JPS61228024A - Production of granular rubber - Google Patents

Abstract

PURPOSE:To produce a granular rubber having excellent kneading dispersibility a nd processability, in high efficiency at a low cost, by crushing a porous unvulcanized rubber having a specific bulk density in the presence of a resinforcing filler. CONSTITUTION:100pts.(wt.) of a porous unvulcanized rubber having a bulk density of 0.01-0.7, preferably 0.1-0.5 (preferably a natural rubber or a synthetic rubber having unsaturated bond in the main chain, e.g. isobutene-isoprene rubber, etc.) is mixed with preferably 10-60pts. of a reinforcing filler (preferably carbon black) and the mixture is crushed with a small-sized crusher preferably at room temperature to obtain the objective granular rubber.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a method for producing granular combs, which has a good kneading and dispersion effect when kneading a comb composition and improves the quality of the bead-kneaded rubber. More specifically, the present invention relates to a method for efficiently and inexpensively manufacturing such granular rubber.

BACKGROUND ART Conventionally, granular rubber has been expected to have many advantages in handling, processing, and quality design of rubber. In particular, the advantages of granular rubber are expected to be utilized from the perspective of automating the manufacturing process of rubber products such as tires, hoses, belts, anti-vibration rubber, fenders, cables, and f-skets. However, so far, there have been few proposals regarding a method for producing granular combs that are advantageous in quality compared to ordinary rubber, and are inexpensive and efficient. Therefore, the emergence of granular rubber that can be widely used industrially by an inexpensive and efficient manufacturing method is awaited.

That is, conventionally known methods for producing granular rubber can be broadly divided into the following two methods.

One of them is a method of producing powdered rubber by mixing f-mulate and a mold release agent, coagulating and coprecipitating and drying, or omitting coagulating and coprecipitating and spray drying. In this case, the raw materials for producing rubber powders are limited to emulsion polymers, in particular nitrile rubber and emulsion SBH, conventionally consisting of milling, spray drying and coagulation of these elastomeric latexes in the presence of anti-adhesives and surfactants. Methods to do so have been reported. For example, U.S. Pat.
Publication No. 32501 describes a method for producing comb powder from a hydrocarbon solution, rubber, Cargenzola, resin, and an antifoaming surfactant, and furthermore, regarding the technology related to granular rubber, Patent No. 2777008, Patent No. 32
No. 45945, No. 3203922, No. 30601
It is also described in No. 45 and No. 3251798.

However, when these methods are applied to solution-reactive synthetic rubber, they require a step to convert them into latex, making them expensive and inefficient methods for producing granular rubber. Excessive mold release agents such as water glass are often used to stabilize the product, which has the disadvantage of leaving quality problems such as having a negative impact on fatigue durability after being made into a rubber product. .

In addition, as another conventional manufacturing method for powdered rubber, a method has been proposed in which granular or powdered rubber is produced by mechanically pulverizing veil-like or slab-like rubber in the coexistence of a mold release agent (Japanese Patent Application Laid-Open No. No. 53-54245 and No. 59-24734)
. However, this method requires a large amount of energy to crush the bale-like or slab-like rubber, and therefore has the problem of being expensive and inefficient.

For this reason, it has superior quality compared to regular rubber.
There is also a strong demand for the development of an inexpensive and efficient method for producing granular rubber or powdered rubber.

Summary of the Invention The present inventors have carried out intensive research in order to solve the above problems, and as a result, the bulk specific gravity in a specific range, that is, 0. When porous uncured rubber with a bulk specific gravity of O1 to 0.7 is mechanically crushed together with a filling reinforcing agent, using a small crusher at room temperature can be done efficiently with low crushing energy, greatly increasing productivity. It has been discovered that granular rubber can be manufactured at low cost with improved performance, and that the obtained granular rubber has good kneading and dispersion effects, improving the quality of kneaded rubber, and has led to the invention.・In other words, the conventional method of pulverizing bale-shaped or slab-shaped rubber as a raw material has problems in the cutting and pulverizing processes, and requires large-scale equipment, space, pulverizing energy, and man-hours. shall be.

