JP5221587B2 - Flame retardant polylactic acid resin composition - Google Patents

Description

  The present invention relates to a flame retardant polylactic acid resin composition containing a polylactic acid resin. From this resin composition, a molded product excellent in flame retardancy, heat resistance and impact resistance can be obtained.

  From the viewpoint of so-called “carbon neutral”, resins made from plant-derived materials and materials obtained from natural materials are attracting attention because they can reduce carbon dioxide emissions. As a representative material, a polylactic acid resin that can be melt-molded is particularly attracting attention. However, polylactic acid resin has low heat resistance and impact resistance, and it is difficult to obtain a practical molded product by itself, and improvement thereof is desired.

  Moreover, since polylactic acid resin itself is easily combusted, it cannot be used for members that require flame retardancy, such as electrical and electronic applications.

  Therefore, in order to improve the impact resistance and flame retardancy of the polylactic acid resin composition, Patent Document 1 proposes a technique in which an aromatic polycarbonate resin is mixed and used. However, although the composition obtained by this method has a V-0 level due to the flame retardancy of UL94, improvement in impact resistance is necessary.

  Patent Document 2 discloses a resin composition comprising a polylactic acid resin containing a flame retardant and a resin other than polylactic acid. Even in this resin composition, flame retardancy and impact resistance are improved, but there remains a problem in improving heat resistance. Furthermore, Patent Document 3 discloses a resin composition in which a compatibilizing agent is applied to a polylactic acid resin and a polycarbonate resin, but there is still a problem in impact resistance.

JP 2008-88226 A JP 2004-190026 JP JP 2007-56247 A

  An object of this invention is to provide the flame-retardant polylactic acid resin composition containing the polylactic acid resin excellent in the flame retardance, heat resistance, and impact resistance.

  The present inventors achieve this object by blending a polylactic acid resin, an aromatic polycarbonate resin, a styrene-butadiene block copolymer, a styrene or acrylic resin having a glycidyl methacrylate unit, and a phosphorus flame retardant. I found that it was possible.

  The present invention is based on (A) 5 to 50 parts by weight of a polylactic acid resin, (B) 50 to 95 parts by weight of an aromatic polycarbonate resin, and 100 parts by weight of (A) and (B). 1 to 30 parts by weight of a butadiene block copolymer, (D) 0.1 to 10 parts by weight of a resin comprising any one of a styrene resin or an acrylic resin having a glycidyl methacrylate unit, or a combination thereof, and (E) It is a flame retardant polylactic acid resin composition comprising 1 to 50 parts by weight of a phosphorus flame retardant.

  Advantageously, (A) 5 to 50% by weight of polylactic acid resin, (B) 50 to 95% by weight of aromatic polycarbonate resin, and (C) for a total of 100 parts by weight of (A) and (B) 1 to 30 parts by weight of a styrene-butadiene block copolymer, (D) 0.1 to 10 parts by weight of a resin comprising any one of a styrene resin or an acrylic resin having a glycidyl methacrylate unit, or a combination thereof; E) A flame retardant polylactic acid resin composition comprising 1 to 50 parts by weight of a phosphorus flame retardant.

  Here, (C) the styrene-butadiene block copolymer has a radial block structure, the styrene content is 60 to 90% by weight, (F) the fluorine-based resin, (A) and (B) 0.01 to 2 parts by weight based on a total of 100 parts by weight, or (G) containing an inorganic filler, and the content is 100 parts by weight in total of (A) and (B) When satisfying any one or more of 0.5 to 50 parts by weight, a preferable flame retardant polylactic acid resin composition is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the flame-retardant polylactic acid resin composition containing the polylactic acid resin excellent in the flame retardance, heat resistance, and impact resistance can be obtained.

