Method of making a laminate and laminate

Abstract

A method of making a laminate and a laminate made by the method are provided.

Description

Technical Field

[0001] This disclosure relates to a method for preparing a laminate and the laminate itself. Background Technology

[0002] There are many types of synthetic leather and it is used in many products, such as home furniture, automotive interiors, and clothing. One of the most commonly used synthetic leathers is a laminate containing a polyurethane foam layer, due to its low production cost and adjustable properties.

[0003] In conventional methods for preparing polyurethane-based laminates, a polyurethane forming composition is spread on release paper and then cured and foamed at a high temperature.

[0004] US 4,102,719 A discloses a method for producing artificial leather. The method includes coating a composition comprising a combination of urethane prepolymer, a catalyst, and a foam stabilizer, and comprising a plurality of extremely fine inert gas pores, onto release paper or onto a surface treatment agent layer coated to release paper at a specified thickness; subjecting the resulting product to steam treatment in a specific atmosphere; laminating a substrate onto the coating under pressure; subjecting the laminated product to heat treatment at a specific temperature; and then peeling off the release paper, and optionally further treating the product with a surface treatment agent.

[0005] CN 102505518 A discloses a method for preparing a 100% solids content polyurethane interlayer for synthetic leather. A non-reactive gas is introduced into the polyurethane material in a spraying apparatus before heating the polyurethane material.

[0006] A simple method is needed to prepare polyurethane-based laminates. Summary of the Invention

[0007] According to one aspect of this disclosure, a method for preparing a laminate is provided, the method comprising (a) preparing an aerated blend from a solvent-free polyurethane forming composition and a gas, wherein the gas is dispersed in the aerated blend in the form of bubbles; (b) spreading the aerated blend on the surface of a substrate and heating it to form a polyurethane composite material; (c) attaching a fabric layer to the surface of the polyurethane composite material to form a laminate preform; (d) heating the laminate preform; and (e) separating at least a portion of the substrate from the laminate preform to form a laminate. The solvent-free polyurethane forming composition comprises a polyol component and a polyisocyanate component. The polyol component comprises a polyol, a catalyst, and a foam stabilizer. The solvent-free polyurethane forming composition has an isocyanate index in the range of 1.05 to 3.8.

[0008] According to another aspect of this disclosure, a laminate prepared by this method is provided, the laminate comprising a fabric layer and a polyurethane foam. Attached Figure Description

[0009] To facilitate identification of any particular element or action being discussed, one or more of the most significant bits in the reference numerals refer to the figure number in which the element is first introduced.

[0010] Figure 1 A flowchart of an exemplary method for preparing a laminate according to one embodiment is shown.

[0011] Figure 2 A flowchart is shown as an exemplary method for preparing an inflatable blend from a solvent-free polyurethane forming composition and a gas, according to one embodiment.

[0012] Figure 3 An exemplary system for preparing synthetic leather from a solvent-free polyurethane forming composition and gas, according to one embodiment, is shown.

[0013] Figure 4 A cross-section of an exemplary synthetic leather according to one embodiment is shown. Detailed Implementation

[0014] Unless otherwise defined, all technical and scientific terms used herein have the meanings commonly understood by one of ordinary skill in the art to which this disclosure pertains. As used herein, unless otherwise stated, the following terms have the meanings assigned to them as follows.

[0015] As used in this article, the article “a / an” refers to one or more (i.e., at least one) grammatical objects of the article. For example, “a / an element” means one or more elements.

[0016] Unless otherwise specified, all percentages (%) are "percentages by weight".

[0017] The "hydroxyl value" (also known as the "OH value") refers to the mass (in milligrams) of potassium hydroxide (KOH) required to neutralize one gram of acetic acid absorbed during the acetylation of a polyol or a blend of polyols. The hydroxyl value is determined according to DIN 53240 (German Institute for Standardization) 2012 and is expressed in mgKOH / g.

[0018] The "functionality" of an alcohol (whether a small molecule alcohol or a polyol) refers to the number of hydroxyl groups per molecule. The average functionality of a blend of several alcohols refers to the molar average of the functionality of all components.

[0019] The "isocyanate index" (or simply index) of a polyurethane forming composition refers to the ratio of the number of NCO groups present in the polyurethane system to the number of reactive hydrogen atoms in isocyanates, expressed as a percentage.

[0020]

[0021] [NCO] represents the number of NCO groups.

[0022] [Isocyanate reactive hydrogen] is the number of isocyanate reactive hydrogen atoms.

[0023] In other words, the isocyanate index represents the percentage of isocyanate actually used in a formulation relative to the theoretically required amount of isocyanate (used to react with the reactive hydrogen of the isocyanate used in the formulation).

