Wet-process polyurethane resin, wet-process synthetic leather base as well as preparation method and application of wet-process polyurethane resin and wet-process synthetic leather base

Abstract

The invention provides a wet-process polyurethane resin, a wet-process synthetic leather base and a preparation method and application of the wet-process polyurethane resin and the wet-process synthetic leather base. The wet-process polyurethane resin is prepared from polyester polyol, basic dihydric alcohol, diisocyanate, a chain extender and a solvent A in specific parts by weight, the raw material of the basic dihydric alcohol is prepared from bio-based monounsaturated fatty acid, and the raw material of the solvent A is prepared from polyether polyol, diisocyanate, a chain extender and a solvent B. The base dihydric alcohol is defined to have a structure as shown in a formula I. The base dihydric alcohol with the structure as shown in the formula I is matched with the polyester polyol, so that a wet-process synthetic leather base further prepared from the obtained wet-process polyurethane resin through a wet process has good hydrolysis resistance, excellent rebound resilience and good peel strength, and the service life of the wet-process synthetic leather base is prolonged. Meanwhile, the method also has the characteristics of reducing the dependence on petroleum resources and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of polyurethane, and in particular relates to a wet-process polyurethane resin, a wet-process synthetic leather base, and a preparation method and application thereof. Background Art

[0002] Polyurethane synthetic leather, also known as PU synthetic leather, is a plastic product that imitates the composition and structure of natural leather. It is usually made of impregnated non-woven fabric as a mesh layer and a microporous polyurethane layer as a grain layer. It has many advantages, such as high strength, wear resistance, cold resistance, breathability, aging resistance, solvent resistance, soft texture, beautiful appearance, etc., and good processing performance. It is an ideal imitation leather product to replace natural leather, and its performance is better than PVC leather. At present, polyurethane synthetic leather is widely used in clothing, footwear, luggage, furniture and other industries.

[0003] Diols are the main raw materials for the preparation of wet-process polyurethane resins, accounting for more than 20% of the solid content of the resin. The diols commonly used in wet-process polyurethane resins are all derived from petroleum, but petroleum products have high energy consumption, emit a large amount of greenhouse gases, and are non-renewable resources; while vegetable oil polyols are a type of bio-based polyol synthesized by chemical modification using vegetable oil as raw material, and are currently widely used in the field of polyurethane materials.

[0004] The use of bio-based polyols can effectively increase the renewable content of polyurethane products, reduce dependence on petroleum resources, and are biodegradable with little impact on the ecological environment. The production methods of vegetable oil polyols mainly include epoxidation, ozone oxidation, hydroformylation, transesterification and amination. Among them, epoxidation is a relatively mature method in the industrial production of vegetable oil polyols. The common introduction strategy is to prepare bio-based polyols by epoxidation, ring opening, alcoholysis and other reactions or combinations of unsaturated double bonds in vegetable oils, which are often used in polyurethane foams. However, due to the high functionality of the polyhydroxy structure of the bio-based polyols obtained by the epoxidation method, it is difficult to use them in the preparation of ordinary wet polyurethane resins. Summary of the invention

[0005] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a wet-process polyurethane resin, a wet-process synthetic leather base, and a preparation method and application thereof. The wet-process synthetic leather base prepared by using the wet-process polyurethane resin has excellent rebound performance, hydrolysis resistance and high peel strength, while reducing dependence on petroleum-based raw materials and being environmentally friendly.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a wet-process polyurethane resin, wherein the raw materials of the wet-process polyurethane resin include the following components in parts by weight:

[0008]

[0009] The raw material of the base diol includes bio-based monounsaturated fatty acid, and the base diol has a structure shown in the following formula I:

[0010]

[0011] Wherein, R1 is selected from C3-C15 (e.g., C3, C5, C7, C9, C11, C13 or C15, etc.) straight chain or branched hydrocarbon group;

[0012] R2 is selected from C1-C4 (e.g. C1, C2, C3 or C4, etc.) straight or branched chain hydrocarbon groups;

[0013] m is an integer from 2 to 16 (e.g., 2, 4, 6, 8, 10, 12, 14 or 16, etc.);

[0014] n is an integer of 3 to 20 (e.g., 3, 5, 7, 9, 11, 13, 15, 17, 18 or 20).

[0015] The raw materials of the wet-process polyurethane resin provided by the present invention include the above-mentioned basic diol with a specific structure, the raw materials of the basic diol include bio-based monounsaturated fatty acids, and the two hydroxyl groups in the structure of the basic diol are respectively located in the main chain and the side chain. By limiting different side chain lengths and adding polyester polyols, the coagulation rate of the obtained wet-process polyurethane resin in the coagulation bath can be controlled. The inventors have creatively discovered through experiments that maintaining a reasonable coagulation rate can make the prepared wet-process synthetic leather base have good resilience, peel strength and hydrolysis resistance.

[0016] Wherein, the content of the base diol can be 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight or 15 parts by weight, etc.

[0017] The content of the polyester polyol can be 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight or 15 parts by weight, etc.

[0018] The content of the diisocyanate may be 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, 11 parts by weight, 12 parts by weight, etc.

