A PETG co-extruded composite sheet and its preparation method

Abstract

This invention discloses a PETG co-extruded composite sheet and its preparation method. The method involves adding extruder and APET masterbatch to an extruder, then layering and combining the extruder melt and APET masterbatch melt to form a composite melt with an upper and lower layer of extruder and a middle layer of APET masterbatch. This is then shaped by roller pressing to obtain the PETG co-extruded composite sheet. During the blending process of modified polyester and modified filler, the epoxy group structure in the modified polyester molecule can react with the secondary amine in the modified filler, resulting in mild cross-linking and increasing the strength of the polyester material. The modified polyester molecular chain contains polysiloxane segments, and also has polysiloxane segments branched onto its side links. When impacted, the flexible polysiloxane segments absorb and dissipate a large amount of energy through violent movement, rotation, and entanglement. Furthermore, the nano-reinforcing points formed by the cage-like silsesquioxane structure within the molecule contribute to the excellent scratch resistance of the prepared composite sheet.

Description

Technical Field

[0001] This invention relates to the field of composite board preparation technology, specifically to a PETG co-extruded composite board and its preparation method. Background Technology

[0002] PETG co-extruded composite sheets are an advanced multilayer composite material that has rapidly developed in the field of high-performance transparent engineering plastics in recent years. Through a co-extrusion molding process, PETG (polyethylene terephthalate-1,4-cyclohexanediol ester) is compounded with other polymer materials (such as APET, EVOH, TPU, etc.) in a molten state to form sheets or plates with a variety of excellent properties. These sheets are widely used in high-end packaging, architectural decoration, advertising signage, medical protective equipment, and automotive interiors. Traditional PETG possesses excellent optical and mechanical properties, impact strength, excellent processability, and good weather and chemical resistance. However, pure PETG material also has some inherent limitations, such as relatively low surface hardness, making it prone to scratches, which seriously affects the normal use of its products.

[0003] Environmental protection and safety Summary of the Invention

[0004] The purpose of this invention is to provide a PETG co-extruded composite sheet and its preparation method, which solves the problem that the PETG layer on the surface of the current PETG co-extruded composite sheet is prone to scratches.

[0005] The objective of this invention can be achieved through the following technical solutions: A method for preparing a PETG co-extruded composite sheet includes the following steps: Step A1: Terephthalic acid, modifying additives, ethylene glycol, 1,4-cyclohexanediol and tetrabutyl titanate are mixed and purged with nitrogen. The mixture is reacted for 2-4 hours at a rotation speed of 150-200 r / min and a temperature of 200-210℃. Then, the temperature is raised to 260-270℃, and antimony trioxide and triphenyl phosphate are added. The temperature is further raised to 280-285℃ and the mixture is reacted for 2-3 hours at a pressure of 80-100 Pa to obtain the modified copolyester. Step A2: Mix octaphenyl cage-type polysilsesquioxane, tetrahydrofuran, and tetraethylammonium hydroxide aqueous solution, and react for 3-5 hours at a speed of 150-120 r / min and a temperature of 66-70℃. Then, add dilute hydrochloric acid to neutralize and obtain pretreated silsesquioxane. Mix the pretreated silsesquioxane, vinyltrichlorosilane, triethylamine, and toluene evenly and react for 3-5 hours at a speed of 200-300 r / min and a temperature of 50-60℃ to obtain modified silsesquioxane. Step A3: Mix modified silsesquioxane, sodium methoxide, triethylenetetramine, and xylene, and react for 3-5 hours at a speed of 200-300 r / min and a temperature of 80-85℃ to obtain modified filler. Mix modified copolyester and modified filler to obtain extrudate. Add extrudate and APET masterbatch to an extruder separately. Combine the extrudate melt and APET masterbatch melt in layers to form a composite melt with extrudate as the upper and lower layers and APET masterbatch as the middle layer. Then, shape with pressure rollers to obtain PETG co-extruded composite sheet.

