Self-heating label adhesive, preparation method thereof and self-heating label

Abstract

The invention relates to the technical field of adhesives, in particular to a self-heating label adhesive, a preparation method thereof and a self-heating label. Comprising the following components in parts by weight: 20-30 parts of a styrene block copolymer, 10-30 parts of a plasticizer, 25-40 parts of tackifying resin, 5-10 parts of liquid resin, 10-20 parts of liquid rubber, 20-30 parts of heating microcapsules and 0.1-1 part of an antioxidant, the heating microcapsule comprises a capsule core and a capsule wall wrapping the surface of the capsule core; the capsule core comprises reduced iron powder, activated carbon, sodium chloride, a reaction accelerator and water-absorbent resin, and the capsule wall comprises poly (N-isopropylacrylamide), gelatin, glutaraldehyde and nano silicon dioxide. The adhesive disclosed by the invention is compounded with various components, so that the adhesive has good initial adhesion, peel strength and adhesion stability on an adhered material under a low-temperature condition.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of adhesive, in particular to a self-heating label adhesive, a preparation method thereof and a self-heating label. BACKGROUND

[0002] With the rapid development of the cold chain industry, the identification of goods in low-temperature environment has become a key link to ensure product quality and safety. However, the traditional label adhesive generally faces the following technical bottlenecks under low-temperature conditions: firstly, due to the glass transition temperature of the material itself, hardening easily occurs at low temperature, resulting in loss of adhesion and label falling off; secondly, in a low-temperature environment, condensation water is easily formed on the surface of the goods, and the main material of the traditional label adhesive is hydrophobic, which makes it difficult to form effective adhesion on the wet surface, so that the label cannot be firmly attached to the surface of the adherend. The existing low-temperature label adhesive has a minimum temperature of about -20℃, and as the temperature further decreases, there is a problem of loss of adhesion. Moreover, the formula of some low-temperature label adhesive relies on a variety of organic solvents, resulting in environmental problems such as the release of volatile organic compounds (VOCs) in production and products.

[0003] In view of this, the present application is proposed. SUMMARY

[0004] The purpose of the present application is to provide a self-heating label adhesive, a preparation method thereof and a self-heating label. The present application regulates the composition of the self-heating label adhesive, so that it still has good initial adhesion, peel strength and adhesion stability under low-temperature conditions below -20℃.

[0005] In order to achieve the above-mentioned purpose of the present application, the first aspect of the present application provides a self-heating label adhesive, which comprises the following components in parts by weight: styrene block copolymer 20-30 parts, plasticizer 10-30 parts, tackifying resin 25-40 parts, liquid resin 5-10 parts, liquid rubber 10-20 parts, heating microcapsule 20-30 parts and antioxidant 0.1-1 part; The heating microcapsule comprises a capsule core and a capsule wall wrapped on the surface of the capsule core; the capsule core comprises reduced iron powder, activated carbon, sodium chloride, reaction promoter and water-absorbing resin, and the capsule wall comprises poly (N-isopropyl acrylamide), gelatin, glutaraldehyde and nano silicon dioxide.

[0006] In the specific embodiment of the present application, based on 100% of the mass of the heating microcapsule, the heating microcapsule comprises reduced iron powder 40%-60%, activated carbon 10%-20%, sodium chloride 2%-5%, reaction promoter 1%-3%, water-absorbing resin 2%-8%, poly (N-isopropyl acrylamide) 15%-25%, gelatin 5%-15%, glutaraldehyde 1%-3% and nano silicon dioxide 2%-5%.

[0007] In a specific embodiment of the present invention, the liquid resin includes at least one of liquid petroleum resin and liquid rosin resin. Further, the glass transition temperature of the liquid resin is not higher than -20°C.

[0008] In a specific embodiment of the present invention, the liquid rubber includes at least one of liquid butadiene rubber, liquid styrene-butadiene rubber, and liquid polyisobutylene rubber.

[0009] In a specific embodiment of the present invention, the mass ratio of the liquid resin to the liquid rubber is 1:(1.2~2).

[0010] In a specific embodiment of the present invention, the styrene block copolymer includes at least one selected from styrene-isoprene-styrene block copolymer, styrene-butadiene-styrene block copolymer, styrene-ethylene / butene-styrene block copolymer, and styrene-ethylene / propylene-styrene block copolymer. Further, in the styrene block copolymer, the diblock content is ≥50 wt%.

[0011] In a specific embodiment of the present invention, the plasticizer includes at least one of naphthenic oil, ester plasticizer and ether plasticizer.

[0012] In a specific embodiment of the present invention, the tackifying resin includes at least one of rosin resin, petroleum resin and terpene resin.

