JP3615875B2 - Methacrylic resin casting polymer - Google Patents

Description

【００３４】
【発明の効果】
本発明のメタクリル樹脂注型重合品は、メタクリル樹脂の特徴である優れた透明性を維持したまま、樹脂を溶剤蒸気に暴露した際に発生する樹脂表面の白化を防止することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a methacrylic resin cast polymer product excellent in solvent resistance obtained by template polymerization of a monomer mainly composed of methyl methacrylate or a mixture thereof with a partial polymer thereof.
[0002]
[Prior art]
There are methods for producing methacrylic resin plates, such as a mold plate method and an extrusion plate method, but methacrylic resin obtained by template polymerization of a monomer mainly composed of methyl methacrylate, compared to an extruded plate obtained by melt molding a resin. Resin cast products are used in many fields because they have low optical distortion and a wide range of molecular weights, which can improve chemical resistance, processability, mechanical strength, and the like.
However, methacrylic resin plates are very rarely whitened when a solvent comes into contact with the resin plate during solvent bonding, and it has been desired to improve this point.
[0003]
[Problems to be solved by the invention]
An object of the present invention is to provide a methacrylic resin cast product having excellent solvent resistance that does not whiten the surface of the cast product when the methacrylic resin cast product comes into contact with a solvent.
[0004]
[Means for Solving the Problems]
As a result of diligent investigations to solve the above-mentioned object, the present inventors have added the characteristics of methacrylic resin by adding salicylic acid and sodium salicylate to a methyl methacrylate monomer or a mixture thereof and a polymer thereof. The inventors found that a methacrylic resin cast polymer product excellent in solvent resistance can be obtained while maintaining certain excellent transparency, and reached the present invention.
[0005]
That is, the present invention relates to 100 parts by weight of a resin component comprising 60 to 100% by weight of methyl methacrylate and 40 to 0% by weight of other copolymerizable vinyl monomers, 0.001 to 0.03 parts by weight of salicylic acid and sodium salicylate. It is in the methacrylic resin casting polymer manufactured from 0.001-0.03 weight part.
[0006]
Further, the present invention relates to 100 parts by weight of a resin component comprising 60 to 100% by weight of methyl methacrylate and 40 to 0% by weight of other copolymerizable vinyl monomers, 0.001 to 0.03 parts by weight of salicylic acid, and sodium salicylate. A methacrylic resin cast polymerized product produced from 0.001 to 0.03 part by weight and 0.01 to 0.1 part by weight of triphenylphosphine.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the monomer constituting the resin component is a monomer mixture of a methyl methacrylate monomer alone and other vinyl monomers copolymerizable with methyl methacrylate.
[0008]
Vinyl monomers copolymerized with methyl methacrylate are, for example, ethyl methacrylate, isopropyl methacrylate, t-butyl methacrylate, s-butyl methacrylate, n-butyl methacrylate, amyl methacrylate, octyl methacrylate, methacrylic acid. 2-ethylhexyl, lauryl methacrylate, phenyl methacrylate, cyclohexyl methacrylate, cycloalkyl groups such as benzyl methacrylate, methacrylic esters having 1 to 12 carbon atoms of alkyl group including benzyl group; bornyl methacrylate, isobornyl methacrylate Methacrylic acid ester having an alkyl group having 8 to 20 carbon atoms or an alicyclic hydrocarbon group such as phentyl methacrylate, 1-methynyl methacrylate, adanthyl methacrylate, dimethyl adamantel methacrylate, etc. Methyl acrylate, ethyl acrylate, isopropyl acrylate, butyl acrylate, t-butyl acrylate, amyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, cyclohexyl acrylate, phenyl acrylate Acrylic esters such as benzyl acrylate; vinyl aromatics such as styrene, α-methyl styrene, paramethyl styrene, isopropenyl styrene and vinyl toluene; unsaturated nitriles such as acrylonitrile and methacrylonitrile; methacrylic acid, Examples thereof include unsaturated carboxylic acids such as acrylic acid and maleic anhydride; polyunsaturated compounds such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate and divinylbenzene. However, it is not limited to these, Moreover, these can be used individually by 1 type or in combination of 2 or more types.
