JPH02281054A - Production of fiber reinforced rubber composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition having excellent processing properties and strength of vulcanized material by blending vulcanizable rubber with acrylic fibers in the presence of a phenol-formaldehyde-based resin and a formaldehyde donor and pulverizing the fibers. CONSTITUTION:(A) 100 pts.wt. vulcanizable rubber is blended with (B) 3 to 150 pts.wt. acrylic fibers (preferably >=10g/denier tensile strength and 1 to 20mm fiber length) in the presence of 0.2 to 15 pts.wt., preferably 1 to 10 pts.wt. resorcinol and/or phenolformaldehyde-based resin and 0.2 to 20 pts.wt., preferably 1 to 15 pts.wt. formaldehyde donor (e.g. formalin) based on 100 pts.wt. total amounts of the components A and B and the fibers are pulverized to give the aimed composition.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for producing a fiber-reinforced rubber composition, and more specifically, to a method for producing a novel fiber-reinforced rubber composition with excellent processability and strength of vulcanizate. It is about law.

[Conventional technology]

Conventionally, reinforcing rubber compositions used for belts, hoses, tires, etc. contain short fibers such as cellulose, vinylon, nylon, polyester, and aromatic polyamide in vulcanizable rubber.

However, in such short fiber reinforced rubber compositions, the fiber diameter is large and the fibers and rubber are not bonded, so the excellent properties of the fibers are not fully exhibited. Furthermore, when these fibers are used as reinforcing materials for rubber products, there is a problem in that the manufacturing process of the rubber products becomes complicated and the manufacturing cost increases.

[Problem to be solved by the invention]

An object of the present invention is to provide a method for producing a fiber-reinforced rubber composition that can produce a fiber-reinforced rubber composition with excellent processability and mechanical properties of a vulcanizate at a low cost.

[Means to solve the problem]

In view of the above-mentioned problems of the prior art, the present inventors conducted extensive research and found that vulcanizable rubber and acrylic fibers are mixed in the presence of resorcinol and/or phenol-formaldehyde-based resin and formaldehyde-donating agent. Add other additives as necessary and knead under high shear force.
It was discovered that a fiber-reinforced rubber composition with excellent processability and strength characteristics can be produced by mixing and making the fibers finer, and the present invention was achieved based on this discovery.

That is, the present invention combines (a) 100 parts by weight of vulcanizable rubber and (b) 3 to 150 parts by weight of acrylic fiber, with respect to 100 parts by weight of the total amount of (a) and (b), resorcinol and/or Phenol formaldehyde resin 0.2
~15 parts by weight, and 0.2 parts by weight of formaldehyde donor
The fibers are kneaded and mixed in the presence of ~20 parts by weight to make the fibers fine.

The vulcanizable rubber (a) used in the present invention is not particularly limited as long as it provides a rubber elastic body by vulcanization, such as natural rubber, polybutadiene rubber,
Carboxy-containing rubbers such as polyisoprene rubber, polychloroprene rubber, acrylonitrile butadiene rubber (NBR), styrene butadiene rubber (SBR), butyl rubber, ethylene propylene rubber, carboxy NBR, carboxy SBR, ethylene acrylate rubber, epichlorohydrin rubber, Examples include various hydrogenated rubbers such as acrylic rubber, silicone rubber, fluororubber, hydrogenated NBR and hydrogenated SBR, chlorinated polyethylene, chlorosulfonated polyethylene, halogenated butyl rubber, various modified rubbers, and various thermoplastic elastomers. . These are one or two types
A mixture of two or more species can be used.

The acrylic fiber (b) used in the present invention is not particularly limited, but preferably has a tensile strength of 10 g/denyl or more. Further, the fiber length of these fibers is preferably about 1 to 20 mm. If the fibers are too short, the reinforcing properties will be poor due to the small aspect ratio, and it will be difficult to apply shearing force when kneading with rubber, so the fibers may not be sufficiently refined. On the other hand, if the fibers are too long, the fibers may become entangled with each other during kneading with rubber, resulting in purling of the fibers and uneven dispersion into the rubber.

