Dainippon Ink and Chemicals, Incorporated

Yasutoshi Kakizawa

Toshiki Shikata

Hiroshi Ebato

Satoshi Oya

Kosuke Arai

Masao Kamikura

Hideyuki Furuta

Yoji Imai

Morio Takada

The present invention provides a biodegradable expanded material having excellent expandability, moldability, impact resistance, heat resistance and storage stability. The present invention also provides a process for the preparation of the foregoing expanded material. The present invention further provides a laminate of a non-expanded material layer and an expanded material layer prepared from the foregoing expanded material which exhibits excellent impact resistance and heat resistance and an excellent transparency in the non-expanded material even after heat treatment so that a pattern printed on the inner side of the non-expanded material layer can be clearly viewed from the outside. A novel expanded material is provided made of a hydroxycarboxylic acid based polyester having a weight-average molecular weight of from 20,000 to 400,000 comprising as structural units a structural unit derived from hydroxycarboxylic acid, a structural unit derived from molecular weight increasing agent and/or a structural unit derived from polymerization catalyst deactivator.

Expanded material and laminate

The present invention provides a biodegradable material having excellent organic compatibility, moldability, mechanical properties, biodegradability and storage stability which can be used as bone substitute material, material for osteosynthesis, bone filling material, dental material, material having controlled release of chemical, material having controlled release of physiologically active compound or the like and a process for the preparation thereof. A novel biodegradable material is provided, comprising as essential components a lactic acid-based polymer (A) consisting of structural units (a) derived from lactic acid components and polyester structural units (b) derived from dicarboxylic acid components and diol components, the weight ratio of (a)/(b) being from 98/2 to 20/80, and a calcium phosphate-based compound (B), wherein the weight ratio of (A)/(B) is from 99/1 to 30/70. A process for the preparation of such a biodegradable material is also provided.

Biodegradable material and process for the preparation thereof

The present invention provides a process for the preparation of a lactic acid-based polyester having an excellent moldability, storage stability and biodegradability which has a less residual lactide left therein and is less susceptible to decomposition of lactic acid-based polyester and attachment of sublimed lactide to the molding apparatus, etc. at the devolatilization step and molding step after the polymerization reaction of lactic acid-based polyester. In the present invention, an organic chelating agent is added to a lactic acid-based polyester to deactivate the esterification catalyst used in the preparation of the lactic acid-based polyester, making it possible to inhibit the decomposition of lactic acid-based polyester at the devolatilizing process and molding process after polymerization reaction. Accordingly, a process for the preparation of a lactic acid-based polyester useful as a packaging material such as film and sheet having a high molecular weight, a high heat resistance, good mechanical properties and excellent moldability, storage stability and biodegradability can be provided.

Process for the preparation of lactic acid-based polyester

The present invention provides a process for the preparation of a biodegradable lactic acid-based polyester composition excellent in thermal stability, storage stability, flexibility, heat resistance, mechanical and physical properties and moldability which comprises kneading a lactic acid-based polyester and a polyester consisting of dicarboxylic acid component(s) and diol component(s) with a chelating agent, an acidic phosphoric acid ester, a molecular weight increasing agent, etc., and then devolatizing the kneaded mixture. The present invention also provides a molding process of the foregoing lactic acid-based polyester composition. A novel process for the preparation of a lactic acid-based polyester composition is provided, which comprises melt-kneading a lactic acid-based polyester (A), a polyester (B) consisting of dicarboxylic acid component(s) and diol component(s) and a chelating agent and/or acidic phosphoric acid ester (C) in an amount such that the weight ratio (A)/(B is from 99/1 to 10/90 and the proportion of (C) is 0.001 to 5 parts by weight based on 100 parts by weight of the sum of (A) and (B). A novel process for molding a lactic acid-based polyester composition is also provided, which comprises kneading a lactic acid-based polyester (A) and a polyester (B) consisting of dicarboxylic acid component(s) and diol component(s) with a chelating agent and/or acidic phosphoric acid ester (C), and then molding the material.

The present invention provides a process for the continuous production of a biodegradable polyester polymer with an excellent quality useful in the field of medicine, coating material and packaging material by eliminating difficulty in uniform agitation and heat removal caused by the rise in the viscosity of reactants in the production of a high molecular biodegradable polyester polymer by ring-opening polymerization. In some detail, the present invention provides a process for the continuous production of a biodegradable polyester polymer having a melt viscosity of not more than 500,000 poise and a weight-average molecular weight of not less than 10,000, which comprises continuously supplying monomers or polymers selected from the group consisting of intermolecularly cyclized ester of hydroxycarboxylic acid, lactone, and polymer having hydroxyl group and/or ester bond into a continuous reaction apparatus equipped with a static mixer where the reactants are subjected to continuous polymerization reaction at a polymerization temperature of 125.degree. to 270.degree. C., a maximum system reaction pressure of 2 to 15 Kg/cm.sup.2 and a conversion (one pass) of not less than 85% in the presence or absence of solvent without coming into contact with oxygen and water in the atmosphere, and then subjected to devolatilization to remove and recover residual monomers and solvent for reuse.

Process for the continuous production of biodegradable polyester polymer

A process for producing a lactic acid-based copolyester by the ring-opening copolymerization and transesterification of a lactide (A) with an aromatic polyester (B) and/or an aliphatic polyester (C) in the presence of a ring-opening polymerization catalyst (D), and a packaging material comprising the lactic acid-based copolyester obtained by the process are disclosed. According to the present invention, a lactic acid-based degradable copolyester which has a sufficiently high molecular weight and satisfactory toughness and also has suitable rigidity, pliability, and transparency according to applications can be produced. Further, a general-purpose packaging material, e.g., a sheet or film, which comprises the lactic acid-based copolyester produced by the process and is excellent in formability, degradability, and transparency can also be produced.

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Chiba, Japan

Yasutoshi Kakizawa