JP2011006639A - Thermoplastic resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel polylactic acid-based thermoplastic resin composition improving impact resistance and elastic modulus, and having well-balanced impact resistance and high elastic modulus.SOLUTION: The composition includes: (A) 5-75 mass% of a polylactic acid resin, (B) 20-60 mass% of ABS resin; (C) 2-10 mass% of (meth)acrylic acid ester; and (D) 3-25 mass% of talc.

Description

  The present invention relates to a thermoplastic resin composition.

  With the recent increase in interest in global environmental problems, it is desired to realize a plastic that does not depend excessively on petroleum resources and has biodegradability. One of such plastic candidates is polylactic acid resin.

  However, polylactic acid resin is generally a hard and brittle material, and practical improvements are required in terms of impact resistance and elasticity.

  Therefore, various measures for solving such problems have been studied.

  For example, in order to improve the impact resistance of polylactic acid resin, a method of adding a modified olefinic compound (Patent Document 1), or in order to improve the balance between impact resistance and strength and rigidity, A method of polymer blending with ABS resin (Patent Document 2), in order to improve impact resistance as well as heat resistance and durability under high temperature and high humidity environment, rubber reinforced styrene resin, epoxy group, isocyanate group It has been proposed to blend a polymer having a reactive functional group such as polylactic acid (Patent Document 3).

  However, even in such conventional improvement measures, the improvement in impact resistance and elasticity is not always practically sufficient, and a polylactic acid-based thermoplastic resin having an excellent balance between impact resistance and improvement in elasticity The composition has not been realized.

JP 2006-199883 A JP 2006-161024 A JP 2007-291171 A

  From the background as described above, the present invention eliminates the problems of the prior art and is expected to be practically used in a wide range of fields such as home appliances, building materials, and sanitary fields. An object is to provide a new polylactic acid-based thermoplastic resin composition that is improved and has an excellent balance between impact resistance and high elastic modulus.

  The thermoplastic resin composition of the present invention is characterized by the following.

<First> The following composition;
(A) Polylactic acid resin: 5 to 75% by mass
(B) ABS resin: 20 to 60% by mass
(C) (Meth) acrylic acid ester polymer: 2 to 10% by mass
(D) Talc: 3 to 25% by mass
have.

  <Second> The above composition contains carbodiimide.

  According to the polylactic acid-based thermoplastic resin composition of the first aspect of the present invention, impact resistance and elastic modulus can be improved, and the balance between impact resistance and high elasticity is excellent. it can. As a result, it will be widely used in home appliances, building materials, sanitary fields, and the like.

  In addition, according to the second invention, by further containing a carbodiimide that reacts with a terminal group of polylactic acid, in addition to the above effects, durability under a high temperature and high humidity environment can be improved.

  The (A) polylactic acid resin contained in the thermoplastic resin composition of the present invention means polylactic acid and a copolymer of lactic acid and hydroxycarboxylic acid. Starch obtained from plants such as corn is fermented into lactic acid and polymerized by chemical synthesis.

  Examples of lactic acid include L- and / or D-lactic acid, lactone which is a dimer of lactic acid, and the like. Furthermore, examples of the hydroxycarboxylic acid copolymerizable with lactic acid include glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxypentanoic acid, and hydroxycaproic acid, and one or more can be used.

  In the present invention, commercially available poly L-lactic acid is preferred.

  The molecular weight of polylactic acid is not particularly limited, but it is considered that the weight average molecular weight is 10,000 or more, more preferably 30,000 or more from the viewpoint of physical and thermal properties.

  In addition, as polylactic acid, about the above polylactic acid resin, the mixture ratio shall be in the range of 5-75 weight%. If it is less than 5%, the structure as a polylactic acid resin is lost, and if it exceeds 75%, it becomes difficult to achieve impact resistance and high elastic modulus.

  On the other hand, the (B) ABS resin is well known as an acrylonitrile-butadiene-styrene copolymer. Although it is a rubber-like resin, it is considered that the gel content is usually in the range of 50 to 90% by mass, preferably 60 to 85% by mass. A commercially available ABS resin can also be used.

  About the compounding ratio of ABS resin, it shall be in the range of 20-60 mass%. If it is less than 20%, the impact resistance and the elastic modulus cannot be improved, and if it exceeds 60%, there are difficulties in terms of strength and durability.

