JPH0873819A - Tetrafluoroethylene resin tacky adhesive tape and its production - Google Patents

Abstract

PURPOSE: To prepare the subject tacky adhesive tape having excellent heat- resistance, electrical insulation, tacky adhesivity, etc., by applying an adhesive to an essentially void-free tetrafluoroethylene resin film free from stripe defects on the surface. CONSTITUTION: This tacky adhesive tape is produced by applying a tacky adhesive to one or both surfaces of an essentially void-free tetrafluoroethylene resin film free from stripe defects on the surface. A fluororesin such as polytetrafluoroethylene or polyvinyl fluoride can be used as the material for the film. The tacky adhesive tape is produced by subjecting the film to a treatment selected from electrical discharge treatment, ultraviolet treatment and ozone treatment and applying the tacky adhesive to the treated surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a film-like article made of a tetrafluoroethylene-based resin which is substantially free of voids and has no streaky damage on the surface, and an adhesive is applied to one or both sides of the film-like article. The present invention relates to a fluorinated ethylene resin adhesive tape.

[0002]

2. Description of the Related Art Conventionally, heat resistance, chemical resistance, electrical insulation,
As a tetrafluoroethylene-based resin adhesive tape coated with an adhesive having excellent friction characteristics and weather resistance, a tape based on a tetrafluoroethylene-based film obtained by the skive method has been used. For example, in Japanese Examined Patent Publication No. 34-10177, a tetrafluoroethylene-based resin powder is put into a cylindrical shape to be processed into a round bar (rod), and the obtained round bar (precursor) is cut to form a film. A film-like material of a tetrafluoroethylene resin to be used as the material is shown. Since the precursor in the skive method is unavoidably mixed with air or an inert gas in the manufacturing method, and is accompanied by the formation of countless cavities or fine voids inside the precursor, a film-like material obtained by cutting the precursor is It will contain fine voids.

[0003]

DISCLOSURE OF THE INVENTION As described above, a rod obtained by filling a powder of tetrafluoroethylene resin into a cylindrical mold, compressing it with a press to form a preform, and then heating and sintering. In the production of, since a tetrafluoroethylene-based resin filled in the mold is mixed with air or an inert gas such as nitrogen, many hollow portions are formed in the rod after heating and sintering, so that it is uniform. The reality is that you can't get a good rod.

Further, in the production of a film-like material by cutting a rod, it is inevitable that the surface of the film-like material is scratched by a cutting blade.

In the production of a film or tape, it is general that the film or tape is subjected to a stretching treatment or a heat treatment to improve the mechanical properties. However, in the above-mentioned rod having poor uniformity, the drawability is not sufficient, and it is actually acceptable to obtain a film or tape having low mechanical properties.

The object of the present invention is to retain the characteristics of the conventional tetrafluoroethylene film-like material coated with an adhesive, and to eliminate the defect of the cavity portion, that is, the so-called void structure. Improve the physical properties based on
An object of the present invention is to provide a tetrafluoroethylene-based resin pressure-sensitive adhesive tape coated with a pressure-sensitive adhesive that is highly uniform and has sufficient physical properties.

[0007]

In order to achieve the above-mentioned object of the present invention, the tetrafluoroethylene resin adhesive tape of the present invention has the following constitution. That is, in a tetrafluoroethylene-based resin pressure-sensitive adhesive tape obtained by applying an adhesive to one or both surfaces of a film-shaped material made of a tetrafluoroethylene-based resin, the film-shaped material made of the tetrafluoroethylene-based resin is substantially A tetrafluoroethylene-based resin pressure-sensitive adhesive tape, characterized in that it is a film-like material containing no voids and no streaky damage on the surface.

In order to achieve the above-mentioned object of the present invention, a method for producing a tetrafluoroethylene-based resin adhesive tape of the present invention comprises:
It has the following configuration. That is, a film-like material made of a tetrafluoroethylene-based resin is subjected to at least one treatment selected from the group consisting of an electric discharge treatment method, an ultraviolet treatment method and an ozone treatment method, and then an adhesive is applied. Is a method for producing an adhesive tape of tetrafluoroethylene resin.

