JP4402698B2 - Eraser elastomer composition, method for producing the same, and eraser using the composition - Google Patents

Description

The present invention relates to an erasing elastomer composition, a method for producing the same, and erasing using the composition. More specifically, the invention can be recycled without depending on fossil resources. The present invention relates to an elastomer composition for erasing, a method for producing the same, and erasing using the composition.

Until now, industries and economies have been developed through the use of fossil resources such as oil and coal, and social systems for mass production, mass consumption and mass disposal have been established. It depends.
The current social system has created economic affluence and convenience, but on the other hand, it emits waste and carbon dioxide that exceed the natural purification capacity, aggravating environmental issues such as global warming and harmful substances. ing.

  In order to solve such problems, we have produced a large amount of products from finite resources so far, consumed and discarded a large amount of this, modified the one-way social system to reduce the generation of waste, There is a strong demand for a transition to a recycling society that effectively uses limited resources. To form this recycling-oriented society, the Cabinet decided on the “Biomass and Nippon Comprehensive Strategy” in December 2002 and is working to rebuild industrial competitiveness.

  Biomass is a continuously renewable organic resource that comes from the bounty of nature. Biomass emits carbon dioxide when combusted, but absorbs and fixes carbon dioxide in the atmosphere by photosynthesis during growth, and therefore has a feature that it does not substantially increase carbon dioxide. This is called “Carbon Neutral”, and by replacing energy and products derived from fossil resources with biomass, it is possible to significantly reduce carbon dioxide emissions. Therefore, there is a strong demand for technology and product development.

In recent years, many proposals have been made for polymer materials in consideration of the formation of a recycling society.
For example, a rubber production composition comprising natural rubber and biodegradable plastic (in the examples, vulcanizing agent and vulcanization accelerator are used) (Patent Document 1), biodegradable material and epoxidized polyisoprene, and necessary A biodegradable material composition obtained by further mixing a cross-linking agent (Patent Document 2), a biodegradable rubber composition obtained by adding a biodegradable resin and a filler to natural rubber (Patent Document 3), crystals A polylactic acid-based resin composition (patent document 4) composed of a basic polylactic acid and a rubber component selected from natural rubber and polyisoprene, and a dispersed phase composed of natural rubber or the like is uniformly fine in a continuous phase composed of polylactic acid. Examples thereof include a dispersed polymer blend material (Patent Document 5).

On the other hand, the eraser can be broadly divided into three types: PVC eraser made of vinyl chloride resin, non-PVC eraser made of styrene thermoplastic elastomer or olefin thermoplastic elastomer, and natural rubber eraser.
Of these, PVC eraser and non-PVC eraser account for over 90% of the eraser market, and the polymer materials, plasticizers, and softeners that make up these are all materials derived from fossil resources such as petroleum. Continuing to use the eraser is contrary to the purpose of creating a recycling society.
On the other hand, natural rubber eraser uses biomass such as sub (factis) produced from natural rubber or vegetable oil, and is consistent with the purpose of forming a recycling society (Patent Document 6, Non-patent) Reference 1).
JP-A-10-274494 JP 2000-95898 A JP 2000-319446 A JP 2003-183488 A JP 2004-143315 A JP 2000-43492 A (see Examples 1 and 2) "Rubber Industry Handbook" (new edition) edited by Japan Rubber Association Table 25.2, pages 817, November 15, 1973 Issued by Rubber Association of Japan

  However, in the above-mentioned prior art, the rubber that is not vulcanized or crosslinked does not have sufficient tensile strength and elasticity, so its use may be limited. For example, rubber erasing material does not exhibit rubber elasticity. It is not appropriate. On the other hand, vulcanized or cross-linked ones are limited in application because they have too high tensile strength and elasticity. For example, they are not suitable because they become hard as a material for erasing and cannot provide rubber elasticity. Furthermore, the vulcanization and cross-linking steps are required, which not only complicates the manufacturing process, but also concerns the safety of vulcanizing agents such as sulfur as a vulcanizing agent, vulcanization accelerator, and zinc oxide as an auxiliary. I am confused.

