JPS6253523B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a dicarboxylic acid ester polymer. Specifically, it is a method for producing a dicarboxylic acid ester polymer having a pearl-like spherical shape with a particle size of 1 to 200 μm and containing an inorganic filler uniformly dispersed within the particles. That is, the general formula (However, R ₁ to _{R 4} are the same or different H or CH ₃
(CH ₂ ) _o (where n is 0 or a positive integer), and R' is

【formula】

[Formula] -HCOH-HCOH- or -(CH ₂ ) _n - (where m is a positive integer)) or a dicarboxylic acid unsaturated ester represented by the general formula [A] An inorganic product characterized by suspension polymerizing a monomer mixture with at least one copolymerizable monomer selected from methacrylates, diallyl compounds, and vinyl compounds in an aqueous medium in the presence of an inorganic filler. This is a method for producing a filler-containing dicarboxylic acid ester polymer. Conventionally, in the manufacturing method of polymers of bifunctional monomers, the polymers have crosslinks and are insoluble and infusible resins (also called thermosetting resins), so it is impossible to mold them after polymerization. Therefore, it is common practice to carry out polymerization and molding at the same time, such as cast polymerization. Therefore, in general, when a polymer of a bifunctional monomer is used in the form of particles or powder, the polymer obtained by the above-mentioned cast polymerization is pulverized. However, the field of use of mechanically pulverized granules is often limited because the pulverized surface does not become spherical. For example, in the field of tooth material resins for dental crowns or restorations, if the pulverized material is mixed with a liquid monomer and used, the operability is poor, and even if the polymer is excellent, it cannot be used. Not done. In addition, in the case of such thermosetting resins, it is impossible to uniformly disperse and integrate the inorganic filler into the resin after polymerization, so it is necessary to mix the inorganic filler into the monomer and then polymerize it. There must be. In this case, if the difference in specific gravity between the monomer and the inorganic filler is small and the two have mutual affinity, the inorganic filler can be uniformly dispersed in the monomer, and by casting the monomer and polymerizing it. It is possible to create a thermosetting resin composition in which an inorganic filler is uniformly dispersed and integrated, but inorganic fillers are usually not compatible with hydrocarbons, and their specific gravity often differs. It has been difficult to obtain thermoplastic resins in which fine powder fillers are uniformly dispersed and integrated. In particular, there has been no technique for uniformly dispersing inorganic fillers in thermosetting resin particles having a diameter of about 1 to 200 microns. The present inventors have conducted intensive research to obtain a polymer in which an inorganic filler is uniformly dispersed and integrated in a method for obtaining a spherical polymer by polymerizing a bifunctional monomer. As a result, they discovered that an excellent pearl-like polymer can be obtained by suspension polymerizing a specific unsaturated dicarboxylic acid ester in an aqueous medium in the presence of an inorganic filler, leading to the completion of the present invention. That is, the present invention is based on the general formula (However, R ₁ to _{R 4} are the same or different H or CH ₃
(CH ₂ ) _o (where n is 0 or a positive integer), and R' is

【formula】

A dicarboxylic acid unsaturated ester represented by [Formula] -HCOH-HCOH- or -(CH ₂ ) _n - (where m is a positive integer) or a dicarboxylic acid unsaturated ester represented by the general formula [A] An inorganic product characterized by suspension polymerization of a monomer mixture with at least one copolymerizable monomer selected from methacrylates, diallyl compounds, and vinyl compounds in an aqueous medium in the presence of an inorganic filler. This is a method for producing a filler-containing dicarboxylic acid ester polymer. In addition, the dicarboxylic acid ester polymer referred to in the present invention refers to a homopolymer obtained by polymerizing the dicarboxylic acid unsaturated ester shown by the above general formula alone, and a copolymer obtained by polymerizing the dicarboxylic acid unsaturated ester and other monomers copolymerizable with it. This is a general term that includes copolymers containing 50% (by weight) or more of the resin portion of the dicarboxylic acid unsaturated ester obtained by the process. Since the dicarboxylic acid ester polymer obtained by the present invention is pearl-like particles, it has good fluidity and
It has good operability and exhibits good properties as an organic filler. For example, it can be easily blended with other polymers and can be effectively used to improve the properties of the polymer. It shows particularly good properties when used as a filling material for dental resins. The dicarboxylic acid unsaturated ester used in the present invention has the general formula: This is shown in . In the general formula [A], R ₁ ~
R ₄ is not particularly limited and may be the same or different H or CH ₃
(CH ₂ ) _o (where n is 0 or a positive integer) can be used, but it is limited to the raw materials for industrially producing the dicarboxylic acid unsaturated ester, and generally H or CH ₃
is most preferably used. Also, in the general formula [A]
R′ is due to the practical constraints of industrial production.

