Biodegradable hot-melt pressure-sensitive adhesive matrix resin and preparation method thereof

Abstract

The invention discloses biodegradable hot-melt pressure-sensitive adhesive matrix resin and a preparation method thereof, and belongs to the technical field of hot-melt pressure-sensitive adhesives. The matrix resin is prepared from polycarbonate polyol, polycaprolactone and polylactic acid through three-block copolymerization. The preparation method comprises the following steps: carrying out ring opening polymerization on polycarbonate polyol and caprolactone under the action of a catalyst, then adding lactide and supplementing the catalyst, polymerizing to obtain a polycarbonate-caprolactone-lactide polymer, and further purifying to obtain the hot-melt pressure-sensitive adhesive matrix resin. By adjusting the content of each component in the three blocks, the initial adhesion, the permanent adhesion and the peel strength can be regulated and controlled. By compounding the matrix resin with a terpene tackifier and a tri-n-butyl citrate plasticizer, the hot-melt pressure-sensitive adhesive with high initial adhesion, good holding power and high peel strength can be obtained.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hot melt pressure sensitive adhesive, and particularly relates to a biodegradable hot melt pressure sensitive adhesive matrix resin and a preparation method thereof. BACKGROUND

[0002] As an article widely used in daily life, the adhesive is widely used in the fields of express package, label, etc. Although cellulose or biaxially oriented polylactic acid has been put forward as the adhesive tape substrate under the promotion of the policy, the commonly used adhesive is still mainly acrylate, polyurethane and rubber. When the adhesive tape is discarded into the environment after use, the non-degradable property of the adhesive will continuously pollute the environment. Therefore, it is of great significance to develop a biodegradable adhesive for solving the current adhesive tape pollution problem. CN107523253A provides a biodegradable pressure sensitive adhesive, but the adhesive needs to be dispersed in a solvent to prepare the adhesive tape, and the use of the solvent and the leakage in the environment will bring new pollution. CN107177339A provides a method for preparing a biodegradable adhesive based on chemical synthesis of lactide, but the performance of the adhesive still needs to be improved.

[0003] Therefore, the application provides a biodegradable hot melt pressure sensitive adhesive matrix resin and a preparation method thereof. SUMMARY

[0004] In view of the deficiencies of the prior art, the purpose of the application is to provide a biodegradable hot melt pressure sensitive adhesive matrix resin and a preparation method thereof, which solves the problems in the prior art.

[0005] In order to achieve the above-mentioned purpose, the application can be realized by the following technical scheme:

[0006] A preparation method of a biodegradable hot melt pressure sensitive adhesive matrix resin comprises the following steps:

[0007] The polycarbonate polyol is subjected to ring-opening polymerization with caprolactone under the action of a catalyst to obtain a polycarbonate-caprolactone polyol;

[0008] The lactide is mixed with the polycarbonate-caprolactone polyol, and a catalyst is supplemented to perform a polymerization reaction to obtain a polycarbonate-caprolactone-lactide polymer; and after the monomer is removed through purification, a hot melt pressure sensitive adhesive matrix resin is obtained.

[0009] Further, the polycarbonate polyol is any one of polycarbonate diol, polypropylene carbonate diol and aromatic polycarbonate diol, the number average molecular weight of the polycarbonate polyol is 4000-40000 Da, and the caprolactone is epsilon-caprolactone monomer.

[0010] Further, the mass of the polycarbonate polyol accounts for 5-30% of the sum of the mass of the caprolactone and the lactide; the mass ratio of the caprolactone and the lactide is (2:8)-(8:2).

[0011] Further, the catalyst is one of stannous octoate, stannous chloride and stannous benzoate or a combination of two.

[0012] Further, the lactide is one of L-lactide, D-lactide and meso-lactide or a combination of several.

[0013] Further, the process of the polymerization reaction comprises pre-polymerization at 120-160℃ and polymerization at 180-210℃.

