A high molecular protective film, a preparation method and application thereof

Abstract

The application relates to a high-molecular protective film, a preparation method and application thereof. The PE film material is a temporary packaging or covering material commonly used in outdoor construction, which is cost-effective but has the defects of easy wrinkles, breakage and dust adsorption. In view of the defects in the prior art, the application provides a high-molecular protective film material which comprises an integrally-formed adhesive layer and a protective layer; the raw material ratio of the adhesive layer is as follows: 150-170 parts of low-density polyethylene, 75-86 parts of starch, 8-11.2 parts of chitosan and 2-6 parts of a crosslinking agent; the raw material of the protective layer is 240-260 parts of low-density polyethylene, and a sunscreen or light stabilizer can be further added. The inner and outer layers of the high-molecular protective film have different characteristics, the inner layer introduces biodegradable materials such as starch and chitosan based on the low-density polyethylene, and has good wrinkle resistance, dust prevention, sunscreen and degradable characteristics, and is especially suitable for being used as a temporary packaging material in outdoor construction.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of packaging materials, in particular to a high-molecular protective film, a preparation method and application thereof. BACKGROUND

[0002] The information disclosed in this Background section is only for the purpose of increasing the understanding of the background of the present application and should not be taken as an acknowledgement or any form of suggestion that this information forms prior art that is already widely known in a field of endeavor.

[0003] In the field of road construction, building materials are usually stacked under outdoor conditions, and need to be packaged or covered when exposed to sunlight or rain. In order to reduce costs, the main packaging material used in construction sites at present is PE film, which is cost-effective and has various models to choose from. However, PE film is also prone to dust adsorption and has poor self-adhesion, and additional adhesives are needed to help secure it.

[0004] In addition, films are also needed as covering materials during construction. For example, in current road construction, after the base layer of the road is completed, the kerb stones are laid first, and then the asphalt is laid. Therefore, when laying asphalt, adhesive tape and plastic film are needed to cover and protect the kerb stones to prevent asphalt from sticking. For example, patent CN212426611U provides a kind of anti-sticking covering material for kerb stones, which fixes the plastic film on the surface of the kerb stone through a fixing piece, and then tears off the plastic film after the asphalt is laid, while the part under the asphalt can only be slowly degraded by microorganisms. PE film has poor degradability, and PE film left in the construction site is often difficult to degrade on its own. SUMMARY

[0005] In view of the above situation, the inventors believe that it is of great significance to provide a packaging material with self-adhesion and degradability for the outdoor protection of building materials and road construction. In order to meet the needs of easy degradation and wrinkle resistance of the packaging material, the present application provides a high-molecular protective film material with different properties in the inner and outer layers. The inner layer in contact with the building materials should have a certain adhesion, be able to self-adhere, and be able to adhere firmly to the building materials. The outer layer has a certain smoothness and sun protection performance, which can cope with the construction environment of sun and rain, reduce the adsorption of dust, and has a certain wrinkle resistance, which is expected to be reused.

[0006] In order to achieve the above technical effects, the present application provides the following technical solutions:

[0007] In the first aspect, the application provides a high polymer protective film, which comprises an integrally formed adhesive layer and a protective layer; the adhesive layer is prepared from the following raw materials: 150-170 parts of low density polyethylene, 75-86 parts of starch, 8-11.2 parts of chitosan, and 2-6 parts of crosslinking agent; and the protective layer is prepared from the following raw materials: at least 240-260 parts of low density polyethylene.

[0008] The adhesive layer of the protective film contains biodegradable materials such as starch and chitosan, which have the following advantages: first, the adhesive layer has certain adsorption and water absorption, and has certain adhesion to the surface of building materials (such as stone), so that it can effectively reduce the construction cost without additional coating; second, in the asphalt paving construction, the protective film can be used for covering and protecting the curbstone, and the buried part can be gradually degraded under the action of microorganisms, thereby reducing the adverse effects on the environment.

