JP2001269989A - Sheet molded container manufacturing method and molded container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transparent styrene resin biaxially oriented sheet molded container and its manufacturing method which maintains good releasability of a molded article in the process of molding and possesses improved practical antifogging properties. SOLUTION: A styrene resin biaxially oriented sheet, of which one surface is coated with an antifogging agent in a coating amount of 5-30 mg/m2 and the other surface is uncoated, is placed in a thermoforming machine such that the antifogging surface is to be the inside of a molded container. The sheet is thermally molded after applying silicone oil to the uncoated surface in a coating amount of 2-40 mg/m2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biaxially stretched transparent styrenic resin sheet molded container which is mainly used as a thermoformed container for lids, food packs, trays, etc., and is used in various packaging applications such as food packaging. The present invention relates to a method for producing a molded article and a molded container.

[0002]

2. Description of the Related Art Biaxially stretched polystyrene resin sheets are:
Various hot forming methods such as hot plate heating type pressure forming method, radiant heating type vacuum forming method and pressure forming method, among others, are formed by hot plate heating type pressure forming method and are often used as various forming containers including food packaging applications. ing. These styrene-based resin biaxially stretched sheet molded containers, especially food packaging containers, have a surfactant applied to the inside of the molded article as an anti-fogging agent (anti-fogging agent), and the mold releasability from the mold of the molding machine. It is generally manufactured using a sheet coated with silicone oil to impart releasability between molded articles and molded articles.

For this reason, for example, Japanese Patent Publication No. 63-6253
No. 8, JP-A-5-287097 describes a method of applying a mixture containing a sucrose fatty acid ester and a silicone emulsion as main components to a biaxially stretched polystyrene resin sheet. Also, Japanese Unexamined Patent Publication No. 9-29538
No. 4 proposes a sheet roll having one surface coated with an antifogging agent and the other surface coated with silicone oil. Further, as a method for improving the antifogging property of a biaxially stretched styrene resin sheet, a method of using a polyglycerin fatty acid ester alone or in a mixture is disclosed in JP-A-9-12751, JP-A-11-277688 and JP-A-11-277688. 11-3009
No. 04, etc. Also in these methods, when used as a sheet for thermoforming, a silicone oil is mixed with an antifogging agent to impart release and release properties together with antifogging properties, or silicone oil is applied to the opposite surface. It is described that it is preferable to use a coated sheet.

As described above, most of biaxially stretched styrene resin sheets are made of a mixture of an antifogging agent and silicone oil, or an antifogging agent on one side, in order to impart antifogging properties, release properties and release properties. The other side is coated with silicone oil and wound into a roll, and is commercially available. As antifog agents, sucrose fatty acid esters and polyglycerin fatty acid esters,
It is recognized as a food additive and is preferred as an antifogging agent for a biaxially stretched styrene-based resin sheet frequently used for food packaging. In addition, a sheet to which silicone oil is not applied causes problems such as deterioration in mold releasability between a mold and a sheet at the time of molding and deterioration in peelability between molded articles when sheet molded articles are overlapped. However, it is lacking in practicality as a molding application, but it is present.

[0005]

