JPS61148256A - Methacrylic resin composition having improved water resistance - Google Patents

Abstract

PURPOSE:A composition having extremely improved water resistance without lowering characteristics such as transparency, weather resistance, etc., obtained by blending polymethyl methacrylate with a tetrafluoroethylene.vinylidene fluoride copolymer. CONSTITUTION:(A) 100pts.wt. polymethyl methacrylate is blended with (B) 1-45pts.wt. tetrafluoroethylene.vinylidene fluoride copolymer. A tetrafluoroethylene vinylidene fluoride copolymer containing 10-30mol% tetrafluoroethylene and 90-70mol% vinylidene fluoride is preferable as the component B.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a methacrylate/Lz resin composition having excellent water resistance. For more details, see polymethyl methacrylate l O
0 parts by weight and 1 to 45 parts by weight of a tetrafluoroethylene/vinylidene heptadide copolymer as essential components.

[Conventional technology]

Polymethyl methacrylate resin has excellent transparency, weather resistance, mechanical strength, etc., and is also excellent in moldability, so it is used in many fields such as lighting materials, signboards, signboards, and building materials.

However, compared to other synthetic resins with good transparency, such as polycarbonate resin and poly(4-styrene) resin, their water absorption is greater, and as a result, they are more prone to dimensional changes and warping, and cracks occur during repeated moisture absorption and drying processes. In some application fields, its use was restricted due to drawbacks such as generation.

Many methods have been disclosed for improving the water resistance of such polymethyl methacrylate resins.

For example, JP-A-58-154751, JP-A-58-68
251 and JP-A-58-13652 disclose the copolymerization of hydrophobic monomers with methyl methacrylate.

[Problem that the invention seeks to solve]

However, although it is possible to improve water resistance to some extent by following these disclosed methods, it is still not sufficient, and the heat resistance has the disadvantage of being significantly lower than that of polymethacrylate methyl tzate resin.

In view of the above-mentioned current situation, the present inventor conducted intensive studies to improve the water resistance without impairing the features of polymethyl methacrylate resin (features such as transparency, weather resistance, mechanical strength, etc.), and found that It has been discovered that the above object can be achieved by incorporating a copolymer of ethylene and vinylidene fluoride having a specific copolymer composition into a polymethyl methacrylate resin, leading to the present invention.

[Failure to solve the problem]

That is, the present invention provides polymethyl methacrylate 100m
Part 1! : Contains 1 to 45 parts by weight of tetrafluoroethylene and vinylidene fluoride copolymer as essential components; By using a copolymer consisting of mol% of methacrylic resin, a methacrylic resin composition with excellent water resistance can be obtained.

The mixing ratio of polymethyl methacrylate and tetrafluoroethylene O vinylidene fluoride copolymer in the present invention is as follows:
Tetrafluoroethylene, vinylidene fluoride copolymer 1 to 4 for polymethacrylic acid methacrylate/l/100 overlapping part
The amount is 5 parts by weight, preferably 2 to 30 parts by weight. If the amount of tetrafluoroethylene and vinylidene fluoride copolymer is too small outside this range, the effect of addition on water resistance will not be clear. On the other hand, if the amount is too high, the water resistance tends to further improve, but the compatibility is poor, so the total light transmittance in the visible region decreases, impairing the transparency that is a feature of polymethyl methacrylate resin.

The monomer composition of the tetrafluoroethylene and vinylidene fluoride copolymer in the present invention is 90 to 70% vinylidene fluoride to 10 to 30 mol% of tetrafluoroethylene.
Mol% is preferred. A copolymer having a composition within this range 1 has little crystallinity and particularly good solubility in methyl methacrylate monomer. Therefore, the transparency of the produced methacrylic resin composition is extremely good.

The polymethyl methacrylate or tetrafluoroethylene, vinylidene fluoride copolymer of the present invention may contain copolymerizable unsaturated monomers as necessary within a range that does not impair the effects of the present invention (
Depending on the purpose, it is also possible to copolymerize the amount (usually in a range of 20% by weight or less).

Examples of the unsaturated monomer include methyl acrylate,
(meth)ethyl acrylate, butyp(meth)acrylate
(meth)acrylic acid esters such as styrene, α-methylstyrene, ethylene glyco-A/dimethacrylate, polyethylene glyco-μ dimethacrylates such as diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, etc. can be mentioned.

In order to obtain the methacrylic resin composition according to the present invention or a molded article using the same, it is possible to use already known injection molding, extrusion molding, compression molding, etc.

That is, the method for producing the composition of the present invention is not particularly limited. For example, polymethyl methacrylate, tetrafluoroethylene, and vinylidene fluoride copolymers are produced by bulk polymerization, suspension polymerization, etc. according to conventional methods, and the resulting polymers and copolymers are mixed and then heated and melted, cross-wired, and extruded. There is a method of manufacturing a resin composition by performing the following steps. Furthermore, after preliminarily dissolving tetrafluoroethylene and dinylidene fluoride copolymer in methyl methacrylate monomer, a polymerization initiator commonly used for methyl methacrylate was added, and the mixture was poured into a casting cell. By polymerizing methyl methacrylate, it is also possible to directly obtain a transparent molded product in which a tetrafluoroethylene and vinylidene fluoride copolymer is uniformly dispersed and mixed in polymethacrylate (methyl methacrylate).