[0009] The surface of the protective layer is relatively smooth, and is not easy to adhere to asphalt or dust, and is not easy to wrinkle.

[0010] In some preferred embodiments, in order to improve the sun protection performance of the protective film, a suitable amount of sunscreen agent such as magnesium oxide, zinc oxide or titanium dioxide can be added to the protective layer. The sunscreen agent of the above-mentioned inorganic salt type can not only improve the sun protection effect of the protective film, but also appropriately improve the hardness of the protective film and increase the anti-wrinkle performance. In a feasible embodiment, the raw material ratio of the protective layer is as follows: 240-260 parts of low density polyethylene, 4-6 parts of magnesium oxide, zinc oxide or titanium dioxide.

[0011] In some other preferred embodiments, an anti-aging agent or a light stabilizer can be added to the protective layer to improve the sun protection effect and durability of the protective film. In a feasible embodiment, the raw material ratio of the protective layer is as follows: 240-260 parts of low density polyethylene, 0.1-2 parts of light stabilizer, and the light stabilizer is selected from any one of light shielding agent, ultraviolet light absorber, quenching agent and hindered amine light stabilizer.

[0012] In some specific embodiments of the protective film of the first aspect:

[0013] The density of the low density polyethylene is in the range of 0.918-0.935 g / cm3.

[0014] The starch is selected from one or a mixture of several of corn starch, barley starch, oat starch, buckwheat starch, potato starch, cassava starch and sweet potato starch; modified starch such as microorganism fermentation modified starch or oxidized denatured starch can also be used.

[0015] The crosslinking agent is selected from one or a combination of N,N'-methylenebisacrylamide (MBA) and dicumyl peroxide (DCP).

[0016] The thickness of the protective film is 25-50 μm, and more preferably 30-40 μm. In the thickness range, the protective film can be extruded and stretch-formed at one time, and the effect of covering the curbstone is best.

[0017] In the second aspect of the present application, a preparation method of the high-molecular protective film is provided, and the preparation method comprises the following steps: grinding and mixing the raw material components for preparing the adhesive layer to obtain premix A, mixing the raw material components for preparing the protective layer to obtain premix B, and extruding the premixes A and B through a single screw after melting, and forming after drawing.

[0018] The present application aims to provide a packaging and protective material in road construction. The packaging material is a consumable, and therefore, cost is the primary factor to be considered in the design and development of the protective film. Polyethylene is a cost-effective and widely available film material. However, the preparation of a one-piece, double-sided polyethylene film product with different properties is still a blank in current research. The present application uses a multi-layer co-extrusion technology to achieve different properties on both sides of the protective film. The interlayer adhesion of the co-extruded composite film is usually poor, and separation and damage often occur at the interface. The present application adds biomass materials such as starch and chitosan to the adhesive layer, which can improve the adsorption and degradation of the adhesive layer. The molten material of the composite adhesive layer and the molten material of the protective layer still have good compatibility, and good interfacial compatibility can be achieved by extrusion and stretching.

[0019] In the preparation method, the premix A is prepared as follows: the starch and chitosan are mixed and then high-speed ground, and then the low-density polyethylene and the crosslinking agent are added and ground at 100-140°C; and the premix B is prepared as follows: the low-density polyethylene is high-speed ground at 100-140°C. The high-speed grinding can be achieved by high-speed shearing grinding or ball milling, and the preferred method is ball milling.

[0020] In a specific embodiment, the premix A is prepared as follows: the starch and chitosan are mixed and then added to a planetary ball mill, ground for 25-35 min, the revolution speed is 40-60 rpm, and the rotation speed is 90-110 rpm; the low-density polyethylene and MBA are added and ground for 100-140 min, the grinding temperature is 110-130°C, at this time, the revolution speed is 90-110 rpm, and the rotation speed is 180-220 rpm.

[0021] In a specific embodiment, the premix B is prepared as follows: the low-density polyethylene is added to a planetary ball mill, the revolution speed is 90-110 rpm, the rotation speed is 180-220 rpm, high-speed ground at 100-140°C, and the grinding time is 110-130 min.