[0014] Further, the purification method comprises removing the insufficiently reacted monomers by a vacuum pump after melting the base resin, the melting temperature being 180-220℃ and the vacuum degree being 20-500Pa.

[0015] A hot-melt pressure-sensitive adhesive base resin is prepared by the above method.

[0016] The above hot-melt pressure-sensitive adhesive base resin is used in the preparation of a hot-melt pressure-sensitive adhesive.

[0017] Compared with the prior art, the present application has the following advantages:

[0018] (1) The present application adjusts the product performance of the biodegradable hot-melt pressure-sensitive adhesive base resin from the structure by adopting the block copolymerization of the polycarbonate polyol, the caprolactone and the lactide; the polycarbonate polyol is introduced to improve the crystallinity of the polycaprolactone structure and improve the comprehensive performance of the pressure-sensitive adhesive base resin; the raw materials used to synthesize the polymer, the monomer or the base resin obtained by the copolymerization are all biodegradable polymers which can be degraded under the industrial composting conditions and the final product is carbon dioxide and water.

[0019] (2) The introduction of the polycarbonate polyol reduces the crystallization behavior of the base resin and improves the initial tack of the product; the comprehensive ring initial tack under the optimal conditions reaches 12N, the peel strength is ≥0.6N / mm and the holding tack is ≥24h. DETAILED DESCRIPTION

[0020] The technical solutions of the present application will be described clearly and completely in combination with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0021] Example 1

[0022] Poly(ethylene carbonate) polyol (5 g, number average molecular weight 20000 Da), caprolactone (20 g) were weighed into a reaction flask which was treated with anhydrous and oxygen-free. The reaction flask was repeatedly treated with vacuum and nitrogen three times using a double-gas dispenser. After the reaction flask was sealed, it was placed in an oil bath. When the raw materials were completely melted, 0.04 wt% of stannous octoate was injected into the reaction flask using a syringe. After the reaction was carried out at 130 °C for 12 h, the temperature of the reaction flask was increased to 180 °C, and the reaction flask was connected to a vacuum pump for devolatilization treatment to remove unreacted monomers, thereby obtaining poly(ethylene carbonate)-poly(caprolactone) polyol.

[0023] Further, lactide (80 g) was weighed into the above reaction flask. After being heated to 150 °C to completely melt, 0.04 wt% of stannous octoate was injected into the reaction flask using a syringe. After the rotor in the reaction flask was completely unable to rotate, the temperature was increased to 180 °C for 3 h of continuous polymerization. The temperature of the reaction flask was increased to 200 °C, and the reaction flask was connected to a vacuum pump for devolatilization treatment to remove unreacted monomers, thereby obtaining poly(ethylene carbonate)-poly(caprolactone)-poly(lactide) matrix resin.

[0024] The matrix resin was further compounded with tackifier and plasticizer at a ratio of 4:4:2, and then coated on a polylactic acid substrate by a hot melt machine. After being placed at room temperature for 24 h, it was used for cutting test to mainly test the loop tack force, peel force and hold tack force.

[0025] Example 2

[0026] Poly(propylene carbonate) polyol (5 g) and caprolactone (20 g) were weighed into a reaction flask which was treated with anhydrous and oxygen-free. The reaction flask was repeatedly treated with vacuum and nitrogen three times using a double-gas dispenser. After the reaction flask was sealed, it was placed in an oil bath. When the raw materials were completely melted, 0.04 wt% of stannous octoate was injected into the reaction flask using a syringe. After the reaction was carried out at 130 °C for 12 h, the temperature of the reaction flask was increased to 180 °C, and the reaction flask was connected to a vacuum pump for devolatilization treatment to remove unreacted monomers, thereby obtaining poly(propylene carbonate)-poly(caprolactone) polyol.

