JPH11166068A - Foamable particle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide foamable particles capable of giving molded foamed products having high foaming ratios and having been difficult to obtain by conventional techniques and capable of being foamed in molds to form the molded foamed products having arbitrary shapes. SOLUTION: The foamable particles comprise a resin composition comprising (A) an aliphatic polyester, (B) a dispersing agent and (C) a foaming agent, and has a function capable of being foamed, when heated in a temperature range of from the glass transition temperature (Tg) of the aliphatic polyester A to its melting point (Tm). Therein, the aliphatic polyester A and the dispersing agent B are contained in amounts of 30-70 wt.% and 70-30 wt.%., respectively, based on the total amount of the aliphatic polyester A and the dispersing agent B, and the dispersing agent C is contained in an amount of 1-30 pts.wt. per 100 pts.wt. of the total amount of the aliphatic polyester A and the dispersing agent B. The molded foam products have biodegradability, and can suitably be used as foamed (molded) products, disposable foam containers, and further substitutes for cushion materials, materials for civil engineering works and industries, materials for agriculture and fishery and materials for leisure, which are difficult to recover and reutilize.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to expandable particles containing an aliphatic polyester component. Furthermore, the present invention relates to a foam molded article obtained by foaming expandable particles.

[0002]

2. Description of the Related Art In general, foam materials are manufactured from resins such as polyethylene, polypropylene, and polystyrene, and are used in various fields by utilizing their properties such as light weight, heat insulation, soundproofing and cushioning.

[0003] However, these foamed materials are difficult to recover and reuse after use, and are hardly decomposed in a natural environment, so that they remain semi-permanently in the ground. In addition, abandoned plastics have caused problems such as spoiling the landscape and destroying the living environment of marine life.

On the other hand, lactic acid-based polymers such as polylactic acid and copolymers of lactic acid and other aliphatic hydroxycarboxylic acids, and aliphatic polyhydric alcohols and aliphatic polyhydric acids are examples of thermoplastic resins having biodegradability. Aliphatic polyesters derived from carboxylic acids have been developed. Some of these polymers are 100% biodegradable within months to one year in animals or, when placed in soil or seawater, begin to degrade within weeks in a humid environment, with about 1 It disappears in a few years from the year. Furthermore, the decomposition products have the property of becoming lactic acid, carbon dioxide, and water that are harmless to the human body.

[0005] In particular, polylactic acid has recently been used in large quantities at low cost by fermentation, and its decomposition rate in compost is high. Is expected.

The prior art relating to the foaming of aliphatic polyesters is disclosed, for example, in JP-A-4-304244, JP-A-5-140361, JP-A-5-170965, JP-A-5-170966, and JP-A-6-240037. ,
JP-A-6-287347, JP-A-6-287338
And Japanese Patent Application Laid-Open No. 9-263652.

[0007] These techniques mainly disclose a method for producing a foam using an extruder, the obtained foam, and a laminate of the foam. At present, there is no technology relating to foaming foamable particles mainly composed of a foam and a dispersant in a mold.

[0008]

DISCLOSURE OF THE INVENTION The present inventors have developed a foamed molded article having good expansion ratio at the time of mold foam molding, reproducibility of the mold shape of the molded article, and good adhesion between foamed particles by a simple operation. An object of the present invention is to develop an expandable particle containing an aliphatic polyester, which is suitable for production by the method described above.

[0009]

Means for Solving the Problems The present inventors have conducted intensive studies on foamed particles containing an aliphatic polyester as a component, and as a result, by mixing a dispersant and a foaming agent at a specific ratio with the aliphatic polyester, The inventors have found that the above-mentioned problems have been solved, and have completed the present invention. That is, the present invention is specified by the matters described in the following [1] to [10].

[1] An aliphatic polyester (A), a dispersant (B), and a foaming agent (C) are contained, and based on the total weight of the aliphatic polyester (A) and the dispersant (B). The aliphatic polyester (A) is 30 to 70% by weight,
And the dispersant (B) is 70 to 30% by weight, and based on the total 100 parts by weight of the aliphatic polyester (A) and the dispersant (B), the foaming agent (C) is 1 to 30 parts by weight. Foamable particles made of a resin composition and having a function of foaming when heated in a temperature range from the glass transition temperature (Tg) to the melting point (Tm) of the aliphatic polyester (A).

[2] The expandable particle according to [1], wherein the aliphatic polyester (A) is a lactic acid-based polymer. [3] The dispersant (B) is bran (fu), [1]
Or the expandable particles according to [2]. [4] The foaming agent (C) is a volatile foaming agent, [1].
To the expandable particles according to any one of [3] to [3]. [5] The foamable particle according to [4], wherein the volatile foaming agent is water.

[6] When the volatile foaming agent is at room temperature and normal pressure (25
C., 1 atm), is in the liquid phase, is at least the glass transition temperature (Tg) of the aliphatic polyester (A), and has a melting point (T
m) When heated in the following temperature range, normal pressure (1 atm)
The expandable particle according to [4], which has a function of performing a phase transition from a liquid phase to a gas phase.

