Abstract: The present invention relates to a dispersing agent for pigments or extenders which is obtainable by salt formation from an amine-functional compound by means of an acid,wherein a polyamine which contains at least three amino groups and which is from the group comprising aliphatic linear polyamines and/or aliphatic branched polyamines and/or modified polyamines, with the proviso that after modification three amino groups which can be converted into salts are still present per molecule, or a mixture of polyamines such as these, is used as the amine-functional compound, andwherein a substance from the group comprising phosphoric acid esters of general formula: (HO).sub.3-n PO(OR.sup.1).sub.n where n=1 or 2, sulphonic acids of general formula HOSO.sub.2 R.sup.2 and acidic sulphuric acid esters of general formula HOSO.sub.3 R.sup.2 is used as the acid, wherein R.sup.1 and R.sup.

Abstract: A process and a device for continuous production of polyamides from a monomer starting material consisting (up to 100%) of adipic acid hexamethylene diamine and water are described. The process is characterized by completing of the first step under pressure at temperatures between 180 and 280.degree. C. in a closed reactor, after which the polyamide is subjected to further steps at the start of each of which vaporized water is removed or driven out by an inert gas.

Abstract: A conductive composition including a mixture of a reaction product ofa hole transporting hydroxy functionalized aryl amine,a hydroxy functionalized arylamine that is different from the hole transporting hydroxy functionalized aryl amine,a cross linkable polyamide, andand an acid capable of simultaneously cross linking the polyamide and oxidizing a portion of the hydroxy functionalized arylamine,the mixture of a reaction product includinga hole transporting hydroxy functionalized aryl amine andan oxidized hydroxy functionalized aryl amine in aa crosslinked polyamide matrix.Other embodiments including processes for applying the aforementioned composition and processes for using devices containing the compositions in high speed laser printing and related printing systems are also disclosed.

Abstract: A method of producing a polyamide resin by reacting with at least one diamine compound, at least one linear polyester resin consisting of at least one dicarboxylic acid component and at least one diol component and having an intrinsic viscosity of not less than 0.2 dl/g, the at least one diamine compound being used in an amount of 0.5-1.5 mol per 1 mol of the at least one linear polyester resin as calculated in the repeating unit thereof, the linear polyester resin and the diamine compound being reacted in a reaction medium comprising at least one solvent selected from aprotic protophobic polar solvents, so that the at least one diol component of the linear polyester resin is substituted by the diamine compound, resulting in the polyamide resin as a reaction product.

Abstract: The invention relates to polymers which form cholesteric phases, to a process for their preparation and to their use.Novel polymers and oligomers which form cholesteric phases essentially consist, as molecular building blocks, ofA. at least one bifunctional chiral molecular building block which contains at least one cyclic structural element other than a monosubstituted p-phenylene group,B. at least one bifunctional achiral or racemic molecular building block which contains at least one cyclic structural element containing at least four ring members, andC. at least one bifunctional molecular building block which can be either chiral or achiral, cyclic or acyclic, and is different from the molecular building blocks A and B actually employed,with the proviso that the molecular building block A is not derived exclusively from camphoric acid.

Abstract: A novel compound of N-substituted aromatic polyamide is prepared by introducing an aralkyl group to the N-position of an aromatic polyamide by metalizing the aromatic polyamide, then reacting the metalized polyamide with an aralkyl halide.

Abstract: An ionic thermosettable resin useful for imparting wet and dry strength to paper is made by: (a) providing a copolymer comprising monomer units derived by copolymerization of acrylamide or alkyl-substituted acrylamide and diallylamine or an acid salt thereof; and (b) reacting the copolymer with epihalohydrin or epihalohydrin equivalent and dialdehyde. Paper products made using the resin are more easily repulped than paper products made with conventional wet strength resins.

Abstract: A two-step process for the production of polyamides from .alpha.,.omega.-dinitriles and .alpha.,.omega.-diamines involving the catalytic hydrolysis of the .alpha.,.omega.-dinitrile by addition of water with simultaneous purging of the reactor (i.e., venting of ammonia and water vapor) in the first step followed by polymerization by addition of the .alpha.,.omega.-diamine to the hydrolysate in the second step. Such a process is particularly useful in the production of poly(hexamethylene adipamide), i.e., nylon 6,6, from adiponitrile and hexamethylene diamine using lower catalyst levels during hydrolysis and resulting in reduced levels of bis(hexamethylene)triamine, BHMT, in the polymer.

