One-component polyurethane primer and adhesive tape using the same

Abstract

The application provides a single-component polyurethane primer, and raw materials for preparing the single-component polyurethane primer include: alcohol materials, the alcohol materials including polyester polyols, the polyester polyols including at least one of polyethylene glycol butanediol adipate polyol, polyethylene glycol diethylene glycol adipate polyol and poly-3-methyl-1,5-pentanediol adipate polyol; isocyanate materials, the isocyanate materials including diisocyanate and polyisocyanate, the diisocyanate and / or the polyisocyanate including an aromatic ring in a molecular structure, and the diisocyanate:polyisocyanate = 6-12:1-5 in terms of mass ratio; additives, the additives including a catalyst; a solvent; and the alcohol materials:isocyanate materials = 1-2:0.7-1.7 in terms of mass ratio. The single-component polyurethane primer can form a primer layer with large surface tension, solvent resistance and corrosion resistance to solvents in a glue layer, and can improve the surface tension of a substrate.

Description

Technical Field

[0001] This invention belongs to the field of primer technology, specifically, it relates to a one-component polyurethane primer and an adhesive tape using the same. Background Technology

[0002] In many situations, when using tapes or protective films to bond objects, the poor surface affinity of the substrate in these materials can easily lead to poor structural stability and delamination, thus failing to achieve the desired adhesion. While PET substrates offer good heat resistance, high transparency and strength, and are less prone to stretching, requiring less stringent tension control than other substrates, their regular macromolecular chain structure and high crystallinity result in poorer surface affinity, printability, and ink adhesion.

[0003] Common substrate surface treatment methods include corona treatment, but this method is time-sensitive, and its effectiveness diminishes to varying degrees depending on the storage environment's temperature, humidity, and duration. Primers, as a pretreatment method, increase the surface tension of the substrate, thereby improving the structural stability of the tape or protective film and reducing delamination. Furthermore, since the primer is applied between the substrate and the adhesive layer, it enhances the adhesion between them. However, most commercially available adhesives contain alcohols, esters, benzenes, and ketones, which can easily corrode the primer.

[0004] Therefore, it is necessary to prepare a primer that can improve the surface tension of the substrate and has good solvent resistance. Summary of the Invention

[0005] The purpose of this invention is to provide a one-component polyurethane primer and an adhesive tape using the same. The one-component polyurethane primer can form a primer layer with high surface tension, solvent resistance, and is not easily corroded by solvents in the adhesive layer, thereby improving the surface tension of the substrate.

[0006] According to a first aspect of the present invention, a one-component polyurethane primer is provided. The raw materials for preparing the one-component polyurethane primer include: alcohol materials, including polyester polyols, which include at least one of polyethylene glycol butylene adipate polyol (PEBA), polyethylene glycol diethylene adipate polyol (PEDA), and poly(3-methyl-1,5-pentanediol adipate) polyol (PMA); isocyanate materials, including diisocyanates and polyisocyanates, wherein the molecular structure of the diisocyanate and / or polyisocyanate includes an aromatic ring, and the mass ratio of diisocyanate to polyisocyanate is 6-12:1-5; additives, including catalysts; solvents; and the mass ratio of alcohol materials to isocyanate materials is 1-2:0.7-1.7.

[0007] The single-component polyurethane primer provided in this solution can increase the surface tension of the substrate, and the primer layer formed by this single-component polyurethane primer has high adhesion to the substrate, allowing the substrate layer and primer layer to adhere firmly. Simultaneously, the primer layer has good solvent resistance and is not easily corroded by alcohols, esters, benzenes, and ketones, giving the tapes and protective films using this single-component polyurethane primer good structural stability. This solution uses highly polar polyester polyols and isocyanate materials that meet the above requirements in the above proportions to prepare a primer with high cohesive strength, forming a primer layer with high surface tension, good adhesion, structural stability, good solvent resistance, good flexibility, and good tensile strength, which is beneficial for a firm adhesion between the substrate and the primer layer. Specifically, the diisocyanate molecule contains two isocyanate groups, and the polyisocyanate molecule contains more than two isocyanate groups. When using this one-component polyurethane primer to prepare tapes, the primer layer in the tape is not easily corroded by the adhesive, and can stably increase the surface tension of the substrate. This improves the structural stability of the tape, making it less likely to leave adhesive residue on the surface after the tape is peeled off. Especially when using PET as the substrate, this one-component polyurethane primer can significantly increase the surface tension of the PET substrate, thereby improving the adhesion between the PET substrate and the adhesive layer. In addition, the one-component polyurethane primer provided in this solution is a hydroxyl-terminated polyurethane primer, which is not easily reacted with water, avoiding the primer from foaming and swelling when exposed to water, thus further improving the storage stability of the primer and the water resistance and solvent resistance of the primer layer.

