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WO2024146876A1 - Non-solvent artificial leather polyurethane system and preparation process - Google Patents

Non-solvent artificial leather polyurethane system and preparation process Download PDF

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Publication number
WO2024146876A1
WO2024146876A1 PCT/EP2024/050004 EP2024050004W WO2024146876A1 WO 2024146876 A1 WO2024146876 A1 WO 2024146876A1 EP 2024050004 W EP2024050004 W EP 2024050004W WO 2024146876 A1 WO2024146876 A1 WO 2024146876A1
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WO
WIPO (PCT)
Prior art keywords
layer
polyurethane composition
weight
coat layer
range
Prior art date
Application number
PCT/EP2024/050004
Other languages
French (fr)
Inventor
Jian Feng XU
Zu Bao NIE
Hang Yu XU
Chun Yi Chen
Original Assignee
Basf Se
Basf (China) Company Limited
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 Basf Se, Basf (China) Company Limited filed Critical Basf Se
Publication of WO2024146876A1 publication Critical patent/WO2024146876A1/en

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/40—High-molecular-weight compounds
    • C08G18/48—Polyethers
    • C08G18/4825—Polyethers containing two hydroxy groups
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/12—Layered products comprising a layer of synthetic resin next to a fibrous or filamentary layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/40—Layered products comprising a layer of synthetic resin comprising polyurethanes
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/08—Processes
    • C08G18/10—Prepolymer processes involving reaction of isocyanates or isothiocyanates with compounds having active hydrogen in a first reaction step
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/08—Processes
    • C08G18/16—Catalysts
    • C08G18/18—Catalysts containing secondary or tertiary amines or salts thereof
    • C08G18/20—Heterocyclic amines; Salts thereof
    • C08G18/2009—Heterocyclic amines; Salts thereof containing one heterocyclic ring
    • C08G18/2027—Heterocyclic amines; Salts thereof containing one heterocyclic ring having two nitrogen atoms in the ring
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/08—Processes
    • C08G18/16—Catalysts
    • C08G18/22—Catalysts containing metal compounds
    • C08G18/222—Catalysts containing metal compounds metal compounds not provided for in groups C08G18/225 - C08G18/26
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/30—Low-molecular-weight compounds
    • C08G18/302—Water
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/30—Low-molecular-weight compounds
    • C08G18/32—Polyhydroxy compounds; Polyamines; Hydroxyamines
    • C08G18/3203—Polyhydroxy compounds
    • C08G18/3206—Polyhydroxy compounds aliphatic
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/40—High-molecular-weight compounds
    • C08G18/48—Polyethers
    • C08G18/4804—Two or more polyethers of different physical or chemical nature
    • C08G18/4812—Mixtures of polyetherdiols with polyetherpolyols having at least three hydroxy groups
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/40—High-molecular-weight compounds
    • C08G18/48—Polyethers
    • C08G18/4829—Polyethers containing at least three hydroxy groups
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/65—Low-molecular-weight compounds having active hydrogen with high-molecular-weight compounds having active hydrogen
    • C08G18/66—Compounds of groups C08G18/42, C08G18/48, or C08G18/52
    • C08G18/6666—Compounds of group C08G18/48 or C08G18/52
    • C08G18/667—Compounds of group C08G18/48 or C08G18/52 with compounds of group C08G18/32 or polyamines of C08G18/38
    • C08G18/6674—Compounds of group C08G18/48 or C08G18/52 with compounds of group C08G18/32 or polyamines of C08G18/38 with compounds of group C08G18/3203
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
    • C08G18/72—Polyisocyanates or polyisothiocyanates
    • C08G18/74—Polyisocyanates or polyisothiocyanates cyclic
    • C08G18/76—Polyisocyanates or polyisothiocyanates cyclic aromatic
    • C08G18/7657—Polyisocyanates or polyisothiocyanates cyclic aromatic containing two or more aromatic rings
    • C08G18/7664—Polyisocyanates or polyisothiocyanates cyclic aromatic containing two or more aromatic rings containing alkylene polyphenyl groups
    • C08G18/7671—Polyisocyanates or polyisothiocyanates cyclic aromatic containing two or more aromatic rings containing alkylene polyphenyl groups containing only one alkylene bisphenyl group
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06N—WALL, FLOOR, OR LIKE COVERING MATERIALS, e.g. LINOLEUM, OILCLOTH, ARTIFICIAL LEATHER, ROOFING FELT, CONSISTING OF A FIBROUS WEB COATED WITH A LAYER OF MACROMOLECULAR MATERIAL; FLEXIBLE SHEET MATERIAL NOT OTHERWISE PROVIDED FOR
    • D06N3/00—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof
    • D06N3/12—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof with macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds, e.g. gelatine proteins
    • D06N3/14—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof with macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds, e.g. gelatine proteins with polyurethanes
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06N—WALL, FLOOR, OR LIKE COVERING MATERIALS, e.g. LINOLEUM, OILCLOTH, ARTIFICIAL LEATHER, ROOFING FELT, CONSISTING OF A FIBROUS WEB COATED WITH A LAYER OF MACROMOLECULAR MATERIAL; FLEXIBLE SHEET MATERIAL NOT OTHERWISE PROVIDED FOR
    • D06N3/00—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof
    • D06N3/12—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof with macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds, e.g. gelatine proteins
    • D06N3/14—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof with macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds, e.g. gelatine proteins with polyurethanes
    • D06N3/145—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof with macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds, e.g. gelatine proteins with polyurethanes two or more layers of polyurethanes
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06N—WALL, FLOOR, OR LIKE COVERING MATERIALS, e.g. LINOLEUM, OILCLOTH, ARTIFICIAL LEATHER, ROOFING FELT, CONSISTING OF A FIBROUS WEB COATED WITH A LAYER OF MACROMOLECULAR MATERIAL; FLEXIBLE SHEET MATERIAL NOT OTHERWISE PROVIDED FOR
    • D06N3/00—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof
    • D06N3/12—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof with macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds, e.g. gelatine proteins
    • D06N3/14—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof with macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds, e.g. gelatine proteins with polyurethanes
    • D06N3/146—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof with macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds, e.g. gelatine proteins with polyurethanes characterised by the macromolecular diols used
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06N—WALL, FLOOR, OR LIKE COVERING MATERIALS, e.g. LINOLEUM, OILCLOTH, ARTIFICIAL LEATHER, ROOFING FELT, CONSISTING OF A FIBROUS WEB COATED WITH A LAYER OF MACROMOLECULAR MATERIAL; FLEXIBLE SHEET MATERIAL NOT OTHERWISE PROVIDED FOR
    • D06N3/00—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof
    • D06N3/12—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof with macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds, e.g. gelatine proteins
    • D06N3/14—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof with macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds, e.g. gelatine proteins with polyurethanes
    • D06N3/147—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof with macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds, e.g. gelatine proteins with polyurethanes characterised by the isocyanates used

