A heat-sealable single-side touch-feeling single-side haze degradable film and a preparation method thereof

Abstract

The application belongs to the technical field of protective film and specifically discloses a heat-sealable single-side touch-feeling single-side mist-degradable film and a preparation method thereof, wherein the degradable film comprises, from inside to outside, a heat-seal layer, an intermediate layer, a surface layer and a touch-feeling layer; the heat-seal layer, the intermediate layer and the surface layer are prepared by three-layer flow casting co-extrusion and bidirectional stretching; the touch-feeling layer is obtained by coating adhesive by means of a network roller and is connected with the surface layer; the heat-seal layer comprises 67.0-77.5 wt% crystalline polylactic acid chips, 21.9-31.0 wt% non-crystalline polylactic acid chips, 0.50-1.00 wt% opening agent and 0.10-1.00 wt% slip agent; the intermediate layer comprises 100 wt% crystalline polylactic acid chips; the surface layer comprises 91.6-95.0 wt% crystalline polylactic acid chips, 4.4-6.4 wt% non-crystalline polylactic acid chips, 0.50-1.00 wt% opening agent and 0.10-1.00 wt% slip agent; and the touch-feeling layer is composed of water-based polyurethane dispersion, touch-feeling aid, crosslinking agent and water in a mass ratio of (90.0-92.5):(10.0-15.0):(1.00-5.00):(45.5-50.0).

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of protective film, and particularly relates to a heat-sealable single-side touch-feeling single-side fog-degradable film and a preparation method thereof. BACKGROUND

[0002] The film is more and more favored by people in the packaging field, and can be used to make bags to package food, and can be used as a protective film to protect the surface, such as high-grade gift boxes, hardcover book covers, electronic covers and the like. Although there are many types of protective films on the market, most of them are mainly transparent materials. With the improvement of living standards, people are no longer limited to the single nature of transparent materials, but pursue the diversity of vision, and the product printing color is realistic, the appearance is quiet and elegant, and the hand feeling is comfortable and the like, which are more and more favored by people.

[0003] The protective film has touch feeling and fog, and can provide better use experience and visual effect. The touch feeling usually relates to the surface hardness and smoothness of the protective film, and the soft and smooth touch feeling often makes the user feel more comfortable when touching. The fog relates to the transparency of the protective film, and a certain degree of fog can make the vision softer, reduce the visual discomfort caused by reflection, and also can provide a certain degree of privacy protection. The protective film with touch feeling and fog is often applied to the surface of liquid crystal display, mobile phone screen, personal computer screen, audio-visual equipment, finishing panel, plastic plate, glass, acrylic plate and the like, to provide physical protection, prevent scratching, wear, dust, fingerprints and the like, and also can improve the visual and touch experience of the user.

[0004] The existing protective film with fog on the market can see the object inside through the film, but the font clarity is low, which is due to the low light transmittance and poor gloss. And these films do not have touch feeling, and the hand feeling is single. Moreover, the film generally adopts PA material, PP material or PET material and the like, which not only does not have heat-sealing performance, but also most of them add powder to the fog surface layer, which not only has poor dispersibility, but also easily causes the film to have particles, low fog, high gloss and low light transmittance. Moreover, these materials cannot be biodegraded after being discarded, and can cause the phenomenon of "white pollution". SUMMARY

[0005] The present application aims to overcome the defects in the prior art, and provides a heat-sealable single-side touch-feeling single-side fog-degradable film and a preparation method thereof, which solves the problems of low fog, high gloss and low light transmittance, and also solves the problems of no heat-sealing performance of the film, poor hand comfort and non-biodegradability.

[0006] In order to achieve the above object, one of the technical solutions of the present application is: a heat-sealable single-side touch-feeling single-side mist-degradable film, comprising a four-layer structure, from inside to outside comprising a heat-seal layer, an intermediate layer, a surface layer and a touch-feeling layer; the heat-seal layer, the intermediate layer and the surface layer are prepared by three-layer flow casting co-extrusion and bidirectional stretching; the touch-feeling layer is obtained by coating glue on a networked roller, and is connected with the surface layer.

