A polyester white film for imitating paper labels and its preparation method

Abstract

The present invention discloses a polyester white film for imitating paper labels and a preparation method thereof. Light raw materials are prepared by a blending method, and the density of the polyester white film for imitating paper labels is controlled within 1.0 g / m by adding the light raw materials. 3 ‑1.2g / m 3 The core layer incorporates lightweight raw materials and white masterbatch to achieve high opacity, while the print layer utilizes a high-content silicon-containing masterbatch to achieve a low gloss that mimics paper labels. High ink adhesion is achieved through an online coating process using a water-based versatate epoxy acrylic resin. This invention eliminates the need for subsequent offline coating, saving production costs and preventing issues like printing breakpoints and de-inking. The polyester white film for paper-like labels offers high strength, low density, and the texture, density, gloss, and color of paper labels. It is also resistant to high-temperature processing and exhibits high ink adhesion.

Description

Technical Field

[0001] The invention relates to a polyester film, in particular to a polyester white film for imitating paper labels and a preparation method thereof. Background Art

[0002] With the development of my country's polyester film industry, polyester materials are widely used in various fields such as home appliances, electronics, and automobiles. In the label industry, labels made of polyester film materials have advantages over paper labels in terms of good heat resistance, high dimensional stability, waterproofness, corrosion resistance, aging resistance, and tear resistance. However, due to the gap between polyester labels and paper labels in appearance and texture, it is not conducive to the widespread replacement of paper labels. The density of polyester white film itself reaches 1.4g / m 3 Above, greater than 1.2g / m 3 The surface gloss and color of paper labels below this density differ significantly from those of paper labels. Furthermore, the high density and high unit cost of the film hinder the widespread adoption of white polyester film for labeling. As a polyester film for labeling, paper-like label film must maintain the texture and gloss of paper labels while ensuring ink adhesion during printing. To achieve high ink adhesion and prevent breakage and missed prints on the rough surface during barcode printing and other printing processes, an acrylic resin coating is applied online to the surface of the paper-like label film. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a polyester white film for imitating paper labels, which has low density, high strength, low surface gloss, a texture close to label paper, good surface ink adhesion, and is conducive to ink printing and label printing, and a preparation method thereof.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing a polyester white film for imitation paper labels, comprising the following steps:

[0005] 1) Preparation of lightweight raw material: Poly (4-methylpentene-1), PET chips, and toughening agent ethylene terpolymer are mixed in a mass ratio of poly (4-methylpentene-1): PET: toughening agent ethylene terpolymer = 40%-45%: 50%-56%: 4%-5%; mixed uniformly by a feeding screw, extruded by a twin-screw extruder at a temperature of 250° C.-265° C. and a water tank temperature of 30° C.-35° C., and pelletized to produce the lightweight raw material;

[0006] 2) Preparation of water-based coating liquid:

[0007] The coating solution includes the following components by mass percentage:

[0008] Sulfosuccinate 0.8% -1%

[0009] Water-based versatile epoxy acrylic resin 30%-32%

[0010] Crosslinking agent isocyanate 0.2%-0.3%

[0011] The balance is deionized water;

[0012] 3) Raw Material Formulation: The polyester white film for paper-like labels is co-extruded in three layers, comprising a core layer and two surface layers, the top layer being a printing layer and the bottom layer being an anti-blocking layer. The middle layer is a core layer, which is a mixture of 70%-75% lightweight raw materials and 25%-30% titanium dioxide masterbatch. The printing layer is a mixture of 40%-50% of a 30,000 ppm silicon-containing masterbatch and 50%-60% PET chips. The anti-blocking layer is a mixture of 70%-80% of a 30,000 ppm silicon-containing polyester masterbatch and 20%-30% PET chips. All percentages are by mass.

[0013] 4) Extrusion Process: The core layer raw material is pre-crystallized at 155°C-160°C for 25-30 minutes, dried at 145°C-150°C for 5-6 hours, and extruded through a single-screw main extruder at an extrusion temperature of 260°C-265°C. The two surface layer raw materials are extruded through a twin-screw auxiliary extruder at an extrusion temperature of 270°C-275°C. The extrusion amount of the three layers of raw materials is (by weight percentage): printing layer: core layer: anti-blocking layer = 8%-10%, 78%-80%, and 10%-12%. After melt extrusion, it is cooled on a chilled roller at 30°C-33°C and longitudinally stretched by 2.9-3.0 times before online coating.

