Solid binder for polyolefins and process for its preparation

Abstract

The present application belongs to the technical field of polymer binder materials, and particularly relates to a solid binder for polyolefins and a preparation method thereof. The solid binder is prepared by compounding styrene-isoprene block copolymer, styrene-butadiene random copolymer rubber and silica particles, so that the bonding strength of the solid binder to a polypropylene base material and the bending strength and shear strength of a polypropylene layered material can be effectively improved. In the present application, the silica particles are modified by a silane coupling agent containing end-branched cyclohexyl, tertiary butyl and butoxy structures, so that a large number of branched cyclohexyl and tertiary butyl structures can be grafted on the surface of the silica particles. These structures can be tightly combined with the organic resin in the solid binder through physical entanglement, embedding and other actions, so that the grabbing force to the polypropylene material can be improved when the polypropylene material is hot-pressed, and the bending strength and shear strength of the high-layered material can be improved.

Description

Technical Field

[0001] This invention belongs to the field of polymer adhesive materials technology, specifically a solid adhesive for polyolefins and its preparation method. 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 treatment, including treatment with strong acids, 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, 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, this invention provides a solid adhesive for polyolefins and its preparation method, which solves the problem of poor bonding strength in the current method of bonding polyolefin materials with polymer resins.

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

[0006] A solid binder for polyolefins comprises a polymer resin matrix and a solid filler, wherein the mass ratio of the polymer resin matrix to the solid filler is 80-95:5-20. The polymer resin matrix is ​​a styrene-isoprene block copolymer or a styrene-butadiene random copolymer rubber. The solid filler is silica particles or modified silica particles. The modified silica particles are prepared by modifying silica powder with a silane coupling agent. The chemical structure of the silane coupling agent is shown below:

[0007] .

[0008] Preferably, the modified silica particles are prepared as follows: a silane coupling agent, water and acetic acid are mixed and allowed to stand for 30-45 minutes, then silica powder is added and the mixture is reacted for 6-9 hours to obtain modified silica particles.

[0009] Preferably, the mass ratio of the silica powder, silane coupling agent, water and acetic acid is 1.2~1.5:1.8~2.4:100~120:1.9~2.5.

[0010] Preferably, the silane coupling agent is prepared as follows: 1,3-bis(tert-butylamino)-2-propanol and (1-bromoethyl)cyclohexane are mixed and reacted to obtain a tertiary amine alcohol compound; then, the tertiary amine alcohol compound and a dichlorosiloxane compound are mixed and reacted to obtain the silane coupling agent; the molar ratio of 1,3-bis(tert-butylamino)-2-propanol and (1-bromoethyl)cyclohexane is 1:2, and the molar ratio of the tertiary amine alcohol compound and the dichlorosiloxane compound is 2.1~2.2:1; the structure of the tertiary amine alcohol compound is as follows:

[0011] ;

[0012] The structure of the dichlorosiloxane compound is as follows:

[0013] .

[0014] Preferably, the dichlorosiloxane compound is prepared as follows: 1,3-divinyl-1,1,3,3-tetramethoxydisiloxane and chloro(butoxy)(methyl)silane are mixed and reacted under the action of a platinum catalyst to obtain the dichlorosiloxane compound; the molar ratio of 1,3-divinyl-1,1,3,3-tetramethoxydisiloxane and chloro(butoxy)(methyl)silane is 1:2.1~2.2.

[0015] Preferably, the temperature for mixing and reacting 1,3-bis(tert-butylamino)-2-propanol and (1-bromoethyl)cyclohexane is 65-75°C, and the time is 5-8 hours.

[0016] Preferably, the average specific surface area of ​​the silica particles and silica powder is independently 150~400m². 2 / g.

[0017] Preferably, the styrene content in the styrene-isoprene block copolymer is 25-30%.

[0018] Preferably, the styrene-butadiene random copolymer rubber contains 23.5% to 28% styrene.

[0019] A method for preparing a solid binder for polyolefins as described above includes the following steps: kneading a polymer resin matrix and then kneading it with a solid filler to obtain a solid binder for polyolefins.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] (1) The peel strength of the solid adhesive and the polypropylene substrate of the present invention is greater than 58 N / 25 mm, and the flexural strength of the resulting polypropylene layered material is greater than 39 MPa and the shear strength is greater than 14 MPa. The present invention uses styrene-isoprene block copolymer, styrene-butadiene random copolymer rubber and silica particles for compounding, which can effectively improve the bonding strength of the solid adhesive to the polypropylene substrate and the flexural and shear strength of the polypropylene layered material. The silica particles filled in the solid adhesive can reduce the internal stress generated during adhesive bonding, and the inorganic silica particles can enhance the strength of the adhesive layer in the layered material, thereby improving the flexural and shear strength of the layered material.

