Degradable hot melt adhesive and preparation method thereof

Abstract

The invention discloses a degradable hot melt adhesive and a preparation method thereof, and relates to the technical field of hot melt adhesives. A degradable hot melt adhesive comprises 50-64 parts of matrix resin, 18-24 parts of tackifying resin, 3.2-4.5 parts of polyethylene wax, 1.5-2.4 parts of a biological wax material, 10-16 parts of modified starch particles and 0.8-1.2 parts of an antioxidant, the matrix resin comprises EVA resin and PHBV resin, and the tackifying resin comprises C5 hydrogenated petroleum resin and rosin polyol ester. The biological wax material comprises any one of soybean wax, beeswax or palm wax. The EVA resin and the PHBV resin are used as matrix resin, and a plurality of bio-based additives are matched, so that the degradation efficiency of the hot melt adhesive is greatly improved, the hot melt adhesive can be fully degraded or hydrolyzed by microorganisms in the environment after being discarded, and the hot melt adhesive has certain environmental protection property.

Description

Technical Field

[0001] The present invention relates to the technical field of hot melt adhesives, and in particular to a degradable hot melt adhesive and a preparation method thereof. Background Art

[0002] Hot melt adhesive is a plastic adhesive. Its physical state changes with temperature within a certain temperature range, while its chemical properties remain unchanged. It is non-toxic and odorless, and is an environmentally friendly chemical product. It can be used to stick solids such as wood, plastic, fiber, fabric, metal, furniture, lampshades, leather, handicrafts, toys, electronics, electrical components, paper products, ceramics, and pearl cotton packaging. It is used in large quantities and is widely used.

[0003] However, due to its structural characteristics, conventional hot melt adhesives are highly resistant to microorganisms and are difficult to be fully degraded or hydrolyzed by microorganisms in the environment. As a result, hot melt adhesives will remain in the environment for a long time after being discarded, causing increasingly prominent environmental problems. Therefore, the production of environmentally friendly hot melt adhesives with good bonding effects and biodegradability has become an important development direction for the adhesive industry. Summary of the invention

[0004] In order to enable the hot melt adhesive to be fully degraded or hydrolyzed by microorganisms in the environment and improve the environmental friendliness of the hot melt adhesive, the present application provides a degradable hot melt adhesive and a preparation method thereof.

[0005] In the first aspect, the present application provides a degradable hot melt adhesive using the following technical solution: A degradable hot melt adhesive comprises the following raw materials in parts by weight: Base resin: 50-64 parts; Tackifying resin: 18-24 parts; Polyethylene wax: 3.2-4.5 parts; Biological wax: 1.5-2.4 parts; Modified starch granules: 10-16 parts; Antioxidant: 0.8-1.2 parts; The base resin comprises EVA resin and PHBV resin mixed and compounded in a weight ratio of 1: (1-1.5), the tackifying resin comprises C5 hydrogenated petroleum resin and rosin polyol ester mixed and compounded in a weight ratio of 1: (2-5), the modified starch particles are thermoplastic starch modified by plasticization, and the biowax comprises any one of soybean wax, beeswax or palm wax.

[0006] By adopting the above technical scheme, using EVA resin and PHBV resin as the base resin, and combining with a variety of bio-based additives, the prepared hot melt adhesive not only has good bonding properties, but also has good degradability and high degradation efficiency. Therefore, the hot melt adhesive can be fully degraded or hydrolyzed by microorganisms in the environment after being discarded, which is beneficial to improving the environmental protection of the hot melt adhesive.

[0007] Optionally, the HV content in the PHBV resin is 9%-16% (mol).

[0008] The adoption of the above technical solution is beneficial to improving the cohesive strength and degradation efficiency of the matrix resin, thereby improving the bonding strength and degradation performance of the hot melt adhesive.

[0009] Optionally, the rosin polyol ester is one of rosin glycerol ester and rosin pentaerythritol ester.

[0010] By adopting the above technical scheme, rosin glycerol ester and rosin pentaerythritol ester are both alcohol esterified modified rosin resins, which can not only be used as tackifying resins to improve the bonding properties of hot melt adhesives, but also have good biodegradability, which is beneficial to improving the degradation properties of hot melt adhesives and improving the degradation efficiency of hot melt adhesives.

