WO1992000389A1 - Aqueous emulsion of filmogenic resins for finishing leather and leather splits, and its application process - Google Patents

Aqueous emulsion of filmogenic resins for finishing leather and leather splits, and its application process Download PDF

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Publication number
WO1992000389A1
WO1992000389A1 PCT/EP1991/001138 EP9101138W WO9200389A1 WO 1992000389 A1 WO1992000389 A1 WO 1992000389A1 EP 9101138 W EP9101138 W EP 9101138W WO 9200389 A1 WO9200389 A1 WO 9200389A1
Authority
WO
WIPO (PCT)
Prior art keywords
leather
foam
splits
finishing
aqueous emulsion
Prior art date
Application number
PCT/EP1991/001138
Other languages
English (en)
French (fr)
Inventor
Giovanni Tadiello
Giuseppe Li Bassi
Maria Carla Cattaneo
Davide Bortignon
Giuliano Bertozzo
Original Assignee
L. Lamberti S.P.A.
Ge.Ma.Ta. S.P.A.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by L. Lamberti S.P.A., Ge.Ma.Ta. S.P.A. filed Critical L. Lamberti S.P.A.
Publication of WO1992000389A1 publication Critical patent/WO1992000389A1/en

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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

Definitions

  • This invention relates to an aqueous emulsion of filmogenic resins for finishing leather and leather splits, and its application process.
  • leather will be used to indicate leather as such, leather splits, sheepskin, nappa, whole skins for upholstery, buffed leather and full grain leather.
  • the emulsion according to the invention contains one or more foaming agents and one or more foam stabilizers.
  • the present invention also relates to a process for applying the aqueous emulsions to leather, said process consisting of foaming the emulsion, applying it continuously in a thin layer to the leather with a roller machine, and drying the film obtained.
  • the leather finishing and leather split enhancement industry is still largely based on batch operations involving a large use of labour. There is therefore a tendency to reduce labour costs and increase cycle productivity by using continuous processes. There is also a further tendency to reduce the energy costs of the various operations and to minimize their environmental impact, for example by seeking to limit the use of volatile solvents where possible. It is difficult to obtain excellent results and to follow up this tendency. For example, in continuous finishing with synthetic resins, the so-called napping, it is difficult to obtain good covering of the leather surface, especially in the case of splits, without having to resort to repeated applications or to costly expedients. There is therefore a requirement for new or improved products and processes which enable a high quality of finish, high productivity and a low level of environmental pollution to be simultaneously obtained.
  • Finishing processes generally involve many stages (each divided into various steps), and which in the most general case comprise the following: applying a base layer to give the desired coloration (synthetic resins and pigments); - applying a synthetic resin layer to form a suitable substrate for preparing an embossed design (this operation can be combined with the preceding) ; applying a nitrocellulose resin layer to facilitate the pressing operation by eliminating problems of tackiness; pressing to form an embossed design; applying a surface finishing layer (nitrocellulose resins). These stages can be repeated individually or in sequence until the desired quality is obtained.
  • Filmogenic compounds are normally applied to leather by one of the three following types of application: 1. "Spray” application This can be carried out both on soft leather and on rigid splits. It is a batch process and is also lengthy in that it requires repeated passes to obtain good covering.
  • the filmogenic substance dissolved in a solvent or dispersed in water, is applied in the form of an aerosol with the result that at least 4 ⁇ # of the sprayed substance rebounds off the leather and is dispersed within the surrounding air. This rejected quantity is unrecoverable and has to be eliminated by treatment in suitable purifiers.
  • Excessively soft leather is "refused" by the rollers as they rotate in the same direction (and thus with their surfaces moving in opposition at different speeds) .
  • aqueous resin dispersions used contain a minimum of 6 ⁇ # of water, with consequent considerable drying problems.
  • This consists of applying a thin layer of resin onto a support web consisting of release paper, which is followed by the formation of the film, bonding to the substrate to be finished, generally by pressing, and successive drying or polymerization and removal of the finished substrate, with recovery of the release paper.
  • the process can be used for both soft and rigid leather, but the deposited film generally has a thickness of 0.2-0.4 mm, so giving it a plastic appearance, feel and consistency unless special techniques are used by which thicknesses less than 0.1 mm can be applied, but which require specially considered resins (such as polyurethane resins) .
  • resins such as polyurethane resins
  • the quantity of foaming agent is between 0.5% and 3# of the dry content of the emulsion.
  • alkaline salts of. fatty monoamides of sulphosuccinic acid have proved particularly active.
  • the quantity of foam stabilizer is between 0.4# and 2% of the dry content of the emulsion according to the invention.
  • the water quantity is between 4 ⁇ and 70 and the viscosity is between 1000 and 1500 mPas (Brookfield RVT 2 - 10 r.p.m., 20 ° C) .
  • an essential characteristic of the emulsions according to the invention is that they contain a foaming agent and a foam stabilizer.
  • the emulsion according to the invention is prepared by simply mixing together the various components normally used for leather finishing.
  • filmogenic resins of normal use polyacrylic or polyurethane resins are particularly suitable, however other resins (nitrile, butadiene, styrene, acrylic etc.) are not excluded.
  • These resins can be thermoplastic, self-crosslinking or co- crosslinking at variable temperatures not exceeding 100°C, or can contain unsaturations (for example acrylic) and therefore be crosslinkable by radiation (eg. by U.V. light). They enable film to be obtained having excellent mechanical strength (tough and scratch- resistant) , good adhesion to its support, flexibility, softness, feel and the desired aesthetic characteristics.
  • the emulsions according to the present invention can also contain a thickener to modify the final rheology of the emulsion and make it suitable for the application.
  • the mostly used thickeners include polyacrylic salts and their copolymers, and modified natural polymers, in particular carboxymethylcellulose.
  • the emulsions of the invention can also contain any other components required to obtain the desired aesthetic or functional characteristics provided they are properly chosen to ensure maximum compatibility with the aforesaid components so that they do not substantially influence the process.
