JP5463670B2 - Thermoplastic resin composition - Google Patents

Description

  The present invention relates to a thermoplastic resin composition containing a high molecular weight plant-derived resin, a flexibility imparting agent and an inorganic flame retardant, and further containing a plasticizer and achieving excellent toughness and flame retardancy.

  In recent years, plant-derived resins have attracted attention as an alternative to petroleum raw materials, and practical application of resin compositions using various plant-derived resins has been actively studied. As an example of plant-derived resins, polylactic acid resins have recently attracted particular attention and are being commercialized for various uses. The plant-derived resin is used for a short period of use, such as containers and packaging, agricultural films, and the like, as well as for household appliances, mobile phones, OA equipment housings, and automotive parts. In particular, there are a wide variety of applications that can maintain the initial characteristics for a long period of time.

  However, since these plant-derived resins, particularly polylactic acid resins, are inferior in toughness, this property must be reinforced. In addition, when plant-derived resins are used for applications that require not only toughness but also high flame resistance, such as housings for home appliances and OA equipment and automobile parts, these characteristics are achieved at the same time. There is a need to. In particular, when a resin composition made of a plant-derived resin is used for a housing of an electrical product, it must satisfy flame retardancy standards such as the US UL (Underwriters Laboratories Inc.) standard. However, the resin composition comprising an existing plant-derived resin could not satisfy the flame retardancy standard.

  On the other hand, as a general method, there is a method in which a flame retardant such as a bromine compound having a high flame retardant efficiency is blended with a resin to make it flame retardant. However, when a halogen-based flame retardant is added to a polycarbonate resin, which is a typical polyester-based resin, if the resin is repeatedly melt-kneaded for reuse, the resin deteriorates and physical properties such as flame retardancy and impact resistance are lost. There was a problem to be reduced. Therefore, when a halogen-based flame retardant is used for a polylactic acid resin having an ester bond, which is a representative of plant-derived resins, there has been a concern that the physical properties may be lowered when melt-kneaded repeatedly as in the case of the polycarbonate resin.

On the other hand, at least one flame retardant additive selected from phosphorus compounds, hydroxide compounds (also called metal hydrates, including aluminum hydroxide) and silica compounds is used in the polylactic acid resin. A biodegradable resin composition is disclosed in Patent Document 1.
JP 2003-192925 A

  However, the above-described conventional techniques have the following problems. That is, polylactic acid resin (this resin also has biodegradability), which is representative of plant-derived resins, is generally a brittle material and has insufficient flame retardancy, so it can be applied to housings for home appliances and OA equipment. There was a problem to do.

  Furthermore, the polylactic acid resin composition described in Patent Document 1, that is, a polylactic acid resin composition containing 50% by mass of the exemplified aluminum hydroxide having a purity of 99.5% by mass (= polylactic acid + water). Aluminum oxide + mass ratio in the total amount of hydrolysis-resistant formulation) is only compatible with V-2 in the UL standard, and is more highly flame retardant required for household appliances and OA equipment housing applications There was a problem that (V-1 or higher) cannot be satisfied.

  In addition, the polylactic acid resin composition containing 50% by mass of aluminum hydroxide described in Patent Document 1 has a bending fracture strain of only about 1%, and is tough to be applied to a housing of home appliances or OA equipment. There was a problem that was not enough.

  This invention is made | formed in view of this subject, Comprising: It aims at providing the thermoplastic resin composition containing the plant-derived resin which is excellent in toughness and a flame retardance.

  The thermoplastic resin composition according to the present invention contains a high molecular weight polylactic acid (A), a flexibility-imparting agent (B), and an inorganic flame retardant (C). The melt flow rate at 15 ° C. is less than 15.

  The thermoplastic resin composition according to the present invention contains a plasticizer (D) in addition to the high molecular weight polylactic acid (A), the flexibility imparting agent (B), and the inorganic flame retardant (C). It is characterized by that.

  The thermoplastic resin composition containing a plant-derived resin according to the present invention comprises a high molecular weight polylactic acid (A), a flexibility imparting agent (B), an inorganic flame retardant (C), and a plasticizer (D ), It is possible to achieve excellent toughness and flame retardancy.

  That is, the thermoplastic resin composition according to the present invention having the inorganic flame retardant (C) as essential components first contains a high molecular weight polylactic acid (A) and a flexibility-imparting agent (B) at the same time. Exhibit excellent toughness (especially large fracture strain). Furthermore, the thermoplastic resin composition according to the present invention containing the inorganic flame retardant (C) as an essential component includes the high molecular weight polylactic acid (A), the flexibility-imparting agent (B), and the plasticizer (D). When the three components are simultaneously contained, a synergistic effect that specifically improves toughness is exhibited. In particular, the breaking strain is remarkably improved.

It is a graph which shows the relationship between a bending fracture | rupture distortion and a melt flow rate.

  The present invention will be described in further detail below.

  The present invention contains a high molecular weight polylactic acid (A), a flexibility imparting agent (B) and an inorganic flame retardant (C), and further contains a plasticizer (D). The present invention relates to a resin composition.

  The high molecular weight polylactic acid (A) according to the present invention is a polylactic acid having a melt flow rate (hereinafter referred to as MFR) at 190 ° C. of less than 15, and the lower this value, the better the toughness. effective.

  Here, MFR is an extrusion type plastometer, which measures the mass (g) of resin flowing out from a nozzle (orifice) having a prescribed size under a constant pressure and a constant temperature for 10 minutes. The index is expressed in units of 10 minutes. In general, a smaller MFR value indicates a resin having lower fluidity at the time of melting, that is, a higher molecular weight. Here, in general, the MFR is measured for polylactic acid, that is, in accordance with ISO (International Standardizing Organization) 1133, an extrusion plastometer is used to set the melting temperature to 190 ° C., and a load of 2.16 kg. The mass (g / 10 minutes) of the resin flowing out for 10 minutes when added was defined as MFR. In the thermoplastic resin composition according to the present invention, in the case of the high molecular weight polylactic acid having an MFR of less than 15, an effect of specifically improving the breaking strain is exhibited.