[0006] Further, in step A1, the molar ratio of terephthalic acid, modifying additive, ethylene glycol, and 1,4-cyclohexanediethanol is 5:0.5:6:3.5; the amount of tetrabutyl titanate is 0.05% of the total mass of terephthalic acid, modifying additive, ethylene glycol, and 1,4-cyclohexanediethanol; the amount of antimony trioxide is 0.05% of the total mass of terephthalic acid, modifying additive, ethylene glycol, and 1,4-cyclohexanediethanol; and the amount of triphenyl phosphate is 0.01% of the total mass of terephthalic acid, modifying additive, ethylene glycol, and 1,4-cyclohexanediethanol.

[0007] Furthermore, in step A2, the volume ratio of the octaphenyl cage-type polysilsesquioxane, tetrahydrofuran, and tetraethylammonium hydroxide aqueous solution is 5:125:2, the mass fraction of the tetraethylammonium hydroxide aqueous solution is 35%, and the molar ratio of the pretreated silsesquioxane, vinyltrichlorosilane, and triethylamine is 1:1.1:3.5.

[0008] Furthermore, in step A3, the molar ratio of modified silsesquioxane to triethylenetetramine is 1:0.5-1, the amount of sodium methoxide is 0.05% of the mass of triethylenetetramine, the weight ratio of modified copolyester to modified filler is 90-100:10-15, and the mass ratio of extruded material to APET masterbatch is 1:3.

[0009] Furthermore, the modified additive is prepared by the following steps: Step B1: Mix octamethylcyclotetrasiloxane, tetramethyldisiloxane, tetramethylammonium hydroxide and dimethyl sulfoxide, and purge with nitrogen. React at 150-200 r / min and 90-95℃ for 10-12 h, then raise the temperature to 105-110℃ and continue the reaction for 2-3 h to obtain dihydropolysiloxane. Mix dihydropolysiloxane, diethylenedichlorosilane, caster catalyst and xylene, and purge with nitrogen. React at 150-200 r / min and 80-85℃ for 6-8 h to obtain pretreated polysiloxane. Step B2: Lithium dimethylhydrosilylsiloxane and tetrahydrofuran are mixed and protected under nitrogen. The mixture is stirred at 200-300 rpm and 0°C, and hexamethylcyclotrisiloxane is added. The mixture is heated to 25-30°C and reacted for 7-9 hours. Pretreated polysiloxane is then added, and the reaction continues for 3-5 hours to obtain modified polysiloxane. The modified polysiloxane, mercaptoethanol, benzophenone, and xylene are mixed and protected under nitrogen. The mixture is reacted at 300-500 rpm and 20-25°C under 365 nm ultraviolet light irradiation for 20-30 minutes to obtain hydroxyl polysiloxane. Step B3: Mix hydroxyl polysiloxane, glycidyl methacrylate, caster catalyst and xylene, purge with nitrogen, and react for 6-8 hours at a speed of 150-200 r / min and a temperature of 80-85℃ to obtain the modified additive.

[0010] Furthermore, in step B1, the molar ratio of octamethylcyclotetrasiloxane, tetramethyldisiloxane, and tetramethylammonium hydroxide is 1.2:1:1.5, the molar ratio of dihydropolysiloxane and divinyldichlorosilane is n:n+1, where n is a natural number greater than 0, and the amount of cassette catalyst is 0.01% of the mass of divinyldichlorosilane.

[0011] Furthermore, in step B2, the molar ratio of the Si-Cl bonds on the lithium dimethylhydrosiloxane, hexamethylcyclotrisiloxane, and pretreated polysiloxane is 1:5:1, the molar ratio of the modified polysiloxane and mercaptoethanol is 1:2, and the amount of benzophenone used is 0.02% of the mass of mercaptoethanol.

[0012] Furthermore, in step B3, the molar ratio of the Si-H bond on the hydroxyl polysiloxane to glycidyl methacrylate is 1:1, and the amount of caster catalyst used is 0.01% of the mass of glycidyl methacrylate.

