JP2000198881A - Deproteinized natural rubber latex and rubber glove using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a deproteinized natural rubber latex capable of producing natural rubber products with a combination of low allergic effect, low modulus and sufficient mechanical strength, and to obtain rubber gloves by using the above latex. SOLUTION: This deproteinized natural rubber latex is obtained by compounding a deproteinized natural rubber latex with a ketone normally at 0.1-10 pts.wt. based on 100 pts.wt. of the latex on a rubber solid basis. The other objective rubber gloves are obtained by molding the above deproteinized natural rubber latex.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a deproteinized natural rubber latex capable of producing a natural rubber product having low allergenicity, low modulus, and excellent mechanical strength, and using the same. Related to rubber gloves.

[0002]

2. Description of the Related Art Natural rubber products have features such as high elongation, high elasticity, and good film strength, and range from industrial goods such as tires and belts to household goods such as gloves. Used in a wide range of fields. In particular, gloves made of natural rubber are excellent in workability and fit and are effective as a means for preventing infectious diseases, and are therefore suitably used in the medical field.

[0003]

However, in recent years,
It has been pointed out that natural rubber products cause allergic symptoms, and it is thought that proteins contained in natural rubber latex, which is a raw material of natural rubber products, cause allergies. Therefore, various methods for removing proteins in the natural rubber latex have been proposed. For example, Japanese Patent Application Laid-Open No. 6-56902 discloses a method in which a protease and a surfactant are added to natural rubber latex to ripen it. Thereafter, a method is disclosed in which the protein in the natural rubber latex is effectively removed by diluting and centrifuging.

[0004] Deproteinized natural rubber (DPNR) latex obtained by the method disclosed in the above-mentioned publications has a significantly reduced protein content as compared with high ammonia (HA) latex usually used for the production of natural rubber products. Therefore, it is possible to provide a natural rubber product that is less likely to cause allergies. Further, since the modulus is reduced as compared with the HA latex, it is possible to provide a rubber glove having high flexibility and excellent workability and fit.

However, a rubber product obtained from a deproteinized natural rubber latex has a problem in that the mechanical strength is lower than in a case where no deproteinization treatment has been performed, and the rubber product is insufficient for practical use. Accordingly, an object of the present invention is to provide a deproteinized natural rubber latex capable of obtaining a natural rubber product having improved mechanical strength without impairing hypoallergenicity and low modulus, and a rubber glove using the same. It is to provide.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, when a ketone is added to a deproteinized natural rubber latex, a deproteinization treatment is performed. The present inventors have found a completely new fact that a natural rubber product having improved mechanical strength can be provided without impairing the low allergenicity and low modulus obtained by the method, and have completed the present invention.

That is, the deproteinized natural rubber latex of the present invention is characterized in that a deproteinized natural rubber latex contains ketones. In the present invention, the content of the ketones is 0.1 to 1 part by weight based on 100 parts by weight of the rubber solid content of the deproteinized natural rubber latex.
It is preferably 0 parts by weight.

According to the deproteinized natural rubber latex of the present invention, the mechanical strength of the deproteinized natural rubber is 10 to 10 compared to the conventional deproteinized natural rubber without impairing the properties such as low allergenicity and low modulus. It can be improved by as much as 15%. Further, a rubber glove of the present invention is formed using the deproteinized natural rubber latex of the present invention.

The rubber gloves of the present invention are less likely to cause allergies, have excellent workability and fit, and have sufficient strength, and are suitably used in various fields including the medical field. be able to.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the deproteinized natural rubber latex of the present invention will be described in detail. As described above, the deproteinized natural rubber latex of the present invention is obtained by blending a ketone with the deproteinized natural rubber latex. [Deproteinization treatment of natural rubber latex] The deproteinized natural rubber latex can be obtained, for example, by the method described in JP-A-6-56902.
According to the method disclosed in Japanese Patent Application Laid-Open Publication No. H10-209, it can be obtained by subjecting natural rubber latex to proteolytic treatment. That is, as an example of the deproteinized natural rubber latex in the present invention, the natural rubber latex was added with a protease and then aged to ripen, decompose the protein in the latex, and then repeatedly washed the latex. Things.

The natural rubber latex used in the present invention may be either a commercially available ammonia-treated latex or a fresh field latex. A conventionally known protease can be used as the protease, and is not particularly limited. For example, an alkaline protease is preferably used. The protease may be derived from a bacterium, a filamentous fungus, a yeast, or the like, but among them, it is preferable to use a bacterium. In addition, enzymes such as lipase, esterase, amylase, laccase, and cellulase may be used in combination.