  However, when the MFR of the high molecular weight polylactic acid (A) is too small (that is, when the molecular weight of the polylactic acid is further increased), the thermoplasticity of the present invention containing the inorganic flame retardant (C) as an essential component. Since the fluidity of the resin composition is lowered and sufficient moldability may not be obtained, the MFR is preferably 3 or more. The molecular structure of polylactic acid is usually linear, but may be branched.

  The flexibility-imparting agent (B) according to the present invention is not particularly limited as long as it is composed of an organic substance having a lower elastic modulus at room temperature than polylactic acid, but is compatible with polylactic acid. A compound having a possible structural unit and a structural unit exhibiting flexibility in the same structure is preferable. Specific examples of the organic substance constituting the flexibility-imparting agent (B) include a copolymer composed of three components of polylactic acid, glycols, and linear saturated dicarboxylic acid. Examples of the glycols constituting the copolymer include ethylene glycol, propylene glycol, diethylene glycol and the like. Examples of the linear saturated dicarboxylic acid constituting the copolymer include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid. Specific examples of the organic substance constituting the flexibility-imparting agent (B) include, in addition to the above, polybutylene succinate, copolymer of polybutylene succinate and polylactic acid, polycaprolactone, copolymer of polycaprolactone and polylactic acid Copolymer, natural rubber, acrylic resin including polymethyl methacrylate (PMMA), a copolymer having a polymer block selected from the group consisting of a polyester segment, a polyether segment and a polyhydroxycarboxylic acid segment, a polylactic acid segment, Block copolymer in which aromatic polyester segment and polyalkylene ether segment are bonded to each other, polymer based on unsaturated carboxylic acid alkyl ester unit, polyethylene succinate, polyethylene adipate, polypropylene azide Chromatography, polybutylene adipate, polyhexamethylene adipate, aliphatic polyesters such as polybutylene succinate adipate, and also polyethylene glycol and esters thereof.

  The mass ratio of the high molecular weight polylactic acid (A) and the flexibility-imparting agent (B) can be 95: 5 to 50:50, but preferably 92: 8 to 70:30. is there.

  The inorganic flame retardant (C) according to the present invention is particularly preferably a metal hydrate. Moreover, as a flame retardant other than the flame retardant (C), a flame retardant other than a halogen flame retardant, such as a nitrogen flame retardant or a phosphorus flame retardant, may be used in combination. Halogen flame retardants capture and reduce active radicals (· OH, · H) generated during the combustion of plastic, and inhibit and cut the combustion cycle by changing to a more inert form. Further, it has a mechanism for generating a gaseous halogen compound to block the polymer from heat and oxygen, and does not simply mean that it contains halogen.

  The flame retardant (C) according to the present invention is an inorganic substance having a content of an alkali metal substance of 0.2% by mass or less, and further, a metal hydrate that exhibits an endothermic effect upon thermal decomposition. In addition to being excellent in flame retardancy, when used in combination with a plant-derived resin having an ester bond (eg, represented by polylactic acid), the molecular weight of the plant-derived resin having an ester bond is particularly small. Preferred (hydrolysis resistance is good).

  Examples of such inorganic flame retardants (C) include aluminum hydroxide, boehmite, magnesium hydroxide, dosonite, calcium aluminate, hydrated gypsum, calcium hydroxide, zinc borate, barium metaborate, borax, kaolin clay. And calcium carbonate, an inorganic filler whose surface is treated with various organic substances such as an epoxy resin and a phenol resin, and an inorganic filler in which a metal is solidified. Among these, aluminum hydroxide, which is a representative metal hydrate, is particularly preferable because it has a particularly high endothermic effect and excellent flame retardancy.

  Furthermore, in this invention, the dispersibility in the plant origin resin contained in the thermoplastic resin composition of this invention is favorable as the 50 mass% particle size of an inorganic type flame retardant (C) is the range of 20 micrometers or less. It is more preferable because it is excellent in the effect of improving flame retardancy and mechanical properties. When the 50% by mass particle diameter of the inorganic flame retardant (C) is 20 μm or less, the surface properties of the thermoplastic resin composition containing the inorganic flame retardant are excellent, and the design does not deteriorate due to unevenness on the surface.

  Furthermore, when the weight ratio of the inorganic flame retardant (C) in the total amount of the thermoplastic resin composition of the present invention is X, the X is in the range of 30% by mass to 60% by mass. In addition to flame retardancy and fluidity, the thermal decomposition resistance is also excellent, which is more preferable. In addition, a flame retardance may become inadequate that the weight ratio X of said inorganic type flame retardant (C) is less than 30 mass%. Moreover, when the weight ratio X of said inorganic type flame retardant (C) exceeds 60 mass%, fluidity | liquidity and thermal decomposition resistance may fall.

  Moreover, as a flame retardant other than the flame retardant (C) and the halogen flame retardant, a nitrogen flame retardant, a phosphorus flame retardant, or the like can be used. Examples of these nitrogen-based flame retardants include melamine and isocyanuric acid compounds, and examples of phosphorus-based flame retardants include red phosphorus, phosphoric acid compounds, and organic phosphorus compounds. In particular, in the thermoplastic resin composition of the present invention, when the inorganic flame retardant (C) contains a metal hydrate such as aluminum hydroxide, the above-mentioned nitrogen flame retardant or phosphorus flame retardant The amount of added can be small, and deterioration of other physical properties such as moisture resistance, heat resistance, mechanical properties and the like caused by the flame retardant other than the inorganic flame retardant (C) can be suppressed. In addition, the above inorganic flame retardant (C) and other flame retardants may be used after being pretreated to high-strength fibers or plant-derived fibers.

