A uv printing polyester film for a battery label and a method for manufacturing the same

Abstract

The application discloses a method for printing polyester film for battery label by UV, and belongs to the technical field of polyester film, and the preparation steps are as follows: weighing unmodified PETG / PET raw materials and polyether / polycarbonate ether modified raw materials, feeding the unmodified PETG / PET raw materials into an inner-layer double-screw extruder, feeding the modified raw materials into an outer-layer double-screw extruder, obtaining a polyester cast sheet with a three-layer structure through co-extrusion, controlling the relative thickness of the three-layer structure through a metering pump, preheating the cast sheet, then performing longitudinal or / and transverse stretching, and then performing cooling and shaping, traction and winding to obtain a polyester film product. The polyester film modified by polyether or polycarbonate ether has strong adhesion to ultraviolet light curing ink, and the ink will not be removed during subsequent processing and use. The modified film has improved alkali corrosion resistance. The modified film has increased surface smoothness, significantly reduced friction coefficient, and increased film light transmittance and reduced haze.

Description

Technical Field

[0001] This invention belongs to the field of polyester film technology, specifically relating to a UV-printed polyester film for battery labels and its preparation method. Background Technology

[0002] Currently, when using solvent-free UV-cured inks on conventional PET or PETG films, ink peeling often occurs due to insufficient ink adhesion. The current solution is to coat the PET or PETG film surface with a coating that strongly adheres to the ink, such as polyurethane, acrylate, or styrene copolymer. While this increases ink adhesion, it adds a processing step, affects yield, and is not conducive to cost reduction.

[0003] CN107459636A uses terephthalic acid, ethylene glycol, neopentyl glycol and polytetramethylene ether glycol to copolymerize and prepare a shrink film, but the film preparation process does not use a three-layer co-extrusion method, and does not explain its improvement on the adhesion of UV inks. Summary of the Invention

[0004] In response to the problems raised in the background technology, this invention studies and designs a UV-printed polyester film for battery labels and its preparation method. The purpose is to provide a special polyester film for UV-curable inks with strong adhesion to UV-curable inks, high resistance to alkaline corrosion, increased film transmittance, and reduced haze, as well as its preparation method.

[0005] The technical solution of this invention:

[0006] A UV-printed polyester film for battery labels has the following molecular structure:

[0007]

[0008]

[0009]

[0010] The polyether unit is one or more of polypropylene glycol, polybutylene glycol, and polypentylene glycol units, and the molecular weight of the polyether ranges from 800 to 1800.

[0011] The polycarbonate ether unit is generated by reacting propylene glycol ether, propylene oxide, and carbon dioxide, and the molecular weight of the polycarbonate ether ranges from 600 to 2000.

[0012] The weight ratio of the polyether unit to the PETG unit is 4:96 to 20:80, and the weight ratio of the polyether unit to the PET unit is 4:96 to 20:80.

[0013] The weight ratio of the polycarbonate ether unit to the PETG unit is 2:98 to 10:90, and the weight ratio of the polycarbonate ether unit to the PET unit is 2:98 to 10:90.

[0014] The polyether / polycarbonate ether is added in two ways: First, the polyether or polycarbonate ether is mixed with PETG / PET, and an appropriate amount of transesterification catalyst (zinc acetate / magnesium acetate, etc.) is added. After being extruded by a reactive twin-screw extruder, PETG / PET chips modified with polyether / polycarbonate ether are obtained. Second, the polyether or polycarbonate ether is mixed with terephthalic acid, ethylene glycol, and neopentyl glycol. After being esterified and polycondensed, modified PETG / PET chips are obtained.

[0015] The transesterification catalyst is 50-300 ppm. In addition method two, the molar fraction of terephthalic acid, ethylene glycol, and neopentyl glycol in the mixture is 5%-30%, and the molar ratio of alcohol to acid in terephthalic acid, ethylene glycol, and neopentyl glycol is 1-1.5:1.

