Label adhesive tape without residual adhesive as well as preparation method and application of label adhesive tape

Abstract

The invention provides a label adhesive tape without adhesive residues and a preparation method and application thereof, and belongs to the technical field of adhesive tapes, the preparation method comprises the following steps: uniformly mixing a waterborne polyurethane emulsion, functionalized polyurethane, a curing agent, a wetting dispersant, a thickening agent and a defoaming agent to obtain a polyurethane label adhesive; coating a polyurethane label adhesive on the base material layer, and curing to form a label adhesive layer; and compounding the protective layer on the label adhesive layer to obtain the label. Wherein the waterborne polyurethane emulsion is prepared by carrying out a reaction on polycarbonate ether polyol, 1, 5-naphthalene diisocyanate, tris (hydroxymethyl) aminomethane, glycerol, stannous octoate, triethylamine and water; the functionalized polyurethane is prepared by reacting sulfydryl grafted graphene, epoxy grafted polyurethane and triethylamine. The label adhesive tape prepared by the invention has good holding power, heat resistance and water resistance, and no adhesive residue exists.

Description

Technical Field

[0001] The invention belongs to the technical field of adhesive tapes, and in particular relates to a label adhesive tape without adhesive residue, and a preparation method and application thereof. Background Art

[0002] Label tape is a convenient identification tool widely used in logistics, warehousing, retail and office fields. It usually consists of three parts: substrate adhesive and release paper. Among them, the substrate can be a variety of materials such as plastic, paper, cloth, etc., and materials with different characteristics are selected according to different application scenarios. The adhesive gives the label tape the ability to adhere to various surfaces, ensuring that the label can be firmly attached to the product packaging or documents and is not easy to fall off. The role of the release paper is to protect the adhesive surface before use to prevent it from sticking in advance. When it is needed, just gently peel off the release paper to easily stick the label to the designated position. Label tape is not only convenient and fast, but also can be customized into different color patterns and text content according to needs to meet diverse identification needs. With the development of science and technology, some special function label tapes have also emerged, such as waterproof and tear-proof, and even with RFID chips to achieve intelligent management. These characteristics make label tapes play an irreplaceable and important role in improving work efficiency, ensuring the safety of goods and optimizing management processes.

[0003] Although label tape provides great convenience in practical applications, it also exposes some shortcomings under certain application conditions, such as easy glue residue, especially when removing labels. If the adhesive quality is poor or the use environment is not suitable for residual glue, it will not only be difficult to clean, but also damage the beauty and texture of the surface of the object being attached. This is particularly obvious in high-end product packaging or occasions where labels need to be replaced frequently. Poor heat resistance is also a common defect of label tape. When exposed to high temperature environments, such as near heating equipment or stored in direct sunlight in summer, the label may deform, fade or even fall off, which directly affects the readability and durability of the label information. Poor water resistance also restricts the application scope of label tape. Once exposed to moisture, whether it is humid air or direct water immersion, the edge of the label may begin to warp, leading to overall shedding. This problem is more common, especially for labels used in high humidity environments such as kitchens, bathrooms, and outdoors.

[0004] In view of the above problems, some solutions have also been reported in the prior art. For example, in order to reduce the problem of residual glue, various types of pressure-sensitive adhesives have been developed, including acrylic resins and rubber bases, etc. These adhesives can reduce or avoid residues when removed while ensuring sufficient initial adhesion. However, on some special material surfaces or after long-term attachment, residual glue that is difficult to completely remove may still occur. For the disadvantage of poor heat resistance, high-temperature resistant surface materials such as PET, PP, PE, etc. can be used, and highly heat-resistant adhesives can be used. However, when the temperature exceeds a certain range, especially when it is close to or exceeds 100°C, some label tapes may still show signs of weakened viscosity or material aging. In order to improve water resistance, highly waterproof surface materials and adhesives with excellent hydrolysis resistance can be selected to improve the durability of the product. However, the composition of these materials is relatively high, which makes its application limited to specific industries or high-end products and cannot be promoted. Therefore, there is an urgent need for a label tape that has the advantages of no residual glue, strong adhesion, heat resistance, and good water resistance. Summary of the invention

[0005] The object of the present invention is to provide a label tape without residual glue and a preparation method thereof, wherein the label tape is composed of a substrate layer, a label glue layer and a protective layer, wherein the label glue layer adopts a self-made polyurethane label glue, and by adding a specific aqueous polyurethane emulsion and functionalized polyurethane into the formula, the label tape has excellent holding force, heat resistance and water resistance, and there is no residual glue. The label tape of the present invention can be widely used for identification and marking of articles.

[0006] In order to achieve the above object, the present invention provides the following technical solutions: The present invention provides a method for preparing a label tape without residual adhesive, comprising the following steps: Step 1: Evenly mix 90-100 parts by weight of aqueous polyurethane emulsion, 6-10 parts by weight of functionalized polyurethane, 2-4 parts by weight of curing agent, 1-2 parts by weight of wetting and dispersing agent, 0.1-0.3 parts by weight of thickener, and 0.2-0.4 parts by weight of defoaming agent to obtain polyurethane label adhesive; Step 2: Apply polyurethane label adhesive on the substrate layer and cure it at 70-75° C. for 2-4 minutes to form a label adhesive layer; and compound the protective layer onto the label adhesive layer to obtain the label tape without residual adhesive.

