One-component polyurethane coating and preparation method and use method thereof

Abstract

The invention discloses a one-component polyurethane coating and a preparation method and a use method thereof. The coating comprises, by weight, 10-100 parts of a polyurethane resin, 50-1000 parts of a solvent, 0-40 parts of an anti-yellowing oxide, 0.5-8 parts of a blocked isocyanate curing agent A, 0.5-8 parts of a blocked isocyanate curing agent B, and 0-5 parts of an auxiliary agent; the unsealing temperature of the blocked isocyanate curing agent A is 80°C-100°C, and the unsealing temperature of the blocked isocyanate curing agent B is 110°C-180°C. The coating is applied to the surface of a material, can be cured and formed in a low-temperature unsealing stage, and can be used for hot-pressing splicing or hot-pressing repair of materials in a high-temperature unsealing stage, thereby improving the thermal processing performance of the material.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials and relates to a one-component polyurethane coating and a preparation method and a use method thereof. Background Art

[0002] Polyurethane coatings can be divided into one-component polyurethane coatings and two-component polyurethane coatings according to their components. Blocked polyurethane coatings are a one-component polyurethane coating composed of blocked isocyanate and hydroxyl-containing resin. They are easy to use and can exist stably at room temperature. Under high temperature conditions, the blocked isocyanate is unblocked and reacts with the hydroxyl group to achieve curing and cross-linking of the coating film.

[0003] CN114920903A discloses a blocked isocyanate curing agent with a hyperbranched structure and its application in a polyurethane surface resin. The blocked isocyanate curing agent in the technical solution comprises a combination of polyester polyol, diisocyanate, polyhydroxy tertiary amine compound, non-protonic polar solvent and blocking agent. The blocked isocyanate is mixed with Huafeng JF-S-8030D polyurethane resin to prepare the polyurethane surface resin. The blocked isocyanate curing agent is unblocked at high temperature, cross-linked and cured, and the resin is endowed with good solvent resistance and certain self-repairing function.

[0004] CN115926546A discloses a one-component weather-resistant coating and its application. The technology selects a hydroxyl-containing weather-resistant resin (hydroxyl-containing fluorocarbon resin, hydroxyl-containing acrylic resin and hydroxyl-containing polyester resin) and combines it with Asahi Kasei MF60X blocked isocyanate curing agent, and applies it to the first coating and inner bonding layer of the photovoltaic backsheet. After high temperature (170 ºC) unsealing and cross-linking curing, a thermosetting coating is formed, which can withstand more than 100 butanone wiping times.

[0005] CN111040602A discloses a polyurethane coating agent and its preparation method and application. The technology selects different polyols and different types of blocked isocyanates in combination, and applies them to the surface of a polycarbonate substrate. After being unblocked at high temperature (125°C), cross-linked and cured, a thermosetting first coating is formed. KH550 containing active groups is introduced into the first coating to provide chemical bonding forces between the coatings for the coating of the second coating (polysiloxane hardening layer), thereby forming a stable composite coating for application in optical lenses.

[0006] The introduction of blocked isocyanates into polyurethane coatings in the prior art is mainly for the preparation of single-component polyurethane coatings, which are easy to operate, stable in storage, and can be unblocked, cross-linked and cured at a certain temperature. The resulting coating has good solvent resistance, but the coating is not thermoplastic, which limits its scope of application. Summary of the invention

[0007] In order to solve the deficiencies of the prior art, the present invention provides a one-component polyurethane coating and a preparation method and a use method thereof. By introducing blocked isocyanates with different unblocking temperatures, the coating can be unblocked and cross-linked and cured at low temperature, and then subjected to secondary high-temperature unblocking and cross-linking curing. In addition, aliphatic yellowing-resistant polyurethane resins and anti-yellowing oxides are introduced to give the coating excellent UV resistance. The coating is applied to the surface of the material, and can be cured and formed in the low-temperature unblocking stage, and used for hot-pressing splicing or hot-pressing repair of the material in the high-temperature unblocking stage, thereby improving the thermal processing performance of the material.

[0008] The first aspect of the present invention provides a one-component polyurethane coating, comprising, by weight:

[0009] Polyurethane resin 10-100

[0010] Solvent 50-1000

[0011] Anti-yellowing oxide 0-40

[0012] Blocked isocyanate curing agent A 0.5-8

[0013] Blocked isocyanate curing agent B 0.5-8

[0014] Additives 0-5

[0015] The deblocking temperature of the blocked isocyanate curing agent A is 80°C-100°C, and the deblocking temperature of the blocked isocyanate curing agent B is 110°C-180°C.

