JPH08151498A - Production of cast methacrylic plate - Google Patents

Abstract

PURPOSE: To produce a cast methacrylic resin plate having a good balance between the impact resistance and the thermoformability. CONSTITUTION: A syrup is produced by dissolving 5-50 pts.wt. methyl methacrylate polymer having a viscosity-average molecular weight of 10,000 to 300,000 in 100 pts.wt. monomer composed mainly of methyl methacrylate and then dispersing 1-50 pts.wt. multilayered elastomer therein. This syrup is injected into a cell and polymerized.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a methacrylic resin cast plate.

[0002]

2. Description of the Related Art A methacrylic resin cast board is widely used for lighting equipment, signboards, various building materials, etc. due to its excellent transparency and surface gloss, good weather resistance and mechanical properties. Is not always sufficient, and is rather fragile, and its improvement is strongly desired, and various proposals have been made as its method. For example, JP-B-55-27576 discloses a methacrylic resin containing 4-90% by weight of a multi-stage sequentially produced polymer containing an elastomer layer.
An impact resistant composition containing is proposed, Example 1 thereof.
9 discloses the production of plates by the cast method. Further, Japanese Unexamined Patent Publication (Kokai) No. 1-198604 discloses a cast sheet to which an acrylic additive obtained by multi-step emulsion polymerization is added in an amount of 0.25 to less than 4% by weight. In addition, JP-A 1-252653
Japanese Patent Laid-Open Publication No. 2003-242242 discloses a graft copolymer obtained by graft-polymerizing a hard resin component to a rubber-like copolymer having a crosslinked structure and an average particle diameter of 0.1 to 1 μm in 100 parts by weight of a methyl methacrylate resin. A cast plate is disclosed in which the polymer is dispersed in an amount of 2 to 30 parts by weight as a rubbery copolymer.

[0003]

The methacrylic resin cast plate obtained by these methods is a methacrylic resin cast plate obtained by a usual cell casting method using only a monomer containing methyl methacrylate as a main component. Although it has excellent impact resistance, it has a low workability and needs to be further improved when the plate is further heated for molding. Therefore, the present invention provides a method for producing a methacrylic resin cast plate in which impact resistance and workability are well balanced.

[0004]

That is, in the present invention, 5 to 50 parts by weight of a methyl methacrylate polymer having a viscosity average molecular weight of 10,000 to 300,000 is added to 100 parts by weight of a monomer containing methyl methacrylate as a main component. It is a method for producing a methacrylic resin cast plate in which a syrup in which 1 to 50 parts by weight of a multilayer elastic body is dispersed is poured into a cell and polymerized.

The monomer containing methyl methacrylate as a main component in the present invention is a monomer mixture containing 50% or more of methyl methacrylate and optionally other copolymerizable monomer. Other copolymerizable monomers are known. For example, various (meth) acrylic acid alkyl esters, monofunctional monomers such as styrene, (poly)
Alkylene glycol di (meth) acrylic acid ester,
It is a polyfunctional monomer having two or more unsaturated double bonds in the molecule, such as allyl (meth) acrylic acid ester, trimethylolpropane tri (meth) acrylic acid ester, and divinylbenzene.

In the present invention, a methyl methacrylate polymer which is dissolved in a monomer containing methyl methacrylate as a main component means a polymer containing a methyl methacrylate unit as a main component, and methacrylic acid In addition to the methyl homopolymer, it also includes a copolymer with the above monofunctional monomer. And its viscosity average molecular weight is about 10,000 to 30
It is in the range of 0000. The viscosity average molecular weight is preferably in the range of 50,000 to 200,000, and more preferably in the range of 70,000 to 150,000.
A resin having a viscosity average molecular weight of less than about 10,000 is not preferable because the resulting resin has good moldability but low mechanical properties. The viscosity average molecular weight is 300,000.
If it exceeds the range, the workability becomes low, which is not preferable.