[0022] (2) In this invention, a silane coupling agent containing end-branched cyclohexyl, tert-butyl and butoxy structures is used to modify silica particles. A large number of branched cyclohexyl and tert-butyl structures can be grafted onto the surface of silica particles. These structures can be tightly bonded to the organic resin in the solid binder through physical winding, embedding and other actions. When hot-pressed with polypropylene material, they can improve the gripping force on polypropylene and improve the bending strength and shear strength of high-layer materials. Attached Figure Description

[0023] Figure 1 The 1H NMR spectrum of the tertiary amine alcohol compound prepared in Example 7 of this invention;

[0024] Figure 2 The image shows the 1H NMR spectrum of the silane coupling agent prepared in Example 7 of this invention. Detailed Implementation

[0025] 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.

[0026] Example 1

[0027] The solid binder for polyolefins in this embodiment is composed of styrene-isoprene block copolymer and silica particles, with a mass ratio of styrene-isoprene block copolymer to silica particles of 92:8.

[0028] The preparation method of the polyolefin solid binder in this embodiment includes the following steps: Styrene-isoprene block copolymer is added to a Hacker internal mixer, the mixer is started, the kneading rotor speed is controlled at 100 rpm, and after 5 minutes, the temperature rises and reaches equilibrium. Then, it is heated to 150°C and kneaded for another 5 minutes. Next, silica particles are added, and kneading and dispersion are continued for 10 minutes. The product is then discharged onto a two-roll mill for rolling and sheet forming to obtain a sheet binder with a thickness of 0.5 mm. The styrene-isoprene block copolymer (SIS) contains 30% styrene, the product brand is Kraton D1124K, and it is supplied by Kraton. The silica particles are SiO2-400 with an average specific surface area (BET method) of 400 m². 2 / g, product brand HDK T40CN, supplied by Wacker AG.

[0029] Example 2

[0030] The only difference between the solid binder for polyolefins in this embodiment and the solid binder for polyolefins in Example 1 is that the mass ratio of styrene-isoprene block copolymer to silica particles in the solid binder for polyolefins in this embodiment is 84:16.

[0031] Example 3

[0032] The only difference between the solid binder for polyolefins in this embodiment and the solid binder for polyolefins in Example 1 is that the silica particles in the solid binder for polyolefins in 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.

[0033] Example 4

[0034] The solid binder for polyolefins in this embodiment is composed of styrene-butadiene random copolymer rubber and silica particles, with a mass ratio of styrene-butadiene random copolymer rubber to silica particles of 95:5.

[0035] The preparation method of the polyolefin solid binder in this embodiment includes the following steps: Styrene-butadiene random copolymer rubber is added to a Hacker internal mixer, the mixer is started, the kneading rotor speed is controlled at 100 rpm, and after 5 minutes, the temperature rises and reaches equilibrium. Then, it is heated to 150°C and kneaded for another 5 minutes. Next, silica particles are added, and kneading and dispersion are continued for 10 minutes. The material is then discharged onto a two-roll mill for rolling and sheet forming to obtain a sheet binder with a thickness of 0.5 mm. The styrene-butadiene random copolymer rubber (SBR) contains 23.5% styrene, and its product grade is Buna SE 1502H, supplied by Arlanxeo. The silica particles are SiO2-150 with an average specific surface area (BET method) of 150 m². 2 / g, product brand HDK V15CN, supplied by Wacker AG.

[0036] Example 5

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

[0038] Example 6

[0039] The only difference between the solid binder for polyolefins in this embodiment and the solid binder for polyolefins in Example 4 is that the mass ratio of styrene-butadiene random copolymer rubber to silica particles in the solid binder for polyolefins in 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 solid binder for polyolefins in this embodiment and the solid binder for polyolefins in Example 1 is that the silica particles in this embodiment are replaced with modified silica particles. The preparation method of the modified silica particles is as follows:

[0042] (1) 1,3-bis(tert-butylamino)-2-propanol and tetrahydrofuran in a mass ratio of 2:1 were added to a reaction vessel, stirred evenly, and heated to 40°C. Under stirring, a tetrahydrofuran solution of (1-bromoethyl)cyclohexane (mass fraction of 30%) was added dropwise to the reaction vessel, followed by the addition of a 35% sodium hydroxide solution. After the addition was completed, the material in the reaction vessel was heated to 65°C and stirred for 5 hours. The mixture was then cooled to room temperature, and the reaction product was extracted with dichloromethane. The extracted organic phase was then distilled under reduced pressure to obtain a concentrate. A mixture of petroleum ether and anhydrous ethanol in a volume ratio of 2:1 was then added to the concentrate. The concentrate and mixed solvent (mass ratio of concentrate to mixed solvent is 1:2.5) were placed in a 60℃ water bath and stirred until the concentrate was fully dissolved. The solution was filtered while hot, and the filtrate was allowed to cool naturally to room temperature before being placed in a refrigerator and allowed to stand at 2℃ for 12 hours to crystallize. The solid was then collected by suction filtration using a Buchner funnel. The filter cake was washed twice with a mixed solvent of petroleum ether and anhydrous ethanol (volume ratio 2:1, pre-cooled to 2℃) (each wash using a mixed solvent with a mass ratio twice the wet weight of the filter cake). Finally, the washed filter cake was placed in a vacuum drying oven and dried under vacuum at 50℃ and -0.08 to -0.09 MPa for 12 hours to obtain tertiary amine alcohols. The molar ratio of 1,3-bis(tert-butylamino)-2-propanol, (1-bromoethyl)cyclohexane, and sodium hydroxide was 1:2:2.3. The 1H NMR spectrum of the tertiary amine alcohols is shown below. Figure 1 As shown, the structural formula is as follows:

[0043] .

[0044] (2) 1,3-Divinyl-1,1,3,3-tetramethoxydisiloxane and dichloromethane were added to the first stirred tank and stirred until homogeneous to obtain a 15% (w / w) 1,3-divinyl-1,1,3,3-tetramethoxydisiloxane solution; chloro(butoxy)(methyl)silane and dichloromethane were added to the second stirred tank and stirred until homogeneous to obtain a 15% (w / w) chloro(butoxy)(methyl)silane solution; then nitrogen gas was introduced into the second stirred tank and a solid platinum catalyst was added, and the second stirred tank was... The temperature of the materials was controlled at 60℃. Under stirring, a solution of 1,3-divinyl-1,1,3,3-tetramethoxydisiloxane was added dropwise to the second stirred tank. After the addition was complete, stirring was continued for 1 hour. The solvent was removed by vacuum distillation to obtain a concentrate. Then, n-hexane (mass ratio of concentrate to n-hexane was 1:5) was added to the concentrate. The mixture was placed in a 55℃ water bath and stirred until the concentrate was fully dissolved. After removal, it was allowed to cool naturally to room temperature, then placed in an ice-water bath to cool to 0℃. Crystallization was allowed to occur at this constant temperature for 8 hours. Crystals were then extracted using a Buchner funnel. The solid was collected by filtration, and the filter cake was washed twice with n-hexane pre-cooled to 0℃ (the mass of n-hexane used for each wash was twice the wet weight of the filter cake). Finally, the washed filter cake was placed in a vacuum drying oven and dried under vacuum at 45℃ and -0.09MPa for 12 h to obtain a dichlorosiloxane compound; wherein the molar ratio of 1,3-divinyl-1,1,3,3-tetramethoxydisiloxane and chloro(butoxy)(methyl)silane was 1:2.1, and the platinum element in the solid platinum catalyst and the chloro(butoxy)(methyl)silane... The solid platinum catalyst, with a mass ratio of 0.0005:1, was prepared as follows: 2.5 g of polyethylene glycol (PEG400) was dissolved in 35 mL of anhydrous ethanol, and then 4 mL of isopropanol chloroplatinate solution (concentration 0.05 mol / L) was added to obtain a mixture. Then, 5 g of dried 4A molecular sieve was added to the mixture, stirred evenly, and allowed to stand for 24 h. The solvent was removed by vacuum distillation, and the catalyst was dried to obtain a solid platinum catalyst (platinum mass fraction 0.4%). The structure of the chloro(butoxy)(methyl)silane is shown below:

[0045] ;

[0046] The chemical structure of dichlorosiloxane compounds is shown below:

[0047] .

[0048] (3) Add a tertiary amine alcohol compound and anhydrous tetrahydrofuran in a mass ratio of 1:1.5 to a reaction vessel, then introduce nitrogen gas into the reaction vessel and heat it to 75°C. Under stirring, add a 15% tetrahydrofuran solution of dichlorosiloxane compound by mass to the reaction vessel dropwise. After the addition is complete, continue stirring for 8 hours. Remove the tetrahydrofuran by vacuum distillation to obtain a concentrate. Then add a mixed solvent consisting of ethyl acetate and petroleum ether in a volume ratio of 1:2 (mass ratio of concentrate to mixed solvent is 1:3) to the concentrate. Place it in a 70°C water bath and stir until the concentrate is fully dissolved. Remove it and let it sit naturally. The mixture was cooled to room temperature and then placed in a refrigerator. Crystallization was carried out at 1°C for 12 hours. The solid was then collected by suction filtration using a Buchner funnel. The filter cake was washed three times with a mixed solvent of ethyl acetate and petroleum ether (volume ratio 1:2), pre-cooled to 1°C (each wash using a mixed solvent mass 1.5 times the wet weight of the filter cake). Finally, the washed filter cake was placed in a vacuum drying oven and dried under vacuum at 55°C and -0.08 to -0.09 MPa for 12 hours to obtain the silane coupling agent. The molar ratio of the tertiary amine alcohol compound to the dichlorosiloxane compound was 2.1:1. The 1H NMR spectrum of the silane coupling agent is shown below. Figure 2 As shown, the chemical structure is as follows:

[0049] .

