JPS62270335A - Plastic film with antistatic layer - 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 3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a plastic film having an antistatic layer. More particularly, the invention relates to plastic films with antistatic layers that can be produced by coextrusion.

(Prior art) Conventionally, gold-N thin films such as gold, platinum, silver, palladium, and aluminum have been formed on transparent polymer films, and semiconductor thin films such as indium oxide, tin oxide, cadmium oxide, and steel iodide have been formed on transparent polymer films. The formed transparent conductive plastic films are known, and these are used for transparent electrodes for displays, transparent heating elements, electrostatic shield transparent windows, light selective transmission films, and the like. These are usually vacuum evaporation methods, CV
It is manufactured by vapor deposition methods such as the D method, ion blasting method, or sputtering method, but the equipment used in these methods is complicated and expensive, and it is difficult to manufacture general-purpose transparent conductive films that are used in large quantities. Not only is it unsuitable for manufacturing purposes, it also has poor transparency because the energy absorbed by free electrons is close to the visible light range, and it also has poor transparency between transparent conductive films and polymer films. There were drawbacks such as insufficient adhesion, the transparent conductive film peeling off during various steps of manufacturing transparent electrodes, and insufficient durability during use. Among these drawbacks, various improvements have been made, especially regarding adhesion (for example, Japanese Patent Application Laid-Open No. 13123/1983)
No. 8, No. 60-131711, Special Publication No. 60-3909
However, durability such as wear resistance is not sufficient.

On the other hand, an antistatic agent such as a quaternary ammonium salt (for example, JP-A-52-136274
), surfactants (e.g., Japanese Patent Publication No. 60-44149), carbon blanks (e.g., Japanese Patent Publication No. 60-2149),
No. 45) Other conductive powders (e.g. JP-A No. 61-24)
It is also known to form a layer of No. , conductivity is lost by washing with water. Furthermore, in order to connect the coater and drying equipment online, it is limited to water-based coating from the viewpoint of explosion protection, and when coating and drying are performed online, there is also the disadvantage that the equipment becomes large-scale.

In addition, in the method of providing a conductive layer on the surface of the film, if it is necessary to lower the surface resistance on both sides of the film, it is necessary to provide the conductive layer on both sides of the film, which is complicated. It is. In order to prevent these drawbacks, surfactants such as alkyl sulfonates and polyalkylene glycols are incorporated into the film (for example, as disclosed in JP-A No. 52-47072,
JP-A-56-149455), surfactants precipitate on the surface over time, causing stickiness and cloudiness, and washing with water not only causes loss of antistatic ability, but also some antistatic agents may interact with the film. It had the drawback of poor compatibility and devitrification of the film. Furthermore, when carbon black or the like is used, there is a drawback that transparency is insufficient.

(Problems to be Solved by the Invention) The present inventors have made extensive studies to solve these conventional drawbacks, and have found that when a finely divided conductive metal oxide is kneaded into a plastic film, it is scratch resistant. It is possible to obtain a conductive plastic film with good properties and no humidity dependence, and by laminating the conductive plastic film and a plastic film that does not contain conductive fine particles by co-extrusion, it is possible to obtain a conductive plastic film that has good properties and is not dependent on humidity. It has been discovered that high-performance antistatic ability can be imparted, and the present invention has been achieved.

Therefore, a first object of the present invention is to provide a plastic film having an antistatic layer that has good resistance and is not dependent on humidity.

A second object of the present invention is to provide a plasti or kufilm having an antistatic layer that is not dependent on humidity and has excellent transparency and reliability.

A third object of the present invention is to provide a plastic film having an antistatic layer that is easily slippery and is not dependent on humidity.

A fourth object of the present invention is to provide a method for producing a plastic film having an antistatic layer with excellent scratch resistance and no humidity dependence, the conductivity of which can be easily adjusted.

(Means for Solving the Problems) The above aspects of the present invention are based on the raw materials for plastic films and ZnO, TiO2, Al2O3, rn, 2O3, S
iO2, MgO,, BaO.

Simultaneously coextruding a raw material for a plastic film containing at least one crystalline metal oxide selected from MoO3, SnO and/or at least one of these crystalline composite oxides. This was achieved by a plastic film with an antistatic layer formed by.

