JP2011148888A - Polylactic acid-based resin emulsion - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polylactic acid-based resin emulsion which allows a film, that is obtained by drying the polylactic acid-based resin emulsion, to have the water resistance bearing comparison with that of the conventional emulsion and which does not contain an organic solvent substantially. <P>SOLUTION: The polylactic acid-based resin emulsion contains a polylactic acid-based resin (L) and a plasticizer (A) and water and satisfies that: (1) the content of the plasticizer (A) is 1-40 wt.% of the weight of the polylactic acid-based resin (L); (2) the content of a volatile organic solvent is ≤100 ppm; and (3) the surface tension of the dried film, which is obtained by drying the polylactic acid-based resin emulsion at 180°C for 3 hours and has 0.2±0.1 mm thickness, is 20-60 mN/m. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a polylactic acid resin emulsion. More specifically, the present invention relates to a polylactic acid resin emulsion substantially free of an organic solvent.

  Since polylactic acid is manufactured from straight plant-derived raw materials, it is known as a plastic with a low environmental impact, and therefore polylactic acid emulsions are being studied in order to develop polylactic acid into coating agents and adhesives. (For example, Patent Documents 1 and 2). However, the conventional polylactic acid emulsion needs to be made into an organic solvent solution at the time of dispersion when producing the emulsion, and since this organic solvent remains, it is not sufficient in terms of environmental burden and production cost.

JP 2004-204219 A JP 2001-11294 A

  The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a coating film obtained by drying with a water resistance comparable to that of a conventional film and containing substantially no organic solvent. The object is to provide a lactic acid resin emulsion.

As a result of intensive studies to achieve the above object, the present inventors have reached the present invention. That is, the present invention comprises a polylactic acid resin emulsion comprising a polylactic acid resin (L), a plasticizer (A) and water and satisfying the following (1) to (3);
(1) The content of the plasticizer (A) is 1 to 40% by weight based on the weight of the polylactic acid resin (L);
(2) The content of the volatile organic solvent is 100 ppm or less;
(3) The surface tension of a dry film having a film thickness of 0.2 ± 0.1 mm obtained by drying the polylactic acid resin emulsion at 180 ° C. for 3 hours is 20 to 60 mN / m.
And a polylactic acid resin (L) and a plasticizer (A), or a polylactic acid resin (L), a plasticizer (A) and a surfactant (S) under a temperature condition of 80 to 160 ° C. It is a manufacturing method of the polylactic acid-type resin emulsion in any one of Claims 1-3 disperse | distributing in water using B), without using an organic solvent.

By using the polylactic acid resin emulsion of the present invention, it is possible to obtain a polylactic acid resin film having a low hydrophilicity and excellent water resistance. Moreover, since the polylactic acid-based resin emulsion of the present invention does not substantially contain an organic solvent, it is possible to provide a polylactic acid-based resin emulsion having a low environmental load and excellent cost performance.

The polylactic acid resin (L) in the present invention includes a copolymer containing 50% by weight or more of polylactic acid and a lactic acid component.
Examples of the copolymer containing 50% by weight or more of the lactic acid component include a copolymer of lactic acid and another oxycarboxylic acid, a copolymer of lactic acid, a polyhydric alcohol, and a polybasic acid. Polylactic acid-type resin (L) may be used independently and may use 2 or more types together.

  Examples of lactic acid used in the production of the polylactic acid resin (L) include L-lactic acid, D-lactic acid, DL-lactic acid, and lactide which is a cyclic dimer of lactic acid.