[0016] A method for preparing a UV-printed polyester film for battery labels includes the following steps:

[0017] The polyester film is produced using a multi-layer co-extrusion casting process. After weighing unmodified PETG / PET raw materials and polyether / polycarbonate ether modified raw materials, the unmodified PETG / PET raw materials are fed into the inner twin-screw extruder, and the modified raw materials are fed into the outer twin-screw extruder. Through co-extrusion, a three-layer polyester sheet is obtained, and the relative thickness of the three layers is controlled by a metering pump. After preheating, the sheet is stretched longitudinally and / or transversely, cooled, shaped, drawn, and wound to obtain the polyester film product.

[0018] The inner twin-screw extruder temperature is set to 240–260°C, the outer twin-screw extruder temperature is set to 190–235°C, the die temperature is set to 245–255°C, the preheating temperature is set to 60–90°C, the longitudinal stretching temperature is set to 80–105°C, the stretching ratio is set to 3.5–5 times, and the stretching rate is set to 80–120 m / min; the transverse stretching temperature is set to 90–115°C, the stretching ratio is set to 3–5.7 times, and the stretching rate is set to 80–120 m / min.

[0019] The beneficial effects of the present invention are as follows: Compared with the prior art, the present invention has the following advantages: (1) The polyester film modified by polyether or polycarbonate ether has strong adhesion to UV-curable ink and will not experience ink removal during subsequent processing and use; (2) The modified film has improved resistance to alkaline corrosion; (3) The modified film has increased surface smoothness, significantly reduced friction coefficient, increased light transmittance, and reduced haze. Detailed Implementation

[0020] The present invention will be further described below with reference to specific embodiments.

[0021] Example 1

[0022] The polyester film in this embodiment has a three-layer structure consisting of an unmodified PETG inner layer and a modified PETG outer layer. The modified PETG outer layer film is prepared from the following components in parts by weight: 100 parts of modified PETG with a polyether unit ratio of 4%, 5 parts of maleic anhydride-styrene copolymer, 1 part of slip agent, and 0.5 parts of anti-aging agent;

[0023] The inner layer unmodified PETG formulation is: 100 parts of conventional PETG, 1 part of slip agent, and 0.5 parts of anti-aging agent;

[0024] Film-making process: Polyester film is produced using a multi-layer co-extrusion casting process. Unmodified PETG raw material is fed into the inner twin-screw extruder, and modified raw material is fed into the outer twin-screw extruder. Through co-extrusion, a three-layer polyester sheet is obtained. The relative thickness of the three layers is controlled by a metering pump. After preheating, the sheet is stretched longitudinally and / or transversely, cooled, shaped, drawn, and wound to obtain the polyester film product.

[0025] The inner extruder temperature is set to 240–260°C, the outer extruder temperature to 190–235°C, the die temperature to 245–255°C, the preheating temperature to 60–90°C, the longitudinal stretching temperature to 80–105°C, the stretching ratio to 3.5–5 times, and the stretching rate to 80–120 m / min; the transverse stretching temperature to 90–115°C, the stretching ratio to 3–5.7 times, and the stretching rate to 80–120 m / min.

[0026] Example 2

[0027] The polyester film in this embodiment has a three-layer structure consisting of an unmodified PETG inner layer and a modified PETG outer layer.

[0028] The modified PETG outer film is prepared from the following raw materials in parts by weight: 100 parts of modified PETG with a polyether unit ratio of 8%, 5 parts of maleic anhydride-styrene copolymer, 1 part of slip agent, and 0.5 parts of anti-aging agent.

[0029] The raw materials for preparing the unmodified PETG inner layer membrane include the following components in parts by weight: same as in Example 1;

[0030] Film-forming process: Same as in Example 1.

[0031] Example 3

[0032] The polyester film in this embodiment has a three-layer structure consisting of an unmodified PETG inner layer and a modified PETG outer layer. The modified PETG outer layer film is prepared from the following components in parts by weight: 100 parts of modified PETG with a polyether unit ratio of 20%, 5 parts of maleic anhydride-styrene copolymer, 1 part of slip agent, and 0.5 parts of anti-aging agent;

[0033] The raw materials for preparing the unmodified PETG inner layer membrane include the following components in parts by weight: same as in Example 1;

[0034] Film-forming process: Same as in Example 1.

