JP2001122907A - Method for producing skim rubber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a skim rubber by using a serum of a deproteinized natural rubber latex. SOLUTION: A proteolytic enzyme and a surfactant are formulated with a natural rubber latex to carry out the proteolytic treatment, and the product is subjected to a concentration treatment to provide the serum of the deproteinized natural rubber latex, and at least one kind selected from a group comprising an amine salt-type cationic surfactant, a dialkyl quarternary ammonium salt-type cationic surfactant and imidazolinium salt-type cationic surfactant is added to the obtained serum to provide the objective skim rubber. The amount of the formulated cationic surfactant is preferably >=0.1 g based on 100 g of the liquid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing skim rubber from the serum of a deproteinized natural rubber latex.

[0002]

2. Description of the Related Art Natural rubber latex such as commercially available ammonia-treated latex is generally produced by subjecting a field latex collected from a rubber tree to a centrifugal separation treatment and concentrating the resultant. In the production of such a natural rubber latex, the serum (skim) generated by the centrifugation treatment contains not only components to be discarded, such as impurities such as proteins and zinc white as a preservative, but also fine particles of natural rubber. . Therefore, conventionally, by adding an acid such as sulfuric acid to the serum, natural rubber fine particles are coagulated and collected, and are effectively used as a skim rubber used for, for example, shoe soles.

[0003]

On the other hand, proteins contained in natural rubber latex have the following problems: (i) they cause allergies; and (ii) their contents vary depending on the latex producing area and the like. (Iii) causes variations in the quality and vulcanization properties of
It has been reported that natural rubber products cause deterioration of mechanical properties such as insulation properties, creep properties, and aging resistance. Therefore, in recent years, deproteinization treatment has been performed on natural rubber latex to reduce its protein content.

[0004] However, in the deproteinized natural rubber latex thus obtained, the particle size of the natural rubber contained in the serum is extremely small, which is coupled with the addition of an anionic surfactant to the latex during the deproteinization treatment. hand,
There was a problem that the natural rubber fine particles were extremely stably dispersed in the latex serum. Therefore, even if a conventional coagulant such as sulfuric acid is added to the serum of the deproteinized natural rubber latex, creaming occurs, but the rubber component is not solidified to obtain a solid rubber component. As a result, a situation has arisen in which the effective use of the skim rubber is limited.

Accordingly, an object of the present invention is to provide a method for removing skim rubber from the serum of a deproteinized natural rubber latex.

[0006]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, if a specific cationic surfactant is added to the serum of the deproteinized natural rubber latex, the serum can be obtained. The present inventors have found a new fact that a skim rubber can be obtained by coagulating fine particles of deproteinized natural rubber contained therein, and have completed the present invention. That is, the production method of the skim rubber of the present invention is to mix a proteinase and a surfactant with a natural rubber latex, perform a protein degradation treatment, and further perform a concentration treatment on the serum of the deproteinized natural rubber latex. , At least one selected from the group consisting of amine salt type cationic surfactants, dialkyl quaternary ammonium salt type cationic surfactants, and imidazolinium salt type cationic surfactants
It is characterized by adding a kind of cationic surfactant.

According to the present invention, natural rubber fine particles present in the serum of a deproteinized natural rubber latex having an extremely small particle size and whose dispersion state is extremely stabilized by the presence of an anionic surfactant. Even so, the dispersion state can be destabilized and solidified, and a skim rubber can be manufactured effectively. In the above method for producing a skim rubber according to the present invention, the amount of the cationic surfactant is preferably 0.1 g or more per 100 g of serum. By setting the blending amount of the cationic surfactant within the above range, the recovery rate of the particulate natural rubber in the serum can be improved.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for manufacturing a skim rubber according to the present invention will be described in detail. [Deproteinized natural rubber latex] As the deproteinized natural rubber latex used in the method of producing the skim rubber according to the present invention, those obtained by subjecting a natural rubber latex to protein degradation by a conventionally known method, specifically, natural rubber The latex may be obtained by adding a protease and a surfactant to the latex, and then ripening the mixture with standing or stirring to decompose the protein, and further purifying the protein by repeating dilution and concentration by centrifugation.

