CN102206410A - Preparation method of high-solid-content aqueous polyurethane for leather - Google Patents

Abstract

The invention relates to the field of synthetic leather material polyurethane, in particular to a preparation method of high-solid content water-based polyurethane for leather. The process route is: prepolymerization reaction: react polyol, hydrophilic chain extender and isocyanate monomer; monomer modification, add polyhydroxy monomer and polyurethane prepolymer for modification; Blending agent to make the emulsion form salt-forming ionic groups; chain extension after emulsification, dissolving external emulsifier and sulfonic acid chain extender in water, adding to the system for emulsification. The present invention uses carboxylic acid type and sulfonic acid type chain extenders to improve the emulsification performance of the emulsion and fully emulsify the polyurethane and water. At the same time, the method of combining self-emulsification and external emulsification can not only synthesize a stable emulsion but also improve the solid content, water is used as solvent during emulsification, which meets the needs of clean production process; the final synthesized emulsion has good film-forming performance, fast drying speed, no yellowing, excellent mechanical properties, and short process flow, suitable for synthetic leather base or surface materials. Can replace solvent-based products.

Description

Preparation method of high solid aqueous polyurethane for leather

technical field

The invention relates to the field of synthetic leather material polyurethane, in particular to a method for preparing water-based polyurethane with high solid content for leather.

Background technique

At present, polyurethane is developing rapidly as a synthetic leather material. Synthetic leather is based on non-woven fabrics made of hollow-core fibers with a lotus-shaped cross-section structure. After a series of finishing treatments such as gravure printing and embossing, it is a synthetic material with a structure similar to natural leather. Most of the synthetic leather products currently on the market are solvent-based polyurethanes. This type of resin is mostly used as toluene, xylene, acetone, butanone (MEK), ethyl acetate, and dimethylformamide (DMF). main solvent. The harm caused by solvents to the human body is manifold. The cost of water-based polyurethane for leather is much lower than that of solvent-based, and it is environmentally friendly. However, the solid content of domestic water-based PU products is mostly between 25-40%, which increases drying time and transportation costs. Therefore, the research and development of domestic leather with high solid content waterborne polyurethane is becoming more and more active.

Chinese patent CN101613455A introduces a production method of water-based polyurethane for high-solid leather by self-emulsification method: after synthesizing a prepolymer with polyethylene glycol butylene glycol adipate diol, polytetrahydrofuran diol and toluene diisocyanate as raw materials , adding a blocking agent before the chain extension of the small molecule diamine, so that the molecular weight is reduced, but the viscosity of the emulsion is still ^5000mPa. Oxidation and yellowing after covering will affect the appearance.

Chinese patent CN101328253A adopts the self-emulsification method, adding polyol, isocyanate and chain extender to the synthetic prepolymer at one time, adding sulfonic acid chain extender after cooling down, and then adding water to emulsify and disperse to obtain an emulsion with a solid content of about 50%, which can be used It is suitable for leather, but the mechanical properties (tensile strength, elongation at break and modulus, etc.) of the emulsion are poor after film formation, so it is not suitable for leather base or surface materials.

Contents of the invention

Aiming at the deficiencies of the prior art above, the present invention introduces a method for preparing high-solid aqueous polyurethane for leather. It mainly uses polyols and polyhydroxy carboxylic acids as the main raw materials to react with polyisocyanates to form prepolymers. After neutralization and salt formation, after a certain period of reaction, dissolve sulfonic acid type chain extenders and external emulsifiers in water, add Put it into the system, stir it at high speed, add an appropriate amount of defoamer dropwise, and it will be a milky white bluish emulsion after discharge.

The process route of the present invention mainly includes four parts: (1) prepolymerization reaction: reacting polyol, hydrophilic chain extender and isocyanate monomer; (2) monomer modification, adding polyhydroxy monomer and polyurethane prepolymer Carry out modification; (3) Neutralize to form a salt, add a neutralizing agent to make the emulsion form a salt-forming ion group; (4) After emulsification, extend the chain, dissolve the external emulsifier and sulfonic acid chain extender in water, add the system medium emulsification.

