Low-residue composite film, preparation method and composite sheet

Abstract

The invention provides a low-residue composite film, a preparation method and a composite sheet. The low-residue composite film comprises an anti-wall-hanging film containing at least one polymer; the anti-wall-hanging film comprises a functional layer, a middle layer and a connecting layer which are sequentially arranged, the functional layer comprises, by weight, 68%-94% of polyethylene, 5%-30% of an anti-wall-hanging additive and 1%-2% of an anti-blocking agent, the anti-wall-hanging additive is polyethylene resin added with a hydrophobic agent and / or an oleophobic agent, and the anti-wall-hanging additive is polyethylene resin added with a hydrophobic agent and / or an oleophobic agent. The composite sheet is used for solving the problems that in the prior art, an inner-layer film of a composite sheet is poor in anti-wall-hanging performance, an adopted anti-wall-hanging coating is prone to falling off, secondary recovery is affected, and the environmental protection performance is poor.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and particularly to a low-residue composite film, a preparation method thereof, and a composite sheet. Among them, the low-residue composite film and the composite sheet are particularly suitable for packaging container materials such as cosmetics, food, and medicine. Background Art

[0002] The composite sheets prepared by the multi-layer co-extrusion blow molding process are widely used in the packaging hoses for products such as cosmetics, food, and medicine. By adjusting the different material compositions and ratios of each layer of the composite film, different performance requirements can be met. Taking paste-like contents such as toothpaste, facial cleanser, and hand cream as examples, after the paste-like contents are injected into the packaging hose, due to the surface tension of the inner wall material of the packaging hose and the relative friction with the contents, further, the inner wall of the existing packaging hose usually does not have the function of avoiding residue (anti-wall hanging). Therefore, there is a problem that the contents remain on the inner wall of the hose packaging during the extrusion process of the contents from the packaging hose and cannot be effectively used, and it is not conducive to cleaning the inner wall of the packaging hose and affects its secondary recycling.

[0003] In the prior art, the method of coating an anti-wall hanging coating on the inner wall of the packaging hose is adopted to reduce the residue amount of the contents on the inner wall of the packaging hose. However, the method of attaching the anti-wall hanging coating to the inner wall of the packaging hose first requires a coating attachment process after the composite film is prepared by the multi-layer co-extrusion blow molding process, resulting in an increase in the complexity of the production process. Moreover, the anti-wall hanging coating has problems of poor adhesion and durability, and it will fall off and mix into the contents, affecting normal use. Further, attaching a coating to the inner wall of the packaging hose will also affect its secondary recycling, and there is a problem of insufficient environmental protection.

[0004] In view of this, it is necessary to improve the inner layer film of the composite sheet in the prior art to solve the above problems. It should be noted that the above introduction of the background art is only for the convenience of clearly and completely explaining the technical solutions of the present application and facilitating the understanding of those skilled in the art. It cannot be considered that the above technical solutions are well-known to those skilled in the art just because these solutions are described in the background art part of the present application. Summary of the Invention

[0005] The purpose of the present invention is to disclose a low-residue composite film, a preparation method thereof, and a composite sheet. Among them, the low-residue composite film is used to solve the problems of poor anti-wall hanging performance of the inner layer film of the existing composite sheet, easy falling off of the anti-wall hanging coating, and poor environmental protection caused by affecting secondary recycling.

[0006] To achieve the above purpose, the present invention provides a low-residue composite film, comprising:

[0007] Anti-sticking film containing at least one polymer;

[0008] The anti-sticking film includes a functional layer, an intermediate layer, and a connecting layer arranged in sequence. The functional layer contains 68% - 94% polyethylene, 5% - 30% anti-sticking additives, and 1% - 2% opening agents by weight percentage. The anti-sticking additives are selected as polyethylene resins added with hydrophobic agents and / or oleophobic agents.

[0009] As a further improvement of the present invention, the ratio of the thicknesses of the functional layer, the intermediate layer, and the connecting layer in the anti-sticking layer is 1:2:1;

[0010] The functional layer contains 68% polyethylene, 30% anti-sticking additives, and 2% opening agents by weight percentage;

[0011] 68% polyethylene by weight percentage includes 50% linear low-density polyethylene and 18% high-density polyethylene.

