Online coating liquid for ultralow-gloss matte film, ultralow-gloss matte film and preparation method of ultralow-gloss matte film

Abstract

The invention discloses online coating liquid for an ultralow-gloss matte film, the ultralow-gloss matte film and a preparation method of the ultralow-gloss matte film. High-content large-particle-size silicon dioxide is uniformly added to the surface layer of a polyester film in a melt blending and three-layer co-extrusion mode; then coating a layer of mixed resin solution after the polyester film is longitudinally stretched in an on-line coating manner, then entering a transverse stretching section, and curing the mixed resin solution in the section, so as to prevent large-particle-size silicon dioxide on the surface layer of the polyester film from being separated out and further reduce the surface glossiness of the polyester film. The prepared ultralow-gloss matte film has ultralow glossiness, the glossiness of the ultralow-gloss matte film is lower than that of a full-matte film, the ultralow-gloss matte film has good ink printing and transferring capacity, no silicon dioxide is separated out in the using process, and the ultralow-gloss matte film is a single-face matte film used for ink printing and transferring of low-gloss materials such as leather and the like and has the advantages of being low in cost and easy to popularize. The excellent potential of replacing a full-matte film is realized.

Description

Technical Field

[0001] The invention relates to a biaxially stretched polyester film, in particular to an online coating liquid for an ultra-low gloss matte film, an ultra-low gloss matte film and a preparation method thereof. Background Art

[0002] Ink printing transfer of low gloss materials such as leather is usually achieved by thermal transfer using a film as a transfer carrier, but the glossiness of the ink printing transfer film suitable for low gloss materials must be less than 20%, which is called full matte film. The production cost of full matte film is high, and the production process of ink printing transfer film made by attaching a low gloss resin composite material on the surface of ordinary matte film as a carrier is complicated and the cost is high. Therefore, it is very necessary to develop an ultra-low gloss matte film for the processing of low gloss soft materials such as leather while maintaining low cost.

[0003] PET polyester film has excellent tensile strength and impact strength, good stiffness, good dimensional stability, excellent heat and cold resistance, and is an ideal material for ink printing transfer. Therefore, it is feasible to develop a matte film with ultra-low gloss by using PET polyester film as the matrix and adding low-cost materials that reduce gloss. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide an online coating liquid for ultra-low gloss matte film, an ultra-low gloss matte film and a preparation method, which are low-cost and easy to process, greatly reduce the gloss of the PET film, and the film has excellent mechanical properties and no precipitation during use, and can be perfectly used in the ink printing transfer process of low-gloss materials such as leather.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is an online coating liquid for ultra-low gloss matte film, which comprises the following components in terms of mass percentage:

[0006] Isopropyl alcohol 30%-60%

[0007] Polyester emulsion 20%-40%

[0008] Epoxy resin 5%-10%

[0009] Amine curing agent 3%-5%

[0010] Water-based wax additive 3%-5%

[0011] Matting powder 2%-4%

[0012] Dispersant 0.1%-1%

[0013] The rest of pure water

[0014] Wherein, the polyester emulsion solid content is 25%-30%, and the epoxy resin solid content is 30%-35%, and the percentages are by mass;

[0015] Preparation method: First, add pure water into the coating preparation tank. After cooling to room temperature, add isopropyl alcohol, dispersant, matting powder and water-based wax additive successively and stir evenly. Then, add polyester emulsion and epoxy resin successively and stir evenly. Finally, add amine curing agent, stir evenly and let stand to degas to complete the preparation of coating liquid.

[0016] The amine curing agent is one or two of melamine, triethyltetramine and diethyltriamine.