[0007] In a preferred embodiment of the present application, the heat-seal layer comprises 67.0-77.5 wt% crystalline polylactic acid chips, 21.9-31.0 wt% non-crystalline polylactic acid chips, 0.50-1.00 wt% opening agent and 0.10-1.00 wt% slip agent.

[0008] In a preferred embodiment of the present application, the intermediate layer comprises 100 wt% crystalline polylactic acid chips.

[0009] In a preferred embodiment of the present application, the surface layer comprises 91.6-95.0 wt% crystalline polylactic acid chips, 4.4-6.4 wt% non-crystalline polylactic acid chips, 0.50-1.00 wt% opening agent and 0.10-1.00 wt% slip agent.

[0010] In a preferred embodiment of the present application, the slip agent is one or more combinations of erucic acid amide, oleic acid amide, silicone oil, silicone, polyethylene wax.

[0011] In a preferred embodiment of the present application, the opening agent is one or more combinations of silicon dioxide, talc, zeolite, diatomite, calcium carbonate, clay.

[0012] In a preferred embodiment of the present application, the touch-feeling layer is composed of water-based polyurethane dispersion, touch-feeling aid, crosslinking agent and water in a mass ratio of (90.0-92.5):(10.0-15.0):(1.00-5.00):(45.5-50.0).

[0013] Further preferably, the water-based polyurethane dispersion is composed of polyether polyol, polyester polyol and isocyanate in a mass ratio of (20.0-25.5):(35.0-38.2):(10.2-13.5).

[0014] More preferably, the polyether polyol is one or a combination of polyether diol, polyether tetraol, polytetrahydrofuran diol, polyethylene oxide diol; the polyester polyol is one or a combination of poly-epsilon-caprolactone diol, polyethylene adipate-1,4-butanediol diol, poly-1,6-hexanediol carbonate diol; the isocyanate is one or a combination of hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, 1,4-cyclohexane diisocyanate, diphenylmethane diisocyanate.

[0015] Further preferably, the touch feel aid is composed of polymethylsilsesquioxane, polydimethylsiloxane and cetyl stearyl polymethylsiloxane in a mass ratio of (24.0-30.0):(10.2-15.0):(2.20-3.50).

[0016] Further preferably, the crosslinking agent is one or a combination of polycarbodiimide crosslinking agent, aliphatic polyisocyanate (HDI trimer) crosslinking agent.

[0017] In a preferred embodiment of the present application, the thickness of the heat-seal layer is 2.0-3.0 μm, the thickness of the surface layer is 3.0-4.0 μm, the thickness of the intermediate layer is 8.0-35.0 μm, and the thickness of the touch feel layer is 1.0-2.0 μm.

[0018] To achieve the above object, the second technical solution of the present application is a method for preparing a heat-sealable single-side touch feel single-side haze degradable film, comprising the following steps:

[0019] (1) mixing the water-based polyurethane dispersion according to the mass ratio of the touch feel layer, then adding the touch feel aid and stirring until uniform, diluting with water first, stirring until uniform, then adding the crosslinking agent, stirring until uniform, standing, and defoaming to obtain the touch feel layer coating;

[0020] (2) mixing the crystalline polylactic acid chips, the non-crystalline polylactic acid chips, the opening agent and the slip agent according to the mass ratio of the heat-seal layer, and then melting, blending, extruding and granulating through a double-screw extruder to obtain the inner layer master batch;

[0021] (3) mixing the crystalline polylactic acid chips, the non-crystalline polylactic acid chips, the opening agent and the slip agent according to the mass ratio of the surface layer, and then melting, blending, extruding and granulating through a double-screw extruder to obtain the surface layer master batch;

[0022] (4) feeding the crystalline polylactic acid chips into the main machine of a three-layer co-extrusion casting extruder to obtain the intermediate layer, and feeding the master batches obtained in steps (2) and (3) into two auxiliary machines respectively to obtain the heat-seal layer and the surface layer respectively;

[0023] (5) the raw material mixture of each film layer is respectively melted and extruded by different extruders at a temperature range of 180-210 DEG C, and then converged in the same T-shaped die, and the solution is cooled by a cooling roller to form a casting sheet;

[0024] (6) the casting sheet obtained in step (5) is first stretched in the longitudinal direction, and then the surface layer is treated by corona treatment;

[0025] (7) the coating for the touch layer obtained in step (1) is poured into a coating agent glue tank, and then the PLA film obtained in step (6) is coated on both surfaces by the coating agent through the network pattern roller coating method, and then dried at a temperature of 80-120 DEG C, stretched in the transverse direction, shaped, wound, and then aged at 45-50 DEG C for 24-48h to obtain a heat-sealable single-touch single-fog degradable film.

