An aqueous semi-PU leather and its preparation method

Abstract

The present invention discloses an aqueous semi-PU leather and its preparation method. The feature is to first perform pretreatment on the PVC base, and then through a dry process, use a dry laminating process to complete lamination to obtain the semi-PU leather. Among them, the pretreatment material, the surface layer and the dry laminating layer are all prepared mainly from aqueous environmentally friendly materials. This method can laminate PVC bases with different hardnesses and softnesses, and has a high peel strength, achieving the effect of substrate destruction, solving the problem of poor lamination firmness in simple dry lamination, semi-dry lamination or wet lamination; replacing traditional solvent-based polyurethane resin with aqueous polyurethane resin, solving the pollution problem and enhancing the added value of the product; at the same time, this process is suitable for large-scale industrial production.

Description

Technical Field

[0001] The present invention relates to an aqueous semi-PU leather and a preparation method thereof, belonging to the field of synthetic leather and artificial leather manufacturing. Technical Background

[0002] Semi-PU leather is an upgraded product of PVC leather, achieving the performance effects of PU leather and increasing the added value of PVC leather. It has been widely used in fields such as clothing, luggage, shoe materials, furniture and home decoration, and sports equipment.

[0003] Traditional semi-PU leather is produced using oil-based polyurethane resin, and the solvents such as DMF, ethyl acetate, and methyl ethyl ketone released pollute the surrounding environment and harm the physical and mental health of workers. To protect the environment and achieve sustainable development, the development of environmentally friendly semi-PU leather materials has become a hot topic in this field.

[0004] Since PVC base is airtight, and different PVC bases contain different plasticizers, the surface is flat and very hydrophobic with low surface tension. It is difficult for ordinary aqueous polyurethane materials to bond completely. Even in the case of dry aqueous bonding, problems such as poor bonding are likely to occur, and semi-dry bonding and wet bonding are even more impossible to implement. After bonding, due to the inability of moisture to evaporate, large areas of bulges will appear on the leather surface.

[0005] Patent 201610476053.X discloses an aqueous semi-PU leather base material and a preparation method thereof, but it is not clearly stated whether it is bonding to the base or the fabric, nor is it clear whether it is dry bonding or wet bonding. At the same time, the peel strength is relatively low, the application has limitations, and there are no data for different soft and hard bases.

[0006] Patent 202210351519.0 discloses a manufacturing method of an environmentally friendly semi-polyurethane leather, which is a one-step process using release paper and does not have universality. Summary of the Invention

[0007] Aiming at the above deficiencies in the prior art, the purpose of the present invention is to provide a preparation method of aqueous semi-PU leather, which is characterized by being able to prepare qualified aqueous environmentally friendly semi-PU leather without replacing the existing production line, being suitable for large-scale production and manufacturing, and meeting the bonding requirements of different types of PVC bases.

[0008] The purpose of the present invention is achieved by the following technical measures:

[0009] The present invention provides a preparation method of aqueous semi-PU leather, including the following steps:

[0010] 1) Prepare an aqueous polyurethane surface layer slurry:

[0011] The composition by parts by mass of the raw materials includes: 100 parts of aqueous polyurethane resin, 1 - 2 parts of aqueous wetting and leveling agent, preferably 1.2 - 1.8 parts, 6 - 10 parts of aqueous color paste, preferably 6 - 8 parts, 0.1 - 0.3 parts of aqueous defoaming agent, preferably 0.15 - 0.25 parts, 0.5 - 2 parts of slip and abrasion resistant agent, preferably 0.8 - 1.5 parts, 0.5 - 2 parts of aqueous crosslinking agent, preferably 0.8 - 1.5 parts, 0.5 - 2 parts of aqueous thickening agent, preferably 0.8 - 1.5 parts; Mix the above raw materials evenly by stirring, filter, and prepare an aqueous polyurethane surface layer slurry with a viscosity of 5000 - 8000 cps, preferably 6000 - 7000 cps;

[0012] 2) Prepare the aqueous dry - sticking slurry:

[0013] The composition by parts by mass of the raw materials includes: 100 parts of aqueous polyurethane resin, 3 - 8 parts of aqueous curing agent, preferably 4 - 6 parts, 0.5 - 1 part of aqueous wetting and leveling agent, preferably 0.6 - 0.8 parts, 0.1 - 0.3 parts of aqueous defoaming agent, preferably 0.15 - 0.25 parts, 0.5 - 2 parts of aqueous thickening agent, preferably 0.8 - 1.5 parts; Mix the above raw materials evenly by stirring, filter, and prepare an aqueous polyurethane dry - sticking slurry with a viscosity of 3000 - 6000 cps, preferably 3500 - 5500 cps;

[0014] 3) Prepare the aqueous pretreatment slurry:

[0015] The composition by parts by mass of the raw materials includes: 100 parts of aqueous chloroprene latex, 20 - 60 parts of aqueous polyurethane resin, preferably 30 - 50 parts, 1 - 2 parts of aqueous wetting and leveling agent, preferably 1.2 - 1.8 parts, 5 - 10 parts of aqueous curing agent, preferably 6 - 8 parts, 0.5 - 2 parts of aqueous thickening agent, preferably 0.6 - 1.5 parts. Mix the above raw materials evenly by stirring and prepare an aqueous pretreatment slurry with a viscosity of 1500 - 2500 cps, preferably 1600 - 2300 cps;

[0016] 4) Use the aqueous pretreatment slurry in step 3) to perform surface treatment on the PVC base;

[0017] 5) Spread the aqueous polyurethane surface layer slurry in step 1) on the release paper, dry it, then spread the aqueous dry - sticking slurry in step 2), dry it, and then cover the PVC base after surface treatment in step 4). After pressure lamination, then cool and peel off the release paper to obtain the aqueous semi - PU leather.