[7] The aliphatic polyester (A) has an expansion ratio of 1.1 to 100 times when heated in a temperature range from the glass transition temperature (Tg) to the melting point (Tm). To the expandable particles according to any one of [6]. [8] The average particle diameter is 0.1 to 30 mm,
The expandable particles according to any one of [1] to [7].

[9] The foamable particles according to any one of [1] to [8] are mixed in a mold with the aliphatic polyester (A).
A foam molded article obtained by heating in a temperature range of not less than the glass transition temperature (Tg) and not more than the melting point (Tm). [10] A film is formed by heating the expandable particles according to any one of [1] to [8] in a temperature range from the glass transition temperature (Tg) to the melting point (Tm) of the aliphatic polyester (A). Foamed film and / or foamed sheet.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

[Aliphatic polyester (A)] In the present invention, the aliphatic polyester (A) is used as a monomer (monomer) with an aliphatic hydroxycarboxylic acid, an aliphatic polyhydric alcohol, or an aliphatic polybasic acid. Homopolymers, copolymers (random copolymers, block copolymers, alternating copolymers) obtained by polymerization in combination, and
And mixtures thereof. In the present invention, the aliphatic polyester (A) is usually preferably amorphous when extruded into pellets. When heat resistance is required for the foamed molded product, it is preferable that the material be amorphous when extruded into pellets and have a high glass transition temperature or a high melting point and be crystalline. Such polymers include lactic acid-based polymers.

[Lactic acid-based polymer] Here, the lactic acid-based polymer includes a polymer containing 50% by weight or more of a lactic acid component in terms of the weight of a monomer to be subjected to polymerization. Specific examples thereof include, for example, polylactic acid, a copolymer of lactic acid and another aliphatic hydroxycarboxylic acid, lactic acid, a copolymer of an aliphatic polyhydric alcohol and an aliphatic polybasic acid, a mixture of any combination of the following, And the like. Specific examples of lactic acid which is a raw material of polylactic acid include L-lactic acid, D-lactic acid, DL-lactic acid or a mixture thereof, or lactide which is a cyclic dimer of lactic acid. As described above, when the heat resistance of the foam molded article is required to be high (for example, 60 ° C. or higher), the obtained polylactic acid is preferably crystalline, and for that purpose, L-lactic acid and D-lactic acid are used. When lactic acid is used as a mixture, L-
It is necessary that either lactic acid or D-lactic acid is 75% by weight or more.

<Aliphatic hydroxycarboxylic acid> Specific examples of the aliphatic hydroxycarboxylic acids include glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid,
Examples thereof include 4-hydroxyvaleric acid, 5-hydroxyvaleric acid, and 6-hydroxycaproic acid, and a cyclic ester of an aliphatic hydroxycarboxylic acid, for example, glycolide or 6-hydroxyl which is a dimer of glycolic acid. Ε-caprolactone, which is a cyclic ester of caproic acid, can be mentioned. These can be used alone or in combination of two or more. In particular, lactic acid, 6-hydroxycaproic acid or ε-caprolactone is preferably used. These may be used alone or in combination of two or more.
Can be used.

<Aliphatic polyhydric alcohol> Specific examples of the aliphatic polyhydric alcohol include, for example, ethylene glycol, diethylene glycol, triethylene glycol,
Polyethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4
-Butanediol, 3-methyl-1,5-pentaneddiol, 1,6-hexanediol, 1,9-nonanediol, neopentyl glycol, polytetramethylene glycol, 1,4-cyclohexanedimethanol, 1,
4-benzenedimethanol and the like. They are,
They can be used alone or in combination of two or more.

<Aliphatic polybasic acid> Specific examples of the aliphatic dibasic acid include, for example, succinic acid, oxalic acid, malonic acid,
Glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecandioic acid, dodecandioic acid, phenylsuccinic acid, 1,4-phenylenediacetic acid, and the like. These can be used alone or in combination of two or more. Specific examples of the method for producing an aliphatic polyester used in the present invention include the above aliphatic hydroxycarboxylic acid, aliphatic dihydric alcohol,
A known and publicly-known method can be employed using an aliphatic dibasic acid. For example, in the case of polylactic acid, a method in which lactic acid or a mixture of lactic acid and an aliphatic hydroxycarboxylic acid is used as a raw material and directly subjected to dehydration polycondensation (for example, a production method described in US Pat. No. 5,310,865), A ring-opening polymerization method for melt-polymerizing a cyclic dimer (lactide) (for example, a production method disclosed in US Pat. No. 2,758,987), a cyclic dimer of lactic acid and an aliphatic hydroxycarboxylic acid,
For example, a ring-opening polymerization method in which lactide or glycolide and ε-caprolactone are melt-polymerized in the presence of a catalyst (for example, a production method disclosed in US Pat. No. 4,057,537), lactic acid, aliphatic divalent A method of directly dehydrating and polycondensing a mixture of an alcohol and an aliphatic dibasic acid (for example, a production method disclosed in US Pat. No. 5,428,126);
Examples thereof include 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 (for example, a production method disclosed in European Patent Publication No. 0712880). The production method is not particularly limited. Further, a small amount of an aliphatic polyhydric alcohol such as glycerin, an aliphatic polybasic acid such as butanetetracarboxylic acid, and a polyhydric alcohol such as a polysaccharide may coexist and be copolymerized. The molecular weight may be increased by using a binder (polymer chain extender) such as a compound. Bis (t-butylperoxyisopropyl)
It may be crosslinked with a peroxide such as benzene or dicumyl peroxide.

