JP2005126631A - Styrene resin sheet, formed article thereof and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prepare a styrene resin sheet causing little staining of a hot plate and having excellent transparency of formed articles, initial antifogging effect, durability of antifogging effect and punching quality of the formed article, and provide a formed article of the sheet and a method for producing the article. <P>SOLUTION: The styrene resin sheet is produced by coating at least one surface of a styrene resin sheet with an antifogging agent containing 30-99 mass% sucrose fatty acid ester and 1-70 mass% polyvinyl alcohol containing residual methanol and residual methyl acetate in an amount of ≤4 mass% in total. This invention further relates to the formed article of the sheet and the production method for the article. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a styrene-based resin sheet, a molded product thereof, and a manufacturing method thereof.

  Styrene-based resin sheets and molded products are widely used as packaging and covering materials, but because the surface is hydrophobic, the water that aggregates due to changes in temperature and humidity becomes minute water droplets and adheres to the surface. May occur. The cloudiness makes it difficult to distinguish the stored items and often causes a reduction in the commercial value.

  In order to solve this problem, it is described that an antifogging agent comprising a sucrose fatty acid ester, an unmodified PVA having a polymerization degree of 800 or less, and a silicone emulsion having a particle size of less than 1 μm is used (for example, see Patent Document 1).

JP 56-166234 A (page 1-9)

  The present invention relates to a styrenic resin sheet excellent in hot plate stain resistance during molding, transparency of the molded product, initial antifogging effect, durability of the antifogging effect, and punching property of the molded product, and a molded product thereof and a method for producing the same. The purpose is to provide.

  The present invention is an antifogging composition comprising 30% by mass or more and 99% by mass or less of sucrose fatty acid ester, and 1% by mass or more and 70% by mass or less of PVA in which the total of residual methanol and residual methyl acetate is 4% by mass or less. The problem is solved by forming a styrene resin sheet on which at least one surface of a styrene resin sheet is coated with an agent and a molded product obtained using the sheet.

  Since the styrenic resin sheet of the present invention, its molded product, and its production method are excellent in hot plate soiling, molded product transparency, initial antifogging effect, antifogging durability, and molded product punchability. It can be widely used for food packaging etc. and is very useful.

The present invention is described in detail below.
The anti-fogging agent essentially comprises PVA in which the total of sucrose fatty acid ester, residual methanol and residual methyl acetate is 4% by mass or less. Sucrose fatty acid ester is an ester of sucrose and a fatty acid. Examples of fatty acids constituting sucrose fatty acid esters include saturated fatty acids having about 6 to 30 carbon atoms such as caproic acid, caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, and montanic acid, and lindenic acid. , Unsaturated fatty acids having about 10 to 24 carbon atoms such as palmitooleic acid, oleic acid, elaidic acid, isooleic acid, erucic acid, linoleic acid, linolenic acid and the like, and these fatty acids may be used alone or in combination. Among these, the fatty acid which comprises a sucrose fatty acid ester is lauric acid, and the ratio as a lauric acid component is 50 mass% or more, More preferably, it is 55 mass% or more, Most preferably, it is 65 mass% or more. When the ratio as a lauric acid component is 50 mass% or more, the tendency which is excellent also in the anti-fogging effect is seen. In addition, although the fatty acid which comprises sucrose fatty acid ester comprises ester from sucrose and a fatty acid, the fatty acid before comprising the ester is said here. These sucrose fatty acid esters can be used alone or in combination of one or more.

  PVA is a homopolymer composed of vinyl alcohol units or a copolymer composed of vinyl alcohol units and vinyl acetate units, and the content of vinyl alcohol units is 50% by mass or more.

  PVA has a saponification degree and a viscosity of 4% aqueous solution at 20 ° C., but the saponification degree is preferably 70% by mass or more, more preferably 70% by mass or more and 95% by mass or less. The viscosity at 20 ° C. of a 4% aqueous solution is preferably 4 cps or more, more preferably 4 cps or more and 60 cps or less.

  The total of residual methanol and residual methyl acetate present in PVA is 4% by mass or less. Preferably it is 3.7 mass% or less, More preferably, it is 3.2 mass% or less. If the total of residual methanol and residual methyl acetate is more than 4% by mass, the hot plate is easily contaminated during sheet forming, and the hot plate is frequently cleaned and the productivity is lowered. The total of residual methanol and residual methyl acetate in the antifogging agent composition of the present invention comprising sucrose fatty acid ester and PVA is preferably 2.8% by mass or less, more preferably 2.3% by mass or less.

