High-performance single-component flocking adhesive and preparation method thereof

Abstract

The invention relates to the technical field of flocking adhesives, in particular to a high-performance single-component flocking adhesive and a preparation method thereof.The high-performance single-component flocking adhesive is at least prepared from, by mass, 40-60% of blocked polyurethane, 5-15% of phenol novolac epoxy resin, 0-5% of aromatic nitroso compounds, 0-5% of imine compounds and the balance solvent, the closed polyurethane has an oxime carbamate structure, the weight-average molecular weight is 60000-90000, by optimizing a product formula system, the problems of poor wear resistance, poor solvent resistance and the like after an adhesive is coated are effectively solved, meanwhile, the operation is convenient and fast, the efficiency is high, the application scene and the application range of the adhesive are expanded, and the market demand is better met.

Description

Technical Field

[0001] This invention relates to the field of flocking adhesive technology, specifically to a high-performance single-component flocking adhesive and its preparation method. Background Technology

[0002] In today's society where cars are becoming increasingly common, window sealing strips, as a key component, have received widespread attention. Compared to emerging coatings, traditional flocked sealing strips are favored by many car manufacturers due to their superior wear resistance and low noise characteristics.

[0003] As the medium that tightly bonds the fibers to the rubber, the performance of the sealing strip adhesive largely determines the quality of the sealing strip and greatly affects the customer's actual user experience. Traditional sealing strip adhesives are mostly two-component or multi-component types, meaning that additional components need to be added before use to achieve a certain performance, and the process is often cumbersome. This not only limits the application range of the adhesive product but also greatly reduces production efficiency. In stark contrast, single-component sealing strip adhesives require minimal additional processing and no additional components need to be added before use, making them convenient and efficient.

[0004] Chinese patent (authorization announcement number CN102516919B) discloses a method for preparing a one-component polyurethane flocking adhesive, mainly addressing the problems of poor opening stability and slow curing speed of EPDM (ethylene propylene diene monomer) surface flocking adhesives through product formulation development. However, flocking strips currently on the market prepared using one-component sealing strip adhesives have poor abrasion resistance and weak adhesion of flocking fibers. At the same time, for subsequent deep workpiece processing, most automotive manufacturers are concerned about the solvent resistance of flocking strips, which are precisely the pain points that current one-component adhesives cannot solve. Summary of the Invention

[0005] To address the aforementioned issues, this invention provides a high-performance single-component flocking adhesive and its preparation method. By optimizing the product formulation system, it effectively solves the problems of poor wear resistance and solvent resistance after adhesive coating. At the same time, it is easy to operate and highly efficient, expanding the application scenarios and scope of adhesives and better meeting market demands.

[0006] This invention provides a high-performance single-component flocking adhesive, the raw materials of which, by mass percentage, include at least: 40-60% blocked polyurethane, 5-15% phenolic epoxy resin, 0-5% aromatic nitroso compounds, 0-5% imine compounds, and solvent to make up the balance. The blocked polyurethane has an oxime carbamate structure and a weight-average molecular weight of 60,000-90,000.

[0007] In one embodiment, the raw materials for preparing the high-performance single-component flocking adhesive, by mass percentage, include at least: 50-55% blocked polyurethane, 6-10% phenolic epoxy resin, 2-4% aromatic nitroso compounds, 3-4% imine compounds, and solvent to make up the balance.

[0008] In one embodiment, the raw materials for preparing the blocked polyurethane, by mass percentage, include 19-23% isocyanate, 50-60% polyol, 1-3% blocking agent, 0.2-0.6% chain extender, and the balance being organic solvent.

[0009] In one embodiment, the isocyanate is selected from one or a combination of several of diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), toluene diisocyanate (TDI), or hexamethylene diisocyanate (HDI).

[0010] In one embodiment, the polyol is a polyether polyol using glycerol as an initiator and propylene oxide as a chain extender, wherein the weight-average molecular weight of the polyether polyol is 500-5000.

[0011] In one embodiment, the blocking agent is selected from one or a combination of several of 2-butanone oxime, phenol, σ-caprolactam, imidazole, thiazole, pyrazole, or indole.

[0012] In one embodiment, the chain extender is selected from one or a combination of several of the following: dioxime, methylglyoxime, dimethyl ketone dioxime, dimethylglyoxime, or diphenylglyoxime.

[0013] In one embodiment, the organic solvent is selected from one or more of acetone, butanone, methyl isobutyl ketone, xylene, ethylbenzene, ethyl acetate, or dimethyl carbonate.

