阅读说明：本技术 一种气相核心微泡散射薄膜及其制备方法和应用 (Gas-phase core microbubble scattering film and preparation method and application thereof ) 是由 江韬 于 2020-06-15 设计创作，主要内容包括：本发明涉及薄膜技术领域,具体涉及一种气相核心微泡散射薄膜及其制备方法和应用。一种气相核心微泡散射薄膜,所述薄膜至少包括聚乙烯芯层；所述聚乙烯芯层的制备原料,按重量份计,至少包括以下组分：聚乙烯和/或乙烯-醋酸乙烯共聚物60-90份、防流滴剂10-20份、发泡剂5-10份、活性剂1-5份、成核剂1-5份、其他助剂5-20份；所述薄膜还包括附着于所述聚乙烯芯层至少一侧表面的聚乙烯表层。本发明提供的薄膜对透光率影响小,保温性能、氧气阻隔能力、揉搓强度和弯曲模量优异。另外,薄膜内部连续性网状结构提高对缓释型添加剂的吸附功能,如流滴剂消雾剂,缓释性能比普通薄膜长一倍之多。(The invention relates to the technical field of films, in particular to a gas-phase core microbubble scattering film and a preparation method and application thereof. A gas phase core microbubble scattering film comprising at least a polyethylene core layer; the polyethylene core layer is prepared from the following raw materials in parts by weight: 60-90 parts of polyethylene and/or ethylene-vinyl acetate copolymer, 10-20 parts of anti-dripping agent, 5-10 parts of foaming agent, 1-5 parts of active agent, 1-5 parts of nucleating agent and 5-20 parts of other auxiliary agent; the film further includes a polyethylene skin layer attached to at least one side surface of the polyethylene core layer. The film provided by the invention has small influence on light transmittance, and has excellent heat preservation performance, oxygen barrier capability, kneading strength and flexural modulus. In addition, the continuous network structure in the film improves the adsorption function of the slow-release additive, such as a dripping agent and an antifogging agent, and the slow-release performance of the film is twice as long as that of the common film.)

1. A gas phase core microbubble scattering film, characterized in that the film comprises at least a polyethylene core layer; the polyethylene core layer is prepared from the following raw materials in parts by weight: 60-90 parts of polyethylene and/or ethylene-vinyl acetate copolymer, 10-20 parts of anti-dripping agent, 5-10 parts of foaming agent, 1-5 parts of active agent, 1-5 parts of nucleating agent and 5-20 parts of other auxiliary agent.

2. The gas-phase core microbubble scattering film according to claim 1, wherein the average particle size of the microbubbles in the polyethylene core layer is 1 to 50 μm.

3. The gas-phase core microbubble scattering film of claim 1, wherein the polyethylene and the ethylene-vinyl acetate copolymer each have a melt flow rate of 0.1-2g/10 min.

4. The gas-phase core microbubble scattering film as set forth in claim 1, wherein the nucleating agent has a fineness of 800-2000 mesh.

5. The gas-phase core microbubble scattering film according to any one of claims 1 to 4, wherein the polyethylene core layer has a thickness of 30 to 150 μm.

6. The gas-phase core microbubble scattering film of claim 1, further comprising a polyethylene skin layer attached to at least one side surface of the polyethylene core layer.

7. The gas-phase core microbubble scattering film according to claim 6, wherein the polyethylene skin layer is prepared from raw materials comprising polyethylene and an auxiliary agent; the auxiliary agent at least comprises at least one of antistatic agent, light stabilizer, light absorber, anti-dripping agent and heat preservation agent.

8. The gas-phase core microbubble scattering film of claim 6, wherein the density of the film is 0.4-0.9g/cm³。

9. A method for preparing a gas-phase core microbubble scattering film according to any of claims 6-8, characterized by comprising at least the following steps:

(1) respectively mixing the polyethylene core layer and the polyethylene surface layer, and uniformly mixing by a mixer;

(2) respectively pumping the uniformly mixed raw materials of the polyethylene core layer and the polyethylene surface layer into corresponding extruders;

(3) extruding the raw materials onto a co-extrusion film head by an extruder, cooling by adopting a long-neck air ring, wherein the primary cooling blow-up ratio is 1-1.5, the secondary cooling blow-up ratio is not less than 2, and blowing to a bubble film with a corresponding diameter;

(4) and (3) gradually forming the film bubble into a sheet film under the traction of a traction machine through the action of a bubble stabilizing frame and a propeller strut, and rolling and packaging to obtain the film bubble.