<Aliphatic polyester> The aliphatic polyester shown in the present invention is an aliphatic polyester produced from the above-mentioned aliphatic hydroxycarboxylic acid, aliphatic polyhydric alcohol and aliphatic polybasic acid. Polyethylene oxalate, polybutylene oxalate, polyneopentyl glycol oxalate, polyethylene succinate, polybutylene succinate, polylactic acid, polyglycolic acid, polyhydroxybutyric acid, polycaproic acid, β-hydroxybutyric acid and β-hydroxyvaleric acid And the like. Polylactic acid, polycaproic acid, polyethylene succinate, polybutylene succinate and the like, which can be supplied at relatively low cost, are particularly preferred.

These can be used alone or in combination of two or more. Aliphatic polyester (A)
The weight average molecular weight (Mw) and the molecular weight distribution of
There is no particular limitation as long as molding is possible. The molecular weight of the aliphatic polyester used in the present invention is not particularly limited as long as it shows substantially sufficient mechanical properties, but is generally preferably 1 to 500,000 in weight average molecular weight (Mw), 30,000 to 400,000 are more preferable, and 50,000 to 300,000 are still more preferable.

Generally, the weight average molecular weight (Mw) is 1
When the molecular weight is smaller than 10,000, the mechanical properties of the foamed molded product obtained by foaming are not sufficient, and when the molecular weight exceeds 500,000, handling becomes difficult or uneconomical.

[Dispersant (B)] In the present invention, a dispersant (B) is added to enhance the expandability of the expandable particles.
In the present invention, the dispersant (B) has a function of improving the uniformity of the dispersion state / mixing state of the foaming agent (C) with respect to the aliphatic polyester (A), and / or the aliphatic polyester (A) There is no particular limitation as long as it has a function of improving the upper limit of the weight of the foaming agent (C) that can be blended per unit weight. In the present invention, the dispersant (B) generally has a high affinity for the aliphatic polyester (A) and / or has a high affinity for the blowing agent (C). preferable.

In the present invention, the dispersant (B) is usually
When degradability is desired for the use of the expandable particles according to the present invention, those having degradability are preferred. In the present invention, when the dispersant (B) contains water in the foaming agent (C),
Usually, hydrophilic ones and water-containing ones are preferred. In the present invention, when the foaming agent (C) contains water, the dispersant (B) can be used in a wet state or a dry state. In the present invention, the dispersant (B) can be used in a dry state when the blowing agent (C) does not contain water.

Specific examples of the dispersant (B) include, for example,
The following <1> to <12> can be mentioned. <1> Grain derived product by-produced in the process of refining cereals such as polished rice and wheat / Brew derived product by-produced in the brewing / fermentation process;
Bran, bran, okara, germ, kasu, koji, etc. <2> cereal flour, etc .; corn flour, potato flour,
Sweet potato flour, wheat flour, barley flour, rice flour, soy flour, red bean flour, konjac flour, puffed grains (popcorn, puffed rice, etc.). <3> Processed foods such as cereals; Takano tofu, dried mashed potatoes, dried fu, dried noodles, yellow flour and the like. <4> vegetable fiber; seed fiber (such as cotton), fruit fiber,
Leaf fiber (hemp, jute, etc.), stem stem fiber, root fiber, dietary fiber, etc. <5>Cellulose; cellulose, carboxymethylcellulose (CMC), other cellulose derivatives, celluloid and derivatives thereof. <6> Plant-derived products obtained by processing plants / Plant-derived products by-produced in the process of processing plants; wood flour, sawdust,
Rice hulls, straw, wood pulp, corn fiber, cotton linter, hechima, coconut shell activated carbon, crushed materials such as used paper and used clothes, and lignin. <7>Starch; natural starch (corn starch, potato starch, wheat starch, etc.), high amylose starch, waxy starch, chemically and physically modified processed starch, cyclodextrin, dextrin, dextran and the like. <8> Polysaccharides other than celluloses and starches; pectins, chitosans, chitins, hemicelluloses, mannans and the like. <9> gums: gum arabic, guar gum, locust bean gum, tarakant gum, chicle and the like. <10> Dairy derivatives; casein, casein hydrochloride, rennet casein, sodium caseinate. <11> Leather bone derivatives; leather powder, gelatin, glue,
Collagen and the like. <12> Seaweeds and marine organisms; laver, agar, toroten, mozuku, hijiki, sponge, etc.

The above dispersants (B) such as <1> to <12> can be used alone or in combination of two or more, and are used in a wet state or a dry state. be able to. In the present invention, the amount of the dispersant (B) used is in the range of 30 to 70% by weight based on the total weight of the aliphatic polyester (A) and the dispersant (B). 3
If the amount is less than 0% by weight, the foaming property may not be sufficient, and if it exceeds 70% by weight, the adhesion between particles during mold foam molding may be insufficient.