[0013] The second aspect of the present invention provides a method for preparing the self-heating label adhesive of the first aspect of the present invention, comprising the following steps: kneading styrene block copolymer, plasticizer and antioxidant, adding tackifying resin, liquid resin and liquid rubber and stirring to melt, and then adding heating microcapsules to obtain the self-heating label adhesive.

[0014] In a specific embodiment of the present invention, the method for preparing the heating microcapsules includes: (a) Reduced iron powder, activated carbon, sodium chloride, and reaction promoter are mixed and ball-milled in a dispersion medium, and then mixed evenly with water-absorbing resin to obtain a core composition; the core composition is dispersed in an organic solvent to obtain an oil phase; (b) After dissolving gelatin in water, add poly(N-isopropylacrylamide) and stir until dissolved. Then add nano-silica, followed by an emulsifier, and adjust the pH to 6.5-7 to obtain an aqueous phase. Under stirring conditions, add the oil phase to the aqueous phase for emulsification. Then add glutaraldehyde and adjust the pH to 8.5-9 to carry out a crosslinking reaction. After the reaction is completed, allow the lower precipitate to stand and collect to obtain the exothermic microcapsules.

[0015] A third aspect of the present invention provides a self-heating label, comprising a substrate and an adhesive layer disposed on the surface of the substrate; the adhesive layer comprises the self-heating label adhesive provided in the first aspect of the present invention.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The adhesive of the present invention is compounded with multiple components, using liquid resin and liquid rubber to reduce the glass transition temperature of the overall adhesive. At the same time, it is combined with the effect of opening the pores of the heating microcapsules to activate heating at low temperature and closing the pores to isolate oxygen at high temperature, so that the adhesive has good initial tack, peel strength and bonding stability to the bonded material under low temperature conditions (such as -30℃). (2) When the adhesive of the present invention is used at high temperature, the pores of the capsule wall of the heating microcapsule are closed, effectively isolating oxygen from contact with the capsule core, preventing oxidation, and extending the shelf life; when used at low temperature, the capsule wall of the heating microcapsule forms microporous channels, activating the heating reaction, which fully meets the application requirements of cold chain labels. Detailed Implementation

[0017] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0018] A first aspect of the present invention provides a self-heating label adhesive, comprising the following components in parts by weight: The mixture contains 20-30 parts of styrene block copolymer, 10-30 parts of plasticizer, 25-40 parts of tackifying resin, 5-10 parts of liquid resin, 10-20 parts of liquid rubber, 20-30 parts of heat-generating microcapsules, and 0.1-1 parts of antioxidant. The exothermic microcapsule includes a core and a capsule wall encapsulating the surface of the core; the core includes reduced iron powder, activated carbon, sodium chloride, reaction promoter and water-absorbing resin, and the capsule wall includes poly(N-isopropylacrylamide), gelatin, glutaraldehyde and nano-silica.

[0019] The adhesive of the present invention is formulated with multiple components, including liquid resin and liquid rubber, which lowers the glass transition temperature of the overall adhesive. At the same time, it is combined with the effect of opening the pores of the heating microcapsules to activate heating at low temperatures and closing the pores to isolate oxygen at high temperatures, so that the adhesive has good initial tack, peel strength and bonding stability to the substrate under low temperature conditions (such as -30°C).

[0020] In some embodiments, the styrene block copolymer in the adhesive is 20 to 30 parts by weight, for example, 20 parts, 22 parts, 25 parts, 28 parts, 30 parts, or any combination thereof; the introduction of an appropriate amount of styrene block copolymer, in combination with the other components, gives the adhesive a certain initial tack and strength.

[0021] In some embodiments, the styrene block copolymer includes at least one of styrene-isoprene-styrene block copolymer (SIS), styrene-butadiene-styrene block copolymer (SBS), styrene-ethylene / butene-styrene block copolymer (SEBS), and styrene-ethylene / propylene-styrene block copolymer (SEPS). Further, the diblock content in the styrene block copolymer is ≥50 wt%, for example, 50 wt% to 70 wt%, specifically within the range of 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, or any combination thereof. An appropriate diblock content helps to achieve a good balance between the initial tack and cohesive strength of the adhesive. When the diblock content is too low, the initial tack of the adhesive is insufficient; when the diblock content is too high, the cohesive strength decreases and the holding power deteriorates.

[0022] In some embodiments, the plasticizer in the adhesive is 10 to 30 parts by weight, for example, 10, 12, 15, 18, 20, 22, 25, 28, 30 parts, or any combination thereof. The introduction of an appropriate amount of plasticizer helps improve the wettability of the adhesive to the surface of the substrate under low-temperature conditions, thereby improving initial tack. When the amount of plasticizer is too low, the improvement in the initial tack of the adhesive is not significant; when the amount of plasticizer is too high, the cohesive strength of the adhesive is significantly reduced, and the peel strength decreases.

