JPS63105200A - Production of regenerated leather - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing recycled leather using shaving waste of chrome-tanned leather generated during the bookbinding process.

[Prior art]

A slurry containing anionic resin Water Bi L Emulsicone adhesive mixed with an aqueous dispersion of open fibers mainly composed of chrome-tanned shaving waste is wet-formed and formed into a sheet.
It is publicly known that recycled leather can be produced by drying this (
JP 59-560, JP 59-33160, JP 57-154500, JP 58-93800, JP 57
-149566).

In these known techniques, the anionic resin emulsion not only functions as an adhesive but also provides water resistance and moldability to the resulting recycled leather.

However, in general, chrome-tanned shaving waste is often treated with cationic chromium salts, and the carboxyl groups of the skin are blocked and the basic groups are activated, so anionic resins are added thereto. When an emulsion adhesive is added, the anionic adhesive and shaving waste bond very quickly, and the adhesive rapidly bonds on the surface of the leather fibers, resulting in a skin T# using the adhesive as a medium.
A lumpy substance is formed, making paper making by the wet method practically difficult.

Therefore, as a method for preventing aggregation when a chromium-tanned shaving waste aqueous dispersion and an anionic resin aqueous emulsion are mixed, the above-mentioned patent publications disclose the
In No. 160, 50 to 95% chrome tanning Honjo, 5
It is said that wet papermaking is possible by adding an anionic resin emulsion to a mixture of ~50% fine asbestos or cationic fine inorganic fibers in water. This causes the anionic resin emulsion to coagulate on the surface of the cationic inorganic fibers before the fibers do, which apparently lowers the probability of aggregation with the leather.

With this method, there is a change in quality because it is necessary to add ingredients other than leather.

In JP-A No. 57-149566, latex and (
The paper is made into a sheet by adding an emulsion (excluding acrylic), but the anion-activated acrylic resin emulsion causes agglomeration in chrome tanned leather. However, acrylic resins have superior hardness, flexibility, weather resistance, and durability compared to latex resins.

JP-A-57-154500 and JP-A-58-93800 disclose a method of defibrating and beating shaving waste in the presence of an anionic acrylate resin emulsion and then forming it into a sheet when mixing shaving waste with papermaking fibers. In No. 560, a flocculant is added to the resin component to form an agglomerate slurry in advance, and this is mixed with a leather waste slurry.
Although attempts have been made to eliminate the non-uniformity between the binder and the leather fibers, there are problems with the complexity of the work and the uniformity.

[Specific measures to solve the problem]

In the present invention, an amphoteric surfactant is blended for the purpose of preventing rapid aggregation during mixing of shaving waste and anionic resin aqueous emulsion.

That is, the present invention proposes a method for producing recycled leather from a slurry containing defibrated chrome-tanned shaving waste, an aqueous anionic resin emulsion, and an amphoteric surfactant.

(Shaving waste) Chrome-tanned shaving waste has a uniform particle size, and is defibrated in a dry state using a beater such as a beater or refiner, or defibrated in water using a beater. Some of the shaving waste may be replaced with tanned fibers, pulp fibers, inorganic fibers, or resin fibers.

This fully defibrated shaving waste becomes slimy like gruel in water. An aqueous solution of an amphoteric surfactant is added to this mixture of shaving waste and water.

Alternatively, it is blended and added to an anionic resin aqueous emulsion.

(Ampholytic surfactant) Examples of amphoteric surfactants include those shown in the following table.

(Hereinafter in the margin) Among these, 2-alkylimidacillin derivatives are excellent.

This aqueous solution of imidacillin-based amphoteric surfactant is manufactured by Lion ■ with 2-alkyl-N-carboxyethyl-N-hydroxyethylimidazolium betaine under the trade name Enadicol CN5 (active ingredient 40%).
N-carboxymethyl-N-hydroxyethylimidazolium betaine is sold under the trade name Enadicol C-40 ((40% active ingredient)).Also, 2-alkyl-N-carboxymethyl-N-hydroxyethyl- Imidazolinium betaine is Amhitol 2o from Kao ■
It is sold under the trade name z (30% active ingredient).

Is the amphoteric surfactant 6 to 20 times the resin solid content of the anionic resin aqueous emulsion? %, preferably 8 to 12% by weight.

Since these amphoteric surfactants have properties such as softening effects and bactericidal properties, these properties can be expected to have a positive effect on artificial leather in addition to the stability of the emulsion system.

(Aqueous anionic resin emulsion) The aqueous anionic resin emulsion that gives shape retention, water resistance, flexibility, or rigidity to recycled leather is made by combining vinyl monomer with sodium dodecylbenzenesulfonate and sulfuric acid half ester of p-nonylphenol. Equal anionic surfactant 0
．． It is obtained by emulsion polymerization in the presence of 1 to 5% by weight, 0 to 5% by weight of a nonionic surfactant, and calcium persulfate.

As a vinyl monomer, n-propyl methacrylate (Tg
81℃), styrene (100℃), acrylonitrile (
100°C), methyl methacrylate (105°C), methacrylic acid (130°C), itaconic acid (130°C), acrylamide (153°C), 2-ethylhexyl acrylate (Tg -ss°C), n-butyl acrylate ( -54℃
), ethyl acrylate (-22℃), isopropyl acrylate (-5℃), 2-ethylhexyl methacrylate (
-5°C), n-propyl acrylate (8°C), n-butyl methacrylate (20°C), vinyl acetate (30°C), t-butyl acrylate (45°C), 2-hydroxyethyl methacrylate (55°C), °C), ethyl methacrylate (65 °C
), isobutyl methacrylate (67℃), vinyl chloride (
(79°C), vinylidene chloride (-18°C), ethylene, etc. are used alone or in combination of two or more (the numbers in parentheses are the glass transition points of homopolymers of these vinyl monomers).

