JPH02138400A - Production of reclaimed leather - Google Patents

Abstract

PURPOSE:To obtain a reclaimed leather of excellent bending strength by making a sheet from a a slurry containing a waste split leather based on shavings of a chromium-tanned leather and a specified aqueous anionic resin emulsion. CONSTITUTION:100 pts.wt. mixture of 0.5-10wt.% unsaturated chloro or bromo monomer (a) (e.g., vinyl monochloroacetate) reactive with the protein of leather with 99.5-90wt.% other unsaturated monomers (b) (e.g., methyl methacrylate) is emulsion-polymerized in water in the presence of 0.5-5 pts.wt. anionic emulsifier (c) to obtain an anionic resin emulsion (B) of a copolymer of components (a) and (b) having a film-forming temperature of -10 to 80 deg.C. A slurry obtained by adding water to a waste split leather (A) based on shavings of chromium- tanned leather and adding 8-50 pts.wt. (in terms of the resin content) component B per 100 pts.wt. component to to the mixture is made into a reclaimed leather.

Description

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

[Prior art]

A slurry containing an aqueous anionic resin emulsion adhesive mixed with an aqueous dispersion of open fibers whose main component is chrome-tanned shaving waste is wet-formed into a sheet, which is then dried to produce recycled leather. are publicly known (Japanese Patent Publication No. 59-560, 59-33,160, 57-154.500, 58-93.800, 57-149,566).

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, OJ-tanned shaving waste is often tanned with cationic chromium salts, and the carboxyl groups of the skin are blocked and the basic groups are activated, so there is anionic shavings. When a resin emulsion adhesive is added, the anionic adhesive and the shaving waste bond rapidly on the surface of the leather fibers, causing the leather fibers to bond together using the adhesive as a medium. Agglomerates are formed, making papermaking by the wet process virtually difficult.

Therefore, as a method for preventing agglomeration when mixing a chromium-tanned 9-shaving clean water dispersion and an anionic resin aqueous emulsion, the aforementioned patent publication group s Naho 9-33
, No. 160, 50-95% chrome tanning straw waste,
It is said that wet papermaking is possible by adding an anionic resin emulsion to a mixture of 5 to 50% fine asbestos or cationic fine inorganic fibers in water. This causes the anionic resin emulsion to aggregate on the surface of the cationic inorganic fibers at the tip of the paper, reducing the apparent 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.

%$t-149,56s issue has leather scraps and latex (
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.

β1 萄#s 7-154.500, 58-93,800
In this issue, when mixing shaving waste with papermaking fibers, an anionic acrylic ester resin emulsion agent is added,
Attempts have been made to eliminate the non-uniformity between the binder and the leather fibers by making an aggregate slurry in advance and mixing it with the straw waste slurry, but the process is complicated and there are still problems with uniformity. be.

As a method to improve such conventional drawbacks, we first
Chrome-tanned shaving waste defibrated material, α, β-
Carboxyl group based on unsaturated carboxylic acid (-COOH
proposed a method for producing recycled leather from a slurry containing an aqueous anionic resin emulsion containing 1.4 x 10 moles or less of
No. 0827).

This method has the advantage that the slurry from which recycled leather is produced by papermaking has good storage stability and that tough recycled leather can be obtained.

[Problem to be solved by the invention]

According to the method of this previous application, the carboxyl group (-COOH') of the emulsion resin reacts to the extent that it reacts with the amino group (-NI(2')) of the protein in the tanning straw, so it is not suitable for artificial leather. It is necessary to use long fiber length (3-7 m) of waste to provide strength.

(Protein) (Binder) However, when long fibers are used, it is difficult to disperse the straw waste, making it impossible to obtain a uniform slurry.

If waste with short fiber length (3 cm or less) is used, the folding strength of the paper-made artificial leather will be low.

An object of the present invention is to provide artificial leather that has good bending strength regardless of whether long or short waste fibers are used.

[Specific means to solve the problem]

In the present invention, as an aqueous emulsion of an anionic copolymer as a binder, -NH
Using a copolymerized aqueous emulsion with -gen groups (-α, -13r) that reacts with polar groups such as z, -8H, -COOH, -CON (using tanned leather scraps with shorter fiber length) However, since many bonds are formed between the halogen group of the binder and the polar group of the protein, artificial leather with high bending strength can be obtained.

