A binder composition and its use

Abstract

The present application belongs to the technical field of polymer adhesive material, and particularly relates to an adhesive composition and application thereof. The present application can effectively improve the bonding strength to a polypropylene base material by compounding a styrene-isoprene block copolymer or a styrene-butadiene random copolymer and silica particles. In addition, the present application realizes surface modification of the silica particles by synthesizing a modified polyphenol monomer with a cyclohexane branch, a tert-butyl branch, a phenolic hydroxyl group and a thioether structure, and performing an oxidative polymerization reaction of the synthesized polyphenol monomer on the surface of the silica particles, thereby improving the affinity and dispersion uniformity of the silica particles in the adhesive. Meanwhile, the cyclohexane branch, the tert-butyl branch and the phenolic hydroxyl group grafted on the surface of the modified silica particles can improve the bonding strength between the adhesive and the polyolefin base material through physical and chemical actions such as crosslinking winding, physical embedding and hydrogen bonding, and improve the bending strength and shear strength of the bonded composite material.

Description

Technical Field

[0001] This invention belongs to the field of polymer adhesive materials technology, specifically an adhesive composition and its application. Background Technology

[0002] Polyolefins have a wide range of applications and are currently the most widely used polymer materials, extensively used in packaging, construction, automotive, aerospace, electronics, textiles, sports and leisure, and other fields. However, polyolefins have very low surface energy, making them difficult to bond. In many applications requiring composite bonding with other materials or coatings, achieving ideal adhesion is challenging. Therefore, much research has been conducted to improve the adhesive strength of polyolefins. Some methods involve surface modification, such as chemical treatments including strong acid treatment, chlorination to introduce chlorine into the surface, or grafting polar groups onto the polyolefin matrix to increase surface energy. Additionally, numerous physical treatment methods have been developed, such as ultraviolet irradiation surface treatment, flame and corona treatment, and plasma treatment. However, these chemical or physical methods for modifying the polyolefin surface lead to increased production steps, higher costs, and the introduction of harmful substances.

[0003] In addition, commonly used adhesive resins include polyurethane, epoxy resin, ethylene-vinyl acetate copolymer (EVA), and polyacrylate. However, these resins, whether used alone or in combination, generally exhibit weak adhesion to non-polar polyolefins. Although ethylene-vinyl acetate copolymers incorporate polar vinyl acetate units, their adhesion to polyolefins is still not ideal. While chlorinated polypropylene can be used to improve adhesion to polyolefins, the improvement is limited and cannot meet practical application requirements. Summary of the Invention

[0004] To address the above problems, the present invention provides an adhesive composition and its application, which solves the problem of poor bonding strength when using polymer resins to bond polyolefin materials.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] An adhesive composition comprises an adhesive resin and a solid filler in a mass ratio of 80-95:5-20. The adhesive resin is a styrene-isoprene block copolymer or a styrene-butadiene random copolymer. The solid filler is silica particles or modified silica particles. The modified silica particles are obtained by reacting silica powder in a mixture, followed by solid-liquid separation and drying. The mixture comprises modified tetrahydroxystilbene, trimethylolaminomethane, sodium chloride, and a solvent. The structure of the modified tetrahydroxystilbene is as follows:

[0007] .

[0008] Preferably, the mass ratio of the modified tetrahydroxystilbene, trihydroxymethylaminomethane, sodium chloride, and solvent is 1.5~1.7:0.2~0.4:2~2.3:140~180.

[0009] Preferably, the solvent is composed of 1,4-dioxane and water in a mass ratio of 50~70:90~110.

[0010] Preferably, the mass ratio of the silica powder to the mixture is 1:20~30; and the mixing reaction time is 20~25h.

[0011] Preferably, the styrene content in the styrene-isoprene block copolymer is 20-30%; and the styrene content in the styrene-butadiene random copolymer is 15-20%.

[0012] Preferably, the average specific surface area of ​​the silica particles and silica powder is independently 150~400m². 2 / g.

[0013] Preferably, the modified tetrahydroxystilbene is prepared as follows: 3-mercapto-β,4-dimethylcyclohexanethiol and 3-tert-butylbenzoyl chloride are mixed and reacted in a molar ratio of 1:1 to obtain a mercapto modifier. The chemical structure of the mercapto modifier is as follows:

[0014] ;

[0015] Then, the thiol modifier and 4-hydroxyresveratrol are mixed and reacted at 50~60℃ for 7~10h to obtain modified tetrahydroxystilbene, wherein the molar ratio of the thiol modifier to 4-hydroxyresveratrol is 1.05~1.1:1.

[0016] Preferably, the method for preparing the adhesive composition includes the following steps: preparing an aqueous emulsion of adhesive resin, then mixing the aqueous emulsion and solid filler to obtain a dispersion, and then drying and molding the dispersion to obtain the adhesive composition.

[0017] The application of an adhesive composition as described above in bonding polyolefin resins.

[0018] Preferably, the application includes the following steps: placing the adhesive composition between the polyolefin resins to be bonded and then hot-pressing it to complete the bonding of the polyolefin resins; the hot-pressing pressure is 0.1~0.15MPa, and the time is 2~3min; the polyolefin resin is polyethylene, and the hot-pressing temperature is 130~140℃; the polyolefin resin is polypropylene, and the hot-pressing temperature is 160~170℃.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] This invention effectively improves the bonding strength to polypropylene substrates by compounding styrene-isoprene block copolymers or styrene-butadiene random copolymers with silica particles. Furthermore, this invention synthesizes modified polyphenol monomers with cyclohexane branches, tert-butyl branches, phenolic hydroxyl groups, and thioether structures, and then performs oxidative polymerization on the surface of silica particles to modify the silica particles, thereby improving the affinity and dispersion uniformity of the silica particles in the adhesive. Simultaneously, the cyclohexane branches, tert-butyl branches, and phenolic hydroxyl groups grafted onto the surface of the modified silica particles can enhance the bonding strength between the adhesive and the polyolefin substrate through physicochemical interactions such as crosslinking, physical intercalation, and hydrogen bonding, and also improve the flexural and shear strength of the bonded composite material. Attached Figure Description

[0021] Figure 1 The image shows the 1H NMR spectrum of the modified tetrahydroxystilbene prepared in Example 7 of this invention. Detailed Implementation

[0022] To enable those skilled in the art to better understand the technical solution, the present invention will be described in detail below with reference to embodiments. The description in this part is only exemplary and explanatory, and should not be used to limit the scope of protection of the present invention in any way.