Abstract: The present invention describes a polyoxaamide copolymer and blends thereof that may be used to produce hydrogels, surgical devices such as catheters, molded devices, and the like. The polyoxaamide copolymers of the present invention are composed of a first divalent repeating unit of formula IA:[--X'--C(O)--R.sub.30 --C(O)--] IAa second divalent repeating unit of the formula IB:[X--C(O)--C(R.sub.1)(R.sub.2)--O--R.sub.3 --O--C(R.sub.1)(R.sub.2)--C(O)--]IBand a third repeating unit selected from the group of formulas consisting of:[--Y--R.sub.17 --].sub.T II[--O--R.sub.5 --C(O)--].sub.B, III([--O--R.sub.9 --C(O)].sub.P --O--).sub.L G XIand combinations thereof, wherein R.sub.30 is an alkylene, arylene, arylalkylene, substituted alkylene, substituted arylene and substituted alkylarylene provided that R.sub.30 cannot be --[C(R.sub.1)(R.sub.2)].sub.1--2 --O--R.sub.3 --O--[C(R'.sub.1)(R'.sub.2)].sub.

Abstract: The invention concerns a softener-free polyamide prepared by polycondensation and/or polymerization of polyamide-forming monomers, wherein it was obtained by adding 5-50 wt. % of a dimer diol with a molecular weight within the range of 400-1000 and/or corresponding OH-terminated polyesters.

Abstract: There are provided a polycarbodiimide copolymer having a main structure represented by the following formula (1): ##STR1## wherein R.sub.1 is an isocyanate residue; R.sub.2 is a polyfunctional liquid rubber residue; X is a urethane bond, an amide bond or a urea bond; p is an integer of 5 to 50; q is an integer of 1 to 5; and r is 0 or 1; and a process for producing the above polycarbodiimide copolymer, which comprises reacting a polyfunctional liquid rubber with an organic diisocyanate in excess of the rubber and then subjecting the diisocyanate components in the reaction system to carbodiimization using a carbodiimidization catalyst. The polycarbodiimide copolymer alleviates the problems of the prior art, has the excellent heat resistance inherently possessed by polycarbodiimide resins, is improved, as compared with conventional polycarbodiimide resins, in thermoformability under heating and pressure when made into a solid such as a powder or granules, and causes no blistering under heating.

Abstract: The new diamine, "3,3',5,5'-tetramethyl-2,2-bis[4-(4-amino-phenoxy)phenyl]propane" was synthesized and used to prepare high performance soluble engineering plastics by polycondensation. The polymer can be polyamides, polyimides or poly(amide-imide)s. These polymers exhibit excellent solubility, processability, heat resistance and mechanical performance.

Abstract: A process for the hydrolysis of a dinitrile (e.g., adiponitrile) utilizing from 0.1 to 500 mmoles of catalyst (e.g., a mixture of phosphorous acid and calcium hypophosphite) per mole of the dinitrile and in the presence of from 0.01 to 0.5 moles of a dicarboxylic acid cocatalyst (e.g., adipic acid) followed by addition of a diamine (e.g., hexamethylenediamine) and heating to produce polymerization. Such a process is particularly useful in the production of nylon 6,6 having a low BHMT content and improved melt stability.

Abstract: A polyoxymethylene resin composition comprising (A) 100 parts by weight of a polyoxymethylene resin and (B) 0.01 to 10 parts by weight of a vinyl compound having a primary acid amide group and an acid imide group is provided. The composition is excellent in heat stability in molding and weatherability and suited for use as a molding material for electric and electronic parts and automotive parts.

Abstract: A bis(disubstitutedmaleimide) derivative and a polyetherimide for optical communications and the polyetherimide formed therefrom are described. The polyetherimde has a high refractive index, so that when using such polyetherimide as a material for a core of an optical fiber, the range of the materials that can be selected for the cladding becomes wide. Also, a coating property and adhesion to a substrate are improved, thereby providing a good film forming property and thermal stability. Also, because the polyetherimide can minimize optical loss at a near infrared wavelength range, the polyetherimide is very useful as an optical material in the optical communications field adopting the light of near infrared wavelength.