Definitions

  • the present invention relates to artificial leather, and more particularly, to a non-solvent polyurethane composition for the use in artificial leather, an artificial leather prepared from the same, and a process for preparing the artificial leather.
  • CN 103797184B discloses a two-component non-solvent polyurethane system for artificial leathers, wherein the isocyanate index of the polyurethane system components is in the range from 101 to 140.
  • the artificial leathers prepared therefrom could be used in furniture, garment and footwear applications. However, the leathers cannot both meet softness, good curing and high peeling strength.
  • Figure 1 illustrates a process according to the invention for preparing artificial leather consisting of a top coat layer, a base coat layer and a substrate layer.
  • Figure 2 illustrates the cross section of the artificial leather according to the invention.
  • Figure 3 illustrates the cross section of the artificial leather, which comprises a permeation layer caused by the interaction between the polyurethane base coat layer and the fabric substrate layer.
  • relative humidity means the ratio of the partial pressure of water vapor in wet air to the saturation pressure of water at the same temperature.
  • isocyanate refers to an organic compound with one or more isocyanate groups.
  • Diisocyanate refers to an organic compound with two (2) isocyanate groups.
  • Polyisocyanate refers to an organic compound with three (3) or more isocyanate groups.
  • polyol refers to an organic compound with two or more hydroxyl (- OH) groups.
  • the polyol component (A) comprises water at an amount of 0.2 to 0.4% by weight, based on the overall weight of the polyol component (A). It is surprisingly found that the addition of water at specified amount is important for the desired compromise between the softness, and the curing and peeling strength. Hence, the water content is in the range of 0.2 to 0.4% by weight, preferably in the range of from 0.22 to 0.38% by weight, more preferably from 0.25 to 0.35% by weight.
  • polyetherols When polyetherols are employed, these are generally obtained by known methods, for example by anionic polymerization using alkali metal hydroxides as catalysts and with addition of a starter molecule comprising multiple reactive hydrogen atoms in attachment, from one or more alkylene oxides selected from propylene oxide (PO) and ethylene oxide (EO), butylene oxide and tetrahydrofuran.
  • the alkylene oxides may be used individually, alternatingly in succession or as mixtures.
  • the use of an EO-PO mixture leads to a polyether polyol having randomly distributed PO/EO units.
  • Thermal delay catalysts are known and comprise for example acid-blocked, for example carboxylic acid-blocked and especially formic acid-blocked amine catalysts, for example tertiary amine catalysts. These are obtainable for example by reaction of acids with bases, in the presence or absence of a solvent.
  • the acid component used is preferably carboxylic acids, particularly oleic acid, formic acid, acetic acid, ethylhexyl acid, phenol, ricinoleic acid, linoleic acid and/or p-toluenesulfonic acid.
  • amine catalysts to be blocked it is preferable to use triethylenediamine, dimethylamino- N-methylpiperazine, N,N-diphenyl-N-methylamine, bis(N,N-dimethylaminoethyl) ether, N,N- dimethylaminoethoxyethanol and/or DBU.
  • These blocked catalysts are usually present in a solvent/dispersant.
  • Glycols such as propylene glycol, dipropylene glycol, ethylene glycol and/or diethylene glycol, are preferably suitable as solvent/dispersant.
  • the thermal delay catalyst is preferably at an amount of from 0.1 to 0.5% by weight and the organometallic catalyst is preferably used at an amount of from 0.03 to 0.3% by weight, based on the overall weight of the polyol component (A).
  • the weight ratio between the thermal delay catalyst and the organometallic catalyst is preferably in the range of from 1 :1 to 3: 1 , more preferably from 1:1 to 2: 1.
  • the substrate layer can be any layer capable of forming an adhering bond with the resulting base coat layer.
  • the base coat layer formed by the polyurethane composition and the substrate layer have an interaction permeation percentage in the range from 10% to 30%. It is surprisingly found in the present invention that the Pll and substrate interacting permeation plays a role in achieving the desired compromise between the softness and peeling strength. If the permeation is less than 10%, then peeling strength is not good; if the permeation is more than 30%, then softness is not good. Hence, the permeation is in the range of 10-30%, and preferably 15-25%.
  • Suitable release layers are typically known in the pertinent art as "release paper".
  • suitable release layers are layers, for example foils, of metal, plastic or paper.
  • the method of applying the top coat layer(s) in step ii) can be any method whereby it is possible to form a coating layer or sheet-like material with desired thickness. Examples of the method include dip coating, knife coating, roller coating and spin coating.
  • the top coat layer is preferably dried, for example by allowing it to flash off or heating, before the step iii) of applying the polyurethane composition. In the event that two or more layers of top coat are applied, it is preferable to dry the applied layer before the subsequent layer of top coat is applied.
  • the polyurethane composition can generally be applied in step iii) using any method whereby it is possible to form a coating layer or sheet-like material with desired thickness. Examples of the method include dip coating, knife coating, roller coating and spin coating.
  • the base coat layer is partially cured, for example by allowing it to flash off or heating, before the step iv) of applying a substrate layer.
  • the time of partial curing is 10 seconds (sec) to 8 min, more preferably 10 sec to 5 min, and especially preferably 20 to 200 sec. This is especially advantageous for achieving the desired interaction permeation percentage in the range from 10% to 30%.
  • the step (iv) of the process according to the present invention comprises attaching a substrate layer to the base coat layer.
  • the substrate layer is applied to the base coat layer by bringing the former into contact with the latter and pressing to form a laminate.
  • the contact pressure is preferably between 0.01 and 6 bar and more preferably between 0.05 and 5 bar.
  • Step (v) of the process according to the invention comprises curing the laminate.
  • This curing may be hastened by temperature elevation, for example in an oven, or by irradiation, for example with microwave radiation or infrared radiation.
  • the curing is effected at temperatures in the range from 80 to 150°C, more preferably from 110 to 140°C.
  • the curing operation continues until the reaction of isocyanate groups with OH-functional groups is essentially complete.
  • the duration of the curing operation is preferably in the range from 0.5 to 20 minutes, more preferably in the range from 1 to 10 minutes and more particularly in the range from 2 to 5 minutes.
  • the process of the present invention may be carried out as a continuous operation or as a batch operation. It is preferably carried out as a continuous operation.
  • the release layer and the substrate layer are present in the form of bands which are continuously advanced and treated according to the process of the present invention.
  • the bands are generally from 10 to 500 meters and preferably from 20 to 200 meters in length.
  • the band speed is typically in the range from 5 to 15 m/min.
  • the substrate layer forms a quasi substrate band.
  • the substrate layer is preferably unwound off a spindle at the start of the process.
  • This continuous process of the present invention provides artificial leather comprising top coat layer, base coat layer and substrate layer, as a process product which is likewise present in the form of a band.
  • the product obtained is preferably wound up on a spindle.
  • the layer of a top coat can be applied by spraying, by knife coating or by a wide slot die.
  • the polyurethane composition may subsequently be applied by spraying or by knife coating. Any combination of these production variants is possible.
  • L2095 Poly propylene oxide and ethylene oxide from BASF, Molecular weight is 5000, Fn
  • L2043 Poly propylene oxide and ethylene oxide from BASF, Molecular weight is 4000, Fn
  • EP-P-16 Leveling agent from Evonik Company
  • Dabco 8154 Amine-based delay catalyst from Evonik Bicat 3228: Metal catalyst from Shepherd Company
  • Haptex CC 6945/90 C-CH Water-based polyurethane dispersion with solid content
  • Astacin Hardener Cl Crosslinker with 70.0% solid content from BASF
  • Favini B100 Release paper from Favini
  • Formulation of a top coat layer was prepared by blending the ingredients by sequence according to Table 1, and then were applied with a thickness of 100 pm within 4 hours by knife coating on a Favini B100 release paper, followed by drying in Oven #1 (as shown in Figure 1) at 80°C for 2 min and at 120°C for 2 min to form a dried top coat layer.
  • Oven #1 as shown in Figure 1
  • the formulations of 2- component non-solvent Pll system were prepared by blending the ingredients by sequence according to Table 2, and then applied with a thickness of 350 pm by knife coating on top of the dried top coat layer, and heated in Oven #2 at 80 to 140°C for 1 to 5 min to form a base coat layer.
  • a polyester-type fabric substrate layer was attached on the base coat layer, followed by pressing, and heated in Oven #3 at 120 to 140°C for 2 to 10 min.
  • Pll artificial leather was obtained after stripping the release paper.
  • Example 10 In order to test the Pll and Fabric interacting permeation, an additional Example 10 was prepared by repeating Example 2, except for the time of the partial curing in Oven #2. The results are shown in Table 3:
  • Open time is the time when the viscosity of the components (A) and (B), after being mixed, reaches to 5000 mPa.s. An open time of > 5 min meet the requirement.
  • Curing property of the base coat layer was evaluated by using nail to press the top coat layer of the laminate and then visually evaluating according to the following grades:
  • Grade 2 nail print rebound (7 sec - 9 sec);
  • Peeling strength test was carried out to the Pll laminates that were just peeled from the release paper after curing, and the testing should be finished within 20 min, including specimen preparation and testing.
  • the test follows the standard SATRA TM 411.
  • the peeling strength was tested after 48 hours.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Dispersion Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Synthetic Leather, Interior Materials Or Flexible Sheet Materials (AREA)