[0019] The content of the chain extender can be 0.1 parts by weight, 0.5 parts by weight, 1 part by weight, 1.5 parts by weight, 2 parts by weight, 2.5 parts by weight or 3 parts by weight.

[0020] The content of the solvent A may be 60 parts by weight, 62 parts by weight, 64 parts by weight, 66 parts by weight, 68 parts by weight, 70 parts by weight, 72 parts by weight, 74 parts by weight, 76 parts by weight, 78 parts by weight or 80 parts by weight, etc.

[0021] In some preferred embodiments, the molecular weight of the base diol is 300-1000 g / mol, for example, 300 g / mol, 400 g / mol, 500 g / mol, 600 g / mol, 700 g / mol, 800 g / mol, 900 g / mol or 1000 g / mol.

[0022] In some preferred embodiments, the hydroxyl value of the base diol is 110 to 380 mgKOH / g, for example, 110 mgKOH / g, 120 mgKOH / g, 140 mgKOH / g, 160 mgKOH / g, 180 mgKOH / g, 200 mgKOH / g, 240 mgKOH / g, 280 mgKOH / g, 320 mgKOH / g, 340 mgKOH / g, 360 mgKOH / g or 380 mgKOH / g, etc.

[0023] In some preferred embodiments, the base diol is obtained by esterifying and epoxidizing bio-based monounsaturated fatty acids and then ring-opening the diol.

[0024] The bio-based monounsaturated fatty acid is used as a raw material, first esterified, then epoxidized to form epoxy fatty acid ester, and then ring-opened with diol under the condition of an acidic catalyst to obtain the basic diol. The present invention does not specifically limit its specific preparation method, and reference can be made to the prior art, for example, reference can be made to the method provided in Kou Xiuying, Yu Guoping. Research on the methyl esterification method of fat and fatty acid [J]. Food Research and Development, 2005, 26 (2): 46-47 and European Polymer Journal 48 (2012) 2097-2106 for preparation. The scheme of the present invention adopts the bio-based monounsaturated fatty acid as a raw material and adopts a diol as a ring-opening agent, which can ensure a single reaction site and ensure that the functionality of the obtained basic diol is controllable; if vegetable oil (such as castor oil and palm oil) is used as a raw material, the saturated stearic acid therein cannot be functionalized and cannot be effectively utilized, and the vegetable oil contains polyunsaturated fatty acids, which will cause the functionality of the obtained basic diol to be uncontrollable and easily cross-linked, making it difficult to use it in the preparation of ordinary wet-process synthetic leather base; similarly, if glycerol, a triol, is used as a ring-opening agent, the polyol obtained by ring opening is also divalent or higher, and likewise cannot be used in ordinary wet-process polyurethane.

[0025] In some preferred embodiments, the bio-based monounsaturated fatty acid includes any one of myristic acid, palmitoleic acid, oleic acid, trans-oleic acid or erucic acid, or a combination of at least two thereof.

[0026] It should be noted that since the basic diol is obtained by esterification and epoxidation of bio-based monounsaturated fatty acids and then diol ring opening, the selection of the bio-based monounsaturated fatty acid will affect the structure of the obtained basic diol, specifically, it will directly determine the selection of R1 and the value range of n in the above-mentioned basic diol having the structure shown in Formula I.

[0027] In some preferred embodiments, the diol is selected from at least one of diols having a C number of 2 to 16 (e.g., 2, 4, 6, 8, 10, 12, 14 or 16, etc.); for example, any one of ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,4-butanediol, 1,6-hexanediol, 1,10-decanediol or 1,16-hexadecanediol or a combination of at least two thereof can be selected.

[0028] Similarly, since the basic diol is obtained by esterification and epoxidation of bio-based monounsaturated fatty acids and then diol ring opening, the selection of the diol will also affect the structure of the obtained basic diol, specifically, it will directly determine the value range of m in the above-mentioned basic diol having the structure shown in Formula I; and the inventors of the present invention creatively discovered during the research process that if the C chain of the selected diol is too short, m will be too small, which will cause the solidification rate of the obtained wet-process polyurethane resin to be too slow, resulting in poor performance of the obtained wet-process base; and if the C chain of the selected diol is too long, m will be too large, which will cause the solidification rate of the obtained wet-process polyurethane resin to be fast, the surface solidification is fast, which will affect the internal solvent and water exchange, resulting in uneven overall solidification, thereby resulting in poor performance of the obtained wet-process synthetic leather base.

[0029] In some preferred embodiments, the two hydroxyl groups of the diol are located at both ends of the C chain, and the diol is selected from at least one of diols having a C number of 3 to 12.

[0030] In some preferred embodiments, the diol is a bio-based diol. The purpose of using bio-based is to make the wet-process polyurethane resin and wet-process synthetic leather base obtained by the present invention more environmentally friendly. Currently commonly used bio-based diols include bio-based ethylene glycol, bio-based 1,3-propylene glycol or bio-based 1,4-butanediol.

[0031] In some preferred embodiments, the esterification agent used in the esterification includes methanol and / or ethanol; the type of the esterification agent will directly determine the selection of R2 in the basic diol having the structure shown in Formula I.

