JP2005060637A - Biodegradable resin composition and resin enclosure using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biodegradable resin composition which contains polylactic acid and can be injection molded to form a molding without lowering strength and heat resistance, and a resin enclosure using it. <P>SOLUTION: The biodegradable resin composition comprises polylactic acid and an amorphous resin having a higher glass transition temperature than the polylactic acid has, or comprises polylactic acid, tannin, and preferably a phosphoric acid ester. The biodegradable resin composition is used to manufacture the enclosure. Polystyrene, an ABS resin, polycarbonate or the like may be used as the amorphous resin. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a biodegradable resin composition and a resin casing using the same.

  Resin products do not decompose even when buried in the soil, and generate high heat and toxic substances such as dioxins when combusted, which is a big problem from the viewpoint of global environmental conservation and prevention of environmental pollution. In recent years, biodegradable resins have attracted attention as a breakthrough. Films, planting pots, fishing lines, materials for agriculture, forestry and fisheries such as fish nets, water retention sheets, materials for civil engineering work such as plant nets, soil, foods, etc. have been attached. Thus, practical application has been promoted mainly for disposable items in the packaging / container field which is difficult to recycle.

Recently, it has been studied to use a biodegradable resin mainly composed of polylactic acid for a housing of an electronic device such as a notebook computer or a mobile phone (for example, see Patent Document 1).
JP 2001-244645 A

  In order to form a casing for an electronic device such as a notebook computer or a mobile phone by injection molding of a polylactic acid resin, it is necessary to ensure strength and heat resistance necessary for the casing. For this purpose, it is necessary to promote the crystallization of polylactic acid to increase the strength and heat resistance.

  In order to promote crystallization of polylactic acid in injection molding, the mold temperature must be set high, and usually the mold temperature during molding needs to be 80 to 110 ° C. However, the crystallinity of polylactic acid is 30 to 40% at the maximum, and its glass transition temperature is about 60 ° C. For this reason, when the mold temperature is 80 to 110 ° C., the amorphous part of polylactic acid is softened and loses its rigidity, so that there is a problem that deformation and defective release occur when the molded product is released.

  Therefore, the present invention provides a biodegradable resin composition that does not decrease in strength and heat resistance even when a molded product is formed by injection molding, and a resin casing using the same.

  The present invention provides a biodegradable resin composition comprising polylactic acid and an amorphous resin having a glass transition temperature higher than that of the polylactic acid.

  The present invention provides a biodegradable resin composition comprising polylactic acid and tannin.

  This invention provides the resin housing | casing characterized by being formed from the said biodegradable resin composition.

  The present invention provides a biodegradable resin composition containing polylactic acid and a resin casing using the same that have the above-described configuration and do not decrease in strength and heat resistance even when a molded product is formed by injection molding. be able to.

  As a result of intensive studies to solve the above problems, the present inventors have found that the glass transition temperature of polylactic acid is higher than that of polylactic acid in order to improve the heat resistance of the amorphous part of the resin containing polylactic acid as a main component. It is found that there is a first solution to mixing an amorphous resin having a glass transition temperature with polylactic acid, and that there is a second solution to mixing tannin with polylactic acid. The headline and the present invention were completed. Embodiments of the present invention will be described below.

(Embodiment 1)
An example of the biodegradable resin composition of the present invention is a biodegradable resin composition containing polylactic acid and an amorphous resin having a glass transition temperature higher than that of polylactic acid.

  Moreover, an example of the resin housing | casing of this invention is the resin housing | casing formed from the said biodegradable resin composition.

  Polylactic acid is a biodegradable resin, and biodegradability can be imparted to the molded body by producing a molded body using the resin containing polylactic acid. Thereby, even if this molded object is buried in the ground as it is, a large part thereof is naturally decomposed by microorganisms present in the ground. In addition, since this molded body generates little harmful substances such as dioxin even when burned, it emits less carbon dioxide, so it has a low environmental load and is extremely excellent in environmental friendliness.

  In order to realize the above effects, the polylactic acid is preferably contained in an amount of 50% by weight or more based on the total weight of the biodegradable resin composition.

  The molecular weight and molecular weight distribution of the polylactic acid are not particularly limited as long as it can be substantially molded, but the weight average molecular weight is preferably 10,000 or more, more preferably 40,000 or more, and particularly preferably Is over 80,000.

