A waterproof polyurethane coating for roll materials and its preparation method

Abstract

This invention relates to the field of coating technology and discloses a waterproof polyurethane coating for roll materials and its preparation method. The waterproof polyurethane coating for roll materials of this invention comprises 100 parts by weight of an aqueous polyurethane dispersion, 5-15 parts by weight of silicone-modified styrene-butadiene rubber (SBR), and 0.1-0.4 parts by weight of additives. The carboxylated SBR introduces hydrophobic silane groups, which can reduce the hydrophilicity of the carboxylated SBR itself and the polyurethane, thereby maintaining a lower water absorption rate in the coating film and improving the waterproof performance of the coating. The modified SBR contains a large number of chlorine atoms, which form hydrogen bonds with the amine esters in the polyurethane molecular chain, enhancing the compatibility between SBR and polyurethane. Simultaneously, with the action of additives such as potassium disproportionated rosinate soap, the SBR is more uniformly dispersed in the polyurethane matrix, effectively improving the tensile strength, impact resistance, and other mechanical properties of the coating.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to a waterproof polyurethane coating for roll materials and its preparation method. Background Technology

[0002] Waterborne polyurethane coatings are environmentally friendly, possess excellent elasticity and toughness, and exhibit good anti-aging and anti-corrosion properties, making them widely used in interior wall, basement, and floor waterproofing applications. However, waterborne polyurethane has a high hydrophilicity and water absorption rate, which can affect the water resistance and waterproofing performance of the coating. Therefore, the development of waterborne polyurethane coatings with low water absorption rates is of great significance.

[0003] Polyurethane, as a high-performance polymer material, combines the elasticity of rubber with the strength of plastics. Combining polyurethane with styrene-butadiene rubber (SBR), polybutadiene rubber (PPB), etc., can improve the overall performance of polyurethane. SBR, in particular, possesses excellent wear resistance, heat resistance, and aging resistance, and has important applications in coatings and adhesives. Chinese patent CN113652162B discloses a water-resistant coating for rotary kiln cooling devices and its preparation method. This method involves mixing SBR, dispersants, fillers, etc., to obtain a binder, which is then mixed with polyurethane. The resulting coating exhibits good water and heat resistance; however, the polyurethane coating in this patent has low tensile strength and does not demonstrate good impact resistance. Summary of the Invention

[0004] This invention solves the problem of low mechanical properties such as water resistance and impact resistance of polyurethane coatings.

[0005] The technical solution of the present invention is: a waterproof polyurethane coating comprising 100 parts by weight of waterborne polyurethane dispersion, 5-15 parts by weight of silicone-modified styrene-butadiene rubber, 0.4-0.7 parts by weight of defoamer, 8-25 parts by weight of filler, 0.3-1.4 parts by weight of dispersant, and 0.1-0.4 parts by weight of additives.

[0006] Furthermore, the fillers include fumed silica, talc, and calcium carbonate powder.

[0007] Furthermore, the additives include disproportionated rosinate soap.

[0008] Furthermore, the preparation method of the waterproof polyurethane coating is as follows: add water-based polyurethane dispersion, additives, silicone-modified styrene-butadiene rubber, defoamer, filler, and dispersant to a shearing machine, and shear and disperse to obtain a waterproof polyurethane coating for roll materials.

[0009] Furthermore, the rotation speed during shear dispersion is 300-500 r / min, and the dispersion time is 0.5-2 h.

[0010] Further, the preparation method of organosilicon-modified styrene-butadiene rubber is as follows: 100 parts by weight of carboxylated styrene-butadiene latex is dried and dehydrated, then added to xylene. Under a nitrogen atmosphere, the mixture is heated to 90-100℃ and stirred for 3-5 minutes. 0.01-0.035 parts by weight of triphenylphosphine rhodium chloride catalyst is added and stirred for 3-5 minutes. Then, 3-10 parts by weight of (3-chloropropyl)dimethylsilane are added and the mixture is stirred and reacted for 5-8 hours. The mixture is refluxed during the reaction. After cooling, ethanol is added, and the precipitate is washed with ethanol after filtration and dried to obtain organosilicon-modified styrene-butadiene rubber.

