Provided is a method of producing fine cellulose fibers that are nanosized, that have a high crystallinity degree, and that are less vulnerable to fiber shape damage, the method including impregnating cellulose with a fibrillation solution to fibrillate the cellulose without mechanical crushing, and modifying the cellulose. The method of producing cellulose microfibrils of the present invention includes impregnating cellulose with a fibrillation solution containing a carboxylic acid vinyl ester or an aldehyde and an aprotic solvent having a donor number of 26 or more to fibrillate the cellulose. The aldehyde is at least one kind of aldehyde selected from the group consisting of an aldehyde represented by the following formula (1), paraformaldehyde, cinnamaldehyde, perillaldehyde, vanillin, and glyoxal:

R.sup.1CHO(1)

where R.sup.1 represents a hydrogen atom, an alkyl group having 1 to 16 carbon atoms, an alkenyl group, a cycloalkyl group, or an aryl group.

The present invention concerns a process for removing ions from waste water, which process comprises providing plant-derived cationic nanofibrillar cellulose, carrying out a purification treatment comprising sorption of ions contained in the waste water to the plant-derived cationic nanofibrillar cellulose, separating used plant-derived cationic nanofibrillar cellulose from the waste water, and recovering treated waste water. The invention also concerns use of plant-derived cationic nanofibrillar cellulose in water treatment for removing charged contaminants.

Provided are modified plant fibers suitable for addition to rubber; an additive for rubber comprising the modified plant fibers which can be micronized and dispersed easily and highly when adding to rubber; a method of preparing the additive for rubber; and a rubber composition comprising the additive for rubber. Modified plant fibers (A) in which plant fibers (a) and a modified synthetic rubber (B) are covalently bonded wherein the ratio of the modified synthetic rubber (B) relative to 100 parts by weight of the plant fibers (a) is 5 to 100 parts by weight. An additive for rubber comprising 20 to 75 weight % of the modified plant fibers (A) according to claim 1 and 25 to 80 weight % of a processing agent for rubber (C), wherein the number average molecular weight of the processing agent for rubber (C) is 400 to 60,000, and the glass transition point of the processing agent for rubber (C) is 100 C. or less, and wherein the additive for rubber includes plant fibers in the ratio of 10 to 65 weight %.

Provided are modified plant fibers suitable for addition to rubber; an additive for rubber comprising the modified plant fibers which can be micronized and dispersed easily and highly when adding to rubber; a method of preparing the additive for rubber; and a rubber composition comprising the additive for rubber. Modified plant fibers (A) in which plant fibers (a) and a modified synthetic rubber (B) are covalently bonded wherein the ratio of the modified synthetic rubber (B) relative to 100 parts by weight of the plant fibers (a) is 5 to 100 parts by weight. An additive for rubber comprising 20 to 75 weight % of the modified plant fibers (A) according to claim 1 and 25 to 80 weight % of a processing agent for rubber (C), wherein the number average molecular weight of the processing agent for rubber (C) is 400 to 60,000, and the glass transition point of the processing agent for rubber (C) is 100 C. or less, and wherein the additive for rubber includes plant fibers in the ratio of 10 to 65 weight %.

An embodiment of the present disclosure provides fine cellulose fibers that satisfy, in measurement using an automatic fiber shape analyzer, all of (i) the length weighted average fiber length of fibers having a fiber length of at least 100 ?m is 110-500 ?m, (ii) the average fiber diameter is at most 42.5 ?m, (iii) the fine fiber area ratio is at most 90%, (iv) the number frequency of fibers having a fiber length of 20-56 ?m is at most 97% among fibers having a fiber length of less than 100 ?m, (v) the number frequency of fibers having a fiber length of at least 411 um is at most 54% among fibers having a fiber length of at least 100 ?m, and (vi) the average fiber diameter is 20-150 nm in terms of specific surface area.

Modified fine cellulose fibers are produced by impregnating a cellulose with a reactive fibrillation solution or mixture containing a catalyst including a base catalyst or an organic acid catalyst, a monobasic carboxylic anhydride, and an aprotic solvent having a donor number of not less than 26 to esterify and chemically fibrillate the cellulose. This method provides a simple efficient process for producing modified fine cellulose fibers that have a diameter from several nano-meters to submicrometers, a large aspect ratio, a high degree of crystallinity, less damage in the shape or crystalline structure of the fine fibers, a large aspect ratio, and an excellent dispersibility in an organic solvent; The catalyst may contain a pyridine compound. The monobasic carboxylic anhydride may be a C.sub.2-4aliphatic monocarboxylic anhydride. The resulting modified fine cellulose fibers modified with a monobasic carboxylic anhydride may have a degree of crystallinity of not less than 70%, an average fiber diameter of 20 to 800 nm, and an average fiber length of 1 to 200 m.

The invention relates to a method for obtaining a release liner and to release liner comprising a primer layer and a cellulose based support layer, the primer layer comprising an organic compound having one or more functional vinylic groups, the organic compound comprising an acetal connecting a first moiety and a second moiety, the first moiety comprising nanofibrillar cellulose having functional hydroxyl groups and the second moiety comprising an organic fragment, the organic fragment comprising at least one functional vinylic group.

The invention relates to a method for obtaining a release liner and to release liner comprising a primer layer and a cellulose based support layer, the primer layer comprising an organic compound having one or more functional vinylic groups, the organic compound comprising an acetal connecting a first moiety and a second moiety, the first moiety comprising nanofibrillar cellulose having functional hydroxyl groups and the second moiety comprising an organic fragment, the organic fragment comprising at least one functional vinylic group.

Provided is a resin composite having high mechanical properties which make the resin composite moldable into and usable as members for use in applications such as vehicle-mounted members and electrical materials. The resin composite comprises 0.5-40 mass % chemically modified, fine cellulose fibers and a resin, wherein the chemically modified, fine cellulose fibers have a pyrolysis initiation temperature (T.sub.D) of 270? C. or higher, a number-average fiber diameter of 10 nm or larger but less than 1 ?m, and a degree of crystallinity of 60% or higher. In a preferred embodiment, the chemically modified, fine cellulose fibers have a coefficient of variation (CV) in DS unevenness ratio, DSs/DSt, of 50% or less, the DS unevenness ratio being the ratio of the modification degree (DSs) of the surface layers of the fibers to the modification degree (DSt) of the whole of the fibers.

Provided is a resin composite having high mechanical properties which make the resin composite moldable into and usable as members for use in applications such as vehicle-mounted members and electrical materials. The resin composite comprises 0.5-40 mass % chemically modified, fine cellulose fibers and a resin, wherein the chemically modified, fine cellulose fibers have a pyrolysis initiation temperature (T.sub.D) of 270? C. or higher, a number-average fiber diameter of 10 nm or larger but less than 1 ?m, and a degree of crystallinity of 60% or higher. In a preferred embodiment, the chemically modified, fine cellulose fibers have a coefficient of variation (CV) in DS unevenness ratio, DSs/DSt, of 50% or less, the DS unevenness ratio being the ratio of the modification degree (DSs) of the surface layers of the fibers to the modification degree (DSt) of the whole of the fibers.