[0012] As a further improvement of the present invention, the oleophobic agent is selected as polytetrafluoroethylene or other fluorine-based compounds, the hydrophobic agent is selected as polydimethylsiloxane or other silicone compounds, and the opening agent is selected as nano-silica, talcum powder or other inorganic opening agents, erucic acid amide or other organic opening agents.

[0013] As a further improvement of the present invention, the intermediate layer contains 80% linear low-density polyethylene and 20% high-density polyethylene by weight percentage.

[0014] As a further improvement of the present invention, the intermediate layer contains 80% linear low-density polyethylene and 20% high-density polyethylene by weight percentage.

[0015] Based on the same inventive concept, the present invention also discloses a method for preparing a low-residue composite film, including:

[0016] Step 1: Dry the production materials of the anti-sticking film;

[0017] Step 2: Reactively extrude the dried polyethylene material, anti-sticking additive material, and opening agent material in a ratio of 68%, 30%, and 2% through a twin-screw extruder to prepare a functional layer masterbatch;

[0018] Step 3: Prepare a connecting layer, an intermediate layer, and a functional layer with a thickness ratio of 1:2:1 through a single-screw extruder A, a single-screw extruder B, and a single-screw extruder C in cooperation with a three-layer co-extrusion die head, and blow-mold the connecting layer, the intermediate layer, and the functional layer to form the anti-sticking film;

[0019] Step 4: Traction-reel and post-treat the anti-sticking film.

[0020] As a further improvement of the present invention, the temperature range for reactive extrusion of the dried polyethylene material, anti-wall-hanging additive material, and opening agent material is 190 - 210 °C.

[0021] As a further improvement of the present invention, the four temperature zones of the single-screw extruder C are set to 195 °C, 205 °C, 215 °C, and 210 °C. The screw rotation speed range of the single-screw extruder is 50 - 70 rpm, and the melt pressure of the single-screw extruder C is set to 12 - 18 MPa.

[0022] As a further improvement of the present invention, 0.5 - 1 wt% maleic anhydride grafted PE is used as an interfacial compatibilizer between the connection layer, the intermediate layer, and the functional layer.

[0023] The present invention also discloses a composite sheet, comprising: an anti-wall-hanging film as described in any one of the foregoing;

[0024] a support layer, and a barrier layer formed between the support layer and the anti-wall-hanging film;

[0025] The connection layer of the anti-wall-hanging film adheres to the side of the barrier layer away from the support layer.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows: Through the anti-wall-hanging film composed of a connection layer, an intermediate layer, and a functional layer, the functional layer is formed by a special component ratio, so as to effectively avoid the problem of a large amount of the content hanging on the wall of the packaging hose made of it as an inner wall without applying an anti-wall-hanging coating. Specifically, the functional layer contains 68% - 94% polyethylene, 5% - 30% anti-wall-hanging functional layer, 1% - 2% functional layer, and 1% - 2% opening agent by weight percentage. The anti-wall-hanging additive is selected as a polyethylene resin added with a water repellent and / or an oil repellent. Further, the water repellent is selected as fluorine-based compounds such as polytetrafluoroethylene, the oil repellent is selected as silicon-based compounds such as polydimethylsiloxane, and the opening agent is selected as organic opening agents such as nano-silica. Through the above design, the fluorine-based compound as a water repellent and the nano-silica opening agent can form a micro-nano composite structure to achieve the effect of combining physical roughening and chemical oil repellent performance, thereby effectively improving the anti-wall-hanging performance of the anti-wall-hanging film; when using silicon-based compounds as water repellents and calcium stearate opening agents to achieve the dual effects of lubrication and nucleation, the anti-residual wall-hanging performance of the functional layer is further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the layer combination structure of the anti-wall-hanging film in the present invention;

[0028] Figure 2This is the process flow chart for reflecting the preparation method of the low-residue composite film in the present invention;

[0029] Figure 3 This is the schematic structural diagram of the composite sheet laminate in the present invention. Detailed implementation manners

[0030] The present invention will be described in detail below with reference to the embodiments shown in the drawings. However, it should be noted that these embodiments do not limit the present invention, and any equivalent transformation or substitution in terms of function, method, or structure made by those of ordinary skill in the art according to these embodiments shall fall within the protection scope of the present invention.