[0018] In the present invention, the aqueous polyurethane resin in the aqueous polyurethane surface layer slurry in step 1) is selected from one or more of aqueous polyurethane resins with a modulus of 2 - 10 MPa, preferably 4 - 7 Mpa, and preferably one or more of aqueous polyurethane resins prepared from polyester polyol or polycarbonate polyol; More preferably, those of Wanhua Chemical 3257, 3375, one or more of 3920;

[0019] Step 2) The aqueous dry pasting slurry. The aqueous polyurethane resin is selected from one or more of aqueous polyurethane resins with a modulus of 0.1 - 1.5 MPa, preferably 0.2 - 1.2 MPa, and preferably one or more of aqueous polyurethane resins prepared from polyether polyols, polyester polyols, or polycarbonate polyols; more preferably those of Wanhua Chemical 1258, 3012, one or more of 3451;

[0020] Step 3) The aqueous pretreatment material. The aqueous polyurethane resin is selected from aqueous polyurethane resins with a particle size of 800 - 3000 nm, preferably 1200 - 2200 nm, and preferably one or more of aqueous polyurethane resins prepared from polyester polyols or polycarbonate polyols, and more preferably one or more of aqueous polyurethane resins with self - extinction properties; particularly preferably those of Wanhua Chemical 3101, 3102, 3120, one or more of 3130.

[0021] In the present invention, for step 3) the aqueous pretreatment material, the aqueous chloroprene latex is selected from one or more of anionic or non - ionic types, preferably one or more of the aqueous chloroprene latex SL - 390, aqueous chloroprene latex LA - 710, and aqueous chloroprene latex LA - 502 of Dongguan Xiangfa Rubber and Plastic Materials.

[0022] In the present invention, for steps 1) - 3), the aqueous wetting and leveling agents are all selected from one or more of silicone - based leveling agents and acrylic - based leveling agents, preferably polyether - modified polysiloxane - based leveling agents among silicone - based ones, and more preferably one or more of Chongyao Chemical 3248, Silok Chemical 8022, and Sanyue New Materials 8009.

[0023] In the present invention, for steps 1) - 3), the aqueous thickener is an associative polyurethane thickener, preferably those of Wanhua Chemical U506, U505, one or more of U605.

[0024] In the present invention, for steps 1) - 2), the aqueous defoamer is any one or more of silicone - modified defoamers, polyether - modified defoamers, and mineral - oil - based defoamers, preferably polyether - modified silicone defoamers among silicone - based ones, and more preferably one or more of BASF's 2360 and Avcona's 2524.

[0025] In the present invention, the aqueous color paste in step 1) is selected from any one or more of aqueous dyes, resin-free systems with high pigment content, and resin-containing systems with low pigment content, preferably resin-free systems with high pigment content, and more preferably the PH brand aqueous color paste series of Jiangxi Sanyue.

[0026] In the present invention, the slip and abrasion resistant agent in step 1) is selected from polyether-modified or polyether-emulsified polysiloxane aqueous dispersions, preferably polyether-emulsified polysiloxane aqueous dispersions, and more preferably one or more of Dow Chemical DC51, Silok Chemical Silok 1951, and Silok Chemical Silok 5289w.

[0027] In the present invention, the aqueous crosslinking agent in step 1) is selected from one or more of silicone-based crosslinking agents, polycarbodiimides, and aziridine crosslinking agents, preferably polycarbodiimide crosslinking agents, and more preferably one or more of CA50 from Shanghai Langyi and 5580 from Stahl.

[0028] In the present invention, the aqueous curing agent in steps 2)-3) is an aqueous isocyanate curing agent, preferably one or more of polyether-modified and sulfonic acid-modified water-dispersible aqueous isocyanate curing agents, and more preferably one or more of 166, 161, 268 from Wanhua Chemical.

[0029] In step 4) of the present invention, the surface treatment method uses a three-roller coater for surface treatment, with a mesh number of 60 - 120 mesh, preferably 80 - 100 mesh, a drying temperature of 80 - 160 °C, preferably 120 - 140 °C, and a vehicle speed of 15 - 40 m / min;

[0030] In step 4) of the present invention, during the surface treatment, the dosage of the aqueous pretreatment slurry per unit area is 20 - 80 g / m 2 , preferably 20 - 50 g / m 2 .

[0031] In step 5) of the present invention, the aqueous polyurethane surface layer slurry of step 1) is scraped and coated on a release paper, and the wet film thickness of the scraping and coating is 0.05 - 0.25 mm, preferably 0.1 - 0.18 mm;

[0032] During the drying process of this step, the temperature is 90 - 130 °C, and the time is 1 - 4 min, preferably 1.5 - 3 min;

[0033] Preferably, a stepwise temperature increase method is adopted, and the gradient is preferably 90 - 110 - 120 - 130; the driving rate during the drying process is 7 - 15 m / min.

[0034] In step 5) of the present invention, when scraping the water-based dry paste slurry of step 2), the wet film thickness of scraping is 0.12 - 0.3 mm, preferably 0.16 - 0.25 mm;

[0035] For the drying in this process, the temperature is 90 - 130 °C, preferably 90 - 110 °C, and the time is 30 - 80 s, preferably 40 s - 60 s.

[0036] In step 5) of the present invention, for the pressure lamination, the pressure is 2 - 7 kg, preferably 3 - 5 kg, and it is the cold lamination temperature. Zero clearance is required during lamination.

