JPH0346587B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a method for treating polyester fibers, and its purpose is to provide a method for treating polyester fibers that dramatically improves the heat-resistant adhesion between the fibers and rubber. be. In particular, the present invention improves the rate of rubber adhesion to polyester fibers (Rubbor coverage) when peeling polyester fibers from a composite molded product with rubber,
The present invention also relates to a treatment method for making polyester fibers flexible and having excellent fatigue resistance. <Prior art> Polyester fibers, typified by polyethylene terephthalate fibers, have physical properties such as high strength and Young's modulus, low elongation and creep, and excellent fatigue resistance. It is widely used for applications such as industrial composites. However, polyester fibers have poor adhesion to rubber materials compared to polyamide fibers such as nylon 6 and nylon 6/6, and ordinary adhesive treatment is insufficient to fully demonstrate the physical properties of the polyester fibers. Strong adhesion performance cannot be obtained. The main reason for this is thought to be that the hydrogen bonding capacity of ester bonds in polyester is smaller than that of amide bonds in nylon. For this reason, a method has been proposed in which the surface of polyester fibers is treated with highly reactive substances such as epoxy compounds and isocyanate compounds to impart adhesive properties. However, when trying to improve the adhesion of polyester fibers to rubber, the treated fiber material becomes hard, making molding difficult and reducing fatigue resistance. In addition, attempts have been made to improve the adhesion to rubber by activating the surface of polyester fibers by subjecting them to low-temperature plasma treatment under reduced pressure, and then treating them with a mixture of a resorcin-formalin initial condensate and rubber latex. JOURNAL OF APPLITED POLYMER
SCIENCE VOL.18 PP.1557−1574 (1974)). Alternatively, ``a method for treating polyester synthetic fibers for rubber reinforcement, which comprises subjecting the polyester synthetic fibers to low-temperature plasma treatment and then treating them with a mixture of a resorcinol-formaldehyde initial condensate and rubber latex'' is disclosed ( Unexamined Japanese Patent Publication 1986
−19880 Publication). However, although the initial adhesion is almost satisfied with these methods, there is a problem in that the heat-resistant adhesion does not reach a practical level, so that the fibers cannot be used as rubber reinforcing fibers. <Object of the invention> The present invention has been made against the background of the above-mentioned circumstances, and the purpose of the present invention is to provide excellent performance in adhesion between polyester fiber and rubber, particularly in heat-resistant adhesion. It is in. <Structure of the Invention> That is, the present invention is characterized in that polyester fibers are subjected to low-temperature plasma treatment under reduced pressure, followed by ion plating treatment with polyamide vapor under reduced pressure, and then treatment with resorcinol-formalin-rubber latex (RFL). This is a method for treating polyester fibers. The low-temperature plasma treatment in the present invention involves treating the polyester fibers in an ionized atmosphere using gases such as oxygen, nitrogen, ammonia, carbon monoxide, nitrogen monoxide, argon, helium, etc. alone or in a mixture of two or more gases. This treatment increases the reactivity of the fiber surface. The purpose of low-temperature plasma treatment on polyester fibers prior to ion plating treatment is to reduce the Week boundary layer (WBL) on the surface of polyester fibers.
layer), surface cleaning, generation of functional groups, and formation of irregularities. This makes it possible to improve the adhesion between the polyester fiber and the film formed in the ion plating treatment that is performed subsequent to the low temperature plasma treatment. A so-called plasma processing device is used to form a low-temperature plasma state. Plasma processing apparatuses include external electrode type, internal electrode type, capacitive coupling type, inductive coupling type, etc., and any method may be used. The operating treatment conditions vary depending on the treatment time, but high frequency glow discharge of 10 ^-5 Torr to 10 Torr is suitable, for example. If the gas pressure in the treatment tank exceeds 10 Torr, the temperature rise during glow discharge will be significant, and the surface of the polyester fibers may be altered, which is not preferable. On the other hand, below 10 ^-5 Torr, glow discharge is unstable and it is difficult to perform normal processing. Note that as the discharge frequency band, in addition to high frequencies, low frequencies and microwaves can be used. In the present invention, polyamides include polyamides synthesized by polycondensation of dicarboxylic acids and diamines, polycondensation of ω-aminocarboxylic acids, or ring-opening polymerization of lactams thereof, or copolymers of two or more of these. It is a blend. Suitable polyamides include poly-ε-capramide (nylon 6), polyhexamethylene adipamide (nylon 6,6), 3-polyhexamethylene sebaamide (nylon 6,10), and other aliphatic Polyamide, aromatic, polyamide containing an alicyclic ring or heterocyclic ring in the main chain, etc. may also be used. The degree of polymerization of polyamide is not limited at all, but for example, poly-ε
