JPH0244844B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing filled plastics useful in the construction industry with improved appearance and heat resistance.

Filled plastics are widely used as building materials and interior decoration. However, compared to natural stone, which has traditionally been used for building materials and interior decoration, filler-containing plastics are more flammable, have lower heat resistance, have poorer surface hardness, and do not have the same appearance as natural stone. lack of depth, etc.
There is a lot of room for improvement.

As for the internal combustibility of these improvements, a method is known in which a methyl methacrylate polymer is made flame retardant by incorporating alumina hydrate into it, as disclosed in Japanese Patent Publication No. 50-22586. However, although alumina hydrate has excellent properties as a flame retardant, it decomposes at temperatures above 180°C, resulting in very poor heat resistance. Therefore, the alumina hydrate-containing methyl methacrylate polymer cannot be subjected to secondary processing such as heat bending, which can be performed with ordinary polymers. Further, JP-A-56-9261 discloses an acrylic resin containing SiO ₂ and alumina hydrate. However, SiO ₂ does not have any positive effect on making the material flame retardant or improving heat resistance, and has the same drawbacks in terms of heat resistance as when it contains alumina hydrate. Further, Japanese Patent Publication No. 52-16131 describes a composition in which 3CaO.Al ₂ O ₃ .6H ₂ O is melt-kneaded with a thermoplastic resin such as polystyrene, polyvinyl chloride, or polyolefin. However, these resins have poor surface hardness, heat deformation resistance, and weather resistance, and do not have sufficient performance as a substitute for natural stone.

In addition, resins mainly composed of methyl methacrylate are
The softening point is high, and if you try to melt and knead 3CaO.Al ₂ O _{3.6H 2} O, 3CaO.Al ₂ O _{3.6H 2} O will thermally decompose, so melt-kneading cannot be applied. Therefore, the present inventors investigated to obtain a cured acrylic resin product with excellent flame retardancy, heat resistance, surface hardness, and appearance. As a result, the present inventors preliminarily added calcium aluminate hydrate to a polymerizable monomer whose main component is methyl methacrylate. It has been discovered that this object can be achieved by polymerizing the materials after mixing them, leading to the present invention.

That is, the present invention is directed to a polymerizable monomer containing methyl methacrylate as a main component or a partial polymer thereof15
~80% by weight and calcium aluminate hydrate ~20~
This is a method for producing a cured acrylic resin by polymerizing an 85% by weight mixture.

The cured acrylic resin obtained by the present invention is dramatically superior in flame retardancy, heat resistance, secondary processability, surface hardness, and appearance compared to conventional filler-containing plastics.

The calcium aluminate hydrate used in the present invention has various types depending on the ratio of CaO/Al ₂ O ₃ /H ₂ O, but the one represented by 3CaO・Al ₂ O ₃・6H ₂ O is the most stable one. It is an easy form. 3CaO・
What is represented _{by Al2O3}・_6H2O is Al(OH) ₃ and Ca
The thermal decomposition temperature is as high as 250°C compared to a simple mixture of (OH) ₂ at a molar ratio of 2:3.
The absorption peaks of X-ray diffraction are also completely different. The manufacturing method is “GMELINS HANDBUCH DER ANORG−
ANISCHEN CHEMIE, ALUMINUM TEIL
B SYSTEM-NUMBER35” (VERLAG
CHEMIE GMBH (1934), page 560, shows that it can be obtained by the reaction of an aluminum compound and a calcium compound, but by-products from the production of alumina can also be used. The average particle size is 3μm or more
The average particle diameter is preferably 80 μm or less, and if it is less than 3 μm, the dispersibility during filling will be poor, making it difficult to fill 20% by weight or more. Moreover, when the average particle diameter is larger than 80 μm, separation from the matrix resin occurs due to sedimentation of the particles during filling, which is not preferable.

As a polymerizable monomer containing methyl methacrylate as a main component, from the viewpoint of appearance resemblance to natural stone, weather resistance, surface hardness, and heat deformation resistance of the obtained cured product,
It is necessary to contain 50% by weight or more of methyl methacrylate units. If the amount is less than this, surface hardness, weather resistance, appearance, and heat deformation resistance cannot be ensured. In addition, in order to improve the thermal decomposition resistance of the methyl methacrylate polymer and the adhesion between the matrix resin and calcium aluminate hydrate, or to improve the moldability of the resulting cured product, less than 50% by weight of a polymerizable monomer may be added. Can be copolymerized. As monomers for copolymerization, methacrylic acid or acrylic acid (hereinafter referred to as (meth)acrylic acid),
Methyl acrylate, ethyl (meth)acrylate,
Esters of (meth)acrylic acid and alcohol represented by butyl (meth)acrylate, stearyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and 2-hydroxyethyl (meth)acrylate; Specific examples include acrylamide and its derivatives, styrene and its derivatives, and vinyl acetate.

