JPS6072930A - Rubber-reinforcing aromatic polyamide fiber material - Google Patents

Abstract

PURPOSE:The titled fiber material having good adhesion to a rubber product, prepared by treating an aromatic polyamide fiber material first with a resorcinol/formaldehyde condensate containing excessive resorcinol and then with an RFL solution. CONSTITUTION:An aromatic polyamide fiber material (which may be a blend with a polyester fiber) is coated with (i) a resorcinol/formaldehyde condensate containing excessive resorcinol, prepared in the presence of a weak acidic catalyst and, after drying, with (ii) an RFL solution comprising a mixture (solid weight ratio of 1-35:100) containing a resol resorcinol/formaldehyde condensate and rubber latex. The product is then heat-treated.

Description

[Detailed description of the invention] Industrial application field m-... -Muroshiro I + IV Aromatic polyamide or mixed fibers of aromatic polyamide and polyester (hereinafter collectively referred to as these) The present invention relates to aromatic polyamide fiber materials) and methods for adhering rubber to aromatic polyamide fiber materials.

Prior art aromatic polyamides are represented by the chemical structure of the general formula (1) or fcrn), and are generally poly(1,4-benzamide), poly(1,4-phecolene ethylenephthalamide),
Poly(1,3-pheconentylephthalamide), 1,4
-7 enylene terephthalamito'-3,4'-diaminodiphenyl ether copolymer is an aromatic linear polymer directly linked with amide groups. Aromatic polyamide fiber materials are generally , twisted coat′
It is used as a reinforcing material for articles as an industrial reinforcing material, but it is also used as an industrial reinforcing material because it maintains stable mechanical properties, has high strength, high modulus, and has excellent creep properties. It is useful for reinforcing rubber articles such as tires, healds, air springs, rubber hoses, etc. in the form of cord fabrics, canvas, etc. Polyester is a linear polymer with ester bonds in its main chain, typified by polyethylene terephthalate, but fiber materials made by mixing aromatic polyamide and polyester in a filament-like form, Generally, it can be twisted and used as a reinforcing material for rubber articles.

However, the strength of aromatic polyamide and polyester
The modulus of nylon and aromatic polyamide, which are equally important as polyester as reinforcing materials for rubber articles, is not as different from that of aromatic polyamide. In other words, for fiber-reinforced rubber articles that require strength and modulus intermediate between aromatic polyamide and polyester, aromatic polyamide and polyester may be mixed in filament form to achieve strength and modulus intermediate between the two. Filamentary fibrous materials having the following properties are extremely useful. This is because, for example, tires are reinforced with two layers of polyester, and although this can be replaced with a single layer of aromatic polyamide, the number of filamentary fibers in the rubber cannot be increased. If the number of holes is reduced, it may be easy to separate due to problems with the structure of the rubber composite, and the performance of the rubber compound may be sacrificed. This is important because it is a fiber material that is a mixture of aromatic polyamide and polyester in the form of filaments.

Even if ζRO tries to use such aromatic polyamide filamentary fiber materials for rubber reinforcement, they have extremely poor adhesiveness compared to existing fiber materials such as nylon and rayon.

RFL is generally used as an adhesive processing method for rubber reinforcing fiber materials, but the same is true for polyesters mixed in the form of filaments, which is ineffective for aromatic polyamides.

Aromatic boria materials with nylon or rayon are RF
Since nylon and rayon adhere to rubber due to L, adhesion is not a problem if an appropriate physical arrangement of the two is taken when mixed in filament form.

In addition, many methods have been proposed for filamentary fiber materials such as aromatic polyamide and polyester to be surface treated with highly chemically reactive compounds such as epoxy compounds, then treated with RPL, and bonded to rubber. In this case, the filamentary fiber material is hardened, its fatigue resistance against mechanical input is poor, and the epoxy itself is unfavorable.

Purpose of the Invention The present inventors have conducted various studies on bonding methods that do not have the drawbacks of the prior art described above, and as a result, have succeeded in obtaining high adhesive strength and have arrived at the present invention. Therefore, the purpose of the present invention is to Another object of the present invention is to treat aromatic polyamide fiber materials with a specific adhesive to obtain excellent adhesive strength. It lies in giving.

