JPH03217401A - Cast polymerization of methacrylic resin - Google Patents

Abstract

PURPOSE:To cast-polymerize the raw material of the subject resin without the leakage of the cast raw material by employing a gasket as a sealing material and covering the gasket with a film comprising a mixture of a methacrylic resin with a vinylidene fluoride resin to bring the film into contact with the raw material. CONSTITUTION:A gasket 3 is employed as a sealing material and wound with film 2 comprising a mixture of 10-90wt.% of a methacrylic resin and 90-10wt.% of a vinylidene chloride resin to partially or wholly bring the casting raw material-contacting surface of the gasket 3 into contact with the film 2 in a linear or surface contact state, followed by setting the covered gasket in a cell 1. A casting material 4 comprising the partial polymerized product of methyl methacrylate and a polymerization initiator is cast in the cell 1 and subsequently cast-polymerized under heating to provide a methacrylic resin without the leakage of the casting raw material.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a method for cast polymerization of methacrylic resin.

[Conventional technology]

Methacrylic resin cast boards are widely used for lighting equipment, signboards, various building materials, etc. due to their excellent appearance, good weather resistance, mechanical properties, etc.

The polymerization method for the methacrylic resin cast plate includes methyl methacrylate monomer or a mixture of the monomer and its partial polymer, or a monomer mixture containing methyl methacrylate as the main component or the monomer mixture and its part. A cell in which a radical polymerization initiator is added to a mixture with a polymer as a casting raw material, and the casting raw material is injected between two facing inorganic glass plates or metal plates whose periphery is sealed with a gasket and heated. The above casting material is continuously injected and heated from upstream of the space sealed by the casting method or two stainless steel endless belt gaskets with single-sided mirror polishing moving in the same direction at the same speed. One example is the continuous casting method.

[Problem to be solved by the invention]

The gasket used here is generally made of vinyl chloride resin, and sealing properties are required for the casting raw material, but the casting raw material is made of methyl methacrylate monomers and methyl methacrylate parts with a low polymerization rate. When a polymer is used for cast polymerization or when a thick cast plate is polymerized, a problem arises when the casting material leaks from the end of the gasket.

[Failure to solve the problem]

As a result of intensive study to improve the shortcomings of the conventional polymerization method described above, the inventors of the Wooden Engineering Co., Ltd. discovered that by coating the gasket with a resin mixture containing a methacrylic resin and vinyl heptafluoride 1-nodene thread resin in a specific ratio, When performing cast polymerization using methacrylate monomers or methacrylate partial polymers with a low polymerization rate as casting raw materials, or when polymerizing thick cast plates, the casting raw materials do not leak from the gasket ends, and methacrylate The inventors have discovered that a cast plate made of a resin based on the resin is highly effective and can achieve the intended purpose, and have thus arrived at the present invention.

That is, the gist of the present invention is to include a method in which a gasket is used as a sealing material and a methacrylic resin raw material is cast-polymerized, and a methacrylic resin with a weight of 10 to 90% is used. Part or all of the surface of the gasket that comes into contact with the casting raw material is in line contact or surface contact with a film made of a resin mixture of 4 and vinyl fluoride IJ-based resins of 90 to 10 parts by weight, or A method for cast polymerizing a methacrylic resin, characterized in that at least the entire outer periphery of the gasket is rubbed with the resin mixture.

Examples of the methacrylic resin constituting the resin mixture used for coating the gasket of the present invention include alkyl methacrylates whose anolekyl group has 1 to 4 carbon atoms, such as methyl methacrylate, ethyl methacrylate, proyl methacrylate, butyl methacrylate, and the like; is an alkyl acrylate whose alkyl group has 1 to 8 carbon atoms, such as methyl acrylate, ethyl acrylate,
A homopolymer containing probyl acrylate, butyl acrylate, octyl acrylate, etc., or at least one of these alkyl methacrylates or alkyl acrylates as a dominant component, and at least one other comonomer copolymerizable with these as a minor component. Examples include copolymers as components or mixtures of these homopolymers and copolymers. These homopolymers and copolymers can be obtained by various polymerization methods such as suspension polymerization, emulsion polymerization, or bulk polymerization, and homopolymers or copolymers containing methyl methacrylate as a component are preferably used. . Furthermore, in order to increase the strength of the single mixed resin for gasket coating, a rubber component derived from alkyl acrylate, particularly butyl acrylate, is preferably introduced into the methacrylic resin.

Furthermore, the vinylidene fluoride resin used in the present invention includes a homobolymer mainly composed of vinylidene fluoride and at least 4-m comonomer copolymerizable with vinylidene fluoride, such as tetrafluoroethylene. cobolimers and mixtures thereof.

The resin mixture used for gasket coating of the present invention requires both a component that swells with the casting raw material and a component that does not swell, and the content of methacrylic resin in the resin mixture is 10 to 10%.
90 weight range, particularly 30 to 70tt4 is preferred.

When the weight of the methacrylic resin is less than 10%, it is preferable to carry out cast polymerization using a gasket covering material made of this resin mixture because the swelling of the covering material by the casting raw material is small and the sealing effect of the covering material is reduced. do not have. On the other hand, if the methacrylic resin exceeds 90% by weight, the gasket coating material made of this resin mixture will swell too much, reducing the sealing effect during cast polymerization.