[0024] "Isocyanate content" refers to the content of isocyanate groups in a preparation, calculated as the ratio of the mass of isocyanate groups (NCO) to the mass of the preparation. The isocyanate content is determined according to ISO 14896 Method A and is expressed in wt.%.

[0025] Figure 1 A flowchart of an exemplary method for preparing a laminate is shown. The laminate includes a polyurethane foam layer and a fabric layer. The laminate can be used as a semi-finished or final product of synthetic leather. While the example routines depict a specific sequence of operations, this sequence can be changed without departing from the scope of this disclosure. For example, some of the depicted operations may be performed in parallel or in a different sequence that does not materially affect the functionality of the routine. In other instances, different components of the example apparatus or system of the example routines may perform their functions substantially simultaneously or in a specific order.

[0026] According to some examples, the method includes preparing an inflatable blend from a solvent-free polyurethane forming composition and a gas in box 102.

[0027] The gas is dispersed in the aerated blend in the form of bubbles. The gas can be ambient air, nitrogen, carbon dioxide, etc.

[0028] The solvent-free polyurethane forming composition comprises a polyol component and a polyisocyanate component. The polyol component includes a polyol, a catalyst, and a foam stabilizer. The solvent-free polyurethane forming composition has an isocyanate index in the range of 1.05 to 3.8.

[0029] In some embodiments, the polyol component and the polyisocyanate component are mixed prior to aeration. In some embodiments, the polyol component is aerated prior to mixing with the polyisocyanate component. In some embodiments, the polyisocyanate component is aerated prior to mixing with the polyol component. In some embodiments, both the polyol component and the polyisocyanate component are aerated separately and then mixed. Aeration can be achieved using a vigorous agitator, optionally capable of introducing gas bubbles into the liquid phase—whether it is the polyol component, the polyisocyanate component, or a mixture thereof.

[0030] After inflation, the volume of the blend expands. The volume of the aerated blend is greater than two and less than five times the volume of the solvent-free polyurethane forming composition. Preferably, the volume of the aerated blend is greater than three and less than four times the volume of the solvent-free polyurethane forming composition. The volumes of the aerated blend and the solvent-free polyurethane forming composition can be determined by pouring them into a measuring cup or cylinder. After frame 102, the aerated solvent-free polyurethane forming composition may appear as a slurry.

[0031] According to some examples, the method includes spreading an inflatable blend on the surface of a substrate in box 104 and heating it to form a polyurethane composite material.

[0032] The spreading of the aerated blend can be achieved using, for example, a sprayer, knife, brush, or roller. Heating can be performed in an oven or an enclosed space with a preset temperature. Heating allows the hydroxyl groups in the polyol component to react with the isocyanate groups in the polyisocyanate component. In this way, urethane bonds are formed. Under heating conditions, the volume of the aerated blend can further expand due to the expansion of bubbles. Due to the sharp increase in viscosity of the aerated blend, at least some of the bubbles can be retained in the aerated blend. During the heating process, the aerated blend gels but does not completely cure. After box 104, the polyurethane composite material may include two layers: a substrate and a gelled polyurethane layer on top of the substrate.

[0033] Preferably, the duration of heating the aerated blend on the substrate surface is 60 to 300 seconds, more preferably 90 to 180 seconds.

[0034] In some embodiments, the substrate is release paper, as typically known in the relevant art. Examples of suitable substrates are metal foil, plastic, or paper. In a preferred embodiment, the substrate used is release paper optionally coated with a polymer composition. Preferably, the release paper is coated with a polyolefin, preferably polypropylene. Alternatively, the release paper is preferably coated with silicone. In an alternative preferred embodiment, the substrate used is a polyethylene terephthalate (PET) layer optionally coated with a polymer composition. Preferably, the PET layer is coated with a polyolefin, preferably polypropylene. Alternatively, the PET layer is preferably coated with silicone.

[0035] Alternatively, the substrate comprises a release paper and a top coating layer in contact with the release paper. The release paper contacts the top coating layer. The release paper can be easily separated from the top coating layer. When the aerated blend is spread on the surface of the substrate, the aerated blend contacts the top coating layer. Therefore, there are three layers from top to bottom: the aerated blend, the top coating layer, and the release paper.

[0036] Release paper is commercially available. Examples of well-known manufacturers in this field include Warren (Sape Inc., USA), Binda (Italy), Arjo Wiggins (UK / USA), and Lintec (Japan).

[0037] The topcoat used in this article is preferably based on polyurethane chemistry, as is known in the art.

[0038] According to some examples, the method includes attaching a fabric layer to the surface of a polyurethane composite material in frame 106 and forming a laminate preform.

[0039] The laminated preform formed in frame 106 comprises three layers: a fabric layer, a gelled polyurethane layer, and a substrate.

