JPH08109399A - High-density regenerated leather - Google Patents

Abstract

PURPOSE: To obtain regenerated leather having excellent leather-like surface and thin leather product-like touch. CONSTITUTION: Leather waste (shaving waste) occurring in leather processing is fibrillated, made into a sheet by a papermaking machine, subjected to super calendering treatment so as to make >=2 degree of smoothness and >=0.5g/cm<2> density and made into a sheet to give regenerated leather having leather-like surface and thin film leather product-like touch.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recycled leather which is made of fibrous leather scraps (shaving scraps, etc.) which have been subjected to a chrome tanning treatment.
More specifically, the present invention relates to a regenerated leather having a very excellent leather-like surface and having a feel like a thin leather product.

[0002]

2. Description of the Related Art At present, natural leather and synthetic leather are widely used for manufacturing clothes, handbags, shoes and the like. However, in the case of natural leather, the solid waste generated during the leather manufacturing process accounts for about 80% of the raw leather, and as a result, this useless by-product is landfilled. However, in recent years, research on resource utilization for increasing the added value of these by-products and more effectively utilizing them has been activated.

One of the effective uses of solid waste (hereinafter, abbreviated as "scrap") generated in the leather industry is the production of recycled leather. Generally, a method for producing recycled leather includes a paper machine, etc., which is produced by dry- or wet-fiberizing the leather scraps, either alone or mixed with other natural fibers, recycled fibers, synthetic fibers, or the like. Sheet (Japanese Patent Publication No. 38-20389, Japanese Patent Publication No. 41-13872, etc.) or mixed with other fibers and added with emulsion or latex to form a sheet (Japanese Patent Publication No. 42-5258). , Japanese Patent Publication No. 47-48644, etc.). The recycled leather sheet thus obtained has a merit that the texture thereof is relatively close to that of natural leather and that it can be obtained at low cost.

When such a recycled leather is used for clothes, for example, a leather-like surface and a feeling of a thin leather product are desired. However, the recycled leather sheets obtained by the conventional manufacturing methods are not sufficient. However, there is a problem that these qualities cannot be satisfied.

In order to improve these drawbacks, for example, in Japanese Patent Laid-Open No. 149566/1982, a sheet-like sheet made by two-layer paper making of a layer made of thick collagen fibers and a layer made of thin collagen fibers. However, when considering the steps of classifying collagen fibers and making a two-layer paper, it cannot be said that the method has good productivity in terms of cost.

Further, Japanese Patent Laid-Open Publication No. 58-93800 describes a sheet-like material prepared by applying a heat-expansion resin-containing paint to recycled leather, heat-treating it, and kneading it. In that case, it is not a productive method in terms of cost.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to improve the leather-like surface of recycled leather and the feel of thin leather products as described above. That is, it is intended to provide a regenerated leather which has good productivity and has an excellent leather-like surface and a feeling like a thin leather product.

[0008]

Means for Solving the Problems The present invention is to disintegrate into a slurry fiber generated during leather processing into a slurry, form the slurry into a sheet by a paper machine, and coat or impregnate a binder resin with a calender. It is a high-density recycled leather which is treated to have a smoothness of 2 seconds or more and a density of 0.5 g / cm ³ or more.

The inventors of the present invention have noticed that smoothing and densifying by supercalendering are highly productive and modify the surface of recycled leather to give a thin leather-like feel. Highly productive with a smooth surface and a high density by superposing a binder resin on the paper made from the dispersed slurry and applying or impregnating it with a binder resin. Found.

The debris used in the present invention is defibrated by a dry method. In this case, as the raw material, the shavings are the shavings generated in the leather manufacturing process of 5 to 10
It is desirable to break up into pieces with a width of about mm and defibrate with a water content of 30% or less. This is to prevent the defibrated fibers from becoming lumpy and reduce the defibration power.
Further, the kind of the genuine leather used at this time is not particularly limited, and any animal leather may be used, and any part of the leather may be used. The defibration is performed by a method that can be performed without pulverization, for example, using a hammer mill type defibrating machine with an improved crusher, mill or the like. In addition, in order to prevent the powder from falling off when the leather dust is made into a sheet,
Fine powder may be removed from the collagen fibers disintegrated by the dry method by sieving. Although the disentangled collagen fibers vary depending on the conditions, the fiber length under normal conditions is about 1 to 50 mm. Further, before or after defibration, the collagen fibers can be colored with an appropriate face dye.

