WO2008038350A1

WO2008038350A1 - Resin composition, pulverized matter and method of discarding resin composition

Info

Publication number: WO2008038350A1
Application number: PCT/JP2006/319174
Authority: WO
Inventors: Kouta Nishii; Koichi Kimura
Original assignee: Fujitsu Limited
Priority date: 2006-09-27
Filing date: 2006-09-27
Publication date: 2008-04-03
Also published as: JP5200937B2; JPWO2008038350A1

Abstract

A resin composition containing a biodegradable plastic and a photocatalyst coated with an inorganic material, wherein 0.1 to 20 parts by weight of photocatalyst is contained per 100 parts by weight of biodegradable plastic. Further, there is provided a method of discarding the resin composition. This resin composition realizes inhibition of quality degradation before pulverization treatment and rapid degradation after pulverization treatment.

Description

Specification

Resin composition, powdered product, and disposal method of resin composition

Technical field

TECHNICAL FIELD [0001] The present invention relates to a resin composition that can reduce the load of waste on the environment and a disposal method thereof.

Background art

[0002] In recent years, a wide variety of synthetic resin materials have been developed and provided, and the amount used in various industrial fields is increasing year by year. However, most of these synthetic resins are made from petroleum, so (1) there is a shortage of drought resources, (2) they are not biodegradable and must be incinerated when discarded, and (3) look at the life cycle. In the case of environmental impact, the burden on the global environment is large, such as high environmental impact (large emissions of carbon dioxide).

[0003] For this reason, various biodegradable plastics have attracted attention in place of conventional synthetic resins for the purpose of reducing the load on the global environment.

[0004] These biodegradable plastics are decomposed by the action of microorganisms when buried in soil at the time of disposal. However, when decomposing using microorganisms, the decomposing process takes a considerable amount of time. This is because it takes a considerable time for the surface decomposition to start because the microorganisms in the ground decompose from the surface of the resin molded product. Furthermore, even if left in the soil or carried, the decomposition was not promoted unless the conditions of high temperature and high humidity and the presence of many microorganisms were not met.

[0005] As means for solving this, for example, Patent Document 1 proposes a method in which a composition in which a saccharide and a photocatalyst are added to a thermoplastic resin is used, and decomposition is accelerated by ultraviolet irradiation. However, with this method, the quality of the molded product is likely to deteriorate, such as causing a choking on the surface of the molded product by the action of the photocatalyst before disposal, and possibly reducing the physical properties of the molded product. It was not right.

Patent Document 1: JP-A-9 309959 (Claims)

Disclosure of the invention

Problems to be solved by the invention [0006] The present invention has been made in view of the above-mentioned facts. During use, quality deterioration such as choking and physical property deterioration (for example, strength reduction) can be suppressed. It is an object to provide a resin composition that is moderately and rapidly decomposable and a disposal method for the resin composition. Still other objects and advantages of the present invention will become apparent from the following description.

Means for solving the problem

[0007] According to one aspect of the present invention, there is provided a resin composition comprising a biodegradable plastic and a photocatalyst coated with an inorganic substance, wherein the photocatalyst is added to 100 parts by weight of the biodegradable plastic. A resin composition containing 20 to 20 parts by weight is provided. According to the embodiment of the present invention, it is possible to obtain a resin composition in which quality deterioration is suppressed before the powder treatment and can be rapidly decomposed after the pulverization treatment.

[0008] The biodegradable plastic is polylactic acid, and the photocatalyst is composed of titanium oxide, zinc oxide, zirconium oxide, strontium titanate, titanium hydroxyapatite, a modified product thereof, a composite thereof, and a mixture thereof. It is preferable that the photocatalyst is titanium hydroxyapatite, and that the resin composition contains 0.1 to 10% by weight of a surfactant.

[0009] According to another aspect of the present invention, there is provided a pulverized product obtained by pulverizing the resin composition. According to the embodiment of the present invention, it is possible to change the resin composition in which quality deterioration is suppressed before the pulverization treatment so that it can be rapidly decomposed. It is preferable that the resin composition before the pulverization treatment is a molded product, and that after the pulverization treatment, any of ultraviolet irradiation treatment, stirring treatment, or water spray treatment is included.

[0010] According to still another aspect of the present invention, there is provided a method for discarding a resin composition, comprising pulverizing the resin composition. According to the embodiment of the present invention, it is possible to rapidly decompose a resin composition in which deterioration of quality is suppressed before pulverization.

