JPS5840577B2 - Dung pine rubber tree - Google Patents

Description

Detailed Description of the Invention A mixture of rubber latex, oil emulsion and carbon black water slurry is coagulated with acid, dehydrated and dried to obtain a block-shaped rubber, which is then pressed to form a bale-shaped polyethylene film, etc. The method of packaging and commercializing the product has already been implemented industrially.

In such a method, the rubber sticks during dehydration and drying, causing block formation, and in order to further form blocks during storage and transportation, a method is used in which the rubber is wrapped in a bale shape with polyethylene film, etc. -ing

When such bale-shaped rubber is used in a rubber processing factory such as a tire manufacturing factory, the bale must be shredded for purposes such as automatic metering of rubber.

Therefore, if this type of rubber were to be supplied in the form of powdered rubber, it would not only eliminate the trouble of shredding in rubber processing factories and facilitate automatic weighing, but also prevent powdered rubber from containing sulfur and aging. vulcanization accelerators, vulcanization accelerators, and other rubber compounding agents can be triblended and directly connected after extrusion.
Powderization of raw rubber has great industrial significance because it makes it possible to significantly shorten the manufacturing process of rubber products.

The present inventors have conducted various studies on a method for advantageously producing powdered rubber from a mixture of rubber latex and carbon black water slurry, and if necessary, a suitable oil is added thereto.

As a result, it was found that there are significant differences in the blocking properties of powdered rubber depending on the type of emulsifier contained in the rubber latex.

Furthermore, in the case of rubber latex containing carbon black, various new findings have been discovered, including the fact that there is a significant difference in the blockability of powdered rubber depending on the coagulation method.

The present invention was completed based on this knowledge.

That is, the present invention mixes an emulsifier-containing rubber latex mainly composed of carphonate soap and a carbon black water slurry, and adds acid to this mixture to form a fine mixture containing rubber and carbon black (hereinafter referred to as "crumb"). That's what it means.

) is coagulated, a carbon black aqueous slurry containing an emulsifier is added to the crumb, the crumb is treated under acidic conditions, and the treated crumb thus obtained is separated from the coagulated mother liquor and dried. This is the manufacturing method.

Conventionally, methods for powderizing rubber include methods such as immersing granular rubber in an aqueous resin dispersion, or spraying the aqueous resin dispersion onto the granular rubber, and then drying the granular rubber.
(See Publication No. 9-11460).

However, when this powdering method is applied to coagulated products from rubber latex and carbon black water slurry, blocks are likely to occur during the drying process, and even if the blocked products are forcibly powdered, they cannot be stored. It is easily formed into blocks, and its storage properties are almost the same as those without resin treatment.

In addition, after coagulating the rubber latex, a small amount of hard polymer latex such as polyvinyl chloride or polystyrene is added to it, and the hard polymer is coagulated on the surface of the first coagulated product.
A method of producing powdered rubber by washing with water and drying is already known.

(Refer to Japanese Patent Publication No. 46-13626).

However, applying this powdering method to a coagulum from rubber latex and carbon black water slurry does not produce good powdered rubber.

The present inventors have learned that the selection of an emulsifier in rubber latex, the coexistence of carbon black, and the selection of a coagulant are important in producing powdered rubber.

That is, the emulsifier used in the rubber latex used in the present invention is limited to an emulsifier mainly composed of carboxylate soap.

When the latex is coagulated by an acid, the carboxylate soap is converted into free carboxylic acid, and this free carboxylic acid evenly coats the rubber powder, which helps prevent the rubber powder from forming into blocks.

If other emulsifiers are used as latex emulsifiers, such as higher alcohol sulfate salts, alkylbenzene sulfonate salts, nonionic surfactants, or cationic surfactants, the powdered rubber will be coated with free carboxylic acids. Not only is this not possible, but it also has the adverse effect of dispersing carbon black into the mother liquor, which is undesirable.

The carboxylate soap used for emulsifying rubber latex in the present invention refers to alkali metal salts, ammonium salts, etc. of compounds containing various carboxyl groups.

For example, carbon atoms derived from saturated or unsaturated carboxylic acid layers having 6 to 22 carbon atoms, rosin acid layers, disproportionated rosin acid layers, tall oil layers, and α-olefin-maleic anhydride copolymers. Examples thereof include acid oxides, carboxylic acid oxides derived from synchropentadiene-maleic anhydride reaction products, and the like.

"Mainly made of carboxylate soap" means that carboxylate soap alone can be used, but for the purpose of improving the stability of latex during polymerization, for example, This is because a mixture of a small amount of other auxiliary emulsifiers, such as a formalin condensate of sodium sulfonate, can also be effectively used, so the soap is not necessarily limited to carboxylic acid salt soaps.