[0037] The method of the present invention can be used for laminating PVC basses with different hardnesses, and has a high peel strength, achieving the effect of substrate damage, solving the problem of poor lamination in simple dry lamination, semi-dry lamination or wet lamination; this process has many advantages such as being suitable for large-scale industrial production, and can be used in fields such as garment leather, luggage leather, shoe upper leather, sofa leather, equipment leather or home decoration interior leather.

[0038] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0039] By pre-treating the PVC bass, the present invention solves the problem of incomplete dry lamination bonding. The main body of the pre-treatment slurry uses the synergistic effect of water-based neoprene latex and water-based large-particle polyurethane emulsion. The neoprene latex is polymerized from chloroprene, which is close to the polarity of PVC material and has good compatibility. At the same time, the excellent coating ability of the water-based neoprene latex is used to coat the dried large water-based polyurethane particles, and the large particles of polyurethane will be evenly exposed on the surface, improving the roughness of the surface after pre-treatment and at the same time increasing the surface polarity, which is beneficial to the requirement of complete and firm bonding with the water-based polyurethane dry paste adhesive later, with firm bonding and no bulging.

[0040] Without replacing the existing production line, the present invention can meet the lamination of different types of PVC basses, is suitable for large-scale production, is environmentally friendly with water throughout the process, and improves the product competitiveness. Specific implementation examples

[0041] The following combines examples to further illustrate the specific implementation examples of this method. However, the present invention is not limited to the listed examples, and should also include any other known changes within the scope of the rights required by the present invention.

[0042] In each example and comparative example of the present invention, the sources of the main raw materials are as follows. Without special instructions for other raw materials and reagents, they are all obtained through ordinary commercial channels:

[0043] Water-based polyurethane resin:

[0044] Water-based polyurethane surface layer slurry: 3257 (modulus 2 MPa), 3375 (Modulus 2 MPa), 3920 (Modulus 6.5 MPa), Wanhua Chemical;

[0045] Water-based dry pasting slurry: 3451 (Modulus 1.2 MPa), 3012 (Modulus 0.5 MPa), 1258 (Modulus 0.1 MPa), Wanhua Chemical;

[0046] Water-based pretreatment material: 3101 (Particle size 1600 nm), 3102 (Particle size 900 nm), 3120 (Particle size 1400 nm), 3130 (Particle size 2200 nm), Wanhua Chemical;

[0047] Water-based chloroprene latex: SL-390, LA-710, LA-502, Dongguan Xiangfa Rubber and Plastic Materials;

[0048] Water-based wetting and leveling agent: 3248, Chongyao Chemical; 8022, Silok Chemical; 8009, Mitsukoshi New Materials;

[0049] Water-based thickener: U506, U505, U605, Wanhua Chemical;

[0050] Water-based defoamer: 2360, BASF; 2524, Avcona;

[0051] Water-based color paste: PH brand series, Jiangxi Mitsukoshi;

[0052] Slip and wear-resistant agent: DC51, Dow Chemical; Silok 1951, Silok 5289w, Silok Chemical;

[0053] Water-based crosslinking agent: CA50, Shanghai Langyi; 5580, Stahl;

[0054] Water-based curing agent: 166, 161, 268, Wanhua Chemical;

[0055] Example 1

[0056] Prepare water-based semi-PU leather, the steps are as follows:

[0057] 1) Prepare water-based polyurethane surface layer slurry

[0058] The water-based polyurethane resin Wanhua Chemical 3257, 100 parts; Chongyao Chemical 3248, 1 part; waterborne color paste, 6 parts; BASF 2360 waterborne defoamer, 0.1 part; Guangzhou Slokor 5289w slip and abrasion resistant agent, 2 parts; Shanghai Langyi CA50 waterborne crosslinking agent, 2 parts; Wanhua Chemical waterborne thickener U506, 1.7 parts, stirred evenly, filtered, and formulated into a waterborne polyurethane surface layer slurry with a viscosity of 6500 cps;

[0059] 2) Preparation of waterborne dry pasting slurry

[0060] The waterborne polyurethane resin of Wanhua Chemical 3451, 100 parts; Wanhua Chemical waterborne curing agent 166, 6 parts; Chongyao Chemical 3248 waterborne wetting and leveling agent, 0.5 part; BASF 2360 waterborne defoamer, 0.1 part; Wanhua Chemical waterborne thickener U506, 2 parts, stirred evenly, filtered, and formulated into a waterborne polyurethane dry pasting slurry with a viscosity of 6000 cps;

[0061] 3) Preparation of waterborne pretreatment slurry

[0062] 100 parts of waterborne chloroprene latex SL-390, 60 parts of waterborne polyurethane resin of Wanhua Chemical 3102, 60 parts; Chongyao Chemical 3248 waterborne wetting and leveling agent, 1.5 parts; Wanhua Chemical waterborne curing agent 166, 8 parts; Wanhua Chemical waterborne thickener U506, 0.5 part, stirred evenly, and formulated into a waterborne pretreatment slurry with a viscosity of 1500 cps.

[0063] 4) For the PVC base to be veneered, use the waterborne pretreatment slurry in step 3) (dosage: 20 g / m 2 ) for surface treatment by a three-roller machine, with a mesh number of 80, a drying temperature of 80 - 120 °C, and a vehicle speed of 30 m / min;

[0064] 5) Adopt the synthetic leather dry process, scrape the waterborne polyurethane surface layer slurry in step 1) on the release paper, with a wet film thickness of 0.15 mm, then enter the drying oven for drying, adopt a stepped heating method, the temperature gradient of the drying oven is 90 - 110 - 120 - 130 °C, the drying time is 2 min, and the driving rate during the drying process is 7 - 15 m / min; then continue to scrape the waterborne dry pasting slurry in step 2), with a wet film thickness of 0.2 mm, enter the drying oven at 90 - 110 °C for drying for 40 s, then cover the PVC base after surface treatment in step 4), with zero gap, press fit under 4 kg pressure, pass through the cooling roller, and then peel off the release paper to obtain the waterborne semi-PU leather.