[0011] The resin composition before the powdering process is a molded product, and after the powdering process, the resin composition includes at least one process selected from the group consisting of an ultraviolet irradiation process, a stirring process, and a water spray process, Is preferred.

The invention's effect [0012] According to the present invention, there is provided a resin composition capable of suppressing quality deterioration before pulverization and rapidly decomposing after pulverization, and a method for discarding such a resin composition.

Brief Description of Drawings

FIG. 1 is a schematic diagram for explaining the action of a photocatalyst according to the present invention.

FIG. 2 is a schematic view showing an example of production of a resin composition according to the present invention.

FIG. 3 is a schematic view showing the state of decomposition of the resin composition according to the present invention.

Explanation of symbols

[0014] 1 Resin composition

2 Inorganic

3 Photocatalyst

4 Grind

31 Molded products

32 Grind

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings, tables, examples and the like. These figures, tables, examples, etc., and explanations are only for illustrating the present invention and are not intended to limit the scope of the present invention. It goes without saying that other embodiments may also belong to the scope of the present invention as long as they meet the spirit of the present invention.

[0016] The resin composition according to the present invention is a resin composition comprising a biodegradable plastic and a photocatalyst coated with an inorganic substance, and the photocatalyst is added to 100 parts by weight of the biodegradable plastic. :! ~ 20 parts by weight included.

[0017] Since the photocatalyst is coated with an inorganic substance in the resin composition according to the present invention, it is possible to suppress quality deterioration due to choking due to the action of the photocatalyst or a decrease in physical properties (such as a decrease in strength). In addition, if this is pulverized, the inorganic substance is removed from the surface of the photocatalyst, whereby the action of the photocatalyst can be made obvious and the resin composition can be rapidly decomposed. Along with this, biodegradable plastics can be rapidly degraded.

[0018] The biodegradable plastic according to the present invention is not particularly limited and is suitable from known ones. It can be selected as appropriate. Specifically, a biodegradable polysaccharide, peptide, aliphatic polyester, polyamino acid, polybutyl alcohol, polyamide, polyalkylene glycol, etc., and a copolymer containing at least one of these, etc. Are listed. In particular, aliphatic polyesters are practically suitable materials because of their excellent mixing and mass productivity.

[0019] The aliphatic polyester is more preferably poly_L_lactic acid (PLLA), polylactic acid such as a random copolymer of L_lactic acid and D_lactic acid, or a derivative thereof. General polylactic acid is a crystalline polymer excellent in biodegradability with a melting point of about 160-170 ° C and a glass transition temperature of about 58 ° C.

[0020] In addition to these, for example, poly force prolatatone, polyhydroxybutyric acid, polyhydroxyvaleric acid, polyethylene succinate, polybutylene succinate, polybutylene adipate, polyphosphonic acid, polydaricholic acid, polysuccinic acid ester, polysuccinic acid ester, Examples include microbial synthetic polyester.

[0021] A photocatalyst itself does not change, but can be defined as a substance that promotes a reaction by receiving light. In other words, it is a substance that is excited by light, and this excited substance is a substance that has a catalytic action on a chemical change of another adjacent substance. Utilizing this catalytic action, the photocatalyst can purify the atmosphere (removal of harmful substances such as Nx, SOx and formaldehyde in the air) and deodorize (adsorption of bad odors such as cetaldehyde, ammonia and hydrogen sulfide). , Decomposition), purified water (decomposition and removal of volatile organochlorine compounds such as tetrachloroethylene trichloroethylene, which is a pollutant melted in water), antibacterial (antibacterial action, and a clean environment is realized by sterilization) It is being studied and put to practical use for that purpose.

[0022] The photocatalyst according to the present invention can be considered as a photocatalyst in this sense. However, in the present invention, the catalytic action is used to accelerate the decomposition of the biodegradable plastic. The mechanism is not clear, but it may be via oxidative degradation.

[0023] The type of the photocatalyst according to the present invention is not particularly limited and can be appropriately selected from known photocatalysts. Specifically, titanium oxide (especially anatase type titanium oxide), oxidation Zinc, zirconium oxide, strontium titanate, titanium hydroxyapatite (a part of calcium constituting calcium hydroxyapatite crystals is replaced by titanium), and modifications, composites and mixtures of these substances Can do. Preferably, the photocatalyst is titanium hydroxyapatite.

[0024] Here, the "modified product" means a material obtained by replacing a part of the elements of these materials with other elements, and the composite means a simple mixture such as a double salt. Rather, it means something that coexists with some interaction. Examples of the former include (anatase-type) titanium oxide fine particles with nanoscale metal ultrafine particles supported, or titanium hydroxyapatite calcium further substituted with other cations. Examples thereof include a mask melon type photocatalyst in which the surface of titanium oxide is coated with inert silica.