[0022] The premix A or B is heated at a constant speed during the melting process, the initial melting temperature is 150 DEG C, the temperature during extrusion is 200 DEG C, and the drawing temperature is not lower than 60 DEG C.

[0023] In a third aspect, the application provides the application of the high polymer protective film in outdoor packaging.

[0024] In a fourth aspect, the application provides the application of the high polymer protective film in road construction, and more preferably, the application of the protective film in covering and protecting the curbstone in the construction of asphalt pavement.

[0025] In the construction of asphalt road, the protective film is covered on the surface of the curbstone before paving the asphalt, the adhesive layer contacts the curbstone, and before covering, only the dust on the surface of the curbstone needs to be removed, and the protective film can be adhered to the surface of the curbstone by the self-adhesion, or the curbstone is wetted, the protective film can better play the adhesion after absorbing water, and the construction personnel can install the fixing member according to the situation. After covering, the asphalt can be paved, and after the asphalt layer is paved, the exposed protective film is torn off.

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

[0027] 1. The application provides a high polymer protective film material with different characteristics on the inner side and the outer side, the adhesive layer of the protective film material has a certain viscosity, has good self-adhesion, can be directly adhered to the surface of the stone, the adhesion increases when water is encountered, the surface of the protective layer is smoother, is not easy to stick dust, and has good wrinkle prevention and sun protection effects. The high polymer protective film can be used as a packaging material in the construction site, and can be packaged without adhesive tape and adhesive, and only needs to be wound in multiple layers.

[0028] 2. In addition, the biodegradable component is introduced into the film material, so that the film material can be naturally degraded under the soil burial condition. The above characteristics determine that the protective film is especially suitable for being used as a covering and protecting material for the curbstone in the road paving process, and the part remaining under the asphalt can be self-degraded, reducing the harm to the environment.

[0029] 3. Multilayer co-extrusion is a common method for preparing composite films in the field, however, due to the difference in crystallization speed between different film materials, under the action of external force, the composite film is easy to be broken at the interface by absorbing energy, and has poor tear resistance. The application realizes the close combination of the inner and outer film materials by optimizing the raw material formula and the preparation process, and the protective film has good tensile strength and puncture resistance, which fills the technical gap for the development of composite films. BRIEF DESCRIPTION OF DRAWINGS

[0030] The accompanying drawings, which form a part of this specification, are included to provide a further understanding of the application and are incorporated herein by reference. The illustrations are of exemplary embodiments of the application and explain the principles of the application, but do not limit the application.

[0031] Figure 1 Schematic diagram of the protective film covering the curbstone in the asphalt paving process of Example 6;

[0032] Wherein, 1 is the protective film, 2 is the curbstone, 3 is the asphalt pavement, 4 is the interface, and 5 is the pavement base. DETAILED DESCRIPTION

[0033] It should be noted that the following detailed description is illustrative only, and is intended to provide further description of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0034] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0035] As introduced in the background section, in order to provide a covering material more suitable for asphalt pavement paving, the present application proposes a high molecular protective film and a preparation method thereof. In order to enable those skilled in the art to have a clearer understanding of the technical solutions of the present application, the technical solutions of the present application will be described in detail below in combination with specific examples and comparative examples.

[0036] The reagent types used in the following examples are as follows:

[0037] Low density polyethylene: LDPE, grade Q210, melt index 2.1 g / 10min.

[0038] Starch: corn starch.

[0039] Modified starch: corn starch is modified by sodium periodate, and the mass ratio of sodium periodate to corn starch is 1:3.

[0040] Chitosan: degree of deacetylation ≥95%, viscosity 100-200 mpa.s.

[0041] Cellulose: colloid, microcrystalline, containing 10.0-20.0% carboxymethyl cellulose sodium as stabilizer.