The methacrylic resin composition of the present invention may be mixed with other polymers as necessary, and additives such as oxidation stabilizers, weathering stabilizers, colorants, and mold release agents may be added. You may also use it.

The methacrylic resin composition based on the present invention can be used for lighting materials,
It can be used in fields such as signboards, signage boards, and building materials, as well as outdoors, where water resistance is particularly required. Furthermore, it can be satisfactorily used in the field of optical discs such as compact discs and video discs, whose use is restricted due to warping caused by moisture absorption.

〔Example〕

EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these Examples in any way.

Examples 1, 2, 3, 4.5 and Comparative Examples A, B Metac I
J/l/methyl acid monomer, predetermined amount of tetrafluoroethylene, vinylidene fluoride copolymer (copolymer composition 20/l)
80 mol%) was dissolved while heating in a water bath at 70'C, then cooled to room temperature, and 0.3 parts by weight of butyl baroxyisobutyrate, which was also used as a polymerization initiator, was added to 100 parts by weight of this solution. After injecting this into a casting cell made of two tempered glass plates via a soft polyvinyl chloride frame, it was suctioned, degassed, heated at 80°C for 4 hours, and then heated at 120°C.
C. for 2 hours to obtain a cast plate. Polymethyl methacrylate and tetrafluoroethylene of this cast plate,
When the composition of the vinylidene fluoride copolymer was quantitatively determined, it was confirmed that there was no difference in the composition of the mixture of methyl methacrylate monomer and tetrafluoroethylene copolymer when initially charged. The water absorption, total light transmittance, warpage, and glass transition temperature of this cast plate are shown in Table 1 along with comparative examples.

The physical property values in the table were measured as follows.

Water absorption rate: Cast plate (5cm x 10cm, thickness 2.5mm
) was immersed in water at 25°C for 24 hours, and the weight increase was determined from the ratio of the weight before immersion.

Total light transmittance: Measured based on ASTM D1003.

Warp: Casting plate (2.5em x 20am, thickness 2.
After evaporating aluminum to a thickness of 0.4 μm on one side of the 5 mm), the
After keeping one end of the cast plate on a flat surface plate, the distance (Hem) from the other end of the cast plate from the surface plate was measured, and the warpage was determined according to the following formula.

Warpage (%) - “xlo.

The Galanu transition temperature was determined from DSC measurements using a conventional method.

Table 1 shows that the copolymer consisting of METAC IJ/l/acid methyl monomer and ester of saturated aliphatic alcohol and acrylic acid or methacrylic acid has already been disclosed for the purpose of improving water resistance. Similar measurements were conducted for the combined composition, and although the water absorption rate was improved to almost the same level as the composition based on the present invention, the glass transition temperature was lowered to about 800C, and the heat resistance was significantly impaired. It was confirmed that there is.

According to the present invention, as shown in Table 1, it is possible to obtain a methacrylic resin composition in which the water absorption rate and warpage are greatly reduced and the water resistance is improved. It can be seen that compared to methyl resin, the resin has the characteristics of polymethyl methacrylate resin without significantly lowering its transparency or glass transition temperature.

Examples 6, 7.8 and Comparative Examples C, D 100 parts by weight of polymethyl methacrylate and 15 parts by weight of tetrafluoroethylene and vinylidene fluoride copolymers having various copolymerization compositions were uniformly mixed and injection molded. Fill a part of the hopper of the machine, and the temperature of the cylinder is 220°C.
Injection molding was performed at a mold temperature of 600C and an injection pressure of 1000100O to create a plate-shaped molded product. Table 2 shows the water absorption rate and total light transmittance of this plate-shaped molded product.

Table 2 As shown in Table 2, there is no significant change in water absorption even if the copolymer composition of tetrafluoroethylene and vinylidene fluoride copolymer is changed, and water resistance is improved in either case. It can be seen that if the copolymerization composition is deviated from the copolymer composition based on , the total light transmittance decreases and the transparency, which is a feature of polymethyl methacrylate resin, is impaired.

〔Effect of the invention〕

As explained above with reference to the embodiments, according to the present invention,
It is possible to obtain a methacrylic resin having excellent water resistance while having the features of polymethac IJ/L' acid methyl resin.

Claims (2)

[Claims] (1) 100 parts by weight of polymethyl methacrylate and 1 to 45 parts of tetrafluoroethylene and vinylidene fluoride copolymer
Methacrylic resin composition containing parts by weight as essential components (2) The tetrafluoroethylene/vinylidene fluoride copolymer contains 10 to 30 mol% of tetrafluoroethylene,
The methacrylic resin composition according to claim 1, which is a copolymer comprising 90 to 70 mol% of vinylidene fluoride.