JP2016132699A - Polylactic acid-based resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polylactic acid-based resin composition which has a high crystallization rate of a polylactic resin, and can shorten a time required for forming.SOLUTION: A resin composition contains a polylactic resin, an organic sulfonic acid metal salt, ethylene-bis-carboxylic acid amide and talc. The polylactic resin has a content of a D body of 1.0 mol% or less, and a melt flow rate when measured at 190°C and load of 21.2 N of 0.1-15 g/10 minutes. Based on 100 pts.mass of the polylactic resin, 8-20 pts.mass of the organic sulfonic acid metal salt, the ethylene-bis-carboxylic acid amide and the talc are contained in total.SELECTED DRAWING: None

Description

  The present invention is a polylactic acid resin composition containing an organic sulfonic acid metal salt, ethylenebiscarboxylic amide and talc in a polylactic acid resin, and has a high crystallization speed and excellent moldability. It is about things.

  Generally, as a raw material for molding, polypropylene resin (PP), acrylonitrile-butadiene-styrene resin (ABS), polyamide resin (PA6, PA66 etc.), polyester resin (PET, PBT etc.), polycarbonate resin (PC) etc. It is used. Molded articles made from such resins are excellent in moldability and mechanical strength, but when discarded, they increase the amount of dust and are hardly decomposed in the natural environment. It remains in the ground semipermanently.

  Therefore, in recent years, biodegradable polyester resins have attracted attention from the viewpoint of environmental conservation. Among them, polylactic acid, polyethylene succinate, polybutylene succinate and the like are low in cost and highly useful because they can be mass-produced. In particular, polylactic acid has already been industrially produced from plants such as corn and sweet potato, and even if incinerated after use, considering the carbon dioxide absorbed during the growth of these plants, the carbon balance is neutral. Therefore, it is considered as a resin with a low impact on the global environment.

  The polylactic acid resin is improved in heat resistance by sufficiently proceeding with crystallization, and can be applied to a wide range of uses. However, the polylactic acid resin alone has a very low crystallization rate. Therefore, a method of adding various crystal nucleating agents to a polylactic acid resin is usually proposed for the purpose of improving the crystallization rate.

  For example, the addition of a carboxylic acid amide or ester having a specific molecular structure to Patent Document 1, the addition of tricyclohexyltrimesic acid amide to Patent Document 2, and the addition of ethylenebis-12 to Patent Document 3 -Addition of hydroxystearic acid amide is disclosed. However, since the D-form content of the polylactic acid resin is large and the selection and amount of the nucleating agent are not appropriate, the crystallization rate cannot be sufficiently improved.

WO2006 / 13797 Publication JP 2006-328163 A JP 2003-226801 A

  The present invention is intended to solve the above-mentioned problems, and an object of the present invention is to obtain a polylactic acid-based resin composition capable of shortening the molding time with a high crystallization speed of the polylactic acid resin. It is.

  As a result of intensive studies to solve the above problems, the present inventor used an organic sulfonic acid metal salt, ethylenebiscarboxylic amide, and talc for polylactic acid resin, and blended them in a specific amount. The present inventors have found that the above problems can be solved and have reached the present invention.

  That is, the present invention is a resin composition containing a polylactic acid resin, an organic sulfonic acid metal salt, ethylene biscarboxylic amide, and talc, wherein the polylactic acid resin has a D-form content of 1.0 mol% or less, and The melt flow rate measured at 190 ° C. and 2.16 kg is 0.1 to 10 g / 10 min, and the total amount of the organic sulfonic acid metal salt, ethylenebiscarboxylic amide and talc is 100 parts by mass of the polylactic acid resin. The main content is a polylactic acid resin composition characterized by containing 8 to 20 parts by mass.

