Biodegradable pressure-sensitive adhesive and preparation method thereof

Abstract

The invention belongs to the technical field of pressure-sensitive adhesives, and provides a biodegradable pressure-sensitive adhesive and a preparation method thereof. The biodegradable pressure-sensitive adhesive is prepared from the following raw materials in parts by weight: 50 to 60 parts of polybutylene succinate, 20 to 30 parts of degradable thermoplastic elastomer, 20 to 30 parts of tackifying resin, 6 to 12 parts of plasticizer, 0.5 to 1.5 parts of mildew preventive, 0.5 to 2 parts of antioxidant and 0.3 to 1 part of anti-aging agent, wherein the degradable thermoplastic elastomer is a polycaprolactone-polylactide segmented copolymer, the weight-average relative molecular mass of the degradable thermoplastic elastomer is 50000 to 70000, and the content of a polycaprolactone phase in the polycaprolactone-polylactide segmented copolymer is 65 to 80 percent. The biodegradable pressure-sensitive adhesive not only has excellent adhesive property, but also has excellent biodegradability, and can effectively overcome the defects of weak cohesion, poor adhesive property and poor degradability of the existing hot-melt pressure-sensitive adhesive containing the thermoplastic elastomer.

Description

Technical Field

[0001] The present invention relates to the technical field of pressure-sensitive adhesives, and particularly to a biodegradable pressure-sensitive adhesive and a preparation method thereof. Background Art

[0002] Pressure-sensitive adhesives, commonly known as self-adhesive tapes, can be classified into solvent-based pressure-sensitive adhesives, emulsion-based pressure-sensitive adhesives, hot-melt pressure-sensitive adhesives, and photocurable pressure-sensitive adhesives according to the preparation process. In recent years, the output of solvent-based pressure-sensitive adhesives has been decreasing year by year. Although emulsion-based pressure-sensitive adhesives use water as a solvent, which is environmentally friendly, they have problems such as slow drying speed and emulsifier migration, which affect their promotion and application. Among them, hot-melt pressure-sensitive adhesives are the third-generation pressure-sensitive adhesive products after solvent-based pressure-sensitive adhesives and emulsion-based pressure-sensitive adhesives. Compared with solvent-based pressure-sensitive adhesives and emulsion-based pressure-sensitive adhesives, hot-melt pressure-sensitive adhesives are more environmentally friendly, safer, and have higher production efficiency and relatively lower production costs because they do not require the addition of solvents. Therefore, hot-melt pressure-sensitive adhesives have attracted the attention and emphasis of researchers. Currently, hot-melt pressure-sensitive adhesives have been widely used in technical fields such as adhesive labels for packaging products, medical supplies, and textile products.

[0003] In the prior art, as shown in the publication number CN110093128A, the raw materials of hot-melt pressure-sensitive adhesives include thermoplastic elastomers such as SBS and SIS, tackifiers, plasticizers, fillers, antioxidants, and so on. However, SBS and SIS have low molecular polarity and unsaturated double bonds in the molecules. Therefore, the existing hot-melt pressure-sensitive adhesives will inevitably have the following defects in their use performance: (1) The cohesive force of this kind of hot-melt pressure-sensitive adhesive is relatively weak, and its heat and oxygen aging resistance is not good. The bonding strength to polar materials is not high enough, and it is easy to fall off; (2) Although this kind of hot-melt pressure-sensitive adhesive has certain degradability under certain specific conditions, the conditions are harsh, and the biodegradation rate is low, resulting in poor biodegradation performance and being unfavorable to environmental protection. Summary of the Invention

[0004] The purpose of the present invention is to provide a biodegradable pressure-sensitive adhesive and a preparation method thereof in view of the deficiencies of the prior art.

