JPH0471414B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing a fluororesin molded product for heat sealing.

[Prior Art] Films, sheets, fabrics, etc. made of fluororesins have excellent properties such as heat resistance, chemical resistance, ultraviolet deterioration resistance, transparency, and electrical properties. However, because its surface is chemically inert, it has low affinity with adhesives, paints, inks, etc., and it also has poor thermocompression adhesion, so-called heat-sealing properties, which polyethylene film has, and therefore has the required adhesive performance. is missing. Therefore, despite having the various features mentioned above, it is currently not widely used.

Conventionally, various methods have been proposed to improve the adhesiveness of fluororesin molded products.

Currently, the most widely used methods are the metallic sodium-ammonia method and the sodium-naphthalene-tetrahydrofuran method.

However, these methods involve wet processing, and therefore there is a problem in that the processing liquid reacts rapidly with water during washing. Also, the life of the processing liquid is short,
Various problems remain in the work process, such as the complexity of replacing the processing liquid. Furthermore, this method has a problem in that the surface of the treated fluororesin molded product is colored, which is a quality defect.

As a method to improve the disadvantages of these wet treatments, Japanese Patent Publication No. 12900/1986 describes a method for producing ethylene tetrafluoride polymer films or ethylene tetrafluoride-hexafluoride films treated by discharge treatment in nitrogen gas or carbon dioxide gas containing acetone vapor. A method of laminating a propylene copolymer film and a polyimide film has been proposed, and US Pat. No. 3,296,011 proposes a method of performing discharge treatment in an atmosphere containing glycidyl methacrylate, methyl methacrylate, etc.

However, although these methods have advantages such as good workability because they are dry treatments, the adhesive performance of the treated fluororesin molded products is
It has the disadvantage of being economically degraded at or under high temperatures. Furthermore, these methods have the disadvantage that a part of the surface to be treated of the treated fluororesin molded article is treated sparsely. Most fluororesin molded products are composited by bonding the adhesive side with metal or plastic, and the other side is used as a fluororesin for applications that take advantage of its non-adhesive and non-adhesive properties. Therefore, it is a serious problem that the back side, which is a non-adhesive and non-adhesive side, is also treated. Although the cause of this phenomenon is not clear, it is a phenomenon that generally occurs frequently in corona discharge treatment, which is called "back-up".

[Problems to be Solved by the Invention] The present invention has been devised in view of the various drawbacks of the prior art, and its purpose is to provide a good and stable product with good workability, no deterioration over time, no backing, and a good and stable structure. An object of the present invention is to provide a method for producing a fluororesin molded article having heat sealability.

[Means for solving the problems] The object of the present invention is to
This is achieved by a method for producing a heat-sealable fluororesin molded product, which is characterized by carrying out a discharge treatment in an atmosphere containing alcohol vapor represented by the chemical formula C _o H _2o+1 OH (n is an integer from 1 to 6).

The fluororesins used in the present invention include polymers and copolymers of fluorine monomers such as tetrafluoroethylene, trifluorochloroethylene, hexafluoropropylene, perfluoroalkoxyethylene, vinyl fluoride, and vinylidene fluoride. , copolymers of these monomers and monomers other than fluorine-based monomers, and mixtures of these polymers and other polymers. Among these, particularly preferred are tetrafluoroethylene polymers, tetrafluoroethylene-hexafluoropropylene copolymers, and tetrafluoroethylene-perfluoroalkoxyethylene copolymers.

In the present invention, the term "molded product" refers to a film, sheet, fabric, etc. made of the above polymer.
Even if these molded products are laminated on other polymer molded products, such as films or fabrics made of polyester, polyamide, polysulfone, polyimide, etc., or on metal foils such as Al, Cu, etc. good. These can be made, for example, by applying a fluororesin dispersion onto the polymer molded product or metal foil and heat-treating it.

In the present invention, such a fluororesin molded product is subjected to electrical discharge treatment in an atmosphere containing alcohol vapor to surface-treat the surface of the molded product.

The alcohol vapor-containing atmosphere employed in the present invention is not particularly limited as long as the gas atmosphere contains alcohol vapor, but preferably, the alcohol vapor concentration in the gas atmosphere is 1% by volume or more. The atmosphere is preferably one in which the alcohol vapor concentration is 5% to 90% by volume.

The gas that dilutes alcohol is not particularly limited, but preferably He, Ne, Ar, _N2 ,
Non-polymerizable gases such as H ₂ , CO, CO ₂ , CF ₄ and H ₂ O are preferred, more preferably inert gases such as He, Ar and N ₂ , particularly preferably Ar or Ar and CO ₂
Alternatively, a mixed gas of Ar and N ₂ is preferable.

In the present invention, alcohol refers to C _o H _2o+1
It refers to a compound represented by OH (n is an integer of 1 to 6), and among them, ethyl alcohol (C ₂ H ₅ OH) where n = 2 has a remarkable reforming effect and is most preferred.