[0014] 5) Gravure roller coating: The coating liquid prepared in step 2) is pumped into an intermediate material tank via a liquid supply pump. The intermediate pump pumps the coating liquid in the intermediate material tank into a sealed doctor blade cavity. The gravure roller transfers the coating liquid in the cavity to the film printing layer through the contact angle with the film, forming a coating layer on the surface of the film printing layer; the coating liquid temperature is 18°C-20°C, the wet coating thickness during the coating process is controlled at 4.5-5.0 μm, and the coating speed is 75-110 m / min;

[0015] 6) Horizontal stretching film formation: The film cast sheet covered with the coating liquid enters the transverse stretching equipment, the transverse stretching ratio is 3.6-3.8 times, the transverse stretching preheating section temperature is 102-104 ° C, the coating liquid evaporates water, and forms a uniform water-based versatile epoxy acrylic acid chemical treatment layer on the surface of the film. The heat setting temperature is 232 ° C -235 ° C, and the film forms a stable thermal shrinkage rate and mechanical strength. After horizontal stretching, it is pulled and rolled into a polyester white film for imitation paper labels.

[0016] Preferably, in step 1), poly-4-methylpentene-1 is dried at 100° C. for 5 hours and PET chips are crystallized and dried at 160° C. for 5 hours, mixed uniformly by a feeding screw according to mass percentage, and extruded through a twin-screw extruder. The extruder temperature is set to 250° C.-265° C., the extruder speed is set to 235 r / min for melt extrusion, the extruder load is controlled between 95A-102A, the water tank temperature is controlled to 30-35° C., the pelletizer speed is controlled to 800-850 rpm, and the lightweight raw material is prepared after pelletizing.

[0017] The polyester white film for imitating paper labels is prepared by the above preparation method.

[0018] The beneficial effects of the present invention are: preparing light raw materials by a blending method, and controlling the density of the polyester white film for imitation paper labels to be 1.0 g / m 3 -1.2g / m 3 Through a layered design, the core layer incorporates lightweight raw materials and white masterbatch to achieve high opacity, while the print layer utilizes a high-content silicone masterbatch to achieve a low gloss that mimics paper labels. High ink adhesion is achieved through an in-line coating process using a water-based versatate epoxy acrylic resin formula. This product eliminates the need for subsequent offline coating, saving production costs and preventing issues such as printing breakpoints and de-inking. The polyester white film for paper-like labels offers high strength and low density, while retaining the texture, density, gloss, and color of paper labels. It is also resistant to high-temperature processing and exhibits excellent ink adhesion. DETAILED DESCRIPTION

[0019] The method for preparing the polyester white film for imitating paper labels of the present invention comprises the following steps:

[0020] 1) Preparation of lightweight raw material: Poly (4-methylpentene-1), PET chips, and toughening agent ethylene terpolymer are mixed in a mass ratio of poly (4-methylpentene-1): PET: toughening agent ethylene terpolymer = 40%-45%: 50%-56%: 4%-5%; mixed uniformly by a feeding screw, extruded by a twin-screw extruder at a temperature of 250° C.-265° C. and a water tank temperature of 30° C.-35° C., and pelletized to produce the lightweight raw material;

[0021] 2) Preparation of water-based coating liquid:

[0022] The coating solution includes the following components by mass percentage:

[0023] Sulfosuccinate 0.8% -1%

[0024] Water-based versatile epoxy acrylic resin 30%-32%

[0025] Crosslinking agent isocyanate 0.2%-0.3%

[0026] The balance is deionized water;

[0027] 3) Raw Material Formulation: The polyester white film for paper-like labels is co-extruded in three layers, comprising a core layer and two surface layers, the top layer being a printing layer and the bottom layer being an anti-blocking layer. The middle layer is a core layer, which is a mixture of 70%-75% lightweight raw materials and 25%-30% titanium dioxide masterbatch. The printing layer is a mixture of 40%-50% of a 30,000 ppm silicon-containing masterbatch and 50%-60% PET chips. The anti-blocking layer is a mixture of 70%-80% of a 30,000 ppm silicon-containing polyester masterbatch and 20%-30% PET chips. All percentages are by mass.

[0028] 4) Extrusion Process: The core layer raw material is pre-crystallized at 155°C-160°C for 25-30 minutes, dried at 145°C-150°C for 5-6 hours, and extruded through a single-screw main extruder at an extrusion temperature of 260°C-265°C. The two surface layer raw materials are extruded through a twin-screw auxiliary extruder at an extrusion temperature of 270°C-275°C. The extrusion amount of the three layers of raw materials is (by weight percentage): printing layer: core layer: anti-blocking layer = 8%-10%, 78%-80%, and 10%-12%. After melt extrusion, it is cooled on a chilled roller at 30°C-33°C and longitudinally stretched by 2.9-3.0 times before online coating.