  The ratio of sucrose fatty acid ester and PVA in the antifogging agent is 30% to 99% by mass for sucrose fatty acid ester and 1% to 70% by mass for PVA. Preferably, the sucrose fatty acid ester is 45% by mass to 95% by mass and the PVA is 5% by mass to 55% by mass, more preferably the sucrose fatty acid ester is 60% by mass to 80% by mass and the PVA is 20% by mass or more. It is 40 mass% or less. When the combined ratio of the sucrose fatty acid ester and PVA is other than the above, the initial antifogging effect or the antifogging durability is poor.

  When the surface of the styrene resin sheet is treated with an antifogging agent, it is used as a solution in which sucrose fatty acid ester and PVA are dissolved in a solvent. As the solvent, water, alcohol or the like is used, but is not particularly limited thereto. Water is preferable for handling. In that case, the solution concentration of the sucrose fatty acid ester and PVA is not particularly limited, but is preferably 0.1% by mass to 10% by mass, more preferably 0.1% by mass to 6% by mass, and particularly preferably. Is 0.5 mass% or more and 4 mass% or less.

  The styrene resin sheet is a sheet before being treated with an antifogging agent obtained by molding a styrene resin. Styrene resins include homopolymers of styrene monomers, partially crosslinked polymers of styrene monomers, copolymers of styrene monomers, and monomers that can be copolymerized with styrene monomers. And a copolymer obtained by copolymerizing and a mixture thereof.

  Examples of the styrene monomer used in the (co) polymer include styrene, α-methyl styrene, p-methyl styrene, vinyl toluene, t-butyl styrene, and the like. Polymerizable monomers include acrylic acid, ethyl acrylate, methyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, acrylonitrile, methacrylic acid, ethyl methacrylate, methyl methacrylate, butyl methacrylate, 2-methacrylic acid 2- Examples include ethylhexyl, 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene) and the like.

  As a homopolymer of these styrene monomers or a copolymer of styrene monomers, GP (general purpose) polystyrene obtained by polymerizing styrene is preferable. Further, copolymers obtained by copolymerizing monomers copolymerizable with styrene monomers include methacrylic acid-styrene copolymer, methyl methacrylate-styrene copolymer, methyl methacrylate-methacrylic acid. An acid-styrene copolymer, an acrylonitrile-styrene copolymer, and a styrene-butadiene block copolymer are preferable.

The above styrenic monomer as long as the transparency of the polymer obtained by polymerizing the styrene monomer and / or the monomer copolymerizable with the styrene monomer in the presence of butadiene rubber is not impaired. It can also be used as a mixture with a (co) polymer that is essential.
As the styrene monomer and / or the monomer copolymerizable with the styrene monomer used here, the monomers mentioned above can be used.
Examples of the butadiene-based rubber include high-cis polybutadiene, low-cis polybutadiene, styrene-butadiene rubber, styrene-butadiene block rubber, styrene-butadiene-styrene block rubber, and partially hydrogenated polybutadiene rubber.
Furthermore, the monomer mentioned above can be used as a monomer copolymerizable with a styrene-type monomer and a styrene-type monomer.
At least one or more types of monomers and butadiene rubbers used for polymerization can be used. As a polymer that can be mixed within a range not impairing the transparency, rubber-modified impact-resistant polystyrene (HIPS) is preferable.

  Additives generally used for styrene resins can be added as long as transparency is not impaired. For example, white mineral oil is used as an internal lubricant, and stearic acid, zinc stearate, ethylene bisamide, an antioxidant, a filler, a colorant, an antistatic agent, and the like are used as a lubricant.

