JP2010006892A - Thermoplastic resin composition and its molded article - Google Patents

Abstract

A thermoplastic resin composition containing polylactic acid and excellent in heat resistance and moldability, and a molded body thereof.
A thermoplastic resin composition containing a polylactic acid (A), a cellulose derivative (B) and a phosphorus-containing compound (C), and preferably satisfies the following conditions (1) and (2) Resin composition. And the molded object obtained by shape | molding the thermoplastic resin composition.
(1): Mass ratio of (A) / (B) is 40/60 to 99/1.
(2): The content of (C) is 1 to 60 parts by mass with respect to a total of 100 parts by mass of (A) and (B).
[Selection figure] None

Description

  The present invention relates to a thermoplastic resin composition containing polylactic acid and excellent in heat resistance and moldability, and a molded body thereof.

Resin materials are widely used in various applications such as parts for automobiles, home appliances, and OA equipment. In recent years, a shift from petroleum-based resins to non-petroleum-based resins has been demanded due to increasing interest in environmental problems. However, since non-petroleum resins are inferior in performance compared to petroleum resins, attempts have been made to improve them.
Polylactic acid is a non-petroleum resin produced from plant-derived raw materials such as corn and sweet potato, and is expected to be an alternative material for petroleum-based resins because of its excellent mechanical properties and moldability. However, it has problems such as poor heat resistance.

As a method for improving the heat resistance of polylactic acid, a method in which a cellulose derivative having a hydroxyl group substituted by esterification or the like is blended with polylactic acid (Patent Document 1), and a method in which a cellulose derivative and a polycarbonate are blended with polylactic acid (Patent Document 2). ) Has been proposed.
However, the method proposed in Patent Document 1 does not sufficiently improve the heat resistance of polylactic acid.
Moreover, in the method proposed in Patent Document 2, although the heat resistance of polylactic acid is improved, since polycarbonate is an essential component, the content of non-petroleum resin is low, and only an opaque molded body is obtained. .
JP 2004-204217 A JP 2006-111858 A

  An object of the present invention is to provide a thermoplastic resin composition containing polylactic acid and having excellent heat resistance and moldability, and a molded product thereof.

  As a result of intensive studies, the present inventors have found that a thermoplastic resin composition having transparency and excellent heat resistance and moldability can be obtained by blending a cellulose derivative and a phosphorus-containing compound with polylactic acid.

That is, the thermoplastic resin composition of the present invention contains polylactic acid (A), cellulose derivative (B), and phosphorus-containing compound (C).
The thermoplastic resin composition of the present invention preferably satisfies the following conditions (1) and (2).
(1): Mass ratio of (A) / (B) is 40/60 to 99/1.
(2): The content of (C) is 1 to 60 parts by mass with respect to a total of 100 parts by mass of (A) and (B).

  The molded body of the present invention is obtained by molding the thermoplastic resin composition.

The thermoplastic resin composition of the present invention can give a molded article excellent in heat resistance with good moldability.
Since the molded product of the present invention is excellent in heat resistance, it can be used as an alternative material for conventional petroleum-based resins in automobiles, home appliances, OA equipment parts, and the like.

Hereinafter, the present invention will be described in detail.
The polylactic acid (A) of the present invention may be a homopolymer of lactic acid or a copolymer of a copolymerizable component capable of copolymerizing with lactic acid and lactic acid.
Examples of the copolymer component include glycol compounds such as ethylene glycol, propylene glycol, and butanediol; dicarboxylic acids such as oxalic acid, adipic acid, and cyclohexanedicarboxylic acid; hydroxycarboxylic acids such as glycolic acid, hydroxypropionic acid, and hydroxybutyric acid; Examples include lactones such as caprolactone and valerolactone.
The copolymerization component is preferably used in an amount of 0 to 30 mol%, more preferably 0 to 10 mol%, based on all monomers (100 mol%).

  Considering the heat resistance of the resulting thermoplastic resin composition, the polylactic acid (A) is preferably lactic acid with high optical purity. For example, in all lactic acid components, the content of either the L-form or the D-form is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more.