Examples of raw materials for plastic films used in the present invention include cellulose-based raw materials such as cellulose triacetate, cellulose acetate butyrate, and cellulose acetate propionate; polyester-based raw materials such as polyethylene terephthalate and polyethylene naphthalate;
Although polycarbonate, polystyrene, polyethylene, polypropylene, etc. can be used, polyester, polycarbonate, and polyethylene are preferred among them, and polyester is particularly preferred from the viewpoints of dimensional stability, moldability, film strength, etc.

A coloring agent, an ultraviolet absorber, a heat ray cutting agent, etc. may be added to these raw materials as necessary.

Examples of the conductive metal oxide used in the antistatic layer in the present invention include ZnO1'rio2.5n02, A (1
203, In2O3,5io2, MgO, B20, Mo
Crystalline metal oxides such as O3 and composite oxides thereof can be mentioned, but among these, especially ZnO, Ti
O2 and 5n07 are preferable, and as the composite oxide, Z
Aβ, In, etc. for n○, Nb for 'rto2,
Those containing 0.01 to 30 mo1% of different elements such as Sb, Nb, and halogen elements based on 5n02, such as Ta, are preferable, and those containing 0.1 to 10 mo1% are particularly preferable. It is preferable that the crystal has oxygen defects or contains a small amount of a foreign atom that serves as a so-called donor for the metal oxide, since the conductivity is improved.

These conductive metal oxides have a particle size of 0.1μ in diameter.
It is preferable to use fine particles of ~2μ, preferably 0.1μ to 1μ, in order to improve the transparency of the film into which they are mixed.

Such conductive fine particles can be manufactured as follows. That is, the first method is a method in which metal oxide fine particles are produced by firing and then heat-treated in the presence of foreign atoms that improve conductivity, and the second method is a method in which metal oxide fine particles are produced by firing. The third method is to reduce the oxygen concentration in the atmosphere and introduce oxygen defects when producing metal fine particles by firing. These methods can also be combined as appropriate.

Details of these are described in, for example, Japanese Patent Application Laid-Open No. 143430/1983.

In the present invention, in order to adjust the conductive particle size to the above range, fine particles that do not directly contribute to improving conductivity are micronized to prevent particles from agglomerating together and becoming coarse particles. It can be made to coexist as an auxiliary agent when producing conductive fine particles. Particles used for this purpose include fine metal oxide particles (e.g. ZnO, TiO2, 5i
02, Al2O3, MgO, BadSWO3, MoO
3, p2o5, etc.), BaSO4, SrSO4, CaSO
3. Fine particles of sulfate such as MgSO4, MgCO3, Ca
Examples include fine particles of carbonate such as CO3.

A more detailed explanation of the production of fine conductive particles can be found, for example, in JP-A-56-143430.

The resistance of the antistatic layer in the present invention can be easily adjusted by adjusting the volume content of conductive fine particles in the film. The proportion of the conductive fine particles is preferably 10% to 80% in terms of volume content.

The plastic film having an antistatic layer of the present invention is
Any one selected from the above raw materials for plastic film and the conductive fine particles are added to a plastic film raw material that is the same as the plastic ring material or has good compatibility and can be made under the same film forming conditions. It can be easily produced by simultaneously coextruding a predetermined amount of .

The conditions for producing a film by coextrusion can be appropriately set from among known techniques, but usually two extruders and a T-die with a feed block or multi-manifold are used for coextrusion. When strictly controlling the thickness of each layer, it is preferable to use a manifold type T-die.

When laminating three layers using a manifold type T-die, the outer two layers can contain conductive fine particles to create a plastic film with antistatic layers on both sides. When the two layers do not contain conductive fine particles, a plastic film having an antistatic layer in the middle layer can be used. These films are preferably uniaxially or biaxially stretched according to a conventional method.

The thickness of the antistatic layer is preferably 50% or less of the thickness of the entire plastic film, particularly preferably 1 μm or less. If the thickness of the antistatic layer is made too thick,
This is not preferable because it not only increases manufacturing costs but also deteriorates the strength of the entire film.