[0016] Furthermore, the polyurethane resin comprises, by weight:

[0017] Polyol 50-200

[0018] Isocyanate 10-60

[0019] Chain Extender 3-25

[0020] Catalyst 0.02-0.1

[0021] The polyol is selected from any one or more of polyoxypropylene polyol, polytetramethylene glycol polyol, polybutylene adipate diol, polyethylene adipate diol, polyhexane adipate diol, polycaprolactone diol and polycarbonate. The number average molecular weight of the polyol is preferably 1000-3000.

[0022] The isocyanate is selected from aliphatic isocyanates, preferably any one or more of isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), meta-xylylene diisocyanate (XDI), para-1,4-methylxylylene diisocyanate (TMXDI), 2,4,4-trimethylhexane diisocyanate (TMHDI), methylcyclohexylene diisocyanate (HTDI), and dicyclohexylmethylene diisocyanate (HMDI).

[0023] The chain extender is selected from one or more of ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, diethylene glycol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, and 1,4-cyclohexanedimethanolhydroquinonebis(2-hydroxyethyl)ether.

[0024] The catalyst is preferably one or more of organic tin, organic bismuth, organic lead, organic zinc and organic mercury.

[0025] The preparation method of the polyurethane resin comprises the following steps: uniformly mixing isocyanate, polyol, chain extender and catalyst, and obtaining polyurethane resin after complete reaction. Preferably, the polyol and chain extender are dehydrated before use. More preferably, the polyol and chain extender are vacuum dehydrated at 100 ºC-110 ºC until the water content is less than 300 ppm, and then the material is discharged and sealed for storage.

[0026] Furthermore, the solvent is selected from one or more of ethyl acetate, propyl acetate, butyl acetate, acetone, tetrahydrofuran, butanone, dioxane, DMF, and isopropanol.

[0027] Further, the anti-yellowing oxide is selected from TiO2, including but not limited to Longbai Group Snow Lotus® R-996, China National Nuclear Titanium Dioxide R217, R216, Jinchuan Titanium Industry JCR-806, Chemours Ti-Pure™ R-960, Bomar Chemical R930-5, R930-4. The amount of the anti-yellowing oxide (mass ratio of solid content) is preferably 10%-25%.

[0028] Furthermore, the blocked isocyanate curing agent A and the blocked isocyanate curing agent B are selected from phenol, amide, and oxime blocked isocyanate curing agents, and the blocked isocyanate curing agent A includes but is not limited to MDF-75 (unsealing temperature 80 ºC), TDF-75 (unsealing temperature 85 ºC), and MF-K60X (unsealing temperature 90 ºC) of Jingxin Huiming Technology Co., Ltd.; the blocked isocyanate curing agent B includes but is not limited to HDF-75 (unsealing temperature 140 ºC), IPDFS-50 (unsealing temperature 140 ºC), IPDF-50 (unsealing temperature 180 ºC), SBN-70D (unsealing temperature 110 ºC), MF-B60X (unsealing temperature 120 ºC), and TPA-B80X (unsealing temperature 130 ºC) of Jingxin Huiming Technology Co., Ltd.; YL-GB9300 (unsealing temperature 110-130 ºC), YL-GB9200 (unsealing temperature 150-170 ºC).

[0029] Furthermore, the auxiliary agent includes one or more of a leveling agent, a wetting and dispersing agent, an antioxidant, a light stabilizer, and an ultraviolet absorber. The amount of the auxiliary agent (in terms of the mass ratio of the solid content) is preferably 1%-3%.

[0030] The leveling agent is selected from silicone, acrylate, or fluorocarbon, including but not limited to Corning KMT-5257N, KMT-5510, KMT-5502, KMT-5517, KMT-5519, KMT-1020, KMT-1023; Qianyou Chemical AKN-114, AKN-157B, AKN-1010, AKN-1032, AKN-1117, AKN-1131. The wetting and dispersing agent is selected from polyether modified silicone oil, including but not limited to Qianyou Chemical AKN-1045, AKN-1070, AKN-1146, AKN-1148; Corning KMT-3033, KMT-3520; German Evonik BYK-104S, BYK9077. The antioxidant is selected from one or more of 245, 1010, 1035, 1076, 1098 or 3114; the light stabilizer can be a hindered amine light stabilizer selected from one or more of 292, 622, 770, 944, 5050, 5060 or 5151; the ultraviolet absorber is selected from one or more of UV-1, UV-320, UV-1130, UV-P, UV-1164 or UV-234.

