JPS6071621A - Production of composite filler - Google Patents

Abstract

PURPOSE:A powder of inorganic filler and a specific monomer are polymerized and the resultant cured product is crushed to produce a composite filler that can prevent the product made of a resin or rubber and the filler from reducing its impact strength and bend strength and improves its toughness, hardness and brittleness. CONSTITUTION:The polymerization of (A) 100pts.wt. of an inorganic filler, preferably silica, (B) an acrylic monomer bearing 3 or more polymerizable double bonds, preferably tri(meth)acrylate, preferably 25-70pts.wt., (C) an acrylic monomer bearing 2 or more polymerizable double bonds, preferably polyethylene glycol di(meth)acrylate, preferably 30-70pts.wt., is carried out using a radical polymerization initiator and stop it at such a stage as a part of polymerizable double bonds in the acrylic monomers remains then the resultant cured product is crushed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a composite filler. More specifically, the present invention relates to a method for producing a composite filler suitable for blending into various resins and rubbers.

Various composite fillers in which an inorganic filler is coated with an organic substance have been studied as composite fillers that have increased affinity for various resins and rubbers and are suitable for blending into them.
Inorganic filler powder and 3 or more polymerizable duplexes in the molecule 4
We have previously proposed a method for producing a composite filler by polymerizing polymers in an acrylic system having a specific composition in the presence of a radical polymerization initiator and pulverizing the resulting cured product (Japanese Patent Application Laid-Open No. 1983-1993). −
Publication No. 20066).

The composite filler produced by this method has three or more polymerizable double bonds in the acrylic monomer, so it is difficult to completely polymerize all of them, but some of them remain. Therefore, the obtained composite filler is highly reactive and can chemically bond with various resins and rubbers to prevent their impact strength and bending strength from decreasing. Since the dispersion of the filler is maintained well, the stiffness, hardness, etc. of the compound are effectively improved.

As described above, the previously proposed composite fillers have shown favorable properties, but depending on the application, the degree of crosslinking may be too high, leading to the problem that the composite fillers and their blends become brittle. . The present inventors investigated ways to solve this problem, and as a result, we decided to replace some of the acrylic monomers with three or more polymerizable double bonds in the molecule with two polymerizable double bonds in the molecule. It has been found that substitution with an acrylic monomer having double bonds is an effective solution.

Therefore, the present invention relates to a method for producing a composite filler, and the method for producing a composite filler includes (A) an inorganic filler powder, (B) an acrylic monomer having three or more polymerizable double bonds in the molecule. This is carried out by polymerizing an acrylic monomer having two polymerizable double bonds in the molecule and (01) in the presence of a radical initiator, and pulverizing the obtained cured product.

The ν filler produced by the method of the present invention improves the brittleness without substantially impairing the above-mentioned favorable modification effect. Here, improvement in brittleness means that, for example, when a compound test piece is subjected to strain, it does not break even if the amount of deformation becomes large. To give a specific example, when used as a dental hard resin filling material, even when the resin is baked onto a large gold cast crown, it is shown that it is difficult for the hard resin to be punctured.

The inorganic filler powder of component (A) and the acrylic monomer having three or more polymerizable double bonds in the molecule of component (B) are both described in the above-mentioned patent publication. Also used in the same way. That is, as the inorganic filler powder, all those generally recognized as inorganic fillers for various resins and combs can be used. Among them, silica, especially silica treated in Tables 1 and 1 to impart hydrophobicity, is used. preferable. In addition, triacrylate, triacrylate,
Triacrylate, tetraacrylate, tetraacrylate, etc. are used, for example,
Tri- or tetra-substituted acrylates or methacrylates such as methylolethane, trimethylolpronochloride, penquerythritol, etc. are used, and trimethylolpronochloride or trimethacrylate is preferred.