[Type of foaming agent (C)] In the present invention,
Known and publicly used foaming agents (C) can be suitably used. For example, "MARUZEN High Polymer Dictionary-Concise Encyclopedia of
Polymer Science and Engin
eering (Kroschwitz, edited by Tatsuta Mita, Maruzen, Tokyo, 1994) ”, pages 811 to 815, can be suitably used. All the descriptions are incorporated as a part of the disclosure of the specification of the present application by explicitly citing the cited documents and the cited range, and by referring to the explicitly cited ranges, the matters or disclosures described in the specification of the present application are all Matters or disclosures that can be directly and uniquely derived by the trader. The blowing agent (C) includes an inert gas, a chemical blowing agent that generates an inert gas when decomposed, a hydrocarbon having 3 to 5 carbon atoms or a chlorinated hydrocarbon, fluorocarbons, fluorocarbons, water, nitrogen, LPG, LNG,
Includes low boiling organic liquids, carbon dioxide, inert gases, ammonia and the like. Further, in accordance with the regulations of the Montreal Protocol concerning the regulation of chlorofluorocarbons for protecting the ozone layer, a new or known / publicly-used foaming agent which meets environmental regulation standards and a foaming technique using the same can be suitably used.

Chemical foaming agent Specific examples of the chemical foaming agent include sodium hydrogen carbonate,
Dinitrosopentamethylenetetramine, sulfonylhydrazide, azodicarbonamide, p-toluenesulfonylsemicarbazide, 5-phenyltetrazole, diisopropylhydrazodicarboxylase, 5-phenyl-
3,6-dihydro-1,3,4-oxadiazine-2
-One, sodium borohydride and the like.

Physical Blowing Agent (Volatile Blowing Agent) In the present invention, the blowing agent (C) is generally preferably a physical blowing agent, that is, a volatile blowing agent. In the present invention, the volatile foaming agent has a glass transition temperature (Tg) or higher and a melting point (Tg) of the aliphatic polyester (A).
m) Those having a function of performing a phase transition from a liquid phase to a gas phase when heated in the following temperature range. In the present invention, the volatile foaming agent is generally used at room temperature and normal pressure (25
C., 1 atm), is in the liquid phase, is at least the glass transition temperature (Tg) of the aliphatic polyester (A), and has a melting point (T
m) Those having a function of performing a phase transition from a liquid phase to a gas phase when heated in the following temperature range are preferable. In the present invention, even when the volatile foaming agent is in a gaseous phase at normal temperature and normal pressure (25 ° C., 1 atm), it is compressed or simultaneously cooled to be in a liquid state, and is used in a pressure-resistant container or an insulated container. A low-boiling gas used as the filled liquefied gas is also preferable. Specific examples of the volatile foaming agent include, for example, <1> inert compound foaming agent, <2>
Aliphatic hydrocarbon-based blowing agents, <3> halogenated hydrocarbon-based blowing agents, and the like. In the present invention, as the foaming agent (C), generally, carbon dioxide gas and water, which are volatile foaming agents having both safety and economy, are particularly preferable.

<1> Inactive Compound Blowing Agent Specific examples of the inert compound blowing agent include nitrogen,
Examples include carbon dioxide gas, argon, and water.

<2> Aliphatic Hydrocarbon Blowing Agent Specific examples of the aliphatic hydrocarbon blowing agent include ethane, propane, butane, ethylene, propylene, petroleum ether, pentanes (n-pentane, 2, 2-dimethylpropane, 1-pentene, cyclopentane, etc.), hexanes (n-hexane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, cyclohexane, etc.), heptane (n-heptane, , 2-dimethylpentane, 2,4-dimethylpentane, 3-ethylpentane, 1-heptene, etc.), toluene, trichloromethane,
Examples thereof include tetrachloromethane, trichlorofluoromethane, methanol, 2-propanol, isopropyl ether, and methyl ethyl ketone.

<3> Halogenated Hydrocarbon Blowing Agent Preferred specific examples of the halogenated hydrocarbon-based blowing agent include, for example, halogenated hydrocarbons having 2 to 6 carbon atoms, and more specifically, Examples include methyl chloride, dichloroethane, chloroform, fluoromethane, difluoromethane, trifluoroethane, chlorotrifluoromethane, dichlorodifluoromethane, fluorochloroethane, dichlorotetrafluoroethane, and the like. Specific examples of fluorocarbons include, for example, Freon (R-11, R-12), and alternative Freon (R-134).
a), CFC-11, CFC-12, CFC-113,
CFC series Freon (Freon) such as CFC-114.

[Addition amount of foaming agent (C)] In the present invention, the addition amount of the foaming agent (C) is not particularly limited as long as it is suitable. In the present invention, the amount of the foaming agent (C) to be added varies depending on the desired expansion ratio and foaming agent at the time of mold foam molding, but generally, the aliphatic polyester (A) is used.
With respect to 100 parts by weight of the mixture of
30 parts by weight is preferable, 3 to 27 parts by weight is more preferable, and 5 to 25 parts by weight is further preferable. In general, if the amount is less than 1 part by weight, foaming tends to be lost or uneven. If the amount is more than 30 parts by weight, not only the effect of excessive addition but also poor appearance and uneven cell diameter are obtained. In some cases.