However, biaxial stretching of a styrene resin coated with a mixture of the above-mentioned anti-fogging agent (sucrose fatty acid ester, polyglycerin fatty acid ester, a mixture thereof, etc.) and silicone oil is applied. Molded containers obtained from a sheet or a biaxially stretched styrene-based resin sheet coated with an antifogging agent on one side and silicone oil on the other side, do not completely satisfy the level of antifogging requirements in the market. It is. The anti-fog performance required on the market for packaging containers, particularly food packaging containers, is the anti-fog property against water vapor when high-temperature contents are packaged (high-temperature anti-fog property),
Anti-fogging properties against dew condensation (low-temperature anti-fogging properties) when contents such as food containing water are packaged and stored refrigerated, and anti-fogging against both dew condensation and water vapor for contents that are heated after refrigeration And the anti-fog performance needs to be maintained immediately after packaging until the contents are consumed. The required level is increasing with the improvement in the level of anti-fog technology throughout the packaging sheet and film industry. However, it has been pointed out that a molded article of a styrene-based resin biaxially stretched sheet generally has a low-temperature antifogging level and a low sustainability, in particular, as compared with other packaging sheets and films. The lack of anti-fogging property of a molded article of a styrene-based resin biaxially stretched sheet is particularly noticeable in a molded container having a high drawing ratio, particularly at low temperatures, and the sucrose fatty acid ester and the polyglycerin fatty acid ester are used as anti-fogging agents. , And any of these mixtures.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a transparent styrene-based resin biaxially stretched sheet molding container having improved practical anti-fogging properties while maintaining mold release properties during molding, and a method for improving the peelability of molded articles. To supply a transparent styrene-based resin biaxially stretched sheet molded container with good and practical anti-fog properties, that is, at a low temperature even in a styrene-based resin biaxially stretched sheet molded container, especially a molded product having a large drawing ratio. Improved initial antifogging level and its sustainability, and good initial antifogging and sustained antifogging properties at high temperatures, good mold release from molding machine molds and good releasability between molded products Another object of the present invention is to provide a method for producing a molded article of a biaxially stretched styrene resin sheet and a molded article.

[0007]

Means for Solving the Problems The inventors of the present invention have studied to achieve the above object, and as a result, it has been found that the reduction in the antifogging property of a biaxially stretched styrene-based resin sheet is described, for example, in JP-B-63-62538.
In the case of a sheet using a mixture of an antifogging agent and a silicone oil as described in Japanese Patent Application Publication No. JP-A-2005-110, a sucrose fatty acid ester as an antifogging agent and a silicone oil (silicone emulsion) having no antifogging effect are mixed. For this reason, the antifogging property for an extremely short time is good, but a remarkable decrease in the antifogging property is observed with time, and an antifogging agent such as sucrose fatty acid ester or polyglycerin fatty acid ester is applied on one side, and When silicone oil is applied, a sheet to which silicone oil has hardly been transferred has an excellent anti-fog effect, but there is a disadvantage that the anti-fogging property decreases with an increase in the transfer ratio of silicone oil, and At present, it is very difficult to suppress the transfer of silicone oil to a level that does not adversely affect the anti-fog property (these types of sheets usually use silicone oil). More than 40% of N'oiru is transferred,
(Which has an adverse effect on the anti-fogging property), and the present invention has been achieved.

That is, a first invention is a method of forming a biaxially stretched styrene resin sheet into a container by a thermoforming machine, wherein one side is coated with 5 to 30 mg / m ² of an antifogging agent,
On the other side, an uncoated styrene-based resin biaxially stretched sheet roll is attached to a thermoforming machine such that the anti-fog surface is on the inside of the molding container.
A method for producing a styrene-based resin biaxially stretched sheet-molded container, characterized in that a styrene-based resin biaxially stretched sheet-molded container is characterized by applying a thickness of 40 to 40 mg / m ² and thermoforming the sheet.
g / m ² coated, the opposite side of which is coated with an uncoated styrene-based resin biaxially oriented sheet roll in a thermoforming machine so that the anti-fog surface is inside the molding container. Was applied by ² to 40 mg / m ² and thermoformed.
m ² (based on the container opening area), ² to 40 mg / m of silicone oil or silicone powder on the outside
( ² ) A container for forming a biaxially stretched styrene-based resin sheet, which is coated (based on the container opening area).

Hereinafter, the present invention will be described in detail. The present invention
Based on this finding, based on this finding, it was found that the decrease in anti-fogging property of a biaxially stretched styrene-based resin sheet was attributable to silicone oil, which is indispensable for imparting release and releasability of the sheet. This was achieved by using a biaxially stretched styrene-based resin sheet (hereinafter referred to as “stretched sheet”) coated with silicone oil and applying silicone oil before molding and heating.
The present invention provides a method for producing a styrene-based resin biaxially stretched sheet molded article having a level of antifogging which is difficult to achieve with the prior art without deteriorating mold release properties or peelability, and a molded article molded by the production method. Supply.

