JPS649194B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a polycarbonate laminate having excellent weather resistance, solvent resistance, stress whitening resistance, water whitening resistance, transparency, and impact resistance. Since polycarbonate sheets are transparent and have excellent impact resistance, they have been used as a substitute for window glass, as roofing materials for arcades, and as wall materials for buildings. However, polycarbonate sheets lack weather resistance, and especially when used outdoors, they develop a yellowish color during use, and furthermore, the surface becomes white and deteriorates, resulting in a significant loss of transparency, which limits the scope of their use. ing. In order to improve these drawbacks of polycarbonate sheets, methods have been proposed to laminate a film with good weather resistance to a polycarbonate sheet. For example, attempts have been made to laminate an acrylic film made of a simple acrylic copolymer. . However, in such cases, although weather resistance is improved, there is a lack of stress whitening resistance and water whitening resistance, and there are restrictions on use under various environmental conditions, so that fully satisfactory properties have not been achieved. In addition, since general acrylic film easily dissolves and swells in printing ink solvents such as toluene and methyl ethyl ketone, it is impossible to make beautiful prints on the film surface, making it difficult to obtain polycarbonate laminates that require decorative properties. It's not on. In view of the current situation, the present inventors conducted intensive studies to obtain a polycarbonate laminate that satisfies the previously unachieved properties as described above, and as a result, an innermost layer polymer (A) containing a specific alkyl acrylate or alkyl methacrylate as a main component. A crosslinkable elastic polymer (B) containing alkyl acrylate as a main component is polymerized in the presence of , and an outermost layer polymer (C) containing alkyl methacrylate as a main component and having a glass transition temperature of at least 60°C is placed as the outermost layer. and an intermediate layer between the polymer (B) layer and the polymer (C) layer in which the amount of alkyl acrylate monotonically decreases from the polymer (B) layer to the polymer (C) layer. A multilayer structure polymer with a layer (D) interposed therein, and a specific range of grafting agent in each polymer layer except the outermost layer polymer (C) to determine the gel content and residual metal content of the final polymer. The present invention was completed based on the discovery that the object can be achieved by laminating films of multilayer polymers in which the amount is within a specific range. That is, the gist of the present invention is a polycarbonate laminate in which a multilayer structure polymer film made of the multilayer structure polymer shown below is laminated on at least one surface of a polycarbonate sheet. Multilayer structure polymer: 80 to 100 parts of an alkyl acrylate having an alkyl group having 1 to 8 carbon atoms or an alkyl methacrylate having an alkyl group having 1 to 4 carbon atoms (A ₁ ), 0 to 20 parts of a copolymerizable A monomer having a heavy bond ( _A2 ), 0 to 10 parts of a polyfunctional monomer ( _A3 ), and 0.1 to 5 parts per 100 parts of the total amount of ( _A1 ) to ( _A3 ).
The innermost layer polymer consists of a composition of graft cross-agents of
(A), 80 to 100 parts of an alkyl acrylate (B ₁ ) having an alkyl group having 1 to 8 carbon atoms, 0 to 20 parts of a monomer (B 2 ) having a copolymerizable double bond, 0 to 100 parts of a monomer (B ₂ ) having a copolymerizable double bond; 10 parts of polyfunctional monomer (B ₃ ), 0.1 to 5 parts per 100 parts of the total amount of (B ₁ ) to (B ₃ )
51 to 100 parts of an alkyl methacrylate having 1 to 4 carbon atoms (C ₁ ), and 0 to 49 parts of a monomer having a copolymerizable double bond. The basic structural unit is an outermost polymer (C) having a glass transition temperature of at least 60°C consisting of a polymer (C ₂ ), and an intermediate layer (D) between the polymer (B) and polymer (C) layers. 10 to 90 parts of an alkyl acrylate (D ₁ ) having an alkyl group having 1 to 8 carbon atoms; 90 to 10 parts of an alkyl methacrylate (D ₂ ) having an alkyl group having 1 to 4 carbon atoms; A monomer having a polymerizable double bond (D ₃ ), 0 to 10 parts of a polyfunctional monomer (D ₄ ), and 0.1 to 100 parts of the total amount of (D ₁ ) to (D ₄ ). 5