[0014] In one embodiment, the method for preparing the closed-type polyurethane includes the following steps:

[0015] The isocyanate is heated and melted, then mixed with an organic solvent while hot and added to the reactor. The temperature is raised to 40-50°C, and a mixture of polyol and chain extender is added in batches. The temperature is raised to 70-80°C and the reaction is maintained for 2.2-2.9 hours. Then the temperature is lowered to 50-60°C, a blocking agent is added, and then the mixture is maintained at 70-80°C for 2-4 hours to mature.

[0016] This invention introduces a blocked polyurethane with an oxime carbamate structure and a weight-average molecular weight of 60,000-90,000 into the flocking adhesive system. This ensures the bonding performance of the flocking adhesive while avoiding the problem of the flock fibers being difficult to implant into the adhesive layer during the subsequent flocking process, thereby effectively guaranteeing the product's abrasion resistance and ethanol resistance.

[0017] Specifically, this invention prepares a closed polyurethane by using diketoxime to extend the polyurethane chain and using 2-butanone oxime to seal the ends, which greatly reduces the sensitivity to moisture during use and extends the product's lifespan after opening.

[0018] In one embodiment, the phenolic epoxy resin is a bisphenol A type epoxy resin (E-03 type), sourced from Jiangsu Runfeng Synthetic Technology Co., Ltd.

[0019] In one embodiment, the aromatic nitroso compound includes at least p-nitrosobenzene.

[0020] In one embodiment, the imine compound is selected from at least one of aldehyde imines or ketimines.

[0021] In one embodiment, the aldehyde imine is designated as F-403 and is sourced from Guangdong Yongjiu Fine Chemical Co., Ltd.

[0022] In one embodiment, the solvent is selected from one or more of acetone, butanone, methyl isobutyl ketone, xylene, ethylbenzene, ethyl acetate, or dimethyl carbonate.

[0023] In one embodiment, the solvent is a combination of xylene, acetone and dimethyl carbonate.

[0024] In one embodiment, the mass ratio of xylene, acetone and dimethyl carbonate is (8-10):1:(5-6).

[0025] This invention optimizes the combination of closed polyurethane with aromatic nitroso compounds and imine compounds in phenolic epoxy resin, enabling the provided flocking adhesive to release a large number of active sites through bond breakage in the soft chain segments after high-temperature curing, thus achieving rapid curing.

[0026] The high-performance single-component flocking adhesive provided by this invention, through the synergistic effect of various raw materials, not only meets the production process requirements of flocked sealing strips but also further enhances the adhesion between the dry film and the rubber substrate, while improving the product's tolerance to ethanol. This not only extends the service life of the flocked sealing strips but also increases the convenience of post-processing.

[0027] Another aspect of the present invention provides a method for preparing a high-performance single-component flocking adhesive, comprising at least the following steps: stirring and mixing a blocked polyurethane, a phenolic epoxy resin, an aromatic nitroso compound, an imine compound, and a solvent until no obvious insoluble matter remains.

[0028] Beneficial effects

[0029] 1. This invention provides a high-performance single-component flocking adhesive and its preparation method. By optimizing the product formulation system, it effectively solves the problems of poor wear resistance and solvent resistance after adhesive coating. At the same time, it is easy to operate and highly efficient, expanding the application scenarios and scope of adhesives and better meeting market demands.

[0030] 2. This invention introduces a closed polyurethane with an oxime carbamate structure and a weight-average molecular weight of 60,000-90,000 into the flocking adhesive system, which ensures the bonding performance of the flocking adhesive while avoiding the problem of the flock fibers being difficult to implant into the adhesive layer during the subsequent flocking process, thereby effectively ensuring the abrasion resistance and ethanol resistance of the product.

[0031] 3. This invention prepares a closed polyurethane by using diketoxime to extend the polyurethane chain and using 2-butanone oxime to seal the ends. This greatly reduces the sensitivity to moisture during use and extends the product's lifespan after opening.

[0032] 4. This invention optimizes the combination of closed polyurethane with aromatic nitroso compounds and imine compounds in the phenolic epoxy resin system, so that after the provided flocking adhesive is cured at high temperature, the soft chain segments break bonds and release a large number of active sites, achieving rapid curing.