(Natural Rubber Latex) The natural rubber latex used for producing the deproteinized natural rubber latex may be either fresh field latex or commercially available ammonia-treated latex. (Protease) Various conventionally known proteases can be used as the protease used in the deproteinization treatment, and are not particularly limited. For example, an alkaline protease is preferably used.

The amount of the proteolytic enzyme to be added is appropriately set according to the enzyme activity, and is usually 0.0001 to 20 parts by weight, preferably 0.1 to 20 parts by weight, based on 100 parts by weight of the solid content of the NR latex. It is set in the range of 001 to 10 parts by weight. When the amount of the protease is below the above range, N
There is a possibility that the protein in the R latex cannot be sufficiently decomposed. On the other hand, when the amount of the protease added exceeds the above range, the activity of the enzyme may be reduced and the cost may be increased. When adding the enzyme, other additives such as a pH adjuster may be added.

(Surfactant) Examples of the surfactant used in the deproteinization treatment include various known anionic surfactants such as carboxylic acids, sulfonic acids, sulfates, and phosphates. No. Examples of the carboxylic acid-based anionic surfactant include those having 6 carbon atoms.
Fatty acid salts, polyvalent carboxylate, rosinate, dimer acid salt, polymer acid salt, trol oil fatty acid salt and the like having 30 or less are mentioned, among which carboxylic acid salts having 10 to 20 carbon atoms are preferred. It is preferably used. When the number of carbon atoms is 6 or less, dispersion and emulsification of proteins and impurities are insufficient, and when the number of carbon atoms is 30 or more, it is difficult to disperse in water. Examples of the sulfonic acid-based anionic surfactant include an alkyl benzene sulfonate, an alkyl sulfonate, an alkyl naphthalene sulfonate, a naphthalene sulfonate, and a diphenyl ether sulfonate. Examples of the sulfate-based anionic surfactant include alkyl sulfates, polyoxyalkylene alkyl sulfates, polyoxyalkylene alkylphenyl ether sulfates,
Tristyrenated phenol sulfate, polyoxyalkylene distyrenated phenol sulfate, and the like. Examples of the phosphate anionic surfactant include an alkyl phosphate salt and a polyoxyalkylene phosphate salt. As salts of these compounds, metal salts (Na, k, Ca, Mg, Zn
Etc.), ammonia salts, amine salts (such as triethanolamine salts) and the like.

In the present invention, various conventionally known nonionic surfactants may be blended during the deproteinization treatment, provided that they are used in combination with the above-mentioned anionic surfactant. (Protein Degradation Treatment) The treatment time of the protein degradation treatment is appropriately set according to the activity of the enzyme to be used, and is not particularly limited. However, it is usually preferable to perform the treatment for several minutes to about one week. During the proteolytic treatment, the latex may be agitated or may be allowed to stand. The temperature may be adjusted as needed, and the temperature suitable for the protein decomposition treatment is 5 to 90 ° C, preferably 20 to 60 ° C. When the treatment temperature exceeds 90 ° C., the enzyme is quickly deactivated.
When the temperature is lower than ℃, the reaction of the enzyme is difficult to proceed.

In the above-mentioned proteolytic treatment, when the above-mentioned enzymes and surfactants are used, other additives, such as phosphates, acetates or salts thereof, pH adjusters such as sodium carbonate, dispersants, etc. Etc. may be added. (Concentration treatment) After performing the protein decomposition treatment, the rubber particles in the latex are washed to remove decomposed products, and when the rubber particles are purified, the rubber particles are concentrated by, for example, a latex that has been subjected to the protein decomposition treatment. Conventional methods such as (a) centrifugation, (b) creaming by adding a creaming agent, (c) ultrafiltration, (d) dialysis, etc. Various methods of concentration are preferably adopted.