[Expandable Particle] The shape of the expandable particle is not particularly limited, but the particle diameter (average particle diameter) is 0.1 to 30 m.
m is preferred. The particle size is appropriately selected according to conditions such as a foaming method and a mold shape. For example, in the case of mold foaming, a relatively small particle size is preferable when foaming is performed in a small mold, and a relatively large particle size is preferable when foaming is performed in a large mold. The shape of the expandable particles is not particularly limited, but preferred specific examples include, for example, a spherical shape and a spheroidal shape. Here, “particles” include, for example,
It also includes polymer emulsions, latex, and microspheres constituting a polymer suspension. In order to express the adhesiveness between the particles when the expandable particles are foamed by heating, usually, the aliphatic polyester (A) component in the expandable particles is preferably in an amorphous state.

[Additives] In the present invention, the purpose of the present invention is to improve the expandability and the physical properties of the foam (for example, to improve the foamability, the flexibility of the foam, the tensile strength, the heat resistance, the weather resistance, etc.). Various additives (nucleating agent, plasticizer, antioxidant,
UV absorbers, heat stabilizers, flame retardants, internal release agents, inorganic additives, antistatic agents, surface wetting improvers, incineration aids, lubricants such as pigments) and the like can be added. For example, specific examples of the nucleating agent include titanium oxide, talc, kaolin, clay, calcium silicate, silica, sodium citrate, calcium carbonate, diatomaceous earth, calcined perlite, zeolite, bentonite, glass, limestone, calcium sulfate, aluminum oxide, Examples include titanium oxide, magnesium carbonate, sodium carbonate, and ferric carbonate. The addition amount of the nucleating agent is preferably 0.01 to 10 parts by weight, more preferably 0.03 to 5 parts by weight, based on 100 parts by weight of the total of the aliphatic polyester (A) and the dispersant (B). 0.05-3
Part by weight is more preferred. When the addition amount is more than 10 parts by weight, voids are generated in the obtained foam, the foaming agent escapes from the foam surface, and a good molded product may not be obtained.

[Production Method of Expandable Particles] The production method of the expandable particles used in the present invention includes, for example, aliphatic polyester (A), dispersant (B), foaming agent (C), and After uniformly mixing various additives using a high-speed stirrer or low-speed stirrer, melt-knead with a single-screw or multi-screw extruder with sufficient kneading capacity, and air-cool or (ice) water-cool the strands taken out through the nozzle at the tip. Method of quenching and pelletizing by the method of (1), or method of pelletizing in (ice) water, using a high-speed stirrer or a low-speed stirrer for the aliphatic polyester (A), dispersant (B), After the mixture is uniformly mixed using a single-screw or multi-screw extruder having sufficient kneading ability, the foaming agent (C) is injected (pressure) into an arbitrary portion of the cylinder in the process of melt-kneading.
A method of quenching and pelletizing the strand to be taken out by air cooling or (ice) water cooling, or a method of pelletizing in (ice) water, aliphatic polyester (A), dispersant (B), various types according to the purpose A method in which the additives are uniformly mixed using a high-speed stirrer or a low-speed stirrer, melt-kneaded with an extruder, and once the pellets are taken out in the same manner as described above, the foaming agent (C) is impregnated in a container such as an autoclave. Is mentioned.

The shape of the resin composition according to the present invention is usually
Pellets, rods and the like may be used. Further, the expandable particles may be unexpanded particles or pre-expanded particles, but are not particularly limited, but those which can substantially satisfy the adhesion of the expanded particles when heated and expanded in a mold. Must. In the latter case, the foaming ability when heated and foamed is 1.2 times, preferably 1.5 times or more, more preferably 2.0 times or more,
More preferably, it is 2.5 times or more, most preferably 3.0 times or more.

[Method for Producing a Foam] In the present invention, a free foam can be obtained by heating the expandable particles. Further, by foaming in a specific mold, it is possible to obtain a foam molded product that reproduces the shape of the mold. The foam can be manufactured by a publicly-known / public method. For example, "MARUZEN High Polymer Dictionary-Concise
Encyclopedia of Polymer
Science and Engineering (K
Roschwitz, translated by Tatsuta Mita, Maruzen, Tokyo, 1
994) ", pp. 811 to 815. All the descriptions are
By explicitly indicating the cited document and the cited reference range, the disclosure is incorporated as a part of the disclosure of the present application specification. Matters or disclosures that can be uniquely derived. Continuity, independence, size, and shape of the voids of the foam (including the concepts of the terms "bubble", "void", "microvoid", "cavity", "cell", etc.) Characteristics such as distribution, size uniformity, etc. can be controlled by appropriately setting foaming conditions according to the purpose. For example, a method of injecting CO ₂ or nitrogen gas into foamable particles in advance and imparting secondary foamability, filling a mold, blowing steam, heating and foaming, and then cooling to obtain a molded article. Is directly filled in a mold, heated and foamed, and then cooled to obtain a molded article. The temperature at the time of heating is in the range from Tg (glass transition temperature) to Tm (melting point) of the aliphatic polyester, and (Tg + 10)
C. to (Tm) .degree. C., preferably (Tg + 20) .degree.
m) ° C. is more preferable, and (Tg + 30) ° C. to (Tm) ° C.
Is more preferable, and (Tg + 40) ° C to (Tm) ° C is most preferable. If the temperature is lower than Tg, foaming may not occur, and if the temperature is higher than Tm, the molded body once foamed may re-shrink, which is not preferable. As the heating method,
There is no particular limitation as long as the energy required for heating and expanding the expandable particles is given by any method, and a known and publicly-known method can be used. For example, when obtaining a foamed molded article, after inserting the expandable particles into a mold that can be heated, the mold containing the expandable particles is placed in a heat medium or exposed to a temperature-controlled atmosphere. For example, a method of blowing a heated inert gas such as nitrogen, water vapor, or carbon dioxide gas into a mold can be used.