[0029] 5) Gravure roller coating: The coating liquid prepared in step 2) is pumped into an intermediate material tank via a liquid supply pump. The intermediate pump pumps the coating liquid in the intermediate material tank into a sealed doctor blade cavity. The gravure roller transfers the coating liquid in the cavity to the film printing layer through the contact angle with the film, forming a coating layer on the surface of the film printing layer; the coating liquid temperature is 18°C-20°C, the wet coating thickness during the coating process is controlled at 4.5-5.0 μm, and the coating speed is 75-110 m / min;

[0030] 6) Horizontal stretching film formation: The film cast sheet covered with the coating liquid enters the transverse stretching equipment, the transverse stretching ratio is 3.6-3.8 times, the transverse stretching preheating section temperature is 102-104 ° C, the coating liquid evaporates water, and forms a uniform water-based versatile epoxy acrylic acid chemical treatment layer on the surface of the film. The heat setting temperature is 232 ° C -235 ° C, and the film forms a stable thermal shrinkage rate and mechanical strength. After horizontal stretching, it is pulled and rolled into a polyester white film for imitation paper labels.

[0031] Preferably, in step 1), poly-4-methylpentene-1 is dried at 100° C. for 5 hours and PET chips are crystallized and dried at 160° C. for 5 hours, mixed uniformly by a feeding screw according to mass percentage, and extruded through a twin-screw extruder. The extruder temperature is set to 250° C.-265° C., the extruder speed is set to 235 r / min for melt extrusion, the extruder load is controlled between 95A-102A, the water tank temperature is controlled to 30-35° C., the pelletizer speed is controlled to 800-850 rpm, and the lightweight raw material is prepared after pelletizing.

[0032] The polyester white film for imitating paper labels is prepared by the above preparation method.

[0033] Example 1: Preparation of polyester white film for imitation paper labels (production thickness 75 μm)

[0034] 1) Lightweight Raw Material Preparation: Poly (4-methylpentene-1) (TPX) was dried at 100°C for 5 hours, and PET chips were crystallized and dried at 160°C for 5 hours. The weight percentage of TPX:PET:toughener ethylene terpolymer (DuPont Elvaloy PTW) was 40%:56%:4%. Mixed uniformly by a feeding screw, the mixture was then extruded through a twin-screw extruder at a temperature of 250°C-265°C and a speed of 235 rpm for melt extrusion. The extruder load was controlled between 95A and 102A, the water tank temperature was maintained at 30-35°C, and the pelletizer speed was controlled between 800 and 850 rpm. After pelletizing, the lightweight raw material was obtained.

[0035] 2) Preparation of water-based coating liquid:

[0036] The coating solution includes the following components by mass percentage:

[0037] Sulfosuccinate TRITON GR-5M 1%

[0038] Water-based versatate epoxy acrylic resin Neander T&C GmbH FM135 32%

[0039] Crosslinking agent isocyanate 0.3%

[0040] The balance is deionized water

[0041] 3) Raw material formula: The core layer is a mixture of 70% lightweight raw materials and 30% titanium dioxide masterbatch. The printing layer is a mixture of 50% 30,000 ppm silicon-containing masterbatch and 50% PET chips, and is coated online with a water-soluble versatate epoxy acrylic resin. The anti-blocking layer is a mixture of 80% 30,000 ppm silicon-containing polyester masterbatch and 20% PET chips. All percentages are by mass.

[0042] 4) Extrusion process: The core layer raw material is pre-crystallized at 160°C for 30 minutes, dried at 150°C for 6 hours, and extruded through a single-screw main extruder at an extrusion temperature of 265°C. The two surface layer raw materials are extruded through a twin-screw auxiliary extruder at an extrusion temperature of 275°C. The extrusion amount of the three layers of raw materials is (by weight percentage) printing layer: core layer: anti-blocking layer = 8%: 80%: 12%. After melt extrusion, it is cooled at 30°C via a chilled roller and longitudinally stretched 3.0 times before in-line coating.

