JPS5935922B2 - Coating agent for styrene resin film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coating agent for styrenic resin films.

More specifically, the present invention relates to a coating agent suitable for improving the printability, blocking property, and antifogging property of styrenic resin films. Styrenic resin films, such as general-purpose polystyrene films, have excellent transparency, water resistance, and high gas permeability, and are widely used as packaging materials for foodstuffs and the like. However, this styrene-based resin film has poor printability, making it difficult to print clearly, and the printing ink tends to set off.Also, when a long film is wound, the films stick to each other, which is a so-called problem. A blocking phenomenon often occurs, causing problems in use.

In addition, when used as a packaging container for food, etc., moisture that evaporates from the food stored in the container aggregates and adheres to the inner surface of the container, making it impossible to observe the stored items, as well as causing discomfort to the purchaser. The downside is that there are things you can do. Conventionally, in order to improve such drawbacks, methods have been developed such as applying corona discharge treatment to the film surface, adding certain auxiliary agents or fine inorganic substances to the styrene resin for pool unevenness production and forming a film, and Methods such as applying a certain type of surfactant have been proposed, but none of these methods can be said to be sufficient in terms of durability, economic efficiency, or transparency, and printing Although it is possible to improve either the properties, blocking properties or anti-fog properties,
It was not possible to improve these properties all at once.

Therefore, the present inventor aimed to improve these drawbacks. As a result of various studies, we have arrived at the present invention. That is,
The purpose of the present invention is to provide a coating agent that can improve the printability, blocking property, and antifogging property of styrenic resin films. A coating agent for a styrenic resin film characterized by containing higher fatty acid ester 5 and/or zorbitan higher fatty acid ester. The present invention will be explained in detail below.

Examples of the styrenic resin in the present invention include general purpose polystyrene, acrylonitrile-styrene copolymer, rubber-reinforced polystyrene, styrene-butadiene block copolymer, and ABS resin.

These may be used alone or in a mixture of two or more with good compatibility. The coating agent according to the present invention is applied to a film obtained from these styrene resins by an appropriate method such as a T-die method or an inflation method.

The coating agent of the present invention must first contain a vinyl synthetic resin emulsion as a first component. As for the synthetic resin emulsion. Acrylic acid, acrylonitrile. Acrylic polymers or copolymers such as acrylic esters. Vinyl acetate, vinyl chloride. Vinylidene chloride. Polymers or copolymers such as polyvinyl alcohol. Polyvinyl acetal. Examples include emulsions of vinyl polymers such as polyvinyl methyl ether. especially. For example, methacrylic acid ester-acrylic acid ester copolymer. Emulsions such as vinyl acetate-vinyl chloride copolymer, vinyl acetate-methacrylic acid ester copolymer, and ethylene-vinyl acetate copolymer are preferably used. These emulsions are usually. A water-based type is used. for example. A non-aqueous type using ethyl alcohol as a dispersion medium can also be used. In the coating agent of the present invention. Sucrose higher fatty acid ester and/or zorbitan higher fatty acid ester are blended as the second component into the above-mentioned synthetic resin emulsion, which is the first component.

Sucrose or zorbitan higher fatty acid ester. usually. HLB value is 9 or less. More preferably 1 to 7. Particularly preferably 4 to 6. It is an ester of a higher fatty acid having usually about 6 to 22 carbon atoms, more preferably about 10 to 20 carbon atoms, and sucrose or zorbitan. As a higher fatty acid. in particular. for example. Purinic acid. Lauric acid. Myristic acid. Palmitic acid. Stearic acid, oleic acid. Examples include linoleic acid.

If you use one with an HLB value of over 9. The film absorbs moisture and causes bumping. Also. This may cause the printing ink to change over time, but if the purpose is to improve the antifogging properties of the film. These can also be used successfully.

In addition. In the present invention. Of course, those obtained by adding ethylene oxide to some of the above esters can also be used.

Sucrose higher fatty acid ester. Zorbitan fatty acid ester. Alone. Or both may be used together. Also. Small amounts of other third surfactants may also be used. water resistance. Or from the point of view of difficulty in foaming. It is more preferable to mainly use sucrose higher fatty acids.