[0017] A method for preparing an ultra-low gloss matte film, the ultra-low gloss matte film comprises a thin film interlayer structure consisting of two upper and lower functional surface layers and a core layer, the upper and lower functional surface layers and the middle core layer are compounded together by a three-layer co-extrusion method, the upper functional surface layer uses a matte material with a large-particle size silicon dioxide content of 88%-100% by mass and a content of 30000ppm, and a PET polyester slice with a mass fraction of 0-12%; the lower functional surface layer uses a PET polyester slice with a mass fraction of 93%-100% and a silicon dioxide matte masterbatch with a mass fraction of 0-7% and a content of 3000ppm; the core layer component uses a silicon-containing masterbatch with a mass fraction of 2%-3% and a silicon dioxide content of 30000ppm and a polyester slice with a mass fraction of 87%-98%; the preparation method comprises:

[0018] (1) Extrusion process: The components of the middle core layer are put into a mixer according to the required mass fraction, mixed evenly by an anchor-type scraping stirrer, and then pre-crystallized for 20-60 minutes at 140°C-155°C; put into a horizontal dryer at 155°C-170°C for 4-5 hours, and then transported to the main extruder for extrusion at an extrusion temperature of 200°C-300°C; the components of the upper and lower functional surface layer raw materials are put into a mixer according to the required mass fraction, mixed evenly by an anchor-type scraping stirrer, and then directly transported to the auxiliary The two twin-screw extruders of the auxiliary extruder perform extrusion work at an extrusion temperature of 200°C-300°C; the polyester melt extrusion amount of the upper functional layer, the middle core layer and the lower functional layer is as follows by weight: upper functional layer: middle core layer: lower functional layer = 9%-15%: 76%-82%: 9%-15%. After the three layers of polyester melt are extruded from the respective extruders, they are compounded through a die head adapter into a composite melt with three layers of melt stacked together and flow out of the die. After being cooled by a cooling roller at 25°C-32°C at the die outlet, a casting sheet is formed and enters the longitudinal drawing molding stage;

[0019] (2) Longitudinal stretching: The composite polyester melt is cooled by a cooling roller into a polyester casting sheet and then enters the longitudinal stretching equipment. The temperature of the longitudinal stretching preheating section is 60°C-80°C, the temperature of the stretching section is 70°C-90°C, and the temperature of the cooling section is 20°C-40°C. After the film is longitudinally stretched at a stretching multiple of 2-3.5 times, it enters the online coating section;

[0020] (3) Online coating: The prepared coating liquid is filtered into the coating machine system and evenly coated on the casting sheet by a scraper. The coating layer thickness is controlled between 2-5 μm, and the coating speed is consistent with the speed of the stretching section.

[0021] (4) Horizontal stretching film formation: The thin cast sheet after online coating enters the transverse stretching equipment. The temperature of the transverse stretching preheating section is 80-100℃, the temperature of the stretching section is 100℃-130℃, and the temperature of the relaxation and shaping section is 150-250℃. The film after relaxation and shaping has stable thermal shrinkage and mechanical strength. After horizontal stretching, it is pulled and rolled into an ultra-low gloss matte film.

[0022] The ultra-low gloss matte film prepared by the above preparation method.

[0023] The beneficial effects of the present invention are: a coating layer with good transferability and good adhesion to the polyester film is attached to the functional surface layer of the film by online coating, and the precipitation of the raw materials of the upper functional surface layer is avoided; a large proportion of expensive matte material is added to the upper functional layer, and a large amount of gloss material and a small amount of matte material are added to the middle core layer and the lower functional layer to reduce the cost. The film produced by this method has a glossiness far lower than that of ordinary matte film, and even its glossiness is lower than that of all matte film. There is no separation between the film layers during use, and the raw materials in the layers are evenly mixed, and there is no precipitation of raw materials. The mechanical properties of the film meet the ink printing transfer conditions and the size is stable. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments, and all other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making creative work are within the scope of protection of the present invention.

[0025] The online coating liquid for ultra-low gloss matte film of the present invention comprises the following components in terms of mass percentage:

[0026] Isopropyl alcohol 30%-60%

[0027] Polyester emulsion 20%-40%

[0028] Epoxy resin 5%-10%

[0029] Curing agent amine compound 3%-5%

[0030] Water-based wax additive 3%-5%

[0031] Matting powder 2%-4%

[0032] Dispersant 0.1%-1%

[0033] The rest of pure water

[0034] The solid content of polyester emulsion is 25%-30%, and the solid content of epoxy resin is 30%-35%;

[0035] Preparation method: First, add pure water into the coating preparation tank. After cooling to room temperature, add isopropyl alcohol, dispersant, matting powder and water-based wax additive successively and stir evenly. Then, add polyester emulsion and epoxy resin successively and stir evenly. Finally, add curing agent, stir evenly and let stand to degas to complete the preparation of coating liquid.