[0033] 5. The high-performance single-component flocking adhesive provided by this invention, through the synergistic effect of various raw materials, enables the product to not only meet the production process requirements of flocked sealing strips but also further improve the adhesion between the dry film and the rubber substrate, while also enhancing the product's tolerance to ethanol. This not only extends the service life of the flocked sealing strips but also increases the convenience of post-processing. Attached Figure Description

[0034] Figure 1 The figures show the water and air resistance test results of the flocking adhesive provided in Examples 1-5 of this invention and the commercially available 852F adhesive. In the figures, af corresponds to the flocking adhesive provided in Examples 1-5 and the commercially available 852F adhesive, respectively. Detailed Implementation

[0035] Blocked polyurethane 1-1

[0036] The raw materials for preparing the blocked polyurethane 1-1, by mass percentage, include 23% isocyanate, 55% polyol, 2% blocking agent, 0.2% chain extender, and organic solvent to make up the balance.

[0037] The isocyanate is diphenylmethane diisocyanate (MDI).

[0038] The polyol is a polyether polyol with a weight-average molecular weight of 700, model number INOVOLC307, and is sourced from Shandong Yinuowei Polyurethane Co., Ltd.

[0039] The blocking agent is 2-butanone oxime.

[0040] The chain extender is dimethylglyoxime.

[0041] The organic solvent is xylene.

[0042] The preparation method of the blocked polyurethane 1-1 includes the following steps: heating and melting isocyanate, mixing it with organic solvent while hot and adding it to a reactor, raising the temperature to 45°C, adding a mixture of polyether polyol and chain extender in batches (three equal batches), raising the temperature to 75°C, keeping the reaction at this temperature for 1.9 hours, then lowering the temperature to 60°C, adding the blocking agent, and then keeping the temperature at 75°C for 3 hours to mature.

[0043] The weight-average molecular weight of the closed polyurethane 1-1 is 40,000, and the gravitational viscosity (2# Zahn cup, 25℃) is 24s.

[0044] Closed-cell polyurethane 1-2

[0045] The specific implementation of the closed polyurethane 1-2 is the same as that of the closed polyurethane 1-1, except that the heat preservation reaction of 1.9h is replaced by a heat preservation reaction of 2h. The weight-average molecular weight of the closed polyurethane 1-2 is 50,000, and the gravitational viscosity (2# Zahn cup, 25℃) is 32s.

[0046] Closed-cell polyurethane 1-3

[0047] The specific implementation of the closed polyurethane 1-3 is the same as that of the closed polyurethane 1-1, except that the heat preservation reaction of 1.9h is replaced by a heat preservation reaction of 2.2h. The weight-average molecular weight of the closed polyurethane 1-2 is 60,000, and the gravitational viscosity (2# Zahn cup, 25℃) is 43s.

[0048] Blocked polyurethane 1-4

[0049] The specific implementation of the closed polyurethane 1-4 is the same as that of the closed polyurethane 1-1, except that the heat preservation reaction of 1.9h is replaced by a heat preservation reaction of 2.4h. The weight-average molecular weight of the closed polyurethane 1-4 is 70,000, and the gravitational viscosity (2# Zahn cup, 25℃) is 46s.

[0050] Blocked polyurethane 1-5

[0051] The specific implementation of the closed polyurethane 1-5 is the same as that of the closed polyurethane 1-1, except that the heat preservation reaction of 1.9h is replaced by a heat preservation reaction of 2.9h. The weight-average molecular weight of the closed polyurethane 1-5 is 90,000, and the gravitational viscosity (2# Zahn cup, 25℃) is 61s.

[0052] Closed-cell polyurethane 1-6

[0053] The specific implementation of the closed polyurethane 1-6 is the same as that of the closed polyurethane 1-1, except that the heat preservation reaction of 1.9h is replaced by a heat preservation reaction of 3.5h. The weight-average molecular weight of the closed polyurethane 1-6 is 120,000, and the gravitational viscosity (2# Zahn cup, 25℃) is 74s.

[0054] Closed polyurethane 2

[0055] The specific implementation of the blocked polyurethane 2 is the same as that of blocked polyurethanes 1-3, except that, by mass percentage, the raw materials for preparing the blocked polyurethane 1 include 21% isocyanate, 55% polyol, 2% blocking agent, 0.4% chain extender, and the balance being organic solvent. The weight-average molecular weight of the blocked polyurethane 1 is 60,000, and its gravitational viscosity (2# Zahn cup, 25°C) is 43 s.

[0056] Closed polyurethane 3

[0057] The specific implementation of the blocked polyurethane 3 is the same as that of blocked polyurethanes 1-3, except that, by mass percentage, the raw materials for preparing the blocked polyurethane 1 include 19% isocyanate, 55% polyol, 2% blocking agent, 0.6% chain extender, and the balance being organic solvent. The weight-average molecular weight of the blocked polyurethane 1 is 60,000, and its gravitational viscosity (2# Zahn cup, 25°C) is 43 s.