  • dyes include dyes, pigments, waxes, feel modifiers, coalescence agents, crosslinking agents, catalysts, antifermenting agents, antimildew agents etc.
  • a high grade of finish is obtained for the leather by treating this with the following process: a) forming a foam by blowing air into an aqueous emulsion of filmogenic resins containing one or more foaming agents and one or more foam stabilizers in quantities such that the sum of said quantities is between 1% and 1% by weight of the dry substance and their weight ratio is between 0.2 and 4; b) applying the foam from step a) to the leather to be treated, using a roller; c) drying the treated leather at a temperature of between 50°C and 90°C; d) subsequent treatments.
  • aqueous emulsion according to the invention is introduced into an apparatus known as a "foamer" in which it undergoes intimate contact with air to produce a foam which can be of variable consistency and characteristics.
  • the air can be microdispersed to the extent of obtaining a gaseous emulsion.
  • the foam characteristics can be adjusted by adjusting the air/compound (volume) ratio (the ratio between the compound volume before and after foaming is known as the "foaming ratio"), and the machine operating parameters.
  • the foam density obtained can be between 20 and 900 g/1.
  • Foam ratios particularly suitable for the purposes of the present invention are between 1:2 and 1:6.
  • the preferred foam ratios are between 1:3 and 1:4, with a corresponding density of 250-350 g/1.
  • the foam prepared as described is fed to a roller finishing machine where it is deposited by an oscillating doctor blade onto a rotating steel roller engraved as for rotogravure printing and therefore known as a gravure-type roller.
  • the machine can also use a roller of different type engraved in a different pattern.
  • the gravure roller rotates in opposition to another roller to uniformly distribute the foam over the leather fed to the machine.
  • the leather is collected at the roller exit and fed to the subsequent drying operation.
  • the feed rate of the leather within the machine is between 4 and 20 m/min, and typically between 8 and 10 m/min.
  • rollers rotating in the same direction can consist of a bank of infrared ray generators, or a conventional hot air oven.
  • Drying is generally conducted at a temperature of between 50 ° C and 90°C, and preferably between 70°C and 8 ⁇ °C.
  • the drying can also be followed by crosslinking of the resins contained in the used emulsion. This can be done by thermal activation at a temperature not exceeding 100°C or by irradiation by UV light, depending on the type of resins used and on the crosslinking agents and catalysts introduced.
  • the final treatment of the leather coated and dried as described comprises the normal operations involving application of the intermediate resin layer, pressing to obtain embossed decorations and, where necessary, final varnishing with possibly nitrocellulose- based resin solutions.
  • This greater effectiveness of the process according to the invention compared with conventional methods means that a smaller number of passes are used to obtain the required characteristics (for example one pass is generally sufficient to obtain complete coverage with a formulation for base colouring) .
  • Very thin and completely transparent films can be obtained (reduced resin consumption) , while at the same time ensuring maximum covering uniformity and mechanical strength. In the case of splits, this for example enables excellent coverage to be obtained in a single pass with the application of a very small quantity of emulsion, this being obtainable in the known art only by using a preliminary rotopressing operation (to reduce the permeability and hence the emulsion absorption) .
  • e It is possible to apply with a single pass a much higher emulsion quantity than that applied in the known art. Whatever
  • VESLIC rubbing resistance dry and wet, to IUF 450: high Hot iron resistance: 200-220 C
  • the compound required for the base coating and pressing operations is prepared by mixing together the following compounds by mechanical stirring in the stated order:
  • pigment content 10 dry content 15%
  • Foaming agent (35% sodium octadecyl sulpho- succinamate in water) 3 parts
  • the compound prepared in this manner has a viscosity of 1300 mPas (Brookfield 2/10 r.p.m. at 20 ° C) .
  • Foaming
  • the set foaming ratio is 1:3. to obtain a foam of density 3 0 g/1. c.
  • the thickness of the foam deposited by the doctor blade on the applicator roller is 0.5 mm, the application being in one pass at 5 m/min.
  • Example 2 passes to deposit a total of 100 g/m of dry substance on the split, which is not rotopressed.
  • d. The traditional finishing operations are carried out as under point e of Example 1.
  • Example 1 Drying as in Example 1, point d, but at 5 m/min. d. The traditional finishing operations are carried out as under point e of Example 1.
  • VESLIC rubbing resistance IUF 450
  • dry felt/dry leather 500 490 495 b- wet felt/dry leather 150 (1) 145 (2) 148 (2)
  • EXAMPLE 4 Foam application system for base covering and resin, intermediate and layer and finish.
  • Foaming agent (35% sodium octadecyl sulpho- succinamate in water) 1.2 parts
  • Foam stabilizer (25% ammonium stearate in water) 1.5 parts 5- 35% polyacrylic thickener in soybean oil/white spirit 1 part
  • the compound has a viscosity of 1500 mPa.s (Brookfield RVT 2 - 10 g/min 20 ° C) 1?
  • the buffed goatskin is treated in the machine previously described in the general part of the invention as in Example 1), with a 0.6 mm thickness of foam deposited on the applicator roller, using 1
  • Example 2 passes, depositing a total of 150 g/m of dry substance.
  • e Drying in a hot air oven (60 C) at a rate of 5 m/min.
  • f Rotopressing, spraying of final coating, drying, drumming and final rotopressing are carried out, as in Example 5.
  • points e, f, g. h, i On examining the articles obtained in Examples 5 and 6 it can be seen that both have good coverage (a 50X microscopic examination shows a more uniform pigment distribution for Example 5) • The surface is more opaque in Example 5. which is an advantage in garments.
  • the comparison shows that using the method of Example 5 the application of the waterproofing base coating can be dispensed with, the base compound can be applied in a smaller number of passes, and the drying time can be reduced.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Synthetic Leather, Interior Materials Or Flexible Sheet Materials (AREA)
  • Treatment And Processing Of Natural Fur Or Leather (AREA)
PCT/EP1991/001138 1990-06-28 1991-06-20 Aqueous emulsion of filmogenic resins for finishing leather and leather splits, and its application process WO1992000389A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT02080090A IT1249019B (it) 1990-06-28 1990-06-28 Emulsione acquosa di resine filmogene per la finitura di pelli, cuoio e croste di pelle e relativo procedimento di applicazione
IT20800A/90 1990-06-28