The film-like material made of tetrafluoroethylene-based resin used in the present invention includes polytetrafluoroethylene, polychlorotrifluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl. A vinyl ether copolymer, a tetrafluoroethylene-ethylene copolymer, a fluororesin such as polyvinyl fluoride, a vinylidene fluoride-hexafluoropropylene-based fluororubber, or the like can be used. These can be obtained by a known method, for example, a molding method of a resin such as polytetrafluoroethylene which is not suitable for the melt molding method because the viscosity of the heated melt is extremely high and there is no suitable solvent for wet spinning. . That is, it can be obtained by a so-called matrix spinning method in which a mixed solution of viscose, polyvinyl alcohol, sodium alginate and the like as a matrix polymer and a water dispersion emulsion of the resin is wet-spun or wet-molded.

The method for producing a film-like product made of a tetrafluoroethylene-based resin of the present invention is to discharge an emulsion of a tetrafluoroethylene-based resin having viscose or the like as a matrix into a coagulation bath liquid through a molding die. Then, washing, scouring, baking and heat treatment, and stretching are carried out. Here, when any of viscose, polyvinyl alcohol and sodium alginate is used as the matrix, the coagulation bath is preferably an aqueous solution of an inorganic mineral acid and / or an inorganic salt.

The general conditions of the wet molding method applicable to the present invention will be described in detail below.

As the molding emulsion, a mixture of a matrix such as viscose and a water dispersion of a tetrafluoroethylene resin is used. When viscose is used as the matrix, the composition is generally in the range of 3 to 10% in cellulose concentration, 2 to 12% in alkali concentration, and 27 to 32% in carbon disulfide (relative to cellulose), but it is usually used for producing rayon. Existing, ie, cellulose concentration 6-8
%, Alkali concentration 6-9%, carbon disulfide 28-30%
Viscose having a composition (relative to cellulose) is preferably used.

The tetrafluoroethylene-based resin contains 20 to 75% as a water dispersion and a nonionic or anionic activator as a stabilizer in an amount of 3 to 10% based on the amount of the tetrafluoroethylene-based resin. Things are conveniently used. The molecular weight of tetrafluoroethylene-based resin is 2 to 9
About one million is used. The particle size of the tetrafluoroethylene-based resin is preferably 0.005 to 1 micron, more preferably 0.2 to 0.6 micron.

The composition of the water dispersion mixture of the matrix such as viscose and the tetrafluoroethylene-based resin is such that the tetrafluoroethylene-based resin in the mixed polymer is 60 to 96%. The preferable concentration of the tetrafluoroethylene-based resin is 70 to 95%. The viscosity of the mixed solution varies depending on the mixing ratio of the viscose and the tetrafluoroethylene resin, the aging degree of the viscose used and the cellulose concentration, but from the viewpoint of stable discharge molding, it is 50 to 200 poise at 30 ° C. Is preferred.

Next, an example of a method for producing a film-like material made of a tetrafluoroethylene resin when viscose is used as a matrix will be described.

A so-called wet molding method is used in which the molding emulsion is a mixed solution of viscose and an ethylene tetrafluoride-based resin, which is discharged into a coagulating liquid through a molding die. A molding die having a rectangular ejection hole shape is used, and the length of the short side of the rectangle is preferably 0.03 mm or more. Furthermore, the length of the short side of the rectangle is more preferably 0.05 mm or more. The short side length is 0.03 mm
If the length is shorter, clogging of the die is likely to occur during discharge molding of the molding emulsion, and stable discharge cannot be obtained. Also,
The molding emulsion discharged from the die generally contracts during solidification, and the ratio of the long side to the short side in the rectangle of the die is preferably at least 5 or more.

An aqueous solution of an inorganic mineral acid and / or an inorganic salt is preferably used as the viscose coagulation bath, and it is sometimes discharged into a saturated salt aqueous solution and then regenerated in the inorganic acid.
Combinations such as bath forming methods are also effective. Generally, a mixed aqueous solution of sulfuric acid / sodium sulfate is used.

