JPS5818374B2 - Dung pine rubber Seizouhou - 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 and formed into a bale shape to produce polyethylene film, etc. The method of packaging and commercializing the product has already been implemented industrially.

In this method, the rubber sticks during dehydration and drying, causing block formation, and in order to prevent the rubber from forming into blocks during storage and transportation, the rubber is packaged in bale form with polyethylene film or the like. There is.

When such bales of rubber are used in rubber processing plants such as tire manufacturing plants, the bales must be shredded for purposes such as automatic metering of the rubber.

Therefore, if this type of rubber is supplied in the form of powdered rubber, not only will it eliminate the trouble of shredding at rubber processing plants and facilitate automatic weighing, but it will also eliminate the need for sulfur, anti-aging agents, etc. in powdered rubber. Vulcanization accelerators and other rubber compounding agents can be triblended and connected directly to the extruder, making it possible to greatly shorten the rubber product manufacturing process.
Powderization of raw rubber has great industrial significance.

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 a mixture to which appropriate oil and the like are added as necessary.

As a result, in the case of powdered rubber made from rubber latex containing carbon black, it was found that there was a significant difference in the blocking properties of the powdered rubber depending on the type of emulsifier contained in the rubber latex, and that blocking properties of the powdered rubber varied depending on the type of coagulant in the rubber latex. In addition, the blocking property can be significantly improved by treating the powdered rubber made of the coagulated product with an acid-induced coagulation of resin latex and an acid-induced coagulation of carboxylic acid salt surface. The present invention was achieved based on these findings.

That is, the present invention mixes an emulsifier-containing rubber latex mainly composed of carboxylic acid salts and a carbon black water slurry, and adds an acid to this mixture to form a fine mixture containing rubber and carbon black (hereinafter referred to as "
It's called "crumb."

) is coagulated, a resin latex is added to the crumb, and the resin latex is coagulated on the crumb surface under acidic conditions,
Further, adding carboxylate soap to the crumb and coagulating the carboxylate soap on the surface of the crumb under acidic conditions,
This method of producing powdered rubber is characterized in that the crumb thus obtained is separated from the coagulated mother liquor and dried.

Conventionally, known methods for pulverizing rubber include, for example, immersing granular rubber in an aqueous resin dispersion, or spraying an aqueous resin dispersion onto granular rubber, and then drying.
(See Japanese Patent Publication No. 49-11460).

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

In addition, after solidifying the latex, a small amount of hard polymer latex such as polyvinyl chloride or polystyrene is added to it, and the hard polymer is solidified on the surface of the first solidified material.
A method of producing powdered powder by washing with water and drying has already been proposed (see Japanese Patent Publication No. 13626/1983).

However, even with such a known method, it is not only difficult to sufficiently prevent blocking of powdered rubber, but also there are various problems when applying this method to a coagulated product from a rubber latex-carbon black water slurry mixture. There is.

In the present invention, the rubber latex used to mix with the carbon black water slurry is limited to those using an emulsifier based on carboxylate soap as its emulsifier.

This is because the carboxylate soap emulsifier generates free carboxylic acid when it coagulates with acid, so this free carboxylic acid is used to coat the surface of crumb particles that are precipitated at the same time, and is used to prevent powdered rubber from forming into blocks. It is for the purpose of being useful.

If a rubber latex containing other emulsifiers, such as higher alcohol sulfates, alkylbenzene sulfonates, nonionic surfactants, or cationic surfactants, is used, coating with such free carboxylic acids may result. Not only is no effect obtained and the blocking prevention property is poor, but it also has the adverse effect of redispersing carbon black and resin latex in the coagulation mother liquor, which is not preferable.

In the present invention, the emulsifier carboxylate soap refers to alkali metal salts, ammonium salts, etc. of carboxyl-based compounds having surface activity.

For example, fatty acids (saturated or unsaturated carboxylic acids having 6 to 22 carbon atoms are preferred).

) stone grains, rosin grains, disproportionated rosin grains,
Examples include I-ru oil surface ken, carvone ryomeken derived from an α-olefin-maleic anhydride copolymer, and carvone ryomeken derived from a dicyclopentadiene-maleic anhydride reaction product. .