First, a method for manufacturing a stretched sheet molded product common to the first and second inventions will be described. In the present invention, the stretched sheet used has an antifogging agent on one side of 5 to 5.
30 mg / m ² coated and the other side is uncoated. If the amount of the antifogging agent coated on one side is less than 5 mg / m ² , the intended antifogging performance cannot be obtained, and 30 mg / m ²
If it exceeds / m ² , it is an area where the sheet becomes sticky. In particular, when the sheet is formed by a hot plate heating type pressure air forming machine, or when a sheet that requires high anti-fog properties is formed and used as a lid material, coating by fine roughness of the sheet surface due to hot plate contact The amount of the antifogging agent should be 10 to 25 mg / m ² from the viewpoint of preventing the deterioration of the antifogging property resulting from the nonuniformity of the film and the viewpoint of preventing the appearance of the molded article from being deteriorated due to the transfer of the antifogging agent to the hot plate. More preferred.

The kind of antifogging agent applied to the stretched sheet is not particularly limited, and various generally known surfactants can be used. Preferably, sucrose fatty acid esters, polyglycerin fatty acid esters, and sorbitan fatty acid are used. Esters, polyoxyethylene sorbitan fatty acid esters,
Polyoxyethylene glycerin fatty acid esters, polyoxyethylene alkyl ethers, nonionic surfactants such as polyoxyethylene fatty acid esters,
Particularly for food packaging containers, sucrose fatty acid esters, polyglycerin fatty acid esters, sorbitan fatty acid esters alone or a mixture thereof are preferred. The anti-fogging agent may be added with a water-soluble polymer such as polyvinyl alcohol as an anti-fogging property improver, or methylcellulose or the like as a hardness modifier for the anti-fogging property.

Further, it is also possible to add a silicone powder or a water-soluble modified silicone oil to the antifogging agent in order to assist the releasing property and the releasability of the sheet molded product. Silicone powders include known silicone resin powders, silicone rubber powders, silicone composite powders, and powders obtained by blending a silicone polymer with a carrier material.
Average particle size 0.1 μm to 10 μm, preferably 0.5 μm
m-5 μm silicone powder can be used. The lower limit of the average particle diameter is determined from the viewpoint of imparting the releasability and releasability of the sheet, and the upper limit is a value determined from the viewpoint of the transparency of the sheet. It is preferable that these powders are suspended in an antifogging agent solution and applied as a silicone powder at ² to 25 mg / m ² . When the coating amount is less than 2 mg / m ² , the effect of improving the releasability and the releasability of the stretched sheet molded product (the auxiliary effect of the silicone oil) cannot be obtained, and 25 mg / m ^2.
When the ratio exceeds / m ² , the silicone powder is detached from the sheet and transferred to a hot plate of a molding machine or a roller of the molding machine. If necessary,
In a silicone powder suspension, polyvinyl alcohol,
A water-soluble polymer such as sodium polyacrylate, polyvinylpyrrolidone, sodium polyphosphate, and polyphosphate K may be added as an adhesive between the silicone powder and the stretched sheet. good.

Examples of the water-soluble modified silicone oil include polyether-modified silicones in which some of the methyl groups of ordinary silicone oil (dimethylpolysiloxane) are modified with polyoxyethylene and / or polyoxypropylene. Those that are water-soluble are preferred. These modified silicone oils are preferably applied at ² to 30 mg / m ² . If the coating amount is less than 2 mg / m ² , the effect of improving the releasability and releasability of the stretched sheet molded product (assisting effect of silicone oil) cannot be obtained, and if it exceeds 30 mg / m ² , the sheet becomes sticky. This is an area where there is a risk of occurrence.