[0005] Based on this, the present invention discloses a biodegradable pressure-sensitive adhesive, which comprises the following raw materials in parts by weight: 50 - 60 parts of polybutylene succinate; 20 - 30 parts of degradable thermoplastic elastomer; 20 - 30 parts of tackifying resin; 6 - 12 parts of plasticizer; 0.5 - 1.5 parts of mildew-proof agent; 0.5 - 2 parts of antioxidant; 0.3 - 1 part of anti-aging agent; Among them, the degradable thermoplastic elastomer is a polycaprolactone - polylactide block copolymer, with a weight - average relative molecular mass of 50000 - 70000, and the content of the polycaprolactone phase in the polycaprolactone - polylactide block copolymer is 65 - 80%. Preferably, the weight - average relative molecular mass of the polycaprolactone - polylactide block copolymer is 60000, and the content of the polycaprolactone phase in the polycaprolactone - polylactide block copolymer is 76%. Further preferably, a biodegradable pressure - sensitive adhesive comprises raw materials in the following weight fractions: 52 parts of polybutylene succinate; 28 parts of degradable thermoplastic elastomer; 23 parts of tackifying resin; 10 parts of plasticizer; 1.2 parts of mildew preventive; 1.5 parts of antioxidant; 0.7 part of anti - aging agent. Preferably, the tackifying resin is at least one of hydrogenated rosin, hydrogenated rosin glyceride, polycaprolactone polyol, and polylactic acid polyol. Preferably, the plasticizer is at least one of dibutyl phthalate, dioctyl phthalate, dioctyl sebacate, and liquid paraffin.

[0006] Preferably, the mildew preventive is at least one of 2 - pyridinethiol - 1 - zinc oxide, 5 - chloro - 2 - methyl - 4 - isothiazolin - 3 - one, copper - 8 - hydroxyquinoline, ammonium persulfate, and calcium phosphate. Preferably, the antioxidant is at least one of tris(2,4 - di - tert - butylphenyl) phosphite, bis(2,4 - di - tert - butylphenyl) pentaerythritol diphosphite, and 2,6 - di - tert - butyl - p - cresol.

[0007] Preferably, the anti - aging agent is at least one of methyl 2 - hydroxybenzoate, 6 - ethoxy - 2,2,4 - trimethyl - 1,2 - dihydroquinoline, N - phenyl - 1 - naphthylamine, and N - isopropyl - N'- phenyl - p - phenylenediamine. The present invention also discloses a preparation method of the biodegradable pressure - sensitive adhesive, comprising the following preparation steps: S1. Under the protection of inert gas, melt - mix polybutylene succinate, degradable thermoplastic elastomer, tackifying resin, plasticizer, and antioxidant weighed according to the formula amounts; S2. Then add the anti - aging agent and mildew preventive in the formula amounts and continue melt - mixing to obtain the biodegradable pressure - sensitive adhesive.

[0008] Preferably, in step S1, the temperature of the melt mixing is 100-120°C, the time of the melt mixing is 90-120 minutes, and the inert gas is nitrogen; in step S2, the time of the melt mixing is 30-50 minutes. Compared with the prior art, the present invention has at least the following beneficial effects: The biodegradable pressure-sensitive adhesive of the present invention is prepared by combining polybutylene succinate, a biodegradable thermoplastic elastomer, a tackifying resin, a plasticizer, a mildew-proof agent, an antioxidant and an anti-aging agent in formula amounts, and specifically selecting a polycaprolactone-polylactide block copolymer with a weight-average relative molecular mass of 50,000-70,000 and a polycaprolactone phase content of 65-80% as the biodegradable thermoplastic elastomer; thus, the biodegradable pressure-sensitive adhesive can not only have excellent adhesion performance (especially excellent holding tack and peel strength), but also have excellent biodegradability, and can effectively solve the defects of weak cohesive force, poor adhesion performance and poor degradation performance existing in the existing hot-melt pressure-sensitive adhesives containing thermoplastic elastomers. Moreover, the biodegradable pressure-sensitive adhesive of the present invention also has the advantages of anti-aging and anti-mildew, stable performance, simple preparation process, and is suitable for large-scale production. Specific embodiments

[0009] In order to make the above objects, features and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with specific embodiments.

[0010] Example 1 A biodegradable pressure-sensitive adhesive of this example includes the following raw materials in parts by weight: 52 parts of polybutylene succinate; 28 parts of biodegradable thermoplastic elastomer; 23 parts of tackifying resin; 10 parts of plasticizer; 1.2 parts of mildew-proof agent; 1.5 parts of antioxidant; 0.7 part of anti-aging agent.

[0011] Among them, the biodegradable thermoplastic elastomer is a polycaprolactone-polylactide block copolymer, its weight-average relative molecular mass is 60,000, and the content of the polycaprolactone phase in the polycaprolactone-polylactide block copolymer is 76%.

[0012] Among them, the tackifying resin includes 8 parts of hydrogenated rosin glyceride, 5 parts of polycaprolactone polyol and 10 parts of polylactic acid polyol.

[0013] Among them, the plasticizer includes 6 parts of dibutyl phthalate and 4 parts of dioctyl sebacate. The mildew-proof agent is 5-chloro-2-methyl-4-isothiazolin-3-one. The antioxidant is tris(2,4-di-tert-butylphenyl) phosphite.