[0008] Preferably, the additives include a hydroxyl-type chain extender, which has at least two hydroxyl groups in its molecular structure; the mass ratio of hydroxyl-type chain extender to isocyanate material is 0.2-0.5:0.7-1.7. Since the above-mentioned hydroxyl-type chain extender contains at least two hydroxyl groups, it belongs to the alcohol-based hydroxyl-type chain extender category. By using the above-mentioned amount of alcohol-based hydroxyl-type chain extender to crosslink with the above-mentioned isocyanate material, the speed of complete surface drying of the primer can be increased, giving the primer rapid surface drying properties. This allows for direct drying and immediate winding and use, greatly improving production efficiency.

[0009] Preferably, the hydroxyl-type chain extender includes at least one of ethylene glycol (EG), 1,4-butanediol (BDO), diethylene glycol (DEG), and neopentyl glycol (NPG). When a hydroxyl-type chain extender is included in the reaction system, the isocyanate material first reacts with the aforementioned low-molecular-weight hydroxyl-type chain extender, and then reacts with the alcohol material to form a primer. The inventors' selection of the aforementioned highly polar, low-cost, and readily available hydroxyl-type chain extender in combination with the aforementioned material system to prepare the primer can increase the crosslinking density of the primer, which is beneficial for the formation of a primer layer with high adhesion, stable structure, and high surface tension.

[0010] Preferably, the molecular weight of the polyester polyol is 1000-2000. By selecting a polyester polyol with the above molecular weight and combining it with isocyanate materials to prepare a primer, it is easy to form a primer layer with moderate hardness, good flexibility and tensile strength, and good solvent resistance, thereby making the adhesive layer structure of the primer stable and less prone to residue.

[0011] Preferably, the diisocyanate includes at least one of toluene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI). Using the above-mentioned types of diisocyanates not only improves the cohesive strength of the primer but also facilitates the formation of a primer layer with high adhesion to the substrate, good solvent resistance, and high surface tension.

[0012] Preferably, the polyisocyanate includes at least one of toluene diisocyanate-trimethylolpropane adduct (TDI-TMP adduct) and polymethylene polyphenyl isocyanate (PAPI).

[0013] Preferably, the solvent includes N,N-dimethylformamide (DMF) and ethyl acetate, with a mass ratio of N,N-dimethylformamide:ethyl acetate of 3-5:5-7. The inventors have found that the above solvent has good compatibility with the above material system, can accommodate polyurethane with a high hard segment content, promotes the dissolution of the single-component polyurethane primer, and avoids agglomeration or clumping of the single-component polyurethane primer during storage, thereby improving the storage stability of the single-component polyurethane primer.

[0014] Preferably, the catalyst comprises an organic bismuth catalyst.

[0015] Preferably, the organic bismuth catalyst is bismuth carboxylate.

[0016] Optionally, the organic bismuth catalyst is a bismuth carboxylate catalyst manufactured by King Industries, USA, with the brand name K-KAT348.

[0017] Preferably, the preparation method of this one-component polyurethane primer includes the following operations: weighing the raw materials used to prepare the one-component polyurethane primer according to the specified amount, wherein the additives include hydroxyl-type chain extenders; prepolymerizing the alcohol and isocyanate materials at a temperature of 70-80°C to obtain a polyurethane prepolymer; adding the hydroxyl-type chain extender to the polyurethane prepolymer, maintaining the reaction temperature at 70-80°C, until the isocyanate value in the reaction system is ≤0.1%. The inventors first prepare an NCO-terminated polyurethane prepolymer through prepolymerization, and then react the polyurethane prepolymer with a hydroxyl-type chain extender to obtain a hydroxyl-terminated polyurethane. This preparation method not only increases the hard segment content of the one-component polyurethane primer, but also effectively avoids the disadvantages of water-induced foaming and poor storage stability present in NCO-terminated polyurethane. In summary, using the above-mentioned operational steps to prepare a one-component polyurethane primer easily results in a primer layer with advantages such as high surface tension, stable structure, and rapid surface drying.