The method of applying the anti-fogging agent is not particularly limited. A spray coater, gravure coater, air knife coater, roll coater, knife coater may be used. It can be performed by coating and drying by other known methods.
In order to further enhance the anti-fogging effect, before coating the anti-fogging agent, the surface of the anti-fogging agent coated surface should have a contact angle of 35 to 6 with pure water.
It is preferable to perform corona treatment so as to be 0 °. If the contact angle is less than 35 °, there is a risk of blocking, and if it exceeds 60 °, the effect of improving the antifogging property cannot be expected.

The surface opposite to the surface coated with the antifogging agent is an uncoated surface. The uncoated surface may be a completely untreated polystyrene surface, or may have been subjected to a surface treatment such as a corona treatment. In particular, in the case of applying a silicone oil to be applied before molding and heating, which will be described later, with an emulsion, it may be preferable to perform corona treatment evenly. In this case, the contact angle between the corona-treated sheet and pure water is preferably 75 to 35 °. When the amount exceeds the upper limit, the effect of corona treatment (uniform application of the aqueous solution) cannot be obtained, and when the amount is less than the lower limit, blocking is likely to occur.

In the method for producing a molded container and the molded container of the present invention, the above-mentioned stretched sheet having one surface coated with an antifogging agent can be used in a thermoforming machine to be described later in which the surface of the stretched sheet coated with the antifogging agent is a molded product. After being mounted inside, before the sheet is heated by a hot plate or a radiant heater, ² to 40 mg / m ² of silicone oil is applied to the surface opposite to the antifogging agent coated surface. In the present invention, the silicone oil applied before heating the sheet is a modified silicone oil such as a polyether-modified silicone oil obtained by copolymerizing dimethylpolysiloxane, methylphenylpolysiloxane, diphenylpolysiloxane, polyoxyethylene and / or polyoxyalkylene. Can be used. Among them, dimethylpolysiloxane having a viscosity of 100 to 10,000 cs is particularly preferable. Silicone oil may be used in the form of an oil solution or an aqueous emulsion emulsified by a known method.
It is preferable to apply 0 mg / m ² . When a water-soluble polyether-modified silicone oil is used, it is also possible to apply the above amount ( ² to 40 mg / m ² ) after preparing the aqueous solution. If the application amount is less than 2 mg / m ² , the releasability and releasability of the stretched sheet molded product will not be obtained, and if it exceeds 40 mg / m ² , the molded product will become sticky and stain on the molding machine mold. It is the area where it occurs. In particular, when a molded product such as a fitting container, which is difficult to release from a molding machine mold and in which silicone oil is easily transferred to the mold, is manufactured, the amount of silicone oil applied is preferably 5 to 30 mg / m ^2. preferable.

When the silicone oil is applied in the form of an emulsion, a surfactant is added to the emulsion as an antistatic agent per 100 parts by weight of the silicone oil.
It is also possible to add １００100 parts by weight. The silicone oil can be applied by a known method such as a spray coater, a gravure coater, a roll coater, and a knife coater. After coating, it may be dried by a drier, a drying furnace or the like, if necessary.

Thermoforming method (thermoforming machine) used in the present invention
There is no particular limitation, and a generally known sheet thermoforming method, for example, a hot plate heating type pressure forming method, a vacuum forming method, a pressure forming method, a vacuum pressure forming method, a plug assist forming method, or the like can be used. Of these, a hot plate heating type pressure forming method is the most common as a stretched sheet forming method, and it is preferable to employ this method also in the present invention. The present invention can be practiced by using a thermoforming machine capable of continuous molding and installing a coating facility between a sheet mounting section and a heating section of the molding machine. In addition, since sheet feeding of a molding machine is generally intermittent, application unevenness of silicone oil is likely to occur. For this reason, a drive roller or the like is provided between the coater and the heating unit of the molding machine, coating is performed continuously, a sheet pool is provided after the drive roller, and the stretched sheets in the pool are sequentially heated with a hot plate or radiantly heated. Then, it is preferable to eliminate the coating unevenness by forming a smoothing roll after the coater, or separately, if coating unevenness countermeasures are taken by intermittent feeding of the sheet of the molding machine, this does not apply. .