The term "emulsifier mainly composed of carboxylate soap" refers to carboxylate soap alone, but it is used to improve the stability of latex during polymerization, for example. Since small amounts of other auxiliary emulsifiers such as formalin condensates of sodium naphthalene sulfonate can be used in combination with carboxylate soaps, this means that small amounts of such auxiliary emulsifiers may be included.

The amount of carboxylate soap used in rubber latex is usually 2 to 15 parts by weight, preferably 5 to 10 parts by weight, based on 100 parts by weight of rubber, and the amount of the other auxiliary emulsifiers used is It is 10% by weight or less based on the salt soap.

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

The rubber latex in the present invention is produced by using an emulsifier mainly composed of carboxylate soap as described above, and by using a monomer or monomer such as butadiene, butadiene-styrene, butadiene-acrylonitrile, butadiene-isoprene, isoprene, chloroprene, etc. It can be easily obtained by emulsion polymerization of a mixture of substances.

In particular, latex of butadiene rubber or butadiene-styrene copolymer rubber, which is used as a general-purpose rubber, is preferable.

In some cases, natural rubber latex, a tiger 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.

The carbon black water slurry in the present invention includes:
An aqueous slurry of various carbon blacks prepared by an appropriate method is used.

For example, 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% by weight, preferably 6% by weight.
~10% by weight 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, oil may be further mixed into the rubber latex and carbon black water slurry mixture if desired.

As such oil, those normally used as rubber extension oils, such as aroma oil, nandene oil, and paraffin oil, are preferred.

The amount of oil added is 70 parts by weight or less per 100 parts by weight of rubber.

It is preferable to add the oil by emulsifying it with water using a carboxylic acid salt.

In the present invention, an acid is selected as the coagulant used to coagulate the mixture of rubber latex, carbon black water slurry, and optionally added oil.

Coagulants for rubber latex include aluminum sulfate,
Salt coagulants such as magnesium sulfate are also known, but when using a salt coagulant for coagulating a rubber latex-carbon black system or a rubber latex-oil-carbon black system mixture as in the present invention,
Not only is it easy to block the powdered rubber, but the carbon black cannot be completely coagulated, and free carbon black remains in the coagulation mother liquor, making the mother liquor black and opaque, which requires extra waste liquid treatment later. It is not desirable to do so.

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.

When the pH of the mixture becomes acidic, the rubber and carbon blank coagulate as crumbs of mixture particles, and at the same time, the carboxylic acid salt surface in the rubber latex also coagulates with the acid to produce free carboxylic acid, and the crumb particles Primarily covered by free carboxylic acid.

The size of the crumb particles generated at this time is usually 5 mm.
Hereinafter, it preferably has a particle size of about 1 mm or less, and the powdered rubber in the present invention refers to particles of this size.

In the present invention, a resin latex is then added to the crumb particles primarily coated with free carboxylic acid thus produced, the resin latex is coagulated under acidic conditions, and the crumb is re-coated with the resin. Coating (secondary coating)
let

The resin latex used for this purpose of the present invention includes polystyrene, styrene-butadiene copolymer resin (bistyrene resin with a styrene content of 50% by weight or more), styrene-acrylonitrile copolymer resin, polymethyl methacrylate, methyl Methacrylate-methyl acrylate co-electric monomer resin, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer resin, acrylonitrile-methyl acrylate copolymer resin, acrylonitrile-methyl vinyl ether copolymer resin, acrylonitrile-butadiene-styrene copolymer resin resin? (Af3S4ttl
Latexes such as methyl methacrylate-phytadiene-styrene graft copolymer resin (MBS resin), ethylene-vinyl acetate copolymer resin, and vinylidene chloride resin are listed.

These resins have their softening point or flow temperature: CASTM
D569-48) is preferably in the range of 35 to 200°C.

Such a resin latex can be easily produced by a known method such as polymerizing or copolymerizing the monomer or monomer mixture in the presence of a suitable emulsifier.

) Emulsifiers for resin latex include various carboxylic acid salts, higher alcohol sulfate ester salts, alkyl phosphate salts, alkylbenzene sulfonates, alkylnaphthalene sulfonates, naphthalene sulfonic acid formalin condensates, dialdecyl sulfosuccinates. , polyoxyethylene sulfate salt, etc. are used.

Examples of carboxylic acid salts include those used as emulsifiers for the above-mentioned rubber latex.