  On the other hand, as described above, natural rubber eraser is suitable for the formation of a recycling-oriented society, but, for example, its eraser performance is inferior to that of PVC eraser, and it includes a vulcanization process. Compared with PVC eraser, the manufacturing process is complicated, and as described above, there are problems in the safety of vulcanizing agents such as sulfur and vulcanization accelerators. Furthermore, it is uneconomical because it is difficult to reuse the scrap generated in the manufacturing process, and there is a problem in productivity.

  In view of such circumstances, the present invention solves the above-mentioned problems of the prior art. The biomass plastic, the natural rubber, and the rubber crosslinking agent are heated at a temperature higher than the melting temperature of the biomass plastic and higher than the crosslinking temperature of the rubber crosslinking agent under high shear. Elastomer composition with properties such as tensile strength and elasticity that cannot be obtained by conventional vulcanization or crosslinking by kneading and dispersing island-shaped cross-linked natural rubber particles in a matrix made of biomass plastic, and its production Methods and erasures using the compositions are provided.

The present invention has been made in order to achieve the above object, and claim 1 of the present invention is characterized in that crosslinked natural rubber particles are dispersed in islands in a matrix made of biomass plastic selected from polylactic acid and polybutylene succinate. The biomass plastic is 50 to 1% by weight, the natural rubber is 50 to 99% by weight, and the rubber crosslinking agent (excluding sulfur and zinc oxide) is 0.1 to 5 parts by weight with respect to 100 parts by weight of the natural rubber. The content of the eraser elastomer composition is characterized .

Claim 2 of the present invention is that the biomass plastic selected from polylactic acid and polybutylene succinate, natural rubber, and rubber cross-linking agent (excluding sulfur and zinc oxide) are not less than the melting temperature of the biomass plastic and the cross-linking temperature of the rubber cross-linking agent. in the above, by kneading under high shear, in a matrix consisting of the biomass plastics, the process according to claim 1 eraser elastomer composition according to cross-linking the rubber particles are characterized in that they are distributed Content.

A third aspect of the present invention includes an erasing function comprising the erasing elastomer composition according to the first aspect.

According to a fourth aspect of the present invention, the eraser according to the third aspect further includes a softening agent.

Claim 5 of the present invention includes the eraser according to claim 4 , wherein the softener is derived from biomass.

Claim 6 of the present invention includes the eraser according to claim 4 or 5 , wherein the softening agent is selected from animal and vegetable oils and plasticizers derived therefrom.

According to claim 7 of the present invention, the softening agent is 1 to 200 parts by weight with respect to 100 parts by weight of the total of the natural rubber and the biomass plastic, according to any one of claims 4 to 6 . Erased as content.

Claim 8 of the present invention further includes a filler, and the content of the eraser according to any one of claims 3 to 7 .

Claim 9 of the present invention includes the eraser according to claim 8 , wherein the filler is derived from biomass.

Claim 10 of the present invention includes the eraser according to claim 8 or 9 , wherein the filler is selected from shell powder and eggshell powder.

Claim 11 of the present invention is that the filler is 10 to 1000 parts by weight with respect to 100 parts by weight of the total of natural rubber and biomass plastics, according to any one of claims 8 to 10 . Erased as content.

The eraser elastomer composition of the present invention does not rely on fossil resources, and the materials used as raw materials are both natural rubber and biomass plastic derived from biomass, and therefore increase carbon dioxide in the atmosphere even when discarded. It is an environmentally friendly elastomer composition that does not cause Furthermore, biomass plastics by Rukoto to have a biodegradable, decomposed under natural environment, are more provided elastomer composition environment adaptive.

In addition, since the eraser elastomer composition of the present invention is a thermoplastic elastomer, the end material produced at the time of molding can be easily recycled. Therefore, the cost can be reduced and the material is suitable for a resource recycling society. It is.

Furthermore, the method for producing an eraser elastomer composition of the present invention simultaneously performs kneading of natural rubber and biomass plastic and crosslinking of natural rubber, so that the process is simplified and the productivity is high. In addition, since a vulcanizing agent such as sulfur or zinc oxide or a vulcanization accelerator is not used for crosslinking natural rubber, safety is high.

The eraser elastomer composition of the present invention is suitable as an eraser base material , unlike materials obtained by conventional vulcanization or crosslinking.

