JP2008056858A - Foamed elastomer and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a foamed elastomer which efficiently modifies/inactivates allergens contained in natural rubber latexes, reduces the characteristic odor of the natural rubber latexes, and has an effect for inactivating other allergens such as mite antigens, and to provide a method for producing the same. <P>SOLUTION: This method for producing the foamed elastomer containing tannic acid comprises mixing a latex raw material containing natural rubber latex with at least a vulcanizing agent and tannic acid, applying a gas-containing treatment to the mixture, molding and then drying the product, or immersing a foamed elastomer containing the natural rubber elastomer in a tannic acid solution, and then drying. The foamed elastomer preferably contains the tannic acid in an amount of 0.01 to 10 mass%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a foamed elastomer with reduced allergens and odors contained in natural rubber latex and a method for producing the same.

  Usually, natural rubber latex is added to a white sap collected from rubber trees (Hevea brasiliens) with a small amount of ammonia and preservatives to prevent coagulation, and then concentrated to vulcanize and accelerate the vulcanization. It is manufactured by adding an agent and heating.

  This natural rubber latex has excellent mechanical properties (elongation, elasticity, film strength, etc.) and good processability, so it can be used for medical devices such as medical gloves, various catheters, and adhesive bandages. It is used in a wide range of fields such as daily necessities such as cooking gloves, nursing tools, and contraceptives. Further, foam rubber (in the present invention, foamed elastomer) coagulated by mixing air with natural rubber latex is excellent in compression characteristics, vibration damping characteristics, cushioning properties, etc., so mattress, pillow, mattress, It is used for cushions for chairs and seats, carpet lining, and door packing.

  However, in recent years, contact with natural rubber latex products has been reported to cause pruritus, urticaria, nose / eye / throat symptoms, asthma attacks, anaphylactic shock and other allergies (hereinafter referred to as latex allergy). It is a problem. Natural rubber latex contains about 1.5% protein, and it is known that this protein is a causative substance (allergen) of latex allergy as described above. This protein remains in the final natural rubber product, elutes during use, and acts as an allergen.

  Therefore, various methods for reducing latex allergy have been proposed. For example, in Patent Document 1 below, an immersed product made of natural rubber latex is brought into contact with water vapor at 200 ° C. or higher, and the amount of eluted protein is reduced. A method for producing a hypoallergenic natural rubber product characterized by reducing the amount of oil is disclosed.

  The following Patent Document 2 discloses the production of a de-allergenized natural rubber latex characterized in that a protein denaturing agent comprising a urea compound is added to a fresh natural rubber latex, and the protein in the latex is removed after the denaturation treatment. A method is disclosed.

  Patent Document 3 listed below discloses a method for producing a hypoallergenic natural rubber latex, characterized by adding a caustic alkali to a natural rubber latex that has been deproteinized in advance and then performing a saponification treatment.

  Patent Document 4 listed below discloses a natural rubber that has been subjected to a protein degradation treatment, and has a number average molecular weight of 4500 or more, and a hypoallergenic natural rubber characterized by not detecting a protein degradation product. ing.

  Patent Document 5 listed below contains a deproteinized natural rubber from which the protein content has been removed to a level of 0.1% or less in terms of nitrogen content, in a proportion of 30% by weight or more based on the total rubber solid content. Disclosed is a foam rubber characterized by being formed from latex.

  Patent Document 6 listed below discloses a deproteinized natural rubber latex sponge characterized in that the nitrogen content derived from protein contained in natural rubber latex is reduced to 0.05% or less.

In Patent Document 7 below, a natural rubber latex product is exposed to carbon dioxide supercritical conditions, extracted for 12 to 18 minutes, and then subjected to a reduced pressure time of 30 minutes or more, followed by an atmospheric pressure reducing odor, allergic protein extraction and removal method. Is disclosed.
JP 2005-126488 A JP 2005-15614 A JP 2003-20301 A JP 2002-145903 A JP 2000-336102 A JP 2000-7708 A JP 2002-69102 A

  However, in the methods disclosed in Patent Documents 1 to 6, it is difficult to completely decompose, remove or denature proteins (allergens) contained in natural rubber latex, and although some allergen reducing effect is recognized, it is sufficiently satisfactory. It was difficult to obtain an effect that could be achieved. The natural rubber latex product has a peculiar odor, but the odor cannot be removed by the above method.