  Hereinafter, the flame retardant polylactic acid resin composition of the present invention will be described in detail. The flame-retardant polylactic acid resin composition of the present invention contains (A) component, (B) component, (C) component, (D) component, and (E) component as essential components. Here, the component (A) is a polylactic acid resin, the component (B) is an aromatic polycarbonate resin, the component (C) is a styrene-butadiene block copolymer, and the component (D) is a styrene or acrylic resin having a glycidyl methacrylate unit. Resin and component (E) are phosphorus flame retardants. The components (A) to (E) are also referred to as (A), (B), (C), (D), and (E), respectively.

  The flame-retardant polylactic acid resin composition of the present invention contains components (A) to (E) as essential components. Furthermore, it is preferable to include any one or more optional components such as the component (F) and the component (G) described later depending on the application. Hereinafter, each component will be described.

  The polylactic acid resin of component (A) used in the present invention is a polymer or copolymer having L-lactic acid and / or D-lactic acid as a main component. In the present invention, from the viewpoint of heat resistance and impact resistance of the composition, it is preferable to contain 90% or more of either unit of L-lactic acid or D-lactic acid, and either L-lactic acid or D-lactic acid More preferably, the unit contains 95% or more.

  As a method for producing the polylactic acid resin, a known polymerization method can be used. Examples thereof include a method of directly dehydrating polycondensation from lactic acid and a ring-opening polymerization method via lactide.

  The molecular weight of the polylactic acid resin is not particularly limited as long as it can be substantially molded, but the weight average molecular weight Mw is usually 10,000 or more, preferably 50,000 or more, more preferably 100,000 to 500,000.

  The melt flow rate (ASTM D1238) at 190 ° C.-2.16 kg of the polylactic acid resin is usually 0.1 to 30 g / 10 minutes, preferably 0.2 to 20 g / 10 minutes, optimally 0.5 to 10 g / 10 minutes. When the melt flow rate exceeds 30 g / 10 min, the melt viscosity is too low, and the impact resistance and heat resistance of the molded product may be inferior.

  Next, the aromatic polycarbonate resin as the component (B) will be described. The aromatic polycarbonate resin is not particularly limited, and can usually be produced by reacting a dihydric phenol and phosgene or diethyl carbonate by a solution method or a melt method in the presence or absence of a molecular weight regulator. I can do it.

  Here, various dihydric phenols are exemplified, and 2,2-bis (4-hydroxyphenyl) propane (common name: bisphenol A) is particularly preferable. Examples of dihydric phenols other than bisphenol A include bis (4-hydroxyphenyl) alkanes other than bisphenol A, 1,1-bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 4 , 4-dihydroxydiphenyl, bis (4-hydroxyphenyl) cycloalkane, bis (4-hydroxyphenyl) oxide, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) sulfone, bis (4-hydroxyphenyl) Examples thereof include sulfoxide, bis (4-hydroxyphenyl) ether, bis (4-hydroxyphenyl) ketone and the like. In addition, examples of the dihydric phenol include hydroquinone. These dihydric phenols may be used alone or in combination of two or more.

  When a molecular weight regulator is used in the production of the polycarbonate resin, the molecular weight regulator to be used may be usually used for polymerization of polycarbonate, and various types can be used. Specific examples include monohydric phenols such as phenol, p-cresol, p-tert-butylphenol, p-tert-octylphenol, p-cumylphenol, and nonylphenol.

  In the production of the polycarbonate resin, a branching agent (usually a polyfunctional aromatic compound) may be used in combination with a dihydric phenol. Examples of branching agents include trimellitic anhydride, trimellitic acid, 4-chloroformylphthalic anhydride, pyromellitic acid, phloroglucin, gallic acid, propyl gallate, melittic acid, trimesic acid, and benzophenonetetracarboxylic acid. It can be illustrated. These polyfunctional aromatic compounds have at least three functional groups such as carboxy, hydroxy, carboxylic anhydride, haloformyl, and combinations thereof.