Although the polymerizable monomer may be used as it is, it is more preferable to use a partial polymer in order to prevent the mixed calcium aluminate hydrate from being unevenly distributed.

The partial polymer is called a syrup when producing methyl methacrylate (co)polymer, and may be one commonly used, with a polymer content of about 3 to 40% by weight. If it exceeds 40% by weight, the viscosity becomes high and it becomes difficult to handle, which is not preferable.

In addition, known methods may be used to produce this partial polymer, such as a method in which an initiator is added to a polymerizable monomer and polymerized, and the polymerization is stopped at an appropriate polymerization rate, a method in which a polymer of the monomer is There is a method of dissolving a predetermined amount of

The polymerizable monomer or its partial polymer and calcium aluminate hydrate may be mixed uniformly by placing them in a container equipped with a stirrer, and the method is not limited as long as both are uniformly mixed.

Note that the amount of calcium aluminate hydrate is required to be 20% to 85% by weight. If it is less than 20% by weight, flame retardancy and heat resistance will be poor, and if it exceeds 85% by weight, it will be difficult to mix uniformly with the polymerizable monomer or its partial polymer, and the resulting cured product will have poor secondary properties. Processability is lost, which is undesirable.

As the polymerization method, bulk polymerization, suspension polymerization, etc. are applied. Among these, bulk polymerization is preferred, and a method of casting polymerization in a mold is particularly preferred. In the cast polymerization method, a mold in the shape of a plate or the desired molded body is created, and a polymerizable monomer mixture or a partial polymer of the polymerizable monomer mixture, a polymerization initiator, calcium aluminate hydrate, and additives are placed in the mold. A predetermined amount of the mixture is poured and polymerized. polymerization temperature,
Although the time varies depending on the type of shape initiator used in the molded article, it is generally carried out at 25°C to 95°C for 30 minutes to one week.

As the polymerization initiator, it is preferable to use a radical polymerization initiator such as an azo compound or an organic peroxide, and the amount thereof is 0.001 to 100% relative to the polymerizable monomer.
It is preferable to add 1% by weight, more preferably 0.01% by weight.
It is preferable to add up to 0.5% by weight. Specific examples of azo compounds used as radical polymerization initiators include 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethyl-4-methoxyvaleronitrile), and examples of organic peroxides include benzoyl peroxide and lauroyl peroxide. Alternatively, a redox-based polymerization initiator, such as a combination of an organic peroxide and an amine, can also be used as a radical polymerization initiator. During this polymerization, additives commonly used in the production of methyl methacrylate polymers can be incorporated. As the additive, one or more of crosslinking agents, ultraviolet absorbers, oxidation stabilizers, plasticizers, molecular weight regulators, colorants, etc. can also be used. As the crosslinking agent, commonly used crosslinking agents containing multiple polymerizable unsaturated bonds in one molecule can be used, such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, and tetraethylene glycol di(meth)acrylate. acrylate, trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate,
Examples include pentaerythritol tetra(meth)acrylate, allyl(meth)acrylate, and the like.
By adding a crosslinking agent, the surface hardness and solvent resistance of the molded article can be improved, and it can be used in an amount of 20% by weight or less based on the polymerizable monomer.

The ultraviolet absorber is added to improve the weather resistance of the matrix resin, and can be used in an amount of 5% by weight or less based on the amount of the matrix resin. As oxidation stabilizers, there are those added to improve the weather resistance of the matrix resin and those added to prevent inhibition of polymerization by air during polymerization, and both are used in an amount of 5% by weight or less based on the amount of matrix resin. Plasticizers, molecular weight regulators, colorants, etc. can be added as necessary.

The present invention will be explained in more detail below using Examples. In the following examples, the oxygen index is
According to VISK7201, Rockwell hardness is
Measured according to ASTMD-785. The viscosity is E
It was measured at 25°C using a model viscometer (manufactured by Tokyo Keiki).

Example 1 120 g of methyl methacrylate polymer (Sumipetx-B MH manufactured by Sumitomo Chemical) was dissolved in 480 g of methyl methacrylate monomer to give a polymer content of 20%.
A methyl methacrylate partial polymer having a viscosity of 1 poise was obtained.

The above methyl methacrylate partial polymer 100 g 3CaO・Al ₂ O ₃・6H ₂ O (average particle size 12 μm) 150 g Ethylene glycol dimethacrylate 1 g 2,2'-Azobisisobutyronitrile 0.1 g Add the above mixture to 500 ml Place in a glass flask and stir thoroughly with a stirring blade for 30 minutes. 150×150×5
A m/m mold was prepared, and the mixture was poured into it and polymerized by heating at 80° C. for 2 hours in a water bath.