[0013] The beneficial effects of this invention: This invention discloses a PETG co-extruded composite sheet, in which extruder and APET masterbatch are added separately to an extruder, and the extruder melt and APET masterbatch melt are layered and merged to form a composite melt with the upper and lower layers being extruder and the middle layer being APET masterbatch. The melt is then shaped by pressure rollers to obtain the PETG co-extruded composite sheet. The extruder includes modified copolyester and modified filler. The modified copolyester is prepared by condensation of terephthalic acid, modifying additives, ethylene glycol, and 1,4-cyclohexanediethanol ester. The ester-modified filler is prepared by treating octaphenyl cage-type silsesquioxane with tetraethylammonium hydroxide aqueous solution to open the vertices, thus obtaining pretreated silsesquioxane. The pretreated silsesquioxane is then reacted with vinyltrichlorosilane to cap the Si-OH bonds on the pretreated silsesquioxane with the Si-Cl bonds on the vinyltrichlorosilane, thus obtaining modified silsesquioxane. The modified silsesquioxane is then reacted with triethylenetetramine to react the double bonds on the modified silsesquioxane with the primary amine on the triethylenetetramine, thus obtaining the modified filler.

[0014] The modified additive uses octamethylcyclotetrasiloxane as a raw material for ring-opening polymerization, followed by end-capping with tetramethyldisiloxane to obtain dihydropolysiloxane. The dihydropolysiloxane is then reacted with divinyldichlorosilane, causing the Si-H bonds on the dihydropolysiloxane to react with the double bonds on the divinyldichlorosilane, yielding a pretreated polysiloxane. Dimethylhydrosilyllithium is used as an initiator, and hexamethylcyclotrisiloxane is used as a polymerization monomer to form a polysiloxane with one end hydrogen and the other end lithium silanolate. Further additives are then added... Pre-treating polysiloxanes allows the Si-Cl bonds on the pre-treated polysiloxanes to react with lithium silanolates, yielding modified polysiloxanes. Reacting the modified polysiloxanes with mercaptoethanol allows the double bonds on the modified polysiloxanes to react with the mercapto groups on the mercaptoethanol under ultraviolet light, yielding hydroxyl polysiloxanes. Reacting the hydroxyl polysiloxanes with glycidyl methacrylate allows the Si-H bonds on the hydroxyl polysiloxanes to react with the glycidyl methacrylate double bonds, yielding a modified additive.

[0015] During the blending process of modified polyester and modified filler, the epoxy structure in the modified polyester molecule can react with the secondary amine in the modified filler, resulting in mild cross-linking, which increases the strength of the polyester material. The modified polyester molecular chain contains polysiloxane segments, and the side links also have polysiloxane segments. When subjected to impact, the flexible polysiloxane segments absorb and dissipate a large amount of energy through violent movement, rotation and entanglement. In addition, the nano-reinforcing points formed by the cage-like silsesquioxane structure in the molecule, together with the nano-reinforcing points, make the prepared composite board have a good scratch resistance. Detailed Implementation

[0016] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Example 1: A method for preparing a PETG co-extruded composite sheet, specifically including the following steps: Step A1: Terephthalic acid, modifying additives, ethylene glycol, 1,4-cyclohexanediol and tetrabutyl titanate are mixed and purged with nitrogen. The mixture is reacted for 2 hours at a speed of 150 r / min and a temperature of 200℃. Then, the temperature is raised to 260℃, antimony trioxide and triphenyl phosphate are added, and the temperature is raised to 280℃. The mixture is then reacted for 2 hours at a pressure of 80 Pa to obtain the modified copolyester. Step A2: Mix octaphenyl cage-type polysilsesquioxane, tetrahydrofuran, and tetraethylammonium hydroxide aqueous solution, and react for 3 hours at a speed of 150 r / min and a temperature of 66℃. Then, add dilute hydrochloric acid to neutralize and obtain pretreated silsesquioxane. Mix the pretreated silsesquioxane, vinyltrichlorosilane, triethylamine, and toluene evenly and react for 3 hours at a speed of 200 r / min and a temperature of 50℃ to obtain modified silsesquioxane. Step A3: Mix modified silsesquioxane, sodium methoxide, triethylenetetramine, and xylene, and react for 3 hours at a speed of 200 r / min and a temperature of 80°C to obtain modified filler. Mix modified copolyester and modified filler to obtain extrudate. Add extrudate and APET masterbatch to an extruder separately. Combine the extrudate melt and APET masterbatch melt in layers to form a composite melt with extrudate as the upper and lower layers and APET masterbatch as the middle layer. Then, shape with pressure rollers to obtain PETG co-extruded composite sheet.

