JP2005200600A - Lactic acid-based polymer composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lactic acid-based polymer composition excellent in injection biaxially stretching blow-molding processability, and an injection biaxially stretched blow bottle obtained therefrom. <P>SOLUTION: This lactic acid-based polymer composition contains (A) 100 pts.wt. lactic acid polymer and (B) 0.1-10 pt.wt. crystalline inorganic compound containing ≥30% silicic acid (SiO<SB>2</SB>) component as a crystal-nucleating agent. The injection biaxially stretched blow bottle is obtained from the composition. Further, the method for producing the lactic acid-based polymer composition by a master batch method, and the master batch are also provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a lactic acid polymer composition. More specifically, the present invention relates to a lactic acid-based polymer composition that is well molded and decomposes in a natural environment after use, and an injection biaxially stretched blow bottle obtained from the composition.

  Conventionally, polystyrene, polyvinyl chloride, polypropylene, polyethylene terephthalate resin, and the like are used as materials for molded articles made of plastic. Some of the molded products produced from such resins are excellent in transparency, but if they are disposed of in an incorrect manner, the amount of dust is increased, and they are hardly decomposed in the natural environment. It remains in the ground semipermanently. On the other hand, polylactic acid or a copolymer of lactic acid and other hydroxycarboxylic acid has been developed as a biodegradable polymer of a thermoplastic resin. These resins are 100% biodegradable within a few months to one year in the body of an animal, and when placed in soil or seawater, they begin to degrade in a few weeks in a moist environment. It disappears over the years, and the degradation products have the property of becoming lactic acid, carbon dioxide and water that are harmless to the human body.

  Although these lactic acid-based polymer compositions are excellent in transparency and rigidity, they have the following problems when trying to mold an injection biaxially stretched blow bottle with heat resistance. When producing an injection biaxially stretched blow bottle with heat resistance, it is necessary to crystallize the mouth of the preform before stretch-blowing the injection-molded preform. However, since lactic acid polymers are inherently slow in crystallization speed, in order to improve this, a crystal nucleating agent effective for increasing the crystallization speed is added, but crystallization proceeds in a short time. If the prescription is used, the crystallization of the body part progresses during the preheating of the preform body part during stretching, and the stretchability deteriorates, so that the preheating temperature and the preheating time are extremely limited. Was.

Also, if the emphasis is on moldability at the time of stretching, and the prescription is such that crystallization does not progress during preheating of the body part, the lactic acid-based polymer takes a long time to crystallize in advance because the crystallization rate is slow There was a problem in terms of productivity.
JP 2001-354223 A Japanese Patent Application Laid-Open No. 08-244781

  The problem to be solved by the present invention is to obtain a lactic acid-based polymer composition and a bottle that are excellent in injection biaxial stretch blow molding processability and decompose in a natural environment after use.

The present invention relates to a lactic acid-based polymer containing 0.07 to 10 parts by weight of a crystalline inorganic compound (B) containing 30% or more of a silicic acid (SiO ₂ ) component with respect to 100 parts by weight of the lactic acid-based polymer (A). A composition (AA) is provided.

  The lactic acid polymer composition (AA) in which the inorganic compound (B) is at least one selected from talc, kaolin, clay, and silica is a preferred embodiment of the present invention.

  A lactic acid polymer composition (AA) in which the content of D-form in the lactic acid unit in the lactic acid polymer (A) is 8% or less is also a preferred embodiment of the present invention.

  The present invention further provides an injection biaxially stretched blow bottle comprising the lactic acid-based polymer composition (AA).

The present invention relates to a lactic acid polymer composition comprising 1.0 to 50 parts by weight of a crystalline inorganic compound (B) containing 30% or more of a silicic acid (SiO ₂ ) component with respect to 100 parts by weight of a lactic acid polymer (A). A method for producing the lactic acid polymer composition (AA) by diluting the product (AAA) with the lactic acid polymer (A) is provided.

The present invention further includes a master comprising 1.0 to 50 parts by weight of a crystalline inorganic compound (B) containing 30% or more of a silicic acid (SiO ₂ ) component with respect to 100 parts by weight of a lactic acid-based polymer (A). A lactic acid-based polymer composition (AAA) suitable for batch is provided.