  The plasticizer (D) according to the present invention includes a “lubricant” having a releasing effect in a broad sense. The plasticizer (D) is not particularly limited as long as it penetrates between polymer molecules, particularly between polylactic acid molecules, weakens the intermolecular force between the polymers and facilitates the movement of the molecular chain. Absent. Specific examples of the plasticizer (D) include dimethyl adipate, dibutyl adipate, diisobutyl adipate, bis (2-ethylhexyl) adipate, diisononyl adipate, diisodecyl adipate, bis (butyl diglycol) adipate, bis (butyl diglycol) adipate Bis (2-ethylhexyl) azelate, dimethyl sebacate, dibutyl sebacate, bis (2-ethylhexyl) sebacate, bis (2-ethylhexyl) sebacate, diethyl succinate, bismethyldiethylene glycol adipate, benzyl-2- (2-methoxy Aliphatic dibasic acid esters such as ethoxy) ethyl adipate, ditridecyl phthalate, dinormal octyl phthalate, diisononyl phthalate, dimethyl phthalate, diethyl Phthalates such as tarate, dibutyl phthalate, bis (2-ethylhexyl) phthalate, di-n-octyl phthalate, diisodecyl phthalate, butyl benzyl phthalate, diisononyl phthalate, ethyl phthalyl ethyl glycolate, tri-normal octyl trimellitate, tri Trimellitic acid esters such as isodecyl trimellitate and tris (2-ethylhexyl) trimellitate, trimethyl phosphate, triethyl phosphate, tributyl phosphate, tris (2-ethylhexyl) phosphate, tris (butoxyethyl) phosphate, triphenyl phosphate, tricres Zyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, 2-ethylhexyl diphenyl phosphate Phosphoric acid esters such as methyl acetyl ricinoleate, aliphatic polyesters such as poly (1,3-butanediol adipate), polyglycerin acetates, epoxidized polyesters such as epoxidized soybean oil, epoxidized linseed Oil, epoxidized linseed oil fatty acid butyl, glyceryl triacetate, acetate ester such as 2-ethylhexyl acetate, sulfonamide such as N-butylbenzenesulfonamide, chlorinated paraffin, liquid paraffin such as alkylnaphthene hydrocarbon, n-paraffin, etc. Paraffin wax, polyethylene waxes such as low molecular weight polyethylene, partially oxidized polyethylene, octyl alcohol, decyl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol Fatty alcohols such as cole, fatty acids such as linolenic acid, linoleic acid, oleic acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, hydroxy fatty acids such as castor oil derived from 12-hydroxystearic acid, methyl stearate Fatty acid esters such as octyl stearate, stearyl stearate, ethylene glycol monostearate, ethylene glycol distearate, methyl 12-hydroxystearate, stearyl 12-hydroxystearate, ethylene glycol mono-12-hydroxystearate, mono- Hydroxy fatty acid esters such as propylene glycol 12-hydroxystearate, stearylamide, N-hydroxyethyl-ricinoleylamide, N-hydroxyethyl-12-hydro Cysteallylamide, N, N′-ethylene-bis-oleylamide, N, N′-ethylene-bis-ricinoleylamide, N, N′-ethylene-bis-octadecadienylamide, N, N′- Ethylene-bis-12-hydroxystearylamide, N, N′-ethylene-bis-stearylamide, N, N′-hexamethylene-bis-ricinoleylamide, N, N′-hexamethylene-bis-12-hydroxy Examples thereof include fatty acid amides such as stearylamide and N, N′-xylylene-bis-12-hydroxystearylamide, and aliphatic soaps.

  When adding the said plasticizer (D) to the thermoplastic resin composition of this invention, it is preferable to add so that it may become 5 mass% or less with respect to the total amount of the said thermoplastic resin composition. If this value exceeds 5%, sufficient flame retardancy may not be obtained.

  In the thermoplastic resin composition of the present invention, when the high molecular weight polylactic acid (A, hereinafter, high molecular weight polylactic acid) and the flexibility-imparting agent (B) are contained simultaneously, the high molecular weight polylactic acid ( In the case of A) alone, polylactic acid other than the high molecular weight polylactic acid (A) (hereinafter referred to as low molecular weight polylactic acid (a)) alone, the flexibility imparting agent to the low molecular weight polylactic acid (a) Compared with the case where (B) is added, the breaking strain is excellent. Hereinafter, the high molecular weight polylactic acid (A) according to the present invention is referred to as crystalline high molecular weight polylactic acid having a MFR of less than 15 (hereinafter referred to as high molecular weight poly L lactic acid (A1). It has a crystalline part and an amorphous part. ) As a flexibility-imparting agent (B), a compound having a structural unit that is compatible with polylactic acid and a structural unit exhibiting flexibility in the same structure, for example, polylactic acid and glycols and linear saturated A mechanism for improving toughness, particularly breaking strain, will be described for each of the cases where a copolymer composed of three components of dicarboxylic acid is used.

  The flexibility imparting agent (B) having a saturated aliphatic chain having a small interaction between molecular chains and polylactic acid as a structural unit is a flexible copolymer, and a part thereof is composed of polylactic acid. Can be compatibilized. Therefore, the molecule | numerator of the said flexibility imparting agent (B) tends to form the entanglement of molecular chains between polylactic acid molecules. In particular, when the high molecular weight poly L lactic acid (A1) according to the present invention is used, the molecular chains are easily entangled with each other, and the distance of entanglement becomes long. As a result, the toughness is estimated to have been effectively improved.

  In the thermoplastic resin composition of the present invention, when the plasticizer (D) is further used in addition to the high molecular weight poly L lactic acid (A1) and the flexibility imparting agent (B), the high molecular weight polylactic acid ( Compared with the case where only two components of A1) and the flexibility imparting agent (B) are contained, the toughness is remarkably improved. Explaining the mechanism of synergistically improving toughness, particularly breaking strain, when a compound that exhibits a sliding effect between polylactic acid molecules, such as trimellitic acid ester, is used as the plasticizer (D). .

In addition to the high molecular weight poly L lactic acid (A1) and the flexibility-imparting agent (B), it was speculated that the presence of the plasticizer (D) would significantly improve toughness due to the following three effects. The three effects are
[1] Effect of improving the dispersibility of the high molecular weight poly-L-lactic acid (A1) and the flexibility-imparting agent (B) in the thermoplastic resin composition of the present invention by adding the plasticizer (D). ,
[2] The effect of increasing the entanglement of molecular chains of the high molecular weight poly-L lactic acid (A1) and the flexibility-imparting agent (B) by the dispersibility improving effect of [1],
[3] By adding the plasticizer (D), the intermolecular force is lowered, and as a result, slip is generated between the molecular chains.