[0023] Example 1

[0024] The adhesive composition of this embodiment consists of a styrene-isoprene block copolymer and silica particles, with a mass ratio of 92:8 between the styrene-isoprene block copolymer and the silica particles.

[0025] The method for preparing the adhesive composition in this embodiment includes the following steps:

[0026] (1) The styrene-isoprene block copolymer and emulsifier were added to a sealed stirred tank and heated to 150°C while stirring slowly. Water was then added under sealed conditions, and the mixture was dispersed and emulsified at a high speed of 5000 rpm. Stirring was continued, and the mixture was slowly cooled to 80°C before being discharged. After cooling to room temperature, a polymer water emulsion was obtained. The mass ratio of styrene-isoprene block copolymer, emulsifier and water was 1:0.2:1. The emulsifier was sodium dodecyl sulfate. The styrene content in the styrene-isoprene block copolymer was 30%. The product brand was Kraton D1124K, which was provided by Kraton.

[0027] (2) Add the polymer emulsion to a mixing tank, add silica particles to the mixing tank under slow stirring, and then disperse by high-speed stirring at 2000 rpm to obtain a dispersion. Pour 8g of the dispersion into a polytetrafluoroethylene mold cavity with dimensions of 100mm×500mm, place it horizontally, and allow it to dry naturally to obtain an adhesive composition. The silica particles are SiO2-400, and the average specific surface area (BET method) is 400m². 2 / g, product brand HDK T40CN, supplied by Wacker AG.

[0028] Example 2

[0029] The only difference between the adhesive composition of this embodiment and the adhesive composition of Example 1 is that the mass ratio of styrene-isoprene block copolymer to silica particles in the adhesive composition of this embodiment is 84:16.

[0030] Example 3

[0031] The only difference between the adhesive composition of this embodiment and the adhesive composition of Example 1 is that the silica particles in the adhesive composition of this embodiment are SiO2-260, and the average specific surface area (BET method) is 260 m². 2 / g, product brand HDK N25CN, supplied by Wacker AG.

[0032] Example 4

[0033] The adhesive composition of this embodiment consists of a styrene-butadiene random copolymer and silica particles, with a mass ratio of 95:5 between the styrene-butadiene random copolymer and the silica particles.

[0034] The method for preparing the adhesive composition in this embodiment includes the following steps:

[0035] Aqueous styrene-butadiene random copolymer (SBR) emulsion was added to a stirred tank. Silica particles were then added to the stirred tank under slow stirring, followed by high-speed stirring at 2000 rpm to disperse the mixture. 8g of the dispersion was poured into a 100mm × 500mm polytetrafluoroethylene mold cavity, placed horizontally, and allowed to dry naturally to obtain the binder composition. The styrene-butadiene random copolymer (SBR) emulsion was a commercially available product, with a styrene-butadiene random copolymer mass fraction of 40% and a styrene content of 15%. The silica particles were SiO2-150 with an average specific surface area (BET method) of 150 m². 2 / g, product brand name HDK V15CN, supplied by Wacker AG.

[0036] Example 5

[0037] The only difference between the adhesive composition of this embodiment and the adhesive composition of Example 4 is that the mass ratio of styrene-butadiene random copolymer to silica particles in the adhesive composition of this embodiment is 80:20.

[0038] Example 6

[0039] The only difference between the adhesive composition of this embodiment and the adhesive composition of Example 4 is that the mass ratio of styrene-butadiene random copolymer to silica particles in the adhesive composition of this embodiment is 90:10, and the silica particles are SiO2-260 with an average specific surface area (BET method) of 260 m². 2 / g, product brand HDK N25CN, supplied by Wacker AG.

[0040] Example 7

[0041] The only difference between the adhesive composition of this embodiment and the adhesive composition of Example 3 is that the silica particles used in the adhesive composition of this embodiment are modified silica particles. The preparation method of the modified silica particles is as follows:

[0042] (1) 3-Mercapto-β,4-dimethylcyclohexanethiol and anhydrous tetrahydrofuran were added to a reaction vessel and stirred until homogeneous to obtain a 13% (w / w) 3-mercapto-β,4-dimethylcyclohexanethiol solution; 3-tert-butylbenzoyl chloride and anhydrous tetrahydrofuran were added to a reaction vessel and stirred until homogeneous to obtain a 20% (w / w) 3-tert-butylbenzoyl chloride solution; the temperature of the 3-mercapto-β,4-dimethylcyclohexanethiol solution was adjusted to -5℃, and the 3-tert-butylbenzoyl chloride solution was added dropwise to the 3-mercapto-β,4-dimethylcyclohexanethiol solution under stirring, and then triethylamine was added. The mixture was stirred at room temperature for 5 h, filtered, and the filtrate was rotary evaporated to obtain the crude product. The crude product was added to a mixed solvent of petroleum ether and ethyl acetate in a volume ratio of 5:4 (the mass ratio of crude product to mixed solvent was 1:1.7). The mixture was heated to reflux to fully dissolve the crude product, then naturally cooled to room temperature and placed in an ice-water bath. It was kept at 0°C for 4 hours, then filtered while cold. The filter cake was washed twice with a small amount of petroleum ether pre-cooled to 0°C (the mass of petroleum ether used in each wash was 1.5 times the mass of the filter cake). Finally, the washed filter cake was vacuum dried at 40°C to obtain the mercapto-modified agent. The molar ratio of 3-mercapto-β,4-dimethylcyclohexanethiol, 3-tert-butylbenzoyl chloride, and triethylamine was 1:1:1.2. The chemical structure of the mercapto-modified agent is as follows:

[0043] .