[0011] Optionally, the rosin polyol ester is rosin pentaerythritol ester, and the C5 hydrogenated petroleum resin and the rosin pentaerythritol ester are mixed in a weight ratio of 1:(2-3).

[0012] By adopting the above technical solution, compared with rosin glycerol ester, rosin pentaerythritol ester has higher molecular weight and thermal stability, which is beneficial to improving the cohesive strength and bonding performance of the hot melt adhesive and can provide better comprehensive performance for the hot melt adhesive.

[0013] Optionally, the biological wax material is beeswax.

[0014] By adopting the above technical solution, beeswax has good viscosity, adhesion and hardness, and the hardness is moderate, which is beneficial to improving the cohesive strength of the hot melt adhesive and further improving the bonding performance of the hot melt adhesive.

[0015] Optionally, the plasticization modification of the modified starch particles comprises the following steps: First, corn starch and water are fully mixed at a ratio of 1:1, and then a composite plasticizer composed of glycerol, formamide and urea is added. The mixture is kept at room temperature and fully stirred at a speed of 3000-3500r / min, and then allowed to stand for 24-48 hours. The modified starch particles are obtained by extrusion and cooling.

[0016] By adopting the above technical scheme, corn starch is modified by using a composite plasticizer made of a mixture of glycerol, formamide and urea, so that corn starch can be modified into a thermoplastic starch, thereby effectively improving the melting point of the modified starch particles and imparting a certain thermoplasticity, which is conducive to making the modified starch particles suitable for high-temperature hot melt adhesive systems and not easily gelatinized due to high temperature.

[0017] Optionally, in the composite plasticizer, the mixing weight ratio of the glycerol, the formamide and the urea is 1:(0.4-0.6):(0.4-0.6), and the mixing weight ratio of the corn starch to the composite plasticizer is 1:(0.2-0.25).

[0018] By adopting the above technical scheme, when the mixing weight ratio of glycerol, formamide and urea is within the range of 1:(0.4-0.6):(0.4-0.6) and the mixing weight ratio of corn starch and composite plasticizer is within the range of 1:(0.2-0.25), the composite plasticizer can fully plasticize and modify the corn starch, thereby facilitating the acquisition of modified starch particles suitable for use in hot melt adhesives.

[0019] Optionally, the antioxidant is selected from antioxidant 1010 and antioxidant 168 mixed in a weight ratio of 1:(2-3).

[0020] By adopting the above technical solution, a certain synergistic effect can be produced between the antioxidant 1010 and the antioxidant 168, which is beneficial to improving the antioxidant property of the hot melt adhesive and preventing the hot melt adhesive from turning yellow or reducing its viscosity due to oxidation after being placed for a long time.

[0021] In the second aspect, the present application provides a method for preparing a degradable hot melt adhesive using the following technical solution: A method for preparing a degradable hot melt adhesive comprises the following steps: S1, firstly, 10% of the base resin is fully mixed with polyethylene wax, biowax and antioxidant at a mixing temperature of 145-160° C., and then the remaining base resin is added, and the mixture is fully stirred to obtain a first mixture; S2, lowering the mixing temperature to 125-135° C., then adding the tackifying resin and the modified starch granules, and continuing stirring for 20-30 minutes to obtain a second mixture; S3, subjecting the second mixture to vacuum exhaust treatment, and then melting and extruding the second mixture, and rapidly drawing it to a circulating cooling water tank with a cooling solution temperature not higher than 5° C. for cooling, and then cutting and drying, thereby obtaining a degradable hot melt adhesive.

[0022] By adopting the above technical solution, the mixing temperature is lowered when mixing the tackifying resin and the modified starch particles, which is beneficial to reducing the impact of high-temperature melt mixing on the tackifying resin and the modified starch particles, preventing the tackifying resin from yellowing and the modified starch particles from gelatinizing at high temperature, and improving the appearance performance of the hot melt adhesive; and quickly cooling the hot melt adhesive after extrusion can not only quickly shape the hot melt adhesive, but also prevent the hot melt adhesive from crystallizing, thereby reducing the impact on the transparency and other properties of the product. Secondly, the preparation method of the degradable hot melt adhesive is simple, which is conducive to subsequent mass production.