Abstract

The present invention relates to a non-solvent polyurethane composition for the use in artificial leather, which comprises a polyol component (A) and an isocyanate component (B), wherein the isocyanate component (B) has an NCO content of from 10% to 12% by weight, and the polyol component (A) comprises a chain extender at an amount of 0 to 3% by weight and water at an amount of 0.2 to 0.4% by weight, based on the overall weight of the polyol component (A). The invention also relates to an artificial leather prepared from the said composition, and a process for preparing the artificial leather.

Description

Non-Solvent Artificial Leather Polyurethane System and Preparation Process
TECHNICAL FIELD
The present invention relates to artificial leather, and more particularly, to a non-solvent polyurethane composition for the use in artificial leather, an artificial leather prepared from the same, and a process for preparing the artificial leather.
BACKGROUND
The use of polyurethane for production of artificial leathers is known. Artificial leathers according to the type of polyurethane systems are typically classified into solvent artificial leathers and non-solvent (or aqueous) artificial leathers. Non-solvent artificial leathers produced from two- component polyurethane systems are more environmental-friendly than traditional solvent artificial leathers. However, non-solvent artificial leathers cannot be as soft as solvent-based leather. The technical difficulty is that: if softness is achieved, then the curing and peeling strength of the leather is not satisfactory, and vice versa.
CN 103797184B discloses a two-component non-solvent polyurethane system for artificial leathers, wherein the isocyanate index of the polyurethane system components is in the range from 101 to 140. The artificial leathers prepared therefrom could be used in furniture, garment and footwear applications. However, the leathers cannot both meet softness, good curing and high peeling strength.
SUMMARY OF THE INVENTION
The problem addressed by the present invention is therefore to provide an artificial leather which is obtainable in an environmentally friendly manner and which can have a satisfactory softness without compromising the curing and peeling strength.
This problem is solved by a non-solvent polyurethane composition for the use in artificial leather, comprising a polyol component (A) and an isocyanate component (B), wherein the isocyanate component (B) has an NCO content of from 10% to 12% by weight, and the polyol component (A) comprises a chain extender at an amount of 0 to 3% by weight and water at an amount of 0.2 to 0.4% by weight, based on the overall weight of the polyol component (A). The present invention further provides an artificial leather, comprising a top coat layer, a base coat layer and a substrate layer, wherein the base coat layer is formed from the polyurethane composition according to the invention.
The present invention finally provides a process for production of the artificial leather according to the invention, said process comprising i) providing a release layer, ii) applying one or more than one layer of a top coat to the release layer to an overall top coat layer thickness in the range from 1 to 500 pm, iii) applying the polyurethane composition according to the invention to the top coat layer(s) and partially curing the composition to form a base coat layer with the thickness in the range from 0.1 to 1.0 mm, iv) attaching a substrate layer to the base coat layer to form a laminate, v) curing the laminate, and vi) separating the release layer from the cured laminate.
DESCRIPTION OF FIGURES
Figure 1 illustrates a process according to the invention for preparing artificial leather consisting of a top coat layer, a base coat layer and a substrate layer.
Figure 2 illustrates the cross section of the artificial leather according to the invention.
Figure 3 illustrates the cross section of the artificial leather, which comprises a permeation layer caused by the interaction between the polyurethane base coat layer and the fabric substrate layer.
DETAILED DESCRIPTION OF THE INVENTION
Unless defined otherwise, all technical and scientific terms used herein have the meaning commonly understood by a person skilled in the art to which the invention belongs. As used herein, the following terms have the meanings ascribed to them below, unless specified otherwise.
As used herein, the articles "a" and "an" refer to one or to more than one (i.e. , to at least one) of the grammatical object of the article or component.
Unless otherwise identified, all percentages (%) are “percent by weight", denoted as wt.%. Unless otherwise identified, the molecular weight of each component or polymer means a weight-average molecular weight.
Unless otherwise identified, relative humidity (R.H.) means the ratio of the partial pressure of water vapor in wet air to the saturation pressure of water at the same temperature.
Unless otherwise identified, isocyanate group refers to the organic radical -N=C=O, denoted also as -NCO.
Unless otherwise identified, isocyanate refers to an organic compound with one or more isocyanate groups. Diisocyanate refers to an organic compound with two (2) isocyanate groups. Polyisocyanate refers to an organic compound with three (3) or more isocyanate groups.
Unless otherwise identified, polyol refers to an organic compound with two or more hydroxyl (- OH) groups.
Unless otherwise identified, OH value (sometime also termed as “hydroxyl value” or “hydroxyl number”) is a measure of the concentration of the hydroxyl groups in a polyol or a polyol component. The OH value is calculated as the number of milligrams of potassium hydroxide required to neutralize the acetic acid taken up on acetylation of one gram of a chemical substance (in the present invention, a polyol, or a polyol component) that contains free hydroxyl groups.
Unless otherwise identified, functionality (abbreviated as “Fn”) of a polyol or a polyol component refers to the number or average number of OH groups per molecule.
Non-solvent polyurethane composition for the use in artificial leather
The polyurethane composition of the present invention comprises a polyol component (A) and an isocyanate component (B).
Polyol component (A)
The polyol component (A) comprises a chain extender at an amount of 0 to 3% by weight. In the present invention, the chain extender is meant to represent compounds having 2 isocyanatereactive hydrogen atoms and molecular weights in the range from 42 to less than 400 g/mol.
Preference is given to using 2-functional alcohols having molecular weights in the range from 60 to 150 g/mol. Examples are ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, dipropylene glycol or tripropylene glycol. 1,4-Butanediol is especially preferably used.
According to the present invention, the chain extender is used at an amount from 0 to 3% by weight, based on the overall weight of the polyol component (A). It is surprisingly found that the addition of a chain extender is beneficial to improving the curing and peeling strength. However, if the excess of a chain extender is added, the softness will be reduced undesirably. Hence, the chain extender is added at an amount in the range of 0 to 3% by weight, preferably 1 to 2.5% by weight, more preferably 1.5 to 2.2% by weight.
