JP3269180B2 - Method for producing methacrylic resin multilayer board - Google Patents

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 a methacrylic resin plate having a multilayer structure.

[0002]

2. Description of the Related Art Methacrylic resins have excellent properties such as transparency, weather resistance and mechanical properties and are used for lighting materials, signboards, displays, building materials and the like. Among them, methacrylic resin plates having a multilayer structure are usefully used for signboards, display boards, name tags, and the like.

Various methods have been proposed for producing a methacrylic resin plate having a multilayer structure. For example, Tokuhei 01-473
In the 08 publication, methacrylic resin syrup containing a light diffusing agent in a cell using a methacrylic resin plate on at least one side, cast polymerization under conditions such that the heat generation peak time of the initial polymerization is 60 minutes or more, A method for manufacturing a light-diffusing methacrylic resin plate, characterized in that a thin layer of methacrylic resin containing a light-diffusing agent is integrally formed on the methacrylic resin plate.

In Japanese Patent Publication No. 01-47310, a transparent acrylic film is previously adhered to the inner surface of at least one mold, and a cell for casting polymerization is formed by using the mold and a gasket. There is disclosed a method for producing an acrylic resin diffusion plate, wherein an acrylic monomer containing a light diffusing agent or a partial polymer thereof is injected into a cell and polymerized and cured.

In Japanese Patent Publication No. 01-47307, a monomer or a partial polymer having the same composition as that of an acrylic synthetic resin plate is applied to a significant surface of a mold to form a thin acrylic synthetic resin layer. An acrylic film containing a light-diffusing agent is continuously pressed on to obtain one surface of the mold, and then opposed to the other mold surface at a constant distance via a gasket, and an acrylic synthetic film is formed in the gap. A method for producing an acrylic synthetic resin plate having a light diffusion layer therein, wherein an acrylic monomer or a partial polymer thereof, which is a raw material of the resin plate, is injected and polymerized and cured.

Japanese Unexamined Patent Publication (Kokai) No. 64-81801 discloses an acrylic resin sheet in which a colored coating film composed of an acrylic resin and a colorant is formed on a part or the whole of one surface of the acrylic resin sheet. Is fixed to one or both sides of a mold having two opposing surfaces with the surface of the colored coating inside, and a polymerizable liquid containing an acrylic monomer as a main component is injected into the mold. A method for producing a colored acrylic resin cast plate characterized by polymerizing is disclosed.

[0007]

[Problems to be solved by the invention]
The method described in JP-A-01-7308 uses a methacrylic resin plate as a cell. Since the methacrylic resin plate has a heat resistance temperature of about 100 ° C., it is difficult to maintain the original shape of the cell when exposed to a high temperature during polymerization, and the obtained multilayer methacrylic plate warps or the thickness accuracy of the layer is good. May not be possible. In addition, since the methacrylic resin plate used as a cell is exposed to a high-temperature water bath or air bath, the surface smoothness may be impaired. In addition, Tokuhei 01-473
In each of the methods described in Japanese Patent Publication No. 10 and Japanese Patent Publication No. H01-47307, an acrylic film is used, and a methacrylic resin multilayer board having a thick layer cannot be obtained. When a methacrylic resin multilayer board having a thin layer is used as a signboard, it is difficult to give a dark color. In either method, it is necessary to attach an acrylic film to the surface of the mold using an acrylic resin monomer or the like, which is industrially disadvantageous. Further, in the method disclosed in Japanese Patent Application Laid-Open No. 64-81801, the temperature of the acrylic monomer is high at the polymerization stage, and the contact state in the mold of the acrylic resin sheet is uneven. Is easily impaired. In addition, in any of the above methods, when using an acrylic monomer or a syrup containing a coloring component,
Since the coloring components are not uniformly dispersed, a colored methacrylic resin multilayer board having good appearance cannot be obtained.

According to the present invention, the range in which the thickness of the layer can be controlled is wide, the smoothness of the surface of the resulting methacrylic resin multilayer board is good, and the color when adding a coloring component such as a pigment is uniform and the appearance is uniform. An object of the present invention is to provide a method for producing a good methacrylic resin multilayer board.