゛In addition, as the acrylic spinning wheel body having two polymerizable double bonds in the molecule of component (0), ethylene glycol di(meth)acrylate, polyethylene glycol di(
meth)acrylate, polyethylene glycol di(meth)acrylate, bisphenol A di(meth)acrylate, 2,2-bis[p-(meth)acryloxyethoxyphenyl]propane, 2,2-bis[p-(meth)rylate Ririloxiho.

ethoxyphenyl] propane, hydroxynigel (
Hydroxyalkyl (meth) such as meth)acrylates
2:1 adducts of acrylate and aliphatic or aromatic diisocyanates are used, in particular polyethylene glycol di(meth)acrylate, hydroxyalkyl (
Preferred are meth)acrylate-diisocyanate adducts.

When producing the composite filler, it is preferable to mix the inorganic filler powder and the acrylic monomer in advance. This premixing involves mixing a small amount of both to form a slightly hard paste, which is then passed through a two-roll machine, a Panbury mixer, a ball mill, etc., and while kneading the remaining inorganic filler powder and acrylic monomer, the radical Polymerization initiators are sequentially mixed.

Their mixing ratio t is generally used within the range of about 25 to 70 parts by weight of component (B) and about 30 to 70 parts by weight of component (0) per 100 parts by weight of component (A). . (
If the Il) and (0) components are used in a ratio higher than this, the hardness and compressive strength of the resulting composite filler will decrease, and if the force (It) component is lower than this ratio, the hardness will also decrease. , the compression strength decreases, and the (C) component
: If the amount is too low, the blended filler will become brittle. In addition, as a radical polymerization initiator, dicumyl perogizide,
Benzoyl peroxide, azobisisobunalonitrile, and the like are used in an amount of about 0.01 to 3 times ffi% based on the total amount of each component (A), (B), and (0).

The mixture consisting of each of these components is heated to about 40 to 250°C, preferably about 60 to 15°C, using a hot press or the like.
At a temperature of 0° C. and about 10 to 3 QOKgGβ, preferably 100 to 200 kg, for about a few minutes to 1
Polymerize by heating for about an hour. Polymerization can also be carried out by heating in an inert gas atmosphere without applying pressure. In any case, some of the polymerizable double bonds in the acrylic monoplane 7
(1) It is preferable to terminate the polymerization reaction under conditions such that the same amount remains. The obtained cured product is pulverized to a desired size using, for example, a ball mill.

The composite filler according to the present invention not only prevents the impact strength and bending strength of the compound from decreasing and effectively improves the stiffness and hardness of the compound, but also allows the degree of crosslinking to be appropriately adjusted. It has the effect of not criticizing its fragility. Utilizing these properties, this composite filler can be used in various resins such as acrylic resins, styrene resins, olefin resins, polyamide resins, polyester resins, phenolic resins, and unsaturated polyester resins, as well as styrene-butadiene rubber and polybutadiene rubber. It can be effectively blended with various rubbers such as diene rubber and ethylene propylene diene rubber, and especially when blended with thermosetting resin before curing or rubber before vulcanization, its reinforcing effect is remarkable. Therefore, It can be used in a wider range of applications than conventional composite fillers, and can be effectively used, for example, in dental hard resins.

Next, the present invention will be explained with reference to examples. Each of these Examples shows that the composite filler according to the present invention is excellent as a filler for dental hard resin.

Example 1 Light fine powder silica (Japan Aerosil product Aerosil R9
72) 1091. ) Rimethylolpropane trimethacrylate 5g, hydroxyethyl methacrylate) -2
, 2,4-)limethylhexamethylene diisocyanate (2:1) adduct and 0.1 g of benzoyl peroxide were kneaded with a roll to form a paste. Polymerization was carried out by heating for 10 minutes under the conditions of att.

The obtained plate-shaped cured product was ground in a ball mill for 2.5 hours to obtain a powdered composite filler.