[0065] Example 2

[0066] Prepare the water-based semi-PU leather, and the steps are as follows:

[0067] 1) Prepare the water-based polyurethane surface layer slurry

[0068] Mix 70 parts of the water-based polyurethane resin Wanhua Chemical 3375, 30 parts of the water-based polyurethane resin Wanhua Chemical 3920, 1.5 parts of the water-based wetting and leveling agent Guangzhou Silkroad 8022, 6 parts of the water-based color paste, 0.2 parts of the water-based defoaming agent Aofukena 2524, 2 parts of the slip and wear-resistant agent Dow Chemical DC51, 1.5 parts of the water-based cross-linking agent Stahl 5580, 0.8 part of the water-based thickener Wanhua Chemical U605, stir evenly, filter, and prepare a water-based polyurethane surface layer slurry with a viscosity of 6000 cps;

[0069] 2) Preparation of the water-based dry pasting slurry

[0070] Mix 100 parts of the water-based polyurethane resin Wanhua Chemical 3012, 8 parts of the water-based curing agent Wanhua Chemical 166, 1 part of the water-based wetting and leveling agent Guangzhou Silkroad 8022, 0.1 part of the water-based defoaming agent Aofukena 2524, 1.5 parts of the water-based thickener Wanhua Chemical U605, stir evenly, filter, and prepare a water-based polyurethane dry pasting slurry with a viscosity of 5000 cps;

[0071] 3) Prepare the water-based pretreatment slurry

[0072] Mix 100 parts of the water-based chloroprene latex LA-710, 20 parts of the water-based polyurethane resin Wanhua Chemical 3130, 1 part of the water-based wetting and leveling agent Jiangxi Sanyue 8009, 5 parts of the water-based curing agent Wanhua Chemical 161, 0.8 part of the water-based thickener Wanhua Chemical U506, stir evenly, and prepare a water-based pretreatment slurry with a viscosity of 1700 cps.

[0073] 4) For the PVC base to be veneered, use the water-based pretreatment slurry in step 3) (the dosage is 40 g / m 2 ) for surface treatment by a three-roller coater, with a mesh number of 60, a drying temperature of 90 - 120 °C, and a vehicle speed of 25 m / min;

[0074] 5) Adopt the dry process of synthetic leather, scrape the waterborne polyurethane surface layer slurry in step 1) on the release paper, with a wet film thickness of 0.18 mm, then enter the drying oven for drying. Adopt a stepped heating method, with the temperature gradient of the drying oven being 90 - 110 - 120 - 130 °C, the drying time being 2.5 min, and the driving speed during the drying process being 10 m / min; then continue to scrape the waterborne dry laminating slurry in step 2), with a wet film thickness of 0.25 mm, enter the drying oven at 90 - 120 °C for drying for 60 s, then cover the PVC base after surface treatment in step 4), with zero gap, laminate under a pressure of 5 kg, pass through the cooling roller, and then peel off the release paper to obtain the waterborne semi-PU leather.

[0075] Example 3

[0076] The steps for preparing the waterborne semi-PU leather are as follows:

[0077] 1) Prepare the waterborne polyurethane surface layer slurry

[0078] Mix 50 parts of the waterborne polyurethane resin Wanhua Chemical 3257, 50 parts of the waterborne polyurethane resin Wanhua Chemical 3375, 1 part of the waterborne wetting and leveling agent Jiangxi Sanyue 8009, 6 parts of the waterborne pigment paste, 0.2 part of the waterborne defoaming agent BASF 2360, 2 parts of the slip and wear resistant agent Guangzhou Silkroad 1951, 0.5 part of the waterborne crosslinking agent Shanghai Langyi CA50, 0.9 part of the waterborne thickening agent Wanhua Chemical U505 and stir evenly, and then filter to prepare a waterborne polyurethane surface layer slurry with a viscosity of 7000 cps;

[0079] 2) Preparation of the waterborne dry laminating slurry

[0080] Mix 50 parts of the waterborne polyurethane resin Wanhua Chemical 3451, 50 parts of the waterborne polyurethane resin Wanhua Chemical 1258, 5 parts of the waterborne curing agent Wanhua Chemical 166, 1 part of the waterborne wetting and leveling agent Jiangxi Sanyue 8009, 0.1 part of the waterborne defoaming agent BASF 2360, 1 part of the waterborne thickening agent Wanhua Chemical U505 and stir evenly, and then filter to prepare a waterborne polyurethane dry laminating slurry with a viscosity of 4500 cps;

[0081] 3) Prepare the waterborne pretreatment slurry

[0082] Mix 100 parts of the waterborne chloroprene latex LA-502, 50 parts of the waterborne polyurethane resin Wanhua Chemical 3101, 2 parts of the waterborne wetting and leveling agent Chongyao Chemical 3248, 6 parts of the waterborne curing agent Wanhua Chemical 268, 2 parts of the waterborne thickening agent Wanhua Chemical 0.5 parts of U605 were stirred evenly to prepare an aqueous pretreatment slurry with a viscosity of 2100 cps.

