JP2000185251A - Masking cover - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a masking cover which has a high heat resistance, high chemical resistance, and high dimensional stability. SOLUTION: The masking cover has a tensile modulus of 1500 MPa or more and lower than 4000 MPa and has a degree of crystallization of 30% or more. Further, the thickness of the cover is 0.3 mm or more, and the cover is obtained by preferably heat-forming a material composed mainly of a syndiotactic polystyrene having a crystallization temperature of 190-250 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a masking cover, and more particularly, to a masking cover used in a secondary processing for imparting a surface function by coating, printing, vapor deposition, corona treatment, ultraviolet treatment, electron beam treatment, or the like. A member used for covering and protecting a surface portion where a function is not to be imparted, and is a styrene-based polymer having a syndiotactic structure (hereinafter, referred to as "syndiotactic polystyrene" or "S
PS ". ) As a main material.

[0002]

2. Description of the Related Art In recent years, in vehicles such as automobiles, motorcycles, and bicycles, particularly, the body of the automobile is often colored in a two-tone color. However, such coloring is conventionally performed by the following steps. It has been done. That is,
First, an adhesive tape is applied to a part where a certain color is not desired to be applied (called “masking”) so that the paint of the color is not applied. After completely covering with a tape, the required part is sprayed with the paint. After that, 130 ~ 200 ℃
Baking (called "baking") at a high temperature. Specifically, in places where you do not want to paint a certain color, an adhesive tape with a width of about a few centimeters is stuck horizontally across several sections in order to completely cover that part. The end part of
At the end of the body to be painted, the so-called "ears" of the strips of tape need to be neatly aligned. In order to sufficiently satisfy this requirement, such a portion is not left as it is, but a resin member called a “masking cover” having a substantially vertically long shape is used. Is completely covered from above.

Conventionally, a polypropylene-based resin or a nylon-based resin has been used for the "masking cover". However, in a baking process at a high temperature, the member is liable to be deformed or change in size, particularly to shrink in size. However, there is a problem that once used, it cannot be reused next time and must be disposed of. Further, in the case of painting the bumper, the paint is sprayed except for the side light, but in this case, specifically, the part of the side light is formed to substantially the same size. A method is adopted in which a resin member is fitted, paint is sprayed, and then baking is performed in the same manner as in the case of the body. Conventionally, a filler-filled polypropylene resin has been used for a member molded to the size of the vehicle width lamp.
In order to avoid thermal deformation and dimensional change during baking, once make a mold by thermoforming, apply heat in an oven and anneal it to give dimensional stability,
There has been a problem that a troublesome process of using it again must be taken.

Further, in the case of this bumper, since the polypropylene resin can withstand only one use,
There was a problem that it had to be disposed of without reuse.

[0005]

SUMMARY OF THE INVENTION The present invention has been made from such a viewpoint, and provides a masking cover which is excellent in high heat resistance, paint chemical resistance, dimensional stability and can be used repeatedly. It is intended to do so.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies from this point of view, and as a result, have excellent heat resistance, paint chemical resistance, dimensional stability, and a surface protection function at the time of various secondary processing. It has been found that the above problem can be solved by using an extremely excellent specific syndiotactic polystyrene resin as a material.

The present invention has been made based on such findings. That is, the present invention provides the following masking cover. (1) A masking cover satisfying the following: Tensile modulus is more than 1500MPa and 4000MPa
Less than. Crystallinity is 30% or more.

[0008] The thickness is 0.3 mm or more. (2) The masking cover has a crystallization temperature of 190 to 190.
A styrenic polymer having a predominantly syndiotactic structure at 250 ° C. or a crystallization temperature of 190 to 250 ° C.
The masking cover according to the above (1), which is obtained by molding a resin composition containing a styrenic polymer having a syndiotactic structure. (3) The resin composition containing a styrenic polymer having a predominantly syndiotactic structure may be composed of:
The masking cover according to the above (2), comprising 95% by weight and (b) 5 to 50% by weight of a rubber-like elastic body. (4) The masking cover according to any one of (1) to (3), obtained by a thermoforming method. (5) The masking cover according to any one of the above (1) to (4), which is used for masking an unpainted portion during painting.