The stretched sheet molded product according to the second invention of the present invention is obtained by the above-described production method. The container of the present invention has a coating of 5 to 30 mg / m ² of the antifogging agent on the inner side (however, the coating amount of the antifogging agent in the molded container is obtained by dividing the amount of the antifogging agent present inside the container by the area of the container opening. And the outside of the container is coated with ^{2 to} 40 mgm ² of silicone oil (however, the coating amount of silicone oil in the molded container is determined by the amount of silicone oil existing outside the container and the area of the opening of the container. Divided by the value).

If the amount of the antifogging agent coated on the inside of the molding container is less than 5 mg / m ² , the desired antifogging performance cannot be obtained, and if it exceeds 30 mg / m ² , the container becomes sticky. This is the area where the error occurs. In the case of a lid material that requires a particularly high anti-fog property and a clear feeling of the container, or a deep drawing container with a large container surface area compared to the container opening area, the surface of the container due to the sheet hot plate contact during molding From the viewpoint of preventing the coating film from becoming non-uniform due to fine roughness and preventing the anti-fogging property from being reduced due to the extension of the anti-fogging agent film during molding, and reducing the appearance of the molded article due to the transfer of the anti-fogging agent to the hot plate during molding. From the viewpoint of prevention, the amount of the antifogging agent is more preferably 10 to 25 mg / m ² . Also,
The antifogging agent used in the molding container is the same as that used in the above-described stretched sheet (the same applies to silicone powder and the like that can be added to the antifogging agent).

Further, the coating amount of the silicone oil coated on the outside of the container is preferably ² to 40 mg / m ² . When the coating amount is less than 2 mg / m ² , the releasability of the molded article is insufficient, and when it exceeds 40 mg / m ² ,
This is the area where stickiness of the molded product occurs. Good adhesion between molded products, especially when superimposed, such as food packs, requires high releasability, and silicone oil on the outer surface of the molded product may transfer to the inner surface of the molded product due to the adherence of the molded products. In the case of a certain container, it is more preferable that the amount of silicone oil applied is 5 to 30 mg / m ² . The silicone oil used for the molding container is the same as that applied to the stretched sheet before the above-mentioned molding heating.

The styrene resin constituting the stretched sheet used in the present invention includes homopolymers of styrene monomers selected from styrene, alkylstyrenes, halogenated styrenes and the like, and copolymers thereof. Block, random, graft copolymers of a rubber component such as a conjugated diene (butadiene, isoprene, etc.), a styrene-conjugated diene copolymer or the like and the above-mentioned styrene-based monomer, 50% by weight or more of the above-mentioned styrene-based monomer and other It is a block, random or graft copolymer with a monomer.
In addition, known additives such as plasticizers such as mineral oil, terpenes, and petroleum resins, antistatic agents, and ultraviolet absorbers may be added to these styrene resins.

Among these resins, preferred are styrene homopolymer (GPPS), styrene-methacrylic acid copolymer, styrene-maleic anhydride copolymer, styrene-
Styrene-alkyl (meth) acrylate copolymers such as butyl (meth) arylate copolymers and GPs
Blend with PS, styrene-conjugated diene block copolymer (SBBC), SBBC and GPPS or styrene
And a blend with an alkyl (meth) acrylate copolymer.

The stretched sheet used in the present invention can be prepared by extruding the above resin by a known method such as T-die, circular die, or the like, by a known method such as roll stretching, tenter stretching, bubble stretching, and the like. Times, preferably 4 to 16 times, thickness 0.1 to 1 mm, preferably 0.13
mm to 0.5 mm. The stretched sheet used in the present invention may be a known multilayer sheet containing one or more layers of the above-mentioned styrene-based resin, in addition to the single-layer sheet made of the above-mentioned styrene-based resin. As the multilayer sheet, for example, GPPS (surface layer) / GPPS + SBBC (inner layer),
Heat-resistant styrenic copolymers such as styrene-methacrylic acid copolymer (surface layer) / GPPS (inner layer), GPPS (surface layer) / styrene-alkyl (meth) acrylate copolymers (inner layer), high molecular weight GPPS (surface layer) ) / Medium to low molecular weight GPPS (inner layer), GPPS + SBBC (surface layer) / G
PPS (inner layer), GPPS (surface layer) / plasticized GPPS
A publicly known sheet having two, three, or four or more layers based on a combination of layers such as (inner layer) can be used.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to embodiments. The performance evaluation of the sheets and films in the examples and comparative examples was performed according to the following criteria (unless otherwise specified, “O” or more is a pass level of the present invention).