[Foam] The term "foam" used in the claims and specification of the present application includes many voids ("bubbles", "voids", "microvoids") inside a resin. , “Cavities”, “cells” and the like are included.) In the continuous phase of the resin having a small apparent density, a void phase (a void is continuous,
(Including independent ones), a resin structure having a two-phase structure or a multi-phase structure, such as a polymer having a cellular structure, a foamed polymer, an expanded polymer, a polymer foam, and a polymer This includes general structures recognized as structures such as foams, and also includes soft and hard structures.

When the foamed article obtained by subjecting the foamable particles according to the present invention to foam molding is used in the form of a foam, it has excellent cushioning properties, impact resistance, heat insulation properties, etc., so that it can be used for various packaging, packing materials, and building. And industrial heat insulating materials, furniture, automobile cushioning materials, interior materials, living goods, sports goods, health goods, agricultural materials, and the like. Depending on the application, it is desired that the vacuoles in the foam are in communication with adjacent vacuoles through pores (open cells), and when the individual vacuoles exist independently (closed cells). It may be desirable, and in some applications, either is acceptable. Foam molded body is 2 ~
From 3 times low foaming to 10 to 20 times medium foaming and 30 to 50 times (in some cases 30 to 100 times) high foaming. The main component of sheet and board-like foam,
Specific examples of so-called high foam applications include, for example, packaging and packaging, construction and civil engineering, vehicles and ships, industrial insulation,
Agriculture, forestry and fisheries, sports and miscellaneous goods, and the like.

[Synthetic Wood] In the present invention, the expandable particles may be a low-expanded foam falling within the category of synthetic wood. Here, "synthetic wood ([Artificia
lwoods]) "is a common name among those skilled in the art, and a formal definition has not yet been defined.
In Europe and the United States, "Structural foam products
what is called "foam]" substantially corresponds to this. That is, it refers to a plastic low-foamed product having a skin layer and an expansion ratio of about 1.1 to 4 times. Synthetic wood is a highly promising material from the standpoint of global wood shortage and environmental protection. Depending on the choice of molding method,
In terms of appearance, synthetic wood can also be manufactured that is difficult to distinguish from natural wood, and can be applied to high value-added applications such as furniture. Specific examples of uses of synthetic wood include, for example, cutting boards, sawboards, container pallets, concrete panels, and the like.

[Use] The foam obtained from the expandable particles of the present invention can also be used as a substitute for the use of a publicly known foam prior to the filing of the present invention. In particular, the foam of the present invention has biodegradability in soil, and is used for difficult-to-collect or disposable foam containers, cushioning (packaging) materials, materials for the civil engineering industry, materials for the agricultural and marine industries, and leisure goods. It can be suitably used as a substitute for a general-purpose resin foam.

General-purpose use The foam obtained from the expandable particles of the present invention can be used, for example, in a lunch box, tableware, a container for lunch and side dishes, a cup for cup ramen, and a vending machine for beverages as sold in convenience stores. Used cups, containers and trays for foodstuffs such as fresh fish, meat, fruits and vegetables, tofu, prepared foods, torobaco (fish box for fisheries) used in the fresh fish market, milk, yogurt, lactic acid bacteria drinks, etc. Containers for dairy products, containers for carbonated drinks and soft drinks, containers for liquor drinks such as beer and whiskey, cosmetic containers, detergent containers, bleach containers, cool boxes, flower pots, tapes, home appliances such as TVs and stereos Cushioning materials and packaging materials for transportation of products, cushioning materials for transportation of precision machines such as computers, printers and watches, cameras, glasses, microscopes, and telescopes Cushioning material for transportation of optical machinery, cushioning material for transportation of ceramic products such as glass and ceramics, loose cushioning material (easy packing material that can be packed at the site), light shielding material, heat insulating material ( Extrusion board, etc.), soundproofing / sound insulation (extrusion board, etc.), extruded foam sheet (polymer paper for food related applications, prepackaged. Mainly applied to food packaging and containers), foaming It can also be suitably used as a sheet obtained by bonding a non-foamed film to a sheet, a filter for passing through a sewage furnace, a net-like foam, a foamed product, and the like.

