JP3399253B2 - Anti-fog resin sheet - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an antifogging resin sheet. More specifically, it is a sheet having a surface that prevents fogging on the surface due to condensation of water vapor, and in particular, it is heated by an indirect heating method and does not reduce the antifogging property even after being formed into various shapes, for example, a container shape. Regarding a resin sheet.

[0002]

2. Description of the Related Art Conventionally, transparent resin sheets such as styrene resin sheets, polyester resin sheets, polypropylene resin sheets and vinyl chloride resin sheets have been widely used as packaging materials and lid materials for various foods. . These transparent resin sheets have excellent transparency, water resistance, and excellent moldability, but their surface is extremely hydrophobic, so water (steam) that condenses in response to changes in temperature and humidity.
Often do not wet the surface uniformly, but become fine water droplets and stop on the surface, and this adheres to the entire surface, so-called clouding often occurs. The occurrence of cloudiness not only reduces the commercial value of various containers that are characterized by transparency, but also non-uniformly agglomerated and adhered moisture affects the food stored in the containers, and In some cases, it caused problems such as deterioration and corruption.

Therefore, in order to prevent water drops from adhering to the surface of various plastic sheets or films,
A method of blending various antifogging agents and coating on the surface of a sheet or film has been proposed, and some of them have been put into practical use. For example, as a method of adding various antifogging agents to a resin to form an antifogging sheet, (1) a method of kneading a polyglycerin fatty acid ester into a vinyl chloride resin (see JP-A-54-56647) (2) ) Method of kneading polyglycerin fatty acid ester into polyolefin film (see JP-A-4-334449) (3) Polyhydric alcohol, ester of hydroxystearic acid, polyhydric alcohol and fatty acid ester antifog agent are polyolefin resin And the like (see Japanese Patent Application Laid-Open No. 6-93139). However, when an antifogging agent is kneaded into these resins, there are problems that the antifogging agent floats up on the surface of the sheet, the transparency of the sheet is extremely lowered, and the sheet surface becomes sticky and blocking occurs.

On the other hand, as a method of compensating for these drawbacks, a method of coating various antifogging agents on the surface of the sheet has been proposed. For example, sucrose fatty acid ester is added to (4) styrene-based resin sheet in an amount of 0.1 to 0.1 part by weight of a surfactant.
A method of applying a liquid mixed with 10 parts by weight (Japanese Patent Publication No. 59-59).
No. 19584) (5) A method of allowing a sucrose fatty acid ester to be present in a polyolefin-based film or sheet (see JP-A-54-99180). However, even in a sheet coated with these sucrose fatty acid esters on the surface, after heating the sheet by the indirect heating method,
There is a defect that the antifogging property is lost when a molded product is manufactured.

Furthermore, in order to make the best use of the transparency, a polyester resin sheet having an extremely good transparency used as a container is heat-molded by an indirect heating method capable of maintaining the transparency of a molded product as compared with the direct heating method. The method is adopted. Therefore, in the case of a molded product of a polyester-based resin sheet, a polyester-based resin sheet whose anti-fog property does not decrease even after molding by heating by an indirect heating method,
It was requested.

[0006]

SUMMARY OF THE INVENTION According to the present invention, a transparent resin sheet made of a polyester-based resin is heated without deterioration in transparency, particularly by an indirect heating method, and is prevented even after being formed into various shapes such as a container shape. It is an object of the present invention to provide an antifogging resin sheet which does not deteriorate in haze and does not have stickiness.

[0007]

According to the present invention, a polyglycerin fatty acid ester is added to the surface of a transparent resin sheet made of a polyester resin so that the solid content is 0.01 to 0.15 g / m ^2.
The present invention relates to an antifogging resin sheet characterized by being applied at a ratio of

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
The raw material resin for the transparent resin sheet in the present invention is a polyester resin such as polyethylene terephthalate or polybutylene terephthalate. Among the polyester resins, polyethylene terephthalate, which is composed of terephthalic acid as a carboxylic acid component and ethylene glycol as a glycol component, and other carboxylic acid components, 2,6-naphthalenedicarboxylic acid, isophthalic acid, Phthalic acid, adipic acid, sebacic acid, oxycarboxylic acid (for example, p-oxyethoxybenzoic acid, etc.)
Etc., and other glycol components such as diethylene glycol, 1,4- and 1,3-cyclohexanedimethanol, propylene glycol, 1,4-butanediol, neopentyl glycol, bisphenol A, bisphenol S, etc. Polymerized resins and the like are included.