[0027] Further, lactide (80 g) was weighed into the above reaction flask. After being heated to 150 °C to completely melt, 0.04 wt% of stannous octoate was injected into the reaction flask using a syringe. After the rotor in the reaction flask was completely unable to rotate, the temperature was increased to 180 °C for 3 h of continuous polymerization. The temperature of the reaction flask was increased to 200 °C, and the reaction flask was connected to a vacuum pump for devolatilization treatment to remove unreacted monomers, thereby obtaining poly(ethylene carbonate)-poly(caprolactone)-poly(lactide) matrix resin.

[0028] The sample is further compounded with tackifier, plasticizer according to the ratio of 4:4:2, and then coated on the polylactic acid substrate by a hot melt machine. After being placed at room temperature for 24 h, the sample is used for cutting test to mainly test the loop initial tack, peel force and holding tack.

[0029] Example 3

[0030] The aromatic polycarbonate polyol 5 g and caprolactone 20 g are weighed and added to a reaction bottle treated with anhydrous and anaerobic. After three times of vacuumizing and nitrogen charging by a double exhaust gas distributor, the reaction bottle is sealed and placed in an oil bath. After the raw materials are completely melted, 0.04 wt% of stannous octoate catalyst is injected into the reaction bottle by a syringe. After being reacted at 130°C for 12 h, the temperature of the reaction bottle is increased to 180°C and connected to a vacuum pump for devolatilization treatment to remove unreacted monomers, thereby obtaining a polycarbonate-poly caprolactone polyol.

[0031] Further, 80 g of lactide is weighed and added to the above reaction bottle. After being heated to 150°C to completely melt, 0.04% of stannous octoate is injected into the reaction bottle by a syringe. After the rotor in the reaction bottle is completely unable to rotate, the temperature is increased to 180°C and the polymerization is continued for 3 h. The temperature of the reaction bottle is increased to 200°C and connected to a vacuum pump for devolatilization treatment to remove unreacted monomers, thereby obtaining an aromatic polycarbonate-poly caprolactone-poly lactide matrix resin.

[0032] The sample is further compounded with tackifier, plasticizer according to the ratio of 4:4:2, and then coated on the polylactic acid substrate by a hot melt machine. After being placed at room temperature for 24 h, the sample is used for cutting test to mainly test the loop initial tack, peel force and holding tack.

[0033] Example 4

[0034] As in Example 1, the polycarbonate polyol is changed to 30 g, and other conditions remain unchanged. The sample is further compounded with tackifier, plasticizer, and then coated on the polylactic acid substrate by a hot melt machine. After being placed at room temperature for 24 h, the sample is used for cutting test to mainly test the loop initial tack, peel force and holding tack.

[0035] Example 5

[0036] As in Example 1, the caprolactone is changed to 50 g, and the lactide is changed to 50 g, and other conditions remain unchanged. The sample is further compounded with tackifier, plasticizer, and then coated on the polylactic acid substrate by a hot melt machine. After being placed at room temperature for 24 h, the sample is used for cutting test to mainly test the loop initial tack, peel force and holding tack.

[0037] Example 6

[0038] As example 1, change caprolactone to 80g, lactide to 20g, other conditions remain the same. The sample is further compounded with tackifier, plasticizer, and coated on polylactic acid substrate by hot melt machine, after 24h at room temperature, used for cutting test, mainly test its initial loop tack, peel force and hold tack.

[0039] Example 7

[0040] As example 1, change polycarbonate polyol number average molecular weight to 4000Da raw material, other conditions remain the same. The sample is further compounded with tackifier, plasticizer, and coated on polylactic acid substrate by hot melt machine, after 24h at room temperature, used for cutting test, mainly test its initial loop tack, peel force and hold tack.

[0041] Example 8

[0042] As example 1, change polycarbonate polyol number average molecular weight to 40000Da raw material, other conditions remain the same. The sample is further compounded with tackifier, plasticizer, and coated on polylactic acid substrate by hot melt machine, after 24h at room temperature, used for cutting test, mainly test its initial loop tack, peel force and hold tack.