[0031] A second aspect of the present invention provides a method for preparing a one-component polyurethane coating, comprising the following steps:

[0032] (1) Add polyurethane resin into a dispersion kettle, add solvent, and stir until completely dissolved;

[0033] (2) Add anti-yellowing oxide, additives, blocked isocyanate curing agent A and blocked isocyanate curing agent B and disperse them evenly.

[0034] A third aspect of the present invention provides a method for using a one-component polyurethane coating, comprising the following steps:

[0035] (1) applying the polyurethane coating on a substrate and curing at 80°C-100°C to form a composite material;

[0036] (2) Maturation at 80°C -90°C.

[0037] The substrate is various types of film materials, including but not limited to polyurethane film, polytetrafluoroethylene film, polyester film, polyvinyl chloride film, etc. The aging time is preferably 48 hours.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The technical solution of the present invention introduces a blocked isocyanate curing agent that can be unblocked at low temperature and high temperature. After aging at low temperature (80°C-90°C), the polyurethane coating has both thermoplasticity and good solvent resistance. In addition, the introduction of the high-temperature sealant provides better interlayer interaction and good bonding strength for thermoplastic processing of composite materials at high temperatures (such as thermal connection of composite materials or thermal repair of damaged parts of composite materials). (2) The technical solution of the present invention is designed to use aliphatic isocyanates and introduce nano-TiO2, which has excellent yellowing resistance. The coating does not yellow after UV aging for 1000 hours. DETAILED DESCRIPTION

[0039] The embodiments of the present invention are described in detail below. The examples of the embodiments are intended to explain the present invention and should not be construed as limiting the present invention. If no specific techniques or conditions are specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be obtained commercially. The amounts of the components are all parts by weight.

[0040] Example 1 Preparation of aliphatic polyurethane resin

[0041] (1) Control the temperature of polycaprolactone (Mn=2000) and diethylene glycol to 100 ºC-110 ºC, evacuate and dehydrate until the moisture content is less than 300 ppm, discharge the material, and seal it for storage.

[0042] (2) Mix 11.5 parts of methylcyclohexylene diisocyanate, 18.0 parts of hexamethylene diisocyanate, 100 parts of polycaprolactone, 10.4 parts of diethylene glycol, and 0.04 parts of bismuth isooctanoate quickly and evenly, and age at 90 ºC-100 ºC for 10-12 h.

[0043] Example 2 Preparation of aliphatic polyurethane resin

[0044] (1) Control the temperature of polytetrahydrofuran (Mn=3000) and 1,4-butanediol to 100 ºC-110 ºC, evacuate and dehydrate until the moisture content is less than 300 ppm, discharge the material, and seal it for storage.

[0045] (2) Quickly mix 19.5 parts of isophorone diisocyanate, 35.9 parts of dicyclohexylmethylene diisocyanate, 150 parts of polytetrahydrofuran, 11.4 parts of 1,4-butanediol, and 0.05 parts of T12, and age at 90 ºC-100 ºC for 10 h-12 h.

[0046] Example 3 Preparation of aliphatic polyurethane resin

[0047] (1) Control the temperature of polycarbonate diol (Mn=1000), polybutylene adipate diol (Mn=2000) and 1,6-hexanediol to 100 ºC-110 ºC, evacuate and dehydrate until the moisture content is less than 300 ppm, discharge the material, and seal it for storage.

[0048] (2) Quickly mix 23.8 parts of isophorone diisocyanate, 28.0 parts of hexamethylene diisocyanate, 75 parts of polycarbonate diol, 11.4 parts of 1,6-hexanediol, and 0.05 parts of T12, and age at 90 ºC-100 ºC for 10 h-12 h.

[0049] Table 1 shows the weight parts of the components used in the synthesis of polyurethane coatings in Examples 4-7 and Comparative Examples 1-3.

[0050]

[0051] Example 4 Preparation of coating

[0052] Raw materials: Table 1

[0053] Preparation process:

[0054] (1) The polyurethane resin prepared in Example 1 was added to a dispersion kettle, and ethyl acetate and dioxane were added and stirred until completely dissolved.

[0055] (2) Add TDF75, HDF75, Zhongnu Titanium Dioxide R-216 and additives (0.08 parts of wetting and dispersing agent 9077, 0.17 parts of leveling agent KMT-5257N, 0.01 parts of 245, 0.01 parts of 292, and 0.01 parts of UV-234), disperse evenly, and discharge.

[0056] Example 5 Preparation of coating

[0057] Raw materials: Table 1

[0058] Preparation process:

[0059] (1) The polyurethane resin prepared in Example 2 was added to a dispersion kettle, and ethyl acetate and DMF were added and stirred until completely dissolved.