[0058] Example 1

[0059] Example 1 of the present invention provides a high-performance single-component flocking adhesive, which, by mass percentage, comprises: 1-3 50% blocked polyurethane, 10% phenolic epoxy resin, 4% aromatic nitroso compound, 4% imine compound, and solvent to make up the balance.

[0060] The phenolic epoxy resin is a bisphenol A type epoxy resin (E-03 type), which is sourced from Jiangsu Runfeng Synthetic Technology Co., Ltd.

[0061] The aromatic nitroso compound is p-dinitrosbenzene.

[0062] The imine compound is an aldehyde imine, specifically model F-403, sourced from Guangdong Yongjiu Fine Chemical Co., Ltd.

[0063] The solvent is a combination of xylene, acetone and dimethyl carbonate, wherein the mass ratio of xylene, acetone and dimethyl carbonate is 9:1:6.

[0064] Example 1 of the present invention provides a method for preparing a high-performance single-component flocking adhesive, comprising the following steps: stirring and mixing a blocked polyurethane, a phenolic epoxy resin, an aromatic nitroso compound, an imine compound, and a solvent until there is no obvious insoluble matter.

[0065] Example 2

[0066] Example 2 of the present invention provides a high-performance single-component flocking adhesive and its preparation method. The specific implementation method is the same as that of Example 1, except that, by mass percentage, the raw materials include: 1-3 55% blocked polyurethane, 6% phenolic epoxy resin, 2% aromatic nitroso compound, 4% imine compound, and solvent to make up the balance.

[0067] Example 3

[0068] Example 3 of the present invention provides a high-performance single-component flocking adhesive and its preparation method. The specific implementation method is the same as that of Example 1, except that the blocked polyurethane 1-3 is replaced with blocked polyurethane 2.

[0069] Example 4

[0070] Example 4 of the present invention provides a high-performance single-component flocking adhesive and its preparation method. The specific implementation method is the same as that of Example 1, except that, by mass percentage, the raw materials include: 2.55% blocked polyurethane, 6% phenolic epoxy resin, 2% aromatic nitroso compound, 4% imine compound, and solvent to make up the balance.

[0071] Example 5

[0072] Example 5 of the present invention provides a high-performance single-component flocking adhesive and its preparation method. The specific implementation method is the same as that of Example 1, except that, by mass percentage, the raw materials include: 3.55% blocked polyurethane, 6% phenolic epoxy resin, 2% aromatic nitroso compound, 4% imine compound, and solvent to make up the balance.

[0073] Example 6

[0074] Example 6 of the present invention provides a high-performance single-component flocking adhesive and its preparation method. The specific implementation method is the same as that of Example 1, except that the blocked polyurethane 1-3 is replaced with blocked polyurethane 1-4.

[0075] Example 7

[0076] Example 7 of the present invention provides a high-performance single-component flocking adhesive and its preparation method. The specific implementation method is the same as that of Example 1, except that the blocked polyurethane 1-3 is replaced with blocked polyurethane 1-6.

[0077] Performance testing

[0078] 1. Moisture resistance test: The flocking adhesive provided in Examples 1-5 and commercially available 852F adhesive were tested. 852F) was placed in a 100mL reagent bottle and left open in a constant temperature and humidity chamber at 35-40% humidity and 25℃. The gravitational viscosity of the product was tested at intervals using a #2 Zahn cup. The results are shown in [reference needed]. Figure 1 ,analyze Figure 1 It can be seen that the high-performance single-component flocking adhesive of the present invention exhibits a viscosity increase that is much smaller than that of traditional grades under high humidity conditions, thus greatly extending its service life.

[0079] 2. After the vulcanized rubber strip is subjected to plasma treatment, it is placed in an oven at 80℃±5℃ and heated for 5 minutes. While it is hot, the flocking adhesive provided in Examples 1-7 and the commercially available 852F adhesive are coated on the surface of the rubber strip. The flocking is performed by electrostatic flocking. Then, it is placed in an oven at 220℃ and cured for 130 seconds. After cooling, the flocked sealing strip sample is obtained and the following tests are performed. The results are shown in Table 1.

[0080] (1) Abrasion test of flocked strips: The following abrasion test was conducted on the sample strips, and the results are shown in Table 1.

[0081] 1) Metal grinding (500g / 2000 cycles) was performed based on the PR231-2019 standard, and the wear marks on the specimens after grinding were rated.

[0082] 2) Dry grinding of metal grinding heads (238g / 250 times) was performed based on the PV3366 standard, and the wear marks of the specimens after wear were rated.