[0009]
The composition ratio of the monomer used in the resin component constituting the methacrylic resin cast polymer of the present invention is usually 60 to 100% by weight of methyl methacrylate and 40 to 0% by weight of other copolymerizable vinyl monomers. However, depending on the purpose of improvement, the amount of other copolymerizable vinyl monomers used may be 5% by weight or less as the amount used so as not to impair the original physical properties of the methacrylic resin obtained by polymerization. desirable.
[0010]
In the present invention, the above-mentioned monomer or monomer mixture (hereinafter simply referred to as “monomer”) is subjected to template polymerization. There is no problem even if a mixture of polymers (hereinafter referred to as “syrup”) is subjected to polymerization.
[0011]
The methacrylic resin of the present invention is characterized in that salicylic acid and sodium salicylate are contained in the above resin constituent components. Of these, sodium salicylate increases the solvent resistance of the surface of the resin cast polymer. However, the addition of sodium salicylate provides solvent resistance on the surface of the resin cast product, but it loses transparency and whitening occurs when immersed in hot water, so salicylic acid is used as a compatibilizing agent.
[0012]
The amount of sodium salicylate used is preferably in the range of 0.001 to 0.03 parts by weight with respect to 100 parts by weight of the monomer or syrup. If the amount used is less than 0.001 parts by weight, the solvent resistance of the surface of the resin cast product is not sufficient, and if the amount used exceeds 0.03 parts by weight, the transparency of the resin cast product obtained decreases, Water absorption whitening when immersed in hot water becomes severe. Addition of sodium salicylate to the resin component uses water as a solvent that is equal to or 20 times the amount added.
[0013]
The amount of salicylic acid used is preferably in the range of 0.001 to 0.03 parts by weight with respect to 100 parts by weight of the monomer or syrup. When the amount used is less than 0.001 part by weight, the transparency of the resulting resin cast product is lowered, and water absorption whitening of the resin cast product occurs when immersed in hot water. Moreover, when the usage-amount exceeds 0.03 weight part, the strength reduction of the resin cast product obtained will be brought about.
[0014]
In the present invention, when an organic peroxide type initiator is used as the polymerization initiator, triphenylphosphine (hereinafter abbreviated as TPP) for further improving the solvent resistance of the surface of the resin cast product may be used in combination. preferable. The amount of TPP used is preferably in the range of 0.01 to 0.1 parts by weight with respect to 100 parts by weight of monomer or syrup. If the amount used is less than 0.01 parts by weight, the surface of the resin cast product The solvent resistance of the resin is not sufficient, and when the amount used exceeds 0.1 parts by weight, the resulting resin cast product is colored or causes a decrease in strength.
[0015]
The methacrylic resin cast polymer of the present invention is polymerized by a template polymerization method.
[0016]
Examples of polymerization initiators that can be used for the polymerization of monomers or syrups in template polymerization include azo-based polymerizations such as azobisisobutyronitrile and 2,2'-azobis- (2,4-dimethylvaleronitrile). Examples thereof include organic peroxides such as an initiator, benzoyl peroxide, t-butylperoxy 2-ethylhexanoate, and t-hexylperoxypivalate.
[0017]
In the polymerization, a molecular weight regulator is used as necessary. This includes alkyl mercaptans such as n-butyl mercaptan, n-dodecyl mercaptan and octyl mercaptan.
[0018]
The polymerization temperature varies depending on the type of polymerization initiator used, but is generally 40 to 170 ° C, and is a two-stage polymerization temperature in which the first stage is 40 to 90 ° C and the second stage is 100 to 140 ° C. Polymerization is preferred.
[0019]
In the polymerization, various additives used in the production of ordinary methacrylic resins or modified products thereof can be added. Additives include dyes, pigments or antioxidants used for coloring, stabilizers such as ultraviolet absorbers or flame retardants, release agents that facilitate the release of molds from plasticizers or resin castings, chain transfer agents , A crosslinking agent, etc.