  The molecular weight of the aromatic polycarbonate resin used in the present invention is not limited as long as it does not impair the effects of the present invention. From the viewpoint of mechanical strength and moldability, the polystyrene-equivalent weight average molecular weight is 5,000 to 100,000, preferably 7,000 to 70,000, more preferably 10,000 to 50,000. Can be suitably used. Further, two or more aromatic polycarbonate resins having different molecular weights may be used in combination.

  The blending amount of (A) polylactic acid resin and (B) aromatic polycarbonate resin in the present invention is preferably (A) / (B) (weight ratio) = 5-50 / 95-50, preferably 15-50. More preferably, it is / 85-50. By using this blending amount, the carbon dioxide emission reduction effect and the modification effect of the polylactic acid resin described above can be obtained.

  Next, the styrene-butadiene block copolymer used as the component (C) will be described. As the styrene-butadiene block copolymer, those having a polymer segment having a glass transition temperature of 20 ° C. or lower, preferably 0 ° C. or lower are preferable from the viewpoint of improving impact resistance. Such a styrene-butadiene block copolymer is obtained from a polymer block A mainly composed of styrene and a polymer block B mainly composed of butadiene, as shown in the following formula.

1) AB (diblock body),
2) A-B-A (triblock body),
3)-[AB-] n- (multi-block body),
4)-([AB-] n) _m -X (radial block)
In the structural formula, A is a polymer block mainly composed of styrene, B is a polymer block mainly composed of butadiene, X is a central atom or central atomic group of a polyfunctional coupling agent, and n is an integer of a continuous unit. , M represents the number of blocks connected to X.

  The styrene-butadiene block copolymer can be produced by an anion living polymerization method or the like. The production conditions may be any conventionally known conditions for any of 1) a diblock body, 2) a triblock body, 3) a multiblock body, and 4) a radial block body. This styrene-butadiene block copolymer contains 60 to 90% by weight, preferably 65 to 85% by weight, more preferably 70 to 80% by weight of styrene units. When the styrene content is less than 60% by weight, the heat resistance is deteriorated, and when it exceeds 90% by weight, the impact resistance is deteriorated.

  The molecular structure of the styrene-butadiene block copolymer may be any of 1) diblock body, 2) triblock body, 3) multiblock body, 4) radial block body, or any combination thereof. In order to develop impact resistance, it is necessary for the butadiene phase to form a continuous phase, and in the composition, it is most preferable to be a 4) radial block body that can easily form its structure.

  The number average molecular weight in terms of polystyrene of the styrene-butadiene block copolymer having the above structure is not particularly limited, but the number average molecular weight is 5,000 to 1,000,000, preferably 10,000 to 500,000, more preferably 30,000 to 300,000. Range.

  The blending amount of the styrene-butadiene block copolymer of component (C) in the present invention is 1 to 30 parts by weight, preferably 5 to 20 parts by weight based on 100 parts by weight of the total of (A) and (B). Part. If the amount of component (C) is less than 1 part by weight, a sufficient impact resistance improving effect cannot be obtained, and if it exceeds 30 parts by weight, the heat resistance deteriorates, which is not preferable.

  Next, the component (D) will be described. The styrene resin or acrylic resin having a glycidyl methacrylate unit is a styrene resin or a polymer compound obtained by copolymerizing an acrylic resin and glycidyl methacrylate. By blending the component (D), the compatibility of the composition is improved.

  The above-mentioned styrene resin having a glycidyl methacrylate unit is a homopolymer of a styrene monomer such as styrene, methylstyrene, α-methylstyrene, or a copolymer of these and other unsaturated monomers with glycidyl methacrylate. A polymer compound. Here, as other unsaturated monomer, unsaturated organic acid such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, methyl acrylate, ethyl acrylate, methyl methacrylate, maleic anhydride, or a derivative thereof, or Vinyl acetate such as vinyl acetate and vinyl butyrate, vinyl silane such as vinyl trimethylmethoxysilane and methacryloyloxypropyltrimethoxysilane, or non-conjugated dienes such as dicyclopentadiene and 4-ethylidene-2-norbornene can be used. In the case of a copolymer, it is not limited to two types, and may be a plurality of types.