The polyol component (A) comprises water at an amount of 0.2 to 0.4% by weight, based on the overall weight of the polyol component (A). It is surprisingly found that the addition of water at specified amount is important for the desired compromise between the softness, and the curing and peeling strength. Hence, the water content is in the range of 0.2 to 0.4% by weight, preferably in the range of from 0.22 to 0.38% by weight, more preferably from 0.25 to 0.35% by weight.
The polyol component (A) comprises polyesterols and/or polyetherols, preferably consists of polyetherols. These are commonly known and described for example in "Kunststoffhandbuch Polyurethane" Gunter Oertel, Carl-Hanser-Verlag, 2nd edition 1983, chapter 3.1.1. Alternative designations likewise customary in the pertinent art are polyether polyols or polyether alcohols on the one hand and polyester polyols or polyester alcohols on the other.
When polyesterols are employed, these are typically obtained by condensation of polyfunctional alcohols having from 2 to 12 carbon atoms, preferably from 2 to 6 carbon atoms, with polyfunctional carboxylic acids having from 2 to 12 carbon atoms, examples being succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, maleic acid, fumaric acid and preferably phthalic acid, isophthalic acid, terephthalic acid and the isomeric naphthalenedicarboxylic acids.
When polyetherols are employed, these are generally obtained by known methods, for example by anionic polymerization using alkali metal hydroxides as catalysts and with addition of a starter molecule comprising multiple reactive hydrogen atoms in attachment, from one or more alkylene oxides selected from propylene oxide (PO) and ethylene oxide (EO), butylene oxide and tetrahydrofuran. The alkylene oxides may be used individually, alternatingly in succession or as mixtures. The use of an EO-PO mixture leads to a polyether polyol having randomly distributed PO/EO units. It is possible to begin by using a PO-EO mixture and then, prior to termination of the polymerization, continue use of just PO or EO, the product then being a polyether polyol having a PO end-cap or, respectively, an EO end-cap. In a preferable embodiment, the polyetherols employed in the present invention have an ethylene oxide (EO) end-cap.
Starter molecules used are typically NH- or OH-functional compounds such as water, amines or alcohols. Preference is given to use di- to hexahydric alcohols, such as ethanediol, 1 ,2- propanediol, 1,3-propanediol, diethylene glycol, dipropylene glycol, 1,4-butanediol, 1 ,6- hexanediol, glycerol, trimethylolpropane, pentaerythritol and/or sorbitol.
In one preferred embodiment, the polyol component (A) comprises one or more constituents selected from
(a-1) a polyol, preferably a polyether polyol, having a number-average molecular weight in the range from 500 g/mol to less than 4500 g/mol, and
(a-2) a polyol, preferably a polyether polyol, having a number-average molecular weight in the range from 4500 g/mol to 8000 g/mol.
In one preferred embodiment, component (a-1) comprises a polyetherol or a polyesterol, more preferably a polyether polyol, having a number average molecular weight in the range from 500 to less than 4500 g/mol, preferably in the range from 1500 to 4500 g/mol, and more preferably in the range from 2800 to 4200 g/mol as components (a-1).
The component (a-1) typically has an average functionality of 1.8 to 3, more preferably of 1.9 to 2.1 and especially of 2.0. Functionality here refers to the "theoretical OH functionality" calculated from the functionality of the starter molecules used.
Polypropylene oxide)-(ethylene oxide) is more preferably used as component (a-1). More particularly, polypropylene oxide)-(ethylene oxide) having a number average molecular weight in the range from 3500 to 4200 g/mol is used.
The component (a-1) is typically present in component (A) in an amount from 45% to 70% by weight and preferably from 50% to 60% by weight, based on the overall weight of the polyol component (A). In one preferred embodiment, the component (a-2) utilize a polyetherol or a polyesterol and more preferably a polyether polyol having a number average molecular weight in the range from 4000 to 8000 g/mol, preferably in the range from 4500 to 7000 g/mol and more preferably in the range from 4500 to 6000 g/mol.
The component (a-2) typically has an average functionality of 1.9 to 6, more preferably of 2.3 to 4 and especially of 3.0. Functionality here refers to the "theoretical OH functionality" calculated from the functionality of the starter molecules used.
Component (a-2) is more preferably a polyether polyol obtainable by propoxylation and/or ethoxylation of glycerol or trimethylolpropane, especially with an EO end-block. This polyether polyol preferably has a number average molecular weight in the range from 4500 to 6000 g/mol.
The component (a-2) is typically present in component (A) in an amount from 30% to 55% by weight and preferably from 40% to 50% by weight, based on the overall weight of the polyol component (A).
Isocyanate component (B)
The isocyanate component (B) has an NCO content of from 10% to 12% by weight. It is surprisingly found that the specified NCO content is important for the desired compromise between the softness, and the curing and peeling strength. Hence, the NCO content is in the range of 10 to 12% by weight, preferably 10.5 to 11.5% by weight.
The isocyanate component (B) comprises customary aliphatic, cycloaliphatic and, more particularly, aromatic di- and/or polyisocyanates. Preference is given to using tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI) and mixtures of diphenylmethane diisocyanate and polyphenylene polymethylene polyisocyanates (polymeric MDI), and especially diphenylmethane diisocyanate (monomeric MDI).
The isocyanates or else hereinbelow described isocyanate prepolymers may also be in a modified state, for example through incorporation of uretidione, carbamate, isocyanurate, carbodiimide or allophanate groups. It is further possible to use blends of the various isocyanates.
The isocyanate component (B) can also comprise, and in a preferred embodiment, consist of polyisocyanate prepolymers. These prepolymers are known in the prior art. They are prepared in a conventional manner by reacting above-described monomeric isocyanates with hereinabove described polyesterols or polyetherols to form the prepolymer. The reaction may for example be carried out at temperatures of about 80°C.
A mixture comprising diphenylmethane diisocyanate and polypropylene oxide)-(ethylene oxide), especially polypropylene oxide)-(ethylene oxide) having a number average molecular weight in the range from 3500 to 4200, is used with particular preference as isocyanate component (B). In a more preferable embodiment, the polyisocyanate prepolymer used as isocyanate component (B) is obtainable by reacting 4,4’-MDI with a polyether polyol.
The amount of the polyol component (A) and the isocyanate component (B) is preferably selected such that the NCO index is in the range from 101 to 140, preferably in the range from 105 to 130, and more particularly in the range from 110 to 120.