[0044] (2) Add the mercapto modifier, tetrahydrofuran, 1,5-diazabicyclo[4.3.0]non-5-ene and 4-hydroxyresveratrol to the reaction vessel, stir evenly and heat to 50°C, stir and react for 7 h, rotary evaporate the reaction product to obtain crude product, add the crude product to a mixed solvent of ethyl acetate and methanol with a volume ratio of 5:4 (mass ratio of crude product to mixed solvent is 1:2), heat to 50°C to fully dissolve the crude product, filter while hot to remove insoluble impurities, cool the filtrate naturally at room temperature and place it in a 4°C refrigerator to stand. After 6 hours, the mixture was filtered while cold. The filter cake was washed twice with methanol pre-cooled to 4°C (the mass of methanol used for each wash was 1.2 times the mass of the filter cake). Finally, the washed filter cake was vacuum dried at 50°C to obtain modified tetrahydroxystilbene. The molar ratio of the mercapto modifier, 4-hydroxyresveratrol, and 1,5-diazabicyclo[4.3.0]non-5-ene was 1.05:1:0.25, and the mass of tetrahydrofuran was 70% of the sum of the masses of the mercapto modifier and 4-hydroxyresveratrol. The 1H NMR spectrum of the modified tetrahydroxystilbene is shown below. Figure 1 As shown, the chemical structure is as follows:

[0045] .

[0046] (3) Modified tetrahydroxystilbene, trihydroxymethylaminomethane, sodium chloride, 1,4-dioxane and distilled water in a mass ratio of 1.5:0.2:2:50:90 were added to an open glass bottle and stirred until the solids were fully dissolved to obtain a mixture. Then, silica particles were added to the mixture and ultrasonically dispersed to obtain a dispersion. The glass bottle was kept open and placed on a shaker for 20 hours. The mixture was filtered, and the filter cake was collected. The filter cake was added to deionized water (the mass of deionized water was 8 times the mass of silica particles) and stirred at 300 rpm for 30 minutes at room temperature. The mixture was then filtered for the first washing. The filter cake after the first washing was then added to ethanol. After stirring at 300 rpm for 30 minutes at room temperature with ethanol (the mass of which is 10 times the mass of the silica particles), the mixture was filtered for a second wash. The filter cake from the second wash was then added to deionized water (the mass of which is 8 times the mass of the silica particles) and stirred at 300 rpm for 30 minutes at room temperature. The mixture was then filtered for a third wash. Finally, the filter cake from the third wash was placed in a vacuum drying oven and dried at 50°C for 12 hours to obtain modified silica particles. The mass ratio of silica particles to the mixture was 1:20, the silica particles were SiO2-260, and the average specific surface area (BET method) was 260 m². 2 / g, product brand HDK N25CN, supplied by Wacker AG.

[0047] Thermogravimetric analyzer (TGA instrument model Netzsch TG 209) was used. F3) Thermogravimetric analysis (TGA) was performed on the original silica and the prepared modified silica. During the test, under a nitrogen protective atmosphere (flow rate 50 mL / min), the silica was heated from room temperature to 800℃ at a heating rate of 10℃ / min. The relationship between the mass retention rate of the original silica and the temperature was obtained. The results showed that after removing the adsorbed water (before 100℃), the weight loss rate of the original silica in the range of 200℃ to 600℃ was only 1.2% (mainly attributed to the condensation of surface silanol groups and residual moisture). The modified silica, on the other hand, showed slight weight loss before 100℃ (adsorbed water evaporation), and the weight loss rate in the range of 200℃ to 600℃ was 4.5%, which was 3.3% higher than that of the original silica. This proved that the organic polymer layer was firmly anchored on the silica surface, forming a stable coating layer that could not be removed by conventional washing. This stability is attributed to the strong interaction between the polymer and the hydroxyl groups on the silica surface (including hydrogen bonding, π-π stacking, and possible chemical bonding).

[0048] Example 8

[0049] The only difference between the adhesive composition of this embodiment and the adhesive composition of Example 6 is that the silica particles used in the adhesive composition of this embodiment are modified silica particles. The preparation method of the modified silica particles is as follows:

[0050] (1) 3-Mercapto-β,4-dimethylcyclohexanethiol and anhydrous tetrahydrofuran were added to a reaction vessel and stirred until homogeneous to obtain a 3-mercapto-β,4-dimethylcyclohexanethiol solution with a mass fraction of 18%; 3-tert-butylbenzoyl chloride and anhydrous tetrahydrofuran were added to a reaction vessel and stirred until homogeneous to obtain a 3-tert-butylbenzoyl chloride solution with a mass fraction of 30%; the temperature of the 3-mercapto-β,4-dimethylcyclohexanethiol solution was adjusted to 0℃, and the 3-tert-butylbenzoyl chloride solution was added dropwise to the 3-mercapto-β,4-dimethylcyclohexanethiol solution under stirring, and then triethylamine was added. The mixture was stirred at room temperature for 7 h, filtered, and the filtrate was rotary evaporated to obtain the crude product. The crude product was added to a mixed solvent of petroleum ether and ethyl acetate in a volume ratio of 5:4 (the mass ratio of crude product to mixed solvent was 1:1.7). The mixture was heated to reflux to fully dissolve the crude product, then naturally cooled to room temperature and placed in an ice-water bath. It was kept at 0°C for 4 hours, then filtered while cold. The filter cake was washed twice with a small amount of petroleum ether pre-cooled to 0°C (the mass of petroleum ether used in each wash was 1.5 times the mass of the filter cake). Finally, the washed filter cake was vacuum dried at 40°C to obtain the mercapto-modified agent. The molar ratio of 3-mercapto-β,4-dimethylcyclohexanethiol, 3-tert-butylbenzoyl chloride, and triethylamine was 1:1:1.4. The chemical structure of the mercapto-modified agent is as follows:

[0051] .