[0036] The method for preparing the ultra-low gloss matte film of the present invention comprises the following steps:

[0037] 1) Film interlayer structure: A three-layer structure obtained by three-layer co-extrusion, including a core layer and two upper and lower surface layers. The upper functional surface layer uses a matte material with a large particle size silica content of 88%-100% and a content of 30,000 ppm, and a mass fraction of 0-12% PET polyester chips; the lower functional surface layer uses a mass fraction of 93%-100% PET polyester chips, and a mass fraction of 0-7% of a matte silica masterbatch with a content of 3,000 ppm; the core layer components include a silicon-containing masterbatch with a mass fraction of 2%-13% and a silica content of 30,000 ppm and a mass fraction of 87%-98% polyester chips.

[0038] 2) Extrusion process: The components of the middle core layer are put into the mixer according to the required mass fraction, mixed evenly by the anchor-type scraping stirrer, and then pre-crystallized for 20-60 minutes at 140℃-155℃; then put into the horizontal dryer at 155℃-170℃ for 4-5 hours, and then transported to the main extruder for extrusion at an extrusion temperature of 200℃-300℃; the components of the upper and lower functional surface layer raw materials are put into the mixer according to the required mass fraction, mixed evenly by the anchor-type scraping stirrer, and then directly transported separately The extrusion work is carried out by two twin-screw extruders serving as auxiliary extruders, and the extrusion temperature is 200℃-300℃; the polyester melt extrusion amount of the upper functional layer, the middle core layer and the lower functional layer is as follows in terms of mass proportion: upper functional layer: middle core layer: lower functional layer = 9%-15%: 76%-82%: 9%-15%. After the three layers of polyester melt are extruded from their respective extruders, they are compounded through a die head adapter into a composite melt with three layers of melt stacked together, and then flow out of the die. After being cooled by a cooling roller at 25℃-32℃ at the die outlet, they enter the longitudinal drawing molding stage.

[0039] 3) Longitudinal drawing: The composite polyester melt is cooled by a cooling roller into a polyester casting sheet and then enters the longitudinal stretching equipment. The temperature of the longitudinal stretching preheating section is 60℃-80℃, the temperature of the stretching section is 70℃-90℃, and the temperature of the cooling section is 20℃-40℃. After the film is longitudinally stretched at a stretching multiple of 2-3.5 times, it enters the online coating section.

[0040] 4) Online coating: the prepared coating liquid prepared in claim 1 is sent to the coating machine system through a filter screen and evenly coated on the casting sheet by a scraper. The coating layer thickness is controlled between 2-5 μm, and the coating speed is consistent with the speed of the stretching section;

[0041] 5) Horizontal stretching film formation: The thin cast sheet that has been coated online enters the transverse stretching equipment. The temperature of the transverse stretching preheating section is 80-100℃, the temperature of the stretching section is 100℃-130℃, and the temperature of the relaxation and shaping section is 150-250℃. The film after relaxation and shaping has stable thermal shrinkage and mechanical strength. After horizontal stretching, it is pulled and rolled into an ultra-low gloss matte film.

[0042] The ultra-low gloss matte film is prepared by the above-mentioned preparation method.

[0043] Specifically, the method for preparing the ultra-low gloss matte film of the present invention comprises the following steps:

[0044] 1) Preparation of epoxy resin-polyester coating liquid: In order to prevent the upper functional layer raw material from precipitating and ensure that there is no separation between the film and the coating layer during use, epoxy resin and polyester emulsion are used, with a polyester emulsion solid content of 25%-30% and an epoxy resin solid content of 30%-35%. In order to ensure that the coating layer has good transfer ability, a water-based wax additive is added. A dispersant is added to ensure that the components of the coating liquid are evenly dispersed. One or two amine compound curing agents are added to fully cure the polyester and epoxy resins and further strengthen the adhesion between the coating layer and the film. The specific preparation method of the coating liquid is as follows: first, pure water is added to the coating liquid preparation tank, and after cooling to room temperature, isopropanol, dispersant, matting powder and water-based wax additive are added successively and stirred for 15 minutes, followed by adding polyester emulsion and epoxy resin successively and stirring for 10 minutes, and finally, a curing agent is added and stirred evenly, and then the coating liquid is prepared by standing and degassing.