  Among the additives, the content of white mineral oil, which is an internal lubricant, and the content of styrene oligomer, which is the sum of styrene dimer and styrene trimer, are effective in preventing cracks when punching molded parts of antifogging stin resin sheets. Show the trend. However, if the amount of the internal lubricant or styrene oligomer is too large, the hot plate stains during molding and the transparency of the molded product tend to be inhibited. Therefore, preferably the internal lubricant in the antifogging styrene resin sheet is 0.1% by mass or more and less than 0.8% by mass, and the amount of styrene oligomer is 0.1% by mass or more and 1.5% by mass or less, more preferably. Is 0.4% by mass or more and less than 0.8% by mass of the internal lubricant and the amount of styrene oligomer is 0.3% by mass or more and 1.2% by mass or less, and more preferably 0.5% by mass or more and 0.8% by mass of the internal lubricant. The amount of styrene oligomer is less than mass% and 0.5 mass% or more and 1.0 mass% or less. The white mineral oil preferably has an initial distillation temperature of 180 ° C. or higher under reduced pressure of 10 mmHg, more preferably 200 ° C. or higher and 350 ° C. or lower. The higher the initial distillation temperature, the less the low-boiling components in the white mineral oil, and the hot plate stain during molding tends not to occur.

  Examples of the production method for processing a styrene resin into a sheet include a uniaxial stretching method, a biaxial stretching method, a multiaxial stretching method, a coextrusion method, and a lamination method, but a biaxial stretching method is preferable. In addition, for the antifogging treatment of the sheet, it is preferable to modify the surface of the sheet by a corona discharge treatment method, an ozone treatment method, a plasma treatment method or the like.

  The method for treating the antifogging agent treatment liquid into the styrene resin sheet is not particularly limited, and a method of applying using a roll coater, a knife coater, a gravure roll coater or the like can be simply mentioned. Moreover, spraying, immersion, etc. can also be employ | adopted. Of these, gravure coating using a gravure roll coater is preferred.

  The solid content of the antifogging agent on the surface of the styrene resin sheet of the present invention treated with the antifogging agent is preferably 0.01 to 0.5 g / m2, more preferably 0.01 to 0.4 g / m2, and particularly preferably 0. 0.01 to 0.25 g / m2. When the solid content of the anti-fogging agent of the tylene-based resin sheet is less than 0.01 g / m 2, a tendency to be inferior in the anti-fogging effect is seen, and when it is more than 0.5 g / m 2, coating unevenness on the sheet surface is easily noticeable, Transparency of a molded product obtained by molding the sheet tends to decrease.

  When the styrene resin sheet is also used as a packaging material or a covering material for foodstuffs, it is necessary to be transparent so that the stored item can be confirmed through the styrene resin sheet. Preferably, Haze is 5% or less, more preferably Haze is 3% or less, and particularly preferably Haze is 2% or less. Moreover, the thickness of this styrene-type resin sheet is not specifically limited, Generally, they are 100 micrometers-1 mm. This sheet is molded and used for containers.

  The molded product of the present invention is a lid container or a food pack for packaging a food product formed by using a styrene resin sheet by pressure forming, vacuum forming, vacuum pressure forming or the like.

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.
In addition, the physical-property measurement in an Example was implemented as follows.

(1) Total amount of residual methanol and residual methyl acetate: The peak area resulting from methanol and methyl acetate is obtained by gas chromatography, and the concentration is calculated by a calibration curve. The gas chromatography apparatus used is HP 6890.

(2) Internal lubricant content: The peak area resulting from white mineral oil is obtained by gas chromatography, and the concentration is calculated by a calibration curve. The gas chromatography apparatus used is HP 6890.

(3) Styrene oligomer content: The peak areas resulting from styrene dimer and styrene trimer are obtained by gas chromatography, the concentration is calculated by a calibration curve, and the styrene dimer and styrene trimer content are summed. The gas chromatography apparatus used is HP 6890.

(4) Hot plate stain resistance at the time of molding: a styrene system in which an antifogging agent is applied to a 0.4 mm thick biaxially stretched styrene-based transparent resin sheet stretched 2.5 times in the vertical direction and 2.5 times in the horizontal direction The transparent resin sheet is continuously molded using a vacuum / pneumatic molding machine PK400 manufactured by Kansai Automatic Molding Machine Co., Ltd. Before the molding, the hot plate is cleaned with a waste cloth to remove the hot plate.
As a continuous molding condition, 500 shots of a lid container (200 mm long × 120 mm wide × 50 mm high) having a flat top surface at a molding temperature of 135 ° C. were continuously molded. After molding, the hot plate was cleaned with a waste cloth, and the degree of dirt was visually evaluated.
A: The waste cloth is hardly dirty.
○: The waste was dirty about 1/3.
□: The waste cloth was dirty about 1/2.
Δ: The waste was soiled by about 2/3.
X: The waste cloth was completely soiled.