Abstract: A process for the hydrolysis of a dinitrile (e.g., adiponitrile) utilizing a dicarboxylic acid (e.g., adipic acid) as the sole catalyst followed by addition of a diamine (e.g., hexamethylenediamine) and heating to produce polymerization. Such a process is particularly usefull in the production of nylon 6,6 having a low BHMT content and improved melt stability.

Abstract: The present invention provides a highly impact resistant polyamide composition which comprises a polyamide resin and an acid modification product of a metallocene catalyzed polyolefin elastomer. The invention also provides a less hygroscopic and highly impact resistant polyamide composition which comprises a polyamide resin, novolak phenol and an acid modification product of a metallocene catalyzed polyolefin elastomer. Used as the polyamide resin is less expensive nylon 6.

Abstract: Polyamides and process for their preparation comprising eitherA) epoxidizing an unsaturated or partially hydrogenated fatty acid glyceride;B) transesterifying the epoxidized glyceride with a C.sub.1-4 alkanol to obtain epoxidized fatty acid C.sub.1-4 alkyl esters;C) ring opening and dimerizing the epoxidized fatty acid C.sub.1-4 alkyl esters; andD) reacting the dimerized fatty acid C.sub.1-4 alkyl esters with a polyamine to obtain a polyamide; orA) transesterifying an unsaturated or partially hydrogenated glyceride with a C.sub.14 alkanol to obtain olefinically unsaturated fatty acid C.sub.1-4 alkyl esters;B) epoxidizing the unsaturated fatty acid C.sub.1-4 alkyl esters;C) ring opening and dimerizing the epoxidized fatty acid C.sub.1-4 alkyl esters; andD) reacting the dimerized fatty acid C.sub.1-4 alkyl esters with a polyamine to obtain a polyamide.

Abstract: A process is disclosed for producing with good productivity a cross-linked polyaspartic acid resin having biodegradability and high water absorbency. The process features inclusion of one of the following steps: (a) a polysuccinimide, which has been brought into a dispersed state by a dispersant, and a cross-linking agent are reacted to produce the cross-linked polyaspartic acid resin; (b) imide rings of a cross-linked polysuccinimide are subjected to a hydrolysis reaction while controlling a swelling degree of a resulting gel, whereby the cross-linked polyaspartic acid resin is produced; and (c) a gel of a cross-linked polysuccinimide, which has been obtained by reacting a cross-linking agent to a solution of a polysuccinimide in an organic solvent, is disintegrated to subject imide rings of the cross-linked polysuccinimide to a hydrolysis reaction, so that the cross-linked polyaspartic acid resin is produced.

Abstract: A thermosetting resin composition for a fixing treatment of electronic parts, which is able to adhere in short time at low temperature, has a heat resistance, is lowly hygroscopic, and hardly produces package cracks, etc.The thermosetting resin composition comprises polycarbodiimide which is soluble in organic solvents and silicone-modified polyimide which is soluble in organic solvents, which are compounded.

Abstract: Disclosed is a method of making an imide-containing polymer by bulk or melt polymerizing monomers. A mixture is formed of (1) a cyclic compound that contains an anhydride group and a second group which is an anhydride, a carboxylic acid, or an ester and (2) a diamine in an amount stoichiometric .+-.5 mole % of stoichiometric with the amount of cyclic compound. An end capper may also be included in the mixture to control the molecular weight but no solvent is used. A polyimidesiloxane can be made by using a siloxane-containing diamine. The mixture is heated to a temperature above the T.sub.g or T.sub.m of the polymer but below its degradation temperature.

Abstract: A copolymer of maleimide derivative and acrylic acid, represented by Formula I, is of high etch resistance and thermal resistance and can be used for photoresist in submicrolithography.

Abstract: The invention relates to a star-shaped branched polyamide that has a high thermal stability and can be produced in existing production facilities for the corresponding linear polyamide. This is achieved by allowing the polyamide branches, at least three, to be formed from a multifunctional core having functional groups chosen from the group comprising amine and carboxyl groups, the amine or carboxyl groups being bound to an acyclic compound in which branching occures, if it is branched, at a carbon atom, or via an acyclic chain to a heterocyclic compound showing point symmetry.The process for the preparation is carried out under the conditions of the preparation of the corresponding linear polyamide. It proves to be possible to obtain, after shorter polymerization times, a product with mechanical properties that are comparable with those of the linear polyamide after significantly longer polymerization times.