[0050] (4) Add silane coupling agent, water and acetic acid to the reactor, stir evenly and let stand for 30 min. Then add silica particles to the reactor and stir at 400 rpm for 6 h. Filter and add the filter cake to ethanol (the mass ratio of wet weight of filter cake to ethanol is 1:5). Stir at 300 rpm for 15 min and filter. Add the obtained filter cake to deionized water again (the mass ratio of wet weight of filter cake to deionized water is 1:5). Stir at 300 rpm for 20 min and filter. Dry the obtained filter cake in a vacuum drying oven at 80℃ and -0.09 MPa for 12 h to obtain modified silica particles. The mass ratio of silica particles, silane coupling agent, water and acetic acid is 1.2:1.8:100:1.9. The silica particles are SiO2-400 and the average specific surface area (BET method) is 400 m². 2 / g, product brand HDK T40CN, supplied by Wacker AG.

[0051] In this embodiment, silica particles and modified silica particles were respectively placed in alumina crucibles and heated from room temperature to 800°C at a heating rate of 10°C / min under high-purity nitrogen purging (purging flow rate of 50 mL / min). The weight loss rate of silica particles and modified silica particles in the range of room temperature to 800°C was recorded. Each sample was tested 3 times, and the average of the 3 experimental results was taken as the final result. The experimental results showed that the weight loss rate of silica particles was 1.5%, and the weight loss rate of modified silica particles was 5.4%.

[0052] Example 8

[0053] The only difference between the solid binder for polyolefins in this embodiment and the solid binder for polyolefins in Example 5 is that the silica particles in this embodiment are replaced with modified silica particles. The preparation method of the modified silica particles is as follows:

[0054] (1) 1,3-bis(tert-butylamino)-2-propanol and tetrahydrofuran in a mass ratio of 2:1 were added to a reaction vessel, stirred evenly, and heated to 50°C. Under stirring, a tetrahydrofuran solution of (1-bromoethyl)cyclohexane (mass fraction of 40%) was added dropwise to the reaction vessel, followed by the addition of a 35% sodium hydroxide solution. After the addition was completed, the material in the reaction vessel was heated to 75°C and stirred for 8 hours. The mixture was then cooled to room temperature, and the reaction product was extracted with dichloromethane. The extracted organic phase was then distilled under reduced pressure to obtain a concentrate. A mixture of petroleum ether and anhydrous ethanol in a volume ratio of 2:1 was then added to the concentrate. The concentrate and mixed solvent (mass ratio of concentrate to mixed solvent is 1:2.5) were placed in a 60℃ water bath and stirred until the concentrate was fully dissolved. The solution was filtered while hot, and the filtrate was allowed to cool naturally to room temperature before being placed in a refrigerator and allowed to stand at 2℃ for 12 hours to crystallize. The solid was then collected by suction filtration using a Buchner funnel. The filter cake was washed twice with a mixed solvent of petroleum ether and anhydrous ethanol (volume ratio 2:1, pre-cooled to 2℃) (each wash using a mixed solvent with a mass ratio of twice the wet weight of the filter cake). Finally, the washed filter cake was placed in a vacuum drying oven and dried under vacuum at 50℃ and -0.08 to -0.09 MPa for 12 hours to obtain tertiary amine alcohol compounds. The molar ratio of 1,3-bis(tert-butylamino)-2-propanol, (1-bromoethyl)cyclohexane, and sodium hydroxide was 1:2:2.5. The structural formula of the tertiary amine alcohol compounds is shown below:

[0055] .

