Abstract: A biodegradable filament of polyglycolic acid resin having practical properties represented by high tensile strength and knot strength is produced. A polyglycolic acid resin having a residual monomer content of below 0.5 wt. % is melt-spun, quenched in a liquid bath of at most 10° C. and then stretched in a liquid bath of 60-83° C. to produce a polyglycolic acid resin filament having a tensile strength of at least 750 MPa and a knot strength of at least 600 MPa.

Abstract: An aromatic polyester resin molded product, including: a matrix of 99-70 wt. parts of an aromatic polyester resin, and a disperse phase of 1-30 wt. parts (providing a total of 100 wt. parts together with the aromatic polyester resin) of a polyglycolic acid resin present in the matrix, wherein the molded product exhibits an oxygen permeability in its thickness direction which is in a range of 55-85% of a minimum gas permeability P0 determined by formula (1) below (Nielsen's theoretical formula): P0=P1×?1/(1+(L/2W)×?2) ??(1), wherein L denotes a longer axis of the polyglycolic acid resin disperse phase; W denotes a shorter axis (thickness) of the polyglycolic acid resin disperse phase; P1 denotes an oxygen permeability of the aromatic polyester resin in an oriented and crystallized state; ?1 denotes a volumetric fraction of the aromatic polyester resin; and ?2 denotes a volumetric fraction of the polyglycolic acid resin.

Abstract: An aromatic polyester resin composition, comprising: a melt-kneaded product of 99-70 wt. parts of an aromatic polyester resin and 1-30 wt. parts (providing a total of 100 wt. parts together with the aromatic polyester resin) of a polyglycolic acid resin, wherein the aromatic polyester resin is an aromatic polyester resin polymerized with an antimony compound (catalyst), the polyglycolic acid resin is a polyglycolic acid resin obtained by ring-opening polymerization of glycolide, and the composition further contains a metal-deactivating agent in a proportion of 17-500 mol. % with respect to the antimony in the aromatic polyester resin. As a result, gas generation during the melt-processing of a composition obtained by adding a relatively small amount of polyglycolic acid resin to an aromatic polyester resin is effectively suppressed to provide an aromatic polyester resin composition with a good gas-barrier property.

Abstract: An aromatic polyester resin composition, comprising: a melt-kneaded product of 99-70 weight parts of an aromatic polyester resin and 1-30 wt. parts (providing a total of 100 wt. parts together with the aromatic polyester resin) of a polyglycolic acid resin, wherein the composition is characterized by a transesterification rate CTE (%) of 20-60% determined by formula (1) below based on a peak integration ratio of methylene group in polyglycolic acid appearing at ?4.87 ppm with reference to tetramethylsilane according to 1H-NMR measurement: CTE(%)=(1?I(B)/I(A))×100 ??(1), wherein I (A): a peak integration ratio of the methylene group of the polyglycolic acid main chain with respect to the alkylene group of the aromatic polyester main chain calculated from the components weight ratio; and I (B): a peak integration ratio of the methylene group of polyglycolic acid main chain to the alkylene group of the aromatic polyester main chain in the resin composition.

Abstract: A method of controlling a moisture resistance of polyglycolic acid resin, by controlling a total carboxyl group-source concentration including a contribution of residual glycolide. As a result, a moisture resistance governing the change of strength with time of the polyglycolic acid resin is controlled at a good accuracy.

Abstract: Polyglycolic acid and polylactic acid having a weight-average molecular weight of at most 50,000 are melt-kneaded in the presence of a thermal stabilizer to obtain a polyglycolic acid-based aliphatic polyester composition. The aliphatic polyester composition alleviates the too fast crystallizability of polyglycolic acid which has been problematic in forming or molding of polyglycolic acid alone or in combination with another thermoplastic resin, thus showing a crystallization speed which has been lowered and can be controlled in a wide range.

Abstract: There is provided a laminate sheet which is excellent in oxygen-barrier property and moisture resistance, biodegradable as a whole and therefore suitable as a base material for packaging materials, such as food containers. The laminate sheet is formed by laminating a water-containable and biodegradable polymer substrate sheet or a precursor thereof in a water-containing state with a layer of polyglycolic acid resin having a residual monomer content below 0.5 wt. % to form a laminate, and subjecting the laminate to bonding and forming under heat and pressure.

Abstract: There are provided a bottle which has a laminate structure including a glycolic acid polymer layer showing good gas-barrier property in addition to a principal resin layer and is yet provided with excellent recyclability, and also an efficient method of recycling the bottle. More specifically, a bottle having a laminate structure including at least one layer of glycolic acid polymer in addition to a principal resin layer, is obtained. After breaking the bottle, the broken pieces are washed with alkaline water, water or acidic water to remove the glycolic acid polymer layer, thereby recovering the principal resin.

Abstract: An aliphatic polyester resin composition of improved moisture resistance formed by adding a phosphoric or phosphorous acid ester having a basicity of at most 1.4 of a saturated aliphatic alcohol having 8-24 carbon atoms.

Abstract: A polyglycolic acid resin-based multilayer sheet is formed by laminating a biological polymer substrate sheet and a polyglycolic acid resin with each other via an aqueous adhesive layer. The multilayer sheet is formed of biodegradable materials as a whole and allows recovery of paper, etc. alone, as desired, by preferential decomposition of the resin, thus being suitable as a packaging material stock for food container, etc.

