High-gloss polyester base film and preparation process thereof

Abstract

The process comprises the following steps: S1, carrying out melt extrusion and curtain coating on raw materials of a first surface layer, a core layer and a second surface layer to prepare a base film casting sheet with a structure that the first surface layer, the core layer and the second surface layer are stacked in sequence; s2, preheating the base film casting sheet, longitudinally stretching under heating, and cooling to obtain a longitudinally stretched sheet; s3, coating the surface of the first surface layer and / or the second surface layer of the longitudinal stretching sheet with high-gloss coating liquid to obtain the longitudinal stretching sheet with the coating liquid; and S4, preheating the longitudinal stretching sheet with the coating liquid, carrying out transverse stretching under heating, curing the high-gloss coating liquid to form a coating, and carrying out heat setting and cooling to obtain the high-gloss polyester base film. According to the invention, the glossiness of the surface of the polyester film can be improved, the temperature resistance and flatness stability of the base film after high-temperature treatment are improved, and the obtained polyester base film product has the index of glossiness greater than 140GU.

Description

Technical Field

[0001] The invention relates to the technical field of film manufacturing, in particular to a high-gloss polyester base film and a preparation process thereof. Background Art

[0002] At present, the glossiness of polyester film produced by biaxial stretching is generally lower than 140GU (45° test), including ordinary bright products, whose glossiness is lower than 140GU (45° test), or matte products, which are divided into high, low and medium matte, and their glossiness is lower than 15-100GU; these two types of products are made of polyester chips (large glossy chips) and masterbatch (with anti-adhesion particles added) mixed and then cast by extrusion, and then made into polyester film by longitudinal and transverse biaxial stretching. The main factors affecting the glossiness of polyester film are the glossiness of polyester chips (large glossy chips) and the number and size of anti-adhesion particles in the masterbatch (with anti-adhesion particles added). The surface gloss of polyester film generally reduces the particle size or addition amount of anti-adhesion particles in the masterbatch (with anti-adhesion particles added). This means that the masterbatch is not used at most, and the gloss limit is the gloss of polyester chips (glossy chips). For example, patent CN201510662414 mentions that the gloss of polyester film is improved by improving the gloss of polyester chips (glossy chips), but the gloss limit is only 140GU (45° test), and this method must use 100% new polyester chips (glossy chips), and recycled materials cannot be used. This will result in a relatively high manufacturing cost, and the recycled materials generated in the process cannot be used. If used, the gloss of the product will be reduced. If the anti-adhesion masterbatch is not added to the surface layer, it will cause adhesion in the product process, resulting in the inability to produce continuously.

[0003] In order to solve the problem that the gloss of the product is affected by recycled materials, masterbatches, and glossy chips, it is necessary to provide a reliable solution. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a high-gloss polyester base film and a preparation process thereof in view of the deficiencies in the above-mentioned prior art.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: In a first aspect of the present invention, a preparation process of a high-gloss polyester base film is provided, comprising the following steps:

[0006] S1, melt-extrude and cast the raw materials of the first surface layer, the core layer and the second surface layer to prepare a base film casting sheet having a structure in which the first surface layer, the core layer and the second surface layer are stacked in sequence;

[0007] S2, preheating the base film casting sheet, longitudinally stretching it under heating, and cooling it to obtain a longitudinally stretched sheet;

[0008] S3, coating the first surface layer and / or the second surface layer of the longitudinally stretched sheet with a high gloss coating liquid to obtain a longitudinally stretched sheet with the coating liquid;

[0009] S4, preheating the longitudinally stretched sheet with the coating liquid, stretching it transversely under heating, and simultaneously curing the high-gloss coating liquid to form a coating, heat-setting, and cooling to obtain the high-gloss polyester base film;

[0010] The coating liquid comprises the following raw material components: a main agent resin, a curing resin, inorganic particles, a wetting agent, a pH regulator, a co-solvent and deionized water.