[0018] According to another aspect of the present invention, a tape is provided, comprising a substrate layer, a primer layer, and an adhesive layer disposed sequentially, wherein the primer layer is made of the aforementioned single-component polyurethane primer. The tape provided by this solution has a stable structure and is less prone to leaving adhesive residue. The primer layer in the tape provides the substrate layer with an adhesion surface of higher surface tension for the adhesive layer to adhere, thus making the tape structure stable. When the adhesive layer is adhered to the surface of an object and then peeled off, the peel force between the adhesive layer and the primer layer is greater than the peel force between the adhesive layer and most of the object, thereby improving the structural stability of the tape and making it less likely to leave adhesive residue on the surface of the object.

[0019] Preferably, the substrate layer comprises polyethylene terephthalate (PET). The inventors have discovered that when polyethylene terephthalate (PET) is used as the substrate layer, the adhesion between the primer layer and the substrate layer is higher, and it can provide a higher surface tension for the PET substrate layer.

[0020] Preferably, the adhesive layer is made from at least one of the following: TP-913 pressure-sensitive adhesive produced by Nanpao Resin Co., Ltd. of Taiwan, Y-1410 produced by Anzo Chemical, and PSA-1330 pressure-sensitive adhesive produced by Guangdong Bang Curing Chemical. Detailed Implementation

[0021] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0022] Example 1

[0023] (1) Preparation of a single-component polyurethane primer

[0024] The raw materials for preparing the single-component polyurethane primer include alcohols, isocyanates, additives, and solvents. The alcohols consist of 14.8200 parts of polyester polyol, specifically poly(ethylene glycol adipate) butanediol (PEBA) with a molecular weight of 1000. The isocyanates consist of 8.980 parts of diisocyanate and 4.000 parts of polyisocyanate. The diisocyanate is diphenylmethane diisocyanate (MDI), and the polyisocyanate is toluene diisocyanate-trimethylolpropane adduct (TDI-TMP adduct) of grade L-75. The additives consist of 0.0059 parts catalyst and 2.1700 parts hydroxyl-type chain extender. The catalyst is bismuth carboxylate catalyst K-KAT348 manufactured by King Industries, USA. The hydroxyl-type chain extender includes 1.1000 parts ethylene glycol (EG) and 1.0700 parts 1,4-butanediol (BDO). The solvents include 30 parts N,N-dimethylformamide (DMF) and 45 parts ethyl acetate.

[0025] Based on the mass proportions of the above materials, the following can be calculated: the mass ratio of alcohols to isocyanates is 1.482:1.298; the mass ratio of diisocyanates to polyisocyanates is 8.980:4.000; the mass ratio of hydroxyl-type chain extenders to isocyanates is 0.217:1.298; and the mass ratio of N,N-dimethylformamide to ethyl acetate is 4:6.

[0026] This one-component polyurethane primer is prepared by the following steps:

[0027] S1. Add alcoholic materials, isocyanate materials, hydroxyl chain extender ethylene glycol, catalyst, and 15 parts of solvent DMF to a reactor and stir for 15 min. Then add diisocyanate, polyisocyanate, and 22.5 parts of solvent ethyl acetate to the reaction system, and heat the reaction system to 75°C for prepolymerization. Continue the reaction for 2.5 hours to obtain polyurethane prepolymer.

[0028] S2. Add hydroxyl-type chain extender 1,4-butanediol and 22.5 parts of solvent ethyl acetate to the polyurethane prepolymer in multiple portions, maintain the temperature of the reaction system at 70-80℃, and continue the reaction for 2.5 hours.

