JPS5938206A - Prevention of coagulation of powdered rubber - Google Patents

Abstract

PURPOSE:To prevent coagulation of powdered rubber during storage and improve its fluidity, by treating a specified powdered rubber slurry with a fatty acid soap and polyaluminum chloride. CONSTITUTION:A mixture containing an anionic or nonionic latex of a rubber (e.g., isoprene rubber) and 0.1-10wt% anionic water-soluble polymer (e.g., sodium alginate) is added dropwise under agitation to an aqueuous acidic solution containing 0.1-10wt% cationic water-soluble polymer (e.g., polyvinylpyridine) or cationic surfactant capable of forming a coacervate with the anionic) water- soluble polymer, then 1-30wt% emulsion of a synthetic resin of a glass transition point >=30 deg.C (e.g., PS) is added, and the resulting mixture is agitated for at least 10min to obtain a powdered rubber slurry. To this slurry are added 0.2-3wt% 12-20C fatty acid soap (e.g., sodium stearate) and 0.1-3wt% polyaluminum chloride, and the mixture is dehydrated and dried.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for improving the cohesiveness of powdered rubber during storage. More specifically, rubber latex containing anionic water-soluble polymer is treated under acidic conditions.
The powder is stored in a powdered rubber slurry liquid that is added dropwise to a cationic water-soluble polymer or cationic surfactant aqueous solution, and then a synthetic resin emulsion is added to it, and then treated with fatty acid and polyaluminum chloride. The present invention relates to a method for producing powdered rubber that prevents rubber agglomeration and improves fluidity.

In recent years, with the advancement of rubber processing technology, pellet-like or powdered rubber that can be automatically weighed, continuously added, etc. is in high demand and attracting attention in the market for the purpose of saving labor and energy. ing.

Furthermore, with the expansion of its uses, rubber is often blended with various resins and is also used as a modifier for resins. Most resins, such as polyvinyl chloride, are in the form of powder or pellets, and therefore, the rubber used as the modifier is powder-like in consideration of mixability and dispersibility. It is desirable that Furthermore, various rubber latexes have been used as asphalt modifiers, but latexes have the disadvantage of requiring a large amount of energy to remove water.

Even in this case, there is almost no difference in dispersibility, and
There is an increasing demand for powdered rubber that does not require water removal.

However, due to its nature, rubber is sticky even at room temperature and has high elasticity, so even if it is made into pellets or powder, it will stick to each other during drying, storage, etc., and will become blocks in the form of lumps. This is normal.

For this reason, in order to obtain powdered rubber that does not stick to each other and form blocks, various studies have been made on methods thereof. General methods include physical methods, such as physically or mechanically crushing, and then adding an anti-agglomerating agent such as calcium carbonate or talc, and using coagulating agents for rubber latex such as polyvalent metal salts. There are two chemical methods in which the rubber is separated into a powder and then isolated.

In the former method, it is difficult to obtain powdered rubber with small particle size and uniformity due to the heat generation of the rubber during crushing, and the throughput is also limited. Furthermore, it has the disadvantage that an anti-agglomerating agent in Issue 88 is required to prevent agglomeration of the powdered rubber. On the other hand, in the latter case, powder gono medium f' 4 'F
A-1 [This is disadvantageous because salt is mixed in and the stability of the powdered rubber is impaired.

Taking these points into consideration, the present inventors conducted various tests regarding the method of powderizing rubber, and as a result, they found that 51
Application No. 148,732 of the year led to the invention of a method for producing powdered rubber essentially free of depressants.

According to this method, an anionic water-soluble polymer is mixed with rubber latex, and a cationic water-soluble polymer that causes coacervation under the anionic water-soluble polymer and 11 The rubber is separated into powder by dropping it into a polymer or cationic surfactant aqueous solution.
Next, a synthetic resin is added as an emulsion, followed by dehydration and drying to produce powdered rubber. It has been found, however, that the dry powder rubber thus obtained loses its fluidity during storage, especially storage under load, and has poor flowability. For example, if stored under no load in a constant temperature room at 23°C, there will be no change in fluidity and the powder form will remain unchanged even after several months;
When stored in 9 bags (equivalent to 8 bags), after 24 hours it becomes a castella-like block, loses fluidity, and cannot be returned to its original uniform particle size powder even if re-pulverized, making it difficult to store or transport powdered rubber. It has been found that this method is disadvantageous industrially because it must be carried out at low temperatures and must be packaged without any load.