Examples of higher alcohol sulfate ester salts include sodium lauryl sulfate, sodium lauryl sulfate, potassium polyoxyethylene alkyl ether sulfate, potassium polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl phenyl ether sulfate, etc.) , potassium, etc.

Examples of alkyl phosphate salts include dialkyl phosphates, sodium and potassium dipolyoxyethylene alkyl phosphates, sodium and potassium dipolyoxyethylene alkyl phenyl ether phosphates, and the like.

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

The amount of these emulsifiers added is 1 to 10 parts by weight, preferably 3 to 7 parts by weight, per 100 parts by weight of the resin.

The amount of resin latex added to the crumb in the present invention is such that the resin is added in an amount of 0.5 to 10 parts by weight, preferably 2 to 7 parts by weight, per 100 parts by weight of rubber.

If a large amount of resin latex is added so that the amount of resin exceeds 10 parts by weight based on the rubber, the resulting powdered rubber will lose its rubber properties, which is not preferable.

The resin latex may be added to the mixture of crumb and its mother liquor after the first coagulation, or p
The crumb may be removed by filtration or the like and added directly to the crumb or to a slurry of the crumb with water or an acidic aqueous solution.

When resin latex is added to the crumb containing the mother liquor during the primary coagulation, the acid remaining in the mother liquor usually dissolves in the resin.

Since it acts as an acid for resin latex coagulation, there is often no need to add another coagulating acid, but if the acid remaining in the mother liquor is insufficient, add a separate acid for resin latex coagulation. Good too.

Also, take out the crumb after the first solidification and add it directly to this.

Alternatively, when adding resin latex to a slurry made by adding water, it is necessary to add an acid for coagulating the resin latex.

Furthermore, the resin latex may be added to a slurry made by adding the extracted crumbs to an acid aqueous solution or the like.

The acid added for coagulating the resin latex is the same as that used for coagulating the rubber latex and carbon black aqueous slurry mixture described above.

When coagulating the resin latex in the present invention, if the amount of acid is not sufficient and the resin is not sufficiently coagulated and remains as latex, various problems will occur in the processing of the resulting rubber.

For example, slipping occurs when mixing powdered rubber.

Therefore, powdered rubber with good processability cannot be obtained by the conventional methods of simply spraying resin latex onto powdered rubber or simply immersing powdered rubber in resin latex.

The amount of acid necessary for coagulating the resin latex is usually such that the pH of the mixture of crumb-containing material and resin latex is in the acidic range, preferably the pH of the mixture is 1.
~6.

In the present invention, the crumb coated with the coagulated resin latex (secondary coating treatment) has the following properties:
A carboxylate soap is then added to coagulate the carboxylate soap under acidic conditions and recoat the crumb with free carboxylic acid (tertiary coating).

As the carboxylate soap, the same carboxylate soap as used as an emulsifier for rubber latex is used.

The addition of carboxylic acid salt soap to crumbs causes secondary coagulation (
A carboxylate soap solution may be added to the crumb and mother liquor mixture after solidification of the resin latex.

In addition, the carboxylate soap solution may be added directly to the crumb separated from the secondary coagulation mother liquor by filtration or the like, or to a slurry of the crumb with water or an acidic aqueous solution. It can also be added.

The amount of carboxylate soap added is 1 to 10 parts by weight, preferably 2 to 6 parts by weight, per 100 parts by weight of rubber.

When carboxylate soap is added to the mixture of crumb and mother liquor after the second coagulation, the carboxylate soap is usually coagulated by the acid remaining in the mother liquor of the second coagulation solution. In many cases, it is not necessary to separately add an acid, but even in this case, a separate acid can be added if necessary.

Further, when adding a carboxylate salt to the crumb after removing it from the mother liquor, it is usually necessary to separately add an acid for coagulating the carboxylate soap.

The acid added for coagulating the carboxylate soap is the same as that used for the primary coagulation described above.

When a carboxylate soap is coagulated, if the amount of acid is insufficient, the carboxylate soap will not be oxidized to free carboxylic acid and will remain in the form of soap, causing various problems during the processing of the resulting powdered rubber. Therefore, the conditions are such that the carboxylate soap does not remain in the form of soap, i.e. acidic conditions, preferably the pH of the mixed liquid at the time of coagulation is 1 to 6.
, especially under conditions such that it becomes 3 to 5.

The crumb obtained by coagulating the carboxylate soap on the surface of the crumb (tertiary coagulation) is subjected to post-treatments such as filtration, washing with water, and filtering, and then is dried to obtain the desired powdered rubber.