[0011] The beneficial technical effects of this invention are as follows: An addition reaction is performed between the Si-H bonds of (3-chloropropyl)dimethylsilane and the alkenyl groups of carboxylated styrene-butadiene rubber to obtain organosilicon-modified styrene-butadiene rubber. This modified rubber is then compounded with waterborne polyurethane, additives, fillers, etc., to obtain a waterproof polyurethane coating for roll materials. The introduction of hydrophobic silane groups into the carboxylated styrene-butadiene rubber reduces the hydrophilicity of both the rubber itself and the polyurethane, thereby maintaining a lower water absorption rate in the coating film and improving its waterproof performance.

[0012] The styrene-butadiene rubber of this invention contains a large number of chlorine atoms, which form hydrogen bonds with the -NH and C=O groups in the amine ester groups of the polyurethane molecular chain, enhancing the compatibility between styrene-butadiene rubber and polyurethane. At the same time, under the action of additives such as potassium disproportionated rosin soap, the styrene-butadiene rubber is more uniformly dispersed in the polyurethane matrix, effectively improving the mechanical properties of the coating, such as tensile strength and impact resistance. Detailed Implementation

[0013] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0014] The following waterborne polyurethane dispersion has a solid content of 64% and is model Mitsui W-5661. The carboxylated styrene-butadiene latex has a solid content of approximately 48% and is model Qingzhou Jinhao New Materials JH-616. The dispersant is model Anjeka6220 from Anjeka Technology. The defoamer is model BYK019.

[0015] (3-Chloropropyl)dimethylsilane was prepared according to the method described in the journal *Journal of the American Chemical Society*, 2014, vol. 136, #33, pp. 11570-11573, "Surface Functionalization of Silica by Si−H Activation of Hydrosilanes". The structural formula is as follows: .

[0016] Example 1: A method for preparing a waterproof polyurethane coating for roll materials: (1) 100g of carboxylated styrene-butadiene latex was dried and removed from water, and added to 0.8L of xylene. Under a nitrogen atmosphere, it was heated to 100℃ and stirred for 3min. 0.018g of triphenylphosphine rhodium chloride was added and stirred for 5min. Then 5g of (3-chloropropyl)dimethylsilane was added and stirred and refluxed for 5h. After cooling, ethanol was added, and the precipitate was washed with ethanol after filtration and dried to obtain organosilicon modified styrene-butadiene rubber.

[0017] (2) Add 1kg of waterborne polyurethane dispersion, 50g of silicone-modified styrene-butadiene rubber, 1g of disproportionated rosin acid potassium soap, 4g of defoamer, 80g of fumed silica and 3g of dispersant to the shearing machine, shear and disperse for 2h at a speed of 300r / min to obtain waterproof polyurethane coating for rolls.

[0018] Example 2: A method for preparing a waterproof polyurethane coating for roll materials: (1) 100g of carboxylated styrene-butadiene latex was dried and removed from water, and added to 1L of xylene. Under a nitrogen atmosphere, it was heated to 90℃ and stirred for 5min. 0.035g of triphenylphosphine rhodium chloride was added and stirred for 3min. Then 10g of (3-chloropropyl)dimethylsilane was added and stirred and refluxed for 7h. After cooling, ethanol was added, filtered, and the precipitate was washed with ethanol and dried to obtain organosilicon modified styrene-butadiene rubber.

[0019] (2) Add 1kg of waterborne polyurethane dispersion, 75g of silicone-modified styrene-butadiene rubber, 2.5g of disproportionated rosin acid potassium soap, 6g of defoamer, 250g of calcium carbonate powder, and 14g of dispersant to the shearing machine, shear and disperse for 2 hours at a speed of 300r / min to obtain waterproof polyurethane coating for rolls.