Specific examples of components and production methods other than lactic acid used in the production of the polylactic acid resin (L) include those described in the following patent documents (1) to (5).
(1) US Pat. No. 5,310,865 (method of direct dehydration polycondensation using lactic acid or a mixture of lactic acid and aliphatic oxycarboxylic acid as a raw material)
(2) U.S. Pat. No. 2,758,987 [ring-opening polymerization method for melt polymerization of lactic acid cyclic dimer (lactide)]
(3) US Pat. No. 4,057,537 (ring-opening polymerization method in which a cyclic dimer of lactic acid and aliphatic oxycarboxylic acid, for example, lactide, glycolide and ε-caprolactone is melt-polymerized in the presence of a catalyst)
(4) US Pat. No. 5,428,126 (Method of direct dehydration polycondensation of a mixture of lactic acid, aliphatic dihydric alcohol and aliphatic dibasic acid)
(5) European Patent Publication No. 071880A2 (a method of condensing a polymer of polylactic acid, an aliphatic dihydric alcohol and an aliphatic dibasic acid in the presence of an organic solvent).

  The production method of the polylactic acid-based resin (L) is not particularly limited, and in addition to the above method, at least a part of the steps when producing a polyester polymer by performing dehydration polycondensation reaction of lactic acid in the presence of a catalyst. The solid phase polymerization may be carried out in the presence of a small amount of an aliphatic polyhydric alcohol such as trimethylolpropane and glycerin, an aliphatic polybasic acid such as butanetetracarboxylic acid, and a polyhydric alcohol such as polysaccharide. It may be polymerized, and the molecular weight may be increased by using a binder (polymer chain extender) such as a diisocyanate compound, or like bis (t-butylperoxyisopropyl) benzene and dicumyl peroxide. You may bridge | crosslink with a proper peroxide.

  Polylactic acid can also be obtained from the market. For example, “Lacia H280” [manufactured by Mitsui Chemicals], “Lacia H440” [manufactured by Mitsui Chemicals], “Lacia H400” [Mitsui Chemicals, Inc. ) Made] and the like.

  The number average molecular weight (hereinafter abbreviated as Mn) and the molecular weight distribution of the polylactic acid-based resin (L) are not particularly limited as long as they can be substantially molded, but Mn is 1,000 to 100,000. It is preferably 1,500 to 80,000, particularly preferably 2,000 to 50,000. When Mn is 1,000 or more, the water resistance of the molded product obtained by applying the emulsion is good, and when it is 100,000 or less, the melt viscosity of the resin is low and the productivity is good.

When the polylactic acid resin emulsion of the present invention contains a plasticizer (A), the polylactic acid resin (L) is plasticized to improve the dispersibility in water and increase the productivity. By appropriately selecting the type and amount of (A), the surface tension of the film obtained by drying the polylactic acid resin emulsion can be controlled.
The plasticizer (A) may be any plasticizer with respect to the polylactic acid resin (L). Known plasticizers (Japanese Patent Application Laid-Open Nos. 2004-83931, 11-35808, and 2007-246707) may be used. Etc.) can be used. Specifically, ester plasticizers (dioctyl phthalate, dibutyl sebacate, etc.), ether ester plasticizers (polyethylene glycol adipic acid, triethylene glycol diacetate, glycerin ethylene oxide addition acetylated product, etc.), rosin modified products, Examples include polyalkylene oxide metal salts.
Of these, ether ester plasticizers are preferred from the viewpoint of ease of control of surface tension of polylactic acid resin emulsion and productivity, and glycerin ethylene oxide addition acetylated product is more preferred.

  The content of the plasticizer (A) is usually 1 to 40% by weight, preferably 1.5 to 20% by weight, more preferably 2 to 10% by weight, based on the solid content weight of the polylactic acid resin emulsion. When the content is less than 1% by weight, the productivity of the emulsion becomes poor, and when it exceeds 40% by weight, the content of the polylactic acid component in the emulsion is lowered and the environmental load is increased.

In the present invention, a surfactant (S) may be further added for the purpose of improving the dispersion stability of the emulsion. The surfactant (S) to be used as necessary is a known surfactant, for example, a surfactant described in JP-A-2004-124059 [nonionic surfactant (polyvinyl alcohol and polylactide polyethylene glycol blocked product, etc.) , Anionic surfactants (such as polycarboxylates and polysulfonates) and cationic surfactants (such as primary amine salts and secondary amine salts)] can be used.
From the viewpoint of dispersion stability, polylactide polyethylene glycol blocked products and polycarboxylates are preferred.