[0042] Example 1

[0043] In this embodiment, a high polymer protective film is provided, comprising an adhesive layer and a protective layer. The raw material ratio of the adhesive layer is as follows: low density polyethylene 160 parts, starch 80 parts, chitosan 9 parts, N,N'-methylene bisacrylamide (MBA) 2 parts.

[0044] The raw material ratio of the protective layer is as follows: low density polyethylene 260 parts.

[0045] The preparation method of the above high polymer protective film is as follows:

[0046] (1) The above preparation raw materials for preparing the adhesive layer are washed with anhydrous ethanol respectively, and are put into a drying box for 10 h at 80℃ to fully dry them. The starch and chitosan in the above parts are fully mixed and ball milled at a revolution speed of 50 rpm and a rotation speed of 100 rpm. After 30 min of ball milling, the low density polyethylene and MBA are added and continue to be ball milled for 120 min. At this time, the grinding temperature is 120℃, the revolution speed is 100 rpm, and the rotation speed is 200 rpm. Pre-mixed material A is obtained.

[0047] (2) The low density polyethylene used for preparing the protective layer is ball milled at a grinding temperature of 120℃, a revolution speed of 100 rpm, and a rotation speed of 200 rpm for 120 min to obtain pre-mixed material B.

[0048] (3) The above pre-mixed material A and pre-mixed material B are added into two single screw extruders of a co-extrusion flow casting composite molding machine. The melting starting temperature of pre-mixed material A is 150℃, and the temperature of each temperature zone during the feeding to discharging process is set to 170℃, 190℃, and 200℃, respectively. The feeding temperature of pre-mixed material B is 150℃, and the temperature of each temperature zone is 165℃, 180℃, and 200℃, respectively. After being fully melted, they are extruded through a single layer die with a die temperature of 200℃.

[0049] (4) The film material after extrusion through the die is stretched on a casting roller, and the casting area temperature is 65℃. The thickness of the stretched film is controlled to be 35-40 μm.

[0050] The adhesive layer has a peel strength of 45.5 N / cm, and the protective layer has a peel strength of 19.1 N / cm, which are tested according to the national standard GB / T2790.

[0051] Example 2

[0052] In this embodiment, another high polymer protective film is provided, comprising an adhesive layer and a protective layer. The raw material ratio of the adhesive layer is as follows: low density polyethylene 150 parts, starch 86 parts, chitosan 11.2 parts, N,N'-methylene bisacrylamide (MBA) 2.8 parts.

[0053] The raw material ratio of the protective layer is as follows: low density polyethylene 245 parts.

[0054] The preparation method of the above high polymer protective film is as follows:

[0055] (1) The above preparation raw materials for preparing the adhesive layer are respectively cleaned with anhydrous ethanol, and are placed in a drying box for 10.5 h at 85°C for full drying; the starch and chitosan in the above proportions are fully mixed and ball milled, with a revolution speed of 40 rpm and a rotation speed of 90 rpm; after 25 min of ball milling, low-density polyethylene and MBA are added for further ball milling for 100 min, at which time the grinding temperature is 110°C, the revolution speed is 90 rpm, and the rotation speed is 180 rpm; to obtain premix A.

[0056] (2) The low-density polyethylene used for preparing the protective layer is ball milled, at a grinding temperature of 110°C, a revolution speed of 90 rpm, and a rotation speed of 180 rpm, for 110 min to obtain premix B.

[0057] (3) The above premix A and premix B are added into two single-screw extruders of a co-extrusion flow casting composite molding machine; the melting starting temperature of premix A is 150°C, and the temperature of each zone during the feeding to discharging process is set to 175°C, 185°C, and 200°C; the feeding temperature of premix B is 150°C, and the temperature of each zone is set to 170°C, 180°C, and 200°C; after full melting, the mixture is extruded through a single-layer die, with a die temperature of 200°C.

[0058] (4) After the film material is extruded through the die, it is stretched on a casting roller, at a casting area temperature of 62°C, and the thickness of the stretched film is controlled to be 35-40 μm.