[0083] Table 1

[0084]

[0085]

[0086] Analysis of the data in Table 1 shows that the high-performance single-component flocking adhesive of the present invention, under normal abrasion conditions, has no significant difference in quality inspection compared with traditional brands.

[0087] (2) Adhesion test: The adhesion was determined based on the GMW 16774 standard. A special mold was used to cover the sample strip, and hot melt adhesive was injected through the hole. After it was completely cooled, the sample was demolded, and the maximum force that completely peeled off the hot melt adhesive was tested. The test results are shown in Table 2.

[0088] Table 2

[0089] Adhesion strength value / KN Example 1 18.16 Example 2 23.44 Example 3 29.21 Example 4 29.31 Example 5 28.11 Example 6 27.04 Example 7 23.9 852F glue 23.63

[0090] Analysis of the data in Table 2 shows that the high-performance single-component flocking adhesive of the present invention has a stronger maximum adhesion than traditional grades when the adhesion test is conducted, which further proves that the single-component flocking adhesive has a stronger adhesion to the rubber substrate.

[0091] (3) Ethanol resistance test: The test was conducted in accordance with GB / T 21282 standard. The sample was immersed in ethanol for 60 seconds and then immediately subjected to abrasion test (1kg / 100 times). The test results are shown in Table 3.

[0092] Table 3

[0093]

[0094]

[0095] Analysis of the data in Table 3 shows that the high-performance single-component flocking adhesive of the present invention exhibits performance far exceeding that of traditional grades in the ethanol resistance test, further proving that the single-component flocking adhesive has a higher crosslinking density, exhibits stronger resistance after ethanol immersion, and has stronger post-processing operability.

Claims

1. A high-performance single-component flocking adhesive, characterized in that, The raw materials for its preparation, by mass percentage, include at least: 40-60% blocked polyurethane, 5-15% phenolic epoxy resin, 0-5% aromatic nitroso compounds, 0-5% imine compounds, and solvent to make up the balance. The blocked polyurethane has an oxime carbamate structure and a weight-average molecular weight of 60,000-90,000.

2. The high-performance single-component flocking adhesive according to claim 1, characterized in that, The raw materials for preparing the blocked polyurethane, by mass percentage, include 19-23% isocyanate, 50-60% polyol, 1-3% blocking agent, 0.2-0.6% chain extender, and organic solvent to make up the balance.

3. The high-performance single-component flocking adhesive according to claim 2, characterized in that, The isocyanate is selected from one or a combination of several of diphenylmethane diisocyanate, isophorone diisocyanate, toluene diisocyanate or hexamethylene diisocyanate.

4. The high-performance single-component flocking adhesive according to claim 2, characterized in that, The polyol is a polyether polyol using glycerol as an initiator and propylene oxide as a chain extender, and the weight-average molecular weight of the polyether polyol is 500-5000.

5. The high-performance single-component flocking adhesive according to claim 2, characterized in that, The blocking agent is selected from one or a combination of several of 2-butanone oxime, phenol, σ-caprolactam, imidazole, thiazole, pyrazole, or indole.

6. The high-performance single-component flocking adhesive according to claim 2, characterized in that, The chain extender is selected from one or a combination of several of the following: dioxime, methylglyoxime, dimethyl ketone dioxime, dimethylglyoxime, or diphenylglyoxime.

7. The high-performance single-component flocking adhesive according to claim 2, characterized in that, The preparation method of the blocked polyurethane includes the following steps: heating and melting isocyanate, mixing it with an organic solvent while hot and adding it to a reactor, raising the temperature to 40-50°C, adding a mixture of polyol and chain extender in batches, raising the temperature to 70-80°C, maintaining the temperature for 2.2-2.9 hours, then lowering the temperature to 50-60°C, adding a blocking agent, and then maintaining the temperature at 70-80°C for 2-4 hours for curing.

8. The high-performance single-component flocking adhesive according to claim 1, characterized in that, The aromatic nitroso compounds include at least p-nitrosobenzene.

9. The high-performance single-component flocking adhesive according to claim 1, characterized in that, The solvent is selected from one or more of acetone, butanone, methyl isobutyl ketone, xylene, ethylbenzene, ethyl acetate, or dimethyl carbonate.

10. A method for preparing a high-performance single-component flocking adhesive according to any one of claims 1-9, characterized in that, It includes at least the following steps: mixing blocked polyurethane, phenolic epoxy resin, aromatic nitroso compounds, imine compounds, and solvent until there are no obvious insoluble substances.

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