The preparation method of high-solid aqueous polyurethane for leather of the present invention is carried out according to the following steps:

(1) Prepolymerization reaction: Dehydrate the hydroxyl monomer and hydrophilic chain extender at 80-100°C and 0.08-0.1Mpa vacuum for 1-3h, adjust the prepolymerization temperature to 70-90°C, and add the measured isocyanate Monomer, small molecule chain extender and catalyst, react for 2.0-4.0h; during the prepolymerization process, the R value is controlled to 1.05-2.0, and the infrared tracking method detects that the NCO content to be reacted will not change before proceeding to the next step of the reaction; the reaction process The viscosity of the prepolymer is adjusted by adding a small amount of solvent, wherein R refers to the molar ratio of the total NCO/OH;

(2) Monomer modification: In order to increase the moisture permeability of the emulsion after film formation, polyethylene glycol (PEG) is added for modification, its molecular weight is 400-2000, and its mass accounts for 1%-15% of the total solids; Then add silicone and monoglyceride,

(3) Neutralize and form salt: on the basis of the above reaction, cool the water bath to 25-60°C, add neutralizing agent to neutralize and form salt for 0.5h, and the amount of neutralizing agent is added according to the neutralization degree of 80-120%; Described degree of neutralization refers to the molar ratio of neutralizing agent and hydrophilic chain extender;

(4) Chain extension after emulsification: dissolve the sulfonic acid type chain extender and external emulsifier in water, adjust the solid content to 50-60%, add emulsification for 0.5h under high-speed stirring, add an appropriate amount of defoamer dropwise, and the output is milky white With blue lotion.

Wherein the hydroxyl monomers described in step (1) include polyester polyols or polyester polyether mixed polyols with a molecular weight of 500-3000; preferably polytetrahydrofuran diol, polyethylene adipate, polyethylene glycol Neopentyl glycol diacid, acrylate polyol, polyethylene adipate diol, polyhexamethylene adipate diol, 1,4-butyl adipate Diol ester diol, polyε-caprolactone diol or polycarbonate-1,6-hexanediol ester diol; more preferably polytetrahydrofuran diol, polyethylene adipate, polyethylene adipate neopentyl glycol ester, polyethylene adipate diol, poly-1,4-butylene adipate diol, etc., most preferably polytetrahydrofuran diol, polyethylene adipate glycol One or more mixtures of polyester and neopentyl glycol adipate, which account for 20% to 65% of the total solid mass of the reaction.

Wherein the hydrophilic chain extender described in step (1) includes small molecular polyols containing carboxyl groups and sulfonic acid (salt) groups, preferably 2,2-dimethylolpropionic acid (DMPA), ethylenediamine Sodium ethyl sulfonate, 1,4-butanediol-2-sulfonate and its derivatives, preferably 2,2-dimethylol propionic acid (DMPA), dimethylol butyric acid, dihydroxy semi Esters, which account for 0.5% to 8% of the total solid mass of the reaction.

Wherein the isocyanate monomer described in step (1) is aliphatic and alicyclic diisocyanate such as isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI). The present invention preferably isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI) or IPDI and HDI mixture, and its mass accounts for 15%～35% of reaction total solid mass.

Among them, the small molecule chain extender described in step (1) is preferably 1,4-butanediol, 2,3-butanediol, diethylene glycol, 1,6-hexanediol, glycerin, trihydroxypropane, ethyl diol. More preferably 1,4-butanediol, 2,3-butanediol, diethylene glycol, ethylene glycol, most preferably one or more mixtures of 1,4-butanediol, diethylene glycol, and ethylene glycol , which accounts for 1%~6% of the total solid mass of the reaction

Wherein the catalyst described in step (1) is organotin or tertiary amine, specifically including dibutyltin dilaurate, stannous octoate, triethylamine, triethylenediamine, dimethyl hexadecylamine, bisdimethyl Amino ethyl ether, nitrogen ethyl morpholine, triethanolamine, ethanolamine, pyridine or N, N'-lutidine, etc., preferably dibutyltin dilaurate, triethylenediamine, the amount of catalyst accounts for the total solid mass of the reaction 0.1%~0.5%.

Wherein the organosilicon described in step (2) is organosilicon monomer or polyorganosiloxane; preferably alkylalkoxysilane, phenylalkoxysilane, alkylchlorosilane, hydroxyl-terminated siloxane, hydroxyl-terminated Polysiloxane, Dimethylcyclosiloxane, Tetramethylphenyldichlorosilane, Trialkoxysilane Methacrylate, Methylpolysiloxane; more preferably Hydroxy-Terminated Silicone, Hydroxy-Terminated Silicone Oxane, its mass accounts for 0.1%-10% of the total solids.

Wherein the monoglyceride described in step (2) is preferably glyceryl monostearate, pentaerythritol fatty acid ester, esterified rosin, orthosilicate, more preferably one or both of glyceryl monostearate and pentaerythritol fatty acid ester. A mixture whose mass accounts for 0.1%-10% of the total solids.