  That is, since the dispersibility of the high molecular weight poly-L lactic acid (A1) and the flexibility-imparting agent (B) is improved by the addition of the plasticizer (D), the molecular chains of the (A1) and (B) And (A1) has a high molecular weight, and therefore, the distance of the entanglement between the molecular chains becomes longer than when only the low molecular weight polylactic acid (a) is used. Therefore, in the case where the thermoplastic resin composition of the present invention is deformed by stress, the stress relaxation caused by the flexibility of the flexibility-imparting agent (B) can be reduced as compared with the case where it consists of only the low molecular weight polylactic acid (a). While the effect is effectively manifested, a large amount of energy is consumed to break the entanglement between the molecular chains, and the plasticizer is interposed between the molecules, so the effect of sliding between the molecular chains is also manifested, and stress is assumed. It was speculated that the effect of mitigating the above appears. As a result, it is thought that it showed a significant improvement in fracture strain. Further, the polylactic acid crystals that are hard, brittle and hardly deformed become “flexible crystals” that are easily deformed against stress due to the addition effect of the plasticizer (D), and the thermoplastic resin composition of the present invention It is estimated that it contributed to the increase in the toughness of objects.

  The thermoplastic resin composition according to the present invention may contain organic substances derived from plants other than polylactic acid, and the structure thereof is not particularly limited. Examples of plant-derived organic substances other than polylactic acid include, for example, succinic acid-based plant-derived resins obtained from saccharides contained in corn and straw, and esters such as polybutylene succinate. is there. Further, starch, amylose, cellulose, cellulose ester, chitin, chitosan, gellan gum, carboxyl group-containing cellulose, carboxyl group-containing starch, polysaccharides such as pectinic acid and alginic acid are plant-derived organic substances. When polybutylene succinate is used as “a plant-derived organic substance other than polylactic acid”, it is excluded from the flexibility-imparting agent (B) of the present invention.

  In addition, polybetahydroxyalkanoate (product name: Biopol, etc., manufactured by Zeneca), which is a polymer of hydroxybutyrate and / or hydroxyvalerate synthesized by microorganisms, is not derived from plants, but uses petroleum resources. It can be used because it has the same significance as a plant-derived resin in that it is not necessary.

  Lignin is a dehydrogenated polymer of coniferyl alcohol and sinapyr alcohol contained in wood in an amount of 20 to 30%, and a modified version thereof is also a plant-derived resin. That is, thermosetting resins using plant raw materials such as lignin, hemicellulose, and cellulose can also be used.

  Among the plant-derived resins as described above, artificially synthesized biodegradable oligomers and polymers, artificially synthesized biodegradable oligomers and modified polymers, naturally synthesized biodegradable oligomers and modified polymers are intermolecular. Since the bonding strength is appropriate, the thermoplastic resin is excellent in thermoplasticity, the viscosity at the time of melting does not increase remarkably, and good molding processability is preferable. Of these, crystalline polyesters and modified polyesters are preferable, and aliphatic polyesters and modified aliphatic polyesters are more preferable. Polyamino acids and modified products of polyamino acids are preferable, and aliphatic polyamino acids and modified products of aliphatic polyamino acids are more preferable. Further, polyols and modified products of polyols are preferable, and aliphatic polyols and modified products of aliphatic polyols are more preferable.

  Petroleum-derived resins can also be mixed with plant-derived resins. Examples of petroleum-derived resins include polypropylene, polystyrene, ABS, nylon, polyethylene terephthalate, polybutylene terephthalate, polycarbonate, urea resin, melamine resin, alkyd resin, acrylic resin, unsaturated polyester resin, diallyl phthalate resin, epoxy resin, silicone Resins, cyanate resins, isocyanate resins, furan resins, ketone resins, xylene resins, thermosetting polyimides, thermosetting polyamides, styrylpyridine resins, nitrile terminated resins, addition curable quinoxalines, addition curable polyquinoxaline resins And an alloy of the thermosetting resin such as the plant-derived resin. When using a thermosetting resin, a curing agent and a curing accelerator necessary for the curing reaction can be used.

  Moreover, the thermoplastic resin composition according to the present invention may contain a char-forming agent (E). The char-forming agent (E) is not particularly limited as long as it is a compound that has excellent thermal decomposition resistance and can easily form a carbonized component (also referred to as char). As the char forming agent (E), phenols, silicone compounds, boron compounds, and the like are particularly preferable from the viewpoints of flame retardancy and fluidity.

  The phenols are not particularly limited as long as they do not volatilize or decompose at the kneading temperature or molding temperature of the resin, and phenol resins generally used as curing agents for epoxy resins are used. Available. Examples of these phenol resins include phenol novolak resin, cresol novolak resin, p-cresol novolak resin, phenol xylene aralkyl type resin, phenol biphenylene aralkyl type resin, bisphenol A type phenol resin, bisphenol F type phenol resin, bisphenol S type phenol. Resin, biphenyl isomer dihydroxy ether type phenol resin, naphthalene diol type phenol resin, phenol diphenyl ether aralkyl type resin, naphthalene-containing novolac resin, anthracene-containing novolac resin, biscresol fluorene, fluorene-containing novolac resin, bisphenol fluorene-containing novolak Resin, bisphenol F-containing novolac phenol resin, bisphenol Contained novolac type phenolic resin, phenol biphenylene triazine type resin, phenol xylylene triazine type resin, phenol triazine type resin, trisphenylol ethane type resin, tetraphenylol ethane type resin, polyphenol type resin, aromatic ester type phenol resin, cyclic Examples thereof include aliphatic ester-containing phenol resins, ether ester-type phenol resins and phenoxy resins, and furan ring-containing phenol resins. Other phenols include biphenol, xylenol, bisphenol A, bisphenol F, bisphenol S, catechol and catechol resin. Furthermore, a catechol biphenylene aralkyl resin or a catechol xylene aralkyl resin obtained by copolymerizing a catechol and an aromatic derivative can also be used. In addition, lignin and its analogs (for example, lignophenols may be used) may be used.

  However, since phenols are easily oxidized, it is generally more preferable to use in combination with a compound that is used as an antioxidant in applications where design properties are required. Alternatively, p-cresol novolac resin and biscresol fluorene are preferable because they have a relatively good flame retardancy and are difficult to have a quinone structure that causes coloration, and thus use them because they have good design properties. In addition, since the compound in which the phenolic hydroxyl group in the structure of phenols is glycidylated or ethylene oxide is not changed to a quinone structure that causes coloring, the thermoplastic resin composition of the present invention can be obtained by using these compounds. The design property of is good.

