JPH0228919B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an antistatic film suitable for packaging electronic devices susceptible to electrostatic damage. polyethylene, polypropylene,
Plastic films such as polyvinyl chloride are
The surface resistance value (measurement method is based on JIS K6911,
(The same applies hereinafter) It has a resistance of 10 ¹⁴ Ω or more and is easily charged, so it is necessary to treat it to prevent static electricity when packaging items that are susceptible to static electricity.

Plastic film coated with an antistatic agent is used to prevent static electricity, but since the antistatic agent used for coating is an oil-like or wax-like substance, it is necessary to apply a large amount to achieve low surface resistance. However, when trying to obtain a product, the surface became sticky, and it was easily washed away by water, resulting in a loss of effectiveness.

In addition, there are ionic conductive resins with ionic functional groups that are known as treatment agents for reducing the surface resistance of electrophotographic paper, electrostatic recording paper, etc. These are applied to the surface of plastic film to create a conductive layer.
Although it is possible to prevent static electricity, ionic conductive resins are water-soluble or water-swellable, have weak water resistance, and have drawbacks such as being prone to surface stickiness and blocking when air humidity is high. Ta.

The film of the present invention is an antistatic film suitable for practical use, with no surface stickiness or blocking, low surface resistance, and high antistatic ability.

In the film of the present invention, a conductive layer made of an ionic conductive resin or a mixture of an ionic conductive resin and an ionic or nonionic organic conductive agent is provided on a plastic film, and the conductive layer is closely attached to the outside. , the volume resistance is 1×10 ¹³ Ω・cm or less,
This is an antistatic plastic film with a water-resistant plastic layer less than 10μ thick.

A coating method is preferably used to form a conductive layer of a conductive resin or a mixture of a conductive resin and a conductive agent on a plastic film. The plastic film is preferably subjected to a corona discharge treatment in advance to improve its adhesion.

The layer of water-resistant plastic placed closely outside the conductive layer must have a volume resistivity of less than 1×10 ¹³ Ω·cm and a thickness of less than 10 microns. The volume resistivity is 1×10 ¹³ Ω・cm or more and the thickness is
If it is 10μ or more, the surface becomes easily charged, which is not preferable. The water-resistant plastic should be one that can be coated, is water resistant, and satisfies the surface properties required for a packaging film, such as hardness, gloss, slipperiness, and anti-blocking properties. Should. The volume resistivity of the water-resistant plastic itself may be such that the resin itself has a low electrical resistance of 1×10 ¹³ Ω・cm or less, but the resin itself may have a high volume resistivity of 10 ¹⁴ Ω・cm or more. However, in order to make the antistatic film of the present invention, it has been found that the film formed by coating directly on the conductive layer often exhibits a low volume resistivity of 10 ¹³ Ω・cm or less. . Although the cause of this is unknown, it is thought that the water-resistant plastic film is denatured due to the influence of the conductive layer components during film formation.

Therefore, whether or not it can be used as a water-resistant plastic layer should not be determined based on the normal volume resistivity of the water-resistant plastic layer, but rather, it should not be determined based on the normal volume resistivity of the water-resistant plastic layer. This can be easily determined by measuring the resistance value by contacting the membrane with a surface contact type electrode.

The antistatic plastic film of the present invention exhibits the following excellent properties.

Low surface resistance and high antistatic ability.

Even in high atmospheric humidity, the surface does not become sticky and does not cause blocking.

Even when the surface is exposed to running water, the surface resistance does not increase, and the antistatic ability can be maintained for a long period of time.

The surface has water resistance, does not swell with water, and the entire film is resistant to deterioration in performance due to water.

This will be explained below using examples.

Example 1 A water-soluble and lower alcohol-soluble compound containing a cationic quaternary ammonium functional group,
A mixture of 95 parts by weight of a toluene-insoluble acrylic conductive resin and 5 parts by weight of hexadecyltrimethylammonium chloride, which is a cationic conductive agent, was made into an ethyl alcohol solution.

Both sides of a 60μm thick polyethylene film,
The wetting tension was adjusted to 41 dynes/cm by corona discharge treatment. On one side of this film, the above mixture solution was applied in a dry amount of 5 g/m ² and dried. Furthermore,
A dry amount of 1 g of a toluene solution of polymethyl methacrylate resin was applied onto the coated surface and dried.
The polymethyl methacrylate resin layer has a thickness of approximately 1μ. After leaving this film for 4 weeks,
When the surface resistance of the coated surface was measured, it was 9×10 ⁶ Ω. Also, the surface resistance of the back non-coated surface is 3×
10 ¹² Ω, and the back surface also had good antistatic properties. This coated surface had good water resistance and did not change even after being exposed to running water for 1 minute. This film can be heat-sealed with its non-coated sides together to form a bag, and is useful for packaging items that are susceptible to electrostatic damage.