[0045] The coating solution mainly includes the following components (all in mass percentage):

[0046] Isopropyl alcohol 30%-60%

[0047] Polyester emulsion 20%-40%

[0048] Epoxy resin 5%-10%

[0049] Curing agent amine compound 3%-5%

[0050] Water-based wax additive 3%-5%

[0051] Matting powder 2%-4%

[0052] Dispersant 0.1%-1%

[0053] The rest of pure water

[0054] 2) Film raw materials: A three-layer structure obtained by a three-layer co-extrusion method, including a core layer and two upper and lower surface layers. The upper functional surface layer uses a matte material with a large particle size silica content of 88%-100% and a content of 30,000 ppm, and a mass fraction of 0-12% PET polyester chips; the lower functional surface layer uses a mass fraction of 93%-100% PET polyester chips, and a mass fraction of 0-7% of a matte silica masterbatch with a content of 3,000 ppm; the core layer components include a silicon-containing masterbatch with a mass fraction of 2%-13% and a silica content of 30,000 ppm and a mass fraction of 87%-98% polyester chips.

[0055] 3) Extrusion process: The components of the middle core layer are put into the mixer according to the required mass fraction, mixed evenly by the anchor-type scraping stirrer, and then pre-crystallized for 20-60 minutes at 140℃-155℃; then put into the horizontal dryer at 155℃-170℃ for 4-5 hours, and then transported to the main extruder for extrusion at an extrusion temperature of 200℃-300℃; the components of the upper and lower functional surface layer raw materials are put into the mixer according to the required mass fraction, mixed evenly by the anchor-type scraping stirrer, and then directly transported separately The extrusion work is carried out by two twin-screw extruders serving as auxiliary extruders, and the extrusion temperature is 200℃-300℃; the polyester melt extrusion amount of the upper functional layer, the middle core layer and the lower functional layer is as follows in terms of mass proportion: upper functional layer: middle core layer: lower functional layer = 9%-15%: 76%-82%: 9%-15%. After the three layers of polyester melt are extruded from their respective extruders, they are compounded through a die head adapter into a composite melt with three layers of melt stacked together, and then flow out of the die. After being cooled by a cooling roller at 25℃-32℃ at the die outlet, they enter the longitudinal drawing molding stage.

[0056] 4) Longitudinal drawing: The composite polyester melt is cooled by a cooling roller into a polyester casting sheet and then enters the longitudinal stretching equipment. The temperature of the longitudinal stretching preheating section is 60℃-80℃, the temperature of the stretching section is 70℃-90℃, and the temperature of the cooling section is 00℃-40℃. After the film is longitudinally stretched at a stretching multiple of 2-3.5 times, it enters the online coating section.

[0057] 5) Online coating: the prepared coating liquid prepared in claim 1 is sent to the coating machine system through a filter screen and evenly coated on the casting sheet by a scraper. The coating layer thickness is controlled between 2-5 μm, and the coating speed is consistent with the speed of the stretching section;

[0058] 6) Horizontal stretching film formation: The thin cast sheet that has been coated online enters the transverse stretching equipment. The temperature of the transverse stretching preheating section is 80-100℃, the temperature of the stretching section is 100℃-130℃, and the temperature of the relaxation and shaping section is 150-250℃. The film after relaxation and shaping has stable thermal shrinkage and mechanical strength. After horizontal stretching, it is pulled and rolled into an ultra-low gloss matte film.

