JPH0532732A - Transparent resin having low water-absorption - Google Patents

Abstract

PURPOSE:To provide the subject composition composed of phenyl methacrylate, dicyclopentenyl acrylate and a specific acrylic acid ester at specific ratios, having excellent mechanical strength and flexibility and useful for optical card, lens, etc. CONSTITUTION:The objective resin is composed of (A) 4-92wt.% of phenyl methacrylate, (B) 4-92wt.% of dicyclopentenyl acrylate and (C) 4-92wt.% of an acrylic acid ester of formula [R is 1-5C hydrocarbon group, 6-12C alicyclic hydrocarbon group or (F-substituted) 3-20C hydrocarbon group] (e.g. methyl acrylate).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acrylic resin having low water absorption and excellent mechanical strength and flexibility.

[0002]

2. Description of the Related Art Conventionally, a method of introducing a compound having a hydrophobic group into a polymer has been mentioned as a method for obtaining an acrylic resin having a low water absorption property. Specifically, a hydrophobic group is introduced at the terminal of a carboxyl group. It is known that the water absorption rate is lowered by polymerizing the compound. On the other hand, in order to improve water absorption and heat resistance, a method of introducing a rigid group having a large molecular volume can be mentioned.

However, a hydrophobic group having a large molecular volume such as an alicyclic hydrocarbon group having a carbon number of 5 or more improves water absorption and heat resistance, but tends to become brittle and mechanical strength decreases, so In order to improve the strength, there is a method of copolymerizing an acrylic acid alkyl ester as a rubber component.

[0004]

However, although a resin having low water absorption can be obtained by the above method,
Since the rubber component is in the state of island-shaped microphase separation and particles larger than the wavelength of visible light are dispersed, there is a problem in that the transparency, which is a characteristic of the acrylic resin, is lowered.

[0005]

DISCLOSURE OF THE INVENTION The present invention is intended to provide a transparent resin having excellent transparency as well as low water absorption.

That is, the present invention relates to phenyl methacrylate 4 to 4
92% by weight, dicyclopentenyl acrylate 4 to 92% by weight, and general formula (I) CH2 = CH-COOR (I) (wherein R is a linear or branched hydrocarbon group having 1 to 5 carbon atoms,
An alicyclic hydrocarbon group having 6 to 12 carbon atoms, or 3 to 20 carbon atoms in which at least a part of hydrogen atoms are substituted with fluorine atoms
Which represents a straight chain hydrocarbon group) of 4 to 92% by weight of at least one acrylic ester.

In the present invention, the acrylic ester represented by the general formula (I) includes methyl acrylate, ethyl acrylate, isopropyl acrylate, butyl acrylate, isobutyl acrylate, t-butyl acrylate, cyclohexyl acrylate, and acrylic. Methyl cyclohexyl acid, 2,2,2-trifluoroethyl acrylate, 2,2,3,3-tetrafluoropropyl acrylate, 1H, 1H, 5H-octafluoropentyl acrylate,
1H, 1H, 2H, 2H-heptadecafluorodecyl acrylate, 1H-hexafluoroisopropyl acrylate, perfluoro-t-butyl acrylate, 1H, 1H, 2H, 2H-tridecafluorooctyl acrylate, 1H acrylic acid , 1H, 2H, 2H-heneicosafluorododecyl, 1H, 1H, 2H, 2H-pentacosafluorotetradecyl acrylate and the like.

The resin of the present invention is very excellent in transparency as compared with the copolymer of phenyl methacrylate and acrylic acid ester because it is further copolymerized with dicyclopentenyl acrylate. If the copolymerization ratio of dicyclopentenyl acrylate is too low, it will be difficult to achieve sufficient transparency of the obtained resin.

In order to obtain a resin excellent in transparency and low water absorption in the present invention, the amount of dicyclopentenyl acrylate is determined as the monomer to be used according to the type and amount of acrylate ester to phenyl methacrylate. However, it is usually 4% by weight or more.

In the present invention, a monovinyl monomer or 2 in the molecule may be added depending on the purpose without departing from the purpose of the present invention.
Vinyl monomers having one or more α, β unsaturated groups can be copolymerized.

