diisocyanate (a2), i.e., it does not have any of the following groups in the molecule: hydroxyl group, amino group, carboxy group, isocyanate group, epoxy group, or mercapto group.

[0045] From the viewpoint of ease of crosslinking, the number of radically polymerizable groups contained in the molecule is preferably 2 to 6, and more preferably 2 to 4. By making the number of radically polymerizable groups 2 or more, the crosslink density can be increased, making it easier to obtain a cured product with sufficient strength. Furthermore, by making the number of radically polymerizable groups 6 or less, it becomes easier to suppress shrinkage during curing. Furthermore, it is preferable that the non-polyaddition monomer (B) is liquid at room temperature (i.e., 25°C).

[0046] The non-polyaddition monomer (B) preferably has a viscosity at room temperature in the range of 1 mPa·s to 1000 mPa·s, particularly in the range of 1 mPa·s to 100 mPa·s.

[0047] As the non-polyaddition monomer (B), it is preferable to use a compound represented by the following general formula (3), from the viewpoint of facilitating high-density crosslinking of the polyurethane component (A).

[0048] [ka]

[0049] In the general formula (3), R2's are each independently a hydrogen atom or a methyl group; R3's are a hydrogen atom, a methyl group, an ethyl group, or a propyl group; and Y's are an integer of 1 to 10, preferably an integer of 1 to 3.

[0050] Examples of compounds that can be particularly suitably used as the non-polyaddition monomer (B) include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and dipentaerythritol hexatri(meth)acrylate.

[0051] The amount of the non-polyaddition monomer (B) used is preferably 2 to 30 parts by mass, and more preferably 3 to 20 parts by mass, per 100 parts by mass of the total of the radically polymerizable alcohol (a1) and the diisocyanate compound (a2). By blending the non-polyaddition monomer (B) in the above-mentioned preferred range, the crosslink density can be increased, making it easier to obtain a polyurethane composite material with high strength.

[0052] (4) Inorganic powder (C) The inorganic powder and particle (C) is dispersed in the polyurethane resin matrix and is composited with the polyurethane resin matrix, thereby improving the physical properties such as mechanical strength, abrasion resistance, and water resistance of the polyurethane composite material.

[0053] Suitable inorganic powders and particles (C) are those composed of particles of inorganic substances such as silica, alumina, titania, zirconia, or composite oxides thereof, or glass. Specific examples of such inorganic powders and particles (C) include spherical particles and irregularly shaped particles (not having a specific shape, such as crushed particles) composed of amorphous silica, silica-zirconia, silica-titania, silica-titania-zirconia, quartz, alumina, and the like. When the polyurethane composite material produced by the production method of the present invention is used as a dental material, the inorganic powder and particles (C) are preferably composed of silica, titania, zirconia, or composite oxides thereof, with silica or composite oxides thereof being particularly preferred. These inorganic powders and particles (C) are unlikely to dissolve in the oral cavity, and the refractive index difference with the polyurethane resin matrix can be easily adjusted, making it easy to control transparency and aesthetics.

[0054] The shape of the particles constituting the powder to be the inorganic powder (C) is not particularly limited and can be appropriately selected depending on the intended use of the polyurethane composite material. For example, from the viewpoint of obtaining a polyurethane composite material that is particularly excellent in abrasion resistance, surface smoothness, and gloss durability, it is preferable that the particles have a (nearly) spherical shape.

[0055] The average particle size of the inorganic powder and granules (C) 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 a plurality of powder and granules with different average particle sizes, since this facilitates increasing the content of the inorganic powder and granules (C) in the polyurethane composite material. Specifically, it is preferable to combine powder and granules having an average particle size of 0.001 μm to 0.1 μm with powder and granules having an average particle size of 0.1 μm to 100 μm, and it is more preferable to combine powder and granules having an average particle size of 0.01 μm to 0.1 μm with powder and granules having an average particle size of 0.1 μm to 10 μm.

[0056] The above-mentioned average particle diameter means the average particle diameter determined by image analysis using a scanning electron microscope (SEM) image, and is obtained by observing a powder sample with an SEM at a magnification of 5,000 to 100,000 times so that 100 or more spherical particles whose overall shape can be confirmed are included in the field of view. The maximum diameter (nm) of each of 30 or more arbitrarily selected particles is measured based on the image (or photograph), and the sum is divided by the number: n (a natural number ≧30). In other words, the maximum diameter of each particle is expressed as x i (i is a natural number from 1 to n), and the average particle size is x AV When expressed as x AV =(Σx i ) / n.

[0057] The inorganic powder and particle (C) is preferably surface-treated to improve compatibility with the polyurethane resin matrix and to improve the mechanical strength and water resistance of the polyurethane composite material.

[0058] The amount of inorganic powder (C) used may be determined appropriately depending on the physical properties, such as the strength, of the desired polyurethane composite material. It is generally 150 to 550 parts by mass, preferably 180 to 500 parts by mass, per 100 parts by mass of the total of the radically polymerizable alcohol (a1) and the diisocyanate compound (a2). If the amount used is below the lower limit, it tends to be very difficult to obtain a polyurethane composite molded product with high strength. If the amount used is above the upper limit, it tends to be very difficult to obtain a polyurethane composite material with a uniform crosslinked structure. When the amount of inorganic powder (C) used is expressed in mass % (hereinafter sometimes simply referred to as "filling rate") based on the mass of the raw material composition, it is preferably 60 to 80% by mass, more preferably 65 to 75% by mass. Furthermore, when a polyurethane composite material produced by the method for producing a polyurethane composite material according to this embodiment is used as a dental cutting material, the filling rate is preferably 65 to 75% by mass.

[0059] (5) Thermal radical polymerization initiator (D) The thermal radical polymerization initiator (D) has the function of initiating a radical polymerization reaction in the polymerization and curing step, and reacts and bonds the radical polymerizable groups of the radically polymerizable polyurethane component (A) with the radical polymerizable groups of the non-polyaddition monomer (B), if present, thereby polymerizing and curing the raw material composition and forming crosslinking points in the polyurethane resin that serves as the matrix.

[0060] From the viewpoint of ease of handling and stability, the 10-hour half-life temperature of the thermal radical polymerization initiator (D): T 10 The 10-hour half-life temperature: T is preferably in the range of 40°C to 150°C, and more preferably in the range of 70°C to 130°C. 10 This is the temperature at which the amount of thermal polymerization initiator present decreases to half of the initial amount after 10 hours from the initial time, and is used as an index of the reactivity of the thermal polymerization initiator.