[0040] The fabric layer can be attached to the polyurethane composite by hot pressing. Because the gelled polyurethane is not fully cured, it can penetrate into the micropores and channels within the fabric layer under elevated temperature and pressure, forming a strong bond.

[0041] The fabric layer can be woven, knitted, or nonwoven. The following materials are particularly suitable for producing fabric layers: cotton, linen, cashmere, wool, silk, hair, hemp, polyester, polyamide, polyurethane, or any combination thereof.

[0042] According to some examples, the method includes heating the laminate preform in frame 108.

[0043] Heating can further crosslink the chemical bonds in gelled polyurethane and increase the volume of the bubbles. As a result, the gelled polyurethane cures and forms polyurethane foam. Heating can occur in an oven.

[0044] Preferably, the duration of heating the laminate preform is 180 to 900 seconds, more preferably 300 to 780 seconds.

[0045] According to some examples, the method includes separating at least a portion of the substrate from the laminate preform in frame 110 and forming a laminate.

[0046] Separation of at least a portion of the substrate can be achieved by dragging a portion or the entire substrate from the laminate preform.

[0047] When the substrate consists only of release paper, the entire release paper is separated from the laminate preform. The laminate obtained after step 110 comprises a polyurethane foam layer and a fabric layer. The laminate can be used as a semi-finished product for the production of synthetic leather. In some applications, the laminate can be attached to an additional topcoat and then manufactured into consumer goods, such as handbags.

[0048] When the substrate includes release paper and a top coating, only the release paper of the substrate separates from the laminate preform. In this case, the resulting laminate includes a top coating layer, a polyurethane foam layer, and a fabric layer. The laminate can be used directly or after post-processing as a final product of synthetic leather. The laminate can be made into consumer goods, such as handbags.

[0049] The separated portion of the substrate following step 110 is then rolled and recycled for another production cycle. For example, to save material, the release paper can be reused several times. Alternatively, the release paper is coated with a polymeric material as a precursor to the topcoat and then heated to form a substrate comprising the topcoat and the release paper.

[0050] Figure 2 A flowchart is shown of an exemplary method for preparing an aerated blend from a solvent-free polyurethane forming composition and a gas. This exemplary method can be used as... Figure 1 The steps in box 102. Although the example routines depict a specific sequence of operations, this sequence may be changed without departing from the scope of this disclosure. For example, some of the depicted operations may be performed in parallel or in different sequences that do not substantially affect the functionality of the routine. In other instances, different components of the example apparatus or system of the example routines may perform their functions substantially simultaneously or in a specific order.

[0051] According to some examples, the method includes mixing a polyol component and a polyisocyanate component in box 202 to form a solvent-free polyurethane forming composition.

[0052] In some embodiments, mixing is achieved by an operating stirrer. The stirrer can be of any form or shape. The stirrer can be a mechanical stirrer or a magnetic stirrer.

[0053] According to some examples, the method includes entrapping a gas in a solvent-free polyurethane forming composition in box 204.

[0054] In some embodiments, gas is encapsulated in the mixture by an in-operation stirrer. The stirrer can be of any form or shape. The stirrer can be a mechanical stirrer or a magnetic stirrer. The stirrer introduces multiple air bubbles into the mixture.

[0055] In some embodiments, the steps of mixing the polyol component and the polyisocyanate component in block 202 and encapsulating the gas in the solvent-free polyurethane forming composition in block 204 are simultaneous, i.e., the gas is encapsulated while the polyol component and the polyisocyanate component are being mixed to form the solvent-free polyurethane forming composition.

[0056] In some embodiments, the step in block 202 precedes the step in block 204.

[0057] Figure 3 An exemplary system for preparing synthetic leather from a solvent-free polyurethane forming composition and a gas is shown. This exemplary system can perform... Figure 1 The steps.

[0058] The system includes a release paper roller 302, release paper 304a, roller 306a, roller 306b, release paper 304b, polyurethane tank 308, pipe 310, knife 312, polyurethane composite material 314, curing oven 316, fabric roller 318, fabric 320, roller 322a, roller 322b, post-curing oven 326, roller 328a, roller 328b, release paper winding machine 330, recycled release paper 332, laminate 334, and laminate winding machine 336. This system can be used to prepare laminates containing polyurethane foam layers and fabric layers.

[0059] Release paper roller 302 rotates and unfolds release paper 304a. Release paper 304a is pressed by rollers 306a and 306b to form release paper 304b. Release paper 304b is flat and serves as a substrate.