[0043] Comparative example 1

[0044] Take caprolactone 20g, add to the reaction bottle after anhydrous and anaerobic treatment, use double exhaust gas distributor to vacuum, nitrogen repeatedly handle three times after the reaction bottle is sealed into the oil bath, after the raw material is completely melted, use the syringe to take 0.04wt% of stannous octoate and 0.3wt% of 1,4-butanediol as initiator into the reaction bottle. After 12h at 130℃, the temperature of the reaction bottle is raised to 180℃, connected to the vacuum pump for devolatilization treatment, remove the unreacted monomer, get poly caprolactone polyol (OH-PCL-OH).

[0045] Take lactide 80g, add to the above reaction bottle, heat to 150℃ completely melted, use the syringe to take 0.04wt% of stannous octoate into the reaction bottle, after the rotor in the reaction bottle is completely not movable, the temperature is raised to 180℃ for 3h, the temperature of the reaction bottle is raised to 200℃, connected to the vacuum pump for devolatilization treatment, remove the unreacted monomer, get poly caprolactone-poly lactide block copolymer.

[0046] The sample is further compounded with tackifier, plasticizer, and coated on polylactic acid substrate by hot melt machine, after 24h at room temperature, used for cutting test, mainly test its initial loop tack, peel force and hold tack.

[0047] Comparative example 2

[0048] Take polycarbonate polyol 5 g, lactide 80 g, add to the reaction bottle, heat to 150 ℃ completely melt, then take 0.04 wt% of stannous octoate of the raw material into the reaction bottle, after the rotor in the reaction bottle is completely not movable, the temperature is raised to 180 ℃, and the polymerization is continued for 3 h, the temperature of the reaction bottle is raised to 200 ℃, and is connected to a vacuum pump for devolatilization treatment to remove unreacted monomers, and a polycarbonate-polylactide block copolymer is obtained.

[0049] The sample is further compounded with tackifier and plasticizer according to a ratio of 4:4:2, and then coated on a polylactic acid substrate by a hot melt machine. After being placed at room temperature for 24 h, it is used for cutting test to mainly test the loop initial tack, peel strength and holding tack.

[0050] Experimental test

[0051] The hot melt pressure sensitive adhesive prepared in Examples 1-8 and Comparative Examples 1-2, and commercial adhesive tapes 1 (3M transparent adhesive tape) and 2 (Huaxian EMS adhesive tape) are respectively tested for loop initial tack, peel strength and holding tack; the test standards are as follows:

[0052] 1) Loop initial tack: the initial tack of the biodegradable adhesive tape is detected according to the national standard GB / T31125-2014 (Adhesive Tape Initial Tack Test Method Loop Method).

[0053] 2) Peel strength test: the peel strength of the biodegradable adhesive tape is detected according to the national standard GB / T2792-2014.

[0054] 3) Holding tack: the holding tack of the biodegradable adhesive tape is detected according to the national standard GB / T 4851-2014 (Adhesive Tape Holding Tack Test Method).

[0055] The test results are shown in Table 1 below:

[0056] Table 1 Performance test results of hot melt pressure sensitive adhesive

[0057] Example Loop tack (N) Peel strength (N / mm) Hold tack (h) Example 1 By 0.51 ＞24 Example 2 6 0.42 ＞24 Example 3 5 0.35 ＞24 Example 4 9 0.42 ＞24 Example 5 12 0.60 ＞24 Example 6 15 0.31 ＞24 Example 7 6 0.60 ＞24 Example 8 9 0.40 ＞24 Comparative Example 1 3 0.25 >24 Comparative Example 2 4 0.22 >24 Commercial adhesive 1 6 0.30 >24 Commercial adhesive 2 7 0.37 >24

[0058] By analyzing Table 1, it can be seen that:

[0059] 1) By comparing the test results of Examples 1-3 and Comparative Example 1, it can be seen that the introduction of polyethylene carbonate is helpful to improve the initial tack, and among the three polycarbonates, polyethylene carbonate has better effect, so the ratio of polycarbonate polyol to caprolactone and lactide in the subsequent adjustment is taken as a reference.