Taking these points into consideration, the inventors of the present invention have conducted intensive studies to prevent the agglomeration of powdered rubber during storage, and have found that 9 in 20
It has improved fluidity, which is industrially advantageous, and can be stored or transported in the same way as conventional rubber, retaining its powder form even when packed in bags, under a load of 8 bags (approximately 489 rivers), and stored in the summer. This led to the invention of a method for producing powdered rubber.

In the present invention, a mixture of anionic and nonionic rubber latex and an anionic water-soluble polymer of f11 to 10% by weight based on the dry weight of the rubber latex is subjected to coacervation with the anionic water-soluble polymer under acidic conditions. The amount of cationic water-soluble polymer, or cationic surfactant, is 0.1 to 10% by weight per dry weight of rubber latex.
1 to 1 per dry weight of rubber latex as an emulsion with a synthetic resin.
Add 0.2 to 3 layers of fatty acid per dry weight of rubber latex to the powdered rubber slurry obtained by adding 50% by weight, and add 0.2 to 3 layers of fatty acid per dry weight of rubber latex, and add 1 to 2 layers of fat when drying the rubber latex. The powdered rubber is treated with polyaluminum chloride to prevent agglomeration of the powdered rubber during storage, and has improved fluidity without agglomeration even when stored under load. It is a violation of the law.

Polyaluminum chloride 11 in the present invention is an inorganic polymer having the Ifl formula (Az)n(oH)mcz3n-4, which has various degrees of polymerization, and is produced in duplicate (e.g. Manufactured by Toyo Soda Kogyo H, product name PA (
1) It is easily available.

In addition, polyvalent metal salts are used as coagulants for latex, including polyaluminum chloride! As seen in Kokai No. 53-137241, 1butC is used as a coagulant to separate rubber from rubber latex into powder, but the use of polyaluminum chloride in the present invention is essentially different from these. They are different.

That is, the polyaluminum chloride in the present invention is obtained by converting rubber latex into rubber powder ((1 part:!t L,
This is then used in the step of adding synthetic (.)1 fat to the powdered rubber slurry obtained as a emulsion, adding fat to the slurry, and treating this with polyaluminum chloride.

When polychlorinated alumina J is used as a coagulant for rubber, as in JP-A-53-1!57241, as seen in the specification, the fluidity of powdered rubber in a wet state containing water is maintained. However, in order to impart fluidity to the dried powdered rubber, it is desirable to add an anti-agglomerating agent such as 7 Lika or talc after dehydration in the furnace and before or during drying. There is no description regarding the fluidity of powdered rubber under λ'χ.

In the present invention, before adding polyaluminum chloride,
It is essential to add synthetic resin and fat, and by skipping these steps, it is possible to produce powdered rubber that is easy to dehydrate and dry, and whose fluidity does not change even when stored under load. It was a success. Simply adding polyaluminum chloride to an aqueous dispersion obtained by separating rubber into powder has no effect, and in such a case, when it is dehydrated under a load of 11 and 7 is added, it aggregates in a lump like rubber V. It cannot be obtained as powdered rubber.

As long as it can be obtained as the rubber site 1 anion or nonionic latex targeted in the present invention,
All can be used, including natural rubber (NR), polyisoprene rubber (NR), which is an independent polymer of conjugated diene compounds such as isoprene, butadiene, and chloroprene produced by conventional emulsion polymerization methods, and polybutene rubber. Jen Gom (BR).

