JPH0692485B2 - Method for producing polymethylmethacrylate resin / silicone hybrid - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a polymethylmethacrylate resin / silicone hybrid, and more specifically, to a polymethylmethacrylate resin without heating and melting the polymethylmethacrylate resin. It relates to a method for producing a silicone hybrid.

[Prior Art] Conventionally, as a method for producing a polymethylmethacrylate resin / silicone hybrid, a method in which a polymethylmethacrylate resin and silicone oil are heated and melted and mixed in an extruder or a mixer (JP-A-49-109438, JPA
50-121344) or a method of adding and dissolving a silicone resin in a prepolymer of a polymethylmethacrylate resin and then performing heat polymerization (see JP-A-51-122161). However, the silicone used here is not curable.

A known manufacturing method applicable to the production of a polymethylmethacrylate resin / silicone hybrid is to heat and melt a thermoplastic resin, mix it with a curable silicone, and cure the curable silicone. (See JP-A-58-189257).

[Problems of the prior art] However, a method of mixing a melted polymethylmethacrylate resin and a curable silicone and curing the curable silicone is a high temperature of 140 to 170 ° C for melting the polymethylmethacrylate resin. However, there is a drawback that the silicone starts to cure while the curable silicone is being mixed and it is difficult to obtain a uniform hybrid. Further, the melted polymethylmethacrylate resin has a drawback that it is difficult to mold because it has a large fluidity and no shapeability.

Therefore, the present inventors have arrived at the present invention as a result of intensive research aimed at eliminating the above-mentioned drawbacks of the prior art. An object of the present invention is to provide a method for easily producing a polymethylmethacrylate-based resin / silicone hybrid without heating and melting the polymethylmethacrylate-based resin, and also to provide a production method having excellent molding workability. .

[Means for Solving Problems and Its Action] This object is a rice cake-like mixture composed of (A) (a) polymethylmethacrylate resin particles, (b) methylmethacrylate vinyl monomer, and (c) organic compound catalyst for radical polymerization. [However, the weight ratio of the component (a) and the component (b) is (1: 1) to (3: 1), and the component (c) is a catalytic amount. ] And a curable silicone polymer (B) [where the weight ratio of the components (A) and (B) is (99.9:
0.1) to (20:80). ] It is achieved by polymerizing and curing.

To explain this, in the present invention, the (a) polymethylmethacrylate-based resin particles include a filler, a small amount of a pigment, and a stabilizer in addition to the particles and the polymethylmethacrylate resin which are composed only of the polymethylmethacrylate resin. Polymethyl methacrylate means a polymer containing only methyl methacrylate and a small amount of other copolymerizable vinyl monomers, for example, alkyl methacrylate, methyl acrylate, etc. , Alkyl acrylates or copolymers with ethylene. The polymethylmethacrylate-based resin particles are preferably microspheres having a particle diameter of 30 to 500 μm from the viewpoint of ease of making a dough-like mixture.

(B) Methyl methacrylate-based vinyl monomer means a vinyl monomer consisting only of methyl methacrylate and a mixture of methyl methacrylate and a small amount of other copolymerizable vinyl monomer. Examples of the other monomer include ethylene glycol dimethacrylate in addition to the vinyl monomer described above. Ethylene glycol dimethacrylate contributes to prevention of deformation and cracking of polymethylmethacrylate resin / silicone hybrid and improvement of mechanical strength.

(C) Organic compound catalysts for radical polymerization include benzoyl peroxide, dilauryl peroxide, and di (t
-Butyl) peroxide, dicumyl peroxide,
Examples are organic peroxides such as 1,1-bis-t-butylperoxy-3,3,3-trimethylcyclohexane, α, α′-azobisisobutyronitrile. The addition amount of the organic compound catalyst for radical polymerization may be a so-called catalytic amount,
Specifically, 0.2 to 1.5 of the total amount of the components (a) and (b)
Weight percent is preferred. When the organic compound catalyst for radical polymerization remains in the polymethylmethacrylate resin, it is not always necessary to add the catalyst separately.