[0026] Compared with the prior art, the present application has the following beneficial effects:

[0027] 1. The crystalline polylactic acid chip and the non-crystalline polylactic acid chip used in the present application are biodegradable.

[0028] 2. The heat-sealing layer of the present application uses crystalline polylactic acid chips and non-crystalline polylactic acid chips, so that the temperature during heat sealing does not need to be too high, and excellent heat sealing effect can be achieved at 80 DEG C, and the heat sealing strength is excellent.

[0029] 3. The middle layer of the present application uses 100% crystalline polylactic acid chips, which can ensure the overall tensile strength and other physical properties of the film.

[0030] 4. Although the surface layer of the present application also uses crystalline polylactic acid chips and non-crystalline polylactic acid chips, the proportion of crystalline polylactic acid chips is relatively high, which is to ensure that the surface has sufficient temperature resistance and does not melt when heat sealing; at the same time, the surface is treated by corona treatment, thereby increasing the bonding force with the touch layer.

[0031] 5. The water-based polyurethane dispersion in the touch layer of the present application is made of polyester polyol and polyether polyol, which not only has excellent hydrolysis resistance, wear resistance, temperature resistance and adhesion, but also has high haze and high transparency; the touch aid in the touch layer is composed of polymethylsilsesquioxane, polydimethylsiloxane and cetyl stearyl polymethylsiloxane, which solves the problem of difficult dispersion of traditional powder, and at the same time, polymethylsilsesquioxane can increase the smoothness of the surface, reduce the gloss and enhance the touch; polydimethylsiloxane can make the coating smooth and delicate, increase the adhesion of the coating, and at the same time, form a three-dimensional network structure in the coating, enhance the wear resistance and water resistance; has easy biodegradation, which can increase the skin feeling of the coating and increase the leveling property of the coating; cetyl stearyl polymethylsiloxane can increase the water resistance of the coating, and at the same time, improve the adhesion and durability of the coating, making the coating more firm; the crosslinking agent in the touch layer makes the coating form a three-dimensional network structure, increases the adhesion of the coating to the substrate, and at the same time, increases the temperature resistance and water resistance of the coating. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The layer structure diagram of the heat-sealable single-sided touch single-sided haze degradable film of Example 1.

[0033] Among them, 10 is a heat-sealable layer, 20 is an intermediate layer, 30 is a surface layer, and 40 is a touch layer. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the present application clearer and more apparent, the present application is described in more detail below in combination with the drawings and specific examples, but the protection scope of the present application is not limited to these examples. The same reference signs in the text always represent the same elements, and similar reference signs represent similar elements.

[0035] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "horizontal", "vertical", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the perspective view of the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0036] Example 1

[0037] The application discloses a heat-sealable single-side touch-feeling single-side mist-degradable film, which comprises a four-layer structure from inside to outside, namely a heat-seal layer, an intermediate layer, a surface layer and a touch-feeling layer; the heat-seal layer, the intermediate layer and the surface layer are prepared by three-layer flow casting co-extrusion and bidirectional stretching; the touch-feeling layer is obtained by coating glue on a netted roller and is connected with the surface layer; the heat-seal layer is composed of 67.0 wt% of crystallized polylactic acid chips, 31.0 wt% of non-crystallized polylactic acid chips, 1.00 wt% of an opening agent and 1.00 wt% of a slip agent; the intermediate layer is composed of 100 wt% of crystallized polylactic acid chips; the surface layer is composed of 91.6 wt% of crystallized polylactic acid chips, 6.4 wt% of non-crystallized polylactic acid chips, 1.00 wt% of an opening agent and 1.00 wt% of a slip agent; the slip agent is composed of a combination of erucic acid amide and oleic acid amide; the opening agent is composed of a combination of silicon dioxide and talcum powder; the touch-feeling layer is composed of a water-based polyurethane dispersion, a touch-feeling aid, a cross-linking agent and water in a mass ratio of 90.0:10.0:1.00:45.5; the water-based polyurethane dispersion is composed of polyether polyol, polyester polyol and isocyanate; the polyether polyol, the polyester polyol and the isocyanate are composed in a mass ratio of 25.5:38.2:13.5; the polyether polyol is composed of polyethylene oxide; the polyester polyol is composed of polyethylene glycol-1,4-butanediol adipate diol; the isocyanate is composed of hexamethylene diisocyanate; the touch-feeling aid is composed of polymethylsilsesquioxane, polydimethylsiloxane and cetyl stearyl polymethylsiloxane in a mass ratio of 24.0:10.2:2.20; the cross-linking agent is composed of a polycarbodiimide cross-linking agent; the thickness of the heat-seal layer is 2.0 microns; the thickness of the surface layer is 3.0 microns; the thickness of the intermediate layer is 10.0 microns; and the thickness of the touch-feeling layer is 1.0 micron.