[0011] Preferably, the coating solution comprises the following raw material components in parts by weight:

[0012] 5-20 parts of main resin, 1.8-7.2 parts of curing resin, 1-4.5 parts of inorganic particles, 0.3-1.2 parts of wetting agent, 0.02-0.08 parts of pH adjuster, 15-60 parts of cosolvent, 25-100 parts of ionized water;

[0013] The pH value of the coating solution is 7.5-9.

[0014] Preferably, the main resin is at least one of a water-based polyester resin, a two-component water-based polyurethane and a one-component water-based polyurethane.

[0015] Preferably, the curing resin is at least one of a water-based isocyanate resin and a water-based melamine resin.

[0016] Preferably, the inorganic particles are silicon dioxide particles with a particle size of 30-130 nm.

[0017] Preferably, the pH adjuster is an alkaline substance.

[0018] Preferably, the co-solvent is one or a mixture of methanol, ethanol and isopropanol.

[0019] Preferably, the raw material of the core layer includes at least one of PET glossy chips and transparent recycled PET particles.

[0020] Preferably, the raw materials of the first surface layer and the second surface layer both include PET large glossy chips and anti-adhesion PET masterbatch, the anti-adhesion particles in the anti-adhesion PET masterbatch are silica particles with a particle size of 0.1-4.0 μm, and the concentration of silica particles in the anti-adhesion PET masterbatch is 2000ppm-10000ppm.

[0021] The second aspect of the present invention provides a high-gloss polyester base film, which is prepared by the process described above.

[0022] The beneficial effects of the present invention are:

[0023] The present invention provides a high-gloss polyester base film and a preparation process thereof. The present invention adopts an online coating process to coat a high-gloss coating liquid on the surface of a polyester film, thereby improving the glossiness of the surface of the polyester film, improving the temperature resistance and flatness stability of the base film after high-temperature treatment, and the obtained polyester base film product has a glossiness index of >140GU, ​​and the glossiness of the product is not affected by the slice raw materials. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below in conjunction with embodiments so that those skilled in the art can implement the invention with reference to the description.

[0025] It should be understood that the terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0026] The test methods used in the following examples are conventional methods unless otherwise specified. The materials and reagents used in the following examples are all commercially available unless otherwise specified. In the following examples, if no specific conditions are specified, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used, if the manufacturer is not specified, are all conventional products that can be purchased commercially.

[0027] The present invention provides a preparation process of a high-gloss polyester base film, comprising the following steps:

[0028] S1, melt-extrude and cast the raw materials of the first surface layer, the core layer and the second surface layer to prepare a base film casting sheet having a structure in which the first surface layer, the core layer and the second surface layer are stacked in sequence;

[0029] S2, preheating the base film casting sheet, longitudinally stretching it under heating, and cooling it to obtain a longitudinally stretched sheet;

[0030] S3, coating the first surface layer and / or the second surface layer of the longitudinally stretched sheet with a high gloss coating liquid to obtain a longitudinally stretched sheet with the coating liquid;

[0031] S4, preheating the longitudinally stretched sheet with the coating liquid, stretching it transversely under heating, and simultaneously curing the high-gloss coating liquid to form a coating, heat-setting, and cooling to obtain a high-gloss polyester base film;

[0032] Among them, the coating process is online coating, and the coating method is one of micro gravure coating, D-bar coating, and doctor blade coating, or a combination of 2-3 methods.

[0033] In a preferred embodiment, the coating solution includes the following raw material components: a main agent resin, a curing resin, inorganic particles, a wetting agent, a pH adjuster, a co-solvent and deionized water.

[0034] In a preferred embodiment, the main resin is at least one of a water-based polyester resin, a two-component water-based polyurethane and a one-component water-based polyurethane, and more preferably a mixture of the three.

[0035] In a preferred embodiment, the curing resin is at least one of a water-based isocyanate resin and a water-based melamine resin.

[0036] In a preferred embodiment, the inorganic particles are silicon dioxide particles with a particle size of 30-130 nm.