[0061] Specific examples of the thermal radical polymerization initiator (D) that can be suitably used include t-butyl peroxylaurate (T 10 =98℃) and dicumyl peroxide (T 10 =116°C), di-t-butylperoxyisopropylbenzene (T 10 =119°C), t-butylcumyl peroxide (T 10 =120°C), peroxide initiators such as 2,2'-azobis(N-butyl-2-methylpropionamide) (T 10 =110°C) and 2,2'-azobis(2,4,4-trimethylpentane) (T 10 =110°C) and azo-based initiators. These thermal polymerization initiators may be used alone or in combination of two or more.

[0062] The amount of the thermal radical polymerization initiator (D) used is 0.01 to 2.0 parts by mass, preferably 0.1 to 1.0 part by mass, per 100 parts by mass of the total of the radical polymerizable alcohol (a1) and the diisocyanate compound (a2).

[0063] (6) Other ingredients (6-1) Alkali metal compounds, alkaline earth metal compounds The inventors' investigations revealed that when glycerol monomethacrylate is used as the radically polymerizable alcohol (a1) in the first polyaddition step for preparing the secondary raw material composition, the change in viscosity over time after mixing the primary raw material composition with the diisocyanate compound (a2) and the optional (D) varies depending on the type (grade) of glycerol monomethacrylate used, and the viscosity rises rapidly, sometimes preventing sufficient operation time (hereinafter also referred to as pot life). Therefore, the inventors analyzed glycerol monomethacrylate to examine the relationship between the analytical results and the change in viscosity over time. They found that the change in viscosity over time is gradual when the amount of sodium contained as an impurity is within a certain range. The sodium is derived from sodium ions eluted from the sodium compound, and it has been found that the sodium ions have the function of regulating the change in viscosity over time (and thus the reaction rate of the primary polyaddition) when the primary raw material composition is mixed with the diisocyanate to prepare the secondary raw material composition, and preventing the number-average molecular weight of the low-molecular-weight radically polymerizable polyurethane component (A') from exceeding the upper limit of 1000 and becoming too high in viscosity before the filling step is completed. Furthermore, as a result of extensive investigation, it has been found that the same effect is also achieved when alkali metal compounds or alkaline earth metal compounds other than sodium are added.

[0064] Although alkali metals and alkaline earth metals may be contained in the inorganic powder or particle (C) in the form of oxides, the amount of alkali metal ions and alkaline earth metal ions having the above-mentioned functions that are eluted and diffused from the oxides is extremely small. Also, the amount of alkali metal ions and alkaline earth metal ions contained in the non-polyaddition monomer (B) is extremely small.

[0065] For these reasons and because viscosity changes after mixing can be suppressed and production stability can be ensured, it is preferable to use a radically polymerizable alcohol (a1) containing 50 to 900 ppm by mass of alkali metal and / or alkaline earth metal, based on the mass of (a1). If the amount of alkali metal and alkaline earth metal is below the above range, the effect of suppressing viscosity changes is small, but if it exceeds the above range, the viscosity increases and it tends to be difficult to obtain a molded product with high strength.

[0066] Therefore, the amount of alkali metal and alkaline earth metal contained in the radical polymerizable alcohol (a1) to be used should be confirmed in advance by analysis (for example, ICP-OES measurement, etc.), and if the amount is below the lower limit of the above range, a required amount of alkali metal and / or alkaline earth metal compound serving as a supply source of the alkali metal and / or alkaline earth metal should be added. Note that it is rare for the amount of alkali metal and alkaline earth metal contained in the radical polymerizable alcohol (a1) to exceed the upper limit, but in that case, a radical polymerizable alcohol (a1) with a low content of alkali metal and alkaline earth metal should be used, or the alcohol should be diluted with this.

[0067] Examples of suitable alkali metal compounds and alkaline earth metal compounds include sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, sodium methacrylate, potassium methacrylate, and calcium methacrylate. When adding these compounds, it is preferable to premix them with the primary raw material composition that does not contain the radically polymerizable alcohol (a1) or the inorganic powder or particle (C) from the viewpoint of solubility and the ability to confirm that they are uniformly dispersed. As for the addition method, they may be added as a single substance or as an aqueous solution.

[0068] (6-2) Components other than alkali metal compounds and alkaline earth metal compounds The primary raw material composition or raw material composition may also contain various additives other than alkali metal compounds and alkaline earth metal compounds. Examples of such additives include polymerization inhibitors, fluorescent agents, ultraviolet absorbers, antioxidants, pigments, antibacterial agents, and X-ray contrast agents. The amounts of these additives added may be determined appropriately depending on the desired purpose.

[0069] 3. Primary raw material composition preparation process In the primary raw material composition preparation step, a primary raw material composition is prepared, which comprises a radically polymerizable alcohol (a1) and the inorganic powder and granules (C), optionally including a non-polyaddition monomer (B) and / or a thermal radical polymerization initiator (D). The primary raw material composition contains a water content of (1) 15,000 ppm or less based on the total mass of (a1) if the composition does not contain (B), or (2) 15,000 ppm or less based on the total mass of (a1) and (B) if the composition contains (B). The water content of the primary raw material composition, expressed as the above standard, is based on the total mass of the liquid components, and is therefore hereinafter referred to as the liquid component-based water content (of the primary raw material composition). The liquid component-based water content can be determined based on the actual water content measured for the primary raw material composition by Karl Fischer analysis.

[0070] The primary raw material composition includes a mixing step of mixing the radically polymerizable alcohol (a1), the inorganic powder and particle (C), and optionally the non-polyaddition monomer (B) and / or the thermal radical polymerization initiator (D), and a moisture content confirmation step of checking the moisture content of the mixture obtained in the mixing step. If the moisture content meets the above conditions, the resulting mixture can be used as the primary raw material composition as is, but since the moisture content usually exceeds the above upper limit (15,000 ppm), it is subjected to a drying step (dehydration step) before being used as the primary raw material composition.