[0020] Example 3: A method for preparing a waterproof polyurethane coating for roll materials: (1) 100g of carboxylated styrene-butadiene latex was dried and removed from water, and added to 0.8L of xylene. Under a nitrogen atmosphere, it was heated to 90℃ and stirred for 3min. 0.01g of triphenylphosphine rhodium chloride was added and stirred for 3min. Then 3g of (3-chloropropyl)dimethylsilane was added and stirred and refluxed for 8h. After cooling, ethanol was added, filtered, and the precipitate was washed with ethanol and dried to obtain organosilicon modified styrene-butadiene rubber.

[0021] (2) Add 1kg of waterborne polyurethane dispersion, 100g of silicone-modified styrene-butadiene rubber, 3.2g of disproportionated rosin acid potassium soap, 7g of defoamer, 150g of fumed silica and 8g of dispersant to the shearing machine, shear and disperse for 0.5h at a speed of 500r / min to obtain waterproof polyurethane coating for rolls.

[0022] Example 4: A method for preparing a waterproof polyurethane coating for roll materials: (1) 100g of carboxylated styrene-butadiene latex was dried and removed from water, and added to 1L of xylene. Under a nitrogen atmosphere, it was heated to 100℃ and stirred for 3min. 0.026g of triphenylphosphine rhodium chloride was added and stirred for 3min. Then 7.5g of (3-chloropropyl)dimethylsilane was added and stirred and refluxed for 8h. After cooling, ethanol was added, the precipitate was washed with ethanol after filtration and dried to obtain organosilicon modified styrene-butadiene rubber.

[0023] (2) Add 1kg of waterborne polyurethane dispersion, 150g of silicone-modified styrene-butadiene rubber, 4g of disproportionated rosin acid potassium soap, 4g of defoamer, 220g of talc powder and 13g of dispersant to the shearing machine, shear and disperse for 1h at a speed of 500r / min to obtain waterproof polyurethane coating for rolls.

[0024] Comparative Example 1: A method for preparing a polyurethane coating: (1) Dry the carboxylated styrene-butadiene latex to remove water and obtain carboxylated styrene-butadiene rubber; then add 1 kg of waterborne polyurethane dispersion, 50 g of carboxylated styrene-butadiene rubber, 1 g of disproportionated rosin acid potassium soap, 4 g of defoamer, 80 g of fumed silica and 3 g of dispersant to a shearing machine, shear and disperse for 2 h at a speed of 300 r / min to obtain polyurethane coating.

[0025] Comparative Example 2: A method for preparing a polyurethane coating: (1) 100g of carboxylated styrene-butadiene latex was dried and removed from water, and added to 0.8L of xylene. Under a nitrogen atmosphere, it was heated to 100℃ and stirred for 3min. 0.018g of triphenylphosphine rhodium chloride was added and stirred for 5min. Then 5g of triethylsilane was added and the mixture was stirred, refluxed and cooled for 5h. After cooling, ethanol was added, the precipitate was washed with ethanol after filtration and dried to obtain organosilicon modified styrene-butadiene rubber.

[0026] (2) Add 1 kg of waterborne polyurethane dispersion, 50 g of silicone-modified styrene-butadiene rubber, 1 g of disproportionated rosin acid potassium soap, 4 g of defoamer, 80 g of fumed silica and 3 g of dispersant to a shearing machine, shear and disperse for 2 h at a speed of 300 r / min to obtain polyurethane coating.

[0027] Comparative Example 3: A method for preparing a polyurethane coating: (1) Add 1 kg of waterborne polyurethane dispersion, 50 g of chloroprene rubber, 1 g of disproportionated rosin acid potassium soap, 4 g of defoamer, 80 g of fumed silica and 3 g of dispersant to a shearing machine, shear and disperse for 2 h at a speed of 300 r / min to obtain polyurethane coating.

[0028] The performance of the coatings was tested according to the method specified in standard GB / T 19250-2013.