[0059] Example 1: Preparation method of 35μ ultra-low gloss matte film

[0060] 1) Preparation of epoxy resin-polyester coating liquid: In order to prevent the upper functional layer raw material from precipitating and ensure that there is no separation between the film and the coating layer during use, epoxy resin and polyester emulsion are used, with a polyester emulsion solid content of 25% and an epoxy resin solid content of 30%. In order to ensure that the coating layer has good transfer ability, a water-based wax additive is added. A dispersant is added to ensure that the components of the coating liquid are evenly dispersed. One or two amine compound curing agents are added to fully cure the polyester and epoxy resins and further strengthen the adhesion between the coating layer and the film. The specific preparation method of the coating liquid is as follows: first, pure water is added to the coating liquid preparation tank, and after cooling to room temperature, isopropanol, dispersant, matting powder and water-based wax additive are added successively and stirred for 15 minutes, followed by adding polyester emulsion and epoxy resin successively and stirring for 10 minutes, and finally, a curing agent is added and stirred evenly, and then the coating liquid is prepared by standing and degassing.

[0061] Prepare 50kg of coating liquid, mainly including the following ingredients:

[0062] Isopropyl alcohol 15kg

[0063] Polyester emulsion 10kg

[0064] Epoxy resin 2.5kg

[0065] Curing agent amine compound 1.5kg

[0066] Water-based wax additive 1.5kg

[0067] Matting powder 1kg

[0068] Dispersant 0.5kg

[0069] The rest of pure water

[0070] 2) Film raw materials: A three-layer structure obtained by a three-layer co-extrusion method, including a core layer and two upper and lower surface layers. The upper functional surface layer uses a matte material with a large particle size silica content of 90% by mass and a content of 30,000 ppm, and a PET polyester chip with a mass fraction of 10%; the lower functional surface layer uses a PET polyester chip with a mass fraction of 95% and a matte masterbatch of silica with a mass fraction of 5% and a content of 3,000 ppm; the core layer components include a silicon-containing masterbatch with a mass fraction of 7% and a silica content of 30,000 ppm and a polyester chip with a mass fraction of 93%.

[0071] 3) Extrusion process: the components of the middle core layer are put into the mixer according to the required mass fraction, mixed evenly by the anchor-type scraper stirrer, and then pre-crystallized for 20 minutes at 155°C; then put into a horizontal dryer at 140°C for 4 hours of drying, and then transported to the main extruder for extrusion, and the extrusion temperature is 280°C; the components of the upper and lower functional surface layer raw materials are put into the mixer according to the required mass fraction, mixed evenly by the anchor-type scraper stirrer, and then directly transported to the auxiliary extruder for extrusion, and the extrusion temperature is 270°C; the polyester melt extrusion amount of the upper functional layer, the middle core layer and the lower functional layer is as follows by mass ratio: upper functional layer: middle core layer: lower functional layer = 9%: 82%: 9%, and the three layers of polyester melt are extruded from their respective extruders. After being compounded into a composite melt with three layers of melt stacked together through a die head adapter, it flows into the die, and enters the longitudinal drawing molding stage after being cooled by a cooling roller at 25°C at the die outlet.

[0072] 4) Longitudinal stretching: The composite polyester melt is cooled by a cooling roller into a polyester casting sheet and then enters the longitudinal stretching equipment. The temperature of the longitudinal stretching preheating section is 60℃-80℃, the temperature of the stretching section is 70℃-90℃, and the temperature of the cooling section is 20℃-40℃. After the film is longitudinally stretched at a stretching multiple of 3 times, it enters the transverse stretching section.

[0073] 5) Horizontal stretching film: The thin cast sheet that has been longitudinally stretched and formed enters the transverse stretching equipment. The temperature of the transverse stretching preheating section is 80-100℃, the temperature of the stretching section is 100℃-130℃, and the temperature of the relaxation and shaping section is 150-250℃. The film after relaxation and shaping has stable thermal shrinkage and mechanical strength; after transverse stretching, it is pulled and rolled into an ultra-low gloss matte film.