Abstract: A multilayer sheet made of a polyglycolic acid resin which is constructed by the fusion/lamination of a biodegradable resin layer on a base sheet of vegetable origin, characterized in that the biodegradable resin layer comprises one or more layers involving at least one polyglycolic acid resin layer and the layer fused with the base sheet is made of a biodegradable resin having a melt viscosity of 10 to 5.0×103 Pa·sec at a temperature of 240° C. and a shear speed of 122 sec?1 and a melting point of 235° C. or lower. Although the multilayer sheet has a lamination structure made of biodegradable materials with light environmental burden at disposal, it is excellent in oxygen-barrier properties and resistance to moisture transmission. Thus, it is appropriately usable as a food container material.

Abstract: In the production of an aliphatic polyester by ring-opening polymerization of a cyclic ester, at least a latter period of polymerization is proceeded with by way of solid-phase polymerization, and the resultant aliphatic polyester is subjected to removal of residual cyclic ester. As a result, an aliphatic polyester with a minimized content of residual monomer is obtained.

Abstract: A biodegradable filament of polyglycolic acid resin having practical properties represented by high tensile strength and knot strength is produced. A polyglycolic acid resin having a residual monomer content of below 0.5 wt. % is melt-spun, quenched in a liquid bath of at most 10 ° C. and then stretched in a liquid bath of 60-83 ° C. to produce a polyglycolic acid resin filament having a tensile strength of at least 750 MPa and a knot strength of at least 600 MPa.

Abstract: The invention relates to a glycolide production process wherein a depolymerization reaction system comprising a glycolic acid oligomer or a glycolic acid oligomer and a polar organic solvent is heated to depolymerize the glycolic acid oligomer into glycolide, the resulting glycolide or the glycolide and polar organic solvent are distilled out of the depolymerization reaction system, and the glycolide is recovered from distillates obtained by distillation. The glycolic acid oligomer or the glycolic acid oligomer and polar organic solvent are continuously or intermittently charged into the depolymerization reaction system, thereby carrying out depolymerization reactions continuously or repeatedly. During the depolymerization reactions, a compound having an alcoholic hydroxyl group is permitted to exist at a specific quantitative ratio in the depolymerization reaction system.

Abstract: A method of recycling a laminate shaped product, including the steps of: breaking a shaped product having a laminate structure including at least one layer of aliphatic polyester resin in addition to a principal resin layer, storing resultant broken pieces in a moisturizing environment to adjust a moisture content of the aliphatic polyester resin (layer) to at least 0.5 wt. %, and then washing the broken pieces with alkaline water to remove the aliphatic polyester resin layer, thereby recovering the principal resin. As a result, it becomes possible to shorten an induction period in the alkaline water washing step that is a principal process step, thereby rationalizing the entire process.

Abstract: A polyglycolic acid resin is used as a forming aid to efficiently produce various shapes, such as porous film, ultrafine fiber, ultrafine film and porous hollow fiber, of shaped products of substantially water-insoluble thermoplastic resins. More specifically, a shaped composite of the polyglycolic acid resin and the substantially water-insoluble thermoplastic resin is caused to contact an aqueous medium, thereby selectively removing the polyglycolic acid resin through solvolysis and extraction to leave a shaped product of the remaining thermoplastic resin. A glycolic acid aqueous produced by the solvolysis and extraction can be recycled into the polyglycolic acid resin as a forming aid via the formation of a concentrated glycolic acid oligomer and glycolide.

Abstract: A polyglycolic acid-based resin composition is formed by adding a relatively small amount of aromatic polyester resin to a polyglycolic acid resin. The thus-formed composition is provided with remarkably improved moisture resistance stability and hot-melt processability, and further improved stretchability, while retaining the excellent properties as represented by gas barrier property of the polyglycolic acid resin. As a result of stretching by utilizing the improved stretchability, a shaped product having an improved transparency can be obtained.

Abstract: A transparent multilayer stretched product is produced through a process including: providing a resin laminate including at least on layer of polyglycolic acid resin, heat-forming and cooling the resin laminate, reheating the resin laminate until the polyglycolic acid resin is crystallized to be opaque and then stretching the reheated resin laminate. The thus-obtained multilayer stretched product is excellent in gas-barrier property in addition to the transparency and is suitable as a packaging material or container.

Abstract: Polyhydroxycarhoxylic acids are provided, which are controlled in terms of the rate of biodegradability, and give molded or otherwise formed articles that are of uniform quality with neither premature strength drop nor premature deterioration of retention of outside shape, and their production process is provided as well. The poly-hydroxycarboxylic acids are obtained by ring-opening polymerization of cyclic esters. The polyhydroxy-carboxylic acids have a weight-average molecular weight (Mw) in the range of 10,000 to 1,000,000, a molecular weight distribution in the range of 1.0 to 2.5 as represented by the weight-average molecular weight-to-number-average molecular weight ratio (Mw/Mn) and a yellowness index (YI) of 40 or less, and have a precisely controlled rate of biodegradability.

Abstract: A polyglycolic acid-based resin composition is formed by adding a relatively small amount of aromatic polyester resin to a polyglycolic acid resin. The thus-formed composition is provided with remarkably improved moisture resistance stability and hot-melt processability, and further improved stretchability, while retaining the excellent properties as represented by gas barrier property of the polyglycolic acid resin. As a result of stretching by utilizing the improved stretchability, a shaped product having an improved transparency can be obtained.