JPS62158042A - Easily heat-sealed electricity-limiting coated film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an antistatic coated film used for packaging articles that are susceptible to static electricity damage, and in particular, it relates to an antistatic coated film that is heat-sealed on the antistatic coated surface. The present invention relates to a film suitable for use in the form of bags, etc.

[Prior art] Ordinary plastic films have a surface resistance value (JIS
This refers to the measured value based on K6911. (same below) is 1
014Ω or more, the film itself is easily charged, and other objects that come into contact with the film and receive friction are strongly charged, so antistatic treatment is required when packaging items that are susceptible to static electricity damage. was necessary. The inventors of the present invention first completed an antistatic plastic film that had low surface resistance and could be seen through, and filed an application for JP-A-60-2.
No. 14945).

Furthermore, using the above-mentioned antistatic film, Keisung, who has conducted extensive research into packaging that is most suitable for protecting items that are susceptible to static electricity damage, found that the surface with low surface resistance is not on the outside of the packaging, but on the packaged object. Found that being on the side of the object is particularly advantageous for protecting the packaged object, and based on this, completed the invention of a bag structure that is effective for protecting objects that are easily susceptible to static electricity damage. and filed Japanese Patent Application No. 199975.

However, in order to obtain a film surface with low surface resistance, the surface obtained by coating a transparent thin layer of carbon black as a conductive material and further coating a transparent thin layer of plastic,
Heat-sealing was not always easy, and extra measures were required to make the bag, such as applying adhesive or using separate tape for sealing.

[Problems to be Solved by the Invention] The present invention relates to a film that solves the problem of poor heat sealability of the conductive coated surface as described above.

[Means for solving the problem] The above problems are solved by using a heat-sealable plastic film as the base film, and by using urethane plastic as a transparent thin layer coated over a conductive thin layer containing carbon black. This problem can be solved by using HFI, which is coated with an acrylic resin containing 10% to 50% of polymer and having a secondary transition temperature of 90° C. or lower and dried and cured. Further, at this time, if the conductive layer containing carbon black is formed into a mesh shape, the heat sealability can be particularly improved.

The film used as a base material must have a heat-sealable surface.Such films include polyethylene, EVA, polypropylene, 1,2 polybutadiene, polyethylene ionomer, and many other polymers alone or in mixtures. A film or a laminated film in which these polymers are laminated as a heat-sealing surface is used.

A thin layer of conductive paint containing carbon black is coated on base film P1 to sealable plastic film A, and a thin layer of acrylic resin containing urethane prepolymer is further coated on top of that. After that, a transparent conductive layer B containing carbon black is placed on side A of the plastic film which can be dried and cured and heat-sealed.
The film of the present invention can be obtained by coating the acrylic resin layer C containing urethane in the order of ABC and then curing it.

In the film of the present invention, the role of the 0 layer is very important. Layer 0 brings Layer B into close contact with Side A, and is heat-sealed with the plastic on Side A, and has enough strong claws to protect Layer B, as well as the necessary lubricity and anti-blocking for the inner surface of the bag. must have gender. These requirements can be met by coating, drying and curing a mixture of 10 to 50% urethane prepolymer in an acrylic resin having a secondary transition temperature of 90 DEG C. or lower. Acrylic resins with a secondary transition temperature of 80°C or less include methyl acrylic acid and methacrylic acid,
Among the so-called acrylic resins, which are polymers of esters such as ethyl, butyl, and ethylhexyl, those having a second-order transition temperature of 90° C. or less are used. If the secondary transition temperature exceeds 90° C., sealing becomes difficult, which is undesirable. As the urethane prepolymer, a two-component type or a moisture-curable one-component prepolymer of polyol and polyisocyanate is used. Urethane prepolymer accounts for 10% or more of the total resin content including acrylic resin.
Add at a rate of 50%. If it is less than 10%, the heat sealing strength will be insufficient, and if it is more than 50%, the heat sealing property will be poor. In order to enhance lubricity and prevent blocking resistance, inorganic substances such as finely powdered silica and calcium carbonate, and lubricants such as polyethylene wax may be blended into the C layer as necessary.