[0014] A preparation method of a biodegradable pressure-sensitive adhesive according to this embodiment includes the following preparation steps: Step S1: Under nitrogen protection, weigh the polybutylene succinate, biodegradable thermoplastic elastomer, tackifying resin, plasticizer, and antioxidant according to the formula amounts, and melt and mix them at 120 °C for 100 minutes.

[0015] Step S2: Then add the antioxidant and mildew-proof agent according to the formula amounts, and continue to melt and mix for 40 minutes to obtain the biodegradable pressure-sensitive adhesive of this embodiment.

[0016] Example 2 A biodegradable pressure-sensitive adhesive according to this embodiment includes the following raw materials in weight fractions: 56 parts of polybutylene succinate; 20 parts of biodegradable thermoplastic elastomer; 30 parts of tackifying resin; 10 parts of plasticizer; 1.5 parts of mildew-proof agent; 2 parts of antioxidant; 0.3 part of antioxidant.

[0017] Among them, the biodegradable thermoplastic elastomer is a polycaprolactone - polylactide block copolymer, its weight-average relative molecular mass is 50,000, and the content of the polycaprolactone phase in the polycaprolactone - polylactide block copolymer is 72%.

[0018] Among them, the tackifying resin includes 15 parts of hydrogenated rosin glyceride and 15 parts of polylactic acid polyol.

[0019] Among them, the plasticizer includes 8 parts of dibutyl phthalate and 2 parts of dioctyl phthalate. The mildew-proof agent is 5-chloro-2-methyl-4-isothiazolin-3-one. The antioxidant is bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite.

[0020] A preparation method of a biodegradable pressure-sensitive adhesive according to this embodiment includes the following preparation steps: Step S1: Under nitrogen protection, weigh the polybutylene succinate, biodegradable thermoplastic elastomer, tackifying resin, plasticizer, and antioxidant according to the formula amounts, and melt and mix them at 116 °C for 120 minutes.

[0021] Step S2: Then add the antioxidant and mildew-proof agent according to the formula amounts, and continue to melt and mix for 30 minutes to obtain the biodegradable pressure-sensitive adhesive of this embodiment.

[0022] Example 3 A biodegradable pressure-sensitive adhesive according to this embodiment includes the following raw materials in weight fractions: 50 parts of polybutylene succinate; 20 parts of degradable thermoplastic elastomer; 20 parts of tackifying resin; 6 parts of plasticizer; 0.5 part of mildew-proof agent; 0.5 part of antioxidant; 0.5 part of anti-aging agent.

[0023] Among them, the degradable thermoplastic elastomer is a polycaprolactone-polylactide block copolymer, its weight-average relative molecular mass is 70,000, and the content of the polycaprolactone phase in the polycaprolactone-polylactide block copolymer is 65%.

[0024] Among them, the tackifying resin includes 10 parts of hydrogenated rosin glyceride and 10 parts of polylactic acid polyol.

[0025] Among them, the plasticizer is dibutyl phthalate. The mildew-proof agent is copper 8-hydroxyquinoline. The antioxidant is 2,6-di-tert-butyl-p-cresol.

[0026] A preparation method of a biodegradable pressure-sensitive adhesive in this embodiment includes the following preparation steps: Step S1: Under nitrogen protection, melt and mix the polybutylene succinate, degradable thermoplastic elastomer, tackifying resin, plasticizer, and antioxidant weighed according to the formula amounts at 100 °C for 90 minutes.

[0027] Step S2: Then add the anti-aging agent and mildew-proof agent according to the formula amounts, and continue to melt and mix for 35 minutes to obtain the biodegradable pressure-sensitive adhesive of this embodiment.

[0028] Example 4 A biodegradable pressure-sensitive adhesive in this embodiment includes the following raw materials in weight fractions: 60 parts of polybutylene succinate; 30 parts of degradable thermoplastic elastomer; 26 parts of tackifying resin; 12 parts of plasticizer; 1 part of mildew-proof agent; 1.5 parts of antioxidant; 1 part of anti-aging agent.

[0029] Among them, the degradable thermoplastic elastomer is a polycaprolactone-polylactide block copolymer, its weight-average relative molecular mass is 57,000, and the content of the polycaprolactone phase in the polycaprolactone-polylactide block copolymer is 80%.

[0030] Among them, the tackifying resin includes 10 parts of hydrogenated rosin, 10 parts of hydrogenated rosin glyceride, and 6 parts of polylactic acid polyol.