  Moreover, since the said biodegradable resin composition contains the amorphous resin which has a glass transition temperature higher than the glass transition temperature of polylactic acid, the glass transition temperature (about 60 degreeC) of polylactic acid in the case of injection molding Even when the mold temperature is set higher, the softening of the resin can be suppressed, and the occurrence of deformation of the molded product and defective mold release at the time of mold release can be reduced. In addition, by using an amorphous resin as a resin to be added to polylactic acid, the amorphous resin is dispersed in the amorphous part of polylactic acid to form a sea-island structure, so that the strength of the amorphous part of polylactic acid is increased. be able to. Thereby, the intensity | strength and heat resistance of a molded article can be improved.

  Amorphous resin refers to a resin in which the proportion of crystalline parts having a periodic higher order structure with molecular chains arranged regularly is smaller than that of crystalline resin.

  Specific examples of the amorphous resin having a glass transition temperature higher than that of polylactic acid include, for example, polyvinyl chloride, polystyrene, ABS resin, AS resin, ASA resin, polycarbonate, polymethyl methacrylate, modified polyphenylene ether, Examples thereof include polysulfone, polyethersulfone, polyarylate, polyamideimide, polyetherimide, thermoplastic polyimide, styrene elastomer, ethylene vinyl acetate copolymer, and polyetheretherketone.

  It is preferable to add a silicone flame retardant, an organic metal salt flame retardant, an organic phosphorus flame retardant, a metal oxide flame retardant, a metal hydroxide flame retardant, etc. to the biodegradable resin composition. . Thereby, while flame retardance improves and a fire spread can be suppressed, the fluidity | liquidity of a biodegradable resin composition improves, Therefore The more outstanding moldability is securable.

  As said silicone type flame retardant, alkyl siloxane, alkylphenyl siloxane, etc. can be used, for example. More specifically, “X40-9805” (trade name) from Shin-Etsu Silicone, “MB50-315” (trade name) from Dow Corning Silicone, etc. can be used.

  Examples of the organic metal salt flame retardant include organic sulfonic acid metal salts such as potassium trichlorobenzene sulfonate, potassium perfluorobutane sulfonate, potassium diphenyl sulfonate-3-sulfonate, aromatic sulfonic imide metal salts, and styrene. Polystyrene sulfonic acid alkali metal salts in which sulfonic acid metal salts, sulfate metal salts, phosphate metal salts, borate metal salts are bonded to the aromatic ring of aromatic group-containing polymers such as polyphenylene ethers can be used. .

  Examples of the organic phosphorus flame retardant include phosphine, phosphine oxide, biphosphine, phosphonium salt, phosphinate, phosphate ester, phosphite ester, and the like. More specifically, triphenyl phosphate, methyl neopentyl phosphite, pentaerythritol diethyl diphosphite, methyl neopentyl phosphate, phenyl neopentyl phosphate, pentaerythritol diphenyl diphosphate, dicyclopentyl high positive phosphate, Dineopentyl hypophosphite, phenyl pyrocatechol phosphite, ethyl pyrocatechol phosphate, dipyrrocatechol high positive phosphate and the like can be used.

  Examples of the metal oxide flame retardant include magnesium oxide, and examples of the metal hydroxide flame retardant include magnesium hydroxide.

  It is preferable to add a lactic acid polyester as a modifier to the biodegradable resin composition. Thereby, not only the impact resistance is improved, but also the flame retarding effect is improved. As this lactic acid-based polyester, a polymer obtained by copolymerizing lactic acid, dicarboxylic acid and diol can be used. Examples of the dicarboxylic acid include succinic acid, adipic acid, sebacic acid, decanedicarboxylic acid, cyclohexanedicarboxylic acid, phthalic acid, terephthalic acid, and isophthalic acid. Examples of the diol include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and the like. More specifically, “EXP-PD-150” (trade name) manufactured by Dainippon Ink can be suitably used. Furthermore, as other modifiers, 1,3-butanediol sebacate and the like can be used.

  It is preferable to add talc, mica, montmorillonite, kaolin or the like as a filler to the biodegradable resin composition. When these become crystal nuclei, crystallization of polylactic acid is promoted, and the impact strength and heat resistance of the molded body are improved. Moreover, the rigidity of the molded body can be increased.

  The biodegradable resin composition further includes hemp fibers, chitin / chitosan, coconut shell fibers, kenaf, short fibers derived from these (length of 10 mm or less), powders derived therefrom, etc. Is preferably added. Thereby, the rigidity and heat resistance of a molded object can be improved. Moreover, these are natural materials and do not reduce the biodegradability of the molded body.

  It is preferable to add glass fiber, carbon fiber, glass flake, glass bead, etc. as a filler to the biodegradable resin composition. Thereby, the rigidity of a molded object can be enlarged.

  The filler may be subjected to surface treatment such as coating with polylactic acid or fatty acid, or may be surface treated with a silane coupling agent or the like.