  The present invention also provides a crystallinity of 5% or less when a lactic acid polymer having a crystallinity of 1% or less is heat-treated for 5 minutes at a glass transition temperature of 100 ° C. or less and a melting point of 120 ° C. or more and a melting point or less. A lactic acid-based polymer composition having a crystallinity of 15% or more when subjected to a heat treatment for 5 minutes is provided.

  INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a lactic acid polymer composition excellent in injection biaxial stretch blow molding processability and further having good decomposability, and an injection stretch blow bottle comprising the same.

  In the present invention, the lactic acid-based polymer (A) is a polyester having lactic acid as a main component, preferably containing 50% or more, particularly preferably 75% or more of lactic acid, and the number of carbons other than lactic acid as other components. It consists of 2-10 aliphatic hydroxycarboxylic acids, aliphatic dicarboxylic acids, aliphatic diols, etc., and contains an aromatic compound such as terephthalic acid as long as the biodegradability of the polymer is not impaired. May be. Homopolymers, copolymers based on these, and mixtures thereof are included.

  As the lactic acid used for the raw material of the polymer, L-lactic acid, D-lactic acid, DL-lactic acid or a mixture thereof or lactide which is a cyclic dimer of lactic acid can be used. The hydroxycarboxylic acids that can be used in combination with lactic acids are preferably hydroxycarboxylic acids other than lactic acid having 2 to 10 carbon atoms, specifically glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxyvaleric acid, 5-hydroxyvaleric acid, 6-hydroxycaproic acid, and the like can be suitably used. Further, cyclic ester intermediates of hydroxycarboxylic acid, for example, glycolide which is a dimer of glycolic acid and 6-hydroxycaproic acid A cyclic ester ε-caprolactone can also be used.

  The aliphatic dicarboxylic acid is preferably an aliphatic dicarboxylic acid having 2 to 30 carbon atoms, specifically, oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecane. Examples include diacid, dodecanedioic acid, phenylsuccinic acid, 1,4-phenylenediacetic acid and the like. These can be used alone or in combination of two or more.

As the aliphatic diol, an aliphatic diol having 2 to 30 carbon atoms is preferable. Specifically, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1 , 4-butanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, neopentyl glycol, polytetramethylene glycol, 1,4-cyclohexanedimethanol 1,4-benzenedimethanol and the like. These can be used alone or in combination of two or more.

  Hydroxycarboxylic acids other than lactic acid, aliphatic dicarboxylic acids, and aliphatic diols as raw materials can be used in various combinations so that the lactic acid content in the resulting copolymer and mixture is 50% or more.

  Lactic acid-based polymers can be obtained by direct dehydration polycondensation of the above raw materials, or ring-opening polymerization of the above cyclic dimers of milk and hydroxycarboxylic acids, such as lactide and glycolide, or cyclic ester intermediates such as ε-caprolactone. It is obtained by the method.

In the case of production by direct dehydration polycondensation, the raw materials lactic acid or lactic acids and hydroxycarboxylic acids, aliphatic dicarboxylic acids and aliphatic diols are preferably added in the presence of an organic solvent, particularly a phenyl ether solvent. Polymerization is performed by a method in which azeotropic dehydration condensation is carried out, and polymerization is performed by a method in which water is removed from a solvent distilled off by azeotropy, and the solvent is made substantially anhydrous, and returned to the reaction system. A molecular weight lactic acid polymer is obtained. The weight average molecular weight of the lactic acid-based polymer is preferably a high molecular weight within a range in which moldability is possible, more preferably 30,000 to 5,000,000, still more preferably 70,000 to 3,000,000, particularly preferably 100,000 or more. 1.5 million or less is preferable.

  In the present invention, the D-lactic acid content in the total lactic acid unit content in the lactic acid-based polymer is 8% or less, preferably 5% or less.