[0007] The present invention uses a specific water-based polyurethane emulsion as the main raw material of the polyurethane label adhesive, thereby improving the bonding ability and heat and water resistance of the label tape to a limited extent. Traditional water-based polyurethane mainly uses polyether diols (such as polytetramethylene glycol) as soft segments, but these polyether diols have weak cohesive force, resulting in the final prepared water-based polyurethane having low cohesive energy and mechanical strength. In contrast, the polycarbonate ether polyol prepared by the present invention contains both carbonate groups and ether groups in its molecular structure. The carbonate groups have high polarity and rigidity, and can enhance the interaction force between molecular chains, thereby improving the cohesive energy of the material. This high cohesive energy enables the aqueous polyurethane emulsion to form a tighter cross-linked network after curing, significantly improving the initial adhesion, lasting adhesion and peel strength of the tape; the introduction of carbonate groups increases the glass transition temperature of the material and enhances the stability of the polyurethane under high temperature conditions; compared with traditional polyether polyols, the polycarbonate ether polyol of the present invention can maintain good mechanical properties at higher temperatures, avoiding the softening or degradation problems caused by high temperature; the carbonate groups are less sensitive to water and are not prone to hydrolysis reactions, so the aqueous polyurethane prepared from the polycarbonate ether polyol has better water resistance, and the performance of the material will not be significantly reduced in a humid environment, ensuring the stability and reliability of the label tape in long-term use. In addition, the present invention also adds tris(hydroxymethyl)aminomethane as a chain extender. As a multifunctional compound, the polyhydroxyl groups it contains can react with isocyanate groups to extend the polyurethane molecular chain and increase the molecular weight, which not only improves the cohesion of the material, but also enhances the mechanical strength and durability of the tape. Since it has multiple reactive functional groups, it can promote the formation of more cross-linking points, further improving the cross-linking density and three-dimensional network structure of the material.

[0008] Preferably, the method for preparing the aqueous polyurethane emulsion comprises the following steps: Mixing 5-8 parts by weight of polyether polyol and 0.002-0.004 parts by weight of DMC bimetallic catalyst, adding 45-60 parts by weight of propylene oxide and 8-12 parts by weight of 1,2-butylene oxide to react after heating, distilling under reduced pressure, and cooling to obtain modified polyether polyol; Mix 6-8 parts by weight of modified polyether polyol and 0.04-0.06 parts by weight of stannous octoate, add 65-75 parts by weight of propylene carbonate and 25-35 parts by weight of N,N-dimethylformamide, introduce CO2 gas, heat the reaction, and perform reduced pressure distillation to obtain polycarbonate ether polyol; 80-90 parts by weight of polycarbonate ether polyol, 20-30 parts by weight of 1,5-naphthalene diisocyanate and 10-30 parts by weight of acetone are mixed, heated for reaction, and after cooling, 5-7 parts by weight of tris(hydroxymethyl)aminomethane, 3-5 parts by weight of propylene glycol, 0.1-0.2 parts by weight of stannous octoate and 30-45 parts by weight of acetone are added for reaction, cooled, and then 1-3 parts by weight of triethylamine and 150-160 parts by weight of water are added for emulsification, and vacuum distillation is performed to obtain an aqueous polyurethane emulsion.

[0009] Furthermore, the preparation method of the aqueous polyurethane emulsion comprises the following steps: In anhydrous nitrogen atmosphere, 5-8 parts by weight of polyether polyol and 0.002-0.004 parts by weight of DMC bimetallic catalyst are mixed, heated to 120-130° C., 45-60 parts by weight of propylene oxide and 8-12 parts by weight of 1,2-butylene oxide are added to react for 1-2 hours, unreacted substances are removed by distillation under reduced pressure, and cooled to room temperature to obtain modified polyether polyol; In anhydrous nitrogen atmosphere, 6-8 parts by weight of modified polyether polyol and 0.04-0.06 parts by weight of stannous octoate are mixed, the vacuum degree is controlled at -0.05~-0.09MPa, 65-75 parts by weight of propylene carbonate and 25-35 parts by weight of N,N-dimethylformamide are added, CO2 gas is introduced, the pressure of CO2 gas is maintained at 4-4.5MPa, the temperature is raised to 150-160°C for reaction for 10-15h, and N,N-dimethylformamide is removed by reduced pressure distillation to obtain polycarbonate ether polyol; 80-90 parts by weight of polycarbonate ether polyol, 20-30 parts by weight of 1,5-naphthalene diisocyanate and 10-30 parts by weight of acetone are mixed, reacted at 85-90° C. in a nitrogen atmosphere for 3-5 hours, cooled to 60-70° C., 5-7 parts by weight of tris(hydroxymethyl)aminomethane, 3-5 parts by weight of glycerol, 0.1-0.2 parts by weight of stannous octoate and 30-45 parts by weight of acetone are added to react for 1-3 hours, cooled to room temperature, and then 1-3 parts by weight of triethylamine and 150-160 parts by weight of water are added, emulsified at 2000-3000 rpm for 70-90 minutes, and acetone is removed by reduced pressure distillation to obtain an aqueous polyurethane emulsion.

[0010] The present invention also adds functionalized polyurethane to assist in improving the performance of the water-based polyurethane emulsion, further improving the holding force and heat resistance of the label adhesive. First, the addition of thiolated graphene brings many aspects of enhancement to the polyurethane. The thiol group in the thiolated graphene not only enhances the surface activity of the graphene, but also can undergo a ring-opening reaction with the epoxy group in the main chain of the polyurethane to form a stable thiol ether bond. This chemical bonding allows the graphene to be evenly dispersed in the polyurethane matrix, avoiding the problem of easy agglomeration of traditional fillers, thereby greatly improving the mechanical strength and heat resistance of the material. The two-dimensional sheet structure of graphene can form a physical barrier on a molecular scale, effectively preventing the penetration of water and oxygen, and further improving the water resistance and oxidation resistance of the label adhesive. Secondly, compared with traditional polyether polyols, rosin contains rich ternary phenanthrene ring structures. These structures give rosin-based polyether polyols higher rigidity and stability, and can enhance the interaction between molecular chains, thereby improving the cohesive energy and mechanical strength of polyurethane. This high cohesive energy enables water-based polyurethane to form a tighter cross-linked network after curing, significantly improving the initial adhesion, lasting adhesion and peel strength of label tapes; the ternary phenanthrene ring structure is less sensitive to water and is not prone to hydrolysis. Therefore, the water-based polyurethane prepared from rosin-based polyether polyols has better water resistance. In addition, the aromatic structure in rosin can further enhance the hydrophobicity of the material, reduce water penetration, and extend the service life of the material.

