JP4763916B2 - Methacrylic resin composition and method for producing methacrylic resin molded product - Google Patents

Description

【００３４】
【発明の効果】
上述したように本発明によれば、短時間で外観欠陥が実質的に無い、耐候性に優れたメタクリル系樹脂成形品を収率良く製造することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a methacrylic resin composition excellent in transparency and weather resistance substantially free from appearance defects, and a method for producing a methacrylic resin molded article.
[0002]
[Prior art]
As a method for producing a methacrylic resin plate, a mold plate method, an extrusion plate method, and the like are generally known. A methacrylic resin plate obtained by mold polymerization generally has less optical distortion and a wider molecular weight selection range than an extruded plate obtained by melt molding, and improves chemical resistance, workability, mechanical strength, etc. Is easy. Therefore, methacrylic resin plates obtained by template polymerization are used in many fields.
[0003]
In the production of methacrylic resin molded products obtained by conventional mold polymerization, the production time has been shortened by a technique such as increasing the radical polymerization initiator in order to improve productivity. However, in the short-time production of such a methacrylic resin molded product, there are drawbacks that it is difficult to control polymerization, and that appearance defects tend to occur in the molded product.
[0004]
In order to control the polymerization in the production, a method using a chain transfer agent is known. For example, Japanese Patent Publication No. 58-455 discloses a technique using an alkyl mercaptan such as n-dodecyl mercaptan. However, mercaptans not only have a problem that odor is generated in their handling, but addition of alkyl mercaptan increases the polymerization time, and the molecular weight of the resulting polymer decreases, resulting in chemical resistance, mechanical strength, etc. It tends to be at a level that is not different from the extruded plate. For this reason, when alkyl mercaptan is used, there is a tendency that the merit of template polymerization is substantially lost.
[0005]
On the other hand, Kinki University Research Report Vol.16, p.19 (1982) discloses that terpenoid compounds have a chain transfer effect. When terpenoid compounds are used in this way, they are not polymerized. There was a problem that the monomer increased and the weather resistance of the resulting polymer deteriorated.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to provide a methacrylic resin composition having substantially no appearance defect and excellent weather resistance, and a method for producing a methacrylic resin molded article.
[0007]
[Means for Solving the Problems]
As a result of diligent investigation, the present inventors have conducted polymerization by using a specific compound and an organic disulfide compound in combination with a polymerizable raw material containing methyl methacrylate, so that there is substantially no appearance defect and weather resistance. The present inventors have found that a methacrylic resin molded product having excellent properties can be obtained with high yield.
[0008]
The methacrylic resin composition of the present invention is based on the above knowledge, and more specifically, methyl methacrylate monomer unit 60-100% by mass and other copolymerizable vinyl monomer units 40-0 mass. A polymer comprising:
Based on 100 parts by mass of the polymer, 1,4-cyclohexadiene, 1-methyl-1,4-cyclohexadiene, terpinolene, myrcene, limonene, α-pinene, β-pinene, β-terpinene, γ- It contains 0.0005 to 0.05 parts by mass of one or more compounds selected from terpinene and 0.002 to 0.05 parts by mass of an organic disulfide compound.
[0009]
According to the present invention, the monomer mixture further comprising 60 to 100% by mass of methyl methacrylate and 40 to 0% by mass of other copolymerizable vinyl monomer units, or the monomer mixture and the monomer mixture 100 parts by weight of a mixture of the monomer mixture and the polymer,
One or more compounds selected from 1,4-cyclohexadiene, 1-methyl-1,4-cyclohexadiene, terpinolene, myrcene, limonene, α-pinene, β-pinene, β-terpinene, γ-terpinene ; Methacrylic acid, characterized by mixing 0005 to 0.05 parts by weight, 0.002 to 0.05 parts by weight of an organic disulfide compound, and 0.01 to 0.5 parts by weight of a radical polymerization initiator, and polymerizing in a mold. A method for producing a resin-based molded article is provided.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described more specifically. In the following description, “parts” and “%” representing the quantity ratio are based on mass unless otherwise specified.
