JP2667890B2 - Method for treating aromatic polyamide film - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to improving the adhesiveness of an aromatic polyamide film, and more specifically, to the performance of an aromatic polyamide film having high strength and high Young's modulus. The present invention relates to a means for improving adhesion without damaging it.

(Prior Art) An aromatic polyamide film is known to have excellent heat resistance, high strength and Young's modulus, and in particular, a para-oriented aromatic polyamide film in which a monomer of a structural unit mainly has linear orientation. Are particularly good at these properties,
Application to various uses is expected. Among them, regarding the application to a composite molded body by laminating a rubber and a film, conventionally, the adhesive force between the aromatic polyamide film and the rubber is very weak, and it is difficult to obtain the effect of improving the physical properties by the composite. there were.

On the other hand, aromatic polyamide fibers have been conventionally used as a rubber reinforcing material for tire cords and the like, and an adhesive composition comprising a resorcinol-formaldehyde initial condensate and a rubber latex for bonding the aromatic polyamide fibers to rubber. It is known that the adhesion is improved by treating with a rubber adhesive such as (RFL liquid). However, even if the aromatic polyamide film is treated with a rubber-based adhesive, the adhesive strength is hardly improved, and it is difficult to bond the film and rubber by this method to obtain an effective laminating effect. Was.

(Problem to be Solved by the Invention) An object of the present invention is to improve the adhesive strength of an aromatic polyamide and rubber having excellent mechanical performance and heat resistance when they are compounded.

(Means for Solving the Problems) As a result of intensive studies to achieve the above object, the present inventors have found that after subjecting an aromatic polyamide film to corona discharge treatment, treatment with a specific adhesive composition is performed. The inventors have found that the adhesive strength is extremely increased, and have completed the present invention.

That is, the present invention is a method for treating an aromatic polyamide film, which comprises treating the surface of an aromatic polyamide film with a corona discharge, and then treating the film with a rubber-based adhesive composition.

In the present invention, the aromatic polyamide film is produced using a polymer represented by the following general formula (I) or (II) or a copolymer thereof.

(Wherein R ₁ , R ₂ and R ₃ And these hydrogen atoms may be substituted with a functional group such as halogen, methyl, ethyl, methoxy, nitro, and sulfone. m and n are average degrees of polymerization and are about 50 to 10
00. ) The aromatic polyamide used in the present invention may be copolymerized or blended with a polymer other than the above components in an amount of about 20 mol% or less.

In the present invention, R ₁ , R ₂ , and R ₃ are preferably para-oriented. Here, the para-oriented type means that the bond growing the molecular chain is located coaxially or parallel to the opposite direction of the aromatic ring.

Particularly preferred as aromatic polyamides are poly (P
-Phenylene terephthalamide).

When a film is produced from these polymers, dimethylacetamide, dimethylformamide, N-methylpyrrolidone, hexamethylphosphoramide, γ-butyrolactone, tetramethylurea, dioxane, or the like, or a mixed solvent thereof, or chloride Lithium, calcium chloride, lithium carbonate, a solvent to which an inorganic salt such as lithium nitrate is added can be used, but preferably, the polymer is produced from a dope dissolved in sulfuric acid, chlorosulfuric acid, fluorosulfuric acid, or the like. .

In order to use the film as a reinforcing material for rubber, the strength should be 20 kg / mm ² or more in all directions inside the film, and
30 kg / mm ² or more is preferable.

As a method for producing a film having such physical properties, an optically anisotropic dope using sulfuric acid or the like of poly (P-phenylene terephthalamide) as a solvent is cast on a support surface,
A method is preferably used in which the dope is converted to optically isotropic by moisture absorption and / or heating, coagulated, washed, stretched uniaxially or biaxially if necessary, and then dried while controlling shrinkage.

The film may be doped or impregnated with additives such as an ultraviolet stabilizer, a heat stabilizer, an antioxidant, a lubricant, a flame retardant, and a delusterant within a range that does not impair the effects of the present invention. Can be granted.

The thickness of the film is usually 2μ to 100μ, preferably 8 μm.
μ to 25 μ is used.

In the present invention, the aromatic polyamide film is subjected to a pretreatment such as heat treatment as necessary, and then one or both surfaces thereof are subjected to a corona discharge treatment.

In corona discharge treatment, high frequency and high voltage are applied between the electrode and the roll to generate corona discharge, and the film surface is treated by passing the film through the corona discharge. Hypalon rubber,
A dielectric roll coated with a dielectric such as EPT or silicon rubber is used. In some cases, however, discharge treatment can be performed directly between the electrodes without using a dielectric.

 The discharge frequency is usually about 10 KHz.

The processing power is adjusted depending on the state of the film, the required adhesive force, etc., and is usually 1 to 200 W / m ² / min, preferably 5 to 50 W
A range of / m ² / min is used. If the processing power is too high, the physical properties of the film may be deteriorated and the surface may be drastically changed, so that the performance may be deteriorated.

The corona discharge treatment can be carried out continuously, for example, by using the apparatus shown in FIG. 1 while running the film at a predetermined speed. The processing speed is usually 1 to 50 m / min. As the processing device, any device such as a spark gap system, a vacuum tube system, and a solid state system can be used.

In the present invention, the above corona-discharge-treated film is treated with a rubber adhesive.