When the rubber particles are concentrated, the latex preferably contains a surfactant. The surfactant is preferably the anionic surfactant exemplified above, and its content is adjusted to be in the range of 0.001 to 20 parts by weight based on 100 parts by weight of the rubber solid content of the latex. Is appropriate. In the case of performing the centrifugation treatment of the above (a), the natural rubber latex subjected to the protein decomposition treatment is centrifuged at 5,000 to 10,000 rpm (or a gravitational acceleration of about 9000 to 10,000 G) for 1 to 60 minutes. Just do it. The centrifugation may be performed once or several times. Usually, a single centrifugation process can provide a deproteinized natural rubber latex from which proteins are highly removed. In the centrifugation treatment, the rubber content of the natural rubber latex subjected to the protein decomposition treatment is 5 to 5.
It may be carried out after dilution with water so as to be 40% by weight, preferably 10 to 30% by weight.

In the latex subjected to the protein decomposition treatment by centrifugation, the serum portion other than the creamy rubber separated in the upper layer is used for the production of the skim rubber according to the present invention. When the creaming of the above (b) is performed, various conventionally known creaming agents such as ammonium alginate and tragagant rubber may be added to the natural rubber latex subjected to the protein decomposition treatment. The serum portion other than the creamy rubber floating on the latex liquid surface due to the addition of the creaming agent is used for producing the skim rubber according to the present invention.

The amount of the creaming agent may be appropriately set according to a conventional method. The ultrafiltration of (c) above or the above
In the case of concentrating by dialysis in (d), separation treatment may be performed according to a conventional method. The ultrafiltration membrane or semipermeable membrane used in the separation treatment is not particularly limited, and various conventionally known ones can be used. [Treatment with Cationic Surfactant] (Cationic Surfactant) In the method for producing a skim rubber according to the present invention, (I) an amine salt type cationic surfactant Surfactants, (II) dialkyl quaternary ammonium salt type cationic surfactants, and (III) imidazolinium salt type cationic surfactants. The above cationic surfactants can be used alone or in combination of two or more.

In the present invention, among various known cationic surfactants, those classified into the above (I) to (III) can be used. When cationic surfactants other than the above (I) to (III) were used, even creaming of serum did not occur, and recovery of skim rubber was impossible, as is clear from the comparative examples described later. The amine salt type cationic surfactant of the above (I) generally has the formula (1):

[0018]

Embedded image

(Wherein, R ¹ represents an aliphatic hydrocarbon group having 12 to 18 carbon atoms, and R ² and R ³ are the same or different and each represent a hydrogen atom or an aliphatic hydrocarbon group having 1 to 4 carbon atoms. X is an inorganic acid or an organic acid), and is a primary, secondary or tertiary amine salt, for example, an alkylamine salt such as coconutamine acetate, stearylamine acetate, etc. Is mentioned.

A specific example of such an amine salt type cationic surfactant is “Acetamine 2” (trade name, manufactured by Kao Corporation).
4 "and" Cation SA "(trade name, manufactured by NOF CORPORATION). The dialkyl quaternary ammonium salt type cationic surfactant of the above (II) generally has the formula (2):

[0021]

Embedded image

(Wherein, R ⁴ and R ⁵ are the same or different and each represent an alkyl group having 12 to 18 carbon atoms, and X ⁻ represents a counter ion.) The nitrogen atom has two higher alkyl groups having 12 to 18 carbon atoms, and examples thereof include dilauryl dimethyl ammonium halide, dicetyl dimethyl ammonium halide, distearyl dimethyl ammonium halide, and dioleyl dimethyl ammonium halide.