Inorganic compound and the inorganic compound (B) used in the present invention include silicic acid (SiO ₂₎ crystalline inorganic compound component containing 30% or more, more preferably silicate (SiO ₂₎ component 40% It is a crystalline inorganic compound. Specific examples thereof include talc, kaolin, clay, and silica. These may be used alone or in combination of two or more. Of these, talc is particularly preferable.

  The inorganic compound (B) shown in the present invention is a compound that promotes and improves the crystallization of a polymer, and specifically has a function of promoting the crystallization speed of a molded product that has been molded.

  The average particle size of the inorganic compound (B) is 0.1 μm to 50 μm, preferably 0.5 μm to 30 μm, and more preferably 1.0 μm to 20 μm.

  In the lactic acid polymer composition (AA) of the present invention, the content of the inorganic compound (B) is 0.07 to 10.0 parts by weight, preferably 0.08 to 10 parts per 100 parts by weight of the lactic acid polymer (A). 0.0 part by weight, and more preferably 0.09 to 9.0 parts by weight. The content is such that a lactic acid polymer having a crystallinity of 1% or less is heated for 5 minutes at a glass transition temperature of 100 ° C. or less for 5 minutes and a crystallinity of 5% or less and 120 ° C. or more and a melting point or less for 5 minutes. The optimum amount is selected as appropriate so that the subsequent crystallinity is 15% or more and the desired molding and workability are good.

  Unless otherwise specified, the crystallinity described in the present invention is a differential scanning calorimeter (DSC Pyris 1) manufactured by PerkinElmer, Inc. The value obtained by subtracting the absolute value of the heat-up crystallization calorie from the absolute value of the heat of crystal-melting when the temperature was raised to 0 ° C. was divided by 93.1 J / g of the theoretical heat of crystal melting of polylactic acid.

  Further, when the composition contains a component that crystal melts in a temperature range close to the temperature range where polylactic acid is heated and crystallized, the above method cannot accurately measure the heat of crystallization of polylactic acid. The crystallinity was determined by the line method (X-ray analyzer: Rigaku Electric Co., Ltd. RINT2500, Cu target, transmission method).

  In the present invention, a modifier such as a plasticizer, an antioxidant, or an ultraviolet absorber can be added as necessary. The addition amount can be appropriately selected depending on the desired physical properties.

  A known kneading technique can be applied to the mixing of the lactic acid polymer and the crystal nucleating agent. The lactic acid-based polymer composition according to the present invention is pelletized to be used for molding.

  A known method can be used as a method for molding the lactic acid-based polymer composition. Usually, after a crystal nucleating agent is mixed with a lactic acid polymer in powder form or pellet form by a ribbon blender or the like, the composition is extruded and pelletized by a twin screw extruder and used for molding. For example, (a) a method of supplying the pellets obtained by the above method to a molding machine, (b) melt-kneading while simultaneously feeding a crystal nucleating agent when melt-kneading pellets of a lactic acid polymer with a twin screw extruder (C) A lactic acid polymer composition (master batch) containing a crystal nucleating agent at a high concentration is once manufactured, and this lactic acid polymer composition is used as a master batch for modification. And a method of diluting and mixing the master batch with lactic acid polymer pellets as normal pellets and feeding them to a molding machine.

  When adopting the master batch method of the above (c), the dilution ratio of the master batch for modification varies depending on the concentration of the crystal nucleating agent in the master batch, but is usually 2 to 50 times, preferably 3 to 40 times, More preferably, it is 5 to 30 times. In this range, the crystal nucleating agent is uniformly dispersed and can be preferably used.

  As a lactic acid polymer composition (masterbatch) containing such a crystal nucleating agent at a high concentration, 1.0 to 50 parts by weight of the inorganic compound (B) with respect to 100 parts by weight of the lactic acid polymer (A), A lactic acid polymer composition (AAA) comprising 2.0 to 40 parts by weight, more preferably 5.0 to 30 parts by weight is preferred. A known kneading technique can also be applied to a known kneading of the master batch (AAA) and the lactic acid polymer (A).

  The pelletized composition promotes the crystallinity of the polymer in the pellet by heat treatment, improves heat resistance, prevents fusion of the pellets, and improves extrusion stability. A known molding machine can be used as it is, and molding can be performed by a known method.

