JPH05140203A - Production of acrylic resin plate - Google Patents

Abstract

PURPOSE:To produce a thick acrylic resin plate at high productivity. CONSTITUTION:A process for producing an acrylic resin plate comprising pouring a solution of a starting material based on methyl methacrylate into a mold and polymerizing the solution, wherein part of the solution is poured into the mold to start polymerization and the remainder of the solution is poured onto the upper surface of the polymerizate in the course of the polymerization to continue the polymerization.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an acrylic resin plate containing methyl methacrylate as a main component. In particular, the present invention relates to a manufacturing method suitable for forming a resin plate having a large wall thickness.

[0002]

2. Description of the Related Art Conventionally, as a method for manufacturing an acrylic resin plate, a method by casting polymerization is generally used. For example, there is a method for producing a batch-type cast polymer plate as described in "Acrylic Resin", page 27 of Plastic Materials Course. In this manufacturing method, first, methyl methacrylate is used as a main component, a polymerization initiator, a coloring agent, and the like are mixed, and prepolymerization is performed to manufacture syrup. After that, along the perimeter between two sheets of inorganic glass, the entire amount of syrup prepared in the previous step was injected and enclosed in a mold holding a gasket, and polymerization was completed in an air bath or water bath. It is a manufacturing method in which the resin plate is taken out after being opened and the resin plate is taken out.

Also, Japanese Patent Publication No. 46-41602 and 49-35818.
JP-A-49-36944 and the like continuous casting polymerization method, a polymerizable liquid composition such as methyl methacrylate is injected from one end between continuous moving bands, and the moving bands are run together. It is a manufacturing method in which the resin plate is polymerized and the resin plate is taken out from the other end.

[0004]

In the manufacturing method by casting polymerization, polymerization is usually carried out at a temperature of 60 to 80 ° C. to manufacture a relatively thin plate. However, in the case of producing a thick plate, if polymerized under the same conditions, heat removal commensurate with the heat of polymerization cannot be removed, the temperature rises, and the contents become boiled to generate bubbles, Does not form a homogeneous plate. Therefore, if the amount of the polymerization initiator is reduced and the temperature is lowered to allow slow polymerization, the polymerization time naturally becomes long. Even in the manufacturing method by continuous casting polymerization, since polymerization is performed with the continuous traveling of the moving band, it is necessary to shorten the polymerization time. It was unsuitable. Therefore, a method of manufacturing a thick plate by bonding a plurality of plates with an adhesive has been proposed, as described in, for example, Japanese Patent Publication No. 62-42951.

The present invention provides a method for efficiently producing a thick plate only by casting polymerization without performing operations such as bonding.

[0006]

The present invention provides a method for producing a resin plate obtained by polymerizing while pouring a polymerization raw material liquid containing methyl methacrylate as a main component into a mold. Hereinafter, the present invention will be described in detail.

The polymerization raw material liquid containing methyl methacrylate as a main component used in the present invention is methyl methacrylate alone or 50% by polymerization or more, preferably 70% by polymerization.
It is a mixture of the above-mentioned monofunctional or polyfunctional unsaturated monomer copolymerizable with methyl methacrylate and a radical initiator. If the methyl methacrylate content is less than 50% by weight, it is difficult to develop the transparency and mechanical strength, which are the characteristics of so-called polymethyl methacrylate.

Examples of the copolymerizable monofunctional unsaturated monomer include, for example, methacrylic acid esters such as ethyl methacrylate, propyl methacrylate, butyl methacrylate and benzyl methacrylate: methyl acrylate, ethyl acrylate, acryl. Acrylic acid esters such as propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate:
Unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid and itaconic acid, acid anhydrides such as maleic anhydride and itaconic anhydride: 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, monoglycerol acrylate, Hydroxyl group-containing monomers such as 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, monoglycerol methacrylate: Nitrogen-containing monomers such as acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, diacetone acrylamide, and dimethylaminoethyl methacrylate. There are monomers: epoxy group-containing monomers such as allyl glycidyl ether, glycidyl acrylate, and glycidyl methacrylate: styrene-based monomers such as styrene and α-methylstyrene.