In the present invention, when collagen fibers are dispersed in an aqueous medium to prepare a slurry, other fibers and pulps used in ordinary papermaking for the purpose of improving various physical properties of a leather sheet. It does not matter if mixed.
For example, wood pulp such as chemical pulp and mechanical pulp of softwood and hardwood, waste paper pulp, non-wood natural pulp such as hemp and cotton, synthetic pulp made from polyethylene, polypropylene, etc., acrylic fiber, rayon fiber, phenol fiber, Examples include organic fibers such as polyamide fibers and polyester fibers, glass fibers, inorganic fibers such as carbon fibers and alumina fibers, heat-fusible fibers such as polyethylene and PET, and use them in combination if necessary. It is possible to

Further, in the slurry in which collagen fibers and are dispersed in an aqueous medium, various anionic, nonionic,
Cationic or amphoteric retention aids, paper strength enhancers and the like can be used depending on the application.

Specifically, as a paper strength enhancer and a yield enhancer, polyacrylamide type anionic, nonionic, cationic and amphoteric resins, polyethyleneimine and its derivatives, polyethylene oxide, polyamines, polyamides and polyamides. Organic compounds such as polyamines and their derivatives, cationic and amphoteric starches, oxidized starches, carboxymethylated starches, plant gums, polyvinyl alcohol, urea formalin resins, melamine formalin resins, hydrophilic polymer particles, and sulfate bands,
Alumina sol, basic aluminum sulfate, basic aluminum chloride, aluminum compounds such as basic aluminum hydroxide, further ferrous sulfide, ferrous chloride, or colloidal silica, may be used in combination with an inorganic compound such as bentonite I can.

In addition to these, papermaking auxiliaries such as dyes, PH adjusting agents, defoaming agents, and viscous agents can be used depending on the application.

A binder resin such as synthetic resin emulsion, synthetic rubber latex, or natural rubber latex is applied to the leather sheet obtained as described above by a coating method such as a size press or a gate roll, or an impregnation machine is used. Impregnate into the sheet.

Examples of the synthetic resin emulsion used at this time include alkyd resins, acrylic resins, vinyl resins, cellulose resins, urethane resins, polyester resins, and the like, and synthetic and natural rubber latexes include Examples thereof include chloroprene rubber, isoprene rubber, nitrile rubber, and diene copolymer latex such as NBR and SBR. In this case, the solid content ratio of the emulsion or latex is preferably about 5 to 60% with respect to the absolute dry weight of the leather sheet as the coating amount or the impregnating amount.

Using the above-mentioned constituent raw materials as main raw materials, paper making is carried out using a paper making machine similar to the paper making of natural pulp, for example, a Fourdrinier type or cylinder type paper making machine.

The leather sheet obtained as described above is treated with a calendar. The calender used in the present invention is not particularly limited as long as the target smoothness and density can be obtained, and a normal paper machine calender, gloss calender, soft calender, super calender, etc. can be used. However, a super calender is suitable for increasing the density. The super calender is a machine used in a usual papermaking finishing (processing) step, and is a machine in which chilled rolls and elastic rolls are alternately overlapped with each other to improve smoothness and gloss when a sheet passes between them.
As the elastic roll, woolen type, cotton type, paper type, asbestos and the like can be used according to the purpose. By performing this super calendering process, a highly smooth and highly glossy sheet, which is difficult to obtain by other calendering processes, can be obtained. The smoothness, surface property, and density of the product are affected by the number of nip steps of the super calender, the pressing force, and the chilled roll temperature, and these conditions can be adjusted to obtain the target quality.

The smoothness of the leather sheet measured by the Oken method is 2
Recycled leather having a leather-like surface and a feeling like a thin leather product can be obtained by supercalendering so that the density is 0.5 g / cm ³ or more for a second or more. If the smoothness is less than 2 seconds, the surface of the sheet will have a rough texture,
It is not preferable because a sufficient leather-like surface cannot be obtained. When the density is less than 0.5 g / cm ³ , the feeling of weight is lost, so
Further, since the sheet becomes thick and the rigidity becomes high, it is not preferable because a sufficient feeling of thin leather products cannot be obtained.