  The content of the surfactant (S) is preferably 0.001 to 10% by weight, more preferably 0.005 to 5% by weight, and particularly preferably 0.000% by weight based on the weight of the solid content of the polylactic acid resin emulsion. 01 to 3% by weight. Within this range, the dispersion stability of the polylactic acid resin emulsion can be further easily improved.

  If necessary, the polylactic acid resin emulsion of the present invention may further contain a thermoplastic resin, a crosslinking agent, a pigment, a pigment dispersant, a viscosity modifier, an antifoaming agent, an antiseptic, a deterioration preventing agent, a stabilizer, an antifreezing agent, and the like. It can contain 1 type (s) or 2 or more types.

  Examples of the thermoplastic resin include polyurethane resin, acrylic resin, olefin resin, polyether resin, and polyester resin. The content of the thermoplastic resin is usually 0 to 50% by weight, preferably 0.1 to 30% by weight, based on the solid content weight of the polylactic acid resin emulsion.

Examples of the crosslinking agent include water-soluble or water-dispersible amino resins, water-soluble or water-dispersible carbodiimides, water-soluble or water-dispersible polyepoxides, water-soluble or water-dispersible blocked polyisocyanate compounds, and polyethylene urea. It is done.
The content of the crosslinking agent is usually 0 to 30% by weight, preferably 0.1 to 20% by weight, based on the solid content weight of the polyurethane resin emulsion.

  Examples of the pigment include inorganic pigments having a solubility in water of 1 or less (for example, white pigment, black pigment, gray pigment, red pigment, brown pigment, yellow pigment, green pigment, blue pigment, purple pigment and metallic pigment) and organic pigments ( For example, natural organic pigment synthetic organic pigments, nitroso pigments, nitro pigments, pigment dye-type azo pigments, azo lakes made from water-soluble dyes, azo lakes made from poorly soluble dyes, lakes made from basic dyes, lakes made from acid dyes, xanthan lakes , Anthraquinone lake, pigments from vat dyes and phthalocyanine pigments). The content of the pigment is usually 50% by weight or less, preferably 30% by weight or less, based on the weight of the aqueous paint.

  Examples of the pigment dispersant include various surfactants [anionic, cationic, nonionic or amphoteric] and a polymeric emulsifying dispersant (Mn 1,000 to 20,000), preferably a polymeric emulsifying dispersion. It is an agent. The content of the pigment dispersant is usually 20% by weight or less, preferably 15% by weight or less, based on the weight of the pigment.

  As a viscosity modifier, a thickener, for example, an inorganic viscosity modifier (such as sodium silicate or bentonite), a cellulose-based viscosity modifier (such as methylcellulose, carboxymethylcellulose, and hydroxymethylcellulose: Mn is usually 20,000 or more), Protein (casein, casein soda and ammonium caseinate) and acrylic (sodium polyacrylate and ammonium polyacrylate: Mn is usually 20,000 or more), and vinyl (polyvinyl alcohol, etc .: Mn is usually 20,000) Above).

  Examples of antifoaming agents include long-chain alcohols (such as octyl alcohol), sorbitan derivatives (such as sorbitan monooleate), and silicone-based antifoaming agents (such as polymethylsiloxane and polyether-modified silicone).

Examples of the preservative include organic nitrogen sulfur compound-based preservatives, organic sulfur halide-based preservatives, and the like.
Examples of deterioration inhibitors and stabilizers (such as UV absorbers and antioxidants) include hindered phenol-based, hindered amine-based, hydrazine-based, phosphorus-based, benzophenone-based or benzotriazole-based UV absorbers or antioxidants. It is done.
Examples of the antifreezing agent include ethylene glycol and propylene glycol.

  The content of the viscosity modifier, antifoaming agent, antiseptic, deterioration preventing agent, stabilizer and antifreezing agent is usually 5% by weight or less, preferably 3% by weight or less, based on the weight of the polylactic acid resin emulsion. is there.