The cellulose / tetrafluoroethylene-based resin mixed film-like material which has been washed with water after discharge is then refined. As the refining bath, an aqueous solution of an alkali metal hydroxide is preferable, and sometimes an organic compound which dissolves in water and exhibits alkalinity, such as sodium parabenzenesulfonate is also effective. Generally, a caustic soda solution is used. The scoured cellulose / tetrafluoroethylene-based resin mixed film material is subsequently heat-treated at a temperature of 330 to 420 ° C. as it is or in a dried state. At this stage, the cellulose is burned and scattered, and the tetrafluoroethylene-based resin particles in the cellulose are heat-sealed in a film form to obtain a precursor of a film-shaped product made of the tetrafluoroethylene-based resin. The heat-treated precursor is usually heat-stretched at 300 to 400 [deg.] C. to enhance the crystallinity and becomes a film made of tetrafluoroethylene resin.

Next, an example of a film-like material made of the tetrafluoroethylene-based resin of the present invention will be described with reference to the drawings.

FIG. 1 is a scanning electron microscope photograph (hereinafter referred to as SEM photograph) showing the surface morphology of the film-like material made of the tetrafluoroethylene-based resin of the present invention, and the photographing magnification is 10,000 times. The lumps in the figure are the outermost tetrafluoroethylene resin particles of the film, and it can be seen that the tetrafluoroethylene resin particles are evenly present. FIG. 2 shows the surface morphology of a tetrafluoroethylene-based resin film based on the conventional skive method taken in the same manner as in FIG.
It is an EM photograph, and in FIG. 2, the presence of a clear hollow portion is seen.

FIG. 3 is an SEM photograph showing the surface morphology of a film-like material made of the tetrafluoroethylene-based resin of the present invention, where the longitudinal direction of the tetrafluoroethylene-based film-like material is SE.
The horizontal direction of the M photograph. The photographing magnification is 149 times. Further, FIG. 4 is a SEM photograph showing the surface morphology of a tetrafluoroethylene-based film based on the conventional skive method, in which the longitudinal direction of the film-shaped product made of the tetrafluoroethylene-based resin is S.
It is the lateral direction of the EM photograph. The photographing magnification is 148 times.
In FIG. 4, many clear horizontal stripes are seen, whereas in FIG.
From the above, it is understood that the film-like material made of the tetrafluoroethylene resin used in the present invention has a much more uniform surface morphology.

Next, the surface treatment method for applying the adhesive will be described.

The tetrafluoroethylene-based resin has a unique non-adhesive property. For example, in the case of tetrafluoroethylene resin, the molecular structure consists of a carbon atom chain as the skeleton and fluorine atoms surrounding it, and the surface free energy of the resin is extremely low. Have sex.

As a method for imparting adhesiveness to a substance having a very low surface free energy, it is sufficient to introduce a polar group into the molecule to enhance the reactivity of the surface, and various surface treatment methods have been conventionally proposed. Has been done. As the surface treatment for increasing the surface reactivity without deteriorating the various properties of the film-like material made of the tetrafluoroethylene-based resin as the base material, one or more selected from the group consisting of discharge treatment, ultraviolet treatment and ozone treatment. The process is known.

The above-mentioned surface treatment method is a method for introducing a polar group into a film-like material made of the tetrafluoroethylene resin of the present invention so as to apply a pressure-sensitive adhesive to the film-like material to enhance the surface reactivity. Can be adopted.

Of these surface treatment methods, the discharge treatment method will be described as an example.

The discharge treatment in the present invention is generated by applying a high voltage between the electrodes, and such discharge treatment involves low temperature plasma which generates corona discharge generated in atmospheric pressure in a vacuum container. is there. As a power supply for applying a high voltage, either direct current or alternating current may be used. The discharge treatment is preferably performed by coating at least one electrode with a dielectric, and the shape of the electrode may be a plate shape, a roll shape, or the like and is not particularly limited. The distance between the electrodes is 0.2 to 40 mm, preferably 0.5 in the case of corona discharge.
~ 3 mm, 0.2-100 m for low temperature plasma
m, preferably 10 to 50 mm.