[0031] Refer Figure 1 As shown, a specific implementation manner of a low-residue composite film designed by the present invention is provided. Compared with the prior art, it has an anti-wall-hanging film 10 composed of a connecting layer 1, an intermediate layer 2, and a functional layer 3. The functional layer 3 is formed by a special component ratio, so as to effectively avoid the problem of a large amount of residue of the content hanging on the wall of the packaging hose made of it as the inner wall without applying an anti-wall-hanging coating.

[0032] Refer Figure 1 As shown, the purpose of the present invention in this embodiment is to disclose a low-residue composite film, which includes an anti-wall-hanging film 10 containing at least one polymer; the anti-wall-hanging film 10 includes a functional layer 3, an intermediate layer 2, and a connecting layer 1 arranged in sequence. The functional layer 3 contains 68% - 94% polyethylene, 5% - 30% anti-wall-hanging additive, and 1% - 2% opening agent by weight percentage. The anti-wall-hanging additive is selected as a polyethylene resin added with a hydrophobic agent and / or an oleophobic agent; the ratio of the thicknesses of the functional layer, the intermediate layer, and the connecting layer in the anti-wall-hanging layer is 1:2:1. Specifically, the functional layer 3 contains 68% polyethylene, 30% anti-wall-hanging additive, and 2% opening agent by weight percentage, and 68% polyethylene by weight percentage includes 50% linear low-density polyethylene (LLDPE) and 18% high-density polyethylene (HDPE). The oleophobic agent is selected as polytetrafluoroethylene or other fluorine-based compounds, the hydrophobic agent is selected as polydimethylsiloxane or other silicone compounds, and the opening agent is selected as nano-silica, talc powder or other inorganic opening agents, erucic acid amide or other organic opening agents.

[0033] It should be noted that in this embodiment, the mixing ratios of the groups of the functional layer 3 can be flexibly adjusted within the above range according to the fluidity of the content. Further, the specific components of the anti-wall-hanging additive can also be flexibly adjusted according to the properties of the content, that is, a water repellent or an oil repellent is added according to the water-oil ratio of the content, and in certain cases, a water repellent and an oil repellent can also be added simultaneously. Specifically, in this embodiment, according to the above description, when the polyethylene substrate is 68% by weight, the addition amounts of the anti-wall-hanging additive and the antiblocking agent are 30% and 2% respectively. Further, the 68% polyethylene substrate specifically includes 50% linear low density polyethylene (LLDPE) and 18% high density polyethylene (HDPE). When the anti-wall-hanging additive is a polyethylene resin added with a water repellent, the water repellent is selected as a silicone compound such as polydimethylsiloxane, and the silicone compound has good hydrophobicity and wear resistance. When the anti-wall-hanging additive is a polyethylene resin added with an oil repellent, the oil repellent is selected as a fluorine-based compound such as polytetrafluoroethylene. The special arrangement of fluorine atoms in the molecule of the fluorine-based compound forms a bottom interface free energy surface, which can significantly reduce the adhesion of oily substances, thereby achieving an oil repellent effect.

[0034] In addition, for the antiblocking agent, it should be noted that the main functions of the antiblocking agent include preventing plastic products from sticking, improving production efficiency, improving the use performance of products and extending the service life of products. In this embodiment, the antiblocking agent can be selected as nano-silica, which has the effect of forming a micro-protrusion structure on the surface to reduce the adsorption force of the film; inorganic antiblocking agents such as talc or diatomaceous earth; erucic acid amide and oleic acid amide, which have the effect of forming a lubricating layer by migrating to the film surface to reduce the friction coefficient. Specifically, the static and dynamic friction coefficients can be reduced to 0.2-0.4; calcium stearate, which has both a nucleating agent and an antiblocking function, can effectively improve the transparency and processing stability of the film. Further, in this embodiment, the antiblocking agent can be selected as an organic antiblocking agent not exemplified above.