That is, the present invention is directed to a smooth fiber whose main component is chrome-tanned leather shavings, and an unsaturated monomer having a chloro group or a bromine group (-〇, -Br) that reacts with the protein of the leather. O, S~10 by weight and other unsaturated monomers 99.5~
90! The present invention provides a method for producing recycled leather by paper-making a slurry containing an aqueous anionic resin emulsion of a copolymer obtained by copolymerizing with f1%.

(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. A portion of the shaving waste may be replaced with tanned leather waste, valve fiber, inorganic fiber, or resin fiber.

This fully defibrated shaving waste becomes slimy like gruel in water. An anionic resin aqueous emulsion is added to this shaving waste and water mixture.

(Aqueous anionic resin emulsion) The aqueous anionic resin emulsion that imparts shape retention, water resistance, flexibility, or rigidity to recycled leather contains ~10% by weight of unsaturated monomers containing chlorine or bromine groups. Containing unsaturated monomers, anionic surfactants such as dodecylbenzenesulfonic acid and p-nonylphenol sulfuric acid half ester, 0.1 to 5% by weight of nonionic surfactants, and 0 to 5% by weight of nonionic surfactants. This is a resin emulsion of a copolymer obtained by emulsion polymerization in the presence of calcium persulfate.

The unsaturated monomer having a halogen group that reacts with the protein of tanned leather scraps has the following formula: [In the formula, R is R or C1 (31R1 is an alcohol residue containing one or more chloro group or bromo group)] 2,3-dicCIOpropyl acrylate represented by
2.3-dichloroglobil methacrylate, etc.; formula, O [wherein,
Monochlorovinyl acetate, monobromovinyl acetate, α-cyanomonochlorovinyl acetate, α-cyanomonobromovinyl acetate, etc.: Formula, RO0 [wherein, R is H or CH3: X is the same as the definition of formula (1) ] (N-monochloroacetamidomethyl)acrylamide, (N-monochloroacetamidomethyl)acrylamide, (N-monobromoacetamidomethyl)
Acrylamide and their methacrylamide equivalents; (N-monochloroacetoxyethyl)acrylamide, (N-motupromacetoxyethyl)acrylamide, (N-monochloroacetoxyethyl)methacrylabad, etc., represented by υ in the formula; , 2-monochloroacetamidoethyl acrylate, 2-monochloroacetamidoethyl methacrylate, 2-monochloroacetamidoethyl acrylate and the like represented by ROO are used.

This unsaturated monomer having a rogene group is 0.5 to 10
It is used in a ratio of 1.5 to 5°O weight%, preferably 1.5 to 5°O weight%. If it is less than 0.5% by weight, the binder effect of the emulsion copolymer resin will be insufficient. If it exceeds 10% by weight, emulsion polymerization is difficult, and this expensive...
The use of C1,-Br)-containing unsaturated monomers is disadvantageous because it increases the production cost of artificial leather.

Other unsaturated monomers include n-propyl methacrylate (Tg81C), styrene (100°C), acrylonitrile (100°C), methyl methacrylate (105°C),
Methacrylic acid (130℃), itaconic acid (130℃),
Acrylamide (153°C), 2-ethylhexyl acrylate (Tg -85°C), acrylic A-acid 1111 pudel (-54'C), ethyl acrylate (-22°C), impropyl acrylate (-50), methacryl acid 2-t
n-propyl acrylate (-5°C), n-propyl acrylate (8
), Budel methacrylate (20°C), vinyl acetate (30°C), t-butyl acrylate (45°C), 2-hydroxynibble methacrylate (55°C), methyl methacrylate (85C), methacrylic acid Inbudel (67℃)
, vinyl chloride (79℃), vinylidene chloride (-180)
, ethylene, etc. are used alone or in combination of two or more types (the numbers in parentheses are the glass transition points of homopolymers of these vinyl monomers). In addition, 2-acid phosphoxyethyl methacrylate, 2-acid phosphoxypropyl methacrylate, etc. represented by the formula % formula % [wherein R is H or cu, and R1 is an alcohol residue containing a phosphoric acid group] 0 to 5% by weight is used.