[0059] The adhesive layer has a peel strength of 33.5 N / cm, and the protective layer has a peel strength of 22.1 N / cm, according to the national standard GB / T2790.

[0060] Example 3

[0061] In this example, another kind of high polymer protective film with a double-layer structure is provided, which comprises an adhesive layer and a protective layer. The raw material ratio of the adhesive layer is as follows: low-density polyethylene 170 parts, modified starch 85 parts, chitosan 8.2 parts, and crosslinking agent DCP 2.5 parts.

[0062] The preparation method of the above high polymer protective film is as follows:

[0063] (1) The above preparation raw materials for preparing the adhesive layer were washed with absolute ethanol respectively, and were put into a drying oven for 9.5 h at 90℃ to make them fully dried; the starch and chitosan in the above proportions were fully mixed and ball-milled, with a revolution speed of 60 rpm and a rotation speed of 110 rpm; after ball-milling for 35 min, low-density polyethylene and MBA were added and ball-milling was continued for 140 min, at which time the grinding temperature was 130℃, the revolution speed was 110 rpm, and the rotation speed was 220 rpm; thus, premix A was obtained.

[0064] (2) The low-density polyethylene used for preparing the protective layer was ball-milled, at a grinding temperature of 140℃, a revolution speed of 110 rpm, and a rotation speed of 220 rpm, for 130 min, to obtain premix B.

[0065] (3) The premix A and the premix B were added into two single-screw extruders of a co-extrusion casting composite molding machine; the melting starting temperature of the premix A was 150℃, and the temperature of each temperature zone during the feeding to discharging process was set to 172℃, 181℃, and 200℃, respectively; the feeding temperature of the premix B was 150℃, and the temperature of each temperature zone was 175℃, 180℃, and 200℃, respectively; after being fully melted, the premixes were extruded through a single-layer die, with a die temperature of 200℃.

[0066] (4) The film material after being extruded through the die was stretched on a casting roller, at a casting area temperature of 60℃, and the thickness of the stretched film was controlled to be 35-40 μm.

[0067] The adhesive layer had a peel strength of 41.8 N / cm, and the protective layer had a peel strength of 24.9 N / cm, as tested according to the national standard GB / T2790.

[0068] Example 4

[0069] In this example, another kind of double-layer structure polymer protective film was provided, which differed from Example 1 in that the raw material ratio of the protective layer was low-density polyethylene 241 parts and 4.2 parts of magnesium oxide or zinc oxide.

[0070] Example 5

[0071] In this example, another kind of polymer protective film was provided, which differed from Example 1 in that the raw material ratio of the protective layer was low-density polyethylene 240 parts and 0.3 parts of TINUVIN 791.

[0072] Comparative Example 1

[0073] In this example, another kind of polymer protective film was provided, which differed from Example 1 in that the raw material ratio of the adhesive layer was as follows: low-density polyethylene 160 parts, cellulose 60 parts, chitosan 9 parts, and N,N'-methylene bisacrylamide (MBA) 2 parts.

[0074] The preparation method is the same as that in Example 1. After single-layer die extrusion, the interface adhesion between the protective layer and the adhesive layer is poor, and the minimum thickness after stretching is 52 μm.

[0075] Comparative Example 2

[0076] In this example, another kind of high molecular protective film is provided. The difference from Example 1 is that the raw material ratio of the adhesive layer is as follows: low-density polyethylene 160 parts, cellulose 65 parts, and N,N'-methylene bisacrylamide (MBA) 2 parts.

[0077] The preparation method is as follows:

[0078] Premix A and premix B are obtained according to the preparation method in Example 1, and the premix A and premix B are added to two single-screw extruders of a co-extrusion casting compound molding machine. The feeding and melting starting temperature of premix A and B is 150°C, and the temperature is uniformly increased during the feeding and discharging process. The extrusion zone temperature is 220°C. After sufficient melting, the extrusion is carried out through a single-layer die, and the extrusion die temperature is set to 200°C. The casting chill roller temperature after extrusion is set to 35°C, and the speed is set to 12 r / min, so that the extruded A film and B film are fully bonded. The bonded film is placed back into a uniaxial stretching device, preheated at 120°C, and stretched at 150°C, so that the thickness of the stretched film is not more than 40 μm.