[0060] A polyurethane canister 308 delivers an aerated blend to release paper 304b via conduit 310. The aerated blend is prepared from a solvent-free polyurethane forming composition comprising a polyol component and a polyisocyanate component, and a gas. A polyurethane composite material 314 is obtained. The polyurethane composite material 314 comprises a layer of aerated blend and a layer of release paper 304b. A blade 312 facilitates spreading the aerated blend to a substantially uniform thickness on the surface of the release paper 304b.

[0061] The polyurethane composite material 314 then proceeds into the curing oven 316. The curing oven 316 heats the polyurethane composite material 314. The aerated blend undergoes a urethane formation process accompanying the foaming process. The aerated blend gels and expands in volume. Its viscosity increases. Nevertheless, the solvent-free polyurethane forming composition has not yet cured.

[0062] Fabric roller 318 rotates and supplies fabric 320. Fabric 320 is attached to polyurethane composite material 314 by pressure from rollers 322a and 322b. A laminate preform 324 is formed, comprising a release paper layer 304b and an inflatable blend layer (…). Figure 3 (Not shown in the image) and fabric layer 320. Since the solvent-free polyurethane forming composition in polyurethane composite 314 is not cured, it penetrates into the micropores and channels within fabric 320 due to compression. This penetration strengthens the bond between the subsequently formed polyurethane foam and fabric 320.

[0063] The laminated preform 324 enters and is heated in a post-curing oven 326. Heating causes the solvent-free polyurethane forming composition in the laminated preform 324 to foam, cure, and crosslink. In the post-curing oven 326, the aerated blend layer is transformed into a polyurethane foam layer.

[0064] The laminate preform 324 is then pressed by rollers 328a and 328b. The release paper layer is separated from the polyurethane foam and fabric 320 to form recycled release paper 332. The recycled release paper 332 is wound by a release paper winding machine 330. The recycled release paper 332 is reusable and can be re-entered into... Figure 3 The entire process described.

[0065] After separating the recycled release paper 332, a laminate 334 is formed. The laminate is then wound and collected by a laminate winding machine 336 for storage or transportation.

[0066] Figure 4 A cross-section of an exemplary synthetic leather is shown. The synthetic leather sequentially includes a top coating layer 402, a polyurethane foam layer 404, and a fabric layer 406. The polyurethane foam layer 404 may be... Figure 3A portion of the laminated preform 324 or a portion of the laminate 334. The polyurethane foam layer 404 includes a polyurethane matrix 408, pores 410a, 410b, 410c, 410d, 410e, 410f, 410g, 410h, 410i, and 410j. Pores 410a to 410j are distributed within the polyurethane matrix 408. The polyurethane matrix 408 is prepared from a solvent-free polyurethane forming composition.

[0067] Solvent-free polyurethane forming composition

[0068] Solvent-free polyurethane forming compositions are systems comprising polyol components and polyisocyanate components.

[0069] The polyurethane forming composition contains no solvent or diluent, or contains negligible amounts of solvent or diluent, such as water, dimethylformamide, or toluene. Solvent-free polyurethane forming compositions reduce environmental impact and safety and health hazards to the workforce.

[0070] The isocyanate index of the solvent-free polyurethane forming composition is in the range of 1.05 to 3.8, preferably in the range of 1.7 to 3.2. When the isocyanate index is too low, the curing or hardening of the polyurethane forming composition may be problematic. When the isocyanate index is too high, the polyisocyanate component may be in excessive excess and the composition may remain liquid after heating. Subsequent steps (such as attaching fabric layers) will not have sufficient time, which further causes processing difficulties and / or leads to product quality problems.

[0071] Preferably, the solvent-free polyurethane forming composition does not contain a chemical blowing agent or contains less than 0.3 wt.% of a chemical blowing agent based on the total weight of the solvent-free polyurethane forming composition. The chemical blowing agent may be selected from water, gas-releasing compounds, carboxylic acids, salts of carboxylic acids, and any combination thereof. Gas-releasing compounds are compounds capable of releasing gases (such as CO2, NH3, N2, or mixtures thereof) at temperatures below 180°C. Examples of gas-releasing agents include, but are not limited to, alkali metal bicarbonates, alkali metal carbonates, ammonium bicarbonate, combinations of alkali metal carbonates and ammonium salts, azodicarbonamide, azodicarbonamide, 4,4'-oxybis(benzenesulfonylhydrazine), p-toluenesulfonylhydrazine, or combinations thereof. Carboxylic acids include formic acid, acetic acid, citric acid, or the like.

[0072] Typically, the presence of water in polyurethane forming compositions, particularly in the polyol component, can initiate foaming when water reacts with isocyanate groups and releases CO2. It is believed that the inclusion of water in polyurethane forming compositions contributes to the formation of polyurethane foam.

[0073] Surprisingly, it was found that even when the chemical blowing agents used in conventional polyurethane chemistry were essentially absent in the polyurethane forming composition, the polyurethane foam in the laminate exhibited low density.