At least an intermediate layer (D) consisting of a composition of a graft cross-agent of A multilayer structure polymer having one layer, the gel content of the multilayer structure polymer being at least 50%, and the residual metal content being 500 ppm or less. The polycarbonate laminate of the present invention is a polycarbonate sheet having a thickness of 10 to 100 g formed by molding a multilayer polymer having the above-mentioned specific structure on one or both sides of the sheet by a conventional molding method such as T-die extrusion or inflation. It is obtained by laminating films of approximately 100μ (thickness is not necessarily limited to this range) using thermocompression bonding or adhesive, and has weather resistance due to the characteristics of the multilayer polymer with such a specific structure. It has extremely excellent properties such as hardness, solvent resistance, stress whitening resistance, water whitening resistance, transparency, and impact resistance. In addition, the polycarbonate sheet constituting the polycarbonate laminate of the present invention has the formula polycarbonate resin having a repeating unit of
Further, it is a sheet made of copolycarbonate resin or modified polycarbonate resin, etc., and its thickness is preferably 0.5 to 10 mm for molding purposes, but is not necessarily limited to this. Next, the multilayer structure polymers constituting the multilayer structure polymer film used in the present invention are as follows: (1) The crosslinked elastic polymer (B) has a two-layer elastic structure containing the innermost layer polymer (A) as an inner layer. (2) One or more intermediate layers (D) are arranged between the crosslinked elastic polymer (B) layer and the outermost polymer layer (C); (3) Glass transition of the outermost polymer layer (C). Temperature (hereinafter referred to as Tg
(4) The interlayers of (A), (B), and (D) above were chemically grafted using a grafting agent having an allyl group; (5) The final The gel content of the polymer must be at least 50%, and (6) the residual metal content of the final polymer must be 500 ppm or less. The characteristics aimed at by the invention cannot be obtained. The multilayer structure polymer used in the present invention will be explained below. The alkyl acrylate having an alkyl group having 1 to 8 carbon atoms, which constitutes the innermost layer polymer (A), may be linear or branched and includes methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate. , n-octyl acrylate, etc. are used alone or in combination, but Tg
A lower one is more preferable. The alkyl methacrylate having an alkyl group having 1 to 4 carbon atoms may be linear or branched, and methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, etc. may be used alone or in combination. These alkyl (meth)acrylates (A ₁ ) are used in an amount of 80 to 100 parts. Furthermore, it is most preferable to use these alkyl (meth)acrylates in the same way in all the multi-stage layers, but depending on the final purpose, two or more types of monomers may be mixed or different types of acrylates may be used. The monomer (A ₂ ) having a copolymerizable double bond is preferably an acrylic monomer such as lower alkyl acrylate, lower alkoxy acrylate, cyanoethyl acrylate, acrylamide, acrylic acid, methacrylic acid, etc. Used within the scope of the section. Styrene, alkyl-substituted styrene, within a range not exceeding 20% by weight in other components (A),
Acrylonitrile, methacrylonitrile, etc. can be used. Furthermore, as the polyfunctional monomer (A ₃ ), alkylene glycol dimethacrylates such as ethylene glycol dimethacrylate, 1,3 butylene glycol dimethacrylate, 1,4 butylene glycol dimethacrylate, and propylene glycol dimethacrylate are preferable, such as divinylbenzene, Polyvinylbenzenes such as trivinylbenzene and alkylene glycol diacrylates can also be used. These monomers effectively act to bridge the layer in which they are contained, and do not act on bonding between layers with other layers. Polyfunctional monomer (A ₃ )
Even if it is not used at all, it will give a fairly stable multilayered polymer as long as the grafting agent is present, but it can be used arbitrarily depending on the purpose of addition, such as when hot strength is strictly required, but the range of use is limited. 0 to 10 parts. On the other hand, copolymerizable α, β
- allyl of unsaturated carboxylic or dicarboxylic acids,
Methallyl or crotyl esters, preferably allyl esters of acrylic acid, methacrylic acid, maleic acid and fumaric acid, are mentioned, with allyl methacrylate being particularly effective. In addition, triallyl cyanurate, triallyl isocyanurate, etc. are also effective. Such graft cross-agents are chemically bonded primarily because the conjugated unsaturated bonds of their esters react much faster than allyl, methallyl, or crotyl groups. During this time, a substantial portion of the allyl group, methallyl group, or crotyl group acts effectively during the polymerization of the next layer to provide a graft bond between two adjacent layers. The amount of the grafting agent used is extremely important, and should be 0.1 to 5 parts per 100 parts of the total amount of the above components (A ₁ ) to (A ₃ ).