  On the other hand, the method disclosed in Patent Document 7 can remove allergen proteins and remove odors, but requires special equipment and has a problem that the production cost becomes very high. It was.

  Furthermore, foamed elastomers are used for mattresses, pillows, mattresses, cushions for chairs and seats, carpet linings, etc., so new allergen problems such as ticks also occur. It was necessary to perform processing.

  Therefore, the object of the present invention is that allergens contained in natural rubber latex are efficiently modified and inactivated, the odor peculiar to natural rubber latex is reduced, and further, allergens such as mite antigens are inactivated. An object of the present invention is to provide a foamed elastomer having an effect and a method for producing the same.

  In order to achieve the above object, the foamed elastomer of the present invention is characterized by containing natural rubber latex as a latex raw material and containing tannic acid.

  By containing tannic acid, the foamed elastomer of the present invention can efficiently denature and inactivate proteins (allergens) contained in natural rubber latex to reduce latex allergy and deodorize natural rubber latex-specific odors. be able to. Tannic acid also has an inactivating activity against other allergens such as mite antigens, and thus has an inhibitory effect on other allergies.

  The foamed elastomer of the present invention preferably contains 0.01 to 10% by mass of the tannic acid. According to this aspect, it is possible to obtain an effect of reducing latex allergen, deodorizing odor peculiar to natural rubber latex, and inactivating effect of other allergens such as mite antigens without impairing workability and processability.

  The foamed elastomer of the present invention is preferably used as a core material or cushion material selected from pillows, mattresses, mattresses, beds, bed pads, cushions, cushions, chairs, strollers, swimwear, and brassieres.

  One of the methods for producing a foamed elastomer is characterized in that at least a vulcanizing agent and tannic acid are mixed with a latex raw material containing natural rubber latex, subjected to an aeration treatment, and then molded and dried.

  According to this production method, since the latex raw material containing natural rubber latex and tannic acid can be uniformly mixed, allergens and odors contained in natural rubber latex can be efficiently reduced, and mite antigens and the like can be reduced. Inactivation effects of other allergens can also be imparted. Further, since tannic acid is encapsulated in the foamed elastomer, the tannic acid does not elute due to sweat or washing, and the above effect can be maintained for a long period of time.

  In the method for producing a foamed elastomer of the present invention, the tannic acid is preferably adjusted to an aqueous solution having a pH of 6 to 10 and added.

  Moreover, it is preferable to use ammonia as a pH adjuster of the aqueous solution of tannic acid.

  According to these embodiments, since the coagulation of the latex raw material that occurs when tannic acid is added can be prevented, workability is not impaired.

  Another method for producing a foamed elastomer of the present invention is characterized in that a foamed elastomer containing natural rubber latex is immersed in a tannic acid solution and dried.

  According to this production method, the allergen and odor contained in the natural rubber latex can be easily reduced, and further, the inactivation effect of other allergens such as mite antigen can be imparted.

  According to the present invention, not only allergens causing latex allergy are sufficiently reduced, but also the odor peculiar to natural rubber latex is reduced, and further, it has inactivation activity against other allergens such as mite antigens. A foamed elastomer can be provided.

  The natural rubber latex (hereinafter referred to as NR latex) used as a raw material for the foamed elastomer of the present invention is any of field latex, ammonia-treated latex, and deproteinized natural rubber (DPNR) latex obtained by performing a conventionally known deproteinization treatment. It may be. For example, by using a deproteinized natural rubber (DPNR) latex, a higher latex allergen reduction effect can be obtained.