Abstract: The present invention provides, as heteroaromatic compounds made functional so as to be used for nonlinear optical materials, compounds represented by the following general formula (1), and also provides polymers obtained from these and nonlinear optical parts comprising such polymers. In the formula, Ar.sup.1 and Ar.sup.2 each represents a divalent aromatic group; R.sup.1, R.sup.2 and R.sup.3 each represents an atom or a group independently selected from a hydrogen atom or an alkyl group and an aromatic group; X.sup.1 represents a monovalent organic group; n represents an integer of 2 to 12; and Z.sup.1 and Z.sup.2 each represents a group independently selected from electron attractive functional groups.

Abstract: Disclosed is a gas separating membrane comprising a layer made of a polycarbodiimide resin having repeating units represented by formula (I): ##STR1## wherein R represents a divalent organic group. The gas separating membrane available according to the present invention has high permeability and separation selectivity as well as excellent permeating performance, and further has excellent heat resistance, chemical resistance and durability.

Abstract: An ink-jet printing dye-fixing agent is provided which comprises a quaternary cationic polymer having the main chain represented by general formula (1): ##STR1## where R.sub.1, R.sub.2, R.sub.3, and R.sub.4 are independently an aliphatic alkyl group of 1 or 2 carbons; R is an aliphatic alkene group of 1-6 carbons or a phenylene group; and n is an integer of from 3 to 300. A recording paper sheet employing the fixing agent is also provided. This fixing agent has excellent ink dye fixability, and makes ink coloring excellent and improves water resistance of the printed matter.

Abstract: An electrically conductive polymer is comprised of the reaction product of a dendrimer and an electrophoric compound which exhibits .pi.-stacking upon reduction. The reaction product which is a peripherally modified dendrimer is formed and reduced, either chemically or electrochemically, in a polar solvent. The reduced electrophoric moieties aggregate (form .pi.-stacks) to form electrically conductive pathways. The reduced peripherally modified dendrimers of the invention can be cast into films and other solid forms to provide flexible electrical conductors and semiconductors. The conductive polymers of the invention exhibit electrical conductivities comparable to that of doped polyacetalene, but are oxygen and moisture stable.

Abstract: This invention relates to methods of recycling catalyst in oxidations of hydrocarbons, such as cyclohexane for example, to respective intermediate oxidation products, such as adipic acid for example, by a direct process. The catalyst remains in solution despite removal of water from the composition, since the water removal is controlled at such temperatures and such remaining water levels that prevent catalyst from precipitating. The water removal is preferably conducted before removal of the intermediate oxidation product. Also, preferably, some, and more preferably all steps of the process are conducted in a single liquid phase region.

Abstract: A bis(trisubstitutedtrimellitic anhydride) derivative and a polyesterimide for optical communications, the polyesterimide being formed therefrom. The polyesterimide has a high refractive index, so that when using such polyesterimide as a material for a core of an optical fiber, the range of materials that can be selected for the cladding becomes wide. Also, a coating property and adhesion to a substrate are improved, thereby providing a good film forming property and thermal stability. Also, because the polyesterimide can minimize optical loss at a near infrared wavelength range, the polyesterimide is very useful as an optical material in the optical communications field adopting the light of near infrared wavelength.

Abstract: A polyamideimide for optical communications, having a minimum light absorption loss in a near infrared light wavelength range, high thermal stability and excellent film processibility, and a method for preparing the same are provided. The polyamideimide has a higher refractive index than the conventional fluorinated polyamideimide. Thus, when using such polyamideimide as a material for a core of an optical fiber, the selection range on the material for cladding becomes wide. Also the coating property and adhesiveness to a substrate are improved, thereby providing a good film processibility and heat resistance.

Abstract: Superabsorbent polymer compositions comprising a fiber-containing composition derived from cellulosic fibers, synthetic fibers or mixtures thereof which is at least partially coated with a partially hydrolyzed, internally plasticized, crosslinked, superabsorbing polymer derived from polysuccinimide and processes for preparing same.

Abstract: A method of forming a polyamide from a corresponding nylon salt material comprises providing a reaction mixture comprising a nylon salt and carbon dioxide; and then condensing the nylon salt in the carbon dioxide to form a polyamide and water. A method of forming a polyamide comprises providing a reaction mixture containing at least one lactam monomer and carbon dioxide; and then polymerizing the lactam monomer in the carbon dioxide to form a polyamide.