[0052] (2) Add the mercapto modifier, tetrahydrofuran, 1,5-diazabicyclo[4.3.0]non-5-ene and 4-hydroxyresveratrol to the reaction vessel, stir evenly and heat to 60°C, stir and react for 10 h, rotary evaporate the reaction product to obtain crude product, add the crude product to a mixed solvent of ethyl acetate and methanol with a volume ratio of 5:4 (mass ratio of crude product to mixed solvent is 1:2), heat to 50°C to fully dissolve the crude product, filter while hot to remove insoluble impurities, cool the filtrate naturally at room temperature and place it in a 4°C refrigerator to stand. After 6 hours, the mixture was filtered while cold. The filter cake was washed twice with methanol pre-cooled to 4°C (the mass of methanol used for each wash was 1.2 times the mass of the filter cake). Finally, the washed filter cake was vacuum dried at 50°C to obtain modified tetrahydroxystilbene. The molar ratio of the mercapto modifier, 4-hydroxyresveratrol, and 1,5-diazabicyclo[4.3.0]non-5-ene was 1.1:1:0.4, and the mass of tetrahydrofuran was 90% of the sum of the masses of the mercapto modifier and 4-hydroxyresveratrol. The chemical structure of the modified tetrahydroxystilbene is shown below:

[0053] .

[0054] (3) Modified tetrahydroxystilbene, trihydroxymethylaminomethane, sodium chloride, 1,4-dioxane, and distilled water in a mass ratio of 1.7:0.4:2.3:70:110 were added to an open glass bottle and stirred until the solids were fully dissolved to obtain a mixture. Then, silica particles were added to the mixture and ultrasonically dispersed to obtain a dispersion. The glass bottle was kept open and placed on a shaker for 25 hours. The mixture was filtered, and the filter cake was collected. The filter cake was added to deionized water (the mass of deionized water was 8 times the mass of silica particles) and stirred at 300 rpm for 30 minutes at room temperature. The mixture was then filtered for the first washing. The filter cake after the first washing was added to... The silica particles were stirred in ethanol (10 times the mass of the silica particles) at 300 rpm for 30 min at room temperature, then filtered for a second wash. The filter cake from the second wash was then added to deionized water (8 times the mass of the silica particles) and stirred at 300 rpm for 30 min at room temperature, followed by a third wash. Finally, the filter cake from the third wash was placed in a vacuum drying oven and dried at 50°C for 12 h to obtain modified silica particles. The mass ratio of silica particles to the mixture was 1:30, the silica particles were SiO2-260, and the average specific surface area (BET method) was 260 m². 2 / g, product brand HDK N25CN, supplied by Wacker AG.

[0055] Thermogravimetric analyzer (TGA instrument model Netzsch TG 209) was used. F3) Thermogravimetric analysis (TGA) was performed on the original silica and the prepared modified silica. During the test, under a nitrogen protective atmosphere (flow rate 50 mL / min), the silica was heated from room temperature to 800℃ at a heating rate of 10℃ / min. The relationship between the mass retention rate of the original silica and the temperature was obtained. The results showed that after removing the adsorbed water (before 100℃), the weight loss rate of the original silica in the range of 200℃ to 600℃ was only 1.2% (mainly attributed to the condensation of surface silanol groups and residual moisture). The modified silica, on the other hand, showed slight weight loss before 100℃ (adsorbed water evaporation), and the weight loss rate in the range of 200℃ to 600℃ was 6.2%, which was 5.0% higher than that of the original silica. This proved that the organic polymer layer was firmly anchored on the silica surface, forming a stable coating layer that could not be removed by conventional washing. This stability is attributed to the strong interaction between the polymer and the hydroxyl groups on the silica surface (including hydrogen bonding, π-π stacking, and possible chemical bonding).

[0056] Comparative Example 1

[0057] The only difference between the adhesive composition of this comparative example and the adhesive composition of Example 1 is that the amount of silica particles in the adhesive composition of this comparative example is 0.

[0058] Comparative Example 2

[0059] The only difference between the adhesive composition of this comparative example and the adhesive composition of Example 4 is that the amount of silica particles in the adhesive composition of this comparative example is 0.

[0060] Comparative Example 3

[0061] The adhesive composition of this comparative example consists of polyacrylate and silica particles in a mass ratio of 90:10.

[0062] The preparation method of the adhesive composition of this comparative example includes the following steps:

[0063] A polyacrylate aqueous emulsion was added to a stirred tank, and silica particles were added to the stirred tank under slow stirring. The mixture was then dispersed by high-speed stirring at 2000 rpm to obtain a dispersion. 8g of the dispersion was poured into a 100mm × 500mm polytetrafluoroethylene mold cavity, placed horizontally, and allowed to dry naturally to obtain the adhesive composition. The polyacrylate aqueous emulsion had a solid content of 55%, was product brand Acronal 3640, and was supplied by BASF. The silica particles were SiO2-400 with an average specific surface area (BET method) of 400 m². 2 / g, product brand HDK T40CN, supplied by Wacker AG.

[0064] Comparative Example 4

[0065] The only difference between the adhesive composition of this comparative example and the adhesive composition of Comparative Example 3 is that the amount of silica particles in the adhesive composition of this comparative example is 0.

[0066] Comparative Example 5

[0067] The adhesive composition of this comparative example consists of polyurethane and silica particles in a mass ratio of 90:10.

[0068] The preparation method of the adhesive composition of this comparative example includes the following steps:

[0069] A polyurethane aqueous dispersion was added to a stirred tank, followed by silica particles under slow stirring. The mixture was then dispersed by high-speed stirring at 2000 rpm to obtain a dispersion. 8g of the dispersion was poured into a 100mm × 500mm polytetrafluoroethylene mold cavity, placed horizontally, and allowed to dry naturally to obtain an adhesive composition. The polyurethane aqueous dispersion had a solid content of 45%, a melting point of 80℃ after drying, and was product brand Dispercoll U 8755, supplied by Covestro. The silica particles were SiO2-400 with an average specific surface area (BET method) of 400 m². 2 / g, product brand HDK T40CN, supplied by Wacker AG.

[0070] Comparative Example 6

[0071] The only difference between the adhesive composition of this comparative example and the adhesive composition of Comparative Example 5 is that the amount of silica particles in the adhesive composition of this comparative example is 0.