  In the present invention, only the above NR latex may be used as a latex raw material, but if necessary, styrene-butadiene rubber latex (SBR latex), butadiene rubber (BR), nitrile rubber (NBR), chloroprene rubber ( Various synthetic latexes such as CR), isoprene rubber (IR), IR latex, DPL (depolymerized latex), EPDM (ethylene propylene diene rubber), acrylic emulsion, polyurethane latex and the like can also be used. When the NR latex and the synthetic latex are used in combination, the blending ratio of each latex may be appropriately selected according to the purpose. However, in order to take advantage of the good characteristics of the NR latex, the NR latex is usually converted into a rubber solid content. It is preferable that it contains 50 mass% or more.

  The tannic acid used in the present invention is a compound represented by the following general formula [1], is easily dissolved in water, and the aqueous solution is acidic. In addition, it shows good solubility in alcohol, acetone, glycerin and the like, and is insoluble in petroleum ether, anhydrous ether, chloroform and the like.

(In the above general formula [1], R represents the same or different hydrogen atom or a functional group composed of a compound represented by the following general formula [2].)

(In the general formula [2], A represents a hydrogen atom which may be the same or different or a functional group composed of a compound represented by the following general formula [3].)

  Tannic acid is derived from plant tannins such as gallic and pentaploids, and is sometimes sometimes referred to as galloyl gallic acid. In addition, the term “tannic acid” may refer to tannin itself because it is generated by hydrolysis of tannin. Tannic acid obtained from gallic and pentaploids produces gallic acid and trace amounts of glucose by hydrolysis.

  The tannic acid used in the present invention is, for example, a product obtained by extracting gallic or pentaploid with hot water and evaporating the extract to dryness, or extracting and purifying these with an organic solvent. Specifically, at least one selected from hydrolyzed gallotannin, hydrolyzed ellagitannin and condensed tannin is preferably used. For example, the trade name “Tannic acid AL” is used. Commercially available products such as “Fuji Chemical Industry Co., Ltd.” can be used.

  Hereinafter, the manufacturing method of the foamed elastomer of this invention is demonstrated.

  The method for producing a foamed elastomer according to the present invention includes (1) a method in which at least a vulcanizing agent and tannic acid are mixed with a raw material containing NR latex, and after aeration treatment, the resulting product is molded and dried. The foamed elastomer to be contained can be roughly divided into two methods of dipping in a tannic acid solution and drying, but the methods (1) and (2) can also be used in combination.

  First, an example of a basic manufacturing process of a foamed elastomer using NR latex will be described.

  A. Necessary additives selected from a vulcanizing agent, a vulcanization accelerator, a vulcanization acceleration aid, a coagulant, an anti-aging agent, a surfactant, a stabilizer, a foaming agent and the like are added to the latex raw material.

  B. Foam while mixing air. This aeration process can be carried out using a foaming agent such as hydrogen peroxide or a foaming agent in addition to a method using a known foaming device such as a batch type or continuous foaming device. The air content may be appropriately set according to the purpose, but is usually preferably 10 to 60% by volume, more preferably 20 to 40% by volume.

  C. Vulcanization accelerator is mixed and high-speed stirring is performed for about 1 to 2 minutes.

  D. Mix coagulant.

  E. It is molded by various molding methods such as injection into a mold and extrusion onto a belt conveyor. For extruding to the belt conveyor, a method of extruding the latex raw material into a sheet shape on a moving belt and heating it with a heater disposed above the belt conveyance path is employed.

  F. Heating is performed by heating means such as steam. For example, when steam is used, the heating time is preferably 20 to 60 minutes.

  G. Remove the formwork.

  H. Drying by microwave heating or heater heating.

  In the method (1), tannic acid is added in any of the steps A, B, C, and D. The amount of tannic acid added is preferably 0.01 to 10% by mass, more preferably 0.01 to 5% by mass, and most preferably 0.05 to 2% by mass.

  Tannic acid is preferably added as an aqueous solution, but can also be added in powder form. In addition, when there is much addition amount of a tannic acid, it is preferable to add the said aqueous solution by adjusting ammonia to pH 6-10 by adding ammonia etc. A surfactant or the like may be added to the tannic acid aqueous solution.