[0023] In some embodiments, the plasticizer includes at least one of naphthenic oils, ester plasticizers, and ether plasticizers, preferably ester plasticizers. Esters include at least one of phthalate plasticizers, terephthalate plasticizers, and aliphatic diester plasticizers.

[0024] In some embodiments, the phthalate plasticizer includes at least one of di(2-ethylhexyl) phthalate (DOP), diisononyl phthalate (DINP), and diisodecyl phthalate (DIDP).

[0025] In some embodiments, the plasticizer has a pour point below -20°C, for example, a range of -20°C, -22°C, -25°C, -28°C, -30°C, -35°C, -40°C, -45°C, -50°C, or any combination thereof.

[0026] In some embodiments, the tackifying resin in the adhesive is 25 to 40 parts by weight, for example, 25, 28, 30, 32, 35, 38, 40 parts or any combination thereof; when the amount of tackifying resin is too low, the initial tack and peel strength deteriorate; when the amount of tackifying resin is too high, the glass transition temperature is high and the low-temperature performance is poor.

[0027] In some embodiments, the tackifying resin includes at least one of rosin resin, petroleum resin, and terpene resin, preferably rosin resin. Rosin resin has relatively greater polarity, which is more beneficial for improving the initial tack and peel strength of the adhesive to the surface of the substrate at low temperatures.

[0028] In some embodiments, the liquid resin in the adhesive comprises 5 to 10 parts by weight, for example, 5, 6, 7, 8, 9, 10 parts, or any combination thereof. The introduction of an appropriate amount of liquid resin lowers the glass transition temperature of the adhesive, preventing it from becoming brittle and hard at low temperatures. When the amount of liquid resin is too low, its effect on lowering the glass transition temperature of the adhesive is not significant; when the amount of liquid resin is too high, it reduces the interaction forces between polymer molecules in the adhesive, leading to decreased cohesive strength and poorer tack.

[0029] In some embodiments, the liquid resin includes at least one of liquid petroleum resin and liquid rosin resin. Further, the glass transition temperature of the liquid resin is not higher than -20°C, for example, it can be a range of -20°C, -21°C, -22°C, -24°C, -25°C, -28°C, or any combination thereof.

[0030] In some embodiments, the liquid rubber in the adhesive is 10 to 20 parts by weight, for example, 10, 11, 12, 14, 16, 18, 20 parts, or any combination thereof. The appropriate amount of liquid rubber is introduced to work with the liquid resin to lower the glass transition temperature of the adhesive, preventing it from becoming brittle and hard at low temperatures. When the amount of liquid rubber is too low, its effect on lowering the glass transition temperature of the adhesive is not significant; when the amount of liquid rubber is too high, it leads to a decrease in the initial tack of the adhesive.

[0031] In some embodiments, the liquid rubber includes at least one of liquid butadiene rubber, liquid styrene-butadiene rubber, and liquid polyisobutylene rubber, preferably liquid polyisobutylene rubber. Liquid polyisobutylene rubber has better flowability and low-temperature properties, which helps to improve the low-temperature performance of the adhesive.

[0032] In some embodiments, the mass ratio of liquid resin to liquid rubber is 1:(1.2-2), specifically within the range of 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2, or any combination thereof. Although both liquid resin and liquid rubber can lower the glass transition temperature of an adhesive system, their effects on the initial tack, cohesive strength, and holding power of the adhesive differ. Liquid resin, while lowering the glass transition temperature, can impart a certain initial tack to the adhesive, but it weakens the cohesive strength. Liquid rubber, while lowering the glass transition temperature, can form an entangled network structure with molecular weights such as styrene block copolymers, improving the cohesive strength of the adhesive, but its structure lacks polar groups and cannot effectively improve the initial tack. Furthermore, a suitable liquid rubber can improve the flowability of the adhesive. This invention regulates the amount of liquid resin and liquid rubber within the above-mentioned range, thereby reducing the glass transition temperature of the adhesive while simultaneously improving the initial tack, cohesive strength, and holding power of the adhesive.

[0033] In some embodiments, the antioxidant in the adhesive is 0.1 to 1 part by weight, for example, it can be 0.1 part, 0.3 part, 0.5 part, 0.8 part, 1 part or any combination thereof.

[0034] In some embodiments, the antioxidants include hindered phenolic antioxidants and / or phosphite antioxidants.