  The polylactic acid-based resin composition of the present invention sufficiently improves the crystallization speed of the polylactic acid resin by containing a specific amount of an organic sulfonic acid metal salt, ethylenebiscarboxylic amide and talc in the polylactic acid resin. And the time required for molding can be shortened. For this reason, the polylactic acid-type resin composition of this invention can be used for various uses, the use range of the polylactic acid resin which is a low environmental impact material can be expanded greatly, and industrial utility value is very high.

Hereinafter, the present invention will be described in detail.
First, the polylactic acid resin constituting the polylactic acid-based resin composition of the present invention is required to have a D-form content of 1.0 mol% or less, and more preferably 0.8 mol% or less. More preferably, it is 0.7 mol% or less. When the D-form content is within this range, the crystallinity is excellent. That is, the crystallization speed is high, and a molded body can be obtained in a short molding cycle. Further, the amount of expensive crystal nucleating agent added can be suppressed, which is advantageous in terms of cost.

  In the present invention, the D-form content of the polylactic acid resin is a ratio (mol%) occupied by the D lactic acid unit in the total lactic acid units constituting the polylactic acid resin. Therefore, for example, in the case of a polylactic acid resin having a D-form content of 1.0 mol%, this polylactic acid resin has a ratio of D lactic acid units of 1.0 mol% and a ratio of L lactic acid units of 99. 0.0 mol%.

  And, as will be described later, by containing three kinds of organic sulfonic acid metal salt, ethylene biscarboxylic acid amide and talc as additives for promoting crystallization, a resin composition having further excellent crystallinity can be obtained. However, by using a polylactic acid resin having a D-form content of 1.0 mol% or less, the effects of these crystallization promoting additives become more remarkable.

  In the present invention, as described later in Examples, the D-form content of the polylactic acid resin is obtained by converting all the L lactic acid and D lactic acid obtained by decomposing the polylactic acid resin into methyl esters, It is calculated by a method of analyzing D-lactic acid methyl ester with a gas chromatography analyzer.

Furthermore, the polylactic acid resin may be abbreviated as a melt flow rate [MFR] measured at 190 ° C. and a load of 21.2 N. The value according to JIS K-7210 (test condition 4)] is 0.1 to 15 g / 10 min, preferably 0.2 to 13 g / 10 min, more preferably 0.5 to 10 g / min. It is preferable.
When the MFR satisfies the above range, the dispersibility of the additive for promoting crystallization described below and other various additives is improved, and the mechanical properties of the resulting molded article are also improved.

  As long as the MFR is in the above range, two or more types of polylactic acid resins having different MFRs may be used. Especially, it is preferable that the thing of MFR 5 g / 10min or less exists 20 mass% or more of the whole polylactic acid resin.

  As the polylactic acid resin used in the present invention, among various commercially available polylactic acid resins, a polylactic acid resin having a D-form content defined by the present invention can be used. In addition, among lactides, which are cyclic dimers of lactic acid, L-lactide having a sufficiently low D-form content or D-lactide having a sufficiently low L-form content is used as a raw material, and a known melt polymerization method is used. Alternatively, those produced by further using a solid phase polymerization method can be used.

  In the present invention, an organic sulfonic acid metal salt and ethylene biscarboxylic amide are used in combination as an additive (nucleating agent) for promoting crystallization. As a specific substance, for example, a combination of dimethyl metal salt of 5-sulfoisophthalic acid and ethylene bishydroxystearic acid amide is preferable. These are each used alone as a nucleating agent, but when used in combination with talc described later, the effect of promoting crystallization of the polylactic acid resin becomes remarkable.

  The total amount of the organic sulfonic acid metal salt and the ethylene biscarboxylic amide is preferably 0.5 to 3 parts by mass, more preferably 0.8 to 2.5 parts by mass with respect to 100 parts by mass of the polylactic acid resin. It is preferable. The ratio of the organic sulfonic acid metal salt to the ethylenebiscarboxylic acid amide is preferably 80/20 to 20/80, more preferably 75/25 to 25/75, in terms of the mass ratio of both.