  The acrylic resin having the glycidyl methacrylate unit is a homopolymer of acrylic monomers such as acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, methyl methacrylate, or other unsaturated monomers. Is a polymer compound obtained by copolymerizing glycidyl methacrylate. Examples of other unsaturated monomers include styrene monomers such as styrene, methylstyrene, and α-methylstyrene, vinyl esters such as vinyl acetate and vinyl butyrate, vinyltrimethylmethoxysilane, and methacryloyloxypropyltrimethoxysilane. Non-conjugated dienes such as vinyl silane, or dicyclopentadiene, 4-ethylidene-2-norbornene, etc. can be used, and in the case of a copolymer, not only two types but also a plurality of types Also good.

  (D) It is preferable that the epoxy equivalent derived from the glycidyl methacrylate of a component is 100-4000 (g / eq), More preferably, it is 100-2000 (g / eq). If it is less than 100 (g / eq), the crosslink density of the composition is excessively increased, so that brittleness is deteriorated, and if it exceeds 4000 (g / eq), a sufficient compatibility improving effect cannot be obtained.

  (D) The compounding quantity of a component is 0.1-10 weight part with respect to a total of 100 weight part of (A) and (B), Preferably it is 0.5-5 weight part. If the amount is less than 0.1 parts by weight, the compatibility is not improved. If the amount exceeds 10 parts by weight, the brittleness deteriorates, which is not preferable.

  The phosphorus-based flame retardant used as the component (E) forms a heat-resistant film by forming a polyphosphoric acid compound when the blended resin is exposed to a high temperature, and is also flame retardant by a mechanism of promoting carbonization by a solid acid. It is thought to show an effect. As such phosphorus flame retardants, known ones can be used without limitation. Specific examples thereof include phosphates such as calcium phosphate and titanium phosphate; phosphate esters such as tributyl phosphate and triphenyl phosphate; Polyphosphates; polyphosphates such as calcium polyphosphate; polyphosphates such as poly (diphenyl phosphate); condensed phosphates such as bisphenol A bisdiphenyl phosphate, 1,3-phenylene bisdixylenyl phosphate; A phosphine oxide such as triphenylphosphine oxide; a phosphorane such as phenylphosphorane; a phosphonic acid such as diphenylphosphonic acid; a phosphine sulfide. Among these, the condensed phosphate ester can be suitably used because it has a large flame retardant effect.

  (E) The compounding quantity of a component is 1-50 weight part with respect to a total of 100 weight part of (A) and (B), Preferably it is 3-30 weight part. If the blending amount is less than 1 part by weight, a sufficient flame retardant effect cannot be obtained, and if it exceeds 50 parts by weight, the moldability and mechanical properties are deteriorated, which is not preferable.

  If necessary, the flame retardant polylactic acid resin composition of the present invention can contain a component (F), a component (G), and other components.

Component (F), which is a fluororesin, imparts the effect of preventing melt dripping during resin combustion, and is preferably finely dispersed in a fibril form in the resin. The preferred fluororesin used in the present invention has a high molecular weight having an average molecular weight of 10,000 or more, a glass transition temperature of −30 ° C. or more, preferably 100 ° C. or more, 65 to 76% by weight, preferably 70 to 76%. It has a fluorine content of wt%, an average particle size of 0.05 to 10 μm, preferably 0.1 to 5 μm and a density of 1.2 to 2.3 g / cm ³ .

  Specific examples of the component (F) include polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene / hexafluoropropylene copolymer and tetrafluoroethylene / ethylene copolymer, and dispersions in which these are dispersed in water. These may be used alone or in combination.

  Component (F) is preferably blended in an amount of 0.01 to 2 parts by weight, preferably 0.02 to 1.5 parts by weight, more preferably 100 parts by weight in total of (A) and (B). 0.03 to 1.0 part by weight. If it is less than 0.01 part by weight, the effect of improving flame retardancy is not seen, and if it exceeds 2 parts by weight, the flame retardancy and mechanical properties are deteriorated.