In the (A) rice cake-like mixture comprising (a) polymethylmethacrylate resin particles, (b) methylmethacrylate vinyl monomer and (c) radical polymerization catalyst, the components (a) and (b) are in a weight ratio ( 1: 1) to (3: 1), preferably about 2: 1 and obtained by mixing and storing in a closed container.

The mixture initially becomes damp, then stringy, then freshly mochi-like, and finally rubbery, but the freshly moistened dough can be mixed with a curable silicone polymer. use. In the freshly-prepared rice cake-like form, the polymethylmethacrylate resin is swollen and dissolved by the methylmethacrylate vinyl monomer, the viscosity becomes almost uniform, and plasticity is exhibited.

The curable silicone polymer (B) may be a single silicone polymer, that is, an organopolysiloxane, or a mixture of two or more silicone polymers, that is, an organopolysiloxane, as long as it can be cured.

Further, it may be in the form of a composition containing not only a silicone polymer but also one or more curing catalysts, curing inhibitors, fillers, heat stabilizers, pigments and the like. The inclusion of a curing catalyst is desired for rapid curing. Further, the curable silicone polymer may be in the form of gel, rubber or cured resin after curing.

The curing functions of curable silicone polymers are roughly classified into those that cure by hydrosilylation reaction using platinum-based catalyst, those that cure by radical reaction that uses organic peroxide catalyst, and those that cure by condensation reaction. However, in any case, those which cure under the condition that the methyl methacrylate vinyl monomer is polymerized are preferable. The type that cures by a hydrosilylation reaction contains a vinyl group-containing organopolysiloxane as a main component, an organohydrogenpolysiloxane, a platinum-based catalyst, and a hydrosilylation reaction inhibitor, and a type that cures by an organic peroxide catalyst is A type containing vinyl group-containing organopolysiloxane as a main agent, containing an organic peroxide, and cured by a condensation reaction is a silanol-containing organopolysiloxane as a main agent, and a crosslinking agent such as an organotrialkoxysilane, an alkyl silicate or an alkyl polysilicate. And a curing catalyst such as a fatty acid metal salt are common.

When the curable silicone polymer is in the form of a curable silicone rubber composition, it preferably contains a reinforcing filler such as fumed silica, precipitated silica, carbon black.

The curable silicone rubber composition is roughly classified into a liquid or paste type and a clay type, but the liquid or paste type is preferable from the viewpoint of easy mixing with the rice cake-like mixture.

To prepare a mixture of (A) rice cake-like mixture (A) polymethylmethacrylate resin particles, (b) methylmethacrylate vinyl monomer, and (c) organic compound catalyst for radical polymerization, and (B) curable silicone polymer It is advisable to mix both components with a spatula, a mixer or the like at a temperature at which they do not polymerize or cure. The mixing ratio of the component (A) and the component (B) is (99.1: 0.1) to (20:80), but it may be changed depending on the properties and intended use of the target hybrid.

When trying to modify the properties of polymethylmethacrylate resin with a cured silicone polymer,
The weight ratio of component (A) to component (B) is (99.9: 0.1) to (8
0:20) position, and when an attempt is made to obtain a hybrid compound having an intermediate property of a polymethylmethacrylate resin and a cured silicone polymer, the weight ratio of the component (A) to the component (B) is (20: It is preferably in the 80) to (80:20) positions.

After the components (A) and (B) have been mixed, they may be subjected to polymerization / curing as they are, or they may be placed under reduced pressure to remove entrapped bubbles and then subjected to polymerization / curing. However, care must be taken not to volatilize the methyl methacrylate vinyl monomer.

The conditions for polymerizing / curing the mixture of the component (A) and the component (B) are not particularly limited, but it is preferable to polymerize / cure in a closed state because the methyl methacrylate vinyl monomer does not volatilize, and to rapidly polymerize / cure. It is preferable to polymerize and cure under heating from the standpoint of causing it.