When an alkaline protease is used as a protease, its activity is suitably in the range of 0.1 to 50 APU / g, preferably 1 to 25 APU / g. The enzyme activity is determined by the Anson-hemoglobin method (Anso
n. ML, J. Gen. Physiol., 22, 79 (1938)). That is, in a solution adjusted so that the final concentration of urea-denatured hemoglobin used as a substrate is 14.7 mg / ml, the reaction is performed at a temperature of 25 ° C. and a pH of 10.5 for 10 minutes, and then trichloroacetic acid is added to the reaction solution. Add to a concentration of 31.25 mg / ml. Next, the soluble matter of trichloroacetic acid was colored with a phenol reagent, and the activity per 10 minutes of the reaction was determined by a calibration curve with the color degree of 1 mol of tyrosine as 1 APU, which was converted to 1 minute. It was measured. In addition, 1
APU refers to the amount of protease that gives a soluble amount of trichloroacetic acid per minute having the same color degree as one mole of tyrosine is colored by the phenol reagent. However,
The activity measurement of the alkaline protease is not limited to this measurement method.

The amount of the proteolytic enzyme to be added is appropriately set according to the enzyme activity, but is usually 0.0001 to 20 parts by weight, preferably 0.1 to 20 parts by weight, per 100 parts by weight of the solid content of the natural rubber 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,
There is a possibility that the protein in the 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.

[0014] The treatment time of the protein degradation treatment is also appropriately set according to the enzyme activity, and is not particularly limited. During the proteolytic treatment, the latex may be agitated or may be allowed to stand. The temperature may be adjusted as needed, but the temperature suitable for the treatment is 5 to 90 ° C, preferably 20 to 60 ° C. When the treatment temperature exceeds 90 ° C., the enzyme is quickly deactivated, and when the treatment temperature is less than 5 ° C., the reaction of the enzyme becomes difficult to proceed.

As a method for washing latex particles with a surfactant, for example, a method in which a latex that has been treated with an enzyme / surfactant is centrifuged is suitably employed. In this case, the surfactant is a rubber solid content of latex of 10%.
It is appropriate to add in the range of 0.001 to 20 parts by weight with respect to 0 parts by weight. In the centrifugation, first, natural rubber latex that has been subjected to a protein decomposition treatment
Centrifugation may be performed at 00 rpm for 1 to 60 minutes. 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. The centrifugation treatment may be performed after diluting with water so that the rubber content of the natural rubber latex subjected to the protein decomposition treatment is 5 to 40% by weight, preferably 10 to 30% by weight.

After the centrifugation, the creamy rubber separated in the upper layer is taken out and diluted with water to obtain a deproteinized natural rubber latex. The operation of removing the creamy rubber component may be continuously performed by a disk-type centrifuge. Further, instead of the washing method by centrifugation, a washing method of aggregating and separating latex particles can be adopted.

Examples of the surfactant include (a) an anionic surfactant, (b) a nonionic surfactant, and (c)
Zwitterionic surfactants can be used. Examples of the anionic surfactant (a) include carboxylic acid-based, sulfonic acid-based, sulfate-based, and phosphate-based surfactants. Examples of the nonionic surfactant (b) include surfactants such as polyoxyalkylene ethers, polyoxyalkylene esters, polyhydric alcohol fatty acid esters, sugar fatty acid esters, and alkyl polyglycoside surfactants. Is mentioned. (c) zwitterionic surfactants include:
For example, amino acid type, betaine type, amine oxide type and the like can be mentioned.

In using the above-described enzymes and surfactants, other additives such as a pH adjuster and a dispersant may be added. Examples of the pH adjuster include phosphates such as potassium dihydrogen phosphate, dipotassium hydrogen phosphate, sodium dihydrogen phosphate, disodium hydrogen phosphate, potassium acetate, acetates such as sodium acetate, sulfuric acid,
Acids such as acetic acid, hydrochloric acid, nitric acid, citric acid and succinic acid or salts thereof, ammonia, potassium hydroxide, sodium hydroxide, sodium carbonate, sodium hydrogen carbonate and the like. The amount of the pH adjuster to be added is usually 0.01 to 0.5 part by weight based on 100 parts by weight of the rubber solid content of the latex.

In the protein degradation treatment, in addition to the above components, styrene sulfonic acid copolymer, naphthalene sulfonic acid formalin condensate, lignin sulfonic acid, polycyclic aromatic sulfonic acid copolymer, acrylic acid and maleic anhydride Dispersants such as acid homopolymers and copolymers, isobutylene-acrylic acid and isobutylene-maleic anhydride copolymers may be used in combination.

The nitrogen content (N%) of the deproteinized natural rubber latex used in the present invention is preferably adjusted to 0.10% by weight or less from the viewpoint of suppressing the occurrence of allergy. The nitrogen content (N%) can be appropriately adjusted depending on the degree of the proteolytic treatment. In order to more reliably suppress the occurrence of immediate allergy, the nitrogen content (N
%) Is preferably adjusted to be 0.05% by weight or less in the above range, and more preferably adjusted to be 0.02% by weight or less.

The deproteinization treatment of the natural rubber latex in the present invention is not limited to the above method.
Various conventionally known deproteinization methods can be used as long as the allergy can be sufficiently reduced. [Ketones] Ketones used in the present invention include various conventionally known ketones such as aliphatic acyclic ketones, alicyclic ketones, carbocyclic ketones, and heterocyclic ketones. Since those having excellent solubility in rubber latex are preferable, lower aliphatic ketones which are easily soluble in water are preferably used.

Examples of the lower aliphatic ketone include lower aliphatic acyclic monoketones having 3 to 6 carbon atoms, such as acetone and 2-butanone (ethyl methyl ketone); butanedione (biacetyl), 2,4-pentanedione (Acetylacetone), lower aliphatic acyclic diketone having 4 to 6 carbon atoms such as 2,5-hexanedione (acetonylacetone); and 4 carbon atoms such as cyclobutanone and cyclohexanone.
To 6 lower aliphatic cyclic ketones and the like.

The content of the ketones is preferably set in the range of 0.1 to 10 parts by weight based on 100 parts by weight of the rubber solid content of the natural rubber latex. If the content of the ketones falls below the above range, the effect of improving the mechanical strength of the rubber product using the natural rubber latex may not be obtained. Conversely, even if the ketones are contained beyond the above range, it is not possible to obtain a further effect of improving the mechanical strength, which may cause problems such as inhibiting the stability of the latex and generating a coagulated substance. There is.

The content of ketones is preferably from 0.7 to 4.5 parts by weight in the above range. [Other Additives] In order to produce a rubber product using the deproteinized natural rubber latex of the present invention, a vulcanizing agent, a vulcanization accelerator, a vulcanization accelerator ( Various conventionally known additives such as an activator, an antioxidant, a filler, a dispersant, and a coagulant (eg, an anodic coagulant and a heat sensitizer) are added as necessary.

Examples of the vulcanizing agent include sulfur and organic sulfur-containing compounds, and the amount of the vulcanizing agent is about 0.5 to 3 parts by weight based on 100 parts by weight of the rubber solid content of the rubber latex. Is preferred. Examples of the vulcanization accelerator include PX (zinc N-ethyl-N-phenyldithiocarbamate), PZ (zinc dimethyldithiocarbamate), and EZ
(Zinc diethyldithiocarbamate), BZ (Zinc dibutyldithiocarbamate), MZ (Zinc salt of 2-mercaptobenzothiazole), TT (Tetramethylthiuram disulfide) and the like. These can be used alone or in combination of two or more. The amount of the vulcanization accelerator is preferably about 0.5 to 3 parts by weight based on 100 parts by weight of the rubber solid content of the rubber latex.

[0026] Examples of the vulcanization accelerating aid include zinc white. The compounding amount of the vulcanization accelerator is preferably 0.5 to 3 parts by weight based on 100 parts by weight of the rubber solid content of the rubber latex. As the anti-aging agent, generally, CP
L (hindered phenol), Antage W-30
0 [4,4'-butylidenebis- (3-methyl-6-t
-Butylphenol)], and non-staining phenols are preferably used, but amines such as octylated diphenylamine may also be used. The compounding amount of the anti-aging agent
For 100 parts by weight of the rubber solid content of the rubber latex, 0.
It is preferably about 5 to 3 parts by weight.

As the filler, for example, kaolin clay,
Hard clay, calcium carbonate and the like can be mentioned. The compounding amount of the filler is preferably 10 parts by weight or less based on 100 parts by weight of the rubber solid content of the rubber latex. In addition, a dispersant may be blended to improve the dispersion of the above additives in the rubber latex. Such dispersants include:
Examples include various anionic surfactants. The compounding amount of the dispersant is 0.1% of the weight of the component to be dispersed.
It is preferably about 3 to 1.0% by weight.

The method for producing a dipped product such as rubber gloves using the deproteinized natural rubber latex of the present invention includes a so-called direct method in which a mold is directly immersed in latex, and a method in which an anode adhesive is previously added to a glove mold. So-called coagulation immersion method in which this mold is immersed in latex, or a coagulant such as a heat-sensitive agent is previously compounded in latex,
A so-called heat-sensitizing method in which a mold is immersed in the latex is exemplified.

Examples of the anode adhesive include metal salts having an ionic value of 2 or more, such as calcium nitrate and calcium chloride; and organic alkylamine salts. Examples of the thermal sensitizer include an inorganic or organic ammonium salt, a water-soluble polymer having a cloud point of normal temperature or higher and 100 ° C. or lower.
Examples of the inorganic or organic ammonium salts include ammonium nitrate, ammonium acetate, various zinc ammonium complex salts and the like. Further, specific examples of the water-soluble polymer include polyvinyl methyl ether, polyalkylene glycol, polyether polyformal, and functional polysiloxane.

Next, the rubber glove of the present invention will be described in detail. As described above, the rubber glove of the present invention is formed using the deproteinized natural rubber latex of the present invention containing a ketone. The rubber glove of the present invention is manufactured by immersing the mold in the deproteinized natural rubber latex of the present invention, lifting the mold, vulcanizing and drying the rubber film formed on the mold surface. As the immersion method, various conventionally known methods such as the above-described direct method, anode adhesion method, and heat-sensitive coagulation method can be used.

The vulcanization conditions for the rubber film formed on the mold surface are as follows:
Although it is appropriately set according to the thickness of the rubber film, etc.,
Usually, it is preferable to set the temperature at 100 to 120 ° C. for about 30 to 90 minutes. After blending the various additives with the deproteinized natural rubber latex, pre-vulcanization may be performed once, and then a rubber film may be formed by a dipping method. The pre-vulcanization in such a case is preferably performed usually at 30 to 50 ° C. for about 15 to 30 hours.

The thickness of the rubber glove can be appropriately adjusted depending on the purpose of use of the rubber glove. For example, in the case of surgical gloves, the softness and water resistance are not impaired, and the rubber is usually 0.1 to 0.1 so that the rubber is not broken.
It is set in the range of 0.3 mm, preferably 0.15 to 0.25 mm. Also, in the case of work gloves, usually 0.5
３3.0 mm, preferably 0.8-2.0 mm.

The tensile stress M ₅₀₀ at 500% elongation of the rubber glove of the present invention is from 10 to 25 kgf in accordance with JIS K 6251 “Tensile test method for vulcanized rubber” from the viewpoint of realizing low modulus. / Cm ² , preferably 15 to 20 kgf / cm ² . If the tensile stress M ₅₀₀ exceeds the above range, the modulus increases, and as a result, the flexibility of the rubber glove is reduced, and the fit is impaired. On the other hand, if the tensile stress M ₅₀₀ is below the above range, the modulus becomes too low and the handling of the rubber glove is reduced, or the rubber glove becomes weak and unsuitable for practical use.

The mechanical strength of the rubber glove of the present invention is as follows.
For example JIS K tensile strength was determined according to "Tensile Test Method of Vulcanized Rubber" of 6251 T _B is, 210 kgf / c
m ² or more, preferably 240 kgf / cm ² or more. If the tensile strength T _B is less than the above range, the strength of the rubber glove is practically insufficient. Also, stretchable rubber gloves, as attachment and detachment of the gloves to exhibit easy and good fit, the elongation at break E _B determined according to the "Tensile Test Method of Vulcanized Rubber" of JIS K 6251 700 to It is preferably 1000%, and 800 to 90%.
More preferably, it is 0%.

The deproteinized natural rubber latex of the present invention can be used for various immersion products such as probe covers and condoms in addition to the above rubber gloves. The rubber component of the latex may be coagulated and dried to obtain a solid deproteinized natural rubber, and then used as a raw material for various rubber products.

[0036]

(Preparation of deproteinized natural rubber latex)

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.
3%] was used.

With respect to about 167 parts by weight of the HA latex (100 parts by weight of rubber solids), 0.067 parts by weight of a protease (proteolytic enzyme) and 10% sodium polyoxyethylene lauryl ether sulfate (a surfactant, Kao ( KP4401) (15 parts by weight) and diluted with water to prepare a natural rubber latex having a rubber solid content of 30% by weight.

Next, the latex was aged while stirring at room temperature for 16 hours to perform a protein decomposition treatment. About 333 parts by weight of the treated latex (100 parts by weight of rubber solids) was diluted with water to adjust the total amount to 1000 parts by weight (about 10% by weight of rubber solids), and then 10,000 rpm (about 9 parts by weight).
(Gravity acceleration of 000 G) for 30 minutes.

After the centrifugation treatment, the creamy rubber component separated in the upper layer was taken out and further diluted with water to obtain a deproteinized natural rubber latex having a rubber solid content of 60%. The nitrogen content (N%) of this latex according to the Kjeldahl method was 0.045%. [Manufacture of Rubber Gloves] Example 1 1 part by weight of sulfur, 0.5 part by weight of zinc white, and vulcanization with respect to 100 parts by weight of the rubber solid content of the deproteinized natural rubber (DPNR) latex obtained in the above Reference Example 0.5 parts by weight of an accelerator (BZ) and 1 part by weight of an antioxidant (CPL) were blended, and 0.5 part by weight of acetone as a ketone was further blended.

Next, the glove mold heated to 70 ° C.
% Calcium nitrate aqueous solution (coagulant) and dried. After immersing the glove mold in the latex, the mold was lifted and dried at room temperature for several minutes to form a rubber film having a thickness of about 0.2 mm on the surface of the mold. After the formation of the rubber film, 50
The gel film was immersed in hot water of 22 ° C. for 22 minutes to perform gel leaching, and the rubber film was heated in an oven at 100 ° C. for 30 minutes to vulcanize, immersed in 50 ° C. warm water for 230 seconds to perform post leaching, I got gloves.

Examples 2 and 3 Rubber gloves were produced in the same manner as in Example 1 except that the amount of acetone was changed to the amount shown in Table 1. Examples 4 to 6 Rubber gloves were produced in the same manner as in Example 1 except that 2-butanone was used instead of acetone. The amount of 2-butanone is as shown in Table 1.

Comparative Example 1 A rubber glove was prepared in the same manner as in Example 1 except that a commercially available high ammonia (HA) latex (described above) was used instead of the deproteinized natural rubber (DPNR) latex. A rubber glove was prepared in the same manner as in Example 1 except that no control ketone was added.

The above Examples 1-6 and Comparative Examples 1 and subject rubber gloves, a stress M ₅₀₀ Tensile during elongation thereof ^{500% (kgf / cm 2)} , tensile strength T _B (kgf
/ Cm ² ) was measured according to the method described in JIS K 6251 “Tensile test method for vulcanized rubber”. Table 1 shows the above results.

[0044]

[Table 1]

As is apparent from Table 1, according to Examples 1 to 6 in which ketones were added to the deproteinized natural rubber latex, the modulus M of the rubber glove was lower than that of Comparative Example 1 in which no deproteinization treatment was performed. ₅₀₀ could be sufficiently reduced, and could be maintained as low as the control without the ketones. On the other hand, the rubber gloves of Examples 1 to 6, compared to the control, it was possible to improve the strength T _B tensile rubber gloves.

Incidentally, the rubber gloves of Comparative Example 1 are the same as those of Examples 1 to
However, although its tensile strength is higher than that of No. 6, the nitrogen content is high, so that there is a problem that allergy is likely to occur.

[0047]

As described above in detail, according to the deproteinized natural rubber latex of the present invention, a rubber glove having characteristics of improving mechanical strength while maintaining low allergenicity and low modulus. And other natural rubber products. In addition, the rubber glove of the present invention has good workability and fit inherent to natural rubber, and also has the above characteristics, so that it can be suitably used for surgical gloves and the like.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08J 5/00 CEQ C08J 5/00 CEQ B29K 7:00 F term (Reference) 3B033 AB06 AB20 AC03 4F071 AA11 AC07A AF13 AG01 AG31 AH19 BA05 BB01 BC07 4J002 AC011 EE036 EE046 FB051 FB081 FD010 FD030 FD140 FD150 FD200 GB00 GC00 HA07 4J100 AS03P CA01 GC35 JA57

Claims (3)

[Claims] 1. A deproteinized natural rubber latex characterized in that ketones are contained in the deproteinized natural rubber latex. 2. The deproteinized natural rubber latex according to claim 1, wherein the content of the ketone is 0.1 to 10 parts by weight based on 100 parts by weight of the rubber solid content of the latex. 3. A rubber glove formed using the deproteinized natural rubber latex according to claim 1.