[0009]

Embodiments of the present invention will be described below. I. Content of Masking Cover According to the Present Invention The masking cover according to the present invention is used when performing secondary processing for imparting various surface functions such as painting, printing, vapor deposition, corona treatment, etc. on the surface of an object. It is a general term for members used for covering and protecting a surface portion where no function is to be provided. For example, in the case of painting, it refers to a member used for the purpose of masking by applying a paint to a part that is not desired to be painted, thereby preventing the paint from being applied to the part. Therefore, the masking cover is also appropriately selected and used according to the shape and size of the portion to be painted or the portion to be masked without painting. The same applies to other surface treatments such as printing and vapor deposition as well as coating. Therefore, the masking cover according to the present invention is appropriately selected according to the purpose, and its shape, size, and the like are not limited. It is particularly preferably used for the purpose of covering the unpainted portion at the time of painting. However, vehicles such as automobiles, trains, ships, aircraft, boats, motorcycles, bicycles, baby carriages, etc., industrial equipment such as industrial robots, and space equipment And can be used for imparting surface functions such as painting.

[0010] The masking cover according to the present invention must satisfy the following properties. (1) The tensile modulus is 1500 MPa or more and 4000 M
It is less than Pa. Here, the tensile modulus is ASTM.
It is a value measured according to D882 and is 1500MP.
If it is less than a, the rigidity will be insufficient, and there is a possibility of deformation at high temperatures. If it exceeds 4000 MPa, it may be hardened and cracks may occur during trimming. The tensile modulus is preferably 2,000 MPa or more and 300
It is less than 0 MPa. (2) Crystallinity is 30% or more.

Here, the crystallinity refers to the enthalpy of crystallization when the temperature is raised from 50 ° C. to 300 ° C. at a rate of 20 ° C./min using a differential scanning calorimeter (DSC7 manufactured by PerkinElmer). It is a value obtained by measuring the enthalpy of fusion and calculating by the following equation. Crystallinity (%) = ｛[enthalpy of fusion (J / g) −enthalpy of crystallization (J / g)] /
Enthalpy of fusion at a crystallinity of 100% (J /
g)｝ × 100 Here, 53 J / g was used as the enthalpy of fusion (J / g) when the crystallinity was 100%.

If the crystallinity is less than 30%, deformation during shrinkage and dissolution in paint may occur. Preferably it is 40%, more preferably 50% or more. (3) The film thickness is 0.3 mm or more. 0.3
If it is less than mm, the rigidity is insufficient, and there is a possibility of deformation at high temperatures. It is preferably at least 0.4 mm. II. Preferred Material Used for Masking Cover According to the Present Invention The masking cover according to the present invention is preferably a styrene-based polymer having a syndiotactic structure or a resin composition containing the styrene-based polymer as a preferred material described below. Object is used. 1. Styrene polymer mainly having a syndiotactic structure Syndiotactic structure in a styrene polymer mainly having a syndiotactic structure means that the stereochemical structure is a syndiotactic structure, that is, a main chain formed from carbon-carbon bonds. Has a steric structure in which phenyl groups, which are side chains, are alternately located in opposite directions, and its tacticity is determined by nuclear magnetic resonance (13C)
-NMR). Tacticity measured by the 13C-NMR method can be represented by the existence ratio of a plurality of continuous structural units, for example, a dyad for two, a triad for three, and a pentad for five. The styrenic polymer having a predominantly syndiotactic structure as referred to in the present invention generally means at least 75%, preferably at least 85%, in racemic diad, or at least 30%, preferably 50%, in racemic pentad.
Polystyrene, poly (alkyl styrene), poly (aryl styrene), poly (halogenated styrene), poly (halogenated alkyl styrene), poly (alkoxy styrene), poly (vinyl benzoate) having the above syndiotacticity , These hydrogenated polymers and mixtures thereof, or copolymers containing these as main components. Here, the poly (alkyl styrene) includes poly (methyl styrene), poly (ethyl styrene), poly (isopropyl styrene), poly (tertiary butyl styrene), and the like. (Phenylstyrene),
There are poly (vinylnaphthalene), poly (vinylstyrene) and the like, and as poly (halogenated styrene), there are poly (chlorostyrene), poly (bromostyrene), poly (fluorostyrene) and the like. Examples of poly (halogenated alkylstyrene) include poly (chloromethylstyrene), and examples of poly (alkoxystyrene) include poly (methoxystyrene) and poly (ethoxystyrene).