Polychloroprene rubber ((!R), the above conjugated diene compound and styrene, acrylonitrile, vinyl vinyl IJ, /
Styrene butadiene rubber (SBT), which is a copolymer with vinyl compounds such as acrylic acid, methacrylic acid, alkyl acrylate, and alkyl methacrylate, acrylonitrile butadiene rubber (NBR), vinylpyridine butadiene styrene rubber, and acrylic f. Butadiene rubber, methyl acrylate butadiene rubber, methyl methacrylate butadiene rubber, etc., as well as ethylene, propylene.

Inbutylene isoprene rubber (AER), which is a copolymer of olefins such as inbutylene and a conjugated diene compound
There is a collar.

The anionic water-soluble molecules used in the present invention include natural products such as &J, sodium alginate, gum arabic, carrageenan, agar, and carboxylic acid), sodium cellulose, polyvinyl sulfonic acid, polystyrene sulfonic acid, acrylic acid/acrylic acid. There are synthetic products such as methyl copolymer, methacrylic acid/methyl methacrylate copolymer, crotonic acid/vinyl acetate copolymer, styrene/maleic acid copolymer, cellulose acetate phthalate, and starch acetate phthalate. ~10.1 V (-4), preferably used at a voltage of 1 to 5%, and mixed in the form of an aqueous solution.

The substances used in the present invention that cause coacervation with the 12-ionic water-soluble product molecules under acid+1 conditions are acidic substances such as polyvinylpyridine, polybenzylaminoethylcellulose, polydiethylaminoethylstyrene, and polyvinylbenzylamine. cationic water-soluble)
Clamp molecule, dodecyltrimethylamine, cetyltrimethylamine, stearyldimethylbenzylamine, dodecyldimethylbenzylamine, coconut alkyldimethylamine.

Hardened beef tallow alkyldimethylamine, polyethylene beef tallow alkylpropylene diamine, dodecyltriethanolamine, coconut alkylamine.

dodecylamine, tallow alkylamine, cetylamine,
Acetate salts of higher amines such as stearyl amine, hardened beef tallow alkyl amines, salts l1liθ salts, K I'/lj, dimethyl sulfate, nitric acid groups, cationic f-surfactants such as quaternary ammonium groups, etc. can be mentioned. These 0.
It is used in the form of an aqueous solution in an amount of 1 to 10 parts, preferably 1 to 5 parts.

In the present invention, first, a mixture of these rubber latex and anionic water-soluble polymer is mixed dropwise under acidic conditions into an aqueous solution of the substance that causes coacervation with the anionic water-soluble polymer. can be separated into powder form. In order to effectively perform powder separation, there is a suitable ratio of anionic water-soluble polymer and the substance that causes coacervation, but this can be easily determined through preliminary experiments. You can ask for it.

Powder separation can only occur under acidic conditions, and the mouth of the powder separation system must be kept acidic, preferably below 5. Acids used for this purpose include inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid, and organic acids such as acetic acid. It should be kept acidic.

This operation only requires mixing each solution with stirring, and can be easily and well controlled.
Immediately grind into powder for 1 iiF- minutes.

In this case, it is affected by the water iA or Ll stirring strength in the solution, but it is not an important factor, and the suitable amount of water or stirring strength can be easily determined in each case by conducting preliminary experiments in advance. can be determined.

The powdered rubber obtained at this stage can be easily separated and washed by using a cotton cloth, but if it is dehydrated under load, it tends to form into blocks after dehydration, leaving the rubber in a powder state. It will be difficult to obtain it.

In the present invention, this problem is solved by adding synthetic resin as an emulsion. By adsorbing the synthetic resin to the surface of powdered rubber particles, viscosity Y1 between rubber particles is prevented and fluidity is improved. Can be made into wet powder rubber.

The synthetic resin emulsion used herein refers to an emulsion in which synthetic resin particles having a glass transition temperature of 30° C. or higher are dispersed in an aqueous medium. Such synthetic resin emulsions include polystyrene emulsion, polymethyl methacrylate emulsion, methyl methacrylate/methyl acrylate copolymer emulsion, polyvinyl chloride emulsion, vinyl chloride/vinylidene chloride copolymer emulsion, polyvinyl acetate emulsion,
Styrene/acrylonitrile copolymer emulsion, styrene/itaconic acid copolymer emulsion, styrene/acrylonitrile copolymer emulsion,
Examples include methyl methacrylate copolymer emulsion, styrene/vinyl chloride copolymer emulsion, and fluororesin emulsion such as polyvinyl fluoride and polychlorotrifluoroethylene.