[0072] Comparative Example 7

[0073] The binder composition of this comparative example consists of a styrene-isoprene block copolymer and chlorinated polypropylene, with a mass ratio of 90:10 between the styrene-isoprene block copolymer and chlorinated polypropylene.

[0074] The preparation method of the adhesive composition of this comparative example includes the following steps:

[0075] (1) This step is the same as step (1) of the method for preparing the adhesive composition in Example 1;

[0076] (2) Add the polymer water emulsion to the mixing tank, add the chlorinated polypropylene water emulsion to the mixing tank under slow stirring, and then disperse it at high speed of 2000 rpm to obtain a dispersion. Pour 8g of the dispersion into a polytetrafluoroethylene mold cavity with a size of 100mm×500mm, place it horizontally, and let it dry naturally to obtain the adhesive composition. The solid content of the chlorinated polypropylene water emulsion is 31%, the product brand is Sumifitt WR101, and it is supplied by Sumitomo Chemical Co., Ltd.

[0077] Comparative Example 8

[0078] The adhesive composition of this comparative example consists of polyurethane and chlorinated polypropylene in a mass ratio of 90:10.

[0079] The preparation method of the adhesive composition of this comparative example includes the following steps:

[0080] Aqueous polyurethane dispersion was added to a mixing tank, and chlorinated polypropylene aqueous emulsion was added to the mixing tank under slow stirring. Then, the mixture was stirred at high speed of 2000 rpm to obtain a dispersion. 8g of the dispersion was poured into a 100mm×500mm polytetrafluoroethylene mold cavity, placed horizontally, and allowed to dry naturally to obtain an adhesive composition. The solid content of the aqueous polyurethane dispersion was 45%, the melting point of the dried solid was 80℃, and the product brand was Dispercoll U8755, supplied by Covestro. The solid content of the chlorinated polypropylene aqueous emulsion was 31%, and the product brand was Sumifitt WR101, supplied by Sumitomo Chemical.

[0081] Comparative Example 9

[0082] The adhesive composition of this comparative example consists of polyacrylate and chlorinated polypropylene in a mass ratio of 90:10.

[0083] The preparation method of the adhesive composition of this comparative example includes the following steps:

[0084] Aqueous polyacrylate emulsion was added to a mixing tank, and chlorinated polypropylene aqueous emulsion was added to the mixing tank under slow stirring. Then, the mixture was dispersed by high-speed stirring at 2000 rpm to obtain a dispersion. 8g of the dispersion was poured into a 100mm×500mm polytetrafluoroethylene mold cavity, placed horizontally, and allowed to dry naturally to obtain an adhesive composition. The solid content of the aqueous polyacrylate emulsion was 55%, the product brand was Acronal 3640, and it was supplied by BASF. The solid content of the chlorinated polypropylene aqueous emulsion was 31%, the product brand was Sumifitt WR101, and it was supplied by Sumitomo Chemical.

[0085] Comparative Example 10

[0086] The adhesive composition of this comparative example is composed of chlorinated polypropylene.

[0087] The preparation method of the adhesive composition of this comparative example includes the following steps:

[0088] 8g of chlorinated polypropylene aqueous emulsion was poured into a polytetrafluoroethylene mold cavity with dimensions of 100mm×500mm, placed horizontally, and allowed to dry naturally to obtain an adhesive composition; wherein, the solid content of the chlorinated polypropylene aqueous emulsion is 31%, the product brand is Sumifitt WR101, and it is supplied by Sumitomo Chemical Co., Ltd.

[0089] Comparative Example 11

[0090] The only difference between the adhesive composition of this comparative example and the adhesive composition of Example 7 is that the modified silica particles in the adhesive composition of this comparative example are prepared by the following method:

[0091] (1) 3-Mercapto-β,4-dimethylcyclohexanethiol and anhydrous tetrahydrofuran were added to a reaction vessel and stirred until homogeneous to obtain a 13% (w / w) 3-mercapto-β,4-dimethylcyclohexanethiol solution; tert-butylacetyl chloride and anhydrous tetrahydrofuran were added to a reaction vessel and stirred until homogeneous to obtain a 20% (w / w) tert-butylacetyl chloride solution; the temperature of the 3-mercapto-β,4-dimethylcyclohexanethiol solution was adjusted to -5℃, and the tert-butylacetyl chloride solution was added dropwise to the 3-mercapto-β,4-dimethylcyclohexanethiol solution under stirring, followed by the addition of triethylamine. The mixture was stirred at room temperature for 5 hours, filtered, and the filtrate was rotary evaporated to obtain... The crude product was added to a mixed solvent of petroleum ether and ethyl acetate in a volume ratio of 5:4 (the mass ratio of crude product to mixed solvent was 1:1.7). The mixture was heated to reflux to fully dissolve the crude product, then naturally cooled to room temperature and placed in an ice-water bath. It was kept at 0°C for 4 hours and then filtered while cold. The filter cake was washed twice with a small amount of petroleum ether pre-cooled to 0°C (the mass of petroleum ether used in each wash was 1.5 times the mass of the filter cake). Finally, the washed filter cake was vacuum dried at 40°C to obtain the mercapto modifier. The molar ratio of 3-mercapto-β,4-dimethylcyclohexanethiol, tert-butylacetyl chloride, and triethylamine was 1:1:1.2.

[0092] (2) Add the mercapto modifier, tetrahydrofuran, 1,5-diazabicyclo[4.3.0]non-5-ene and 4-hydroxyresveratrol to the reaction vessel, stir evenly and heat to 50°C, stir and react for 7 h, rotary evaporate the reaction product to obtain crude product, add the crude product to a mixed solvent of ethyl acetate and methanol with a volume ratio of 5:4 (mass ratio of crude product to mixed solvent is 1:2), heat to 50°C to fully dissolve the crude product, filter while hot to remove insoluble impurities, cool the filtrate naturally at room temperature and place it in a 4°C refrigerator for 6 h. The mixture was filtered while cold, and the filter cake was washed twice with methanol pre-cooled to 4°C (the mass of methanol used for each wash was 1.2 times the mass of the filter cake). Finally, the washed filter cake was vacuum dried at 50°C to obtain modified tetrahydroxystilbene. The molar ratio of the mercapto modifier, 4-hydroxyresveratrol, and 1,5-diazabicyclo[4.3.0]non-5-ene was 1.05:1:0.25, and the mass of tetrahydrofuran was 70% of the sum of the masses of the mercapto modifier and 4-hydroxyresveratrol. The chemical structure of the modified tetrahydroxystilbene is shown below:

[0093] .