  Furthermore, the polylactic acid-based resin composition of the present invention contains talc as an additive (nucleating agent) that promotes crystallization of the polylactic acid resin. By adding talc, the effect of promoting crystallization of polylactic acid resin can be improved, as well as the molded body that has been crystallized in a high-temperature mold can be taken out with sufficient rigidity. Improves.

  The total amount of the organic sulfonic acid metal salt, ethylenebiscarboxylic amide, and talc needs to be 8 to 20 parts by mass with respect to 100 parts by mass of the polylactic acid resin, and in particular, 10 to 18 parts by mass. preferable.

  When the content of various additives that promote crystallization of the polylactic acid resin is less than the above value, the effect of promoting crystallization is poor. On the other hand, when the content is larger than the above value, the crystallization promoting effect is saturated and disadvantageous in terms of cost, and at the same time, the mechanical properties are poor or the surface appearance is inferior.

  Various types of talc can be used. In view of the above-mentioned purpose and considering the appearance of the obtained molded body, it is preferable to use one having an average particle diameter of 0.5 to 20 μm.

  Furthermore, the polylactic acid resin composition of the present invention preferably contains an impact resistance improver. As the impact resistance improver, a multilayer structure polymer having a core layer and a shell layer is preferably used. The multilayer structure polymer is a polymer having a so-called core-shell type structure in which a core layer and a shell layer covering the core layer are formed, and adjacent layers are formed of different types of polymers. The number of layers in both the core layer and the shell layer is 1 or more, and the core layer and the shell layer may have two or more layers. The shell layer component is preferably obtained by graft polymerization in the presence of the core layer component.

  Specifically, “Metabrene S-2006”, “Metabrene S-2200”, “Metabrene W-450A”, “Metabrene W-600A” manufactured by Mitsubishi Rayon Co., Ltd., “Paralloid BPM-500” manufactured by Rohm and Haas Co., Ltd. And “Paralloid BPM-515”.

  By including such an impact resistance improver, the impact resistance of the polylactic acid-based resin composition is improved. However, if a polylactic acid resin satisfying the above-mentioned D-form content is used, Impact is greatly improved. That is, when an impact modifier is added to a polylactic acid resin having a normal D-form content, impact resistance can be imparted, but crystallinity deteriorates. However, in the polylactic acid resin composition whose crystallinity is improved by the above-mentioned polylactic acid resin having a specific D range and a specific nucleating agent, it is possible to impart impact resistance while maintaining good crystallinity. It becomes. In addition, in the resin composition having improved crystallinity as described above, the effect of the impact resistance improver is sufficiently exerted, and the impact resistance is greatly improved.

  The polylactic acid resin composition of the present invention preferably contains a carbodiimide compound for the purpose of improving the durability of the resin composition. As the carbodiimide compound, various compounds can be used and are not particularly limited as long as they have one or more carbodiimide groups in the molecule. For example, aliphatic monocarbodiimide, aliphatic polycarbodiimide, alicyclic mono Carbodiimide, alicyclic polycarbodiimide, aromatic monocarbodiimide, aromatic polycarbodiimide, or the like can be used. Furthermore, you may have various heterocyclic rings or various functional groups in a molecule | numerator.

  Specific products of the carbodiimide compound include, for example, monocarbodiimide, “STABAXOL I” and “STABAXOL IP” manufactured by Rhein Chemie, “EN-160” manufactured by Matsumoto Yushi Seiyaku Co., Ltd. “HMV-15CA”, “HMV-8CA”, “Stavaxol P” manufactured by Rhein Chemie, and “LA-1” manufactured by Nisshinbo Co., Ltd. as polycarbodiimide having an isocyanate group in the molecule.

  In addition, the polylactic acid-based resin composition of the present invention is blended with a release agent for the purpose of smoothly releasing the molded body having a reduced rigidity in the high-temperature mold from the mold surface. Also good. Various release agents can be used. Specifically, a carboxylic acid amide such as erucic acid amide is preferable.