Note that the surface resistance was measured in accordance with JIS K6911. The measurement electrodes were a mercury electrode with a diameter of 5 cm and a donut-shaped mercury electrode with an inner diameter of 7 cm and an outer diameter of 8 cm arranged concentrically with the electrode, and the contact area was 11.8 cm ² for the donut-shaped pole and 19.6 cm ² for the circular one in the center. It is. Also,
Before applying the polymethyl methacrylate resin layer, the surface resistance of the film coated with the conductive layer is 6×
It was 10 ⁶ Ω. Difference from surface resistance after applying polymethyl methacrylate resin layer, 3×10 ³ Ω
However, with a coating layer of 1μ polymethyl methacrylate,
The volume resistivity of the coated layer is calculated to be 2×10 ¹¹ Ω·cm based on the volume resistivity between the portion in contact with the electrode and the conductive layer below. Although this value is a very low value as a volume resistivity value, it is considered that the polymethyl methacrylate layer is altered by the components of the conductive layer.

Example 2 A mixture of 92 parts by weight of an ethyl alcohol-soluble styrene-type conductive resin containing an anionic functional group and 8 parts by weight of dimethyldodecyl alkyl betaine, which is an amphoteric conductive agent, was made into an ethanol solution. Both sides of a 60 μ thick EVA film were treated with corona discharge to adjust the wetting tension to 40 dynes/cm, and the above mixture solution was applied to one side of the film at a light weight of 10 g/m ²
It was applied, dried and left for two weeks. The surface resistance of the coated surface was 3×10 ⁷ Ω, and the surface resistance of the non-coated surface behind the coated surface was 4×10 ¹¹ Ω. On this coated surface,
Furthermore, an acrylic latex containing polymethyl acrylate as a main component was applied in a dry amount of 2 g/m ² and dried. The surface resistance was 5×10 ⁷ Ω, the surface hardness was increased, and the water resistance was also improved. The volume resistivity of the acrylic latex coating was determined from the coating thickness of the acrylic latex in the same manner as in Example 1, and was found to be 7×10 ¹¹ Ω·cm. This value is also a very low value as a volume resistivity value, and it is considered that the latex coating film has been altered by the components of the conductive layer.

Example 3 One side of a 20 micron thick polypropylene film was treated with corona discharge to adjust the wetting tension to 41 dynes/cm. An aqueous emulsion of an acrylic polymer having cationic quaternary ammonium functionality was applied to the corona-treated side of the film at a dry weight of 3 g/m ² and dried. The surface resistance of the coated surface was 5×10 ⁷ Ω. This coated surface had poor gloss and swelled significantly when exposed to water, so it had many drawbacks for general use in packaging. On top of this coated surface, apply a toluene solution of polystyrene.
A dry amount of 1 g/m ² was applied and dried. The coated surface had a surface resistance of 9×10 ⁷ Ω and was glossy. Although running water was applied to the coated surface for 1 minute, there was no change. The volume resistivity of the polystyrene coating is 3×10 ¹² Ω·cm, which is a very low value for volume resistivity. It is thought that the polystyrene coating film is altered by the components of the acrylic conductive layer.

This film is useful as a laminating film with excellent antistatic properties.

Example 4 A water-soluble and lower alcohol-soluble compound containing a cationic quaternary ammonium functional group,
90 parts by weight of a toluene-insoluble acrylic conductive resin and 4 parts by weight of a nonionic surfactant as a conductive agent.
A mixture of parts by weight and 6 parts by weight of cationic octadecyltrimethylammonium chloride was made into an ethyl alcohol solution. Both sides of a polyethylene film having a thickness of 40 microns were subjected to corona discharge treatment to adjust the wetting tension to 41 dynes/cm, and the above solution was applied to one side in a dry amount of 8 g/m ² and dried. The surface resistance of this coated surface was 1×10 ⁶ Ω. On this coated surface, a polyvinylidene chloride emulsion was further applied in a dry amount of 10 g/m ² by a spray method and dried. When the surface resistance was measured after two weeks, the coated surface had a resistance of 5×10 ⁶ Ω, and the back uncoated surface had a resistance of 2.
×10 ¹² Ω. Since the specific gravity of polyvinylidene chloride is 1.7, the thickness of the water-resistant plastic layer is 6 microns, and the volume resistivity of this layer is 5×
It was 10 ¹¹ Ω・cm.

This film has a layer of polyvinylidene chloride, so it has a high resistance to oxygen and water vapor, and is not static-charged, so it is susceptible to static electricity damage.
Moreover, it is useful for packaging articles that may be deteriorated by moisture or oxygen.

Claims (1)

[Claims] 1. A conductive layer made of an ionic conductive resin or a mixture of an ionic conductive resin and an ionic or nonionic organic conductive agent is provided on a plastic film, and the volume resistivity is Antistatic plastic film with a water-resistant plastic layer of 1×10 ¹³ Ω・cm or less and a thickness of 10μ or less.