[0032] In some preferred embodiments, the molecular weight of the polyester polyol is 2000-4000 g / mol, for example, 2000 g / mol, 2200 g / mol, 2400 g / mol, 2600 g / mol, 2800 g / mol, 3000 g / mol, 3200 g / mol, 3400 g / mol, 3600 g / mol, 3800 g / mol or 4000 g / mol, etc.

[0033] In some preferred embodiments, the hydroxyl value of the polyester polyol is 25 to 60 mgKOH / g, for example, 25 mgKOH / g, 30 mgKOH / g, 35 mgKOH / g, 40 mgKOH / g, 45 mgKOH / g, 50 mgKOH / g, 55 mgKOH / g or 60 mgKOH / g.

[0034] In some preferred embodiments, the polyester polyol is obtained by polymerizing at least one C2-C10 (e.g., C2, C3, C4, C5, C6, C7, C8, C9 or C10, etc.) dibasic acid and at least one C2-C10 (e.g., C2, C3, C4, C5, C6, C7, C8, C9 or C10, etc.) diol.

[0035] In some preferred embodiments, the C2-C10 dibasic acid includes any one of malonic acid, succinic acid, glutaric acid, adipic acid or phthalic acid, or a combination of at least two thereof.

[0036] In some preferred embodiments, the C2-C10 diol includes any one of ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptanediol, octanediol or diethylene glycol, or a combination of at least two thereof.

[0037] In some preferred embodiments, the diisocyanate includes any one or a combination of at least two of diphenylmethane diisocyanate, toluene diisocyanate, naphthalene diisocyanate or isophorone diisocyanate.

[0038] In some preferred embodiments, the chain extender includes any one of ethylene glycol, propylene glycol or butanediol, or a combination of at least two thereof, such as 1,3-propylene glycol and / or 1,4-butanediol.

[0039] In some more preferred embodiments, the chain extender is of bio-based origin, including any one of bio-based ethylene glycol, bio-based 1,3-propylene glycol or bio-based 1,4-butanediol, or a combination of at least two thereof; selecting the above-mentioned specific bio-based chain extender can further increase the proportion of bio-based materials in the raw materials, making the resulting wet-process polyurethane resin less dependent on petroleum resources and more environmentally friendly.

[0040] In some preferred embodiments, the solvent A comprises N,N-dimethylformamide and / or dimethylacetamide.

[0041] In some preferred embodiments, the coagulation rate of the wet-process polyurethane resin in the coagulation bath is 0.2 to 0.6 mm / min, for example, 0.2 mm / min, 0.21 mm / min, 0.22 mm / min, 0.25 mm / min, 0.26 mm / min, 0.3 mm / min, 0.31 mm / min, 0.35 mm / min, 0.4 mm / min, 0.41 mm / min, 0.45 mm / min, 0.5 mm / min, 0.51 mm / min, 0.52 mm / min, 0.55 mm / min, 0.59 mm / min or 0.6 mm / min, etc.

[0042] In some preferred embodiments, the formation time of the epidermis layer of the wet polyurethane resin in the coagulation bath is 0.5 to 2 min, for example, 0.5 min, 0.6 min, 0.7 min, 0.8 min, 0.9 min, 1.0 min, 1.1 min, 1.2 min, 1.3 min, 1.4 min, 1.5 min, 1.6 min, 1.7 min, 1.8 min, 1.9 min or 2 min, etc.

[0043] Preferably, the total amount of base diol and polyester polyol in the raw material of the wet-process polyurethane resin is 11 to 25 parts by weight, for example, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 18 parts by weight, 19 parts by weight, 20 parts by weight, 21 parts by weight, 22 parts by weight, 23 parts by weight, 24 parts by weight or 25 parts by weight, etc.

[0044] In some embodiments of the present invention, the raw material of the wet polyurethane resin further includes a certain amount of a blocking agent in parts by weight, and the role of the blocking agent is to react with residual isocyanate groups as needed. The amount of the blocking agent added is not particularly limited, and can be added according to the conventional amount in the art, generally 0.01 to 0.1 parts by weight, such as 0.01 parts by weight, 0.02 parts by weight, 0.04 parts by weight, 0.06 parts by weight, 0.08 parts by weight or 0.1 parts by weight, etc.

[0045] In some preferred embodiments, the capping agent includes any one of methanol, ethanol or isopropanol, or a combination of at least two of them.

[0046] In a second aspect, the present invention provides a method for preparing the wet-process polyurethane resin as described in the first aspect, the preparation method comprising the following steps:

[0047] (1) mixing a base diol, a polyester polyol, a portion of a diisocyanate and a portion of a solvent A, and performing a prepolymerization reaction until the NCO value in the system reaches a theoretical value, thereby obtaining a polyurethane prepolymer;

[0048] (2) reacting the polyurethane prepolymer obtained in step (1), the chain extender and the remaining solvent A, and then adding the remaining diisocyanate to carry out a chain growth reaction, and when the viscosity of the system reaches the standard, optionally adding a blocking agent to carry out blocking, thereby obtaining the wet polyurethane resin.

[0049] In some preferred embodiments, the portion of diisocyanate in step (1) accounts for 5-12.5% ​​of the total weight of diisocyanate, for example 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12% or 12.5%, etc.