[0071] In the mixing step, the blending of (B) and (D) is optional and may be performed during the first polyaddition step. Alternatively, all of these components may be mixed at once, or a mixture of some of the components may be prepared and then the remaining components added and mixed. The mixing method for the components is not particularly limited, and methods using a magnetic stirrer, a mortar and pestle mixer, a planetary mixer, a trimix, a centrifugal mixer, or the like may be used as appropriate. Furthermore, because it is easier to uniformly disperse the inorganic powder and granules (C), it is preferable to first mix the alcohol compound (a1) having a radically polymerizable group in its molecule and the optional non-polyaddition monomer (B) to prepare a mixed composition, and then add and mix the inorganic powder and granules (C) to this mixed composition. Furthermore, it is preferable to add a thermal radical polymerization initiator (D) and other additives to facilitate suppression of side reactions and ease of dispersion. In the mixing step, a catalyst that promotes the polyaddition reaction may also be included as an additional additive, if necessary. Examples of catalysts that promote the polyaddition reaction include tin octoate, dibutyltin diacetate, etc. It is preferable to avoid contamination of moisture from the environment during the mixing step.

[0072] The moisture content in the moisture content confirmation step can be confirmed by Karl Fischer measurement. When measuring the moisture content, the primary raw material composition may be used as a measurement sample as is, or the measurement sample may be a sample obtained by diluting the primary raw material composition with an inert solvent (e.g., a dehydrating solvent) having a low moisture content and a known amount. In this case, the liquid component reference moisture content (ppm by mass): M (of the primary raw material composition) is calculated by dividing the measured moisture content (ppm by mass): M s , mass of the measurement sample: W s , the moisture content of the primary raw material composition in the measurement sample: M p , Water content of dilution solvent (mass ppm): M a , the mass of the primary raw material composition in the measurement sample: W p , the mass of the diluent in the measurement sample: W a and the filling rate of inorganic powder (C) in the primary raw material composition: C p (mass%), Ms ·W s =M s ·(W a +W p )=(M a ·W a )+(M p ·W p ) and M=M p ×{100 / (100-C p )}, so The following formula (1): M=100{M s ·(W p +W a )-(M a ·W a )} / {W p ·(100-C p )} It can be calculated as follows.

[0073] In addition, the filling rate C p The formula: filling rate C is obtained by assuming that the content (parts by mass) of the inorganic powder and granules (C) contained in the primary raw material composition is [C] and the content of components other than the inorganic powder and granules (C) contained in the primary raw material composition is [SUM]. p = {[C] / ([C]+[SUM])}×100.

[0074] The drying step (dehydration step) can be carried out by bringing the mixture (undried primary raw material composition) obtained in the mixing step into contact with an atmosphere in a low humidity environment or a low humidity air flow environment. In order to efficiently carry out drying and shorten the drying step time, it is preferable to carry out drying in a low humidity atmosphere under normal pressure, specifically, an absolute humidity of 0.1 to 6.0 (g / m 3 ), preferably 0.1 (g / m 3 )~4.0(g / m 3It is more preferable to obtain the primary raw material composition by dehydrating it by contacting it with an atmosphere maintained at 20°C (24°F). When a thermal polymerization initiator is contained, the temperature for adjusting the water content is preferably 80°C or lower from the viewpoint of preventing unintended radical polymerization from proceeding. Since there is no benefit to cooling, it is more preferable to perform the adjustment at room temperature (for example, normal room temperature of 15 to 35°C) to 80°C. In this case, since the dehydration efficiency increases as the contact area with the atmosphere increases, it is preferable to increase the contact area by stirring or the like rather than placing the undried primary raw material composition in a shallow container and leaving it to stand in the atmosphere.

[0075] The drying time depends on the amount of water contained in the undried primary raw material composition, but is usually 20 to 200 hours, preferably 30 to 100 hours, when drying is performed without stirring, and is usually 1 to 40 hours, preferably 2 to 10 hours, when drying is performed with stirring.

[0076] In the production method of the present invention, by setting the liquid component standard water content to 15,000 ppm or less, it is possible to prevent carbon dioxide gas, which is generated by the reaction of the remaining water with the diisocyanate compound (a2) in the subsequent steps, from remaining in the finally obtained cured product.

[0077] 4.First double addition process In the first polyaddition step, the primary raw material composition is mixed with a diisocyanate compound (a2) and, if necessary, the (B) and / or the (D) blended therein, to partially polyaddition-react (a1) and (a2) in the primary raw material composition to form a low-molecular-weight radically polymerizable polyurethane component (A') having a number-average molecular weight of 500 to 1000, thereby preparing a secondary raw material composition containing (A'), unreacted (a1), unreacted (a2), (B), (C), and (D). Here, the number-average molecular weight of the low-molecular-weight radically polymerizable polyurethane component (A') refers to the polystyrene-equivalent number-average molecular weight determined by gel permeation chromatography (GPC). The number-average molecular weight of (A') in the secondary raw material composition can be determined by adding a solvent such as tetrahydrofuran (THF) or dimethyl sulfoxide (DMSO) to the secondary raw material composition as needed, removing insoluble components such as the inorganic powder (C) by filtration or centrifugation, and then performing GPC analysis on the resulting solution. If the number-average molecular weight of the resulting (A') is below 500, depending on the water content of the liquid components, water that was not completely removed in the dehydration step and remained in the primary raw material composition may react with unreacted diisocyanate compound (a2) in the second addition step, generating carbon dioxide at a level that cannot be removed even by degassing, and this carbon dioxide may remain in the cured product. Furthermore, if the number average molecular weight of the secondary raw material composition exceeds 1000, the viscosity increases and air bubbles cannot be completely removed in the degassing step, making it difficult to prevent air bubbles from remaining in the molded product.

[0078] The method for mixing the components in the first polyaddition step is not particularly limited, and methods using a magnetic stirrer, a mortar and pestle mixer, a planetary mixer, a trimix, a centrifugal mixer, or the like are appropriately used. If moisture is mixed in when mixing the components, the effect of removing moisture in the dehydration step will be lost, and carbon dioxide gas generated by the reaction of the mixed moisture with the diisocyanate compound (a2) will remain in the final cured product. Therefore, mixing is preferably carried out under vacuum, in an enclosed space, or in a low-humidity space. Since prolonged mixing under vacuum conditions may cause unintended radical polymerization to proceed, it is more preferable to carry out mixing in an enclosed space or a low-humidity space. The humidity in the low-humidity space referred to here is an absolute humidity of 0.1 to 6.0 (g / m), the same as that in the dehydration step. 3 ), and 0.1 (g / m 3 )~4.0(g / m 3) is more preferable. The temperature at which the components are mixed (i.e., the reaction temperature of the polyaddition reaction) is preferably 0 to 50°C, more preferably 10 to 30°C, and most preferably around room temperature (e.g., 25°C) because this makes it easier to control the number-average molecular weight of (A'). If the mixing temperature is below 0°C, the viscosity of the components other than the inorganic powder and particle (C) increases, making mixing difficult. On the other hand, if the temperature exceeds 50°C, the polyaddition reaction proceeds rapidly, causing the viscosity of the secondary raw material composition to increase in a short period of time. This limits the time available for defoaming within the preferred viscosity range in the defoaming step, reducing the amount that can be produced at one time and lowering productivity.