General Industrial Use and Recreational Use of the Foam The foam obtained from the expandable particles of the present invention can be used for general industrial use and leisure, including agriculture, fishing, forestry, industry, construction and civil engineering, and transportation. It can be suitably used for recreational applications including sports. For example, agricultural cold gauze, oil absorbent, soft ground reinforcement, artificial leather,
Suitable as floppy disk lining, sandbag bag, heat insulating material, soundproofing material, cushioning material, cushioning material for furniture such as bed / chair, cushioning material for floor, packaging material, binding material, non-slip material for muddy and snowy roads, etc. Can be used.

[0046]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the scope of the present invention. [Evaluation of Physical Properties] Weight average molecular weight (Mw), glass transition temperature (Tg) of aliphatic polyester in Production Examples and Examples,
The melting point (Tm), the shapeability of the foam, and the strength were measured by the following methods.

Weight Average Molecular Weight The weight average molecular weight of the lactic acid-based polymer can be determined by gel permeation chromatography (G
PC) under the following conditions. Apparatus: Shimadzu LC-IOAD Detector: Shimadzu RID-6A Column: Hitachi Chemical GL-S350DT-5, GL-S3
7ODT-5 Solvent: chloroform Concentration: 1% Injection volume: 20 μl Flow rate: 10 ml / min

Glass transition temperature (Tg), melting point (T
m) Differential scanning calorimeter (manufactured by Shimadzu Corporation, DSC-50)
The point at which the molded body changed to a rubbery state when the temperature of the molded body was raised at 10 ° C./min was defined as the glass transition point (Tg), and the peak of the melting peak was defined as the melting point (Tm).

The degree of crystallinity was measured by an X-ray diffractometer (Rint 1500, manufactured by Rigaku Corporation), and the ratio of the crystal peak area to the total area of the obtained chart was determined.

Shape Reproducibility The reproducibility of the mold shape of the foam molded article was visually observed. ○ ・ ・ ・ Good. △ ... Shape of corner part is not good. ×: defective.

Strength The following classification was performed for the strength of the foamed molded article.・ ・ ・: Strong. Δ: Slightly brittle. ×: brittle.

C. Examples and Comparative Examples [Production Example 1] <Production of Polymer A (Poly L-lactide)> 100 parts by weight of L-latatide and stannous octoate 0.1 part by weight.
01 parts and 0.03 parts of lauryl alcohol were sealed in a thick cylindrical stainless steel polymerization vessel equipped with a stirrer, degassed under vacuum for 2 hours, and then replaced with nitrogen gas. The mixture was heated at 200 ° C. for 3 hours with stirring under a nitrogen atmosphere. While maintaining the temperature as it was, the air was gradually degassed by a vacuum pump through an exhaust pipe and a glass receiver, and the pressure inside the reaction vessel was reduced to 3 mmHg. One hour after the start of degassing, the distillation of monomers and low-molecular-weight volatiles disappeared, so the inside of the vessel was replaced with nitrogen, the polymer was drawn out from the lower part of the vessel in the form of a strand, pelletized, and homopolymer of L-lactide (polymer A) was obtained. The yield was 78% and the weight average molecular weight Mw was 136,000.

[Production Example 2] <Production of polymer B (poly L-lactic acid)> In a 100-liter reactor equipped with a Dien-Stark trap, 10 kg of 90% L-lactic acid was added at 150 ° C / 5.
After distilling water while stirring at 0 mmHg for 3 hours, 6.2 g of tin powder was added, and the mixture was further heated at 150 ° C / 30 mmHg for 2 hours.
The mixture was oligomerized by stirring for an hour. 28.8 g of tin powder and 21.1 kg of diphenyl ether were added to this oligomer,
An azeotropic dehydration reaction at 150 ° C./35 mmHg was performed, and the distilled water and the solvent were separated by a water separator, and only the solvent was returned to the reactor. After 2 hours, the organic solvent to be returned to the reactor was passed through a column packed with 46 kg of molecular sieve 3A, and then returned to the reactor. The reaction was carried out at 150 ° C./35 mmHg for 40 hours, and the weight average molecular weight was 146,000. A solution of polylactic acid was obtained. Diphenyl ether 44 dehydrated in this solution
After adding kg and diluting, the mixture was cooled to 40 ° C., and the precipitated crystals were filtered, washed three times with 10 kg of n-hexane, and dried at 60 ° C./50 mmHg. 0.5 N of this powder
-Add 12 kg of HCl and 12 kg of ethanol, and add 35
After stirring at 1 ° C. for 1 hour, the mixture was filtered and dried at 60 ° C./50 mmHg. lkg (yield 85
%). The weight average molecular weight Mw of this polylactic acid (Polymer B) was 145,000.

[Production Example 3] <Production of polymer C (polybutylene succinate)>
50.5 g of 1,4-butanediol and 66.5 succinic acid
g to 293.0 g) Metal tin 2.02
g was added and heated and stirred at 130 ° C./140 mmHg for 7 hours while distilling water out of the system to oligomerize. to this,
Attach Dean-Stark trap, 140 ° C
After azeotropic dehydration for 8 hours at / 30 mmHg, a tube filled with 40 g of molecular sieve 3A was attached, and the distilled solvent was returned to the reactor through the molecular sieve tube, and stirred at 130 ° C / 17 mmHg for 40 hours. did. The reaction mass was dissolved in 600 ml of chloroform, added to 4 liters of acetone and reprecipitated, and then a solution of HCl in isopropyl alcohol (hereinafter abbreviated as IPA) (H
(Cl concentration 0.7 wt%) for 0.5 hour (three times), washed with IPA, and dried under reduced pressure at 60 ° C. for 6 hours to obtain polybutylene succinate (hereinafter abbreviated as PSB). The weight average molecular weight Mw of this polymer is 1
It was 18,000.