Examples of the polyfunctional monomer include ethylene glycol dimethacrylate, ethylene glycol diacrylate, 1,3-butylene glycol dimethacrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, divinylbenzene and triallyl shear. Nurate, allyl cinnamate, allyl methacrylate, allyl acrylate, allyl cinnamate, allyl sorbate, diallyl phthalate, diallyl malate and the like, preferably allyl methacrylate,
Allyl acrylate, allyl cinnamate, 1,3-butylene glycol dimethacrylate and the like can be mentioned.

The type and amount of the copolymerizable monofunctional or polyfunctional unsaturated monomer can be appropriately selected according to the intended properties of the resin plate.

As the radical polymerization initiator, for example, 2,
Azo compounds such as 2′-azobis (isobutyronitrile), 2,2azobis (2,4dimethylvaleronitrile), 2,2azobis (2,4-dimethyl, 4-methoxyvaleronitrile) and diisopropyl purge carbonate, Benzoyl peroxide, lauroyl peroxide,
There are organic peroxides such as tertiary butyl perbenzoate and tertiary butyl per 2-ethylhexanoate. A redox polymerization initiator such as an organic peroxide and an amine acid can also be used. The amount of these polymerization initiators used is about 0.001 to 1% by weight, preferably 0.01 to 0.7% by weight, in the polymerization stock solution.

Further, if necessary, a heat stabilizer, an ultraviolet absorber, a colorant, a plasticizer, a flame retardant, various fillers and the like may be added to the above-mentioned monomer as long as the amount is within the range for achieving the object of the present invention. Additives can be mixed and used.

In this method, the raw material liquid may be a monomer state of an acrylic polymerization raw material liquid containing methyl methacrylate as a main component, or a syrup containing a partial polymer may be used.

The mold of the present invention does not need to have a particularly peculiar structure as long as the desired resin plate can be molded. The bottom surface, the side surface, or the upper surface may be heated and cooled, and the structure other than the upper surface may be an airtight structure so that the raw material liquid does not leak, and the structure need not follow the polymerization shrinkage. Resin, glass, or metal is applied as the material.

As a method for injecting the raw material liquid into the mold to polymerize, first of all, about half or less of the whole raw material liquid and about 15 mm or less of the thickness of the resin plate are put in as an initial injection. This initial injection can be at any location on the formwork.
The polymerization is started by heating and heating the mold. The polymerization temperature is determined mainly by the type and amount of the polymerization initiator used and the type of the monomer, but is 10 to 150 ° C.
It is a degree.

Some amount of initial injection, for example 20% by weight
From the time when the polymerization has been completed for a certain degree or more, the raw material liquid is additionally injected. This additional injection is put on the upper surface of the initial injection, that is, so as to overlap. The additional injection may be performed gradually and continuously or intermittently. In any case, the injection rate is set to a rate commensurate with the progress of polymerization of the already injected portion. The progress of polymerization can be determined by a known determination method, that is, the amount of heat generated.

The exothermic heat of polymerization can be removed by the sensible heat of the raw material liquid for this additional injection, so that the polymerization can proceed more quickly. Also, the composition of the raw material for additional injection is different, and the resin plate with unique mechanical properties and optical properties, for example, the surface part has high rigidity and is not easily scratched, and has a high impact resistant part inside Plate or a plate whose front can be seen as fluctuating due to a combination of portions having different light refractive indices.

The upper surface of the mold during polymerization while injecting the polymerization raw material may be in a free surface state which is not in contact, or the upper surface of the mold is movable and rises as the polymerization raw material is injected. The upper surface may be in contact as long as it is one.

[0019]

In the method for producing a resin plate according to the present invention, the polymerization is performed while injecting the raw material liquid, so that the temporary generation of heat of polymerization can be suppressed and the heat of polymerization can be removed by the sensible heat of the raw material liquid. The polymerization time can be shortened, and a thick resin plate, particularly a resin plate having a thickness of 10 mm or more can be manufactured with high productivity. Among them, it is suitable for thick plates of about 20 mm to 70 mm. Moreover, not only a single plate but also a single plate can be provided with a distribution of a plurality of compositions, and more functions can be added.