  The biodegradable resin composition may contain other additives as necessary. For example, a carbodiimide compound, an isocyanate compound, an oxazoline compound, or the like can be added as a substance capable of suppressing the hydrolysis of the resin. Moreover, plasticizers, such as polyester and polyether other than lactic acid type, can also be added and used as needed. Furthermore, a weather resistance improver, an antioxidant, a heat stabilizer, an ultraviolet absorber, a crystal nucleating agent, a lubricant, a release agent, a colorant, a compatibilizing agent, and the like can be blended. These kneadings improve heat resistance, bending strength, impact strength, flame retardancy, etc., and further promote application to molded bodies such as casings for electronic devices such as laptop computers and mobile phones. The

  Next, the present invention will be specifically described based on examples.

(Example 1)
<Preparation of biodegradable resin composition (molding material)>
Glass fiber (filler) and modified resin made of polylactic acid (trade name: Lacia H-100J, manufactured by Mitsui Chemicals) and polystyrene (trade name: Stylon H8652, manufactured by Asahi Kasei) which is an amorphous resin An agent and a silicone flame retardant were kneaded using a kneader (trade name: TEX30α, manufactured by Nippon Steel Works) to prepare a molding material composed of a biodegradable resin composition.

  The blending ratio of the polylactic acid and polystyrene was polylactic acid: polystyrene = 70: 30 (% by weight).

  As the glass fiber, glass fiber having an average fiber length of 3 mm (trade name: CS03JAFT592, manufactured by Asahi Fiber Glass Co., Ltd.) was used. Examples of the modifier include lactic acid: succinic acid: propylene glycol = 50: 30: 20 (wt%) copolymer (lactic acid polyester, weight average molecular weight: 50000) and 1,3-butanediol sebacate. A 1 to 1 weight ratio mixture was used. As the silicone flame retardant, a flame retardant composed of polycarbonate and polydimethylsiloxane (trade name: MB50-315, manufactured by Dow Corning Silicone) was used.

  The compounding ratio of the resin, glass fiber, modifier, and silicone flame retardant in the molding material is 80: 10: 5: 5 (= resin: glass fiber: modifier: silicone flame retardant, wt%). It was.

  The cylinder temperature of the kneader was 220 ° C., and the screw rotation speed was 150 rpm.

The composition of the molding material excluding the modifier is shown in Table 1. In Table 1, polystyrene is indicated as PS.
<Measurement of high temperature stiffness>
A test piece (60 mm × 180 mm × 0.8 mm) was prepared from the molding material obtained as described above by injection molding (cylinder temperature: 190 ° C., mold temperature: 80 ° C.), and the high-temperature rigidity was measured. . Specifically, the displacement of the central portion p due to its own weight when the left and right 17 mm of the test piece was fixed with a double-supported beam shown in FIG. The results are shown in Table 2.
<Measurement of Izod impact strength>
From the molding material obtained as described above, a JIS Z 2204 No. 2 A test piece (12 mm × 64 mm × 3.2 mm, notch 2) was formed by injection molding (cylinder temperature: 190 ° C., mold temperature: 80 ° C.). 54 mm) and Izod impact strength was measured. Specifically, an Izod impact test was performed using an Izod impact tester (trade name: B-121202403, manufactured by Toyo Seiki Co., Ltd.) in accordance with JIS 7110. The results are shown in Table 2.
<Evaluation of flame retardancy>
From the molding material obtained as described above, a test piece for combustion test (125 mm × 13 mm × 1 mm) is prepared by injection molding (cylinder temperature: 190 ° C., mold temperature: 80 ° C.), and a combustion test is performed. It was. Specifically, according to a method based on the UL94 vertical combustion test method, a combustion test is performed by bringing a burner flame of about 2.5 cm into contact with the above test piece in a UL combustion test chamber (trade name: HVUL, manufactured by Toyo Seiki). The flame retardancy was evaluated. The results are shown in Table 2.

The UL94 vertical combustion test method is evaluated in 6 grades of 5VA, 5VB, V-0, V-1, V-2, and HB in descending order of flame retardancy.
<Evaluation of formability>
The notebook computer case (265 mm x 175 mm x 0.8 mm) shown in Fig. 1 is prepared from the molding material obtained as described above by injection molding (cylinder temperature: 190 ° C, mold temperature: 80 ° C). And the quality of the moldability was evaluated by measuring the size of the warp of the housing. The results are shown in Table 2.

  For the size of the warp, 24 points of displacement were measured for the entire casing, and the maximum value was adopted.