[0037] In a preferred embodiment, the pH adjuster is an alkaline substance, such as a base, a salt or an organic amine, and more preferably an amine compound.

[0038] In a preferred embodiment, the co-solvent is a low-carbon alcohol organic solvent, such as one or a mixture of methanol, ethanol, and isopropanol. In order to achieve the best film-forming effect and defoaming effect, the co-solvent is more preferably isopropanol.

[0039] In a preferred embodiment, the coating solution includes the following raw material components by weight:

[0040] 5-20 parts of main resin, 1.8-7.2 parts of curing resin, 1-4.5 parts of inorganic particles, 0.3-1.2 parts of wetting agent, 0.02-0.08 parts of pH adjuster, 15-60 parts of cosolvent, 25-100 parts of ionized water;

[0041] The pH value of the coating liquid is 7.5-9.

[0042] In a preferred embodiment, the raw material of the core layer includes at least one of PET glossy chips and transparent recycled PET particles.

[0043] In a preferred embodiment, the raw materials of the first surface layer and the second surface layer both include PET large glossy chips and anti-adhesion PET masterbatch, the anti-adhesion particles in the anti-adhesion PET masterbatch are silica particles with a particle size of 0.1-4.0 μm, and the concentration of silica particles in the anti-adhesion PET masterbatch is 2000ppm-10000ppm.

[0044] The present invention also provides a high-gloss polyester base film, which is prepared by the above process.

[0045] The above is the overall concept of the present invention, and detailed embodiments and comparative examples are provided below on the basis of the overall concept of the present invention to further illustrate the present invention.

[0046] Example 1

[0047] A high-gloss polyester base film, the preparation process of which comprises the following steps:

[0048] S1, the raw material of the first surface layer, the raw material of the core layer and the raw material of the second surface layer are batched by a batching system, melt-extruded (temperature is 285° C.), and cast to prepare a base film casting sheet having a structure in which the first surface layer, the core layer and the second surface layer are stacked in sequence;

[0049] S2, the base film casting sheet is preheated to about 88°C by rollers at 72°C, 78°C, 80°C, 82°C, 84°C, 86°C, and 88°C in sequence, and longitudinally stretched at 90°C-92°C (using an infrared lamp auxiliary heater for auxiliary heating, so the film temperature is an interval temperature), with a stretching ratio of 3.2, and then cooled to obtain a longitudinally stretched sheet;

[0050] S3, coating the first surface layer and the second surface layer of the longitudinally stretched sheet with a high gloss coating liquid (coating amount 6 g / ㎡) to obtain a longitudinally stretched sheet with the coating liquid;

[0051] S4. Preheat the longitudinally stretched sheet with the coating to 108°C, and continuously and sequentially stretch it transversely in four stretching zones at 112°C, 114°C, 118°C, and 120°C, respectively, with a total transverse stretching ratio of 3.67. At the same time, cure the high-gloss coating to form a coating (the thickness of the coating after curing is 40nm), heat-set at 230°C, and then cool to room temperature at 160°C, 105°C, and 50°C, respectively, to obtain a high-gloss polyester base film; wherein, the coating process is online coating, and the coating method is blade coating.

[0052] Among them, the raw materials of the first surface layer and the second surface layer include 50wt% of PET large glossy chips (Yizheng Chemical Fiber FG600) and 30wt% of anti-adhesion masterbatch (Yizheng Chemical Fiber FG610). The anti-adhesion particles in the anti-adhesion PET masterbatch are silica particles with a particle size of 3.0um, and the concentration of silica particles in the anti-adhesion PET masterbatch is 3500ppm.

[0053] The raw materials of the core layer include 80wt% of PET high gloss chips (Yizheng Chemical Fiber FG600) and 20wt% of transparent recycled PET particles (transparent PET particles recycled in the product production process).