[0038] The method comprises the following steps:

[0039] Step one: the water-based polyurethane dispersion required by the touch-feeling layer is weighed in proportion, then the touch-feeling aid is added and stirred uniformly, water is added for dilution and adjustment, then the cross-linking agent is added and stirred uniformly, and the coating for the touch-feeling layer is obtained after standing, defoaming and the like;

[0040] Step two: the crystallized polylactic acid chips, the non-crystallized polylactic acid chips, the opening agent and the slip agent are blended, extruded and granulated through a double-screw extruder according to the proportion of the heat-seal layer to obtain the master batch for the inner layer, which is ready for use;

[0041] Step three: the crystallized polylactic acid chips for the intermediate layer are ready for use;

[0042] Step four: the crystallized polylactic acid chips, the non-crystallized polylactic acid chips, the opening agent and the slip agent are blended, extruded and granulated through a double-screw extruder according to the proportion of the surface layer to obtain the master batch for the surface layer, which is ready for use.

[0043] Step five: put the slice of step four into the main machine of three-layer co-extrusion casting extruder to make the middle layer; put the master batch of step two and step three into two auxiliary machines respectively to make the hot heat-seal layer and the surface layer respectively;

[0044] Step six: melt and extrude the mixture of raw materials of each film layer by different extruders at a temperature range of 180-210°C, and converge them in the same T-shaped die head, and then leave the melt to pass through the cooling roller to form a casting sheet;

[0045] Step seven: then stretch the casting sheet obtained in step six in the longitudinal direction, and then perform corona treatment on the surface layer;

[0046] Step eight: pour the coating for the touch layer obtained in step one into the coating agent tank, and then coat the coating for the upper and lower surface layers on both sides of the PLA film by the method of coating agent anilox roll coating, and then dry at a temperature of 80-120°C, stretch in the transverse direction during drying, shape, wind up, and then put into the oven at 45°C for 48h to obtain a heat-sealable single-touch single-fog degradable film.

[0047] Example 2

[0048] A heat-sealable single-touch single-fog degradable film, the preparation method of which is the same as that of example 1, and the difference from example 1 is that the heat-seal layer is composed of 77.5wt% of crystalline polylactic acid slice, 21.9wt% of non-crystalline polylactic acid slice, 0.50wt% of opening agent and 0.10wt% of slip agent; the middle layer is composed of 100wt% of crystalline polylactic acid slice; the surface layer is composed of 95.0wt% of crystalline polylactic acid slice, 4.4wt% of non-crystalline polylactic acid slice, 0.50wt% of opening agent and 0.10wt% of slip agent; the touch layer is composed of water-based polyurethane dispersion, touch aid, crosslinking agent and water in a mass ratio of 92.5:15.0:5.00:50.0; the touch aid is composed of polymethylsilsesquioxane, polydimethylsiloxane and cetyl stearyl polymethylsiloxane in a mass ratio of 30.0:15.0:3.50.