  In order to form a bottle from the composition of the present invention, a publicly known method can be used. For example, a preform can be formed by an injection molding machine, and the mouth of this can be heated and crystallized, and then obtained by a stretch blow molding method.

  In the bottle of the present invention, a layer having functions such as antistatic property, antifogging property, tackiness, gas barrier property, adhesion and easy adhesion can be formed on the bottle surface by coating as necessary. For example, the antistatic layer can be formed by applying and drying an aqueous coating solution containing an antistatic agent on the surface of the bottle.

  The bottle made of the resin composition according to the present invention can be suitably used as other bottles for beverages.

  The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

In the present invention, various physical properties were measured and evaluated by the following methods.
(1) Crystallinity Unless otherwise specified, the temperature was raised from 0 ° C. to 200 ° C. using a differential scanning calorimeter (DSC Pyris 1) manufactured by Perkin Elmer under a nitrogen atmosphere at 10 ° C./min. The value obtained by subtracting the absolute value of the heat-up crystallization heat quantity from the absolute value of the heat of crystal fusion at the time was divided by 93.1 J / g of the theoretical heat of crystal fusion of polylactic acid. Further, when the composition contains a component that crystal melts in a temperature range close to the temperature range where polylactic acid is heated and crystallized, the crystallization heat quantity of polylactic acid cannot be accurately measured by the above-described method. X-ray analyzer (Rigaku Electric Co., Ltd. RINT2500)
, Cu target, permeation method).
(2) Shape of mouth at the time of biaxial stretch blow molding Evaluated by visual inspection, and the case where no deformation of the shape was observed was defined as “no deformation”.
(3) Stretchability of the bottle body at the time of biaxial stretch blow molding The case where the preform could be formed to the end without being broken during stretching was defined as “good”.

[Example 1]
Polylactic acid (A1) in Henschel mixer (H-440 (sold by Mitsui Chemicals), weight average molecular weight 210,000, L-form / D-form = 96/4, melting point 155 ° C.) 100 parts by weight, talc XE-7
0.6 parts by weight of 1 (manufactured by Fuji Talc Kogyo Co., Ltd.) was mixed to prepare a dry blend. Then, this dry blend was supplied to the same-direction biaxial rotary extruder set at 210 ° C. and having a screw diameter of 35 mmφ, and melt-kneaded to prepare pellets.

  Next, using the pellets obtained by the above-described method, an amorphous 500 cc bottle preform (weighing amount = about 32 g) was molded by an injection molding machine set at a cylinder temperature of 200 ° C.

  The crystallinity of the mouth portion of this preform was less than 1%. The mouth of this preform was heated at a surface temperature of 140 ° C. for 5 minutes. At this time, the crystallinity of the mouth was 15%.

  Subsequently, the preform body was heated at 80 ° C. within the stretchable temperature range for 1 minute, and then subjected to stretch blow molding. As a result, the mouth portion was not deformed and the body portion was stretched well. Sexually. After heating the preform body at 80 ° C. for 1 minute, the crystallinity before stretch blow molding was less than 1%.

[Example 2]
Except for changing the addition amount of 0.6 parts by weight of talc XE-71 in Example 1 to 1.0 parts by weight,
The same operation as in Example 1 was performed to obtain a preform.

  The crystallinity of the mouth portion of this preform was less than 1%. The mouth of this preform was heated at a surface temperature of 140 ° C. for 5 minutes. At this time, the crystallinity of the mouth of the preform was 20%.

  Subsequently, the preform body was heated at 80 ° C. within the stretchable temperature range for 1 minute, and then subjected to stretch blow molding. As a result, the mouth portion was not deformed and the body portion was stretched well. Sexually. After heating the preform body at 80 ° C. for 1 minute, the crystallinity before stretch blow molding was less than 1%.

[Example 3]
Except for changing the amount of addition of 0.6 parts by weight of talc XE-71 in Example 1 to 8.0 parts by weight,
The same operation as in Example 1 was performed to obtain a preform.