[0025] The shape of these photocatalysts may be any, but since it is mixed in the resin composition, it is generally preferable that the photocatalyst is in the form of a powder.

[0026] The combination of the biodegradable plastic and the photocatalyst according to the present invention may be arbitrarily selected. However, several candidates are specifically selected and kneaded, and the obtained kneaded product or the powder of this kneaded product is used. It can be easily selected through comparison of results such as degradation test of crushed material (for example, acceleration test for choking and mechanical strength degradation).

[0027] In the resin composition according to the present invention, the ratio of the biodegradable plastic and the photocatalyst coated with an inorganic substance is 0.1 to 20 parts by weight of the photocatalyst with respect to 100 parts by weight of the biodegradable plastic. It is preferable that The “photocatalyst” in this case is an amount that does not contain any organic matter as a coating. If the photocatalyst is less than 0.1 part by weight, the decomposition effect after disposal is small. If it exceeds 20 parts by weight, practical defects such as difficulty in molding the resin composition are likely to be realized.

[0028] The surface of the photocatalyst according to the present invention is coated with an inorganic substance. In the organic matter, the organic matter itself is deteriorated by the action of the photocatalyst, and as a result, the decomposition of the resin composition may be promoted even before the pulverization treatment.

[0029] The inorganic substance may be selected from any substances that suppress the catalytic action of the photocatalyst and can be removed from the photocatalyst by pulverization. By grinding process, It can be easily found by experiment whether or not the polishing agent is peeled off from the surface of the photocatalyst.

[0030] The inorganic substance can be appropriately selected from known inorganic coating agents. Typical examples of inorganic coating agents (solutions) include silicone-based hard coating materials such as Solgard (Nippon Dacro Shamrock), Quad Dyne (KADOWAKI), and Heatless Glass (Miyaki). In addition to the silicone type, there are coating agents such as aluminum oxide type, zirconium oxide type, and magnesium oxide type. It suppresses the catalytic action of the photocatalyst, and the inorganic substance that coats the photocatalyst easily peels off by pulverization. A silicone-based hard coat material is preferred.

[0031] The coating method and coating thickness of these inorganic materials and the weight ratio of the inorganic material to the photocatalyst may be appropriately selected according to the actual situation without any particular limitation. Commercial products may be used. In general, the weight ratio of the inorganic substance to the photocatalyst is preferably about 1:10 to about 100: 10.

[0032] The resin composition according to the present invention necessarily contains a biodegradable plastic and a photocatalyst coated with an inorganic substance, but may contain other substances within the scope allowed for practical purposes. Good. For example, plastics other than biodegradable plastics and additives other than photocatalysts coated with inorganic substances (colored substances, fillers for improving mechanical strength, etc.) may coexist.

[0033] As such an additive, a surfactant is preferably added in order to improve the dispersibility of the photocatalyst in the resin composition. If the dispersibility of the photocatalyst in the resin composition is low, the efficiency of the photocatalyst is lowered, the moldability becomes poor, and the mechanical properties (for example, strength) of the molded product are likely to be inconvenient.

[0034] The surfactant can be appropriately selected from known ones according to the type of photocatalyst used and its inorganic substance (coating agent). As the surfactant, any force of an anionic surfactant and a cationic surfactant can be preferably used. The amount used is not particularly limited, but in general, the surfactant is preferably contained in an amount of 0.1 to 10% by weight based on the total amount of the resin composition. If the content is less than 1% by weight, it is difficult to obtain a dispersion effect. [0035] The method for obtaining the resin composition according to the present invention by mixing the various substances described above can be appropriately selected from known methods without particular limitations. A uniaxial or biaxial kneading apparatus (such as an etastruder) is preferred. The above various substances may be dry blended, blended during kneading, or a combination thereof. Needless to say, the blend is preferably one that does not break the coating of the inorganic material on the photocatalyst as much as possible, but there is little need to worry about breaking the coating in a normal dry blending apparatus or kneading apparatus.