The powdered rubber of the present invention thus obtained does not form blocks even when compressed under its own weight during heating during drying, storage, and transportation.

In particular, the blocking properties during storage are significantly improved compared to those that are not subjected to the tertiary coagulation treatment.

This is because the crumbs are coated with resin in the second coagulation process, but the free carboxylic acid produced in the tertiary coagulation process removes the small amount of uncoated crumbs that remain. It is assumed that the uncoated crumbs are completely coated, so that stickiness between the crumb particles is largely prevented.

In addition, in the manufacturing method of the present invention, rubber latex using an emulsifier mainly composed of carboxylate soap is used, and since the mixture of rubber latex and carbon black is coagulated using a powder solidifying agent, carbon There is no risk of black remaining in the coagulation mother liquor and turning the solution opaque or black, and the waste solution can be easily disposed of.

Furthermore, since there is no risk that the powdered rubber will form blocks during drying, there is an advantage that highly efficient drying methods such as powder fluidized drying and flash drying can be employed.

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

Parts and percentages in these examples are by weight unless otherwise specified.

In addition, in these examples, the powdered rubber blocks were tested after drying.

The experiment (measurement) and its evaluation were carried out using the following method.

In other words, 15 f in a cylinder with an inner diameter of 35 mm! After adding powdered rubber of The degree of blocking is evaluated based on the load at which the molded object collapses, and if the shape collapses without applying any load, it is 0,
The case where the shape collapsed under a load of 10 (1) was set as 1, and the case where the shape collapsed under a load of 2007 was set as 2 (the same applies hereinafter).

Example l SBR latex (styrene/butadiene = 2 by weight)
3777, rubber content 22.2%, emulsifier is fatty acid soda/
In a soap mixed with 1/1 sodium rosin acid, the amount of emulsifier is 6.5 parts per 100 parts of rubber.

) 18M', a water slurry (8% carbon black content) of 337 carbon black (manufactured by Mitsubishi Chemical Industries, Ltd., trade name Diablack SH), and aroma oil 257
and an oil emulsion emulsified with a tall oil layer.
After mixing in a 21-volume tank equipped with a stirrer and stirring for 3 minutes, 20 rILl of 5% aqueous sulfuric acid solution is added to form a crumb, that is, a rubber-oil-carbon black co-coagulate.

Next, polyvinyl chloride latex 4 rnl (
Softening point: 162°C, resin content: 50%, equivalent to 5 parts of resin to 100 parts of rubber.

), the polyvinyl chloride immediately coagulates and coalesces with the rubber particles.

Furthermore, while stirring was continued, 10 rIll of KS soap (semi-cured beef tallow potash soap manufactured by Kao Atlas Co., Ltd.) was added (solid content 27, equivalent to 5 parts per 100 parts of rubber).

) is added. After stirring for 30 minutes, the obtained powdered rubber was washed with water, filtered, and dried in a drier at a temperature of 80° C. for 3 hours.

It did not form blocks even during drying, and the evaluation in the blocking property test was 0.

This shows that this powdered rubber can be stored at a height of at least 5 m without forming blocks.

On the other hand, when an attempt was made to produce powder rubber in the same manner as in Example 1 except for using SBR latex obtained by emulsion polymerization with sodium alkylbenzenesulfonate as an emulsifier, rubber latex and The carbon blank water slurry mixture was already blocked during coagulation, and no powdered rubber was obtained.

Example 2 Instead of the SBR latex in Example 1, an SBR latex containing 0.26 parts of sodium naphthalene sulfonate/formalin condensate per 100 parts of rubber was used in addition to the soap in the same latex as an emulsifier. Powdered rubber was produced in the same manner as in Example 1 in other respects.

The blocking property evaluation of the obtained powdered rubber was O.

'Reference Example 1 Powdered rubber was produced in the same manner as in Example 1, except that the polyvinyl chloride latex treatment was not performed, and the resulting powdered rubber had a blockability evaluation of 8.

Reference Example 2 Similarly, powdered rubber was produced in the same manner as in Example 2 using polyvinyl chloride latex treatment, and the resulting powdered rubber had a blockability rating of 10.

Examples 3-8 Instead of polyvinyl chloride latex in Example 1,
Powdered rubber was produced in the same manner as in Example 1 except for using various resin latexes listed in the table below.