[0029] S3. When the isocyanate value in the reaction system is ≤0.1%, there is no NCO residue in the reaction system. Add the remaining 15 parts of solvent DMF to the reaction system, stir for 15 minutes, cool down and collect the material to obtain a single-component polyurethane primer.

[0030] The prepared single-component polyurethane primer was tested and found to contain 50.59% hard segments and 30% solids. Based on actual production needs, the viscosity of this single-component polyurethane primer at 25°C can be in the range of 100–300 mPa·s. In other embodiments, the reaction time, theoretical NCO value, and amount of material added in stages S1, S2, and S3 can be adjusted according to production requirements, provided that the total amount of raw materials and the normal preparation of the primer are not affected.

[0031] (2) Preparation of adhesive tape

[0032] The tape comprises a substrate layer, a primer layer, an adhesive layer, and a release film, which are sequentially laminated. The primer layer is made from the single-component polyurethane primer provided in (1) above. The substrate layer is a polyethylene terephthalate (PET) film with a thickness of 50 μm, the adhesive layer is a high-viscosity acrylic pressure-sensitive adhesive of brand name TP-913 produced by Nanpao Resin Co., Ltd. of Taiwan, and the release film has a thickness of 25 μm.

[0033] This tape is prepared by the following steps:

[0034] First, the above-mentioned single-component polyurethane primer is diluted with ethyl acetate to a concentration of 25%. Then, the diluted single-component polyurethane primer is applied to the substrate layer with a coating thickness of 0.5-1 g / m². Next, the substrate layer is transferred to an environment of 120°C and dried for 20-30 seconds to form a primer layer on one side of the substrate layer, thus forming an adhesive intermediate.

[0035] A high-viscosity acrylic pressure-sensitive adhesive is applied to the side of the primer layer facing away from the substrate layer, with a coating thickness of 20±1μm. This coating is then transferred to a 120°C environment and dried for 20–30 seconds to form an adhesive layer. A release film is then laminated onto the side of the adhesive layer facing away from the primer layer to obtain an adhesive tape. The tape is then cured at 50°C for 24 hours.

[0036] Example 2

[0037] (1) Preparation of a single-component polyurethane primer

[0038] The raw materials for preparing the single-component polyurethane primer include alcohols, isocyanates, additives, and solvents. The alcohols consist of 16.4200 parts of polyester polyol, specifically polyethylene adipate diethylene glycol polyol (PEDA) with a molecular weight of 2000. The isocyanates consist of 7.5700 parts of diisocyanate and 1.6600 parts of polyisocyanate, specifically toluene diisocyanate (TDI) and polymethylene polyphenyl isocyanate (PAPI). The additives include 0.0049 parts of catalyst and 4.3300 parts of hydroxyl-type chain extender. The catalyst is bismuth carboxylate catalyst K-KAT348 manufactured by King Industries, USA. The hydroxyl-type chain extender includes 1.4800 parts of 1,4-butanediol (BDO) and 2.8500 parts of neopentyl glycol (NPG). The solvents consist of 24.5 parts N,N-dimethylformamide (DMF) and 45.5 parts ethyl acetate.

[0039] Based on the mass proportions of the above materials, the following mass ratios can be calculated: Alcohol to isocyanate: 1.642:0.923; Diisocyanate to polyisocyanate: 8.980:4.000; Hydroxyl chain extender to isocyanate: 0.433:0.923; N,N-Dimethylformamide to ethyl acetate: 3.5:6.5.

[0040] The preparation steps of this single-component polyurethane primer are the same as those in Example 1, except that the hydroxyl-type chain extender BDO is added in S1 and the hydroxyl-type chain extender NPG is added in S2.

[0041] The prepared single-component polyurethane primer was tested and found to contain 45.25% hard segments and 30% solids. Based on actual production needs, the viscosity of this single-component polyurethane primer at 25°C can be in the range of 100–300 mPa·s. In other embodiments, the reaction time, theoretical NCO value, and amount of material added in stages S1, S2, and S3 can be adjusted according to production requirements, provided that the total amount of raw materials and the normal preparation of the primer are not affected.

[0042] (2) Preparation of adhesive tape

[0043] The steps and raw material composition are strictly consistent with those in Example 1.