These synthetic resin emulsions have a dry weight of 1 to 30 'ji for the dry type M of rubber latex.
j is added in an amount of 1%, preferably 2 to 15% by weight more than t. If the amount of synthetic resin is less than 1% by weight, it will be difficult to obtain a sufficient effect, and there will be a tendency for blocks to form.
It is not preferable because the rubber properties are impaired.

In order to sufficiently adsorb the synthetic resin particles onto the surface of the powdered rubber particles, it is necessary to thoroughly mix the mixture after adding the synthetic resin emulsion, but stirring for 10 minutes or more is sufficient. Furthermore, for the purpose of rapid and more sufficient adsorption, inorganic type 1 solutes such as sodium chloride, potassium chloride, sodium sulfate, calcium chloride, magnesium sulfate, zinc sulfate, aluminum chloride, etc.
Lower alcohols such as methanol and ethanol, acetone, etc. may be added. With these additives, ↓ powder rubber V
It can be easily removed by washing with water after isolation using a suitable method, and is not contained in the final powdered rubber.

Next, it is easily dehydrated using a centrifuge or the like, but at this point it does not stick to each other and form blocks, and is fluid or wet enough to be easily crushed by a light crushing operation. A powdered rubber is obtained. Furthermore, it is possible to obtain a free-flowing dry powder rubber with a diameter of about 2 mm or less by fluidized drying, etc. However, such powder rubber can be made into a dry powder rubber with a load of 1-(
It was found that when stored at 35°C at a temperature of about 489/c, IIt), it formed into a castella-like block after 24 hours.

Even after these tri-pulverizations, the original powdered rubber does not return to its original form, making it difficult to use as an old powdered rubber material and being industrially disadvantageous.

In order to improve this point, as a result of intensive research, I decided to self-discipline (
6J fat emulsion/p
Hf: By adding fatty acid and polyaluminum chloride while maintaining the acidity, it was possible to successfully produce a powdered rubber that does not coagulate with each other when stored under load.

The fat weight stone used here has a carbon number of 12 to 2.
Sodium salts, potassium salts, etc. of fatty acids having 0 and lauric acid as a fatty acid.

Myristic acid, valmitic acid, stearic acid, oleic acid, linoleic acid, lylinic acid, etc. are used in an amount of 0.2 to 3% by weight, preferably α5 to 2% by weight based on the dry weight of the rubber latex. used. It is preferable to use Fatty Stones in the form of an aqueous solution, but some types of Fatty Stones have limited solubility in water.
In this case, it is desirable to raise the temperature of the powdered rubber slurry to the melting temperature of the 7In fatty acid soap in order to quickly and uniformly disperse the fatty acid soap. These temperatures can be easily found from literature.

Polyaluminum chloride may be added immediately or in parallel with the addition of these fatty acid sulfates, but considering that the aqueous fatty sulfuric acid solution is essentially alkaline, the pH of the powdered rubber slurry should be made acidic. For the purpose of maintaining, geoacid, sulfuric acid.

Even if polyaluminum chloride is added after neutralization with an inorganic acid such as nitric acid, an organic acid such as acetic acid, or a polyvalent metal salt such as calcium chloride, barium sulfate, zinc chloride, or magnesium chloride. good. The polyaluminum chloride used here is 90.1 to 5% by weight per dry weight of rubber latex.
It is used preferably in the range of 0.2 to 1 weight.

In the present invention, both of these are necessary components, and when the fatty acid is less than 0.2i and polyaluminum chloride is added, or when treated with only the fatty acid, dry Although it is possible to have a free-flowing powdered rubber, it is not possible to prevent the powdered rubber from agglomerating during storage under load. In addition, using more than 5 weights of fatty acid lime and polyaluminum chloride more than 3 times the weight may cause a delay in vulcanization of the rubber or may result in poor stability of the rubber. This is not preferable because it impairs the properties of the rubber.