[0035] Specifically, when the anti-wall-hanging additive is a polyethylene resin added with a fluorine-based compound as an oil repellent, the antiblocking agent is selected as silica to achieve the functional coordination effect of the micro-nano composite structure, so that the functional layer 3 has a dual mechanism of physical roughening and chemical oil repellency, thereby effectively improving the anti-wall-hanging effect of the functional layer. When the anti-wall-hanging additive is a polyethylene resin added with a silicon-based compound as a water repellent, the antiblocking agent can be selected as calcium stearate to improve the lubricity of the functional layer 3 and have a nucleating effect. In addition, when the water repellent and the oil repellent are added to the polyethylene resin simultaneously in the above description, they can be adjusted within the range of 30% according to actual needs, and then the corresponding antiblocking agent is selected and the addition ratio is adjusted within the range of 2%. The specific ratio is not elaborated here.

[0036] Further, in this embodiment, both the intermediate layer 2 and the connecting layer 1 of the anti-wall-hanging film 10 contain 80% linear low-density polyethylene (LLDPE) and 20% high-density polyethylene (HDPE) by weight percentage. And as described above, in this embodiment, the thickness ratio of the functional layer 3, the intermediate layer 2, and the connecting layer 1 is 1:2:1, that is, the thickness percentages of the functional layer 3, the intermediate layer 2, and the connecting layer 1 in the anti-wall-hanging film 10 are 25%, 50%, and 25%, respectively. Among them, linear low-density polyethylene has a lower density, better tear resistance and puncture resistance, and has better flexibility and processability, while high-density polyethylene has a higher density, hardness and stiffness, and also has good wear resistance and chemical resistance. Both the connecting layer 1 and the intermediate layer 2 adopt 80% linear low-density polyethylene and 20% high-density polyethylene by weight percentage, so that the connecting layer 1 and the intermediate layer 2 have the advantages of both high-density polyethylene and linear low-density polyethylene, and cooperate with the functional layer 3 to make the anti-wall-hanging film 10 have the characteristics of anti-wall-hanging, wear resistance, tear resistance, flexibility, and chemical resistance, and is suitable for packaging contents mainly composed of paste-like daily chemicals and drugs. In addition, it is also suitable for solid food packaging.

[0037] It should be noted that for the anti-wall-hanging film 10 prepared by the formula in the above embodiment, the water or oil contact angle formed on its surface (i.e., the surface of the functional layer 3) is greater than or equal to 110°. It should be noted that the contact angle is also called the wetting angle. It refers to the angle between the solid-liquid interface, through the liquid interior, to the gas-liquid interface at the three-phase junction of solid, liquid, and gas. When the contact angle is 180°, the liquid is completely non-wetting. At this time, the liquid droplet formed by water or oil on the solid plane is spherical, which can be called a completely non-wall-hanging state in this embodiment; when the contact angle is 0°, the liquid is completely wetting. At this time, the liquid droplet formed by water or oil on the solid plane spreads along the plane and extends infinitely, which can be called a completely wall-hanging state in this embodiment. In this embodiment, a contact angle greater than or equal to 110° is formed between the functional layer and water or oil, thereby achieving a good effect of preventing wall-hanging when containing the content.

[0038] For example, 10 ml of glycerol is respectively poured on the surfaces of the anti-wall-hanging film 10 and the ordinary film disclosed in this embodiment, and then the anti-wall-hanging film 10 and the ordinary film are respectively erected vertically. In the same time, the glycerol on the surface of the anti-wall-hanging film 10 flows faster and has better fluidity. Specifically, the liquid flow performance of the anti-wall-hanging film 10 is improved by 50% compared with that of the ordinary film. As shown in Table 1 below, the data measured by a contact angle tester for the anti-wall-hanging film 10 with an anti-wall-hanging additive content of 30% are shown.