[0079] The film material prepared according to the formula in this example has obvious interface separation between the two layers after the first extrusion, and the casting property is poor, which cannot be stretched to below 40 μm. In this example, the thickness of the high molecular film is reduced to below 40 μm by prolonging the standing time and secondary warming and stretching.

[0080] Comparative Example 3

[0081] In this example, another kind of high molecular protective film is provided. The difference from Example 1 is that the preparation method is as follows:

[0082] The raw material ratio of the adhesive layer is as follows: low-density polyethylene 180 parts, chitosan 45 parts, and N,N'-methylene bisacrylamide (MBA) 2 parts. The rest is the same as in Example 1.

[0083] Performance characterization

[0084] The tensile strength, puncture resistance and degradation performance of the high molecular protective film materials prepared in the above examples and comparative examples are tested. In the following performance tests, the thickness of each group of film materials is 35±5 μm. Since the thickness of the film material in Comparative Example 1 cannot be reduced to below 50 μm, the tensile strength and puncture resistance of Comparative Example 1 are not investigated, and only the degradation performance is investigated.

[0085] Tensile strength

[0086] The membrane materials from the above embodiments and comparative examples were cut to the same size, and their tensile strength, elongation at break, and tensile modulus of elasticity were measured according to the method of national standard GB / T 1040.3-2006. Five samples were used in each group, and the average measurement results were taken. The results are shown in Table 1 below:

[0087] Table 1. Tensile strength of membrane materials in Examples 1-5 and Comparative Examples 1-3.

[0088]

[0089] Based on the above measurement results, the combination of starch and chitosan effectively improved the membrane strength of the polyethylene membrane after cross-linking. Using high molecular weight raw materials for cross-linking (Comparative Example 2) or using chitosan alone (Comparative Example 3) could not achieve similar technical effects.

[0090] Puncture resistance

[0091] According to the method of national standard GB / T 10004-2008, the puncture strength of the membrane materials in the above examples and comparative examples was tested. The membrane material thickness was 35±5μm. The membrane material was cut into test pieces with a diameter of 100mm. The puncture speed was (50±5)mm / min. The maximum load of the steel needle penetrating the membrane was read. Five membrane samples were measured in each group and the average value was taken. The results are shown in Table 2 below:

[0092] Table 2. Puncture resistance of membrane materials in Examples 1-5 and Comparative Examples 1-3

[0093]

[0094] In Comparative Example 1, the membrane material thickness could not be reduced to below 50 μm, making the measurement results meaningless for comparison. In Comparative Example 2, the membrane material exhibited greater strength; however, the preparation process required secondary stretching, resulting in higher costs. The comparative examples only introduced chitosan, a biodegradable material, which, while forming a dense membrane, also resulted in a decrease in strength.

[0095] Degradation performance:

[0096] The degradation performance of the membrane materials in Examples 1-5 was tested using the soil burial method. The samples were cut into 5×5cm pieces, and the shredded membranes were placed in a laboratory environment below the soil interface. They were removed periodically, washed, dried to constant weight, and then weighed. Each group of samples was weighed five times, and the average weight was taken. W 平均 The degradation rate of the membrane material is calculated using the following formula:

[0097] A %=W 起始 - W 平均 / W 起始 *100%.

[0098] The results are shown in Table 3 below:

[0099] Table 3. Degradation rates of membrane materials in Examples 1-5 and Comparative Examples 1-3 (ambient temperature 15℃)

[0100]

[0101] The membrane materials provided in Examples 1-5 all showed good degradation performance. The degradation effect was the worst in the comparative example, which may be related to the large membrane thickness. The degradation effect in Comparative Example 2 was also not ideal. The degradation effect of the membrane material in Comparative Example 3 was still somewhat different from that in Examples 1-5. It is speculated that this may be because the number of microorganisms adapted to chitosan is limited, thus reducing the decomposition effect.