- In the case of capramide, those having a limit year [η] of 0.8 to 1.5 as measured in a metacresol solution at 35° C. can be used. Further, the shape of the polyamide may be bulk, film, thread, powder, etc., and is not particularly limited. The ion plating treatment in the present invention utilizes a so-called ion plating apparatus to melt the nylon mentioned above under reduced pressure to convert the vapor generated into a plasma state, or to generate a plasma state by generating this vapor with another gas. The vapor activated by exposure to the polyester fiber is cooled and solidified on the surface of the polyester fiber. There are two ways to melt nylon: a resistance heating method in which nylon resin is placed in a metal port, a ceramic crucible, etc., and the heat generated by passing an electric current through the crucible melts the nylon resin; There is an EB heating method that melts the material by irradiating it, but any method is fine. In order to turn the vapor generated by melting nylon under reduced pressure into a plasma state, the degree of vacuum in the reaction vessel is adjusted to 10 ^-5 Torr to 10 Torr using the generated vapor. In this case, a gas such as Ar, O ₂ , NH ₃ or the like may be used in addition to the generated steam, but in that case, the degree of vacuum in the reaction vessel is adjusted so that the final level is 10 ⁻⁵ Torr to 10 Torr. Electrical energy such as high frequency, low frequency, microwave, etc. can be used as energy for creating a plasma state. It is thought that the energy of the vapor particles increases when the vapor generated by melting nylon under reduced pressure becomes a plasma state or is exposed to a plasma state, but polyester is used to control this energy. There is no problem in applying a bias voltage between the fiber and an electrode such as a high frequency one. In the present invention, polyester fibers are subjected to plasma treatment and ion plating treatment, and then further treated with a composition containing resorcinol, formalin, and rubber latex. The resorcinol/formaldehyde rubber latex used here is usually called RFL, and the molar ratio of resorcinol and formaldehyde is 1:0.1 to 1:8, preferably 1:0.5 to 1:5.
More preferably, it is used in a range of 1:1 to 1:4. Examples of rubber latex include natural rubber latex, styrene-butadiene copolymer latex, vinylpyridine-styrene-butadiene terpolymer latex, nitrile rubber latex, chloroprene rubber latex, etc.
Use these alone or in combination. Among these, vinylpyridine-styrene-butadiene terpolymer latex shows excellent performance when used alone or in an amount of 1/2 or more. The blending ratio of resorcinol/formalin and rubber latex is preferably in the range of 1:1 to 1:15, preferably 1:3 to 1:12 in terms of solid weight ratio. If the proportion of rubber latex is too small, the treated polyester fiber material will become hard and have poor fatigue resistance. On the other hand, if the amount is too large, satisfactory adhesive strength and rubber adhesion rate cannot be obtained. In order to adhere this treatment agent to the polyester fiber material, any method such as contact with a roller, application by spraying from a nozzle, or immersion in a bath liquid can be adopted. The amount of solid content deposited on the polyester fiber is preferably 0.1 to 10% by weight, preferably 0.5 to 7% by weight. In order to control the amount of solid content attached to the fibers,
Means such as squeezing with a pressure roller, scraping off with a scraper, blowing off with air, suction, and beating with a beater may be used. In the present invention, polyester fibers are treated with low-temperature plasma, followed by ion plating treatment, and further treated with an RFL treatment agent, and then heated to a temperature of 120°C or higher and lower than the melting point of the polyester fiber, preferably
Dry and heat treat at a temperature of 180-250℃. If the drying/heat treatment temperature is too low, the adhesion of the rubber will be insufficient, while if the temperature is too high, the polyester fibers will melt, fuse, or significantly decrease in strength, making it impossible to put it to practical use. <Effects of the Invention> Compared to conventional methods, fibers treated by the method of the present invention have improved heat-resistant adhesion and improved peel strength and durability without impairing moldability with rubber. <Example> Hereinafter, the present invention will be specifically described with reference to Examples. In the examples, the inter-ply peel adhesion strength and fatigue strength retention rate are values determined as follows. Inter-ply peel adhesion strength Indicates the adhesive strength between fabric and rubber. Sandwich a 0.8mm thick rubber sheet between the fabrics,
Furthermore, rubber sheets with a thickness of 0.8 mm were laminated on both sides, and after vulcanization at 150°C for 30 minutes, the force required to peel both fabrics (both plies) at a speed of 200 mm/min was expressed in Kg/2 cm. It is something. Strength retention rate during fatigue Using a Gutsudoritsu disk tester, which is a measure of fatigue resistance, repeated fatigue was measured at 350 degrees with elongation set at 6% and compression set at 18% between rotating disks.