The transparent resin sheet according to the present invention can be manufactured by a conventionally known manufacturing method such as the T-die method or the inflation method. Further, the transparent resin sheet of the present invention is a sheet that can be used by molding the sheet by thermoforming and is used for a molded product. Therefore, although it depends on the kind of the raw material resin, a non-oriented sheet is preferable.
In particular, a sheet made of polyester resin is a non-oriented sheet. The antifogging oil-permeable sheet according to the present invention is a transparent resin sheet coated with polyglycerin fatty acid ester.

The polyglycerin fatty acid ester of the present invention is an ester of a saturated or unsaturated fatty acid having 10 to 18 carbon atoms and polyglycerin. Polyglycerol having a degree of polymerization of 2 to 16 is used, and a degree of polymerization of 6 to 1
2 can be preferably used. Esters are monoesters in which one molecule of fatty acid is bonded to one molecule of polyglycerin, 2
It may be a diester having a molecule bound thereto or a triester having a molecule bound thereto, or may be a mixture of two or more thereof. As the fatty acid, specifically, capric acid,
Examples thereof include lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid and linoleic acid.

As specific examples, diglycerin laurate, diglycerin stearate, diglycerin oleate, tetraglycerin laurate, tetraglycerin stearate, tetraglycerin oleate, hexaglycerin stearate, hexaglycerin oleate, decaglycerin laurate, Examples thereof include decaglycerin stearate and decaglycerin oleate. These may be used alone or in combination of two or more. When applying the polyglycerin fatty acid ester to the transparent resin sheet,
A solution in which a polyglycerol fatty acid ester is dissolved in a solvent in a specific ratio is used.

Any solvent may be used as long as it dissolves the polyglycerin fatty acid ester, preferably water.
Alcohol, etc. The antifogging resin sheet of the present invention,
By coating the transparent resin sheet with the polyglycerin fatty acid ester at a solid content of 0.01 to 0.15 g / m ² , a film having good antifogging property and stickiness can be obtained. When the amount of solids is less than 0.01 g / m ² ,
The antifogging property of the sheet surface is inferior, and if it exceeds 0.15 g / m ² , the sheet surface becomes sticky, which is not preferable. The solid content is preferably 0.01 to 0.1 g / m ² , and more preferably 0.02 to 0.05 g / m ² . Here, the "solid content" means polyglycerin fatty acid ester dissolved in a solvent.

To produce the antifogging resin sheet of the present invention, for example, a coating step may be added during the production step of the transparent resin sheet, or the polyglycerin fatty acid ester may be dissolved in a solvent on the surface of the transparent resin sheet as a product. It is obtained by coating the solution thus prepared, and evaporating and evaporating the solvent. As the coating method, known methods such as brushing, spraying, roll coater, gravure roll coater, knife coater, rotor dampening method, dipping method and the like can be used.

The antifogging resin sheet of the present invention can be used by heating it by a direct heating method or an indirect heating method and then molding it into a desired container shape. In the direct heating method, the sheet is placed directly on the heating plate to heat it, whereas in the indirect heating method, the sheet is inserted into a heating furnace set to a predetermined temperature by a heater for a predetermined time without contacting the sheet with the heater. It is a method of indirectly heating the sheet. The sheet heated by these direct heating and indirect heating is brought into contact with a mold having a container shape, and is molded into a desired container shape by a vacuum molding method, a pressure molding method, a plug assist molding method, or the like.

[0015]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. The antifogging property of the sheet, the antifogging property of the molded product obtained by directly heating the sheet, the antifogging property of the molded product obtained by the indirect heating system, and the evaluation of the stickiness of the sheet are as follows. It carried out by the method shown.