[0056] (2) 1,3-Divinyl-1,1,3,3-tetramethoxydisiloxane and dichloromethane were added to the first stirred tank and stirred until homogeneous to obtain a 20% (w / w) 1,3-divinyl-1,1,3,3-tetramethoxydisiloxane solution; chloro(butoxy)(methyl)silane and dichloromethane were added to the second stirred tank and stirred until homogeneous to obtain a 20% (w / w) chloro(butoxy)(methyl)silane solution; then nitrogen gas was introduced into the second stirred tank and a solid platinum catalyst was added, and the second stirred tank was... The temperature of the materials was controlled at 65℃. Under stirring, a solution of 1,3-divinyl-1,1,3,3-tetramethoxydisiloxane was added dropwise to the second stirred tank. After the addition was complete, the reaction was continued with stirring for 1.5 hours. The solvent was removed by vacuum distillation to obtain a concentrate. Then, hexane (mass ratio of concentrate to hexane was 1:5) was added to the concentrate. The mixture was placed in a 55℃ water bath and stirred until the concentrate was fully dissolved. After removal, it was allowed to cool naturally to room temperature, then placed in an ice-water bath to cool to 0℃. Crystallization was carried out at this constant temperature for 8 hours using a Buchner funnel. The solid was collected by vacuum filtration, and the filter cake was washed twice with n-hexane pre-cooled to 0℃ (the mass of n-hexane used for each wash was twice the wet weight of the filter cake). Finally, the washed filter cake was placed in a vacuum drying oven and dried under vacuum at 45℃ and -0.09MPa for 12 h to obtain a dichlorosiloxane compound; wherein the molar ratio of 1,3-divinyl-1,1,3,3-tetramethoxydisiloxane and chloro(butoxy)(methyl)silane was 1:2.2, and the platinum element in the solid platinum catalyst and the chloro(butoxy)(methyl)silane... The solid platinum catalyst, with a mass ratio of 0.0005:1, was prepared as follows: 2.5 g of polyethylene glycol (PEG400) was dissolved in 35 mL of anhydrous ethanol, and then 4 mL of isopropanol chloroplatinate solution (concentration 0.05 mol / L) was added to obtain a mixture. Then, 5 g of dried 4A molecular sieve was added to the mixture, stirred evenly, and allowed to stand for 24 h. The solvent was removed by vacuum distillation, and the catalyst was dried to obtain a solid platinum catalyst (platinum mass fraction 0.4%). The structure of the chloro(butoxy)(methyl)silane is shown below:

[0057] ;

[0058] The chemical structure of dichlorosiloxane compounds is shown below:

[0059] .

[0060] (3) Add a tertiary amine alcohol compound and anhydrous tetrahydrofuran in a mass ratio of 1:2 to a reaction vessel, then introduce nitrogen gas into the reaction vessel and heat it to 80°C. Under stirring, add a 20% tetrahydrofuran solution of dichlorosiloxane compound by mass to the reaction vessel dropwise. After the addition is completed, continue stirring and reacting for 10 hours. Remove the tetrahydrofuran by vacuum distillation to obtain a concentrate. Then add a mixed solvent consisting of ethyl acetate and petroleum ether in a volume ratio of 1:2 (mass ratio of concentrate to mixed solvent is 1:3) to the concentrate. Place it in a 70°C water bath and stir until the concentrate is fully dissolved. Remove it and allow it to cool naturally. The mixture was cooled to room temperature and then placed in a refrigerator. It was kept at 1°C for 12 hours to allow crystals to settle. The solid was then collected by suction filtration using a Buchner funnel. The filter cake was washed three times with a mixed solvent of ethyl acetate and petroleum ether (volume ratio 1:2), pre-cooled to 1°C (each wash using a mixed solvent mass 1.5 times the wet weight of the filter cake). Finally, the washed filter cake was placed in a vacuum drying oven and dried under vacuum at 55°C and -0.08 to -0.09 MPa for 12 hours to obtain the silane coupling agent. The molar ratio of the tertiary amine alcohol compound to the dichlorosiloxane compound was 2.2:1. The chemical structure of the silane coupling agent is shown below:

[0061] .

[0062] (4) Add silane coupling agent, water and acetic acid to the reactor, stir evenly and let stand for 45 min. Then add silica particles to the reactor and stir at 500 rpm for 9 h. Filter and add the filter cake to ethanol (the mass ratio of wet weight of filter cake to ethanol is 1:5). Stir at 300 rpm for 15 min and filter. Add the obtained filter cake to deionized water again (the mass ratio of wet weight of filter cake to deionized water is 1:5). Stir at 300 rpm for 20 min and filter. Dry the obtained filter cake in a vacuum drying oven at 80℃ and -0.09 MPa for 12 h to obtain modified silica particles. The mass ratio of silica particles, silane coupling agent, water and acetic acid is 1.5:2.4:120:2.5. The silica particles are SiO2-150 and the average specific surface area (BET method) is 150 m². 2 / g, product brand HDK V15CN, supplied by Wacker AG.

[0063] In this embodiment, silica particles and modified silica particles were respectively placed in alumina crucibles and heated from room temperature to 800°C at a heating rate of 10°C / min under high-purity nitrogen purging (purging flow rate of 50 mL / min). The weight loss rate of silica particles and modified silica particles in the range of room temperature to 800°C was recorded. Each sample was tested 3 times, and the average of the 3 experimental results was taken as the final result. The experimental results showed that the weight loss rate of silica particles was 1.5%, and the weight loss rate of modified silica particles was 6.1%.