[0074] Preferably, the solvent-free polyurethane forming composition further comprises a filler in an amount of 0.5 to 50 wt.%, more preferably 20 to 40 wt.%, based on the total weight of the polyurethane forming composition. The filler is preferably selected from calcium carbonate, aluminum hydroxide, barium sulfate, magnesium oxide, talc, diatomaceous earth, zinc oxide, titanium dioxide, aluminosilicates, and combinations thereof. The filler can help adjust the mechanical strength and other properties of the polyurethane foam and laminate.

[0075] polyol components

[0076] In this disclosure, the polyol component includes polyols, catalysts, and foam stabilizers.

[0077] Preferably, the polyol component has an average functionality of 2.0 to 2.6.

[0078] The polyol is preferably selected from polyether polyols, polycarbonate polyols, polyester polyols, and any combination thereof. These are well known in the relevant field.

[0079] When polyether polyols are used, these are typically obtained by known methods, such as anionic polymerization of one or more epoxides selected from propylene oxide (PO) and ethylene oxide (EO), butane oxide, and tetrahydrofuran, using an alkali metal hydroxide as a catalyst and adding a starting molecule containing a plurality of attached reactive hydrogen atoms. Available polyether polyols further include so-called low-unsaturated polyether polyols. Low-unsaturated polyols for the purposes of this invention are more particularly polyether polyols containing less than 0.02 meq / g, and preferably less than 0.01 meq / g, of unsaturated compounds. This type of polyether polyol is obtained by adding ethylene oxide and / or propylene oxide and mixtures thereof to at least a difunctional alcohol in the presence of a so-called bimetallic cyanide catalyst.

[0080] Epoxides can be used alone, alternately, or as mixtures. The use of EO-PO mixtures results in polyether polyols with randomly distributed PO / EO units. One can begin by using a PO-EO mixture and then continue using only PO or EO until polymerization terminates, resulting in polyether polyols with PO-terminated or EO-terminated caps, respectively.

[0081] The starting molecules used are typically NH- or OH- functional compounds, such as water, amines, or alcohols. Preferred starting molecules are di- to hexahydrols, such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, diethylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, glycerol, trimethylolpropane, pentaerythritol, and / or sorbitol.

[0082] Further preferred are polyether polyols obtained by ring-opening polymerization of tetrahydrofuran. These polytetrahydrofuran (pTHF) polyols preferably have a functionality of about 2 and are often referred to as polytetrahydrofuran diols. They preferably further have a number average molecular weight in the range of 500 to 4,000 g / mol, more preferably in the range of 700 to 3,000 g / mol, and more preferably in the range of 900 to 2,500 g / mol. pTHF polyols are also known in the relevant art as poly(tetramethylene) glycol (PTMG), poly(tetramethylene ether) glycol (PTMEG), or polytetramethylene oxide (PTMO).

[0083] When polyester polyols are used, these are typically obtained by condensation of a polyfunctional alcohol having 2 to 12 carbon atoms, preferably 2 to 6 carbon atoms, with a polyfunctional carboxylic acid having 2 to 12 carbon atoms. Examples of polyfunctional carboxylic acids are succinic acid, glutaric acid, adipic acid, octanoic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, maleic acid, fumaric acid, and preferably phthalic acid, isophthalic acid, terephthalic acid, and isomerized naphthalic acid.

[0084] Preferably, the polyol component comprises a chain extender selected from the following: ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, dipropylene glycol, and combinations thereof.

[0085] Preferably, the content of the chain extender is 0.1 to 10 wt.% based on the total weight of the polyol components.

[0086] Preferably, the polyol component comprises polytetrahydrofuran diol.

[0087] As catalysts, compounds that accelerate the isocyanate-polyol reaction can be used. These catalysts include amine-based catalysts and organometallic compound-based catalysts or mixtures thereof. As organometallic compound-based catalysts, for example, organotin compounds, such as tin(II) salts of organic carboxylic acids, such as tin(II) acetate, tin(II) octoate, tin(II) ethylhexanoate, and tin(II) laurate; and dialkyltin(IV) salts of organic carboxylic acids, such as dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate, and dioctyltin diacetate; as well as Zn or Bi salts, such as zinc octoate, bismuth(III) neodecanoate, bismuth 2-ethylhexanoate, and bismuth octoate; or alkali metal salts of carboxylic acids, such as potassium acetate or potassium formate.