(Monomer)
The monomer used in the present invention may be a single monomer of methyl methacrylate, or a monomer mixture of methyl methacrylate and a vinyl monomer copolymerizable with methyl methacrylate. (In the present invention, even a single monomer may be referred to as a “monomer mixture” for convenience).
(Copolymerizable monomer)
The vinyl monomer to be copolymerized with methyl methacrylate (vinyl monomer other than methyl methacrylate) is not particularly limited. Examples of such vinyl monomers include ethyl methacrylate, isopropyl methacrylate, t-butyl methacrylate, s-butyl methacrylate, n-butyl methacrylate, amyl methacrylate, octyl methacrylate, 2-methacrylic acid 2- Methacrylic acid esters other than methyl methacrylate having 1 to 12 carbon atoms of cycloalkyl group such as ethylhexyl, lauryl methacrylate, phenyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, and alkyl groups containing benzyl group; bornyl methacrylate; Methacrylic acid esters having an alkyl group or alicyclic hydrocarbon group having 8 to 20 carbon atoms such as isobornyl methacrylate, 1-menthyl methacrylate, adamantyl methacrylate and dimethyladamantyl methacrylate; acrylic acid Chill, ethyl acrylate, isopropyl acrylate, butyl acrylate, t-butyl acrylate, amyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, etc. Acrylic esters of styrene; vinyl aromatics such as styrene, α-methyl styrene, paramethyl styrene, isopropenyl styrene, vinyl toluene; unsaturated nitriles such as acrylonitrile, methacrylonitrile; methacrylic acid, acrylic acid, maleic anhydride Examples thereof include, but are not limited to, unsaturated carboxylic acids such as acids; polyunsaturated compounds such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, and divinylbenzene. These monomers can be used alone or in combination of two or more as required.
[0011]
The composition of the monomer that can be used in the present invention is usually 40 to 0% by mass of other copolymerizable vinyl monomers with respect to 60 to 100% by mass of methyl methacrylate (based on the whole monomer). % Range. The use amount of the copolymerizable vinyl monomer is preferably 10% by mass or less as a use amount that does not impair the original physical properties of the methacrylic resin obtained by polymerization.
[0012]
In the present invention, the monomer mixture can be subjected to polymerization. However, a mixture of the monomer mixture and a polymer of the monomer mixture (hereinafter, such a mixture is sometimes referred to as “syrup” as appropriate). There is no problem even if it is subjected to polymerization.
When producing a plate-shaped article using a monomer mixture, use syrup containing a polymer for the purpose of shortening the production time and reducing the appearance defects of the obtained plate-like product. Is preferred. The polymer content in syrup is preferably in the range of 5 to 40%.
[0013]
In the present invention, either a homopolymer of methyl methacrylate or a copolymer of methyl methacrylate and another vinyl monomer is referred to as “polymer” for convenience.
(Cyclopentadiene derivatives, etc.)
When one or more selected from cyclopentadiene and derivatives thereof, and terpenoid compounds and derivatives thereof used in the present invention are added to a monomer mixture or syrup (for example, at 90 ° C. or lower), polymerization time and molecular weight change The polymerization peak temperature can be greatly reduced with a small amount. Therefore, even when the amount of the radical polymerization initiator is increased in order to shorten the production time, it is easy to reduce the polymerization peak temperature by adding these cyclopentadiene and the like, and to hardly cause appearance defects in the molded product. It becomes. Therefore, addition of these cyclopentadiene etc. is very useful also about shortening of production time.
[0014]
Alkyl mercaptans are also found to have the same effect as cyclopentadiene and the like, but when alkyl mercaptans are used, the molecular weight is greatly reduced, and the physical properties of the resulting molded product are significantly reduced.
The addition amount of one or more compounds selected from cyclopentadiene and derivatives thereof, and terpenoid compounds and derivatives thereof used in the present invention is (based on the mass of the polymer derived from the monomer mixture, that is, 100 parts by mass). It is preferably in the range of 0.0005 parts by mass to 0.05 parts by mass and in the range of 0.001 parts by mass to 0.03 parts by mass.