[0036] The shape of the resin composition according to the present invention is often in the form of pellets when produced using a kneading apparatus with no particular restriction, but may be in the form of a powder. Generally speaking, it is a resin composition containing a biodegradable plastic and a photocatalyst coated with an inorganic substance, and the photocatalyst is in the range of 0.:! To 20 wt. Per 100 parts by weight of the biodegradable plastic. Any shape of the resin composition that satisfies the requirements of the resin composition contained in the resin and before the pulverization treatment according to the present invention is considered to be the resin composition according to the present invention. Therefore, the resin composition according to the present invention includes those molded using these pellets and powders (for example, a molded product formed by injection molding). Note that the molded product according to the present invention includes a three-dimensional molded product as well as a sheet-shaped product, a strand-shaped product or a thread-shaped product. Specifically, it may be used for any purpose. Electronic devices such as computers Cases, home appliances, furniture, toys, tableware and the like can be exemplified.

[0037] The resin composition according to the present invention can be rapidly decomposed by pulverization. This is probably because the inorganic material that coats the photocatalyst peels off due to the energy given to the resin composition by the pulverization treatment, and the action of the photocatalyst becomes obvious. The photocatalyst itself is exposed, making it easier to irradiate light directly.

[0038] An example of this situation is shown in FIG. FIG. 1 (1) shows a state in which the photocatalyst 3 coated with the inorganic substance 2 is dispersed in the resin composition 1 according to the present invention. (2) represents the state of the pulverized product 4 after the resin composition 1 is pulverized. In this figure, the inorganic substance is peeled off from the photocatalyst 3, and the photocatalyst 3 is exposed to the outside. When, for example, sunlight is applied in such a state, as shown in (3), the resin composition around the photocatalyst 3 is It deteriorates rapidly and decomposes, whereby the decomposition of the entire resin composition can be promoted.

[0039] The resin composition subjected to the pulverization treatment according to the present invention may have any shape. A molded article that has already been used for some purpose can be preferably used. That is, it is preferable to pulverize the molded product when it is discarded. As a result, quality degradation can be suppressed during use of the molded product, and rapid and powerful degradation of the biodegradable plastic can be achieved after disposal.

[0040] The pulverization method and the apparatus used for pulverization according to the present invention can be appropriately selected from known ones without particular limitations. For example, it is possible to illustrate the use of what is called a crusher, (compression crushing), cutter (cut crushing crushing), mill (grinding). There is no particular limitation on the size and shape of the pulverized product, but generally a smaller size is advantageous. In general, those having a sphere equivalent diameter of 1 cm or less are preferred, and those having a diameter of 5 mm or less are more preferred.

[0041] The powdered product according to the present invention is rapidly decomposed thereafter. Thereafter, the pulverized product may be carried on the ground or in the ground. At that time, microorganisms for biodegradation may be added, or water for promoting biodegradation may be replenished by spraying or the like. However, before or instead of such treatment, it is possible to include any treatment selected from the group consisting of ultraviolet irradiation treatment, stirring treatment and water spray treatment of the resin composition according to the present invention. It is preferable in terms of realizing rapid decomposition. You can combine these. You may combine heat processing. Furthermore, a microorganism for biodegradation may coexist.

In this way, the effect of the photocatalyst, in which the inorganic substance is peeled off and the action of the photocatalyst becomes obvious, can be effectively utilized. The technique used for the ultraviolet irradiation process, the stirring process, and the water spray process can be appropriately selected from known techniques that are not particularly limited. In the stirring treatment, the pulverized product may be in a dry state, a wet state with water, or a slurry state with water.

[0043] Hereinafter, an example of the production of the resin composition is shown in Fig. 2, and the state of pulverization is shown in Fig. 3. In Fig. 2, the photocatalyst is dispersed in the inorganic coating agent solution to obtain a photocatalyst coated with the inorganic coating agent. This is put together with a biodegradable resin and a surfactant into an etastruder for compound preparation, melt-kneaded, and then cooled with water to form a strand. Process with a pelletizer to obtain pellets. Next, in the pulverization process according to the present invention, for example, a molded product 31 injection-molded using the pellets is pulverized to obtain a pulverized product 32. This pulverized product can be naturally decomposed with sunlight as shown in the lower right side of Fig. 3, and put into a tank, added with water, stirred and irradiated with ultraviolet rays as shown on the lower left side of the force. Decomposition may be promoted.

Example

Next, examples and comparative examples of the present invention will be described in detail.

[0045] [Example 1]

50 parts by weight of titanium oxide as a photocatalyst was dispersed in 100 parts by weight of a silicone hard coat agent Solgard (Nihon Dacro Shamrock) as an inorganic coating agent solution.