[0094] (3) Modified tetrahydroxystilbene, trihydroxymethylaminomethane, sodium chloride, 1,4-dioxane and distilled water in a mass ratio of 1.5:0.2:2:50:90 were added to an open glass bottle and stirred until the solids were fully dissolved to obtain a mixture. Then, silica particles were added to the mixture and ultrasonically dispersed to obtain a dispersion. The glass bottle was kept open and placed on a shaker for 20 hours. The mixture was filtered, and the filter cake was collected. The filter cake was added to deionized water (the mass of deionized water was 8 times the mass of silica particles) and stirred at 300 rpm for 30 minutes at room temperature. The mixture was then filtered for the first washing. The filter cake after the first washing was then added to ethanol. After stirring at 300 rpm for 30 minutes at room temperature with ethanol (the mass of which is 10 times the mass of the silica particles), the mixture was filtered for a second wash. The filter cake from the second wash was then added to deionized water (the mass of which is 8 times the mass of the silica particles) and stirred at 300 rpm for 30 minutes at room temperature. The mixture was then filtered for a third wash. Finally, the filter cake from the third wash was placed in a vacuum drying oven and dried at 50°C for 12 hours to obtain modified silica particles. The mass ratio of silica particles to the mixture was 1:20, the silica particles were SiO2-260, and the average specific surface area (BET method) was 260 m². 2 / g, product brand HDK N25CN, supplied by Wacker AG.

[0095] Thermogravimetric analysis (TGA) was performed on pristine silica and the prepared modified silica using a Netzsch TG 209 F3 instrument. The test was conducted under a nitrogen atmosphere (flow rate 50 mL / min) with a heating rate of 10 °C / min from room temperature to 800 °C. The relationship between the mass retention rate of pristine silica and the temperature was obtained. The results showed that after removing adsorbed water (before 100 °C), the weight loss rate of pristine silica in the 200 °C–600 °C range was only 1.2% (mainly attributed to the condensation of surface silanol groups and residual moisture); while the modified silica showed slight weight loss before 100 °C (adsorbed water evaporation), with a weight loss rate of 3.9% in the 200 °C–600 °C range.

[0096] Comparative Example 12

[0097] The only difference between the adhesive composition of this comparative example and the adhesive composition of Example 7 is that the modified silica particles in the adhesive composition of this comparative example are prepared by the following method:

[0098] (1) 3-Mercapto-β,4-dimethylcyclohexanethiol and anhydrous tetrahydrofuran were added to a reaction vessel and stirred until homogeneous to obtain a 13% (w / w) 3-mercapto-β,4-dimethylcyclohexanethiol solution; benzoyl chloride and anhydrous tetrahydrofuran were added to a reaction vessel and stirred until homogeneous to obtain a 20% (w / w) benzoyl chloride solution; the temperature of the 3-mercapto-β,4-dimethylcyclohexanethiol solution was adjusted to -5℃, and the benzoyl chloride solution was added dropwise to the 3-mercapto-β,4-dimethylcyclohexanethiol solution under stirring, followed by the addition of triethylamine. The mixture was stirred at room temperature for 5 hours, filtered, and the filtrate was rotary evaporated to obtain the crude product. The crude product was added to a mixed solvent of petroleum ether and ethyl acetate in a volume ratio of 5:4 (the mass ratio of crude product to mixed solvent was 1:1.7). The mixture was heated to reflux to fully dissolve the crude product, then naturally cooled to room temperature and placed in an ice-water bath. It was kept at 0°C for 4 hours and then filtered while cold. The filter cake was washed twice with a small amount of petroleum ether pre-cooled to 0°C (the mass of petroleum ether used in each wash was 1.5 times the mass of the filter cake). Finally, the washed filter cake was vacuum dried at 40°C to obtain the mercapto modifier. The molar ratio of 3-mercapto-β,4-dimethylcyclohexanethiol, benzoyl chloride, and triethylamine was 1:1:1.2.

[0099] (2) Add the mercapto modifier, tetrahydrofuran, 1,5-diazabicyclo[4.3.0]non-5-ene and 4-hydroxyresveratrol to the reaction vessel, stir evenly and heat to 50°C, stir and react for 7 h, rotary evaporate the reaction product to obtain crude product, add the crude product to a mixed solvent of ethyl acetate and methanol with a volume ratio of 5:4 (mass ratio of crude product to mixed solvent is 1:2), heat to 50°C to fully dissolve the crude product, filter while hot to remove insoluble impurities, cool the filtrate naturally at room temperature and place it in a 4°C refrigerator for 6 h. The mixture was filtered while cold, and the filter cake was washed twice with methanol pre-cooled to 4°C (the mass of methanol used for each wash was 1.2 times the mass of the filter cake). Finally, the washed filter cake was vacuum dried at 50°C to obtain modified tetrahydroxystilbene. The molar ratio of the mercapto modifier, 4-hydroxyresveratrol, and 1,5-diazabicyclo[4.3.0]non-5-ene was 1.05:1:0.25, and the mass of tetrahydrofuran was 70% of the sum of the masses of the mercapto modifier and 4-hydroxyresveratrol. The chemical structure of the modified tetrahydroxystilbene is shown below:

[0100] .