[0083] 4) The PVC base to be veneered was treated with the aqueous pretreatment slurry in step 3) (dosage: 80 g / m 2 ) through the surface treatment of a three-plate machine, with a mesh number of 60, a drying temperature of 90 - 160 °C, and a vehicle speed of 26 m / min;

[0084] 5) Using the dry process of synthetic leather, the aqueous polyurethane surface layer slurry in step 1) was scraped onto the release paper, with a wet film thickness of 0.22 mm, and then entered the drying tunnel for drying. The stepwise temperature increase method was adopted, with a temperature gradient in the drying tunnel of 90 - 110 - 120 - 130 degrees Celsius, a drying time of 3 min, and a driving rate during the drying process of 10 m / min; then the aqueous dry pasting slurry in step 2) was continuously scraped, with a wet film thickness of 0.14 mm, entered the drying tunnel at 90 - 125 °C for drying for 35 s, and then the PVC base treated in step 4) was covered, with zero gap, pressed at a pressure of 3 kg, passed through the cooling roller, and then the release paper was peeled off to obtain the aqueous semi-PU leather.

[0085] Example 4

[0086] The steps for preparing the aqueous semi-PU leather were as follows:

[0087] 1) Preparation of the aqueous polyurethane surface layer slurry

[0088] 60 parts of the aqueous polyurethane resin Wanhua Chemical 3920, 40 parts of the aqueous polyurethane resin Wanhua Chemical 3375, 1 part of the aqueous wetting and leveling agent Guangzhou Slok 8022, 6 parts of the aqueous color paste, 0.3 part of the aqueous defoaming agent Afcona 2524, 0.5 part of the slip and wear-resistant agent Dow Chemical DC51, 0.5 part of the aqueous cross-linking agent Shanghai Langyi CA50, 2 parts of the aqueous thickener Wanhua Chemical U506 were stirred evenly, filtered, and prepared into an aqueous polyurethane surface layer slurry with a viscosity of 8000 cps;

[0089] 2) Preparation of the aqueous dry pasting slurry

[0090] 80 parts of the aqueous polyurethane resin Wanhua Chemical 3012, 20 parts of the aqueous polyurethane resin Wanhua Chemical 1258, 8 parts of the aqueous curing agent Wanhua Chemical 161, 0.5 part of the aqueous wetting and leveling agent Guangzhou Slok 8022, 0.1 part of the aqueous defoaming agent BASF 2360, 2 parts of the aqueous thickener Wanhua Chemical Mix 2 parts of U506 evenly, filter it, and prepare an aqueous polyurethane dry pasting slurry with a viscosity of 3000 cps.

[0091] 3) Prepare an aqueous pretreatment slurry

[0092] Mix 100 parts of aqueous chloroprene latex LA-502, 25 parts of aqueous polyurethane resin Wanhua Chemical 3120, 1.2 parts of aqueous wetting and leveling agent Jiangxi Sanyue 8009, 10 parts of aqueous curing agent Wanhua Chemical 166, 1.7 parts of aqueous thickening agent Wanhua Chemical U506 evenly, and prepare an aqueous pretreatment slurry with a viscosity of 1700 cps.

[0093] 4) For the PVC base to be veneered, use the aqueous pretreatment slurry in step 3) (dosage: 45 g / m 2 ) for surface treatment on a three-roller machine, with a mesh number of 70, a drying temperature of 90 - 135 °C, and a vehicle speed of 22 m / min;

[0094] 5) Adopt the synthetic leather dry process, scrape the aqueous polyurethane surface layer slurry in step 1) on the release paper, with a wet film thickness of 0.18 mm, then enter the drying tunnel for drying, using a stepped heating method, with a drying tunnel temperature gradient of 90 - 110 - 120 - 130 °C, a drying time of 2.5 min, and a driving rate during the drying process of 10 m / min; then continue to scrape the aqueous dry pasting slurry in step 2), with a wet film thickness of 0.23 mm, enter the drying tunnel at 90 - 130 °C for drying for 60 s, then cover the PVC base after surface treatment in step 4), with zero gap, press fit under a pressure of 4.5 kg, pass through the cooling roller, and then peel off the release paper to obtain the aqueous semi-PU leather.

[0095] Comparative Example 1

[0096] Refer to the preparation method of Example 1, the difference is only that: omit the aqueous pretreatment slurry in step 3) and the surface treatment step in step 4), and keep other operations unchanged to obtain the aqueous semi-PU leather.

[0097] Comparative Example 2

[0098] Refer to the preparation method of Example 1, the difference is only that: do not add chloroprene latex to the aqueous pretreatment slurry in step 3), and keep other operations unchanged to obtain the aqueous semi-PU leather.

[0099] Comparative Example 3

[0100] Refer to the preparation method of Example 1, the difference is only that: do not use large-particle-size polyurethane emulsion in the aqueous pretreatment slurry in step 3), and keep other operations unchanged to obtain the aqueous semi-PU leather.

[0101] Comparative Example 4

[0102] Refer to the preparation method of Example 1, with the difference being only that: in step 3), the chloroprene latex in the aqueous pretreatment slurry is replaced by styrene-butadiene latex (SBR latex), and other operations remain unchanged, to obtain an aqueous semi-PU leather.

[0103] Comparative Example 5

[0104] Refer to the preparation method of Example 1, with the difference being only that: in step 3), the chloroprene latex in the aqueous pretreatment slurry is replaced by an aqueous acrylic resin, and other operations remain unchanged, to obtain an aqueous semi-PU leather.

[0105] Comparative Example 6

[0106] Refer to the preparation method of Example 1, with the difference being only that: in step 4), PVC is replaced by a polyolefin base, and other operations remain unchanged, to obtain an aqueous semi-PU leather.