The obtained cured product had an oxygen index of 26 and a Rockwell surface hardness of 98 (M scale), showing excellent flame retardancy and surface hardness. The appearance was also good. This cured product was heated in a hot air oven at 200°C for 20 minutes, but there was no change in appearance such as swelling.

Example 2 Methyl methacrylate 392 in a container with a stirrer from 1
g, 1.2 g of lauryl mercaptan in 8 g of methyl acrylate, 2,2'-azobisisobutyronitrile
After adding 0.02 g and dissolving in a nitrogen atmosphere, the mixture was stirred at 75° C. for 90 minutes at 30 rpm using a stirring blade to polymerize, yielding a partial polymer with a polymerization rate of 20% and a viscosity of 2 poise.

The above partial polymer 100g 3CaO・_Al2O3・_6H2O (average particle _size 12μm) 185g Triethylene glycol dimethacrylate 2g Benzoyl peroxide 0.1g N,N-dimethyl-p-toluidine 0.05g The above mixture was poured into a 500ml glass flask. The mixture was thoroughly mixed for 30 minutes using a stirring blade in the chamber, and then poured into a mold of 150 x 150 x 5 m/m and left at room temperature for one day.

The obtained cured product had an oxygen index of 33 and a Rockwell surface hardness of 99 (M scale), showing excellent flame retardancy and surface hardness.

The cured product was heated at 200°C for 30 minutes, but there was no change in appearance such as swelling.

Comparative Example 1 100 g of the partial polymer obtained in Example 2 2 g of triethylene glycol dimethacrylate 0.3 g of benzoyl peroxide The above mixture was mixed with 0.05 g of hydroxyethyl cellulose.
85 wt% in an aqueous solution with vigorous stirring.
Suspension polymerization was carried out at ℃.

20g of the obtained polymer was added to 3CaO・Al ₂ O ₃・6H ₂ O37
After mixing with g, the polymer was kneaded at 250°C using a roll kneader (6-inch roll manufactured by Toyo Seiki Co., Ltd.), but the polymer did not melt and could not be blended.

Example 3 A methyl methacrylate partial polymer having a polymer content of 23% and a viscosity of 2 poise was obtained by dissolving 92 g of methyl methacrylate polymer (SumiPex-B MH manufactured by Sumitomo Chemical) in 312 g of methyl methacrylate monomer.

The above partial polymer 300g 3CaO・Al ₂ O ₃・6H ₂ O (average particle size 12 μm) 450g 2,2′-Azobisisobutyronitrile 0.2g The above mixture was mixed in a glass flask with a stirring blade.
The mixture was thoroughly mixed for 30 minutes, poured into a mold of 250 x 250 x 6 m/m, and heated to 70°C in a water bath for 4 hours to polymerize. The appearance of the obtained cured product is color tone,
The depth was also good. The cured product had an oxygen index of 26 and a Rockwell hardness of 96 (M scale), showing excellent flame retardancy and surface hardness.

Comparative Example 2 40 g of powdered methyl methacrylate polymer (Sumipetx-B MH manufactured by Sumitomo Chemical)
After mixing 10 g of 3CaO.Al ₂ O ₃ .6H ₂ O, the mixture was kneaded at 230° C. for 10 minutes using a Plastomill (Brabender).
The resulting polymer contained a large number of cells and a very fragile composition was obtained.

Example 4 180 g of methyl methacrylate monomer, 30 g of styrene monomer, and 5 g of ethyl acrylate were added to 10 g of methyl methacrylate polymer (SumiPex-B MH manufactured by Sumitomo Chemical) and dissolved with stirring to obtain a partial polymer of polymerizable monomers.

Partial polymer of the above polymerizable monomer 100 g 3CaO・Al ₂ O ₃・6H ₂ O (average particle size 12 μm) 180 g N,N-dimethyl-p-toluidine 0.1 g Benzoyl peroxide 0.15 g After thoroughly mixing the above mixture 150×150×5m/
The mixture was poured into a mold of 1.5 m and left at 40°C for 1 day. The appearance of the obtained cured product is excellent, and the oxygen index is
30, Rockwell surface hardness 90 (M scale), showing excellent flame retardancy and surface hardness.

Claims (1)

[Claims] 1. Polymerizable monomer containing methyl methacrylate as a main component or a mixture of 15 to 80% by weight of a partial polymer thereof and 20 to 85% by weight of calcium aluminate hydrate having an average particle size of 3 μm or more and 80 μm or less. Method for producing cured acrylic resin.