10. Use of the gas-phase core dispersion micro-irradiated film according to any one of claims 6 to 8 in the fields of packaging bags, vacuum heat-sealing films, low-temperature packaging films, composite films, medical and hygienic products, and agricultural films.

Technical Field

The invention relates to the technical field of films, in particular to a gas-phase core microbubble scattering film and a preparation method and application thereof.

Background

China is a big country for agricultural production, agricultural films are important production data of modern agriculture, and particularly, functional agricultural films play an important role in increasing both production and income of agriculture. The functional film covering area of China reaches 3000 ten thousand mu, and the functional film covers the top of the world, but compared with advanced countries, the agricultural film level of China has obvious gap, high technical content, few products with high added value, and a large number of middle and low-grade products, and the requirements of modern agricultural cultivation technology on the aspects of variety, quality, function, application field and the like cannot be met. With the improvement of raw materials, additives, processing technology and gardening production mode, the varieties of novel functional agricultural films are endless. At present, the research of the functional greenhouse film takes a polyolefin multifunctional film with high weather resistance, high light transmission, high scattering, high heat preservation, long-acting dripping antifogging and light quality improvement as a research and development hotspot.

The functional agricultural film in China takes LDPE and LLDPE as base resin, and has common light transmittance. The traditional functional film is prepared by adopting common talcum powder, diatomite, kaolin and nano-silica as heat-insulating additives, so that the transparency of the product is greatly influenced, and visible light and invisible light are blocked while far infrared light is blocked, so that the temperature-increasing effect is poor. Secondly, the traditional agricultural film achieves the purpose of scattering light in the greenhouse by adding an inorganic scattering agent, but also causes the serious influence on the light transmittance, and the serious cooling effect in the greenhouse influences the growth of crops. In addition, the anti-fogging function is mainly realized by adopting a method of internally adding dripping agents, the internal addition method causes the reduction of the mechanical property of the greenhouse film and the interference of the stability of an anti-aging auxiliary agent system due to the addition of the dripping agents, the dripping agents continuously migrate from film molecules to the surface and are taken away along with water flow, the dripping period is short, and generally 3-6 months; in addition, the dripping agent is precipitated on the surface of the outer layer of the film in a considerable amount, thereby having a significant adverse effect on the transparency and dust-proof performance of the greenhouse film.

Therefore, the present invention provides a gas phase core microbubble scattering film with high heat preservation, high scattering degree, no obvious reduction in light transmittance, long lasting period of dripping fog prevention, oxygen barrier capacity, high kneading strength and high flexural modulus.

Disclosure of Invention

In order to solve the above technical problems, a first aspect of the present invention provides a gas phase core microbubble diffusion film comprising at least a polyethylene core layer; the polyethylene core layer is prepared from the following raw materials in parts by weight: 60-90 parts of polyethylene and/or ethylene-vinyl acetate copolymer, 10-20 parts of anti-dripping agent, 5-10 parts of foaming agent, 1-5 parts of active agent, 1-5 parts of nucleating agent and 5-20 parts of other auxiliary agent.

In a preferred embodiment of the present invention, the average diameter of the microbubbles in the polyethylene core layer is 1 to 50 μm.

As a preferable technical scheme of the invention, the melt flow rates of the polyethylene and the ethylene-vinyl acetate copolymer are both 0.1-2g/10 min.

As a preferable technical scheme of the invention, the fineness of the nucleating agent is 800-2000 meshes.

In a preferred embodiment of the present invention, the polyethylene core layer has a thickness of 30 to 150 μm.

In a preferred embodiment of the present invention, the film further comprises a polyethylene skin layer attached to at least one surface of the polyethylene core layer.

As a preferred technical scheme of the invention, the raw materials for preparing the polyethylene surface layer comprise polyethylene and an auxiliary agent; the auxiliary agent at least comprises at least one of antistatic agent, light stabilizer, light absorber, anti-dripping agent and heat preservation agent.

As a preferable technical scheme of the invention, the density of the film is 0.4-0.9g/cm³。

The second aspect of the present invention provides a method for preparing the gas-phase core microbubble scattering film, which at least comprises the following steps:

(1) respectively mixing the polyethylene core layer and the polyethylene surface layer, and uniformly mixing by a mixer;

(2) respectively pumping the uniformly mixed raw materials of the polyethylene core layer and the polyethylene surface layer into corresponding extruders;

(3) extruding the raw materials onto a co-extrusion film head by an extruder, cooling by adopting a long-neck air ring, wherein the primary cooling blow-up ratio is 1-1.5, the secondary cooling blow-up ratio is not less than 2, and blowing to a bubble film with a corresponding diameter;

(4) and (3) gradually forming the film bubble into a sheet film under the traction of a traction machine through the action of a bubble stabilizing frame and a propeller strut, and rolling and packaging to obtain the film bubble.