(5) Transparency of molded product: Measure the haze of the top surface of the lid container from the 401th shot to the 410th shot of the molded product continuously molded in (2) with a measuring machine NDH-1001DP manufactured by Nippon Denshoku Industries Co., Ltd. The average value was evaluated.
◎: Haze is less than 2.0% ○: Haze is 2.0% or more and less than 2.5% □: Haze is 2.5% or more and less than 3.0% Δ: Haze is 3.0% or more and 3.5% Less than x: Haze is 3.5% or more

(4) Initial anti-fogging: The lid container obtained in (3) is placed on a PSP (polystyrene paper) container with a 1 cm interval lattice pattern (the size of the lattice line is 2 mm) filled with hot water of 90 ° C. After sticking one each, it was left to stand in a 25 ° C. atmosphere for 10 seconds. Thereafter, the visibility of the lattice pattern was visually evaluated through the lid container. In addition, it evaluated using 10 containers of the 411st-420th shot.
A: The lattice pattern is almost clearly visible.
○: The lattice pattern appears to be blurred by about 1/3.
□: The lattice pattern appears to be blurred about 1/2.
Δ: The lattice pattern appears to be blurred by about 2/3.
X: The lattice pattern looks blurry as a whole.
(5) Anti-fogging durability: a lid container obtained in (3) on a PSP (polystyrene paper) container having a lattice pattern (the size of the lattice line is 2 mm) spaced 1 cm apart with hot water of 45 ° C. After sticking one each, it was further left to stand in an atmosphere at a temperature of 5 ° C. for 3 hours. Thereafter, the visibility of the lattice pattern was visually evaluated through the lid container. In addition, it evaluated using 10 containers of 421-430 shots.
A: The lattice pattern is almost clearly visible.
○: The lattice pattern appears to be blurred by about 1/3.
□: The lattice pattern appears to be blurred about 1/2.
Δ: The lattice pattern appears to be blurred by about 2/3.
X: The lattice pattern looks blurry as a whole.

(6) Punching property of molded product: 20 lid containers formed in (4) are stacked, and 20 sheets of the 20 stacked containers are prepared, and the entire lid container is cracked when punched. The number of

Example 1
A biaxially stretched GP polystyrene sheet having a sheet thickness of 0.4 mm and containing 0.6% by mass of internal lubricant and 0.7% by mass of styrene oligomer was used in the styrene resin sheet. Further, as the antifogging agent, sucrose lauric acid ester in which 70% by mass of the fatty acid constituting the sucrose fatty acid ester is lauric acid, and a 40% by mass aqueous solution thereof is used, and PVA contains residual methanol and residual methyl acetate. Using PVA having a total of 3.0% by mass, sucrose laurate and PVA were adjusted to a solid content ratio of 70% by mass and 30% by mass. Furthermore, this antifogging agent was diluted to 1.0 mass% aqueous solution, and the sheet | seat which apply | coated the solid content of the antifogging agent to 0.05 g / m <2> on the surface of one side of the sheet | seat was obtained. Moreover, the lid | cover container (200 mm length x 120 mm width x 50 mm height) was shape | molded using the sheet | seat. The internal lubricating oil is a white mineral oil having an initial distillation temperature of 230 ° C. under a reduced pressure of 10 mmHg, a 40% by mass aqueous solution of sucrose lauric acid ester, a short sugar ester LWA1570 manufactured by Mitsubishi Chemical Foods, and PVA has a saponification degree of 88%. A 4% aqueous solution having a viscosity of 23 cps at 20 ° C. was used. Table 1 shows the blending ratio of the solid content of the antifogging agent in mass%, and the obtained physical properties are also shown.

Example 2
As the antifogging agent, the sucrose laurate of Example 1 was used as the sucrose fatty acid ester, and PVA was used in which the total of residual methanol and residual methyl acetate was 3.3% by mass. The same procedure as in Example 1 was carried out except that sucrose laurate and PVA were adjusted to a solid content ratio of 50% by mass and 50% by mass. PVA used was a product having a saponification degree of 88% and a 4% aqueous solution having a viscosity at 20 ° C. of 23 cps. Table 1 shows the blending ratio of the solid content of the antifogging agent in mass%, and the obtained physical properties are also shown.