When it is desired to mold it to a certain shape, it may be molded in a gypsum mold, a mold, a ceramic mold or the like. Gypsum molds are convenient because it is easy to make various negative molds and the molded product can be taken out by breaking the gypsum layer after molding.

Molding methods include compression molding, injection molding, and transfer molding.

Further, it may be molded in such a form as to enclose another article such as a metal plate or glass cloth, or may be formed in a shape such that it is laminated on another article such as a glass cloth or wire mesh.

[Embodiment] Next, an embodiment of the present invention will be described. The number of parts in the examples is part by weight, and the viscosity is the value at 25 ° C.

Example 1 Of a pair of dental metal flasks, gypsum mud was poured almost completely into the lower porcelain of the flask, and 60 mm × 13 mm × 5 mm
The wax block of 60 mm × 13 mm was embedded so that one surface was the upper surface. After the gypsum hardened, a mold release agent was applied to the gypsum surface, the flask was overlaid with the mold release agent, and gypsum mud was poured into this to harden it. Next, separate the upper and lower burr, melt the wax block and let it flow out, 60 mm × 13 mm × 5 mm
A gypsum mold with a negative shape was created. Average particle size 50μ
Polymethylmethacrylate resin spherical particles of m and methylmethacrylate were mixed at a weight ratio of 2: 1, and 0.5% of both were mixed.
% Of benzoyl peroxide was added and mixed, and the mixture was stored in a petri dish. When left standing at room temperature to form a freshly moistened dough, mix well with the addition reaction-curable silicone rubber composition using a platinum-based catalyst in a weight ratio of 2: 1 to form a gypsum split type shadow. Filled in the mold. The addition reaction-curable silicone rubber composition described above was prepared by adding 100 parts of a dimethylpolysiloxane having vinyl groups at both ends blocked (viscosity 2000 cs), (C
H ₃ ) ₂ CH ₂ ＝ CH 40 parts toluene soluble copolymer consisting of SiO1 / 2 unit and SiO4 / 2 unit, trimethylsiloxane group-blocked methylhydrogenpolysiloxane at both ends (viscosity 10cs) 7.
0 parts, 37 parts of fumed silica having a specific surface area of 200 m ² / g hydrophobized with hexamethyldisilazane, 12 parts of the total amount of platinum complex catalyst of chloroplatinic acid and divinyltetramethyldisiloxane as 12 ppm and methylvinylcyclotetrazane It is a uniform mixture of 0.5 parts of siloxane, is in the form of a thixotropic paste, and has a hardness of 50 after curing. The upper and lower flasks were combined so that the gypsum surfaces were in contact with each other, pressure was applied with a flask press, and both flasks were clamped with a clamp. Put this in water at 70 ℃ for 60 minutes, then 100
It was put in water at ℃ for 120 minutes. Remove from water, allow to cool at room temperature, open the flask, break the plaster and resize to 60
A molded body of mm × 13 mm × 5 mm of polymethylmethacrylate resin / addition reaction curing type silicone rubber was taken out.
The molded body had flexibility and was excellent in lubricity. Since the above-mentioned addition reaction-curable silicone rubber composition cures immediately at 140 ° C., it was impossible to heat-melt and mix the polymethylmethacrylate resin.

Example 2 A molded product was produced under the same conditions as in Example 1 except that the mixing ratio of the dough-like mixture and the addition reaction-curable silicone rubber composition was 1: 1 and 1: 2 by weight. All of the molded products were flexible and excellent in lubricity, but the molded product with the mixing ratio of 1: 2 had greater flexibility and was closer to rubber.