The type of these single pieces and the stitches to be used are determined by considering the usage temperature of the resulting emulsion and using the glass transition point of the resulting resin as a guide.

In the present invention, from the viewpoint of forming a film, it is preferable to use an emulsion in which the film forming temperature is 30° C. or lower, and the film forming temperature is 110° C. or higher in consideration of the hardness of the film, stains due to stickiness, etc. Alternatively, two or more types of emulsions may be blended for use.

In addition, when molding recycled leather, the glass transition point is 30
An aqueous emulsion of the resin at ~80°C is preferred. If the Tg of the resin in the emulsion becomes high, the leather fibers will deteriorate due to heating for film formation.
It is necessary to select

In this case, it is preferable that the straw waste has a long fiber length. Also, emulsion resin! Variant I is usually used in amounts of 20 to 55% by weight. In addition, antifoaming agents, dispersants, thickeners, antifreeze agents,
Coating aids, plasticizers, colorants, fillers, fragrances, etc. may be added to the emulsion.

A preferable aqueous copolymer emulsion includes (8) an unsaturated monomer containing a chloro group or a bromine group (0.5 to 1 O), an acrylic acid alkyl ester (the number of carbon atoms in the alkyl group is 2 to 8); 40-55 weight (C) Monomer selected from methyl methacrylate, styrene and acrylonitrile 30-55 weight l1% 1) N-phenyl! Reimide, N-methylolacrylamide, acrylamide, methacrylamide, 2-hydroxyalkyl acrylate (the number of carbon atoms in the alkyl group is 2
4) 100 parts by weight of an unsaturated monomer mixture consisting of 0 to 0.3% by weight of an unsaturated single precipitate selected from θ to 1O (e) 0 to 0.3% by weight of α,β-unsaturated carboxylic acid, 0.1 to 5 parts by weight of emulsifier and 0 to 5 parts of nonionic emulsifier
The film thickness obtained by emulsion polymerization using a polymerization catalyst such as calcium persulfate in the presence of 5 parts by weight is 110~
+80°C.

Component (a), the unsaturated monomer containing a rogene group, improves adhesion to shaving debris, and is therefore preferably present as much as possible; however, if it is too large, emulsion polymerization becomes difficult.

(b) Fy, the acrylic acid alkyl ester, is a knot monomer that gives flexibility to the film, including ethyl acrylate, inglovir acrylate, n-butyl acrylate, 1-butyl acrylate, n-propyl acrylate, 2-ethylhexyl acrylate or the like is used.

Component (C), methyl methacrylate, acrylonitrile, or styrene, gives toughness to the film.
However, some of these may be replaced with ethyl methacrylate, inglovir methacrylate, or isobutel methacrylate.

The unsaturated monomer having an 10H group, -CONHz group, and methylol group in component (d) has good adhesion to shaving debris, similar to the unsaturated acid having a carboxyl group in component (e). It is.

As the α,β-unsaturated carboxylic acid (including its anhydride) of component (e), acrylic acid, methacrylic acid, itaconic acid, etc. can be used.

Anionic resin aqueous emulsion, shaving waste 1
The resin solid content is used in a ratio of 8 to 50 parts by weight, preferably 12 to 20 parts by weight, per 00 parts by weight.

If the amount is less than 8 parts, the contribution to the improvement of water resistance is small.

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. Further, from the viewpoint of the efficiency of coating the resin component on the waste leather during paper making, a flocculant may be added.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples. Note that parts and percentages in the examples are based on weight unless otherwise specified.

Emulsion production example 1 Temperature controller, anchor stirrer, R flow cooler, supply container,
The following raw materials were charged into a reaction vessel equipped with a hood meter and a nitrogen inlet tube.

water 20
0 parts 35% aqueous solution of sodium #1 ester of p-7 nylphenol in sulfuric acid (anionic emulsifier) reacted with 20 moles of ethylene oxide 5 parts of p-nonylphenol (nonionic emulsifier) reacted with 25 moles of ethylene oxide 20 parts of 20% solution.