Catalyst
In one preferred embodiment, the reaction of components (A) and (B) takes place in the presence of a catalyst. This is more preferably a constituent part of component (A). The customary and known polyurethane formation catalysts are optionally used as catalysts for producing the polyurethane of the present invention, examples being thermal delay catalysts, such as thermal delay amine catalysts.
Thermal delay catalysts are known and comprise for example acid-blocked, for example carboxylic acid-blocked and especially formic acid-blocked amine catalysts, for example tertiary amine catalysts. These are obtainable for example by reaction of acids with bases, in the presence or absence of a solvent. In the case of acid-blocked catalysts, the acid component used is preferably carboxylic acids, particularly oleic acid, formic acid, acetic acid, ethylhexyl acid, phenol, ricinoleic acid, linoleic acid and/or p-toluenesulfonic acid. By way of amine catalysts to be blocked it is preferable to use triethylenediamine, dimethylamino- N-methylpiperazine, N,N-diphenyl-N-methylamine, bis(N,N-dimethylaminoethyl) ether, N,N- dimethylaminoethoxyethanol and/or DBU. These blocked catalysts are usually present in a solvent/dispersant. Glycols, such as propylene glycol, dipropylene glycol, ethylene glycol and/or diethylene glycol, are preferably suitable as solvent/dispersant.
In one preferred embodiment, the catalyst component is a combination of the thermal delay catalyst and an organometallic catalyst. It is surprisingly found that the combined catalysts make it possible to improve the peeling maintenance, which is measured 48 hours after the curing of the base coat layer and after the laminate is peeled from the release layer. Here, the organometallic catalyst is preferably selected from the group consisting of metal salts catalyst, including bismuth and zinc salts. In a more preferable embodiment, the zinc salts comprises zinc carboxylates, such as zinc neodecanoate or zinc octoate.
When the aforementioned combined catalyst is used, the thermal delay catalyst is preferably at an amount of from 0.1 to 0.5% by weight and the organometallic catalyst is preferably used at an amount of from 0.03 to 0.3% by weight, based on the overall weight of the polyol component (A). The weight ratio between the thermal delay catalyst and the organometallic catalyst is preferably in the range of from 1 :1 to 3: 1 , more preferably from 1:1 to 2: 1.
Other
Optionally, the polyurethane composition according to the invention can comprise a blowing agent, a filler or any other adjuvants such as a leveling agent that are well known in the field of polyurethane. All the adjuvants are more preferably a constituent part of component (A). The type and amount thereof could be selected as desired by one skilled in the art, to the extent that the use thereof does not impair the desirable properties of the present invention.
In a preferable embodiment, the adjuvant used is a leveling agent which is commercially available from Evonik Company.
Artificial leather
The present invention further provides an artificial leather, comprising a top coat layer, a base coat layer and a substrate layer, wherein the base coat layer is formed from the polyurethane composition according to the present invention.
Top coat layer
The top coats used in the invention can be of the type typically used in the production of leather or leather imitations. These comprise polyurethane-based top coats, such as solventborne polyurethane coats or waterborne polyurethane dispersion coats, preferably waterborne polyurethane dispersion coats. Suitable coats may be based on a linear MDI-polyether-based polyurethane and be in a state of solution in DMF for example. Coats based on aliphatic isocyanates and polyesters or polyethers are likewise conceivable. These coats can be cured by addition of curatives, for example by addition of carbodiimide-based curative. The amount of curative added controls the hardness of the top coat layer obtained. The hardness of the top coat layer is preferably conformed to the hardness of the polyurethane layer. Preferably, the polyurethane coats comprise addition agents, such as dyes or pigments. Such waterborne polyurethane coats are described for example in PCT/CN2020/084834, which is incorporated herein by reference. Commercially available examples of waterborne polyurethane coat are Haptex CC 6945/90 C-CH from BASF SE. There may be one layer, or two or more layers of the top coat in the artificial leather of the present invention, and in the latter case, the starting materials for producing the respective layers of the top coat can be the same or different.
The overall thickness of the top coat layer(s) is in the range from 1 to 500 pm, preferably in the range from 5 to 150 pm and more preferably in the range from 10 to 120 pm.
Base coat layer
The base coat layer is prepared from the polyurethane composition according to the present invention. The polyurethane composition is the same as described above, and is thus not repeated here.
The thickness of the base coat layer is in the range from 0.01 millimeters (mm) to 20 mm, preferably in the range from 0.05 mm to 10 mm and more preferably in the range from 0.1 mm to 1.0 mm.
Substrate layer
In principle, the substrate layer can be any layer capable of forming an adhering bond with the resulting base coat layer.
Substrate layer thickness is typically in the range from 0.01 millimeters (mm) to 20 mm, preferably in the range from 0.1 mm to 10 mm and more particularly in the range from 0.3 mm to 5 mm.
Examples of suitable substrate layers are layers, for example foils, of metal, plastic, leather and/or fabric materials.
Various kinds of substrate layers are possible for the present invention, examples being: A fabric substrate layer: In this case the substrate layer can consist of one or more, identical or different, firmly interconnected plies, for example of narrowly or widely meshed wovens, knits, braids, networks (net cloths).
Batt substrate layer: sheetlike structures composed of randomly disposed fibers (examples being felts and fibrous webs), which may preferably be bound together by a binder. Batt substrate layers are usually cellulosic or textile batts consolidated with water-insoluble impregnants.
Fibrous substrate layer: articles of manufacture composed of loose, randomly disposed fibers which are consolidated by plastics being used as a binder. They are obtained for example by adhering together leather fibers (preferably obtainable from leather waste, for example from vegetable-tanned leather) with 8-40% by weight of a binder.
Foil substrate layer: articles of manufacture comprising (preferably homogeneous) foils composed of metal or plastic, for example rubber, PVC, polyamides, interpolymers and the like. A foil substrate layer preferably comprises no incorporated fiber.
One preferred embodiment utilizes a fabric layer as substrate layer. When a fabric layer is used, the following materials will be particularly suitable to produce the fabric layer: cotton, linen, polyester, polyamide and/or polyurethane.
