JP2003292632A - Method for producing acrylic resin plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a resin plate with reduced strain without reducing productivity. <P>SOLUTION: In the method for producing an acrylic resin plate by casting a polymerizable raw material into a casting mold, and polymerizing and curing the polymerizable raw material, the viscosity of the polymerizable raw material is controlled according to the thickness of the acrylic resin plate in such a manner that (1) when the thickness is less than 8 mm, the viscosity is 0.12-0.36 Pas; (2) when the thickness is not less than 8 mm to less than 40 mm, the viscosity is 0.18-0.42 Pas; and (3) when the thickness is not less than 40 mm, the viscosity is 0.48-0.72 Pas. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an acrylic resin plate. 2. Description of the Related Art As a method for producing a resin plate such as an acrylic resin plate, a polymerizable material is poured into a mold, and the polymerizable material is polymerized and cured by immersing the mold in warm water or the like. Plate manufacturing methods are widely used. The acrylic resin plate is manufactured from a thin plate such as 1.5 mm to a thick plate such as 100 mm depending on the use. [0003] However, in the manufacturing method, when a thin plate or a thick plate is manufactured using the same polymerizable raw material, the thin plate requires a long time to be poured into a mold. There is a problem that the properties of the polymerizable material are reduced, and a trace of the flow of the raw material when the polymerizable raw material is injected into the mold is distorted. On the other hand, in the case of a thick plate, there is a problem that the polymerizable raw material in the mold convects due to heating during the polymerization curing, and the convection causes distortion. An object of the present invention is to provide a method for producing a resin plate having less distortion without lowering productivity. SUMMARY OF THE INVENTION The gist of the present invention is to provide a method for producing an acrylic resin plate by injecting a polymerizable material into a mold and polymerizing and curing the polymerizable material. In the production method, the viscosity of the polymerizable raw material is set to the following viscosity. (1) When the thickness is less than 8 mm, 0.12 to 0.36P
a · s (2) When the thickness is 8 mm or more and less than 40 mm, 0.18
(0.4) 0.48 to 0.72 when the thickness is 40 mm or more.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A mold used in the production method of the present invention comprises a pair of glass plates, a stainless steel plate whose surface is polished, and a gasket. Examples of the gasket include a vinyl chloride resin gasket, a polyethylene resin gasket, and a silicone rubber gasket. Examples of the shape of the gasket include a cross section having a hollow circular shape, a square shape, a round shape, a trapezoidal shape, and the like. The thickness and length are not particularly limited, and can be appropriately changed according to the thickness and area of the manufactured resin plate. The polymerizable raw material injected into the mold preferably contains at least 70% by mass of methyl methacrylate (hereinafter referred to as "MMA" as appropriate). Other polymerizable raw materials include acrylates such as methyl acrylate and ethyl acrylate, methacrylates other than MMA such as ethyl methacrylate, and methacrylic acid. The viscosity of the polymerizable material depends on the thickness of the acrylic resin plate to be manufactured. When the thickness of the acrylic resin plate is less than 8 mm, the viscosity of the polymerizable raw material is 0.12 to 0.36 Pa
-It is s. 0.20 to 0.28 Pa · s is preferable.
The lower limit of the thickness of the acrylic resin plate is preferably 1.5 mm. The thickness of the acrylic resin plate is 8 mm or more and 40 m
m, the viscosity of the polymerizable raw material is 0.18 to 0.4.
2 Pa · s. 0.26 to 0.34 Pa · s is preferable. When the thickness of the acrylic resin plate is 40 mm or more, the viscosity of the polymerizable raw material is 0.48 to 0.72 Pa · s.
It is. 0.56 to 0.64 Pa · s is preferable. The upper limit of the thickness of the resin plate is preferably 100 mm. As a method of adjusting the viscosity of the polymerizable raw material, a polymerization initiator such as 2,2'-azobisisobutyronitrile is added to MMA, and a part of the polymerization initiator is polymerized. There is a method of adjusting the viscosity of the polymerizable raw material by adjusting the molecular weight and the polymerization rate.