It is preferably used in an amount of 0.5 to 2 parts. If the amount used is less than 0.1 part, the effective amount of graft bonding will be small, and if the amount used exceeds 5 parts, the amount of reaction with the crosslinked elastic polymer (B) formed by polymerization in the second stage will be large, resulting in the formation of this multilayer structure polymer. This leads to a decrease in the elasticity of the two-layer crosslinked rubber elastic body, which is one of the characteristics of the two-layer elastic body structure. The innermost layer polymer (A) is a graft-active layer and its
Tg is appropriately set depending on the physical properties required of the final polymer. In general, it is advantageous in terms of quality that the crosslinking density is the same as or even higher than that of the crosslinked elastic polymer (B). Although it is possible that the innermost layer polymer (A) and the crosslinked elastic polymer (B) have the same composition, it is important that they have a two-layer elastic body structure through two-stage polymerization, rather than being charged at one time. Catalyst amount,
It is advantageous for the polymer (A) to have a higher crosslinking density. Considering the initial polymerizability, the presence of the innermost layer polymer (A) is extremely important in order to obtain a stable multilayer structure polymer, and the amount of catalyst is generally charged in the largest amount in each polymer layer. The use of a grafting cross-agent is essential for effectively synthesizing a two-layer elastic structure that is chemically bonded to the crosslinked elastic polymer (B) formed in the second stage. Without this graft bond, the two-layer elastomer structure would easily undergo phase destruction during melt molding, resulting in lower rubber efficiency and would not exhibit the desired excellent weather resistance, solvent resistance, water whitening resistance, etc. The content of the innermost layer polymer (A) in the present multilayer structure polymer is 5 to 35% by weight, preferably 5 to 15% by weight, and is preferably lower than the content of the crosslinked elastic polymer (B). Next, the crosslinked elastic polymer (B) constituting the present multilayer structure polymer is a main component that gives rubber elasticity to the multilayer structure polymer, and is composed of (B ₁ ) to (B ₃ ).
The components, graft cross-agents, etc. used are those used in the innermost layer polymer (A) described above.
(B ₁ ) component is 80 to 100 parts, (B ₂ ) component is 0 to 20 parts,
(B ₃ ) component is 0 to 10 parts, grafting agent is (B ₁ )
- (B ₃ ) are each used in a range of 0.1 to 5 parts per 100 parts of the total amount. The Tg of the crosslinked elastic polymer (B) alone is 0°C or lower, preferably -30°C or lower to provide good physical properties. The content of the crosslinked elastic polymer (B) in the present multilayer structure polymer is preferably in the range of 10 to 45% by weight, and is preferably higher than the content of the innermost layer polymer (A). In this way, the innermost layer polymer (A) and crosslinked elastic polymer (B)
By having a two-layer cross-linked rubber elastic body consisting of a two-layer elastic body structure in which the be.
In order to obtain excellent solvent resistance and water whitening resistance, this two-layer crosslinked rubber elastic body should have a gel content of 85% or more and a swelling degree of 3 to 13, as determined by the following measurement method. is necessary. (Measurement method for gel content and degree of swelling) According to JIS K-6388, a predetermined amount of the two-layer crosslinked rubber elastic body was taken, immersed in methyl ethyl ketone (hereinafter abbreviated as MEK) for 48 hours at 25°C, and then pulled out.
After wiping off the adhered MEK, measure its weight.
After that, MEK is removed by drying in a vacuum dryer, and the absolute dry weight, which has reached a constant weight, is read and calculated using the following formula. Swelling degree = Weight after MEK swelling - Bone dry weight / Bone dry weight Gel content (%) = Bone dry weight / Weight of collected sample x
100 Generally, if the degree of polymerization of the crosslinked elastic polymer (B) is as high as possible, high impact strength will be imparted to the final polymer.
On the other hand, for the core innermost layer polymer (A), this is not the case; rather, it is better to use a large amount of catalyst and to use a large amount of graft active groups in order to stabilize the initial polymerization including particle formation. The performance as a two-layer crosslinked rubber elastic body tends to be good. Such a combined effect cannot be obtained with a single conventional single-layer rubber polymer system. Furthermore, the outermost layer polymer (C) constituting this multilayer structure polymer is involved in distributing moldability, mechanical properties, etc. to the multilayer structure polymer, and is the component (C ₁ ) that constitutes this. and (C ₂ ) component is the above-mentioned (A ₁ )
Components equivalent to component and (A ₂ ) are used.
