JP2003277404A - Method for producing resin plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a resin plate having a good see- through transparent visually recognizing property without having a surface defect derived from the generation of unevenness on the surface of the resin plate caused by the partial peeling off of the resin plate from a mold in producing the resin plate on forming the mold by laminating 2 pieces of plates mediated by a gasket and polymerizing and curing a polymerizable raw material in the mold to produce the resin plate. <P>SOLUTION: This method for producing the resin plate comprises pouring the polymerizable raw material into the mold having the gasket and polymerizing and curing the polymerizable raw material is provided where the gasket surface layer is not swollen or dissolved with the polymerizable raw material, and removing the gasket from the mold at a time point within a range of 20-80 mass % polymerization rate of the polymerizable raw material. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for manufacturing a resin plate.

[0002]

2. Description of the Related Art Acrylic resin plates are widely used in applications such as water tanks and aircraft windshields where importance is attached to their visibility because of their excellent transparency.
As a method for producing a resin plate such as an acrylic resin plate, a method for producing a resin plate by injecting a polymerizable raw material into a mold having a gasket and polymerizing and curing the polymerizable raw material by immersing the mold in hot water or the like Is widely used. When used in the above-mentioned applications, it is necessary to reduce the distortion of the resin plate so that the image seen through the resin plate is not distorted. As a method of reducing strain, it is necessary to reduce the difference between the ambient temperature during polymerization and curing and the temperature inside the mold to reduce convection of the polymerizable raw material.

[0003]

However, when the difference between the ambient temperature and the temperature inside the mold is reduced, the polymerization time becomes longer, and the swelling of the gasket by the polymerizable raw material proceeds. As the gasket swells, it becomes longer,
There was a case where the polymer material leaked out of the mold and the polymerizable raw material leaked out of the mold.

Therefore, there has been developed a method for preventing the swelling of the gasket and preventing the polymerizable raw material from leaking from the mold by coating the surface layer of the gasket with a material which does not swell the polymerizable raw material. , A sink defect occurs in which the mold and the resin plate are separated during the polymerization. Here, the sink mark defect is a surface defect in which the mold and the resin plate are partially separated to form irregularities on the surface of the resin plate.

An object of the present invention is to provide a method for producing a resin plate which is free from sink marks and has good transmission visibility.

[0006]

The gist of the present invention is to provide a method for producing a resin plate in which a polymerizable raw material is injected into a mold having a gasket, and the polymerizable raw material is polymerized and cured. In the method for producing a resin plate, which is a layer that does not swell or dissolve, and in which the gasket is removed from the mold when the polymerization rate of the polymerizable raw material is within the range of 20 to 80 mass%.

It is preferable to remove the gasket from the mold when the polymerization rate of the polymerizable raw material is within the range of 20 to 70% by mass.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The mold used in the manufacturing method of the present invention has a gasket. Examples of the gasket include vinyl chloride resin-based gaskets, silicone rubber gaskets, polyethylene gaskets, and the like.

The surface layer of the gasket used in the production method of the present invention must be a layer that does not swell or dissolve in the polymerizable raw material. When a polymerizable raw material containing methyl methacrylate as the main component is used, PET or nylon is preferably used as the material forming the surface layer that does not swell or dissolve in methyl methacrylate.

As a method for providing a layer made of PET or nylon on the surface layer of a gasket made of vinyl chloride resin or the like, there is a method of winding a film made of PET or nylon around the gasket or a gasket made of PET or nylon as a surface layer. A method of co-extruding with other resin constituting the inside can be mentioned.

Examples of the shape of the gasket include a circular cross section, a square shape, a circular shape, a trapezoidal shape and the like. It is preferably hollow. The thickness and length are not particularly limited, and can be appropriately changed depending on the thickness and area of the resin plate to be manufactured.

Examples of the mold used in the manufacturing method of the present invention include a pair of glass plates and a stainless plate whose surface is polished.

The polymerizable raw material injected into the mold having the gasket is methyl methacrylate (hereinafter referred to as "MMA" as appropriate).
That of 70% by mass or more is preferable. Other polymerizable raw materials include acrylic acid esters such as methyl acrylate and ethyl acrylate, methacrylic acid esters other than MMA such as ethyl methacrylate, and methacrylic acid. The polymerizable raw material may be a syrup-shaped polymerizable raw material composed of a polymer such as MMA and MMA. In that case, the polymerization rate of the polymerizable raw material needs to be 19% by mass or less.

To polymerize the polymerizable raw material, 2,2'-azobisisobutyronitrile, 2,2'-
2 '-(2,4-dimethylvaleronitrile), 2,2'
-Azo polymerization initiators such as azobis (4-methoxy2,4-dimethylvaleronitrile) and 1,1'-azobis (cyclohexane-1-carbonitrile), lauroyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxydiene It is preferable to add a peroxide type polymerization initiator such as carbonate or dicyclohexane peroxydicarbonate.

Further, in the method for producing a resin plate of the present invention, various known additives such as an ultraviolet absorber, an antioxidant and a release agent may be contained in the polymerizable raw material, if necessary. .

To polymerize and cure the polymerizable raw material, water is used as a heat medium at 20 ° C to 80 ° C, preferably 30 ° C to 6 ° C.
It is preferable to polymerize and cure in a temperature range of 5 ° C. The polymerization time is preferably 0.5 to 200 hours.