The third aspect of the invention provides application of the gas-phase core scattering film, which is applied to the fields of packaging bags, vacuum heat-sealing films, low-temperature packaging films, composite films, medical and health products and agricultural films.

Advantageous effects

The invention provides a gas-phase core microbubble scattering film which is prepared by a multilayer co-extrusion blow molding process, wherein the shape of microbubbles is continuous, the diameter of the microbubbles is controllable, inert gas is filled in foam holes, light is reflected and refracted through the microbubbles, the gas-phase core microbubble scattering film can replace the traditional inorganic scattering agent, the scattering degree can reach 90 percent at most, the light transmittance is reduced slightly, meanwhile, the heat preservation coefficient of the film is improved by more than 200 percent, the temperature reduction effect of a greenhouse is achieved in summer, the heat dissipation in the greenhouse is delayed in winter, and the high heat preservation effect is achieved; the continuous air cavity improves the oxygen barrier capability, the kneading strength and the bending modulus of the film. In addition, the continuous network structure in the film improves the adsorption function of the slow-release additive, such as a dripping agent and an antifogging agent, and the slow-release performance of the film is twice as long as that of the common film.

Detailed Description

The disclosure may be understood more readily by reference to the following detailed description of preferred embodiments of the invention and the examples included therein. Unless defined otherwise, 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 invention belongs. In case of conflict, the present specification, including definitions, will control.

The term "prepared from …" as used herein is synonymous with "comprising". The terms "comprises," "comprising," "includes," "including," "has," "having," "contains," "containing," or any other variation thereof, as used herein, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

The conjunction "consisting of …" excludes any unspecified elements, steps or components. If used in a claim, the phrase is intended to claim as closed, meaning that it does not contain materials other than those described, except for the conventional impurities associated therewith. When the phrase "consisting of …" appears in a clause of the subject matter of the claims rather than immediately after the subject matter, it defines only the elements described in the clause; other elements are not excluded from the claims as a whole.

When an amount, concentration, or other value or parameter is expressed as a range, preferred range, or as a range of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted to include the ranges "1 to 4", "1 to 3", "1 to 2 and 4 to 5", "1 to 3 and 5", and the like. When a range of values is described herein, unless otherwise stated, the range is intended to include the endpoints thereof and all integers and fractions within the range.

The singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. "optional" or "any" means that the subsequently described event or events may or may not occur, and that the description includes instances where the event occurs and instances where it does not.

Approximating language, as used herein throughout the specification and claims, is intended to modify a quantity, such that the invention is not limited to the specific quantity, but includes portions that are literally received for modification without substantial change in the basic function to which the invention is related. Accordingly, the use of "about" to modify a numerical value means that the invention is not limited to the precise value. In some instances, the approximating language may correspond to the precision of an instrument for measuring the value. In the present description and claims, range limitations may be combined and/or interchanged, including all sub-ranges contained therein if not otherwise stated.

In addition, the indefinite articles "a" and "an" preceding an element or component of the invention are not intended to limit the number requirement (i.e., the number of occurrences) of the element or component. Thus, "a" or "an" should be read to include one or at least one, and the singular form of an element or component also includes the plural unless the stated number clearly indicates that the singular form is intended.

In order to solve the above technical problems, a first aspect of the present invention provides a gas phase core microbubble diffusion film comprising at least a polyethylene core layer; the polyethylene core layer is prepared from the following raw materials in parts by weight: 60-90 parts of polyethylene and/or ethylene-vinyl acetate copolymer, 10-20 parts of anti-dripping agent, 5-10 parts of foaming agent, 1-5 parts of active agent, 3-8 parts of nucleating agent and 5-20 parts of other auxiliary agent.

In a preferred embodiment, the raw materials for preparing the polyethylene core layer at least comprise the following components in parts by weight: 80 parts of polyethylene and/or ethylene-vinyl acetate copolymer, 15 parts of anti-dripping agent, 8 parts of foaming agent, 4 parts of active agent, 4 parts of nucleating agent and 10 parts of other auxiliary agent.

Polyethylene and/or ethylene-vinyl acetate copolymer

In the invention, the content of the ethylene-vinyl acetate in the polyethylene and/or the ethylene-vinyl acetate copolymer is 0-70 wt% of the polyethylene.

In a preferred embodiment, the content of ethylene-vinyl acetate in the polyethylene and/or ethylene-vinyl acetate copolymer is 10-50 wt% of the polyethylene.