The crystallinity of the mouth portion of this preform was less than 1%. The mouth of this preform was heated at a surface temperature of 140 ° C. for 5 minutes. At this time, the crystallinity of the mouth of the preform was 30%.

  Subsequently, the preform body was heated at 80 ° C. within the stretchable temperature range for 1 minute, and then subjected to stretch blow molding. As a result, the mouth portion was not deformed and the body portion was stretched well. Sexually. After the preform body was heated at 80 ° C. for 1 minute, the crystallinity before stretch blow molding was 4%.

[Example 4]
100 parts by weight of polylactic acid (A1) of Example 2 was added to polylactic acid (A2) (H-400 (sold by Mitsui Chemicals), weight average molecular weight 200,000, L-form / D-form = 98.6 / 1.4. ) A preform was obtained in the same manner as in Example 2 except that the amount was changed to 100 parts by weight.

  The crystallinity of the mouth portion of this preform was less than 1%. The mouth of this preform was heated at a surface temperature of 140 ° C. for 5 minutes. At this time, the crystallinity of the mouth of the preform was 35%.

  Subsequently, the preform body was heated at 80 ° C. within the stretchable temperature range for 1 minute, and then subjected to stretch blow molding. As a result, the mouth portion was not deformed and the body portion was stretched well. Sexually. After the preform body was heated at 80 ° C. for 1 minute, the crystallinity before stretch blow molding was 4%.

[Example 5]
A preform was obtained in the same manner as in Example 1 except that the amount of addition of 1.0 part by weight of talc XE-71 in Example 4 was changed to 0.1 part by weight.

  The crystallinity of the mouth portion of this preform was less than 1%. The mouth of this preform was heated at a surface temperature of 140 ° C. for 5 minutes. At this time, the crystallinity of the mouth of the preform was 29%.

  Subsequently, the preform body was heated at 80 ° C. within the stretchable temperature range for 1 minute, and then subjected to stretch blow molding. As a result, the mouth portion was not deformed and the body portion was stretched well. Sexually. After heating the preform body at 80 ° C. for 1 minute, the crystallinity before stretch blow molding was less than 1%.

[Example 6]
The same operation as in Example 2 was conducted except that 100 parts by weight of polylactic acid (A1) in Example 2 was changed to 90 parts by weight of polylactic acid (A1) and 10 parts by weight of Bionore # 1001 (manufactured by Showa Polymer Co., Ltd.). Done to obtain a preform.

  The crystallinity of the mouth portion of this preform was less than 1%. The mouth of this preform was heated at a surface temperature of 140 ° C. for 5 minutes. At this time, the crystallinity of the mouth of the preform was 23%.

  Subsequently, the preform body was heated at 80 ° C. within the stretchable temperature range for 1 minute, and then subjected to stretch blow molding. As a result, the mouth portion was not deformed and the body portion was stretched well. Sexually. After heating the preform body at 80 ° C. for 1 minute, the crystallinity before stretch blow molding was less than 1%.

[Example 7]
Polylactic acid (A1) (H-440 (Mitsui Chemicals, Inc.), weight average molecular weight 210,000, L-form / D-form = 96/4, melting point 155 ° C.) 100 parts by weight in a Henschel mixer, talc XE-
A dry blend was prepared by mixing 10 parts by weight of 71 (Fuji Talc Kogyo Co., Ltd.). Thereafter, this dry blended product is supplied to a co-axial twin screw extruder having a screw diameter of 35 mmφ set at 210 ° C., melt kneaded to prepare a pellet, and a master batch pellet of talc XE-71 It was.

  Next, 10 parts by weight of the master batch pellets obtained by the above method and 90 parts by weight of polylactic acid (A1) were premixed in a pellet state and supplied to an injection molding machine set at a cylinder temperature of 200 ° C. A preform (weight per unit area = about 32 g) was molded.

The crystallinity of the mouth portion of this preform was less than 1%. The mouth of this preform was heated at a surface temperature of 140 ° C. for 5 minutes. The crystallinity of the mouth at this time was 17%.
Subsequently, the preform body was heated at 80 ° C. within the stretchable temperature range for 1 minute, and then subjected to stretch blow molding. As a result, the mouth portion was not deformed and the body portion was stretched well. Sexually. After heating the preform body at 80 ° C. for 1 minute, the crystallinity before stretch blow molding was less than 1%. That is, the same effect as in Example 1 was obtained.