The remaining strength after being applied to the cord 10,000 times is expressed in units of 1,000,000. Example 1 A glass plate with a thickness of about 0.2 mm is attached to a substrate mounting pedestal of an ion plating processing apparatus. Vacuum-dried nylon 6 chips (intrinsic viscosity
1.34) Add 1.5g. Then, after reducing the pressure to 5 × 10 ^-5 Torr, O ₂ gas was introduced into the device and the pressure was reduced to 5 × 10 -5 Torr.
Set to 10 ^-4 Torr. Next, a high-frequency glow discharge of 13.56 MHz was performed, and a low-temperature plasma treatment using O ₂ was applied to the surface of the glass substrate. The discharge output was 100W and the time was 1 minute. Thereafter, the pressure was reduced to 5×10 ⁻⁵ Torr, and then argon gas (Ar) was introduced into the apparatus until the pressure reached 7×10 ⁻⁴ Torr, and a low-temperature plasma of Ar was generated in the same manner as described above. The discharge output at this time was 100W. In this state, the nylon 6 chips were heated to melt and evaporate. When nylon 6 melts and evaporates, the degree of vacuum inside the device decreases, but when the degree of vacuum is 5
When the temperature reached ×10 ^-4 Torr, the introduction of Ar gas was stopped, and from then on, the vacuum level was maintained at 5 × 10 ^-5 Torr by adjusting the temperature at which the nylon was heated and controlling the melting and evaporation rate of nylon 6. . In this manner, nylon vapor generated by melting nylon 6 in an Ar low-temperature plasma atmosphere was turned into plasma, and ion plating was performed in this state for 5 minutes. The discharge output at this time was 100W.
Next, stop heating the nylon 6 and
After reducing the pressure to 10 ^-5 Torr, Ar gas was introduced into the device to bring it to atmospheric pressure, and when we examined the nylon film formed on the glass substrate, we found that the film had a uniform thickness of 100 nm.
It was a thin film of No change was observed even when this membrane was immersed in organic solvents such as methanol, xylene, acetone, and dimethylformamide; It remained insoluble even when immersed in nylon solvents such as chlorophenol. Example 2 A fabric made of 1500 denier/192 filament polyethylene terephthalate multifilament was attached to a substrate mounting pedestal instead of the glass plate of Example 1, and subjected to plasma treatment and ion plating treatment in the same manner as in Example 1. After treatment, immerse it in the RFL treatment agent shown in Table 1 and heat it at 120℃ for 2 hours.
Dry for a minute. Thereafter, it was further heat-treated at 230°C for 2 minutes. The treatment agent was adhered to the polyester fabric thus obtained in an amount of 6 wt% in solids based on the weight of the fabric. The inter-ply peel adhesion strength of the obtained treated fabric was measured. The results are shown in Table 2. Examples 3 to 5 Treated fabrics were produced in exactly the same manner as in Example 2, except that the type of gas used for plasma treatment was changed, and the inter-ply peel adhesion strength of the resulting fabrics was measured. The results are shown in Table 2. Comparative Examples 1 to 3 Treated fabrics were prepared in exactly the same manner as in Examples 2 to 4, except that fabrics that were not subjected to ion plating treatment were used, and the inter-ply peel adhesion strength of the obtained fabrics was measured. The results are shown in Table 2. Comparative Example 4 After immersing a polyester fabric (used in Comparative Examples 1 to 3) that was not subjected to plasma treatment or ion plating treatment in the first treatment agent of an epoxy compound and an isocyanate compound shown in Table 3, It was dried at 120°C for 2 minutes and then heat treated at 230°C for 2 minutes. This was further immersed in the second treatment agent (Table 1) used in Example 2, dried at 120°C for 2 minutes, and then heat-treated at 230°C for 2 minutes. The polyester fabric thus obtained had a solid content of 2.2wt% of the first treatment agent and a solid content of 2.2wt% of the second treatment agent.
2.5wt% was attached. The inter-ply peel adhesion strength of the obtained treated fabric was measured. The results are shown in Table 2.

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Claims (1)

[Claims] 1 Polyester fibers were subjected to low-temperature plasma treatment under reduced pressure, followed by ion plating treatment with polyamide vapor under reduced pressure, and then resorcinol.
A method for processing polyester fibers, which is characterized by processing with formalin rubber latex (RFL).