Example 3
As the antifogging agent, the sucrose laurate of Example 1 was used as the sucrose fatty acid ester, and the PVA of Example 2 was used as the PVA. The same procedure as in Example 1 was carried out except that sucrose laurate and PVA were adjusted to 90% by mass and 10% by mass in terms of solid content. Table 1 shows the blending ratio of the solid content of the antifogging agent in mass%, and the obtained physical properties are also shown.

Example 4
As the antifogging agent, the sucrose laurate of Example 1 was used as the sucrose fatty acid ester, and PVA was used in which the total of residual methanol and residual methyl acetate was 3.9% by mass. The same procedure as in Example 1 was carried out except that sucrose laurate and PVA were adjusted to a solid content ratio of 35% by mass and 65% by mass. PVA used was a product having a saponification degree of 88% and a 4% aqueous solution having a viscosity at 20 ° C. of 23 cps. Table 1 shows the blending ratio of the solid content of the antifogging agent in mass%, and the obtained physical properties are also shown.

Example 5
As the antifogging agent, the sucrose laurate of Example 1 was used as the sucrose fatty acid ester, and the PVA used in Example 4 was used as the PVA. The same procedure as in Example 1 was carried out except that sucrose laurate and PVA were adjusted to a solid content ratio of 97% by mass and 3% by mass. Table 1 shows the blending ratio of the solid content of the antifogging agent in mass%, and the obtained physical properties are also shown.

Example 6
As an antifogging agent, sucrose laurate ester and PVA of Example 1 were used for sucrose fatty acid ester and PVA. Furthermore, sucrose palmitic acid ester in which 80% by mass of the fatty acid constituting the sucrose fatty acid ester is palmitic acid was also used. At that time, sucrose laurate and sucrose palmitate were used in combination so that 60% by mass of the amount of fatty acid in the sucrose fatty acid ester corresponds to lauric acid. Other than that was carried out in the same manner as in Example 1. In addition, the short sugar ester P-1570 by Mitsubishi Chemical Foods Co., Ltd. was used for sucrose palmitic acid ester. Table 1 shows the blending ratio of the solid content of the antifogging agent in mass%, and the obtained physical properties are also shown.

Example 7
As the antifogging agent, sucrose fatty acid ester and PVA used were sucrose laurate and PVA used in Example 1, and sucrose palmitate used in Example 5. At that time, sucrose laurate and sucrose palmitate were used together so that 52% by mass of the fatty acid amount of sucrose fatty acid ester corresponds to lauric acid. Other than that was carried out in the same manner as in Example 1. Table 1 shows the blending ratio of the solid content of the antifogging agent in mass%, and the obtained physical properties are also shown.

Example 8
The styrene resin sheet contains 0.2% by mass of internal lubricant and 0.2% by mass of styrene oligomer, and a biaxially stretched methacrylic acid-styrene copolymer sheet (styrene resin is 0.4 mm thick). This was carried out in the same manner as in Example 1 except that 97% by mass of styrene and 3% by mass of methacrylic acid were used. Table 1 shows the blending ratio of the solid content of the antifogging agent in mass%, and the obtained physical properties are also shown.

Example 9
The same as Example 1 except that the styrene-based resin sheet contained 0.4% by mass of the internal lubricant and 0.4% by mass of the styrene oligomer, and used a biaxially stretched GP polystyrene sheet having a sheet thickness of 0.4 mm. Went to. Table 1 shows the blending ratio of the solid content of the antifogging agent in mass%, and the obtained physical properties are also shown.

Example 10
Using the antifogging agent of Example 1, this antifogging agent was diluted so as to be a 3.0% by weight aqueous solution, and the solid content of the antifogging agent was applied to one side of the sheet to 0.3 g / m 2. The same procedure as in Example 1 was performed except that the above was obtained. Table 1 shows the blending ratio of the solid content of the antifogging agent in mass%, and the obtained physical properties are also shown.

Example 11
Using the antifogging agent of Example 1, this antifogging agent was diluted so as to be a 5.0 mass% aqueous solution, and the solid content of the antifogging agent was applied to one surface of the sheet to 0.47 g / m 2. The same procedure as in Example 1 was performed except that the above was obtained. Table 1 shows the blending ratio of the solid content of the antifogging agent in mass%, and the obtained physical properties are also shown.