Among these, preferred styrene polymers include polystyrene, poly (p-methylstyrene), poly (m-methylstyrene), poly (p-tert-butylstyrene), and poly (p-chlorostyrene). ), Poly (m-chlorostyrene), poly (p-fluorostyrene), hydrogenated polystyrene and copolymers containing these structural units.

Such a styrenic polymer having a predominantly syndiotactic structure can be obtained, for example, by using a titanium compound and a condensation product of water and a trialkylaluminum as a catalyst in an inert hydrocarbon solvent or in the absence of a solvent.
It can be produced by polymerizing a styrene-based monomer (a monomer corresponding to the above-mentioned styrene-based polymer) (JP-A-62-187708). For poly (halogenated alkylstyrene), see JP-A-1-4691.
No. 2, these hydrogenated polymers are disclosed in JP-A-1-1785.
It can be obtained by the method described in JP-A-05-2005.

Among these styrenic polymers having a syndiotactic structure, in the present invention, those having a tacticity of 70% or more by racemic pentad are particularly preferable from the viewpoint of heat resistance and mechanical strength. . Also,
As for the molecular weight, a high molecular weight type is preferable,
MI (measurement condition of 300 ° C, load 1.2kg) is 20 (g
/ 10 minutes) or less, preferably 15 or less, and more preferably 10 or less. If it exceeds 20, it becomes brittle and easily cracked.

The crystallization temperature is 190 ° C.
To 250 ° C, preferably 220 ° C to 240 ° C. As a method of manufacturing a masking cover according to the present invention, preferably, first, an extruded sheet having a low degree of crystallinity is prepared using a material resin, and then, the product is formed into a masking cover by thermoforming using the sheet. Is made. The extruded sheet must have low crystallinity to facilitate subsequent thermoforming. Crystallization in the thermoforming step can provide dimensional stability and stability to paint. Therefore, in such a production method, when the crystallization temperature of the material resin is lower than 190 ° C., crystallization may take a long time during thermoforming, and productivity does not increase. On the other hand, when the temperature exceeds 250 ° C., an extruded sheet having a low crystallinity may not be produced. 2. Resin Composition Containing Syndiotactic Polystyrene As a suitable material used for the masking cover according to the present invention, not only the above-mentioned syndiotactic polystyrene but also a resin composition containing syndiotactic polystyrene can be suitably used. In this resin composition, it is necessary that (a) syndiotactic polystyrene is contained as a resin component. However, from the viewpoint of imparting crack prevention properties, (b) a rubber-like elastic body is required. desirable. Further, within the range not to impair the object of the present invention, having a compatibility or affinity with a thermoplastic resin or syndiotactic polystyrene other than syndiotactic polystyrene, and a polymer having a polar group, or an inorganic filler, Furthermore, various additives such as an antiblocking agent, an antioxidant, a nucleating agent, an antistatic agent, a process oil, a plasticizer, a release agent, a compatibilizer, a flame retardant, a flame retardant auxiliary, and a pigment are compounded. can do.

