JP2008074901A - Low humidity-dependent antistatic primer and composite resin film using the primer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a low humidity-dependent antistatic primer having no reduction in antistatic performance, high adhesivity to a plastic film and yet excellent transparency even at a low humidity and a composite resin film using the same. <P>SOLUTION: The low humidity-dependent antistatic primer comprises a mixture of amorphous conductive tin oxide, a polyester polyol-based urethane polymer and an acrylic copolymer. The polyester polyol-based urethane polymer and the acrylic copolymer have carboxy groups in the molecular structures. The composite resin film is combined by using the primer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The primer of the present invention is an intermediate primer having both characteristics of prevention of deterioration of antistatic performance, improvement of adhesion between a deposition material and a plastic film, and transparency of the primer, particularly in a silica or alumina-deposited plastic film. And a composite resin film using this primer.

In general, vapor-deposited plastic films of dielectric materials such as silica and alumina generate extremely strong triboelectric charge, so electrostatic damage in the post-processing steps (laminate, printing, bag making, etc.) of these films is a serious problem. . As a measure for preventing static electricity, a method of kneading an antistatic agent into the vapor deposition base film is conceivable. However, the adhesion between the vapor deposition material and the film is poor, and it is not generally implemented. In addition, a vapor-deposited film is not used alone, and a laminate film having a vapor-deposited surface as an intermediate layer is usually used. As an antistatic measure, an antistatic agent is generally kneaded into a laminate base film. .
However, since the conventional antistatic agent is an ionic conductive system with moisture, when the humidity in the air is 15 to 20% or less, the antistatic performance is remarkably lowered.

Therefore, the present inventor has proposed a low-humidity-dependent antistatic primer that is not deteriorated in antistatic performance even under low humidity, has high adhesion to a plastic film, and is excellent in transparency. JP-A-2002-80775).
According to the primer of this prior application, it is possible to obtain a composite film that does not deteriorate the antistatic performance even under low humidity and has high adhesion to the film, excellent transparency, and low humidity dependency. In the present invention, among these characteristics, an object is to provide a primer improved so as to further improve the adhesion to the film and a composite resin film using the primer.

  In order to achieve the above object, in the invention described in claim 1, in the low humidity dependent antistatic primer, it comprises a mixture of amorphous conductive tin oxide, polyester polyol urethane polymer and acrylic copolymer polymer. It is characterized by this.

  Furthermore, in the invention described in claim 2, in the low-humidity-dependent antistatic primer, the polyester polyol-based urethane polymer described in claim 1 has a carboxyl group in the molecular structure and is an acrylic copolymer. It is a polymer mixture having a carboxyl group in its molecular structure.

  Furthermore, the invention according to claim 3 is characterized in that the polymer according to claim 2 is obtained by neutralizing a water-insoluble resin having a carboxyl group with ammonia or an organic amine and making it water-soluble. It is.

  Furthermore, in the invention described in claim 4, the antistatic composite resin film is combined using the primer described in any one of claims 1 to 3.

  As described above, the present invention provides a mixture of amorphous conductive tin oxide and acrylic copolymer polymer in a low-humidity-dependent antistatic primer, and further mixed with a polyester polyol-based urethane polymer, particularly silica and alumina. In the vapor-deposited film, it is possible to provide a primer and a composite resin film having a high adhesion force that cannot be realized by the above-mentioned Japanese Patent Application No. 2000-272025.

Acrylic copolymer polymer or polyester polyol-based urethane polymer having a carboxyl group in the side chain is a binder of tin oxide particles as a means that the dried coating film of amorphous tin oxide aqueous sol solution has strong adhesion to the plastic film surface It is effective for. In this case, the polymer added to the sol solution should be adjusted to a stable, colorless and transparent sol solution without causing white precipitation in the solution due to the stability breakdown of the tin oxide particles in the sol solution. Is essential. In addition, since this prepared sol solution is water-soluble, the coating film repelling phenomenon occurs due to the difference in surface tension when coating on the plastic film surface, so the addition of surfactant is generally considered. Is unsuitable because it causes poor adhesion.
That is, this sol solution is a colorless and transparent stable liquid without aggregation and precipitation of amorphous tin oxide particles in the solution, and there is no repellency phenomenon in the coating film, and it is a colorless and transparent with strong adhesion. It is to make a sol solution to be a coating film.

  The amorphous tin oxide sol according to claim 1 of the present invention is a colorless transparent liquid adjusted to pH = 9.8 to 10.0 containing a small amount of ammonia as a sol stabilizer at a solid content concentration of 8% by weight, The solid content concentration of the mixture was adjusted to about 40% by weight and pH = 7.5 to 8.5 with an aqueous dispersion obtained by neutralizing carboxyl groups in the polyester polyol urethane polymer and acrylic copolymer of claim 2. A translucent white liquid obtained by making these white liquids and mixing them can be made.