[0035] In some embodiments, the amount of heat-generating microcapsules in the adhesive is 20 to 30 parts by weight, for example, 20, 22, 25, 28, 30 parts, or any combination thereof. The introduction of an appropriate amount of heat-generating microcapsules can activate heating under low-temperature conditions, improving the low-temperature performance of the adhesive. However, the introduction of excessive amounts of heat-generating microcapsules can lead to poor system compatibility and affect the performance of the adhesive.

[0036] In some embodiments, the heating microcapsules, based on the total mass of 100%, comprise 40%–60% reduced iron powder, 10%–20% activated carbon, 2%–5% sodium chloride, 1%–3% reaction promoter, 2%–8% water-absorbing resin, 15%–25% poly(N-isopropylacrylamide), 5%–15% gelatin, 1%–3% glutaraldehyde, and 2%–5% nano-silica.

[0037] In different embodiments, taking the total mass of the heating microcapsules as 100%, the amounts of each component in the heating microcapsules can be as follows: The amount of reduced iron powder can be 40%, 45%, 50%, 55%, 60%, or any combination thereof. The amount of activated carbon used can be 10%, 12%, 15%, 18%, 20%, or any combination thereof; The amount of sodium chloride used can be 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any combination thereof; The amount of reaction promoter can be 1%, 1.5%, 2%, 2.5%, 3%, or any combination thereof; The amount of water-absorbing resin can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, or any combination thereof. The amount of poly(N-isopropylacrylamide) can be 15%, 18%, 20%, 22%, 25%, or any combination thereof; The amount of gelatin used can be 5%, 8%, 10%, 12%, 15%, or any combination thereof; The dosage of glutaraldehyde can be 1%, 1.5%, 2%, 2.5%, 3%, or any combination thereof; The amount of nano silica used can be 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any combination thereof.

[0038] In some embodiments, the average particle size of the reduced iron powder is 300 to 500 mesh.

[0039] In some embodiments, the specific surface area of ​​the activated carbon is not less than 800 m². 2 / g.

[0040] In some implementations, the reaction promoter is manganese dioxide.

[0041] In some embodiments, the water-absorbing resin is sodium polyacrylate.

[0042] In some embodiments, the mass ratio of the core to the wall in the heating microcapsule is (2.5 to 3):1, for example, it can be a range of 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1, 3:1 or any two of these.

[0043] In some embodiments, the method for preparing the heating microcapsules includes: (a) Reduced iron powder, activated carbon, sodium chloride, and reaction promoter are mixed and ball-milled in a dispersion medium, and then mixed evenly with a water-absorbing resin to obtain a core composition; the core composition is dispersed in an organic solvent to obtain an oil phase; (b) After dissolving gelatin in water, add poly(N-isopropylacrylamide) and stir until dissolved. Then add nano-silica, emulsifier, and adjust pH to 6.5-7 to obtain an aqueous phase. Add the oil phase to the aqueous phase under stirring and emulsify. Then add glutaraldehyde and adjust pH to 8.5-9 to carry out cross-linking reaction. After the reaction is completed, let stand and collect the lower precipitate to obtain the exothermic microcapsules.

[0044] Before use, reduced iron powder can be pre-treated by drying in a vacuum oven at 100℃.

[0045] In some embodiments, in step (a), the dispersion medium is ethanol. Further, the amount of ethanol used is 1 to 2 times the mass of the reduced iron powder, activated carbon, sodium chloride, and reaction promoter (to visually ensure that all powders are wetted and a uniform suspension is formed).

[0046] In some implementations, after ball milling, the ethanol is removed before subsequent operations are performed. Methods for removing ethanol include, but are not limited to, drying.

[0047] In some embodiments, in step (a), the organic solvent includes toluene and cyclohexane. Further, the volume ratio of toluene to cyclohexane in the organic solvent is 1:(2-3).

[0048] In some embodiments, in step (a), the mass ratio of the core composition to the organic solvent is 1:(2.5–3.5). Further, the core composition is dispersed in the organic solvent by ultrasonic treatment.

[0049] In some embodiments, the mass ratio of gelatin to water in step (b) is 1:(10-13).

[0050] In some embodiments, the emulsifier includes a nonionic emulsifier. Further, the emulsifier includes, but is not limited to, at least one of polyoxyethylene sorbitan fatty acid ester, sorbitan monolaurate, sorbitan monostearate, and sorbitan monooleate.

[0051] In some embodiments, the amount of emulsifier used is 1% to 2% of the total mass of the aqueous phase.

[0052] In some embodiments, the emulsification time is 20–40 min and the emulsification temperature is 35–45 °C. The emulsification time can be adjusted according to the obtained emulsion particle size, with the aim of obtaining an emulsion particle size of 20–50 μm.