Example 1 10 kg of polylactic acid (Polymer A) as a lactic acid-based polymer and bran as a dispersant
10 kg was thoroughly mixed using a Henschel mixer,
The mixture was melt-kneaded with a screw extruder, and water was further injected as a foaming agent at a predetermined ratio [10 parts by weight / (100 parts by weight of a mixture of polylactic acid and bran (fu))] from the middle of the extruder. The strand coming out of the tip of the die was cooled by passing through a water tank. The resulting strand is cut with a pelletizer,
A pellet (expandable particles) having a particle size of 3 mm was obtained. A mold (length * width * height = 100 mm * 50 mm * 20) made of the expandable particles from a 2 mm-thick iron plate with an air hole.
mm), the foam was blown through hot air at 110 ° C. through an air hole to fuse the particles together, and then cooled.
The mold was opened, and the obtained foamed molded product was taken out, and its shapeability and strength were evaluated. The results are shown in Table 1.

[Examples 2 and 3 and Comparative Example 1]
3, and Comparative Example 1 are aliphatic polyester, dispersant,
The procedure was the same as in Example 1 except that the molding conditions during foam molding were changed. The results are shown in Table 1 [Table 1].

[0057]

[Table 1] [Legend] ND; cannot be evaluated

[0058]

By forming and processing the expandable particles according to the present invention, it is possible not only to obtain a foam having a high expansion ratio which was difficult to obtain by the conventional technique, but also to expand the foam in a mold. In this way, a foam molded article having an arbitrary shape can be obtained. The foam molded product has biodegradability and is difficult to collect and reuse, and is a foam (molded) body, a disposable foam container, a cushioning material, a material for the civil engineering industry, a material for the agriculture and fisheries industry, leisure. It can be suitably used as a substitute for a foam molded article used for an article.

The foamed product has at least the following excellent properties <1> to <7>. <1> It can be soft or hard. <2> Low thermal conductivity and good heat insulation (energy saving effect). <3> Degradable. <4> Excellent heat resistance and oil resistance. <5> Even when incinerated, harmful substances are hardly generated. <6> Non-toxic and odorless. <7> Excellent workability.

Continuation of the front page (51) Int.Cl. ⁶ Identification code FI B29K 105: 04 B29L 7:00 (72) Inventor Yasuhiro Kitahara 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Chemicals Co., Ltd. (72) Inventor Nakata Tomoyuki 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Pref. Mitsui Chemicals Co., Ltd. (72) Kazuhiko Suzuki 1190 Kasama-cho, Sakae-ku, Yokohama-shi Kanagawa pref. 1190 Mitsui Chemicals Co., Ltd.

Claims (10)

[Claims] Claims: 1. An aliphatic polyester (A), a dispersant (B), and a foaming agent (C), and based on the total weight of the aliphatic polyester (A) and the dispersant (B). The aliphatic polyester (A) is 30 to 70% by weight, and the dispersant (B) is 70 to 30% by weight, based on the total 100 parts by weight of the aliphatic polyester (A) and the dispersant (B). The foaming agent (C) comprises a resin composition containing 1 to 30 parts by weight, and functions to foam when heated in a temperature range from the glass transition temperature (Tg) to the melting point (Tm) of the aliphatic polyester (A). Expandable particles having the formula: 2. The expandable particle according to claim 1, wherein the aliphatic polyester (A) is a lactic acid-based polymer. 3. The dispersant (B) is bran (fu),
The expandable particles according to claim 1. 4. The blowing agent (C) is a volatile blowing agent.
The expandable particles according to claim 1. 5. The expandable particles according to claim 4, wherein the volatile blowing agent is water. 6. The volatile foaming agent is used at room temperature and normal pressure (25 ° C., 1
Atmospheric pressure) is a liquid phase, and when heated in a temperature range from the glass transition temperature (Tg) to the melting point (Tm) of the aliphatic polyester (A), the liquid phase at normal pressure (1 atm) The expandable particle according to claim 4, which has a function of performing a phase transition from a gas to a gas phase. 7. The expansion ratio of the aliphatic polyester (A) when heated in a temperature range of not less than the glass transition temperature (Tg) and not more than the melting point (Tm) is 1.1 to 100 times. 6. The expandable particle according to any one of 6. 8. The expandable particle according to claim 1, wherein the average particle diameter is 0.1 to 30 mm. 9. The expandable particle according to claim 1, which is heated in a mold in a temperature range from a glass transition temperature (Tg) to a melting point (Tm) of the aliphatic polyester (A). Foamed article obtained by 10. A film is formed by heating the expandable particles according to any one of claims 1 to 8 in a temperature range from the glass transition temperature (Tg) to the melting point (Tm) of the aliphatic polyester (A). Foamed film and / or foamed sheet.