The melting point of polylactic acid (A) is preferably 120 ° C. or higher, and more preferably 150 ° C. or higher.
The higher the optical purity of the lactic acid used, the higher the melting point of the resulting polylactic acid. For example, when the content of either L-form or D-form in lactic acid is 90% by mass or more, a polylactic acid having a melting point of 120 ° C. or more can be obtained, and in the case of 95% by mass or more, a melting point of 150 ° C. The above polylactic acid can be obtained.

  The mass average molecular weight of the polylactic acid (A) is preferably 50,000 or more, more preferably 80,000 or more, and even more preferably 100,000 or more. The mass average molecular weight of polylactic acid (A) is preferably 300,000 or less.

  As a method for producing the polylactic acid (A), a known polymerization method can be used. Examples thereof include a direct polymerization method from lactic acid and a ring-opening polymerization method via lactide.

The cellulose derivative (B) of the present invention is obtained by chemically substituting a functional group of cellulose.
Considering the heat resistance and moldability of the resulting thermoplastic resin composition, the cellulose derivative (B) is preferably a cellulose ester obtained by esterifying all or part of the hydroxyl groups of cellulose.

Examples of the cellulose ester include cellulose diacetate, cellulose triacetate, cellulose acetate propionate, cellulose acetate butyrate, and cellulose acetate butyrate.
These may be used alone or in combination of two or more.
Among these, cellulose diacetate and cellulose triacetate are preferable in consideration of the heat resistance of the resulting thermoplastic resin composition.

The phosphorus-containing compound (C) of the present invention is not particularly limited as long as it is a phosphorus-containing compound.
Examples of the phosphorus-containing compound (C) include triphenyl phosphate, tricresyl phosphate, isopropylated triphenyl phosphate, diphenylpentaerythritol diphosphate, phenyl bis (dodecyl) phosphate, phenyl bis (neopentyl) phosphate, phenyl bis (3 , 5,5′-trimethylhexyl) phosphate, ethyl diphenyl phosphate, 2-ethylhexyl di (p-tolyl) phosphate, bis (2-ethylhexyl) p-tolyl phosphate, tolyl phosphate, bis (2-ethylhexyl) phenyl phosphate, Tri (nonylphenyl) phosphate, bis (dodecyl) p-tolylphosphate, dibutylphenyl phosphate, 2-chloroethyldiphenylphosphate, p-to Aromatic phosphates such as rilbis (2,5,5′-trimethylhexyl) phosphate, 2-ethylhexyldiphenylphosphate; resorcinol-di-phosphate, phenylenebis (di-2,6-xylenylphosphate), resorcinol tetra Aromatic condensed phosphates such as phenyl diphosphate, hydroquinone bis (diphenyl) phosphate, bisphenol A bis (diphenyl) phosphate; oligomers or polymers of aromatic phosphates and / or aromatic condensed phosphates; Examples include phosphorus-nitrogen-containing compounds such as phosphorus ester amide, phosphoric acid amide, phosphonic acid amide, phosphinic acid amide, and tris (aziridinyl) phosphine oxide.

  Among these, considering the heat resistance, moldability, transparency and molding appearance of the obtained thermoplastic resin composition, triphenyl phosphate, tricresyl phosphate, isopropylated triphenyl phosphate, diphenylpentaerythritol diphosphate, resorcinol -Di-phosphate and phenylene bis (di-2,6-xylenyl phosphate) are preferable, and triphenyl phosphate, resorcinol-di-phosphate, and phenylene bis (di-2,6-xylenyl phosphate) are more preferable.

Examples of commercially available phosphorus-containing compounds (C) include trade names “TPP” (triphenyl phosphate), “CR-733S” (resorcinol-di-phosphate), “PX-200” (1,3-phenylenebis). (Di-2,6-xylenyl phosphate) (above, manufactured by Daihachi Chemical Industry Co., Ltd.).
These may be used alone or in combination of two or more.