[0020]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In Examples and Comparative Examples,% and parts mean% by weight and parts by weight, respectively.

Example 1 Collagen fiber obtained by defibrating the shaving waste of genuine leather by mechanical crushing was beaten to 600 ml of Canadian standard freeness (CSF) and dispersed in water. The raw material slurry was prepared by mixing and agitating softwood bleached pulp (NBKP) beaten to 600 ml of the Canadian standard freeness (CSF) in the collagen fiber slurry at a weight ratio of 80:20. A leather sheet having a basis weight of 100 g / m ^{2 was made} by a square sheet machine according to a conventional method. An NBR (Lack Star DN-703 (manufactured by Dainippon Ink and Chemicals, Inc.)) was applied to this sheet using an impregnation machine so that the solid content was 15% of the absolute dry weight of the leather sheet. To a cotton-based elastic roll (Special White Cotton Roll (Yuri Roll Machine Co., Ltd.)
(3) test calender (3 step test super calender (manufactured by Yuri Roll Machine Co., Ltd.)) at a temperature of 60 ° C. and a linear pressure of 190 kg / cm. A calender treatment was carried out so as to contact the elastic roll twice each) to prepare a leather sheet.

Example 2 Calendering was carried out 4 times under the processing conditions of the super calender used in Example 1 at a temperature of 60 ° C. and a linear pressure of 30 kg / cm (on both sides of the sheet, contacting the elastic roll twice). A leather sheet was prepared in the same manner as in Example 1 except that the calendering was performed on the leather sheet.

Comparative Example 1 A leather sheet was prepared in the same manner as in Example 1 except that the super calendar used in Example 1 was not used.

Comparative Example 2 The super calender used in Example 1 was calendered twice under the conditions of a temperature of 60 ° C. and a linear pressure of 30 kg / cm (on both sides of the sheet, contacting the elastic roll once). A leather sheet was prepared in the same manner as in Example 1 except that the calendering was performed on the leather sheet.

COMPARATIVE EXAMPLE 3 The NBR impregnated in Example 1 was impregnated so that the solid content was 40% of the absolute dry weight of the leather sheet, and the super calender treatment condition was a temperature of 60.
A leather sheet is prepared in the same manner as in Example 1 except that calendering is performed twice under conditions of a temperature of 15 ° C. and a linear pressure of 15 kg / cm (the calendering is performed once so that both sides of the sheet are brought into contact with the elastic roll). did.

The sheet-like materials obtained in Examples 1 and 2 and Comparative Examples 1 to 3 were evaluated for the leather-like surface and the feel of a thin leather product in the following manner.

The leather-like surface was visually evaluated and evaluated on a 4-point scale. The excellent one was classified into 1, the normal one into 2, the poor one into 3, and the extremely poor one into 4.

The feel of a thin leather product was judged by the rigidity and visual observation. The rigidity is evaluated by the Gurley stiffness measured according to TAPPI-T543, and the smaller the value, the better.
In addition, the visual judgment was classified into four grades, and the excellent ones were classified into 1, the normal ones into 2, and the defective ones into 3 and the extremely poor ones into 4.

The results are shown in Table 1.

[Table 1]

As is clear from Table 1, the regenerated leathers obtained in the examples can provide regenerated leathers having a leather-like surface and a feeling like a thin leather product as compared with the regenerated leathers of the comparative examples. did.

[0031]

EFFECT OF THE INVENTION According to the present invention described above, after the leather scraps (shaving scraps and the like) generated during leather processing are fibrillated into a sheet, and then coated or impregnated with a sheet and a binder resin by a paper machine, Smoothness 2 seconds or more, density 0.5g /
By supercalendering the sheet into a sheet having a size of ³ cm ³ or more, it is possible to obtain a recycled leather which has a high productivity and an excellent leather-like surface and feel like a thin leather product.

Claims (1)

[Claims] 1. A calender, which is produced by defibrating leather dust generated during leather processing into a slurry by dispersing it in an aqueous medium to form a slurry, coating the slurry with a paper machine, and coating or impregnating with a binder resin. Processed, smoothness 2 seconds or more,
Recycled leather having a density of 0.5 g / cm ³ or more.