[0101] (3) Modified tetrahydroxystilbene, trihydroxymethylaminomethane, sodium chloride, 1,4-dioxane and distilled water in a mass ratio of 1.5:0.2:2:50:90 were added to an open glass bottle and stirred until the solids were fully dissolved to obtain a mixture. Then, silica particles were added to the mixture and ultrasonically dispersed to obtain a dispersion. The glass bottle was kept open and placed on a shaker for 20 hours. The mixture was filtered, and the filter cake was collected. The filter cake was added to deionized water (the mass of deionized water was 8 times the mass of silica particles) and stirred at 300 rpm for 30 minutes at room temperature. The mixture was then filtered for the first washing. The filter cake after the first washing was then added to ethanol. After stirring at 300 rpm for 30 minutes at room temperature with ethanol (the mass of which is 10 times the mass of the silica particles), the mixture was filtered for a second wash. The filter cake from the second wash was then added to deionized water (the mass of which is 8 times the mass of the silica particles) and stirred at 300 rpm for 30 minutes at room temperature. The mixture was then filtered for a third wash. Finally, the filter cake from the third wash was placed in a vacuum drying oven and dried at 50°C for 12 hours to obtain modified silica particles. The mass ratio of silica particles to the mixture was 1:20, the silica particles were SiO2-260, and the average specific surface area (BET method) was 260 m². 2 / g, product brand HDK N25CN, supplied by Wacker AG.

[0102] Thermogravimetric analysis (TGA) was performed on pristine silica and the prepared modified silica using a Netzsch TG 209 F3 instrument. The test was conducted under a nitrogen atmosphere (flow rate 50 mL / min) with a heating rate of 10 °C / min from room temperature to 800 °C. The relationship between the mass retention rate of pristine silica and modified silica and temperature was obtained. The results showed that after removing adsorbed water (before 100 °C), the weight loss rate of pristine silica in the 200 °C–600 °C range was only 1.2% (mainly attributed to the condensation of surface silanol groups and residual moisture); while modified silica showed slight weight loss before 100 °C (adsorbed water evaporation), with a weight loss rate of 4.1% in the 200 °C–600 °C range.

[0103] Comparative Example 13

[0104] The only difference between the adhesive composition of this comparative example and the adhesive composition of Example 7 is that the modified silica particles in the adhesive composition of this comparative example are prepared by the following method:

[0105] 4-hydroxyresveratrol, tris(hydroxymethyl)aminomethane, sodium chloride, 1,4-dioxane, and distilled water in a mass ratio of 1.5:0.2:2:50:90 were added to an open glass bottle and stirred until the solids were fully dissolved to obtain a mixture. Then, silica particles were added to the mixture and ultrasonically dispersed to obtain a dispersion. The glass bottle was kept open and placed on a shaker for 20 hours. After filtration, the filter cake was collected. The filter cake was added to deionized water (the mass of deionized water was 8 times the mass of silica particles) and stirred at 300 rpm for 30 minutes at room temperature. The mixture was then filtered for the first washing. The filter cake after the first washing was then added to ethanol (ethanol...). The silica particles were mixed with alcohol (10 times the mass of the silica particles) and stirred at 300 rpm for 30 min at room temperature. The mixture was then filtered for a second wash. The filter cake from the second wash was then added to deionized water (8 times the mass of the silica particles) and stirred at 300 rpm for 30 min at room temperature. The mixture was then filtered for a third wash. Finally, the filter cake from the third wash was placed in a vacuum drying oven and dried at 50°C for 12 h to obtain modified silica particles. The mass ratio of silica particles to the mixture was 1:20, the silica particles were SiO2-260, and the average specific surface area (BET method) was 260 m². 2 / g, product brand HDK N25CN, supplied by Wacker AG.

[0106] Thermogravimetric analysis (TGA) was performed on pristine silica and the prepared modified silica using a Netzsch TG 209 F3 instrument. The test was conducted under a nitrogen atmosphere (flow rate 50 mL / min) with a heating rate of 10 °C / min from room temperature to 800 °C. The relationship between the mass retention rate of pristine silica and the temperature was obtained. The results showed that after removing adsorbed water (before 100 °C), the weight loss rate of pristine silica in the 200 °C–600 °C range was only 1.2% (mainly attributed to the condensation of surface silanol groups and residual moisture); while the modified silica showed slight weight loss before 100 °C (adsorbed water evaporation), with a weight loss rate of 2.5% in the 200 °C–600 °C range.

[0107] Application examples

[0108] To examine the bonding effect of the adhesive compositions of the various embodiments and comparative examples on polyolefin resins, the adhesive compositions of the various embodiments and comparative examples were cut into adhesive sheets with a size of 50mm × 50mm, and then placed between two sheets of untreated polypropylene material. They were then hot-pressed for 2 minutes at 160°C and 0.1MPa pressure in a hot press to obtain an adhesive composite consisting of a three-layer structure of polypropylene layer / adhesive layer / polypropylene layer. After hot pressing, the composite was cooled to room temperature, and then cut into 2.5mm wide strip samples for adhesive performance testing. Adhesive performance tests included peel force testing, flexural strength testing, and shear strength testing. The peel force test method was as follows: the strip sample was clamped on both sides using two clamps on an electronic universal testing machine, and peeled at a speed of 100mm / min. The average peel force was recorded, and the experiment was repeated three times, calculating the average value. Flexural strength and shear strength were tested using a universal testing machine, with each sample tested three times, and the average of the three test results was taken as the final test result. When testing the same performance index, ensure that the production batch of the polypropylene material used for the upper and lower polypropylene layers in different adhesive composites, the thickness of the formed polypropylene layer, and the thickness of the formed intermediate adhesive layer are the same; when testing peel strength, the polypropylene material is a polypropylene film, and when testing flexural strength and shear strength, the polypropylene material is a polypropylene sheet.

[0109] The bonding effects of the adhesive compositions of each embodiment and comparative example on polyolefin resins are shown in Table 1.

[0110] Table 1. Adhesion effect of the adhesive compositions of each embodiment and comparative example on polyolefin resin.

[0111]

[0112] Note: "-" indicates that it has not been tested.

