JP2901293B2 - Method for producing olefin rubber solution - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a rubber solution. More specifically, the present invention relates to a method for inexpensively producing an olefin-based rubber solution by introducing an olefin-based rubber in the form of fine particles into a solvent and dissolving it in a short time.

[Prior Art] In producing a rubber solution, rubber is cut into a suitable size, put into a solvent, and stirred and dissolved. Further, when rubber is dissolved on an industrial scale, if the rubber is poured into a solvent in a lump state, it takes a long time to dissolve the rubber, which increases the cost. Therefore, in order to dissolve quickly, it is desirable to powder the rubber in advance and increase the surface area, but since rubber generally has tackiness,
It cannot be easily pulverized on an industrial scale. For example, when rubber is mechanically pulverized, the heat generated at the time of pulverization raises the temperature of the rubber, and as a result, the tackiness of the rubber increases, and once the pulverized rubber is reagglomerated, usually a lump rather than a powder is obtained. Can be

In order to solve such problems, a method of performing low-temperature pulverization or freeze-pulverization using a refrigerant such as liquid nitrogen when mechanically pulverizing rubber has been used. However, when this method is carried out industrially, there is a drawback that the cost of equipment is increased due to the increase in size and complexity of the crushing device and accessory equipment.

Also, when mechanically pulverizing rubber, a method of coexisting liquids such as water and alcohol, performing pulverization under conditions where these liquids can evaporate, and removing generated heat as heat of vaporization of the liquid has been proposed. (Japanese Patent Publication Nos. 38-630 and 40-3524). As described above, the method using the heat of vaporization such as water or alcohol is essentially an idea of treating rubber at a low temperature. In this method, if the coexistence amount of the liquid is insufficient, it is inevitable that a part of the powder is re-agglomerated. On the other hand, if the amount of the liquid is excessive, there is a problem that a liquid removing step is required. .

Further, a method has been proposed in which an olefin-based copolymer rubber is mechanically pulverized in the presence of an aqueous dispersion containing a polyolefin such as polyethylene wax as a main solid content (JP-A-5959 / 1984).
-159831). In this method, the temperature rise is prevented by the heat of vaporization of water, and the surface of the rubber powder is coated with polyolefin to prevent re-agglomeration, but a step of removing excess water is required or unnecessary. When a rubber solution is produced as a result of the incorporation of polyolefin, there is a problem that the solution becomes turbid depending on the type of solvent.

Further, a method using an anti-adhesive such as carbon black, zinc oxide, and calcium carbonate has also been proposed (U.S. Pat. No. 3,623,703), but as in the above case, as an anti-adhesive used for dissolving rubber. Due to the carbon black and the like, the solution becomes turbid, and a step for filtering the solution becomes necessary.

Furthermore, a method has been proposed in which rubber or vulcanized rubber is pulverized by simultaneously applying different pressures and shearing forces, and the treatment at that time is performed under a cycle of heating at 80 to 250 ° C and cooling at 15 to 60 ° C. (JP-A-61-154910). The major feature of this method is that it crushes by applying a shearing force under a temperature cycle from heating to cooling.However, depending on the type of rubber such as butyl rubber, it is recommended that the crushing process be performed in the presence of polyethylene additives. doing. According to the examples of the publication, the rubber which is pulverized without adding polyethylene is waste rubber or product rubber of diene rubber such as polyisoprene, natural rubber, chloroprene rubber, butadiene-styrene rubber, and the like. In all olefin rubbers such as butyl rubber shown in Examples, polyethylene (known as an anticoagulant) is added. According to the results of additional tests by the present inventors, vulcanized natural rubber and SBR (butadiene-styrene rubber) could be powdered. However, when olefin rubber such as polyisobutylene was pulverized without adding polyethylene, cooling was performed. Reagglomeration occurred during the cycle and no powder was obtained.

[Problems to be Solved by the Invention] In a situation where a pulverization method as a means for rapidly dissolving the rubber is in such a situation, the present inventors have performed refrigeration treatment of an olefin rubber, addition of water or alcohol, and carbon black. Without adding inorganic anti-adhesives such as etc. or adding anti-agglomeration agents such as polyethylene, etc. An object of the present invention is to produce a solution of a system rubber.

[Means for Solving the Problems] In order to solve the above problems, the present inventors have conducted intensive studies, and as a result, have found the following surprising matters.