In contrast, the method of the present invention has a bulk specific gravity of 0.01 to 0.7.
The energy required for rubber pulverization can be reduced by using porous unhardened rubber, especially porous unhardened rubber obtained from the normal desolvation or drying process of raw rubber, and pulverizing it in the coexistence with a filling reinforcing agent. This made it possible to significantly reduce the amount and improve manufacturing capacity.

The present invention will be explained in more detail below.

Structure of the Invention The method for producing granular rubber according to the present invention has a bulk specific gravity of 0.01.
-0.7 porous uncured rubber in the coexistence of a filling reinforcing agent, the method is characterized by grinding porous uncured rubber having a particle diameter of -0.7 in the presence of a filling reinforcing agent, and efficiently using a small grinder at room temperature with low grinding energy.
Granular rubber can be produced more cheaply than porous uncured rubber.

In this case, the porous uncured rubber having a bulk specific gravity tW of 0.01 to 0.7 is, for example, a porous uncured rubber obtained immediately after removing the solvent after the synthesis reaction in a solution of synthetic rubber synthesized by a bath reaction. Uncured rubber, natural rubber obtained in the form of a latex, and porous uncured rubber obtained immediately after coagulation and drying of the synthetic rubber latex can be used.

Accordingly, in the present invention, both natural rubber and synthetic rubber can be used, but examples of natural rubber include para rubber, guanyl rubber, and mixed rubbers thereof. It is also possible to use chemically modified natural rubbers, such as chemically modified and sulfonated rubbers. Synthetic rubbers include rubbers, lates, and rubbers specified in ASTM standards, and such rubbers and latexes include saturated polymethylene synthetic rubbers, such as those made from acrylate and α-olefin polymers, Related copolymers, such as those of the ethylene propylene type (EPM or EPR), terpolymers of various types, such as EPDM, /'? -7A/oro rubber (FKM and FFKM), oxygenated rubbers containing oxygen in the polymer chain, such as those obtained from ethylene and propylene (POR: 7° propylene oxide dodem, ECHR: epichlorohydrin rubber), their sulfurs 8
3. In addition to phosphazene rubber and silicone rubber (Sa), other synthetic rubbers include / 17-mer chains containing carbon, oxygen, and nitrogen, such as urethane type 1-hydrogenated rubbers. Examples of chemically treated synthetic compounds include hydrogenated BR, chlorinated BR, brominated BR, and the like. Particularly preferred rubbers are natural rubbers and synthetic rubbers having unsaturated bonds in the main chain, examples of which include IIR (inlatene-isobrene rubber), CIIR (chloro-inopten-isoderene rubber), and BIIR (promo-isobutene-isobrene rubber). ), BR (butadiene rubber), S
BR (styrene-butazoendem), IR (synthetic isoprene rubber), BIR (butanoene-isoprene rubber),
EPR (ethylene-propylene rubber), EPDM (ethylene-propylene-diene rubber), tolyl in NBR
! (tanoene rubber), NCR (tolyl-chlorograne rubber), NIR (tolyl-isoprene rubber), NR (natural rubber), ABR (acrylate-!tazoene rubber), PB
R (pyridine-butadiene rubber), PSBR (pyridine-styrene notazoene rubber), 5Ca (styrene-
Mixed rubbers of these rubbers, such as S
BR/NR (50/50), guanyl rubber/para rubber (20/80), IR/hydrogenated BR (33/67)
), EPDM/B P (60/40), CHR/B
HR (35/65) and the like are also preferably used.

Among these, IIR% CIIR, BIIR, SBR, and BR are particularly useful as synthetic rubbers synthesized by solution reaction.

IR, AIR%EPR%KPDM, POR, ECHR
, SR and their derivative polymers and blends are preferred, and as natural rubbers and synthetic rubbers obtained in the form of latex, NR%SBR%NBR, CR and their alligator conductors and blends are preferred.