[0009]

That is, the present invention uses a cell in which a methacrylic resin plate is provided on at least one side of the cell and injects and polymerizes a methacrylic syrup into the cell to produce a methacrylic resin multilayer plate. In the method, the methacrylic resin plate and the methacrylic syrup, as a unit constituting either or both of the methacrylic syrup, by adding a copolymerizable ethylenically unsaturated monomer in addition to methyl methacrylate, the methacrylic resin plate and methacrylic The constitutional unit composition of the syrup is different , and
The surface of the cell in contact with the methacrylic resin plate becomes a matte surface
It is intended to provide a method for producing a methacrylic resin multilayer board characterized by comprising:

The methacrylic resin plate used in the present invention is a methacrylic resin composed of methyl methacrylate alone or a copolymer of 80% by weight or more of methyl methacrylate and another copolymerizable ethylenically unsaturated monomer. Plate.

Examples of the copolymerizable ethylenically unsaturated monomers include monofunctional monomers such as methacrylates other than methyl methacrylate, acrylates, styrene, acrylonitrile and acrylamide; glycol dimethacrylate, allyl Methacrylates such as methacrylate, trimethylolpropane trimethacrylate, and neopentyl glycol dimethacrylate; acrylates such as glycol diacrylate, trimethylolpropane triacrylate, and neopentyl glycol diacrylate; divinylbenzene, diallyl phthalate, and the like Of a polyfunctional monomer. Among them, methacrylic acid or acrylic acid ester of an alcohol having 4 or more carbon atoms is particularly preferable.

The methacrylic resin plate may be manufactured by any method, and examples thereof include a cast plate, an extruded plate, and a continuous cast plate. The thickness of the methacrylic resin plate is approximately 0.5 to 100 mm. Preferably 1 to 50 mm
It is. It may be colored.

[0013] The methacrylic syrup is a monomer containing a polymer, which is composed entirely of methyl methacrylate units alone or containing at least 80% by weight of methyl methacrylate units and other copolymerizable ethylenically unsaturated monomers. It consists of body units. The content of the polymer is 1 to 50% by weight,
Preferably it is 5 to 30% by weight. In addition, a well-known polymerization initiator is contained. Further, if necessary, other additives are mixed.

The other copolymerizable ethylenically unsaturated monomer units are as described above.

The additives include known light diffusing agents, coloring agents, reinforcing agents, fillers, release agents, stabilizers, ultraviolet absorbers,
Examples include antioxidants, antistatic agents, flame retardants and the like. As the coloring agent, there are a dye used for so-called coloring, a pigment and a white pigment used also as a light diffusing agent, and its concentration is about 0.1 to 5% by weight.

[0016] As the unit further constituting the methacrylic resin plate and methacrylic syrup, by the inclusion of either or both copolymerizable with methyl methacrylate in the ethylenic unsaturated monomer units, methacrylic resin plate and a methacrylic Make a difference in the composition of the units that make up the system syrup. The constituent unit refers to a combination of a monomer unit and a monomer unit which is a polymer.

[0017] The difference in the composition of the constituent units means that the difference between the contents of the copolymerizable ethylenically unsaturated monomer units in the methacrylic resin plate and the methacrylic syrup is 1% by weight.
Say that's all. If the difference in the content of the monomers other than methyl methacrylate is less than 1% by weight, when the coloring component is used in the methacrylic syrup, the coloring component does not disperse uniformly, and a methacrylic resin multilayer board having a good appearance is obtained. I can't get it.

The cell used in the present invention has two plates and a gasket sandwiched between the plates. The material is not particularly limited, and glass, stainless steel, or the like is used. Among them, those in which the inner surface of the cell in contact with the methacrylic resin plate has a matte surface are preferable because of their excellent surface smoothness.

The methacrylic resin plate is provided on at least one side of the cell. If the methacrylic resin plate is provided on both surfaces, a three-layer plate is obtained. In this case, the methacrylic resin plates may be the same or different.

The methacrylic syrup is injected into the cell space. The polymerization after the injection is performed by a known method called a so-called cell casting method. That is, the cell after the injection is heated and polymerized in a water bath or an air bath. The polymerization conditions are not particularly limited, but are usually 0 to 150 ° C, preferably 50 to 100 ° C.
Do with.

After the polymerization, the cell is disassembled to obtain a methacrylic resin multilayer board.

[0022]

According to the present invention, a methacrylic resin multilayer plate having good plate thickness ratio accuracy, surface condition, pigment dispersibility and low warpage can be obtained. The methacrylic resin multilayer board obtained by the present invention is used for engraving materials, display materials, signboards, screens and the like.

[0023]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. The evaluation was performed by the following method. Surface condition: The surface of the methacrylic resin multilayer board was visually observed and judged. -Thickness distribution: The thickness of each layer on the outer periphery of the methacrylic resin multilayer board of 300 mm square was measured at 50 mm intervals, and the maximum value and the minimum value were shown. -Warpage: A 300 mm square methacrylic resin multilayer board was placed on a flat surface with the convex surface facing down, and the distance between both ends and the flat surface was measured. Coloring uniformity: The transmission color of the obtained methacrylic resin multilayer board was visually observed and judged.

