Classifications

• • C—CHEMISTRY; METALLURGY
  • C14—SKINS; HIDES; PELTS; LEATHER
  • C14C—CHEMICAL TREATMENT OF HIDES, SKINS OR LEATHER, e.g. TANNING, IMPREGNATING, FINISHING; APPARATUS THEREFOR; COMPOSITIONS FOR TANNING
  • C14C11/00—Surface finishing of leather
  • C14C11/003—Surface finishing of leather using macromolecular compounds
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/4935—Impregnated naturally solid product [e.g., leather, stone, etc.]

Definitions

• the present invention relates to a process for finishing leather with a carboxylated rubber dispersion based on butadiene and / or isoprene and styrene and optionally oxides and / or hydroxides of 2 and / or 3-valent metals.
• Aqueous polyacrylate dispersions aqueous dispersions of vinyl acetate copolymers or aqueous dispersions of synthetic rubbers, i.e. Copolymers of 1,3-dienes, such as butadiene, isoprene or chloroprene, are used.
• the suitable pigments can be organic or inorganic in nature; come into question e.g. Iron oxide, titanium dioxide, kaolin, phthalocyanine or azo pigments.
• such dressings can contain thickeners, e.g. based on cellulose, such as carboxymethyl cellulose, polyvinyl alcohols, polyacrylic acid or their salts, casein or polymers of N-vinylpyrrolidone.
• binders of the type mentioned are satisfactory when dressing split leather, e.g. for upper leather, not yet, because they show poor embossability, poor cold flexibility and insufficient dry and wet buckling strength.
• Aqueous dispersions of synthetic rubber dispersions containing carboxyl groups have also been used as binders in the finishing of leather.
• a finish with improved hot ironing strength is achieved with the addition of zinc compounds, but with which the gloss, fullness and coverage as well as the grip are deteriorated and when different layers are applied due to insufficient adhesion of the layers to one another there is poor wet kink resistance .
• the dressings known from GB-PS 921 798 and 900 591 based on rubber dispersions containing polymerized carboxyl groups are also unsatisfactory in terms of their resistance to dry kinking.
• US Pat. No. 3,330,597 discloses a process for finishing leather in which a carboxylated synthetic rubber latex is used which is not completely polymerized and in which the remaining monomers have been removed.
• the rubber is after the Batch-Wd / HB - Procedure (one-step process) by emulsion polymerization of 1 to 10 parts by weight of ⁇ , ⁇ -monoethylenically unsaturated aliphatic carboxylic acids and 90 to 99 parts by weight of a mixture of acyclic, conjugated dienes with 4 to 9 carbon atoms and vinylaromatic compounds with 8 to 12 Carbon atoms and / or (meth) acrylonitrile of a (meth) acrylonitrile content of a maximum of 50 parts by weight.
• the dressing agent contains 0.5 to 50% by weight, based on the rubber, of one or more oxides and / or hydroxides of divalent metals such as zinc oxide or magnesium hydroxide.
• Preparations of split leather, which are produced by this method, show good closure and coverage, grain scar, toughness, cold flexibility and adhesion as well as dry and wet buckling strength, but their embossability and stack stickiness still leave something to be desired.
• the aqueous dispersions of the synthetic carboxylated rubber dispersions used for the dressings generally have a carboxylated rubber concentration of from 30 to 60, in particular from 35 to 55,% by weight.
• part of the monomer mixture in emulsified form together with a corresponding part of the emulsifier and the polymerization initiator and regulator are introduced in an aqueous receiver, the receiver is heated to the polymerization temperature and, after the polymerization has started, the remaining monomer emulsion, which contains the emulsifier and generally regulator, and separately run an aqueous solution of the polymerization initiator according to consumption.
• the reaction is then generally allowed to continue, so that the conversion is over 90, usually 95 to 98%.
• the polymerization temperature is usually selected in the range from 45 to 65 ° C. and generally customary water-soluble radical-forming polymerization initiators, such as sodium and ammonium persulfate or redox catalysts such as tert-butyl perbenzoate / formaldehyde sulfoxylate / iron (II) sulfate and tert.- Butyl hydroperoxide / ascorbic acid / iron (II) sulfate used. Water-soluble persulfates of the type mentioned are preferred.