[0018] The molar ratio of terephthalic acid, modifying additive, ethylene glycol, and 1,4-cyclohexanediethanol in step A1 is 5:0.5:6:3.5. The amount of tetrabutyl titanate is 0.05% of the total mass of terephthalic acid, modifying additive, ethylene glycol, and 1,4-cyclohexanediethanol. The amount of antimony trioxide is 0.05% of the total mass of terephthalic acid, modifying additive, ethylene glycol, and 1,4-cyclohexanediethanol. The amount of triphenyl phosphate is 0.01% of the total mass of terephthalic acid, modifying additive, ethylene glycol, and 1,4-cyclohexanediethanol.

[0019] The volume ratio of the octaphenyl cage-type polysilsesquioxane, tetrahydrofuran, and tetraethylammonium hydroxide aqueous solution in step A2 is 5:125:2, the mass fraction of the tetraethylammonium hydroxide aqueous solution is 35%, and the molar ratio of the pretreated silsesquioxane, vinyltrichlorosilane, and triethylamine is 1:1.1:3.5.

[0020] The molar ratio of modified silsesquioxane and triethylenetetramine in step A3 is 1:0.5, the amount of sodium methoxide is 0.05% of the mass of triethylenetetramine, the weight ratio of modified copolyester and modified filler is 90:10, and the mass ratio of extruded material to APET masterbatch is 1:3.

[0021] The modified additive is prepared by the following steps: Step B1: Octamethylcyclotetrasiloxane, tetramethyldisiloxane, tetramethylammonium hydroxide and dimethyl sulfoxide are mixed, and nitrogen gas is introduced for protection. The mixture is reacted at 150 r / min and 90 °C for 10 h. Then the temperature is raised to 105 °C and the reaction is continued for 2 h to obtain dihydropolysiloxane. Dihydropolysiloxane, diethylenedichlorosilane, caster catalyst and xylene are mixed, and nitrogen gas is introduced for protection. The mixture is reacted at 150 r / min and 80 °C for 6 h to obtain pretreated polysiloxane. Step B2: Lithium dimethylhydrosilyl alcohol and tetrahydrofuran were mixed and protected with nitrogen. Under the conditions of 200 r / min and 0°C, hexamethylcyclotrisiloxane was added while stirring. The temperature was raised to 25°C and the reaction was carried out for 7 h. Pretreated polysiloxane was added and the reaction was continued for 3 h to obtain modified polysiloxane. Modified polysiloxane, mercaptoethanol, benzophenone and xylene were mixed and protected with nitrogen. Under the conditions of 300 r / min, 20°C and 365 nm ultraviolet light irradiation, the reaction was carried out for 20 min to obtain hydroxyl polysiloxane. Step B3: Mix hydroxyl polysiloxane, glycidyl methacrylate, caster catalyst and xylene, purge with nitrogen, and react for 6 hours at a speed of 150 r / min and a temperature of 80 °C to obtain the modified additive.

[0022] In step B1, the molar ratio of octamethylcyclotetrasiloxane, tetramethyldisiloxane, and tetramethylammonium hydroxide is 1.2:1:1.5, the molar ratio of dihydropolysiloxane and divinyldichlorosilane is 1:2, and the amount of caster catalyst is 0.01% of the mass of divinyldichlorosilane.

[0023] In step B2, the molar ratio of lithium dimethylhydrosiloxane, hexamethylcyclotrisiloxane, and the Si-Cl bond on the pretreated polysiloxane is 1:5:1, the molar ratio of modified polysiloxane and mercaptoethanol is 1:2, and the amount of benzophenone used is 0.02% of the mass of mercaptoethanol.

[0024] In step B3, the molar ratio of Si-H bonds on the hydroxyl polysiloxane to glycidyl methacrylate is 1:1, and the amount of caster catalyst used is 0.01% of the mass of glycidyl methacrylate.