[0044] Example 3

[0045] (1) Preparation of a single-component polyurethane primer

[0046] The raw materials for preparing the single-component polyurethane primer include alcohols, isocyanates, additives, and solvents. The alcohols consist of 13.0800 parts of polyester polyol, specifically 7.8500 parts of poly(3-methyl-1,5-pentanediol adipate) polyol (PMA) and 5.2300 parts of poly(ethylene glycol butanediol adipate) polyol (PEBA). PMA has a molecular weight of 2000, and PEBA has a molecular weight of 1000. The isocyanates consist of 11.49 parts of diisocyanate and 1.7500 parts of polyisocyanate. The diisocyanate used is diphenylmethane diisocyanate (MDI), and the polyisocyanate used is polymethylene polyphenyl isocyanate (PAPI). The additives include 0.00523 parts catalyst and 3.6600 parts hydroxyl-type chain extender. The catalyst is a bismuth carboxylate catalyst, K-KAT348, manufactured by King Industries, USA. The hydroxyl-type chain extender includes 1.3000 parts ethylene glycol (EG) and 2.3600 parts 1,4-butanediol (BDO). The solvents include 24.5 parts N,N-dimethylformamide (DMF) and 45.5 parts ethyl acetate.

[0047] Based on the mass proportions of the above materials, the following can be calculated: the mass ratio of alcohols to isocyanates is 1.308:1.497; the mass ratio of diisocyanates to polyisocyanates is 11.4900:1.7500; the mass ratio of hydroxyl-type chain extenders to isocyanates is 0.366:1.497; and the mass ratio of N,N-dimethylformamide to ethyl acetate is 4.5:5.5.

[0048] The preparation steps of this single-component polyurethane primer are strictly consistent with those in Example 1.

[0049] The prepared single-component polyurethane primer was tested and found to contain 56.38% hard segments and 30% solids. Based on actual production needs, the viscosity of this single-component polyurethane primer at 25°C can be in the range of 100–300 mPa·s. In other embodiments, the reaction time, theoretical NCO value, and the amount of material added in stages S1, S2, and S3 can be adjusted according to production requirements, provided that the total amount of raw materials and the normal preparation of the primer are not affected.

[0050] (2) Preparation of adhesive tape

[0051] The steps and raw material composition are strictly consistent with those in Example 1.

[0052] Example 4

[0053] This embodiment refers to the preparation method provided in Example 1 to prepare an adhesive tape. The difference between this embodiment and Example 1 is that, in the process of preparing the single-component polyurethane primer, while keeping the amount of isocyanate materials unchanged, the mass ratio of diisocyanate to polyisocyanate is 10:1. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0054] Example 5

[0055] This embodiment refers to the preparation method provided in Example 1 to prepare an adhesive tape. The difference between this embodiment and Example 1 is that in the process of preparing the single-component polyurethane primer, the amount of isocyanate material is adjusted so that the mass ratio of alcohol material to isocyanate material is 1.5:1. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0056] Example 6

[0057] This embodiment refers to the preparation method provided in Example 1 to prepare an adhesive tape. The difference between this embodiment and Example 1 is that, in the process of preparing the single-component polyurethane primer, an equal mass of polyester polyol with a molecular weight of 1500 is used instead of the polyester polyol in Example 1. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0058] Example 7

[0059] This embodiment refers to the preparation method provided in Example 1 to prepare an adhesive tape. The difference between this embodiment and Example 1 is that in the preparation of the single-component polyurethane primer, the following steps replace the stepwise preparation operations of S1 and S2: the alcohol materials, isocyanate materials, all additives, and part of the solvent are stirred evenly, and the reaction system is heated to 75°C and stirred continuously for 5 hours. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0060] Comparative Example 1

[0061] This comparative example uses the preparation method provided in Example 1 to prepare an adhesive tape. The difference between this comparative example and Example 1 is that, in the preparation of the single-component polyurethane primer, an equal mass of diisocyanate is used instead of the polyisocyanate in Example 1. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0062] Comparative Example 2