Specific examples of such a dialkyl quaternary ammonium salt-type cationic surfactant include “Coatamine D10P” (trade name, manufactured by Kao Corporation), “Coatamine D86P” (trade name, manufactured by Kao Corporation), and Sanyo Chemical Co., Ltd. Trade name "Cation DS". The imidazolinium salt type cationic surfactant of the above (III) generally has the formula (3):

[0024]

Embedded image

(Wherein, R ⁶ represents a hydrocarbon group having 1 to 4 carbon atoms, R ⁷ represents a hydrocarbon group having 12 to 24 carbon atoms,
R ⁸ represents a hydrocarbon group having 1 to 5 carbon atoms. X ^- represents a counter ion. ), For example, 2-heptadecenyl-hydroxylethylimidazoline and the like. Specific examples of such an imidazolinium salt type cationic surfactant include “Cation SF-10” (trade name, manufactured by Sanyo Chemical Co., Ltd.) and “Cation AR ₄ ” (trade name, manufactured by NOF Corporation). .

(Amount of Cationic Surfactant) In the method for producing a skim rubber according to the present invention, the amount of the cationic surfactant added is not particularly limited because it varies depending on the type of the cationic surfactant used. Usually, it is preferably 0.1 g or more per 100 g of serum of the deproteinized natural rubber latex. If the amount of the cationic surfactant is less than the above range with respect to 100 g of serum, the fine particles of deproteinized natural rubber contained in the serum may be sufficiently coagulated and may not be recovered.

From the viewpoint of increasing the amount of skim rubber recovered (produced), it is preferable to use an amine salt type cationic surfactant as the cationic surfactant, and to set the addition amount to at least 0.75 g in the above range. . (Recovery treatment of skim rubber) In coagulating and recovering fine particles of deproteinized natural rubber from the serum of deproteinized natural rubber latex, the serum added with the cationic surfactant is
It is preferable to leave it as it is.

Usually, after adding a cationic surfactant,
By allowing the serum to stand for about 5 to 10 minutes, the fine rubber particles in the serum can be coagulated to obtain a skim rubber. Even when the standing time was increased to, for example, about 24 hours, the amount of skim rubber obtained hardly changed.

[0029]

(Preparation of serum)

Reference Example As a natural rubber latex, commercially available high ammonia (H
A) Latex [Rubber solid content 60%, ammonia content 0.7%, nitrogen content (N%) by Kjeldahl method 0.
38%].

For about 167 parts by weight of the HA latex (100 parts by weight of rubber solids), 0.3 parts by weight of an alkaline protease (protease) and 3 parts by weight of a commercially available sodium lauryl sulfate (anionic surfactant). Was added and diluted with water to prepare a natural rubber latex having a rubber solid content of 30% by weight.
The mixture was aged while stirring for 6 hours to perform a protein decomposition treatment. Next, about 3 latexes subjected to protein degradation treatment
33 parts by weight (100 parts by weight of rubber solids) are diluted with water,
The total amount was adjusted to 1,000 parts by weight (rubber solid content: about 10% by weight), and centrifuged at 10,000 rpm (gravity acceleration of about 9000 G) for 30 minutes.

After the centrifugation treatment, the creamy rubber component (deproteinized natural rubber) separated in the upper layer was taken out, and the serum other than the rubber component was subjected to the production of skim rubber in the following Examples and Comparative Examples. The nitrogen content (N%) of the rubber component (deproteinized natural rubber) by the Kjeldahl method was 0.02%. The total amount of solids contained in 100 g of the serum was measured by evaporating water in the serum, and was 2.2 g. The pH of the serum is 9.
It was 8.

[Manufacture of skim rubber] Example 1 An amine salt type cationic surfactant [trade name “Acetamine manufactured by Kao Corporation” was added to 100 g of the serum derived from the deproteinized natural rubber latex obtained in the above Reference Example. 24 "] in the proportions of 0.1 g, 0.25 g, 0.5 g, 0.75 g and 1.0 g and left for 5 minutes, respectively.

After standing, the serum was filtered through an 80-mesh net, and the obtained solid was dried. As a result, the solid shown in Table 1 was obtained. Example 2 Instead of an amine salt type cationic surfactant, a dialkyl quaternary ammonium salt type cationic surfactant [Kao Corporation]
Product name "Coatamine D10P"]
A skim rubber was manufactured in the same manner as in Example 1.