[0064] Comparative Example 1

[0065] The only difference between the solid binder for polyolefins in this comparative example and the solid binder for polyolefins in Example 1 is that the amount of silica particles in the solid binder for polyolefins in this comparative example is 0.

[0066] Comparative Example 2

[0067] The only difference between the solid binder for polyolefins in this comparative example and the solid binder for polyolefins in Example 4 is that the amount of silica particles in the solid binder for polyolefins in this comparative example is 0.

[0068] Comparative Example 3

[0069] The solid binder for polyolefins in this comparative example is composed of polyacrylate and silica particles in a mass ratio of 90:10.

[0070] The preparation method of the solid binder for polyolefins in this comparative example includes the following steps: Polyacrylate is added to a Hacker internal mixer, the mixer is started, the kneading rotor speed is controlled at 100 rpm, and after 5 minutes, the temperature rises and reaches equilibrium. Then, it is heated to 150°C and kneaded for another 5 minutes. Next, silica particles are added, and kneading and dispersion are continued for 10 minutes. The material is then discharged onto a two-roll mill for rolling and sheet forming to obtain a sheet binder with a thickness of 0.5 mm. The polyacrylate has a melting point of 76°C, the product brand is EMAC SP2260, and it is supplied by Westlake Chemical. The silica particles are SiO2-400, with an average specific surface area (BET method) of 400 m². 2 / g, product brand HDK T40CN, supplied by Wacker AG.

[0071] Comparative Example 4

[0072] The only difference between the solid binder for polyolefins in this comparative example and the solid binder for polyolefins in Comparative Example 3 is that the amount of silica particles in the solid binder for polyolefins in this comparative example is 0.

[0073] Comparative Example 5

[0074] The solid binder for polyolefins in this comparative example is composed of polyurethane resin and silica particles, with a mass ratio of polyurethane resin to silica particles of 90:10.

[0075] The preparation method of the solid binder for polyolefins in this comparative example includes the following steps: Polyurethane resin is added to a Hacker internal mixer, the mixer is started, the kneading rotor speed is controlled at 100 rpm, and after 5 minutes, the temperature rises and reaches equilibrium. Then, it is heated to 150°C and kneaded for another 5 minutes. Next, silica particles are added, and kneading and dispersion are continued for 10 minutes. The mixture is then discharged onto a two-roll mill for rolling and sheet forming to obtain a sheet binder with a thickness of 0.5 mm. The polyurethane resin has a melting point of 80°C, the product brand is Pearlbond 5717NT2, and it is supplied by Lubrizol. The silica particles are SiO2-400 with an average specific surface area (BET method) of 400 m². 2 / g, product brand HDK T40CN, supplied by Wacker AG.

[0076] Comparative Example 6

[0077] The only difference between the solid binder for polyolefins in this comparative example and the solid binder for polyolefins in Comparative Example 5 is that the amount of silica particles in the solid binder for polyolefins in this comparative example is 0.

[0078] Comparative Example 7

[0079] The solid binder for polyolefins in this comparative example is composed of styrene-isoprene block copolymer and chlorinated polypropylene, with a mass ratio of 90:10 between the styrene-isoprene block copolymer and chlorinated polypropylene.

[0080] The preparation method of the solid binder for polyolefins in this comparative example includes the following steps: Styrene-isoprene block copolymer and chlorinated polypropylene are added to a Hacker internal mixer, the mixer is started, the kneading rotor speed is controlled at 100 rpm, after 5 minutes the temperature rises and reaches equilibrium, it is heated to 150℃ and kneaded for another 15 minutes, then discharged onto a two-roll mill for rolling to produce sheet-like binders with a thickness of 0.5 mm. The styrene-isoprene block copolymer (SIS) contains 30% styrene, is product brand Kraton D1124K, and is supplied by Kraton; the chlorinated polypropylene contains 26% chlorine, is product brand Hardlene 13-LLP, and is supplied by Toyobo.

[0081] Comparative Example 8

[0082] The only difference between the solid adhesive for polyolefins in this comparative example and the solid adhesive for polyolefins in Comparative Example 7 is that the styrene-isoprene block copolymer in the solid adhesive for polyolefins in this comparative example is replaced with the polyurethane resin used in Comparative Example 5.

[0083] Comparative Example 9

[0084] The only difference between the solid adhesive for polyolefins in this comparative example and the solid adhesive for polyolefins in Comparative Example 7 is that the styrene-isoprene block copolymer in the solid adhesive for polyolefins in this comparative example is replaced with the polyacrylate used in Comparative Example 3.

[0085] Comparative Example 10

[0086] The only difference between the solid adhesive for polyolefins in this comparative example and the solid adhesive for polyolefins in Comparative Example 7 is that the amount of styrene-isoprene block copolymer in the solid adhesive for polyolefins in this comparative example is 0.