  The mixed liquid obtained here can determine the adhesion of the coating film on the film surface and the performance of the surface electrical resistance value by the mixing ratio of the present tin oxide sol and the present resin mixture. This mixed liquid can form a uniform coating film with excellent surface adhesion and excellent adhesion to plastic film surfaces such as PET, OPP, ONY, silica-deposited PET, and alumina-deposited PET. The surface electrical resistance value of the film is almost unaffected by humidity and exhibits a characteristic that exhibits a substantially constant low resistance value. These evaluation values are shown in the examples described later.

  The anti-static deposition film such as silica or alumina can be made by the coating agent of the present invention by the anti-static agent in the low humidity environment that cannot be achieved by the conventional humidity-dependent ion conductive anti-static coating agent. it can. Moreover, by using the base film for vapor deposition coated with the coating agent of the present invention, it becomes a means for solving the vapor deposition obstacle due to static electricity generated in the base film.

In addition, since the dry coating film of this coating agent forms the outstanding water-resistant coating film, it can hold | maintain the outstanding adhesiveness also with respect to a hygroscopic film like an ONY film.
The following examples describe the adjustment of the coating agent and the performance of the coating agent coating film.

The mixed sol solution of the present invention comprises an aqueous dispersion (B) obtained by neutralizing and mixing an amorphous stannic oxide sol solution (A), a polyester polyol polyurethane resin, and an acrylic copolymer with an organic amine. It was prepared as a mixed solution.

Above (A) solution: Appearance = colorless transparent liquid
pH = 10.0
Solid content = 8.0% by weight
(B) Solution: Appearance = White emulsion solution
pH = 8.0
Solid content = 8.0% by weight (stock solution 40% diluted with water to 8%)

Three types of antistatic coating materials were prepared by mixing and preparing the above solutions at the ratios shown in Table 1.

Each of the above antistatic coating agents was applied to various plastic films with a gravure coating type coater, and dried to produce a trial antistatic film. The gravure coating type coater used for coating has a dryer that is 2 m long and divided into 3 zones. The drying capacity has a maximum air volume of 120 m ³ / min and a maximum temperature of 120 ° C., and can run a film having a maximum width of 1,200 mm. The coating gravure cylinder used is 175 lines, 30 microns deep. The coating speed was set to 50 m / min, and the drying conditions were set to the first zone (60 ° C.), the second zone (70 ° C.), and the third zone (75 ° C.).

  The antistatic coating material of the present invention is aqueous, and a corona discharge treated surface was used for coating on a plastic film. However, in the case of a silica-deposited PET film, the silica surface was used. Tables 2 and 3 show the surface electrical resistance value and triboelectric charge value of the coating film.

The above results show that the amorphous stannic oxide antistatic agent shows sufficient antistatic performance even in a low humidity environment (20% RH), but the cationic organic ion conductive antistatic agent has a humidity. Even if the surface electrical resistance value at 50% RH is E9, it is generally E12 Ω / cm ² or more at a humidity of 20% RH, and generally exhibits no antistatic performance. In addition, as shown in Table 3, the frictional voltage was 0.0 to 0.1 kv at a low humidity of −20% RH on the coating surface and the back surface (the frictional band voltage was measured 20 times on both sides of the coating surface and the back surface). Friction and immediately after measurement with a static measuring instrument manufactured by Nihon Statech.

  Table 4 shows the results of a comparative evaluation of the adhesion of various plastic film coating films by a peel test using a cellophane adhesive tape.

  From the performance evaluation of surface resistance, frictional voltage, and adhesion to plastic film as shown in Table 2, Table 3, and Table 4, depending on the mixing ratio of amorphous conductive stannic oxide and resin binder, it can be achieved in the past. An antistatic primer in a low-humidity environment that does not exist is an innovative feature of the present invention.

A configuration example of a composite resin film using the above-described primer is shown below.
Deposition base film / primer / adhesive layer / heat seal film

Claims (4)

  A low humidity-dependent antistatic primer comprising amorphous conductive tin oxide, a mixture of a polyester polyol-based urethane polymer and an acrylic copolymer.   The polyester polyol-based urethane polymer according to claim 1 is a polymer mixture having a carboxyl group in the molecular structure and a carboxyl group in the molecular structure of the acrylic copolymer. Antistatic primer.   The aqueous low-humidity-dependent antistatic primer according to claim 2, wherein a water-insoluble resin having a carboxyl group is neutralized with ammonia or an organic amine and water-solubilized.   The antistatic composite resin film combined with the primer of any one of the said Claims 1 thru | or 3.