(Example 2)
Example 1 except that the silicone, flame retardant was not included, and the compounding ratio of resin, glass fiber, and modifier in the molding material was 85: 10: 5 (= resin: glass fiber: modifier, wt%). A molding material was prepared in the same manner as described above. The main composition of the molding material is shown in Table 1. In addition, measurement of high-temperature rigidity, measurement of Izod impact strength, evaluation of flame retardancy and evaluation of moldability were performed in the same manner as in Example 1, and the results are shown in Table 2.

(Example 3)
Molded in the same manner as in Example 1 except that it does not contain glass fiber and silicone flame retardant, and the blending ratio of resin and modifier in the molding material is 95: 5 (= resin: modifier, wt%). The material was prepared. The main composition of the molding material is shown in Table 1. In addition, measurement of high-temperature rigidity, measurement of Izod impact strength, evaluation of flame retardancy and evaluation of moldability were performed in the same manner as in Example 1, and the results are shown in Table 2.

Example 4
A molding material was obtained in the same manner as in Example 1 except that ABS resin (trade name: Stylac 121, manufactured by Asahi Kasei) was used instead of polystyrene, and the cylinder temperature of the kneader was set to 240 ° C. Prepared. The main composition of the molding material is shown in Table 1. Further, except that the injection molding cylinder temperature was set to 220 ° C., the high temperature stiffness measurement, the Izod impact strength measurement, the flame retardance evaluation, and the moldability evaluation were performed in the same manner as in Example 1, and the results are shown. It was shown in 2. In Table 1, the ABS resin is indicated as ABS.

(Example 5)
Example 4 except that the silicone-based flame retardant was not included and the compounding ratio of the resin, glass fiber, and modifier in the molding material was 85: 10: 5 (= resin: glass fiber: modifier, wt%). A molding material was prepared in the same manner as described above. The main composition of the molding material is shown in Table 1. In addition, measurement of high-temperature rigidity, measurement of Izod impact strength, evaluation of flame retardancy and evaluation of moldability were performed in the same manner as in Example 1, and the results are shown in Table 2.

(Example 6)
Molded in the same manner as in Example 4 except that it does not contain glass fiber and silicone flame retardant, and the blending ratio of resin and modifier in the molding material is 95: 5 (= resin: modifier, wt%). The material was prepared. The main composition of the molding material is shown in Table 1. In addition, measurement of high-temperature rigidity, measurement of Izod impact strength, evaluation of flame retardancy and evaluation of moldability were performed in the same manner as in Example 1, and the results are shown in Table 2.

(Example 7)
A molding material was obtained in the same manner as in Example 1 except that polycarbonate (trade name: Toughlon A1900, manufactured by Idemitsu Petrochemical Co., Ltd.), which is an amorphous resin, was used instead of polystyrene, and the cylinder temperature of the kneader was set to 260 ° C. Prepared. The main composition of the molding material is shown in Table 1. Further, except that the injection molding cylinder temperature was set to 240 ° C., the high temperature stiffness measurement, the Izod impact strength measurement, the flame retardance evaluation, and the moldability evaluation were performed in the same manner as in Example 1, and the results are shown. It was shown in 2. In Table 1, polycarbonate is indicated as PC.

(Example 8)
Example 7 except that the silicone-based flame retardant was not included and the compounding ratio of the resin, glass fiber, and modifier in the molding material was 85: 10: 5 (= resin: glass fiber: modifier, wt%). A molding material was prepared in the same manner as described above. The main composition of the molding material is shown in Table 1. In addition, measurement of high-temperature rigidity, measurement of Izod impact strength, evaluation of flame retardancy and evaluation of moldability were performed in the same manner as in Example 1, and the results are shown in Table 2.

Example 9
Molded in the same manner as in Example 7 except that it does not contain glass fiber and silicone flame retardant, and the blending ratio of resin and modifier in the molding material is 95: 5 (= resin: modifier, wt%). The material was prepared. The main composition of the molding material is shown in Table 1. In addition, measurement of high-temperature rigidity, measurement of Izod impact strength, evaluation of flame retardancy and evaluation of moldability were performed in the same manner as in Example 1, and the results are shown in Table 2.

(Comparative Example 1)
A molding material was prepared in the same manner as in Example 3 except that a resin composed only of polylactic acid not containing polystyrene was used. The main composition of the molding material is shown in Table 1. In addition, measurement of high-temperature rigidity, measurement of Izod impact strength, evaluation of flame retardancy and evaluation of moldability were performed in the same manner as in Example 1, and the results are shown in Table 2.