In actual production, it is also possible to prepare polymerizable raw materials which have been adjusted to a plurality of viscosities in advance, and to mix and use them. In order to polymerize the polymerizable raw material, 2,2′-azobisisobutyronitrile,
2′-azobis (2,4-dimethylvaleronitrile),
Azo polymerization initiators such as 2,2′-azobis (4-methoxy 2,4-dimethylvaleronitrile) and 1,1′-azobis (cyclohexane-1-carbonitrile), lauroyl peroxide, methyl ethyl ketone peroxide, It is preferable to contain a peroxide polymerization initiator such as diisopropyl peroxydicarbonate and dicyclohexaneperoxydicarbonate. 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. it can. In order to polymerize and cure the polymerizable raw material, it is preferable to polymerize and cure at 20 to 80 ° C., preferably 30 to 65 ° C. using water or air as a heat medium. The polymerization time is preferably from 0.5 to 200 hours. After this polymerization, 100 ° C.
It is preferable to further polymerize in a temperature range of from 140 to 140C, preferably from 120C to 135C. The polymerization time is preferably 1 hour or more. After polymerizing and curing the polymerizable raw material, the resin plate can be taken out by peeling the plate-like polymer from the mold. EXAMPLES (1) Method of Measuring Viscosity The viscosity of a polymerizable material was measured using a B-type viscometer manufactured by Tokyo Keiki Seisakusho in accordance with JIS K 7117-1. (2) Method of Measuring Polymerization Rate A polymerizable raw material is put in a solvent composed of normal hexane,
After the polymer insoluble in the solvent and the monomer soluble in the solvent are separated by filtration through a filter paper, the polymer on the filter paper is dried, and the solvent is removed to remove only the polymer, thereby obtaining a polymerizable raw material. The polymerization rate X was determined from a / M × 100 (% by mass) by setting the mass of M to M and the mass of the separated polymer to a. (3) Method of measuring weight average molecular weight A polymerizable raw material is dissolved in tetrahydrofuran, and gel permeation chromatography HP manufactured by Tosoh Corporation is used.
It measured using LC-8120GPC. T in the column
SK-GEL SUPER HM-H 6.0mmφ ×
150 mm, TSK-GUARDC for guard column
OLUMN SUPER H-H 4.6mmφ × 35
mm. Polystyrene was used as the standard polymer for the calibration curve. (4) A projector was set in front of measuring the distortion of the obtained resin plate, and an acrylic resin plate was set at a position 4 m away from the projector. A screen is placed 1 m behind the acrylic resin plate in parallel with the acrylic resin plate, and the light projected from the projector passes through the acrylic resin plate and is projected on the screen, and the light and shade of the projected light is observed. Thus, the presence or absence of distortion in the acrylic resin plate was determined. That is, it was determined that the acrylic resin plate having no shading in the light on the screen had no distortion, and the acrylic resin plate having shading in the light had distortion. [Example 1] Outer diameter 8.5 mm, wall thickness 2 mm
Size 12 through an endless gasket made of vinyl chloride
A mold was formed by laminating two tempered glass plates of 00 mm × 1200 mm × 10 mm. The MMA was heated in a SUS polymerization vessel equipped with a cooling pipe for the generated steam. When the temperature of the MMA reached 75 ° C., 2,2′-azobisisobutyronitrile was added to 100 parts by mass of the MMA. 0.0022 parts by mass was added, and the heating was further continued. When the temperature of the MMA reached 95 ° C., the heating was stopped. After keeping the heating stopped for 10 minutes, the polymerization vessel was put into ice water and cooled to room temperature. The viscosity of the obtained polymerizable raw material (1) is 0.12 Pa · s,
The conversion was 6% by mass, and the weight average molecular weight of the polymer was 8%.
00,000. Polymerization was carried out in the same manner as described above, except that the amount of 2,2'-azobisisobutyronitrile was 0.0006 parts by mass and the holding time was 20 minutes. The viscosity of the obtained polymerizable raw material (2) is 0.6 Pa · s,
The conversion was 7% by mass, and the weight average molecular weight of the polymer was 2,400,000. Next, 60 parts by mass of the polymerizable material (1) having a viscosity of 0.12 Pa · s and 40 parts by mass of the polymerizable material (2) having a viscosity of 0.6 Pa · s are uniformly stirred, and the mixture 10
With respect to 0 parts by mass, 2,2 ′-(2,4
-Dimethylvaleronitrile) 0.01 part by mass, Aerosol OT (manufactured by American Cyanamide Co., Ltd.) as a release agent
0.02 parts by mass was added, and the mixture was uniformly stirred again to obtain a polymerizable material having a viscosity of 0.24 Pa · s. 9100 g of this polymerizable material was injected into the mold. The time required for injection into the mold was 40 seconds.
In the early stage of the polymerization, polymerization was carried out for 3 hours in a water bath at 65 ° C.