In a more preferred embodiment, the polyethylene and/or ethylene-vinyl acetate copolymer has an ethylene-vinyl acetate content of 20 to 40 wt% of the polyethylene.

In a most preferred embodiment, the polyethylene and/or ethylene-vinyl acetate copolymer has an ethylene-vinyl acetate content of 30 wt% of the polyethylene.

In the invention, the melt flow rates of the polyethylene and the ethylene-vinyl acetate copolymer are both 0.1-2g/10 min.

Melt flow rate (abbreviated as MFR, melt mass flow rate), also referred to as Melt Index (MI), is the gram of melt flowing through a standard capillary over a period of time (typically 10min) in g/10min at a certain temperature and pressure in a standardized melt index apparatus. The melt flow rate is an important reference basis for selecting plastic processing materials and brands, so that the selected raw materials can better meet the requirements of the processing technology, and the reliability and the quality of the formed product are improved. The melt flow rate of the invention is 230 ℃/2.16 kg.

Polyethylene

Polyethylene (PE) is a thermoplastic resin obtained by polymerizing ethylene. In industry, copolymers of ethylene with small amounts of alpha-olefins are also included. The polyethylene has no odor and no toxicity, feels like wax, has excellent low-temperature resistance (the lowest use temperature can reach-100 to-70 ℃), has good chemical stability, and can resist the corrosion of most of acid and alkali (cannot resist acid with oxidation property). Is insoluble in common solvents at room temperature, has low water absorption and excellent electrical insulation.

In the present invention, the polyethylene is not particularly limited, and high density polyethylene, low density polyethylene, linear low density polyethylene and the like can be mentioned.

In a preferred embodiment, the polyethylene is a low density polyethylene.

In a preferred embodiment, the low density polyethylene has a melt flow rate of from 0.1 to 1g/10 min.

In a more preferred embodiment, the low density polyethylene has a melt flow rate of from 0.1 to 0.5g/10 min.

In a most preferred embodiment, the low density polyethylene has a melt flow rate of from 0.2 to 0.4g/10 min.

In the present invention, the source of the low density polyethylene is not particularly limited, and ExxonMobil chemical industry, Exxonmobil, may be mentioned^TMLDPE LD 165BW1、ExxonMobil^TMLDPE LD 051, LQ, etc.

Ethylene-vinyl acetate copolymer

The ethylene-vinyl acetate copolymer is a general high molecular polymer, is called EVA for short, has a code of 1314, and has a molecular formula of (C)₂H₄)_x.(C₄H₆O₂)_y. It is combustible and has no irritation to combustion smell.

In the invention, the content of vinyl acetate in the ethylene-vinyl acetate copolymer is 10-25 wt%.

In a preferred embodiment, the ethylene-vinyl acetate copolymer has a vinyl acetate content of 15 to 20 wt%.

In a preferred embodiment, the ethylene-vinyl acetate copolymer has a melt flow rate of 0.5 to 1.5g/10 min.

In a more preferred embodiment, the ethylene-vinyl acetate copolymer has a melt flow rate of 0.5 to 1g/10 min.

In a most preferred embodiment, the ethylene vinyl acetate copolymer has a melt flow rate of 0.7g/10 min.

In the present invention, the source of the ethylene-vinyl acetate copolymer is not particularly limited, and Escorene, chemical engineering, Escorene, may be mentioned^TMUltra LD 730Series Blown、Escorene^TMUltra LD 730series molding, etc.

The inventor finds that the low-density polyethylene has good flexibility, extensibility, transparency and easy processability, and simultaneously has larger air permeability, and when the gas decomposition speed of the foaming agent is too high, the bubble growth speed is too high, and the phenomena of bubble collapse and gas escape are easy to occur. The inventor finds in the experimental process that when the ethylene-vinyl acetate copolymer is compounded in a certain proportion, particularly when the vinyl acetate content in the ethylene-vinyl acetate copolymer is 10-25 wt%, the compatibility of molecules of two polymers is ensured, and simultaneously the stability of foam holes is effectively improved. The inventor thinks that the possible reason is that the compounding of two high molecular polymers with different melt strengths improves the mutual crosslinking strength between the polymer molecules, adjusts the melt strength of the polymer molecules and obviously improves the stability of foam pores. Because the melt strength of the polyethylene with low crosslinking degree is low, the foam holes are uneven, and the crosslinking degree of the polyethylene can be improved and the gas retention property can be improved by compounding a certain amount of the ethylene-vinyl acetate copolymer; however, if the amount of ethylene-vinyl acetate added is too large, the degree of crosslinking becomes excessive, and the foaming, appearance and unevenness are observed, so that the foaming effect is best when the ethylene-vinyl acetate content is 10 to 50 wt% of the polyethylene.