Next, after purging the inside of the reaction vessel with nitrogen gas, 10% of the following feed (2) was added, and the mixture was heated to 90°C.

Supply I Water 200
Part: 35% aqueous solution of the anionic emulsifier, 25
Parts Methyl methacrylate 195 parts Acrylic acid n-bu''fk 189 parts Vinyl chloroacetate 8 parts Acrylamide
Part 8.

Furthermore, after charging 10% of a solution of 2.5 parts of potassium persulfate in 185 parts of water (Feed ■) into the container, all of the remaining Feed ■ and 90 parts of Feed ■ were added to 3. The mixture was fed into the container over a period of 5 hours, and after the feeding was completed, the feed L was polymerized while being kept at the same temperature for 2 hours to obtain an anionic resin aqueous emulsion.

Examples 2 to 15 Anionic resin aqueous emulsions were obtained in the same manner as in Example 1, except that the composition of the vinyl monomer was changed as shown in Table 1.

Example 1 Chrome tanning shaving waste (fiber length 5cm), which is waste material generated from the leather manufacturing industry, was ground into a predetermined granule using a super mixer, and then charged into a Niagara beater at a concentration of 4%. is. Beating and defibration were performed using a Niagara beater for 40 minutes.

Water was further added to this beaten solution to give a concentration of 2%.

The anionic aqueous emulsion obtained in Production Example 1 with a film-forming temperature of 23°C (solid content concentration 50%, pi (7, 5) in the beating liquid, 201i!% (resin solid content) of shaving waste)
A papermaking raw material slurry was obtained by mixing with stirring so that the following results were obtained.

The state of dispersion of straw waste during the elapsed time after the preparation of this papermaking raw material slurry 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, 8% sulfuric acid was added to this papermaking raw material slurry to adjust the pH to 4, and then it was made into fourdrinier. Paper was made using a multi-tube paper machine, dehydrated by press, and further dried in dry air to obtain recycled leather with a wall thickness of approximately 2 cm.

The tensile strength of this recycled leather is 48mm/1.5an width9
The three-point bending strength was 1.3Ai'/1.5t1n width, and the absorption rate was 26.3%.

Examples 2 to 12, Comparative Examples 1 to 5 Using papermaking raw material slurries having the compositions shown in Table 2, recycled leather having the physical properties shown in the optical spectrum was obtained.

(Left below) Example 15, Comparative Example 6 In Example 1, the fiber length was 2+ as shaving waste.
Regenerated leather was obtained in the same manner except that a+ product was used and the emulsion of Example 1 (Example 16) or Example 10 (Comparative Example 5) was used.

Patent applicant Mitsubishi Yuka Verdice Co., Ltd. Agent
Patent Attorney Tadashi Hase Daido Takaya Yamamoto

Claims (1)

[Scope of Claims] 1) A defibrated waste material mainly composed of chrome-tanned leather shavings and an unsaturated monomer having a chloro group or a bromine group that reacts with the protein of the leather. A method for producing recycled leather by making paper from a slurry containing an aqueous emulsion of an anionic resin of a copolymer obtained by copolymerizing 10% by weight and 99.5 to 90% by weight of other unsaturated monomers. 2) The copolymer of the anionic resin aqueous emulsion contains (a) 0 unsaturated monomers having a chloro group or a bromine group.
．． 5 to 10% by weight (b) 40 to 55% by weight of an acrylic acid alkyl ester (alkyl group has 2 to 8 carbon atoms), (c) 30 to 55% by weight of a monomer selected from methyl methacrylate, styrene, and acrylonitrile. (d) 0 to 10 weight unsaturated monomers selected from N-phenylmaleimide, N-methylolacrylamide, acrylamide, methacrylamide, 2-hydroxyalkyl acrylate (alkyl group has 2 to 4 carbon atoms), (e ) Obtained by emulsion polymerization of 100 parts by weight of an unsaturated monomer mixture consisting of 0 to 0.3% by weight of α,β-unsaturated carboxylic acid in the presence of 0.5 to 5 parts by weight of an anionic emulsifier. 2. The method according to claim 1, which is a copolymer. 3) 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.
Claim 1, characterized in that it is blended in the proportion of parts by weight.
The method described in section.