【formula】

[Formula] -HCOH-HCOH- or -(CH ₂ )- _n is preferred. However, m in the above (CH ₂ ) _n is not particularly limited, but 1 or 2 is most suitable in practice. Examples of typical unsaturated dicarboxylic esters represented by the general formula [A] include diallyl epoxysuccinate (hereinafter sometimes abbreviated as ESA(A) ₂ ), dimethallyl epoxysuccinate, and diallyl maleate. , dimethallyl maleate, diallyl acetate (hereinafter sometimes abbreviated as TA(A) ₂ ), dimethallyl acetate, diallyl malonate, dimethallyl malonate, diallyl succinate, and the like are preferably used. The present invention is characterized in that the inorganic filler is uniformly dispersed and integrated into the dicarboxylic acid ester polymer. However, it is generally difficult to uniformly blend an inorganic filler into the dicarboxylic acid ester polymer and mold it. In addition, it is generally technically difficult to produce a polymer uniformly containing an inorganic filler. However, in the present invention, when an inorganic filler is coexisted in the polymerization system when the dicarboxylic acid unsaturated ester represented by the general formula [A] is suspension polymerized in an aqueous medium, the inorganic filler is uniformly dispersed. A dispersed dicarboxylic acid ester polymer is obtained. Although it is not clear how the inorganic filler behaves in the dicarboxylic acid ester polymer in an aqueous medium, the above phenomenon can be said to be surprising. Moreover, although the inorganic filler added to the polymerization system differs slightly depending on its type, it is not only almost completely contained in the dicarboxylic acid ester polymer and recovered, but also the desired pearls, regardless of the amount added. It is possible to obtain a dicarboxylic acid ester polymer having the following properties. In the present invention, favorable results can often be obtained by the presence of a monomer copolymerizable with the unsaturated dicarboxylic ester represented by the general formula [A]. The copolymerizable monomer is not particularly limited as long as it can be copolymerized with the unsaturated dicarboxylic ester, but examples of commonly used monomers include methyl methacrylate, diethylene glycol dimethacrylate, and bismethacrylate. Methacrylates such as oxyethoxyphenylpropane; diallyl compounds such as diallyl phthalate, diallyl terephthalate, and diethylene glycol bisallyl carbonate; vinyl compounds such as maleic anhydride, vinyl acetate, and styrene, and the like are preferably used. The use of these copolymerizable monomers is often effective in improving the properties of the resulting copolymer, but if the amount of the copolymerizable monomer used is large, the polymer of dicarboxylic acid unsaturated ester Usually, the content of the dicarboxylic acid unsaturated ester component in the copolymer is
It is preferable to select it so that it is 50% (by weight) or more. Next, the inorganic filler used in the present invention is not particularly limited, and any known inorganic filler can be used. For example, various inorganic fillers can be used, such as those described in "Powder (Theory and Application)" (edited by Kiichiro Kubo, published by Maruzen Co., Ltd., May 12, 1970), but typical Examples include silica, alumina, glass beads, crystal, quartz, copper alloy, aluminum alloy, silicate, porcelain, and apatite powder. Although it varies depending on the use of the dicarboxylic acid ester polymer obtained in the present invention, in particular surface-treated inorganic fillers, such as
It is preferable to use a silane coupling agent such as dimethyldichlorosilane or γ-methacryloxypropyltrimethoxysilane, or one surface-treated with stearic acid. Further, the inorganic filler varies depending on its shape and type, but can be used in any proportion as described above. Generally, it is most preferred to use the inorganic filler in a proportion of 1 to 99% based on the total amount of dicarboxylic acid unsaturated ester and inorganic filler. The shape, particle size, etc. of the inorganic filler may be selected as required, but it is generally most suitable to use one in the range of 0.001 to 10 μm. The suspension polymerization means used in the present invention is not particularly limited, and polymerization is carried out in an aqueous medium in the presence of a suspending agent. The suspending agent used in the present invention is not particularly limited, and any suspension agent used in known suspension polymerization can be used. For example, "Polyvinyl Chloride - Its Chemistry and Industry" (edited by Kinki Chemical Industry Association, Vinyl Section, Asakura Shobo Publishing, Showa
(issued June 25, 1936) can be used. Representative examples of commonly used materials include gelatin, starch, sodium algyl acid, polyvinyl alcohol, polyvinylpyrrolidodone, methyl cellulose, hydroxyethyl cellulose, polyvinyl methyl ether, vinyl acetate/maleic anhydride copolymer, etc. It is. The amount of the suspending agent to be used varies depending on the type of unsaturated dicarboxylic acid ester, polymerization conditions, etc., and cannot be absolutely limited, but in general, it is necessary to use an unsaturated dicarboxylic ester or, in the case of copolymerization, an unsaturated dicarboxylic ester and an unsaturated dicarboxylic ester. It may be added in an amount of 0.1 to 40% (by weight) based on the total amount including the copolymerizable monomer. Further, in the suspension polymerization, it is necessary to use a polymerization initiator as in generally known suspension polymerization.