[0079] In the first polyaddition step, the number-average molecular weight of the resulting low-molecular-weight radically polymerizable polyurethane component (A') must be within the range of 500 to 1,000. The number-average molecular weight can be controlled by the temperature and time of the polyaddition reaction, as well as the sodium content. Therefore, after all components begin to coexist through mixing, portions of the mixture are sampled over time and analyzed by GPC. When the number-average molecular weight of (A') exceeds 500, the reaction rate can be reduced by lowering the reaction temperature, essentially stopping the reaction, thereby keeping the number-average molecular weight within the above range. Furthermore, since the rate of increase in number-average molecular weight increases over time at a constant temperature, it is necessary to previously examine the change in number-average molecular weight over time at a predetermined temperature and ensure that the number-average molecular weight of (A') does not exceed 1,000 (1) until the start of the filling step if the degassing treatment is performed before the filling step, or (2) until the start of the degassing step if the degassing treatment is performed after the filling step.

[0080] For reasons of ease of filling in the filling step and efficient degassing in the degassing step, the viscosity of the secondary raw material composition at 25°C is preferably 5 to 1000 Pa·s, and more preferably 10 to 400 Pa·s. By controlling the viscosity of the secondary raw material composition within this range, it becomes easier to remove air bubbles in the degassing step and to prevent air bubbles from being entrained in the filling step, making it easier to suppress air bubbles remaining in the molded product.

[0081] Here, the viscosity of the secondary raw material composition can be determined by adjusting the temperature of the sample stage of a rotational viscometer using parallel plates to 25°C, pressing the secondary raw material composition between parallel plates of φ20 mm so that the paste thickness is 1 mm, leaving it to stand for 1 minute, and then measuring the shear rate by scanning at 1 rotation per minute.

[0082] In the first polyaddition step, a portion of the radically polymerizable alcohol (a1) and a portion of the diisocyanate (a2) undergo a nearly quantitative polyaddition reaction to form the (A') component. In the second polyaddition step described below, the unreacted radically polymerizable alcohol (a1) and the unreacted diisocyanate (a2) undergo a (quantitative) polyaddition reaction to grow the (A') component, producing the radically polymerizable polyurethane component (A). Therefore, the amount of diisocyanate (a2) used in the first polyaddition step is determined based on the total number of moles of hydroxyl groups in the radically polymerizable diol (a1): T OH The total number of moles of isocyanate groups contained in the diisocyanate (a2) relative to T NCO Ratio of:T NCO / T OH T so that NCO / T OH = 0.8 to 1.2, preferably 0.9 to 1.1. Note that even if unreacted (a1) or diisocyanate (a2) remains, it is permissible as long as the amount is small.

[0083] 5.Filling process In the filling step, the secondary raw material composition is filled into the mold. The filling step may be performed before or after the degassing step described below. The temperature when filling the secondary raw material composition is preferably 0 to 50°C, more preferably 10 to 30°C. If the temperature when filling is below 0°C, the viscosity of the secondary raw material composition increases, resulting in a slower filling speed and lower productivity. If the temperature exceeds 50°C, the reaction between the remaining moisture and the diisocyanate compound (a2) proceeds rapidly, causing foaming and making filling defects more likely. In addition, the viscosity increases in a short period of time, resulting in a slower filling speed and lower productivity. The filling of the secondary raw material composition in the filling step can be performed by a method such as extrusion or pouring, which can be appropriately selected depending on the fluidity of the raw material. The filling may be performed automatically using a filling machine or manually using a syringe or the like.

[0084] While the material of the mold used in the filling step is not particularly limited, a resin mold is preferred because it allows for inexpensive production of a molded product of the desired shape. The type of resin is not particularly limited as long as it can withstand the temperatures and pressures encountered during radical polymerization. Examples include thermoplastic resins such as polypropylene, polyacetal, polytetrafluoroethylene, and polycarbonate; thermosetting resins such as polyimide, polyamide, phenol, and melamine resins; and various engineering plastics such as PEEK, PTFE, PEK, and PEKK. Considering cost and ease of handling during molding, general-purpose thermoplastic resins such as polypropylene and high-density polyethylene are preferred. These resins can be selected based on factors such as ease of handling during manufacturing and ease of pouring a fluid paste. The thickness of the resin mold is preferably 0.5 to 20 mm, more preferably 1 to 5 mm. If the thickness is thinner than this range, the mold will deform when filled with the secondary raw material composition, making it difficult to obtain a cured product of the same shape. If the thickness is greater than the above range, an extra space is required during filling and polymerization / curing steps, resulting in a decrease in productivity.

[0085] 6. Defoaming process In the degassing step, the secondary raw material composition is degassed between the end of the first polyaddition step and the start of the polymerization / curing step. The degassing step may be performed before or after the filling step described above. Any known degassing method can be used without limitation. However, centrifugal degassing using a centrifuge or a rotation-revolution agitator / degasser, or pressurized degassing using a CIP (cold isostatic press) or a WIP (warm isostatic press) are preferred because they allow for efficient degassing. Vacuum centrifugal degassing, in which the centrifugal degassing is performed under vacuum, is more preferred. Furthermore, vacuum rotation-revolution agitator / degassing, in which the composition is rotated, is more preferred because it makes it easier to suppress component separation due to centrifugation.

[0086] The temperature in the degassing step is preferably 0 to 50°C, and more preferably 10 to 40°C. If the temperature during filling is below 0°C, the viscosity of the secondary raw material composition increases, making degassing failure more likely. On the other hand, if the temperature exceeds 50°C, the polyaddition reaction proceeds rapidly, causing the viscosity of the secondary raw material composition to increase in a short period of time, limiting the time available for degassing treatment, reducing the amount that can be produced at one time, and decreasing productivity.

[0087] The degassing step is preferably carried out by placing the mold-filled secondary raw material composition obtained after the filling step in a container, fixing it, and using a vacuum-equipped planetary centrifugal stirring and degassing machine.

[0088] 7.Second addition process In the second polyaddition step, the secondary raw material composition filled in the mold is subjected to a further polyaddition reaction under a pressurized gas of 0.2 to 10 MPa to grow (A') and form a radically polymerizable polyurethane component having a number average molecular weight of 1,500 to 20,000, which becomes (A), and is used as a raw material composition.