  As the inorganic filler of the component (G), various commonly known fillers can be used. However, in order to improve the heat resistance and impact resistance of the composition, fibrous or flake-like ones can be used. Further, from the viewpoint of reducing carbon dioxide emission, an inorganic filler made of a pulverized natural mineral is more preferable.

  Specific examples of the component (G) include wollastonite, kaolin clay, mica and talc, and wollastonite, mica and talc are particularly preferable. The amount of component (G) is preferably 0.5 to 50 parts by weight, preferably 0.5 to 30 parts by weight, more preferably 100 parts by weight in total of (A) and (B). Is 0.5 to 10 parts by weight. If the amount is less than 0.5 part by weight, the effect of addition is not observed, and if it exceeds 50 parts by weight, the mechanical properties deteriorate, which is not preferable.

  The proportion of each component in the flame-retardant polylactic acid resin composition of the present invention is (A) component / (B) component = 5-50 / 50-95 (parts by weight), preferably (A) component / (B ) Component = 15-50 / 50-85 (parts by weight). Advantageously, the resin composition contains 5 to 50% by weight of component (A), 50 to 95% by weight of component (B), preferably 15 to 50% by weight of component (A), and 50 to 85% by weight of component (B). To exist. And (C) component is 1-30 weight part with respect to a total of 100 weight part of (A) component and (B) component, Preferably it is 5-20 weight part, (D) component is 0.1-10 weight Parts, preferably 0.5-5 parts by weight, component (E) is 1-50 parts by weight, preferably 3-30 parts by weight, and (F) is component 0.01-2 parts by weight, preferably 0.03-parts. 1.0 part by weight, component (G) is 0.5 to 50 parts by weight, preferably 0.5 to 10 parts by weight. And the following ranges are preferable for content of each component in the state except (G) component. (A) Component 10-40%, (B) Component 40-80%, (C) Component 5-20%, (D) Component 0.5-5%, (E) Component 3-30 % By weight. When the component (F) is present, the content is 0.03 to 1.0% by weight.

  The flame-retardant polylactic acid resin composition of the present invention can be used by blending an amount of additives in a range that does not impair the original properties for the purpose of imparting desired performance depending on the application. Examples of the additive include an external lubricant, an antioxidant, a heat stabilizer, an antistatic agent, an ultraviolet absorber, a light stabilizer, a plasticizer, a pigment, a dye, and a colorant.

  In the flame-retardant polylactic acid resin composition of the present invention, the above components (A) to (E), and the components (F) to (G) used as necessary are in the above proportions, and further if necessary. It can be obtained by blending various optional additive components to be used in an appropriate ratio, and melt-kneading. Compounding and melt-kneading at this time are usually used equipment such as ribbon blender, Henschel mixer, Banbury mixer, drum tumbler, single screw extruder, twin screw extruder, conida, multi-screw extruder, etc. It can be performed by a method using The heating temperature at the time of melt kneading is appropriately selected in the range of usually 240 to 300 ° C.