[0039]

[0040] Table 1

[0041] As can be seen from the above, when the addition amount of the anti-wall-hanging additive is 30%, a contact angle with an average value of 121.789° is formed on the surface of the anti-wall-hanging film 10, and when oil or water contacts the surface of the anti-wall-hanging film 10, a droplet close to a spherical shape is formed, thus achieving an excellent anti-wall-hanging effect. Further, the specific components of the anti-wall-hanging additive are as described above and will not be elaborated here. It has the advantages of strong bonding force with the polyethylene substrate and wear resistance, so that the service life of the packaging hose made of it can be extended, and it also has the advantages of flexibility and tear resistance, and can be applied to the production of any-shaped packaging without complicated treatment.

[0042] Based on the same inventive concept, referring to Figures 1 to 2 As shown, the present invention also discloses a method for preparing a low-residue composite film, including steps S1 to S4:

[0043] Step S1: Dry the production materials of the anti-wall-hanging film 10.

[0044] Step S2: Reactively extrude the dried polyethylene material, anti-wall-hanging additive material, and opening agent material through a twin-screw extruder in a ratio of 68%, 30%, and 2% to prepare the masterbatch of the functional layer 3.

[0045] Step S3: Use a single-screw extruder A, a single-screw extruder B, and a single-screw extruder C in cooperation with a three-layer coextrusion die head to prepare the connecting layer 1, the intermediate layer 2, and the functional layer 3 with a thickness ratio of 1:2:1, and blow-mold the connecting layer 1, the intermediate layer 2, and the functional layer 3 to form the anti-wall-hanging film 10.

[0046] Step S4: Traction-reel and post-treat the anti-wall-hanging film 10.

[0047] As can be seen from the foregoing embodiments, the specific composition of the functional layer 3 is 68% polyethylene substrate, 30% anti-wall-hanging opening additive, and 2% opening agent by weight percentage. Moreover, the 68% polyethylene substrate includes 50% linear low-density polyethylene and 18% high-density polyethylene, and the compositions of the connecting layer 1 and the intermediate layer 2 are 80% linear low-density polyethylene and 20% high-density polyethylene. Therefore, the production materials of the anti-wall-hanging film 10 in step S1 are specifically: linear low-density polyethylene resin, high-density polyethylene resin, fluorine-based modified polyethylene masterbatch or silicone-modified polyethylene masterbatch (i.e., the production materials of the anti-wall-hanging additive), and inorganic opening agents such as nano-silica.

[0048] Further, when performing step S1, the linear low-density polyethylene resin and the high-density polyethylene resin are dried in a hot air circulation at 60°C for four hours until the moisture content ≤ 0.03%. The fluorine-modified polyethylene masterbatch or the silicone-modified polyethylene masterbatch is dried in a hot air vacuum at 50°C for two hours. The inorganic antiblocking agent is dried in hot air at 80°C for 1 hour.

[0049] Then, step S2 is carried out. The dried linear low-density polyethylene resin, high-density polyethylene resin, fluorine-modified polyethylene masterbatch or silicone-modified polyethylene masterbatch, and inorganic antiblocking agent are added to a twin-screw extruder in the proportions of 50%, 18%, 30%, and 2% respectively for reactive extrusion to prepare the masterbatch of the functional layer 3. Specifically, the reactive extrusion temperature range of the twin-screw extruder is 190-210°C. Further, in this embodiment, the twin-screw extruder can also be called a twin-screw extrusion granulator. By using the twin-screw extruder, a masterbatch of the high-concentration functional layer 3 is manufactured, and molecular-level dispersion is achieved. It should be noted that in this embodiment, the twin-screw extruder is provided with a high-shear section, and the screw combination is selected as a 2×60° + 3×30° staggered angle.