The gasket covering material used in the present invention has the effect of preventing leakage of casting raw materials from the end of the gasket because the methacrylic resin, which is a component, swells with the casting component, but the pinylidene fluoride resin, which is another component, swells with the casting component. This is to prevent leakage of the casting material from the end of the gasket by the swelling of the covering material, while maintaining the strength of the covering material since it will not swell due to the casting material.

In the normal cast polymerization method for methacrylic resin, for example, when a single gasket made of vinyl chloride resin is used, the plasticizer, etc. in the gasket bleeds into the casting raw material, causing polymerization at the ends of the cast plate. However, the gasket coating material composed of the resin mixture according to the present invention also has the effect of preventing plasticizer and the like from seeping into the casting raw material from the gasket.

As an embodiment of the resin mixture for gasket coating according to the invention, methacrylic resin and vinylidene fluoride resin are mixed in, for example, a V-shaped blender, and then mixed in a melt extruder having an annular die or a T-die at the tip. After melting and kneading to form a film, the obtained film is wrapped around a gasket used during cast polymerization, and then used in the same way as a normal gasket, or as shown in Figure 1. It is used in surface contact with the gasket as shown in the cross-sectional view of the gasket, or in line contact with the gasket as shown in Figure 2K.

Gaskets may also be made by coextruding two or more layers of a resin mixture of a gasket material such as vinyl chloride resin, methacrylic resin, and vinylidene fluoride resin. A specific example is shown in FIG. Furthermore, the entire gasket can be molded from a resin mixture of methacrylic resin and vinylidene fluoride resin.

A stabilizer against heat or light may be added to the resin mixture of the methacrylic resin and vinylidene fluoride resin of the present invention, if necessary. Further, other resin components such as vinyl chloride resin can also be added as long as they do not impede the effects of the present invention.

〔Example〕

The present invention will be explained in more detail with reference to Examples below.

Example 1 (1) Production of film The resins shown in Table 1 were mixed in the proportions shown in Table 2, and this mixture was fed to a 30 mφ vented twin-screw extruder and melted and mixed at a cylinder temperature of 240°C to form a pellet. It was shaped into a shape. After drying the obtained pellet, a film having a thickness of 40 μm and a width of 200 μm was obtained by extrusion using a T-die extrusion method at a resin temperature of 240° C.

Table 1 Table 2 (2) Production of cast plate To 100 parts of partially polymerized methyl methacrylate (viscosity 100 centibois, polymerization rate 104), 0.06 part of azobis(2.4-dimethylpareronitrile) was added as a polymerization initiator. It was melted and used as a raw material for casting.

The casting raw material was reduced in size to remove dissolved air. This raw material was poured into a cell previously formed to a thickness of 12 squares using two sheets of tempered glass measuring 650 m x 450 square meters and a vinyl chloride resin gasket wrapped around films A1 to A4. Polymerization was carried out for 60 minutes in a warm water atmosphere at 82°C and for 30 minutes in an empty atmosphere at 130°C. Cast polymerization was carried out under the same conditions for 20 films, and the sealing performance of the film made of the resin mixture was judged based on the number of films from which the casting raw material leaked out of the 20 films. The results are shown in Table 3.

Table 3 Comparative Examples Table 4 11C The same cast polymerization as in Example 1 was carried out using a gasket wrapped with a film of 5.6 and a gasket alone without a film wrapped thereon. The results are shown in Table 5.

Table 4 Table 5 Example 2 The Hibet [F] powder 50 weight range used in Example row 1 and Kynar [F] 721 50 weight range were mixed,
Coextrusion with vinyl chloride resin was carried out at a mixed resin temperature of 220°C and a vinyl chloride resin temperature f of 80°C to obtain a two-layer gasket shown in the TLC diagram. The total thickness of the gasket is 12 mm, and the thickness of the mixed resin coating is 0.5 m. Using this gasket, cast polymerization was carried out in the same manner as in Example 1.
When 0 sheets were tested, no leakage of the casting raw material was observed, indicating good sealing performance.

〔Effect of the invention〕

As described above, the present invention is a method for cast polymerization of methacrylic resin using a gasket covering material made of a specific resin mixture, and therefore is highly effective in preventing leakage of casting raw materials.

[Brief explanation of drawings]

1, 2, and 3 are partial cross-sectional views showing embodiments of the present invention. DESCRIPTION OF SYMBOLS 1... Cell, 2... Film composed of resin mixture, 3...
Gasket, 4... Casting raw material, 5... Surface layer of two-layer gasket composed of resin mixture

Claims (1)

[Claims] 1. In a method of cast polymerizing methacrylic resin raw materials using a gasket as a sealing material, 10 to 90% by weight of methacrylic resin and 9% by weight of vinylidene fluoride resin.
Part or all of the surface of the gasket in contact with the casting raw material is covered with a film made of 0 to 10% by weight of a resin mixture,
A cast polymerization method for methacrylic resin characterized by line contact or surface contact, respectively. 2. In a method of cast polymerizing methacrylic resin raw materials using a gasket as a sealing material, 10 to 90% by weight of methacrylic resin and vinylidene fluoride resin 9
A method for cast polymerization of methacrylic resin, characterized in that a gasket having at least an outer circumferential portion made of 0 to 10% by weight of a resin mixture is used.