[0015]
If the amount of the compound such as cyclopentadiene added is less than 0.0005 parts by mass, it is difficult to obtain the effect of lowering the polymerization peak temperature, and foamed defects tend to occur in the molded product. On the other hand, when the compound such as cyclopentadiene is added in an amount exceeding 0.05 parts by mass, the unreacted monomer increases beyond the limit, and the physical properties of the obtained molded product tend to be lowered.
[0016]
Cyclopentadiene, its derivatives, terpenoid compounds and as its inductive element, 1,4-cyclohexadiene, 1-methyl-1,4-cyclohexadiene, terpinolene, myrcene, limonene, alpha-pinene, beta-pinene, α- terpinene, beta-terpinene, Ru include compounds of γ- Terupine down it is. These compounds can be used alone or in combination of two or more as required. Of these, terpenoid compounds are preferred, and terpinolene is most preferred.
(Organic disulfide compound)
When a compound selected from cyclopentadiene and derivatives thereof, and terpenoid compounds and derivatives thereof is added and polymerized alone, the number of unreacted monomers increases, so that the molded product turns yellow after the weather resistance test, There is a tendency for optical properties to deteriorate. However, as in the present invention, when cyclopentadiene or the like and an organic disulfide compound are used in combination or in combination, surprisingly, yellowing of the resulting polymer can be suppressed and weather resistance can be improved.
[0017]
The amount of the organic disulfide compound used in the present invention is in the range of 0.002 to 0.05 parts by mass (based on the mass of the polymer, that is, 100 parts by mass), and 0.003 to 0.03 parts by mass. It is preferable to use in a partial range. If the amount of the organic disulfide compound added is less than 0.002 parts by mass, the effect of improving weather resistance by addition tends to be difficult to obtain. On the other hand, when the organic disulfide compound is added in an amount exceeding 0.05 parts by mass, the molded product is yellowed, and the optical properties of the obtained molded product tend to deteriorate.
[0018]
Specific examples of the organic disulfide compound used in the present invention include diethyl disulfide, di-n-butyl disulfide, di-n-hexyl disulfide, di-n-octyl disulfide, di-n-dodecyl disulfide, di-t-butyl. Examples include, but are not limited to, disulfide, di-t-hexyl disulfide, di-t-octyl disulfide, di-t-dodecyl disulfide, and the like. Of these, di-t-butyl disulfide, di-t-hexyl disulfide, di-t-octyl disulfide, and di-t-dodecyl disulfide are preferable, and di-t-dodecyl disulfide is most preferable.
(Method for producing methacrylic resin molded product)
The method for polymerizing the raw material of the methacrylic resin composition of the present invention is not particularly limited. The above-described features of the methacrylic resin composition raw material of the present invention (that is, it is easy to reduce the polymerization peak temperature and make it difficult to cause appearance defects in the molded product) are particularly effective when applied to mold polymerization. It is.
[0019]
Therefore, the methacrylic resin molded article of the present invention includes, for example, one or more compounds selected from cyclopentadiene and derivatives thereof, terpenoid compounds and derivatives thereof, and organic disulfides in the above monomer mixture or syrup. After adding and mixing the compound, it can be produced by pouring into a mold and polymerizing.
[0020]
The template that can be used in this case is not particularly limited. In the present invention, for example, those composed of a plate-like body such as tempered glass, chrome-plated plate or stainless steel plate and a gasket such as soft vinyl chloride, or the same relative direction described in Japanese Patent Publication No. 52-30985. A mold composed of two endless belts that travel at the same speed and gaskets that travel at the same speed as both endless belts at both ends of the opposing surfaces can be used. Among other things, the production method of the present invention is particularly effective in the case of production by an endless belt device in which the line is automated so that it can be continuously processed and the line speed can be freely and finely adjusted by mechanical drive. High effect.