The ratio of each component in the thermoplastic resin composition of the present invention preferably satisfies the following conditions (1) and (2).
(1): The mass ratio of polylactic acid (A) / cellulose derivative (B) is 40/60 to 99/1.
(2): The content of the phosphorus-containing compound (C) is 1 to 60 parts by mass with respect to 100 parts by mass in total of the polylactic acid (A) and the cellulose derivative (B).

Considering the heat resistance and moldability of the resulting thermoplastic resin composition, the mass ratio of polylactic acid (A) / cellulose derivative (B) is more preferably 50/50 to 90/10, and 60/40 to 80 / 20 is more preferable.
Moreover, when the transparency and molding appearance of the obtained molded product are taken into consideration, the content of the phosphorus-containing compound (C) is 3 to 40 masses with respect to a total of 100 mass parts of the polylactic acid (A) and the cellulose derivative (B). Part is more preferable, and 5 to 15 parts by mass is further preferable.

The thermoplastic resin composition of this invention can mix | blend other thermoplastic resins as needed.
As other thermoplastic resins, for example, styrene resins such as polystyrene, high impact polystyrene, acrylonitrile-styrene resin, acrylonitrile-butadiene-styrene resin, styrene-butadiene copolymer, hydrogenated styrene-butadiene copolymer; Olefin resins such as polypropylene, low density polyethylene, high density polyethylene, ethylene-propylene copolymer, cyclic olefin-containing polymer; polyester resins such as polyethylene terephthalate, polytrimethylene glycol terephthalate, polybutylene terephthalate; polycarbonate resins Can be mentioned.

  The amount of the other thermoplastic resin (petroleum resin) blended in the thermoplastic resin composition of the present invention is preferably as small as possible, and is 0 in the total components (100% by mass) in the thermoplastic resin composition of the present invention. -30 mass% is preferable, 0-20 mass% is more preferable, and 0-10 mass% is further more preferable.

  The thermoplastic resin composition of the present invention comprises, as necessary, known additives such as antioxidants, light stabilizers, flame retardants, plasticizers; glass fibers, carbon fibers, talc, calcium carbonate, kenaf, bacterial cellulose Fillers such as pigments; impact resistance modifiers such as rubber-containing graft copolymers; and molding processability modifiers such as acrylic and / or styrene-based polymers.

The thermoplastic resin composition of the present invention can be obtained by blending polylactic acid (A), cellulose derivative (B), phosphorus-containing compound (C), and various additives as required by a known method.
Examples of the blending method include a blending method using a batch kneader, a single-screw or multi-screw extruder, and the like.

The thermoplastic resin composition of the present invention can be used for production of various molded products by applying known molding methods such as extrusion molding, injection molding, press molding, inflation molding, calendar molding and the like.
The molded body of the present invention can be used for various applications such as parts for automobiles, home appliances, and OA equipment.

  Hereinafter, the present invention will be described specifically by way of examples. “Part” and “%” represent “part by mass” and “% by mass”, respectively. Moreover, evaluation was implemented with the following method.

(1) Heat resistance The Vicat softening temperature of the obtained molded body was measured with a load of 10 N in accordance with ASTM-D1525.

(2) Moldability The molding conditions (barrel temperature of the desktop injection molding machine) when the obtained thermoplastic resin composition was molded using a desktop injection molding machine were evaluated according to the following criteria.
○: Molding was possible at a barrel temperature of 220 ° C.
Δ: Molding was not possible at a barrel temperature of 220 ° C. and molding was possible at a barrel temperature of 260 ° C., but the resulting molded product was severely colored.
×: Could not be molded at a barrel temperature of 260 ° C.

(3) Transparency The total light transmittance of the obtained molded product was measured in accordance with JIS-K3261, with a test piece thickness of 2 mm and an opening through which light was transmitted as a diameter of 6 mm, and was evaluated according to the following criteria.
○: Total light transmittance of 60% or more Δ: Total light transmittance of 30% or more and less than 60% ×: Total light transmittance of less than 30%

(4) Molding appearance The obtained molding was observed visually and evaluated according to the following criteria.
○: Good △: Presence of fibrils and the like was observed in part.
X: Fibrous cracks were observed.