The surface tension of the dried film having a film thickness of 0.2 ± 0.1 mm obtained by drying the polylactic acid resin emulsion of the present invention at 180 ° C. for 3 hours is usually 20 to 60 mN / m, preferably 30 to 58, more preferably. Is 40-55. If it is this range, the water resistance of the film | membrane obtained by drying a polylactic acid-type resin emulsion and the dispersion stability of a polylactic acid-type resin emulsion can be maintained favorable.
The surface tension can be measured according to JISK6768 (Plastic-film and sheet-wetting tension test method).

As will be described later, the polylactic acid resin emulsion of the present invention does not contain a volatile organic solvent when the polylactic acid resin (L) is dispersed in water. That is, the content of the volatile organic solvent in the polylactic acid resin emulsion of the present invention is usually 100 ppm or less, preferably 50 ppm or less, more preferably 20 ppm or less.
The volatile organic solvent in the present invention is a volatile organic compound defined in the Air Pollution Control Law, and corresponds to toluene, xylene, ethyl acetate and the like.
The content of the volatile organic solvent conforms to JISK5601-5-1 (Paint component test method-Part 5: Measurement of volatile organic compounds (VOC) in paint-Section 1: Gas chromatograph method). Can be measured.

The volume average particle diameter of the polylactic acid-based resin emulsion is preferably 20 to 10,000 nm, more preferably 30 to 5,000 nm, and particularly preferably 40 to 3,000 nm from the viewpoint of the fluidity of the emulsion.
In addition, a volume average particle diameter is based on JISZ8825-1: 2001, a laser-type particle size distribution measuring apparatus [For example, "LA-920", Horiba Ltd. (dispersion medium: ion-exchange water, measurement temperature) : 25 ° C.] and the like.

  The solid content concentration of the polylactic acid resin emulsion in the present invention is preferably 10 to 70% by weight, more preferably 15 to 60% by weight.

  The polylactic acid-based resin emulsion of the present invention is a process in which a polylactic acid-based resin (L), a plasticizer (A), and a surfactant (S) used as necessary are dispersed in water using a dispersing device (B). In the method, the polylactic acid resin (L) is softened under heating and dispersed to the desired fine particles.

  From the viewpoint of ease of handling in the step of dispersing the polylactic acid-based resin (L) in water, it is preferable that the shape of the polylactic acid-based resin (L) is a 0.2 to 500 mm granular or block shape, and its size Is more preferably 0.5 to 100 mm, particularly preferably 0.7 to 30 mm, and most preferably 1 to 10 mm.

As means for adjusting the shape of the polylactic acid-based resin (L) to a granular or block shape, for example, means such as cutting, pelletizing, granulating, or pulverizing can be used. This granular or block adjustment can be performed in water or in the absence of water.
For example, the method of processing the polylactic acid-type resin (L) rolled into the sheet form with a square pellet machine, and making it granule is illustrated.

  Examples of the dispersion apparatus (B) for dispersing the polylactic acid resin (L) of the present invention in water include a rotary dispersion mixing apparatus, an ultrasonic dispersion machine, and a kneading machine. From the viewpoints of temperature adjustment, supply of granular or block resin and dispersion capability, a rotary dispersion mixing apparatus is preferable.

  The main dispersion principle of the rotary dispersion mixing apparatus is to apply a shearing force to the processed material from the outside by rotation of the drive unit or the like to make fine particles and disperse them. Further, can be operated under normal pressure, reduced pressure or increased pressure.

  Examples of the rotary dispersion mixing apparatus include TK homomixer [manufactured by Primics Co., Ltd.], Claremix [manufactured by Mtechnics Co., Ltd.], Philmix [manufactured by Primix Co., Ltd.], Ultra Turrax [manufactured by IKA Corporation]. ], Ebara Milder [manufactured by Ebara Manufacturing Co., Ltd.], Cavitron (manufactured by Eurotech), biomixer [manufactured by Nippon Seiki Co., Ltd.], and the like.