[0088] As amine-based catalysts, strong basic amines such as N,N,N-triethylaminoethoxyethanol, bis(N,N-dimethylaminoethyl) ether, dimethylcyclohexylamine, trimethylhydroxyethyl ethylenediamine, dimethylbenzylamine, triethylamine, triethylenediamine, pentamethyldipropylenetriamine, dimethylethanolamine, N-methylimidazole, N-ethylimidazole, tetramethylhexamethylenediamine, tris(dimethylaminopropyl)hexahydrotriazine, dimethylaminopropylamine, N-ethylmorpholine, diazabicycloundecene, diazabicyclononene, diazabicyclooctane, are preferred, with triethylenediamine or bis(N,N-dimethylaminoethyl) ether being preferred.

[0089] The catalyst used in this disclosure may be commercially available, such as Haptex CC6945 / 92C-CC from BASF.

[0090] Preferably, the catalyst has a content of 0.05 to 5 wt.% based on the total weight of the polyol components, more preferably 0.1 to 1.5 wt.%.

[0091] Foam stabilizers can stabilize aerated blends and prevent dispersed bubbles from bursting and releasing gas. Without foam stabilizers, aerated blends may be unstable and release some or even almost all of the gas in the following steps, such as when the aerated blend is heated.

[0092] The foam stabilizer is preferably selected from siloxane-oxidized olefin copolymers, organosiloxanes, ethoxylated alkylphenols, ethoxylated fatty alcohols, paraffin oil, castor oil esters, castor oil esters, Turkish red oil, peanut oil, and combinations thereof.

[0093] The foam stabilizer preferably has an content of 0.1 to 5 wt.%, more preferably 0.5 to 3 wt.%, based on the total weight of the polyol components.

[0094] Polyisocyanate components

[0095] The polyisocyanate component is selected from diisocyanates, oligomeric forms of diisocyanates, carbodiimide-modified diisocyanates, isocyanate-terminated prepolymers, and combinations thereof. The diisocyanate can be an aliphatic diisocyanate such as hexamethylene diisocyanate, an alicyclic diisocyanate such as isophorone diisocyanate or 4,4'-methylene di(cyclohexyl)isocyanate, or an aromatic diisocyanate such as toluene diisocyanate or methylene diphenyl diisocyanate. A polycarbodiimide-modified diisocyanate is a polyisocyanate in which at least a portion of the isocyanate groups have been modified to a carbodiimide structure.

[0096] Preferably, the polyisocyanate component is an isocyanate-terminated prepolymer formed by reacting an excess of diisocyanate or an oligomer of diisocyanate with a compound containing active hydrogen. Due to an insufficient number of active hydrogen groups relative to the isocyanate groups, all or substantially all of the active hydrogen groups in the compound disappear. The isocyanate-terminated prepolymer contains multiple urethane, urea, or thiourethane bonds and multiple terminal isocyanate groups. The active hydrogen-containing compound may include alcohols, amines, amino alcohols, thiols, or combinations thereof. Preferably, the active hydrogen-containing compound is a polyester polyol, a polyether polyol, a polycarbonate polyol, or a combination thereof.

[0097] Preferably, the polyisocyanate component is substantially unmodified with carbodiimide. "Substantially unmodified with carbodiimide" means that the polyisocyanate component contains very few (due to trace impurities) carbodiimide functional groups to none, which is below the detection limit of the characterization method.

[0098] Preferably, the polyisocyanate component has an isocyanate content of 7 to 22 wt.% as determined according to ISO 14896 Method A, more preferably 10 to 19 wt.% isocyanate content.

[0099] Laminate

[0100] This disclosure also provides a laminate comprising a fabric layer and a polyurethane foam. Preferably, the laminate further comprises a top coating layer in contact with the polyurethane foam.

[0101] Preferably, the polyurethane foam has a content of 0.3 to 0.5 g / cm³. 3 The density.

[0102] Preferably, the laminate has a peel strength greater than 30 N / 3 cm, more preferably greater than 45 N / 3 cm.

[0103] In addition to high peel strength and lightweight, the laminate also has good flexibility.

[0104] Laminates can be used as synthetic leather, and are applied in a variety of scenarios, including but not limited to the interior decoration of transport vehicles, furniture, handbags, clothing or shoes.

[0105] Example

[0106] The following examples are intended to illustrate this disclosure, but do not limit its scope.

[0107] The materials used in the example are as follows.

[0108] Polyether polyol 1, an ethylene oxide-propylene oxide polymer polyol with diol as the starting material, functionality 2, hydroxyl value 29.5 mgKOH / g.

[0109] Polyether polyol 2, an ethylene oxide-propylene oxide polymer polyol with triol as the starting material, has a functionality of 3 and a hydroxyl value of 35 mg KOH / g.

[0110] Polytetrahydrofuran diol (pTHF diol), from BASF, with a functionality of 2 and a hydroxyl value of 56 mg KOH / g.