[0050] In some preferred embodiments, the portion of solvent A in step (1) accounts for 20-60% of the total mass of solvent A, for example 20%, 22%, 24%, 26%, 28%, 30%, 32%, 36%, 40%, 45%, 50%, 55% or 60%, etc.

[0051] In some preferred embodiments, the isocyanate index of the mixed solution obtained by mixing in step (1) is 0.5-0.9 or 1.1-1.2, for example, 0.5, 0.7, 0.9, 1.1, 1.3, 1.5, 1.7, 1.9 or 2, etc. There are no special requirements, as long as the NCO value of the prepolymerization reaction is controlled within the above range.

[0052] In some preferred embodiments, the reaction temperature in step (1) is 70-80°C, such as 70°C, 72°C, 74°C, 76°C, 78°C or 80°C.

[0053] In some preferred embodiments, the reaction time of step (1) is 1 to 1.2 h, for example, 1 h, 1.02 h, 1.04 h, 1.06 h, 1.08 h, 1.1 h, 1.12 h, 1.14 h, 1.16 h, 1.18 h or 1.2 h, etc.

[0054] In some preferred embodiments, the reaction temperature in step (2) is 70-80°C, such as 70°C, 72°C, 74°C, 76°C, 78°C or 80°C.

[0055] In some preferred embodiments, the reaction time of step (2) is 0.3 to 1 h, for example, 0.3 h, 0.4 h, 0.5 h, 0.6 h, 0.7 h, 0.8 h, 0.9 h or 1 h.

[0056] In some preferred embodiments, the viscosity of the system in step (2) is 160-300 Pa·s / 25°C (for example, 160Pa·s / 25°C, 180Pa·s / 25°C, 200Pa·s / 25°C, 220Pa·s / 25°C, 240Pa·s / 25°C, 260Pa·s / 25°C, 280Pa·s / 25°C or 300Pa·s / 25°C, etc.).

[0057] In the present invention, the preparation method can be carried out in the presence of a catalyst known in the art to accelerate the reaction rate, such as an organic tin catalyst. The amount added is not particularly limited and can be added according to the conventional amount in the art.

[0058] In a third aspect, the present invention provides a wet-process synthetic leather base, wherein the wet-process synthetic leather base comprises a base fabric and a coating;

[0059] The raw materials of the coating include, by weight: 100 parts by weight of the wet-process polyurethane resin as described in the first aspect, 50 to 80 parts by weight of solvent B and 10 to 35 parts by weight of wood powder.

[0060] Wherein, the usage amount of the solvent B can be 50 parts by weight, 55 parts by weight, 60 parts by weight, 65 parts by weight, 70 parts by weight, 75 parts by weight or 80 parts by weight, etc.

[0061] The amount of the wood powder can be 10 parts by weight, 15 parts by weight, 20 parts by weight, 25 parts by weight, 30 parts by weight or 35 parts by weight.

[0062] In some preferred embodiments, the solvent B comprises N,N-dimethylformamide and / or dimethylacetamide.

[0063] In the present invention, there is no special requirement for the base fabric, and the base fabric commonly used in the art, such as single-sided raised fabric or single-sided raised knitted fabric, can be selected.

[0064] In a fourth aspect, the present invention provides a method for preparing the wet synthetic leather base as described in the third aspect, the preparation method comprising the following steps:

[0065] (A1) fully mixing the wet polyurethane resin as described in the first aspect, solvent B and wood powder to obtain a working solution;

[0066] (A2) applying the working solution obtained in step (A1) on a base fabric to form a coating, and placing the base fabric with the coating in a coagulation bath for coagulation to obtain a formed bass;

[0067] (A3) The shaped leather obtained in step (A2) is subjected to extrusion and hot water soaking treatment, and then dried to obtain the wet synthetic leather leather.

[0068] In some preferred embodiments, the viscosity of the working fluid obtained in step (A1) is 5 to 10 Pa·s, for example, 5 Pa·s, 6 Pa·s, 7 Pa·s, 8 Pa·s, 9 Pa·s or 10 Pa·s.

[0069] In some preferred embodiments, the concentration of the solvent in the coagulation bath in step (A2) is 20-25wt%, for example, 20wt%, 20.5wt%, 21wt%, 21.5wt%, 22wt%, 22.5wt%, 23wt%, 24wt% or 25wt%, etc.

[0070] In some preferred embodiments, the temperature of the coagulation bath in step (A2) is 25-30°C, for example, 25°C, 26°C, 27°C, 28°C, 29°C or 30°C.

[0071] In some preferred embodiments, the temperature of the hot water immersion treatment in step (A3) is 50-65°C, for example, 50°C, 52°C, 54°C, 56°C, 58°C, 60°C, 62°C, 64°C or 65°C, etc.

[0072] In some preferred embodiments, the drying temperature in step (A3) is 115-125°C, for example, 115°C, 117°C, 119°C, 121°C, 123°C or 125°C.