The evaluation of blocking properties of each of the obtained powdered rubbers was as shown in the table below.

Example 3 Instead of the KS soap used in the third stage of coagulation in Example 2, Lebenol WX (trade name of polyoxyethylene alkyl ether sodium sulfate manufactured by Kao Atlas Co., Ltd.) was used, and the other conditions were the same as in Example 2. Powdered rubber was produced.

The product was already blocked upon drying and no powdered rubber was obtained.

Reference Example 4 Powdered rubber was produced in the same manner as in Example 2, except that the third-stage KS soap coagulation process in Example 2 was not performed at all.

The blocking property evaluation of the produced powdered rubber was 1.

Reference Examples 5 and 6 ABS latex or acrylonitrile-methyl vinyl ether copolymer latex was used instead of the polyvinyl chloride latex used in the second stage coagulation treatment in Example 2, and A powdered rubber was produced in the same manner as in Example 2, except that no KS soap coagulation treatment was performed.

The obtained powdered rubber contained 4 parts of ABS latex (10 parts of rubber).
When 0 parts of the acrylonitrile-methyl vinyl ether copolymer latex was used, the blocking property evaluation was 2, and when 5 parts of the acrylonitrile-methyl vinyl ether copolymer latex was used, the blocking property evaluation was 3.

Example 9 A water slurry (carbon black content: 8%) of SBR Latexne 180P (rubber content: 407, same latex as Example 1) and 301 carbon black (product name: Diablack SH1, manufactured by Mitsubishi Chemical Industries, Ltd.) was mixed with a stirrer. After stirring for 3 minutes, 15 rnl of 5% sulfuric acid aqueous solution was added to form fine crumbs of rubber-carbon black co-coagulate.

Next, 4 ml of polyvinyl chloride latex (resin content: 2
1. Add KS soap (equivalent to 5 parts to 100 parts of rubber), continue stirring, and add KS soap (semi-cured beef tallow potash soap,
Kao Atlas Co., Ltd.) 10ml (Soap: 21, Rubber: 10
(equivalent to 5 parts to 0 parts) is added.

After stirring for 30 minutes, the obtained powdered rubber was washed with water and filtered.
The mixture was dried in a dryer at 0° C. for 3 hours to produce a powdered rubber.

This powdered rubber did not form blocks during drying, and the blocking property evaluation was 0.

Example 10 BR latex 1747 obtained by emulsion polymerization method (rubber content 23%, emulsifier is a mixed soap of fatty acid soda and rosin acid soda, emulsifier amount is 8 parts per 100 parts of rubber)
Then, an oil emulsion made by emulsifying 307 carbon black (product name: Diablack H, E manufactured by Ryo Kasei Kogyo Co., Ltd.) (carbon black content 8%) and aroma oil 151 in a tall oil surface was prepared using a stirrer. 2
Add to tank 1 and stir for 3 minutes, then add 5% sulfuric acid aqueous solution 1
5 ml is added to form a fine crumb of rubber-carbon black-oil co-agglomerate.

Next, 4 ml of polyvinyl chloride latex (resin content: 2
7. Add KS soap (equivalent to 5 parts to 100 parts of rubber), continue stirring, and add KS soap (semi-hardened beef tallow potassium soap,
Kao Atlas Co., Ltd.) 10ml (soap 27, rubber 10)
(equivalent to 5 parts to 0 parts) is added.

After stirring for 30 minutes, the obtained powdered rubber was washed with water and filtered.
The mixture was dried in a dryer at 0° C. for 3 hours to produce a powdered rubber.

The obtained powdered rubber does not form blocks during drying (
Moreover, the evaluation of blocking property was 0.

Claims (1)

[Claims] 1. Mixing an emulsifier-containing rubber latex mainly composed of carboxylic acid salts and a carbon black water slurry,
Acid is added to this mixture to coagulate a fine mixture containing rubber and carbon black (hereinafter referred to as "crumb"), resin latex is added to the crumb, and the resin latex is applied to the crumb surface under acidic conditions. solidify into
Further, a carboxylic acid salt surface is added to the crumb, and the carboxylic acid salt surface is coagulated on the surface of the crumb under acidic conditions.
A powder rubber manufacturing method characterized by separating the crumb thus obtained from the coagulated mother liquor and drying it.