[0054] In a preferred embodiment, the raw materials of the first surface layer and the second surface layer both include PET large glossy chips and anti-adhesion PET masterbatch, the anti-adhesion particles in the anti-adhesion PET masterbatch are silica particles with a particle size of 0.1-4.0 μm, and the concentration of silica particles in the anti-adhesion PET masterbatch is 2000ppm-10000ppm.

[0055] The coating solution includes the following raw material components by weight:

[0056] 10.7 parts of main resin, 3.6 parts of curing resin, 2.25 parts of inorganic particles, 0.62 parts of wetting agent, 0.04 parts of pH adjuster, 30.5 parts of cosolvent, 52.29 parts of ionized water. The above raw materials are mixed evenly to obtain a coating liquid with a pH value of 8.6.

[0057] The main resin includes: 1.5 parts of water-based polyester resin (RZ-570 from Huying Chemical), 5 parts of two-component water-based polyurethane (water-based polyurethane from DSM), 4.2 parts of one-component water-based polyurethane (HUX-3560 from Idico),

[0058] The inorganic particles include: 2 parts of LEVASIL30 from Grace Ludox and 0.25 parts of MP1040 from Nissan Chemical;

[0059] The wetting agent includes: BYK-349 of BYK: 0.5 parts, EXP.42000 of Nissin Chemical: 0.12 parts;

[0060] The pH regulator was ammonia water (Taixing Yimin Chemical), and the cosolvent was isopropanol (Nanjing Beihua Chemical).

[0061] Example 2

[0062] Based on Example 1, the difference is that the core layer is composed of 100% PET high gloss chips (Yizheng Chemical Fiber FG600) and 0% transparent recycled particles (transparent particles recycled during the product production process).

[0063] Example 3

[0064] Based on Example 1, the difference is that the core layer is composed of 0% PET high gloss chips (Yizheng Chemical Fiber FG600) and 100% transparent recycled particles (transparent particles recycled during the product production process).

[0065] Example 4

[0066] Based on Example 1, except that single-sided coating was used.

[0067] Example 5

[0068] Based on Example 2, except that single-sided coating was used.

[0069] Example 6

[0070] Based on Example 3, except that single-sided coating was used.

[0071] Example 7

[0072] Based on Example 1, the difference is that the first and second surface layers include 0% PET glossy chips (Yizheng Chemical Fiber FG600) and 100% anti-adhesion masterbatch (Yizheng Chemical Fiber FG610).

[0073] Example 8

[0074] Based on Example 1, the difference is that the first and second surface layers include 100% PET glossy chips (Yizheng Chemical Fiber FG600) and 0% anti-adhesion masterbatch (Yizheng Chemical Fiber FG610).

[0075] Example 9

[0076] Based on Example 7, except that single-sided coating was used.

[0077] Example 10

[0078] Based on Example 8, except that single-sided coating was used.

[0079] Embodiment 11

[0080] Based on Example 7, the difference is that the core layer is composed of 0% PET high gloss chips (Yizheng Chemical Fiber FG600) and 100% transparent recycled particles (transparent particles recycled during the product production process).

[0081] Example 12

[0082] Based on Example 9, the difference is that the core layer is composed of 0% PET high gloss chips (Yizheng Chemical Fiber FG600) and 100% transparent recycled granules (transparent particles recycled during the product production process).

[0083] Comparative Example 1

[0084] The comparative example is based on Example 1, except that no in-line coating was performed on both sides.

[0085] Comparative Example 2

[0086] The comparative example is based on Example 2, except that no in-line coating was performed on both sides.

[0087] Comparative Example 3

[0088] The comparative example is based on Example 3, except that no in-line coating is performed on both sides.

[0089] Comparative Example 4

[0090] The comparative example is based on Example 7, except that no in-line coating was performed on both sides.

[0091] Comparative Example 5

[0092] The comparative example is based on Example 8, except that no in-line coating was performed on both sides.

[0093] Comparative Example 6

[0094] The comparative example is based on Example 11, except that no in-line coating was performed on both sides.