[0073] Compared with the prior art, the present invention has the following beneficial effects:

[0074] (1) The raw materials of the wet-process polyurethane resin provided by the present invention include specific weight parts of a basic diol, a polyester polyol, a diisocyanate, a chain extender and a solvent A, and the raw materials of the basic diol include a bio-based monounsaturated fatty acid, and the basic diol has a structure shown in Formula I. By using the above-mentioned basic diol having the structure shown in Formula I for matching, the wet-process synthetic leather base further prepared by the wet-process polyurethane resin has good resilience, good hydrolysis resistance and high peel strength;

[0075] (2) The present invention further optimizes the type of basic diol and adjusts the formula so that the coagulation rate of the prepared wet-process polyurethane resin in the coagulation bath is 0.2-0.6 mm / min, and the skin layer formation time in the coagulation bath is 0.5-2 min, thereby making the final wet-process synthetic leather base have better resilience, better hydrolysis resistance, aging resistance and peel strength;

[0076] (3) The present invention limits the raw materials of the base diol to bio-based sources, which reduces the dependence on petroleum and has environmentally friendly characteristics. DETAILED DESCRIPTION

[0077] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0078] Terminology explanation:

[0079] "Skin layer": When the wet polyurethane resin is wet processed in a coagulation bath, the polyurethane mixture is applied to the base fabric, and the base fabric with the polyurethane coating is placed in the coagulation bath. The polyurethane coating is in contact with the liquid in the coagulation bath. The layer where the polyurethane coating first begins to coagulate is called the skin layer. During the experiment, the time when the skin layer is formed can be determined by observation or by temporarily removing the coated base fabric from the coagulation bath.

[0080] Raw material preparation or source:

[0081] (1) Basic diol

[0082] Referring to Kou Xiuying, Yu Guoping. Research on the methylation method of fat and fatty acid [J]. Food Research and Development, 2005, 26(2): 46-47, bio-based monounsaturated fatty acids and methanol are subjected to methylation reaction to prepare fatty acid methyl esters; referring to European Polymer Journal 48(2012)2097-2106, the obtained fatty acid methyl ester is subjected to epoxidation reaction under hydrogen peroxide and formic acid conditions to obtain epoxy fatty acid methyl ester, which is also applicable to the use of ethanol for ethylation first; referring to European Polymer Journal 48(2012)2097-2106, the obtained epoxy fatty acid methyl ester is ring-opened with diols, and the basic diols are obtained through post-treatment.

[0083] Referring to the above preparation method, the following basic diols A to F and methyl oleate polyol were prepared respectively, and the hydroxyl value was determined according to HG / T 2709-2022:

[0084] The following basic diols A to F all have the structure shown in the following formula I:

[0085]

[0086] Base diol A: prepared from oleic acid (CAS 112-80-1), methanol, formic acid, hydrogen peroxide and bio-based 1,3-propylene glycol, with a hydroxyl value of 295 mgKOH / g, where R1 is -C8H 17 , R2 is methyl, m is 3, and n is 6;

[0087] Base diol B: myristic acid (CAS 544-64-9), prepared from ethanol, formic acid, hydrogen peroxide and bio-based 1,4-butanediol, with a hydroxyl value of 241 mgKOH / g, wherein R1 is -C4H9, R2 is ethyl, m is 4, and n is 6;

[0088] Base diol C: oleic acid (CAS 112-80-1), prepared from methanol, formic acid, hydrogen peroxide and 1,6-hexanediol, with a hydroxyl value of 270 mgKOH / g, where R1 is -C8H 17 , R2 is methyl, m is 6, and n is 6;

[0089] Base diol D: oleic acid (CAS 112-80-1), prepared from methanol, formic acid, hydrogen peroxide and 1,10-decanediol, with a hydroxyl value of 230 mgKOH / g, where R1 is -C8H 17 , R2 is methyl, m is 6, and n is 10;

[0090] Base diol E: oleic acid (CAS 112-80-1), prepared from methanol, formic acid, hydrogen peroxide and 1,16-hexadecanediol, with a hydroxyl value of 180 mgKOH / g, where R1 is -C8H 17 , R2 is methyl, m is 6, and n is 16;

[0091] Base diol F: prepared from oleic acid (CAS 112-80-1), methanol, formic acid, hydrogen peroxide and ethylene glycol, with a hydroxyl value of 305 mgKOH / g, wherein R1 is -C8H 17 , R2 is methyl, m is 2, and n is 6.

[0092] Methyl oleate polyol: prepared from oleic acid (CAS 112-80-1), methanol, formic acid, hydrogen peroxide and glycerol, with a hydroxyl value of 421 mgKOH / g.

[0093] (2) Polyester polyol

[0094] Polybutylene adipate diol: molecular weight 2000 g / mol;

[0095] Poly(ethylene glycol)-butylene glycol adipate polyol: functionality 2, molecular weight 2500 g / mol;

[0096] Polyglutaric acid-ethylene glycol-pentylene glycol ester polyol: functionality is 2, molecular weight is 4000g / mol.