[0050] Further, the parameter configurations of the single-screw extruder A, single-screw extruder B, and single-screw extruder C in step S3 are set as shown in Table 2 below:

[0051]

[0052]

[0053] Table 2

[0054] Specifically, temperature zones 1 to 4 are the feeding zone, heating zone, melting zone, and die head respectively. And in combination with the foregoing, since the connecting layer 1 and the intermediate layer 2 have the same composition, the single-screw extruder A and the single-screw extruder B perform the extrusion processing of the intermediate layer 2 and the connecting layer 1 at the same zone temperature, the same screw speed, and the same melt pressure. The four temperature zones of the single-screw extruder C are set at 195°C, 205°C, 215°C, and 210°C. The screw speed range of the single-screw extruder is 50-70 rpm, and the melt pressure of the single-screw extruder C is set at 12-18 MPa to process the functional layer 3 with a composition different from that of the intermediate layer 2 and the connecting layer 1.

[0055] Further, the three-layer coextrusion die head is selected as a spiral coextrusion die head, and the die lip gap is 0.8-1.2 mm. During the blow molding process of the anti-blocking film 10 in step S3, the blow-up ratio (BUR) is 2.5-3.0.

[0056] In step S4, the traction and winding speed of the anti-wall-hanging film 10 is 8 - 12 m / min. During the traction and winding process, the anti-wall-hanging film 10 is cooled by a double-air outlet air ring with an air temperature of 15°C - 20°C in combination with an IBC internal cooling film blowing machine. During the post-treatment process of step S4, the surface of the anti-wall-hanging film 10 can be selectively corona-treated to improve its outer layer printing adaptability. Specifically, during the surface corona treatment process, the power is 5 - 8 kW and the treatment strength is ≥ 38 dyn / cm. The post-treatment process of the anti-wall-hanging film 10 also includes aging treatment. Specifically, the anti-wall-hanging film 10 is stored at a constant temperature of 40°C for 24 hours to promote the migration of the opening agent to the surface of the functional layer 3 of the anti-wall-hanging film 10. When the surface corona treatment is not required, the anti-wall-hanging film 10 after winding and cooling is directly subjected to aging treatment.

[0057] It should be noted that, in combination Figure 1 as shown in this embodiment, 0.5 - 1 wt% maleic anhydride grafted PE is used as an interfacial compatibilizer between the connecting layer 1, the intermediate layer 2, and the functional layer 3, and the melt index (MI) difference between the fluorine-based compound or siloxane compound and the polyethylene substrate is ≤ 0.5 g / 10 min (190°C / 2.16 kg). Further, the addition amount of the opening agent in step S2 also needs to be dynamically adjusted within the range of 1% - 2% according to other factors. For example, the addition amount of the opening agent in summer is 1.5% - 2.0%, and the addition amount of the opening agent in winter is 1.0% - 1.5%. Moreover, the surface friction coefficient of the anti-wall-hanging film 10 (more specifically, the surface of the functional layer 3) after blow molding is ≤ 0.35 (ASTM D1894, a standard test method for measuring the static and dynamic friction coefficients of plastic films and sheets).

[0058] In the above method for preparing a low-residue composite film disclosed in this embodiment, the anti-wall-hanging film 10 is formed into a gradient layer structure of the connecting layer 1, the intermediate layer 2, and the functional layer 3, and the masterbatch of the functional layer 3 is prepared to achieve the effect of molecular-level dispersion and dynamically adjust the formula of each component of the functional layer 3, so as to balance the anti-wall-hanging performance and processing efficiency of the anti-wall-hanging film 10, thus being applicable to the hose packaging in the fields of cosmetics, food, etc.

[0059] Refer Figure 3 as shown, the present invention also discloses a composite sheet, including: the anti-wall-hanging film 10 as described in the foregoing embodiment; a support layer 30, and a barrier layer 20 formed between the support layer 30 and the anti-wall-hanging layer 10; the connecting layer 1 of the anti-wall-hanging film 10 (in combination Figure 1 as shown) is attached to the side of the barrier layer 20 away from the support layer 30.