<Anti-fog property of the sheet> 300cc of water was placed in a 500cc beaker, and the upper surface of the beaker was covered so that the antifogging agent-coated surface of the sheets obtained in Examples and Comparative Examples faced downward. , Sealed. This beaker at room temperature 2
It was immersed in a constant temperature water bath installed in a room at 3 ° C, and the water temperature in the beaker was kept at 60 ° C. After 10 minutes, the condition of the water vapor condensing on the surface of the sheet was observed with the naked eye, and evaluated as follows. No water droplets 5, 5 slightly water droplets, 4 water droplets in about 20% of the total, 3 water droplets in about 50% of the total 2, the state in which water droplets are generated in about 50% or more of the whole is set as 1.

<Anti-fog property of molded products obtained by the direct heating method or the indirect heating method> The sheets obtained by the examples and the comparative examples were (1) heated at a hot plate temperature of 95 ° C. in the direct heating method.
Heat for 2 seconds, hot plate forming machine (Kansai Automatic Forming Machine Co., Ltd., P
K-450 type) and by the pressure molding method,
In the indirect heating method, heating is performed for 6 seconds in an oven heater having an upper heater temperature of 540 ° C. and a lower heater of 330 ° C., and a vacuum forming machine (Kyoei Development Co., Ltd., FM
-2A type), the opening is 100mm by the vacuum forming method.
A container lid having a size of × 145 mm, a bottom of 70 mm × 120 mm, a height of 50 mm, and a flange of 15 mm width around the opening was formed so that the surface coated with the antifogging agent was the inside. The molded container lid was placed in a 1000 cc prismatic container with an opening of 100 mm x 145 mm, and water at 40 ° C was added to 70
The container was put in 0 cc, covered with the surface coated with the antifogging agent inside, and placed in a room at room temperature of 5 ° C. After 10 minutes, the state of condensation of water vapor on the surface of the sheet was visually observed. Evaluation,
The antifogging property of the sheet was used.

<Stickiness of Sheet> The sheets obtained in Examples and Comparative Examples were cut into a square size of 10 cm × 10 cm, and the coated surface and the non-coated surface of the antifog agent were put together to obtain 50 kg / m ² After pressing, the sheet on the non-coated side is pasted on a flat table with double-sided tape, and the sheet on the coated side is turned 2 cm from the edge of one side of the square, and a digital push gauge (made by Aiko Engineering Co., Ltd.) is placed in the center. ), The tensile load was measured 5 times right above, and the average value was taken as the stickiness value. The larger the value, the greater the stickiness, and the smaller the value, the smaller the stickiness.

Example 1 40 parts by weight of decaglycerin laurate ("Poem J-0021" manufactured by Riken Vitamin Co., Ltd.) and 5 parts of water on one side of a non-oriented polyethylene terephthalate sheet having a thickness of 0.25 mm.
A solution of 6 parts by weight and 4 parts by weight of ethyl alcohol was prepared. The prepared solution was further diluted with water and applied as a 2.5% aqueous solution with a bar coater to 2 g / m ² at 80 ° C. in a gear oven. After drying for 1 minute, an antifog resin sheet having a solid content of decaglycerin laurate on the sheet surface of 0.020 g / m ² was prepared. For the obtained anti-fog resin sheet, by the evaluation method described above, the anti-fog property of the sheet, the anti-fog property of the molded product obtained by directly heating the sheet, the anti-fog property of the molded product obtained by the indirect heating system. Table 1 shows the results of evaluation of the sheet properties and the stickiness of the sheet.

Example 2 In the same manner as in Example 1, except that a 6.25% aqueous solution of decaglycerin laurate was used, the solid content of decaglycerin laurate on the sheet surface was 0. An antifogging resin sheet of 0.050 g / m ² was prepared.
For the obtained anti-fog resin sheet, by the evaluation method described above, the anti-fog property of the sheet, the anti-fog property of the molded product obtained by directly heating the sheet, the anti-fog property of the molded product obtained by the indirect heating system. Table 1 shows the results of evaluation of the sheet properties and the stickiness of the sheet.

[0021]

Comparative Example 1 In the same manner as in Example 1 except that a 1.25% aqueous solution of decaglycerin laurate was used, the solid content of decaglycerin laurate on the surface of the sheet was 0. An antifogging resin sheet of 0.010 g / m ² was prepared.
For the obtained anti-fog resin sheet, by the evaluation method described above, the anti-fog property of the sheet, the anti-fog property of the molded product obtained by directly heating the sheet, the anti-fog property of the molded product obtained by the indirect heating system. Table 1 shows the results of evaluation of the sheet properties and the stickiness of the sheet.