The discharge treatment in the present invention is carried out by using air, oxygen,
It is preferable to carry out in a non-polymerizable gas atmosphere such as nitrogen, carbon monoxide, water, argon, helium, etc., but a polymerizable gas such as methane, perfluoroethylene, silane, etc. should be mixed within a range that does not impair the effects of the present invention. Can be used.

The atmospheric pressure of the discharge treatment in the present invention is
In the case of corona discharge, the atmospheric pressure is lower than atmospheric pressure, and the low-temperature plasma is a specific gas introduced, 0.001 to 50 Torr, preferably 0.01 to 10 Torr, more preferably 0.1 to 5 Torr.
It is under reduced pressure of Torr.

The treatment time of the discharge treatment in the present invention is preferably several seconds to several minutes, and can be set according to the purpose.

Next, the application of the pressure-sensitive adhesive of the present invention will be described.

After subjecting the film made of the tetrafluoroethylene-based resin of the present invention to discharge treatment, ultraviolet treatment or ozone treatment, or after performing any two or more treatments of discharge treatment, ultraviolet treatment and ozone treatment The adhesive is applied and processed.

The pressure-sensitive adhesive that can be used in the present invention is a pressure-sensitive adhesive whose main component is a polymer compound such as acrylic type, modified acrylic type, synthetic rubber type, recycled rubber type, polyamide type, polyimide type, polyurethane type. . The above-mentioned pressure-sensitive adhesives can be used alone or in combination of two or more depending on the purpose of use. Further, it is possible to make use of the excellent properties of the film-like material made of the tetrafluoroethylene resin, which is a feature of the present invention, that is, heat resistance, chemical resistance, electrical insulation, dielectric properties, frictional properties, weather resistance, and the like. If possible, the adhesive is not limited to the above.

[0034]

EXAMPLES The present invention will be described in more detail below with reference to examples.
In addition, each characteristic value in this Example is measured as follows. The concentration in this example is% by weight unless otherwise specified.

[Aspect Ratio] In a rectangular or elliptical cross section, the ratio of the long side to the short side, expressed as the ratio of the width to the thickness of the film-like material.

[Tensile Strength and Tensile Elongation of Film-like Material] It was measured according to JIS K 6891.

[Physical Adhesion Improvement Treatment] (A: Corona Discharge Treatment) Electrode: 1 roll of metal rod coated with silicone rubber
Installed at mm distance Discharge frequency: 35 KHz Discharge power: 1200 w Treatment speed, number of treatment: 5 m / min, 1 to 5 times Discharge atmosphere gas: Air (B: Low temperature plasma) Electrode: Parallel plate type Discharge frequency: 600 KHz Discharge power: 250 w Treatment time: 5 to 30 sec Discharge atmosphere gas, flow rate: argon, 100 cc / min (C: ozone treatment) Ozone generator: corona discharge method Raw material gas: oxygen Ozone concentration: 8000 ppm Treatment temperature: 150 ° C. Treatment time: 0.5 to 5 min (D: UV treatment) Irradiation device: Low-pressure mercury lamp 253.7 nm Illuminance: 38 mW / cm ² Atmosphere temperature: 140 ° C Atmosphere gas: Air Treatment time: 10-120 sec [Surface resin processing] Crisbon NY361 (Dainippon Ink and Industries Co., Ltd.) Co., Ltd., polycarbonate-based polyurethane resin) 100 parts and N, N 'dimethy The resin consisting of formamide 50 parts by applying an amount of 180 g / m ² by a knife coater, dried at 80 ° C., and heat treated at 120 ° C..