Generally known polymerization initiators can be used as the polymerization initiator, and representative examples include azo compounds such as azobisisobutyronitrile, ketone peroxide, diacyl peroxide, dialkyl peroxide, and hydroperoxide. , perester, and other organic peroxides are preferably used. The amount of the polymerization initiator to be used varies depending on the type of unsaturated dicarboxylic ester, polymerization conditions, etc., and cannot be absolutely limited, but in general, the amount of unsaturated dicarboxylic acid used or, in the case of copolymerization, the unsaturated dicarboxylic acid used. It is suitable to use it in an amount of 0.1 to 10% (by weight) based on the total amount of the ester and the copolymerizable monomer. Furthermore, in order to aid in the dispersion of the polymerization reaction system during the polymerization, means such as adding a surfactant such as sodium dodecylbenzenesulfonate or an inorganic salt can be employed as necessary. The conditions for suspension polymerization in the present invention are not particularly limited and may be appropriately determined as necessary. In general, 20° C. to 120° C. for 30 minutes to 10 hours is suitable, although it varies depending on, for example, the polymerization temperature and the type and amount of the polymerization initiator. In addition, for polymerization, it is possible to use known suspension polymerization techniques, and it is also possible to add a seed polymer to obtain a uniform particle shape, and for copolymerization, methods such as random copolymerization and block copolymerization can be used. It is also possible to use Furthermore, the polymerization is preferably carried out with stirring in an atmosphere of an inert gas such as nitrogen, similar to known suspension polymerization. Generally, stirring blades are of the turbine type, fan turbine type, propeller type, etc., and it is also a preferred embodiment to use a baffle plate in the polymerization tank to aid stirring. Furthermore, the particle size and particle size distribution of the dicarboxylic acid ester polymer can be changed by changing the suspension polymerization conditions such as the type and amount of the suspending agent, the monomer concentration, the method of sequential addition of monomers, stirring, and baffles. The dicarboxylic acid ester polymer of the present invention is obtained as a pearl-like spherical polymer having an average particle size of 1 to 200 μm. The particle size of the dicarboxylic acid ester polymer varies depending on the type of polymerization, stirring speed, etc., but by providing the baffle plate described above, the dicarboxylic acid ester polymer can be made to have a uniform particle size. An electron micrograph is shown in FIG. 1 to show an example of the dicarboxylic acid ester polymer obtained by the present invention. That is, FIG. 1 is an electron micrograph of the dicarboxylic acid ester polymer obtained in Example 1.
FIG. 2 is a photograph analyzed by an X-ray microanalyzer (abbreviated as XMA) to show that the inorganic filler is uniformly dispersed in the particles shown in FIG. It can be seen from the dispersion of many small dots in the photograph that the inorganic filler is uniformly dispersed in the resin. The dicarboxylic acid ester polymer of the present invention is obtained as a pearl-shaped spherical polymer having an average particle size of 1 to 200 μm, for example, unlike conventional pulverized granules or powders. Therefore, it is used for various purposes, such as the above-mentioned tooth materials for dental crowns or restorations, or as an additive to various polymers. EXAMPLES In order to explain the present invention more specifically, Examples and Comparative Examples will be described below, but the present invention is not limited to these Examples. Example 1 Four baffle plates were installed vertically in the polymerization tank,
After a single cylindrical glass reactor using a flat-blade turbine as the stirring blade was purged with nitrogen, 420 ml of ion-exchanged water (hereinafter abbreviated as water) and 5 g of polyvinyl alcohol (saponification degree 80%, 2500) (4% aqueous solution 125 ml) were added.
ml) and methyl cellulose 0.5 g (4% aqueous solution 125
ml) was added. Next, ESA(A) ₂ 200g, silica
A mixture of 50 g of AER-300 (manufactured by Nihon Erosil Co., Ltd., hydrophilic, average particle size 7 mμ) and 4 g of benzoyl peroxide (hereinafter abbreviated as BPO) was added to a reactor, and the mixture was heated at 90°C for 3 hours under stirring at 2700 rpm. Polymerized. Note that all polymerization operations were performed in a nitrogen atmosphere. After the polymerization was completed, the contents were filtered and washed successively with water and methanol in order to remove the suspending agent and unreacted monomers. After drying under reduced pressure, average particle size is 120μ
187 g of pearl-like dicarboxylic acid ester polymer was obtained. (The obtained polymer is shown in Figure 1) The obtained pearl-like polymer was immersed in a 10% fluoric acid aqueous solution to dissolve the silica that was not incorporated into the polymer, and then XMA analysis was performed. Ivy (second
(see figure). It was confirmed that silica was uniformly dispersed within the polymer. Examples 2 to 7 In Example 1, except that the dicarboxylic acid unsaturated ester and inorganic filler shown in Table 1 were added,
It was carried out in the same manner as in Example 1. The results are also shown in Table 1. However, in Examples 2 to 5 and 7, the dicarboxylic acid unsaturated ester, the inorganic filler, and the polymerization initiator were each independently added to the reactor without being mixed in advance. Pearl-like polymers were obtained in all Examples. Further, in Example 2, it was a pearl-like polymer containing 18% silica.

