摘要:
A process for producing aliphatic polyester wherein a crystallized aliphatic polyester prepolymer formed from an aliphatic dihydric alcohol and an aliphatic dicarboxylic acid and having a weight-average molecular weight of 2,000 to 100,000 is caused to undergo solid-phase polymerization in the presence of a volatile catalyst to make an aliphatic polyester having a weight-average molecular weight of 50,000 to 1,000,000. This process is more efficient than any prior process calling for a complicated step for catalyst removal, since it enables the removal of the catalyst from the reaction system during and/or after solid-phase polymerization. The polyester is comparable in stability to any aliphatic polyester having any catalyst removed therefrom.
摘要:
The invention relates to a process for producing an aliphatic polyester excellent in stability which includes subjecting an aliphatic polyester containing at least 50% of an aliphatic hydroxycarboxylic acid unit, obtainable by solid-phase polymerization under a flowing gas in the presence of a volatile catalyst so as to have a desired weight average molecular weight within the range of 50,000 to 1,000,000, to a heat treatment at a temperature equal to or higher than the reaction temperature of the solid-phase polymerization under a flowing gas with maintaining the aliphatic polyester in a solid state. According to the process of the invention, an aliphatic polyester excellent in stability at molding and storage stability is obtained.
摘要:
The invention provides a process for producing high-molecular aliphatic polyesters capable of being substitutes for general-purpose resins that are required to have high toughness, in a simplified manner and at a high volume efficiency. Specifically, in the process, used as the starting material is an easily-available, low-molecular aliphatic polyester prepolymer to be prepared through polycondensation of inexpensive materials of an aliphatic hydroxycarboxylic acid such as lactic acid, glycolic acid or the like, an aliphatic polyalcohol such as butanediol or the like, and an aliphatic polycarboxylic acid such as succinic acid or the like, and the starting prepolymer is crystallized and thereafter polycondensed in a solid phase in the presence of a catalyst to give the intended, tough and high-molecular aliphatic polyester.
摘要:
A preparation process of a degradable copolymer comprising carrying out dehydration polycondensation of polysaccharide (A) with one or more compounds (B) selected from the group consisting of: (b1) hydroxycarboxylic acid, (b2) polyhydroxycarboxylic acid, (b3) aliphatic polyhydric alcohol and aliphatic polybasic acid, and (b4) aliphatic polyester derived from aliphatic polyhydric alcohol and aliphatic polybasic acid. A copolymer having a high molecular weight, excellent toughness, transparency and heat resistance, and additionally having a high melt tension can be obtained with a reaction time less than a half of the conventional process. The copolymer obtained by the invention is a material suited for injection molding, extrusion, calendaring, blow forming, balloon forming, vacuum forming and foaming. Particularly, the copolymer obtained by the invention has a high melt tension and thus the molten copolymer is difficult to sag and flow and can be processed with ease into foams and blow bottles.
摘要:
A biodegradable aliphatic polyester elastomer which has rubber-like elasticity, hardness of 80 or less in accordance with ASTM D 676-58T, and elastic modulus from 1.times.10.sup.5 Pa to 1.times.10.sup.8 Pa at 25.degree. C., and decomposes with ease in the natural environment, under composting conditions or under hydrolysis conditions. The biodegradable aliphatic elastomer can be obtained by crosslinking aliphatic polyester containing aliphatic unsaturated polybasic acid as a polymer constituting ingredient and having a weight average molecular weight of 15,000 or more.
摘要翻译:具有橡胶状弹性,根据ASTM D 676-58T的硬度为80以下的生物降解性脂肪族聚酯弹性体,25℃下的弹性模量为1×10 5 Pa〜1×10 8 Pa,在自然环境中容易分解, 在堆肥条件下或在水解条件下。 可生物降解的脂肪族弹性体可以通过将含有脂肪族不饱和多元酸的脂肪族聚酯作为构成成分的聚合物交联而获得,重均分子量为15000以上。
摘要:
A purification process of an aliphatic polyester prepared in the presence of a catalyst from a hydroxycarboxylic acid or a cyclic ester of a hydroxycarboxylic acid, or a combination of an aliphatic polyhydric alcohol with an aliphatic polybasic acid, or a mixture of these compounds, comprising deactivating the catalyst while maintaining the aliphatic polyester in a molten or dissolved state, or insolubilizing and separating the catalyst and successively removing low molecular compounds. The process can provide aliphatic polyester which has a low content of unreacted monomers and low molecular weight compounds and is excellent in heat resistance and weatherability.
摘要:
The invention is a purification process of an aliphatic polyester prepared in the presence of a catalyst from a hydroxycarboxylic acid or a cyclic ester of a hydroxycarboxylic acid, or a combination of an aliphatic polyhydric alcohol with an aliphatic polybasic acid, or a mixture of these compounds, comprising deactivating the catalyst while maintaining the aliphatic polyester in a molten or dissolved state, or insolubilizing and separating the catalyst and successively removing low molecular compounds; and can provide aliphatic polyester which has a low content of unreacted monomers and low molecular weight compounds and is excellent in heat resistance and weatherability.
摘要:
A low-birefringent organic optical component comprising a polymer prepared by polymerizing a racemic mixture of the monomer with an asymmetric spiro ring represented by general formula (1) as an essential ingredient; wherein ring A represents a monocyclic or polycyclic organic group, wherein two ring As are mutually bound each other via a spiro bond to form a spiro ring which has a molecular asymmetric structure; n is an integer of 0 to 10; X.sub.1 and Y.sub.1 are binding groups; and Z.sub.1 is a polymerization-active group. The component has excellent transparency, mechanical strength and heat resistance, as well as a low birefringence.
摘要:
The invention provides a phosphate compound having an unsaturated double bond and a metal salt thereof; a dental material containing a phosphate compound having an unsaturated double bond and/or a metal salt thereof; and a dental composition containing a phosphate compound having an unsaturated double bond and/or a metal salt thereof. The phosphate compound of the invention provides a dental material and a dental composition such as a bonding material, adhesive material and a dental luting agent that are highly stable during storage, convenient for handling, and that exhibit higher adhesiveness and bond durability.
摘要:
A fuel pump includes a case member defining a fuel passage and a discharge-side cover connected to the case member and defining an outlet port. A pump section has an inlet port and is connected to the case member. A motor section is housed in the case member for driving the pump section. A positive electrode terminal and a negative electrode terminal are supported by an insulative terminal support member fixed to the discharge-side cover. Base portions of the positive and negative electrode terminals are covered by insulative portions. The insulative portions are fitted in fitting holes of the discharge-side cover. The discharge-side cover has guide portions on its inner surface. The terminal support member has engagement projections on opposite side walls thereof. The engagement projections are guided by the guide portions to restrict the discharge-side cover from rotating with respect to the terminal support member.