[0043] 5) Gravure roller coating: The coating liquid prepared in step 2) is pumped into an intermediate material tank via a liquid supply pump. The intermediate pump pumps the coating liquid in the intermediate material tank into a sealed scraper cavity. The gravure roller transfers the coating liquid in the cavity to the film surface through the contact angle with the film, forming a coating layer on the film surface; the coating liquid temperature is 18°C ​​to 20°C, the wet coating thickness during the coating process is controlled at 4.5-5.0 μm, and the coating speed is 75 m / min;

[0044] 6) Transverse stretching: The film sheet covered with the coating liquid enters the transverse stretching equipment. The temperature of the transverse stretching preheating section is 104°C. The coating liquid evaporates the water and forms a uniform water-based versatate epoxy acrylic acid chemical treatment layer on the surface of the film. The heat setting temperature is 232°C. The film forms a stable thermal shrinkage rate and mechanical strength. After transverse stretching, it is traction and reeled to produce a polyester white film for imitation paper labels.

[0045] 7) Thermal stability control: The longitudinal thermal shrinkage rate is 1.1%-1.2% in hot air at 150℃ for 30 minutes, and the transverse thermal shrinkage rate is -0.2%-0.0%

[0046] 8) Density control: density 1.0g / m 3 -1.2g / m 3

[0047] 9) Light transmittance control: Light transmittance is between 8% and 11%

[0048] Example 2: Preparation of polyester white film for imitation paper labels (production thickness 50 μm)

[0049] 1) Lightweight Raw Material Preparation: Poly (4-methylpentene-1) (TPX) was dried at 100°C for 5 hours, and PET chips were crystallized and dried at 160°C for 5 hours. The weight ratio of TPX:PET:toughener ethylene terpolymer (DuPont Elvaloy PTW) was 45%:50%:5%. The mixture was uniformly mixed using a feed screw and then extruded through a twin-screw extruder at a temperature of 250°C-265°C and a speed of 235 rpm for melt extrusion. The extruder load was controlled between 95A and 102A, the water tank temperature was maintained at 30-35°C, and the pelletizer speed was controlled between 800 and 850 rpm. After pelletizing, the lightweight raw material was obtained.

[0050] 2) Preparation of water-based coating liquid:

[0051] The coating solution includes the following components by mass percentage:

[0052] Sulfosuccinate TRITON GR-5M 1%

[0053] Water-based versatate epoxy acrylic resin Neander T&C GmbH FM135 32%

[0054] Crosslinking agent isocyanate 0.3%

[0055] The balance is deionized water

[0056] 3) Raw material formula: The core layer is a mixture of 70% lightweight raw materials and 30% titanium dioxide masterbatch. The printing layer is a mixture of 50% 30,000 ppm silicon-containing masterbatch and 50% PET chips, and is coated online with a water-soluble versatate epoxy acrylic resin. The anti-blocking layer is a mixture of 80% 30,000 ppm silicon-containing polyester masterbatch and 20% PET chips. All percentages are by mass.

[0057] 4) Extrusion process: The core layer raw material is pre-crystallized at 160°C for 30 minutes, dried at 150°C for 6 hours, and extruded through a single-screw main extruder at an extrusion temperature of 265°C. The two surface layer raw materials are extruded through a twin-screw auxiliary extruder at an extrusion temperature of 275°C. The extrusion amount of the three layers of raw materials is based on the mass percentage of printing layer: core layer: anti-blocking layer = 10%: 80%: 10%. After melt extrusion, it is cooled at 30°C by chilled rollers and longitudinally stretched 2.9 times before online coating.

[0058] 5) Gravure roller coating: The coating liquid prepared in step 2) is pumped into an intermediate material tank via a liquid supply pump. The intermediate pump pumps the coating liquid in the intermediate material tank into a sealed scraper cavity. The gravure roller transfers the coating liquid in the cavity to the film surface through the contact angle with the film, forming a coating layer on the film surface; the coating liquid temperature is 18°C ​​to 20°C, the wet coating thickness during the coating process is controlled at 4.5-5.0 μm, and the coating speed is 110 m / min;

[0059] 6) Transverse stretching: The film sheet covered with the coating liquid enters the transverse stretching equipment. The temperature of the transverse stretching preheating section is 104°C. The coating liquid evaporates the water and forms a uniform water-based versatate epoxy acrylic acid chemical treatment layer on the surface of the film. The heat setting temperature is 235°C. The film forms a stable thermal shrinkage rate and mechanical strength. After transverse stretching, it is traction and reeled to produce a polyester white film for imitation paper labels;

[0060] 7) Thermal stability control: The longitudinal thermal shrinkage rate is 1.1%-1.2% in hot air at 150℃ for 30 minutes, and the transverse thermal shrinkage rate is -0.2%-0.0%

[0061] 8) Density control: density 1.0g / m 3 -1.2g / m 3

[0062] 9) Transmittance control: Transmittance is between 12% and 14%

[0063] The polyester white film for imitating paper labels prepared by the method of the present invention has the following performance indicators (with a 75 μm thick film as a reference):

[0064]

[0065] The embodiments described above are only used to illustrate the technical ideas and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. The scope of the patent of the present invention cannot be limited by these embodiments alone. That is, any equivalent changes or modifications made to the spirit disclosed by the present invention still fall within the scope of the patent of the present invention.