  In the method (2), after the step H, the following step is further performed.

  I. The foamed elastomer is immersed in a tannic acid solution.

  In this case, the tannic acid concentration of the tannic acid solution is preferably 0.01 to 30% by mass, and more preferably 0.1 to 20% by mass. If the amount of tannic acid added is too small, the allergen contained in the NR latex cannot be sufficiently denatured and inactive, so a sufficient allergen-reducing effect cannot be expected. Deodorizing effect and inactivation of other allergens such as mite antigens We cannot expect effect. Moreover, when there is too much addition amount of tannic acid, it will become easy to damage a foaming elastomer.

  As the solvent, an organic solvent can be used, but water is preferably used from the viewpoint of safety and cost. The immersion temperature is not particularly limited, but is preferably around room temperature in order to prevent damage to the foamed elastomer. What is necessary is just to set immersion time suitably according to immersion temperature so that the solution of a tannic acid may fully osmose | permeate to the center part of a foamed elastomer, Usually, 30 seconds-30 minutes are preferable at room temperature.

  J. et al. Dehydrate to remove the tannic acid solution. The tannic acid solution can be recovered and used repeatedly.

  K. Dehydrate.

  L. Drying by microwave heating or heater heating.

  The steps I, J, K, and L may be performed after the step G.

  The shape of the foamed elastomer of the present invention obtained as described above is not particularly limited, and various shapes such as a sheet shape, a plate shape, a block shape, and a spherical shape can be selected according to the purpose of use. Processing such as drilling and drilling can also be performed.

  The foamed elastomer obtained as described above can be used in various products, for example, core materials such as pillows, mattresses, mattresses, beds, bed pads, cushions, cushions, chairs, strollers, swimwear, brassieres, etc. Or it is preferably used as a cushioning material.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, these Examples do not limit the scope of the present invention.

<Example 1>
Latex (raw material) 100 kg (rubber solid content 60 kg), sulfur (vulcanizing agent), vulcanization accelerator (zinc diethyldithiocarbamate), vulcanization accelerator (zinc salt of 2-mercaptobenzothiazole), anti-aging agent, dispersion The agent was added and stirred uniformly.

  Subsequently, an aqueous solution of tannic acid (hydrolyzable gallotannin, trade name “tannic acid AL”, manufactured by Fuji Chemical Industry Co., Ltd.) was added to the latex raw material so as to be 0.1 mass% with tannic acid.

  This latex composition is aerated using a batch foaming device, added with a vulcanization accelerator (zinc oxide) and stirred at high speed, then added and mixed with a coagulant, and immediately molded. Then, heat treatment was performed with steam (100 ° C.) for 35 minutes.

  The foamed elastomer was taken out from the mold, washed with water, centrifuged and dehydrated, then subjected to microwave drying and tenter drying to obtain a foamed elastomer in which tannic acid was added to the raw material.

<Example 2>
In Example 1, a foamed elastomer was produced without adding an aqueous solution of tannic acid to the latex raw material.

  This foamed elastomer was taken out by being immersed in an aqueous solution in which tannic acid (hydrolyzable gallotannin, trade name “tannic acid AL”, manufactured by Fuji Chemical Industry Co., Ltd.) was dissolved to 0.1 mass% for 5 minutes.

  The foamed elastomer was subjected to centrifugal dehydration, followed by microwave drying and tenter drying to obtain a foamed elastomer to which tannic acid was added by immersion.

<Comparative example>
In Example 1, a foamed elastomer was produced without adding an aqueous solution of tannic acid to the latex raw material. This foamed elastomer was used as a comparative example in the following tests.

<Test Example 1> Inactivation test of mite antigen 100 mg of the foamed elastomer obtained in Examples 1 and 2 and the comparative example was reacted with 2 ml of a mite antigen (Der f1) solution for 24 hours.