After this polymerization, 100 ° C. in a hot air oven.
It is preferable to carry out post-polymerization in a temperature range of ˜140 ° C., preferably 120 ° C. to 135 ° C. The post-polymerization time is preferably 1 hour or more.

In the production method of the present invention, it is necessary to remove the gasket from the mold when the polymerization rate of the polymerizable raw material is within the range of 20% by mass to 80% by mass. The reason is that when the polymerization rate of the polymerizable raw material exceeds 80% by mass, a sink defect occurs. The polymerization rate of the polymerizable raw material at the time of removing the gasket is preferably 70% by mass or less, and more preferably 65% by mass or less. The lower limit of the polymerization rate is preferably 25% by mass or more, and more preferably 30% by mass or more.

The method for measuring the polymerization rate of the polymerizable raw material includes the following methods.

During the polymerization and curing, the mold is taken out and immersed in ice water to stop the polymerization and curing. Next, the template is decomposed, the polymerizable raw material during polymerization and curing is taken out, put in a solvent such as normal hexane, and the polymer insoluble in the solvent and the monomer soluble in the solvent are filtered with a filter paper. After the separation, the polymer on the filter paper is dried and the solvent is removed to take out only the polymer, and the mass of the polymerization intermediate is M, and the mass of the separated polymer is a. The rate X can be calculated from a / M × 100 (mass%).

As a method for removing the gasket from the mold, there is a method in which a metal rod-shaped object having a finely pointed tip is pierced on the outer peripheral portion of the gasket and the metal rod-shaped object is pulled to extract the gasket to the outside of the mold.

After the polymerizable raw material is polymerized and cured, the plate polymer can be peeled from the mold to take out the resin plate.

The thickness of the resin plate is preferably 2 to 120 mm.

Since the resin plate obtained by this method has no sink mark defect and the strain is reduced, it is suitable for applications such as water tanks and aircraft windshields where importance is attached to the visual recognition of transmission.

[0025]

Examples (1) Method of evaluating transmission visibility The obtained acrylic resin plate was vertically stood, and a grid board was installed 8 m ahead of it in parallel with the acrylic resin plate.
The grid board was a blackboard with white lines drawn vertically and horizontally at intervals of 25 mm. For the transmission visibility, the white line of the grid board was visually observed from 2 m behind the acrylic plate through the acrylic resin plate. That is, when viewed through an acrylic resin plate with good transparency and visibility, the white lines of the grid board are not distorted, and when viewed through an acrylic resin plate with poor transparency and visibility, the white lines of the grid board appear distorted. .

[Example 1] With respect to 100 parts by mass of methyl methacrylate, 0.002 part by mass of 2,2 '-(2,4-dimethylisovaleronitrile) as a polymerization initiator and aerosol OT (American as a release agent) (Made by Cyanamide)
0.02 parts by mass was added and uniformly stirred to obtain a polymerizable raw material.

The outer circumference of a hollow circular vinyl chloride resin tube having an outer diameter of 50 mm and an inner diameter of 36 mm is 50 mm in cross section.
Two sets of molds each consisting of a gasket covered with a PET film of μm and two tempered glass plates having a size of 2000 × 2000 × 10 mm were formed, and a polymerizable raw material was injected into each of them. It was immersed in a 40 ° C. water bath at the beginning of the polymerization. After the lapse of 130 hours, in one of the molds, an L-shaped metal rod having a fine tip was pierced into the outer peripheral portion of the gasket, and the metal rod was pulled to pull the gasket out of the mold.

When the polymerization rate of the polymerizable raw material in the other mold was measured, it was 50% by mass.

The mold from which the gasket had been removed was subsequently immersed in a water bath at 40 ° C. and polymerized for 40 hours. Then, it polymerized in a 130 degreeC air bath for 3 hours, the plate-shaped polymer was peeled from the mold, and the 30-mm-thick acrylic resin board was obtained.

There were no sink marks on this acrylic resin plate. The white line of the grid board seen through the acrylic resin plate was not distorted and the transmission visibility was good.

[Comparative Example 1] In the same manner as in Example 1, 40
The gasket was removed from one of the molds when it was immersed in a water tank at ℃ for 170 hours.

When the polymerization rate of the polymerization raw material in the other mold was measured, it was 85% by mass. After that, 130 ℃
Polymerization was performed for 3 hours in the air bath, and the plate polymer was peeled from the mold to obtain an acrylic resin plate having a plate thickness of 30 mm.

A sink defect was generated in this acrylic resin plate. The white lines of the grid board seen through the sink mark defects of the acrylic resin plate looked distorted, and the transmission visibility was poor.

[0034]

According to the method for producing a resin plate of the present invention, it is possible to provide an acrylic resin plate which is free from sink marks and has good transmission visibility.

Claims (2)

[Claims] 1. In a method for producing a resin plate in which a polymerizable raw material is injected into a mold having a gasket and the polymerizable raw material is polymerized and cured, the gasket surface layer is a layer which does not swell or dissolve in the polymerizable raw material, The polymerization rate of the polymerizable raw material is 2
A method for producing a resin plate, wherein the gasket is removed from the mold at a time point within the range of 0 to 80% by mass. 2. The polymerization rate of the polymerizable raw material is 20 to 70% by mass.
The manufacturing method according to claim 1, wherein the gasket is removed from the mold at a time within the range.