[0053] In some embodiments, glutaraldehyde is added in the form of an aqueous solution of glutaraldehyde. Further, the glutaraldehyde aqueous solution contains 2% to 3% by mass, such as 2.5%, but not limited to this.

[0054] In some embodiments, the crosslinking reaction is carried out at a temperature of 45–55°C for 3–4 hours.

[0055] In some embodiments, the process further includes washing the lower precipitate with deionized water to remove unreacted substances and emulsifiers, followed by drying.

[0056] In some embodiments, a 2% HCl solution is used when adjusting the pH to 6.5-7; and a 2% NaOH aqueous solution is used when adjusting the pH to 8.5-9.

[0057] The second aspect of the present invention provides a method for preparing the self-heating label adhesive of the first aspect of the present invention, comprising the following steps: kneading styrene block copolymer, plasticizer and antioxidant, adding tackifying resin, liquid resin and liquid rubber and stirring to melt, and then adding heating microcapsules to obtain the self-heating label adhesive.

[0058] In some embodiments, the kneading temperature is 160–180°C, for example, a range of 160°C, 165°C, 170°C, 175°C, 180°C or any combination thereof; the kneading time is 20–40 min, for example, a range of 20 min, 25 min, 30 min, 35 min, 40 min or any combination thereof.

[0059] In some embodiments, the temperature during stirring and melting is 160–180°C, for example, a range of 160°C, 165°C, 170°C, 175°C, 180°C, or any combination thereof.

[0060] In some embodiments, after adding the heating microcapsules, the mixture is vacuumed and defoamed under stirring conditions, and after being mixed evenly, heating and stirring are stopped, and the material is discharged while still hot.

[0061] A third aspect of the present invention provides a self-heating label, comprising a substrate and an adhesive layer disposed on the surface of the substrate; the adhesive layer comprises the self-heating label adhesive provided in the first aspect of the present invention.

[0062] In some embodiments, the substrate includes any one of thermal paper, coated paper, or synthetic paper.

[0063] This invention also provides a method for preparing a self-heating label. In practice, the adhesive layer can be obtained by coating the prepared self-heating label adhesive onto a substrate and then drying it. The coating method includes, but is not limited to, using a pressure plate coating machine for scraping.

[0064] In some implementations, the amount of adhesive applied to the adhesive layer can be freely selected according to actual needs, for example, it can be 18 to 22 gsm.

[0065] The specific embodiments and comparative examples of this invention used some raw material information as follows, but are not limited thereto: Styrene block copolymer SIS 9270, Ningbo Jinhai Chenguang Chemical Co., Ltd.; Styrene block copolymer SBS 3545, Lee Chang Yung Chemical Industry Co., Ltd.; Styrene block copolymer SIS 1106, Sinopec Baling Petrochemical Co., Ltd.; Rosin resin GA-90DG, Arakawa Chemical Industry Co., Ltd. Liquid resin C8010, glass transition temperature -24°C, Eastman Chemical Company; Liquid polyisobutylene PB950, Daelim, South Korea; Liquid polyisobutylene PB1300, Daelim, South Korea; Reduced iron powder, Lingshou County Shicheng New Material Technology Co., Ltd.; Activated carbon, Linyi Mengjieer Activated Carbon Co., Ltd.; Sodium polyacrylate, Tianjin Kemeo Chemical Reagent Co., Ltd. Poly(N-isopropylacrylamide), Shanghai Yuanye Biotechnology Co., Ltd.; Nano-silica, Weifang Sanjia Chemical Co., Ltd.

[0066] Example 1 This embodiment provides a self-heating label adhesive, comprising the following components in parts by weight: Styrene block copolymer SIS 9270 25 parts, plasticizer DINP 15 parts, tackifying resin rosin resin 25 parts, liquid resin C8010 8 parts, liquid rubber polyisobutylene PB950 12 parts, heating microcapsules 25 parts, antioxidant 1010 0.3 parts and antioxidant 168 0.2 parts.

[0067] The preparation method of self-heating label adhesive includes: adding styrene block copolymer, plasticizer, and antioxidant into a kneader and kneading at 170°C for 30 minutes; then slowly adding tackifying resin, liquid resin, and liquid rubber, and continuing to stir and melt at 170°C until uniformly mixed; then slowly adding heating microcapsules, stirring at a low speed of 20 rpm, and vacuuming to remove air bubbles. When the system becomes a uniform viscous liquid, stop heating and stirring, and discharge the material while hot to obtain the self-heating label adhesive to be coated.

[0068] The self-heating label adhesive is applied to the substrate surface using a scraping coating method. The amount of adhesive applied is 18-22 gsm (e.g., 20 gsm). The label is then laminated with release paper and sealed in packaging to obtain the self-heating label.