In one preferable embodiment, the base coat layer formed by the polyurethane composition and the substrate layer have an interaction permeation percentage in the range from 10% to 30%. It is surprisingly found in the present invention that the Pll and substrate interacting permeation plays a role in achieving the desired compromise between the softness and peeling strength. If the permeation is less than 10%, then peeling strength is not good; if the permeation is more than 30%, then softness is not good. Hence, the permeation is in the range of 10-30%, and preferably 15-25%.
For the definition of the interaction permeation percentage, reference can be made to the Examples of the present application.
Process for production of the artificial leather
The present invention provides a process for production of the artificial leather according to the invention, said process comprising i) providing a release layer, ii) applying one or more than one layer of a top coat to the release layer to an overall top coat layer thickness in the range from 1 to 500 pm, iii) applying the polyurethane composition according to the invention to the top coat layer(s) and partially curing the composition to form a base coat layer with the thickness in the range from 0.1 to 1.0 mm, iv) attaching a substrate layer to the base coat layer to form a laminate, v) curing the laminate, and vi) separating the release layer from the laminate.
The process of the present invention comprises a release layer in step i). In principle, any layer is useful as release layer that allows polyurethane system components to be applied thereto and reacted to form polyurethane and the resulting polyurethane to be separated again from the release layer.
Release layer thickness is typically in the range from 0.001 millimeters (mm) to 10 mm, preferably in the range from 0.01 mm to 5 mm and more particularly in the range from 0.1 mm to 2 mm.
Suitable release layers are typically known in the pertinent art as "release paper". Examples of suitable release layers are layers, for example foils, of metal, plastic or paper.
In one preferred embodiment, the release layer used is a paper layer optionally coated with a plastic. Preferably, the paper layer here is coated with a polyolefin, preferably polypropylene. Alternatively, the paper layer is preferably coated with silicone.
In an alternative preferred embodiment, the release layer used is a PET layer (= polyethylene terephthalate) optionally coated with a plastic. Preferably, the PET layer here is coated with a polyolefin, preferably polypropylene. Alternatively, the PET layer is preferably coated with silicone.
Examples of suitable release layers are commercially available. Examples of renowned manufacturers in the pertinent art include Favini (Italy).
The release layers used may have a smooth or uneven surface. The type of release layer depends on the surface desired for the polymer layer resulting from the process of the present invention. When it is desired for a resulting polyurethane layer to have a smooth surface, the release layer will likewise have a smooth surface. When a resulting polyurethane layer is desired to have an uneven or patterned surface, the release layer will likewise have an uneven or patterned surface. Preferably, the release layer is patterned such that the product has a leather grain.
Step ii) comprises applying a top coat layer(s) to the release layer. For details concerning the top coat layer(s), reference can be made to the above-described “Top coat layer” part.
The method of applying the top coat layer(s) in step ii) can be any method whereby it is possible to form a coating layer or sheet-like material with desired thickness. Examples of the method include dip coating, knife coating, roller coating and spin coating.
The top coat layer is preferably dried, for example by allowing it to flash off or heating, before the step iii) of applying the polyurethane composition. In the event that two or more layers of top coat are applied, it is preferable to dry the applied layer before the subsequent layer of top coat is applied.
The polyurethane composition can generally be applied in step iii) using any method whereby it is possible to form a coating layer or sheet-like material with desired thickness. Examples of the method include dip coating, knife coating, roller coating and spin coating.
For details concerning the base coat layer formed by the polyurethane composition in step iii), reference can be made to the above-described “Base coat layer” part.
The base coat layer is partially cured, for example by allowing it to flash off or heating, before the step iv) of applying a substrate layer. In one preferable embodiment, the time of partial curing is 10 seconds (sec) to 8 min, more preferably 10 sec to 5 min, and especially preferably 20 to 200 sec. This is especially advantageous for achieving the desired interaction permeation percentage in the range from 10% to 30%.
The step (iv) of the process according to the present invention comprises attaching a substrate layer to the base coat layer. The substrate layer is applied to the base coat layer by bringing the former into contact with the latter and pressing to form a laminate. The contact pressure is preferably between 0.01 and 6 bar and more preferably between 0.05 and 5 bar.
Step (v) of the process according to the invention comprises curing the laminate. This curing may be hastened by temperature elevation, for example in an oven, or by irradiation, for example with microwave radiation or infrared radiation. In one preferred embodiment, the curing is effected at temperatures in the range from 80 to 150°C, more preferably from 110 to 140°C.
The curing operation continues until the reaction of isocyanate groups with OH-functional groups is essentially complete. The duration of the curing operation is preferably in the range from 0.5 to 20 minutes, more preferably in the range from 1 to 10 minutes and more particularly in the range from 2 to 5 minutes.
Step (vi) of the process according to the present invention comprises separating the release layer from the laminate. The separating may be effected by customary methods known in the prior art. For example, the release layer is peeled off the laminate when the adjacent base coat layer is preferably in a fully cured state before the release layer is separated off.
The process of the present invention may be carried out as a continuous operation or as a batch operation. It is preferably carried out as a continuous operation.
Continuous in this context is to be understood as meaning that the release layer and the substrate layer are present in the form of bands which are continuously advanced and treated according to the process of the present invention. The bands are generally from 10 to 500 meters and preferably from 20 to 200 meters in length. The band speed is typically in the range from 5 to 15 m/min.
In one continuous process of the present invention, the release layer forms a quasi release band. The release layer is preferably unwound off a spindle at the start of the process, the release layer removed from the polyurethane layer in the process of the present invention may preferably be wound up again on a spindle. This wound-up release layer may be reused in the process of the present invention; that is, it is reusable. The wound-up release layer is preferably reused at least 2 to 5 times.