• anionic and nonionic emulsifiers are suitable as emulsifiers, anionic emulsifiers being of particular interest.
• Sodium lauryl sulfate or alkylarylsulfonates with mostly 7 to 12 carbon atoms in the alkyl groups are preferably used as emulsifiers.
• the aqueous carboxylated rubber dispersions contain 1 to 10, preferably 1 to 5 parts by weight of (, .beta.-monoethylenically unsaturated 3 to 5 carbon atoms containing carboxylic acids, such as acrylic acid, methacrylic acid, maleic acid and / or itaconic acid, polymerized, acrylic acid being preferred
• carboxylic acids such as acrylic acid, methacrylic acid, maleic acid and / or itaconic acid, polymerized, acrylic acid being preferred
• the polymers contain butadiene or isoprene or mixtures of these in copolymerized form as monomers (a), butadiene polymers being preferred.
• the proportion of butadiene and / or isoprene is preferably between 40 and 60 parts by weight.
• the polymers should contain at least 10 parts Styrene may also contain up to 50 parts by weight of acrylonitrile in copolymerized form. The total amount of styrene and acrylonitrile should not exceed 90 parts by weight. Of the monomers (b), up to 25 parts by weight can be added by others copolymerizable monomers must be replaced, but the proportion of water-soluble mono together do not exceed 10% by weight of the polymer. Examples of additional water-soluble monomers are acrylamide, methacrylamide, N-methylol-acrylamide and -methacrylamide, vinylsulfonic acid or its water-soluble salts and allylsulfonic acid and its water-soluble salts.
• water-insoluble monomers are, for example, acrylic and methacrylic esters, such as methyl acrylate and methacrylate, ethyl acrylate, n-butyl acrylate and methacrylate, tert-butyl acrylate, isobutyl acrylate and methacrylate and 2-ethylhexyl acrylate and methacrylate, vinyl acetate and vinyl acetate, such as vinyl acetate and also vinyl halides, such as vinyl chloride and vinylidene chloride, and also hydroxyalkyl acrylates and methacrylates, such as 2-hydroxyethyl acrylate and methacrylate, 1,4-butanediol monoacrylate and 3-hydroxypropyl acrylate.
• acrylic and methacrylic esters such as methyl acrylate and methacrylate, ethyl acrylate, n-butyl acrylate and methacrylate, tert-butyl acrylate, isobuty
• regulators are usually used in amounts which are conventional per se and which are 0.3 to 1% by weight, based on the amount of the monomers.
• regulators e.g. Tetrabromethane, dialkyldixanthate and preferably alkyl mercaptans, such as especially dodecyl mercaptan, in question.
• the polymerization can be controlled in a conventional manner such that the proportion of the carboxylated rubber obtained (solid) which is soluble in dimethylformamide at room temperature is 20 to 60, preferably 25 to 50% by weight of the polymer.
• the new process gives leather formulations with very high buckling strengths in the dry and wet state which, despite improved embossability and reduced stacking tackiness, do not lag behind the buckling strengths of the process according to the US -PS 3 330 597 finished leather stand back.
• customary wetting agents can be added to the oxides or hydroxides of the divalent or trivalent metals, nonionic wetting agents being preferred.
• organic solvents for example methyl, ethyl, n-propyl and iso-propyl alcohol or ethyl glycol monoethyl ether or ketones, such as acetone and methyl ethyl ketone, natural or synthetic oils, such as claw oil, peanut oil or Vietnamese red oil, in free and / or emulsified form and also Defoamers can be added.
• Mixtures of this type are preferably used in the form of pastes in the process according to the invention.
• finishing agents can be applied to the leather in a manner known per se using the aqueous synthetic rubber dispersions containing carboxyl groups, pigment preparations of the type mentioned above and other additives. Casting, knife coating, brushing, spraying, brushing or plush processes can be used for this. The amount of finishing agent depends on the type and pretreatment of the leather and can be easily determined by preliminary tests.
• Priming is usually carried out in one or more orders and good hot-melted intermediate ironing or scar embossing results in a good fusion and thus a good finish of the primer.