  The polylactic acid-based resin composition of the present invention preferably contains a plasticizer for promoting the effect of improving the crystallization speed and impact resistance. Examples of the plasticizer include fatty acid ester, high fatty acid ester, alcohol ester, polyhydric alcohol ester, glycerin ester, and polyglycerin ester.

  Furthermore, a pigment, a heat stabilizer, an antioxidant, a weathering agent, a lubricant, an antistatic agent, and the like can be added to the polylactic acid resin composition of the present invention as long as the characteristics are not significantly impaired. Examples of heat stabilizers and antioxidants include hindered phenols, hindered amines, sulfur compounds, copper compounds, alkali metal halides, and the like. In addition, the method of mixing these with the resin composition of this invention is not specifically limited.

  The polylactic acid resin composition of the present invention can be preferably applied to injection molding. As an example of injection molding conditions suitable for the polylactic acid resin composition of the present invention, the cylinder temperature is not less than the melting point or flow start temperature of the resin composition, preferably 170 to 250 ° C., and the mold temperature is It is preferable that the temperature is in the vicinity of 80 to 120 ° C. where crystallization of the lactic acid resin is likely to proceed. If the molding temperature is too low, the operability becomes unstable, such as short-circuiting in the molded body, and it tends to be overloaded. Conversely, if the molding temperature is too high, the resin composition will decompose and the resulting molded body Problems such as reduction in strength and coloration are likely to occur, and both may be undesirable.

  Specific examples of the molded body made of the polylactic acid resin composition of the present invention include, for example, daily necessaries having various heat resistance, tableware, crafts, interiors in cars, toys, electronic equipment cases, and various electronic components. Etc.

  Hereinafter, the present invention will be described more specifically with reference to examples. The measuring method used for the evaluation of the resin compositions (molded articles) of Examples and Comparative Examples is as follows.

(1) Heat resistance Using the obtained test piece, the deflection temperature under load (DTUL) at a load of 0.45 MPa was measured according to ISO75.
The deflection temperature under load is preferably 120 ° C. or higher.
(2) Impact resistance Charpy impact value was measured according to ISO179 using the obtained test piece.
The Charpy impact value is preferably 9 kJ / m ² or more.
(3) Molding cycle When preparing a test piece for measuring general physical properties (ISO type), after the resin composition is injected (filling, holding pressure) into the mold and cooled, the molded body is fixed to the mold. Alternatively, the molding cycle was defined as the shortest required time (seconds) until it was possible to take out without resistance, and there was no deformation due to the protruding pin, and the mold could be released satisfactorily. The shortest required time of 10 test pieces was measured and taken as the average value.
In addition, the molding cycle exceeding 29 seconds was judged to be inferior in moldability.

Moreover, the various raw materials used for the Example and the comparative example are as follows.
[Polylactic acid resin]
PLA-1: “3100HP” manufactured by NatureWorks (D-form content: 0.6 mol%, MFR: 10 g / 10 min)
PLA-2: “2,500HP” manufactured by NatureWorks (D-form content 0.6 mol%, MFR 3 g / 10 min)
PLA-3: “3001D” manufactured by NatureWorks (D-form content: 1.4 mol%, MFR: 10 g / 10 min)
PLA-4: “4032D” manufactured by NatureWorks (D-form content: 1.4 mol%, MFR: 3 g / 10 min)

[Crystal nucleating agent]
S-1: “LAK-403” (5-sulfoisophthalic acid dimethyl metal salt) manufactured by Takemoto Yushi Co., Ltd.
S-2: “ASA T-530SF” (ethylene bishydroxystearic acid amide) manufactured by Ito Oil Co., Ltd.
〔talc〕
T-1: “MS” (average particle size: 14 μm) manufactured by Nippon Talc
・ T-2: Hayashi Kasei Co., Ltd. “MWHST” (average particle size 5 μm)

