JPH034576B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a coupling agent for alumina. (Prior Art and Problems) Granular or whisker-like alumina is used as a filler for various synthetic resins. In general, inorganic fillers have a low affinity with synthetic resins, and if used as is, it is difficult to impart desired physical properties to the synthetic resin. Therefore, before blending the inorganic filler with the synthetic resin, it is treated with a coupling agent to increase its affinity with the synthetic resin. As the coupling agent, a silane compound such as γ-methacryloxypropylmethoxysilane is often used. By the way, it has been found that even if alumina is treated with a silane coupling agent, its affinity with synthetic resins does not increase as expected. Alumina is not only useful as a filler for general-purpose resins such as polyolefin and polyamide, but has also recently attracted attention as a filler for dental composite resins, and the development of a coupling agent for alumina is desired. (Means for Solving the Problems) The present invention satisfies the above requirements. According to the invention, the formula (In both formulas, R ¹ is hydrogen or an alkyl group having 1 to 4 carbon atoms, R ² is an alkylene group having 1 to 6 carbon atoms, X is COO or O, and n is 1 or 2. .In addition, when n is 2 and COOH is bonded to the adjacent position of the benzene ring,
Carboxylic acid anhydrides may also be formed. ),
A coupling agent for alumina is provided which is used by being mixed into a dental resin. Specific examples of the compound represented by formula [] include acrylic acid and methacrylic acid. Specific examples of the compound represented by formula [] include the following compounds. There are no particular restrictions on the shape of alumina treated with the coupling agent of the present invention, and it can be in the form of particles, whiskers, or fibers. For particulate alumina, its average diameter is usually 0.1~
60μ, and for whiskered or fibrous alumina, the diameter is generally 0.1-1μ and the length/diameter is 5-200. Although alumina is preferably treated with a coupling agent before being blended into dental resin, alumina can also be added when blending with dental resin. Further, as long as the polymerization reaction is not inhibited, alumina treated with a coupling agent may be present during the production of dental resin, or a coupling agent and alumina may be present. The amount of coupling agent used is based on the alumina.
It is preferably 0.1 to 5% by weight. If the amount of coupling agent used is too small, it will not be possible to impart sufficient affinity to the dental resin to alumina, and even if the amount used is too large, no noticeable difference in effectiveness will be observed. Specific examples of dental resins include: (In the formula, m and n are 0 to 2.) Examples include polymers obtained by radical polymerization of monomers such as. The dental resin described above is preferably used as the alumina matrix resin treated with the coupling agent of the present invention. The amount of alumina added to the synthetic resin can be varied over a wide range; for example, 10 to 500 parts by weight of alumina can be mixed per 100 parts by weight of the synthetic resin. (Effects of the Invention) A dental resin containing alumina on the surface of which the coupling agent of the present invention is adsorbed or bonded exhibits excellent physical properties, such as high bending strength and compressive strength. (Example) Examples are shown below. In the examples, the bending strength was measured on a test piece of 3 x 30 x 2 mm, and the compressive strength was measured on a test piece of 4 mmφ x 3 mm using a Shimadzu autograph at a head speed of 2 mm/min. The coupling agent and dental resin raw materials used in the examples are shown below. Examples 1 to 3 10 g of alumina with an average particle size of 0.4 μm and the amount of (C1) shown in Table 1 were added to 10 ml of acetone, and after adsorbing (C1) on the alumina, the acetone was distilled off. 1 g of the obtained alumina (M1) and 0.01 g of benzoyl peroxide were mixed, and a gap corresponding to the shape of the test piece was formed through a 3 mm thick Teflon sheet, and a slide glass was attached to the bottom surface. The mixture was injected into the mold, and a slide glass was pressed against the top of the mold and fixed with a clip. The mixture in the mold was held at 100°C for 30 minutes under a pressure of 5 kg/cm ² to polymerize (M1),
I made a test piece. After cooling to room temperature,
Take out the test piece and use emery paper to
It was polished to No. 800 and its bending strength and compressive strength were measured. The results are shown in Table 1. Comparative Example 1 The same method as Example 1 was repeated except that the alumina was not treated with (C1). The results are shown in Table 1. Comparative Example 2 The same method as Example 1 was repeated except that 0.2 g of γ-methacryloxypropylmethoxysilane (MPS) was used in place of (C1). The results are shown in Table 1.

[Table] Examples 4-5 The same method as in Example 1 was repeated, except that 0.2 g of the coupling agent listed in Table 2 was used in place of (C1). The results are shown in Table 2.

[Table] Example 7 The same method as in Example 1 was repeated, except that alumina was not treated with (C1) in advance, and (M1) was mixed with alumina and (C1) to polymerize (M1). Bending strength is 1601Kg/ ^cm2 , compressive strength is 3527Kg/ ^cm2
It was hot.

Claims (1)

[Claims] 1 formula (In the formula, R ¹ is hydrogen or an alkyl group having 1 to 4 carbon atoms, R ² is an alkylene group having 1 to 6 carbon atoms, X is COO or O, and n is 1 or 2
It is. Note that when n is 2 and COOH is bonded to adjacent positions of the benzene ring, a carboxylic acid anhydride may be formed. ) is a coupling agent for alumina used in combination with dental resin.