The above components can be kneaded in various ways, such as a method of blending and melt-kneading at any stage of the syndiotactic polystyrene production process, and a method of blending and melt-kneading the components constituting the composition. It can be done by the method. (1) Rubber-like elastic body Specific examples of the rubber-like elastic body include, for example, natural rubber, polybutadiene, polyisoprene, polyisobutylene, neoprene, polysulfide rubber, thiochol rubber, acrylic rubber, urethane rubber, silicone rubber, epichlorohydrin rubber Styrene-butadiene block copolymer (SBR), hydrogenated styrene-butadiene block copolymer (SEB), styrene-butadiene-styrene block copolymer (SBS), hydrogenated styrene-butadiene-styrene block copolymer ( SEBS), styrene-isoprene block copolymer (SIR), hydrogenated styrene-isoprene block copolymer (SEP), styrene-isoprene-styrene block copolymer (SI
S), hydrogenated styrene-isoprene-styrene block copolymer (SEPS), or ethylene propylene rubber (EPM), ethylene propylene diene rubber (EPD)
M), olefin rubbers such as linear low-density polyethylene elastomers, or butadiene-acrylonitrile-styrene-core-shell rubber (ABS), methyl methacrylate-butadiene-styrene-core-shell rubber (MBS), methyl methacrylate-butyl acrylate-styrene Core-shell rubber (MAS), octyl acrylate-butadiene-styrene-core-shell rubber (MABS), alkyl acrylate-butadiene-acrylonitrile-styrene-core-shell rubber (AAB)
S), butadiene-styrene-core-shell rubber (SB
R), a core-shell type particulate elastic material such as a siloxane-containing core-shell rubber such as methyl methacrylate-butyl acrylate-siloxane, or a rubber obtained by modifying the same, for example, maleic anhydride-modified hydrogenated styrene-butadiene-styrene block copolymer. Polymer (MA
-SEBS) and the like.

Among these rubber-like elastic materials, in the present invention, hydrogenated styrene-butadiene-styrene block copolymer (SEB) is used in view of heat resistance and dielectric properties.
S) is preferred. (2) Thermoplastic resins other than syndiotactic polystyrene Examples of thermoplastic resins other than syndiotactic polystyrene include linear high-density polyethylene, linear low-density polyethylene, high-pressure low-density polyethylene, isotactic polypropylene, and syndoxy. Otactic polypropylene, block polypropylene, random polypropylene, polybutene, 1,2-polybutadiene, 4-methylpentene, cyclic polyolefins and polyolefin resins represented by these copolymers, atactic polystyrene, isotactic polystyrene, HIPS, A
BS, AS, styrene-methacrylic acid copolymer, styrene-methacrylic acid / alkyl ester copolymer, styrene-methacrylic acid / glycidyl ester copolymer, styrene-acrylic acid copolymer, styrene-acrylic acid / alkyl ester copolymer Polystyrene resins such as polymers, styrene-maleic acid copolymers and styrene-fumaric acid copolymers, polyester resins such as polycarbonate, polyethylene terephthalate and polybutylene terephthalate, polyamide 6, polyamide 6,6 And other polyamide resins, polyphenylene ether, polyarylene sulfide, poly-4
-Any known materials such as fluorinated polyethylene resins such as fluorinated ethylene (PTFE) can be used. Among them, polyolefins such as polyethylene and polypropylene or polyphenylene ethers are preferred.
In addition, these thermoplastic resins can be used alone or in combination of two or more. (3) Polymer having compatibility or affinity with syndiotactic polystyrene and having a polar group Syndiotactic polystyrene and thermoplastic resin and / or
Alternatively, it is blended to improve the affinity between the rubber-like elastic body and effectively compatibilize it, and to improve the affinity between the syndiotactic polystyrene and the inorganic filler.

Here, the polymer having compatibility or affinity with syndiotactic polystyrene refers to a polymer having a chain exhibiting compatibility or affinity with syndiotactic polystyrene in a polymer chain. Examples of the polymer exhibiting such compatibility or affinity include, for example, syndiotactic polystyrene, atactic polystyrene, isotactic polystyrene, styrene-based copolymer, polyphenylene ether, polyvinyl methyl ether, and the like. , A block or a graft chain.

The polar group referred to herein may be any group which improves the adhesiveness with an inorganic filler, and specifically includes an acid anhydride group, a carboxylic acid group, a carboxylic ester group, and a carboxylic acid group. Chloride group, carboxylic acid amide group, carboxylic acid group, sulfonic acid group, sulfonic acid ester group, sulfonic acid chloride group, sulfonic acid amide group, sulfonic acid group, epoxy group, amino group, imide group, oxazoline group, etc. No.