Further, the silicone compound is an organosilane containing an aromatic ring, and may be branched or linear as long as it does not volatilize or decompose at the resin kneading temperature or molding temperature, and the structure is particularly limited. Not. Among them, the silicone compound of a branched structure, preferably contains a unit (T unit) represented by the formula RSiO _1.5. Furthermore, it may also contain units (Q units) represented by the formula SiO _2.0. Further, the branched structure of the silicone compound is composed of a unit represented by the formula RSiO _1.5 (T unit), a unit represented by the formula R ₂ SiO _1.0 (D unit), and a unit represented by the formula R ₃ SiO _0.5 (M unit). It is particularly preferable in terms of improving flame retardancy. Here, R represents a monovalent aliphatic hydrocarbon group or an aromatic hydrocarbon group, and at least one of R is a group containing an aromatic ring. R may be all different or all R may be the same. The subscript numbers “2” and “3” of R indicate the number of substitutions. If it is a thing of such a structure, a flame retardance can be improved further. Further, the silicone compound a linear structure, units (D units) of the formula R ₂ SiO _1.0, refers to those composed of units of the formula R ₃ SiO _0.5 (M units). Furthermore, such a silicone compound is effective in improving impact resistance in addition to improving flame retardancy and fluidity.

  Moreover, when the weight ratio of said char formation agent (E) to the total amount of the thermoplastic resin composition of this invention is set to Y, said Y is the range of 0.5 mass% or more and 20 mass% or less. And even if it reduces the usage-amount of an inorganic type flame retardant (C), since it is excellent in not only a flame retardance and fluidity | liquidity but heat resistance, it is more preferable. When the weight ratio Y of the char forming agent (E) is less than 0.5% by mass, the effect of improving flame retardancy and fluidity may be insufficient. On the other hand, when the weight ratio Y of the char forming agent (E) exceeds 20% by mass, the heat resistance (in particular, the deflection temperature under load <HDT>) may be lowered.

  The thermoplastic resin composition of the present invention comprising the above char-forming agent (E), high molecular weight polylactic acid (A), flexibility imparting agent (B), inorganic flame retardant (C) and plasticizer (D). It has been found that, when used in combination with the above, there is not only an improvement in fluidity but also an excellent improvement in flame retardancy. Although the cause of this effect is not necessarily clear, especially when a metal hydrate is used as the inorganic flame retardant (C), the carbide formed when the resin composition containing the char-forming agent (E) is ignited. (Including melted resin) is combined with the above metal hydrate (including the generated metal oxide) to form a specific composite layer (carbide, molten resin, metal hydrate and this oxide) This composite layer expands by containing moisture generated by the thermal decomposition of the metal hydrate and decomposition gas (including flammable gas) of the resin component in the resin composition. As a result of the formation of a heat insulating layer that can effectively block the heat of ignition, flame retardancy is considered to have improved. Further, it is assumed that this heat insulating layer also has an effect of capturing the decomposition gas of the resin and suppressing the decomposition gas from diffusing to the outside and spreading the resin.

  Furthermore, it is preferable to add a crystal nucleating agent (F) to the thermoplastic resin composition of the present invention. As the crystal nucleating agent (F), an inorganic crystal nucleating agent or an organic crystal nucleating agent can be used. Inorganic crystal nucleating agents include clay minerals, calcium carbonate, boron nitride, synthetic silicic acid, silicate, silica, carbon black, zinc white, basic magnesium carbonate, quartz powder, glass fiber, glass powder, diatomaceous earth, Examples thereof include dolomite powder, titanium oxide, zinc oxide, antimony oxide, barium sulfate, calcium sulfate, alumina, calcium silicate, and boron nitride. Here, the clay mineral refers to a hydrous silicate produced as a main component of clay. Specific examples of clay minerals include allophane, hysinger gel, phyllosilicate, pyrophyllite, talc, unmo (also called mica) group, montmorillonite group, vermiculite, ryokdeite group, kaolin group, inosilicate, Palygorskite group.

As an organic crystal nucleating agent,
(1) Organic carboxylic acids, for example, octylic acid, toluic acid, heptanoic acid, pelargonic acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, serotic acid, montanic acid, melicic acid, benzoic acid, p -Tert-butylbenzoic acid, terephthalic acid, terephthalic acid monomethyl ester, isophthalic acid, isophthalic acid monomethyl ester, rosin acid, 12-hydroxystearic acid, cholic acid, etc.
(2) Alkali (earth) metal salt of organic carboxylic acid, for example, alkali (earth) metal salt of organic carboxylic acid,
(3) High molecular organic compounds having a metal salt of carboxyl group, for example, carboxyl group-containing polyethylene obtained by oxidation of polyethylene, carboxyl group-containing polypropylene obtained by oxidation of polypropylene, olefins such as ethylene, propylene, butene-1 Copolymer of acrylic acid and methacrylic acid, copolymer of styrene and acrylic acid or methacrylic acid, copolymer of olefins and maleic anhydride, copolymer of styrene and maleic anhydride, etc. Metal salts, etc.
(4) Amide compounds, for example, oleic acid amide, stearic acid amide, erucic acid amide, behenic acid amide, N-oleyl palmitoamide, N-stearyl erucic acid amide, N, N′-methylenebis (stearylamide) , Methylol stearylamide, ethylene bisbehenamide, ethylenebislaurate amide, hexamethylene bisoleic acid amide, hexamethylene bis stearamide, butylene bis stearamide, N, N′-dioleyl sebacic acid amide, N , N′-dioleyl adipic acid amide, N, N′-distearyl adipic acid amide, N, N′-distearyl sebacic acid amide, m-xylylene bis stearic acid amide, N, N′-distearyl isophthalic acid Amide, N, N'-distearyl terephthalic acid N-oleyl oleic acid amide, N-stearyl oleic acid amide, N-stearyl erucic acid amide, N-oleyl stearic acid amide, N-stearyl stearic acid amide, N-butyl-N′-stearyl urea, N-propyl -N'-stearyl acid urea, N-allyl-N'-stearyl urea, N-phenyl-N'-stearyl urea, N-stearyl-N'-stearyl urea, dimethylol oil amide, dimethyl lauric acid amide, dimethyl stearic acid Amides, etc., N-hydroxyethyl-ricinoleylamide, N-hydroxyethyl-12-hydroxystearylamide, N, N′-ethylene-bis-oleylamide, N, N′-ethylene-bis-ricinoleylamide, N, N'-ethylene-bis-octadecadienylamide, N, N'-ethylene- S-12-hydroxystearylamide, N, N'-ethylene-bis-stearylamide, N, N'-hexamethylene-bis-ricinoleylamide, N, N'-hexamethylene-bis-12-hydroxystearylamide N, N′-xylylene-bis-12-hydroxystearylamide, N, N′-cyclohexanebis (stearoamide), N-lauroyl-L-glutamic acid-α, γ-n-butyramide, trimesic acid tris (t-butyramide) ), Trimesic acid tris (2-methylcyclohexylamide), trimesic acid tribenzylamide, 1,4-cyclohexanedicarboxylic acid dianilide, 1,4-cyclohexanedicarboxylic acid bis (p-toluidineamide), 2,6-naphthalenedicarboxylic acid Dicyclohexylamide, adipic acid di Nilide, Adipic acid bis (4-cyclohexylanilide), Butanetetracarboxylic acid tetradicyclohexylamide, Butanetetracarboxylic acid tetra (2-methylcyclohexylamide), Terephthalic acid dibenzylamide, N, N′-Dibenzoyl-1,4- Diaminocyclohexane, N, N′-dicyclohexanecarbonyl-1,4-diaminocyclohexane, N, N′-dicyclohexanecarbonyl-1,5-diaminonaphthalene, N, N′-dibenzoyl-p-phenylenediamine, N, N '-Dibenzoyl-1,4-diaminobutane, etc.

