Daicel Chemical Industries, Ltd.

Japan Tobacco Inc.

Daicel Corporation

Ministry of International Trade & Industry

Hitoshi Tsugaya

Kiyoshi Ishii

Yasushi Maeda

Zenjiro Honda

Hiroki Taniguchi

Syu Shimamoto

Kanae Nishimura

Nobuyuki Oji

Ryoshu Suzuki

Kengo Magara

Michio Tsuyumoto

Masahiko Sugimoto

Using a slurry containing a particulate or fibrous cellulose ester and a wood pulp with a Canadian standard freeness of 100 to 800 ml in a ratio of 10/90 to 90/10 (weight %), a tobacco filter material in the form of a sheet having a nonwoven web structure is produced. The slurry may contain a microfibrillated cellulose in a proportion of 0.1 to 10 weight % on a nonvolatile matter basis. The cellulose ester may be a cellulose acetate with a combined acetic acid in the range of 30 to 62%. This tobacco filter material in a sheet form can be applied to a tobacco filter having a high dry strength and, yet, a high degree of wet disintegratability without adversely affecting the smoking quality of tobacco. Thus, the potential environmental pollution is mitigated by the tobacco filter.

Tobacco filter material and a method of producing the same

A filter rod is produced by adding a water-soluble polymer in the form of an aqueous solution or dispersion, or in a particulate form, to a tow of cellulose ester fiber, with the amount of any water used being controlled within 25 parts by weight relative to 100 parts by weight of the tow, and wrapping the treated tow in wrapping paper. The water contained in the filter rod is removed or the particulate water-soluble polymer is melted by heating to bond the fiber to provide a tobacco filter. The proportion of the water-soluble polymer is 0.5 to 30 parts by weight to 100 parts by weight of the tow. To reduce the amount of water relative to the tow, a hot-melt adhesive water-soluble polymer may be employed. As the amount of water added to the tow is thus decreased, the tow can be smoothly wrapped up even at a high speed so that filter productivity is improved. This tobacco filter is highly wet-disintegratable and, hence, contributes to mitigation of the environmental pollution.

Tobacco filters and method of producing the same

A separatory membrane is provided which has a sufficient durability and shows a high rate of permeation therethrough and a high separation factor to a variety of organic substances and a wide range of concentration thereof in mutual separation of organic substances and separation of a water/organic substance mixture by pervaporation, vapor permeation or perstraction. The separatory membrane shows the performance that water permeates selectively through the membrane while satisfying such conditions that the product (QL) of the rate Q (kg/m.sup.2 .multidot.hr) of permeation and the thickness L (.mu.m) of the membrane is at least 0.5 kg.multidot..mu.m/m.sup.2 .multidot.hr and that the separation factor .alpha..gtoreq.10 and log.alpha..gtoreq.-1.77.times.log(QL)+2.77 when the pervaporation performance of a 5-30 .mu.m-thick dense uniform membrane is evaluated using as a liquid feed, an 80 wt. % aqueous solution of acetic acid at a temperature of 70.degree. C., and comprises, as the membrane material, a polyacrylonitrile copolymer constituted of 90 to 97 mol % of acrylonitrile monomer units and a specific comonomer(s).

Permselective membrane of polyacrylonitrile copolymer and process for

Separating membrane of polyion complex

A semipermeable membrane composed of a water-insoluble, cross-linked, membrane-forming polymer (hereinafter referred to as 'polymer (II)') which is obtained by partially converting the hydroxyl groups of a polymer represented by the following formula (hereinafter referred to as 'polymer (I)'): ##STR1## wherein R and R' are halogen, nitro, methyl or ethyl,

Semipermeable membrane

A semipermeable membrane suitable for the use in an artificial kidney of the filtration type is produced by preparing a solution of cellulose acetate in a solvent mixture consisting essentially of a solvent for cellulose acetate and a swelling agent and spreading said solvent on a substrate, the solvent being a mixture of dimethylformamide and acetone, the swelling agent being a mixture of cyclohexanone and water, the ratio by weight of the amount of dimethylformamide and that of acetone to that of the swelling agent being within the area defined by four points consisting of A (60, 20, 20), B (35, 45, 20), C (25, 35, 40) and D (50, 10, 40) in the triangular coordinates represented by FIG. 1; the ratio of cyclohexanone to water being in a range of from 0.8 to 1.3.

Process for preparing semipermeable membrane having selective

A semipermeable membrane composed of a water-insoluble, membrane-forming polymer (hereinafter referred to as 'polymer (II)') which is obtained by partially converting the hydroxyl groups of a polymer represented by the following formula (hereinafter referred to as 'polymer (I)'): ##STR1## wherein R and R' are halogen, nitro, methyl or ethyl, X stands for a divalent group selected from methylene, ethylene, isopropylidene, ether (--O--), carbonyl (--CO--), sulfide (--S--), sulfoxide (--SO--) and sulfone (--SO.sub.2 --), l and m are integers of from 0 to 4, p is 0 or 1, and n is an integer of from 100 to 1000, to sulfuric acid groups or alkali metal, ammonium or nitrogen-containing basic organic compound salts thereof.

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Kawachinagano, Japan

Hitoshi Tsugaya