[0011] Preferably, the method for preparing the functionalized polyurethane comprises the following steps: 1-4 parts by weight of graphene oxide is mixed with 75-90 parts by weight of ethanol aqueous solution, and then 0.1-0.3 parts by weight of γ-mercaptopropyltriethoxysilane is added, and the mixture is heated and stirred, cooled, filtered, and dried to obtain mercaptolated graphene; Mixing 35-50 parts by weight of rosin and 50-65 parts by weight of poly(propylene glycol) diglycidyl ether, adding 1-2 parts by weight of a catalyst to react after heating, wherein the catalyst is composed of N-methylmorpholine and triethylamine in a weight ratio of 1:1-2, and distilling under reduced pressure to obtain a rosin-based polyether polyol; 40-50 parts by weight of rosin-based polyether polyol, 10-15 parts by weight of isophorone diisocyanate, 2-4 parts by weight of tris(hydroxymethyl)aminomethane and 8-12 parts by weight of acetone are mixed, 0.1-0.2 parts by weight of stannous octoate are added after heating for reaction, 0.6-0.8 parts by weight of 2-methylglycidol is added for further reaction, 1-2 parts by weight of ethanolamine and 15-30 parts by weight of water are reacted, and reduced pressure distillation is performed to obtain epoxy grafted polyurethane; 0.6-1 parts by weight of thiol grafted graphene, 5-5.5 parts by weight of epoxy grafted polyurethane and 0.08-0.1 parts by weight of triethylamine are mixed, heated for reaction, and cooled to obtain functionalized polyurethane.

[0012] Furthermore, the preparation method of the functionalized polyurethane comprises the following steps: 1-4 parts by weight of graphene oxide and 75-90 parts by weight of 85-90 wt% ethanol aqueous solution are mixed, ultrasonicated at a frequency of 20-30 kHz and a power of 100-250 W for 20-30 min, then 0.1-0.3 parts by weight of γ-mercaptopropyltriethoxysilane are added, stirred at 80-85° C. and 100-300 rpm for 10-15 h, cooled to room temperature, filtered, and dried to obtain thiolated graphene; Mix 35-50 parts by weight of rosin and 50-65 parts by weight of poly(propylene glycol) diglycidyl ether, add 1-2 parts by weight of a catalyst at 135-140° C. and in a nitrogen atmosphere, and react for 3-5 hours, wherein the catalyst is composed of N-methylmorpholine and triethylamine in a weight ratio of 1:1-2, and remove the catalyst and water by distillation under reduced pressure to obtain a rosin-based polyether polyol; 40-50 parts by weight of rosin-based polyether polyol, 10-15 parts by weight of isophorone diisocyanate, 2-4 parts by weight of tris(hydroxymethyl)aminomethane and 8-12 parts by weight of acetone are mixed, heated to 75-80°C, 0.1-0.2 parts by weight of stannous octoate are added to react for 3-5 hours, then 0.6-0.8 parts by weight of 2-methylglycidol are added to continue the reaction for 2-3 hours, 1-2 parts by weight of ethanolamine and 15-30 parts by weight of water are reacted for 0.5-1 hour, and acetone is removed by reduced pressure distillation to obtain epoxy grafted polyurethane; 0.6-1 parts by weight of thiol grafted graphene, 5-5.5 parts by weight of epoxy grafted polyurethane and 0.08-0.1 parts by weight of triethylamine are mixed, reacted at 60-70°C in a nitrogen atmosphere for 2-4 hours, and cooled to room temperature to obtain functionalized polyurethane.

[0013] Preferably, the curing agent is a water-based isocyanate curing agent; the water-based isocyanate curing agent is any one of curing agent Bayhydur 3100, curing agent Bayhydur 304, and curing agent Bayhydu 305. Brand: Bayer.

[0014] Preferably, the wetting and dispersing agent is any one of Tween 80, Tween 60 and Tween 40.

[0015] Preferably, the thickener is a nonionic associative polyurethane thickener; the nonionic associative polyurethane thickener is any one of RM-12W thickener, RM-8W thickener, and RM-2050D thickener. Brand: Rohm and Haas.

[0016] Preferably, the defoamer is a mineral oil defoamer; the mineral oil defoamer is any one of defoamer Foamaster Mo2190, defoamer Foamaster Mo2160 and defoamer Foamaster Mo2111. Brand: BASF.

[0017] Preferably, the thickness of the substrate layer is 40-50 μm.

[0018] Preferably, the thickness of the label adhesive layer is 10-20 μm.

[0019] Preferably, the thickness of the protective layer is 45-60 μm.

[0020] Preferably, the substrate layer is any one of a PET film, a BOPP film, a PVC film and a PP film.

[0021] Preferably, the protective layer is any one of glassine release paper, kraft release paper, PEK release paper and CCK release paper.

[0022] The present invention also provides an application of the label tape without residual glue prepared by the above method in object identification and marking, including but not limited to daily necessities marking, household marking, wire and cable marking, circuit board marking, equipment maintenance marking, etc.

[0023] Compared with the prior art, the advantages and beneficial effects of the present invention are: 1. The present invention provides a label tape without residual glue, and a preparation method and application thereof. The label tape improves the component formula of the label adhesive layer, adds an aqueous polyurethane emulsion prepared by reacting polycarbonate ether polyol, 1,5-naphthalene diisocyanate, tris(hydroxymethyl)aminomethane, propylene glycol, stannous octoate, triethylamine, and water, and adds a functionalized polyurethane prepared by reacting thiol-grafted graphene, epoxy-grafted polyurethane and triethylamine, thereby further improving the adhesive force, heat resistance and water resistance of the label tape, and no residual glue is present.

[0024] 2. The present invention uses a specific aqueous polyurethane emulsion as the main raw material of the polyurethane label adhesive, thereby improving the bonding ability and heat and water resistance of the label tape to a limited extent; compared with traditional polyether polyols, the present invention uses polycarbonate ether polyols to prepare aqueous polyurethane emulsions, which can maintain good mechanical properties at higher temperatures and avoid softening or degradation problems caused by high temperatures; the carbonate group is less sensitive to water and is not prone to hydrolysis reactions, so the aqueous polyurethane prepared from polycarbonate ether polyols has better water resistance, and the performance of the material will not be significantly reduced in a humid environment, ensuring the stability and reliability of the label tape in long-term use.