Example 3 Using a mixer, a mixture of the polymethylmethacrylate resin of Example 1 and methylmethacrylate and benzoyl peroxide and the addition reaction curable silicone gel composition were mixed well in a weight ratio of 9: 1. did. Here, the addition reaction-curable silicone gel composition is a dimethylpolysiloxane (viscosity 5000 cs) 100 blocked with vinyl groups at both ends.
Parts, silanol group-blocked methyl vinyl siloxane at both ends (viscosity 40cs) 6.0 parts, trimethylsiloxy group-blocked methyl hydrogen polysiloxane at both ends 3.4 parts, and chloroplatinic acid as platinum weight consist of 10 ppm of the total amount of the composition at room temperature. It was liquid.

This mixture was filled into the negative gypsum mold of Example 1,
The upper and lower flasks were closed, the flask was pressed with a flask press, and the upper and lower flasks were clamped. Put this in water at 70 ° C for 60 minutes, then put it in water at 100 ° C for 120 minutes, take out the flask, allow it to cool at room temperature, open the flask, destroy the gypsum, and destroy the polymethylmethacrylic resin and addition reaction curable silicone. A molded body in which the gel composition was mixed at a weight ratio of 9: 1 was taken out. This molded product was slightly more flexible and more lubricative than the polymethylmethacrylate resin molded product.

Since the above-mentioned addition reaction-curable silicone gel composition cures immediately at 140 ° C., it was impossible to heat-melt and mix the polymethylmethacrylate resin.

Example 4 A molded product was produced under the same conditions as in Example 1 except that a radical reaction curable silicone rubber composition using an organic peroxide catalyst was used instead of the addition reaction curable silicone rubber in Example 1.

However, after removing the molded body from the flask, it was immersed in hot water at 70 ° C. for 2 hours to remove the decomposition product of the organic peroxide. The molded body had flexibility and excellent lubricity.

Here, the radical reaction-curable silicone rubber composition using an organic peroxide catalyst is 100 parts of dimethylpolysiloxane blocked with vinyl groups at both ends (viscosity 10000cs), (CH ₃ ) ₂ CH ₂ = CHS
5 parts of a toluene-soluble copolymer resin composed of iO1 / 2 units and SiO4 / 2 units, 30 parts of fumed silica having a specific surface area of 200 m ² / g treated with dimethyldichlorosilane, 1,1-bis-t-
Butyl peroxy-3,3,3-trimethylcyclohexane
It is a thixotropic paste-like material consisting of 1.0 part, and has a hardness of 40 after curing. Since this silicone rubber composition cures immediately at 140 ° C., it was impossible to heat-melt and mix the polymethylmethacrylate resin.

EFFECTS OF THE INVENTION In the present invention, (A) a poly (methyl methacrylate) -based resin particle, (b) a methyl methacrylate-based vinyl monomer, and (c) a radical polymerization catalyst, and a (B) curable silicone. As the mixture with the polymer is polymerized and cured, the polymethylmethacrylate-based resin does not have to be melted by heating.
It is characterized in that a silicone hybrid can be easily manufactured with good molding workability.

Therefore, the production method of the present invention is modified by a cured silicone polymer, that is, a polymethylmethacrylate resin molded article having excellent lubricity, and an intermediate property between the polymethylmethacrylate resin and the cured silicone polymer. It is useful for producing a molded body.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display area C08K 5/14 C08L 33/04 LJE 7921-4J 83/04 LRY 8319-4J

Claims (3)

[Claims] 1. A dough-like mixture comprising (A) (a) polymethylmethacrylate resin particles, (b) methylmethacrylate vinyl monomer, and (c) organic compound catalyst for radical polymerization [where component (a) and ( The weight ratio of the component (b) is (1: 1) to (3: 1), and the component (c) is a catalytic amount. ] And a curable silicone polymer (B) [where the weight ratio of the components (A) and (B) is (99.9:
0.1) to (20:80). ] Is polymerized and cured, and a method for producing a polymethylmethacrylate-based resin / silicone hybrid. 2. The method according to claim 1, wherein the component (a) is polymethylmethacrylate resin particles, the component (b) is methyl methacrylate, and the component (c) is an organic peroxide. . 3. The method according to claim 1, wherein the mixture of the component (A) and the component (B) is polymerized and cured under heating.