EXAMPLES Next, the present invention will be described with reference to examples, but the present invention is not limited thereto. In each example, the materials used are shown below.
(A) Polylactic acid resin: REVODE 101-B (trade name, Mw 150,000, manufactured by Kaisho Biological Materials Co., Ltd.)
(B) Aromatic polycarbonate resin: A-1900 (trade name, Mw 32,000, manufactured by Idemitsu Petrochemical Co., Ltd.)
(C) Styrene-butadiene block copolymer C-1: KK-38 (trade name, radial block structure, butadiene content 30%, manufactured by Chevron Phillips)
C-2: KR-05E (trade name, radial block structure, butadiene content 25%, manufactured by Chevron Phillips)
C-3: Asaflex 830 (trade name, triblock structure, butadiene content 30%, manufactured by Asahi Kasei Chemicals Corporation)
(D) Styrenic resin or acrylic resin D-1 having glycidyl methacrylate unit D-1: Marproof G-0250S (trade name, styrene resin, Mw 20,000, epoxy equivalent 310 (g / eq), NOF Corporation ) Made)
D-2: Marproof G-01100 (trade name, acrylic resin, Mw 12,000, epoxy equivalent 170 (g / eq), manufactured by NOF Corporation)
D-3: Marproof G-02050M (trade name, acrylic resin, Mw 200,000, epoxy equivalent 340 (g / eq), manufactured by NOF Corporation)
(E) Phosphorus flame retardant: CR-741 (trade name, condensed phosphate ester, manufactured by Daihachi Chemical Industry Co., Ltd.)
(F) Fluorine resin: 31-JR (trade name, tetrafluoroethylene-containing dispersion, manufactured by Mitsui DuPont Fluorochemical Co., Ltd.)
(G) Inorganic filler: TP-A25 (trade name, talc, average particle size 4.9 μm, manufactured by Fuji Talc Industry Co., Ltd.)

Moreover, evaluation of the flame-retardant polylactic acid resin compositions of the following examples and comparative examples was performed in the following manner.
(1) Impact resistance: As an impact resistance evaluation, evaluation was performed based on ASTM D256, using a notched Izod impact strength (KJ / m ² ) as a scale with a test piece having a thickness of 6.4 mm.

(2) Heat resistance: As a heat resistance evaluation, load deflection temperature (DTUL) under a load of 1.82 MPa was measured and evaluated in accordance with ASTM D256.

(3) Flame retardance: As a flame retardancy evaluation scale, evaluation was performed using a test piece having a thickness of 1.5 mm in accordance with the UL 94 vertical combustion test of the US UL standard. In the descending order of flame retardancy, the ranks are 5V, V-0, V-1, and V-2, and those that do not correspond to any rank are indicated as NG.

Examples 1-13 and Comparative Examples 1-4
The raw materials described above were blended at the composition ratios shown in Tables 1 to 4 (units are parts by weight), kneaded and granulated with a twin-screw extruder (cylinder temperature 260 ° C., rotation speed 200 rpm), and then injection molded machine (cylinder Test pieces for measuring various physical properties were obtained using a temperature of 230 ° C. and a mold temperature of 50 ° C. Tables 1 to 4 show the results of various evaluations using the obtained test pieces.

  As is clear from Tables 1 to 4, in Examples 1 to 13 containing essential components, heat resistance (load deflection temperature) and impact resistance (Izod impact) were compared with Comparative Examples 1 to 4 including only a part. Strength) and flame retardancy were confirmed to be significantly improved.

Claims (4)

  (A) Polylactic acid resin 5 to 50 parts by weight, (B) Aromatic polycarbonate resin 50 to 95 parts by weight, and (C) Styrene-butadiene block copolymer weight with respect to a total of 100 parts by weight of (A) and (B). 1 to 30 parts by weight of a coalescence, (D) 0.1 to 10 parts by weight of a resin comprising any one of a styrene resin or an acrylic resin having a glycidyl methacrylate unit, or a combination thereof, and (E) a phosphorus flame retardant A flame-retardant polylactic acid resin composition comprising 1 to 50 parts by weight.   (C) The flame retardant polylactic acid resin composition according to claim 1, wherein the styrene-butadiene block copolymer has a radial block structure and has a styrene content of 60 to 90% by weight.   The flame-retardant polylactic acid resin composition according to claim 1 or 2, wherein (F) 0.01 to 2 parts by weight of a fluorine-based resin is blended with respect to a total of 100 parts by weight of (A) and (B). object.   Furthermore, (G) inorganic filler is contained, The content is 0.5-50 weight part with respect to a total of 100 weight part of (A) and (B), The 1-3 characterized by the above-mentioned. The flame-retardant polylactic acid resin composition according to any one of the above.