[0031] Among them, the plasticizer includes 6 parts of dibutyl phthalate and 6 parts of dioctyl phthalate. The mildew preventive is 5-chloro-2-methyl-4-isothiazolin-3-one. The antioxidant is tris(2,4-di-tert-butylphenyl) phosphite.

[0032] A preparation method of a biodegradable pressure-sensitive adhesive according to this embodiment includes the following preparation steps: Step S1: Under nitrogen protection, melt and mix the polybutylene succinate, biodegradable thermoplastic elastomer, tackifying resin, plasticizer, and antioxidant weighed according to the formula amount at 105 °C for 110 minutes.

[0033] Step S2: Then add the antioxidant and mildew preventive according to the formula amount, and continue to melt and mix for 50 minutes to obtain the biodegradable pressure-sensitive adhesive of this embodiment.

[0034] Comparative Example 1 A biodegradable pressure-sensitive adhesive and its preparation method according to this comparative example both refer to Example 1, and the difference from Example 1 is that: In the biodegradable pressure-sensitive adhesive of this comparative example, the polybutylene succinate in Example 1 is replaced with the same weight of polyethylene glycol succinate, and the remaining raw material formula and preparation process both refer to Example 1.

[0035] Comparative Example 2 A biodegradable pressure-sensitive adhesive and its preparation method according to this comparative example refer to Example 1, and the difference from Example 1 is that: In the biodegradable pressure-sensitive adhesive of this comparative example, the polycaprolactone-polylactide block copolymer with a weight-average relative molecular mass of 60,000 and a polycaprolactone phase content of 76% in Example 1 is replaced with the same weight of a polycaprolactone-polylactide block copolymer with a weight-average relative molecular mass of 75,000 and a polycaprolactone phase content of 60%, and the remaining raw material formula and preparation process both refer to Example 1.

[0036] Performance Test The biodegradable pressure-sensitive adhesives of Examples 1 to 4 and Comparative Examples 1 to 2 were respectively subjected to performance tests, and the test results are shown in Table 1 below.

[0037] (1) The biodegradable pressure-sensitive adhesive was hot-melt coated on a BOPET substrate with a coating thickness of 25 μm, and then the initial tack, holding tack, and 180° peel strength were respectively tested; among them, the initial tack was tested according to the regulation of the inclined plane with an inclination of 30° in Method A of Standard GB / T4852-2002, the 180° peel strength was tested according to the regulation of Method 1 in Standard GB / T2792-2014, and the holding tack was tested according to Standard GB / T4851-2023.

[0038] (2)The biodegradability of the biodegradable pressure-sensitive adhesive was characterized by the composting test according to the standard GB / T 19277.1-2011, and its biodegradability was characterized by the biodegradation rate.

[0039] Table 1

[0040] Initial tack (ball number) 180° peel strength (N / mm) Holding tack (h) Biodegradation rate (%) Example 1 12 1.43 >120 91 Example 2 11 1.25 >120 88 Example 3 9 1.33 >120 85 Example 4 11 1.38 >120 90 Comparative Example 1 8 1.12 >70 85 Comparative Example 2 5 0.88 >50 80 It can be seen from Table 1 that: (1) The biodegradable pressure-sensitive adhesives of Examples 1-4 are prepared by combining polybutylene succinate, biodegradable thermoplastic elastomer, tackifying resin, plasticizer, mildew preventive, antioxidant and anti-aging agent in formula amounts, and specifically selecting a polycaprolactone-polylactide block copolymer with a weight-average relative molecular mass of 50,000-70,000 and a polycaprolactone phase content of 65-80% as the biodegradable thermoplastic elastomer; thus, the biodegradable pressure-sensitive adhesives of Examples 1-4 can not only have excellent bonding properties (especially excellent holding tack and peel strength), but also have excellent biodegradability; moreover, the biodegradable pressure-sensitive adhesive has anti-aging and anti-mildew properties, stable performance, simple preparation process and is suitable for large-scale production. Among them, the biodegradable pressure-sensitive adhesive of Example 1 has the best comprehensive performance.

[0041] (2) Compared with Example 1, when the polybutylene succinate in Comparative Example 1 is replaced with polyethylene glycol succinate, the bonding performance of the biodegradable pressure-sensitive adhesive in Comparative Example 1 becomes worse, especially in terms of holding tack and peel strength.