[0025] 3. The present invention also adds functionalized polyurethane to assist in improving the performance of the water-based polyurethane emulsion. The introduction of thiolated graphene in the functionalized polyurethane brings about multiple enhancement effects for the polyurethane. The thiol group in the thiolated graphene not only enhances the surface activity of the graphene, but also can undergo a ring-opening reaction with the epoxy group in the main chain of the polyurethane to form a stable thiol ether bond. This chemical bonding allows the graphene to be evenly dispersed in the polyurethane matrix, avoiding the problem of easy agglomeration of traditional fillers, thereby greatly improving the mechanical strength and heat resistance of the material. The two-dimensional sheet structure of graphene can form a physical barrier at the molecular scale, effectively preventing the penetration of water and oxygen, and further improving the water resistance and oxidation resistance of the label adhesive. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Example 1 This embodiment provides a method for preparing a label tape without residual adhesive, comprising the following steps: Step 1: 92 parts by weight of aqueous polyurethane emulsion, 8 parts by weight of functionalized polyurethane, 3 parts by weight of curing agent, 1.5 parts by weight of wetting and dispersing agent, 0.2 parts by weight of thickener, and 0.3 parts by weight of defoamer are uniformly mixed to obtain polyurethane label adhesive; the curing agent is an aqueous isocyanate curing agent, specifically using curing agent Bayhydur3100, brand: Bayer; the wetting and dispersing agent is Tween 80; the thickener is a non-ionic associative polyurethane thickener, specifically using RM-12W thickener, brand: Rohm and Haas; the defoamer is a mineral oil defoamer, specifically using defoamer Foamaster Mo2190, brand: BASF; Step 2: Apply polyurethane label adhesive on the substrate layer and cure at 72°C for 3 minutes to form a label adhesive layer; compound the protective layer on the label adhesive layer to obtain the label tape without residual adhesive. The substrate layer is a PET film with a thickness of 45 μm; the label adhesive layer has a thickness of 15 μm; and the protective layer is a glassine release paper with a thickness of 50 μm.

[0028] The preparation method of the aqueous polyurethane emulsion comprises the following steps: In anhydrous nitrogen atmosphere, 6 parts by weight of polyether polyol and 0.003 parts by weight of DMC bimetallic catalyst were mixed, heated to 125°C, 50 parts by weight of propylene oxide and 10 parts by weight of 1,2-butylene oxide were added to react for 1.5 hours, unreacted substances were removed by reduced pressure distillation, and the mixture was cooled to room temperature to obtain a modified polyether polyol; wherein the polyether polyol was purchased from Jurong Ningwu New Materials Co., Ltd., item number: NJ-310, with a viscosity (25°C) of 190-270 mPa•s and a hydroxyl value of 168±10 mgKOH / g; the DMC bimetallic catalyst was purchased from Shanghai Qike Fluorosilicon Materials Co., Ltd., item number DMC-001; In an anhydrous, nitrogen atmosphere, 7 parts by weight of modified polyether polyol and 0.05 parts by weight of stannous octoate were mixed, the vacuum degree was controlled at -0.05 MPa, 70 parts by weight of propylene carbonate and 30 parts by weight of N, N-dimethylformamide were added, CO2 gas was introduced, the pressure of CO2 gas was maintained at 4.2 MPa, the temperature was raised to 155°C for reaction for 12 hours, and N, N-dimethylformamide was removed by reduced pressure distillation to obtain polycarbonate ether polyol; 85 parts by weight of polycarbonate ether polyol, 25 parts by weight of 1,5-naphthalene diisocyanate and 20 parts by weight of acetone were mixed, reacted at 86°C in a nitrogen atmosphere for 3.5 hours, cooled to 65°C, 6 parts by weight of tris(hydroxymethyl)aminomethane, 4 parts by weight of propylene glycol, 0.15 parts by weight of stannous octoate and 40 parts by weight of acetone were added to react for 2.5 hours, cooled to room temperature, and then 2 parts by weight of triethylamine and 155 parts by weight of water were added, emulsified at 2500 rpm for 80 minutes, and acetone was removed by reduced pressure distillation to obtain an aqueous polyurethane emulsion.

[0029] The preparation method of the functionalized polyurethane comprises the following steps: 2.5 parts by weight of graphene oxide was mixed with 80 parts by weight of 90 wt% ethanol aqueous solution, and ultrasonicated for 25 min at a frequency of 30 kHz and a power of 250 W, and then 0.2 parts by weight of γ-mercaptopropyltriethoxysilane was added, and stirred at 83° C. and 200 rpm for 12 h, cooled to room temperature, filtered, and dried to obtain thiolated graphene; wherein the graphene oxide was purchased from Jiangsu Xianfeng Nanomaterial Technology Co., Ltd., item number: XF002-2, single layer, sheet diameter of 0.5-5 μm, thickness of 0.8-1.2 nm; 40 parts by weight of rosin and 60 parts by weight of poly(propylene glycol) diglycidyl ether are mixed, 1.5 parts by weight of a catalyst is added and reacted for 4.5 hours at 138° C. in a nitrogen atmosphere, wherein the catalyst is composed of N-methylmorpholine and triethylamine in a weight ratio of 1:1.5, and the catalyst and water are removed by reduced pressure distillation to obtain a rosin-based polyether polyol; wherein the rosin has a CAS number of 8050-09-7 and an acid value of 166 mgKOH / g; the poly(propylene glycol) diglycidyl ether has an average molecular weight of 400 and an epoxy value of 0.28-0.35 eq / 100 g; Take 45 parts by weight of rosin-based polyether polyol, 12 parts by weight of isophorone diisocyanate, 3 parts by weight of tris(hydroxymethyl)aminomethane and 10 parts by weight of acetone, heat to 78°C, add 0.1 parts by weight of stannous octoate and react for 4 hours, then add 0.7 parts by weight of 2-methylglycidol and continue to react for 2.5 hours, then 1.2 parts by weight of ethanolamine and 20 parts by weight of water are reacted for 1 hour, and acetone is removed by reduced pressure distillation to obtain epoxy grafted polyurethane; 0.8 parts by weight of thiol grafted graphene, 5.2 parts by weight of epoxy grafted polyurethane and 0.1 parts by weight of triethylamine are mixed, reacted at 65°C and nitrogen atmosphere for 2.5 hours, and cooled to room temperature to obtain functionalized polyurethane.