This compatibilizer can be obtained by reacting a polymer having compatibility or affinity with the above-mentioned syndiotactic polystyrene and a modifier described below in the presence or absence of a solvent or other resin. it can. As the modifier, for example, a compound containing an ethylenic double bond and a polar group in the same molecule can be used. Specifically, maleic anhydride, maleic acid, maleic ester, maleimide and its N-substituted product, maleic acid derivatives such as maleic acid salt, fumaric acid, fumaric acid ester, and fumaric acid such as fumaric acid salt Derivatives, itaconic anhydride, itaconic acid, itaconic acid esters, itaconic acid derivatives including itaconic acid salts, acrylic acid, acrylic acid esters,
Acrylic acid derivatives such as acrylamide and acrylate, methacrylic acid, methacrylic acid esters, methacrylic acid amides, methacrylic acid salts, and methacrylic acid derivatives such as glycidyl methacrylate are exemplified. Among them, maleic anhydride, fumaric acid and glycidyl methacrylate are particularly preferably used.

A known method is used for the denaturation.
150 using a mill, Banbury mixer, extruder, etc.
A method of melt-kneading and reacting at a temperature of from 0 to 350 ° C, and a method of heating and reacting in a solvent such as benzene, toluene, and xylene can be exemplified. In order to further facilitate these reactions, benzoyl peroxide, di-t-butyl peroxide, dicumyl peroxide, t-butyl peroxybenzoate, azobisisobutyronitrile, azobisisovaleronitrile, It is effective to use a radical generator such as 2,3-diphenyl-2,3-dimethylbutane. Of these, 2,3-diphenyl-2,3-dimethylbutane is particularly preferably used.

A preferred modification method is a method of melt-kneading in the presence of a radical generator. Further, at the time of modification, another resin may be added. Specific examples of the compatibilizer include a styrene-maleic anhydride copolymer (SM
A), a styrene-glycidyl methacrylate copolymer,
Carboxylic acid-modified polystyrene, epoxy-modified polystyrene, oxazoline-modified polystyrene, amine-modified polystyrene, sulfonated polystyrene, styrene ionomer, styrene-methyl methacrylate
To-graft polymer, (styrene-glycidyl methacrylate) -methyl methacrylate-graft copolymer, acid-modified acryl-styrene-graft polymer,
(Styrene-glycidyl methacrylate) -styrene-
Graft polymer, polybutylene terephthalate-polystyrene-graft polymer, maleic anhydride-modified P
S, fumaric acid-modified PS, glycidyl methacrylate-modified PS, amine-modified PS and other modified styrenic polymers,
Modified polyphenylene ethers such as (styrene-maleic anhydride) -polyphenylene ether-grafted polymer, maleic anhydride-modified polyphenylene ether, glycidyl methacrylate-modified polyphenylene ether, and amine-modified polyphenylene ether And the like.

Of these, modified PS and modified polyphenylene ether are particularly preferably used. Further, two or more of the above polymers can be used in combination. The polar group content in the compatibilizer is preferably 10
It is in the range of 0.05 to 20% by weight, more preferably 0.05 to 10% by weight, based on 0% by weight. If the content is less than 0.01% by weight, it is necessary to add a large amount of a compatibilizing agent in order to exert an adhesive effect with the inorganic filler, and the mechanical properties, heat resistance, and moldability of the composition may be reduced. Absent. On the other hand, if it exceeds 20% by weight, the compatibility with syndiotactic polystyrene may be undesirably reduced. (4) Inorganic filler The inorganic filler may be fibrous, granular or powdery. As the fibrous filler,
For example, glass fiber, carbon fiber, whisker and the like can be mentioned. The shape is a cross shape, mat shape, focused cut shape,
There are short fibers, filaments, whiskers, etc., and in the case of a bundle cut, those having a length of 0.05 mm to 50 mm and a fiber diameter of 5 to 20 μm are preferred.

On the other hand, as the granular or powdery filler, for example, talc, carbon black, graphite, titanium dioxide, silica, mica, calcium carbonate, calcium sulfate, barium carbonate, magnesium carbonate, magnesium sulfate, barium sulfate, Oxysulfate, tin oxide,
Examples include alumina, kaolin, silicon carbide, metal powder, glass powder, glass flake, glass beads and the like.