[0042] (3) Compared with Example 1, when the polycaprolactone-polylactide block copolymer with a weight-average relative molecular mass of 60,000 and a polycaprolactone phase content of 76% in Comparative Example 2 is replaced with a polycaprolactone-polylactide block copolymer with a weight-average relative molecular mass of 75,000 and a polycaprolactone phase content of 60%, due to the decrease in the polycaprolactone phase content, the initial tack, holding tack and peel strength of the biodegradable pressure-sensitive adhesive in Comparative Example 2 all become significantly worse, and the biodegradability also decreases.

[0043] Although the preferred embodiments of the embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications once they learn the basic creative concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present invention.

[0044] The technical solutions provided by the present invention have been introduced in detail above. Specific examples are used herein to elaborate on the principles and implementation manners of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A biodegradable pressure-sensitive adhesive, characterized in that, It comprises raw materials in the following weight fractions: 50 - 60 parts of polybutylene succinate; 20 - 30 parts of a biodegradable thermoplastic elastomer; 20 - 30 parts of a tackifying resin; 6 - 12 parts of a plasticizer; 0.5 - 1.5 parts of a mildew-proof agent; 0.5 - 2 parts of an antioxidant; 0.3 - 1 part of an anti-aging agent; wherein, the biodegradable thermoplastic elastomer is a polycaprolactone - polylactide block copolymer, its weight-average relative molecular mass is 50000 - 70000, and the content of the polycaprolactone phase in the polycaprolactone - polylactide block copolymer is 65 - 80%.

2. The biodegradable pressure-sensitive adhesive according to claim 1, wherein The weight-average relative molecular mass of the polycaprolactone - polylactide block copolymer is 60000, and the content of the polycaprolactone phase in the polycaprolactone - polylactide block copolymer is 76%.

3. The biodegradable pressure-sensitive adhesive according to claim 2, wherein It comprises raw materials in the following weight fractions: 52 parts of polybutylene succinate; 28 parts of a biodegradable thermoplastic elastomer; 23 parts of a tackifying resin; 10 parts of a plasticizer; 1.2 parts of a mildew-proof agent; 1.5 parts of an antioxidant; 0.7 part of an anti-aging agent.

4. A biodegradable pressure-sensitive adhesive according to any one of claims 1-3, characterized in that, The tackifying resin is at least one of hydrogenated rosin, hydrogenated rosin glyceride, polycaprolactone polyol, and polylactic acid polyol.

5. A biodegradable pressure-sensitive adhesive according to any one of claims 1-3, characterized in that The plasticizer is at least one of dibutyl phthalate, dioctyl phthalate, dioctyl sebacate, and liquid paraffin.

6. A biodegradable pressure-sensitive adhesive according to any one of claims 1 to 3, characterized in that, The mildew-proof agent is at least one of 2 - pyridinethiol - 1 - zinc oxide, 5 - chloro - 2 - methyl - 4 - isothiazolin - 3 - one, copper 8 - hydroxyquinoline, ammonium persulfate, and calcium phosphate.

7. A biodegradable pressure-sensitive adhesive according to any one of claims 1 to 3, characterized in that, The antioxidant is at least one of tris(2,4 - di - tert - butylphenyl) phosphite, bis(2,4 - di - tert - butylphenyl) pentaerythritol diphosphite, and 2,6 - di - tert - butyl - p - cresol.

8. A biodegradable pressure-sensitive adhesive according to any one of claims 1-3, characterized in that, The anti-aging agent is at least one of methyl 2 - hydroxybenzoate, 6 - ethoxy - 2,2,4 - trimethyl - 1,2 - dihydroquinoline, N - phenyl - 1 - naphthylamine, and N - isopropyl - N'-phenyl - p - phenylenediamine.

9. A method for preparing a biodegradable pressure-sensitive adhesive according to any one of claims 1-8, characterized in that, It comprises the following preparation steps: S1. Under the protection of an inert gas, melt and mix the polybutylene succinate, biodegradable thermoplastic elastomer, tackifying resin, plasticizer, and antioxidant weighed according to the formula amounts. 10.S2. Then add the anti-aging agent and mildew-proof agent in the formula amounts and continue to melt and mix to obtain the biodegradable pressure-sensitive adhesive.

11. The preparation method of a biodegradable pressure-sensitive adhesive according to claim 9, characterized in that, In step S1, the temperature of the melt mixing is 100 - 120 °C, the time of the melt mixing is 90 - 120 minutes, and the inert gas is nitrogen; in step S2, the time of the melt mixing is 30 - 50 minutes.

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