[0021]
The mold surface may have a shape having minute irregularities. A film that does not swell or dissolve in the monomer mixture or syrup, and has a film with fine irregularities on its surface, is attached so that the irregular surface of the film is the polymerizable raw material side of the mold inner surface. Raw materials can also be injected. By these methods, it is also possible to obtain a resin molded product having a minute uneven shape on the surface and preventing glare.
(Radical polymerization initiator)
In the present invention, the polymerization initiator or polymerization initiation method that can be used when polymerizing the monomer mixture or syrup is not particularly limited. In the present invention, it is preferable to use a radical polymerization initiator.
[0022]
The radical polymerization initiator that can be used in the present invention is not particularly limited, and examples thereof include 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, Azo polymerization initiators such as 2,2′-azobis- (2,4-dimethylvaleronitrile) and 1,1′-azobis (cyclohexane-1-carbonitrile), benzoyl peroxide, bis (4-t-butyl) Cyclohexyl) peroxydicarbonate, t-hexylperoxyneodecanoate, t-butylperoxyneodecanoate, t-butylperoxy-2-ethylhexanoate, t-hexylperoxypivalate, etc. Specific examples include oxides. These polymerization initiators can be used alone or in combination or in combination of two or more as required.
[0023]
The addition amount of the radical initiator is preferably in the range of 0.01 to 0.5 parts by mass per 100 parts by mass of the monomer mixture or syrup. If the amount of radical initiator added is too small, polymerization will not be completed due to a shortage of initiator, so that unreacted monomers increase and the weather resistance tends to deteriorate. On the other hand, if the amount of radical initiator added is too large, it tends to be difficult to obtain a polymerization control effect due to one or more compounds of cyclopentadiene and its derivatives, and terpenoid compounds and their derivatives, resulting in surface defects in the molded product. It tends to occur.
(Additive)
The monomer mixture or syrup can be added with various additives used in producing a normal methacrylic resin or a modified product thereof, if necessary. Examples of the additive herein include dyes and pigments used for coloring; stabilizers such as antioxidants and ultraviolet absorbers; flame retardants, chain transfer agents, and crosslinking agents.
(Polymerization temperature)
The polymerization temperature in the present invention varies depending on the type of polymerization initiator used, but is generally preferably 40 to 170 ° C. Furthermore, it is preferable to perform polymerization at a two-stage polymerization temperature in which the first stage is 40 to 90 ° C. and the second stage is 100 to 140 ° C.
[0024]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.
In addition, the physical property evaluation in an Example was performed based on the following method.
1) Appearance observation The surface defects of the methacrylic resin plate taken out from the mold and the presence or absence of internal foaming were visually observed.
[0025]
2) Weather resistance test Using a sunshine weatherometer (manufactured by Suga Test Instruments Co., Ltd.), 2000 hours with respect to a test piece cut out from a resin plate under conditions of rain at 12 ° C for 60 minutes per cycle at 63 ° C Exposure was performed.
3) Yellowness measurement The yellowness of the test piece after the weather resistance test was measured according to JIS K7103.
Example 1
100 parts by mass of methyl methacrylate was supplied to a 50 liter SUS304 reactor equipped with a condenser, a thermometer and a stirrer and heated while stirring, and when the internal temperature reached 80 ° C., 2, 2 ′ -Reprecipitation method by adding 500 ppm of azobis- (2,4-dimethylvaleronitrile) (based on the mass of methyl methacrylate), further heating to an internal temperature of 90 ° C, holding for 8 minutes, and then cooling to room temperature A syrup having a polymerization rate of about 22% and a viscosity at 20 ° C. of 1.5 Pa · s measured with a B-type viscometer was obtained.
[0026]
Next, to 100 parts by mass of this syrup, 0.001 part by mass of terpinolene, 0.03 part by mass of di-t-dodecyl disulfide, and 2,2′-azobis- (2,4-dimethylvaleronitrile which is a radical polymerization initiator) ) After adding 0.085 parts by mass and 0.01 parts by mass of 2- (5-methyl-2-hydroxyphenyl) benzotriazole, the mixture was stirred and degassed under reduced pressure at -90 kPa for 5 minutes, and then a gasket made of polyvinyl chloride. The two SUS304 plates facing each other at an interval of about 4 mm were injected into a mold fixed with a clamp.