[0107] Comparative Example 7

[0108] Refer to the preparation method of Example 1, with the difference being only that: in step 5), the wet pasting process is adopted, and the specific operation is to omit the drying process of the dry pasting glue in step 5) and directly perform zero-gap lamination, and other operations remain unchanged, to obtain an aqueous semi-PU leather.

[0109] The aqueous semi-PU leathers prepared in the examples and comparative examples of the present invention were subjected to performance tests by the following methods, and the results are shown in Table 1:

[0110] 1. Surface effect test: Fold the aqueous semi-PU leather obtained in the above examples and observe whether there are any defective phenomena such as insecure lamination or loose surface.

[0111] 2. Peel strength test: Conduct a peel strength test on the aqueous semi-PU leather obtained in the above examples and record the peel strength of each specimen.

[0112] 3. Normal temperature flexing test: Conduct a normal temperature flexing test on the aqueous semi-PU leather obtained in the above examples.

[0113] 4. Jungle resistance test: Place the aqueous semi-PU leather obtained in the above examples at 70 °C and 90% humidity for 3 weeks, and record whether there are any abnormal conditions such as delamination or brightening.

[0114] 5. Alkaline resistance test: Immerse the aqueous semi-PU leather obtained in the above examples in a 10% NaOH solution for 24 h, then wash and air-dry it, and test its peel strength.

[0115] Table 1:

[0116]

[0117]

[0118] It can be seen from the results that all the data obtained from Examples 1 to 4 for preparing semi-PU leather from semi-PU leather base materials meet the requirements and are significantly improved compared with the prior art.

[0119] The difference between Comparative Example 1 and Example 1 is that in Comparative Example 1, no pretreatment was carried out, resulting in ineffective and firm dry bonding. There will be a phenomenon of loose surface when folded, and the jungle and alkali resistance will directly delaminate, failing to meet the basic performance requirements of PVC leather.

[0120] The difference between Comparative Example 2 and Example 1 is that in Comparative Example 1, there is no chloroprene latex in the aqueous pretreatment slurry, resulting in ineffective and firm dry bonding. There will be a partial loose surface phenomenon when folded, and the jungle and alkali resistance will delaminate, failing to meet the basic performance requirements of PVC leather.

[0121] The difference between Comparative Example 3 and Example 1 is that in Comparative Example 1, there is no aqueous large-particle self-extinguishing resin in the aqueous pretreatment slurry, resulting in ineffective and complete firm bonding during dry bonding. There will be a partial loose surface phenomenon when folded, and the jungle and alkali resistance will delaminate, failing to meet the basic performance requirements of PVC leather.

[0122] The difference between Comparative Example 4 and Example 1 is that in Comparative Example 1, the chloroprene latex in the aqueous pretreatment slurry is replaced with styrene-butadiene rubber latex (SBR latex). Although styrene-butadiene rubber latex can achieve bonding, its jungle and alkali resistance performance is not up to standard, failing to meet the basic performance requirements of PVC leather.

[0123] The difference between Comparative Example 5 and Example 1 is that in Comparative Example 1, the chloroprene latex in the aqueous pretreatment slurry is replaced with aqueous acrylic resin, resulting in low dry bonding peel strength and easy delamination, and the jungle and alkali resistance will delaminate, failing to meet the basic performance requirements of PVC leather.

[0124] The difference between Comparative Example 6 and Example 1 is that in Comparative Example 1, the pre-treated polyolefin base is modified. Since the pretreatment layer has no adhesive force to the polyolefin base, it fails to meet the basic performance requirements of synthetic leather, indicating that the present invention mainly aims at different soft and hard PVC base materials.

[0125] The difference between Comparative Example 7 and Example 1 is that Comparative Example 7 uses a wet bonding process. Because the PVC leather is not breathable, it results in ineffective and firm bonding. There will be a phenomenon of loose surface when folded, and the jungle and alkali resistance will directly delaminate, failing to meet the basic performance requirements of PVC leather.

[0126] In summary, the present invention uses a pre-treatment plus dry pasting process to solve the industrial problem that due to the airtightness of PVC bass and different plasticizers in different PVC bass, the surface is relatively hydrophobic, and even in the case of water-based dry pasting, it is easy to have the problem of poor adhesion, and semi-dry pasting and wet pasting are even more impossible to implement; and without replacing the existing production line, it can meet the lamination of different types of PVC bass and is suitable for large-scale production and manufacturing.