The amount of carboxylate soap used in rubber latex is usually 2 to 15 weight φ, preferably 5 to 15% by weight, based on the rubber.
The amount of the other auxiliary emulsifiers used is 10% by weight or less based on the carboxylic acid salt soap.

If the amount of other auxiliary emulsifiers used is too large, the powdered rubber tends to become blocked, which is not preferable.

Furthermore, the rubber latex and carbon black water slurry mixture (this mixture may contain oil) in the present invention.

) is selectively used as a coagulant.

Salt coagulants such as aluminum sulfate and magnesium sulfate are also known as coagulants for rubber latex.
When a salt coagulant related to the rubber latex-carbon black system or rubber latex-oil-carbon black system in the present invention is used, not only does the powdered rubber become blocked, but the carbon black is not completely coagulated and the coagulation mother liquor Free carbon black remains in the solution, turning the mother liquor black and opaque, and requiring extra effort and cost to dispose of the waste solution.

As the acid coagulant used in the present invention, any of inorganic acids such as sulfuric acid, hydrochloric acid, and phosphoric acid, and organic acids such as acetic acid can be used.

The amount of acid coagulant used may be sufficient to bring the pH of the mixture into the acidic range, and is usually an amount that brings the pH to 1-6, preferably 3-5.

The rubber latex used in the present invention includes a monomer or monomer mixture such as butadiene, butadiene-styrene, butadiene-acrylonitrile, butadiene-isoprene, isoprene, chloroprene, etc., and an emulsifier mainly composed of the above-mentioned carboxylate soaps. It is a rubber latex obtained by emulsion polymerization using a rubber latex, and particularly preferred are butadiene rubber latex and butadiene-styrene copolymer rubber latex, which are used as general-purpose rubbers.

In some cases, natural rubber latex, a rubber solution obtained by a solution polymerization method, or a recovered solid rubber may be used as a raw material and re-emulsified in water with carboxylic acid salt soap or newly emulsified. Can be used as rubber latex.

As the carbon black aqueous slurry used in the present invention, aqueous slurries of various carbon blacks can be used.

As a method for turning carbon black into a water slurry, it is preferable to disperse carbon black as fine particles as uniformly as possible in water using a colloid mill, a centrifugal pump, or the like.

The slurry concentration is 4 to 15%, preferably 6 to 10%.
% is selected.

The mixing ratio of the carbon black water slurry to the rubber latex is 30 to 100 parts by weight of carbon black per 100 parts by weight of rubber.

In the present invention, it is preferable to further mix oil appropriately into the rubber latex and carbon black water slurry mixture.

Such oils are preferably aromatic oils, naphthic oils, paraffin oils, etc., which are normally used as rubber extender oils, and are added in an amount of 70 parts by weight or less per 100 parts by weight of rubber.

Preferably, the oil is added to the rubber latex as an aqueous emulsion using a carboxylate soap.

If an acid serum solidifying agent is added to the thus obtained mixture of rubber latex and carbon black water slurry (in some cases, oil may be further added) to make the pH of the mixture acidic (for example, pH 3 to 5), The rubber, carbon black, and optionally added oil coagulate as fine particles or crumbs of the mixture.

The size of the crumb particles is 5 pairs or less, preferably about 171 m or less.

The powdered rubber obtained by the manufacturing method of the present invention has a particle size of this order.

The crumb obtained by coagulating as described above is then added to a carbon black water slurry containing an emulsifier (hereinafter referred to as
This is called "carbon black emulsion."

) and treated under acidic conditions.

In this treatment, the carbon black emulsion may be directly added to the acidic coagulated slurry liquid (first stage coagulated slurry liquid) obtained by acid coagulating the rubber latex and carbon black water slurry mixture. Alternatively, a method may be used in which the first-stage coagulated slurry liquid is once filtered to remove crumbs, the carbon black emulsion is added to the crumbs, and then an acid is separately added.

The carbon black emulsion is a carbon black water slurry similar to that used in producing the above-mentioned crumb containing an appropriate emulsifier.

Such emulsifiers include, for example, carboxylate soaps,
Higher alcohol sulfate salts, alkyl phosphate salts, alkylbenzene sulfonates, alkylnaphthalene sulfonates, naphthalene sulfonate formalin condensates, dialkyl sulfosuccinates, polyoxyethylene sulfate salts, and the like are used.

As the carboxylate soap, those used as emulsifiers for the above-mentioned rubber latex can be used.