The amount of acrylic fibers to be blended is 3 to 150 parts by weight, preferably 10 to 100 parts by weight, based on 100 parts by weight of vulcanizable rubber. If the amount of fiber blended is less than 3 parts by weight, when the composition is used as a masterbatch, the effect of blending the fibers will hardly be obtained, and if it exceeds 150 parts by weight, kneading properties will be poor and dispersion into rubber will be poor. This results in non-uniformity and poor mechanical strength.

The phenol formaldehyde resin used in the present invention is, for example, manufactured by Gunei Chemical Industry Co., Ltd. under the trade name PL-22.
11 is used, and modified phenolic resins such as resorcinol, cresol, cashew, melamine, etc. can also be used.

The amount of resorcinol and/or phenol formaldehyde resin used in the present invention is the total amount of (a) vulcanizable rubber and (b) acrylic fiber: 100! The amount is 0.2 to 1.5 parts by weight, preferably 1 to 10 parts by weight, based on the amount of E. If it is less than 0.2 parts by weight, the bonding between the fibers and the rubber will not proceed sufficiently, and if it exceeds 15 parts by weight, the hardness of the composition will increase too much.

As the formaldehyde donor used in the present invention,
Any compound that generates formaldehyde when heated may be used, such as formalin, hexamethylenetetramine, acetaldehyde ammonia, paraformaldehyde, α-polyoxymethylene, polyvalent methylolmelamine derivatives such as hexamethoxymethylmelamine, oxazolidine derivatives, and polymethylolated compounds. Examples include acetylene urea.

The amount of the formaldehyde donor is 0.2 to 20 parts by weight, preferably 1 to 15 parts by weight, based on 100 parts by weight of the total amount of (a) vulcanizable rubber and (b) acrylic fiber. If it is less than 0.2 parts by weight, the bonding between the fiber and rubber will not proceed sufficiently, and if it exceeds 20 parts by weight, the performance of the composition will deteriorate.

In addition to the vulcanizable rubber, acrylic fiber, resorcinol and/or phenol-formaldehyde resin, and formaldehyde donor, the composition of the present invention may optionally contain carbon black, an inorganic filler, a plasticizer, and a softening agent. , anti-aging agents, various stabilizers, processing aids, metal oxides used as acid acceptors and other known rubber additives can be added. Incorporation of appropriate amounts of carbon black, inorganic fillers, plasticizers, softeners, etc. is effective in improving kneading properties, improving dispersibility of fibers in rubber, and making fibers finer. Furthermore, when the composition is blended as a masterbatch, it has an effect on processability and dispersibility.

The blending amount of the carbon black and/or inorganic filler is 1 to 600 parts by weight per 100 parts by weight of vulcanizable rubber.
The MR part is preferred, particularly preferably 5 to 500 parts by weight. If the amount is less than 1 part by weight, no effect as a filler can be expected, and if the amount is less than 1 part by weight, the amount of 600! If the amount exceeds this amount, kneading may become difficult.

Carbon blacks include SAF, 15AF, HAF, and MAF, which are commonly used for rubber applications.

FEF, GPFXSRF, FT, etc. can be used. Inorganic fillers include calcium carbonate, silica,
Magnesium carbonate, clay, talc, etc. can be used.

The amount of the plasticizer and softener used is preferably 1 to 300 parts by weight, particularly preferably 5 to 250 parts by weight, per 100 parts by weight of vulcanizable rubber. If it is less than 1 part by weight, no plasticizing effect can be obtained, and if it exceeds 300 parts by weight, the plasticity of the composition may become too high. Examples of plasticizers and softeners include aromatic, naphthenic, and paraffinic process oils, phthalate, adipate, sebacate, phosphate, and polyester plasticizers, polybutenes, and various liquid rubbers. Can be used.