[0060] 2) By comparing the test results of Example 1, 4 and Comparative Example 2, it can be seen that: the increase of polycarbonate is meaningful for improving the initial adhesion, but the peeling strength will decrease to a certain extent, so the polycarbonate proportion in Example 1 is still selected for further study of the suitable proportion of caprolactone and lactide;

[0061] 3) By comparing the test results of Example 1, 5 and 6, and Comparative Example 3, it can be seen that: the proportion of caprolactone and lactide is also important for the regulation of overall performance. From the data, the comprehensive performance is the best when the mass ratio of caprolactone to lactide is 1:1;

[0062] 4) By comparing Example 1, 7 and 8: the change of polycarbonate polyol molecular weight mainly affects the initial adhesion and peeling strength, and the overall performance of the matrix resin can be optimized by adjusting the molecular weight of polycarbonate polyol;

[0063] 5) By comparing Examples 1-8 and commercially available pressure-sensitive adhesive tapes (commercial tapes 1 and 2), it can be found that the adhesives prepared by using the triblock copolymer as the matrix resin all reach the performance of the currently commercial pressure-sensitive adhesive tapes.

[0064] In the description of the present specification, the description referring to the terms "one embodiment", "an example", "a specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0065] The basic principles, main features and advantages of the present application are shown and described above. It should be understood by those skilled in the art that the present application is not limited by the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application.

Claims

1. A process for the preparation of a biodegradable hot-melt pressure sensitive adhesive matrix resin, characterized in that, The method comprises the following steps: The polycarbonate polyol is subjected to ring-opening polymerization with caprolactone under the action of a catalyst to obtain a polycarbonate-caprolactone polyol; The lactide is mixed with the polycarbonate-caprolactone polyol and a catalyst is supplemented to perform a polymerization reaction to obtain a polycarbonate-caprolactone-lactide polymer; and after purification to remove monomers, a hot-melt pressure-sensitive adhesive matrix resin is obtained.

2. The method for preparing a biodegradable hot-melt pressure-sensitive adhesive matrix resin according to claim 1, characterized in that, The polycarbonate polyol is any one of polycarbonate polyol, polypropylene carbonate polyol and aromatic polycarbonate polyol.

3. The method for preparing a biodegradable hot-melt pressure-sensitive adhesive matrix resin according to claim 1, characterized in that, The number average molecular weight of the polycarbonate polyol is 4000-40000 Da, and the caprolactone is ε-caprolactone monomer.

4. The method for preparing a biodegradable hot-melt pressure-sensitive adhesive matrix resin according to claim 1, characterized in that, The mass of the polycarbonate polyol accounts for 5-30% of the sum of the masses of the caprolactone and the lactide; and the mass ratio of the caprolactone to the lactide is (2:8) to (8:2).

5. The method for preparing a biodegradable hot-melt pressure-sensitive adhesive matrix resin according to claim 1, characterized in that, The catalyst is one or a combination of two of stannous octoate, stannous chloride and stannous benzoate.

6. The method for preparing a biodegradable hot-melt pressure-sensitive adhesive matrix resin according to claim 1, characterized in that, The lactide is one or a combination of two of L-lactide, D-lactide and meso-lactide.

7. The method for preparing a biodegradable hot-melt pressure-sensitive adhesive matrix resin according to claim 1, characterized in that, The polymerization process comprises pre-polymerization at 120-160 ℃ and then polymerization at 180-210 ℃.

8. The method for preparing a biodegradable hot-melt pressure-sensitive adhesive matrix resin according to claim 1, characterized in that, The purification method is that after the matrix resin is melted, the monomers that are not fully reacted are removed by the action of a vacuum pump, the melting temperature is 180-220 ℃, and the vacuum degree is 20-500 Pa.

9. A hot melt pressure sensitive adhesive base resin characterized by, The method is prepared by using the preparation method of any one of claims 1-8.

10. Use of the hot-melt pressure-sensitive adhesive matrix resin of claim 9 in the preparation of a hot-melt pressure-sensitive adhesive.