The amount of the methyl methacrylate polymer used is 5 to 50 parts by weight, preferably 10 to 40 parts by weight, based on 100 parts by weight of the monomer containing methyl methacrylate as a main component. If this amount is too small, the workability of the plate produced will be low, and if it is too large, the viscosity of the syrup will be too high and it will be difficult to handle.

In order to dissolve the methyl methacrylate-based polymer in the monomer containing methyl methacrylate as a main component, the methyl methacrylate-based polymer is prepared in advance and dissolved in the monomer anyway. Good. There is also a method of partially polymerizing the monomer containing methyl methacrylate as a main component by selecting the type and amount of the radical initiator or by a known method using a chain transfer agent together.

The multi-layered elastic body in the present invention is a powder or granular material having at least a two-layer structure and containing a rubber elastic layer or an elastomer layer in an amount of 20 to 60% by weight, for example, JP-B-55-27576. The materials described in the official gazette and Japanese Patent Laid-Open No. 1-252653 can be used.

1 to 50 parts by weight of the multi-layered elastic body is dispersed in 100 parts by weight of the monomer containing methyl methacrylate as a main component. Above all, the amount of rubber component and elastomer is
An amount of 0.2 to 30 parts by weight is desirable.

In order to disperse the multi-layered elastic body in the monomer, it is sufficient that both are uniformly mixed. This mixing may be performed after the methyl methacrylate-based polymer is already dissolved in the monomer, before the dissolution, or at the same time. To the syrup thus obtained, if necessary, known additives such as antioxidants, ultraviolet absorbers, chain transfer agents, release agents, dyes, pigments and inorganic fillers are added. You can also do it.

In order to polymerize the syrup, a known cell casting method can be applied as it is. That is, a radical polymerization initiator is added to the syrup,
As the radical polymerization initiator, a usual polymerization initiator used for producing a methacrylic resin plate can be used. For example, lauroyl peroxide, benzoyl peroxide, di-t-butyl peroxide, t-butyl peroxy 2-ethylhexanoate, t-butyl peroxyisobutyrate, t-butyl peroxypivalate, t-butyl peroxybenzoate, t-butyl peroxy. Acetate, diisopropyl peroxydicarbonate, di s
ec butyl peroxydicarbonate and other organic peroxide-based initiators; 2,2'azobisisobutyronitrile, 2,
Azo initiators such as 2'azobis (2,4-dimethylvaleronitrile); further known redox initiators obtained by combining a peroxide initiator and a reducing compound such as amines and mercaptans as main components. System etc.

The syrup is injected into a cell and polymerized by a known so-called cell casting method. That is, as the cell, for example, a batch-type cell casting method using two cells composed of a glass plate or a metal plate, a soft sealant and a clamp, and a continuous cell using two stainless continuous belts can be used. The thickness of the cell is also determined by the thickness of the desired methacrylic resin cast plate. The thickness of the plate is generally in the range of 1 to 30 mm.

The heating method in the polymerization is a known method, for example, hot air, hot water, or a heat source such as an infrared heater. The polymerization conditions are appropriately selected depending on the type and amount of the initiator used and the composition of the monomer mixture, but generally the polymerization is performed at 50 to 130 ° C. for 1 to several tens of hours. After completion of the polymerization, the glass plate or the metal plate forming the cell is removed to obtain a methacrylic resin plate.

[0015]

According to the present invention, a methacrylic resin cast plate having an excellent balance of impact resistance and workability can be obtained.

[0016]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited to this. The physical property measurements and test methods used in the examples are as follows. -Viscosity average molecular weight: The intrinsic viscosity [η] was determined using an Ubbelohde viscometer, and the viscosity average molecular weight M was determined by the formula [1].