[0023] In summary, the technical solution of this application has at least one of the following beneficial effects: 1. By using EVA resin and PHBV resin as the base resin and combining with a variety of bio-based additives, the degradation efficiency of the hot melt adhesive is greatly improved, which is conducive to the hot melt adhesive being fully degraded or hydrolyzed by microorganisms in the environment after being discarded, and has a certain degree of environmental protection. DETAILED DESCRIPTION

[0024] The present application is further described in detail below with reference to the preparation examples, embodiments and comparative examples of the accompanying drawings.

[0025] Preparation Example [Preparation Example 1] A modified starch granule comprises the following preparation steps: First, 20 kg of corn starch and 20 kg of water were fully stirred, and then a composite plasticizer consisting of 5 kg of glycerol, 0.25 kg of formamide and 0.25 kg of urea was added, and the mixture was fully stirred at a speed of 3000 r / min for 20 minutes, and then allowed to stand for 24 hours, and then extruded and cooled to granulate to obtain modified starch granules.

[0026] [Preparation Example 2] A modified starch granule comprises the following preparation steps: First, 20 kg of corn starch and 20 kg of water were fully stirred, and then a composite plasticizer composed of 4 kg of glycerol, 0.16 kg of formamide and 0.16 kg of urea was added, and the mixture was fully stirred at a speed of 3500 r / min for 20 minutes, and then allowed to stand for 48 hours, and then extruded and cooled to granulate to obtain modified starch granules. Example

[0027] [Example 1] A degradable hot melt adhesive comprises the following raw materials: 50 kg of base resin, 24 kg of tackifying resin, 3.2 kg of polyethylene wax, 2.4 kg of biological wax, 16 kg of modified starch particles, 0.4 kg of antioxidant 1010 and 0.8 kg of antioxidant 168.

[0028] In this embodiment, the base resin is a mixture of EVA resin and PHBV resin in a weight ratio of 1:1, that is, the addition amount of EVA resin is 25kg, and the addition amount of PHBV resin is 25kg. Specifically, the EVA resin is Taiwan Taiju EVAUE639-04, in which the VA content of this grade of EVA resin is 28 and the MI value is 150, and the PHBV resin is a PHBV resin with an HV content of 9%.

[0029] In this embodiment, the tackifying resin is a mixture of C5 hydrogenated petroleum resin and rosin glycerol ester in a ratio of 1:2, that is, the added amount of C5 hydrogenated petroleum resin is 8 kg, and the added amount of rosin glycerol ester is 16 kg.

[0030] In this embodiment, the biological wax material is soybean wax, and the modified starch particles are modified starch particles prepared in [Preparation Example 1].

[0031] A method for preparing a degradable hot melt adhesive comprises the following steps: S1, firstly, 10% of the base resin is fully mixed with the polyethylene wax, the biowax material and the antioxidant at a mixing temperature of 145° C., and then the remaining base resin is added, and the mixture is fully stirred to obtain a first mixture; S2, lowering the mixing temperature to 125° C., then adding the tackifying resin and the modified starch granules, and continuing stirring for 20 minutes to obtain a second mixture; S3, subjecting the second mixture to vacuum exhaust treatment, and then melting and extruding the second mixture, and rapidly drawing it to a circulating cooling water tank with a cooling solution temperature of 5° C. for cooling, and then cutting and drying, thereby obtaining a degradable hot melt adhesive.

[0032] The cooling solution includes 10% anti-adhesive liquid and 90% deionized water.

[0033] [Example 2] A degradable hot melt adhesive comprises the following raw materials: 64 kg of base resin, 18 kg of tackifying resin, 4.5 kg of polyethylene wax, 1.5 kg of biological wax, 10 kg of modified starch particles, 0.2 kg of antioxidant 1010 and 0.6 kg of antioxidant 168.

[0034] In this embodiment, the matrix resin is a mixture of EVA resin and PHBV resin in a weight ratio of 1:1.5, that is, the addition amount of EVA resin is 25.6kg, and the addition amount of PHBV resin is 38.4kg. Specifically, the EVA resin is Taiwan Taiju EVA UE639-04, in which the VA content of the EVA resin is 28 and the MI value is 150, and the PHBV resin is a PHBV resin with an HV content of 16%.