[0111] 1,4-Butanediol (“BDO”), used as a chain extender in polyol components, is from BASF, CAS No. 110-63-4.

[0112] Diphenylmethane diisocyanate (MDI), from BASF, CAS No. 101-68-8.

[0113] MM 103 is a carbodiimide-modified isocyanate from BASF, with an isocyanate content of 29.5 wt.%.

[0114] Zinc carboxylate and N,N-dimethylcyclohexylamine, mixed in a 1:1 weight ratio, were used as a catalyst.

[0115] VORASURF TM DC 193 is a silicone surfactant from Dow Chemical Company, used as a foam stabilizer.

[0116] Water and sodium bicarbonate are used as chemical foaming agents.

[0117] Calcium carbonate is used as a filler.

[0118] The polyol mixtures A1 to A7 used to prepare polyurethane forming compositions are shown in Table 1.

[0119] Table 1

[0120]

[0121] The isocyanate-terminated prepolymers used to prepare polyurethane forming compositions are shown in Table 2.

[0122] Table 2

[0123]

[0124] To prepare polyurethane forming compositions F1 to F12 and cF1 to cF2, the mixed polyols, catalyst, foam stabilizer, and filler were first thoroughly mixed. The mixture was stirred using a hand mixer, which introduced air bubbles into the liquid phase. The aerated liquid phase was then mixed with the isocyanate component to form the polyurethane forming system. The polyurethane forming system was then stirred and further aerated with air bubbles using a hand mixer. Using a measuring cup, it was found that the volume of the finally aerated polyurethane forming system was approximately three times the total volume of its components (excluding air bubbles). During the preparation of synthetic leather, the aerated polyurethane forming system was applied to release paper.

[0125] To prepare polyurethane forming compositions cF3 to cF4, a mixture of polyols, catalysts, foam stabilizers, fillers, and chemical foaming agents is thoroughly mixed. The liquid phase is then mixed with the isocyanate component to form the polyurethane forming system. No inflation is performed. During the preparation of synthetic leather, the polyurethane forming system is applied to release paper.

[0126] Synthetic leathers L1 to L12 and cL1 to cL4 are manufactured according to the following scheme.

[0127] Commercial release paper with a PU top coating is passed through a continuous apparatus for synthetic leather preparation at a speed of 1 m / min. The thickness of the top coating layer is approximately 50 micrometers. Subsequently, a solvent-free polyurethane forming system layer of approximately 400 micrometers thickness is applied using a manual mixer with whiskey. The material is then guided through an oven controlled at 140°C. The material re-emerges from the oven after approximately 90 seconds. A textile substrate is then applied to the still partially cured polyurethane under slight pressure. A laminate preform is produced. The laminate preform is then pressed and cured in an oven at 140°C. The laminate preform is removed from the oven after 10 minutes. The final synthetic leather is then obtained by peeling the release paper from the laminate preform. In the following text, the processability of the solvent-free polyurethane forming composition refers to the successful or unsuccessful preparation of synthetic leather by processing it according to the above scheme. Successful preparation of synthetic leather following the scheme is indicated as "G" in Table 5, and unsuccessful preparation of synthetic leather is indicated as "B".

[0128] The polyurethane forming compositions used to prepare synthetic leather are shown in Table 3, where “CBA” refers to a chemical foaming agent. Polyurethane forming compositions F1 to F12 are working examples, while polyurethane forming compositions cF1 to cF4 are comparative examples. cF3 and cF4 comprise a chemically foamed polyurethane foam layer.

[0129] Synthetic leathers (L1 to L12 and cL1 to cL4) prepared from polyurethane forming compositions were tested for their properties or performance according to the standards listed in Table 4.

[0130] The density here refers to the density of the foam layer within the synthetic leather being tested. Peel strength (abbreviated as "PS" in the table) refers to the adhesive strength between two adjacent layers of the laminate.

[0131] Peel strength measurements were performed according to standard GB / T 8949-2008 as follows: Synthetic leather samples were cut into 15cm × 3cm pieces and adhered to the outermost surface of the top coating using TPU hot melt adhesive tape. They were then pressed at 150°C for several minutes and then cooled to room temperature. A T-peel test was then performed on a ZwickRoell tensile testing machine at a speed of 100mm / min.

[0132] The flexural strength test of dry synthetic leather samples was conducted for 300,000 cycles at room temperature (RT), 30,000 cycles at -20°C, and 30,000 cycles at -30°C. The test followed standard ISO 5402-1 2017. Synthetic leather samples either failed (marked "F" in Table 5) or passed (marked "P" in Table 5) without cracking.

[0133] The test results for the synthetic leather are listed in Table 5.