[0049] Example 3

[0050] A heat sealable single touch-feel single haze degradable film, the preparation method is the same as example 1, and the difference from example 1 is that the heat seal layer is composed of 72.75wt% of crystalline polylactic acid chip, 26.0wt% of non-crystalline polylactic acid chip, 0.75wt% of opening agent and 0.50wt% of slip agent; the intermediate layer is composed of 100wt% of crystalline polylactic acid chip; the surface layer is composed of 93.75wt% of crystalline polylactic acid chip, 5.00wt% of non-crystalline polylactic acid chip, 0.70wt% of opening agent and 0.55wt% of slip agent; the touch-feel layer is composed of water-based polyurethane dispersion, touch-feel auxiliary agent, crosslinking agent and water in a mass ratio of 91.0:12.0:3.0:47.0; the touch-feel auxiliary agent is composed of polymethylsilsesquioxane, polydimethylsiloxane and cetyl stearyl polymethylsiloxane in a mass ratio of 27.0:12.7:3.00;

[0051] Example 4

[0052] A heat sealable single touch-feel single haze degradable film, the preparation method is the same as example 1, and the difference from example 1 is that the slip agent is composed of oleic acid amide and silicone oil; the opening agent is composed of talc, zeolite and diatomite; the polyether polyol is composed of polyoxyethylene glycol and polyether glycol; the polyester polyol is composed of polyethylene glycol-1,4-butanediol adipate diol and poly-1,6-hexanediol carbonate diol; the isocyanate is diphenylmethane diisocyanate.

[0053] Example 5

[0054] A heat sealable single touch-feel single haze degradable film, the preparation method is the same as example 1, and the difference from example 1 is that the crosslinking agent is composed of aliphatic polyisocyanate (HDI trimer) crosslinking agent.

[0055] Example 6

[0056] A heat sealable single touch-feel single haze degradable film, the preparation method is the same as example 1, and the difference from example 1 is that the thickness of the heat seal layer is 3.0μm; the thickness of the surface layer is 4.0μm; the thickness of the intermediate layer is 18.0μm; the thickness of the touch-feel layer is 2.0μm.

[0057] Comparative example 1

[0058] A degradable film, comprising a four-layer structure, from inside to outside in turn is heat-sealing layer, intermediate layer, surface layer and touch layer, the thickness of heat-sealing layer is 2.0 μm, the thickness of surface layer is 3.0 μm; the thickness of intermediate layer is 10.0 μ; heat-sealing layer, intermediate layer and surface layer are prepared by three-layer flow casting co-extrusion and bidirectional stretching; the preparation method of degradable film is same as example 1, the difference is that no coating layer is prepared, heat-sealing layer is composed of 67.0 wt% of crystalline polylactic acid chip, 31.0 wt% of non-crystalline polylactic acid chip, 1.00 wt% of opening agent and 1.00 wt% of slip agent; intermediate layer is composed of 100 wt% of crystalline polylactic acid chip; surface layer is composed of 91.6 wt% of crystalline polylactic acid chip, 6.4 wt% of non-crystalline polylactic acid chip, 1.00 wt% of opening agent and 1.00 wt% of slip agent; slip agent is composed of erucic acid amide and oleic acid amide combination; opening agent is composed of silicon dioxide and talcum powder combination.

[0059] Comparative example 2

[0060] A degradable film, the preparation method is same as example 1, and the difference from example 1 is that: heat-sealing layer is composed of 91.6 wt% of crystalline polylactic acid chip, 6.40 wt% of non-crystalline polylactic acid chip, 1.00 wt% of opening agent and 1.00 wt% of slip agent; intermediate layer is composed of 100 wt% of crystalline polylactic acid chip; surface layer is composed of 91.6 wt% of crystalline polylactic acid chip, 6.40 wt% of non-crystalline polylactic acid chip, 1.00 wt% of opening agent and 1.00 wt% of slip agent.

[0061] Comparative example 3

[0062] A degradable film, the preparation method is same as example 1, and the difference from example 1 is that: touch layer is composed of water-based polyurethane dispersion, touch aid, crosslinking agent and water in a mass ratio of 60.0:10.0:1.00:45.5.

[0063] Comparative example 4

[0064] A degradable film, the preparation method is same as example 1, and the difference from example 1 is that: touch layer is composed of water-based polyurethane dispersion, crosslinking agent and water in a mass ratio of 90.0:1.00:45.5; polyether polyol is composed of polyethylene oxide alcohol; the polyester polyol is composed of polyethylene glycol-1,4-butanediol adipate diol; the isocyanate is composed of hexamethylene diisocyanate; the crosslinking agent is composed of polycarbodiimide crosslinking agent;

[0065] Comparative example 5

[0066] A degradable film, the preparation method is same with example 1, the difference with example 1 is that the touch layer is composed of water-based polyurethane dispersion, touch aid, crosslinking agent and water with the mass ratio of 90.0:5.00:1.00:45.5.