[Impact resistance improver]
・ M-1: “Metablene S-2006” manufactured by Mitsubishi Rayon Co., Ltd.
[Other additives]
EN160: Carbodiimide compound: Monocarbodiimide “EN160” manufactured by Matsumoto Yushi Co., Ltd.
P-10: Mold release agent: Erucic acid amide “Alflow P-10 (EA-P10)” manufactured by NOF Corporation
VR-01: Plasticizer: Taiyo Kagaku Glycerin fatty acid ester surfactant “VR-01”
TG-1: Plasticizer: Triglyceride (C8-10) “M-1” manufactured by Riken Vitamin

Example 1
As a polylactic acid-based resin, 69 parts by mass of PLA-1 and 31 parts by mass of PLA-2, 0.9 parts by mass of S-1 as an organic sulfonic acid metal salt, and 0.2% of S-2 as an ethylenebiscarboxylic amide. 3 parts by weight, 11 parts by weight of T-1 as talc, 6 parts by weight of M-1 as an impact modifier, 1.8 parts by weight of EN-160, 0.24 of P-10 as other additives Using 1.2 parts by mass of TG-1 and 0.6 parts by mass of VR-01, dry blending was performed, and the mixture was supplied from the root supply port of a twin-screw extruder (TEM 37BS manufactured by Toshiba Machine Co., Ltd.). Extrusion was carried out while venting under the conditions of a barrel temperature of 180 ° C., a screw rotation speed of 150 rpm, and a discharge of 20 kg / h. The resin discharged from the tip of the extruder was cut into pellets to obtain pellets of a polylactic acid resin composition.
The obtained pellets were dried with hot air at 80 ° C. for 8 hours, and then a test piece for measuring general physical properties (ISO) while adjusting the mold surface temperature to 105 ° C. using an IS-80G injection molding machine manufactured by Toshiba Machine Co., Ltd. Mold) and prepared for various measurements.

Examples 2-3 and Comparative Examples 1-4
Except for changing the types and amounts of polylactic acid resin, organic sulfonic acid metal salt, ethylenebiscarboxylic amide, talc, impact modifier and other additives as shown in Table 1, the same as in Example 1 To obtain pellets of the polylactic acid resin composition.
Then, injection molding was performed in the same manner as in Example 1 to prepare a test piece for general physical property measurement (ISO type), which was subjected to various measurements.

  As is clear from Table 1, the polylactic acid resin compositions obtained in Examples 1 to 3 had a short required time (molding cycle) required for molding and excellent moldability. Further, the obtained molded product was excellent in both heat resistance and impact resistance.

On the other hand, the polylactic acid-based resin composition obtained in Comparative Example 1 uses a polylactic acid-based resin having a D-form content exceeding 1.0 mol% and does not contain ethylene biscarboxylic amide. The cycle was long, resulting in poor moldability. Since the polylactic acid resin composition obtained in Comparative Example 2 did not contain an organic sulfonic acid metal salt, the molding cycle was long and the moldability was poor. Since the polylactic acid resin composition obtained in Comparative Example 3 did not contain talc, the molding cycle was long and the moldability was poor. Since the polylactic acid resin composition obtained in Comparative Example 4 used a polylactic acid resin having a D-form content exceeding 1.0 mol%, the molding cycle was long and the moldability was poor.

Claims (1)

A resin composition comprising a polylactic acid resin, an organic sulfonic acid metal salt, ethylenebiscarboxylic amide, and talc, wherein the polylactic acid resin has a D-form content of 1.0 mol% or less, 190 ° C., and a load of 21. The melt flow rate measured at 2N is 0.1 to 15 g / 10 min, and the organic sulfonic acid metal salt, ethylenebiscarboxylic amide and talc are 8 to 20 mass in total with respect to 100 parts by mass of the polylactic acid resin. A polylactic acid-based resin composition characterized by containing a part.