[0089] Here, the number average molecular weight of the radical polymerizable polyurethane component (A) is determined by GPC measurement, similar to the number average molecular weight of (A') above. By adjusting the number average molecular weight of the radical polymerizable polyurethane component (A) to 1,500 or more, a polyurethane composite material with sufficient strength can be obtained. Furthermore, according to the studies of the present inventors, it is substantially impossible or extremely difficult to obtain a radical polymerizable polyurethane component (A) with a number average molecular weight exceeding 20,000.

[0090] The polyaddition reaction in the second polyaddition step is carried out at a temperature higher than that in the first polyaddition step until at least one of the alcohol compound (a1) having a radical polymerizable group and the diisocyanate (a2) is substantially consumed by the polyaddition reaction. The temperature of the polyaddition reaction in the second polyaddition step is any temperature higher than that in the first polyaddition step, preferably 35 to 80°C, more preferably 40 to 70°C. If the temperature is lower than 35°C, the polyaddition reaction takes time to complete, resulting in reduced productivity. If the temperature exceeds the above range, the polyaddition reaction proceeds too rapidly, making cracks due to polymerization shrinkage more likely to occur. The reaction time varies depending on the reaction temperature. For example, if the reaction temperature is 30°C or higher but lower than 50°C, the reaction time is preferably 60 hours or longer, more preferably 72 hours or longer. If the heating temperature is 50°C or higher but lower than 80°C, the reaction time is preferably 30 hours or longer, more preferably 36 hours or longer.

[0091] Although a small amount of radical polymerization reaction inevitably occurs in the second double addition step, the thermal radical polymerization initiator (D) used must be within the range of T 10 is preferably higher than the reaction temperature of the second addition step.

[0092] The pressure of the pressurized gas used in the second addition step is in the range of 0.2 to 10 MPa, more preferably 0.25 to 5.0 MPa. By carrying out the polyaddition reaction under a pressure of 0.2 MPa or higher, it is possible to suppress the formation of bubbles derived from carbon dioxide gas, which are generated when the residual moisture in the secondary raw material composition reacts with the diisocyanate compound (a2) during the growth of the low-molecular-weight radically polymerizable polyurethane component (A') to form the radically polymerizable polyurethane component (A). Furthermore, by carrying out the polyaddition reaction under a pressure of 10 MPa or lower, it is possible to prevent the unexpected progression of radical polymerization and obtain a polyurethane composite material with sufficient strength. From the perspective of ease of operation, the gas used is preferably air or nitrogen. Furthermore, if moisture is introduced during the second addition step, the effect of removing moisture in the dehydration step is negated, and carbon dioxide gas generated by the reaction of the introduced moisture with the diisocyanate compound (a2) is likely to remain in the final cured product. Therefore, the second addition step, like the first polyaddition step, is preferably carried out in an enclosed or low-humidity space. The polyaddition reaction can be carried out under pressurized gas by placing the secondary raw material composition filled in a mold in a pressure-resistant container, supplying pressurized gas from a compressor or cylinder, and maintaining the temperature at a desired level using an incubator or a blower dryer, or by placing the secondary raw material composition filled in a mold in an automatic heating and pressure treatment device and maintaining the temperature at a desired level while applying pressure.

[0093] 8.Polymerization / curing process In the polymerization and curing step, the raw material composition filled in the mold is heated to carry out radical polymerization, thereby crosslinking the radically polymerizable polyurethane component (A) and obtaining the polyurethane composite material. Since the radical polymerization generates heat due to reaction heat, it is preferable to control the heating temperature (curing temperature). In this case, it is preferable to control the heating temperature so that it does not exceed 150°C, and the 10-hour half-life temperature (T) of the thermal radical polymerization initiator is not exceeded. 10 (℃) -10℃~+25℃, i.e. T 10 Temperature 10°C lower than the lower limit temperature (L) to T 10It is particularly preferable to carry out the radical polymerization at a temperature (upper limit temperature H) 25°C higher than the lower limit temperature L. Setting the heating temperature at or above the lower limit temperature L not only sufficiently increases the radical polymerization rate but also facilitates the prevention of unintended coloration of the cured product. Setting the heating temperature at or below the upper limit temperature H prevents excessive consumption of radically polymerizable groups present in the reaction system and suppresses the effects of polymerization shrinkage due to rapid radical polymerization. Controlling the heating temperature within the above-mentioned temperature range allows polymerization and curing to proceed at an industrially acceptable reaction rate and also suppresses the occurrence of distortion or cracks in the cured product due to rapid reaction progress. Furthermore, when radically polymerizing by heating, the raw material composition may be pressurized during radical polymerization to prevent the formation of voids in the cured product due to bubbles. There are no limitations on the pressurization method, and mechanical pressurization or pressurization with a gas such as nitrogen may be used. By carrying out the radical polymerization process in this manner, a molded product made of the polyurethane composite material of the present invention can be efficiently obtained. [Example]

[0094] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[0095] 1. Raw materials The components used in each of the examples and comparative examples and their abbreviations are shown below.

[0096] (1) Radically polymerizable alcohol compound (a1) Radical polymerizable diol GLM: glycerol monomethacrylate Radical polymerizable monool HEMA: Ethylene glycol monomethacrylate (2) Diisocyanate compound (a2) XDI: m-xylylene diisocyanate HXDI: 1,3-bis(isocyanatomethyl)cyclohexane (3) Non-polyaddition monomer (B) TEGDMA: Triethylene glycol dimethacrylate TMPTMA: Trimethylolpropane trimethacrylate DEGDMA: Diethylene glycol dimethacrylate DPEHTA: Dipentaerythritol hexatriacrylate (4) Inorganic powder (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) Thermal radical polymerization initiator (D) PBP: Di-t-butylperoxyisopropylbenzene (T 10 =119℃) DPO: Dicumyl peroxide (T 10 =116℃) (6) Metal compounds (alkali metal compounds or alkaline earth metal compounds) Na2CO3: Sodium carbonate NaOH: Sodium hydroxide Sodium methacrylate: Sodium methacrylate Calcium methacrylate: Calcium methacrylate K2CO3: Potassium carbonate 2. Manufacturing method for polyurethane composite molded body Examples of the manufacturing method of the present invention will be described below together with comparative examples.