Then, polymerization was carried out for 3 hours in an air bath at 125 ° C., and the plate-like polymer was peeled off from the mold to obtain an acrylic resin plate having a thickness of 5 mm. [Example 2] A size of 120 mm was passed through an endless gasket made of vinyl chloride having an outer diameter of 41 mm and a thickness of 7 mm.
A mold was formed by laminating two tempered glass plates of 0 mm × 1200 mm × 10 mm. Next, 90 parts by mass of the polymerizable raw material (2) having a viscosity of 0.6 Pa · s and 10 parts by mass of MMA are uniformly stirred, and 100 parts by mass of the mixture is mixed with 2,2- 0.0035 parts by mass of azobis (4-methoxy 2,4-dimethylvaleronitrile) and 0.02 parts by mass of aerosol OT (manufactured by American Cyanamide Co.) as a release agent were added, and the mixture was stirred uniformly and the viscosity was 0.3 Pa. * The polymerizable raw material of s was obtained. The polymerizable material is placed in a mold in 5130
0 g was injected. The time required for injection into the mold was 62 seconds. In the early stage of polymerization, polymerization was carried out in a water bath at 40 ° C. for 20 hours, then polymerization was carried out for 3 hours in a water bath at 65 ° C.
After polymerizing for 2 hours in an air bath at 125 ° C., polymerizing for 3 hours in an air bath at 125 ° C., the plate polymer was peeled off from the mold to obtain an acrylic resin plate having a thickness of 30 mm. [Example 3] Outer diameter 68 mm, wall thickness 11 mm
Size 12 through an endless gasket made of vinyl chloride
A mold was formed by laminating two tempered glass plates of 00 mm × 1200 mm × 10 mm. Next, 2,100 as a polymerization initiator was added to 100 parts by mass of the polymerizable raw material (2) having a viscosity of 0.6 Pa · s.
0.0015 parts by mass of azobis (4-methoxy 2,4-dimethylvaleronitrile), Aerosol O as a release agent
0.02 parts by mass of T (manufactured by American Cyanamid Co.) was added and stirred uniformly. The viscosity of the polymerizable material after stirring is 0.1.
It was 6 Pa · s. Put the polymerizable material in a mold
6,500 g were injected. The time required for injection into the mold was 48
Seconds. In a water bath at 40 ° C. in the early stage of polymerization, 62
After polymerizing for 3 hours in a 70 ° C. air bath, polymerizing for 2 hours in a 95 ° C. air bath and 3 hours in a 125 ° C. air bath, the plate polymer was peeled from the mold, and the A 50 mm acrylic resin plate was obtained. [Comparative Example 1] The mixing ratio was changed and 0.6 Pa
An acrylic resin plate was manufactured in the same manner as in Example 1 except that the polymerizable raw material adjusted to have a viscosity of s was used. The time required for injection into the mold was 276 seconds. [Comparative Example 2] The mixture ratio was changed to 0.03 Pa
An acrylic resin plate was manufactured in the same manner as in Example 2 except that the polymerizable raw material adjusted to have a viscosity of s was used. The time required for injection into one set of molds was 32 seconds. The distortion of the acrylic resin plates obtained in Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 was measured. The light transmitted through the acrylic resin plates manufactured in Examples 1 to 3 was an acrylic resin plate having no density and no distortion. The light transmitted through the acrylic resin plate manufactured in Comparative Example 1 was a dark and distorted acrylic resin plate. The light transmitted through the acrylic resin plate produced in Comparative Example 2 was a dark and light, distorted acrylic resin plate. According to the method for producing a resin plate of the present invention, an acrylic resin plate with less distortion can be provided without lowering productivity.

   ────────────────────────────────────────────────── ─── Continuation of front page    F term (reference) 4F071 AA32X AA33 AA33X AA88                       AG02 AG32 BA09 BB01 BB12                       BC03 BC17                 4J100 AJ02P AL03P CA01 CA04                       DA09 FA17 FA27 FA47 GC00                       GD19

Claims (1)

Claims: 1. A method for producing an acrylic resin plate, in which a polymerizable material is injected into a mold and the polymerizable material is polymerized and cured, wherein the viscosity of the polymerizable material is determined according to the thickness of the acrylic resin plate. Production method for obtaining a viscosity of (1) When the thickness is less than 8 mm, 0.12 to 0.36P
a · s (2) When the thickness is 8 mm or more and less than 40 mm, 0.18
(0.4) 0.48 to 0.72 when the thickness is 40 mm or more.
Pa · s