[Peeling strength] JIS K6328-197
According to Method 7, measurement was performed using strip-shaped test pieces having a width of 2.5 cm. (Example 1) Viscose maturity (salt point) of 5.0, cellulose concentration of 9.0%, alkali concentration of 5.9%, 49% by weight of viscose and 60% of concentration of tetrafluoroethylene resin water dispersion 51. %, And then defoamed under a reduced pressure of 10 Torr to obtain a stock solution for molding having a polymer concentration of 35.0%.
The PTFE resin content in the undiluted solution was 87.4%,
The stock solution viscosity, measured at ° C, was 125 poise. Use one gear pump with a discharge rate of 5.0 cc per revolution of this stock solution.
After passing through at a speed of 17 revolutions per minute, it was introduced into a molding die having a slit-shaped discharge hole having a short side length of 0.1 mm and a long side length of 17.0 mm, and discharged into a coagulation bath solution. The coagulation liquid was a mixed aqueous solution having a sulfuric acid concentration of 10% and a sodium sulfate concentration of 21.0%, and the temperature was 10 ° C. The solidified product had a tape shape having a width of 12 mm. The tape in the coagulation bath solution was taken out at a speed of 20 m / min, washed with warm water at a temperature of 70 ° C. to remove most of sulfuric acid and sodium sulfate, and then introduced into a 0.2% concentration caustic soda aqueous solution for scouring. A tape from which the acid component was completely removed was obtained.

The tape after scouring was introduced into a nip roller to obtain a tape having a water content of 70%. Then, heat treatment was carried out on a roller heated to 380 ° C. to obtain a film-form precursor.
This precursor was stretched using a stretching machine having a heated hot tube at a temperature of 340 ° C. to obtain a film-like material having a stretching ratio of 8 times.

The thickness of the obtained film-like material was measured with a Digimatic Micrometer (manufactured by Mitoyo Co., Ltd.) and the width was measured with a caliper (manufactured by Mitoyo Co., Ltd.). there were.

The aspect ratio calculated by these values was 56.8. The tensile strength and tensile elongation are 26.9 kg / mm ² and 10.9, respectively.
%Met. (Examples 2 to 13 and Comparative Example 1) The results obtained by carrying out and evaluating the physical adhesion-improving surface treatment and surface resin processing of the film-like material made of the tetrafluoroethylene-based resin obtained in Example 1 under the following conditions: Are summarized in Table 1.

As a comparative example, surface resin processing was carried out without physical surface treatment.

[0043]

[Table 1] It can be seen from Table 1 that the resin according to the present invention has excellent resin adhesion.

[0044]

EFFECTS OF THE INVENTION According to the present invention, the tetrafluoroethylene resin has various excellent properties, that is, heat resistance, chemical resistance, electrical insulation, dielectric properties, frictional properties, weather resistance, etc. In addition, it is possible to provide an adhesive tape having excellent adhesiveness.

[Brief description of drawings]

FIG. 1 is an SEM photograph showing the surface morphology of a film-like material made of the tetrafluoroethylene-based resin of the present invention.

FIG. 2 is an SEM photograph showing a surface morphology of a tetrafluoroethylene-based resin film based on a conventional skive method.

FIG. 3 is an SEM photograph showing the surface morphology of a film-like material made of the tetrafluoroethylene-based resin of the present invention.

FIG. 4 is an SEM photograph showing the surface morphology of a tetrafluoroethylene-based resin film based on the conventional skive method.

Claims (2)

[Claims] 1. A tetrafluoroethylene-based resin pressure-sensitive adhesive tape comprising a tetrafluoroethylene-based resin film-shaped product coated with an adhesive on one or both sides thereof, wherein the tetrafluoroethylene-based resin-based film-shaped product is used. Is an ethylene tetrafluoride-based resin pressure-sensitive adhesive tape, which is a film-like substance substantially free of voids and having no streaky damage on the surface. 2. A film-like material comprising a tetrafluoroethylene-based resin is subjected to at least one treatment selected from the group consisting of an electric discharge treatment method, an ultraviolet treatment method and an ozone treatment method, and then coated with an adhesive. A method for producing a tetrafluoroethylene-based resin adhesive tape, comprising: