JP2001310902A - Deproteinization agent, deproteinized natural rubber latex using the same and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an agent capable of highly deproteinizing, keeping a latex for a long time after deproteinization and also giving a sufficient heat-sensitive coagulation property, to provide a deproteinized natural rubber latex having both stability and the heat-sensitive coagulation property, and to provide a method of producing the latex. SOLUTION: The deproteinization agent for natural rubber contains a protease and a polymer which has a functional group such as a hydroxy group, a carboxyl group, and the like and a main chain of C100-5,000,000. Rubber particles in the natural rubber latex are washed by adding the agent to this latex.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a deproteinizing agent for removing proteins in natural rubber, and a method for producing a deproteinized natural rubber latex using the same.

[0002]

2. Description of the Related Art Natural rubber has high elongation, high elasticity,
Because it has characteristics such as good film strength, it can be used from industrial products such as automobile tires, belts, adhesives and adhesives, household products such as gloves, medical devices such as catheters, nursing devices, and contraceptive devices. It is used in a wide range of fields, such as For example, for gloves, the so-called direct method, in which the (a) type is directly immersed in natural rubber latex, the so-called anodic adhesion method, in which the anode adhesive is applied to the type (b) and the type is immersed in the natural rubber latex, (c) Processing is performed using a so-called heat-sensitive method or the like, in which a preheated mold is immersed in a natural rubber latex containing a heat-sensitizing agent, and a gel is sequentially deposited on the mold surface.

[0003] These production methods are appropriately selected depending on the kind of the above-mentioned glove product. In general, when a product such as a condom having a very thin rubber film is produced, the direct method is used. The anode adhesion method is used to produce gloves for work, and the heat-sensitive method is used to produce thicker gloves such as work gloves. By the way, in recent years, when medical devices such as surgical gloves and various catheters made of natural rubber are used, after a few hours, dyspnea and anaphylactoid symptoms (angioedema, urticaria, collapse, cyanosis, etc.) immediate ( (Type I) It has been reported to cause allergy. It is presumed that such an immediate allergy is induced by a protein in natural rubber as an antigen.

[0004] Further, since the type and amount of the protein contained in the natural rubber latex vary depending on the place of origin and the time of production of the natural rubber latex, the quality and vulcanization characteristics of the natural rubber may vary, This has the effect of reducing mechanical properties such as creep properties and aging resistance of natural rubber and electrical properties such as insulation. Therefore, in view of the above problems, it is important to remove proteins from natural rubber latex to a high degree, and to obtain so-called deproteinized natural rubber latex which has been highly deproteinized in this way.

[0005]

SUMMARY OF THE INVENTION Japanese Patent Application Laid-Open No. 6-56902
Japanese Patent Application Publication No. JP-A-2005-115122 discloses a method in which a protease is added to a natural rubber latex to decompose a protein, followed by centrifugation to separate a creamy deproteinized natural rubber component. According to this method, the protein in the natural rubber latex can be removed at a very high level, and the protein content is such that the nitrogen content (N%) measured by the Kjeldahl method is 0.1% by weight or less. It is reduced until becomes.

[0006] However, the deproteinized natural rubber latex obtained by the above method contains a large amount of a surfactant in order to prevent destabilization of the latex due to removal of protein and coagulation of the resulting rubber particles. Therefore, the dispersion state of the rubber particles in the latex is excessively stable. Therefore, the deproteinized natural rubber latex obtained by the above method cannot be used to form a film depending on the prescription, such as a heat-sensitive method which has conventionally been widely used, since the coagulation of rubber particles cannot be advanced with a normal heat-sensitive agent. There was a problem that can not be. In addition, in order to impart heat sensitivity to the deproteinized natural rubber latex obtained by the above method, a heat-sensitizing agent or an anode coagulant, which is not widely used, is used in a specific combination and in a larger amount than in a normal formulation. It becomes difficult to control the heat-sensitive properties, or the long-term stability of the latex may be impaired. A problem arises in that a material having sufficient water resistance cannot be obtained.

Accordingly, an object of the present invention is to realize a high degree of deproteinization of natural rubber latex, maintain the stability of the deproteinized natural rubber latex for a long period of time, and obtain a sufficient amount of the latex. An object of the present invention is to provide a deproteinizing agent capable of imparting excellent heat-sensitive coagulability, and to provide a method for producing a deproteinized natural rubber latex having both latex stability and heat-sensitive coagulability.

[0008]

Means for Solving the Problems and Effects of the Invention The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and as a result, together with a protease commonly used for deproteinization of natural rubber latex, a predetermined amount of When a deproteinization treatment is performed by blending a water-soluble polymer of the present invention, a natural rubber latex highly deproteinized by the treatment is obtained, and the latex maintains long-term stability, and The inventors have found a completely new fact that they also exhibit sufficient heat-sensitive coagulability, and have completed the present invention.

That is, the deproteinizing agent of the present invention is characterized by containing a protease and one or more water-soluble polymers as active ingredients. According to the deproteinizing agent of the present invention, despite its simple configuration as described above,
Advanced deproteinization of natural rubber latex can be realized, the stability of natural rubber latex after deproteinization can be maintained for a long time, and furthermore, the deproteinized natural rubber latex can be further improved. Sufficient heat-sensitive coagulability.

The water-soluble polymer in the deproteinizing agent of the present invention has, for example, at least one type of hydrophilic functional group selected from the group consisting of a hydroxyl group, a carboxyl group, an amide group and an ester bond, and has a carbon number of the main chain. Is 100-500
0000 or a salt thereof. By using the above-mentioned polymer as the water-soluble polymer, it is possible to simultaneously provide the deproteinized natural rubber latex with long-term stability and with sufficient heat-sensitive coagulation. The above-mentioned polymers may be used alone or as a mixture of two or more.

In the deproteinizing agent of the present invention, the content ratio of the protease and the water-soluble polymer is preferably from 1: 1 to 1: 200 by weight. The deproteinized natural rubber latex of the present invention is characterized in that it has been subjected to deproteinization using the deproteinizing agent of the present invention.
On the other hand, the method for producing a deproteinized natural rubber latex according to the present invention is characterized in that the deproteinizing agent of the present invention is added to a natural rubber latex and the rubber particles in the latex are washed.

The deproteinized natural rubber latex obtained by the method of the present invention is a stable latex from which proteins are highly removed. Further, since the latex shows sufficient heat sensitivity, it is suitable as a raw material for producing thick and thick rubber products such as working gloves and catheters. In the method for producing a deproteinized natural rubber latex according to the present invention, the amount of the deproteinizing agent added is:
It is preferably 0.001 to 10 parts by weight based on 100 parts by weight of the rubber solid content in the natural rubber latex.

[0013]

Next, the present invention will be described in detail. [Deproteinizing Agent] As described above, the deproteinizing agent of the present invention contains a protease and one or more water-soluble polymers as active ingredients. (Protease) As the protease used in the deproteinizing agent of the present invention, conventionally known proteases can be used and are not particularly limited. For example, alkali proteases and the like are preferable. The protease may be derived from a bacterium, a filamentous fungus, a yeast, or the like, but among these, a bacterium is preferable, and a Bacillus genus is particularly preferable. Also,
It is also possible to use enzymes such as lipase, esterase, amylase, laccase and cellulase in combination.

[0014] Among them, protease KAP manufactured by Kao Corporation having resistance to surfactants is particularly preferred.
Is preferably used. When an alkaline protease is used, its activity [Anson-hemoglobin method (An
measured by the improved method of son. ML, J. Gen. Physiol., 22, 79 (1938)] is in the range of 0.1 to 50 APU / g, preferably 1 to 25 APU / g. .

[0015] The amount of the protease used varies depending on the amount of the deproteinizing agent of the present invention described later and the activity of the protease itself, and is not particularly limited. However, in general, it is preferable to adjust the amount of the deproteinizing agent so that the protease content is 0.0001 to 20 parts by weight based on 100 parts by weight of the rubber component in the natural rubber latex. , And more preferably 0.001 to 10 parts by weight. When the content of the protease is within the above range, the protein in the latex can be sufficiently degraded while maintaining the activity of the protease, or an effect commensurate with the amount of the protease used can be effectively exhibited, and the cost can be reduced. It will be advantageous.

(Water-soluble polymer) The water-soluble polymer which can be used in the deproteinizing agent of the present invention is, for example, at least one selected from the group consisting of a hydroxyl group, a carboxyl group, an amide group and an ester bond, as described above. A polymer having one kind of hydrophilic functional group and having 100 to 5,000,000 carbon atoms in the main chain, or a salt thereof may be mentioned. More specifically, among (meth) acrylic acid-based polymers, alginic acid-based polymers, vinyl-based polymers, polyethylene oxide-based polymers, cellulose-based polymers and the like, those having 100 to 5,000,000 carbon atoms in the main chain can be mentioned.

Examples of the (meth) acrylic acid-based polymer include sodium polyacrylate, sodium polymethacrylate, ammonium polyacrylate, and ammonium polymethacrylate. Examples of the alginic acid-based polymer include sodium alginate, ammonium alginate, potassium alginate, propylene glycol alginate, and the like. Examples of the vinyl polymer include polyvinyl alcohol (PVA) and potassium salt of PVA (saponified product).

Examples of the polyethylene oxide-based polymer include polyethylene oxide and polypropylene oxide. Examples of the cellulosic polymer include carboxymethyl cellulose (CMC),
Hydroxyethyl cellulose, hydroxypropyl cellulose, cellulose xanthate and the like can be mentioned. The water-soluble polymer in the deproteinizing agent of the present invention is not limited to the above-mentioned polymers. For example, protein-based water-soluble polymers such as casein, polyacrylamide, or sodium starch glycolate, starch phosphorus Sodium acid esters and the like can also be used.

Further, a small amount of a surfactant may be added to the deproteinizing agent of the present invention together with the above-mentioned polymer. However, when the content of the surfactant is large, the stability of the latex becomes excessive, and the effect of the present invention may be impaired. Therefore, it is necessary to pay close attention to the compounding amount. In addition, as a stabilizer used for deproteinization of a conventional natural rubber latex, a “polyoxyethylene nonionic surfactant” is known.
However, the hydrophobic group of such a surfactant is only one in which several to about 30 ethylene glycols are bonded, and thus is not included in the category of the water-soluble polymer according to the present invention.

The amount of the water-soluble polymer varies depending on the amount of the deproteinizing agent of the present invention described later and the properties of the water-soluble polymer itself, and is not particularly limited. Absent. However, in general, the amount of the deproteinizing agent used is adjusted so that the content of the water-soluble polymer is 0.1 to 10 parts by weight based on 100 parts by weight of the rubber component in the natural rubber latex. And more preferably adjusted to be 0.5 to 3 parts by weight. When the content of the water-soluble polymer is within the above range, both stability and heat-sensitive coagulation properties of the deproteinized natural rubber latex can be achieved.

(Proportion of Protease and Water-Soluble Polymer) The protease and the water-soluble polymer in the deproteinizing agent of the present invention are contained in a weight ratio of 1: 1 to 1: 200 as described above. You. If the content of the protease is below the above range, or if the content of the water-soluble polymer exceeds the above range, a sufficient deproteinization effect may not be obtained, or the heat-sensitive coagulability of the latex may be impaired. .

On the other hand, if the protease is contained beyond the above range, there is almost no influence on the deproteinization effect, and on the contrary, there is a possibility that disadvantages such as an increase in cost may be involved. Also,
If the content of the water-soluble polymer is below the above range, the stability of the latex may be impaired. The content ratio of the protease and the water-soluble polymer in the deproteinizing agent of the present invention is preferably from 1: 5 to 1: 100, more preferably from 1:10 to 1:50, in the above range. preferable.

[Deproteinized Natural Rubber Latex and Production Method Thereof] As described above, the deproteinized natural rubber latex of the present invention has been deproteinized using the deproteinizing agent of the present invention. It is characterized by the following. Further, as described above, the method for producing a deproteinized natural rubber latex according to the present invention comprises adding the deproteinizing agent of the present invention to the natural rubber latex to ripen it, and then washing the rubber particles in the latex. It is characterized by doing.

(Natural Rubber Latex) The natural rubber latex used for producing the deproteinized natural rubber latex of the present invention may be either a field latex obtained as a rubber sap or a concentrated ammonia storage latex. (Blending amount of deproteinizing agent) The blending amount of the deproteinizing agent when deproteinizing natural rubber latex is determined by the protease content in the deproteinizing agent and the protease activity. However, it is usually set in the range of 0.0001 to 10 parts by weight, preferably 0.001 to 10 parts by weight, based on 100 parts by weight of the rubber component in the latex.

If the amount of the deproteinizing agent is less than the above range, the effect of deproteinization becomes insufficient, and the possibility of immediate allergy caused by protein may not be sufficiently removed. Conversely, even if the deproteinizing agent is blended beyond the above range, the expected effect may not be exhibited, or the effect corresponding to the cost may not be obtained.

(Deproteinization Treatment) As described above, the deproteinization treatment is carried out by adding the deproteinizing agent of the present invention to the natural rubber latex as a raw material, and for several tens of minutes to about one week, preferably one week.
It is performed by aging for about 3 days. By such aging, a protein decomposition treatment for natural rubber latex can be realized. This aging treatment may be performed while stirring the latex, or may be performed in a state where the latex is left still. Moreover, you may adjust temperature as needed. In order to make the activity of the enzyme sufficient, the temperature is preferably from 5 to 90 ° C, more preferably from 20 to 60 ° C. If the temperature is lower than 5 ° C., the enzyme reaction may not proceed,
Conversely, if the temperature exceeds 90 ° C., the enzyme may be deactivated.

The washing (purification) treatment of the rubber particles in the latex after the deproteinization treatment is not particularly limited. For example, the latex is concentrated by centrifugation, ultrafiltration, or the like, and transferred to water. For example, a treatment for separating a non-rubber component such as a decomposed protein product from rubber particles in latex, and a treatment for aggregating and separating rubber particles with an acid or the like. Among them, purification by centrifugation is most preferable from the viewpoint of purification accuracy and efficiency.

When the washing (purification) treatment after the deproteinization treatment is carried out by centrifugation, the treatment conditions are 5,000 to 5,000.
15,000 rpm for 1 to 60 minutes (or 10
If the cream fraction separated into the upper layer by centrifugation is re-dispersed in water of the same volume as the cream fraction, sufficient deproteinization effect can be obtained. In addition, the stability and heat-coagulability of the latex can be sufficiently maintained by the water-soluble polymer which is added in advance before the deproteinization treatment and remains after the purification treatment.

(Degree of Deproteinization) The degree of deproteinization achieved in the present invention is such that the nitrogen content (N%) of the rubber latex after deproteinization by the Kjeldahl method is 0.1%.
%, Preferably 0.5% or less, more preferably 0.1% or less.
It is adjusted so as to be 02% or less. When the nitrogen content exceeds the above range, the degree of deproteinization becomes insufficient, and the occurrence of allergy may not be sufficiently suppressed.

The degree of deproteinization can also be confirmed by the presence or absence of protein-based absorption in the infrared absorption spectrum and the degree of absorption. In the rubber treated with the deproteinizing agent of the present invention, absorption at 3320 cm ⁻¹ derived from short-chain peptides or amino acids may be observed,
The smaller the absorption at 3280 cm ⁻¹ derived from the high molecular polypeptide which causes allergy, the smaller is preferable.
More preferably, no absorption is observed at cm ^-1 .

[Preparation of heat-sensitive coagulable latex] The deproteinized natural rubber latex of the present invention can be used for working by mixing a vulcanizing compound such as a vulcanizing agent with a heat-sensitizing agent. It can be used as a raw material when manufacturing thick or thick rubber products such as gloves and catheters by a thermal method. Examples of the vulcanization-based compounding agent include various conventionally known additives such as a vulcanizing agent, a vulcanization accelerator, a vulcanization acceleration aid, and a vulcanization retarder.

Examples of the vulcanizing agent include sulfur and organic sulfur-containing compounds. 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 latex. preferable. Examples of the vulcanization accelerator include PX (zinc N-ethyl-N-phenyldithiocarbamate), PZ (zinc dimethyldithiocarbamate), 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 compounding 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 latex.

Examples of the vulcanization accelerating aid include zinc white. The 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 latex. Examples of the thermal sensitizer include various conventionally known thermal sensitizers such as an inorganic or organic ammonium salt, and a water-soluble polymer having a cloud point of from room temperature to 100 ° C. 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.

In order to prepare thick and thick rubber products such as working rubber gloves and catheters using the deproteinized natural rubber latex of the present invention, the above latex containing a coagulant such as a heat sensitive agent in advance is prepared. Then, a method of dipping a preheated mold may be adopted. The amount of the heat-sensitizing agent, the preheating temperature of the mold, and the like may be adjusted according to a conventional method. [Other additives] The deproteinized natural rubber latex of the present invention may be subjected to a deproteinization treatment with other compounding agents other than the vulcanizing compounding agent and the heat-sensitive agent according to the properties required for rubber products. It can be added later.

As such other additives, various conventionally known additives such as an antioxidant, a filler, a plasticizer, a softener, a reinforcing agent and the like can be blended. As anti-aging agents, generally, CPL (hindered phenol),
Antage W-300 [4,4'-butylidenebis-
Non-staining phenols such as (3-methyl-6-t-butylphenol)] are preferred, but amines such as octylated diphenylamine may also be used. The compounding amount of the antioxidant is preferably about 0.5 to 3 parts by weight based on 100 parts by weight of the rubber solid content of the latex.

As the filler, for example, kaolin clay,
Hard clay and calcium carbonate are exemplified. The 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 latex. In addition, a dispersant may be blended in order to improve the dispersion of the additives in the rubber latex. Such dispersants include, for example, various surfactants, especially anionic surfactants. The compounding amount of the dispersant is preferably about 0.3 to 1.0% by weight of the weight of the component to be dispersed.

When the content of the above surfactant is increased, the stability of the latex becomes excessive, and the effect of the present invention, which achieves both stability and heat-sensitive coagulation, may be impaired. Therefore, when mixing a surfactant as a dispersant, it is necessary to pay sufficient attention to the amount of the surfactant.

[0038]

Next, the present invention will be described with reference to examples and comparative examples. Example 1 (Preparation of Deproteinizing Agent) An alkaline protease and ammonium polyacrylate as a water-soluble polymer were
The mixture was mixed at a weight ratio of 2:98 to obtain a deproteinizing agent.

(Production of deproteinized natural rubber latex) After diluting natural rubber high-ammonia latex so as to have a rubber solid content of 30% by weight, the above-mentioned deproteinizing agent was added, and the mixture was added at 30 ° C. It was left standing for 24 hours. After standing, the latex was centrifuged at 13000 rpm for 30 minutes, and the cream separated in the upper layer was taken out and redispersed in the same volume of water as the cream to obtain a deproteinized natural rubber latex.

(Preparation of heat-sensitive compounded latex)
Rubber solid content 1 in the above deproteinized natural rubber latex
1 part by weight of colloidal sulfur (vulcanizing agent) dispersed in water, 1 part by weight of zinc white (vulcanization accelerating aid), and vulcanization accelerator BZ (zinc dibutyldithiocarbamate, 1 part by weight of "Noxeller BZ" manufactured by Uchi Shinko Chemical Co., Ltd.) and 0.3 part by weight of a nonionic surfactant ("Emulbin" manufactured by Kao Corporation) are added, followed by aging at 40 ° C. for 24 hours. Was.

After aging, the compounded latex was added to 2
After cooling to 5 ° C. and adjusting the pH to 8.5 with 10% formalin, polyvinyl methyl ether as a heat-sensitizing agent was added in an amount of 0.1 to 100 parts by weight of the rubber solid content in the latex.
5 parts by weight were added. (Preparation of rubber film) Next, a ceramic test tube having a diameter of 5 cm preheated to 90 ° C was immersed in the thus obtained compounded latex for heat-sensitive molding for 30 seconds, and vulcanized at 100 ° C for 90 minutes to obtain a rubber film. Was prepared.

Examples 2 to 5 Examples of the deproteinizing agent include alkaline protease, sodium alginate as a water-soluble polymer (Example 2), sodium polyacrylate (Example 3), and carboxymethyl cellulose (Example 2). 4) Or a mixture of ammonium polyacrylate (Example 5) at a weight ratio of 2:98 was used. Then, the heat treatment was performed in the same manner as in "Production of deproteinized natural rubber latex" and "Preparation of heat-sensitive compounded latex" in Example 1, except that the above-mentioned deproteinizing agent was used. A compounded latex was obtained.

Next, a rubber film was prepared in the same manner as in "Preparation of rubber film" in Example 1 except that the compounded latex for thermoforming was used. In Example 5, after the redispersion process in “Production of deproteinized natural rubber latex”, the centrifugation process and the redispersion process were performed again under the same processing conditions as above (that is, the centrifugation process was performed). Performed twice). Comparative Examples 1 to 3 The deproteinizing agent was obtained by mixing alkali protease and polyoxyethylene oleyl ether (POE oleyl ether) as a nonionic surfactant at a weight ratio of 2:98 (Comparative Example 1); A mixture of an alkaline protease and a nonionic surfactant polyoxyethylene sorbitan monooleate (POE sorbitan monooleate) in a weight ratio of 2:98 (Comparative Example 2); or A mixture of a nonionic surfactant, polyoxyethylene nonylphenyl ether (POE nonylphenyl ether), in a weight ratio of 2:98 was used.

Next, a treatment was carried out in the same manner as in "Production of deproteinized natural rubber latex" and "Preparation of heat-sensitive compounded latex" in Example 1 except that the above-mentioned deproteinizing agent was used. Thus, a compounded latex for heat-sensitive molding was obtained. Next, a rubber film was prepared in the same manner as in "Preparation of Rubber Film" in Example 1 except that the compounded latex for heat-sensitive molding was used. Incidentally, the compounded latex for heat-sensitive molding in Comparative Examples 1 to 3 contained a total of 1.28 parts by weight of a nonionic surfactant based on 100 parts by weight of a rubber solid content.

Control (Blank test) A high ammonia latex of natural rubber was diluted to a rubber solids concentration of 30% by weight, and then diluted at 13000 r.
The mixture was centrifuged at pm for 30 minutes, the cream separated in the upper layer was taken out, and redispersed in the same volume of water as the cream to obtain latex. 1 part by weight of colloidal sulfur (vulcanizing agent) dispersed in water, 1 part by weight of zinc white (vulcanization accelerating aid), and vulcanization accelerator BZ with respect to 100 parts by weight of a rubber solid content in the latex. (Zinc dibutyldithiocarbamate, 1 part by weight of “Noxeller BZ” manufactured by Ouchi Shinko Chemical Co., Ltd.) and 0.3 part by weight of a nonionic surfactant (“Emulbin” manufactured by Kao Corporation)
Aged at 40 ° C. for 24 hours.

Further, after aging, the compounded latex was added to 2
After cooling to 5 ° C. and adjusting the pH to 8.5 with 10% formalin, polyvinyl methyl ether as a heat-sensitizing agent was added in an amount of 0.1 to 100 parts by weight of the rubber solid content in the latex.
5 parts by weight were added. (Preparation of rubber film) Next, a ceramic test tube having a diameter of 5 cm preheated to 90 ° C was immersed in the thus obtained compounded latex for heat-sensitive molding for 30 seconds, and vulcanized at 100 ° C for 90 minutes to obtain a rubber film. Was attempted.

With respect to the above Examples 1 to 5, Comparative Examples 1 to 3, and the control, the active ingredients of the deproteinizing agent used and the content ratio thereof, the amount of the deproteinizing agent, the amount of the surfactant,
Table 1 shows the number of times of centrifugation. In Table 1,
The “content ratio” in the “deproteinizing agent” column indicates the content ratio (% by weight) of the components listed in the “active ingredient” column. The “blending amount” in the same column is the blending amount (parts by weight) of the deproteinizing agent with respect to 100 parts by weight of the rubber solid content of the latex.

In the "Surfactant" column, the "content" is
Amount (parts by weight) of nonionic surfactant based on 100 parts by weight of rubber solid content of latex after addition of heat-sensitizer
It is. In addition, the surfactant contained in the “deproteinizing agent” was also added to the “blending amount” in the “surfactant” column in Comparative Examples 1 to 3.

[0049]

[Table 1]

[Evaluation of Properties of Natural Rubber Latex] The deproteinized natural rubber latex obtained in the above Examples and Comparative Examples and the natural rubber latex after the blank test were subjected to the Kjeldahl method to determine the total content of the latex in the solid content. The amount of nitrogen (nitrogen content, N%) was determined. [Evaluation of Physical Properties of Rubber Film] The rubber films obtained in the above Examples and Comparative Examples were punched out to prepare dumbbell-shaped No. 4 test pieces specified in JIS K6251 (Tensile test method for vulcanized rubber).

Next, according to the test method described in JIS K6251, the tensile stress at 500% elongation (500% modulus, M ₅₀₀ , unit: MPa), the tensile strength T _B (MPa) and the elongation at break E _B (%) Was measured. In addition, the thickness of the rubber films obtained in the above Examples and Comparative Examples was measured. Table 2 shows the above results.

[0052]

[Table 2]

As is clear from Tables 1 and 2, according to Examples 1 to 5 using the deproteinizing agent comprising the combination of the protease and the water-soluble polymer, the nitrogen content was low (that is, the nitrogen content was high). Deproteinization could be realized), and a rubber film having a sufficient thickness as a working rubber glove or catheter and maintaining the excellent mechanical strength inherent to natural rubber could be obtained. On the other hand, in Comparative Examples 1 to 3, a rubber film having a sufficient film thickness could not be obtained due to the excessive stabilizing action caused by the presence of the surfactant.

In the control (blank test), the stability of the latex was remarkably reduced by the deproteinization treatment, so that a sufficient film could not be formed.

[Procedure amendment]

[Submission date] April 17, 2001 (2001.4.1
7)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0048

[Correction method] Change

[Correction contents]

In the "Surfactant" column, the "content" is
Amount (parts by weight) of nonionic surfactant based on 100 parts by weight of rubber solid content of latex before addition of heat-sensitizer
It is. In addition, the surfactant contained in the “deproteinizing agent” was also added to the “blending amount” in the “surfactant” column in Comparative Examples 1 to 3.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0049

[Correction method] Change

[Correction contents]

[0049]

[Table 1]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 89:00) C08L 89:00) (72) Inventor Akihiko Hamada 3-chome, Wakihama-cho, Chuo-ku, Kobe-shi, Hyogo Prefecture. No. 6-9 Sumitomo Rubber Industries, Ltd. F term (reference) 4B050 CC10 LL05 4B064 CA21 CB05 DA16 4J002 AA031 AB011 AB021 AB031 AB041 AD002 AD032 BE021 BG011 BG131 FD202 GE00

Claims (6)

[Claims] 1. A deproteinizing agent comprising a protease and one or more water-soluble polymers as active ingredients. 2. A polymer wherein the water-soluble polymer has at least one hydrophilic functional group selected from the group consisting of a hydroxyl group, a carboxyl group, an amide group and an ester bond, and has a main chain carbon number of 100 to 5,000,000. 2. The deproteinizing agent according to claim 1, which is a salt thereof. 3. The content ratio of said protease to said water-soluble polymer is from 1: 1 to 1: 200 by weight.
The deproteinizing agent according to the above. 4. A deproteinized natural rubber latex which has been deproteinized using the deproteinizing agent according to claim 1. 5. A deproteinizing agent according to any one of claims 1 to 3, which is added to a natural rubber latex to ripen it.
A method for producing a deproteinized natural rubber latex, comprising washing rubber particles in the latex. 6. The amount of said deproteinizing agent added is 0.00 0.00 parts by weight of rubber solids in natural rubber latex.
The method for producing a deproteinized natural rubber latex according to claim 5, wherein the amount is 1 to 10 parts by weight.