[0027]
The mold in which syrup was injected in this manner was immersed in warm water at 78 ° C. for 30 minutes to be polymerized and cured, then heat-treated in a 135 ° C. air heating furnace for 60 minutes and cooled to 90 ° C. The methacrylic resin plate having a thickness of about 3 mm was obtained by removing the frame.
After the appearance of the obtained resin plate was observed, a weather resistance test was performed, and then the degree of yellowing was measured. The obtained results are shown in Table 1.
Example 2
96 parts by mass of methyl methacrylate and 4 parts by mass of butyl acrylate were supplied to the same reactor as that used in Example 1, and 630 ppm of n-dodecyl mercaptan was used as a molecular weight regulator (total of methyl methacrylate and butyl acrylate). (Based on mass), and when the internal temperature reached 80 ° C. with stirring, 500 ppm of 2,2′-azobis- (2,4-dimethylvaleronitrile) (total of methyl methacrylate and butyl acrylate) (Based on mass), further heated to an internal temperature of 90 ° C. and held for 13 minutes, and then cooled to room temperature, the polymerization rate measured by the reprecipitation method was about 26%, and measured by a B-type viscometer 20 A syrup having a viscosity at 2 ° C. of 2 Pa · s was obtained.
[0028]
Next, to 100 parts by mass of this syrup, 0.01 parts by mass of α-terpinene, 0.005 parts by mass of di-t-butyl disulfide, and 0.25 parts by mass of t-hexyl peroxypivalate which is a radical polymerization initiator, After adding 0.01 parts by mass of 2- (5-methyl-2-hydroxyphenyl) benzotriazole, the mixture was stirred, degassed under reduced pressure at -90 kPa for 5 minutes, and then passed through a polyvinyl chloride gasket at an interval of about 6 mm. The two SUS304 plates facing each other were injected into a mold fixed with a clamp.
[0029]
The mold in which syrup is injected in this manner is immersed in warm water at 86 ° C. for 20 minutes, polymerized and cured, then heat-treated in a 130 ° C. air heating furnace for 60 minutes and cooled to 90 ° C., and then the mold is removed. Thus, a methacrylic resin plate having a thickness of about 5 mm was obtained.
Various evaluations were made on the resin plates thus obtained. The obtained results are shown in Table 1.
Example 3
100 parts by mass of syrup similar to that used in Example 1, 0.03 parts by mass of β-pinene, 0.01 parts by mass of di-t-octyl disulfide, 0.15 parts by mass of t-hexylperoxypivalate, After adding 0.01 part by mass of 2- (5-methyl-2-hydroxyphenyl) benzotriazole, the mixture was stirred to obtain syrup.
[0030]
SUS304 endless belt with a mirror finish of 1200 mm width and 1 mm thickness that travels in the same direction at the same speed, and a polyvinyl chloride gasket that travels at the same speed as both endless belts at both ends of the opposite surface A device in which the gap between the two endless belts was set to have a thickness of about 6 mm in advance was used as a mold. The syrup obtained above was degassed under reduced pressure at -90 kPa for 10 minutes, and then sufficient syrup was injected into the mold at a constant flow rate to fill the mold using a metering pump.
[0031]
The polymer was cured for 30 minutes in a 82 ° C hot water shower along with the movement of the belt at 1 m / min, then heat treated at 135 ° C for 20 minutes with a far-infrared heater, cooled to 100 ° C over 10 minutes by blowing air, and then from the belt The resin plate was peeled off to obtain a methacrylic resin plate having a thickness of about 5 mm.
Various evaluations were made on the resin plates thus obtained. The obtained results are shown in Table 1.