[0097] Example 1

[0098] A wet-process polyurethane resin, the raw materials of which include the following components in parts by weight:

[0099]

[0100] The preparation method of the wet-process polyurethane resin provided in this embodiment comprises the following steps:

[0101] (1) mixing base diol C, polybutylene adipate diol, diphenylmethane diisocyanate accounting for 10% of the total mass, and N,N-dimethylformamide accounting for 40% of the total mass, and performing a prepolymerization reaction at 75° C. for 1.1 h, and obtaining a polyurethane prepolymer after the NCO value in the system reaches a theoretical value;

[0102] (2) reacting the polyurethane prepolymer obtained in step (1), bio-based 1,4-butanediol and the remaining N,N-dimethylformamide at 75° C. for 0.5 h, then adding the remaining diphenylmethane diisocyanate to carry out a chain growth reaction, and when the viscosity of the system reaches 200 Pa·s / 25° C., the wet-process polyurethane resin is obtained.

[0103] Example 2

[0104] A wet-process polyurethane resin, the raw materials of which include the following components in parts by weight:

[0105]

[0106]

[0107] The preparation method of the wet-process polyurethane resin provided in this embodiment comprises the following steps:

[0108] (1) mixing base diol B, poly(ethylene glycol-butylene adipate) polyol, 5% by weight of diphenylmethane diisocyanate, and 20% by weight of N,N-dimethylformamide, and performing a prepolymerization reaction at 70° C. for 1.2 h, and obtaining a polyurethane prepolymer after the NCO value in the system reaches a theoretical value;

[0109] (2) reacting the polyurethane prepolymer obtained in step (1), 1,4-butanediol and the remaining N,N-dimethylformamide at 70° C. for 1 hour, then adding the remaining diphenylmethane diisocyanate for chain growth reaction, and when the viscosity of the system reaches 300 Pa·s / 25° C., obtaining the wet-process polyurethane resin.

[0110] Example 3

[0111] A wet-process polyurethane resin, the raw materials of which include the following components in parts by weight:

[0112]

[0113] The preparation method of the wet-process polyurethane resin provided in this embodiment comprises the following steps:

[0114] (1) mixing base diol C, polyglutaric acid-ethylene glycol-pentanediol ester polyol, diphenylmethane diisocyanate accounting for 12% of the total mass, and N,N-dimethylformamide accounting for 40% of the total mass, and prepolymerizing at 80° C. for 1 hour, and obtaining a polyurethane prepolymer after the NCO value in the system reaches the theoretical value;

[0115] (2) The polyurethane prepolymer obtained in step (1), 1,4-butanediol and the remaining N,N-dimethylformamide are reacted at 70° C. for 1 hour, and then the remaining diphenylmethane diisocyanate is added to carry out a chain growth reaction. When the viscosity of the system reaches 180 Pa·s / 25° C., the wet-process polyurethane resin is obtained.

[0116] Example 4

[0117] A wet-process polyurethane resin, which differs from Example 1 in that an equal molar amount of base diol A is used to replace base diol C, and other components and amounts are the same as those in Example 1.

[0118] Example 5

[0119] A wet-process polyurethane resin, which differs from Example 1 in that an equal molar amount of base diol D is used to replace a base diol C, and other components and amounts are the same as those in Example 1.

[0120] Example 6

[0121] A wet-process polyurethane resin, which differs from Example 1 in that an equal molar amount of base diol E is used to replace a base diol C, and other components and amounts are the same as those in Example 1.

[0122] Example 7

[0123] A wet-process polyurethane resin is different from Example 1 in that an equal molar amount of base diol F is used to replace a base diol C, and other components and amounts are the same as those in Example 1.

[0124] Example 8

[0125] A wet-process polyurethane resin, the raw materials of which include the following components in parts by weight:

[0126]

[0127] The preparation method of the wet-process polyurethane resin provided in this embodiment refers to Example 1.

[0128] Example 9

[0129] A wet-process polyurethane resin, the raw materials of which include the following components in parts by weight:

[0130]

[0131] The preparation method of the wet-process polyurethane resin provided in this embodiment refers to Example 1.

[0132] Comparative Example 1

[0133] A wet-process polyurethane resin, which differs from Example 1 in that methyl oleate polyol in an equal molar amount is used to replace the base diol C, and other components and amounts are the same as those in Example 1.

[0134] Comparative Example 2

[0135] A wet-process polyurethane resin, which differs from Example 1 in that the amount of polybutylene adipate diol used is 4 parts by weight, the amount of base diol C used is 16 parts by weight, and other components, amounts used and preparation methods are the same as those in Example 1.

[0136] Comparative Example 3

[0137] A wet-process polyurethane resin, which differs from Example 1 in that the amount of polybutylene adipate diol used is 16 parts by weight, the amount of base diol C used is 4 parts by weight, and other components, amounts used and preparation methods are the same as those in Example 1.

[0138] Application Example 1

[0139] A wet synthetic leather base, the preparation method of which comprises the following steps:

[0140] (1) 100 parts by weight of the wet-process polyurethane resin provided in Example 1, 70 parts by weight of DMF, and 30 parts by weight of wood powder were fully mixed to obtain a working liquid having a viscosity of 6 Pa·s;

[0141] (2) applying the working solution obtained in step (1) on a conventional single-sided raised fabric to form a coating having a thickness of 1.2 mm, and placing the coated single-sided raised fabric in a coagulation bath of a 20 wt % DMF aqueous solution at a temperature of 25° C. to obtain a formed bass after coagulation, and recording the time of epidermal layer formation and the coagulation time of the bass during the coagulation process;

[0142] (3) The shaped leather obtained in step (2) is extruded, soaked in hot water at 60° C., and dried at 120° C. to obtain the wet synthetic leather leather.