Examples of higher alcohol sulfate ester salts include sodium lauryl sulfate, sodium lauryl sulfate, potassium polyoxyethylene alkyl ether sulfate, potassium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate, potassium sulfate, and the like. .

Examples of alkyl phosphate salts include dialkyl phosphates, dipolyoxyethylene alkyl phosphates, and dipolyoxyethylene alkyl phenyl ether phosphates.

Examples of alkylbenzene sulfonates include sodium and potassium dodecylbenzene sulfonate; examples of dialkyl sulfosuccinates include sodium and potassium dioctyl sulfosuccinate; examples of polyoxyethylene sulfate salts include sodium polyoxyethylene alkyl ether sulfonate; Examples include potassium chloride, sodium polyoxyethylene phenyl ether sulfate, potassium chloride, and the like.

Such a carbon black emulsion contains an emulsifier in the emulsion of 0.5 to 20 parts per 100 parts of rubber,
The carbon black in the emulsion is preferably added to the crumb in an amount of 0.5 to 10 parts, and in an amount of 1 to 20 parts, preferably 2 to 10 parts, per 100 parts of rubber.

If there is too much emulsifier, carboxylate soap etc. will remain in the powdered rubber, which is undesirable as it will cause slippage during rubber processing. Also, if there is too much carbon black, the crumb surface will remain in the processing mother liquor. Free carbon black that has not been adsorbed and coated will remain, which is undesirable because it will cause work contamination.

Note that if the amount of emulsifier or carbon black added is too small, the effects of the present invention cannot be fully exhibited.

When crumb is treated with a carbon black emulsion under acidic conditions according to the present invention, the emulsifier coagulates and is adsorbed and coated on the crumb surface, and at the same time, coexisting fine particles of carbon black are sucked into the coagulated emulsifier and the crumb surface It is thought that this effectively prevents the stickiness of

This is also supported by the following phenomenon.

In other words, depending on the method of simply spraying or dipping carbon black emulsion on the crumb, not only is it not effective in preventing stickiness, but the uncoagulated emulsifier remains, causing many problems in terms of product quality. .

Thus, the treated crumb treated with the carbon black emulsion is post-treated by the usual means such as filtration, washing with water, and further filtration, and then dried to become a powdered rubber product.

Since this powdered rubber is free from blocking during drying, highly efficient drying methods such as powder fluidized drying and flash drying can be used for drying.

The powdered rubber product is compressed by the mold of the powdered rubber during its storage and transportation, but the powdered rubber product of the present invention is free from the risk of forming into blocks even when compressed during storage and transportation.

Next, examples and reference examples will be given and explained.

In these examples, unless otherwise noted,
Parts by weight and parts by weight.

Further, in these examples, the testing (measurement) of blocking of the powdered rubber after drying was carried out by the following method.

Add 15> powdered rubber into a cylinder with an inner diameter of 3571gIl and get 0.25KI! After applying a load of /m and leaving it for 5 minutes, the load and cylinder were removed, weights of various weights were placed on the obtained powder rubber molding, and the block was The degree of change was evaluated.

In other words, the case where the shape collapses without applying any load is O11.
If the shape collapses when applying part 1ooy, 1, load 2
The same case of 00g was set as 2 (the same applies hereinafter).

Example l SBR latex (styrene/butadiene = 2 by weight)
3/77, the rubber content is 22.7 parts, the emulsifier is a mixed soap with a weight ratio of fatty acid soda/rosin acid soda = 1:1, and the emulsifier amount is 6.5 parts per 100 parts of the rubber content.

) 180 ml, carbon black (manufactured by Mitsubishi Chemical Industries, Ltd.,
50 ml of oil emulsion made by emulsifying 400 g of water slurry (carbon black content: 8 mounds) and 25 g of aroma oil with tall oil (trade name Diablack 5H)
was added to a 21-volume tank equipped with a stirrer, and after stirring for 3 minutes, 20 ml of a 5% aqueous sulfuric acid solution was added to form a rubber-oil-carbon black co-coagulate (crumb).

Carbon black 211 (5 parts per 100 parts of rubber) and KS soap (semi-cured tallow potash soap, KAO-ATLA) are added to the acidic coagulated mixture slurry containing the above crumb.
A carbon black emulsion prepared by emulsifying 0.4 g (1 part per 100 parts of rubber) of S Company with 20 m 11 of warm water was added and stirred for 30 minutes.

The treated crumb thus obtained was filtered, washed with water, and dried in a dryer at 80° C. for 3 hours to obtain powdered rubber.

The treated crumbs did not form blocks during drying.