(5) High molecular organic compound, for example, 3,3-dimethylbutene-1,3-methylbutene-1,3-methylpentene-1,3-methylhexene-1,3,5,5-trimethylhexene-1 3 or more branched α-olefins having 5 or more carbon atoms such as, and polymers of vinylcycloalkanes such as vinylcyclopentane, vinylcyclohexane and vinylnorbornane, polyalkylene glycols such as polyethylene glycol and polypropylene glycol, polyglycolic acid, cellulose, Cellulose ester, cellulose ether, polyester, polycarbonate, etc.
(6) Organic compounds such as phosphoric acid or phosphorous acid or metal salts thereof, for example, diphenyl phosphate, diphenyl phosphite, sodium bis (4-tert-butylphenyl) phosphate, methylene phosphate (2,4 -Tert-butylphenyl) sodium, etc.
(7) sorbitol derivatives, for example, bis (p-methylbenzylidene) sorbitol, bis (p-ethylbenzylidene) sorbitol,
(8) Cholesterol derivatives, for example, cholesteryl stearate, cholesteryloxycystearamide,
(9) Examples thereof include thioglycolic anhydride, paratoluenesulfonic acid, paratoluenesulfonic acid amide and metal salts thereof.

  In addition to the above, zinc phenylphosphonate, phenylphosphonate metal salts such as calcium phenylphosphonate and magnesium phenylphosphonate, melamine compounds such as melamine cyanurate and melamine polyphosphate, and bis (benzhydrazinocarbonyl) octanoate Can be used.

  Some of these organic crystal nucleating agents exhibit the effect as a plasticizer (D), but when used as a crystal nucleating agent (F), they are excluded from the plasticizer (D). To do.

  Regarding organic crystal nucleating agents, organic crystal nucleating agents that act as crystal nuclei are dissolved or dissolved or finely dispersed in the resin in a high-temperature molten state in injection molding, etc., and precipitated or phase separated in the molding cooling stage in the mold. Is preferably used. Further, the inorganic crystal nucleating agent functions efficiently as a crystal nucleus when fine inorganic substances are highly dispersed in the resin. The surface of the inorganic crystal nucleating agent is preferably subjected to a compatibilizing treatment (a coating treatment using a resin or compound having a compatibilizing action, or a surface treatment with an ion exchange treatment or a coupling agent). The inorganic crystal nucleating agent whose surface has been compatibilized has an enhanced interaction with the resin and improved dispersibility, and can prevent aggregation of the nucleating agent.

  A master batch in which the crystal nucleating agent (F) is previously dissolved or dispersed in a plant-derived resin such as polylactic acid may be used. In addition, when using a crystal nucleating agent (F), when the weight ratio which occupies for the total amount of the thermoplastic resin composition of this invention is set to Z, Z is more than 0.05 mass% and 20 mass% or less. It is particularly preferable because the crystallization speed of a crystalline resin such as polylactic acid can be increased to improve the productivity and the impact resistance is good. That is, when the weight ratio Z of the crystal nucleating agent (F) is more than 0.05% by mass, crystallization proceeds rapidly and the production rate is improved. In addition, when the weight ratio Z of the crystal nucleating agent (F) is 20% by mass or less, particularly when an inorganic crystal nucleating agent is used, the growth of cracks based on the inorganic crystal nucleating agent can be suppressed. The impact resistance of the thermoplastic resin composition of the present invention is improved.

  An anti-drip agent (G) may be used in combination with the thermoplastic resin composition of the present invention. Examples of the anti-drip agent (G) include organic fibers such as polytetrafluoroethylene (PTFE) and acrylic modified PTFE. In particular, when these anti-drip agents are used, it is preferable that the weight ratio in the total amount of the thermoplastic resin composition of the present invention is 1% by mass or less. When the weight ratio of these anti-drip agents is 1% by mass or less, the granulation property is good when producing pellets.

  Furthermore, when the plant-derived resin has an ester bond in the structure, it is generally easy to hydrolyze, so that a known hydrolysis inhibitor (H) is used in combination for the purpose of improving hydrolysis resistance. Also good. As said hydrolysis inhibitor, the compound which has the reactivity with the active hydrogen in plant origin resin can be used. Here, as active hydrogen, hydrogen in a carboxyl group, a hydroxyl group, an amino group, an amide group or the like in a plant-derived resin can be mentioned. As compounds having reactivity with these active hydrogens, carbodiimide compounds, isocyanate compounds and oxazoline compounds are applicable. Although not particularly limited to these, aromatic polycarbodiimide is particularly preferable from the viewpoint of achieving both hydrolysis resistance and flame retardancy.