[0030] Example 2 This embodiment provides a label tape without residual adhesive, comprising the following raw materials in parts by weight: Step 1: 90 parts by weight of aqueous polyurethane emulsion, 6 parts by weight of functionalized polyurethane, 2 parts by weight of curing agent, 1 part by weight of wetting and dispersing agent, 0.1 parts by weight of thickener, and 0.2 parts by weight of defoamer are uniformly mixed to obtain polyurethane label glue; the curing agent is an aqueous isocyanate curing agent, specifically using curing agent Bayhydur3100, brand: Bayer; the wetting and dispersing agent is Tween 80; the thickener is a non-ionic associative polyurethane thickener, specifically using RM-12W thickener, brand: Rohm and Haas; the defoamer is a mineral oil defoamer, specifically using defoamer Foamaster Mo2190, brand: BASF; Step 2: Apply polyurethane label adhesive on the substrate layer, cure at 70°C for 4 minutes to form a label adhesive layer; compound the protective layer on the label adhesive layer to obtain the label tape without residual adhesive. The substrate layer is a PET film with a thickness of 40 μm; the label adhesive layer has a thickness of 10 μm; and the protective layer is a glassine release paper with a thickness of 45 μm.

[0031] The aqueous polyurethane emulsion is the same as that in Example 1.

[0032] The functionalized polyurethane is the same as that in Example 1.

[0033] Example 3 This embodiment provides a label tape without residual adhesive, comprising the following raw materials in parts by weight: Step 1: 100 parts by weight of aqueous polyurethane emulsion, 10 parts by weight of functionalized polyurethane, 4 parts by weight of curing agent, 2 parts by weight of wetting and dispersing agent, 0.3 parts by weight of thickener, and 0.4 parts by weight of defoamer are mixed uniformly to obtain polyurethane label glue; the curing agent is an aqueous isocyanate curing agent, specifically the curing agent Bayhydur3100, brand: Bayer; the wetting and dispersing agent is Tween 80; the thickener is a non-ionic associative polyurethane thickener, specifically the RM-12W thickener, brand: Rohm and Haas; the defoamer is a mineral oil defoamer, specifically the defoamer Foamaster Mo2190, brand: BASF; Step 2: Apply polyurethane label adhesive on the substrate layer, cure at 75°C for 2 minutes to form a label adhesive layer; compound the protective layer on the label adhesive layer to obtain the label tape without residual adhesive. The substrate layer is a PET film with a thickness of 50 μm; the label adhesive layer has a thickness of 20 μm; and the protective layer is a glassine release paper with a thickness of 60 μm.

[0034] The aqueous polyurethane emulsion is the same as that in Example 1.

[0035] The functionalized polyurethane is the same as that in Example 1.

[0036] Comparative Example 1 The difference between this comparative example and Example 1 is that the preparation method of the aqueous polyurethane emulsion is different, which is as follows: the preparation method of the aqueous polyurethane emulsion comprises the following steps: 85 parts by weight of polyether polyol, 25 parts by weight of 1,5-naphthalene diisocyanate and 20 parts by weight of acetone were mixed, reacted at 86°C in a nitrogen atmosphere for 3.5 hours, cooled to 65°C, 6 parts by weight of tris(hydroxymethyl)aminomethane, 4 parts by weight of propylene glycol, 0.15 parts by weight of stannous octoate and 40 parts by weight of acetone were added to react for 2.5 hours, cooled to room temperature, and then 2 parts by weight of triethylamine and 155 parts by weight of water were added, emulsified at 2500rpm for 80 minutes, and acetone was removed by vacuum distillation to obtain an aqueous polyurethane emulsion. Among them, polyether polyol was purchased from Jurong Ningwu New Materials Co., Ltd., item number: NJ-310, viscosity (25°C) is 190-270mPa•s, and hydroxyl value is 168±10mgKOH / g.

[0037] Comparative Example 2 The difference between this comparative example and Example 1 is that the preparation method of the aqueous polyurethane emulsion is different, which is as follows: the preparation method of the aqueous polyurethane emulsion comprises the following steps: In anhydrous nitrogen atmosphere, 6 parts by weight of polyether polyol and 0.003 parts by weight of DMC bimetallic catalyst were mixed, heated to 125°C, 50 parts by weight of propylene oxide and 10 parts by weight of 1,2-butylene oxide were added to react for 1.5 hours, unreacted substances were removed by reduced pressure distillation, and the mixture was cooled to room temperature to obtain a modified polyether polyol; wherein the polyether polyol was purchased from Jurong Ningwu New Materials Co., Ltd., item number: NJ-310, with a viscosity (25°C) of 190-270 mPa•s and a hydroxyl value of 168±10 mgKOH / g; the DMC bimetallic catalyst was purchased from Shanghai Qike Fluorosilicon Materials Co., Ltd., item number DMC-001; In an anhydrous, nitrogen atmosphere, 7 parts by weight of modified polyether polyol and 0.05 parts by weight of stannous octoate were mixed, the vacuum degree was controlled at -0.05 MPa, 70 parts by weight of propylene carbonate and 30 parts by weight of N, N-dimethylformamide were added, CO2 gas was introduced, the pressure of CO2 gas was maintained at 4.2 MPa, the temperature was raised to 155°C for reaction for 12 hours, and N, N-dimethylformamide was removed by reduced pressure distillation to obtain polycarbonate ether polyol; 85 parts by weight of polycarbonate ether polyol, 25 parts by weight of 1,5-naphthalene diisocyanate and 20 parts by weight of acetone were mixed, reacted at 86°C in a nitrogen atmosphere for 3.5 hours, cooled to 65°C, 10 parts by weight of propylene glycol, 0.15 parts by weight of stannous octoate and 40 parts by weight of acetone were added to react for 2.5 hours, cooled to room temperature, and then 2 parts by weight of triethylamine and 155 parts by weight of water were added, emulsified at 2500 rpm for 80 minutes, and acetone was removed by reduced pressure distillation to obtain an aqueous polyurethane emulsion.