[0087] Comparative Example 11

[0088] The only difference between the solid binder for polyolefins in this comparative example and the solid binder for polyolefins in Example 7 is that in step (1) of the preparation method of the modified silica particles used in the solid binder for polyolefins in this comparative example, (1-bromoethyl)cyclohexane is replaced with (1-bromopropane-2-yl)cyclohexane.

[0089] Comparative Example 12

[0090] The only difference between the solid binder for polyolefins in this comparative example and the solid binder for polyolefins in Example 7 is that in step (2) of the preparation method of the modified silica particles used in the solid binder for polyolefins in this comparative example, chloro(butoxy)(methyl)silane is replaced with dimethylchlorosilane.

[0091] Comparative Example 13

[0092] The only difference between the solid binder for polyolefins in this comparative example and the solid binder for polyolefins in Example 7 is that the silane coupling agent in step (4) of the preparation method of the modified silica particles used in the solid binder for polyolefins in this comparative example is tert-butyltrimethoxysilane.

[0093] Comparative Example 14

[0094] The only difference between the solid binder for polyolefins in this comparative example and the solid binder for polyolefins in Example 7 is that the silane coupling agent in step (4) of the preparation method of the modified silica particles used in the solid binder for polyolefins in this comparative example is cyclohexyltrimethoxysilane.

[0095] Example of effect

[0096] To evaluate the bonding effect of the solid adhesives of the various embodiments and comparative examples on polyolefin resins, the solid adhesives of the various embodiments and comparative examples were cut into strips with a size of 50mm × 50mm, and then placed between two pieces of untreated polypropylene material. They were then hot-pressed for 2 minutes at 160°C and 0.1MPa in a hot press to obtain a layered adhesive composite with a three-layer structure of polypropylene layer / solid adhesive layer / polypropylene layer. After hot pressing, the composite was cooled to room temperature, and then cut into strips 2.5mm wide along the thickness direction for adhesive performance testing.

[0097] The adhesion performance tests included peel force, flexural strength, and shear strength tests. The peel force test was conducted as follows: The upper and lower polypropylene layers of a strip sample were clamped in an electronic universal testing machine using two clamps. Peeling was performed at a speed of 100 mm / min, and the average peel force was recorded. Each sample was tested three times, and the average value was calculated. Flexural strength and shear strength were tested using a universal testing machine. Each sample was tested three times, and the average of the three test results was taken as the final result. When testing the same performance index, it was ensured that the production batch and thickness of the polypropylene materials forming the upper and lower polypropylene layers, as well as the thickness of the intermediate solid adhesive layer, were the same in different layered adhesive composites to avoid affecting the comparison effect between different solid adhesives. For the peel force test, the polypropylene material was a 0.3 mm thick polypropylene film; for the flexural strength and shear strength tests, the polypropylene material was a polypropylene sheet. The adhesion effects of the solid adhesives to the polypropylene materials in each embodiment and comparative example are shown in Table 1.

[0098] Table 1. Bonding effect of solid binders on polypropylene materials in each embodiment and comparative example.

[0099]

[0100] Note: "-" indicates that it has not been tested.

[0101] As shown in Table 1, the solid adhesive of the present invention exhibits excellent adhesion to the polypropylene substrate after hot pressing, significantly improving the flexural and shear strength of the polypropylene layered material. The peel force between the solid adhesive and the polypropylene substrate is greater than 58 N / 25 mm, and the resulting polypropylene layered material has a flexural strength greater than 39 MPa and a shear strength greater than 14 MPa.

[0102] As demonstrated in Examples 1, 4, and Comparative Examples 1-2, compared to using styrene-isoprene block copolymers and styrene-butadiene random copolymer rubbers alone, using styrene-isoprene block copolymers, styrene-butadiene random copolymer rubbers, and silica particles simultaneously can effectively improve the bonding strength of the solid adhesive to the polypropylene substrate, as well as the flexural and shear strength of the polypropylene layered material. This is because the silica particles filled in the solid adhesive can reduce the internal stress generated during adhesive bonding, while the inorganic silica particles can enhance the strength of the adhesive layer in the layered material, thereby improving the flexural and shear strength of the layered material.

[0103] As shown in Comparative Examples 3-6, replacing the resin in the solid adhesive with polyacrylate or polyurethane resin worsens the bonding performance of the solid adhesive to polypropylene materials. This indicates that polyacrylate or polyurethane resins have high polarity and weak affinity with the polyolefin substrate, making them unable to effectively bond polypropylene materials. Furthermore, adding silica particles to the polyacrylate further worsens the bonding performance of the solid adhesive to polypropylene materials, suggesting that internal stress is not the primary factor affecting the bonding strength of polyacrylate to polypropylene materials. Adding silica particles to the polyurethane resin does not significantly improve the bonding performance of the solid adhesive to polypropylene materials, indicating that silica particles need to be matched with specific polymer resins to effectively improve the bonding performance of the polymer resin to polypropylene materials.