That is, even if an olefin-based rubber is crushed by applying a shearing force with a kneader or the like, the olefin-based rubber usually does not become powder but remains in a lump. However, while the olefin rubber is in a heated state while a shear force is being applied in the kneader, it is in a powdery state, but in the process of cooling it, reagglomeration occurs regardless of the presence or absence of the shear force. And found the fact that it returned to a lump, based on which the present invention was completed.

That is, in the present invention, in producing a solution of an olefin-based rubber, first, a heated olefin-based rubber is pulverized by applying a shearing force with a kneader or the like to form a powder, and then, while the powder is hot, or The present invention relates to a method for producing an olefin rubber solution, wherein the powder is cooled in a state where the particles do not come into contact with each other, and then the powder is introduced into a solvent for dissolving an olefin rubber and dissolved.

The olefin rubber shown in the present invention includes polyisobutylene, isobutylene-isoprene copolymer rubber (butyl rubber: IIR), ethylene-propylene rubber (EPM), ethylene-propylene terpolymer (EPDM), acrylic rubber (ACM), acrylic rubber Acid ester-acrylonitrile copolymer rubber (ANM), chlorosulfonated polyethylene rubber (C
Vulcanized and unvulcanized olefinic rubbers and elastomers such as SM) and fluororubbers. In the present invention, as long as it can be dissolved in a solvent, vulcanized olefin-based rubber can be used irrespective of whether it is unvulcanized, but particularly unvulcanized products, further, polyisobutylene, butyl rubber and the like It is particularly effective when an unvulcanized isobutylene homopolymer or copolymer is dissolved to produce a rubber solution. An appropriate additive may be added to the olefin rubber as long as its physical properties are not impaired.

As the solvent for dissolving an olefin rubber in the method of the present invention (hereinafter simply referred to as “solvent”), any solvent generally used as a solvent for rubber can be used. For example, rubber volatiles, natural or synthetic aliphatic, alicyclic or aromatic hydrocarbon oils such as toluene and asphalt,
Mixtures thereof, polymerized oils such as polybutene, ketones such as methyl ethyl ketone (MEK), ethers such as isopropyl ether and the like can be used.

To carry out the process according to the invention, use can be made of kneaders, Banbury mixers or customary single- or twin-screw kneaders which give shear to the rubber. For example, 10 pressure-type kneaders are used, and 6 to 7 kg, preferably about 7 kg, of the olefin rubber to be ground is supplied thereto. The shearing force applied by the kneader is not particularly limited as long as the rubber can be sheared.
That is, the conditions may be the same as those used when kneading or kneading rubber using a normal pressure-type kneader. The temperature at the time of pulverization by a kneader or the like and at the time of introduction into the solvent or at the start of cooling is in the range of 100 ° C to 200 ° C, preferably
80 ° C. If the temperature is lower than 100 ° C., reagglomeration of the powder occurs and it is difficult to obtain a fine powder. On the other hand, if the temperature exceeds 200 ° C., the rubber deteriorates, which is not preferable.
As for the heating, both the kneader and the rubber may be heated to a predetermined temperature before charging the olefin rubber, or the olefin rubber may be charged into the kneader and then heated to the predetermined temperature. The pulverization time by a kneader or the like is preferably 20 minutes to 60 minutes after adjusting to a predetermined temperature. If the pulverization time is shorter than 20 minutes, the pulverization is insufficient, and if the pulverization time exceeds 60 minutes, the particle size of the powder hardly changes, which is uneconomical.

It is important that after the pulverization, the powdered olefin rubber is taken out without cooling the kneader while maintaining the temperature at the time of the pulverization. If the powder is cooled before being charged into the solvent, reagglomeration occurs and the powder again becomes agglomerated. Therefore, the powder is directly charged into the solvent while being hot and dissolved to form an olefin rubber solution. Alternatively, the hot powder particles removed from the kneader may be cooled in a state where they do not come into contact with each other before being charged into the solvent.

[Examples] Next, the present invention will be described in more detail with reference to Examples.
Prior to the examples, the conditions for pulverization in the reference example will be described.

Reference Example 1 A polyisobutylene [L-120, manufactured by Exxon Chemical Co., Ltd., L-120, viscosity average molecular weight 100,000 (Staudinger)] was added to 10 preheated pressure kneaders [MS pressurized kneader manufactured by Moriyama Seisakusho] 7.0. kg was charged, the temperature was adjusted to 180 ° C., and the mixture was pulverized by applying a shearing force for 30 minutes. After the pulverization was completed, the mixture was directly poured into a water-alcohol 1: 1 (volume ratio) mixed solution 20 from the outlet of the kneader without cooling, to obtain a dispersion. This dispersion was stirred well, a part was extracted, and the particle size distribution was measured. Table 1 shows the results.