[0143] Application Examples 2 to 9

[0144] A wet-process synthetic leather base, which differs from Application Example 1 in that the wet-process polyurethane resins provided in Examples 2 to 9 are used to replace the wet-process polyurethane resin provided in Example 1, and other substances, amounts used and preparation methods are the same as those in Application Example 1.

[0145] Comparative Application Examples 1 to 3

[0146] A wet-process synthetic leather base, which differs from Application Example 1 in that the wet-process polyurethane resins provided in Comparative Examples 1 to 3 are used to replace the wet-process polyurethane resin provided in Example 1, and other substances, amounts used and preparation methods are the same as those in Application Example 1.

[0147] Comparative Application Example 4

[0148] A wet synthetic leather base, which differs from Application Example 1 in that the concentration of DMF in the coagulation bath is 30wt%, and other substances, dosages and preparation methods are the same as those in Application Example 1.

[0149] Performance Test:

[0150] (1) Coagulation time: The finger pressure rebound method (the bass can rebound after the finger or nail presses the surface of the bass) is used to confirm the bass molding. The time from placing the resin-coated base cloth into the coagulation bath to the bass molding is called the coagulation time.

[0151] (2) Skin layer formation time: The time from when the surface resin is completely solidified to form the skin layer is observed. The time from when the base fabric coated with the resin is placed in the coagulation bath to when the skin layer is formed is called the skin layer formation time.

[0152] (3) Hydrolysis resistance: The peel strength attenuation degree of the prepared bass after being immersed in 10% NaOH at room temperature, wherein the immersion time is 24h and 72h; the peel strength is measured according to GB / T 1040.3 standard.

[0153] (4) Resilience: Press the wet bass and record the recovery time. If it recovers within 3 seconds, it means good resilience; if it recovers within 3 to 5 seconds, it means good resilience; if it recovers within 5 to 10 seconds, it means average resilience; if it fails to recover within more than 10 seconds, it means poor resilience.

[0154] According to the above test method, the wet synthetic leather base obtained from Examples 1 to 9 and Comparative Application Examples 1 to 4 was tested, and the test results are shown in Table 1:

[0155] Table 1

[0156]

[0157] From the data in Table 1, we can see that:

[0158] The wet synthetic leather base provided in Application Examples 1 to 9 has good rebound performance, high peel strength and good hydrolysis resistance; specifically, the rebound performance is general, better and good, the original peel strength is as high as 25 to 32 N / 3cm, the peel strength after soaking in 10% NaOH for 24 hours is still as high as 24 to 32 N / 3cm, and the peel strength after soaking in 10% NaOH for 72 hours is still as high as 21 to 30 N / 3cm.

[0159] By comparing the data of Application Example 1 and Comparative Application Examples 1-2, it can be seen that the use of methyl oleate polyol to replace basic diol C will lead to a too fast solidification rate and too short a skin layer formation time, which will lead to poor rebound performance and peel strength of the obtained wet synthetic leather base.

[0160] Comparing the data of Application Example 1 and Comparative Application Examples 2-3, it can be seen that if the addition ratio of the basic diol is relatively too low or too high, the rebound performance and peel strength of the obtained wet-process synthetic leather base will also deteriorate.

[0161] Further comparison of the data of Application Example 1 and Comparative Application Example 4 also shows that too high a concentration of the solvent in the coagulation bath will also lead to deterioration of the resilience and peel strength of the obtained wet-process synthetic leather base.

[0162] Finally, by comparing the data of Application Example 1 and Application Examples 8 to 9, it can be found that if the total amount of base diols and polyester polyols in the raw materials of the wet-process polyurethane resin is too low or too high (that is, the solid content is too high or too low), it will affect the solidification rate, and thus will also have an adverse effect on the resilience and peel strength of the final wet-process synthetic bass.

[0163] The applicant declares that the present invention illustrates a wet-process polyurethane resin and its preparation method and application through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A wet-process polyurethane resin, characterized in that: The raw materials of the wet-process polyurethane resin include the following components in parts by weight: The raw material of the base diol includes bio-based monounsaturated fatty acid, and the base diol has a structure shown in the following formula I: Wherein, R1 is selected from C3-C15 straight chain or branched hydrocarbon group; R2 is selected from C1-C4 straight or branched hydrocarbon groups; m is an integer from 2 to 16; n is an integer from 3 to 20.

2. The wet-process polyurethane resin according to claim 1, characterized in that: The molecular weight of the base diol is 300 to 1000 g / mol; Preferably, the hydroxyl value of the base diol is 110 to 380 mgKOH / g.