[0069] The preparation method of the heating microcapsules in this embodiment includes: (1) Weigh out 42% reduced iron powder, 15% activated carbon, 3% sodium chloride, 2% manganese dioxide, 5% sodium polyacrylate, 20% poly(N-isopropylacrylamide), 8% gelatin, 2% glutaraldehyde and 3% nano silica by mass percentage; wherein, glutaraldehyde is in the form of 2.5wt% glutaraldehyde aqueous solution, and the amount used is based on the glutaraldehyde content in the aqueous solution.

[0070] (2) Take reduced iron powder, activated carbon, sodium chloride and manganese dioxide, add ethanol as dispersion medium, ball mill and mix evenly, then add sodium polyacrylate and stir evenly to obtain the core composition; then add the core composition to a mixed solvent of toluene and cyclohexane, sonicate for 20 min to form a uniform suspension as the oil phase; The amount of ethanol used is twice the sum of the masses of reduced iron powder, activated carbon, sodium chloride, and manganese dioxide; the amount of the mixed solvent of toluene and cyclohexane is 2.8 times the mass of the core composition; and the volume ratio of toluene to cyclohexane in the mixed solvent of toluene and cyclohexane is 1:2.

[0071] (3) Dissolve gelatin in deionized water, heat to 50°C to dissolve gelatin, then add poly(N-isopropylacrylamide), stir until dissolved, then add nano silica, stir to disperse evenly, then add Tween-80, then add 2% HCl solution to adjust pH to 6.8, then keep the temperature at 40°C as the aqueous phase; The amount of deionized water used is 12 times the mass of gelatin, and the amount of Tween-80 used is 1% of the total mass of the aqueous phase.

[0072] (4) Slowly add the oil phase obtained in step (2) to the aqueous phase in step (3). The initial stirring speed is 500 rpm. After the oil phase is added, increase the speed to 3000 rpm and stir at 3000 rpm for 30 min. Control the emulsification temperature to 40℃. After emulsification, raise the temperature to 50℃ and slowly add glutaraldehyde aqueous solution. After the addition is complete, add 2% NaOH aqueous solution to adjust the pH to 8.8 and react at 50℃ for 3 h.

[0073] (5) Cool the material after the reaction in step (4) to room temperature, stop stirring, and let it stand to separate into layers; then remove the supernatant, wash the lower precipitate three times with deionized water, and then vacuum dry to obtain the exothermic microcapsules.

[0074] Example 2 This embodiment refers to Embodiment 1, the only difference being that the amount of some components in the self-heating label adhesive is different.

[0075] The self-heating label adhesive of this embodiment includes the following components in parts by weight: Styrene block copolymer SIS 9270 20 parts, plasticizer DINP 15 parts, tackifying resin rosin resin 25 parts, liquid resin C8010 8 parts, liquid rubber polyisobutylene PB950 12 parts, heating microcapsules 30 parts, antioxidant 1010 0.3 parts and antioxidant 168 0.2 parts.

[0076] Example 3 This embodiment refers to Embodiment 1, the only difference being that the amount of some components in the self-heating label adhesive is different.

[0077] The self-heating label adhesive of this embodiment includes the following components in parts by weight: Styrene block copolymer SIS 9270 30 parts, plasticizer DINP 15 parts, tackifying resin rosin resin 25 parts, liquid resin C8010 8 parts, liquid rubber polyisobutylene PB950 12 parts, heating microcapsules 20 parts, antioxidant 1010 0.3 parts and antioxidant 168 0.2 parts.

[0078] Example 4 This embodiment refers to Embodiment 1, the only difference being that the styrene block copolymer and the type of liquid rubber are different.

[0079] In this embodiment, the styrene block copolymer is styrene block copolymer SBS 3545; the liquid rubber is liquid polyisobutylene PB1300.

[0080] Example 5 This embodiment refers to Embodiment 1, the only difference being that the amount of some components in the self-heating label adhesive is different.

[0081] The self-heating label adhesive of this embodiment includes the following components in parts by weight: Styrene block copolymer SIS 9270 25 parts, plasticizer DINP 15 parts, tackifying resin rosin resin 25 parts, liquid resin C8010 10 parts, liquid rubber polyisobutylene PB950 10 parts, heating microcapsules 25 parts, antioxidant 1010 0.3 parts and antioxidant 168 0.2 parts.

[0082] Example 6 This embodiment refers to Embodiment 1, the only difference being that the amount of some components in the self-heating label adhesive is different.