The discharge treatment as used in the present invention is performed by exposing the fluororesin molded product, which is the substrate to be treated, to a discharge initiated by applying a high voltage in an atmosphere containing alcohol vapor. It is processing.

The pressure of the alcohol vapor-containing atmosphere is not particularly limited, but corona discharge treatment tends to occur in the pressure range of 100 Torr to 1520 Torr, or 10 ^-3 Torr to
Glow discharge treatment occurring in the pressure range of 10 Torr, so-called low temperature plasma treatment, is preferred. Low-temperature plasma treatment is more preferable in terms of uniformity of treatment.

Corona discharge treatment is generally used to modify the surface of plastics, but when it is performed in an atmosphere containing alcohol vapor as in the present invention, the discharge is more stable than conventional corona discharge, especially for fluororesin molded products. Remarkable effects such as significantly improved adhesion and no sagging of the back surface are achieved.

Note that the device, electrode, etc. for the discharge treatment are not particularly limited, and known devices can be used.

Heat-sealability as used in the present invention refers to adhesiveness when bonded to a fluororesin or other base material by heat-pressing without an adhesive at a temperature below the melting point of the fluororesin.

The fluororesin molded product obtained by the present invention can be heat-sealed well between the fluororesin molded products or between the fluororesin molded product and other resin molded products, metals, glass, etc.

In addition, it does not impair the characteristics of fluorinated olefin polymers (chemical resistance, heat resistance, resistance to ultraviolet deterioration, etc.), and it is transparent and free from yellowing and peeling, which were unavoidable with conventional adhesive improvement technologies. Because of its excellent properties, it can be effectively used in various applications such as adhesive tapes, magnetron coverlay films, composite films, and glass-coated films. Furthermore, it has good affinity with paints and inks, so it can be printed or painted.

[Effects of the Invention] Since the present invention is configured as described above, it exhibits the following excellent effects.

Heat sealing between fluororesin molded products or other resin molded products, metals, glass, etc. can be performed efficiently and well.

A fluororesin molded product that has excellent heat sealability and adhesion without sacrificing the excellent features of fluorinated olefin polymers, and has excellent transparency without changing over time (yellowing) or peeling. can be obtained.

[Example] Hereinafter, the present invention will be specifically explained with reference to Examples.

In the following explanation, the physical properties were measured by the following method.

Attaching films together using heat sealing Using a heat sealer, heat plate temperature 240℃ and pressure
Adhesion was carried out under conditions of 1.5Kg/cm ² and heat sealing time of 30 seconds.

Measurement of Adhesive Strength The obtained sample was subjected to a T-peel test under the following conditions using a universal tensile tester (manufactured by Toyo Baldwin, Tensilon).

Tensile speed: 200mm/min Sample dimensions: Width 10mm, length 100mm, adhesion length 75mm Evaluation of aging characteristics A High temperature deterioration test The treated surfaces were attached together under the heat sealing conditions described above and placed in a hot air oven at 200℃ for 8 days. After that, it was returned to room temperature and a tensile test was performed.
Adhesive strength was measured.

B High humidity deterioration test Samples with treated surfaces heat-sealed
After being left in an atmosphere of 100% RH and 65℃ for 10 days,
A tensile test was conducted to measure the adhesive strength.

Example 1 A copolymer film of tetrafluoroethylene and hexafluoropropylene (“Toyoflon” 25F manufactured by Toray Industries, Inc.) with a thickness of 25 μm and a width of 15 mm was placed in an internal electrode type plasma processing device, and the initial pressure was
After exhausting to 0.03Torr, a mixed gas of 10% by volume of ethyl alcohol and 90% by volume of Ar was introduced, and the temperature was reduced to 0.4Torr.
Apply a high frequency voltage of 110KHz, keeping the pressure at
Processing was performed at a discharge power of 6 Watt and a processing speed of 1 m/min.

After bonding the treated films together under the heat-sealing conditions described above, the adhesive strength was measured, and it was found that the film itself was cut without peeling on the adhesive surface. That is, it had sufficient adhesive strength.

In addition, when we conducted the high temperature deterioration test mentioned above,
The product of the present invention had an adhesive strength of 430 g/cm or more, and almost no decrease in adhesive strength was observed. Furthermore, when we conducted the high-humidity deterioration test described above, the product of the present invention had an adhesive strength of 440 g/cm even after being left for 10 days, which was almost the same as the initial strength of 450 g/cm, indicating that it was stable under high humidity. Ta.

Comparative Example 1 The treated surfaces of "Toyoflon" 25F similar to those in Example 1 were overlapped and pressure bonded under the same conditions as in Example 1, but no adhesion occurred at all and the peel strength could not be measured.

Claims (1)

[Claims] 1 The fluororesin molded product has the chemical formula C _o H _2o+1 OH
(n is an integer of 1 to 6) A method for producing a fluororesin molded product for heat sealing, characterized in that a discharge treatment is performed in an atmosphere containing alcohol vapor represented by (n is an integer of 1 to 6).