In one continuous process of the present invention, the substrate layer forms a quasi substrate band. The substrate layer is preferably unwound off a spindle at the start of the process.
This continuous process of the present invention provides artificial leather comprising top coat layer, base coat layer and substrate layer, as a process product which is likewise present in the form of a band. The product obtained is preferably wound up on a spindle. When the process of production is continuous, the layer of a top coat can be applied by spraying, by knife coating or by a wide slot die. The polyurethane composition may subsequently be applied by spraying or by knife coating. Any combination of these production variants is possible.
The examples which follow illustrate the invention.
EXAMPLES
The following input materials were used:
L2095: Poly propylene oxide and ethylene oxide from BASF, Molecular weight is 5000, Fn
= 3
L2043: Poly propylene oxide and ethylene oxide from BASF, Molecular weight is 4000, Fn
= 2
BDO: 1,4-Butanediol
EP-P-16: Leveling agent from Evonik Company
Dabco 8154: Amine-based delay catalyst from Evonik Bicat 3228: Metal catalyst from Shepherd Company
Lupranate MS: Diphenylmethane 4,4’-diisocyanate (MDI) from BASF
Haptex CC 6945/90 C-CH: Water-based polyurethane dispersion with solid content
34.5% from BASF
Permutex PP-39-611 : Pigment Black with solid content 20.0% from Stahl
Permutex RM 4456: Thickener with solid content 28.0% form Stahl
Astacin Hardener Cl: Crosslinker with 70.0% solid content from BASF
Astacin Hardener CA: Crosslinker with 60.0% from BASF
BYK 348 Wetting agent with 100% solid content form BYK
Favini B100: Release paper from Favini
Preparation of PU artificial leather comprising a top coat layer, a base coat layer and a substrate layer Table 1 Formulation of the top coat layer
Figure imgf000016_0001
Formulation of a top coat layer was prepared by blending the ingredients by sequence according to Table 1, and then were applied with a thickness of 100 pm within 4 hours by knife coating on a Favini B100 release paper, followed by drying in Oven #1 (as shown in Figure 1) at 80°C for 2 min and at 120°C for 2 min to form a dried top coat layer. Next, the formulations of 2- component non-solvent Pll system were prepared by blending the ingredients by sequence according to Table 2, and then applied with a thickness of 350 pm by knife coating on top of the dried top coat layer, and heated in Oven #2 at 80 to 140°C for 1 to 5 min to form a base coat layer. Then, a polyester-type fabric substrate layer was attached on the base coat layer, followed by pressing, and heated in Oven #3 at 120 to 140°C for 2 to 10 min. Pll artificial leather was obtained after stripping the release paper.
Below is the formulation example data.
able 2: Formulations of the base coat layer (part by weight)
Figure imgf000017_0001
Figure imgf000018_0001
n.d.: In Comparative Example 9, the open time was so short that no further test could be done to obtain data.
The result data in Table 2 show that a good compromise between the softness on one hand, and the curing and peel properties on the other hand was obtained in Inventive Examples 1 and 2. In contrast, said desirable compromise was not available when the NCO content of the isocyanate component (A) was too low or too high (in Comparative Examples 6 and 7), the amount of BDO as a chain extender was too high (in Comparative Example 3), or the water content was too low or too high (in Comparative Examples 4 and 5). In one word, the test results have clearly shown that in order to achieve the desirable compromise between the softness and the curing and peel properties, all of the NCO content of the isocyanate component (A), the amount of BDO as a chain extender, and the water content are critical.
In order to test the Pll and Fabric interacting permeation, an additional Example 10 was prepared by repeating Example 2, except for the time of the partial curing in Oven #2. The results are shown in Table 3:
Table 3:
Figure imgf000019_0001
The results in Table 3 show that the Pll and fabric interacting permeation plays a role in achieving the desired softness and peeling strength. If the permeation is less than 10%, then peeling strength is not good (in Comparative Example 10); if the permeation is more than 30%, then softness is not good (in Comparative Example 6). The desired softness and peeling strength is available only when the permeation is in the range of 10-30% (in Inventive Example 2).
Open time: Open time is the time when the viscosity of the components (A) and (B), after being mixed, reaches to 5000 mPa.s. An open time of > 5 min meet the requirement.
Softness testing method:
GT-303 Leather Softness tester was used, wherein the softness being greater than 5 meets the requirement.
Curing testing method:
Curing property of the base coat layer was evaluated by using nail to press the top coat layer of the laminate and then visually evaluating according to the following grades:
Grade 1 : nail print is rebound > 10 sec, or the top coat layer is damaged;
Grade 2: nail print rebound (7 sec - 9 sec);
Grade 3: nail print rebound (4 sec - 6 sec);
Grade 4: nail print rebound (1 sec - 3 sec); and Grade 5: no obvious nail print.
Grades 5 and 4 meet the requirement.
Peeling test and peeling maintenance after 48 hours:
Peeling strength test:
Peeling strength test was carried out to the Pll laminates that were just peeled from the release paper after curing, and the testing should be finished within 20 min, including specimen preparation and testing. The test follows the standard SATRA TM 411.
Peeling maintenance after 48 hours:
The peeling strength was tested after 48 hours.
PU and Fabric interacting permeation (%):
The PU and Fabric interacting permeation is determined by referring to GB/T 22889- 2021 , Section 6.2.2 and is depicted in Figure 3. Particularly, a small piece of specimen in the form of 10*10 mm square was sampled from the center of the artificial leather to be tested, and then was cut to observe the cross section of the artificial leather by using microscope. Within the cross section, a first measuring site was selected arbitrarily at the boundary between the base coat layer and the fabric substrate layer, and at said site, a first interacting permeation depth was measured. Then, a second measuring site with a distance of 500 pm from the first measuring site was selected and then, at said second site, a second interacting permeation depth was measured. In this way, the measurement was repeated for six times at six different sites, with the proviso that the total distance of the said six sites shall include one permeation depth maximum and one permeation depth minimum. The recorded result was the average of the six measuring values of the Pll and Fabric interacting permeation percentage.
Pll and Fabric interacting permeation = average interacting permeation distance I whole fabric thickness
The permeation percentage of from 10% to 30% meets the requirement.