The ( _C1 ) component is used in a range of 51 to 100 parts, and the ( _C2 ) component is used in a range of 0 to 49 parts. Note that the Tg of the outermost layer polymer (C) alone needs to be 60°C or higher, preferably 80°C or higher in order to obtain excellent solvent resistance and water whitening resistance. the polymer
(C) If the individual Tg is less than 60°C, the solvent resistance and water whitening resistance cannot be excellent even if the gel content of the final polymer described below is 50% or more. The content of the outermost layer polymer (C) in the present multilayer structure polymer is 10 to 80% by weight, preferably 40 to 60% by weight. This multilayer structure polymer has the above-mentioned innermost layer polymer (A), crosslinked elastic polymer (B), and outermost layer polymer (C) as basic structural units, and further includes the polymer (B) layer and the polymer (C). )10 between layers
~90 parts of alkyl acrylate (D ₁ ) having an alkyl group having 1 to 8 carbon atoms, 90 to 10 parts of an alkyl group having 1 to 8 carbon atoms;
Alkyl methacrylate having 4 alkyl groups ( _D2 ), 0 to 20 parts of a monomer having a copolymerizable double bond ( _D3 ), 0 to 10 parts of a polyfunctional monomer ( _D4 ) , D ₁ ) to 0.1 to 100 copies of (D ₄ )
The intermediate layer (D) is composed of 5 parts of a graft cross-agent such that the amount of alkyl acrylate in the intermediate layer (D) decreases monotonically from the polymer (B) layer to the polymer (C) layer. At least one layer is disposed in the Here, the components (D ₁ ) to (D ₄ ) and the graft cross-agent are the same as each component used in the innermost layer polymer (A). The grafting agent used in the intermediate layer (D) is essential for closely bonding each polymer layer and obtaining excellent properties. The content of each intermediate layer (D) in this multilayer structure polymer is 5 to 35% by weight; if it is less than 5% by weight, it will not lose its function as an intermediate layer, and if it exceeds 35% by weight, the final polymer will This is not desirable because it upsets the balance. This multilayer structure polymer is composed of the above polymer layers (A), (B), (C), and (D), and also has excellent solvent resistance, which is the purpose of the multilayer structure polymer. The gel content must be at least
It is necessary that it be 50%, preferably at least 60%, and is one of the major characteristics. In this case, the gel content refers to the two-layer crosslinked rubber elastic body itself and the intermediate layer.
(D) and the outermost layer polymer (C) are grafted onto the crosslinked rubber elastic body, and the gel content here refers to the amount of gel content prepared by preparing a 1% by weight MEK solution of the multilayer structure polymer and heating it to 25°C. After leaving it for a day and night, use a centrifuge for 16,000 r.
This is the weight percent of insoluble matter after centrifugation at pm for 90 minutes. The component is the added weight of the two-layer crosslinked rubber elastic body and the grafted chain, and it can be replaced by the grafting rate, but since it has a special structure, the gel content was used as a guideline for the amount of grafting. From the point of view of solvent resistance, the higher the gel content, the more advantageous it is, but from the point of view of easy moldability, the presence of a certain amount or more of free polymer is necessary, so the upper limit of the gel content is about 80%. preferable. When producing this multilayer structure polymer, there is no particular restriction on the emulsion particle size of the final polymer.
The most balanced structure can be obtained in the range of about 800 to 2000 Å. Note that there are no particular restrictions on the surfactant, catalyst, etc. used in the production, and additives such as antioxidants and lubricants are added as necessary for salting out treatment. What should be noted here is that when salting out using metal salts, the residual metal content in the final product must be
It is extremely important to keep the concentration below 500ppm, and this is one of the major characteristics. In particular, when using metal salts with a strong affinity for water, such as magnesium and sodium, as salting-out agents, the residual metal content must be minimized as much as possible.If the final polymer is immersed in boiling water, it will cause a whitening phenomenon, which is a practical problem. It becomes a problem. Calcium-based or sulfuric acid-based coagulation shows a relatively good tendency, but in any case, in order to provide excellent water whitening resistance, it is necessary to keep the residual metal content below 500 ppm, and the smaller the better. . The most suitable method for producing the present multilayer structure polymer is a sequential multistage polymerization method using an emulsion polymerization method, but it is not particularly limited to this method. For example, the polymerization of the outermost layer polymer (C) after emulsion polymerization is It can also be carried out by emulsion suspension polymerization, which is sometimes converted to a suspension polymerization system. The plastic laminate of the present invention is a polycarbonate laminate with unprecedented properties because it is laminated with a film formed by molding an acrylic multilayer polymer composed of the above-mentioned specific polymer structure. That's what I got. The present invention will be specifically explained below with reference to Examples. Abbreviations used in the examples are as follows. Methyl methacrylate…MMA Butyl acrylate…BuA 2-ethylhexyl acrylate…2EHA Allyl methacrylate…AMA 1,3-butylene dimethacrylate…BD Triallyl cyanurate…TAC Kyumene hydroperoxide…CHP Sodium formaldehyde sulfoxylate…
SFS Styrene...St Also, the Tg of each polymer layer used in the examples is determined by the commonly known FOX formula, for example, from the Tg values listed in the Polymer Handbook: 1/Tg=a ₁ /Tg ₁ +a ₂ /Tg This is calculated from ₂ . Furthermore, the solvent resistance, water whitening resistance, and bending whitening properties in the examples are determined by using a 50μ thick film made by molding a multilayer polymer by T-die extrusion into a 3mm thick transparent polycarbonate sheet (product name Dialite).