[Table] Examples 8 to 11 In Example 2, the dicarboxylic acid unsaturated ester/comonomer shown in Table 2 was used instead of the dicarboxylic acid unsaturated ester, and polymerization was performed in the presence of an inorganic filler. , carried out in the same manner as in Example 2. The results are shown in Table 2. Pearl-like polymers were obtained in all Examples. However, in Examples 8 and 10, the unsaturated dicarboxylic ester, comonomer, inorganic filler, and polymerization initiator were mixed in advance and then added to the reactor.

[Table] Examples 12 to 16 The same procedure as in Example 1 was carried out except that the unsaturated dicarboxylic ester and inorganic filler in Example 1 were replaced by those shown in Table 3. The results are shown in Table 3. Pearl-like polymers were obtained in all Examples.

【table】 [Brief explanation of the drawing]

Figure 1 is an electron micrograph of the pearl-like polymer obtained by the present invention, and Figure 2 is an electron micrograph of the same type of particles used to take the electron micrograph shown in Figure 1. This is an electron micrograph taken using an X-ray microanalyzer.

Claims (1)

[Claims] 1 General formula [A], (However, R ₁ , R ₂ , R ₃ and R ₄ are the same or different H or CH ₃ (CH ₂ ) _o (however, n is 0 or a positive integer)
So, R' is [Formula] [Formula] -HCOH- HCOH- or -(CH ₂ ) _n - (where m is a positive integer)
) or a dicarboxylic unsaturated ester represented by the general formula [A] and at least one copolymerizable monomer selected from methacrylates, diallyl compounds, and vinyl compounds. 1. A method for producing an inorganic filler-containing dicarboxylic acid ester polymer, which comprises suspending and polymerizing a monomer mixture with an inorganic filler in an aqueous medium in the presence of an inorganic filler. 2. The manufacturing method according to claim 1, wherein the inorganic filler has a particle size of 0.001 to 10μ. 3. The manufacturing method according to claim 1 or 2, wherein the inorganic filler is a surface-treated inorganic filler.