Abstract: By heating at above the melting point or glass transition point of the polyamide and adding a secondary aromatic amine and a difunctional epoxide it is possible to bring about an increase in the molecular weight and/or viscosity of virgin polyamide and recycled polyamide.

Abstract: Novel molten-salt type polyelectrolytes are disclosed which contain as an essential ingredient a molten salt polymer obtained by reacting an imidazolium derivative, such as a 1,3-dialkylimidazolium halide, 1,2,3-trialkylimidazolium halide, 1-vinyl-3-alkylimidazolium halide, or 1-vinyl-2,3-alkylimidazolium halide, with an acid monomer, a poly(vinylsulfonamide), trifluoromethanesulfonimide, or the like. The electrolytes show high ionic conductivity at room temperature and have excellent stability to temperature fluctuations and excellent mechanical properties.

Abstract: The present invention relates to an adhesive film which may be applied to several substrates, including plasticized polyvinyl chloride, such as canvas for trucks. The adhesive film according to the invention comprises at least a barrier layer and an adhesive layer, the barrier layer comprising a (co)polyamide. The adhesive film according to the invention may furthermore comprise a front layer, which is applied to the barrier layer. The barrier layer serves to prevent migration of components from the substrate, the front layer and the adhesive layer.

Abstract: The invention relates to belts made of thermoplastic polymer (A) and comprising a sufficient amount of a polymer (B) to render them antistatic, the said polymer (B) comprising polyethylene glycol blocks. Use is advantageously made of polymers (A) containing polyamide-6 (PA-6) or polyamide-12 (PA-12) blocks and polytetramethylene glycol blocks and polymers (B) containing PA-6 or PA-12 blocks and polyethylene glycol blocks.

Abstract: A polyamideimide for optical communications, having a minimum optical loss in a near infrared light wavelength range, high thermal resistance and good film processibility, and a method for preparing the same are provided. The polyamideimide is very useful as an optical material in the optical communications field adopting the light of near infrared light wavelength.

Abstract: Process for the preparation of polyamides comprising the steps of A) reacting a soybean oil condensate obtained from the deodorization of refined soybean oil and which contains less than 30% by weight of free and esterified oleic acid based on the total weight of free and esterified fatty acids in said condensate, with a C.sub.1-4 alkanol in the presence of a zinc oxide catalyst to convert free fatty acids and fatty acid glyceride esters to fatty acid C.sub.1-4 alkyl esters;B) removing excess C.sub.1-4 alkanol, volatile reaction by-products, water, and the zinc oxide catalyst from the resulting reaction mixture;C) heating the reaction mixture from step B) under vacuum to obtain a distillate of fatty acid C.sub.1-4 alkyl esters;D) separating the distillate from step C) into a fraction containing mostly C.sub.16-18 saturated fatty acid C.sub.1-4 alkyl esters and a second fraction containing mostly C.sub.16-18 unsaturated fatty acid C.sub.1-4 alkyl esters wherein the oleic acid C.sub.

Abstract: An improved method for manufacturing poly(hexamethylene adipamide), i.e. nylon 6,6, by reacting monomethyl adipate with hexamethylenediamine in an approximately equimolar ratio in the presence of water at a temperature of 100 to 165.degree. C. while simultaneous distilling off of a stoichiometric amount of methanol. The resulting aqueous intermediate product is then heated to 200 to 260.degree. C. while distilling off substantially all water at a pressure of 150 to 250 psig (1.03 .times.10.sup.6 to 1.72 .times.10.sup.6 Pa) followed by reducing the pressure to atmospheric pressure and increasing the temperature to 270 to 280.degree. C. to polycondense the distillate residue. Such a process is useful in producing high purity commercial grade poly(hexamethylene adipamide) that advantageously avoids problems caused by N-methylation of the polyamide.

Abstract: A fluororesin sheet is disclosed which comprises an aromatic polyamide pulp and a fluororesin as an essential component, the tensile strength of the fluororesin sheet being not less than about 250 kg/cm.sup.2. A process for producing this fluororesin sheet comprises dispersing the aromatic polyamide pulp and the fluororesin powder in water, adding a coagulating agent which destabilizes the dispersing of the fluororesin powder to the dispersion to deposit the fluororesin powder on the surface of the aromatic polyamide pulp, paper-making, followed by drying to obtain a sheet article, and compressing the sheet article using a roller, followed by heating.