(Comparative Example 2)
A molding material was prepared in the same manner as in Example 1, except that polyethylene terephthalate (trade name: W3030, manufactured by Teijin), which is a crystalline resin, was used instead of polystyrene, and the cylinder temperature of the kneader was 250 ° C. The main composition of the molding material is shown in Table 1. Further, except that the injection molding cylinder temperature was 240 ° C. and the mold temperature was 100 ° C., the high temperature stiffness measurement, the Izod impact strength measurement, the flame retardancy evaluation, and the moldability evaluation were performed in the same manner as in Example 1. The results are shown in Table 2. In Table 1, polyethylene terephthalate is indicated as PET.

  As is apparent from Tables 1 and 2, the molded articles of Examples 1 to 9 have higher high-temperature rigidity and Izod impact strength than Comparative Examples 1 and 2, and excellent moldability. I understand. Thereby, even if a molded article is formed by injection molding, a biodegradable resin that does not decrease in strength and heat resistance and a resin casing using the same can be provided.

  Moreover, in Example 1, Example 4 and Example 7 to which a flame retardant was added, flame retardance was all able to achieve V-2 with UL94. Moreover, in Example 1, Example 2, Example 4, Example 5, Example 7, and Example 8 to which the glass fiber was added, the Izod impact strength could be greatly improved.

  In addition, as for the moldability of Comparative Example 1, warpage was 10 mm or more, and twist occurred. Also in Comparative Example 2, warpage increased due to crystallization, and twisting occurred as in Comparative Example 1.

(Embodiment 2)
Next, another embodiment of the present invention will be described.

  Another example of the biodegradable resin composition of the present invention is a biodegradable resin composition containing polylactic acid and tannin.

  Another example of the resin casing of the present invention is a resin casing formed from the biodegradable resin composition.

  As polylactic acid, the thing similar to what was demonstrated in Embodiment 1 can be used, and there can exist an effect similar to Embodiment 1 by it. In order to realize the above effects, the polylactic acid is preferably contained in an amount of 50% by weight or more based on the total weight of the biodegradable resin composition, as in the first embodiment.

  Moreover, since the said biodegradable resin composition contains tannin, even if it sets to mold temperature higher than the glass transition temperature (about 60 degreeC) of polylactic acid in the case of injection molding, it suppresses softening of resin. It is possible to reduce the occurrence of deformation of the molded product and defective mold release at the time of mold release. Moreover, flame retardance can be improved without adding a flame retardant.

  Tannins are called polyhydric phenols including tannic acids, catechins, leucoanthocyans, and chlorogenic acids, and are widely contained in natural plants. Tannins can be broadly divided into two types, hydrolyzed and condensed, but since both are natural compounds, there are many compounds with different structures. Examples of the hydrolyzed form include chinatannin, ellagitannin, chlorogenic acid composed of depsides such as caffeic acid and quinic acid, etc., among which chinatannin is an ester-linked gallic acid and its derivatives. On the other hand, the condensed type includes, for example, kepracotannin, wattle tannin, ganvil tannin, cut titanin, flava tannin and the like, and further includes catechins, leucoanthocyanes, leucoanthocyanidins and the like.

  In the present embodiment, any of the above tannins can be used. Tannic acid is also called tannin and is not particularly distinguished in the present invention. Since tannin is a compound widely contained in natural plants, there is a possibility that the chemical structure is partially different. In the present invention, polyphenols including such tannins and catechins having partially different chemical structures are used. As polyhydric phenols having different chemical structures, there are catechin, kebrotannin, turkey tannin, and the like. Polyhydric phenols having a dye fixing effect and a skin tanning effect are called “synthetic tannins” or “syntans”, but these polyhydric phenols may be used in the present invention. In the present embodiment, one or more of these tannins can be mixed and used. Further, tannin, a dehydrated polycondensed tannin thereof, a copolymerized tannin copolymerized with polyethylene glycol or polyvinyl alcohol can be mixed and used.

  It is preferable to add a phosphate ester to the biodegradable resin composition. Thereby, the flame retardance of resin can further be improved. This is because by adding a phosphate ester, various tannins are combined with the phosphate ester to form a network bond between the polylactic acid polymers, resulting in less movement of the polymer molecules and combustion of the resin. It is thought that it can be suppressed. The mixing ratio of tannin and phosphate ester is preferably tannin: phosphate ester = 1: 0.1 to 1:10 in weight ratio.

  Phosphate esters are roughly classified into aliphatic and aromatic. Examples of the aliphatic system include trimethyl phosphate and triethyl phosphate. In addition, there are many compounds in the aromatic system, and phosphoric acid exists in a wide variety such as one molecule, two molecules, and three molecules. In the case of a phosphoric acid ester compound in the chemical structure, even if there is a slight molecular structure difference, for example, a difference between a methyl group and an ethyl group, or a difference in the presence or absence of chemical modification as a side chain of the benzene ring, the flame retardant of the resin Sex is not affected. In the present embodiment, a plurality of these phosphate esters can be mixed and used.