7.29 g of this powdered composite filler, 2.5 g of the above adduct, 2.5 g of 2.2-bis(4-methacryloxypolyethoxyphenyl)propane, and 1.0 g of light fine powder silica.
and benzoyl peroxide 0.0359 were kneaded with a spatula on a glass plate, and the formed base was mixed with 1
The mixture was heated and polymerized under the conditions of 20° C. and 4 KgG7 to obtain a cured product as a dental hard resin.

Example 2 In Example J, the same amount of hydroxyethyl methacrylate-hexamethylene diisocyanate (2:1) sized product was used as an adduct when polymerizing to form a plate-shaped cured product.

Example 3 In Example 1, the same amount of hydroxyethyl methacrylate-toluene diisocyanate (2:1) adduct was used as the adduct when polymerizing to form a plate-shaped cured product.

Example 4 In Example 1, the same amount of ethylene glycol dimethacrylate was used instead of the adduct when polymerizing to form a plate-shaped cured product.

Example 5 In Example 1, the same value of 1,8-octanediol dimethacrylate was used instead of the adduct when polymerizing to form a plate-shaped cured product.

Example 6 In Example 1, when polymerizing to form a plate-shaped cured product, trimethylolpurpane trimethacrylate was changed to 3.37 g, and the adduct was changed to 3.3 g, and in addition, hexamethylene glycol dimethacrylate was changed to 3.3 g. .37 was used.

Comparative Example In Example 1, when polymerizing to form a plate-shaped cured product, the amount of trimethylolpropane was changed to 10.09, and no additive was used.

Regarding the cured products at each stage obtained in each of the above examples and comparative examples, the content of polymerizable double bonds in the composite filler, hardness (Brinell hardness of dental hard resin), compressive strength and The strain at compression break was measured. The results obtained are shown in the following table.

Table example Double bond (mm) Hardness Compressive strength) Example 1 1.7 34 4
750 41//2 1.7 33 4710 40/
/3 - 34 4610 39 N4 2.1 35 4800 40 /15 1.9 33 4420 39//6 1.5
33 4780 43 Comparative example 1.7 34 506
0 35 [Measurement method] Polymerizable double bond: Hardness determined by measuring the absorbance of the double bond in the infrared absorption spectrum (1635 cm = ) (Brinell hardness): Compression according to 5.2.3 of J Engineering 5T-6508 Strength and strain at compression break: A 3X3X3 test piece was prepared and compressed at room temperature using Shimadzu Autograph M-5001 at a compression speed of 2mm7'.
The strength at the time of ri1 destruction and hemostasis at that time were measured. The amount of strain is expressed as a percentage of the length of the specimen in the compression direction, and a large value means that
This shows that it does not break under large deformation, that is, it is not brittle.

agent Patent Attorney Yoshi Hl Toshio

Claims (1)

[Claims] 1. (A) inorganic filler powder, CB) an acrylic monomer having 9 or more polymerizable double bonds in the molecule, and (0
) A method for producing a composite filler, which comprises polymerizing an acrylic monomer having two polymerizable double bonds in the molecule in the presence of a radical polymerization initiator, and pulverizing the obtained cured product. . 2. Component (B) is used in a proportion of about 25 to 70 parts by weight and component (0) is used in a proportion of about 30 to 70 parts by weight per 100 parts by weight of component (A). The method for producing a composite filler according to claim 1. 3. The method for producing a composite filler according to claim 1, wherein the acrylic monomer component CB) is tri(meth)acrylate or tetra(meth)acrylate. 4. Manufacturing method 05, (0) of the composite filler according to claim 1, wherein the acrylic monomer component (0) is polyethylene glycol di(meth)acrylate.
Special δ whose component acrylic monomer is an adduct of hydroxyalkyl (meth)acrylate and di-isocyanate.
``The method for producing a composite filler as set forth in claim 1. 6. The method as set forth in claim 1 in which the acrylic monomer is polymerized so that some of the polymerizable double bonds remain. Method for producing composite filler.