The reinforcing agent mixed with the above-mentioned sub-elongated uncured rubber and pulverized may be any reinforcing agent as long as it suppresses or inhibits the adhesive interaction between rubber particles. Preferably, it is a compounding material to be compounded. Such reinforcing materials include carden black, silica, talc, various clays, zinc oxide, precipitated calcium carbonate/calcium silicate, pumice, tripoli, car random, titanium dioxide, zinc sulfide, iron oxide, and chalk.
Examples include various inorganic or organic materials such as carbonated limestone or crushed limestone), baryta, asphalt, phenolic resin, and ultramarindel, and one or more of these may be used. Among these, especially car? Zorac is preferably used.

The amount of these reinforcing agents used is not necessarily limited, but from the viewpoint of handling properties, economical pulverization efficiency, kneading processability, etc., it is preferably 10 to 300 parts by weight, particularly 10 to 60 parts by weight, per 100 parts by weight of porous uncured rubber. It is preferable to do so, and within this range, the object of the present invention can be effectively achieved.

In the present invention, the above-mentioned porous uncured comb has a bulk specific gravity of 0.01 to 0.7, preferably 0.1 to 0.5, which appears in the normal desolvation or drying process of raw rubber. The reinforcing agent is mixed with porous uncured rubber, and the uncured rubber is pulverized in the presence of the reinforcing agent to obtain granular rubber.

Thus, the granular rubber of the present invention can be produced by direct mechanical means without the intervention of emulsions or solutions, does not require latex formation or dissolution steps, and does not require working at low temperatures. Can be ground at room temperature.

In the method for producing granular combs of the present invention, as described above, the bulk specific gravity of 0.01 obtained by the usual solvent removal or drying process is as follows.
~0.7, preferably 0.1 to 0.5 porous uncured comb t - Comparison was made using the same rubber quality, the same comb amount, and the same equipment used as the raw rubber for pulverization. In this case, the crushing energy can be reduced by half compared to the case of crushing bale-shaped solid rubber, and the production capacity of granular rubber or powdered rubber can be doubled. In this case, the bulk specific gravity is 0.7
If the size is larger, the crushing energy will increase and the production will decrease, so that the object of the present invention will not be achieved.

t+, in the present invention, when crushing rubber, a filling reinforcing agent is mixed and coexisted, but in this case, more than a certain amount of reinforcing agent gold, for example, when Kagen black is used, more than 5% by weight is attached to the granular rubber. It is preferable to allow the rubber to coexist in a free state, so that the porous uncured rubber can be stably pulverized and stored.

Furthermore, in the present invention, when porous uncured rubber obtained after desolvation during the process or during the drying process is used as the raw material rubber for pulverization, the process is performed within 60 minutes, particularly after the rubber has been obtained and pulverized. Preferably, it is fed to the grinding process within 20 minutes together with the filling reinforcing agent which acts as an anti-adhesion agent. If the porous uncured rubber obtained after removing the solvent or during the drying process is left as it is, the porous rubbers will melt and solidify with each other due to their own weight or rubber flow, reducing the pulverization efficiency. There is.

The size of the granular comb is not particularly limited and can be determined freely, but the major diameter is usually set in consideration of handling, economical pulverization, and kneading processability for the next process. It is appropriate to crush it into pieces of about 0.2 to 20 m.

Although the pulverization conditions and the pulverization device are not necessarily limited, the pulverization temperature may be room temperature, and sufficient pulverization can be performed using a small-sized pulverizer such as a horizontal twin-shaft continuous screw type. In this case, the present invention does not require a special cooling device, and the pulverized material may be simply cooled by the amount of air sucked into the raw material during pulverization.