  Moreover, it is preferable to add at least one biodegradable resin selected from polycaprolactone, polyhydroxybutyrate, polybutylene succinate, and derivatives thereof to the biodegradable resin composition. Thereby, molding shrinkage is stabilized and impact resistance is improved.

  The biodegradable resin composition preferably further includes an amorphous resin having a glass transition temperature higher than that of polylactic acid described in the first embodiment. This is because the same effects as those of the first embodiment can be further achieved.

  In the biodegradable resin composition, as in the first embodiment, a silicone flame retardant, an organic metal salt flame retardant, an organic phosphorus flame retardant, a metal oxide flame retardant, and a metal hydroxide flame retardant Etc. can be added.

  It is preferable to add a lactic acid polyester as a modifier to the biodegradable resin composition. Thereby, not only the impact resistance is improved, but also the flame retarding effect is improved. As the lactic acid-based polyester, those described in the first embodiment can be used.

  The biodegradable resin composition is derived from talc, mica, montmorillonite, kaolin, etc., or hemp fiber, chitin / chitosan, coconut shell fiber, kenaf, and the like, as in the first embodiment. It is preferable to add short fibers (10 mm or less in length), powders derived from these, glass fibers, carbon fibers, glass flakes, glass beads, or the like.

  Further, the filler may be surface-treated such as coating with polylactic acid or fatty acid, or may be surface-treated with silane coupling agent or the like, as in the first embodiment. . Furthermore, the biodegradable resin composition can contain other additives as necessary, as in the first embodiment.

  Next, the present invention will be specifically described based on examples.

(Example 10)
<Preparation of biodegradable resin composition (molding material)>
Polylactic acid (trade name: Lacia H-100J, manufactured by Mitsui Chemicals), China tannin (manufactured by Koso Chemical), and [2,2'-methylenebis- (4,6-di-tert-butyl) which is a phosphate ester Phenyl) octyl phosphite (trade name: MARKHP-10, manufactured by Adeka Argus) and a glass fiber (filler) and a modifier are used in a kneader (trade name: TEX30α, manufactured by Nippon Steel Works). And kneaded to prepare a molding material comprising a biodegradable resin composition.

  The compounding ratio of the polylactic acid, the china tannin and the phosphate ester was polylactic acid: china tannin: phosphate ester = 100: 0.5: 1.0 (weight ratio).

  As the glass fiber, glass fiber having an average fiber length of 3 mm (trade name: CS03JAFT592, manufactured by Asahi Fiber Glass Co., Ltd.) was used. Examples of the modifier include lactic acid: succinic acid: propylene glycol = 50: 30: 20 (wt%) copolymer (lactic acid polyester, weight average molecular weight: 50000) and 1,3-butanediol sebacate. A 1 to 1 weight ratio mixture was used.

  The blending ratio of the resin, glass fiber, and modifier in the molding material was 85: 10: 5 (= resin: glass fiber: modifier, wt%).

  The cylinder temperature of the kneader was 190 ° C., and the screw rotation speed was 150 rpm.

The composition of the molding material is shown in Table 3.
<Measurement of high temperature stiffness>
A test piece (60 mm × 180 mm × 0.8 mm) was prepared from the molding material obtained as described above by injection molding (cylinder temperature: 190 ° C., mold temperature: 40 ° C.). The high temperature stiffness was measured. The results are shown in Table 4.
<Measurement of Izod impact strength>
JIS Z 2204 No. 2 test piece (12 mm × 64 mm × 3.2 mm, notch 2) was formed from the molding material obtained as described above by injection molding (cylinder temperature: 190 ° C., mold temperature: 40 ° C.). 54 mm) and Izod impact strength was measured in the same manner as in Example 1. The results are shown in Table 4.
<Evaluation of flame retardancy>
From the molding material obtained as described above, a test piece for combustion test (125 mm × 13 mm × 1 mm) was prepared by injection molding (cylinder temperature: 190 ° C., mold temperature: 40 ° C.). A combustion test was conducted in the same manner. The results are shown in Table 4.
<Evaluation of formability>
The notebook computer case (265 mm x 175 mm x 0.8 mm) shown in Fig. 1 is prepared from the molding material obtained as described above by injection molding (cylinder temperature: 190 ° C, mold temperature: 40 ° C). In the same manner as in Example 1, the quality of the moldability was evaluated. The results are shown in Table 4.