The eraser comprising the eraser elastomer composition of the present invention is environmentally friendly, unlike the conventional PVC eraser and non-PVC eraser that rely on fossil resources, and the end material produced during molding is easily recycled. The cost is reduced because of the reduction of waste.

Further, the conventional natural rubber eraser requires a cross-linking step separately from the kneading step, whereas in the present invention, the cross-linking is performed simultaneously with the kneading, so the process is simplified and the productivity is high.
In addition, conventional natural rubber eraser uses vulcanizing agents and vulcanization accelerators such as sulfur and zinc oxide, whereas the eraser of the present invention does not use such chemicals and is therefore highly safe. .

  Furthermore, the eraser of the present invention has a higher erase ability than conventional natural rubber eraser and non-vinyl chloride eraser.

Eraser elastomer composition of the present invention include polylactic acid, the matrix during the scan comprising a biomass plastic selected from polybutylene succinate, natural rubber particles crosslinked be dispersed like islands, biomass plastics 50-1 weight %, Natural rubber is 50 to 99% by weight, and rubber cross-linking agent (excluding sulfur and zinc oxide) is 0.1 to 5 parts by weight with respect to 100 parts by weight of natural rubber .

  Natural rubber used in the present invention is classified into sheet rubber, pale crepe, brown crepe, blanket crepe, block rubber, crumb rubber, etc., depending on the method of processing from latex to solid rubber. There are no restrictions on the production area. In addition, natural rubber derivatives such as epoxidized natural rubber can be used. These may be used alone or in combination of two or more as required.

Biomass plastic used in the present invention can be produced corn, potato, polylactic acid resin obtained by polymerizing lactic acid obtained by fermenting sugars and starches derived from sugar cane (e.g. manufactured by Mitsui Chemicals, Inc. Lacea), from starch and a polybutylene succinate to succinic acid and 1,4-butanediol as raw materials (e.g., manufactured by Mitsubishi Chemical Corporation GS-Pla), these are alone or if necessary, be used in combination of two or more.

The composition ratio of the natural rubber and biomass plastic, natural rubber 50 to 99 wt%, preferably in the range of biomass plastic is 50 to 1 wt%, more preferably natural rubber 70-95% by weight, biomass plastics 30-5 % By weight. When the biomass plastic is less than 1% by weight, the fluidity of the elastomer composition is poor and a problem occurs in moldability. Biomass plastic does not express exceeds the elastomer composition becomes hard rubber elasticity 50% by weight, there is a tendency that sufficient erasing characters performance is exhibited when used as a substrate for erasers.

  As the rubber cross-linking agent used in the present invention, an organic peroxide can be suitably used. Specifically, dicumyl peroxide (for example, Park Mill D manufactured by NOF Corporation), 2,5-dimethyl-2,5-di-t-butylperoxyhexane (for example, Perhexa 25B manufactured by NOF Corporation), di-t. -Butylperoxydiisopropylbenzene (for example, Perbutyl P manufactured by NOF Corporation), 2,5-dimethyl-2,5-di-t-butylperoxyhexine-3 (for example, Perxin 25B manufactured by NOF Corporation) and the like. . Other organic vulcanizing agents can also be used. Specifically, N, N′-m-phenylene dimaleimide (for example, Barnock PM manufactured by Ouchi Shinsei Chemical Co., Ltd.), p-quinone dioxime (for example, Barnock GM manufactured by Ouchi New Chemical Co., Ltd.), alkylphenol formaldehyde resin (for example Taoka) And Tacchi roll 201) manufactured by Kagaku Corporation. These may be used alone or in combination of two or more as required.

  The rubber crosslinking agent is used in an amount of 0.1 to 5.0 parts by weight with respect to 100 parts by weight of natural rubber. If the rubber cross-linking agent is less than 0.1 parts by weight, the cross-linking is insufficient, and natural rubber does not become particles and the desired structure cannot be obtained. It tends to be too large and cause problems in formability.

Various additives used in the fields of biomass plastic materials and natural rubber materials can be added to the eraser elastomer composition of the present invention. Examples of such additives include ultraviolet absorbers, hindered amine light stabilizers, weather resistance improvers such as antioxidants, higher fatty acid alcohols, aliphatic amides, metal soaps, lubricants such as fatty acid esters, and the like.