A known polymerization method such as radical polymerization or ionic polymerization can be applied to the resin of the present invention. For example, it can be produced by a method such as bulk polymerization, solution polymerization or suspension polymerization in the presence of a polymerization initiator.

As the radical polymerization initiator used in the present invention, a radical polymerization initiator generally used for the polymerization of methyl methacrylate can be used. Specifically, lauroyl peroxide, benzoyl peroxide, t-butyl peroxypivalate, t-butyl peroxy neodecanoate, t-butyl peroxy-2
-Ethyl hexanoate, t-butyl peroxyisobutyrate, diisopropyl peroxydicarbonate,
Organic peroxide such as di-2-ethylhexyl peroxydicarbonate, 2,2′-azobisisobutyronitrile,
2,2'-Dimethyl-azobisisobutyrate, 2,2'-
Azo compounds such as azobis (2-methylbutyronitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), Examples thereof include water-soluble catalysts typified by potassium persulfate and ammonium persulfate, and redox catalysts obtained by combining a peroxide or a persulfate salt with a reducing agent. These polymerization initiators can be used alone or in combination of two or more kinds.

The type and amount of these polymerization initiators are determined in consideration of the resin composition, reactivity, reaction rate control, etc.
Ordinarily 0.01 to 10 relative to 100 parts by weight of the monomer mixture.
Used in the range of parts by weight.

The polymerization conditions for the transparent resin of the present invention are not particularly limited, but the polymerization temperature is usually 50 to 150 ° C.
Therefore, it is possible to carry out the polymerization in multiple stages by changing the polymerization temperature.

In the case of production by cast polymerization, the mold used is not particularly limited, and for example, a mold composed of a plate-like body such as tempered glass, a chrome-plated plate, a stainless plate and a gasket made of soft vinyl chloride, An example is a mold composed of opposing surfaces of a pair of endless belts that travel in the same direction at the same speed, and gaskets that run at the same speed as both endless belts on both sides of the surfaces.

[0014]

The present invention will be described in more detail with reference to the following examples. The physical properties in the examples were evaluated as follows. Total Light Transmittance and Haze Value It was performed according to ASTM D1003. Tensile Strength It was performed according to ASTM D638. Bending strength was measured according to ASTM D790. Water absorption The test piece was dried at 80 ° C / 0.1 mmHg or less for 48 hours or more to measure the initial weight, and then the test piece was allowed to stand in water at 40 ° C for 30 days, and the weight was measured. The test formula of JIS-K7209 It was obtained from the A method (when it is obtained from the ratio of the original weight of the test piece and the increase in weight after absorbing water).

Example 1 60 parts by weight of phenyl methacrylate, 10 parts by weight of dicyclopentenyl acrylate and 30 parts by weight of butyl acrylate were mixed, and further 0.01 parts by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator. And 2,2′-azobis (2,4-dimethylvaleronitrile) (0.06 parts by weight) were added, and 0.1 part by weight of sodium dioctylsulfosuccinate as a release agent was added and dissolved, followed by degassing in a vacuum. To remove volatiles. Next, it is poured into a casting cell made of 30 mm x 30 mm size inorganic reinforced glass plate, steel clip, and polyvinyl chloride gasket, and the temperature is 60 ° C.
Polymerization was carried out for 4 hours in a water bath and further in an air bath at 120 ° C. for 2 hours to obtain a plate having a thickness of 3 mm. The results are shown in Table 1.

An experiment was conducted in the same manner as in Example 1 except that the composition of the monomer used was changed as shown in Table 1. The results are shown in Table 1.

[0018]

[Table 1]

[0019]

INDUSTRIAL APPLICABILITY The resin of the present invention has low water absorption and is excellent in transparency, and can be used for optical information recording media such as optical cards and optical disks, and has high industrial utility value.

Claims (1)

Claims: 1. Phenyl methacrylate 4 to 92% by weight,
4 to 92% by weight of dicyclopentenyl acrylate and the general formula (I) CH2 = CH-COOR (I) (wherein R is a linear or branched hydrocarbon group having 1 to 5 carbon atoms,
An alicyclic hydrocarbon group having 6 to 12 carbon atoms, or 3 to 20 carbon atoms in which at least a part of hydrogen atoms are substituted with fluorine atoms
A straight-chain hydrocarbon group) of 4) to 92% by weight of at least one acrylate ester.