The blending ratio of sucrose and/or higher fatty acid ester of zorbitan in the present invention is. Usually 0.1 to 10% by weight based on the solid content of the synthetic resin emulsion. Preferably 0.5~
3% by weight 1 and these formulations are e.g. It is done as follows.

Heating higher fatty acid esters. Dissolve. Partial saponification is performed by adding a small amount of alkali. Next. Add hot water to make an emulsion with a solids content of 10-30% by weight.

Next, the emulsion of the higher fatty acid ester is added to the synthetic resin emulsion in the above ratio and mixed well.

In this way. The resulting coating agent is. It is applied to styrene resin film. As for the method of application,
usually. Brush painting, spraying, roll coater, gravure roll coater. Known methods such as knife coaters, dipping methods, etc. can be used. In particular, it is most often done by a roll coater.

In other words. Continuously when using a roll coater. The amount of application can be changed freely. In addition. The coating agent of the present invention is a pigment. Or other additives. for example. Viscosity modifier. Antifoaming agent. Preservatives and the like can be appropriately used in combination using conventional methods. The coating agent of the present invention has the following effects. In other words. The styrenic resin film using the coating agent of the present invention is... Even when a long film is wound into a roll, it does not cause so-called flopping, where the film pieces stick together. It can have unique surface characteristics such as excellent slipping properties.

In addition. The coating agent according to the present invention does not impair the transparency of the base film. It can prevent fogging on the film surface and has an extremely excellent anti-fog effect.

Furthermore. It has extremely good printability. For example, alcoholic or aqueous gravure inks can also be used.

In this way, the coating agent according to the present invention... It is possible to improve the printing properties, blocking properties, and antifogging properties of a styrene resin film, and its industrial utility value is great. below. The present invention will be explained in more detail with reference to Examples. The present invention is not limited to the following examples unless it exceeds the gist thereof. In addition. In the examples. What does "department" mean? Indicates "parts by weight".

Example 75 parts of methacrylic acid methyl ester (40% solids emulsion). Sucrose higher fatty acid ester (HLB: 5
．． A mixture of 10 parts of 20% emulsion) and 15 parts of water was added. A clear coating was obtained.

<Plocking property test> The obtained coating agent was applied to one side of a biaxially stretched polystyrene film using a roll coater method. The coated surface was dried with radiant heat, and the film was wound into a roll.

The film is wound into a roll. I was able to unwind it smoothly without causing any flopping. <Printing suitability test> When we printed on the coated surface of this film with alcohol-based gravure ink, applied zero tape to the printed surface and peeled it off, the printing ink did not adhere to the zero tape at all. It did not peel off from the printed surface.

<Anti-fogging property test> G) Meat was placed in a container formed so that the surface coated with the film was on the inside, and the container was heat-sealed with a lid so that the surface coated with the film was on the inside.

The coated surface was brought into contact with meat. The inside of the container was transparent, and no clouding occurred even when the meat was stored at a low temperature of -5°C, and no clouding occurred even when stored at this temperature for 48 hours. Even after repeated cold storage and room temperature storage. No clouding occurred on the inner surface of the container. (mouth) 30 liters of water in a 500 cc beaker
Enter 0CC. The above film was placed on top of the beaker with the coated side facing down, and the beaker was sealed. This beaker was placed indoors near a sunny window where the temperature difference between day and night is the greatest, and the appearance of the film surface was observed with the naked eye. The state of adhesion of condensed water was visually observed for two months.

Due to temperature differences between day and night or changes in vapor pressure, water vapor reaches its dew point and condenses on the film surface. The condensed water does not form droplets on the film surface, but wets it evenly. The film remains transparent. Its antifogging properties were extremely excellent. Comparative Example A biaxially oriented polystyrene film was produced by a conventional method. Without applying any coating agent. It was wound up into a roll as in the example.

The film is wound into a roll. The films stuck to each other and it was difficult to unwind them smoothly. Print on this film with alcohol-based gravure ink. As in the example, zero tape was applied to the printed surface and then peeled off. A portion of the printing ink peeled off from the printed surface and adhered to the zero tape.

Claims (1)

[Claims] 1. A coating agent for a styrenic resin film, comprising a vinyl synthetic resin emulsion and a sucrose higher fatty acid ester and/or a sorbitan higher fatty acid ester.