Among the various fillers described above, particulate and powdery fillers such as glass powder and glass free
, Glass beads, talc, carbon black, graphite, titanium dioxide, silica, mica, calcium carbonate, calcium sulfate, barium carbonate, kaolin, and silicon carbide are preferred. As these fillers, those subjected to surface treatment are preferable. The coupling agent used for the surface treatment is used for improving the adhesiveness between the filler and the resin, and includes a so-called silane-based coupling agent, a titanium-based coupling agent, and the like. Any one can be selected and used. Among them, γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, β
Preferred are aminosilanes such as-(3,4-epoxycyclohexyl) ethyltrimethoxysilane, epoxysilane, and isopropyltri (N-amidoethyl, aminoethyl) titanate.

As the film former, a conventionally known one can be used. Among them, urethane type, epoxy type, polyether type and the like are preferably used. In addition, these inorganic fillers can be used alone or in combination of two or more. (5) Various additives As long as the object of the present invention is not impaired, various additives exemplified below can be blended.

Antiblocking Agent (AB Agent) Examples of the antiblocking agent include the following inorganic particles or organic particles. As the inorganic particles, IA
, IIA, IVA, VIA, VIIA, VIII, IB
Oxides, hydroxides, sulfides, nitrides, halides, carbonates, sulfates, acetates, phosphates, phosphites, organic carboxylate salts of Group IIB, IIIB, IIIB and IVB elements, Examples thereof include silicates, titanates, borates and hydrates thereof, composite compounds centered on them, and natural mineral particles.

Specifically, Group IA element compounds such as lithium fluoride, borax (sodium borate hydrate), magnesium carbonate, magnesium phosphate, magnesium oxide (magnesia), magnesium chloride, magnesium acetate, magnesium fluoride, titanium Magnesium silicate, magnesium silicate, magnesium silicate hydrate (talc), calcium carbonate, calcium phosphate, calcium phosphite, calcium sulfate (gypsum), calcium acetate, calcium terephthalate, calcium hydroxide, calcium silicate, calcium fluoride, titanate Group IIA compounds such as calcium, strontium titanate, barium carbonate, barium phosphate, barium sulfate, barium sulfite, titanium dioxide (titania), titanium monoxide, titanium nitride, zirconium dioxide (zirconia), dimonoxide Group VIA element compounds such as IVA element compounds such as conium, molybdenum dioxide, molybdenum trioxide, and molybdenum sulfide; Group VIA element compounds such as manganese chloride and manganese acetate; Group VIII element compounds such as cobalt chloride and cobalt acetate; Group IB element compounds such as cuprous chloride, group IIB compounds such as zinc oxide and zinc acetate, aluminum oxide (alumina), aluminum hydroxide, aluminum fluoride, alumina silicate (alumina silicate, kaolin, kaolinite), etc. III Group B element compounds, silicon oxide (silica, silica gel), graphite, carbon, graphite, glass, etc., Group IVB element compounds, kernalite, kainite, mica (mica, kinunmo), and particles of natural minerals such as byrose ore. Can be

Examples of the organic particles include Teflon, melamine resin, styrene / divinylbenzene copolymer, acrylic resin, and cross-linked products thereof. Antioxidant As the antioxidant, any known antioxidant such as phosphorus-based, phenol-based, and sulfur-based can be used. In addition, these antioxidants may be used alone, or
Two or more can be used in combination.

Nucleating Agents Metal nucleating agents such as aluminum di (pt-butylbenzoate) and phosphoric acid such as sodium methylenebis (2,4-di-t-butylphenol) acid phosphate are used as nucleating agents. Any of known metal salts, talc, phthalocyanine derivatives and the like can be used. These nucleating agents can be used alone or in combination of two or more. Plasticizers Examples of the plasticizer include polyethylene glycol, polyamide oligomer, ethylene bisstearamide, phthalic acid ester, polystyrene oligomer, and the like. Any known materials such as polyethylene wax and silicone oil can be arbitrarily selected and used. These plasticizers can be used alone or in combination of two or more.

Release Agent The release agent can be arbitrarily selected from known materials such as polyethylene wax, silicone oil, long-chain carboxylic acid, and metal salt of long-chain carboxylic acid. These release agents may be used alone or in combination of two or more.