[0074] The ultra-low gloss matte film prepared by the method of the present invention has the following performance indicators:

[0075]

[0076]

[0077] Example 2: Preparation method of 50μ ultra-low gloss matte film

[0078] 1) Preparation of epoxy resin-polyester coating liquid: In order to prevent the upper functional layer raw material from precipitating and ensure that there is no separation between the film and the coating layer during use, epoxy resin and polyester emulsion are used, with a polyester emulsion solid content of 27% and an epoxy resin solid content of 33%. In order to ensure that the coating layer has good transfer ability, a water-based wax additive is added. A dispersant is added to ensure that the components of the coating liquid are evenly dispersed. One or two amine compound curing agents are added to fully cure the polyester and epoxy resins and further strengthen the adhesion between the coating layer and the film. The specific preparation method of the coating liquid is as follows: first, pure water is added to the coating liquid preparation tank, and after cooling to room temperature, isopropanol, dispersant, matting powder and water-based wax additive are added successively and stirred for 15 minutes, followed by adding polyester emulsion and epoxy resin and stirring for 10 minutes, and finally, a curing agent is added and stirred evenly, and then the coating liquid is prepared by standing and degassing.

[0079] Prepare 50kg of coating liquid, mainly including the following ingredients:

[0080] Isopropyl alcohol 22.5kg

[0081] Polyester emulsion 15kg

[0082] Epoxy resin 3.5kg

[0083] Curing agent amine compound 2kg

[0084] Water-based wax additive 2kg

[0085] Matting powder 1.5kg

[0086] Dispersant 0.75kg

[0087] The rest of pure water

[0088] 2) Film raw materials: A three-layer structure obtained by a three-layer co-extrusion method, including a core layer and two upper and lower surface layers. The upper functional surface layer uses a matte material with a large particle size silica content of 90% by mass and a content of 30,000 ppm, and a PET polyester chip with a mass fraction of 10%; the lower functional surface layer uses a PET polyester chip with a mass fraction of 95% and a matte masterbatch of silica with a mass fraction of 5% and a content of 3,000 ppm; the core layer components include a silicon-containing masterbatch with a mass fraction of 7% and a silica content of 30,000 ppm and a polyester chip with a mass fraction of 93%.

[0089] 3) Extrusion process: the components of the middle core layer are put into the mixer according to the required mass fraction, mixed evenly by the anchor-type scraper stirrer, and then pre-crystallized for 20 minutes at 155°C; then put into a horizontal dryer at 140°C for 4 hours of drying, and then transported to the main extruder for extrusion, and the extrusion temperature is 280°C; the components of the upper and lower functional surface layer raw materials are put into the mixer according to the required mass fraction, mixed evenly by the anchor-type scraper stirrer, and then directly transported to the auxiliary extruder for extrusion, and the extrusion temperature is 270°C; the polyester melt extrusion amount of the upper functional layer, the middle core layer and the lower functional layer is as follows by mass ratio: upper functional layer: middle core layer: lower functional layer = 9%: 82%: 9%, and the three layers of polyester melt are extruded from their respective extruders. After being compounded into a composite melt with three layers of melt stacked together through a die head adapter, it flows into the die, and enters the longitudinal drawing molding stage after being cooled by a cooling roller at 25°C at the die outlet.

[0090] 4) Longitudinal stretching: The composite polyester melt is cooled by a cooling roller into a polyester casting sheet and then enters the longitudinal stretching equipment. The temperature of the longitudinal stretching preheating section is 60℃-80℃, the temperature of the stretching section is 70℃-90℃, and the temperature of the cooling section is 20℃-40℃. After the film is longitudinally stretched at a stretching multiple of 3 times, it enters the transverse stretching section.

[0091] 5) Horizontal stretching film: The thin cast sheet that has been longitudinally stretched and formed enters the transverse stretching equipment. The temperature of the transverse stretching preheating section is 80-100℃, the temperature of the stretching section is 100℃-130℃, and the temperature of the relaxation and shaping section is 150-250℃. The film after relaxation and shaping has stable thermal shrinkage and mechanical strength; after transverse stretching, it is pulled and rolled into an ultra-low gloss matte film.