[0060] It should be noted that in this embodiment, the support layer 30 is selected as a conventional polyethylene resin laminate, and the barrier layer 20 is selected as a laminate with barrier properties, such as aluminum foil, aluminized cast polypropylene film, EVOH (ethylene-vinyl alcohol copolymer), etc., which are used to block the water vapor outside the package to prevent the contents from spoiling. The connecting layer 1 of the anti-wall-hanging film 10 is attached to the side of the barrier layer 20 away from the support layer 30 and is used to contact the contents, so as to effectively reduce the amount of the contents attached to the inner wall of the package. The specific composition of the anti-wall-hanging film 10 is as described in the foregoing embodiment and will not be elaborated here.

[0061] The series of detailed descriptions listed above are only specific descriptions of the feasible embodiments of the present invention, and they are not intended to limit the protection scope of the present invention. Any equivalent embodiments or changes made without departing from the technical spirit of the present invention should be included in the protection scope of the present invention.

[0062] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-mentioned exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be construed as limiting the claims involved.

[0063] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A low-residue composite film, characterized in that, Comprising: An anti-sticking film containing at least one polymer; The anti-sticking film includes a functional layer, an intermediate layer, and a connecting layer arranged in sequence. The functional layer contains 68% - 94% polyethylene, 5% - 30% anti-sticking additives, and 1% - 2% opening agents by weight percentage. The anti-sticking additives are selected as polyethylene resins added with hydrophobic agents and / or oleophobic agents.

2. The low-residue composite film according to claim 1, wherein The ratio of the thicknesses of the functional layer, the intermediate layer, and the connecting layer in the anti-sticking layer is 1:2:1; The functional layer contains 68% polyethylene, 30% anti-sticking additives, and 2% opening agents by weight percentage; 68% polyethylene by weight percentage includes 50% linear low-density polyethylene and 18% high-density polyethylene.

3. The low-residue composite film according to claim 2, wherein The oleophobic agent is selected as polytetrafluoroethylene or other fluorine-based compounds, the hydrophobic agent is selected as polydimethylsiloxane or other silicone compounds, and the opening agent is selected as nano-silica, talcum powder or other inorganic opening agents, erucic acid amide or other organic opening agents.

4. The low-residue composite film according to claim 1, wherein The connecting layer contains 80% linear low-density polyethylene and 20% high-density polyethylene by weight percentage.

5. The low-residue composite film according to claim 1, characterized in that, The intermediate layer contains 80% linear low-density polyethylene and 20% high-density polyethylene by weight percentage.

6. A preparation method of a low-residue composite film, characterized in that, Comprising: Step 1: Dry the production materials of the anti-sticking film; Step 2: Reactively extrude the dried polyethylene material, anti-sticking additive material, and opening agent material through a twin-screw extruder at a ratio of 68%, 30%, and 2% to prepare a functional layer masterbatch; Step 3: Use single-screw extruder A, single-screw extruder B, and single-screw extruder C in cooperation with a three-layer co-extrusion die head to prepare a connecting layer, an intermediate layer, and a functional layer with a thickness ratio of 1:2:1, and blow-mold the connecting layer, the intermediate layer, and the functional layer to form the anti-sticking film; Step 4: Carry out traction winding and post-treatment on the anti-sticking film.

7. The method for preparing a low-residue composite film according to claim 6, characterized in that, The temperature range for the reactive extrusion of the dried polyethylene material, anti-sticking additive material, and opening agent material is 190 - 210 °C.

8. The preparation method of the low-residue composite film according to claim 6, characterized in that, The four temperature zones of the single-screw extruder C are set at 195 °C, 205 °C, 215 °C, and 210 °C. The screw rotation speed range of the single-screw extruder is 50 - 70 rpm, and the melt pressure of the single-screw extruder C is set at 12 - 18 MPa.

9. The method for preparing a low-residue composite film according to claim 6, wherein A 0.5 - 1 wt% maleic anhydride grafted PE is used as an interfacial compatibilizer between the connecting layer, the intermediate layer, and the functional layer.

10. A composite sheet, characterized in that, Comprising: The anti-sticking film according to claims 1 to 5; A support layer, and a barrier layer formed between the support layer and the anti-sticking film; The connecting layer of the anti-sticking film adheres to the side of the barrier layer away from the support layer.

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