[0038] Comparative Example 3 The difference between this comparative example and Example 1 is that the preparation method of the functionalized polyurethane is different, which is as follows: The preparation method of the functionalized polyurethane comprises the following steps: 40 parts by weight of rosin and 60 parts by weight of poly(propylene glycol) diglycidyl ether are mixed, 1.5 parts by weight of a catalyst is added and reacted for 4.5 hours at 138° C. in a nitrogen atmosphere, wherein the catalyst is composed of N-methylmorpholine and triethylamine in a weight ratio of 1:1.5, and the catalyst and water are removed by reduced pressure distillation to obtain a rosin-based polyether polyol; wherein the rosin has a CAS number of 8050-09-7 and an acid value of 166 mgKOH / g; the poly(propylene glycol) diglycidyl ether has an average molecular weight of 400 and an epoxy value of 0.28-0.35 eq / 100 g; Take 45 parts by weight of rosin-based polyether polyol, 12 parts by weight of isophorone diisocyanate, 3 parts by weight of tris(hydroxymethyl)aminomethane and 10 parts by weight of acetone, heat to 78°C, add 0.1 parts by weight of stannous octoate and react for 4 hours, then add 0.7 parts by weight of 2-methyl glycidol and continue to react for 2.5 hours, then 1.2 parts by weight of ethanolamine and 20 parts by weight of water react for 1 hour, remove acetone by reduced pressure distillation to obtain epoxy grafted polyurethane; 0.8 parts by weight of graphene oxide, 5.2 parts by weight of epoxy grafted polyurethane and 0.1 parts by weight of triethylamine are mixed, reacted at 65°C and nitrogen atmosphere for 2.5 hours, cooled to room temperature, and functionalized polyurethane is obtained. Among them, graphene oxide was purchased from Jiangsu Xianfeng Nanomaterial Technology Co., Ltd., item number: XF002-2, single layer, sheet diameter of 0.5-5μm, thickness of 0.8-1.2nm.

[0039] Comparative Example 4 The difference between this comparative example and Example 1 is that the preparation method of the functionalized polyurethane is different, which is as follows: The preparation method of the functionalized polyurethane comprises the following steps: 40 parts by weight of rosin and 60 parts by weight of poly(propylene glycol) diglycidyl ether are mixed, 1.5 parts by weight of a catalyst is added and reacted for 4.5 hours at 138° C. in a nitrogen atmosphere, wherein the catalyst is composed of N-methylmorpholine and triethylamine in a weight ratio of 1:1.5, and the catalyst and water are removed by reduced pressure distillation to obtain a rosin-based polyether polyol; wherein the rosin has a CAS number of 8050-09-7 and an acid value of 166 mgKOH / g; the poly(propylene glycol) diglycidyl ether has an average molecular weight of 400 and an epoxy value of 0.28-0.35 eq / 100 g; Take 45 parts by weight of rosin-based polyether polyol, 12 parts by weight of isophorone diisocyanate, 3 parts by weight of tris(hydroxymethyl)aminomethane and 10 parts by weight of acetone, heat to 78°C, add 0.1 parts by weight of stannous octoate and react for 4 hours, then add 0.7 parts by weight of 2-methylglycidol and continue to react for 2.5 hours, then 1.2 parts by weight of ethanolamine and 20 parts by weight of water are reacted for 1 hour, and the acetone is removed by distillation under reduced pressure to obtain a functionalized polyurethane.

[0040] Comparative Example 5 The difference between this comparative example and Example 1 is that the preparation method of the functionalized polyurethane is different, which is as follows: The preparation method of the functionalized polyurethane comprises the following steps: 2.5 parts by weight of graphene oxide was mixed with 80 parts by weight of 90 wt% ethanol aqueous solution, and ultrasonicated for 25 min at a frequency of 30 kHz and a power of 250 W, and then 0.2 parts by weight of γ-mercaptopropyltriethoxysilane was added, and stirred at 83° C. and 200 rpm for 12 h, cooled to room temperature, filtered, and dried to obtain thiolated graphene; wherein the graphene oxide was purchased from Jiangsu Xianfeng Nanomaterial Technology Co., Ltd., item number: XF002-2, single layer, sheet diameter of 0.5-5 μm, thickness of 0.8-1.2 nm; Take 45 parts by weight of polyether polyol, 12 parts by weight of isophorone diisocyanate, 3 parts by weight of tris(hydroxymethyl)aminomethane and 10 parts by weight of acetone, heat to 78°C, add 0.1 parts by weight of stannous octoate to react for 4 hours, then add 0.7 parts by weight of 2-methyl glycidol to continue the reaction for 2.5 hours, then 1.2 parts by weight of ethanolamine and 20 parts by weight of water to react for 1 hour, remove acetone by reduced pressure distillation to obtain epoxy grafted polyurethane; 0.8 parts by weight of thiol grafted graphene, 5.2 parts by weight of epoxy grafted polyurethane and 0.1 parts by weight of triethylamine are mixed, reacted at 65°C and nitrogen atmosphere for 2.5 hours, and cooled to room temperature to obtain functionalized polyurethane. Among them, polyether polyol was purchased from Jurong Ningwu New Materials Co., Ltd., item number: NJ-310, viscosity (25°C) is 190-270mPa•s, and hydroxyl value is 168±10mgKOH / g.