[0092] The ultra-low gloss matte film prepared by the method of the present invention has the following performance indicators:

[0093]

[0094]

[0095] Example 3: Preparation method of 75μ ultra-low gloss matte film

[0096] 1) Preparation of epoxy resin-polyester coating liquid: In order to prevent the upper functional layer raw material from precipitating and ensure that there is no separation between the film and the coating layer during use, epoxy resin and polyester emulsion are used, with a polyester emulsion solid content of 30% and an epoxy resin solid content of 35%. In order to ensure that the coating layer has good transfer ability, a water-based wax additive is added. A dispersant is added to ensure that the components of the coating liquid are evenly dispersed. One or two amine compound curing agents are added to fully cure the polyester and epoxy resin and further strengthen the adhesion between the coating layer and the film. The specific preparation method of the coating liquid is as follows: first, pure water is added to the coating liquid preparation tank, and after cooling to room temperature, isopropanol, dispersant, matting powder and water-based wax additive are added successively and stirred for 15 minutes, followed by adding polyester emulsion and epoxy resin successively and stirring for 10 minutes, and finally, a curing agent is added and stirred evenly, and then the coating liquid is prepared by standing and degassing.

[0097] Prepare 50kg of coating liquid, mainly including the following ingredients:

[0098] Isopropyl alcohol 22.5kg

[0099] Polyester emulsion 17.5kg

[0100] Epoxy resin 4kg

[0101] Curing agent amine compound 2.5kg

[0102] Water-based wax additive 2kg

[0103] Matting powder 1.5kg

[0104] Dispersant 0.75kg

[0105] The rest of pure water

[0106] 2) Film raw materials: A three-layer structure obtained by a three-layer co-extrusion method, including a core layer and two upper and lower surface layers. The upper functional surface layer uses a matte material with a large particle size silica content of 90% by mass and a content of 30,000 ppm, and a PET polyester chip with a mass fraction of 10%; the lower functional surface layer uses a PET polyester chip with a mass fraction of 95% and a matte masterbatch of silica with a mass fraction of 5% and a content of 3,000 ppm; the core layer components include a silicon-containing masterbatch with a mass fraction of 7% and a silica content of 30,000 ppm and a polyester chip with a mass fraction of 93%.

[0107] 3) Extrusion process: the components of the middle core layer are put into the mixer according to the required mass fraction, mixed evenly by the anchor-type scraper stirrer, and then pre-crystallized for 20 minutes at 155°C; then put into a horizontal dryer at 140°C for 4 hours of drying, and then transported to the main extruder for extrusion, and the extrusion temperature is 280°C; the components of the upper and lower functional surface layer raw materials are put into the mixer according to the required mass fraction, mixed evenly by the anchor-type scraper stirrer, and then directly transported to the auxiliary extruder for extrusion, and the extrusion temperature is 270°C; the polyester melt extrusion amount of the upper functional layer, the middle core layer and the lower functional layer is as follows by mass ratio: upper functional layer: middle core layer: lower functional layer = 9%: 82%: 9%, and the three layers of polyester melt are extruded from their respective extruders. After being compounded into a composite melt with three layers of melt stacked together through a die head adapter, it flows into the die, and enters the longitudinal drawing molding stage after being cooled by a cooling roller at 25°C at the die outlet.

[0108] 4) Longitudinal stretching: The composite polyester melt is cooled by a cooling roller into a polyester casting sheet and then enters the longitudinal stretching equipment. The temperature of the longitudinal stretching preheating section is 60℃-80℃, the temperature of the stretching section is 70℃-90℃, and the temperature of the cooling section is 20℃-40℃. After the film is longitudinally stretched at a stretching multiple of 3 times, it enters the transverse stretching section.

[0109] 5) Horizontal stretching film: The thin cast sheet that has been longitudinally stretched and formed enters the transverse stretching equipment. The temperature of the transverse stretching preheating section is 80-100℃, the temperature of the stretching section is 100℃-130℃, and the temperature of the relaxation and shaping section is 150-250℃. The film after relaxation and shaping has stable thermal shrinkage and mechanical strength; after transverse stretching, it is pulled and rolled into an ultra-low gloss matte film.

[0110] The ultra-low gloss matte film prepared by the method of the present invention has the following performance indicators:

[0111]

[0112]

[0113] The embodiments described above are only used to illustrate the technical ideas and features of the present invention, and their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. The patent scope of the present invention cannot be limited only by this embodiment, that is, any equivalent changes or modifications made to the spirit disclosed by the present invention still fall within the patent scope of the present invention.