(Low-Temperature Anti-Fogging Property) Two pieces of sushi (temperature: 27 to 30 ° C.) and radish cut into small pieces are placed in a foamed polystyrene fitted container body (100 mm × 100 mm, depth: 8 mm), and the following will be described from a stretched sheet. 100 manufactured by the method
cover with a fitting cover with a size of 100 mm × 100 mm and a depth of 35 mm.
℃ showcase, after 10 minutes (initial anti-fog), 2
After 4 hours (sustained antifogging), the adhesion of water droplets was evaluated according to the following criteria. ：: A mirror-like water film was observed on the entire surface of the molded container lid, and the entire surface was transparent glass, and the inner surface was completely visible. ：: Cracks in the water film are partially observed in an area of 25% or less of the lid of the molded container, but the overall appearance is somewhat “smoky” but good. Δ: Cracks in the water film were partially observed in an area of less than 50% of the lid of the molded container, and the contents were visible, but the overall appearance was “smoky”.
are doing. ×: Partial water film cracks were observed in 50% or more of the area of the molded container lid, or small water droplets of about 5 mm or less were generated.

(High-Temperature Sustained Anti-Fogging Property) An opening 100 manufactured from a stretched sheet by a method described later at a position 25 mm from the water surface in a constant temperature water bath controlled at 60 ± 1 ° C.
Place a molded product with a size of 100 mm × 100 mm and a depth of 35 mm.
The adhesion of water droplets after the time was evaluated based on the following criteria. ：: A mirror-like water film was observed on the entire surface of the molded container lid, and the entire surface was transparent glass, and the inner surface was completely visible. ：: Cracks in the water film are partially observed in an area of 25% or less of the lid of the molded container, but the overall appearance is somewhat “smoky” but good. Δ: Partial water film cracks were observed in an area of less than 50% of the lid of the molded container. Alternatively, water droplets of 5 mm or less are observed at the corners of the molded article. ×: Cracks in a partial water film are observed in an area of 50% or more of the lid of the molded container, or small water droplets of about 5 mm or less are generated even in a portion other than the corner portion.

(High temperature initial anti-fog property) Opening 100 mm x 100 mm, depth 50 mm, with a board on which 100 katakana 100 characters of 10.5 point half size were printed at the bottom
After placing 400 ml of water at 90 ° C. in the container of (1), an opening 100 mm × 100 m manufactured from the stretched sheet by the method described later.
m, a cover having a depth of 35 mm was covered with the molded product, and the time until 15% or more of characters placed on the bottom could not be identified was measured at n = 6, and the average was evaluated according to the following criteria. ：: 300 seconds to less than 600 seconds Δ: 120 seconds to less than 300 seconds ×: less than 120 seconds

(Releasability of Molded Product) A food pack is manufactured from a stretched sheet by the method described below, and eight sets of 25 shots are punched out and punched. After standing for 1 minute, the hoods are lifted one by one. The peelability of the main body at the time of the evaluation was evaluated according to the following criteria. ◎: Can be peeled satisfactorily on molded articles of 98% or more: good peelability. ：: Molded articles of 95% or more can be peeled satisfactorily and do not overlap with three or more sheets. ~ 95% of the molded product can be peeled off satisfactorily, or 9
0% or more is good, but 3 or more sheets may be overlapped and lifted: inferior in releasability (however, it may be practical depending on the shape of a molded product). ×: Less than 90% of molded articles that can be peeled well: No peelability The method for producing a stretched sheet is as follows.