[0097] Example 1 (1) Primary raw material composition preparation process First, a mixed composition was prepared by mixing the radically polymerizable alcohol compound (a1), which is a diol GLM (44.3 parts by mass), the monool HEMA (1.7 parts by mass), the non-polyaddition monomer (B) TEGDMA (18.3 parts by mass), and the thermal radical polymerization initiator (D) PBP (0.4 parts by mass). The sodium content of (a1) was confirmed in advance using the method described below. The GLM content in (a1) was 95 mol%. Next, fillers (C) F1 (221.3 parts by mass) and F2 (94.8 parts by mass) were added to this mixture composition and kneaded to prepare a wet primary raw material composition. The above operation was carried out in a room temperature (25°C) environment. The obtained undried primary raw material composition (10.0 g) was placed in an auto-dry desiccator, Drymax DMX-400 (manufactured by AS ONE) (temperature inside the desiccator: 25°C, humidity: 2%, absolute humidity: 0.5 (g / m 3 The mixture was placed in a container measuring 2 cm x 4 cm x 0.7 cm and left to stand for 96 hours to carry out a drying treatment (drying step), thereby preparing a primary raw material composition. Thereafter, the water content of the prepared primary raw material composition was evaluated by the method described below.

[0098] [Method for evaluating alkali metal and alkaline earth metal content] The alcohol compound (a1) used in the first raw material composition preparation step was diluted with a 1 wt% nitric acid-isopropanol (IPA) solution to prepare a measurement sample with a concentration of 1 wt%. The obtained measurement sample was analyzed using an inductively coupled plasma optical emission spectrometer (ICP-OES) CAP 6500 DUO (manufactured by Thermo Fisher Scientific), and the sodium content in the alcohol compound (a1) was found to be 5 ppm.

[0099] [Method for evaluating the moisture content of primary raw material composition] The resulting primary raw material composition was suspended in Aquamicron Dehydrating Solvent OLII (manufactured by Mitsubishi Chemical Corporation), a dehydrating solvent, to prepare a concentration of Aquamicron OLII / dried primary raw material composition = 1 g / g, which was used as a measurement sample. Next, the moisture content of the measurement sample and Aquamicron OLII was measured using an 870 Titrino Plus (volumetric KF moisture meter) (manufactured by Metrohm International Headquarters), a volumetric titration moisture measurement device, to obtain actual values ​​for each. The moisture content was then calculated using the respective measured values ​​using the above formula (1), and the moisture content in the primary raw material composition matrix component was found to be 7000 ppm.

[0100] The compositions and evaluation results of the primary raw material compositions are summarized in Table 1. Regarding the compositions, (a1), (B), and (D) are shown by the respective raw materials (abbreviations) and amounts used (numbers in parentheses: units are parts by mass), while (C) is shown by the amount used (units are parts by mass). Also, "↑" in the table means "same as above."

[0101] [Table 1]

[0102] (2) First polyaddition step, filling step and degassing step First addition process: In a glove box with the inside humidity reduced using a refrigerated air dryer RAX3J-SE (manufactured by Orion Machinery) (temperature 25°C, humidity 7% = absolute humidity 1.6 (g / m 3 )) To the primary raw material composition obtained in step (a), 54.0 parts by mass of XDI, a diisocyanate compound (a2), was added to a total of 46.0 parts by mass of (a1) so that the total of (a1) and (a2) was 100 parts by mass, and the mixture was kneaded for 0.25 hours and allowed to stand for 2.75 hours to obtain a secondary raw material composition. The number average molecular weight of the low molecular weight radically polymerizable polyurethane (A') in the obtained secondary raw material composition and the viscosity of the secondary raw material composition were then evaluated using the methods described below.

[0103] Filling step: Next, at 25°C, the obtained secondary raw material composition was filled into a Terumo syringe (manufactured by Terumo), and then injected into a polypropylene mold (length 14.5 mm × width 18 mm × height 60 mm (thickness 1.7 mm)) to obtain a molded filling of the secondary raw material composition.

[0104] Degassing step: At 25°C, the obtained mold filling of the secondary raw material composition was placed in a container and fixed, and a rotation-revolution degassing process (vacuum degree: 1.3 kPa, revolution speed: 1420 rpm, rotation speed: 284 rpm, processing time: 3 minutes, number of repetitions: 3 times) was carried out using a Kakuhunter (manufactured by Photo Chemical Co., Ltd.), a rotation-revolution stirring degassing machine with vacuum function, to obtain a degassed product of the secondary raw material composition.

[0105] [Method for evaluating the number average molecular weight of low molecular weight radically polymerizable polyurethane (A')] The number-average molecular weight of the low-molecular-weight radically polymerizable polyurethane component (A') from the resulting secondary raw material composition was evaluated as follows. Specifically, 1 g of the resulting secondary raw material composition was weighed into a screw cap bottle, and 1.75 ml of methanol and 1.75 ml of DMSO were added and stirred to obtain a DMSO solution. The resulting solution was centrifuged at 10,000 rpm in a centrifuge (manufactured by AS ONE Corporation) for 10 minutes. The supernatant obtained by centrifugation was then filtered through a membrane filter (pore size 20 μm, manufactured by ADVANTEC) to obtain a filtrate. The resulting filtrate was subjected to GPC measurement under the GPC measurement conditions shown below to determine the polystyrene-equivalent number-average molecular weight of the resulting low-molecular-weight radically polymerizable polyurethane component (A'). The resulting number-average molecular weight was 900.

[0106] 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).

[0107] [Method for evaluating viscosity of secondary raw material composition] The viscosity of the resulting secondary raw material composition was evaluated immediately before the degassing process. 0.7 g of the secondary raw material composition, which had been left stationary in the glove box for 3 hours after the start of kneading the primary raw material composition and diisocyanate compound (a2) in the first polyaddition process, was pressed into a parallel-plate rotational viscometer with the sample stage temperature adjusted to 25°C using a 20 mm diameter parallel plate to achieve a paste thickness of 1 mm. After leaving the composition stationary for 1 minute, the shear rate was scanned at 1 revolution per minute to measure the viscosity, which was 142 Pa s.

[0108] The conditions for the first polyaddition step and the evaluation results of the secondary raw material composition are summarized in Table 2.

[0109] [Table 2]

[0110] (3) Second addition process The degassed secondary raw material composition was molded with a pusher, placed in a pressure vessel, and heated at 60°C for 72 hours under nitrogen pressure (0.3 MPa) to allow polyaddition, yielding a raw material composition. The number average molecular weight of the radically polymerizable polyurethane component (A) in the resulting raw material composition was determined in the same manner as in the evaluation method for the number average molecular weight of the low-molecular-weight radically polymerizable polyurethane (A'), and was found to be 5,600.