[0067] Comparative example 6

[0068] A degradable film, the preparation method is same with example 1, the difference with example 1 is that the touch layer is composed of water-based polyurethane dispersion, touch aid, crosslinking agent and water with the mass ratio of 90.0:30.0:1.00:45.5.

[0069] Comparative example 7

[0070] A degradable film, the preparation method is same with example 1, the difference with example 1 is that the touch layer is composed of water-based polyurethane dispersion, touch aid and water with the mass ratio of 90.0:10.0:45.5; the water-based polyurethane dispersion is composed of polyether polyol, polyester polyol and isocyanate; the polyether polyol is composed of polyethylene oxide alcohol; the polyester polyol is composed of polyethylene glycol-1,4-butanediol adipate diol; the isocyanate is hexamethylene diisocyanate; the touch aid is composed of polymethylsilsesquioxane, polydimethylsiloxane and cetyl stearyl polymethylsiloxane with the mass ratio of 24.0:10.2:2.20.

[0071] Comparative example 8

[0072] A degradable film, the preparation method is same with example 1, the difference with example 1 is that the touch layer is composed of water-based polyurethane dispersion, touch aid, crosslinking agent and water; the touch aid is composed of polymethylsilsesquioxane, polydimethylsiloxane, cetyl stearyl polymethylsiloxane with the mass ratio of 12.0:10.2:2.20.

[0073] Comparative example 9

[0074] A degradable film, the preparation method is same with example 1, the difference with example 1 is that the touch layer is composed of water-based polyurethane dispersion, touch aid, crosslinking agent and water; the touch aid is composed of polymethylsilsesquioxane, polydimethylsiloxane, cetyl stearyl polymethylsiloxane with the mass ratio of 24.0:5.00:2.20.

[0075] Comparative example 10

[0076] A degradable film, the preparation method is same with example 1, the difference with example 1 is that the touch layer is composed of water-based polyurethane dispersion, touch aid, crosslinking agent and water; the touch aid is composed of polymethylsilsesquioxane, polydimethylsiloxane, cetyl stearyl polymethylsiloxane with the mass ratio of 24.0:10.2:1.00.

[0077] The bidirectional stretched polyamide films prepared in the above examples and comparative examples were tested for performance according to the following test standards and methods:

[0078] I. Light transmittance and haze test

[0079] Tested according to GB 2410-1980 Test Method for Light Transmittance and Haze of Transparent Plastics;

[0080] II. Gloss test

[0081] Tested according to GB / T 8807-1988 Test Method for Specular Gloss of Plastics;

[0082] III. Scratch and abrasion resistance test

[0083] The cut sample was fastened with a clamp, the testing surface (coating surface) was horizontal, the sample surface must be flat, free of bubbles and impurities, etc. The abrasion tester LT803 (Dongguan Longtian Instrument and Equipment Co., Ltd.) was set up, the speed range was set at 30 times / min, the travel range was set at 0-50 mm, the weight and material positions were adjusted to the appropriate positions, the weight was 500 g, the number of abrasions was set to 2000 times, the speed was adjusted to 20 times / min, the switch was pressed, and the test began. After the test was completed, the coating surface wear was observed, and the scratched surface was indicated with "X", and the appearance without change was indicated with "O";

[0084] IV. Heat sealing performance test

[0085] According to QB-T2358-1998 Test Method for Heat Seal Strength of Plastic Film Packaging Bag, the heat sealing surface of the film was heat sealed with kraft paper, the heat sealing temperature was 85°C, the heat sealing pressure was 300 Kpa, the heat sealing time was 1 s, and the heat sealing strength was tested after heat sealing, and the peeling phenomenon was recorded: "O" for kraft paper tearing, and "X" for kraft paper not tearing;

[0086] V. Touch feeling judgment

[0087] Whether there is a delicate silk, skin touch feeling was felt by hand rubbing; "O" was used to indicate the touch feeling, and "X" was used to indicate no touch feeling;

[0088] VI. Adhesion test of touch layer

[0089] Adhesive tape bonding test: a 15-20 cm long and 0.5-1.0 inch wide 3M adhesive tape was attached to the ink layer of the pre-coated film printed with ink and flattened, then the adhesive tape was peeled off at a uniform speed, and the residual rate of the touch layer was observed and estimated.