[0060] (2) Add MDF75, HDF75, and Snow Lotus ® R-996 and additives (0.4 parts of wetting and dispersing agent 9077, 0.85 parts of leveling agent KMT-5257N, 0.05 parts of 245, 0.05 parts of 944, 0.05 parts of UV-234) are evenly dispersed and discharged.

[0061] Example 6 Preparation of coating

[0062] Raw materials: Table 1

[0063] Preparation process:

[0064] (1) The polyurethane resin prepared in Example 2 was added to a dispersion kettle, and ethyl acetate, dioxane and isopropanol were added and stirred until completely dissolved.

[0065] (2) Add TDF75, IPDFS-50, Zhongnu Titanium Dioxide R-216 and additives (0.27 parts of wetting and dispersing agent 104s, 0.51 parts of leveling agent AKN-1146, 0.03 parts of 1010, 0.03 parts of 292, and 0.03 parts of UV-320), disperse evenly, and discharge.

[0066] Example 7 Preparation of coating

[0067] Raw materials: Table 1

[0068] Preparation process:

[0069] (1) The TPU pellets prepared in Example 3 were added to a dispersion kettle, and ethyl acetate, dioxane and isopropanol were added and stirred until they were completely dissolved.

[0070] (2) Add TDF75, IPDFS-50, Zhongnu Titanium Dioxide R-216 and additives (0.64 parts of wetting and dispersing agent AKN-1070, 1.36 parts of leveling agent KMT-5257N, 0.08 parts of 1010, 0.08 parts of 292, and 0.08 parts of UV-1), disperse evenly, and discharge.

[0071] Comparative Example 1 Preparation of coating

[0072] Raw materials: Table 1

[0073] Preparation process:

[0074] (1) The polyurethane resin prepared in Example 2 was added to a dispersion kettle, and ethyl acetate, dioxane and isopropanol were added and stirred until completely dissolved.

[0075] (2) Add TDF75, China National Titanium Dioxide R-216 and additives (0.16 parts of wetting and dispersing agent AKN-1070, 0.34 parts of leveling agent KMT-5257N, 0.02 parts of 1010, 0.02 parts of 5060, and 0.02 parts of UV-234), disperse evenly, and discharge.

[0076] Comparative Example 2 Preparation of coating

[0077] Raw materials: Table 1

[0078] Preparation process:

[0079] (1) The polyurethane resin prepared in Example 2 was added to a dispersion kettle, and ethyl acetate, dioxane and isopropanol were added and stirred until completely dissolved.

[0080] (2) Add TDF75, IPDFS-50 and additives (0.16 parts of wetting and dispersing agent AKN-1070, 0.34 parts of leveling agent KMT-5517, 0.02 parts of 1010, 0.02 parts of 292, and 0.02 parts of UV-234), disperse evenly, and discharge.

[0081] Comparative Example 3 Preparation of coating

[0082] Raw materials: Table 1

[0083] Preparation process:

[0084] (1) The polyurethane resin prepared in Example 2 was added to a dispersion kettle, and ethyl acetate, dioxane and isopropanol were added and stirred until completely dissolved.

[0085] (2) Add China National Titanium Dioxide R-216 and additives (0.16 parts of wetting and dispersing agent 9077, 0.34 parts of leveling agent KMT-5257N, 0.02 parts of 1010, 0.02 parts of 292, and 0.02 parts of UV-234), disperse evenly, and discharge.

[0086] Application Examples

[0087] The polyurethane coatings prepared in Examples 4-7 and Comparative Examples 1-3 were scraped and coated on a thermoplastic polyurethane film of 70 μm-80 μm, with the coating thickness controlled to be 20 μm-30 μm, and cured to form a polyurethane composite film.

[0088] The composite film was tested for tensile strength, yellowing resistance, solvent resistance and softening point. The test methods are as follows:

[0089] Tensile strength: Tested in accordance with standard Q / AA408-2009, (25±1) mm×(250±1) mm rectangular specimen, set tensile rate to (305±13) mm / min, clamp distance to (76±1) mm. Tensile strength unit: N / cm.

[0090] Yellowing resistance: Test according to HG / T 3689-2014. Cut a sample with a size of not less than 30 mm×10 mm, one piece for yellowing resistance test, and one piece outside the box for test result comparison. Select 2 15 W UV lamps with a wavelength of 280nm~320 nm, and the temperature in the test box is room temperature. The surface of the sample is parallel to the bottom surface of the lamp tube, with a distance of (250±2) mm. Place the sample on the tray with the irradiated surface of the sample facing the light source. The length direction of the sample is perpendicular to the length direction of the lamp tube. Turn on the switch and let the sample irradiate under the UV light. As the radiation energy accumulates, compare it with the non-irradiated sample to observe the surface changes of the sample. After the UV aging test, test the yellowness of the aged sample. The lower the yellowness, the better the yellowing resistance.