The method of measuring the particle size distribution is to separate the dispersed particles with a standard sieve,
After drying, a method of weighing was used. As a result, the particle size is 3m
36% by weight of fine powder of m or less, 38
By weight, large particles having a particle size of 9 to 13 mm were obtained in a proportion of 26% by weight.

Reference Example 2 The same treatment as in Reference Example 1 was carried out with a charged amount of 7.2 kg and a pulverization temperature of 150 ° C. Table 1 shows the results. That is, 49% by weight of fine powder having a particle diameter of 3 mm or less was obtained, which was about half.

Reference Example 3 The same treatment as in Reference Example 1 was performed with the charged amount of 6.6 kg and the pulverization temperature of 120 ° C. Table 1 shows the results. In this reference example, although the number of large particles increased, a result almost similar to that of reference example 1 was obtained.

Reference Example 4 The same treatment as in Reference Example 1 was performed except that the charged amount was 6.8 kg, the pulverization temperature was 160 ° C., and the pulverization time was 80 minutes. Table 1 shows the results. That is, the result was almost the same as that of Reference Example 1 even after grinding for 80 minutes.

Example 1 Polyisobutylene [L-120, viscosity average molecular weight 100,000 (Staudinger)] in 10 pre-heated pressure-type kneaders (manufactured by Moriyama Seisakusho, MS type pressure-type kneader) 7.2 kg was charged, the temperature was adjusted to 150 ° C., and the mixture was pulverized by applying a shearing force for 30 minutes. Obtained particle size 3m
m without cooling polyisobutylene fine powder below m
352.8 kg of polybutene (manufactured by Nippon Petrochemical Co., Ltd., HV-300, average molecular weight 1,350, kinematic viscosity at 40 ° C. 280 Stokes) is directly charged from the outlet of the kneader (weight ratio of polybutene / polyisobutylene: 98). / 2), and heated and stirred at 170 ° C. As a result, as shown in FIG. 1, the solution was dissolved in about 15 hours, and a colorless and transparent rubber solution having a viscosity of 270 centipoise was obtained.

Comparative Example 1 An inorganic anticoagulant was added to the polyisobutylene used in Example 1 and sheared to about 2 mm square, and the same polybutene used in Example 1 was introduced at the same ratio as in Example 1. And
After heating and stirring at 170 ° C., as shown in FIG. 1, it took about 22 hours for the viscosity to reach 270 centipoise. The solution was gray and opaque.

Comparative Example 2 When the pulverization of Example 1 was carried out at room temperature, polyisobutylene was agglomerated and could not be pulverized, and the lump had to be broken off by hand and put into polybutene.

[Effects of the Invention] In producing a rubber solution in which an olefin rubber is dissolved by the method of the present invention, a freezing treatment, addition of water or alcohols, addition of an inorganic anti-adhesive such as carbon black or polyethylene or the like is used. The olefin-based rubber is easily pulverized with ordinary equipment without adding an anti-agglomerating agent, etc., and the powder is directly poured into a solvent, or the powder is cooled in a state where the powder particles do not contact each other, and then the solvent is removed. By introducing the rubber into the inside, the olefin rubber can be rapidly dissolved, and a pure rubber solution free from turbidity and foreign matters can be produced at low cost.

[Brief description of the drawings]

FIG. 1 is a graph showing the dissolution rate when producing a rubber solution.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C08J 3/11-3/16

Claims (4)

(57) [Claims] The method comprises the steps of: applying a shearing force to a heated olefin-based rubber to pulverize the heated olefin-based rubber into a powder; then cooling the powder while the powder is hot or in a state where particles of the powder are not in contact with each other. A method for producing an olefin-based rubber solution, wherein the olefin-based rubber solution is dissolved by being introduced into a solvent for dissolving rubber. 2. The method for producing an olefin rubber solution according to claim 1, wherein the olefin rubber is a homopolymer or a copolymer of isobutylene. 3. The method for producing an olefin rubber solution according to claim 1, wherein the temperature at the time of pulverizing the olefin rubber, charging the olefin rubber into a solvent, or starting cooling is in the range of 100 ° C. to 200 ° C. 4. The method for producing an olefin rubber solution according to claim 1, wherein the pulverization is performed by applying a shearing force by a kneader or a Banbury mixer.