[0102] Example 6

[0103] This embodiment provides the application of the polymer protective film in the asphalt pavement paving process described in Embodiment 1 above: such as Figure 1 As shown, after the road base layer 5 is laid, the curb stones 2 are installed. Before the asphalt pavement is laid, the protective film 1 from Example 1 is placed on the surface of the curb stones 2. The side closest to the curb stone is the adhesive layer, and the exposed side is the protective layer. When laying asphalt, after roughly cleaning the dust off the surface of the curb stones 2, the protective film 2 can be directly placed on the surface of the curb stones 2. The protective film 2 can adhere to the surface of the curb stones 2 through its own adhesive properties, or the surface of the curb stones 2 can be moistened to increase the adhesion with the protective film 1. After the asphalt pavement 3 is laid and the asphalt pavement 3 is formed, the construction workers can peel off the exposed protective film from the interface 4. The part buried under the asphalt can degrade on its own.

[0104] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high molecular protective film, characterized by, The protective film comprises an integrally formed adhesive layer and a protective layer; the adhesive layer is prepared from the following raw materials: 150-170 parts of low-density polyethylene, 75-86 parts of starch, 8-11.2 parts of chitosan, and 2-6 parts of cross-linking agent; and the protective layer is prepared from the following raw materials: at least 240-260 parts of low-density polyethylene. The low-density polyethylene has a density of 0.918-0.935 g / cm3. The protective film has a thickness of 30-40 μm. The preparation method of the high-molecular protective film comprises the following steps: mixing and grinding the raw material components for preparing the adhesive layer to obtain premix A, mixing the raw material components for preparing the protective layer to obtain premix B, and then melt-extruding the premixes A and B through a single-screw respectively and then drawing to obtain the high-molecular protective film. The premix A is prepared by mixing and grinding the starch and chitosan at high speed for 25-35 min at a revolution speed of 40-60 rpm and a rotation speed of 90-110 rpm, and then adding the low-density polyethylene and cross-linking agent and continuing to ball mill at 100-140 ℃ for 100-140 min at a grinding temperature of 110-130 ℃, a revolution speed of 90-110 rpm and a rotation speed of 180-220 rpm. The premix B is prepared by ball milling the low-density polyethylene at 100-140 ℃ for 110-130 min at a revolution speed of 90-110 rpm and a rotation speed of 180-220 rpm.

2. The polymeric protective film according to claim 1, wherein The protective layer further comprises 4-6 parts of sunscreen agent, and the sunscreen agent is magnesium oxide, zinc oxide or titanium dioxide.

3. The polymeric barrier film of claim 1, wherein The protective layer further comprises a light stabilizer, and the light stabilizer is TINUVIN 791.

4. The polymeric barrier film of claim 1, wherein The starch is selected from one or a mixture of several of corn starch, barley starch, oat starch, buckwheat starch, potato starch, cassava starch, sweet potato starch, and modified starch, and the modified starch is microbial fermentation modified starch or oxidized denatured starch.

5. The polymeric barrier film of claim 1, wherein The cross-linking agent is selected from one or a combination of N,N'-methylene bisacrylamide and dicumyl peroxide.

6. The polymeric barrier film of claim 1, wherein In the preparation method, the premix A or B is uniformly heated during the melting process, and the melting starting temperature is 150 ℃ when feeding and the temperature is 200 ℃ when extruding.

7. The polymeric barrier film of claim 1, wherein In the preparation method, the drawing temperature is 60-65 ℃, and is not lower than 60 ℃.

8. Use of the high-molecular protective film according to any one of claims 1-7 as outdoor packaging material.

9. Use of the high-molecular protective film according to any one of claims 1-7 in the field of asphalt pavement laying.

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