[0113] As shown in Table 1, this invention effectively improves the bonding strength to polypropylene substrates by combining styrene-isoprene block copolymers or styrene-butadiene random copolymers with silica particles. Furthermore, this invention synthesizes modified polyphenol monomers with cyclohexane branches, tert-butyl branches, phenolic hydroxyl groups, and thioether structures, and then performs oxidative polymerization on the surface of silica particles to modify the silica particles, thereby improving the affinity and dispersion uniformity of the silica particles in the adhesive. Simultaneously, the cyclohexane branches, tert-butyl branches, and phenolic hydroxyl groups grafted onto the surface of the modified silica particles can improve the bonding strength between the adhesive and the polyolefin substrate through physicochemical interactions such as crosslinking, physical intercalation, and hydrogen bonding, and also enhance the flexural and shear strength of the bonded composite material.

[0114] As can be seen from Examples 1, 4 and Comparative Examples 1-2, when styrene-isoprene block copolymer or styrene-butadiene random copolymer is used alone as an adhesive, the bonding strength to the polypropylene substrate is poor, indicating that silica particles can reduce the internal stress of the resin adhesive and improve the bonding strength.

[0115] As shown in Comparative Examples 3-6, when polyacrylate is used alone or when a mixture of polyacrylate and silica particles is used as an adhesive, the bonding strength to the polypropylene substrate is poor. Furthermore, the addition of silica particles to polyacrylate does not significantly improve the bonding strength of the adhesive to polypropylene. In contrast, the addition of silica particles to polyurethane reduces the bonding strength of the adhesive to polypropylene, indicating that silica particles do not necessarily improve the bonding performance of all adhesive resins.

[0116] As shown in Comparative Examples 7-10, using chlorinated polypropylene alone as a binder does not significantly alter the bonding performance of polypropylene. However, when chlorinated polypropylene is added to styrene-isoprene block copolymers, polyurethanes, and polyacrylates for modification, the bonding strength of the binder to polypropylene exhibits irregular changes. The bonding strength of styrene-isoprene block copolymers decreases after the addition of chlorinated polypropylene, while the bonding strength of polyurethanes and polyacrylates increases slightly, but the increase is not significant, and the shear strength of the bonded composite decreases.

[0117] As shown in Examples 3, 7, and Comparative Examples 11-13, while the modified silica particles obtained by coating silica particles with 4-hydroxyresveratrol can improve the compatibility of silica particles in organic binders, the lack of cyclohexane and tert-butyl branches results in weak distribution and bonding force of the modified silica particles in the organic resin, leading to low bonding strength and mechanical strength. Furthermore, when the polymer layer grafted onto the surface of the modified silica particles lacks benzene rings, cyclohexyl groups, or tert-butyl groups, the modified silica particles also fail to effectively improve the overall performance of the binder, indicating that the structure and functional groups of the coating layer have a significant impact on the binder's performance.

[0118] It should be noted that, in this document, the terms "comprising," "including," and any other variations are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Specific examples have been used in this document to illustrate the principles and implementation methods of the present invention. These examples are merely for the purpose of helping to understand the method and core ideas of the present invention. The above descriptions are only preferred embodiments of the present invention. It should be pointed out that, due to the limitations of written expression and the objective existence of infinite specific structures, those skilled in the art can make several improvements, modifications, or variations without departing from the principles of the present invention, and can also combine the above technical features in an appropriate manner. These improvements, modifications, variations, or combinations, or the direct application of the concept and technical solution of the present invention to other situations without modification, should all be considered within the scope of protection of the present invention.

Claims

1. An adhesive composition, characterized in that, It is composed of an adhesive resin and a solid filler in a mass ratio of 80~95:5~20. The adhesive resin is a styrene-isoprene block copolymer or a styrene-butadiene random copolymer. The solid filler is silica particles or modified silica particles. The modified silica particles are obtained by mixing silica powder in a mixture, reacting, separating the solid and liquid components, and drying. The mixture consists of modified tetrahydroxystilbene, tris(hydroxymethyl)aminomethane, sodium chloride, and a solvent. The structure of the modified tetrahydroxystilbene is as follows: 。 2. The adhesive composition according to claim 1, characterized in that, The mass ratio of the modified tetrahydroxystilbene, trihydroxymethylaminomethane, sodium chloride, and solvent is 1.5~1.7:0.2~0.4:2~2.3:140~180.

3. The adhesive composition according to claim 2, characterized in that, The solvent is composed of 1,4-dioxane and water in a mass ratio of 50~70:90~110.

4. The adhesive composition according to any one of claims 1-3, characterized in that, The mass ratio of silica powder to the mixture is 1:20~30; the mixing reaction time is 20~25h.

5. The adhesive composition according to claim 1, characterized in that, The styrene-isoprene block copolymer contains 20-30% styrene; the styrene-butadiene random copolymer contains 15-20% styrene.

6. The adhesive composition according to claim 1, characterized in that, The average specific surface area of ​​the silica particles and silica powder is independently 150~400m². 2 / g.

7. The adhesive composition according to claim 1 or 2, characterized in that, The modified tetrahydroxystilbene is prepared as follows: 3-mercapto-β,4-dimethylcyclohexanethiol and 3-tert-butylbenzoyl chloride are mixed and reacted in a molar ratio of 1:1 to obtain a mercapto modifier. The chemical structure of the mercapto modifier is as follows: ； Then, the thiol modifier and 4-hydroxyresveratrol are mixed and reacted at 50~60℃ for 7~10h to obtain modified tetrahydroxystilbene, wherein the molar ratio of the thiol modifier to 4-hydroxyresveratrol is 1.05~1.1:

1.

8. The adhesive composition according to claim 1, characterized in that, The method for preparing the adhesive composition includes the following steps: preparing an adhesive resin into an aqueous emulsion, then mixing the aqueous emulsion and a solid filler to obtain a dispersion, and then drying and molding the dispersion to obtain the adhesive composition.

9. The use of an adhesive composition as described in any one of claims 1-8 in bonding polyolefin resins.

10. The application according to claim 9, characterized in that, The application includes the following steps: placing the adhesive composition between the polyolefin resins to be bonded and then hot-pressing it to complete the bonding of the polyolefin resins; the hot-pressing pressure is 0.1~0.15MPa, and the time is 2~3min; the polyolefin resin is polyethylene, and the hot-pressing temperature is 130~140℃; the polyolefin resin is polypropylene, and the hot-pressing temperature is 160~170℃.

Images