Structure of the Invention The above object is as follows: (1) (a) The reaction molar ratio of resorcinol and formaldehyde is reduced to 1. Q: Q, within the range of 1 to 1.0:0.75, is a resorcin-excess resorcin formaldehyde condensate synthesized without a catalyst or under a weak acidic catalyst, and the component (A) has a formaldehyde content of 20% or less. is applied to an aromatic polyamide fiber material, heat-treated, and then (b) the reaction molar ratio of resorcinol and formaldehyde is 1.0:1.0 to 1.0 in the presence of an alkali catalyst. A resol-type resorcin formaldehyde 11m compound TO-T latex synthesized in the range of Q near and Q was prepared so that the solid content weight ratio of both was in the range of 1:IQQ to 35:100.
This can be achieved by using rubber reinforcing fibers that are heat-treated after applying the mixed RFL liquid (B).

Here, the aromatic polyamide has the following general formula (where Ar
1 and Ar2 represent aromatic groups, and n represents the repeating number. ), and is particularly effective when the aromatic polyamide fiber material to be bonded to rubber is comprised of aromatic polyamide and polyester in the same filamentary fiber material bundle. As polyesters, glycols such as ethylene glycol, globylene glycol, methoxypolyethylene glycol, pentaerythritol, etc. are esterified with dicarboxylic acids or dicarboxylic acid esters such as terephthalic acid, isophthalic acid, dimethyl terephthalate, dimethyl inphthalate, etc. Alternatively, the most typical fiber is polyethylene terephthalate fiber, which is obtained by condensing to a high degree of polymerization by transesterification.

Compound (A), a resorcinol-formaldehyde condensate with too much resorcinol, is obtained by making resorcinol into an aqueous solution, and using a weak acid catalyst such as oxalic acid or without a catalyst, at a molar ratio of formaldehyde to resorcinol of 1:1, 1 to 1:Q, 75 It is preferable that the number of resorcinols is 3 or 4, which is obtained by relatively mild reaction conditions at a temperature of 70°C or lower, and is linked by methylene groups that are formaldehyde-reactive residues, and has a molecular weight as defined in the present invention. You can get the following.

Compound (A) has excellent bonding strength to aromatic polyamide or filiamide, and also bonds to RIi'L, so it can be strongly bonded to rubber. Conventionally, adhesive compounds in this form (A) ).

did not have an adhesive effect on aromatic polyamides, but this is because aromatic polyamides have very low diffusion properties; by optimizing the molecular weight, extremely strong bonding can be achieved. It is what gives rise to power.

The molecular weight referred to in the present invention is defined as follows. 1. The molecular weight is measured using APC (Gel-Sation Chromatography). Sample 0.12 is dissolved by adding T[(Floml), the mobile phase is closed with THF, and the column is coated with THF. G2000 [(
(1ox1) at a flow rate of 1 mel rn at room temperature.
Molecular weights were measured by an RI detector under in conditions.

The obtained GPC chart is as shown in the figure below.The amount of each polymer was determined as follows. ri, S-mer T.

The tetramer is Q, and the S-mer or more is R.

@) Connect the base of the peak on the low molecular weight side and the base of the peak on the high molecular weight side, and use this as the baseline (a).

(1) Draw a perpendicular line (b) from the valley (lowest part) between the peaks of the waveform indicating each molecular weight to the baseline. This is defined as a boundary between adjacent polymers having different molecular weights.

(→The area of the chart showing each type of coalescence was expressed as a percentage of the total area (total area of the GPC waveform on the baseline), and this was taken as the content of each polymer.

As a method for preparing RFL (B) used in the present invention, the reaction molar ratio of resorcinol and formaldehyde is 1, and Q: 1.
．． After aging with an alkaline catalyst (e.g. caustic soda, caustic potash, ammonium hydroxide, urea, thiourea, etc.) in the range of Q to 1.0Nia, 0, rubber latex and 1:IQ
Q~ You can mix in a weight ratio of 35:100 and age for several hours, or you can mix and age resorcinol/formaldehyde pot rubber latex in the above ratio from the beginning.
The amount of alkaline catalyst added is such that the pH after ripening of RFL is 8.5.
-12.0.

A particularly suitable catalyst is ammonium hydroxide, and in this case, it is preferable to mix the resorcin formaldehyde/rubber latex from the beginning and then ripen it.