[0111] (4) Polymerization / curing process The resulting raw material composition was placed in a mold and placed in a pressure vessel. Radical polymerization was carried out by heating at 120°C for 18 hours under nitrogen pressure (0.3 MPa). This resulted in a polyurethane composite molded product with the filler dispersed in the polyurethane resin matrix. The resulting polyurethane composite was evaluated for flexural strength, underwater flexural strength, water resistance, and the presence or absence of defects. The evaluation methods and results are shown below.

[0112] [Flexural strength BS d ] The resulting polyurethane composite (cured body) was cut using a mold (14.5 mm long x 18 mm wide x 60 mm high (1.7 mm thick)) with a low-speed diamond cutter (Buehler). Five rectangular prism-shaped test specimens (approximately 1.2 mm thick x 4.0 mm wide x 14.0 mm long) were then prepared by polishing with P2000 waterproof abrasive paper. Each test specimen was then subjected to a three-point bending test using an autograph (Shimadzu Corporation), and the bending load at the maximum point was measured. The bending strength (MPa): BS was calculated from the bending load at the maximum point (N): P, the distance between supports: S, the width (measured value, mm): W, and the thickness (measured value, mm): B, using the following formula: BS=3P·S / 2W·B 2 The bending strength BS was calculated based on the above. 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 321 MPa.

[0113] [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 the above formula. 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 302 MPa.

[0114] [Retention rate (water resistance)] The retention rate, which is an index showing the water resistance of the hardened body, is calculated using the following formula: Retention rate (%)=100×BS w / BS d In this example, the retention rate was 94%, confirming high water resistance.

[0115] [Presence or absence of bubbles] The appearance of the test pieces prepared in the [Flexural strength] column was visually evaluated to check for the presence or absence of air bubbles, and no remaining air bubbles were found.

[0116] Table 3 shows the pressurization conditions in the second addition step, the number average molecular weight of (A) in the raw material composition obtained in the step, and the evaluation results of the resulting polyurethane composite material.

[0117] [Table 3]

[0118] Examples 2 to 11 and 14 to 19 In the primary raw material composition preparation step, sodium carbonate was added to GLM so as to obtain the sodium amount shown in Table 2, and the amounts of raw materials used, the water content of the primary raw material composition, the humidity in the first polyaddition step, and the time from the start of mixing to the degassing step were changed as shown in Tables 1 and 2. The secondary raw material composition, raw material composition, and polyurethane composite material were evaluated in the same manner as in Example 1. The results are shown in Table 3.

[0119] Example 12 In the primary raw material composition preparation step, sodium hydroxide was added to GLM so as to obtain the sodium amount shown in Table 2, and the amounts of raw materials used, the water content of the primary raw material composition, and the humidity in the first polyaddition step were changed as shown in Tables 1 and 2. The secondary raw material composition, raw material composition, and polyurethane composite material were evaluated in the same manner as in Example 1. The results are shown in Table 3.

[0120] Example 13 In the primary raw material composition preparation step, sodium methacrylate was added to GLM so as to obtain the sodium amount shown in Table 2, and the amounts of raw materials used, the water content of the primary raw material composition, and the humidity in the first polyaddition step were changed as shown in Tables 1 and 2. The secondary raw material composition, raw material composition, and polyurethane composite material were evaluated in the same manner as in Example 1. The results are shown in Table 3.

[0121] Example 20 The secondary raw material composition, raw material composition, and polyurethane composite material were evaluated in the same manner as in Example 1, except that HXDI was used instead of XDI as the diisocyanate compound, and the amounts of raw materials used, the water content of the primary raw material composition, the humidity in the first polyaddition step, and the time from the start of mixing to the degassing step were changed as shown in Tables 1 and 2. The results are shown in Table 3.

[0122] Examples 21-22 In the primary raw material composition preparation step, sodium carbonate was added to GLM so as to obtain the sodium amount shown in Table 2, and the amounts of raw materials used, the water content of the primary raw material composition, the humidity in the first multi-addition step, and the time from the start of mixing to the degassing step were changed as shown in Tables 1 and 2. Furthermore, the pressure of the pressurized gas in the second multi-addition step was changed. Except for this, the secondary raw material composition, raw material composition, and polyurethane composite material were evaluated in the same manner as in Example 1. The results are shown in Table 3.

[0123] Example 23 In the primary raw material composition preparation step, sodium carbonate was added to GLM to achieve the sodium content shown in Table 2, and the amounts of raw materials used, the water content of the primary raw material composition, and the humidity in the first polyaddition step were varied as shown in Tables 1 and 2. Furthermore, the resulting secondary raw material composition was placed in a polyethylene cylindrical container (diameter 118 mm x height 125 mm) and subjected to a similar degassing process. The container was then tilted to avoid air bubbles being trapped, and the composition was poured into a polypropylene mold (length 14.5 mm x width 18 mm x height 14.5 mm (thickness 1.7 mm)). The secondary raw material composition, raw material composition, and polyurethane composite material were evaluated in the same manner as in Example 1, except that a mold filling of the secondary raw material composition was obtained. The results are shown in Table 3.

[0124] Examples 24 to 26 In the primary raw material composition preparation step, sodium carbonate was added to GLM so as to obtain the sodium amount shown in Table 2. The type of non-polyaddition monomer, the amount of raw materials used, the water content of the primary raw material composition, the humidity in the first polyaddition step, and the time from the start of mixing to the degassing step were varied as shown in Tables 1 and 2. Furthermore, the pressure of the pressurized gas in the second polyaddition step was varied. Except for this, the secondary raw material composition, raw material composition, and polyurethane composite material were evaluated in the same manner as in Example 1. The results are shown in Table 3.

[0125] Example 27 In the primary raw material composition preparation step, calcium methacrylate was added to GLM so as to obtain the calcium amount shown in Table 2, and the amounts of raw materials used, the water content of the primary raw material composition, and the humidity in the first polyaddition step were changed as shown in Tables 1 and 2. The secondary raw material composition, raw material composition, and polyurethane composite material were evaluated in the same manner as in Example 1. The results are shown in Table 3.

[0126] Example 28 In the primary raw material composition preparation step, potassium carbonate was added to GLM so as to obtain the potassium amount shown in Table 2, and the amounts of raw materials used, the water content of the primary raw material composition, and the humidity in the first polyaddition step were changed as shown in Tables 1 and 2. The secondary raw material composition, raw material composition, and polyurethane composite material were evaluated in the same manner as in Example 1. The results are shown in Table 3.