  Moreover, high-strength fiber (I) can be used as a technique for improving heat resistance (particularly heat distortion temperature) and impact strength. High-strength fibers (I) include polyamide fibers such as aramid fibers and nylon fibers, polyester fibers such as polyarylate fibers and polyethylene terephthalate fibers, ultrahigh-strength polyethylene fibers, polypropylene fibers, carbon fibers, metal fibers, glass fibers, etc. And organic and inorganic substances having a high aspect ratio.

  Aramid fiber and polyarylate fiber are aromatic compounds, have high heat resistance and high strength compared to other fibers, and because they are light in color, they do not impair the design properties even when added to the resin, and the specific gravity is also It is particularly desirable because of its low.

  The shape of the high-strength fiber (I) is not a circular fiber cross section, but a polygonal shape, an indeterminate shape or an uneven shape, and a high aspect ratio or a small fiber diameter is used as a resin. The bonding area of the is increased. As a result, the debonding effect between the fibers and the matrix is increased, and the impact mitigating effect due to the fiber drawing is also increased, so that the impact strength is improved. Also, a fiber with irregularities on the surface of the fiber, a fiber with a kind of wedge shape in which both ends of the fiber are thicker than the center, a part of the fiber with a neck, or a non-linear shape By using a fiber having a crimped shape, the friction when the fiber is pulled out is increased, and the impact resistance is improved.

  In addition, the high-strength fiber (I) can be subjected to a surface treatment as necessary in order to increase the affinity with the resin serving as the base material or the entanglement between the fibers. As the surface treatment method, treatment with a coupling agent such as silane or titanate, ozone or plasma treatment, or treatment with an alkyl phosphate type surfactant is effective. However, it is not particularly limited to these, and a processing method that can be normally used for surface modification of the filler is possible.

  When the average fiber length of the high-strength fiber (I) is in the range of 1 mm to 10 mm, it is particularly effective for improving impact resistance. When the average fiber length of the high-strength fiber (I) is 1 mm or more, the energy absorption effect by pulling out the fiber is high, and sufficient impact resistance is obtained. In addition, when the average fiber length of the high-strength fiber (I) is 10 mm or less, it is preferable because the moldability is good. Moreover, when using the high strength fiber (I), if the weight ratio of the high strength fiber (I) in the total amount of the thermoplastic resin composition of the present invention is 10% by mass or less, the impact resistance is increased. And formability is particularly excellent.

  In addition to the high-strength fibers (I), plant fibers such as kenaf and flax can also be used. In the present invention, plant fiber refers to a fiber derived from a plant, and specific examples include fibers obtained from wood, kenaf, bamboo, hemp and the like. These fibers preferably have an average fiber length of 10 mm or less. In addition, pulp obtained by delignifying or depectining these plant fibers is particularly preferable because it has little deterioration such as decomposition or discoloration due to heat. Kenaf and bamboo have high photosynthesis and fast growth, and can absorb large amounts of carbon dioxide, making them an excellent means of simultaneously solving the global warming and deforestation problems caused by carbon dioxide. Further, among the high-strength fibers (I) and the above-described plant fibers, the organic fibers act as a crystal nucleating agent for the resin, so that the heat resistance of the thermoplastic resin composition of the present invention (particularly the deflection temperature under load < HDT>)).

  In addition, the thermoplastic resin composition of the present invention may include a reinforcing material, a colorant (such as titanium oxide), a stabilizer (such as a radical scavenger and an antioxidant), an antibacterial agent, and an antifungal material as necessary. Can be used together. As the reinforcing material, silica, alumina, sand, clay, slag and the like can be used. Moreover, as an antibacterial agent, silver ion, copper ion, zeolite containing these, etc. can be used.

  The thermoplastic resin composition of the present invention as described above is not particularly limited, and by a known injection molding method, injection / compression molding, compression molding method, film molding method, blow molding method, foam molding method, or the like, It can be processed into molded products for electrical and electronic equipment such as housings for electrical appliances, building materials, automobile parts, daily necessities, medical uses, and agricultural uses.

  There are no particular restrictions on the method of mixing the various blending components of the thermoplastic resin composition in the present invention, and mixing and extrusion using known mixers such as tumblers, ribbon blenders, single-screw or twin-screw kneaders, rolls, etc. For example, melt-mixing may be used.

  About the temperature at the time of these melt mixing and shaping | molding, it is possible to set the range which is more than the melting temperature of resin used as a base material, and a vegetable fiber and plant origin resin do not thermally deteriorate.

  Hereinafter, the present invention will be described in more detail with specific examples.

  First, the raw materials used in the present invention examples and comparative examples will be described. High molecular weight polylactic acid (A), low molecular weight polylactic acid (a), flexibility imparting agent (B), inorganic flame retardant (C), plasticizer (D), char forming agent (shown in Table 1 below) E), crystal nucleating agent (F), anti-drip agent (G) and hydrolysis inhibitor (H) were used.

* 1 Melt flow rate (MFR) is specified according to ISO 1133 using an extrusion plastometer when the temperature of the resin composition is 190 ° C. and a load of 2.16 kg is applied for 10 minutes. The mass (g) of the resin composition flowing out from a nozzle (orifice) having dimensions was measured and calculated (the unit is g / 10 minutes).
* 2 Table 1 shows the total amount of Na ₂ O as the total amount of alkali metal substances in aluminum hydroxide.

  Next, evaluation methods for bending characteristics and flame retardancy in the examples of the present invention and comparative examples will be described.

(1) Kneading of resin composition The materials for the thermoplastic resin compositions shown in the examples (sometimes referred to as examples) and comparative examples are set so that the temperature of the composition is about 180 ° C. The mixture was melted and mixed in a kneader (using a biaxial type) to produce pellets for injection molding.

(2) Preparation of sample for evaluation 1 (molding with low temperature mold)
Using pellets dried at 100 ° C. for 7 hours or more, setting the mold temperature to 25 ° C., and using an injection molding machine, two types of length 13 cm, width 13 mm, plate thickness 1.6 mm or 3.2 mm A molded body was created. Next, these molded bodies were heated at 100 ° C. for 4 hours to crystallize the resin component, and then used as various samples for evaluation. Incidentally, the temperature of the barrel of the injection molding machine was set to 190 ° C.