[0091] Solvent resistance: Tested in accordance with GB / T 23989-2009. Dip absorbent cotton in methyl ethyl ketone and wipe forward and backward in a fixed rectangular area with appropriate pressure. Repeat each time for about 1 s and observe the changes on the film surface in the wiped area.

[0092] Softening point detection: Thermomechanical analyzer (TMA) is used for detection in the temperature range of 0-300 ºC.

[0093] The specific test results are as follows:

[0094]

[0095] Comparative Example 7 and Comparative Example 2, aliphatic TPU is used to prepare polyurethane coatings. Under the synergistic effect of anti-yellowing oxides, the yellowing resistance is excellent, the yellowing resistance is equivalent to 4-5 levels, and it is basically not yellowing. Comparative Example 6 and Comparative Example 1, Comparative Example 3, introduce a blocked isocyanate curing agent. According to the different unblocking temperatures, after low-temperature aging, the cured coating has a certain solvent resistance. At this time, the coating softening temperature is low. After further aging at high temperature, the coating solvent resistance is further improved, but the softening point is significantly increased. This step-by-step aging design can provide better operating space for thermoplastic processing of composite materials at high temperatures (such as thermal connection of composite materials or thermal repair of damaged composite materials), improve interlayer interaction, and further improve solvent resistance.

Claims

1. A one-component polyurethane coating, comprising, by weight: Polyurethane resin 10-100 Solvent 50-1000 Anti-yellowing oxide 0-40 Blocked isocyanate curing agent A 0.5-8 Blocked isocyanate curing agent B 0.5-8 Additives 0-5 The deblocking temperature of the blocked isocyanate curing agent A is 80°C-100°C, and the deblocking temperature of the blocked isocyanate curing agent B is 110°C-180°C; The blocked isocyanate curing agent A and the blocked isocyanate curing agent B are selected from phenol, amide, and oxime blocked isocyanate curing agents.

2. The coating according to claim 1, characterized in that The polyurethane resin comprises, by weight: Polyol 50-200 Isocyanate 10-60 Chain Extender 3-25 Catalyst 0.02-0.

1.

3. The coating according to claim 2, characterized in that The polyol is selected from any one or more of polyoxypropylene polyol, polytetramethylene glycol polyol, polybutylene adipate diol, polyethylene adipate diol, polyhexane adipate diol, and polycaprolactone diol.

4. The coating according to claim 2, characterized in that The isocyanate is selected from aliphatic isocyanates.

5. The coating according to claim 2, characterized in that: The isocyanate is selected from any one or more of isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), meta-xylylene diisocyanate (XDI), para-1,4-methylxylylene diisocyanate (TMXDI), 2,4,4-trimethylhexane diisocyanate (TMHDI), methylcyclohexylene diisocyanate (HTDI), and dicyclohexylmethylene diisocyanate (HMDI).

6. The coating according to claim 2, characterized in that The chain extender is selected from one or more of ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, diethylene glycol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, and 1,4-cyclohexanedimethanolhydroquinonebis(2-hydroxyethyl)ether.

7. The coating according to claim 2, characterized in that The catalyst is one or more of organic tin, organic bismuth, organic lead, organic zinc, and organic mercury; the solvent is selected from one or more of ethyl acetate, propyl acetate, butyl acetate, acetone, tetrahydrofuran, butanone, dioxane, DMF, and isopropanol; and the anti-yellowing oxide is selected from TiO2.

8. The coating according to claim 7, characterized in that The TiO2 is one or more of Longbai Group's Snow Lotus® R-996, CNNC Titanium Dioxide R217, R216, Jinchuan Titanium Industry's JCR-806, Chemours' Ti-Pure™ R-960, and Bomar Chemical's R930-5 and R930-4.

9. The coating according to claim 1 or 2, characterized in that: The auxiliary agent includes one or more of a leveling agent, a wetting and dispersing agent, an antioxidant, a light stabilizer, and an ultraviolet absorber.

10. A method for preparing the coating according to any one of claims 1 to 9, comprising the following steps: (1) Add polyurethane resin into a dispersion kettle, add solvent, and stir until completely dissolved; (2) Add anti-yellowing oxide, additives, blocked isocyanate curing agent A and blocked isocyanate curing agent B and disperse them evenly.

11. A method for using the coating according to any one of claims 1 to 9, comprising the following steps: (1) applying the polyurethane coating on a substrate and curing at 80°C-100°C to form a composite material; (2) Maturation at 80°C -90°C.

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