[0035] In this embodiment, the tackifying resin is a mixture of C5 hydrogenated petroleum resin and rosin glycerol ester in a ratio of 1:5, that is, the added amount of C5 hydrogenated petroleum resin is 3 kg, and the added amount of rosin glycerol ester is 15 kg.

[0036] In this embodiment, the biological wax material is soybean wax, and the modified starch particles are modified starch particles prepared in [Preparation Example 2].

[0037] A method for preparing a degradable hot melt adhesive comprises the following steps: S1, firstly, 10% of the base resin is fully mixed with the polyethylene wax, the biowax material and the antioxidant at a mixing temperature of 160° C., and then the remaining base resin is added, and the mixture is fully stirred to obtain a first mixture; S2, lowering the mixing temperature to 135° C., then adding the tackifying resin and the modified starch granules, and continuing stirring for 30 minutes to obtain a second mixture; S3, subjecting the second mixture to vacuum exhaust treatment, and then melting and extruding the second mixture, and rapidly drawing it to a circulating cooling water tank with a cooling solution temperature of 5° C. for cooling, and then cutting and drying, thereby obtaining a degradable hot melt adhesive.

[0038] The cooling solution includes 10% anti-adhesive liquid and 90% deionized water.

[0039] [Example 3] A degradable hot melt adhesive, which differs from [Example 1] in that the proportions of EVA resin and PHBV resin in the base resin are different.

[0040] In this embodiment, the matrix resin is a mixture of EVA resin and PHBV resin in a weight ratio of 1:0.6, that is, the added amount of EVA resin is 31.25 kg, and the added amount of PHBV resin is 18.75 kg.

[0041] [Example 4] A degradable hot melt adhesive, which differs from [Example 1] in that the proportions of EVA resin and PHBV resin in the base resin are different.

[0042] In this embodiment, the base resin is a mixture of EVA resin and PHBV resin in a weight ratio of 1:1.5, that is, the added amount of EVA resin is 20 kg, and the added amount of PHBV resin is 30 kg.

[0043] [Example 5] A degradable hot melt adhesive, which differs from [Example 1] in that the PHBV resin in the base resin is different.

[0044] In this embodiment, the PHBV resin is a PHBV resin with an HV content of 12%.

[0045] [Example 6] A degradable hot melt adhesive, which differs from [Example 1] in that the PHBV resin in the base resin is different.

[0046] In this embodiment, the PHBV resin is a PHBV resin with an HV content of 16%.

[0047] [Example 7] A degradable hot melt adhesive, which differs from [Example 6] in that the tackifying resin is different.

[0048] In this embodiment, the tackifying resin is a mixture of C5 hydrogenated petroleum resin and rosin glycerol ester in a ratio of 1:3, that is, the added amount of C5 hydrogenated petroleum resin is 6 kg, and the added amount of rosin glycerol ester is 18 kg.

[0049] [Example 8] A degradable hot melt adhesive, which differs from [Example 6] in that the tackifying resin is different.

[0050] In this embodiment, the tackifying resin is a mixture of C5 hydrogenated petroleum resin and rosin pentaerythritol ester in a ratio of 1:2, that is, the added amount of C5 hydrogenated petroleum resin is 8 kg, and the added amount of rosin pentaerythritol ester is 16 kg.

[0051] [Example 9] A degradable hot melt adhesive, which differs from [Example 6] in that the tackifying resin is different.

[0052] In this embodiment, the tackifying resin is a mixture of C5 hydrogenated petroleum resin and rosin pentaerythritol ester in a ratio of 1:3, that is, the added amount of C5 hydrogenated petroleum resin is 6 kg, and the added amount of rosin pentaerythritol ester is 18 kg.

[0053] [Example 10] A biodegradable hot melt adhesive, which differs from [Implementation 9] in that the biowax material is different.

[0054] In this embodiment, the biological wax material is replaced by beeswax in equal amounts.

[0055] [Example 11] A degradable hot melt adhesive, which differs from [Example 9] in that the biowax material is different.

[0056] In this example, the biowax was replaced by palm wax in equal amounts.

[0057] Comparative Example [Comparative Example 1] A hot melt adhesive is selected from the common EVA system plate edge sealing hot melt adhesive on the market, and specifically Henkel KS3925 edge sealing hot melt adhesive is selected.