The blocking property evaluation of the obtained powdered rubber was 1, indicating that it was an excellent powdered rubber.

For comparison, powdered rubber was produced in the same manner as in Example 1 except for using SBR latex containing sodium alkylbenzenesulfonate as an emulsifier for SBH. No powdered rubber was obtained.

Example 2 Instead of the SBR latex in Example 1, 0.26 sodium naphthalene sulfonate/formalin condensate was added to the fatty acid layer of the emulsifier based on 100 parts of rubber.
A powdered rubber was produced in the same manner as in Example 1 except that the emulsifier contained in the powdered rubber was used.

The obtained powder rubber had a blocking property evaluation of 2, indicating that it was an excellent powder rubber.

Reference Example 1 Powder rubber was produced in the same manner as in Example 1 except that a carbon black water slurry containing no emulsifier was used in the crumb treatment of Example 1. The resulting powder rubber had a blockability evaluation of 6. Ta.

Reference Example 2 Powdered rubber was produced in the same manner as in Example 1 except that a carbon black water slurry containing no emulsifier was used in the crumb treatment of Example 2. The resulting powdered rubber had a blockability evaluation of 8. Ta.

Examples 3 to 6 Powdered rubber was produced in the same manner as in Example 2, except that various carbon black emulsions listed in the table below were used in the crumb treatment of Example 2.

The blocking properties of each of the obtained powdered rubbers were evaluated as shown in the table below.

Reference Example 3 Instead of 20ml of the 5-kinju acid aqueous solution used in Example 2,
Powdered rubber was produced in the same manner as in Example 2 except that 12 mA of a 10φ aluminum sulfate aqueous solution was used.

The coagulation mother liquor after coagulating the rubber latex contains a considerable amount of free carbon black, which is therefore problematic in wastewater treatment.

Moreover, the blocking property evaluation of the obtained powdered rubber was 5.

Example 7 A carbon black water slurry (carbon black content: 8φ) containing 180 m7 of SBR latex (same as in Example 1) and 33 g of carbon black (same as in Example 1) was added to a tank of 21 equipped with a stirrer. After stirring for 3 minutes, 5 mA' of sulfuric acid aqueous solution was added to form a finely divided rubber-carbon black co-coagulate (oil-free crumb).

Thereafter, a carbon black emulsion prepared by emulsifying 2 g of carbon black and 0.4 g of KS Sorb in 20 ml of warm water was added and stirred for 30 minutes.

The treated crumb thus obtained was washed with water, filtered, and dried in a dryer at 80° C. for 3 hours to obtain powdered rubber.

The treated crumb did not form blocks even during the drying period, and the blockability evaluation of the obtained powdered rubber was 1.

Example 8 Polybucdiene rubber latex 174 produced by emulsion polymerization method
m1 (rubber content: 23 strips, emulsifier is a soap mixture of fatty acid soda and rosin acid soda, the amount of emulsifier is 8 parts per 100 parts of rubber) and 30 g of carbon black (product name: Diablack H1 Mitsubishi Chemical Industries, Ltd.) carbon black water slurry containing carbon black (8φ carbon black)
was added to a 21 tank equipped with a stirrer, and after stirring for 3 minutes, 15 ml of an aqueous sulfuric acid solution was added to solidify an oil-free crumb.

Next, carbon black 2. ! i' and KS soap 0.
4. ! A carbon black emulsion prepared by emulsifying No. 9 with 20 ml of warm water was added, and the mixture was stirred for 30 minutes.

The treated crumb thus obtained was washed with water, filtered, and dried in a dryer at 80° C. for 3 hours.

The treated crumb did not form blocks even during drying, and the obtained powdered rubber had a blockability rating of 1.

Example 9 Powder was prepared in the same manner as in Example 1, except that Emal 2F needle (sodium lauryl sulfate, manufactured by KAO-ATLAS) was used instead of KS Sorb as an emulsifier for carbon black emulsion preparation. manufactured rubber.

The treated crumb did not form blocks even during drying, and the obtained powdered rubber had a blockability evaluation of 3.

Claims (1)

[Claims] 1. Mixing an emulsifier-containing rubber latex mainly containing a carboxylic acid salt layer and a carbon black water slurry,
An acid is added to this mixture to coagulate a fine mixture containing rubber and carbon black (hereinafter referred to as "crumb"), and a carbon blank water slurry containing an emulsifier is added to the crumb, and the mixture is heated under acidic conditions. A method for producing powdered rubber, which comprises treating the powdered rubber with the following steps, separating the treated crumb thus obtained from the coagulation mother liquor, and drying it.