[0127] Comparative Example 1 The moisture content of the primary raw material composition was adjusted to 18,000 ppm by changing the standing time during drying to 15 hours, and the amounts of raw materials used, the moisture content of the primary raw material composition, the humidity in the first polyaddition step, and the time from the start of mixing to the degassing step were changed. Except for this, the secondary raw material composition, raw material composition, and polyurethane composite material were evaluated in the same manner as in Example 1. The results are shown in Table 3.

[0128] Comparative Example 2 The nitrogen pressure in the second double addition step was changed to 0.1 MPa, and the amounts of raw materials used, the water content of the first raw material composition, the humidity in the first double addition step, and the time from the start of mixing to the degassing step were changed, but the secondary raw material composition, raw material composition, and polyurethane composite material were evaluated in the same manner as in Example 1. The results are shown in Table 3.

[0129] Comparative Example 3 The time from the start of mixing to the degassing step was changed to 9 hours, and the amounts of raw materials used and the water content of the primary raw material composition were changed, but the secondary raw material composition, raw material composition, and polyurethane composite material were evaluated in the same manner as in Example 1. The results are shown in Table 3.

[0130] As shown in Examples 1 to 28, the polyurethane composite materials produced by the production method of the present invention have no internal defects and have high bending strength and water resistance.

[0131] As shown in Comparative Example 1, when the water content of the primary raw material composition exceeds 15,000 ppm, the amount of bubbles generated in the secondary addition step due to carbon dioxide gas increases, and the bubbles cannot be completely removed, resulting in defects inside the resulting polyurethane composite material, significantly reducing the bending strength and retention rate.

[0132] As shown in Comparative Example 2, when the nitrogen pressure in the second addition step is less than 0.2 MPa, the pressure is insufficient to remove the bubbles derived from the carbon dioxide gas generated in the second addition step, resulting in defects inside the resulting polyurethane composite material, and a significant decrease in bending strength and retention rate.

[0133] As shown in Comparative Example 3, when the molecular weight of the low-molecular-weight radically polymerizable polyurethane (A') in the secondary raw material composition exceeds 1,000, air bubbles cannot be completely removed in the degassing step and the second addition step, resulting in defects inside the resulting polyurethane composite material, and the bending strength and retention rate are significantly reduced.

Claims

1. A method for producing a molded article made of a polyurethane composite material in which (C) is dispersed in a matrix made of a polyurethane resin having a crosslinked structure, by radically polymerizing in a mold a raw material composition comprising: (A) a radically polymerizable polyurethane component made of a polyurethane having a radically polymerizable group; (C) an inorganic powder or particle; and (D) a thermal radical polymerization initiator, which may also contain a non-polyaddition monomer (B) made of a polymerizable monomer that does not undergo a polyaddition reaction with either an alcohol compound or a diisocyanate compound, thereby crosslinking (A), a primary raw material composition preparation step of preparing a primary raw material composition comprising a composition comprising a radically polymerizable alcohol (a1) consisting of an alcohol compound having a radically polymerizable group in the molecule, 90 mol % or more of which is a diol having a radically polymerizable group in the molecule, and (C), and optionally containing (B) and / or (D), wherein the composition has a water content of (1) 15,000 ppm or less relative to the total mass of (a1) when the composition does not contain (B), and (2) 15,000 ppm or less relative to the total mass of (a1) and (B) when the composition contains (B); a first polyaddition step of mixing the primary raw material composition with a diisocyanate compound (a2) and, if necessary, the (B) and / or the (D) blended therein, to partially polyaddition-react the (a1) in the primary raw material composition with the (a2) to form a low-molecular-weight radically polymerizable polyurethane component (A') having a number-average molecular weight of 500 to 1,000, and preparing a secondary raw material composition containing the (A'), unreacted (a1), unreacted (a2), (B), (C), and (D); a filling step of filling the secondary raw material composition into a mold; a second polyaddition step in which the secondary raw material composition filled in the mold is further subjected to a polyaddition reaction under a pressurized gas of 0.2 to 10 MPa to grow (A') and form a radical polymerizable polyurethane component having a number average molecular weight of 1,500 to 20,000, which becomes (A), thereby obtaining a raw material composition; and a polymerization and curing step of heating the raw material composition filled in the mold to carry out the radical polymerization; Including, In the primary raw material composition preparation step and the first polyaddition step, the amounts of (C) and (D) used are 150 to 550 parts by mass of (C) and 0.01 to 2.0 parts by mass of (D) relative to 100 parts by mass of the total of (a1) and (a2), A degassing treatment of the composition is carried out between the end of the first polyaddition step and the start of the polymerization and curing step; and When the degassing treatment is carried out before the filling step, the number average molecular weight of (A') is kept not to exceed 1,000 until the filling step is started, and when the degassing treatment is carried out after the filling step, the number average molecular weight of (A') is kept not to exceed 1,000 until the degassing step is started.

1. A method for producing a polyurethane composite material molded article, comprising:

2. the primary raw material composition preparation step is a step of mixing the (a1) and the (C), and the (B) and / or the (D) blended as necessary, to obtain an untreated primary raw material composition having the same blending ratio of these components as the primary raw material composition and a larger water content than the primary raw material composition; and The untreated primary raw material composition is subjected to a temperature of 0.1 to 6.0 (g / m ３ a dehydration step in which the primary raw material composition is dehydrated by contacting the primary raw material composition with an atmosphere maintained at 20°C; The method of claim 1 , comprising:

3. 50 to 100 mass % of (a1) is glycerol monomethacrylate, The diisocyanate (a2) may be a diisocyanate represented by the following general formula (1): 【Chemistry 1】 [X in the above general formula (1) is a group represented by the following general formula (2)] 【Chemistry 2】 {R in the above general formula (2) １ are each independently a hydrogen atom or a methyl group. A compound represented by the formula: The non-polyaddition monomer (B) may be a monomer represented by the following general formula (3): 【Transformation 3】 {R in the above general formula (3) ２ are each independently a hydrogen atom or a methyl group, and R ３ represents a hydrogen atom, a methyl group, an ethyl group, or a propyl group, and Y represents an integer of 1 to 10. A compound represented by The method of claim 1.

4. The method according to claim 1, wherein the (a1) contains 50 to 900 ppm by mass of alkali metal and / or alkaline earth metal based on the mass of the (a1).

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