[Example] Examples will be explained below. In the examples, the surface resistivity of the coated surface was measured by the following method. Width 10m
Prepare two elongated strip-shaped conductive rubber electrodes. Prepare a sample piece with both ends parallel to each other, and place it on a flat rubber plate.
1.1, press the electrodes at right angles to the sample at intervals equal to the width of the antecedent, measure the resistance between the electrodes, and calculate this value as the resistance between opposite sides of the square sample surface between the electrodes, In other words, it is defined as surface resistivity.

Moreover, the heat seal strength was measured according to the method of JIS Z 1707.

Actual hFA Example 1 5%
Polyethylene copolymerized with vinyl acetate was laminated to a thickness of 60 microns, and the EVA surface was subjected to corona discharge treatment. Next, a conductive paint containing carbon black and using a partially saponified EVA as a binder is coated with a coating at a thickness of 0.159/m. On top of that, a paint containing 68% acrylic resin with a secondary transition humidity of 24°C, 30% moisture-curable polyurethane prepolymer, and 2% polyethylene wax as a lubricant was applied at a dry weight of 1 g/m2. It was coated and dried at a ratio of . This was left at 40°C for 50 hours to cure the polyurethane prepolymer. The coated surface of this film had a surface resistivity of 1×10 6 Ω, and had good antistatic properties. The heat seal strength of this coated surface is 550g/
It was 15mm. A bag could be made by heat-sealing the coated sides together with the coated side facing inside.

This bag allowed the contents to be seen through. Moreover, the inner surface of this bag was slippery and the bag was easy to open. This bag is useful for packaging ICI and other items that are susceptible to static electricity damage.

Example 2 The same procedure as in Example 1 was used, except that a paint containing 60% acrylic resin with a secondary transition temperature of 50°C, 39% moisture-curable polyurethane prepolymer, and 1% polyethylene wax was used. , anti-static coating film is 17. The surface resistivity of the coated surface was 1×10 6 Ω, and the heat seal strength between the coated surfaces was 500 g/15#.

The heat seal strength of the film of Example 1, which was made by blending 98% of an acrylic resin with a next transition temperature of 24°C and 2% of polyethylene wax as a comparative example, without blending a polyurethane prepolymer, was 80 g/15 mm. Therefore, it was not possible to make a practical bag using heat sealing.

Example 3 A conductive paint containing carbon black similar to that in Example 1 was applied to the corona discharge treated surface of the @ layer film of Example 1 in the form of a square mesh with a line width of 0.5 # and a line spacing of 1.5 ni. ,
It was coated at a dry weight of 0.15 g/Td, and further coated on top of it in the same manner as in Example 1, and dried and cured to produce a conductive film.

The surface resistivity of the coated surface of this film was 5×10''Ω, and the heat seal strength between the coated surfaces was 650 g/m.

This film can be heat-sealed with its conductive, coated sides to create a bag with transparent contents, which is useful for packaging items that are susceptible to static electricity damage.

[Effects of the Invention] As explained above, the film of the present invention is a heat-sealable film coated with a transparent conductive layer containing carbon black and a resin liquid with a special composition that is a mixture of a specific acrylic resin and a polyurethane prepolymer. By overcoating the resulting plastic film surface and curing it, it becomes a conductive coated film that can be easily heat-sealed, and is particularly useful for making bags with the conductive coated surface facing inside. This provided a film that is highly suitable for packaging items susceptible to electrostatic damage.

Claims (1)

[Claims] 1. A transparent conductive layer B containing carbon black on the heat-sealable side A of the plastic film, and a secondary transition temperature 90 containing 10 to 50% urethane prepolymer.
An antistatic coated film that can be easily heat-sealed on the above-mentioned coated surface, which is obtained by coating A with an acrylic resin layer C at a temperature of 0.degree. 2. The antistatic coated film according to claim 1, wherein the conductive layer B is coated in a mesh shape.