[0020]
【Example】
Hereinafter, the present invention will be described in detail by examples. In the description, “parts” means parts by weight. In addition, the physical property evaluation in an Example was performed based on the following method.
(1) Transparency The transparency and coloring of the resin cast product were observed under illumination in a dark place, and a good one was evaluated as ◯, a slightly good one as Δ, and a poor one as X.
(2) The resin cast product was immersed in warm water at 80 ° C. for 24 hours and then evaluated as whitening: No, whitening: Δ, whitening: x, depending on the degree of whitening.
(3) The degree of whitening of the surface of the resin cast product when the solvent-resistant resin cast product was exposed to methylene chloride vapor was evaluated as no whitening: ○, slightly whitened: Δ, and whitened: ×.
[0021]
[Examples 1 to 3]
Methyl methacrylate is supplied to a reactor equipped with a condenser, a thermometer and a stirrer, and heated with stirring, and when the internal temperature reaches 80 ° C., 2,2′-azobis- (2,4- 0.05 parts of dimethylvaleronitrile) was added, and the internal temperature was further increased to 90 ° C. and maintained at that temperature for 8 minutes. After cooling to room temperature, the polymerization rate was about 22% and the viscosity at 20 ° C. was 1500 centipoise. I got syrup.
[0022]
Next, 0.083 part of 2,2'-azobis- (2,4-dimethylvaleronitrile) as a polymerization initiator was used as a polymerization initiator in 100 parts of this syrup, and the amount of salicylic acid shown in Table 1 and pure water of 1000 ppm were used as solvents. After the addition of sodium salicylate, the mixture is stirred and poured into a mold made of two SUS304 plates facing each other at a distance of 3 mm through a polyvinyl chloride gasket, and immersed in warm water at 78 ° C. for 30 minutes for polymerization curing. Then, heat treatment was performed in an air heating furnace at 135 ° C. for 60 minutes. After cooling, the mold was removed to obtain a resin cast product having a plate thickness of about 3 mm. The physical properties of this resin casting were evaluated. The results are shown in Table 1.
[0023]
[Comparative Examples 1-5]
100 parts of syrup similar to those used in Examples 1 to 3, 0.083 parts of 2,2′-azobis- (2,4-dimethylvaleronitrile) as a polymerization initiator, in an amount shown in Table 1. Salicylic acid and sodium salicylate using 0.1 part of pure water as a solvent were added, and a resin cast product was obtained in the same manner as in Example 1 to evaluate physical properties. The results are also shown in Table 1.
[0024]
As apparent from Table 1, Examples 1 to 3 which are the resin cast products of the present invention keep the transparency and suppress whitening after immersion in hot water and whitening of the surface of the cast product after exposure to solvent vapor. On the other hand, in the resin cast product to which salicylic acid and sodium salicylate are not added (Comparative Example 1), the surface of the cast product is whitened after exposure to solvent vapor. In addition, the resin cast products (Comparative Examples 2 and 3) that are out of the range of the preferred use amount have a cast product surface whitened or lost transparency after exposure to solvent vapor. Transparency is lost in the resin cast product added with sodium salicylate alone (Comparative Example 4), and the cast product surface of the resin cast product added with salicylic acid alone (Comparative Example 5) is whitened after exposure to solvent vapor. ing.
[0025]
[Examples 4 to 6]
While supplying 95.7 parts by weight of methyl methacrylate and 4.3 parts by weight of butyl acrylate to the same apparatus as in Example 1, 0.063 part of n-dodecyl mercaptan was added as a molecular weight regulator, and then stirred. When the internal temperature reaches 80 ° C by heating, 0.05 part of 2,2'-azobis- (2,4-dimethylvaleronitrile) is added and further heated until the internal temperature reaches 90 ° C. Was kept for 13 minutes, and then cooled to room temperature to obtain a syrup having a polymerization rate of about 26% and a viscosity at 20 ° C. of 2000 centipoise.