[Examples 1 to 3]
Polylactic acid (trade name “Lacia H-100”, manufactured by Mitsui Chemicals, Inc.), cellulose diacetate (trade name “L-40”, manufactured by Daicel Chemical Industries, Ltd., acetylation degree 55%), cellulose triacetate ( The trade name “LT-35”, manufactured by Daicel Chemical Industries, Ltd. (degree of acetylation 61%), triphenyl phosphate (trade name “TPP”, manufactured by Daihachi Chemical Industry Co., Ltd.) are shown in Table 1. Using a kneader (trade name “Plastic Coder”, manufactured by Brabender, internal volume 50 cm ³ ), melt blending was performed at a barrel temperature of 220 ° C. to obtain thermoplastic resin compositions (I) to (C).

These thermoplastic resin compositions were melted at a barrel temperature of 220 ° C. or 260 ° C. using a desktop injection molding machine (trade name “CS-183”, manufactured by Custom Scientific Instruments) and injected into the mold. .
After cooling the mold to room temperature, a molded body (length 20 mm × width 10 mm × thickness 2 mm) was taken out from the mold.
Using the obtained test piece, moldability, molding appearance, heat resistance, and transparency were evaluated. The evaluation results are shown in Table 1.

Table 1

[Comparative Example 1]
A molded body was obtained in the same manner as in Example 1, using polylactic acid (trade name “Lacia H-100”, manufactured by Mitsui Chemicals, Inc.) as a raw material. The evaluation results are shown in Table 1.

[Comparative Examples 2 to 5]
The thermoplastic resin compositions (d) to (g) were obtained in the same manner as in Example 1 except that the raw material composition was changed as shown in Table 1. Using these thermoplastic resin compositions, molded articles were obtained in the same manner as in Example 1. The evaluation results are shown in Table 1.

As is clear from Table 1, the molded bodies (Examples 1 to 3) containing polylactic acid (A), cellulose derivative (B), and phosphorus-containing compound (C) were excellent in heat resistance and moldability. Moreover, it was confirmed that the transparency and the molded appearance can be improved by adjusting the content of the phosphorus-containing compound.
When cellulose diacetate was used as the cellulose derivative (B), the moldability and transparency of the obtained molded product were particularly excellent.

  The molded product of polylactic acid (A) alone (Comparative Example 1) was inferior in heat resistance. Moreover, the molded object (Comparative Example 3) which does not contain a cellulose derivative (B) and contains a polylactic acid (A) and a phosphorus-containing compound (C) was similarly inferior in heat resistance.

The molded article (Comparative Example 2) containing the polylactic acid (A) and the cellulose derivative (B) without the phosphorus-containing compound (C) was inferior in moldability. Moreover, the molded object (Comparative Example 5) using dibutyl phthalate as a plasticizer instead of the phosphorus-containing compound (C) was similarly inferior in moldability.
The molded product (Comparative Example 4) which does not contain polylactic acid (A) and contains the cellulose derivative (B) and the phosphorus-containing compound (C) was inferior in moldability.

  From the above results, the thermoplastic resin composition of the present invention contains polylactic acid by containing polylactic acid (A), cellulose derivative (B), and phosphorus-containing compound (C). It is clear that it is excellent in heat resistance and moldability.

  Since the thermoplastic resin composition of the present invention can give a molded article having excellent heat resistance with good moldability, it can be used as an alternative material for conventional petroleum-based resins in parts of automobiles, home appliances, OA equipment, and the like. it can.

Claims (3)

  A thermoplastic resin composition comprising polylactic acid (A), a cellulose derivative (B), and a phosphorus-containing compound (C). The thermoplastic resin composition according to claim 1, which satisfies the following conditions (1) and (2).
(1): Mass ratio of (A) / (B) is 40/60 to 99/1.
(2): The content of (C) is 1 to 60 parts by mass with respect to a total of 100 parts by mass of (A) and (B).   The molded object obtained by shape | molding the thermoplastic resin composition of Claim 1 or 2.