[0017]

LnM = {ln [η] -ln (4.8 × 10-
5)} / 0.8 • Tensile test: JIS No. 2 test piece is used in accordance with JIS K 7113, the test piece is preheated to 170 ° C., and a tensile test is performed at a crosshead speed of 500 mm / min. The elastic modulus (Kgf / cm ² ) and the elongation at break (%) were determined. -Impact resistance: In accordance with JIS K 7211, a DuPont drop weight evaluation test was performed to drop a 500 g weight, and the 50% breaking energy (joule J) of the test piece was determined from the height. Workability: A 500 × 500 mm test piece was preheated at 170 ° C. and free blow molding was performed. The molded test piece was placed at a distance of 50 cm in front of the zebra pattern, the molded product was seen through from a distance of 1 m, and the zebra pattern was distorted, and the appearance was evaluated visually for the smoothness of the surface.

Example 1 Methyl methacrylate resin (98% by weight of methyl methacrylate unit, 2% by weight of methyl acrylate unit, viscosity average molecular weight) obtained by a suspension polymerization method was added to 100 parts by weight of a methyl methacrylate monomer. 20 parts by weight of powder of about 120,000) was added with stirring, and stirring was continued at 60 ° C. for 2 hours to dissolve the methacrylic resin. Subsequently, 15 parts by weight of a multi-layered elastic body having a three-layer structure (elastomer content of 25.2% by weight obtained by the method described in JP-B-55-27576, Example 3) was added with stirring, and after stirring for 1 hour. Then, it was cooled to room temperature to obtain a syrup in which the multilayer elastic body was uniformly dispersed. To 100 parts by weight of this syrup, 0.15 parts by weight of 2,2'azobisisobutyronitrile was added and dissolved, and degassed. Then, the gap between the glass plates was made by the two glass plates and the vinyl chloride resin gasket. Injected into a cell configured to be 3 mm, 6
Polymerization was carried out for 4 hours in a hot water bath at 5 ° C. 120 ° C
Heat treatment was carried out for 2 hours in the hot air drying oven, and after cooling to near room temperature, the glass plate was removed to obtain a methacrylic resin cast plate having a thickness of 3 mm. The obtained resin cast plate was evaluated. The results are shown in [Table 1].

Example 2 Powder 50 of methyl methacrylate resin (98% by weight of methyl methacrylate unit, 2% by weight of methyl acrylate unit, viscosity average molecular weight of about 150,000) obtained by suspension polymerization method
By weight, 50 parts by weight of the multilayer elastic body having the same three-layer structure as in Example 1 were mixed by a mixer and melt-kneaded by an extruder to obtain pellets. 45 parts by weight of the pellets were added to 100 parts by weight of methyl methacrylate monomer with stirring, and the mixture was heated at 60 ° C.
After continuing stirring for 2 hours, the mixture was cooled to room temperature to obtain a syrup in which the multilayer elastic body was dispersed. Example 1 of this syrup
Cast polymerization was carried out in the same manner as above to obtain a cast plate. The obtained resin cast plate was evaluated. The results are shown in [Table 1].

Comparative Example 1 To 200 parts by weight of methyl methacrylate, 0.002 parts by weight of azobisisobutyronitrile was added, and the mixture was mixed at 80 ° C. for 3 days.
After heating for an hour, the mixture was cooled to room temperature to obtain a syrup in which methyl methacrylate was partially polymerized. The viscosity-average molecular weight of the methyl methacrylate polymer contained in this syrup was 930,000, and its content was 5% by weight. To 105.3 parts by weight of this partially polymerized syrup of methyl methacrylate, 15 parts by weight of the same multi-layer elastic body as in Example 1 was added and stirred to obtain a syrup in which the multi-layer elastic body was dispersed. This syrup was cast-polymerized in the same manner as in Example 1 to obtain a cast plate. The obtained resin cast plate was evaluated. The results are shown in [Table 1].

[0021]

[Table 1]

Claims (1)

[Claims] 1. A viscosity average molecular weight of 10,000 to 3,000 in 100 parts by weight of a monomer containing methyl methacrylate as a main component.
A method for producing a methacrylic resin cast plate, in which 5 to 50 parts by weight of a methyl methacrylate polymer of No. 00 is dissolved, and further, 1 to 50 parts by weight of a multilayer structure elastic body is dispersed and injected into a cell for polymerization.