[0063] This comparative example uses the preparation method provided in Example 1 to prepare an adhesive tape. The difference between this comparative example and Example 1 is that, in the preparation of the single-component polyurethane primer, an equal mass of HDI biuret is used instead of the polyisocyanate in Example 1, and an equal mass of isophorone diisocyanate is used instead of the diisocyanate in Example 1. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0064] Comparative Example 3

[0065] This comparative example uses the preparation method provided in Example 1 to prepare an adhesive tape. The difference between this comparative example and Example 1 is that the amount of isocyanate material added is adjusted during the preparation of the single-component polyurethane primer so that the mass ratio of alcohol material to isocyanate material is 1:2. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0066] Comparative Example 4

[0067] This comparative example uses the preparation method provided in Example 1 to prepare an adhesive tape. The difference between this comparative example and Example 1 is that the amount of isocyanate material added is adjusted during the preparation of the single-component polyurethane primer so that the mass ratio of alcohol material to isocyanate material is 2:0.5. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0068] Comparative Example 5

[0069] This comparative example uses the preparation method provided in Example 1 to prepare an adhesive tape. The difference between this comparative example and Example 1 is that the application of the single-component polyurethane primer is omitted during the tape preparation process, and a high-viscosity acrylic pressure-sensitive adhesive is directly applied to the substrate layer. The remaining raw material ratios and preparation methods are strictly consistent with those in Example 1.

[0070] Test Example 1

[0071] 1. Performance testing of single-component polyurethane primer

[0072] Test subjects: Adhesive intermediates provided in Examples 1-7 and Comparative Examples 1-5. The adhesive intermediates comprise a substrate layer and a primer layer laminated sequentially. The primer layer is prepared from the single-component polyurethane primers provided in Examples 1-7 and the primers provided in Comparative Examples 1-5, respectively.

[0073] Test items and test methods:

[0074] (1) Surface drying test: Cut the test object into 50mm*50mm pieces and place them on a horizontal table. Use a 25mm*50mm*50um PET film to bond the test object. If the PET film can bond with the test object, it means that the coating has no surface drying, so the next test is not performed.

[0075] (2) Corona value test: First, clean the surface of the test object and lay it flat on a horizontal table. Use a corona pen to lightly draw a line on the surface of the primer layer of the test object. If the liquid does not shrink within three seconds, the dyne value selected by the corona pen has been reached; otherwise, it has not been reached. In this test, the substrate layer was set as a blank control group, and the surface dyne value of the blank control group was recorded.

[0076] (3) Back Adhesion Test: The test object was cut into 100mm*100mm pieces and laminated with a 50um PET film. The test object was then pressed down with a 1kg weight and placed in a 40℃ oven for 24 hours. After cooling to room temperature, the peel force between the primer layer and the original film was tested. If the peel force was 0, the next test was performed. If a peel force was found, it indicated that the primer had poor temperature resistance and would stick to the back in the actual roll sample, thus having no practical application value and making the next test unnecessary.

[0077] (4) Adhesion test: According to GB / T9286-1998, a coating is applied to a 50um PET film, and the coating thickness is controlled at 3-5um. 100 small squares are scraped out with a 1mm spacing cross-cutting tool. M600 or 610 tape is used to stick the tape into the cross-cutting. The 3M tape is quickly pulled up and the number of peelings is tested. If the number of peelings is ≤5% (i.e., 4B grade or above), it is considered qualified and proceeds to the next test.

[0078] 2. Performance testing of the tape

[0079] Test subjects: the tapes provided in Examples 1-7 and Comparative Examples 1-5.

[0080] Test items and test methods:

[0081] (1) 180° peel strength test: According to the test method in GB / T 2792-2014 Test method for peel strength of adhesive tape, the test object was cut into a size of 24mm*150mm, and the test object was laid on the glass. It was rolled back and forth three times with a 1kg rubber roller and left at room temperature for 20min. Then, the test object was peeled off the glass at a peel speed of 300mm / min to perform the peel strength test, and whether there was any adhesive residue on the glass was recorded.

[0082] Test results: The test results are shown in Table 1.

[0083] Table 1. Performance test results of single-component polyurethane primer and tape.