[0030]

[Stretched sheet production example 1] Polystyrene (GPPS) is supplied to an extruder, extruded from a T-die, stretched 2.8 times vertically by a speed ratio between rolls, and then stretched 3.0 times horizontally with a tenter. A 0.25 mm biaxially oriented polystyrene sheet was obtained.
One side of this sheet was adjusted with a corona treatment machine so that the contact angle with pure water became 40 ° on average, and then one spray coater was used to apply an antifogging agent (sucrose fatty acid ester: 72% of the fatty acid component was lauric acid). ) Of 0.3, 0.5, and 0.9% by weight were sequentially supplied, and an aqueous antifogging agent solution was applied to the corona-treated surface at 3 g / m ² (9, 15, 27 solids).
mg / m ² ), and then continuously dried by a hot air drier, and the sheet is wound into a roll.
(9 mg of antifogging agent), 2 (15 mg of antifogging agent), and 3 (27 mg of antifogging agent) were obtained.

[0031]

[Stretched sheet production example 2] A liquid supplied to the coater was mixed with decaglycerin monolaurate, hexaglycerin monolaurate and a sucrose fatty acid ester as described above in a 3: 1: 6 mixture as antifogging agent, for a total of 0.5 weight. %, Silicone powder (spherical silicone resin powder having an average particle diameter of 0.8 μm), 0.3% by weight, and polyvinyl alcohol at 50% by weight based on the weight of the silicone powder. Thus, a stretched sheet 4 was obtained.

[0032]

[Stretched Sheet Production Example 3] A sheet extruded and stretched in the same manner as in Production Example 1 was subjected to two corona treatment machines to average the contact angle of the antifogging agent-coated surface with pure water at 40 ° and the opposite surface to pure water. After adjusting the contact angle to an average of 65 °, a 7: 3 mixture of a sucrose fatty acid ester and a silicone emulsion (dimethylpolysiloxane having a viscosity of 1000 cs) was used in a single spray coater. The same amount of antifogging agent was applied, and a silicone oil emulsion (a 60-fold diluted aqueous solution containing 30% of dimethylpolysiloxane having a viscosity of 10,000 cs) was supplied to another spray coater. 3 g / m ² (solid content of 1 g / m ² ) was applied to the opposite surface (surface adjusted to an average contact angle of 65 °).
After applying 5 mg / m ² ), it was continuously dried with a hot air drier and wound up in a roll to obtain a stretched sheet 5.

[0033]

[Stretched Sheet Production Example 4] The antifogging agent was prepared by mixing the above sucrose fatty acid ester and hexaglycerin monolaurate (weight ratio: 7).
5:25), and the solid content of the antifogging agent is 25
mg / m ² , the solid content of silicone oil is 20 m
A sheet 6 was obtained in the same manner as in the production example 3 of the stretched sheet except that g / m ² was used. After aging the sheet for 5 days, it was confirmed by IR (ATR method) that 42% of the silicone oil on the wound sheet was transferred.

[0034]

Example 1 A roll-shaped stretched sheet 2 was attached to a hot-plate heating type pressurized air molding machine (a continuous molding machine manufactured by Kansai Automatic Molding Machine Co., Ltd.) so that the anti-fog treatment surface was inside the container, and the hot-plate heating was performed. Before coating the uncoated surface of the stretched sheet with a spray coater, 15 mg / m ^{2 of} silicone oil (10-fold diluted aqueous solution of 30% dimethylpolysiloxane having a viscosity of 10000 cs) was applied as a solid matter at 15 mg / m ² , and then heated on a hot plate and compressed air. A fitting lid having a size of 100 mm x 100 mm and a depth of 30 mm and a food pack of a standard size were manufactured by molding. The releasability between the molded product and the mold at the time of molding is good, and the obtained molded product has low-temperature antifogging properties (both initial antifogging and continuous antifogging), sustained high temperature antifogging properties, and initial high temperature antifogging properties. In each case, the level was “◎”, and the releasability of the molded product was also “◎” level.