(Example 11)
A molding material was prepared in the same manner as in Example 10 except that the mixing ratio of the resin and the modifier in the molding material was 95: 5 (= resin: modifier, wt%). The composition of the molding material is shown in Table 3. Further, high temperature rigidity measurement, Izod impact strength measurement, flame retardancy evaluation and moldability evaluation were performed in the same manner as in Example 10, and the results are shown in Table 4.

(Example 12)
Polylactic acid (trade name: Lacia H-100J, manufactured by Mitsui Chemicals), China tannin (manufactured by Koso Chemical), and [2,2'-methylenebis- (4,6-di-tert-butyl) which is a phosphate ester Phenyl) octyl phosphite (trade name: MARKHP-10, manufactured by Adeka Argus) and polybutylene succinate (trade name: Bionore 1020, manufactured by Showa Polymer Co., Ltd.), which is a biodegradable resin, was added to the resin. A molding material was prepared in the same manner as in Example 10. The blending ratio of the above polylactic acid, polybutylene succinate, china tannin and phosphate ester is as follows: polylactic acid: polybutylene succinate: china tannin: phosphate ester = 80: 20: 0.5: 1.0 (weight ratio) ). The composition of the molding material is shown in Table 3.

  In addition, except that the injection molding cylinder temperature was 220 ° C., the high temperature stiffness measurement, the Izod impact strength measurement, the flame retardance evaluation, and the moldability evaluation were performed in the same manner as in Example 10, and the results are shown. This is shown in FIG. In Table 4, polybutylene succinate is indicated as PBS.

(Example 13)
A molding material was prepared in the same manner as in Example 12 except that the mixing ratio of the resin and the modifier in the molding material was 95: 5 (= resin: modifier, wt%). The composition of the molding material is shown in Table 3. Further, in the same manner as in Example 12, measurement of high-temperature rigidity, measurement of Izod impact strength, evaluation of flame retardancy, and evaluation of moldability were performed, and the results are shown in Table 4.

(Example 14)
Polylactic acid (trade name: Lacia H-100J, manufactured by Mitsui Chemicals), China tannin (manufactured by Koso Chemical), and [2,2'-methylenebis- (4,6-di-tert-butyl) which is a phosphate ester Phenyl) octyl phosphite (trade name: MARKHP-10, manufactured by Adeka Argus) is further added with an amorphous resin polycarbonate (trade name: Toughlon A1900, manufactured by Idemitsu Petrochemical Co., Ltd.), and the cylinder temperature of the kneader A molding material was prepared in the same manner as in Example 10 except that the temperature was 260 ° C. The blending ratio of the polylactic acid, polycarbonate, china tannin and phosphate ester was polylactic acid: polycarbonate: china tannin: phosphate ester = 80: 20: 0.5: 1.0 (weight ratio). The composition of the molding material is shown in Table 3.

  Further, except that the injection molding cylinder temperature was 240 ° C. and the mold temperature was 80 ° C., the high temperature stiffness measurement, the Izod impact strength measurement, the flame retardance evaluation and the moldability evaluation were carried out in the same manner as in Example 10. The results are shown in Table 4. In Table 4, polycarbonate is indicated as PC.

(Example 15)
A molding material was prepared in the same manner as in Example 14 except that the resin and modifier compounding ratio in the molding material was 95: 5 (= resin: modifier, wt%). The composition of the molding material is shown in Table 3. Further, high temperature rigidity measurement, Izod impact strength measurement, flame retardancy evaluation and moldability evaluation were performed in the same manner as in Example 14, and the results are shown in Table 4.

(Example 16)
A molding material was prepared in the same manner as in Example 10 except that the glass fiber and the modifier were not included. The composition of the molding material is shown in Table 3. Further, high temperature rigidity measurement, Izod impact strength measurement, flame retardancy evaluation and moldability evaluation were performed in the same manner as in Example 10, and the results are shown in Table 4.

(Example 17)
A molding material was prepared in the same manner as in Example 10 except that phosphate ester, glass fiber, and modifier were not included. The composition of the molding material is shown in Table 3. Further, high temperature rigidity measurement, Izod impact strength measurement, flame retardancy evaluation and moldability evaluation were performed in the same manner as in Example 10, and the results are shown in Table 4.

(Comparative Example 3)
A molding material was prepared in the same manner as in Example 17 except that a resin composed only of polylactic acid not containing tannin was used. The composition of the molding material is shown in Table 3. Further, in the same manner as in Example 17, measurement of high-temperature rigidity, measurement of Izod impact strength, evaluation of flame retardancy, and evaluation of moldability were performed, and the results are shown in Table 4.