Wherein the neutralizing salt forming agent described in step (3) is triethylamine, tripropylamine, triethanolamine, diethylenetriamine, methylamine, ammonia water, sodium hydroxide, potassium hydroxide, preferably triethylamine, hydrogen Potassium oxide.

Wherein the sulfonic acid type chain extender described in step (4) is H2N(CH2)nNH(CH2)mSO3Na(n=1-12, m=1-12), sodium ethylenediamine ethanesulfonate, 1, Sodium 4-butanediol-2-sulfonate and its derivatives, preferably H2N(CH2) ₃ NH(CH2) ₅ SO3Na (X506), sodium ethylenediamine sulfonate or H2N(CH2) ₃ NH(CH2) ₅ A mixture of SO3Na (X506) and sodium ethylenediaminoethanesulfonate, the mass of which accounts for 1.0%-10% of the total solids.

The external emulsifier described in step (4) is a nonionic or anionic emulsifier, and the nonionic emulsifier is: alkylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, polyethylene glycol fatty acid Esters, etc.; anion-type emulsifiers include: alkylbenzene sulfonate, α-olefin sulfonate, alkyl sulfonate, etc., preferably alkylphenol polyoxyethylene ether (OP-10) or dodecyl sulfate Sodium (sps), its mass accounts for 0.5%-6% of the total solids.

Wherein the defoamer described in step (4) is a water-based silicone defoamer, and its mass accounts for 0.02%-1% of the total emulsion mass.

The leather water-based polyurethane synthesized by this technology has a solid content of 50% to 60%, and the product viscosity is less than 1000mPa·s. At a drying temperature of about 50°C, its drying speed is similar to that of ordinary solvent-based polyurethane, and its performance in all aspects can be compared with that of solvent-based polyurethane. Comparable.

The present invention uses two kinds of chain extenders (carboxylic acid type and sulfonic acid type) to improve the emulsification performance of the emulsion, so that the polyurethane and water can be fully emulsified. At the same time, a method of combining self-emulsification and external emulsification can be used to synthesize a stable emulsion. It can also increase the solid content, and use water as the solvent during emulsification, which meets the needs of clean production processes; the final synthesized emulsion has good film-forming performance, fast drying speed, no yellowing, excellent mechanical properties, and short process flow, and is suitable for synthetic leather. Or surface material, can replace solvent-based products.

Detailed ways

The following examples serve to illustrate the invention, but in no way limit the scope of the invention.

Comparative example: Add 1.5kg of polyethylene adipate and 0.035kg of dihydroxypropionic acid (DMPA) into the reaction kettle, mix and stir, put them in a water bath at 90°C, and wait until the solid particles are completely dissolved. Vacuum dehydration at 0.095Mpa for 1.0h. Cool down to 80°C, add a small amount of 1-methyl-2-pyrrolidone (NMP), add IPDI, 0.05kg diethylene glycol (DEG) and 0.3% catalyst according to the OH/NCO molar ratio (R value) of 1.5, React for 2 hours to get the prepolymer; lower the temperature to 50°C, first use a small amount of acetone to reduce the viscosity, then add triethylamine to neutralize and form a salt for 0.5h according to the neutralization degree of 100%, then slowly add sulfur dissolved in water after cooling down to 30°C Acid-type chain extender X506 (0.131kg), 0.068kg alkylphenol polyoxyethylene ether and 0.012kg sodium lauryl sulfate, control the solid content to 55%, high-speed emulsification for 0.5h, drop an appropriate amount of defoamer, reduce The acetone was removed by pressure distillation, and finally a milky white emulsion with bluish light was obtained.

Example 1: Under the operating conditions of the comparative example, 0.4kg polyneopentyl glycol adipate was used to replace part of the polyethylene adipate (the sum of the moles of OH is the same as that of the comparative example), and HDI replaced half of the IPDI (NCO mol number), the prepolymerization reaction time is 3h, all the other conditions are the same as the comparative example, finally obtain a white translucent band bluish emulsion, the solid content is 50%.

Example 2: Under the operating conditions of the comparative example, polyethylene adipate was replaced with 1.0kg polytetrahydrofuran glycol and 0.255kg polyethylene glycol (M=1000), the prepolymerization reaction time was 2.5h, neutralization The concentration is 90%, and all the other conditions are the same as those of the comparative example, finally a white translucent band bluish emulsion is obtained, and the solid content is 52%.

Example 3: Under the operating conditions of the comparative example, replace part of polyethylene adipate with 0.5kg polytetrahydrofuran diol (the sum of its OH moles is the same as that of the comparative example), and add IPDI prepolymerization reaction time according to R=1.3 for 2.5 hours, and the rest of the conditions were the same as those of the comparative example, and finally a white translucent emulsion with bluish light was obtained, with a solid content of 57%.