Example 1 (Reference) On a glass plate having a thickness of 10 mm and a square of 300 mm, 98% by weight of methyl methacrylate unit and 2% by weight of a unit of 2-ethylhexyl acrylate, and a colorless transparent methacryl having a thickness of 3 mm and a square of 300 mm A resin plate was installed. On this methacrylic resin plate, place a glass plate of 1 mm in thickness and a glass of the same size as that of the vinyl chloride gasket.
A cell with a space of mm was created. The following syrup was poured into this space. Syrup composition ・ Methyl methacrylate 80 parts by weight ・ Polymethyl methacrylate 20 parts by weight ・ 2-ethylhexyl acrylate 5 parts by weight ・ Titanium oxide 1.0 part by weight ・ Azobisisobutyronitrile 0.1 part by weight It was kept in a 65 ° C. water bath for 5 hours and in a 100 ° C. air bath for 1 hour for polymerization. Thus, the white layer was 0.2 mm, the transparent layer was 3.8 mm, and the total was 4 mm.
A methacrylic resin multilayer board having a thickness of 300 mm and a thickness of 300 mm was obtained. The surface condition was good. The thickness distribution is 0.18 to 0.25 mm for the white layer, and 3.9 to the whole.
It was 4.1 mm. Warpage was 0 mm. The coloring uniformity was good.

Example 2 In Example 1, a glass having a matte surface on the side in contact with the methacrylic resin plate was used on the side where the methacrylic resin plate was installed, of the glass constituting the cell. It was created. Further, the polymerization conditions were set in a 65 ° C. water bath for 5 hours.
The procedure was performed in the same manner as in Example 1 except that the temperature was changed to 1 hour in a 120 ° C. air bath. As a result, the white layer was 0.2 mm and the transparent layer was 3.8 m.
m, a total of 4 mm thick, 300 mm square methacrylic resin multilayer board was obtained. The surface condition was good. Thickness distribution is white layer 0.1
It was 5 to 0.22 mm, and the whole was 3.9 to 4.0 mm. Warpage was 0 mm. The coloring uniformity was good.

COMPARATIVE EXAMPLE 1 The procedure of Example 1 was repeated except that the cell was prepared using only glass on one side and a methacrylic resin plate on the other side. 8mm, 4mm in total
A 300 mm square methacrylic resin multilayer board was obtained. The surface condition of the methacrylic resin multilayer board on the side used as a cell lost gloss and was poor. The thickness distribution is 0.10
It was 0.50 mm, and the whole was 3.5 to 4.7 mm. Warpage is 4
mm. The coloring uniformity was good.

Comparative Example 2 A white layer was prepared in the same manner as in Example 1 except that a methacrylic resin plate was a 100% by weight methyl methacrylate unit and a syrup having the following composition was used. 2mm, transparent layer 3.8mm, total 4mm thickness, 300
A methacrylic resin multilayer board of mm square was obtained. Syrup composition-95 parts by weight of methyl methacrylate-5 parts by weight of polymethyl methacrylate-1.0 part by weight of titanium oxide-0.1 part by weight of azobisisobutyronitrile The surface condition was good. The thickness distribution is 0.17-
0.22 mm, and the whole was 3.9 to 4.1 mm. No warpage
mm. The color tone of the white layer was different depending on the location, and the color uniformity was poor.

Example 3 (Reference) The polymerization conditions in Example 1 were changed in a water bath at 65 ° C. for 5 hours.
Proceed in the same manner except that it was 1 hour in a 120 ° C air bath,
White layer 0.2mm, transparent layer 3.8mm, total 4mm thickness, 300mm
A corner methacrylic resin multilayer board was obtained. The surface had slight sink marks. The thickness distribution of the white layer is 0.17 to 0.22 mm, the whole is 3.9 to
It was 4.1 mm. Warpage was 0 mm. The coloring uniformity was good.

Examples 4 to 6 (Reference) A white layer of 0.2 m was prepared in the same manner as in Example 1 except that a syrup having the composition shown in Table 1 was used instead of the syrup in Example 1.
m, a transparent layer 3.8 mm, a total of 4 mm thickness, and a 300 mm square methacrylic resin multilayer board were obtained. Table 1 also shows the evaluation results.