Further, as the rubber latex used for RFL, one or more types of synthetic rubber latex such as natural rubber latex, styrene-butadiene copolymer rubber latex, styrene-vinylpyridine-butadiene copolymer rubber latex, etc. may be used. Generally, the type of rubber latex is determined depending on the type of rubber to be bonded.

The aromatic polyamide fiber material is treated with an adhesive as described above, and the application methods include immersing the twisted cord or filamentary fiber material in the adhesive solution and attaching it, applying the adhesive solution with a doctor knife, etc. Alternatively, there is a method of spraying, and you can choose the appropriate method depending on the situation.

As mentioned above, the form of the adhesive is that an aqueous alkaline solution of the compound is first applied, then heat treated, and then RFL,
There is a method of applying liquid (B) and heat-treating, but this heat-treating is preferably performed at a temperature of at least 200° C. or higher and 250° C. or lower.

The reason is that the adhesive compound (A) of the present invention, a component, diffuses into fibers for aromatic polyamide and polyester mixed and twisted with aromatic polyamide in a filament shape, and RFL is a co-vulcanizable adhesive with rubber. The adhesive force is developed by reacting with the adhesive, and the higher the temperature, the better the result. Further, temperatures of 250° C. or higher are undesirable because deterioration of the aromatic polyamide and polyester and deterioration of the adhesive are observed.

By the above method, the aromatic polyamide filamentary fiber material of the present invention and rubber can be bonded together.

The rubber used in the present invention refers to natural rubber and synthetic rubber in general, and is generally called a rubber-like elastic polymer. In particular, one or more rubbers selected from the general-purpose rubber group of natural rubber, styrene-butadiene copolymer rubber, polybutadiene rubber, polyimprene rubber, isopreno-in-butylene copolymer rubber, and polychloroprene rubber. means a formulation of a blend.

In the present invention, the filamentary fiber bundle containing aromatic polyamide and polyester refers to one in which the aromatic polyamide and polyester filamentary fiber materials are individually twisted and then twisted together;
The aromatic polyamide fiber material of the present invention can be selected according to the purpose of reinforcing rubber articles, such as by pre-twisting filamentary fiber materials of aromatic polyamide and polyester. It adheres strongly to rubber, hardens the filament-like fiber material, has excellent fatigue resistance against mechanical input, and does not cause pollution problems, making it extremely useful for industrial use.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 (1) Poly(1,4 phenylene terephthalamide) as aromatic polyamide <trade name Kevlar manufactured by DuPont
>1500 d raw yarn was twisted with a number of first twists of 32 times/10 m and a number of final twists of 32 times/10 m to obtain a cord with a twisted structure of 150G (L/2).

(2) Resorcinol 11os, 0.62 parts of Shu [0.62 parts] and 248 parts of water were placed in a Kolben, and while stirring at 60°C, 50 parts of 37% formalin was added dropwise over 1 hour.
The mixture was further stirred for 1 hour to obtain a resorcin-excess resorcin formaldehyde condensate (A). When I measured apc, it was 5.
The content of mercury or more is 31. Sqb, and the monomer content was 10.8.

From there, 36 parts of solid content were taken out, 18 parts of 28 thiammonium water was added thereto, and water was further added so that the total amount was 100 parts to completely dissolve, and an adhesive liquid was obtained.

(3) Next, using a combutreator made by Riller, immerse the cord in the above-mentioned water at 160°C x 60”
After passing through a drying oven of
The cord was passed through a 0°C x 60# drying oven and then a 220°C x 60'' heat treatment oven to obtain an adhesive-treated cord.

Water 518.8 Resorcinol 11.0 Formalin (37%) 16.2 Ammonium hydroxide (28%) 10.0 Vinylpyridine-styrene-244.0 Butadiene copolymer rubber latex (41%) Numbers indicate parts by weight The adhesion strength of the resulting cord was
Embed the adhesive processing cord into the unvulcanized compounded rubber composition,
Vulcanize at 145°C for 30 minutes under a pressure of 2 kg/tan2,
A cord was excavated from the obtained vulcanizate and coated at a speed of 30 m/min.

was peeled from the vulcanizate, and the peel resistance was measured, and this was taken as the adhesive strength (kg/piece). The results are shown in Table 1.

The compounded rubber composition used is as follows.