[0035] Example 4

[0036] The polyester film in this embodiment has a three-layer structure consisting of an unmodified PETG inner layer and a modified PETG outer layer. The modified PETG outer layer film is prepared from the following components in parts by weight: 100 parts of modified PETG with a polycarbonate ether unit ratio of 2%, 5 parts of maleic anhydride-styrene copolymer, 1 part of slip agent, and 0.5 parts of anti-aging agent;

[0037] The raw materials for preparing the unmodified PETG inner layer membrane include the following components in parts by weight: same as in Example 1;

[0038] Film-forming process: Same as in Example 1.

[0039] Example 5

[0040] The polyester film in this embodiment has a three-layer structure consisting of an unmodified PETG inner layer and a modified PETG outer layer.

[0041] The modified PETG outer film is prepared from the following raw materials in parts by weight: 100 parts of modified PETG with a polycarbonate ether unit ratio of 6%, 5 parts of maleic anhydride-styrene copolymer, 1 part of slip agent, and 0.5 parts of anti-aging agent.

[0042] The raw materials for preparing the unmodified PETG inner layer film include the following components in parts by weight: 100 parts of conventional PETG, 1 part of slip agent, and 0.5 parts of anti-aging agent;

[0043] Film-forming process: Same as in Example 1.

[0044] Example 6

[0045] The polyester film in this embodiment has a three-layer structure consisting of an unmodified PETG inner layer and a modified PETG outer layer.

[0046] The modified PETG outer film is prepared from the following raw materials in parts by weight: 100 parts of modified PETG with a polycarbonate ether unit ratio of 10%, 5 parts of maleic anhydride-styrene copolymer, 1 part of slip agent, and 0.5 parts of anti-aging agent.

[0047] The raw materials for preparing the unmodified PETG inner layer membrane include the following components in parts by weight: same as in Example 1;

[0048] Film-forming process: Same as in Example 1.

[0049] Example 7

[0050] The polyester film in this embodiment has a three-layer structure consisting of an unmodified PETG inner layer and a modified PETG outer layer.

[0051] The modified PETG outer film is prepared from the following raw materials in parts by weight: 70 parts of modified PETG with a polyether unit ratio of 8%, 30 parts of modified PETG with a polycarbonate ether unit ratio of 2%, 5 parts of maleic anhydride-styrene copolymer, 1 part of slip agent, and 0.5 parts of anti-aging agent.

[0052] The raw materials for preparing the unmodified PETG inner layer membrane include the following components in parts by weight: same as in Example 1;

[0053] Film-forming process: Same as in Example 1.

[0054] Comparative Example 1

[0055] The conventional unmodified PETG film is produced using a three-layer co-extrusion process, with both the inner and outer layers made of conventional PETG material.

[0056] Comparative Example 2

[0057] The formulation is the same as in Example 3, but the three-layer co-extrusion method is not used; the film consists of only one layer.

[0058] Note: 1. Comparative Example 1 is a conventional unmodified PETG film, which is produced by three-layer co-extrusion. Both the inner and outer layers are made of conventional PETG material.

[0059] 2. Comparative Example 2 is the same formulation as Example 3, but it does not use a three-layer co-extrusion method; the film consists of only one layer.

[0060] UV ink adhesion fastness test method: Apply the ink to the film with a squeegee and cure it with a UV lamp. Then, stick 3M tape onto the ink layer and press it back and forth 3 times with a 2 kg pressure roller. Let it stand for 30 or 60 seconds, and then quickly peel it off to observe the coating peeling. √ indicates that the ink has not peeled off, ○ indicates that the ink has peeled off in spots, and × indicates that the ink has peeled off in flakes.