[0025] Example 2, a method for preparing a PETG co-extruded composite sheet, specifically includes the following steps: Step A1: Terephthalic acid, modifying additives, ethylene glycol, 1,4-cyclohexanediol and tetrabutyl titanate are mixed and purged with nitrogen. The mixture is reacted for 3 hours at a speed of 150 r / min and a temperature of 205℃. Then, the temperature is raised to 265℃, antimony trioxide and triphenyl phosphate are added, and the temperature is further raised to 280℃. The mixture is then reacted for 2.5 hours at a pressure of 90 Pa to obtain the modified copolyester. Step A2: Mix octaphenyl cage-type polysilsesquioxane, tetrahydrofuran, and tetraethylammonium hydroxide aqueous solution, and react for 4 hours at a speed of 150 r / min and a temperature of 70℃. Then, add dilute hydrochloric acid to neutralize and obtain pretreated silsesquioxane. Mix the pretreated silsesquioxane, vinyltrichlorosilane, triethylamine, and toluene evenly and react for 4 hours at a speed of 200 r / min and a temperature of 55℃ to obtain modified silsesquioxane. Step A3: Mix modified silsesquioxane, sodium methoxide, triethylenetetramine, and xylene, and react for 4 hours at a speed of 200 r / min and a temperature of 85°C to obtain modified filler. Mix modified copolyester and modified filler to obtain extrudate. Add extrudate and APET masterbatch to an extruder separately. Combine the extrudate melt and APET masterbatch melt in layers to form a composite melt with extrudate as the upper and lower layers and APET masterbatch as the middle layer. Then, shape with pressure rollers to obtain PETG co-extruded composite sheet.

[0026] The molar ratio of terephthalic acid, modifying additive, ethylene glycol, and 1,4-cyclohexanediethanol in step A1 is 5:0.5:6:3.5. The amount of tetrabutyl titanate is 0.05% of the total mass of terephthalic acid, modifying additive, ethylene glycol, and 1,4-cyclohexanediethanol. The amount of antimony trioxide is 0.05% of the total mass of terephthalic acid, modifying additive, ethylene glycol, and 1,4-cyclohexanediethanol. The amount of triphenyl phosphate is 0.01% of the total mass of terephthalic acid, modifying additive, ethylene glycol, and 1,4-cyclohexanediethanol.

[0027] The volume ratio of the octaphenyl cage-type polysilsesquioxane, tetrahydrofuran, and tetraethylammonium hydroxide aqueous solution in step A2 is 5:125:2, the mass fraction of the tetraethylammonium hydroxide aqueous solution is 35%, and the molar ratio of the pretreated silsesquioxane, vinyltrichlorosilane, and triethylamine is 1:1.1:3.5.

[0028] The molar ratio of modified silsesquioxane and triethylenetetramine in step A3 is 1:0.8, the amount of sodium methoxide is 0.05% of the mass of triethylenetetramine, the weight ratio of modified copolyester and modified filler is 95:13, and the mass ratio of extruded material to APET masterbatch is 1:3.

[0029] The modified additive is prepared by the following steps: Step B1: Octamethylcyclotetrasiloxane, tetramethyldisiloxane, tetramethylammonium hydroxide and dimethyl sulfoxide are mixed, and nitrogen gas is introduced for protection. The mixture is reacted at 150 r / min and 95 °C for 10 h. Then the temperature is raised to 110 °C and the reaction is continued for 3 h to obtain dihydropolysiloxane. Dihydropolysiloxane, diethylenedichlorosilane, caster catalyst and xylene are mixed, and nitrogen gas is introduced for protection. The mixture is reacted at 150 r / min and 85 °C for 7 h to obtain pretreated polysiloxane. Step B2: Lithium dimethylhydrosilyl alcohol and tetrahydrofuran were mixed and protected with nitrogen. Under the conditions of 200 r / min and 0°C, hexamethylcyclotrisiloxane was added while stirring. The temperature was raised to 25°C and the reaction was carried out for 8 h. Pretreated polysiloxane was added and the reaction was continued for 4 h to obtain modified polysiloxane. Modified polysiloxane, mercaptoethanol, benzophenone and xylene were mixed and protected with nitrogen. Under the conditions of 300 r / min, 25°C and 365 nm ultraviolet light irradiation, the reaction was carried out for 25 min to obtain hydroxyl polysiloxane. Step B3: Mix hydroxyl polysiloxane, glycidyl methacrylate, caster catalyst and xylene, purge with nitrogen, and react for 7 h at a speed of 200 r / min and a temperature of 80 °C to obtain the modified additive.