  Comparative example 3 has the same contents as comparative example 1 of the first embodiment.

  As is apparent from Tables 3 and 4, it can be seen that the molded articles of Examples 10 to 17 have a higher high-temperature rigidity than that of Comparative Example 3 and are excellent in moldability. Thereby, even if a molded article is formed by injection molding, a biodegradable resin that does not decrease in strength and heat resistance and a resin casing using the same can be provided.

  Moreover, in Examples 10-16 which added tannin and phosphate ester, flame retardance was able to achieve V-2 by UL94. Moreover, in Example 10, Example 12, and Example 14 to which glass fiber was added, the Izod impact strength could be greatly improved.

  Further, it can be seen that Example 14 and Example 15 in which polycarbonate was added as an amorphous resin had higher high-temperature rigidity and Izod impact strength than Comparative Example 3, and were excellent in moldability.

  As a summary of the above, the configurations of the present invention and variations thereof are listed below as supplementary notes.

  (Appendix 1) A biodegradable resin composition comprising polylactic acid and an amorphous resin having a glass transition temperature higher than that of the polylactic acid.

  (Appendix 2) A biodegradable resin composition comprising polylactic acid and tannin.

  (Additional remark 3) The biodegradable resin composition of Additional remark 2 which further contains phosphate ester.

  (Supplementary note 4) The biodegradable resin composition according to supplementary note 2 or 3, further comprising at least one biodegradable resin selected from polycaprolactone, polyhydroxybutyrate, polybutylene succinate, and derivatives thereof.

  (Appendix 5) The biodegradable resin composition according to any one of appendices 2 to 4, further including an amorphous resin having a glass transition temperature higher than that of the polylactic acid.

  (Appendix 6) The amorphous resin is polyvinyl chloride, polystyrene, ABS resin, AS resin, ASA resin, polycarbonate, polymethyl methacrylate, modified polyphenylene ether, polysulfone, polyethersulfone, polyarylate, polyamideimide, poly 6. The biodegradable resin composition according to appendix 1 or 5, wherein the biodegradable resin composition is at least one kind of resin selected from ether imide, thermoplastic polyimide, styrene elastomer, ethylene vinyl acetate copolymer, and polyether ether ketone.

  (Supplementary note 7) Additional note further including at least one flame retardant selected from a silicone-based flame retardant, an organic metal salt-based flame retardant, an organic phosphorus-based flame retardant, a metal oxide-based flame retardant, and a metal hydroxide-based flame retardant The biodegradable resin composition according to any one of 1 to 6.

  (Additional remark 8) The biodegradable resin composition in any one of Additional remark 1-7 which further contains lactic acid-type polyester.

  (Supplementary note 9) The biodegradable resin composition according to any one of supplementary notes 1 to 8, further comprising at least one selected from talc, mica, montmorillonite, and kaolin.

(Appendix 10)
The biodegradation according to any one of supplementary notes 1 to 9, further comprising at least one selected from hemp fiber, chitin / chitosan, coconut shell fiber, kenaf, short fiber derived therefrom, and powder derived therefrom. Resin composition.

  (Additional remark 11) The biodegradable resin composition in any one of Additional remark 1-10 which further contains at least 1 sort (s) chosen from glass fiber, carbon fiber, glass flakes, and glass beads.

  (Additional remark 12) The resin housing | casing characterized by being formed from the biodegradable resin composition in any one of Additional remarks 1-11.

  As described above, according to the present invention, a resin casing using a biodegradable resin based on polylactic acid can be provided as a casing for an electronic device typified by a notebook computer, a mobile phone, or the like.

It is a front view of the housing | casing for notebook personal computers (LCD front cover) which is an example of the resin housing | casing which concerns on this invention. It is the top view A and side view B which show typically the measuring method of high temperature rigidity.

Explanation of symbols

  p Central part

Claims (5)

  A biodegradable resin composition comprising polylactic acid and an amorphous resin having a glass transition temperature higher than that of the polylactic acid.   The amorphous resin is polyvinyl chloride, polystyrene, ABS resin, AS resin, ASA resin, polycarbonate, polymethyl methacrylate, modified polyphenylene ether, polysulfone, polyethersulfone, polyarylate, polyamideimide, polyetherimide, heat The biodegradable resin composition according to claim 1, wherein the biodegradable resin composition is at least one resin selected from a plastic polyimide, a styrene-based elastomer, an ethylene vinyl acetate copolymer, and a polyether ether ketone.   A biodegradable resin composition comprising polylactic acid and tannin.   The biodegradable resin composition according to claim 3, further comprising a phosphate ester. A resin casing formed from the biodegradable resin composition according to claim 1.

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