Example 4: Under the operating conditions of the comparative example, replace polyethylene adipate with 1.475kg polytetrahydrofuran diol and 0.025kg organosilicon 8427 (hydroxyl-terminated siloxane), the prepolymerization reaction time is 3.5h, and the remaining conditions Same as the comparative example, a white translucent emulsion with bluish light was obtained at last, and the solid content was 51%.

Example 5: Under the operating conditions of the comparative example, IPDI was added according to R=1.8, diethylene glycol was replaced with 1,4-butanediol, and the amount of sulfonic acid chain extender was increased to 0.137kg to neutralize The viscosity is 95%, and all the other conditions are the same as those of the comparative example, finally obtain a white translucent emulsion with bluish light, and the solid content is 59%.

Embodiment 6: Under the operating conditions of comparative examples, replace all polyethylene adipate with 1.4kg polytetrahydrofuran glycol and 0.018kg glycerol monostearate, the prepolymerization reaction time is 4.0h, and the degree of neutralization is 110%, all the other conditions are the same as the comparative example, finally obtain a white translucent emulsion with a solid content of 53%.

experiment one

Test Methods:

Viscosity: Under the condition of temperature (25±0.5)℃, use the NDJ-7 rotational viscometer of Shanghai Instrument (Group) Supply and Marketing Company to test.

Storage period: According to GB/T 14732-2006 (urea formaldehyde, phenol formaldehyde, melamine formaldehyde resins for wood industry adhesives), seal the emulsion and store it at room temperature to observe the stratification and thickening and curing. It will expire when the liquid stratifies or solidifies.

Solid content: test according to GB/T2793-1995 (determination of non-volatile content of adhesive).

Mechanical properties: According to GB/T1040-2006 (Test method for tensile properties of plastics), the speed is 50mm/min, and the gauge length is 25mm.

The main performance of the high solid content emulsion for leather of above-mentioned embodiment gained product and import is listed in the following table:

Claims (9)

1. remove from office preparation method, it is characterized in that carrying out according to following step with high solid aquosity urethane:

(1) prepolymerization reaction: with carboxylic monomer and hydrophilic chain extender under 80～100 ℃, 1-3h dewaters under the 0.08-0.1Mpa vacuum tightness, regulate the pre-polymerization temperature to 70-90 ℃, the isocyanate-monomer, small molecule chain extender and the catalyzer that add metering, reaction 2.0-4.0h; Control R value is 1.05-2.0 in the prepolymerization reaction process, and the NCO content of infrared tracing detection question response no longer changes and carries out the next step again; By adding the viscosity that a small amount of solvent is regulated prepolymer, wherein R is meant the mol ratio of total NCO/OH in the reaction process;

(2) monomer modified: be the water vapour permeability behind the increase emulsion film forming, add polyoxyethylene glycol and carry out modification that its molecular weight is 400-2000, its quality accounts for the 1%-15% of total solids; Add organosilicon and Tegin 55G again;

(3) in and salify: on above-mentioned reaction basis, water-bath is cooled to 25-60 ℃, adds in the neutralizing agent and salify 0.5h, and the neutralizing agent consumption is to be that 80-120% adds according to degree of neutralization; Wherein said degree of neutralization is meant the ratio of neutralizing agent and the molar weight of hydrophilic chain extender;

(4) chain extension after the emulsification: sulfonic acid type chainextender and outer emulsifying agent is soluble in water, regulate solid content 50～60%, add emulsification 0.5h under the high-speed stirring, drip proper quantity of defoaming agent, discharging is milky white colour band blue light emulsion.

2. the leather according to claim 1 preparation method of high solid aquosity urethane, it is characterized in that wherein the carboxylic monomer described in the step (1) comprises that molecular weight is 500-3000 polyester polyol or polyester polyethers polyol blend, it accounts for 20% ~ 65% of reaction total solids quality;

Wherein the hydrophilic chain extender described in the step (1) is for containing the small molecules polyvalent alcohol of carboxyl, sulfonic acid (salt) group, and it accounts for 0.5% ~ 8% of reaction total solids quality;

Wherein the isocyanate-monomer described in the step (1) is aliphatics, alicyclic diisocyanate, and its quality accounts for 15% ~ 35% of reaction total solids quality;

Wherein the small molecule chain extender described in the step (1) is 1,4-butyleneglycol, 2, and 3-butyleneglycol, glycol ether, 1,6-hexylene glycol, glycerine, trihydroxy-propane or ethylene glycol, it accounts for 1% ~ 6% of reaction total solids quality,

Wherein the catalyzer described in the step (1) is organic tin or tertiary amines, and catalyst levels accounts for 0.1% ~ 0.5 % of reaction total solids quality.