[0030] In step B1, the molar ratio of octamethylcyclotetrasiloxane, tetramethyldisiloxane, and tetramethylammonium hydroxide is 1.2:1:1.5, the molar ratio of dihydropolysiloxane and divinyldichlorosilane is 2:3, and the amount of caster catalyst is 0.01% of the mass of divinyldichlorosilane.

[0031] In step B2, the molar ratio of lithium dimethylhydrosiloxane, hexamethylcyclotrisiloxane, and the Si-Cl bond on the pretreated polysiloxane is 1:5:1, the molar ratio of modified polysiloxane and mercaptoethanol is 1:2, and the amount of benzophenone used is 0.02% of the mass of mercaptoethanol.

[0032] In step B3, the molar ratio of Si-H bonds on the hydroxyl polysiloxane to glycidyl methacrylate is 1:1, and the amount of caster catalyst used is 0.01% of the mass of glycidyl methacrylate.

[0033] Example 3, a method for preparing a PETG co-extruded composite sheet, specifically includes the following steps: Step A1: Terephthalic acid, modifying additives, ethylene glycol, 1,4-cyclohexanediol and tetrabutyl titanate are mixed and purged with nitrogen. The mixture is reacted for 4 hours at a speed of 200 r / min and a temperature of 210°C. Then, the temperature is raised to 270°C, and antimony trioxide and triphenyl phosphate are added. The temperature is further raised to 285°C and the mixture is reacted for 3 hours at a pressure of 100 Pa to obtain the modified copolyester. Step A2: Mix octaphenyl cage-type polysilsesquioxane, tetrahydrofuran, and tetraethylammonium hydroxide aqueous solution, and react for 5 hours at a speed of 120 r / min and a temperature of 70℃. Then, add dilute hydrochloric acid to neutralize and obtain pretreated silsesquioxane. Mix the pretreated silsesquioxane, vinyltrichlorosilane, triethylamine, and toluene evenly and react for 5 hours at a speed of 300 r / min and a temperature of 60℃ to obtain modified silsesquioxane. Step A3: Mix modified silsesquioxane, sodium methoxide, triethylenetetramine, and xylene, and react for 5 hours at a speed of 300 r / min and a temperature of 85°C to obtain modified filler. Mix modified copolyester and modified filler to obtain extrudate. Add extrudate and APET masterbatch to an extruder separately. Combine the extrudate melt and APET masterbatch melt in layers to form a composite melt with extrudate as the upper and lower layers and APET masterbatch as the middle layer. Then, shape with pressure rollers to obtain PETG co-extruded composite sheet.

[0034] The molar ratio of terephthalic acid, modifying additive, ethylene glycol, and 1,4-cyclohexanediethanol in step A1 is 5:0.5:6:3.5. The amount of tetrabutyl titanate is 0.05% of the total mass of terephthalic acid, modifying additive, ethylene glycol, and 1,4-cyclohexanediethanol. The amount of antimony trioxide is 0.05% of the total mass of terephthalic acid, modifying additive, ethylene glycol, and 1,4-cyclohexanediethanol. The amount of triphenyl phosphate is 0.01% of the total mass of terephthalic acid, modifying additive, ethylene glycol, and 1,4-cyclohexanediethanol.

[0035] The volume ratio of the octaphenyl cage-type polysilsesquioxane, tetrahydrofuran, and tetraethylammonium hydroxide aqueous solution in step A2 is 5:125:2, the mass fraction of the tetraethylammonium hydroxide aqueous solution is 35%, and the molar ratio of the pretreated silsesquioxane, vinyltrichlorosilane, and triethylamine is 1:1.1:3.5.