Abstract: Ethylenically unsaturated compounds are provided having the structure: ##STR1## wherein R.sub.1 is hydrogen or methyl, R.sub.2 is a divalent linking group having 2 to 20 carbon atoms such as alkylene groups, and R.sub.3 is hydrogen or lower alkyl having 1 to 4 carbon atoms, and when R.sub.3 is hydrogen and R.sub.2 has two carbon atoms R.sub.2 is methyl methylene.

Abstract: A thermoplastic resin composition that includes a polyetherimide resin and a phosphorus-containing stabilizer that exhibits a low volatility. The thermoplastic resin composition exhibits improved melt stability and improved resistance to thermal degradation.

Abstract: Methods and devices for controlling the oxidation of a hydrocarbon to an acid by regulating the temperature hold-up time, and conversion in consecutive reaction zones. The temperature in the consecutive reaction zones progressively decreases, while the hold-up time increases. Preferably, the conversion also increases. One of the major advantages of the methods and devices of the present invention is that an outstanding balance between productivity and selectivity/yield of the desired acid may be achieved. In this respect high yields and selectivities may be obtained without sacrificing productivity.

Abstract: Super-absorbing polymeric networks of crosslinked polyaspartates are produced from crosslinked polysuccinimide. Super-absorbing polymeric networks are produced in a single reaction vessel by crosslinking polysuccinimide with at least one organic polyamine crosslinking agent in the presence of at least one nitrogenous base. The reaction is carried out in an aqueous reaction mixture to produce a polymeric network of crosslinked polyaspartate.

Abstract: A composition of matter comprising a polyamic acid/ester having an amide pendant group directly substituting an acid site of the polyamic acid is provided, which composition when cured provides a colored polymer film when the amide group is a chromophore. The resulting polymer which may be applied as a film to semiconductor chips to provide an optically sensitive semiconductor chip comprises a partially imidized polyamic acid wherein an amide pendant group is directly attached to one acid moiety of the polyamic acid and the other acid group imidized with the adjacent amino group of the polyamic acid. The polymers are useful as optical filters on semiconductor chips and for photoresist applications.

Abstract: Superabsorbent fiber and film compositions comprising partially acidified, hydrolyzed, internally plasticized, crosslinked, superabsorbing fibers or film derived from polysuccinimide and processes for preparing same.

Abstract: An antisettling agent for aqueous paints giving excellent settling-preventing properties to aqueous paints is provided. The antisettling agent is produced by the following process: A polyamide, which is obtained by reacting a primary diamine having 2 to 12 carbon atoms with, in an amount excess to the diamine, a dimer dicarboxylic acid obtained by polymerizing an unsaturated fatty acid (common name: dimer acid) or a mixture of a dimer acid with another dicarboxylic acid having 3 to 21 carbon atoms and/or a monocarboxylic acid having 2 to 22 carbon atoms, is neutralized with a neutralizing base, and then the neutralized polyamide is dispersed in a medium mainly composed of water.

Abstract: The present invention relates to an optical fiber (1) comprising an optical core (2) for guiding the majority of the lightwaves transmitted by the fiber, and surrounded by optical cladding (3), itself surrounded by a protective covering (4) of a plastics material, characterized in that the plastics material (4) is a reversibly cross-linked material.

Abstract: The improved water-soluble photosensitive resin composition comprises a high-polymer compound represented by the general formula (I): ##STR1## (where X is Na, K or NH.sub.4) and a water-soluble polymer which is either polyvinylpyrrolidone or a copolymer of vinylpyrrolidone and vinylimidazole or both. The composition is applied to a substrate, exposed through a mask pattern and developed to form a photocured pattern and, thereafter, a light absorber is applied to the entire surface of the substrate and dried, followed by stripping away the photocured pattern and the overlying light absorber to form a black matrix pattern. The composition is suitable for use as a photoresist in the manufacture of black matrices as on color CRTs and capable of efficient formation of photocured patterns with high sensitivity by shorter times and lower intensities of exposure.

Abstract: A cross-linked polymer containing, in its molecule, recurring units represented by the following formula (1), and having biodegradability and high water-absorbency: ##STR1## wherein R.sub.1 is a pendant group having at least one functional group selected from the group consisting of acidic groups and salts thereof, a glycino group and salts thereof, cationic groups and betaine groups; X.sub.1 is NH, NR.sub.1 ', R.sub.1 ' being an alkyl, aralkyl or aryl group, O or S; and n.sub.1 is 1 or 2.