The fiber-reinforced rubber composition of the present invention is produced by kneading and mixing vulcanizable rubber and acrylic fibers in the presence of resorcinol and/or phenol formaldehyde resin and formaldehyde donor, along with other additives as necessary. , manufactured by refining the fibers. The degree of fiber refinement is preferably in the range of 1/200 or more and 115 or less, more preferably 1/150 or more and 1/10 or less of the original fiber diameter. 1/2 of the original fiber diameter
If it is less than 00, a large amount of energy is required to make the fiber finer, which is not economical, and if it exceeds 115, the effect of making the fiber finer may not be obtained. The amount of fibers to be refined is at least 10% by weight of the acrylic fibers used.
It is preferably at least 20% by weight, more preferably at least 20% by weight.

The above-mentioned fibers need to be kneaded and mixed in a vulcanizable rubber to form fine fibers, but the kneading is preferably carried out under high shearing force. Further, in order to bond the fine fibers and the vulcanizable rubber, it is preferable to maintain the temperature at a temperature higher than that at which the formaldehyde donor releases formaldehyde.

The kneading is preferably carried out for 5 to 120 minutes using a kneading device such as a Banbury mixer, single screw or twin screw extruder, kneader, intermixer, Prabender blastograph, or mixing roll, alone or in combination. .

Although there is no particular restriction on the method of adding the above-mentioned components to the kneading device, it may be carried out, for example, as follows. First, vulcanizable rubber is put into a kneading device and masticated, and then acrylic fibers are put in and kneaded to disperse the fibers into the rubber. If carbon black, inorganic fillers, plasticizers, softeners, etc. need to be added, they are added and kneaded at the same time as the fibers, or before or after, and dispersed in the rubber. Next, resorcinol and/or phenol-formaldehyde resin is added and kneaded, and finally a formaldehyde donor is added,
The fiber-reinforced rubber composition of the present invention is obtained by kneading for a minute at a temperature equal to or higher than the aldehyde release temperature of the aldehyde donor.

The kneading may be performed continuously or intermittently. In cases where there is a risk of deterioration of the vulcanizable rubber due to the large amount of heat generated during cross-talk, or in cases where increased temperature increases fluidity, it is difficult to apply shearing force, and fiber refinement is not successful. It is preferable to carry out the kneading intermittently in several batches. In this case, if the formaldehyde donor is added in portions, as the fibers become finer, the newly generated formaldehyde can efficiently bond the fibers and the rubber.

The fiber-reinforced rubber composition of the present invention is used alone or as a blend with vulcanizable rubber or the like as a fiber masterbatch. In particular, when used as a fiber masterbatch, the dispersibility of the fibers in the rubber is improved, and the fabric of the composition is made softer, which improves processability, and it also improves cost and performance compared to blending the fibers directly into the rubber. It is advantageous. In addition, when blending with vulcanizable rubber, carbon black, inorganic fillers, plasticizers, softeners, anti-aging agents, processing aids, vulcanization aids, vulcanization accelerators, vulcanization Agents etc. can also be added.

By vulcanizing the composition of the present invention, a vulcanizate with excellent modulus, tensile strength, fatigue properties, and heat resistance can be obtained, and by utilizing the excellent properties, it can be used for tire applications such as carcass and tread, hoses, etc. It can be used in industrial products such as belts, seals and gaskets, and as footwear materials.

〔Example〕

EXAMPLES Hereinafter, the present invention will be explained in detail with reference to examples, but the present invention is not limited to these examples at all. In the examples, parts mean parts by weight.

Example 1 100 parts of NBR (trade name JSRN230S, manufactured by Japan Synthetic Rubber Co., Ltd.) was put into a BR type 1.72 capacity Banbury mixer set at 50°C and 160 rpm, and after mastication for 30 seconds, high-strength acrylic fiber ( 2. 50 parts (manufactured by Mitsubishi Rayon Co., Ltd., fiber diameter 12 μ, strength 12 g/d) and 2.5 parts of resorcinol (manufactured by Wako Pure Chemical Industries, Ltd.) were added.
Knead for 5 minutes, then add hexamethoxymethylmelamine (
(manufactured by Mitsubishi Monsando Kasei Co., Ltd.) was added and kneaded for 2.0 minutes to obtain a kneaded product. After cooling the kneaded material, the entire amount was again put into the Banbury mixer set to the above conditions, and 2
．． Kneaded for 5 minutes. Similar operations were repeated intermittently for a total of 15 times.