[0058] [Comparative Example 2] A hot melt adhesive, which differs from [Example 1] in that no biological wax is added.

[0059] In this comparative example, the biowax was replaced by PE wax in equal amounts.

[0060] [Comparative Example 3] A hot melt adhesive, which differs from [Example 1] in that modified starch particles are not added.

[0061] In this comparative example, the modified starch granules were replaced by corn starch in equal amounts.

[0062] Performance test data 1. Degradation performance test: The hot melt adhesives prepared in each embodiment and comparative example were uniformly coated on release paper, and pressed into hot melt adhesive sheets with a thickness of 0.3 mm by a hot press, and then placed in an environmental box with an ambient temperature of 25°C and a humidity of 50%Rh for full curing for 72 hours. The sheets were uniformly cut into 50mm×50mm sizes and weighed, and then buried in the same piece of moist soil with a burial depth of 100mm. The soil was dug out regularly, thoroughly cleaned and dried, and then weighed. The remaining mass percentage (%) of the hot melt adhesive sheet was calculated and recorded.

[0063] 2. Bond strength test: The test was carried out with reference to GB / T 7124-2008 Determination of tensile shear strength of adhesives (rigid material to rigid material), wherein pine wood board was selected as the bonding material, and the tensile shear strength (MPa) and bonding failure type of the hot melt adhesive prepared in each embodiment and comparative example were recorded.

[0064] Table 1 Degradation performance test data of hot melt adhesive Table 2 Hot melt adhesive bonding performance test data Combining Example 1 with Comparative Example 1 and the data in Tables 1 and 2, it can be seen that compared with conventional EVA edge-sealing hot melt adhesives, the hot melt adhesive prepared in Example 1 using EVA resin and PHBV resin as base resins and combined with a variety of bio-based additives exhibits excellent degradability and bonding properties. It not only has a high degradation efficiency in the natural environment and can be degraded to less than 40% of the original mass within 360 days, but also has good bonding strength when used for bonding polar materials.

[0065] Combining Example 1 with Examples 3-6 and the data in Tables 1 and 2, it can be seen that as the proportion of PHBV resin in the matrix resin gradually increases, the degradation efficiency of the prepared hot melt adhesive gradually increases, but the bonding strength shows a trend of gradually decreasing. This may be because PHBV resin is a bio-based biodegradable polyester, which has better biodegradability and biocompatibility than EVA resin. Therefore, as the proportion of PHBV resin in the matrix resin increases, the matrix resin degrades faster in the soil. However, since the bonding performance of PHBV resin itself is low, after mixing with EVA resin, it will directly affect the bonding performance of the matrix resin, thereby reducing the bonding strength of the hot melt adhesive to various materials.

[0066] Secondly, as the HV (hydroxyvaleric acid) content in the PHBV resin increases, the bonding strength of the hot melt adhesive increases significantly, and the degradation efficiency of the hot melt adhesive also increases slightly. This may be because the HV segment plays the role of a soft segment in PHBV, and as the HV content increases, the soft segment may interfere with the orderly arrangement of the PHBV resin molecular segments, causing the crystallinity of the PHBV resin to decrease, thereby increasing the elastic modulus, breaking stress and degradability of the PHBV resin, which is beneficial to improving the cohesive strength and degradation efficiency of the matrix resin, and improving the bonding strength and degradation performance of the hot melt adhesive.

[0067] Combined with Examples 6-9 and the data in Tables 1 and 2, it can be seen that as the proportion of rosin glycerol ester in the tackifying resin increases, the degradation efficiency and bonding strength of the hot melt adhesive are slightly improved; and when the rosin glycerol ester in the tackifying resin is replaced by rosin pentaerythritol ester in equal amounts, the hot melt adhesive has better bonding performance. This may be because both rosin glycerol ester and rosin pentaerythritol ester belong to alcohol esterified modified rosin resin, and rosin resin belongs to natural polymers, which have good biodegradability. After being modified by alcohol esterification, it is more suitable for hot melt adhesive systems. As the proportion of rosin glycerol ester or rosin pentaerythritol ester in the tackifying resin increases, the degradation performance of the hot melt adhesive can naturally be improved to a certain extent. Compared with rosin glycerol ester, rosin pentaerythritol ester has a higher molecular weight and thermal stability, which is beneficial to improve the cohesive strength and bonding performance of the hot melt adhesive, and can provide better comprehensive performance for the hot melt adhesive.