[0083] The self-heating label adhesive of this embodiment includes the following components in parts by weight: Styrene block copolymer SIS 9270 25 parts, plasticizer DINP 15 parts, tackifying resin rosin resin 25 parts, liquid resin C8010 5 parts, liquid rubber polyisobutylene PB950 15 parts, heating microcapsules 25 parts, antioxidant 1010 0.3 parts and antioxidant 168 0.2 parts.

[0084] Example 7 This embodiment refers to Embodiment 1, the only difference being that the type of styrene block copolymer is different.

[0085] The styrene block copolymer in this embodiment is styrene block copolymer SIS 1106.

[0086] Comparative Example 1 Comparative Example 1 refers to Example 1, except that the amount of some components in the self-heating label adhesive is different.

[0087] The self-heating label adhesive of this comparative example comprises the following components by weight: Styrene block copolymer SIS 9270 40 parts, plasticizer DINP 15 parts, tackifying resin rosin resin 25 parts, liquid resin C8010 8 parts, liquid rubber polyisobutylene PB950 12 parts, heating microcapsules 10 parts, antioxidant 1010 0.3 parts and antioxidant 168 0.2 parts.

[0088] Comparative Example 2 Comparative Example 2 is the same as Example 1, except that the amount of some components in the self-heating label adhesive is different.

[0089] The self-heating label adhesive of this comparative example comprises the following components by weight: Styrene block copolymer SIS 9270 10 parts, plasticizer DINP 15 parts, tackifying resin rosin resin 25 parts, liquid resin C8010 8 parts, liquid rubber polyisobutylene PB950 12 parts, heating microcapsules 40 parts, antioxidant 1010 0.3 parts and antioxidant 168 0.2 parts.

[0090] Comparative Example 3 Comparative Example 3 refers to Example 1, except that the amount of some components in the self-heating label adhesive is different.

[0091] The self-heating label adhesive of this comparative example comprises the following components by weight: Styrene block copolymer SIS 9270 25 parts, plasticizer DINP 15 parts, tackifying resin rosin resin 33 parts, liquid rubber polyisobutylene PB950 12 parts, heating microcapsules 25 parts, antioxidant 1010 0.3 parts and antioxidant 168 0.2 parts.

[0092] Comparative Example 4 Comparative Example 4 refers to Example 1, except that the amount of some components in the self-heating label adhesive is different.

[0093] The self-heating label adhesive of this comparative example comprises the following components by weight: Styrene block copolymer SIS 9270 37 parts, plasticizer DINP 15 parts, tackifying resin rosin resin 25 parts, liquid resin C8010 8 parts, heat-generating microcapsules 25 parts, antioxidant 1010 0.3 parts and antioxidant 168 0.2 parts.

[0094] Comparative Example 5 Comparative Example 5 refers to Example 1, except that the amount of some components in the self-heating label adhesive is different.

[0095] The self-heating label adhesive of this comparative example comprises the following components by weight: Styrene block copolymer SIS 9270 37 parts, plasticizer DINP 18 parts, tackifying resin rosin resin 35 parts, liquid resin C8010 8 parts, liquid rubber polyisobutylene PB950 12 parts, antioxidant 1010 0.3 parts and antioxidant 168 0.2 parts.

[0096] Experimental Example Label samples prepared in different embodiments and comparative examples were tested. The test results are shown in Table 1. The test methods are as follows.

[0097] (1) Peel strength at -30℃: The label sample was cut into strips 2.5cm wide. The test method was carried out in accordance with GB / T 2792-2014 "Test method for peel strength of adhesive tape". The test panel was a steel plate. The peel strength test at -30℃ refers to: after placing the label sample and the test panel at -30±2℃ for 2 hours, the sealed packaging and release paper were torn off, the adhesive layer of the label sample was attached to the test panel, and after placing it at -30±2℃ for 20 minutes, the test was carried out at -30℃. The average adhesive force required to peel the label strip from the panel was recorded and expressed as N / 25mm.

[0098] (2) -30℃ ring initial tack: Cut the label sample into strips 2.5cm wide. The test method is in accordance with GB / T 31125-2014 "Test Method for Initial Tack of Adhesive Tape - Ring Method". The test panel is a steel plate. The -30℃ ring initial tack test means that after placing the label sample and the test panel at -30±2℃ for 2 hours, the sealed packaging and release paper are torn off, and then the ring initial tack of the label to the steel plate is tested.

[0099] (3) Low temperature labeling application test: After placing the label sample and PE packaging bag at -30±2℃ for 2 hours, tear off the sealed packaging and release paper, and attach it to the PE packaging bag after 1 minute. Tear it off 5 minutes after attaching and visually observe the material breaking effect. If material breaking occurs, calculate the proportion of the area of ​​the label sample remaining in the PE bag after material breaking to the total area of ​​the label sample, which is taken as the material breaking ratio.