The sample was a laminate made by thermocompression bonding on one side of the laminate, and was determined by the following method. Solvent resistance: Leave in a constant temperature room at 25℃ overnight, and MEK
A cylindrical paper impregnated with was placed on the film surface of the sample for 60 seconds and removed to observe changes in the appearance of the laminate. The display is as follows. ◎…No change at all. 〇…The surface is slightly rough. △... Some wrinkles occur. ×: Large deformation occurs. Water whitening resistance: Samples were sandwiched between 200 mesh wire meshes and immersed in boiling water for 60 minutes to observe changes in appearance. The display is as follows. ◎…No change in transparency. 〇…Slightly cloudy. △...Whitening is observed. ×…devitrification and opacity. Bending whitening: Shows the whitening state when the sample is bent 90 degrees using the cold working method. The display is as follows. ◎…Almost no whitening. △...Whitening is observed. Transparency: Samples were evaluated visually. 〇…Good. △...Transparency is somewhat poor. Example 1 250 parts of ion-exchanged water was placed in a polymerization container equipped with a cooler.
2 parts of ester soda salt of sulfosuccinic acid,
After adding 0.05 parts of SFS and stirring under nitrogen, 1.6 parts of MMA,
A mixture consisting of 8 parts BuA, 0.4 parts BD, 0.1 part AMA and 0.04 parts CHP was charged. After raising the temperature to 70°C, the reaction was continued for 60 minutes to complete polymerization of the innermost layer polymer (A). Subsequently, a monomer mixture forming the crosslinked elastic polymer (B) shown in Table 1 was added for 60 minutes and polymerized to obtain a two-layer crosslinked rubber elastic body. In this case, the amount of CHP used for the formation of the polymer (B) was 0.05% by weight, based on the monomer mixture. The degree of swelling and gel content of the obtained two-layer crosslinked rubber elastic body were determined by the method described above.
It was 10.0, 90%. Next, as the middle layer (D), 5 parts of MMA, 5 parts of BuA, and
A mixture of 0.1 part of AMA was reacted, and finally, monomer mixtures having various compositions as shown in Table 1 were reacted to form outer layer polymers (C) with different Tg ( Experiment numbers 1-4). In all cases, the final particle diameter was in the range of 1000 to 1500 Å. Next, polymerization was carried out in the same manner while changing the composition of the innermost layer polymer (A) as shown in Table 1 (Experiment Nos. 5 and 6). Experiment No. 7 shows an example of a three-stage polymer synthesized according to the content described in JP-A-52-33991. These obtained polymer emulsions are polymerized.
Salting out was performed using 5 parts of calcium chloride per 100 parts, washed, and then dried. The residual amount of calcium in the final polymer composition was approximately 200 ppm. In addition, the gel content is 60% for all cases other than experiment number 7.
The above values were shown. A stabilizer was added to the obtained polymer, and a film having a thickness of 50 μm was formed by T-die extrusion. This film was thermocompression bonded to one side of a 3 mm thick polycarbonate sheet separately produced by an extrusion method to form a laminate. Various evaluations were performed on these laminates. As is clear from the results in Table 1, in the solvent resistance test, even if the gel content of the multilayer structure polymer is high, as in experiment number 4, the Tg of the outermost layer polymer (C) is 60.