[0020]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 340 × 235 × 70 with an oil jacket on the bottom
A mm container made of stainless steel was prepared. As a lid of this stainless steel container, a stainless steel plate provided with a raw material polymerization liquid drop lowering port was mounted on the upper surface with Teflon as a packing to complete a formwork. Set the temperature of the jacket on the bottom of the formwork to 8
The mixture was heated to 0 ° C., and 800 cc of a raw material polymerization solution in which 0.014% by weight of 2,2′-azobis (isobutyronitrile) was dissolved in methyl methacrylate was added to initiate polymerization. After 3 hours, the raw material polymerization liquid was added from the dropping port on the upper surface of 400 cc,
After that, the raw material polymerization liquid was added 7 times every 1.5 hours to carry out polymerization. The total of the raw material polymerization liquids is 2
It was 950cc. 1.5 hours after the last addition, the jacket temperature on the bottom surface was raised to 1280 ° C. over 1.5 hours, and then the temperature was maintained for 1.5 hours. After cooling, the mold was removed and a transparent resin plate having a thickness of 30 mm and free from foaming was obtained. It took 19 hours to manufacture this resin plate including the cooling time.

Example 2 The same mold and raw material polymerization solution as in Example 1 were prepared. The temperature of the jacket on the bottom of the mold was heated to 80 ° C., and 800 cc of the raw material polymerization liquid was added to start polymerization. After 3 hours, the raw material polymerization liquid was added from the dropping port on the upper surface of 400 cc, and thereafter, 250 cc of the raw material polymerization liquid was added 18 times every 2.8 hours for polymerization. The total raw material polymerization liquid was 5700 cc.
Finally, 3 hours after the raw material polymerization solution was added, the jacket temperature on the bottom surface was raised to 130 ° C. over 8 hours, and the temperature was maintained for 3.5 hours and then cooled. The mold was removed and a 55 mm thick transparent resin plate without foam was obtained. It took 70 hours including the cooling time to manufacture this resin plate.

Comparative Example 1 Example 1 except that 2950 cc of the raw material polymerization liquid was injected at one time
When polymerization was carried out under the same conditions as above, heat was generated rapidly after 1 hour and the entire surface of the resin plate was foamed.

Comparative Example 2 A mold having a gasket having a thickness of 30 mm sandwiched between two 345 × 240 mm stainless steel plates was prepared and the same raw material polymerization solution as in Example 1 was prepared. 2950
When cc was poured at one time, polymerization was performed in the hot water to find a temperature condition where foaming did not occur, and it was found that the temperature was 57 ° C or lower. After polymerizing at about 57 ° C. for 100 hours, the temperature was raised to 120 ° C. over 1.5 hours, and then the temperature was maintained for 1.5 hours. The resin plate taken out after cooling had a thickness of 30 mm and no defect was found. It took 103 hours to manufacture this resin plate, including the cooling time. About 5 compared to Example 1.
Double the polymerization time was required.

Comparative Example 3 When a polymerization temperature at which foaming did not occur was searched for in the same manner as in Comparative Example 2 except that the stock polymerization stock solution poured at one time was 5700 cc, it was found to be a temperature of 50 ° C. or lower.
Polymerize at about 50 ° C for 172 hours, then 1 hour over 1.5 hours
The temperature was raised to 20 ° C., and the temperature was maintained for 1.5 hours. The resin plate taken out after cooling had a thickness of 55 mm and had no defects.
It took 175 hours including the cooling time to manufacture this resin plate. The polymerization time required was about 2.5 times longer than that in Example 2.

Claims (1)

[Claims] 1. In a method for producing an acrylic resin plate by injecting a polymerization raw material liquid containing methyl methacrylate as a main component into a mold to polymerize, a part of the polymerization raw material liquid is initially injected, A method for producing an acrylic resin plate, characterized by starting polymerization and injecting the rest of the polymerization raw material liquid into the upper surface from the middle of the progress of the polymerization.