  The amount of mite antigen after the reaction was measured by enzyme immunoassay (ELISA method) using a monoclonal antibody. For the ELISA method, anti-Der f1 antibody (manufactured by INDOOR biotechnologies), biotin-labeled anti-Der f1 antibody (manufactured by INDOOR biotechnologies), and enzyme (β-galactosidase) -labeled streptavidin (manufactured by SIGMA) are prepared and performed according to a conventional method. It was.

  That is, after coating each well of the plate with anti-Der f1 antibody, the mite antigen reacted with each sample was added, and biotin-labeled anti-Der f1 antibody was reacted with the mite antigen captured on the plate. The wells were washed, reacted with enzyme-labeled streptavidin and washed again, then a substrate was added, and the enzyme activity of each well was measured by absorbance (wavelength 490 nm).

  Then, a standard curve was prepared from the absorbance of the wells to which the standard antigen was added, and the amount of mite antigen in each aqueous solution was determined. In addition, the inactivation rate was calculated | required on the basis of the value obtained using the foamed elastomer of a comparative example. The results are shown in Table 1.

  From the results of Table 1, it can be seen that mite antigens are inactivated in the foamed elastomers of Examples 1 and 2 to which tannic acid was added.

<Test Example 2> Latex protein inactivation test In Example 2, the foamed elastomer obtained in the same manner as in Example 2 except that the concentration of the tannic acid aqueous solution in which the foamed elastomer was immersed was 10% by mass. The amount of protein was measured by an improved Lowry method (ASTM Method D5712-95), and the amount of allergen protein was measured by an ELISA method (ASTM Method D6499-00) (both measured by LEAP Testing Service, USA). The results are shown in Table 2.

  In general, when the total protein amount is 100 to 50 μg / g, it is said that a healthy person is hardly sensitized. As shown in Table 2, the foamed elastomer of Example 2 has a total protein amount and allergen. It can be seen that the amount of protein is such that there is no risk of sensitization.

<Test Example 3> Odor analysis In Example 1, a foamed elastomer (containing 2% by mass of tannic acid) was obtained in the same manner as in Example 1 except that the amount of tannic acid added to the latex raw material was 2% by mass. ) And the foamed elastomer (with no tannic acid added) obtained in the comparative example, using an odor discriminating device “FF-2A” (trade name, manufactured by Shimadzu Corporation), the odor resembles odor to ammonia. And the odor contribution (measured by Shimadzu Corporation). The measurement results of odor similarity are shown in Table 3, and the measurement results of odor contribution are shown in Table 4.

  The odor similarity represents the similarity of the value obtained by the sensor with respect to the reference gas for the odor obtained from the sample. The odor contribution represents a value obtained by correcting the odor that a person feels to the value obtained by the sensor.

  From the results in Table 3, it can be seen that the foamed elastomer of Example 1 to which tannic acid was added had a low odor similarity to ammonia.

  From the results in Table 4, it can be seen that the foamed elastomer of Example 1 to which tannic acid was added had an ammonia value of 0, and the ammonia odor contained in the odor specific to the NR latex was significantly reduced.

  Since the foamed elastomer of the present invention contains tannic acid, the allergen contained in the natural rubber latex is efficiently modified and inactivated, so there is no concern about latex allergies, and there is also a odor peculiar to natural rubber latex. Furthermore, it has an inactivating activity against other allergens such as mite antigens, and can be used for various products including products that directly touch the human body.

Claims (5)

  A foamed elastomer comprising natural rubber latex as a latex raw material and containing tannic acid.   The foamed elastomer according to claim 1, comprising 0.01 to 10% by mass of the tannic acid.   The foamed elastomer according to claim 1 or 2, wherein the foamed elastomer is used as one kind of core material or cushion material selected from pillows, mattresses, mattresses, beds, bed pads, cushions, cushions, chairs, strollers, swimsuits, and bras.   A method for producing a foamed elastomer, comprising mixing at least a vulcanizing agent and tannic acid with a latex raw material containing natural rubber latex, and after molding with air treatment, molding and drying.   A method for producing a foamed elastomer comprising dipping a foamed elastomer containing natural rubber latex in a solution of tannic acid and drying.