(3) Preparation of sample for evaluation 2 (molding with high temperature mold)
Using pellets dried for 7 hours or more at 100 ° C., the mold surface temperature is set to 110 ° C., and an injection molding machine is used with a length of 13 cm, a width of 13 mm, and a plate thickness of 1.6 mm or 3.2 mm. Various types of molded bodies were prepared and used as various samples for evaluation. Incidentally, the temperature of the barrel of the injection molding machine was set to 190 ° C., and the sample holding time in the mold was 180 seconds.

(4) Evaluation of bending characteristics For the molded body having a thickness of 3.2 mm obtained by the method of (2) or (3) above, the distance between fulcrums was set to 5 cm, and the indentation speed was set to 1.6 mm / min. A three-point bending test in accordance with JIS K7171 was performed to determine bending rupture stress (MPa), bending elastic modulus (GPa), and bending rupture strain (%).

(5) Evaluation of flame retardancy For samples (plate thickness 1.6 mm) molded by the method of (2) or (3) above, UL (Underwriters
Laboratories Inc.) 94 standard vertical flame test was conducted to evaluate flame retardancy. The evaluation criteria for flame retardancy are as shown in Table 2.

  In addition, when taking combustion forms other than said classification, it classified as NOT. By the way, if the flame retardancy is arranged in order from good to bad, V-0, V-1, and (V-2 or NOT) are obtained.

(Example 1)
50% by mass of polylactic acid (A-1) having an MFR of 3 as high molecular weight polylactic acid (A), 5% by mass of (B-1) shown in Table 1 as a flexibility-imparting agent (B), inorganic type A mixture containing 45% by mass of aluminum hydroxide (C-1) shown in Table 1 as the flame retardant (C) was melt-mixed with a kneader to prepare pellets of the resin composition. The temperature of the kneader was set so that the temperature of the resin composition in the kneader was about 180 ° C.

  Next, using the obtained pellet, an evaluation sample was prepared according to the method of (2) Preparation of evaluation sample 1 (molding with a low-temperature mold).

(Example 2-11), (Comparative Example 1-7)
Various evaluation samples were prepared in the same manner as in Example 1 except that the resin compositions having the formulations shown in Tables 3 to 6 were used. For the resin composition having the composition shown in Table 7, an evaluation sample was prepared according to the method of (3) Preparation of evaluation sample 2 (molding with a high-temperature mold). The evaluation results are shown in Tables 3 to 6.

  Based on the results in Table 5, the relationship between MFR and bending fracture strain is shown in FIG.

  From the results shown in Tables 3 to 8 above, it is clear that the thermoplastic resin composition of the present invention has higher bending fracture strain and superior toughness than the resin compositions of the comparative examples related to the prior art. is there. In particular, it can be seen that when three components of high molecular weight polylactic acid (A), flexibility-imparting agent (B) and plasticizer (D) are contained simultaneously, extremely high bending fracture strain is exhibited.

  As is clear from the comparison between Example 1 of the present invention shown in Table 3 and Comparative Examples 1 to 3, by using the high molecular weight polylactic acid (A) in combination with the flexibility imparting agent (B), the breaking strain. Is improved, and a thermoplastic resin composition having good toughness is obtained.

  Further, as is clear from the comparison between Example 2 of the present invention and Comparative Example 4 shown in Table 4 and the comparison between Example 3 and Comparative Example 5, high molecular weight polylactic acid (A), flexibility imparting agent (B) And the plasticizer (D) are contained at the same time, a thermoplastic resin composition having a particularly improved toughness and excellent toughness can be obtained.

  In addition, the present invention examples 2, 5, and 6 shown in Table 5 were compared with Comparative Example 4 and, as is clear from FIG. 1, high molecular weight polylactic acid (A) having an MFR of less than 15 was used. In this case, a thermoplastic resin composition having a particularly improved fracture strain and excellent toughness can be obtained.

  In addition, as is clear from the comparison between Example 4 of the present invention shown in Table 6 and Example 7 and Comparative Example 6, the combined use of the high molecular weight polylactic acid (A) and the flexibility-imparting agent (B), By using the plasticizer (D), a thermoplastic resin composition having a particularly improved fracture strain and excellent toughness can be obtained.

  Further, as is clear from the comparison between Examples 8 to 16 of the present invention shown in Tables 7 to 8 and Comparative Example 7, the combined use of the high molecular weight polylactic acid (A) and the flexibility-imparting agent (B), By using the plasticizer (D), a thermoplastic resin composition excellent in toughness with a specific improvement in breaking strain can be obtained.

  The present invention has been described with reference to the embodiments. However, the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

  The thermoplastic resin composition of the present invention is applied to electrical / electronic equipment applications, building materials applications, automobile parts applications, daily necessities applications, medical applications, agriculture, etc. by methods such as injection molding, film molding, blow molding, and foam molding. It is processed into molded products for uses, toys, and entertainment.

  This application claims the priority on the basis of Japanese application Japanese Patent Application No. 2006-276679 for which it applied on October 10, 2006, and takes in those the indications of all here.

Claims (7)

A thermoplastic resin composition comprising at least a high molecular weight polylactic acid (A), a flexibility imparting agent (B) , an inorganic flame retardant (C), and a plasticizer (D) ,
The melt flow rate at 190 ° C. of the high molecular weight polylactic acid (A) is less than 15,
The flexibility imparting agent (B) contains a lactic acid unit in the structure,
The thermoplastic resin composition, wherein the inorganic flame retardant (C) is a metal hydroxide having an alkali metal content of 0.2% by mass or less. The thermoplastic resin composition according to claim 1, comprising a char-forming agent (E). The thermoplastic resin composition according to claim 1 or 2 , comprising an anti-drip agent (G). The thermoplastic resin composition according to any one of claims 1 to 3 , comprising a hydrolysis inhibitor (H). The thermoplastic resin composition according to claim 4 , wherein the hydrolysis inhibitor (H) is an aromatic carbodiimide compound. The thermoplastic resin composition according to any one of claims 1 to 5 , comprising a crystal nucleating agent (F). The thermoplastic resin composition according to claim 6 , wherein the crystal nucleating agent (F) is a compound having an amide bond.

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