[0068] Combining Examples 9-11 and the data in Tables 1 and 2, it can be seen that when beeswax is used as the biowax material, the bonding strength of the hot melt adhesive is improved compared to when soybean wax is used, but when palm wax is used as the biowax material, the bonding strength of the hot melt adhesive is reduced compared to when soybean wax is used. This may be because soybean wax is not only fine and soft, but also has a certain degree of adhesion, which is conducive to increasing the bonding performance and fluidity of the hot melt adhesive, while beeswax and palm wax have higher viscosity and hardness than soybean wax, which can supplement the corresponding viscosity and cohesive strength for the hot melt adhesive, but the hardness of palm wax may be too high, making the colloid brittle after hardening, so that cohesive failure occurs during the tensile test, affecting the bonding strength.

[0069] This specific implementation manner is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the specific implementation manner as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A degradable hot melt adhesive, It is characterized in that It includes the following raw materials in parts by weight: Base resin: 50-64 parts; Tackifying resin: 18-24 parts; Polyethylene wax: 3.2-4.5 parts; Biological wax: 1.5-2.4 parts; Modified starch granules: 10-16 parts; Antioxidant: 0.8-1.2 parts; The base resin comprises EVA resin and PHBV resin mixed and compounded in a weight ratio of 1: (1-1.5), the tackifying resin comprises C5 hydrogenated petroleum resin and rosin polyol ester mixed and compounded in a weight ratio of 1: (2-5), the modified starch particles are thermoplastic starch modified by plasticization, and the biowax comprises any one of soybean wax, beeswax or palm wax.

2. A degradable hot melt adhesive according to claim 1, Features: The HV content in the PHBV resin is 9%-16% (mol).

3. The degradable hot melt adhesive according to claim 1, Features: The rosin polyol ester is one of rosin glycerol ester and rosin pentaerythritol ester.

4. The degradable hot melt adhesive according to claim 3, Features: The rosin polyol ester is selected from rosin pentaerythritol ester, and the C5 hydrogenated petroleum resin and the rosin pentaerythritol ester are mixed in a weight ratio of 1:(2-3).

5. The degradable hot melt adhesive according to claim 1, Features: The biological wax material is beeswax.

6. The degradable hot melt adhesive according to claim 1, Features: The plasticizing modification of the modified starch granules comprises the following steps: First, corn starch and water are fully mixed at a ratio of 1:1, and then a composite plasticizer composed of glycerol, formamide and urea is added. The mixture is kept at room temperature and fully stirred at a speed of 3000-3500r / min, and then allowed to stand for 24-48 hours. The modified starch particles are obtained by extrusion and cooling.

7. The degradable hot melt adhesive according to claim 6, Features: In the composite plasticizer, the mixing weight ratio of the glycerol, the formamide and the urea is 1:(0.4-0.6):(0.4-0.6), and the mixing weight ratio of the corn starch to the composite plasticizer is 1:(0.2-0.25).

8. The degradable hot melt adhesive according to claim 1, Features: The antioxidant is selected from antioxidant 1010 and antioxidant 168 mixed in a weight ratio of 1: (2-3).

9. A method for preparing a degradable hot melt adhesive, It is characterized in that The method for preparing a degradable hot melt adhesive according to any one of claims 1 to 8 comprises the following preparation steps: S1. First, 10% of the base resin is fully mixed with polyethylene wax, biowax and antioxidant at a mixing temperature of 145-160° C., and then the remaining base resin is added, and the mixture is fully stirred to obtain a first mixture; S2, lowering the mixing temperature to 125-135° C., then adding the tackifying resin and the modified starch granules, and continuing stirring for 20-30 minutes to obtain a second mixture; S3, subjecting the second mixture to vacuum exhaust treatment, and then melting and extruding the second mixture, and rapidly drawing it to a circulating cooling water tank with a cooling solution temperature not higher than 5° C. for cooling, and then cutting and drying, thereby obtaining a degradable hot melt adhesive.

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