When the eraser elastomer composition of the present invention is used as a eraser base material, softeners, fillers, organic / inorganic pigments, dyes and other colorants, fragrances, stabilizers, antioxidants, ultraviolet absorbers In addition, other additives such as a fungicide can be arbitrarily used as appropriate.

  As the softener, mineral oil, animal and vegetable oil, or a plasticizer derived therefrom can be used. Specific examples of the mineral oil include paraffinic process oil, naphthenic process oil, and aromatic process oil. Specific animal and vegetable oils include rapeseed oil, castor oil, cottonseed oil, linseed oil, soybean oil, sesame oil, corn oil, safflower oil, palm oil, coconut oil, peanut oil, wood wax, rosin, pine tar, tall oil, etc. . Examples of plasticizers derived from animal and vegetable oils include glycerin fatty acid esters, and specific examples include glycerin diacetate monolaurate, glycerin triacetate, and glycerol diacetate. These may be used alone or in combination of two or more as required. From the standpoint of providing a more environmentally adaptable elastomer composition, it is preferable to use a biomass-derived animal or vegetable oil or a plasticizer derived therefrom, which is a renewable resource.

  The amount of the softening agent added can be 1 to 200 parts by weight with respect to 100 parts by weight of the mixture of natural rubber and biomass plastic. The amount is preferably 10 to 150 parts by weight. If the amount of the softener is less than 1 part by weight, the amount of the softener added is not sufficient, while if it exceeds 200 parts by weight, bleeding may occur.

Fillers include heavy calcium carbonate, light calcium carbonate, silica, diatomaceous earth, magnesium oxide, titanium oxide, talc, sericite, quartz powder, montmorillonite, scallops, oysters, spotted shell powder, eggshell powder, organic hollow particles And inorganic hollow particles. These may be used alone or in combination of two or more as required. From the standpoint of providing a more environmentally adaptable elastomer composition, it is preferable to use shellfish powders such as scallops and oysters, oysters or eggshell powders that are generated in large quantities as waste.
The blending amount of the filler can be 10 to 1000 parts by weight with respect to 100 parts by weight of the mixture of natural rubber and biomass plastic. Preferably it is 50-500 weight part. If the amount is less than 10 parts by weight, the effect of adding the filler is not sufficient. On the other hand, if the amount exceeds 1000 parts by weight, the composition becomes hard and sufficient rubber elasticity does not appear. There is a tendency that the erasing performance is not demonstrated.

The eraser elastomer composition of the present invention comprises a biomass plastic, natural rubber and a rubber cross-linking agent, and further, if necessary, a softener, a filler and the like in a kneading machine, which are above the melting temperature of the biomass plastic and of the rubber cross-linking agent. It can be obtained by kneading under a high shear at a crosslinking temperature or higher.
Examples of the kneading machine capable of kneading under high shear include a biaxial kneading extruder, a Banbury mixer, a pressure kneader, a mixing roll, and the like, and a biaxial kneading extruder is preferably used.
The temperature higher than the melting temperature of the biomass plastic is preferably 10 to 50 ° C. higher than the melting temperature of the biomass plastic, and the temperature higher than the crosslinking temperature of the rubber cross-linking agent is 5 to 20 ° C. higher than the cross-linking temperature of the rubber cross-linking agent. Is preferred .

The eraser of the present invention using the eraser elastomer composition is formed by press molding, injection molding, extrusion molding, or the like, and cut into a predetermined size to obtain a product.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example and a comparative example, these do not restrict | limit the scope of the present invention at all.

  The materials used in the following examples and comparative examples are shown in Table 1.