[0061] The performance of the films in Examples 1 to 7 and Comparative Examples 1 to 2 was tested, and the test results are shown in Table 1:

[0062] Table 1. Performance test results of the thin films in Examples 1-7 and Comparative Examples 1-2

[0063]

[0064] As can be seen from Table 1, (1) the polyester film modified with polyether or polycarbonate ether has enhanced adhesion to UV-curable inks; (2) the modified polyester film has improved resistance to alkaline corrosion; (3) the modified polyester film has increased surface smoothness, significantly reduced friction coefficient, increased light transmittance, and reduced haze.

[0065] The above embodiments are merely illustrative of specific implementations of this disclosure, but the implementations of this disclosure are not limited to the above content. Any changes, modifications, substitutions, combinations, or simplifications made without substantially departing from the spirit and principle of the inventive concept of this disclosure shall be considered equivalent substitutions and included within the scope of protection defined by the claims.

Claims

1. A method for preparing a UV-printed polyester film for battery labels, characterized in that: The molecular structure of the UV-printed polyester film used for the battery label is as follows: or , The UV-printed polyester film for the battery label employs a multi-layer co-extrusion casting process, including the following specific steps: After weighing unmodified PETG raw material and polyether / polycarbonate ether modified raw material, the unmodified PETG raw material is fed into the inner twin-screw extruder, and the modified raw material is fed into the outer twin-screw extruder. A three-layer polyester casting is obtained through co-extrusion, and the relative thickness of the three layers is controlled by a metering pump. The casting is preheated, then longitudinally and / or laterally stretched, cooled, shaped, drawn, and collected. The product is a polyester film. The inner twin-screw extruder temperature is set to 240~260℃, the outer twin-screw extruder temperature is set to 190~235℃, the die temperature is 245~255℃, the preheating temperature is 60~90℃, the longitudinal stretching temperature is 80~105℃, the stretching ratio is 3.5~5 times, and the stretching rate is 80~120m / min; the transverse stretching temperature is 90~115℃, the stretching ratio is 3~5.7 times, and the stretching rate is 80~120m / min.

2. The method for preparing a UV-printed polyester film for battery labels as described in claim 1, characterized in that: The polyether unit is one or more of polypropylene glycol, polybutylene glycol, and polypentylene glycol units, and the molecular weight of the polyether ranges from 800 to 1800.

3. The method for preparing a UV-printed polyester film for battery labels as described in claim 1, characterized in that: The polycarbonate ether unit is generated by reacting propylene glycol ether, propylene oxide, and carbon dioxide, and the molecular weight of the polycarbonate ether ranges from 600 to 2000.

4. The method for preparing a UV-printed polyester film for battery labels as described in claim 1, characterized in that: The weight ratio of the polyether unit to the PETG unit is 4:96 to 20:

80.

5. The method for preparing a UV-printed polyester film for battery labels as described in claim 1, characterized in that: The weight ratio of the polycarbonate ether unit to the PETG unit is 2:98 to 10:

90.

6. The method for preparing a UV-printed polyester film for battery labels as described in claim 1, characterized in that: The polyether / polycarbonate ether is added in two ways: First, the polyether or polycarbonate ether is mixed with PETG, an appropriate amount of transesterification catalyst is added, and the PETG chips modified with polyether / polycarbonate ether are obtained after reactive twin-screw extrusion; Second, the polyether or polycarbonate ether is mixed with terephthalic acid, ethylene glycol, and neopentyl glycol, and the modified PETG chips are obtained after esterification and polycondensation reactions.

7. The method for preparing a UV-printed polyester film for battery labels as described in claim 6, characterized in that: The transesterification catalyst is zinc acetate or magnesium acetate.

8. The method for preparing a UV-printed polyester film for battery labels as described in claim 6, characterized in that: In addition method one, the transesterification catalyst is 50~300ppm. In addition method two, the molar fraction of terephthalic acid, ethylene glycol, and neopentyl glycol in the mixture is 5%~30%, and the molar ratio of alcohol to acid in terephthalic acid, ethylene glycol, and neopentyl glycol is 1~1.5:1.

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