In the granular rubber obtained by the method of the present invention, the filled reinforcing agent that acts as an anti-adhesive agent forms an orderly anti-adhesive layer (filled reinforcing agent layer) on the surface of the uncured rubber, achieving substantial adhesion prevention. This produces a granular rubber that is free-flowing and non-cohesive on a macroscopic scale. In this case, as mentioned above, it is preferable that there is a free filler that is not attached to the rubber particles.

The granular rubber thus obtained can be mixed with a conventional compound to form a rubber composition, which is then vulcanized under conventional conditions to produce a product.

Effects of the Invention The method for producing granular rubber of the present invention has a bulk specific gravity of 0.01 to 0.
．． According to the present invention, it is possible to produce granular rubber gold efficiently and inexpensively with low crushing energy and high quality. can do. In this case, the equipment used for this rubber crushing is not special, and no special cooling device is required, and sufficient cooling can be achieved by simply cooling the crushed material with the amount of air sucked into the raw material during crushing.

In addition, the granular rubber obtained by the method of the present invention does not generate heat during crushing, does not deteriorate in quality due to partial dulling due to thermal history, has excellent kneading and dispersibility, and has excellent processability and The processed rubber quality is excellent.

Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to the following examples.

[Example 1, Comparative Example 1] Using IIR (IIR268 manufactured by Nippon Butyl Co., Ltd.) and carbon black (indicated by the symbol in the table), a car & n! Mix the coriander and lily, crush and then. In addition, as Comparative Example 1, conventional method veil-shaped Go A (I [450 m.

Pulverization was performed from pieces (length: 780 g, height: 80 to 120 m, weight per piece: 38 kg). The crushing conditions and reinforcing agent compounding conditions are shown in Table 1.

Table 1 The above compound was pulverized using a horizontal twin-shaft continuous screw type pulverizer, and a fixed amount of rubber and reinforcing agent were continuously introduced into the pulverizer. Further, the blending and pulverization of the comb and reinforcing agent were carried out at room temperature.Next, the energy and production capacity required for the pulverization of the two were compared and the results are shown in Table 2.

Table 2 As can be seen from Table 2, compared to the conventional method (starting from baled plum), the method of the present invention requires fewer pulverizing steps, significantly reduces the required amount of pulverizing energy, and has a pulverizing equipment. Production capacity will increase significantly. Therefore, it is understood from this that the method of the present invention is an inexpensive and highly efficient method for producing granular rubber.

[Example 2, Comparative Example 2] SBR rubber (5IRiso manufactured by Japan Synthetic Rubber Co., Ltd.) was used as the rubber.
o) The test was conducted in the same manner as in Example 1 and Comparative Example 1 except that -6 was used. The results are shown in Table 3.

Table 3 It can also be seen from Table 3 that the method of the present invention is an inexpensive and highly efficient method for producing granular rubber.

Next, a processed rubber was produced from a cured rubber composition using the granular rubber obtained by the method of the present invention, and its physical properties were examined and the results are shown as a reference example.

[Reference example]

Depending on the formulation and conditions shown below, a cured rubber composition using granular rubber according to the method of the present invention and a conventional veil rubber composition were prepared.
-Processed rubber (slab sheet) from directly used rubber composition
The next step is to manufacture the material and investigate its physical properties.

The results are shown in Table 4.

Blend 1R268100 parts by weight Carrying plastic (GPF) 4ON spindle 1Ol zinc oxide
31 Vulcanization accelerator (DM)
1 #Sulfur 4N Conditions/Small Banbury kneading vulcanization conditions: 170cXIO min, f-less vulcanization No. 4
As shown in Table 4, when using the granular rubber according to the method of the present invention, the total energy amount is approximately the same as when using the conventional bale-shaped rubber that is kneaded at Banbury. It is found that the kneading and dispersion effect is improved and the quality of the kneaded rubber is improved.

Claims (1)

[Claims] 1. A method for producing granular rubber, which comprises pulverizing porous uncured rubber having a bulk specific gravity of 0.01 to 0.7 in the coexistence of a filling reinforcing agent.