[0104] As shown in Comparative Examples 7-10, when chlorinated polypropylene with a structure similar to that of polypropylene is added to styrene-isoprene block copolymers, styrene-butadiene random copolymer rubbers, polyacrylates, or polyurethane resins, the bonding strength of the solid binder to the polypropylene material is indeed improved compared to using the resin matrix alone. However, the improvement is limited and far lower than the improvement of the resin matrix by silica particles.

[0105] As shown in Examples 7 and Comparative Examples 11-14, when the silane coupling agent used to modify silica particles is replaced with tert-butyltrimethoxysilane or cyclohexyltrimethoxysilane, or when the end-branched cyclohexyl groups in the silane coupling agent are replaced with tert-butyl groups and the butoxy groups on the silicon atoms are replaced with methyl groups, the bonding strength of the solid binder to the polypropylene material is significantly reduced. This indicates that not all organosilane coupling agents can effectively improve the bonding performance of the solid binder and the flexural and shear strength of the high-layer materials after modifying silica particles. According to the experimental results, the silane coupling agent containing end-branched cyclohexyl, tert-butyl, and butoxy structures used in this invention to modify silica particles can graft a large number of branched cyclohexyl and tert-butyl structures onto the surface of the silica particles. These structures can be tightly bonded to the organic resin in the solid binder through physical winding, embedding, etc., and when hot-pressed with polypropylene material, they can improve the gripping force on polypropylene and increase the flexural and shear strength of the high-layer materials.

[0106] 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. A solid binder for polyolefins, characterized in that, It is composed of a polymer resin matrix and a solid filler, wherein the mass ratio of the polymer resin matrix to the solid filler is 80~95:5~20. The polymer resin matrix is ​​a styrene-isoprene block copolymer or a styrene-butadiene random copolymer rubber. The solid filler is silica particles or modified silica particles. The modified silica particles are obtained by modifying silica powder with a silane coupling agent. The chemical structure of the silane coupling agent is shown below: 。 2. The solid binder for polyolefins according to claim 1, characterized in that, The modified silica particles are prepared as follows: silane coupling agent, water and acetic acid are mixed and allowed to stand for 30-45 minutes, then silica powder is added and the mixture is reacted for 6-9 hours to obtain modified silica particles.

3. The solid binder for polyolefins according to claim 2, characterized in that, The mass ratio of the silica powder, silane coupling agent, water, and acetic acid is 1.2~1.5:1.8~2.4:100~120:1.9~2.

5.

4. The solid binder for polyolefins according to any one of claims 1-3, characterized in that, The silane coupling agent is prepared as follows: 1,3-bis(tert-butylamino)-2-propanol and (1-bromoethyl)cyclohexane are mixed and reacted to obtain a tertiary amine alcohol compound; then, the tertiary amine alcohol compound and a dichlorosiloxane compound are mixed and reacted to obtain the silane coupling agent; the molar ratio of 1,3-bis(tert-butylamino)-2-propanol and (1-bromoethyl)cyclohexane is 1:2, and the molar ratio of the tertiary amine alcohol compound and the dichlorosiloxane compound is 2.1~2.2:1; the structure of the tertiary amine alcohol compound is as follows: ； The structure of the dichlorosiloxane compound is as follows: 。 5. The solid binder for polyolefins according to claim 4, characterized in that, The preparation method of the dichlorosiloxane compound is as follows: 1,3-divinyl-1,1,3,3-tetramethoxydisiloxane and chloro(butoxy)(methyl)silane are mixed and reacted under the action of a platinum catalyst to obtain the dichlorosiloxane compound; the molar ratio of 1,3-divinyl-1,1,3,3-tetramethoxydisiloxane and chloro(butoxy)(methyl)silane is 1:2.1~2.

2.

6. The solid binder for polyolefins according to claim 4, characterized in that, The temperature for mixing and reacting 1,3-bis(tert-butylamino)-2-propanol and (1-bromoethyl)cyclohexane is 65-75℃, and the time is 5-8h.

7. The solid binder for polyolefins 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.

8. The solid binder for polyolefins according to claim 1, characterized in that, The styrene-isoprene block copolymer contains 25-30% styrene.

9. The solid binder for polyolefins according to claim 1, characterized in that, The styrene-butadiene random copolymer rubber contains 23.5% to 28% styrene.

10. A method for preparing a solid binder for polyolefins as described in any one of claims 1-9, characterized in that, Includes the following steps: After the polymer resin matrix is ​​intensively mixed, it is kneaded with solid fillers to obtain a solid binder for polyolefins.

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