The powdered rubber slurry thus obtained can be easily dehydrated using a centrifuge or the like to obtain a wet powdered rubber that is fluid or can be easily crumbled by hand. Then,
The drying method is not particularly limited, and methods such as ventilation drying, hot air drying, vacuum drying, and fluidized drying can be freely selected and used.

The present invention is a method for producing powdered rubber that does not agglomerate during storage under load, having the above-mentioned structure. It can be manufactured efficiently and quickly.

The cohesiveness of the powdered rubber under load according to the present invention is approximately 1509 to 4I (, 4ih, Ka 60 sns
, filled into a box with a depth of 70 kg, and this [20 kg bag,
The force equivalent to the cart exerted on the bottom K of 8 bags loaded, 482/7
The rubber was stored at 35° C. for 24 hours under a load of 100.degree. C., and then taken out from the box and evaluated based on the force with which it was broken into powdered rubber and the particle size of the powdered rubber before storage.

Examples are shown below.d;1. However, it is not limited to this.

Unless otherwise stated in the examples, parts and percentages refer to the heavy phase.

Rubber latex and synthetic resin emulsion (A) used in Examples Polychloroprene rubber latex (abbreviated as cR) Rosin potassium soap 4.0 parts, caustic soda 0 in a nitrogen stream
．． 0.4 parts of a condensate of 4 parts formaldehyde and sodium naphthalene sulfonate are dissolved in 100 parts of water, and then!
1-dodecylmercaptan [], 22 parts 2.6-di-t
-Butyl-p-cresol (0.1 part) was emulsified by adding chlorobrene, and at 40°C, the excess value "1
Polymerization was carried out while dropping the aqueous solution. The polymerization was stopped at a conversion rate of 70%, and unreacted chloroprene was distilled off to obtain a polychloroprene rubber latex with a dry weight of 65 inches.

(B) Acrylonitrile-butadiene rubber latex (abbreviated as NBR) High-acrylonitrile-butadiene rubber latex (trade name: N1po, 1571) manufactured by Nippon Zeon Co., Ltd. was adjusted to have a dry weight of 35%.

(C) Polybutadiene rubber latex (abbreviated as BR) Polybutadiene rubber latex (trade name: JSRO700) manufactured by Japan Synthetic Rubber Co., Ltd. was adjusted to have a dry weight of 35 inches.

(T)) Styrene-butadiene rubber latex (S
(abbreviated as BR) Styrene-butadiene rubber latex (trade name: JSRO561) manufactured by Japan Synthetic Rubber Co., Ltd. was adjusted to have a dry weight of 35 yen.

(K) Polymethyl methacrylate emulsion (P
(abbreviated as MMA) In a nitrogen stream, 7.5 parts of sodium alkylarylborioxyethylene sulfonate and 7.5 parts of sodium dodecylbenzenesulfonate were dissolved in 200 parts of water. Then, 150 parts of methyl methacrylate were added and polymerization was carried out at 75°C using potassium persulfate as an initiator. The dry weight of the obtained polymethylmethac IJI/) was 42 inches.

(F) Polyvinyl chloride emulsion (abbreviated as PVC) A polyvinyl chloride emulsion (trade name: Geon 150X15) manufactured by Nippon Zeon Co., Ltd. was used. Dry weight was 50%.

U Polystyrene emulsion (pst (L: Abbreviation t)) Dissolve 75 parts of sodium argylarylpolyoxyethylene sulfonate and 0.7 parts of sodium lauryl sulfate in 100 parts of water in a nitrogen stream, then add 65 parts of styrene, Polymerization was carried out at °C using potassium persulfate as an initiator.

The dry weight of the resulting polystyrene emulsion was 40 inches.