[0090] The performance test results of the biaxially stretched polyamide films prepared in the above examples and comparative examples are shown in Table 1 below.

[0091] Table 1 Performance test results

[0092]

[0093]

[0094] From the above data, it can be seen that Examples 1-6 have higher haze, lower gloss, and also have more excellent scratch and wear resistance and touch performance than Comparative Example 1; have more excellent heat seal strength than Comparative Example 2; have higher haze, lower gloss, and also have excellent scratch and wear resistance and touch performance, and also have more excellent touch layer adhesion than Comparative Examples 3-10.

[0095] Although the three-layer structure of heat-seal layer, intermediate layer and surface layer in Comparative Example 1 has excellent heat-seal strength and biodegradability, it does not have the characteristics of single-side touch and single-side haze, and the glossiness is also high. In Comparative Example 2, the content of crystalline polylactic acid chips in the heat-seal layer is higher than that of non-crystalline polylactic acid chips, which improves the temperature resistance, but the heat-seal performance is not good at 85°C. In Comparative Example 3, the content of waterborne polyurethane dispersion in the touch layer is reduced, which does not affect the light transmittance, heat-seal performance and touch, but the haze, glossiness, scratch resistance and adhesion of the touch layer are affected. In Comparative Example 4, no touch agent is added, which does not affect the light transmittance, heat-seal strength and adhesion of the coating, but the haze, glossiness, scratch resistance and wear resistance are affected, and the touch performance is also not good. In Comparative Example 5, the content of touch agent in the touch layer is too low, which does not affect the light transmittance, heat-seal strength and adhesion of the touch layer, but the haze, glossiness, scratch resistance and wear resistance are affected, and the touch performance is also not good. In Comparative Example 6, the content of touch agent in the touch layer is too high, which does not affect the scratch resistance, heat-seal strength and touch performance, but the light transmittance, haze and glossiness are affected, and the adhesion of the touch layer is not affected. In Comparative Example 7, no crosslinking agent is added in the touch layer, which does not affect the light transmittance, haze, glossiness, heat-seal strength and touch performance, but the scratch resistance and adhesion of the touch layer are affected, and the temperature resistance of the touch layer itself is also affected. In Comparative Example 8, the content of polymethylsilsesquioxane in the touch agent of the touch layer is too low, which does not affect the light transmittance, heat-seal performance, scratch resistance and wear resistance, and the adhesion of the touch layer, but the haze and glossiness are affected, and the touch performance is also not good. In Comparative Example 9, the content of polydimethylsiloxane in the touch agent of the touch layer is too low, which does not affect the light transmittance and heat-seal strength, but the haze, glossiness, scratch resistance and wear resistance are affected, and the touch performance and adhesion of the touch layer are also affected. In Comparative Example 9, the content of cetyl stearyl polymethylsiloxane in the touch agent of the touch layer is too low, which does not affect the light transmittance, haze, glossiness, heat-seal performance and touch performance, but the scratch resistance of the touch layer is affected, and the adhesion of the touch layer is also low.

[0096] The above embodiments are only used to illustrate the technical solutions of the present application, and are not limited thereto; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A heat-sealable, single-sided tactile, single-sided haze-degradable film, characterized in that, The heat-sealing layer, the intermediate layer, the surface layer and the touch layer are sequentially arranged from the inside to the outside; the heat-sealing layer, the intermediate layer and the surface layer are prepared by three-layer flow casting co-extrusion and bidirectional stretching; the touch layer is obtained by coating adhesive on the surface layer by a textured roll; the heat-sealing layer comprises 67.0-77.5 wt% crystalline polylactic acid chips, 21.9-31.0 wt% non-crystalline polylactic acid chips, 0.50-1.00 wt% opening agent and 0.10-1.00 wt% slip agent; the intermediate layer comprises 100 wt% crystalline polylactic acid chips; the surface layer comprises 91.6-95.0 wt% crystalline polylactic acid chips, 4.4-6.4 wt% non-crystalline polylactic acid chips, 0.50-1.00 wt% opening agent and 0.10-1.00 wt% slip agent; the touch layer is composed of water-based polyurethane dispersion, touch aid, crosslinking agent and water in a mass ratio of (90.0-92.5):(10.0-15.0):(1.00-5.00):(45.5-50.0); the touch aid is composed of polymethylsilsesquioxane, polydimethylsiloxane and cetyl stearyl polymethylsiloxane in a mass ratio of (24.0-30.0):(10.2-15.0):(2.20-3.50).