[0041] Comparative Example 6 The difference between this comparative example and Example 1 is that the preparation method of the functionalized polyurethane is different, which is as follows: The preparation method of the functionalized polyurethane comprises the following steps: 40 parts by weight of rosin and 60 parts by weight of poly(propylene glycol) diglycidyl ether are mixed, 1.5 parts by weight of a catalyst is added and reacted for 4.5 hours at 138° C. in a nitrogen atmosphere, wherein the catalyst is composed of N-methylmorpholine and triethylamine in a weight ratio of 1:1.5, and the catalyst and water are removed by reduced pressure distillation to obtain a rosin-based polyether polyol; wherein the rosin has a CAS number of 8050-09-7 and an acid value of 166 mgKOH / g; the poly(propylene glycol) diglycidyl ether has an average molecular weight of 400 and an epoxy value of 0.28-0.35 eq / 100 g; Take 45 parts by weight of rosin-based polyether polyol, 12 parts by weight of isophorone diisocyanate, 3 parts by weight of tris(hydroxymethyl)aminomethane and 10 parts by weight of acetone, heat to 78°C, add 0.1 parts by weight of stannous octoate and react for 4 hours, remove acetone by vacuum distillation to obtain polyurethane; mix 0.8 parts by weight of graphene oxide and 5.2 parts by weight of polyurethane to obtain functionalized polyurethane. Among them, graphene oxide was purchased from Jiangsu Xianfeng Nanomaterial Technology Co., Ltd., item number: XF002-2, single layer, sheet diameter of 0.5-5μm, thickness of 0.8-1.2nm.

[0042] Performance Testing 1. The label tapes corresponding to the above-mentioned examples 1-3 and comparative examples 1-6 and the commercially available label adhesive were respectively pasted on the surface of the glass bottle body, and then placed in a 60°C constant temperature box for 1 week, and then the state of the label tape was observed to evaluate the heat resistance. The label was washed with 80°C hot water to observe whether there was any residue. The results are shown in Table 1.

[0043] Table 1: Test results of heat resistance and residual adhesive

[0044] 2. According to method 1 (test method for 180° peel strength of adhesive tape and stainless steel plate) in GB 2792-2014, the peel strength of the label tape corresponding to the above examples 1-3 and comparative examples 1-6 was measured to evaluate the holding force. The polyurethane label adhesive corresponding to the above examples 1-3 and comparative examples 1-6 was coated on a glass plate with a coating thickness of 10 μm. After curing, the water contact angle was tested to evaluate the water resistance. The results are shown in Table 2.

[0045] Table 2: Peel strength and water resistance test results

[0046] It can be seen from the above performance test results that the label tapes without residual glue prepared in Examples 1-3 have good adhesion, heat resistance and water resistance, especially the comprehensive performance of the label tape without residual glue in Example 1 is the most outstanding. This is because the present invention adds specific aqueous polyurethane emulsion and functionalized polyurethane to the polyurethane label glue, which significantly improves the adhesion, heat resistance and water resistance of the label tape without residual glue.

[0047] In comparison, since Comparative Examples 1-6 did not adopt the necessary technical solutions, they were significantly worse than Examples 1-3 in the corresponding performance tests. In Comparative Examples 1-2, no specific aqueous polyurethane emulsion was used, and in Comparative Examples 3-6, no functionalized polyurethane was prepared using a specific method. It can be seen from the results that this caused the adhesive force, heat resistance and water resistance of the label tape without residual glue to decrease. The above experimental results further prove the importance of the technical solution defined in the present invention for its technical effect.

[0048] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a label tape without residual adhesive, characterized in that: The following steps are involved: Step 1, 90-100 parts by weight of aqueous polyurethane emulsion, 6-10 parts by weight of functionalized polyurethane, 2-4 parts by weight of curing agent, 1-2 parts by weight of wetting and dispersing agent, 0.1-0.3 parts by weight of thickener, and 0.2-0.4 parts by weight of defoaming agent are uniformly mixed to obtain polyurethane label adhesive; the aqueous polyurethane emulsion is prepared by reacting polycarbonate ether polyol, 1,5-naphthalene diisocyanate, tris(hydroxymethyl)aminomethane, glycerol, stannous octoate, triethylamine, and water; the functionalized polyurethane is prepared by reacting thiol-grafted graphene, epoxy-grafted polyurethane, and triethylamine; Step 2: coating the polyurethane label adhesive on the substrate layer and curing it to form a label adhesive layer; and compounding the protective layer on the label adhesive layer to obtain the label tape without residual adhesive.

2. The method for preparing a label tape without residual adhesive according to claim 1, characterized in that: The preparation method of the aqueous polyurethane emulsion comprises the following steps: Mixing 5-8 parts by weight of polyether polyol and 0.002-0.004 parts by weight of DMC bimetallic catalyst, adding 45-60 parts by weight of propylene oxide and 8-12 parts by weight of 1,2-butylene oxide to react after heating, distilling under reduced pressure, and cooling to obtain modified polyether polyol; Mix 6-8 parts by weight of modified polyether polyol and 0.04-0.06 parts by weight of stannous octoate, add 65-75 parts by weight of propylene carbonate and 25-35 parts by weight of N,N-dimethylformamide, introduce CO2 gas, heat the reaction, and perform reduced pressure distillation to obtain polycarbonate ether polyol; 80-90 parts by weight of polycarbonate ether polyol, 20-30 parts by weight of 1,5-naphthalene diisocyanate and 10-30 parts by weight of acetone are mixed, heated for reaction, and after cooling, 5-7 parts by weight of tris(hydroxymethyl)aminomethane, 3-5 parts by weight of propylene glycol, 0.1-0.2 parts by weight of stannous octoate and 30-45 parts by weight of acetone are added for reaction, cooled, and then 1-3 parts by weight of triethylamine and 150-160 parts by weight of water are added for emulsification, and vacuum distillation is performed to obtain an aqueous polyurethane emulsion.