[Comparative Example 1]
A preform was obtained in the same manner as in Example 1 except that the amount of talc XE-71 added in Example 1 was changed from 0.6 parts by weight to 0.05 parts by weight.

The crystallinity of the mouth portion of this preform was less than 1%. The mouth of this preform was heated at a surface temperature of 140 ° C. for 5 minutes. At this time, the crystallinity of the mouth of the preform was 8%. Subsequently, the preform body was heated at 80 ° C. within the stretchable temperature range for 1 minute and then stretch blow molded. As a result, the mouth was crushed during longitudinal stretching and the mouth was swollen during blow molding. Occurred and a good bottle was not obtained.
[Comparative Example 2]
A preform was obtained in the same manner as in Example 1 except that 1.0 part by weight of talc XE-71 in Example 4 was changed to 15 parts by weight.

  The crystallinity of the mouth portion of this preform was less than 1%. The mouth of this preform was heated at a surface temperature of 140 ° C. for 5 minutes. At this time, the crystallinity of the mouth of the preform was 45%.

Subsequently, the body part of this preform was heated at 80 ° C. within the stretch blowable temperature range for 1 minute and then stretch blow molded. As a result, the body part was broken during stretching and could not be molded. After the preform body was heated at 80 ° C. for 1 minute, the crystallinity before stretch blow molding was 25%.

Polylactic acid (A1): weight average molecular weight 210,000, L-form / D-form = 96/4, melting point 155 ° C. (Mitsui Chemicals, Inc., sales H-440)
Polylactic acid (A2): weight average molecular weight 200,000, L-form / D-form = 98.6 / 1.4, melting point 167 ° C. (Mitsui Chemicals, Inc., sales H-400)
Crystallinity A: Crystallinity of the mouth after heating the mouth of the injection-molded preform at 140 ° C. for 5 minutes Crystallinity B: Body after heating the mouth of the preform at 140 ° C. for 5 minutes Of the body after heating the part at 80 ° C for 1 minute

  According to the present invention, it is possible to provide a lactic acid polymer composition having excellent moldability and good degradability. Furthermore, according to the present invention, it is possible to provide an injection biaxial stretch blow having excellent moldability and productivity and good decomposability from the lactic acid-based polymer composition.

Claims (7)

A lactic acid polymer composition (AA) containing 0.07 to 10 parts by weight of a crystalline inorganic compound (B) containing 30% or more of a silicic acid (SiO ₂ ) component with respect to 100 parts by weight of the lactic acid polymer (A). The lactic acid polymer composition (AA) according to claim 1, wherein the inorganic compound (B) is at least one selected from talc, kaolin, clay, and silica. Content of D body in the lactic acid unit in lactic acid-type polymer (A) is 8% or less, The lactic acid-type polymer composition (AA) of Claims 1-2 characterized by the above-mentioned. An injection biaxially stretched bottle comprising the lactic acid-based polymer composition (AA) according to any one of claims 1 to 3. A resin composition (AAA) containing 100 to 50 parts by weight of a lactic acid polymer (A) and 1.0 to 50 parts by weight of a crystalline inorganic compound (B) containing 30% or more of a silicic acid (SiO ₂ ) component, The method to manufacture the lactic acid-type polymer composition (AA) described in Claims 1-3 by diluting with a polymer (A). Resin composition suitable for a masterbatch comprising 1.0 to 50 parts by weight of a crystalline inorganic compound (B) containing 30% or more of a silicic acid (SiO ₂ ) component with respect to 100 parts by weight of a lactic acid polymer (A) Things (AAA). Heating a lactic acid polymer having a crystallinity of 1% or less for 5 minutes at a glass transition temperature of 100 ° C. or less for 5 minutes and a crystallinity of 5% or less and 120 ° C. or more and a melting point or less for 5 minutes. Lactic acid-based polymer composition characterized by having a crystallinity of 15% or more when treated