[0035]

Examples 2 to 4, Comparative Examples 1 and 2 Rolled stretched sheet 1 (Example 2), rolled stretched sheet 3 (Example 3), rolled stretched sheet 4 (Example 4), roll Stretched sheet 5 (Comparative Example 1), rolled stretched sheet 6
A molded product was obtained in the same manner as in Example 1 except that (Comparative Example 2) was used. The releasability between the molded article and the mold during molding was good for all sheets. Table 1 shows the evaluation results of the molded articles.

[0036]

Comparative Example 3 The same procedure as in Example 1 was carried out except that the rolled stretched sheet 2 was used, and the silicone oil was not applied before heating the hot plate. In this case, as for the fitting container, the molding machine mold and the sheet molded product could not be produced smoothly because the mold release property was not smooth. In addition, the food pack was scratched due to friction with the mold at the time of mold release, and only molded articles of low commercial value were obtained. The stretched sheet 2 was molded into a fitted container by a single-shot molding machine, and the antifogging property was evaluated. As a result, the high-temperature sustained antifogging property and the high-temperature initial antifogging property were all “◎” levels.

[0037]

Examples 5 and 6 Molding was carried out in the same manner as in Examples 1 (Example 5) and 3 (Example 6) except that the silicone emulsion was diluted 30 times and the silicone oil coverage was 5 mg / m ^2. Product was obtained. In the case of Example 5, the mold releasability between the molded product and the mold at the time of molding was able to be formed without any problem of generating a slightly high sound at the time of mold release, and Example 6 was good.
Table 1 shows the evaluation results of the molded articles.

[0038]

Example 7 Using silicone oil (dimethylsiloxane oil having a viscosity of 100 cs), the silicone oil was applied with a roll coater, and then a portion of the silicone oil was scraped off from the sheet with a smoothing roll to reduce the amount of application.
A molded product was obtained in the same manner as in Example 1 except that the amount was adjusted to 0 mg / m ² . The releasability between the molded product and the mold during molding was good. Table 1 shows the evaluation results of the molded articles.

[0039]

[Table 1]

[0040]

According to the method for producing a sheet-formed container and the molded container of the present invention, silicone oil is applied to the uncoated surface of a biaxially stretched styrene-based resin sheet in which one side is coated with an antifogging agent and the other side is uncoated. It is characterized by performing thermoforming after doing, and retains the releasability and releasability of the practical level of sheet molding,
It shows an excellent antifogging effect that cannot be obtained with a conventional biaxially stretched styrene resin sheet product. For this reason,
It can be suitably used as various types of molded containers, including those for food packaging requiring excellent antifogging properties.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C08L 25:04 C08L 25:04 F term (Reference) 4F006 AA15 AB39 AB69 BA09 BA10 CA07 DA04 4F208 AA13 AB09 AC03 AD08 AD11 AG03 AG07 AH57 AH58 MA01 MA02 MB01 MB22 MG04 MG12 MH06

Claims (2)

[Claims] 1. A method for forming a biaxially stretched styrene resin sheet into a container by a thermoforming machine, wherein one side is coated with 5 to 30 mg / m ² of an antifogging agent and the other side is uncoated. After attaching a biaxially stretched sheet roll to a thermoforming machine so that the anti-fog surface is inside the molding container, apply ² to 40 mg / m ² of silicone oil to the uncoated surface and thermoform the sheet. A method for producing a biaxially stretched sheet molded container for a styrene resin. 2. An antifogging agent is coated on one side with 5 to 30 mg / m ² , and the other side is coated with an uncoated biaxially stretched styrene resin sheet roll. after attaching so, the silicone oil to 40 mg / m ² was applied to the uncoated surface, molded by the method of thermoforming, anti-fogging agent inside a 5 to 30 mg / m ² (container opening area 2) silicone oil on the outside
A styrene-based resin biaxially stretched sheet molded container coated with 〜40 mg / m ² (based on the container opening area).