[0127] As described above, the above are only the preferred embodiments of the present invention, and do not impose any formal or substantial limitations on the present invention. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the method of the present invention, several improvements and supplements can still be made, and these improvements and supplements should also be regarded as the protection scope of the present invention. For those skilled in the art, without departing from the spirit and scope of the present invention, any equivalent changes made by using the technical content disclosed above, such as minor changes, modifications and evolutions, are equivalent embodiments of the present invention; at the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the substantial technology of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A preparation method of a water-based semi-PU leather, characterized in that, It includes the following steps: 1) Prepare the aqueous polyurethane surface layer slurry: The raw material mass composition includes: 100 parts of aqueous polyurethane resin, 1 - 2 parts of aqueous wetting and leveling agent, 6 - 10 parts of aqueous color paste, 0.1 - 0.3 part of aqueous defoaming agent, 0.5 - 2 parts of slip and abrasion resistant agent, 0.5 - 2 parts of aqueous crosslinking agent, 0.5 - 2 parts of aqueous thickening agent; Mix the above raw materials evenly by stirring, filter, and prepare an aqueous polyurethane surface layer slurry with a viscosity of 5000 - 8000 cps; 2) Prepare the aqueous dry - sticking slurry: The raw material mass composition includes: 100 parts of aqueous polyurethane resin, 3 - 8 parts of aqueous curing agent, 0.5 - 1 part of aqueous wetting and leveling agent, 0.1 - 0.3 part of aqueous defoaming agent, 0.5 - 2 parts of aqueous thickening agent; Mix the above raw materials evenly by stirring, filter, and prepare an aqueous polyurethane dry - sticking slurry with a viscosity of 3000 - 6000 cps; 3) Prepare the aqueous pretreatment slurry: The raw material mass composition includes: 100 parts of aqueous chloroprene latex, 20 - 60 parts of aqueous polyurethane resin with a particle size of 800 - 3000 nm, 1 - 2 parts of aqueous wetting and leveling agent, 5 - 10 parts of aqueous curing agent, 0.5 - 2 parts of aqueous thickening agent. Mix the above raw materials evenly by stirring and prepare an aqueous pretreatment slurry with a viscosity of 1500 - 2500 cps; 4) Use the aqueous pretreatment slurry in step 3) to perform surface treatment on the PVC base; 5) Knife - coat the aqueous polyurethane surface layer slurry in step 1) on the release paper, dry it, then knife - coat the aqueous dry - sticking slurry in step 2), dry it, then cover the PVC base after surface treatment in step 4), perform pressure lamination, then cool and peel off the release paper to obtain the aqueous semi - PU leather.

2. The preparation method according to claim 1, wherein, It includes the following steps: 1) Prepare the aqueous polyurethane surface layer slurry: The raw material mass composition includes: 100 parts of aqueous polyurethane resin, 1.2 - 1.8 parts of aqueous wetting and leveling agent, 6 - 8 parts of aqueous color paste, 0.15 - 0.25 part of aqueous defoaming agent, 0.8 - 1.5 parts of slip and abrasion resistant agent, 0.8 - 1.5 parts of aqueous crosslinking agent, 0.8 - 1.5 parts of aqueous thickening agent; Mix the above raw materials evenly by stirring, filter, and prepare an aqueous polyurethane surface layer slurry with a viscosity of 6000 - 7000 cps; 2) Prepare the aqueous dry - sticking slurry: The raw material mass composition includes: 100 parts of aqueous polyurethane resin, 4 - 6 parts of aqueous curing agent, 0.6 - 0.8 part of aqueous wetting and leveling agent, 0.15 - 0.25 part of aqueous defoaming agent, 0.8 - 1.5 parts of aqueous thickening agent; Mix the above raw materials evenly by stirring, filter, and prepare an aqueous polyurethane dry - sticking slurry with a viscosity of 3500 - 5500 cps; 3) Prepare the aqueous pretreatment slurry: The raw material mass composition includes: 100 parts of aqueous chloroprene latex, 30 - 50 parts of aqueous polyurethane resin with a particle size of 800 - 3000 nm, 1.2 - 1.8 parts of aqueous wetting and leveling agent, 6 - 8 parts of aqueous curing agent, 0.6 - 1.5 parts of aqueous thickening agent. Mix the above raw materials evenly by stirring and prepare an aqueous pretreatment slurry with a viscosity of 1600 - 2300 cps.

3. The preparation method according to claim 1, wherein, Step 1) Waterborne polyurethane surface layer slurry The waterborne polyurethane resin is selected from one or more of waterborne polyurethane resins with a modulus of 2 - 10 MPa; Step 2) Waterborne dry - sticking slurry 4. The preparation method according to claim 3, characterized in that, The waterborne polyurethane resin is selected from one or more of waterborne polyurethane resins with a modulus of 0.1 - 1.5 MPa; 5. The preparation method according to claim 3, characterized in that, Step 3) Waterborne pretreatment material 6. The preparation method according to claim 5, characterized in that The aqueous polyurethane resin is selected from one or more of 3257, 3375, 3920 of Wanhua Chemical. 3257、 3375、 3920.

7. The preparation method according to claim 3, characterized in that, The waterborne polyurethane resin is selected from waterborne polyurethane resins with a particle size of 1200 - 2200 nm.

8. The preparation method according to claim 3, characterized in that Step 1) Waterborne polyurethane surface layer slurry 9. The preparation method according to claim 8, characterized in that, The aqueous polyurethane resin is selected from those of Wanhua Chemical's 1258, 3012, one or more of 3451.

10. The preparation method according to claim 3, characterized in that, The waterborne polyurethane resin is selected from one or more of waterborne polyurethane resins with a modulus of 4 - 7 Mpa.

11. The preparation method according to claim 10, characterized in that, Step 1) Waterborne polyurethane surface layer slurry 12. The preparation method according to claim 11, wherein The aqueous polyurethane resin is selected from among 3101, 3102, 3120, one or more of 3130.

13. The preparation method according to claim 1, wherein The waterborne polyurethane resin is selected from one or more of waterborne polyurethane resins prepared from polyester polyol or polycarbonate polyol.

14. The preparation method according to claim 13, characterized in that, Step 2) Waterborne dry - sticking slurry 15. The preparation method according to claim 1, characterized in that, The waterborne polyurethane resin is selected from one or more of waterborne polyurethane resins with a modulus of 0.2 - 1.2 Mpa. Step 2) Waterborne dry - sticking slurry The waterborne polyurethane resin is selected from one or more of waterborne polyurethane resins prepared from polyether polyol, polyester polyol or polycarbonate polyol. Step 3) Waterborne pretreatment material The waterborne polyurethane resin is selected from one or more of waterborne polyurethane resins prepared from polyester polyol or polycarbonate polyol. The waterborne polyurethane resin is selected from one or more of waterborne polyurethane resins with self - extinction properties. Step 3) The waterborne chloroprene latex is selected from one or more of anionic or non - ionic types.