Example 12
As the antifogging agent, sucrose fatty acid ester and PVA used were sucrose laurate and PVA used in Example 1, and sucrose palmitate used in Example 5. At that time, sucrose laurate and sucrose palmitate lauric acid were used together so that 40% by mass of the fatty acid amount of sucrose fatty acid ester corresponded to lauric acid. Other than that was carried out in the same manner as in Example 1. Table 1 shows the blending ratio of the solid content of the antifogging agent in mass%, and the obtained physical properties are also shown.

Example 13
The same as in Example 1 except that the styrene resin sheet contained 1.4% by mass of the internal lubricant and 0.7% by mass of the styrene oligomer, and a biaxially stretched GP polystyrene sheet having a sheet thickness of 0.4 mm was used. Went to. Table 1 shows the blending ratio of the solid content of the antifogging agent in mass%, and the obtained physical properties are also shown.

Example 14
Example 1 except that a biaxially stretched GP polystyrene sheet having an internal lubricant content of 0% by mass (none) and a styrene oligomer content of 0.7% by mass and having a sheet thickness of 0.4 mm was used in the styrene resin sheet. The same was done. Table 1 shows the blending ratio of the solid content of the antifogging agent in mass%, and the obtained physical properties are also shown.

Example 15
The styrene resin sheet contains 0.6% by mass of internal lubricant, 0.05% by mass of styrene oligomer, and a biaxially stretched methyl methacrylate-styrene copolymer sheet (styrene resin having a sheet thickness of 0.4 mm). Was performed in the same manner as in Example 1 except that 80% by mass of styrene and 20% by mass of methacrylic acid were used. Table 1 shows the blending ratio of the solid content of the antifogging agent in mass%, and the obtained physical properties are also shown.

Example 16
The same as in Example 1 except that a biaxially stretched GP polystyrene sheet having a sheet thickness of 0.4 mm containing an internal lubricant content of 0.6% by mass and a styrene oligomer content of 1.6% by mass in the styrene resin sheet was used. Went to. Table 1 shows the blending ratio of the solid content of the antifogging agent in mass%, and the obtained physical properties are also shown.

Example 17
Using the antifogging agent of Example 1, this antifogging agent was diluted to a 0.1% by weight aqueous solution, and the solid content of the antifogging agent was applied to one surface of the sheet so that the solid content of the antifogging agent was 0.005 g / m 2. The same procedure as in Example 1 was performed except that the above was obtained. Table 1 shows the blending ratio of the solid content of the antifogging agent in mass%, and the obtained physical properties are also shown.

Example 18
Using the antifogging agent of Example 1, this antifogging agent was diluted to a 7.0% by weight aqueous solution, and the solid content of the antifogging agent was applied to one side of the sheet to 0.6 g / m 2. The same procedure as in Example 1 was performed except that the above was obtained. Table 1 shows the blending ratio of the solid content of the antifogging agent in mass%, and the obtained physical properties are also shown.

Comparative Example 1
A biaxially stretched GP polystyrene sheet containing 1.4% by mass of the internal lubricant and 0.7% by mass of the styrene oligomer in the styrene resin sheet and having a sheet thickness of 0.4 mm is used, and sucrose is used as an antifogging agent. The fatty acid ester was the sucrose laurate used in Example 1, and the PVA was a PVA having a total of residual methanol and residual methyl acetate of 8.0% by mass.
Except this, the same procedure as in Example 1 was performed. The internal lubricating oil used was a white mineral oil having an initial distillation temperature of 178 ° C. under a reduced pressure of 10 mmHg, and the PVA used was a product having a saponification degree of 88% and a 4% aqueous solution having a viscosity at 20 ° C. of 23 cps. Table 2 shows the blending ratio of the solid content of the antifogging agent in mass%, and also shows the obtained physical properties. It turns out that it is inferior to the dirtiness of a hot platen, and the transparency of a molded article.

Comparative Example 2
Using the biaxially stretched GP polystyrene sheet of Comparative Example 1 for the styrene resin sheet,
As an antifogging agent, the sucrose laurate used in Example 1 was used for the sucrose fatty acid ester, the PVA of Comparative Example 1 was used for PVA, and the sucrose laurate and PVA were 99.5 masses in a solid content ratio. % And 0.5% by mass, except that the adjustment was performed in the same manner as in Example 1. Table 2 shows the blending ratio of the solid content of the antifogging agent in mass%, and also shows the obtained physical properties. It turns out that it is inferior to the stain | pollution | contamination property of a hot platen, transparency of a molded article, and anti-fogging sustainability.