Claims

1. An online coating liquid for ultra-low gloss matte film, characterized in that: According to mass percentage, it includes the following ingredients: Isopropyl alcohol 30%-60% Polyester emulsion 20%-40% Epoxy resin 5%-10% Amine curing agent 3%-5% Water-based wax additive 3%-5% Matting powder 2%-4% Dispersant 0.1%-1% The rest of pure water Wherein, the polyester emulsion solid content is 25%-30%, and the epoxy resin solid content is 30%-35%, and the percentages are by mass; Preparation method: First, add pure water into the coating preparation tank. After cooling to room temperature, add isopropyl alcohol, dispersant, matting powder and water-based wax additive successively and stir evenly. Then, add polyester emulsion and epoxy resin successively and stir evenly. Finally, add amine curing agent, stir evenly and let stand to degas to complete the preparation of coating liquid.

2. The online coating liquid for ultra-low gloss matte film according to claim 1, characterized in that: The amine curing agent is one or two of melamine, triethyltetramine and diethyltriamine.

3. A method for preparing an ultra-low gloss matte film, characterized in that: The ultra-low gloss matte film is composed of a thin film interlayer structure consisting of two upper and lower functional surface layers and a core layer. The upper and lower functional surface layers and the middle core layer are compounded together by a three-layer co-extrusion method. The upper functional surface layer uses a matte material with a large particle size of silicon dioxide with a mass fraction of 88%-100% and a content of 30000ppm, and a PET polyester slice with a mass fraction of 0-12%; the lower functional surface layer uses a PET polyester slice with a mass fraction of 93%-100% and a silicon dioxide matte masterbatch with a mass fraction of 0-7% and a content of 3000ppm; the core layer component uses a silicon-containing masterbatch with a mass fraction of 2%-3% and a silicon dioxide content of 30000ppm and a polyester slice with a mass fraction of 87%-98%. The preparation method includes: (1) Extrusion process: The components of the middle core layer are put into a mixer according to the required mass fraction, mixed evenly by an anchor-type scraping stirrer, and then pre-crystallized for 20-60 minutes at 140°C-155°C; put into a horizontal dryer at 155°C-170°C for 4-5 hours, and then transported to the main extruder for extrusion at an extrusion temperature of 200°C-300°C; the components of the upper and lower functional surface layer raw materials are put into a mixer according to the required mass fraction, mixed evenly by an anchor-type scraping stirrer, and then directly transported to the auxiliary The two twin-screw extruders of the auxiliary extruder perform extrusion work at an extrusion temperature of 200°C-300°C; the polyester melt extrusion amount of the upper functional layer, the middle core layer and the lower functional layer is as follows by weight: upper functional layer: middle core layer: lower functional layer = 9%-15%: 76%-82%: 9%-15%. After the three layers of polyester melt are extruded from the respective extruders, they are compounded through a die head adapter into a composite melt with three layers of melt stacked together and flow out of the die. After being cooled by a cooling roller at 25°C-32°C at the die outlet, a casting sheet is formed and enters the longitudinal drawing molding stage; (2) Longitudinal stretching: The composite polyester melt is cooled by a cooling roller into a polyester casting sheet and then enters the longitudinal stretching equipment. The temperature of the longitudinal stretching preheating section is 60°C-80°C, the temperature of the stretching section is 70°C-90°C, and the temperature of the cooling section is 20°C-40°C. After the film is longitudinally stretched at a stretching multiple of 2-3.5 times, it enters the online coating section; (3) Online coating: The prepared coating liquid prepared in claim 1 is filtered into the coating machine system and evenly coated on the casting sheet by a scraper. The coating layer thickness is controlled between 2-5 μm, and the coating speed is consistent with the speed of the stretching section. (4) Horizontal stretching film formation: The thin cast sheet after online coating enters the transverse stretching equipment. The temperature of the transverse stretching preheating section is 80-100℃, the temperature of the stretching section is 100℃-130℃, and the temperature of the relaxation and shaping section is 150-250℃. The film after relaxation and shaping has stable thermal shrinkage and mechanical strength. After horizontal stretching, it is pulled and rolled into an ultra-low gloss matte film.

4. The ultra-low gloss matte film prepared by the preparation method as claimed in claim 3.

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