[0036] The molar ratio of modified silsesquioxane and triethylenetetramine in step A3 is 1:1, the amount of sodium methoxide is 0.05% of the mass of triethylenetetramine, the weight ratio of modified copolyester and modified filler is 100:15, and the mass ratio of extruded material to APET masterbatch is 1:3.

[0037] The modified additive is prepared by the following steps: Step B1: Octamethylcyclotetrasiloxane, tetramethyldisiloxane, tetramethylammonium hydroxide and dimethyl sulfoxide are mixed and purged with nitrogen. The mixture is reacted at 200 r / min and 95 °C for 12 h. The temperature is then raised to 110 °C and the reaction is continued for 3 h to obtain dihydropolysiloxane. Dihydropolysiloxane, diethylenedichlorosilane, caster catalyst and xylene are mixed and purged with nitrogen. The mixture is reacted at 200 r / min and 85 °C for 8 h to obtain pretreated polysiloxane. Step B2: Lithium dimethylhydrosilylsiloxane and tetrahydrofuran were mixed and protected with nitrogen. Under the conditions of 300 r / min and 0°C, hexamethylcyclotrisiloxane was added while stirring. The temperature was raised to 30°C and the reaction was carried out for 9 h. Pretreated polysiloxane was added and the reaction was continued for 5 h to obtain modified polysiloxane. Modified polysiloxane, mercaptoethanol, benzophenone and xylene were mixed and protected with nitrogen. Under the conditions of 500 r / min, 25°C and 365 nm ultraviolet light irradiation, the reaction was carried out for 30 min to obtain hydroxyl polysiloxane. Step B3: Mix hydroxyl polysiloxane, glycidyl methacrylate, caster catalyst and xylene, purge with nitrogen, and react for 8 hours at a speed of 200 r / min and a temperature of 85℃ to obtain the modified additive.

[0038] In step B1, the molar ratio of octamethylcyclotetrasiloxane, tetramethyldisiloxane, and tetramethylammonium hydroxide is 1.2:1:1.5, the molar ratio of dihydropolysiloxane and divinyldichlorosilane is 3:4, and the amount of caster catalyst is 0.01% of the mass of divinyldichlorosilane.

[0039] In step B2, the molar ratio of lithium dimethylhydrosiloxane, hexamethylcyclotrisiloxane, and the Si-Cl bond on the pretreated polysiloxane is 1:5:1, the molar ratio of modified polysiloxane and mercaptoethanol is 1:2, and the amount of benzophenone used is 0.02% of the mass of mercaptoethanol.

[0040] In step B3, the molar ratio of Si-H bonds on the hydroxyl polysiloxane to glycidyl methacrylate is 1:1, and the amount of caster catalyst used is 0.01% of the mass of glycidyl methacrylate.

[0041] Comparative Example 1: This comparative example uses triethylenetetramine instead of the modified filler, but the other steps are the same as in Example 1.

[0042] Comparative Example 2: This comparative example uses hydroxyl polysiloxane instead of the modifying additives, while the remaining steps are the same as in Example 1.

[0043] Comparative Example 3: This comparative example uses dihydropolysiloxane instead of hydroxyl polysiloxane, while the remaining steps are the same as in Example 1.

[0044] The composite boards prepared in Examples 1-3 and Comparative Examples 1-3 were tested for surface hardness at temperatures of 25℃, 50℃ and 80℃, respectively, in accordance with the standard GB / T 6739-2022. The test results are shown in Table 1 below.

[0045] Table 1

[0046] As shown in Table 1, this application has excellent scratch resistance and high temperature resistance.

[0047] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing a PETG co-extruded composite sheet, characterized in that: Specifically, the steps include: adding the extruded material and APET masterbatch into the extruder respectively, then layering and combining the extruded material melt and APET masterbatch melt to form a composite melt with the upper and lower layers being extruded material and the middle layer being APET masterbatch, and then shaping it with pressure rollers to obtain PETG co-extruded composite sheet.