[0030]

[Table 1] MMA: methyl methacrylate PMMA: polymethyl methacrylate 2EHA: 2-ethylhexyl acrylate AIBN: azobisisobutyronitrile

Examples 7 to 9 (Reference) The procedure of Example 1 was repeated except that the methacrylic resin plate and syrup shown in Table 2 were used instead of the methacrylic resin plate and the syrup. 3.8mm layer, 4mm thickness in total
A 300 mm square methacrylic resin multilayer board was obtained. Table 2 also shows the evaluation results.

[0032]

[Table 2]

Example 10 (Reference) A colorless transparent methacrylic resin plate having a thickness of 5 mm and a thickness of 300 mm was placed on a glass plate having a thickness of 10 mm and a square having a thickness of 300 mm. On this methacrylic resin plate, a 3 mm thick gasket made of vinyl chloride, and a 10 mm thick
Was placed, and a cell having a space having a thickness of 3 mm was formed between the methacrylic resin plate and the glass. The following syrup was poured into this space. Syrup composition Methyl methacrylate 95 parts by weight Polymethyl methacrylate 5 parts by weight 2-ethylhexyl acrylate 5 parts by weight Titanium oxide 1.0 part by weight Azobisisobutyronitrile 0.1 part by weight This cell was placed in a 55 ° C water bath. 5 hours in a 75 ° C water bath
It was kept in a 100 ° C. air bath for 1 hour for polymerization. Thus, a white layer 2 mm, a transparent layer 6 mm, a total thickness of 8 mm, 3
A 00 mm square methacrylic resin multilayer board was obtained. The surface condition was good. The thickness distribution is 1.95 to 2.15 mm for the white layer, and 7.9 to total.
8.2 mm. Warpage was 0 mm. The coloring uniformity was good.

Example 11 (Reference) A 5 mm thick, 300 mm square white methacrylic resin plate containing 0.5 parts by weight of titanium oxide in 100 wt% methyl methacrylate units was placed on a 10 mm thick, 300 mm square glass. did. A 3 mm-thick vinyl chloride gasket and a 10 mm-thick glass were placed on the methacrylic resin plate to form a cell having a 3 mm-thick space between the methacrylic resin plate and the glass. The following syrup was poured into this space. Syrup composition Methyl methacrylate 95 parts by weight Polymethyl methacrylate 5 parts by weight 2-ethylhexyl acrylate 5 parts by weight Sumiplast green (manufactured by Sumitomo Chemical Co., Ltd.) 0.3 parts by weight Azobisisobutyronitrile 0.1 parts by weight Part This cell was placed in a 55 ° C water bath for 5 hours,
It was kept in a 100 ° C. air bath for 1 hour for polymerization. In this way, the green layer is 2 mm, the white layer is 6 mm, the total thickness is 8 mm,
A 00 mm square methacrylic resin multilayer board was obtained. The surface condition was good. The thickness distribution of the white layer is 1.90 to 2.13 mm, and the whole is 7.8 to
It was 8.0 mm. Warpage was 0 mm. The coloring uniformity was good.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-138211 (JP, A) JP-A-56-151560 (JP, A) JP-A-4-296334 (JP, A) JP-A-59-159 47208 (JP, A) JP-A-57-18251 (JP, A) JP-A-62-183886 (JP, A) JP-A-60-76328 (JP, A) (58) Fields investigated (Int. ⁷ , DB name) B29C 39/10-39/12 B29C 39/22-39/36 B32B 27/30 C08J 7/04

Claims (4)

(57) [Claims] 1. A method for manufacturing a methacrylic resin multilayer board by injecting and polymerizing a methacrylic syrup into a cell using a cell having a methacrylic resin board provided on at least one side of the cell, the method comprising the steps of: By including a copolymerizable ethylenically unsaturated monomer in addition to methyl methacrylate as a unit constituting one or both of the syrup-based syrups, the constituent unit composition of the methacrylic resin plate and the methacryl-based syrup may be different. And the cell in contact with the methacrylic resin plate
A method for producing a methacrylic resin multilayer board, characterized in that the surface is a matte surface . Differences 2. A structural unit composition of the methacrylic resin plate and methacrylic syrup, Ru der that a difference 1% by weight or more copolymerizable ethylenically unsaturated monomer content請<br / > The method for producing a methacrylic resin multilayer board according to claim 1. 3. The polymerization temperature of the methacrylic syrup is 100.
The method for producing a methacrylic resin multilayer board according to claim 1, wherein the temperature is lower than or equal to ° C. 4. The methacrylic syrup contains a coloring component.
The method for producing a methacrylic resin multilayer board according to claim 1.