Example 4
In 100 parts by mass of syrup as in Example 1, 0.01 parts by mass of γ-terpinene, 0.02 parts by mass of di-n-butyl disulfide, 0.14 parts by mass of t-hexylperoxypivalate, 2- (5 After adding 0.01 part by mass of -methyl-2-hydroxyphenyl) benzotriazole, the mixture was stirred to obtain syrup. The syrup thus obtained was degassed under reduced pressure at -90 kPa for 5 minutes, and then injected through a polyvinyl chloride gasket into a mold in which two opposed SUS304 plates were fixed with clamps.
[0032]
The mold in which syrup is injected is immersed in warm water at 78 ° C. for 20 minutes, polymerized and cured, then heat-treated in an air heating furnace at 125 ° C. for 60 minutes and cooled to 90 ° C., and then the mold is removed. Thus, a methacrylic resin plate having a thickness of about 6 mm was obtained.
Various evaluations were made on the resin plates thus obtained. The obtained results are shown in Table 1.
Comparative Example 1
A resin plate was obtained in the same manner as in Example 1 except that the di-t-dodecyl disulfide used in Example 1 was not added. Various evaluations were made on the resin plates thus obtained. The obtained results are shown in Table 1.
Comparative Example 2
A resin plate was obtained in the same manner as in Example 1 except that the terpinolene used in Example 1 was not added. Various evaluations were made on the resin plates thus obtained. The obtained results are shown in Table 1.
Comparative Example 3
A resin plate was obtained in the same manner as in Example 1 except that the amount of terpinolene used in Example 1 was 0.08 parts by mass. Various evaluations were made on the resin plates thus obtained. The obtained results are shown in Table 1.
Comparative Example 4
A resin plate was obtained in the same manner as in Example 2 except that α-terpinene used in Example 2 was not added. Various evaluations were made on the resin plates thus obtained. The obtained results are shown in Table 1.
Comparative Example 5
A resin plate was obtained in the same manner as in Example 2 except that the amount of di-t-butyl disulfide used in Example 2 was 0.1 parts by mass. Various evaluations were made on the resin plates thus obtained. The obtained results are shown in Table 1.
[0033]
[Table 1]

[0034]
【The invention's effect】
As described above, according to the present invention, a methacrylic resin molded article having substantially no appearance defect and excellent weather resistance can be produced in high yield in a short time.

Claims (4)

A polymer comprising 60 to 100% by weight of methyl methacrylate monomer units and 40 to 0% by weight of other copolymerizable vinyl monomer units;
Based on 100 parts by mass of the polymer, 1,4-cyclohexadiene, 1-methyl-1,4-cyclohexadiene, terpinolene, myrcene, limonene, α-pinene, β-pinene, β-terpinene, γ- A methacrylic resin composition comprising 0.0005 to 0.05 parts by mass of one or more compounds selected from terpinene and 0.002 to 0.05 parts by mass of an organic disulfide compound.   The methacrylic resin composition according to claim 1, wherein the organic disulfide compound is a dialkyl disulfide having an alkyl chain having a tertiary structure. A monomer mixture comprising 60 to 100% by weight of methyl methacrylate and 40 to 0% by weight of other copolymerizable vinyl monomer units, or a polymer of the monomer mixture and the monomer mixture; 100 parts by weight of a mixture of
One or more compounds selected from 1,4-cyclohexadiene, 1-methyl-1,4-cyclohexadiene, terpinolene, myrcene, limonene, α-pinene, β-pinene, β-terpinene, γ-terpinene ; Methacrylic acid, characterized by mixing 0005 to 0.05 parts by weight, 0.002 to 0.05 parts by weight of an organic disulfide compound, and 0.01 to 0.5 parts by weight of a radical polymerization initiator, and polymerizing in a mold. Of manufacturing resin-based molded resin. Two endless belts, in which the mold travels in the same direction in the same direction relative to each other;
4. The method for producing a methacrylic resin molded product according to claim 3, wherein the molded product is a mold composed of a gasket that travels at the same speed as the endless belt at both ends of the opposing surfaces of the endless belt.