If the temperature is lower than ℃, it will be easily exposed to solvents and printing resistance will be poor. The laminate obtained in Experiment No. 7 had a low gel content in the multilayer structure polymer, poor solvent resistance, and extremely poor water whitening resistance. The acrylic film surface of each of the above laminates was irradiated with a Sunshine Weather-Ometer and exposed at accelerated speed for 3000 hours, but no change in appearance was observed in any of them.

[Table] Example 2 In Experiment No. 1 of Example 1, the amount of AMA used as a graft cross-agent was varied as shown in Table 2, and TAC was used as a graft cross-agent.
Various polymers were obtained using the same composition and the same method as in Experiment No. 1, except that the amounts shown in Table 2 were used, and these polymers were formed into films using the same method as described in Example 1 to obtain laminates. Table 2 shows the evaluation results of these laminates. Experiment No. 8 is a case without the addition of AMA, and in addition to poor transparency, the desired improvement in solvent resistance and water whitening resistance was not observed. As shown in experiment numbers 13 and 14, (A) layer, (B) layer,
Good results cannot be obtained if any of the layers (C) lacks a graft cross-agent. It can be seen that when the gel content of the final polymer used as a film exceeds 50%, the solvent resistance becomes good.

【table】

[Table] Example 3 A polymer was obtained in the same manner as in Experiment No. 1 of Example 1, except that the type of salting-out agent was changed. Using calcium chloride, magnesium sulfate, and aluminum sulfate as salting-out agents and devising washing conditions, various polymer samples with residual metal amounts as shown in Table 3 were obtained, and then polycarbonate was prepared in the same manner as in Example 1. It was made into a laminate. These were evaluated for water whitening resistance. As is clear from the results in Table 3, the residual metal content in the multilayer structure polymer used as a film is
When it exceeds 500 ppm, devitrification phenomenon occurs especially under conditions where the energy of water such as boiling water is large.

[Table] Example 4 Polymerization was carried out in the same manner as in Experiment No. 1 of Example 1 except for changing the conditions below, and then a polycarbonate laminate was prepared in the same manner as in Example 1.

[Table] All of the polycarbonate laminates obtained by thermocompression bonding the obtained multilayer structure polymer as films showed good solvent resistance and water whitening resistance.

Claims (1)

[Scope of Claims] 1. A polycarbonate laminate, in which a multilayer structure polymer film made of the multilayer structure polymer shown below is laminated on at least one surface of a polycarbonate sheet. Multilayer structure polymer: 80 to 100 parts by weight (hereinafter abbreviated as parts) of alkyl acrylate having an alkyl group having 1 to 8 carbon atoms or alkyl methacrylate having an alkyl group having 1 to 4 carbon atoms (A 1 ), 0 to 100 parts by weight (A ₁ ) 20 parts of monomer having a copolymerizable double bond (A ₂ ), 0 to 10 parts of polyfunctional monomer (A ₃ ), total amount of (A ₁ ) to (A ₃ ) 100 parts 0.1 to 5
The innermost layer polymer consists of a composition of graft cross-agents of
(A), 80 to 100 parts of an alkyl acrylate (B ₁ ) having an alkyl group having 1 to 8 carbon atoms, 0 to 20 parts of a monomer (B 2 ) having a copolymerizable double bond, 0 to 100 parts of a monomer (B ₂ ) having a copolymerizable double bond; 10 parts of polyfunctional monomer (B ₃ ), 0.1 to 5 parts per 100 parts of the total amount of (B ₁ ) to (B ₃ )
51 to 100 parts of an alkyl methacrylate having 1 to 4 carbon atoms (C ₁ ), and 0 to 49 parts of a monomer having a copolymerizable double bond. The basic structural unit is an outermost polymer layer (C) having a glass transition temperature of at least 60°C consisting of a polymer (C ₂ ), and an intermediate layer (D) between the polymer (B) layer and the polymer (C) layer. 10 to 90 parts of an alkyl acrylate (D ₁ ) having an alkyl group having 1 to 8 carbon atoms, 90 to 10 parts of an alkyl methacrylate having an alkyl group having 1 to 4 carbon atoms (D ₂ ), 0 to 20 parts A monomer having a copolymerizable double bond (D ₃ ), 0 to 10 parts of a polyfunctional monomer (D ₄ ), and 0.1 parts per 100 parts of the total amount of (D ₁ ) to (D ₄ ). ~5
At least an intermediate layer (D) consisting of a composition of a graft cross-agent of A multilayer structure polymer having one layer, the gel content of the multilayer structure polymer being at least 50%, and the residual metal content being 500 ppm or less.