[0134]

[0135]

[0136]

[0137] The "Not Applicable" indication indicates that data could not be obtained, possibly due to unsuccessful synthetic leather preparation or abandonment of performance testing. For comparative synthetic leathers cL1 and cL2, the compositions failed to cure and therefore no usable synthetic leather was obtained. For comparative synthetic leathers cL3 and cL4, based on polyurethane forming compositions containing significant amounts of chemical foaming agents, synthetic leathers with high-density foam layers were obtained, which are of little practical use for synthetic leather. Therefore, testing was abandoned.

[0138] Typically, for the test specimens used in this disclosure, good flexibility under normal conditions is indicated by room temperature bending and -20°C temperature bending. Excellent flexibility is indicated even under extremely cold conditions by -30°C temperature bending.

[0139] From Table 5, except for examples cL1 and cL2 which have isocyanate indices of 4.0 and 1.0 respectively, all solvent-free polyurethane forming compositions can be processed into synthetic leather.

[0140] Compared to Examples L1, L2, or L3, Examples L4, L5, or L6 exhibit significantly lower peel strength. The main difference between F1 and F4, F2 and F5, or F3 and F6 is whether the carbodiimide-modified polyisocyanate is included in the polyisocyanate component. Solvent-free polyurethane forming compositions without carbodiimide modification can produce robust synthetic leather.

[0141] Comparative examples L1 and cL3 or cL4 demonstrate that synthetic leather prepared from a composition without a chemical foaming agent by a mechanical foaming method can achieve a lower foam layer density.

[0142] Compared to synthetic leather L7, made from composition F7 which does not contain 1,4-butanediol as a chain extender, synthetic leather L1 exhibits significantly higher peel strength. Synthetic leather L1 is made from composition F1, which has a similar formulation to F7, except that it includes 1,4-butanediol as a chain extender in its polyol component. Synthetic leather L1 achieves peel strength in the range of 30 to 80 N / 3 cm.

Claims

1. A method for preparing a laminate, comprising: (a) Preparation of an aerated blend from a solvent-free polyurethane forming composition and a gas; (b) Spread the aerated blend on the surface of a substrate and heat it to form a polyurethane composite material; (c) Attaching the fabric layer to the surface of the polyurethane composite material to form a laminated preform; (d) Heating the laminated preform; and (e) Separating at least a portion of the substrate from the laminate preform and forming a laminate. The gas is dispersed in the aerated blend in the form of bubbles. The solvent-free polyurethane forming composition includes a polyol component and a polyisocyanate component. The polyol component includes a polyol, a catalyst, and a foam stabilizer. The solvent-free polyurethane forming composition has an isocyanate index in the range of 1.05 to 3.

8.

2. The method as described in claim 1, wherein, The isocyanate index of the solvent-free polyurethane forming composition is in the range of 1.7 to 3.

2.

3. The method as described in claim 1, wherein, The solvent-free polyurethane forming composition does not contain a chemical blowing agent or contains less than 0.3 wt.% of a chemical blowing agent based on the total weight of the solvent-free polyurethane forming composition.

4. The method of claim 1, wherein, The polyurethane forming composition further comprises filler in an amount of 0.5 to 50 wt.%, preferably 20 to 40 wt.%, based on the total weight of the polyurethane forming composition.

5. The method of claim 1, wherein, The polyol component has an average functionality of 2.0 to 2.

6.

6. The method of claim 1, wherein, The polyol component contains a chain extender selected from the following: ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, dipropylene glycol, and combinations thereof.

7. The method of claim 1, wherein, The polyol component includes polytetrahydrofuran diol.

8. The method of claim 1, wherein, The polyisocyanate component is an isocyanate-terminated prepolymer formed by reacting excess diisocyanate or excess diisocyanate oligomer with a compound containing active hydrogen.

9. The method of claim 1, wherein, The polyisocyanate component was essentially not modified with carbodiimide.

10. The method of claim 1, wherein, Step (a) includes (a1) The polyol component and the polyisocyanate component are mixed to form the solvent-free polyurethane composition; and (a2) The gas is encapsulated in the solvent-free polyurethane forming composition.

11. The method of claim 1, wherein, The aerated blend on the surface of the substrate is heated for a duration of 60 to 300 seconds, preferably 90 to 180 seconds.

12. The method of claim 1, wherein, The laminate preform is heated for a duration of 180 to 900 seconds, preferably 300 to 780 seconds.

13. A laminate prepared by any one of claims 1 to 12, comprising a fabric layer and a polyurethane foam.

14. The laminate of claim 13, wherein, The polyurethane foam has a content of 0.3 g / cm³. 3 up to 0.5 g / cm 3 The density.

15. The laminate of claim 14, having a peel strength greater than 30 N / 3 cm, preferably greater than 45 N / 3 cm.

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