<Measurement of the degree of fineness of fibers> 0.5 g of the fiber reinforced rubber composition obtained above was added to MEK1
00m/! After the fibers were separated by filtration and dried, the degree of fineness was measured using a scanning electron microscope (SEM). The results are shown in Table 1.

Note that the degree of refinement was determined based on the SEM photographs (magnification = 260 times) shown in FIGS. 1, 2, and 3.

In other words, Fig. 1 shows a 1.71 Banbury mixer with 3
It is a diagram showing the state of fineness of fibers when kneaded for minutes, and this state is expressed by the degree of refinement x. The fiber diameter at this time is about 12 parts. Further, FIG. 2 is a diagram showing a state in which the fibers have been refined to a necessary degree, and the degree of refinement is expressed as 0. Most of the fine fibers have a diameter of about 0.3 to 1.2 g. Further, FIG. 3 is a diagram showing a state in which the fibers have been sufficiently refined, and the degree of refinement is indicated by ◎.

Evaluation Test> The fiber-reinforced rubber composition obtained above was vulcanized at 170°C for 20 minutes according to the formulation shown in Table 2, and the physical properties of the obtained vulcanizate were measured. The results are shown in Table 2. In addition,
Physical property tests of the vulcanizate were conducted in accordance with JIS K6301.

Example 2 In Example 1, carbon black FE was added following high-strength acrylic fiber when producing a fiber-reinforced rubber composition.
The same procedure as in Example 1 was carried out except that 20 parts of F was added.
A vulcanizate was obtained and its physical properties were measured. The results are shown in Tables 1 and 2.

Example 3 In Example 1, carbon black FE was added following high-strength acrylic fiber when producing a fiber-reinforced rubber composition.
A vulcanizate was obtained in the same manner as in Example 1 except that 20 parts of F, 50 parts of carbon black SRF, and 30 parts of dioctyl phthalate were added, and its physical properties were measured. The results are shown in Tables 1 and 2.

Example 4 100 parts of NBR was put into a BR type 1.71 capacity Banbury mixer set at room temperature and 60 rpm, and masticated for 30 seconds. After that, 50 parts of high-strength acrylic fiber, 20 parts of carbon black FEF and SRF were added, and 50
30 parts of dioctyl phthalate, 5 parts of ZnO, 1 part of stearic acid, 0.5 part of 2.2.4-1-dimethyl-1,2-dihydroquinoline polymer, 3 parts of coumaron resin, 1 part of microcrystal wax, Subsequently, 2.5 parts of resorcinol were added and kneaded for 2.5 minutes, then 10 parts of hexamethoxymethylmelamine was added and kneaded for 2 minutes to obtain a kneaded product. After cooling the kneaded material, the entire amount was again put into the BR type Banbury mixer set to the above conditions, and 2.5
Mixed for a minute. This operation was repeated 10 times intermittently.

The obtained fiber-reinforced rubber composition was prepared in the same manner as in Example 1 using the formulations shown in Table 2 to obtain a vulcanizate, and its physical properties were measured. The results are shown in Tables 1 and 2.

Example 5 A vulcanizate was obtained in the same manner as in Example 4, except that re-kneading was carried out in a BR type Banbury mixer 15 times for 2.5 minutes, and its physical properties were measured. The results are shown in Tables 1 and 2.

Example 6 In Example 1, carbon black SR was added following high-strength acrylic fiber when producing a fiber-reinforced rubber composition.
A vulcanizate was obtained in the same manner as in Example 1 except that 40 parts of F and 20 parts of white carbon were added, and its physical properties were measured. The results are shown in Tables 1 and 2.