Examples 1-11
Of the materials shown in Table 2, natural rubber, softener, and filler were previously kneaded with a pressure kneader, and a rubber cross-linking agent was added using a roll to obtain a rubber kneaded product. The obtained rubber kneaded product was cut into pellets of about 5 mm square. Next, rubber kneaded pellets and biomass plastic pellets are shown in Table 2 using a twin-screw extruder KZW-15TW-60 (same direction complete meshing type, screw diameter 15 mm, L / D = 60) manufactured by Technobel. Each was supplied with a fixed amount feeder so as to have a blending ratio, and kneaded at a screw rotation speed of 400 rpm. The cylinder temperature was set to 120 to 190 ° C. so that the kneading temperature was higher than the melting point (170 ° C.) of the biomass plastic and higher than the rubber crosslinking temperature (180 ° C.).
The obtained composition pellets were extruded into a square bar shape with a single screw extruder (cylinder temperature 90 to 110 ° C., head temperature 120 ° C.), and cut to produce an eraser.

Hardness and erasure rate were evaluated as erasing characteristics.
The hardness was measured in accordance with “JIS S 6050 Plastic Eraser” using a C-type hardness meter (Type C hardness meter manufactured by Kobunshi Keiki).
The erasure rate was measured by the following method.
(1) A sample was cut into a plate having a thickness of 5 mm, and a test piece was prepared by finishing a contact portion with a test paper into an arc having a radius of 6 mm.
(2) The test piece is brought into contact with the colored paper perpendicularly and at right angles to the colored line, and the weight is placed on the test piece so that the sum of the weight of the weight and the holder is 0.5 kg. The colored part was brushed back and forth four times at a speed of 150 ± 10 cm / min.
(3) Using a densitometer (DENSITOMETER PDA65 made by Sakura), the density of the non-colored part of the colored paper was set to 0, and the density of the colored part and the eroded part were measured.
(4) The erasure rate was calculated by the following formula.
Erase rate (%) = (1− (density of wear part ÷ density of colored part)) × 100

Comparative Example 1
Using the materials shown in Table 3, a rubber kneaded product was obtained by kneading all the compounding materials into natural rubber using two rolls. The obtained rubber kneaded material was preformed according to the dimensions of a predetermined mold, and vulcanized and molded under conditions of 130 ° C. for 20 minutes using a hot press. The obtained rubber molding was cut into a predetermined size to obtain an eraser.

As described above, the eraser elastomer composition of the present invention is mainly composed of biomass-derived biomass plastic and natural rubber, so it does not depend on fossil resources and increases carbon dioxide in the atmosphere even if discarded. It is an elastomer composition that is recyclable, environmentally friendly and compatible with a recycling-oriented society. When used as an erasing base material, it provides erasing ability and excellent erasure. Can do. Further, it is possible to further provide eraser elastomer composition and eraser environment adaptive because they are decomposed under the natural environment.

Claims (11)

Cross-linked natural rubber particles are dispersed in an island shape in a matrix made of biomass plastic selected from polylactic acid and polybutylene succinate , biomass plastic is 50 to 1 wt%, natural rubber is 50 to 99 wt%, and An eraser elastomer composition , wherein the rubber cross-linking agent (excluding sulfur and zinc oxide) is 0.1 to 5 parts by weight with respect to 100 parts by weight of natural rubber . Kneading biomass plastic selected from polylactic acid and polybutylene succinate, natural rubber, and rubber cross-linking agent (excluding sulfur and zinc oxide) at high shear above the melting temperature of biomass plastic and above the cross-linking temperature of rubber cross-linking agent it allows the matrix of the said biomass plastic, the method according to claim 1 eraser elastomer composition according to cross-linking the rubber particles are characterized in that they are distributed to. An eraser comprising the eraser elastomer composition according to claim 1 . The eraser according to claim 3 , further comprising a softening agent. The eraser according to claim 4 , wherein the softening agent is derived from biomass. The eraser according to claim 4 or 5 , wherein the softening agent is selected from animal and vegetable oils and plasticizers derived therefrom. The eraser according to any one of claims 4 to 6 , wherein the softening agent is 1 to 200 parts by weight with respect to 100 parts by weight of the total of natural rubber and biomass plastic. The eraser according to any one of claims 3 to 7 , further comprising a filler. The eraser according to claim 8 , wherein the filler is derived from biomass. The eraser according to claim 8 or 9 , wherein the filler is selected from shell powder and eggshell powder. The eraser according to any one of claims 8 to 10 , wherein the filler is 10 to 1000 parts by weight with respect to 100 parts by weight of the total of natural rubber and biomass plastic.