  From the viewpoint of dispersion capability, the number of rotations when producing a polylactic acid resin emulsion using a rotary dispersion mixer is usually 100 to 30000 rpm, preferably 500 to 20000 rpm, and more preferably 1000 to 10,000 rpm.

In the present invention, in order to suppress the deterioration of the polylactic acid resin (L), it is preferable to disperse the polylactic acid resin (L) in water at a temperature lower than its melting point.
The temperature at which the polylactic acid-based resin (L) is dispersed in water is usually 80 to 180 ° C, preferably 90 to 170 ° C, more preferably 100 to 160 ° C, and particularly preferably 120 to 155 ° C.
If it is this range, degradation of the polylactic acid-type resin by hydrolysis etc. can be suppressed.

The weight ratio of the polylactic acid resin (L), the plasticizer (A), and the surfactant (S) used if necessary to the dispersion apparatus (A) and water is determined by the solidity of the target aqueous dispersion. The amount of water is preferably 20 to 900% by weight, more preferably 30 to 500% by weight, particularly preferably 50 based on the solid content of the polylactic acid resin emulsion. ~ 200% by weight. Within this range, the dispersion stability of the polylactic acid resin emulsion can be further easily improved.
In the dispersion treatment, an amount of water in which the solid content concentration of the polylactic acid-based resin emulsion becomes a desired value may be used within the range of the amount of water used, or the solid content concentration is obtained by adding water after the dispersion treatment. May be adjusted.

  The time for treating the polylactic acid resin (L) and water with the dispersing device (B) is usually 10 seconds to 10 hours from the viewpoint of preventing decomposition or deterioration of the polylactic acid resin (L) as a dispersion. More preferably, it is 1 minute to 3 hours, most preferably 10 to 60 minutes.

  The polylactic acid-based resin emulsion of the present invention comprises an aqueous coating composition, an aqueous adhesive composition, an aqueous fiber processing agent composition (a binder composition for pigment printing, a binder composition for nonwoven fabric, a sizing agent composition for reinforcing fibers, Antibacterial binder composition and artificial leather / synthetic leather raw material composition), aqueous coating composition (paper coating composition, floor polish composition, waterproof coating composition, water repellent coating composition, antifouling coating) Composition), water-absorbing polymer filler, water-based paper treating agent composition, water-based ink composition, etc., but it does not contain organic solvents and has high water resistance. It can be suitably used as a filler and an aqueous coating composition.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these. Hereinafter, the part means part by weight.
Production Example 1
A glass reactor equipped with a stirrer and a temperature controller was charged with 2000 parts of “Sanniks GE-200” [200 molecular weight glycerin ethylene oxide adduct: Sanyo Chemical Industries, Ltd.], and 3700 parts of acetic anhydride were reacted. While maintaining the temperature at 60 to 120 ° C., the mixture was gradually added over 5 hours with stirring. After further reaction at 120 ° C. for 5 hours, the pressure was gradually reduced, and the temperature was raised to 140 ° C. while distilling off excess acetic anhydride and by-product acetic acid, and the temperature was reduced under reduced pressure (30 mmHg) for 5 hours. Leaving 3100 parts of plasticizer (a). The acid value of the plasticizer (a) was 0.1.

Example 1
Polylactic acid 36 parts [Lacia H-400: manufactured by Mitsui Chemicals, Inc.], plasticizer (a) 2 parts, carboxymethylcellulose 1 part, polycarboxylate [Sunspear PS-8: Sanyo] Kasei Kogyo Co., Ltd.] 1 part and ion-exchanged water 60 parts were charged, and dispersion treatment was carried out at 5000 rpm for 20 minutes at 150 ° C. using CLEARMIX [M Technique Co., Ltd.] (X- 1) was obtained.