Examples 1 to 6 Powdered rubber was produced using the combinations of reagents shown in Table 1. That is, 200 parts of a 1% aqueous solution of an anionic water-soluble polymer was added to 285 parts of rubber latex, mixed until a homogeneous solution was obtained, and a 10% acetic acid aqueous solution was slowly added to adjust the pH to 6.3. Next, this mixed solution was added to an acidic aqueous solution containing 2 parts of acetate of a higher amine.
00 parts at room temperature with vigorous stirring, the rubber immediately separated into powder. Field after powder separation is 4.9
Met.

Next, a synthetic resin emulsion was added in an amount of 5% by weight based on the dry weight of the rubber latex, and mixing was continued for about 10 minutes. This powdered rubber slurry liquid was heated to about 50°C so that the fat weight stone was uniformly dissolved.
The indicated fatty acids were added in the respective proportions and neutralized with equimolar amount of hydrochloric acid.

Subsequently, polyaluminum chloride was added in respective proportions and mixing continued for 30 minutes. A wet powder rubber was obtained which was separated into a furnace using a cotton cloth, washed, and then dehydrated by centrifugation to form a powder easily by hand.

Then, it was dried in a fluidized fluid dryer to obtain a powdered rubber having a uniform particle size as shown in Table 2. As shown in Table 2, which evaluates the cohesiveness of these powdered rubbers after they were stored under load for 24 hours at 35°C, they could be crumbled into the cylinder by hand, indicating that they were not agglomerated in most cases. Recognize.

Furthermore, the particle size after storage was almost unchanged from before storage, indicating that the properties as a powdered rubber were not impaired.

As shown in the comparative example, when the treatment with fat barite and polyaluminum chloride was not performed, the case where only the fat barber's treatment was performed, and the case where only the treatment with polyaluminum chloride was performed, under a load of 35 parts So 2
When stored for 4 hours, it aggregates into a castella-like shape and is impossible to break, and even if it can be broken, it will not become the powder state it was before storage and will lose its properties as a powdered rubber. You can see that

Example 7 100 parts of a 100% aqueous solution of sodium carboxymethyl cellulose was added to 100 parts of OR latex and mixed to form a homogeneous solution. Add 10% acetic acid aqueous solution to adjust pH to 6.3
After soaking, this mixed solution was poured into 500 parts of a 0.2% acidic aqueous solution of polyvinylpyridine hydrochloride at room temperature with vigorous stirring, and the rubber was separated into powder. PMM
A ratio of emulsion 6 to the dry weight of rubber latex
The weight M% was added and mixing was continued for 10 minutes. Next, the temperature was raised to about 50°C, 07 parts of sodium stearate was dissolved, and 3.5 parts of polyaluminum chloride (trade name: PAO, solid content: about 10%, manufactured by Toyo Soda Co., Ltd.) was added and mixed for 30 minutes. continued. After washing with a cotton cloth and dehydrating with a centrifuge, a wet powdered rubber was obtained that could be easily crushed. Then, it was dried to obtain a dry powder rubber of which 96.1% was 20 mesh or less. This powdered rubber was applied under a load of 35°C (4B 9,6
When stored for 24 hours, the powder molded product had a load of 10
kg, and the powder properties were 95.7% 20 mesh or less, almost unchanged from before storage.

Comparative Example 4 In the same manner as in Example 1, rubber was separated into powder from OR latex. TIH after powder separation is 4°9,'
Three parts of polyaluminum chloride (manufactured by Toyo Soda Co., Ltd., trade name PΔC1, solid content: about 10%) was added to this powder separated liquid. When the thus obtained powdered rubber slurry liquid was dehydrated using a centrifugal separator, the rubber formed into blocks and was washed away, making it impossible to obtain powdered rubber.

Patent applicant: Toyo Soda Kogyo Co., Ltd.

Claims (1)

[Claims] 1. Rubber latex containing an anionic water-soluble polymer is placed in an aqueous solution of a cationic water-soluble polymer or a cationic surfactant that coacerbates with the anionic water-soluble polymer under acidic conditions. 1. A method for preventing agglomeration of powdered rubber during storage, characterized in that the powdered rubber slurry obtained by adding a synthetic resin as an emulsion and then treating the obtained powdered rubber slurry with a fatty acid and polyaluminum chloride.