Process Oil In the present invention, a process oil may be further added. Process oils are roughly classified into paraffin-based oils, naphthenic-based oils, and aroma-based oils, depending on the type of oil. Among them, paraffin-based oils are preferred. As the viscosity of the process oil, the kinematic viscosity at 40 ° C. is 15 to 600.
cs is preferable, and 15 to 500 cs is more preferable.

These process oils can be used alone or in combination of two or more. (6) Mixing ratio of each component Regarding the mixing ratio of each component, (a) 50 to 100% by weight (including 100) of syndiotactic polystyrene, preferably 60 to 90% by weight, and more preferably 60 to 8% by weight.
0% by weight, and (b) 0 to 50% by weight of the rubbery elastic body
(Including 0), preferably 10 to 40% by weight, more preferably 20 to 40% by weight. If the component (b) is more than 40% by weight, the elastic modulus may be reduced. Further (a)
When a polymer (c) having compatibility or affinity with the component and having a polar group is blended, the proportion of the component (c) is determined by the sum of the component (a) and the component (b). 0.1 to 10 parts by weight, preferably 0.5 to 8 parts by weight, based on 100 parts by weight,
More preferably, it is 1 to 5 parts by weight. III. Method for Producing Masking Cover According to the Present Invention The method for producing the masking cover according to the present invention is not particularly limited, but the following method is preferred. That is, a method in which an extruded sheet having a low degree of crystallinity is first produced by using a material resin, and then the sheet is used to form a product into a masking cover by thermoforming. Conditions for producing an extruded sheet and conditions for thermoforming the extruded sheet may be appropriately selected depending on the purpose. Further, as the thermoforming, vacuum forming, vacuum / pressure forming, pressure forming and the like are preferably used.

[0035]

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. Example 1 SPS (Syndiotactic polystyrene homopolymer, crystallization temperature = 235 ° C., MI = 3 (30
75 parts by weight at 0 ° C. under a load of 1.2 kg) and 25 parts by weight of SEBS (hydrogenated styrene-butadiene copolymer, “Septon 8006” manufactured by Kuraray Co., Ltd.) as a rubber-like elastic material were dry-blended into a 65 mmφ Pellets were obtained by melt kneading with a screw extruder.

Using the pellets, an extruded sheet was prepared as follows. That is, a T-die was attached to the tip of a 60 mmφ single screw extruder, and using this extruder, the extrusion temperature was set
The sheet was formed at a temperature of 00 ° C. The extruded molten resin was formed into a sheet by a touch roll method. The temperature of the touch roll was 50 ° C. The properties of this sheet were as follows. (1) The tensile modulus was 2000 MPa. (2) The crystallinity was 20%. (3) The thickness was 0.5 mm.

Next, the sheet obtained as described above was preheated to 140 to 150 ° C., and formed into a masking cover by a vacuum forming method. At that time, by applying radiant heat from the top of the sheet shaped in the mold,
The temperature was raised to 200 to 220 ° C. to increase the crystallinity of the sheet. The masking cover thus obtained had the following properties. (1) The tensile modulus was 2500 MPa. (2) The crystallinity was 50%. (3) The thickness was 0.4 mm.

[0038]

According to the present invention, a masking cover having excellent heat resistance, paint chemical resistance and dimensional stability can be obtained.

Claims (5)

[Claims] 1. A masking cover satisfying the following (1) to (3). (1) The tensile modulus is 1500 MPa or more and 4000 M
It is less than Pa. (2) Crystallinity is 30% or more. (3) The thickness is 0.3 mm or more. 2. The masking cover according to claim 1, wherein said masking cover has a crystallization temperature of 190 to 250 ° C. and a styrenic polymer having a syndiotactic structure or a crystallization temperature of 190 to 250 ° C.
The masking cover according to claim 1, wherein the masking cover is formed by molding a resin composition containing a styrenic polymer having a syndiotactic structure at 250 ° C. 3. The resin composition containing a styrenic polymer having a predominantly syndiotactic structure comprises: (a) 50 to 95% by weight of a styrenic polymer having a predominantly syndiotactic structure; 3. The masking cover according to claim 2, comprising 5 to 50% by weight of the elastic body. 4. The method according to claim 1, which is obtained by a thermoforming method.
The masking cover according to any one of the above. 5. The masking cover according to claim 1, which is used for masking an unpainted portion during coating.