[0026]
Next, in 100 parts of this syrup, 0.03 part of n-dodecyl mercaptan as a molecular weight regulator and 0.32 part of t-hexylperoxypivalate as an organic peroxide polymerization initiator are shown in Table 1. Sodium salicylate using 0.1 parts of TPP, salicylic acid and 0.1 part of pure water as a solvent was added, and the same procedure as in Example 1 was followed to obtain a resin cast product, and the physical properties were evaluated. The results are shown in Table 1.
[0027]
[Comparative Examples 6-7]
100 parts of syrup similar to that obtained in Example 4, 0.03 part of n-dodecyl mercaptan as a molecular weight regulator, and 0.03 part of t-hexylperoxypivalate as an organic peroxide polymerization initiator. 32 parts, sodium salicylate using TPP in the amounts shown in Table 1, sodium salicylate and 0.1 part of pure water as a solvent was added, and the same procedure as in Example 4 was followed to obtain a resin cast product. Evaluated. The results are also shown in Table 1.
[0028]
As is apparent from Table 1, Examples 4 to 6, which are resin cast products of the present invention, maintain whiteness and suppress whitening after immersion in hot water and whitening of the cast product surface after exposure to solvent vapor. On the other hand, in the resin cast products (Comparative Examples 6 and 7) that are out of the preferable range of use amount, the surface of the cast product is whitened or the transparent product is lost after the solvent vapor exposure.
[0029]
[Examples 7 to 8]
In the same apparatus as in Example 1, methyl methacrylate was supplied, heated with stirring, and when the internal temperature reached 75 ° C, 0.002 part of azobisisobutyronitrile was added, and the internal temperature was 95 ° C. Was heated to 10 minutes and then cooled to room temperature to obtain a syrup having a polymerization rate of about 8% and a viscosity of 200 centipoise at 20 ° C.
[0030]
Next, 0.003 part of 2,2'-azobis- (2,4-dimethylvaleronitrile) as a polymerization initiator and 0.1 part of salicylic acid and pure water in the amounts shown in Table 1 were added to 100 parts of this syrup as a solvent. After adding sodium salicylate as described above, the mixture was stirred and poured into a mold made of two inorganic glass plates facing each other at 10 mm intervals through a polyvinyl chloride gasket and immersed in warm water at 65 ° C. for 6 hours. After polymerization and curing, heat treatment was performed in an air heating furnace at 125 ° C. for 3 hours. After cooling, the mold was removed to obtain a resin cast product having a plate thickness of about 10 mm. The physical properties of this resin casting were evaluated and are shown in Table 1.
[0031]
[Comparative Examples 8-9]
To 100 parts of syrup similar to that obtained in Example 7, sodium salicylate with the amount of salicylic acid shown in Table 1 and 0.1 part of pure water as a solvent was added. And physical properties were evaluated. The results are shown in Table 1.
[0032]
As is apparent from Table 1, Examples 7 and 8 which are resin cast products of the present invention suppress the whitening after immersion in hot water and the surface of the cast product after exposure to solvent vapor while maintaining transparency. On the other hand, in the resin cast products (Comparative Examples 8 and 9) that are out of the range of the preferable use amount, the cast product surface is whitened or the transparency is lost after the solvent vapor exposure.
[0033]
[Table 1]

[0034]
【The invention's effect】
The methacrylic resin cast polymerized product of the present invention can prevent whitening of the resin surface that occurs when the resin is exposed to solvent vapor while maintaining the excellent transparency characteristic of the methacrylic resin.

Claims (2)

100 parts by weight of a resin component comprising 60 to 100% by weight of methyl methacrylate and 40 to 0% by weight of other copolymerizable vinyl monomers, 0.001 to 0.03 parts by weight of salicylic acid and 0.001 to 0 of sodium salicylate A methacrylic resin cast polymer produced from 0.03 part by weight. 100 parts by weight of a resin component comprising 60 to 100% by weight of methyl methacrylate and 40 to 0% by weight of other copolymerizable vinyl monomers, 0.001 to 0.03 parts by weight of salicylic acid, 0.001 to 0 of sodium salicylate A methacrylic resin cast polymerized product produced from 0.03 part by weight and 0.01 to 0.1 part by weight of triphenylphosphine.