2. The method for preparing PETG co-extruded composite sheet according to claim 1, characterized in that: The mass ratio of the extruded material to the APET masterbatch is 1:

3.

3. The method for preparing PETG co-extruded composite sheet according to claim 1, characterized in that: Step A1: Mix octaphenyl cage-type polysilsesquioxane, tetrahydrofuran and tetraethylammonium hydroxide aqueous solution, react and then add dilute hydrochloric acid to neutralize, to obtain pretreated silsesquioxane. Mix the pretreated silsesquioxane, vinyltrichlorosilane, triethylamine and toluene and react to obtain modified silsesquioxane. Step A2: Terephthalic acid, modifying additives, ethylene glycol, 1,4-cyclohexanediethanol and tetrabutyl titanate are mixed and reacted under nitrogen protection. Then, antimony trioxide and triphenyl phosphate are added and reacted to obtain a modified copolyester. Modified silsesquioxane, sodium methoxide, triethylenetetramine and xylene are mixed and reacted to obtain a modified filler. The modified copolyester and the modified filler are mixed to obtain an extruded material.

4. The method for preparing PETG co-extruded composite sheet according to claim 3, characterized in that: The volume ratio of the octaphenyl cage-type polysilsesquioxane, tetrahydrofuran, and tetraethylammonium hydroxide aqueous solution in step A1 is 5:125:2, and the molar ratio of the pretreated silsesquioxane, vinyltrichlorosilane, and triethylamine is 1:1.1:3.

5.

5. The method for preparing PETG co-extruded composite sheet according to claim 3, characterized in that: The molar ratio of terephthalic acid, modified additive, ethylene glycol and 1,4-cyclohexanediethanol in step A1 is 5:0.5:6:3.5, the molar ratio of modified silsesquioxane and triethylenetetramine is 1:0.5-1, and the weight ratio of modified copolyester and modified filler is 90-100:10-15.

6. The method for preparing PETG co-extruded composite sheet according to claim 3, characterized in that: The modified additive is prepared by the following steps: Step B1: Mix octamethylcyclotetrasiloxane, tetramethyldisiloxane, tetramethylammonium hydroxide and dimethyl sulfoxide, and react under nitrogen protection to obtain dihydropolysiloxane. Mix dihydropolysiloxane, diethylenedichlorosilane, caster catalyst and xylene, and react under nitrogen protection to obtain pretreated polysiloxane. Step B2: Lithium dimethylhydrosilyl alcohol and tetrahydrofuran are mixed, nitrogen gas is introduced for protection, hexamethylcyclotrisiloxane is added under stirring, and the reaction is carried out. Pretreated polysiloxane is added and the reaction is continued to obtain modified polysiloxane. Modified polysiloxane, mercaptoethanol, benzophenone and xylene are mixed, nitrogen gas is introduced for protection, and ultraviolet light is used for reaction to obtain hydroxyl polysiloxane. Step B3: Mix hydroxyl polysiloxane, glycidyl methacrylate, caster catalyst and xylene, purge with nitrogen gas, and react to obtain the modified additive.

7. The method for preparing PETG co-extruded composite sheet according to claim 6, characterized in that: The molar ratio of octamethylcyclotetrasiloxane, tetramethyldisiloxane and tetramethylammonium hydroxide in step B1 is 1.2:1:1.5, and the molar ratio of dihydropolysiloxane and diethylenedichlorosilane is n:n+1, where n is a natural number greater than 0.

8. The method for preparing PETG co-extruded composite sheet according to claim 6, characterized in that: In step B2, the molar ratio of the Si-Cl bonds on the dimethylhydrosilyl alcohol lithium, hexamethylcyclotrisiloxane, and pretreated polysiloxane is 1:5:1, and the molar ratio of the modified polysiloxane and mercaptoethanol is 1:

2.

9. The method for preparing PETG co-extruded composite sheet according to claim 6, characterized in that: The molar ratio of the Si-H bond on the hydroxyl polysiloxane and the glycidyl methacrylate in step B3 is 1:

1.

10. A PETG co-extruded composite sheet, characterized in that: Prepared according to any one of the preparation methods described in claims 1-9.

Images