3. The wet-process polyurethane resin according to claim 1 or 2, characterized in that: The basic diol is obtained by esterifying and epoxidizing bio-based monounsaturated fatty acids and then ring-opening the diol; Preferably, the bio-based monounsaturated fatty acid comprises any one of myristic acid, palmitoleic acid, oleic acid, trans-oleic acid or erucic acid, or a combination of at least two thereof; Preferably, the diol is selected from at least one diol having a C number of 2 to 16; Preferably, the two hydroxyl groups of the diol are located at both ends of the C chain; Preferably, the diol is a bio-based diol; Preferably, the diol includes any one or a combination of at least two of bio-based 1,3-propylene glycol, bio-based 1,4-butanediol, 1,6-hexanediol, 1,10-decanediol or 1,16-hexadecanediol; Preferably, the esterification agent used in the esterification comprises methanol and / or ethanol.

4. The wet-process polyurethane resin according to any one of claims 1 to 3, characterized in that: The molecular weight of the polyester polyol is 2000-4000 g / mol; Preferably, the hydroxyl value of the polyester polyol is 25 to 60 mgKOH / g; Preferably, the polyester polyol is obtained by polymerizing at least one C2-C10 dibasic acid and at least one C2-C10 diol; Preferably, the C2-C10 dibasic acid includes any one or a combination of at least two of malonic acid, succinic acid, glutaric acid, adipic acid or phthalic acid; Preferably, the C2-C10 diol includes any one of ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptanediol, octanediol or diethylene glycol, or a combination of at least two thereof; Preferably, the diisocyanate includes any one of diphenylmethane diisocyanate, toluene diisocyanate, naphthalene diisocyanate or isophorone diisocyanate, or a combination of at least two thereof.

5. The wet-process polyurethane resin according to any one of claims 1 to 4, characterized in that: The chain extender includes any one of ethylene glycol, propylene glycol or butanediol or a combination of at least two thereof; Preferably, the chain extender is of bio-based origin, including any one or a combination of at least two of bio-based ethylene glycol, bio-based 1,3-propylene glycol or bio-based 1,4-butanediol; Preferably, the solvent A comprises N,N-dimethylformamide and / or dimethylacetamide; Preferably, the coagulation rate of the wet polyurethane resin in the coagulation bath is 0.2 to 0.6 mm / min; Preferably, the skin layer formation time of the wet polyurethane resin in the coagulation bath is 0.5 to 2 minutes; Preferably, the total amount of the base diol and the polyester polyol in the raw material of the wet-process polyurethane resin is 11 to 25 parts by weight; Preferably, the raw material of the wet-process polyurethane resin also includes a blocking agent; Preferably, the content of the end-capping agent in the raw material of the wet-process polyurethane resin is 0.01 to 0.1 parts by weight; Preferably, the capping agent includes any one of methanol, ethanol or isopropanol, or a combination of at least two of them.

6. A method for preparing a wet polyurethane resin according to any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: (1) mixing a base diol, a polyester polyol, a portion of a diisocyanate and a portion of a solvent A, and performing a prepolymerization reaction until the NCO value in the system reaches a theoretical value, thereby obtaining a polyurethane prepolymer; (2) reacting the polyurethane prepolymer obtained in step (1), the chain extender and the remaining solvent A, and then adding the remaining diisocyanate to carry out a chain growth reaction, and when the viscosity of the system reaches the standard, optionally adding a blocking agent to carry out blocking, thereby obtaining the wet-process polyurethane resin.

7. The preparation method according to claim 6, characterized in that: The part of diisocyanate in step (1) accounts for 5 to 12.5% ​​of the total weight of diisocyanate; Preferably, the part of solvent A in step (1) accounts for 20 to 60% of the total mass of solvent A; Preferably, the prepolymerization reaction temperature in step (1) is 70-80° C. and the reaction time is 1-1.2 h; Preferably, the reaction temperature in step (2) is 70-80°C and the reaction time is 0.3-1h; Preferably, the viscosity of the system in step (2) is 160-300 Pa·s / 25°C.

8. A wet synthetic leather bass, characterized in that: The wet synthetic leather bass comprises a base fabric and a coating; The raw materials of the coating include, in parts by weight: 100 parts by weight of the wet polyurethane resin according to any one of claims 1 to 5, 50 to 80 parts by weight of solvent B and 10 to 35 parts by weight of wood powder.

9. A method for preparing a wet synthetic leather base as claimed in claim 8, characterized in that: The preparation method comprises the following steps: (A1) fully mixing the wet polyurethane resin according to any one of claims 1 to 5, solvent B and wood powder to obtain a working solution; (A2) applying the working solution obtained in step (A1) on a base fabric to form a coating, and placing the base fabric with the coating in a coagulation bath for coagulation to obtain a formed bass; (A3) The shaped leather obtained in step (A2) is subjected to extrusion and hot water soaking treatment, and then dried to obtain the wet synthetic leather leather.

10. The preparation method according to claim 9, characterized in that: The viscosity of the working fluid obtained in step (A1) is 5 to 10 Pa·s; Preferably, the concentration of the solvent in the coagulation bath in step (A2) is 20 to 25 wt %; Preferably, the solidification temperature in step (A2) is 25 to 30°C; Preferably, the temperature of the hot water soaking treatment in step (A3) is 50-65°C; Preferably, the drying temperature in step (A3) is 115-125°C.

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