Example 7 The same procedure as in Example 5 was conducted except that 5 parts of phenolic resin (manufactured by Gunei Kagaku Co., Ltd.) was used instead of resorcinol when producing the fiber-reinforced rubber composition, and the vulcanizate was prepared in the same manner as in Example 5. was obtained and its physical properties were measured.

The results are shown in Tables 1 and 2.

Example 8 100 parts of NBR was put into a BR type 1.72 capacity Banbury mixer set at room temperature and 60 rpm, and masticated for 30 seconds, followed by 100 parts of high-strength acrylic fiber and 5 parts of resorcinol. After kneading for 0.5 minutes, 15 parts of hexamethoxymethylmelamine was added and kneading was continued for 7.5 minutes. The obtained reinforced rubber composition was treated in the same manner as in Example 1 to obtain a vulcanizate, and its physical properties were measured.

The results are shown in Tables 1 and 2.

Example 9 A vulcanizate was obtained in the same manner as in Example 1, except that the fiber reinforced rubber composition obtained in Example 1 was kneaded according to the formulation shown in Table 2, and its physical properties were measured.

The results are shown in Table 2.

Example 10 In Example 4, a fiber-reinforced rubber composition was prepared without adding hexamethoxymethylmelamine, and when blending the accelerator, 10% of hexamethoxymethylmelamine was added on the roll.
A vulcanizate was obtained in the same manner as in Example 4, except that 50% of the vulcanizate was added, and its physical properties were measured. The results are shown in Tables 1 and 2.

Comparative Example 1 NBR101 was charged into a BR type 1.71 capacity Banbury mixer set at 50°C and 60 rpm.
After mastication for seconds, 50 parts of high strength acrylic fiber, 2.5 parts of resorcinol and 10 parts of hexamethoxymethylmelamine
1 part was then added and kneaded for 4.5 minutes to obtain a kneaded product. Example 1 was prepared using the obtained kneaded product according to the formulation shown in Table 2.
A vulcanizate was obtained in the same manner as above, and its physical properties were measured. The results are shown in Tables 1 and 2.

Comparative Example 2 100 parts of NBR was put into a BR type 1.71 capacity Banbury mixer set at 50°C and 60 rpm.
After masticating for seconds, 50 parts of high-strength acrylic fiber, 70 parts of carbon black, and 30 parts of dioctyl phthalate were subsequently added and kneaded for 4.5 minutes to obtain a kneaded product. After cooling the kneaded material, the entire amount was again put into the BR Banbury mixer set to the above conditions and kneaded for 2.5 minutes. This operation was repeated 15 times intermittently. The kneaded product was prepared in the same manner as in Example 1 using the formulation shown in Table 2 to obtain a vulcanized product, and its physical properties were measured. The results are shown in Tables 1 and 2.

Comparative Example 3 A vulcanizate was obtained in the same manner as in Example 6 except that hexamethoxymethylmelamine was not added, and its physical properties were measured. The results are shown in Tables 1 and 2.

Comparative Example 4 A vulcanizate was obtained in the same manner as in Example 5 except that resorcinol was not added, and its physical properties were measured.

The results are shown in Tables 1 and 2.

Comparative Example 5 In Comparative Example 1, when producing a fiber reinforced rubber composition, carbon black 7 was added following high strength acrylic fiber.
0 parts, 30 parts of dioctyl phthalate, 5 parts of ZnO, 1 part of stearic acid, 1 part of microcrystal wax, 2,
2.4-) The same procedure as Comparative Example 1 was carried out, except that 0.5 parts of a polymer of trimethyl-1,2-dihydroquinoline and 3 parts of coumaron resin were added, and resorcinol and hexamethoxymethylmelamine were not added. A vulcanizate was obtained and its physical properties were measured. The results are shown in Tables 1 and 2.