Styrene-butadiene copolymer rubber 20 Carbon black 4° Stearic acid 2 Petroleum softener 1° Binal 4 Zinc flower 5 N-phenyl-β-naphthylamine 1.52-penzothiazolyl disulfide)' 0.75 diphthylamine Enylguanidine 0.75 Example 2 The aromatic polyamide of Example 1 was mixed with 1500+1 of 1,4-phenylene terephthalamide-5,4'-diaminodiphenyl ether copolymer (trade name: Ni-50, manufactured by Teijin).
The processing and evaluation were carried out in the same manner as in Example 1, except that the raw yarn was changed to . The results are shown in Table 1.The structure of the 1,4-phenylene terephthalamide-3,41-diaminodiphenyl ether copolymer is shown in Table 1.

Example 3 As an aromatic polyamide, a 150 Od yarn of poly(1 μm phenylene terephthalamide) was twisted 29 times/1.
03. As polyester, 1500 d raw yarn of polyethylene terephthalate was twisted with a first twist of 18 times/10α, then both were placed together and twisted with a final twist of 29 times/10 cm.
The processing and evaluation were carried out in the same manner as in Example 1, except that a 500 d/2 composite fiber material cord was used. Display the results -
Shown in 1.

Example 4 A 1500 d yarn of poly(1,4 phenylene terephuclamide) as an aromatic polyamide was twisted 29 times/10 times.
crn, as polyester, 1500 d raw yarn of polyethylene terephthalate is twisted at 29 times/10 (7), and the combined fibers are twisted at 29 times/10 cm to create a 1500 d/2 composite fiber monthly cord. The processing and evaluation were carried out in the same manner as in Example 1 except for the following.

The results are shown in Table-1.

Comparative Example 1 The aromatic polyamide cord of Example 1 was immersed in a mixture of 50 parts each of the adhesive liquid of Example 1 and RFL, and then heated at 240°C through a 160°C x 60'' drying oven.
The same evaluation as in Example 1 was carried out except that the cord was passed through a 120' heat treatment furnace to obtain an adhesive-treated cord. The results are shown in Table-1.

Comparative Example 2 The resorcin-rich formaldehyde condensate (A) of Example 1 was dissolved in resorcin t6oit Kolben for 12 hours.
Melt by heating to 0°C and add 37% formalin 4 under reflux cooling.
5 parts were added dropwise over 20 minutes with stirring and an additional 20 parts
The same processing and evaluation as in Example 1 were carried out except that the monomer content was changed to 10.2% and the content of si form or higher was 38.7%.

Comparative Example 3 Too much resorcin in 'J [flJl] Resorcin was added to the resorcin formaldehyde condensate (A) to increase the amount of resorcin, and as determined by GPC measurement, the monomer content was 21.3%.
The same processing and evaluation as in Example 1 were carried out except that the composition was changed to a composition having a pentamer or higher content of 27.8%. Display the results -
Shown in 1.

Table-1

[Brief explanation of drawings]

The attached figure shows an APC CHAD model of the components of the adhesive of the invention.

Claims (3)

[Claims] (1) (a) The reaction molar ratio of resorcinol and formaldehyde is 1. Q: Q, within the range of 1 to 1.0:0.75, is a resorcin-excess resorcin formaldehyde condensate synthesized without catalyst or under a weak acidic catalyst, and the component (A) has a formaldehyde content of 20% or less. was coated on an aromatic polyamide fiber material and heat-treated, and then (1) reaction molar ratio of resorcinol and formaldehyde in the presence of an alkali catalyst t: 1. , . :1.0~1. Resol-type resorcin formaldehyde 8 compound synthesized in the range of Q near, Q,! =Rubber latex with a solid content weight ratio of 1:100 to 35:10G
The amount of mixed rubber reinforcing fiber material is within the range of 0. (2) The aromatic polyamide has the following general formula (where Ar
1 and Ar2 represent aromatic groups (Table 1), and n represents the repeating number. ) Claim (1) or (2) that breaks
Aromatic polyamide fiber material for rubber reinforcement. (3) Aromatic polyamide fiber feather material with aromatic core IJ
An aromatic polyamide fiber material for rubber reinforcement according to claims (1) to (3), which is a filamentous fiber bundle containing mixed and twisted amide fibers and polyester fibers.