Claims

1. A method for preparing a polyester white film for imitation paper labels, characterized in that: The following steps are involved: (1) Preparation of lightweight raw materials: Poly (4-methylpentene-1), PET chips, and toughening agent ethylene terpolymer are mixed in a mass ratio of poly (4-methylpentene-1): PET chips: toughening agent ethylene terpolymer = 40%-45%: 50%-56%: 4%-5%; mixed evenly by a feeding screw, extruded by a twin-screw extruder at a temperature of 250°C-265°C and a water tank temperature of 30-35°C, and pelletized to produce a lightweight raw material; (2) Preparation of water-based coating liquid: The coating solution includes the following components by mass percentage: Sulfosuccinate 0.8%-1% Water-based versatile epoxy acrylic resin 30%-32% Crosslinking agent isocyanate 0.2%-0.3% The balance is deionized water; (3) Raw material formula: The polyester white film for imitation paper labels is co-extruded in three layers, including a core layer and two surface layers, wherein the uppermost layer is a printing layer and the lowermost layer is an anti-blocking layer; the middle layer is a core layer, which is a mixture of 70%-75% lightweight raw materials and 25%-30% titanium dioxide masterbatch; the printing layer is a mixture of 40%-50% of a silicon-containing polyester masterbatch with a content of 30,000 ppm and 50%-60% of PET chips; the anti-blocking layer is a mixture of 70%-80% of a silicon-containing polyester masterbatch with a content of 30,000 ppm and 20%-30% of PET chips. All percentages are by mass. (4) Extrusion process: the core layer raw material is pre-crystallized at 155℃-160℃ for 25-30 minutes, dried at 145℃-150℃ for 5-6 hours, and extruded by a single-screw main extruder at an extrusion temperature of 260℃-265℃; the two surface layer raw materials are extruded by a twin-screw auxiliary extruder at an extrusion temperature of 270℃-275℃; the extrusion amount of the three layers of raw materials is based on the mass percentage of the printing layer: core layer: anti-blocking layer = 8%-10%: 78%-80%: 10%-12%. After the melt is extruded, it is cooled by a chilled roller at 30℃-33℃ and longitudinally stretched by 2.9-3.0 times to obtain a film for online coating; (5) Gravure roller coating: The coating liquid prepared in step (2) is pumped into the intermediate material tank through the liquid supply pump. The intermediate pump pumps the coating liquid in the intermediate material tank into the closed scraper cavity. The gravure roller transfers the coating liquid in the cavity to the film printing layer through the contact angle with the film, forming a coating layer on the surface of the film printing layer; the coating liquid temperature is 18°C-20°C, the wet coating thickness during the coating process is controlled at 4.5-5.0 μm, and the coating speed is 75-110 m / min; (6) Horizontal stretching: The film cast coated with the coating liquid enters the transverse stretching equipment, and the transverse stretching ratio is 3.6-3.8 times. The temperature of the transverse stretching preheating section is 102-104℃. The coating liquid evaporates the water and forms a uniform water-based versatile epoxy acrylic acid chemical treatment layer on the surface of the film. The heat setting temperature is 232℃-235℃. The film forms a stable thermal shrinkage rate and mechanical strength. After horizontal stretching, it is pulled and rolled to form a polyester white film for imitation paper labels.

2. The method for preparing the polyester white film for imitating paper labels according to claim 1, characterized in that: In step (1), poly-4-methylpentene-1 is dried at 100° C. for 5 hours and PET chips are crystallized and dried at 160° C. for 5 hours, mixed uniformly by a feeding screw according to mass percentage, and extruded through a twin-screw extruder. The extruder temperature is set to 250° C.-265° C., the extruder speed is set to 235 r / min for melt extrusion, the extruder load is controlled to be between 95A and 102A, the water tank temperature is controlled to be 30-35° C., the pelletizer speed is controlled to be 800-850 r / min, and the lightweight raw material is prepared after pelletizing.

3. The polyester white film for imitating paper labels prepared by the preparation method according to claim 1.

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