Example 3 A dialkyl quaternary ammonium salt type cationic surfactant [Kao Corporation] was used in place of the amine salt type cationic surfactant.
Product name "Coatamine D86P"]]
A skim rubber was manufactured in the same manner as in Example 1. Example 4 Example 1 was repeated, except that an imidazolinium salt-type cationic surfactant [trade name “Cation SF-10” manufactured by Sanyo Chemical Co., Ltd.] was used instead of the amine salt-type cationic surfactant.
A skim rubber was manufactured in the same manner as described above.

Comparative Example 1 In place of the amine salt type cationic surfactant, a benzalkonium salt type cationic surfactant [trade name "Sanisol B-50" (alkylbenzyldimethylammonium chloride) manufactured by Kao Corporation] was used. This benzalkonium salt type cationic surfactant was used in 0.1 g, 0.25 g, 0.5 g, and 100 g of the serum obtained in the above reference example.
0.75 g and 1.0 g were added and left for 5 minutes, respectively.

After standing, the serum was filtered in the same manner as in Example 1 and the obtained solid was dried. The obtained solid was very small, and a skim rubber could be produced. Did not. Comparative Example 2 In place of the amine salt type cationic surfactant, a monoalkyl quaternary ammonium salt type cationic surfactant [trade name “Coatamine 24P” (lauryl trimethyl ammonium chloride) manufactured by Kao Corporation) was used. In the same manner as in Comparative Example 1, a surfactant was added, allowed to stand, and filtered, but the resulting solid content was very small, and a skim rubber could not be produced.

Comparative Example 3 A monoalkyl quaternary ammonium salt type cationic surfactant [trade name “Coatamine 86P” (stearyltrimethylammonium chloride) manufactured by Kao Corporation) was used instead of the amine salt type cationic surfactant. Other than using
When the operations of adding a surfactant, leaving, and filtering were carried out in the same manner as in Comparative Example 1, the obtained solid content was very small, and a skim rubber could not be produced.

Table 1 shows the above results. In Table 1, “◎”, “○”, and “X” described after the numerical value indicating the weight (g) of the obtained solid content are as follows, respectively. A: The amount of the solid skim rubber recovered (produced) was extremely large, and 70% or more of the total solid content in the serum could be recovered. ：: Skim rubber was recovered (manufactured). ×: The skim rubber could not be collected (produced).

[0039]

[Table 1]

As is evident from Table 1, in Examples in which the specific cationic surfactants exemplified in the above (I) to (III) were added to the serum of the deproteinized natural rubber latex, the content of impurities was all , A very small amount of skim rubber was recovered. In particular, when 0.75 parts by weight or more of the amine salt type cationic surfactant was added, a sufficient amount of skim rubber could be obtained. On the other hand, (I)
In the comparative example in which a different kind of cationic surfactant from that exemplified in (III) was added, a very small coagulated product was obtained, but a skim rubber suitable for practical use could not be obtained.

[0041]

As described in detail above, according to the present invention,
The extremely stable fine particle deproteinized natural rubber contained in the serum of the deproteinized natural rubber latex can be recovered as a skim rubber. Therefore, the present invention is suitably used for effectively utilizing the serum of the deproteinized natural rubber latex.

Claims (2)

[Claims] 1. An amine salt type cationic interface is added to a serum of a deproteinized natural rubber latex produced by blending a protease with a natural rubber latex, a proteinase and a surfactant, and subjecting the mixture to a concentration treatment. A method for producing a skim rubber, comprising adding at least one cationic surfactant selected from the group consisting of a surfactant, a dialkyl quaternary ammonium salt type cationic surfactant and an imidazolinium salt type cationic surfactant. . 2. The method according to claim 1, wherein the amount of the cationic surfactant is 0.1 g or more per 100 g of serum.