3. leather according to claim 1 is characterized in that with the preparation method of high solid aquosity urethane wherein organosilicon described in the step (2) is organosilane monomer or organopolysiloxane, and its quality accounts for the 0.1%-10% of total solids;

Wherein mono-glycerides described in the step (2) is single stearic acid glycerine lipoprotein, the sour fat of tetramethylolmethane fat, esterified rosin, tetraethoxy, and its quality accounts for the 0.1%-10% of total solids.

4. leather according to claim 1 is with the preparation method of high solid aquosity urethane, it is characterized in that wherein described in the step (3) in and salt forming agent be triethylamine, tripropyl amine, trolamine, diethylenetriamine, methylamine, ammoniacal liquor, sodium hydroxide or potassium hydroxide.

5. leather according to claim 1 is characterized in that with the preparation method of high solid aquosity urethane wherein the sulfonic acid type chainextender described in the step (4) is H2N (CH2) nNH (CH2) mSO3Na, n=1-12 wherein, m=1-12; Quadrol base ethyl sulfonic acid sodium, 1,4-butyleneglycol-2-sodium sulfonate and derivative thereof, its quality accounts for the 1.0%-10% of total solids;

Wherein the outer emulsifying agent described in the step (4) is non-ionic type or anionic emulsifier, and its quality accounts for the 0.5%-6% of total solids;

Wherein defoamer is the waterborne organic silicon defoamer described in the step (4), and its quality accounts for the 0.02%-1% of total emulsion quality.

6. the leather according to claim 2 preparation method of high solid aquosity urethane, it is characterized in that wherein the carboxylic monomer described in the step (1) is polytetrahydrofuran diol, polyethylene glycol adipate, polyneopentyl glycol adipate, acrylate polyvalent alcohol, polyethylene glycol adipate glycol, poly-hexanodioic acid-1,6-hexylene glycol esterdiol, poly-hexanodioic acid-1,4-butanediol ester glycol, poly-ε-caprolactone diol or polycarbonate-1,6-hexylene glycol esterdiol;

Wherein the hydrophilic chain extender described in the step (1) is 2,2-dimethylol propionic acid, quadrol base ethyl sulfonic acid sodium, 1,4-butyleneglycol-2-sodium sulfonate and derivative thereof;

Wherein the isocyanate-monomer described in the step (1) is isophorone diisocyanate, hexamethylene diisocyanate or its mixture;

Wherein the small molecule chain extender described in the step (1) is 1, one or more mixing of 4-butyleneglycol, glycol ether, ethylene glycol;

Wherein the catalyzer described in the step (1) is dibutyl tin laurate, stannous octoate, triethylamine, triethylene diamine, dimethyl cetylamine, two dimethyl amine benzyl ethyl ether, nitrogen Ethylmorphine quinoline, trolamine, thanomin, pyridine or N, the N'-lutidine.

7. leather according to claim 2 is characterized in that with the preparation method of high solid aquosity urethane wherein organosilicon described in the step (2) is alkylalkoxy silane, octadecyloxy phenyl TMOS, alkyl chlorosilane, terminal hydroxy group siloxanes, hydroxy-terminated polysiloxane, dimethyl cyclosiloxane, tetramethylphenyl dichlorosilane, methacrylic acid trialkoxy silane, methyl polysiloxane; Wherein mono-glycerides described in the step (2) is one or both mixing of single stearic acid glycerine lipoprotein, the sour fat of tetramethylolmethane fat.

8. leather according to claim 2 is with the preparation method of high solid aquosity urethane, it is characterized in that wherein described in the step (3) in and salt forming agent be triethylamine, potassium hydroxide.

9. leather according to claim 2 is characterized in that with the preparation method of high solid aquosity urethane wherein the sulfonic acid type chainextender described in the step (4) is H2N (CH2) ₃NH (CH2) ₅SO3Na, quadrol base ethyl sulfonic acid sodium or H2N (CH2) ₃NH (CH2) ₅The mixture of SO3Na and quadrol base ethyl sulfonic acid sodium;

Wherein the nonionic emulsifier described in the step (4) is: alkylphenol polyoxyethylene, fatty alcohol-polyoxyethylene ether, cithrol; Cloudy release emulsification is: alkylbenzene sulfonate, ɑ-alkene sulfonate, alkylsulfonate.