• the viscosity of the application can be regulated in a conventional manner by means of thickeners, an increase in viscosity leading to a reduction in the penetration capacity and thereby to a higher filling effect, which is of particular interest when dressing split leather and leather fiber materials.
• the leathers prepared according to the new process dry very quickly and show excellent dry and wet kink resistance, good cold flexibility and embossability as well as very good rub-through resistance and adhesion from layer to layer and very good fullness. They also show greatly reduced stack gluing in comparison to the dressings according to US Pat. No. 3,330,597. This is surprising because of the virtually complete polymerization in the preparation of the binder dispersion with regard to the disclosure of US Pat. Nos. 3,330,597 and GB Pat. Nos. 921,798 and 900,591.
• the parts and percentages given in the following examples relate to the weight, unless stated otherwise.
• the parts by volume given in relation to the parts by weight are like the liter to the kilogram.
• the mixture is heated to 60 ° C. and polymerized for 30 minutes.
• the remaining monomer emulsion and the remaining peroxodisulfate solution are then fed in uniformly within 2 hours.
• the polymerization is continued at 60 ° C. until the solids content is about 38% (conversion about 95%, based on the monomers).
• the soluble fraction of the polymer is 38%.
• the comparative dispersion (a) obtained is freed from residual monomers.
• the carboxylated polymer contained therein has a soluble content of 17%.
• the mixture is then polymerized at 55 ° C. to a solids content of about 42% (conversion about 94%).
• the comparative dispersion (b) obtained is freed of residual monomers by passing nitrogen through it.
• the carboxylated polymer contained therein has a soluble fraction of 73%.
• a reducing agent solution of 0.0025 part of sodium formaldehyde sulfoxylate dihydrate and 0.1 part of ethoxylated octylphenol (25 ethylene oxide residues) in 0.9 part of water is then added within 2 hours and the mixture is polymerized at 35 ° C. to a solids content of 30.4% (turnover about 86 Z) after.
• the comparative dispersion (c) obtained is freed from residual monomers under reduced pressure.
• the carboxylated polymer dissolves completely in dimethylformamide.
• split leather For the preparation of split leather, 100 parts of a commercially available pigment preparation each with 600 parts of the above-described dispersions 1, 2, 3, (a), (b) and (c), 200 parts of water and 40 parts of a zinc oxide paste each in column 7, below, of the composition indicated in US Pat. No. 3,330,597.
• the mixture is applied to split leather with the plush board in an amount of 12 g / m 2 , the application is ironed at 80 ° C. and then sprayed until completely covered with another mixture. After drying, mint at 80 ° C and 200 bar with a 2 sec delay. Finally, a usual finish based on a nitro emulsion varnish is applied.
• the leathers are dried after the last spray application, with the coated side on top of one another and stored under a load of 5 kg / cm 2 at 40 ° C. for 18 hours.
• the assessment of the wet kink resistance and dry kink resistance of the finished leather is carried out in the usual way using a Bally flexometer.
• dispersions 1, 2 and 3 are used according to the dressing method described in Examples 1 to 3, but in each case without the zinc oxide dispersion being used, dressings with split leather that have practically the same physical fastness properties are obtained if the procedure is otherwise the same little loss in processing properties, ie a drop of 1 to 2 notes when stacking.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Paper (AREA)
• Treatment And Processing Of Natural Fur Or Leather (AREA)
• Paints Or Removers (AREA)
• Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)
• Polymerisation Methods In General (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Synthetic Leather, Interior Materials Or Flexible Sheet Materials (AREA)

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• 1983
  • 1983-05-19 DE DE3318219A patent/DE3318219A1/de not_active Withdrawn
• 1984
  • 1984-05-14 EP EP19840105470 patent/EP0127055B1/fr not_active Expired
  • 1984-05-14 DE DE8484105470T patent/DE3462152D1/de not_active Expired
  • 1984-05-15 US US06/610,406 patent/US4581034A/en not_active Expired - Lifetime
  • 1984-05-17 JP JP59097662A patent/JPS59221400A/ja active Granted

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