 Here, the rubber adhesive is an emulsion of a rubber component,
With rubber and other materials contained in latex or dissolved state
And a resorcinol-formalde
Rubber-based adhesive group consisting of a hydrocondensate and a rubber latex
Compound (so-called RFL liquid) or chlorinated butadiene polymer
, A rubber-based adhesive composition containing an isocyanate compound
Things (eg Chem Rock 402) and the like are preferably used
You. RFL liquid is the most preferable rubber adhesive composition.
It is.

RFL solution is sodium hydroxide, ammonium hydroxide,
A mixture of a relatively high molecular weight initial condensate and rubber latex obtained by reacting resorcinol and formaldehyde in the presence of a basic catalyst such as potassium hydroxide, in which case the reaction between resorcinol and formaldehyde The molar ratio of formaldehyde to 1 mole of resorcinol
0.8-7.5 mol is preferred.

On the other hand, as rubber latex, natural rubber latex,
Styrene-butadiene copolymer rubber latex, acrylonitrile-styrene-butadiene copolymer rubber latex, chloroprene rubber latex, vinylpyridine-styrene-butadiene copolymer rubber latex, and these carboxyl group-modified rubber latexes alone or in combination of two or more These are used arbitrarily changed depending on the type of rubber to be adhered. In this case, as for the mixing ratio with the polymer resorcinol-formaldehyde precondensate, it is preferable that the condensate is 5 to 30% by weight based on the total solid content and that of the rubber latex is 95 to 70% by weight.

As a method of contacting the rubber-based adhesive composition with the film, a method of running the film in a tank containing the rubber-based adhesive composition, or applying the rubber-based adhesive composition to the surface of the running film Methods, eg, reverse coat (3 bottom feed reverse, 4 bottom feed reverse, 2 roll reverse or 3 top feed reverse), kissmeer coat, gravure coat (direct gravure or offset gravure), slot die coat or curtain coat And so on. The adhesion amount of rubber adhesive is usually 0.1 to 10 g
A range of / m ² is used.

After applying the rubber-based adhesive composition to the film in this way, it is dried and optionally heat-treated. For example,
If using an RFL solution, dry at about 150 ° C and then
Heat treatment is performed to the extent.

The aromatic polyamide film treated by the method of the present invention can be bonded to unvulcanized rubber, and can be heated and pressed to vulcanize the rubber composition to obtain a film-rubber composite having excellent adhesive performance. When used as an automobile airbag such as a conveyor belt and a timing belt, excellent performance can be exhibited.

(Examples) Hereinafter, the present invention will be described with reference to examples. In the examples, parts and% are parts by weight unless otherwise specified.
Is shown.

(Reference example)

Production of Polyamide Film A PPTA polymer having an inherent viscosity ηinh of 5.5 was dissolved in 99.7% sulfuric acid to a polymer concentration of 11.5% to obtain a dope having optical anisotropy at 60 ° C. The viscosity of this dope measured at room temperature was 10600 poise. In order to facilitate film formation, the dope was degassed under vacuum while maintaining the temperature at about 70 ° C. Also in this case, it had optical anisotropy and had a viscosity of 4400 poise. A 1.5m curved pipe that goes through the filter from the tank to the die via the gear pump is kept at about 70 ° C, and 0.1mm x 3
Cast from a die with a slit of 00 mm to a tantalum belt polished to a mirror surface (moving at 2 m / min), and blow air at about 90 ° C with a relative humidity of about 85% to make the casting dope optically isotropic. Then, it was introduced into diluted sulfuric acid at −5 ° C. and solidified together with the belt. Next, the coagulated film was peeled off from the belt and washed by running in warm water at about 40 ° C. After the washed film is stretched without drying, using a tenter, and then dried at 240 ° C. under a constant length using another tenter, the film is dried.
A constant-length heat treatment was performed at 90 ° C.

The film thus obtained has a thickness of 15μ and strength (kg / m
m ² ) is 40/38 (MD / TD), elongation (%) is 26/27 (MD / TD),
The Young's modulus (kg / mm ² ) was 1250/1180 (MD / TD).

Example A film having a speed of 10 was obtained by using the above film and the apparatus shown in FIG.
After performing corona discharge treatment at m / min, frequency 10KHz, electrode width 5mm, gap width 3mm, apply two kinds of RFL liquids shown in Table 1 with a reverse coater, then dry at 150 ° C for 2 minutes, 200
A heat treatment was performed at 1 ° C. for 1 minute to obtain a treated film.

Laminate this film with unvulcanized rubber about 2 mm thick, 150
The results of the T-peel test conducted after vulcanization at 30 ° C. for 30 minutes are shown in Table 2.

(Effect of the Invention) By the treatment of the present invention, the adhesive force between the aromatic polyamide film and the rubber can be significantly increased, and a film-rubber composite material is obtained in which the mechanical properties and heat resistance of the aromatic polyamide film are utilized. be able to. Therefore, the film-rubber composite material obtained by the processing method of the present invention is extremely useful for applications such as timing belts, conveyor belts and automobile airbags.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a corona discharge treatment device used in the method of the present invention. 1 ... electrode 2 ... dielectric roll 3 ... high frequency power supply
4,5 ... guide roll, 6 ... film

Claims (1)

(57) [Claims] 1. A method for treating an aromatic polyamide film, comprising subjecting the surface of the aromatic polyamide film to a corona discharge treatment, and then treating the film with a rubber-based adhesive composition.