[0084]

[0085] Results analysis:

[0086] Comparing the test indicators of Examples 1-7 with those of Comparative Examples 1-5 in Table 1, it can be found that the single-component polyurethane primers provided in Examples 1-7 can all improve the corona value of the substrate layer, and exhibit structural stability, good storage stability, and excellent solvent resistance. However, in actual production testing, the single-component polyurethane primers provided in Comparative Examples 1-3 showed significant poor storage stability. This is because the reaction R value in Comparative Examples 1-3 was too large, resulting in poor regularity of the polyurethane reaction and a hard, brittle film. Therefore, although the primers provided in Comparative Examples 1-3 can improve the surface corona value of the substrate layer in a short time, their poor structural stability prevents them from providing a high corona value over a long period.

[0087] Comparing the performance of Examples 1-7 in Table 1 with that of Comparative Example 4, it can be found that the primer in Comparative Example 4 is more difficult to surface dry. This is because the reaction R value in Comparative Example 4 is too small, which is equivalent to an excess of -OH, making it difficult to surface dry.

[0088] Comparing the performance of Examples 1-7 with Comparative Example 5, it can be found that the pretreatment method using a single-component polyurethane primer in Examples 1-7 not only improved the surface tension of the substrate layer but also enhanced the structural stability of the tape. This demonstrates that the single-component polyurethane primer, while increasing the surface tension of the substrate layer, also exhibits good solvent resistance and structural stability.

[0089] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A one-component polyurethane primer, characterized in that, The raw materials for preparing the single-component polyurethane primer include: Alcohol materials, including polyester polyols, which include at least one of polyethylene glycol butylene adipate polyol, polyethylene glycol diethylene adipate polyol, and poly(3-methyl-1,5-pentanediol adipate). Isocyanate materials, wherein the isocyanate materials include diisocyanate and polyisocyanate, wherein the molecular structure of the diisocyanate and / or the polyisocyanate includes an aromatic ring, and the mass ratio of the diisocyanate to the polyisocyanate is 6~12:1~5; The additives include a catalyst and a hydroxyl-type chain extender, wherein the molecular structure of the hydroxyl-type chain extender contains at least two hydroxyl groups; and the mass ratio of the hydroxyl-type chain extender to the isocyanate material is 0.2~0.5:0.7~1.

7. Solvent; Furthermore, based on the mass ratio, the ratio of the alcohol to the isocyanate is 1~2:0.7~1.7; The isocyanate value of the single-component polyurethane primer is ≤0.1%.

2. The single-component polyurethane primer as described in claim 1, characterized in that, Hydroxyl chain extenders include at least one of ethylene glycol, 1,4-butanediol, diethylene glycol, and neopentyl glycol.

3. The single-component polyurethane primer as described in claim 1, characterized in that, The molecular weight of the polyester polyol is 1000~2000.

4. The single-component polyurethane primer as described in claim 1, characterized in that, The diisocyanate includes at least one of toluene diisocyanate and diphenylmethane diisocyanate.

5. The single-component polyurethane primer as described in claim 4, characterized in that, The polyisocyanate includes at least one of toluene diisocyanate-trimethylolpropane adduct and polymethylene polyphenyl isocyanate.

6. The single-component polyurethane primer as described in claim 1, characterized in that, The solvent includes N,N-dimethylformamide and ethyl acetate, and the mass ratio of N,N-dimethylformamide to ethyl acetate is 3~5:5~7.

7. A single-component polyurethane primer as described in any one of claims 1 to 6, characterized in that, Its preparation method Includes the following operations: Weigh out the raw materials used to prepare the single-component polyurethane primer according to the specified amount, wherein the additives include hydroxyl-type chain extenders; The alcohol and isocyanate materials are prepolymerized at a temperature of 70-80°C to obtain a polyurethane prepolymer. The hydroxyl-type chain extender is added to the polyurethane prepolymer, and the reaction temperature is maintained at 70~80℃ until the isocyanate value in the reaction system is ≤0.1%.

8. A type of adhesive tape, characterized in that, The tape comprises a substrate layer, a primer layer, and an adhesive layer arranged sequentially, wherein the primer layer is made of a single-component polyurethane primer as described in any one of claims 1 to 6.

9. The tape as described in claim 8, characterized in that, The substrate layer comprises polyethylene terephthalate.

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