3. The method for preparing a label tape without residual adhesive according to claim 2, characterized in that: The preparation method of the aqueous polyurethane emulsion comprises the following steps: In anhydrous nitrogen atmosphere, 5-8 parts by weight of polyether polyol and 0.002-0.004 parts by weight of DMC bimetallic catalyst are mixed, heated to 120-130° C., 45-60 parts by weight of propylene oxide and 8-12 parts by weight of 1,2-butylene oxide are added to react for 1-2 hours, unreacted substances are removed by distillation under reduced pressure, and cooled to room temperature to obtain modified polyether polyol; In anhydrous nitrogen atmosphere, 6-8 parts by weight of modified polyether polyol and 0.04-0.06 parts by weight of stannous octoate are mixed, the vacuum degree is controlled at -0.05~-0.09MPa, 65-75 parts by weight of propylene carbonate and 25-35 parts by weight of N,N-dimethylformamide are added, CO2 gas is introduced, the pressure of CO2 gas is maintained at 4-4.5MPa, the temperature is raised to 150-160°C for reaction for 10-15h, and N,N-dimethylformamide is removed by reduced pressure distillation to obtain polycarbonate ether polyol; 80-90 parts by weight of polycarbonate ether polyol, 20-30 parts by weight of 1,5-naphthalene diisocyanate and 10-30 parts by weight of acetone are mixed, reacted at 85-90° C. in a nitrogen atmosphere for 3-5 hours, cooled to 60-70° C., 5-7 parts by weight of tris(hydroxymethyl)aminomethane, 3-5 parts by weight of glycerol, 0.1-0.2 parts by weight of stannous octoate and 30-45 parts by weight of acetone are added to react for 1-3 hours, cooled to room temperature, and then 1-3 parts by weight of triethylamine and 150-160 parts by weight of water are added, emulsified at 2000-3000 rpm for 70-90 minutes, and acetone is removed by reduced pressure distillation to obtain an aqueous polyurethane emulsion.

4. The method for preparing a label tape without residual adhesive according to claim 1, characterized in that: The preparation method of the functionalized polyurethane comprises the following steps: 1-4 parts by weight of graphene oxide is mixed with 75-90 parts by weight of ethanol aqueous solution, and then 0.1-0.3 parts by weight of γ-mercaptopropyltriethoxysilane is added, and the mixture is heated and stirred, cooled, filtered, and dried to obtain mercaptolated graphene; Mixing 35-50 parts by weight of rosin and 50-65 parts by weight of poly(propylene glycol) diglycidyl ether, adding 1-2 parts by weight of a catalyst to react after heating, and performing reduced pressure distillation to obtain a rosin-based polyether polyol; 40-50 parts by weight of rosin-based polyether polyol, 10-15 parts by weight of isophorone diisocyanate, 2-4 parts by weight of tris(hydroxymethyl)aminomethane and 8-12 parts by weight of acetone are mixed, 0.1-0.2 parts by weight of stannous octoate are added after heating for reaction, 0.6-0.8 parts by weight of 2-methylglycidol is added for further reaction, 1-2 parts by weight of ethanolamine and 15-30 parts by weight of water are reacted, and reduced pressure distillation is performed to obtain epoxy grafted polyurethane; 0.6-1 parts by weight of thiol grafted graphene, 5-5.5 parts by weight of epoxy grafted polyurethane and 0.08-0.1 parts by weight of triethylamine are mixed, heated for reaction, and cooled to obtain functionalized polyurethane.

5. The method for preparing a label tape without residual adhesive according to claim 4, characterized in that: The preparation method of the functionalized polyurethane comprises the following steps: 1-4 parts by weight of graphene oxide and 75-90 parts by weight of 85-90 wt% ethanol aqueous solution are mixed, ultrasonicated at a frequency of 20-30 kHz and a power of 100-250 W for 20-30 min, then 0.1-0.3 parts by weight of γ-mercaptopropyltriethoxysilane are added, stirred at 80-85° C. and 100-300 rpm for 10-15 h, cooled to room temperature, filtered, and dried to obtain thiolated graphene; Mix 35-50 parts by weight of rosin and 50-65 parts by weight of poly(propylene glycol) diglycidyl ether, add 1-2 parts by weight of catalyst to react for 3-5 hours at 135-140° C. in a nitrogen atmosphere, and remove the catalyst and water by distillation under reduced pressure to obtain a rosin-based polyether polyol; 40-50 parts by weight of rosin-based polyether polyol, 10-15 parts by weight of isophorone diisocyanate, 2-4 parts by weight of tris(hydroxymethyl)aminomethane and 8-12 parts by weight of acetone are mixed, heated to 75-80°C, 0.1-0.2 parts by weight of stannous octoate are added to react for 3-5 hours, then 0.6-0.8 parts by weight of 2-methylglycidol are added to continue the reaction for 2-3 hours, 1-2 parts by weight of ethanolamine and 15-30 parts by weight of water are reacted for 0.5-1 hour, and acetone is removed by reduced pressure distillation to obtain epoxy grafted polyurethane; 0.6-1 parts by weight of thiol grafted graphene, 5-5.5 parts by weight of epoxy grafted polyurethane and 0.08-0.1 parts by weight of triethylamine are mixed, reacted at 60-70°C in a nitrogen atmosphere for 2-4 hours, and cooled to room temperature to obtain functionalized polyurethane.

6. The method for preparing a label tape without residual adhesive according to claim 4 or 5, characterized in that: The catalyst is composed of N-methylmorpholine and triethylamine in a weight ratio of 1:1-2.

7. The method for preparing a label tape without residual adhesive according to claim 1, characterized in that: The curing agent is a water-based isocyanate curing agent; the thickener is a non-ionic associative polyurethane thickener; the defoamer is a mineral oil defoamer; and the wetting and dispersing agent is any one of Tween 80, Tween 60 and Tween 40.

8. The method for preparing a label tape without residual adhesive according to claim 1, characterized in that: The substrate layer is any one of PET film, BOPP film, PVC film and PP film; the protective layer is any one of glassine release paper, kraft release paper, PEK release paper and CCK release paper.

9. A label tape without residual adhesive, prepared according to the method according to any one of claims 1 to 8.

10. Use of the label tape without residual adhesive according to claim 9 in marking and labeling of articles.

Images