16. The preparation method according to claim 15, characterized in that, The waterborne chloroprene latex is selected from one or more of waterborne chloroprene latex SL - 390, waterborne chloroprene latex LA - 710, and waterborne chloroprene latex LA - 502 of Dongguan Xiangfa Rubber and Plastic Materials.

17. The preparation method according to claim 16, characterized in that, The waterborne wetting and leveling agents in Steps 1) - 3) are all selected from one or more of silicone - based leveling agents and acrylic - based leveling agents; 18. The preparation method according to claim 15, wherein, The aqueous thickener described in steps 1)-3) is from Wanhua Chemical U506, U505, one or more of U605.

19. The preparation method according to claim 15, wherein, The waterborne thickener in Steps 1) - 3) is an associative polyurethane thickener; 20. The preparation method according to claim 19, characterized in that, The waterborne defoaming agents in Steps 1) - 2) are any one or more of silicone - modified defoaming agents, polyether - modified defoaming agents, and mineral - oil - based defoaming agents; 21. The preparation method according to claim 15, characterized in that, The waterborne color paste in Step 1) is selected from any one or more of waterborne dyes, resin - free systems with high pigment content, and resin - containing systems with low pigment content; The slip - resistance and wear - resistance agent in Step 1) is selected from polyether - modified or polyether - emulsified polysiloxane aqueous dispersions; The waterborne cross - linker in Step 1) is selected from one or more of silicone - based cross - linkers, polycarbodiimide, and aziridine cross - linkers; The waterborne curing agent in Steps 2) - 3) is a waterborne isocyanate curing agent. The waterborne wetting and leveling agents in Steps 1) - 3) are all selected from polyether - modified polysiloxane - based leveling agents in silicone - based types. The waterborne wetting and leveling agents are all selected from one or more of Chongyao Chemical 3248, Silok Chemical 8022, and Sanyue New Materials 8009. The waterborne defoaming agents in Steps 1) - 2) are polyether - modified silicone defoaming agents in silicone - based types. The waterborne defoaming agent is selected from one or more of BASF's 2360 and Affkina's 2524. The waterborne color paste in Step 1) is selected from resin - free systems with high pigment content.

22. The preparation method according to claim 15, wherein Step 1): The smooth and wear-resistant agent is selected from polyether-emulsified polysiloxane aqueous dispersions.

23. The preparation method according to claim 22, characterized in that, The smooth and wear-resistant agent is selected from one or more of Dow Chemical DC51, Slok Chemical Silok 1951, and Slok Chemical Silok 5289w.

24. The preparation method according to claim 15, characterized in that, Step 1): The aqueous cross-linking agent is selected from one or more of CA50 from Shanghai Langyi and 5580 from Stahl.

25. The preparation method according to claim 15, wherein, Steps 2)-3): The aqueous curing agent is one or more of polyether-modified and sulfonic acid-modified water-dispersible aqueous isocyanate curing agents.

26. The preparation method according to claim 25, characterized in that, The aqueous curing agent described in steps 2)-3) is one of 166, 161, 268 or more than one of them.

27. The preparation method according to claim 1, wherein In Step 4), the surface treatment method uses a three-roller coater, with a mesh number of 60 - 120 mesh, a drying temperature of 80 - 160 °C, and a vehicle speed of 15 - 40 m / min; In step 4), during the surface treatment process, the dosage of the aqueous pretreatment slurry per unit area is 20 - 80 g / m 2 .

28. The preparation method according to claim 27, characterized in that, The mesh number is 80 - 100 mesh, and the drying temperature is 120 - 140 °C.

29. The preparation method according to claim 27, characterized in that, The dosage per unit area of the aqueous pretreatment slurry is 20-50 g / m 2 .

30. The preparation method according to claim 1, characterized in that, In Step 5), the aqueous polyurethane surface layer slurry from Step 1) is scrape-coated on the release paper, and the wet film thickness of the scrape-coating is 0.1 - 0.18 mm; For the drying in this process, the temperature is 90 - 130 °C, and the time is 1 - 4 min.

31. The preparation method according to claim 30, wherein, The wet film thickness of the scrape-coating is 0.1 - 0.18 mm; for the drying, the time is 1.5 - 3 min.

32. The preparation method according to claim 30, characterized in that, For the drying, a stepwise temperature increase method is adopted, with a gradient of 90 - 110 - 120 - 130; the driving rate during the drying process is 7 - 15 m / min.

33. The preparation method according to claim 1, characterized in that, In Step 5), when scrape-coating the aqueous dry laminating slurry from Step 2), the wet film thickness of the scrape-coating is 0.12 - 0.3 mm; For the drying in this process, the temperature is 90 - 130 °C, and the time is 30 - 80 s.

34. The preparation method according to claim 33, characterized in that, The wet film thickness of the scrape-coating is 0.16 - 0.25 mm; the drying temperature is 90 - 110 °C, and the time is 40 - 60 s.

35. The preparation method according to claim 1, wherein, In Step 5), for the pressure lamination, the pressure is 2 - 7 kg, which is the cold lamination temperature, and zero clearance is required during lamination.

36. The preparation method according to claim 35, characterized in that, The pressure is 3 - 5 kg.

37. An aqueous semi-PU leather prepared by the method according to any one of claims 1 - 36.

38. The aqueous semi-PU leather according to claim 37, characterized in that, It can be used for equipment leather or home interior decoration leather.

39. The water-based semi-PU leather according to claim 38, wherein It can be used for clothing leather, luggage leather, shoe upper leather, and sofa leather.

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