The plastic film having an antistatic layer of the present invention is
When the conductivity is 10 9 to 10 10 Ω, it can be used as an antistatic sheet for glass, walls, etc.

In addition, when the conductivity is 105 to 106 Ω/c, it can be used as an electrostatic recording material or touch panel, or 102 to 103 Ω/c.
When it is ta, it can be used as an electromagnetic barrier.

Furthermore, by providing an adhesive layer on one side, the method of use can be facilitated and the range of uses can be expanded.

(Effects of the Invention) Since the plastic film having the antistatic layer of the present invention uses finely divided metal oxide as the conductive particles, good transparency can be easily obtained. Furthermore, since the conductive particles used in the present invention are ionic conductors, they are not only unaffected by humidity, but also are kneaded into the film, and since the films are bonded together by co-extrusion, the adhesion between the films is improved. is extremely good, and the antistatic ability of the film as a whole is permanent.

Furthermore, when the antistatic layer is on the surface, minute irregularities are formed on the surface by the conductive particles kneaded into it.
It also has the secondary effect of improving the lubricity of the film.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto.

Example 1 [Preparation of tin oxide-antimony oxide composite dispersion] 230 parts by weight of stannic chloride hydrate and 23 parts by weight of antimony trichloride were dissolved in 300 parts by weight of ethanol to obtain a homogeneous solution.

An aqueous solution of IN sodium hydroxide was added dropwise to this solution until the pH of the solution became 3 to obtain a coprecipitate of colloidal stannic oxide and antimony oxide. The obtained coprecipitate was
C. for 24 hours to obtain a reddish-brown colloidal precipitate.

A reddish-brown colloidal precipitate was separated by centrifugation. In order to remove excess ions, water was added to the precipitate and the precipitate was washed with water by centrifugation. This operation was repeated three times to remove excess ions.

200 parts by weight of the colloidal precipitate from which excess ions have been removed are redispersed in 1500 parts by weight of water and sprayed into a calcining furnace heated to 600°C to form a bluish tin oxide-antimony oxide composite with an average particle size of 0.15μ. A fine powder of the product was obtained. The specific resistance of this fine particle powder was 25Ω. Polyethylene terephthalate (abbreviated as PET) containing 70 ffl of the obtained conductive fine particles and a PET film containing no conductive fine particles were co-pressed into a film. I got it.

Table 1 shows the results of measuring the surface resistance, static friction coefficient (μS), and dynamic friction coefficient (μk) of the film of the present invention obtained in this way and a PET film that does not contain conductive particles for comparison. there were.

Table 1 ° -Ω Haze S μ at 30% R) I Lumum of the invention 5 X 108 10χ 0.36
0.30ET Flume 1016 1χ 1ν - However, each measurement was performed as follows.

Measurements of μS and μ were performed according to the ASTM D 1894 method.

To measure the surface resistance, measure the surface resistance of the sample at 25°C and 10% R.
The measurement was carried out in an atmosphere of H using an insulation resistance measuring instrument VE-30 model (manufactured by Kawaguchi Denki ■).

The degree of haze was measured for each sample using an integrating sphere type haze meter (Model 5EP-H-3 manufactured by Nippon Seimitsu Kogaku Co., Ltd.).

As is clear from the results in Table 1, it was demonstrated that the film of the present invention has good transparency, sufficient antistatic ability even at low humidity, and also has good lubricity.

Claims (1)

[Claims] 1) Raw materials for plastic film, ZnO, TiO_
2, Al_2O_3, In_2O_3, SiO_2, M
Simultaneously coextruding a raw material for a plastic film containing at least one crystalline metal oxide selected from gO, BaO, MoO_3, and SnO_2 and/or at least one of these crystalline composite oxides. A plastic film with an antistatic layer formed by 2) A layer containing a crystalline metal oxide and/or a composite oxide is provided so as to cover at least one surface of a plastic film that does not contain the oxide. Plastic film with antistatic layer. 3) A plastic having an antistatic layer according to claim 1, wherein a layer containing a crystalline metal oxide and/or a composite oxide is sandwiched between plastic films not containing the oxide. film. 4) Claims 1 to 3, characterized in that the raw material for the plastic film is polyester resin.
A plastic film having an antistatic layer according to any one of paragraphs.