Claims

1. A non-solvent polyurethane composition for the use in artificial leather, comprising a polyol component (A) and an isocyanate component (B), wherein the isocyanate component (B) has an NCO content of from 10% to 12% by weight, and the polyol component (A) comprises a chain extender at an amount of 0 to 3% by weight and water at an amount of 0.2 to 0.4% by weight, based on the overall weight of the polyol component (A).
2. The polyurethane composition according to claim 1 , wherein the isocyanate component (B) comprises, preferably consists of a polyisocyanate prepolymer.
3. The polyurethane composition according to claim 2, wherein the polyisocyanate prepolymer is obtainable by reacting 4,4’-MDI with a polyether polyol.
4. The polyurethane composition according to claim 1 , wherein the polyurethane composition comprises a catalyst component consisting of a combination of a thermal delay catalyst and an organometallic catalyst.
5. The polyurethane composition according to claim 4, wherein the thermal delay catalyst is at an amount of from 0.1 to 0.5% by weight and the organometallic catalyst is at an amount of from 0.05 to 0.3% by weight, based on the overall weight of the polyol component (A).
6. The polyurethane composition according to claim 4, wherein the weight ratio between the thermal delay catalyst and the organometallic catalyst is in the range of from 1 :1 to 3: 1.
7. The polyurethane composition according to claim 4, wherein the thermal delay catalyst is selected from the group consisting of thermal delayed amine catalyst and the organometallic catalyst is selected from the group consisting of bismuth and zinc salt catalysts.
8. The polyurethane composition according to claim 1 , wherein the chain extender is selected from 2-functional alcohols having molecular weights in the range from 60 to 150 g/mol, preferably ethylene glycol, propylene glycol, diethylene glycol,
1.4-butanediol, dipropylene glycol and tripropylene glycol, especially preferably
1.4-butanediol.
9. An artificial leather, comprising a top coat layer, a base coat layer and a substrate layer, wherein the base coat layer is formed from the polyurethane composition according to any one of claims 1 to 8.
10. The artificial leather according to claim 9, wherein the polyurethane composition and the substrate layer have an interaction permeation percentage in the range from 10% to 30%.
11. A process for production of the artificial leather according to claim 9, said process comprising i) providing a release layer, ii) applying one or more than one layer of a top coat to the release layer to an overall top coat layer thickness in the range from 1 to 500 pm, iii) applying the polyurethane composition according to any one of claims 1 to 8 to the top coat layer(s) and partially curing the composition to form a base coat layer with the thickness in the range from 0.1 to 1.0 mm, iv) attaching a substrate layer to the base coat layer to form a laminate, v) curing the laminate, and vi) separating the release layer from the cured laminate.
12. The process according to claim 11 , wherein the time of partial curing is 20-200 seconds.
PCT/EP2024/050004 2023-01-06 2024-01-02 Non-solvent artificial leather polyurethane system and preparation process WO2024146876A1 (en)

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Citations (4)

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Publication number Priority date Publication date Assignee Title
US20090247671A1 (en) * 2008-03-25 2009-10-01 Hyundai Motor Company Solvent-free polyurethane-based artificial leather having the texture of human skin and the preparation method thereof
CN108164675A (en) * 2017-12-29 2018-06-15 浙江华峰合成树脂有限公司 The solvent-free leather polyurethane resin of high temperature resistant integrative and preparation method and application
WO2022100950A1 (en) * 2020-11-13 2022-05-19 Basf Se Embossable non-solvent pu sheet, a laminate and a synthetic leather comprising the same
WO2022218680A1 (en) * 2021-04-13 2022-10-20 Basf Se Non-solvent pu system, an artificial leather comprising the same and a process for producing the artificial leather

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090247671A1 (en) * 2008-03-25 2009-10-01 Hyundai Motor Company Solvent-free polyurethane-based artificial leather having the texture of human skin and the preparation method thereof
CN108164675A (en) * 2017-12-29 2018-06-15 浙江华峰合成树脂有限公司 The solvent-free leather polyurethane resin of high temperature resistant integrative and preparation method and application
WO2022100950A1 (en) * 2020-11-13 2022-05-19 Basf Se Embossable non-solvent pu sheet, a laminate and a synthetic leather comprising the same
WO2022218680A1 (en) * 2021-04-13 2022-10-20 Basf Se Non-solvent pu system, an artificial leather comprising the same and a process for producing the artificial leather

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