Comparative Example 1
36 parts of polylactic acid [Lacia H-400 manufactured by Mitsui Chemicals, Inc.], 1 part of carboxymethyl cellulose, 4 parts of polycarboxylate [Sunspear PS-8: manufactured by Sanyo Chemical Industries, Ltd.] Then, 50 parts of ethyl acetate and 100 parts of ion-exchanged water were charged, and polylactic acid emulsion (H-1) was obtained by carrying out dispersion treatment at 5000 rpm for 80 minutes at 50 ° C. using CLEARMIX [manufactured by M Technique Co., Ltd.]. It was.

Comparative Example 2
36 parts of polylactic acid (Lacia H-400 manufactured by Mitsui Chemicals, Inc.), 1 part of carboxymethyl cellulose, 1 part of polycarboxylate [Sunspear PS-8: manufactured by Sanyo Chemical Industries, Ltd.] Then, 100 parts of ion-exchanged water was charged, and a polylactic acid emulsion (H-2) was obtained by dispersing at 5000 rpm for 80 minutes at 50 ° C. using Claremix [M Technique Co., Ltd.].

  Volume average particle diameter (Dv) measured by the following methods for the polylactic acid emulsions (X-1), (H-1) and (H-2) of Example 1 and Comparative Examples 1 and 2, and the surface of the dried film The values of tension and organic solvent content are shown in Table 1.

<Volume average particle diameter (Dv)>
The sample was diluted with ion-exchanged water so that the solid content was 0.01% by weight, and then measured using a light scattering particle size distribution analyzer [ELS-8000 (manufactured by Otsuka Electronics Co., Ltd.)].

<Surface tension of dry film>
Pour a sample with a film thickness of 0.2 ± 0.1 mm after drying into a polypropylene mold of 10 cm × 20 cm × 1 cm, and dry it at 180 ° C. for 3 hours in a smooth air dryer. A film was obtained. The surface tension of the obtained dried film was measured using a test liquid mixture prepared in accordance with JISK6768 (plastic-film and sheet-wetting tension test method).

<Organic solvent content>
1 g of a sample was diluted with 8 g of ion-exchanged water and 1 g of a 5 wt% propylene glycol aqueous solution, and measured with a gas chromatograph [GC-2010 {manufactured by SHIMADZU Co., Ltd.}, column used: DB-WAX].

  The polylactic acid-based resin emulsion of the present invention comprises an aqueous coating composition, an aqueous adhesive composition, an aqueous fiber processing agent composition (a binder composition for pigment printing, a binder composition for nonwoven fabric, a sizing agent composition for reinforcing fibers, Antibacterial binder composition and artificial leather / synthetic leather raw material composition), aqueous coating composition (paper coating composition, floor polish composition, waterproof coating composition, water repellent coating composition, antifouling coating) Composition), water-absorbing polymer filler, water-based paper treating agent composition, water-based ink composition, etc., but it does not contain organic solvents and has high water resistance. It can be suitably used as a filler and an aqueous coating composition.

Claims (4)

A polylactic acid resin emulsion comprising a polylactic acid resin (L), a plasticizer (A) and water and satisfying the following (1) to (3);
(1) The content of the plasticizer (A) is 1 to 40% by weight based on the weight of the polylactic acid resin (L);
(2) The content of the volatile organic solvent is 100 ppm or less;
(3) The surface tension of a dry film having a film thickness of 0.2 ± 0.1 mm obtained by drying the polylactic acid resin emulsion at 180 ° C. for 3 hours is 20 to 60 mN / m.   The aqueous polylactic acid resin emulsion according to claim 1, further comprising a surfactant (S).   The polylactic acid resin emulsion according to claim 1 or 2, wherein the plasticizer (A) is an ether ester plasticizer.   Disperser (B) with polylactic acid resin (L) and plasticizer (A) or polylactic acid resin (L), plasticizer (A) and surfactant (S) at a temperature of 80 to 160 ° C. The method for producing a polylactic acid-based resin emulsion according to any one of claims 1 to 3, wherein the polylactic acid resin emulsion is dispersed in water without using an organic solvent.