2. The degradable film of claim 1, wherein, The slip agent is one or more combinations of erucic acid amide, oleic acid amide, silicone oil, silicone, polyethylene wax.

3. The degradable film of claim 1, wherein, The opening agent is one or more combinations of silicon dioxide, talcum powder, zeolite, diatomite, calcium carbonate, clay.

4. The degradable film of claim 1, wherein, The water-based polyurethane dispersion is composed of polyether polyol, polyester polyol and isocyanate in a mass ratio of (20.0-25.5):(35.0-38.2):(10.2-13.5).

5. The biodegradable film as described in claim 4, characterized in that, The polyether polyol is one or more combinations of polyether diol, polyether tetraol, polytetrahydrofuran diol, polyethylene oxide diol; the polyester polyol is one or more combinations of polyepsilon-caprolactone diol, polyethylene glycol-1,4-butanediol adipate diol, poly-1,6-hexanediol carbonate diol; the isocyanate is one or more combinations of hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, 1,4-cyclohexane diisocyanate, diphenylmethane diisocyanate.

6. The degradable film of claim 1, wherein, The crosslinking agent is one or more combinations of polycarbodiimide crosslinking agent and aliphatic polyisocyanate crosslinking agent.

7. The degradable film of claim 1, wherein The thickness of the heat-sealing layer is 2.0-3.0 μm, the thickness of the surface layer is 3.0-4.0 μm, the thickness of the intermediate layer is 8.0-35.0 μm, and the thickness of the touch layer is 1.0-2.0 μm.

8. A process for the production of a degradable film as claimed in any one of claims 1 to 7, characterised in that, The method comprises the following steps: (1) The water-based polyurethane dispersion is prepared according to the mass ratio of the touch layer, then the touch aid is added and stirred uniformly, then water is added for dilution and adjustment, then the crosslinking agent is added and stirred uniformly, and then the touch layer coating is obtained after standing and defoaming. (2) The crystalline polylactic acid chip, non-crystalline polylactic acid chip, opening agent and slip agent are mixed according to the mass ratio of the heat-sealing layer, and then melt-blended, extruded and granulated by a double screw extruder to obtain the master batch for the inner layer; (3) The crystalline polylactic acid chip, non-crystalline polylactic acid chip, opening agent and slip agent are mixed according to the mass ratio of the surface layer, and then melt-blended, extruded and granulated by a double screw extruder to obtain the master batch for the surface layer; (4) The crystalline polylactic acid chip is put into the main machine of the three-layer co-extrusion casting extruder to obtain the middle layer; the master batch obtained in step (2) and step (3) is respectively put into two auxiliary machines to obtain the heat-sealing layer and the surface layer; (5) The raw material mixture of each film layer is melt-extruded by different extruders and converged in the same T-shaped die, and the melt is cooled by a cooling roller to form a casting sheet; (6) The casting sheet obtained in step (5) is first stretched in the longitudinal direction, and then the surface layer is treated by corona; (7) The coating for the touch layer obtained in step (1) is poured into the coating agent glue tank, and then the poly lactic acid film stretched in the longitudinal direction obtained in step (6) is coated with the coating for the upper and lower surface layers by the netted roller coating method; the PLA film is dried and stretched in the transverse direction, shaped, wound and then aged to obtain the heat-sealable single-touch single-fog degradable film.

9. The production method according to claim 8, wherein The melting temperature in step (5) is 180-210℃, the drying temperature in step (7) is 80-120℃, the aging temperature is 45-50℃, and the aging time is 24-48h. ​

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