[0046] 9 parts by weight of the dispersion, 90 parts by weight of polylactic acid as a biodegradable plastic, and Anion surfactant blended _(w _ 304, manufactured by Asahi Kasei Corporation) 3 parts by weight, kneading extruder It knead | mixed at 200 degreeC using the biaxial etastruder which is. This composition was molded by an injection molding machine to produce a molded product (plate) for evaluation of 80 × 80 × 1 mm.

[0047] [Example 2]

As a photocatalyst, 50 parts by weight of titanium apatite was dispersed as an inorganic coating agent solution in 100 parts by weight of a silicone-based hard coating agent KADOWAKI. A twin screw extruder which is a kneading extruder containing 9 parts by weight of the above dispersion, 90 parts by weight of polylactic acid as a biodegradable plastic, and 3 parts by weight of anionic surfactant (w_304, manufactured by Asahi Kasei). And kneaded at 200 ° C. This composition was molded by an injection molding machine to produce a molded product (plate) for evaluation of 80 × 80 × 1 mm.

[0048] [Comparative Example 1]

Kneading and molding were performed in the same manner as in Example 1 except that the photocatalyst and the inorganic coating agent were not used.

[0049] [Comparative Example 2]

Kneading and molding were performed in the same manner as in Example 1 except that the inorganic coating agent was not used.

[0050] [Example 3] Kneading and molding were carried out in the same manner as in Example 1 except that the surfactant was not used. [0051] (Evaluation)

The resin molded products of Examples and Comparative Examples were pulverized with a resin pulverizer to obtain a pulverized product having an average particle size of 5 mm, and then discarded in soil, and the weight loss rate was measured every 1, 3, and 6 months. did. The results are shown in Table 1. The weight retention in Table 1 shows the change in dry weight of the sample before and after burying in soil for 1, 3 and 6 months (ratio of weight after burying when the value before loading is 100%) It is. The choking was confirmed visually. Dispersibility was confirmed visually under a microscope.

[0052] In Examples 1 and 2, under normal use (36 months), there was no problem such as choking, and decomposition was promoted at the time of disposal. In Example 3, there was no problem such as choking under normal use (36 months). However, since the dispersibility of the photocatalyst particles was insufficient, the pulverized product was not uniformly dispersed as shown in the remarks about dispersibility. For this reason, the decomposition was inferior to Examples 1 and 2.

[0053] On the other hand, it was found that in Comparative Example 1, decomposition after disposal was slower and did not proceed easily as compared with Example. In Comparative Example 2, decomposition was promoted at the time of disposal, but choking occurred under normal use (1 month).

[0054] [Table 1] Table 1

[Example 4]

[0055] 5 kg of the same molded and pulverized product used in Example 1 was placed in a 60 L stainless steel container equipped with a stirrer shown in the lower left of FIG. 3 and irradiated with ultraviolet rays (light quantity: 10 mWZcm ² ). 1st Z day LOOmL of water was sprayed, and the change in dry weight for each elapsed time was examined.

As a result, the weight retention was 75% after 1 week, 57% after 2 weeks, and 32% after 3 weeks, confirming that the decomposition was promoted more than when discarded in soil.

Claims

The scope of the claims

[I] A resin composition comprising a biodegradable plastic and a photocatalyst coated with an inorganic substance, wherein the photocatalyst is contained in an amount of 0.:! To 20 parts by weight per 100 parts by weight of the biodegradable plastic. object.

[2] The resin composition according to claim 1, wherein the biodegradable plastic is polylactic acid.

[3] The photocatalyst is titanium oxide, zinc oxide, zirconium oxide, strontium titanate.

2. The resin composition according to claim 1, wherein the resin composition is selected from the group consisting of titanium hydroxyapatite, modified products thereof, composites thereof, and mixtures thereof.

[4] The resin composition according to claim 1, wherein the photocatalyst is titanium hydroxyapatite.

[5] The resin composition according to claim 1, comprising 0.1 to 10% by weight of a surfactant.

[6] A pulverized product obtained by pulverizing the resin composition according to any one of claims 1 to 5.

[7] The pulverized product according to claim 6, wherein the resin composition before the pulverization treatment is a molded product.

[8] The pulverized product according to claim 6 or 7, comprising any one of an ultraviolet irradiation treatment, a stirring treatment, and a water spray treatment after the pulverization treatment.

[9] A method for discarding a resin composition, comprising pulverizing the resin composition according to any one of claims 1 to 5.

[10] The disposal method according to appendix 9, wherein the resin composition before pulverization is a molded product.

[I I] The disposal method according to claim 9 or 10, comprising at least one treatment selected from the group consisting of ultraviolet irradiation treatment, stirring treatment and water spray treatment after the pulverization.