  In the present invention, as described above, (C) (meth) acrylic acid ester polymer is blended. Here, (meth) acrylic acid ester polymer is acrylic acid ester polymer or methacrylic acid ester. It means that it is either a polymer or a copolymer of an acrylic ester and a methacrylic ester. In any case, the ester residue is preferably a lower alkyl group such as a methyl group or an ethyl group, or a phenyl group or a benzyl group. The range of the average molecular weight (Mw) of the (meth) acrylic acid ester polymer is preferably 50,000 to 150,000. Such a (meth) acrylic acid ester polymer can be used as a commercially available product.

  About the mixture ratio, it shall be in the range of 2-10 mass%. If it is less than 2%, it is difficult to improve the impact resistance, and if it exceeds 10%, the elastic modulus is low.

  Furthermore, in the present invention, (D) talc is blended. This talc is well known as a commercially available filler material. About the magnitude | size, it is usually preferable to set it as the thing within the range of a particle size of 0.5 micrometer-12 micrometers.

  The blending ratio of talc is in the range of 3 to 25% by mass.

  When the amount of talc is less than 3%, the elastic modulus cannot be improved, and when it exceeds 25%, the impact resistance is lowered.

  And in the thermoplastic resin composition of this invention, it is still more effective to contain the carbodiimide which reacts with the terminal group of polylactic acid other than the said component. Thereby, the durability under a high temperature and high humidity environment is improved.

  The carbodiimide can be used as a commercially available product, and the blending ratio thereof is preferably in the range of 0.1 to 5% by mass in the total amount of the composition of the present invention. If it is less than 0.1%, the improvement of the durability cannot be expected so much, and if it exceeds 5%, the reaction becomes excessive during melt-kneading and the melt viscosity increases and the moldability may be impaired.

  Furthermore, in the thermoplastic resin composition of the present invention, as long as the object and effect of the present invention are not impaired, a stabilizer, pigment, dye, reinforcing agent (mica, Clay, glass fiber, etc.), colorants, ultraviolet absorbers, antioxidants, lubricants, mold release agents, plasticizers, antistatic agents, inorganic and organic antibacterial agents, and the like.

  The thermoplastic resin composition of the present invention as described above can be produced by mixing and kneading each component. In the case of producing as pellets, there is no particular limitation, and for example, a twin screw extruder, a Banbury mixer, a heating roll or the like can be used. Among them, melt kneading by a twin screw extruder is preferable, and if necessary, side Resins and other additives can be blended by feeding or the like.

  The polylactic acid-based resin composition of the present invention can be molded into various molded products by a usual molding method such as injection molding, blow molding, sheet molding, vacuum molding and the like.

  Therefore, an example will be shown below and will be described in more detail. Of course, the present invention is not limited to the following examples.

<Manufacture of resin composition>
Composition distribution is used at the blending ratio (unit: mass%) shown in Table 1.

  The resin component is dried in advance, and the blend is mixed for 10 minutes with a tumbler and passed through a twin screw extruder.

  The temperature of the twin screw extruder was set to 190 ° C. near the die and 200 ° C. near the inlet.

  The strand exiting the twin screw extruder is immediately cooled in a cooling bath.

The strand was then cut into 2-4 mm pellets with a cutter.
<Molding>
Prior to molding, the pellets were dried.

  Drying was performed by a dehumidifying dryer at 120 ° C. for 4 hours.

  Molding was performed with a 100-ton injection molding machine.

  The cylinder temperature is set to 200 ° C near the head and 190 ° C near the material inlet.

Mold temperature is 40 ° C.
<Evaluation>
1) The obtained molded article samples were evaluated for impact resistance, elastic modulus, and durability. The method at that time was as follows.
(Evaluation methods)
Impact resistance Measured Charpy impact value with notch according to ISO 179.

Elastic modulus Measures the tensile modulus in accordance with ISO 527.

durability
A wet heat test was conducted at 60 ° C. and 95% RH, and the time during which the tensile strength retention was 80% or less was defined as the durability performance. Tensile strength conforms to IS0527.

2) As is clear from the comparison between Examples 1 to 8 and Comparative Examples 1 to 5 shown in Table 1, according to the examples of the present invention,
Impact resistance: 10 KJ / m ² or more Elastic modulus: 3.2 GPa or more in excellent balance properties. Moreover, the durability is 70 hours or more.

Claims (2)

The following formulation:
(A) Polylactic acid resin: 5 to 75% by mass
(B) ABS resin: 20 to 60% by mass
(C) (Meth) acrylic acid ester polymer: 2 to 10% by mass
(D) Talc: 3 to 25% by mass
A thermoplastic resin composition characterized by comprising:   The thermoplastic resin composition according to claim 1, comprising carbodiimide.