Comparative Example 2 In the same manner as in Example 1, except that a 20% aqueous solution of decaglycerin laurate was used, the solid content of decaglycerin laurate on the sheet surface was 0.160 g in the same manner as in the same example. An anti-fogging resin sheet of / m ² was prepared. For the obtained anti-fog resin sheet, by the evaluation method described above, the anti-fog property of the sheet, the anti-fog property of the molded product obtained by directly heating the sheet, the anti-fog property of the molded product obtained by the indirect heating system. Table 1 shows the results of evaluation of the sheet properties and the stickiness of the sheet.

Comparative Example 3 In the example described in Example 1, sucrose laurate ester (Mitsubishi Chemical Foods Co., Ltd. "LWA-1570", water 56 parts by weight, ethyl alcohol 4 parts by weight) was used in place of decaglycerin laurate. Parts and sucrose laurate 40
Anti-fogging resin having a solid content of sucrose laurate of 0.020 g / m ² on the surface of the sheet in the same manner as in the same example except that 2.5 parts by weight of the solution) is replaced with a 2.5% aqueous solution. Created a sheet. For the obtained anti-fog resin sheet, by the evaluation method described above, the anti-fog property of the sheet, the anti-fog property of the molded product obtained by directly heating the sheet, the anti-fog property of the molded product obtained by the indirect heating system. Table 1 shows the results of evaluation of the sheet properties and the stickiness of the sheet.

Comparative Example 4 In the example described in Example 2, decaglycerin laurate was replaced by sucrose lauric acid ester (“LWA-1570” by Mitsubishi Chemical Foods Co., Ltd., 56 parts by weight of water, 4 parts by weight of ethyl alcohol). Parts and sucrose laurate 40
Anti-fogging resin having a solid content of sucrose laurate ester of 0.050 g / m ² on the surface of the sheet, in the same manner as in the same example except that the (part by weight of solution) was changed to a 6.25% aqueous solution. Created a sheet. For the obtained anti-fog resin sheet, by the evaluation method described above, the anti-fog property of the sheet, the anti-fog property of the molded product obtained by directly heating the sheet, the anti-fog property of the molded product obtained by the indirect heating system. Table 1 shows the results of evaluation of the sheet properties and the stickiness of the sheet.

[0026]

[Table 1]

From Table 1, the anti-fogging resin sheet according to the present invention has good anti-fogging property and anti-fogging property by heat molding by a direct heating plate or heat molding by an indirect heating method. It can be seen that the sheet does not decrease and the stickiness of the sheet is good. From Comparative Example 1, the solid content is 0.0
If it is less than 1 g / m ² , the antifogging property is inferior, and if it exceeds 0.15 g / m ^{2 according} to Comparative Example 2, the sheet becomes sticky, and the sheet coated with sucrose fatty acid ester on the surface is indirect heating type. It can be seen that the anti-fogging property is significantly reduced when heated and molded.

[0028]

EFFECTS OF THE INVENTION The antifogging resin sheet of the present invention does not deteriorate in antifogging property even when heated and molded by an indirect heating method, has no stickiness, and has good transparency.

Claims (3)

(57) [Claims] 1. A thermoforming material, characterized in that a polyglycerin fatty acid ester is applied to the surface of a transparent resin sheet made of polyester resin at a solid content of 0.01 to 0.15 g / m ² . Anti-fog resin sheet. 2. An anti-fogging resin characterized in that a polyglycerin fatty acid ester is applied on the surface of a transparent resin sheet made of a polyester resin at a solid content of 0.01 to 0.15 g / m ^2. A molded product, which is formed by heat-molding a sheet by a direct heating method. 3. An anti-fogging resin, characterized in that the surface of a transparent resin sheet made of a polyester resin is coated with polyglycerin fatty acid ester at a solid content of 0.01 to 0.15 g / m ^2. A molded product characterized by being heat-formed by a sheet by an indirect heating method.