Publications (1)

Publication Number Publication Date
WO1992000389A1 true WO1992000389A1 (en) 1992-01-09

Family

ID=11172256

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP1991/001138 WO1992000389A1 (en) 1990-06-28 1991-06-20 Aqueous emulsion of filmogenic resins for finishing leather and leather splits, and its application process

Country Status (3)

Country Link
AU (1) AU8095391A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
IT (1) IT1249019B (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
WO (1) WO1992000389A1 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5234913A (en) * 1991-03-06 1993-08-10 Burroughs Wellcome Co. Antiviral nucleoside combination
DE4230997A1 (de) * 1992-09-16 1994-03-24 Sandoz Ag Spritzbeständiger wässriger Schaum, dessen Herstellung und Verwendung
KR20030017835A (ko) * 2001-08-23 2003-03-04 주식회사 덕인 회전 마스크 패턴을 사용한 에스엘에스 공정 방법 및 그장치
ITUA20161537A1 (it) * 2016-03-10 2017-09-10 Ge Ma Ta Spa Linea per rifinire pelli che avanzano in modo continuo ed automatico per l'intero ciclo di rifinizione

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2129567A5 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) * 1971-03-12 1972-10-27 Rohm & Haas
CH542665A (de) * 1970-09-22 1973-11-30 Sandoz Ag Verfahren zur Nassbehandlung von porösen Materialien aus Kunststoff oder Leder

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH542665A (de) * 1970-09-22 1973-11-30 Sandoz Ag Verfahren zur Nassbehandlung von porösen Materialien aus Kunststoff oder Leder
FR2129567A5 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) * 1971-03-12 1972-10-27 Rohm & Haas

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5234913A (en) * 1991-03-06 1993-08-10 Burroughs Wellcome Co. Antiviral nucleoside combination
DE4230997A1 (de) * 1992-09-16 1994-03-24 Sandoz Ag Spritzbeständiger wässriger Schaum, dessen Herstellung und Verwendung
US6303665B1 (en) 1992-09-16 2001-10-16 Clariant Finance (Bvi) Limited Spray-resistant aqueous foam, its production and use
KR20030017835A (ko) * 2001-08-23 2003-03-04 주식회사 덕인 회전 마스크 패턴을 사용한 에스엘에스 공정 방법 및 그장치
ITUA20161537A1 (it) * 2016-03-10 2017-09-10 Ge Ma Ta Spa Linea per rifinire pelli che avanzano in modo continuo ed automatico per l'intero ciclo di rifinizione

Also Published As

Publication number Publication date
IT9020800A1 (it) 1991-12-28
IT1249019B (it) 1995-02-11
IT9020800A0 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1990-06-28
AU8095391A (en) 1992-01-23

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