[0095] The high gloss polyester base film prepared in the examples and comparative examples was tested for properties such as haze, light transmittance, and glossiness. The testing method is as follows:

[0096] 1. Haze and transmittance: Use German BYK company AT-4725 transmission haze meter, according to standard ASTM D1003;

[0097] 2. Gloss: Use German BYK 4567 micro gloss meter according to ASTM D2457;

[0098] The test results are shown in Table 1 below:

[0099] Table 1

[0100]

[0101]

[0102] Note: “ / ” indicates that it is not the item or the test is not conducted, and “▲” indicates that it belongs to the item.

[0103] Through Examples 1-12, it can be found that no matter how the surface layer or the core layer changes, as long as the coating treatment of this solution is used, whether it is single-sided or double-sided, the glossiness of the coated side is greater than 140GU. From Examples 4-12 and Comparative Examples 1-6, it can be found that the glossiness of the surface layer without coating is less than 140GU.

[0104] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to specific details.

Claims

1. A process for preparing a high gloss polyester base film, characterized in that: The following steps are involved: S1, melt-extrude and cast the raw materials of the first surface layer, the core layer and the second surface layer to prepare a base film casting sheet having a structure in which the first surface layer, the core layer and the second surface layer are stacked in sequence; S2, preheating the base film casting sheet, longitudinally stretching it under heating, and cooling it to obtain a longitudinally stretched sheet; S3, coating the first surface layer and / or the second surface layer of the longitudinally stretched sheet with a high gloss coating liquid to obtain a longitudinally stretched sheet with the coating liquid; S4, preheating the longitudinally stretched sheet with the coating liquid, stretching it transversely under heating, and simultaneously curing the high-gloss coating liquid to form a coating, heat-setting, and cooling to obtain the high-gloss polyester base film; The coating liquid comprises the following raw material components: a main agent resin, a curing resin, inorganic particles, a wetting agent, a pH regulator, a co-solvent and deionized water.

2. The process for preparing the high gloss polyester base film according to claim 1, characterized in that: The coating solution includes the following raw material components by weight: 5-20 parts of main resin, 1.8-7.2 parts of curing resin, 1-4.5 parts of inorganic particles, 0.3-1.2 parts of wetting agent, 0.02-0.08 parts of pH adjuster, 15-60 parts of cosolvent, 25-100 parts of ionized water; The pH value of the coating solution is 7.5-9.

3. The process for preparing the high gloss polyester base film according to claim 2, characterized in that: The main resin is at least one of water-based polyester resin, two-component water-based polyurethane and one-component water-based polyurethane.

4. The process for preparing the high gloss polyester base film according to claim 2, characterized in that: The curing resin is at least one of a water-based isocyanate resin and a water-based melamine resin.

5. The process for preparing the high gloss polyester base film according to claim 2, characterized in that: The inorganic particles are silicon dioxide particles with a particle size of 30-130 nm.

6. The process for preparing the high gloss polyester base film according to claim 2, characterized in that: The pH adjuster is an alkaline substance.

7. The process for preparing the high gloss polyester base film according to claim 2, characterized in that: The co-solvent is one of methanol, ethanol and isopropanol or a mixture of several of them.

8. The process for preparing the high gloss polyester base film according to claim 1, characterized in that: The raw material of the core layer includes at least one of PET glossy chips and transparent recycled PET particles.

9. The process for preparing the high gloss polyester base film according to claim 1, characterized in that: The raw materials of the first surface layer and the second surface layer both include PET large glossy chips and anti-adhesion PET masterbatch. The anti-adhesion particles in the anti-adhesion PET masterbatch are silicon dioxide particles with a particle size of 0.1-4.0 μm, and the concentration of silicon dioxide particles in the anti-adhesion PET masterbatch is 2000ppm-10000ppm.

10. A high gloss polyester base film, characterized in that: The method is prepared by the process as described in any one of claims 1 to 9.

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