Comparative Example 3
Using the biaxially stretched GP polystyrene sheet of Comparative Example 1 for the styrene resin sheet,
As the antifogging agent, the sucrose laurate used in Example 1 was used for the sucrose fatty acid ester, the PVA of Comparative Example 1 was used for PVA, and the sucrose laurate and PVA were 80% by mass in terms of solid content. The same procedure as in Example 1 was performed except that the content was adjusted to 20% by mass. Table 2 shows the blending ratio of the solid content of the antifogging agent in mass%, and also shows the obtained physical properties. It turns out that it is inferior to the stain | pollution | contamination property of a hot platen, transparency of a molded article, and an initial antifogging effect.

Comparative Example 4
The styrene-based resin sheet contains 0% by mass (none) of the internal lubricant, 0.05% by mass of the styrene oligomer component, and a biaxially stretched methyl methacrylate-styrene copolymer sheet (styrene-based) having a sheet thickness of 0.4 mm. The resin was used in the same manner as in Example 1 except that 80% by mass of styrene and 20% by mass of methacrylic acid were used, and the antifogging agent of Comparative Example 1 was used as the antifogging agent. Table 2 shows the blending ratio of the solid content of the antifogging agent in mass%, and also shows the obtained physical properties. It turns out that it is inferior to the stain | pollution | contamination property of a hot plate, the transparency of a molded article, and the punching property of a molded article.

Comparative Example 5
Using the biaxially stretched GP polystyrene sheet of Example 1 for the styrene resin sheet,
As the antifogging agent, the sucrose laurate and PVA used in Example 1 were used for sucrose fatty acid ester and PVA, and the sucrose laurate and PVA were 99.5% by mass and 0.5% in terms of solid content. The same procedure as in Example 1 was performed except that the content was adjusted to be%. Table 2 shows the blending ratio of the solid content of the antifogging agent in mass%, and also shows the obtained physical properties. It turns out that it is inferior to anti-fog sustainability.

Comparative Example 6
Using the biaxially stretched GP polystyrene sheet of Example 1 for the styrene resin sheet,
As the antifogging agent, sucrose laurate and PVA used in Example 1 are used for sucrose fatty acid ester and PVA, and sucrose laurate and PVA are 20% by mass and 80% by mass in solid content ratio. The procedure was the same as in Example 1 except that the adjustment was made. Table 2 shows the blending ratio of the solid content of the antifogging agent in mass%, and also shows the obtained physical properties. It can be seen that the initial antifogging effect is inferior.

Claims (10)

Containing 30% by mass to 99% by mass of sucrose fatty acid ester and 1% by mass to 70% by mass of polyvinyl alcohol (hereinafter abbreviated as PVA) in which the total of residual methanol and residual methyl acetate is 4% by mass or less. A styrenic resin sheet characterized by applying an antifogging agent to at least one surface of a styrenic resin sheet. The styrenic resin sheet according to claim 1, wherein 50 mass% or more of the fatty acid constituting the sucrose fatty acid ester is lauric acid. The styrene oligomer content of the styrene resin sheet is 0.1% by mass or more and 1.5% by mass or less, and the amount of internal lubricant is 0.1% or more and less than 0.8% by mass. The styrene resin sheet as described. The styrenic resin sheet according to any one of claims 1 to 3, wherein the internal lubricant is a white mineral oil having an initial storage temperature of 180 ° C or higher under a reduced pressure of 10 mmHg. 5. The styrene resin sheet according to claim 1, wherein the amount of the antifogging agent obtained by surface-treating the styrene resin sheet is 0.01 g to 0.5 g / m 2 as a solid content. 6. The styrene resin sheet according to claim 1, wherein a biaxially stretched GP polystyrene sheet is used as the styrene resin sheet. HAZE is 5% or less, The styrene resin sheet of Claim 6 characterized by the above-mentioned. A molded article obtained by using the styrene resin sheet according to any one of claims 1 to 7. 9. The molded article according to claim 8, wherein the molded article is a food packaging container. A method for producing a styrene resin sheet, comprising gravure-coating the antifogging agent according to claim 1 on at least one surface of the styrene resin sheet.