[0029] Table 1 Performance of Coatings As shown in Table 1, compared with Comparative Example 1, the polyurethane coatings of each embodiment have lower water absorption rates and higher impact resistance, tensile strength, and elongation at break, as well as better waterproofing and mechanical properties. This is mainly due to the addition of silicone-modified styrene-butadiene rubber (SBR). The carboxyl SBR introduces hydrophobic silane groups, which can reduce the hydrophilicity of the carboxyl SBR itself and the polyurethane, thereby maintaining a lower water absorption rate in the coating film and improving the waterproofing performance of the coating. At the same time, SBR contains a large number of chlorine atoms, which form hydrogen bonds with the -NH and C=O groups in the amine ester groups of the polyurethane molecular chain, enhancing the compatibility between SBR and polyurethane, and making SBR uniformly dispersed in the polyurethane matrix, effectively improving the mechanical properties of the coating, with a significant increase in tensile strength and impact resistance.

[0030] Compared to Example 1, the triethylsilane in Comparative Example 2 and the organosilicon-modified styrene-butadiene rubber prepared therefrom do not contain chlorine atoms, resulting in weaker hydrogen bonding with polyurethane. This is detrimental to improving the compatibility between styrene-butadiene rubber and polyurethane, leading to lower tensile strength and elongation at break in the coating. The chloroprene rubber in Comparative Example 3 exhibits poor dispersibility in polyurethane aqueous emulsions, forming phase separation defects in the polyurethane. This is detrimental to reducing aluminum nitrate and severely affects the mechanical properties of the coating, resulting in very low tensile strength and elongation at break.

Claims

1. A waterproof polyurethane coating, characterized in that, The waterproof polyurethane coating comprises 100 parts by weight of waterborne polyurethane dispersion, 5-15 parts by weight of silicone-modified styrene-butadiene rubber, 0.1-0.4 parts by weight of additives, 0.4-0.7 parts by weight of defoamer, 8-25 parts by weight of filler, and 0.3-1.4 parts by weight of dispersant.

2. The waterproof polyurethane coating according to claim 1, characterized in that, The filler is fumed silica, talc, or calcium carbonate powder.

3. The waterproof polyurethane coating according to claim 1, characterized in that, The additive is potassium disproportionated rosinate soap.

4. A method for preparing a waterproof polyurethane coating as described in any one of claims 1-3, characterized in that, The preparation method is as follows: add water-based polyurethane dispersion, silicone-modified styrene-butadiene rubber, additives, defoamer, filler, and dispersant to a shearing machine, and shear and disperse to obtain a waterproof polyurethane coating for roll materials.

5. The method for preparing the waterproof polyurethane coating according to claim 4, characterized in that, The rotation speed during shear dispersion is 300-500 r / min, and the dispersion time is 0.5-2 h.

6. The method for preparing the waterproof polyurethane coating according to claim 4, characterized in that, The preparation method of the organosilicon-modified styrene-butadiene rubber is as follows: carboxylated styrene-butadiene latex is dried to remove water, added to xylene, heated and stirred in a nitrogen atmosphere, triphenylphosphine rhodium chloride catalyst is added, and after stirring, (3-chloropropyl)dimethylsilane is added to carry out the reaction. After cooling, ethanol is added, the precipitate is washed with ethanol after filtration, and dried to obtain organosilicon-modified styrene-butadiene rubber.

7. The method for preparing the waterproof polyurethane coating according to claim 6, characterized in that, The amount of the carboxylated styrene-butadiene latex is 100 parts by weight, (3-chloropropyl)dimethylsilane is 3-10 parts by weight, and triphenylphosphine rhodium chloride is 0.01-0.035 parts by weight.

8. The method for preparing the waterproof polyurethane coating according to claim 6, characterized in that, The heating and stirring temperature is 90-100℃, and the reaction time is 5-8 hours.

9. The application of a waterproof polyurethane coating as described in any one of claims 1-3 in a roll material.

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