The type and amount of these monomers to be used are determined by taking into consideration the usage temperature of the resulting emulsion and using the glass transition point of the resulting resin as a guide.

In the present invention, it is preferable to use an emulsion in which the film forming temperature is 30° C. or lower from the viewpoint of film formation, and the film forming temperature is 10° C. or higher in consideration of the hardness of the film, stains due to stickiness, etc.

In addition, when molding recycled leather, the glass transition point is 40
Aqueous emulsions of resins at ~120°C are preferred. In this case, it is preferable that the fiber length of Honsho is long.

The particle size of the emulsion resin is O,OS to 1 micron, and the emulsion resin ε) degree is usually used in the range of 20 to 550 to 55 parts by weight. Father, antifoaming agent, dispersion IJ, thickener,
Anti-freezing agents, film-forming aids, plasticizers, fragrances, etc. may also be added.

Anionic resin aqueous emulsion is shaving waste 1
00 parts by weight, the resin solid bond is used in an amount of 8 to 50 parts by weight, preferably 12 to 20 parts by weight.

8 parts by weight without grooves makes a small contribution to improving water resistance.

On the other hand, if it exceeds 50 parts by weight, it will not have a leather-like appearance but will become hard like a resin board.

The resulting recycled leather may be colored by adding dyes and pigments to the emulsion. From the standpoint of coating efficiency of the resin component to the waste leather during papermaking, a coagulant may be added.

Example 1 Shaving waste from chrome tanning, which is a waste material generated from the leather manufacturing industry, was ground in a super mixer until it became a predetermined granule, and this was charged into a Niagara beater to a concentration of 4%. Beating and defibration were performed using a Niagara beater for 40 minutes.

Further water was added to this beating solution to form an anionic aqueous emulsion of methyl methacrylate (47%), n-butyl acrylate (SO%) and acrylic acid (3%) copolymer (solid 50% by weight, film forming temperature: 20℃
, pH 9,3) 10% by weight of a 40% aqueous solution of Lion's amphoteric surfactant 2-alkyl-N-carboxyethyl-N-hydroxyethylimidazolinium betaine "Enadicol CNS" (trade name) in the 100 executive area. An emulsion blended at a ratio of 1 was mixed with the beating liquid under stirring so that the amount was 20% by weight (resin solid content) of the shaving waste to obtain a papermaking raw material slurry.

The dispersion state of this papermaking raw material slurry over the elapsed time after its preparation was as follows.

Immediately Good, paper can be made after 3 hours
Good, stored at 50°C for 1 day Good, stored at 50°C for 2 days Good, 1 Stored at 50°C for 7 days Good, paper making possible After adding 8% sulfuric acid to this papermaking raw material slurry and adjusting the pH to 4, This was made into paper using a Fourdrinier multi-tube paper making method, dehydrated by press, and further dried in dry air to obtain recycled leather having a wall thickness of about 2=.

The tensile strength of this recycled leather is 46Ay/1.5α width, and the 3-point bending strength is 1.2K! i/1.5 cm wide.

Example 2 As an anionic resin aqueous emulsion, Mitsubishi Yuka Verdice's acrylic room temperature crosslinking emulsion "Acronal YJ-2730D" (trade name, solid content 47%,
Regenerated leather was obtained in the same manner as in Example 1, except that the pH was 9.0 and the Tg was approximately 33°C.

The tensile strength of this recycled leather is u 56ky/1.5c
m width, bending strength is 1.9 / 1.5 t:n
It was q width. In addition, the dispersion state of the papermaking raw material slurry is
There was no problem.

Examples 3 to 7, Comparative Examples 1 to 4 Regenerated leather having the physical properties shown in Table 1 was obtained using a papermaking raw material slurry having the composition shown in Table 1.

Claims (1)

[Scope of Claims] 1) A waste defibrated material mainly composed of chrome-tanned leather shavings, and an anionic resin aqueous emulsion;
A method for producing recycled leather from a slurry containing an amphoteric surfactant. 2) The method according to claim 1, wherein the amphoteric surfactant (active ingredient) is blended in a proportion of 6 to 20% by weight of the resin solid content of the anionic resin aqueous emulsion. . 3) Amphoteric surfactants are represented by ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R is an alkyl group having 1 to 16 carbon atoms; R' is an alkylene group having 1 to 12 carbon atoms) 2. The method according to claim 1, wherein the alkylimidazoline derivative is an alkyl imidazoline derivative. 4) The anionic resin aqueous emulsion is obtained by emulsion polymerization of vinyl monomers with an emulsifier system consisting of 0.1 to 5% by weight of an anionic emulsifier and 0 to 5% by weight of a nonionic emulsifier based on the resin solid content. The method according to claim 1, characterized in that the method is performed by: 5) The anionic resin aqueous emulsion has a resin solid content of 8 to 50 parts by weight per 100 parts by weight of defibrated shaving waste.
2. The method according to claim 1, wherein the ingredients are blended in parts by weight.