Comparative Example 6 100 parts of NBR was added to a BR type 1.71 capacity Banbury mixer set at 50°C and 160 rpm.
After masticating for 0 seconds, 24.9 parts of high strength acrylic fiber,
70 parts of carbon black, 30 parts of dioctyl phthalate, 5 parts of ZnO, 1 part of stearic acid, 0.5 part of 2,2,4-trimethyl-1,2-dihydroquinoline polymer, 3 parts of coumaron resin, 1 part of microcrystal wax. A vulcanized product was obtained in the same manner as in Example 1, except that 1.3 parts of resorcinol, and 5 parts of hexamethoxymethylmelamine were added and kneaded for 4.5 minutes, and its physical properties were measured. The results are shown in Tables 1 and 2.

Margin below Manufactured by Japan Synthetic Rubber Co., Ltd. JSRN230S = Manufactured by Hishi Rayon Co., Ltd. Geast SO made by Tokai Carbon Co., Ltd. HTCIs manufactured by Chubu Carbon Co., Ltd. Nippon Silica Co., Ltd. Nip Seal VN.

DOP manufactured by Blockbuster Chemical Co., Ltd. R3107 manufactured by Adeka Argus Co., Ltd. Antioxidant RD manufactured by Seiko Chemical Co., Ltd. N-cyclohexyl-2-benzothiacylsulfenamide *10: Tetramethylthiuram disulfide *11: Manufactured by Tsurumi Chemical Co., Ltd. Sulfax A *12: [Observation results of the fractured surface of the test piece after the rubber tension test O = Rubber fracture × = Interface fracture between rubber and fiber * l *2 *3 *4 *5 *6 *7 *8 *9 Based on the above results , Comparative Examples 1 and 6 use resorcin and hexamethoxymethylmelamine as a binder between vulcanizable rubber and fibers, but the fibers are not refined, and Comparative Example 2 uses resorcin and Comparative Example 3 is an example in which fibers were made fine in the absence of hexamethoxymethylmelamine, and Comparative Example 4 is an example in which fibers were made fine in the absence of hexamethoxymethylmelamine. Comparative Example 5, which is an example of finer fibers, is an example in which neither resorcinol nor hexamethoxymethylmelamine is used, nor is the fiber finer. Rubber NB that has extremely excellent processability of reinforced rubber compositions and strength properties of vulcanizates, and that can be used to vulcanize fiber-reinforced rubber compositions.
Example 9 and Example 9, which were blended with R, were similarly excellent in workability and strength properties. This demonstrated the need for fiber refinement by high shear forces in the presence of resorcinol and formaldehyde donor. The results of Example 7 showed that phenolic resin can be used in place of resorcinol. Furthermore, the results of Example 10 showed that even if hexamethoxymethylmelamine was added on a roll during blending of the vulcanization accelerator after the formaldehyde donor was added, the strength properties were excellent.

Further, in all of the comparative examples, interface destruction between the fiber and rubber occurred, whereas in all the examples, rubber failure occurred. This confirms that the fibers and rubber are bonded well.

[Effects of the Invention] According to the method for producing a fiber-reinforced rubber composition of the present invention, a fiber-reinforced rubber composition with excellent processability and mechanical properties of a vulcanizate can be produced at low cost. The composition is used for tire applications such as carcass and tread, hoses, belts,
It is useful for applications such as industrial products such as seals and gaskets, and footwear materials.

[Brief explanation of drawings]

Figure 1 shows 1. M! Figure 2 is a micrograph showing that the fibers have hardly been refined after 3 minutes of kneading with a Banbury mixer. FIG. 3 is a microscopic photograph showing a state in which the fibers have been sufficiently refined.

Claims (1)

[Claims] (1) Add 100 parts by weight of (a) vulcanizable rubber and (b) 3 to 150 parts by weight of acrylic fiber to 100 parts by weight of the total amount of (a) and (b), and add resorcinol and/or phenol formaldehyde based A method for producing a fiber-reinforced rubber composition, which comprises kneading and mixing in the presence of 0.2 to 15 parts by weight of a resin and 0.2 to 20 parts by weight of a formaldehyde donor to make the fibers fine.