[0100] (4) Low temperature labeling and storage application test: After placing the label sample and PE packaging bag at -30±2℃ for 2 hours, tear open the sealed packaging and release paper, and then attach it to the PE packaging bag after 2 minutes. Then place it at -60±2℃ for 24 hours and visually observe whether the label sample peels off or falls off.

[0101] Table 1 Performance test results for different labels

[0102] The test results above show that the adhesive of the present invention is compounded with multiple components, using liquid resin and liquid rubber to reduce the glass transition temperature of the overall adhesive. At the same time, the heating microcapsules open at low temperatures to activate heating and close at high temperatures to isolate oxygen, so that the adhesive has good initial tack, peel strength and bonding stability to the substrate under low temperature conditions (such as -30°C).

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A self-heating label adhesive, characterized by The composition comprises the following components by weight parts: The styrene block copolymer 20-30 parts, plasticizer 10-30 parts, tackifying resin 25-40 parts, liquid resin 5-10 parts, liquid rubber 10-20 parts, heat generating microcapsule 20-30 parts and antioxidant 0.1-1 parts; The heat generating microcapsule comprises a capsule core and a capsule wall wrapped on the surface of the capsule core; the capsule core comprises reduced iron powder, activated carbon, sodium chloride, a reaction promoter and a water-absorbing resin, and the capsule wall comprises poly(N-isopropyl acrylamide), gelatin, glutaraldehyde and nano-silicon dioxide.

2. The self-warming label adhesive according to claim 1, wherein The heat generating microcapsule comprises, based on 100% of the mass of the heat generating microcapsule, 40-60% of reduced iron powder, 10-20% of activated carbon, 2-5% of sodium chloride, 1-3% of a reaction promoter, 2-8% of a water-absorbing resin, 15-25% of poly(N-isopropyl acrylamide), 5-15% of gelatin, 1-3% of glutaraldehyde and 2-5% of nano-silicon dioxide.

3. The self-warming label adhesive according to claim 1, wherein At least one of the following characteristics is possessed: (1) The liquid resin comprises at least one of liquid petroleum resin and liquid rosin resin; (2) The glass transition temperature of the liquid resin is not higher than -20℃.

4. The self-warming label adhesive according to claim 1, wherein The liquid rubber comprises at least one of liquid butadiene rubber, liquid styrene-butadiene rubber and liquid polyisobutylene rubber.

5. The self-warming label adhesive of claim 1, wherein The mass ratio of the liquid resin to the liquid rubber is 1:(1.2-2).

6. The self-heat generating label adhesive according to claim 1, wherein At least one of the following characteristics is possessed: (1) The styrene block copolymer comprises at least one of styrene-isoprene-styrene block copolymer, styrene-butadiene-styrene block copolymer, styrene-ethylene / butylene-styrene block copolymer and styrene-ethylene / propylene-styrene block copolymer; (2) In the styrene block copolymer, the content of diblock is ≥50wt%.

7. The self-heat generating label adhesive according to claim 1, wherein At least one of the following characteristics is possessed: (1) The plasticizer comprises at least one of naphthenic oil, ester plasticizer and ether plasticizer; (2) The tackifying resin comprises at least one of rosin resin, petroleum resin and terpene resin.

8. The method of producing a self-heating label adhesive according to any one of claims 1 to 7, characterized in that, The method comprises the following steps: after the styrene block copolymer, the plasticizer and the antioxidant are kneaded and treated, the tackifying resin, the liquid resin and the liquid rubber are added and stirred to melt, and then the heat generating microcapsule is added to obtain the self-heating label adhesive.

9. The production method according to claim 8, characterized by, The preparation method of the heat generating microcapsule comprises the following steps: (a) The reduced iron powder, the activated carbon, the sodium chloride and the reaction promoter are mixed and ball milled in a dispersion medium, and then mixed uniformly with the water-absorbing resin to obtain a capsule core composition; the capsule core composition is dispersed in an organic solvent to obtain an oil phase; (b) The gelatin is dissolved in water, the poly(N-isopropyl acrylamide) is stirred to dissolve, then the nano-silicon dioxide is added, the emulsifier is added, and the pH is adjusted to 6.5-7 to obtain an aqueous phase; the oil phase is added to the aqueous phase under stirring, emulsified, then the glutaraldehyde is added, and the pH is adjusted to 8.5-9 to perform a crosslinking reaction; after the reaction is completed, the lower layer precipitate is collected after standing to obtain the heat generating microcapsule.

10. A self-heating label characterized in that, A self-heating label adhesive comprising a substrate and an adhesive layer disposed on a surface of the substrate; the adhesive layer comprising the self-heating label adhesive of any one of claims 1 to 7.

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