Anti-dripping agent

The dripping agent is a surfactant which acts as a kind of auxiliary agent for destroying the interfacial tension between the water droplets and the film and preventing the formation of water droplets on the surface. The dripping agent is generally a chemical with surface activity, and is added in the process of processing the polymer, so that condensed water drops can be distributed into a continuous transparent thin layer, and the function of the dripping agent is to reduce the contact angle between water and the surface of the polymer and prevent the surface from forming water drops.

In the present invention, the drip inhibitor is not particularly limited, and is commercially available and suitable for use in the present invention.

In a preferred embodiment, the anti-drip agent may be a glyceryl stearate anti-drip agent.

The inventors have found that whatever anti-dripping agent or anti-fogging agent is used in the present invention, the sustained release property is as much as twice as long as that of a conventional film. The inventor thinks that the possible reason is that the film is internally provided with interconnected or closed holes to form a network structure, so that the adsorption function of the film on the anti-dripping agent is obviously improved, and the anti-dripping agent is effectively inhibited from migrating from the film molecules to the surface and flowing away along with water.

Foaming agent

The foaming agent is a substance for forming pores in a target substance and can be classified into a chemical foaming agent, a physical foaming agent and a surfactant. Chemical blowing agents are those compounds which decompose upon heating to release gases such as carbon dioxide and nitrogen and form pores in the polymer composition; physical blowing agents are those in which the foam cells are formed by a change in the physical form of a substance, i.e., by expansion of a compressed gas, volatilization of a liquid, or dissolution of a solid; the foaming agents have higher surface activity, can effectively reduce the surface tension of liquid, are arranged on the surface of a liquid film in an electric double-layer mode to surround air to form bubbles, and then form foam by single bubbles.

In the present invention, the foaming agent is not particularly limited, and inorganic foaming agents, organic foaming agents, physical foaming agents and the like can be mentioned.

As the inorganic foaming agent, silicate, carbonate, silicon carbide, carbon black, and the like can be mentioned.

As the organic foaming agent, there may be mentioned azo compounds, sulfonylhydrazide compounds, nitroso compounds and the like.

As the physical blowing agent, n-pentane, n-hexane, n-heptane, petroleum ether, trichlorofluoromethane, dichlorodifluoromethane, dichlorotetrafluoroethane and the like can be mentioned.

In a preferred embodiment, the foaming agent is an organic foaming agent or an inorganic foaming agent.

Active agent

Can increase the activity of the organic accelerator to fully exert the effect, thereby reducing the dosage of the accelerator or shortening the vulcanization time.

In the present invention, the accelerator is a surfactant.

Surfactant (surfactant) is a substance added in a small amount to change the interface state of a solution system obviously. Has fixed hydrophilic and lipophilic groups and can be directionally arranged on the surface of the solution. The molecular structure of the surfactant has amphipathy: one end is a hydrophilic group, and the other end is a hydrophobic group; the hydrophilic group is often a polar group, such as carboxylic acid, sulfonic acid, sulfuric acid, amino or amino groups and salts thereof, hydroxyl, amide, ether linkages, and the like may also be used as the polar hydrophilic group; and the hydrophobic group is often a non-polar hydrocarbon chain, such as a hydrocarbon chain of 8 or more carbon atoms. The surfactant is divided into ionic surfactant (including cationic surfactant and anionic surfactant), nonionic surfactant, amphoteric surfactant, compound surfactant, other surfactants, etc.

In a preferred embodiment, the surfactant is not particularly limited.

As the surfactant, cationic surfactants, anionic surfactants, nonionic surfactants, and the like can be mentioned.

In a preferred embodiment, the surfactant is an anionic surfactant.

In the present invention, the source of the active agent is not particularly limited, and commercially available active agents are suitable for use in the present invention.

Nucleating agent

The nucleating agent is a new functional assistant which is suitable for incomplete crystallization plastics such as polyethylene, polypropylene and the like, accelerates the crystallization rate, increases the crystallization density and promotes the grain size to be micronized by changing the crystallization behavior of resin, thereby achieving the purposes of shortening the molding period, and improving the physical and mechanical properties such as the transparency, the surface gloss, the tensile strength, the rigidity, the heat distortion temperature, the impact resistance, the creep resistance and the like of products.

In the present invention, the nucleating agent is not particularly limited, and organic nucleating agents, inorganic nucleating agents, polymeric nucleating agents and the like can be mentioned.

In a preferred embodiment, the nucleating agent is an inorganic nucleating agent.

In a more preferred embodiment, as the inorganic nucleating agent, talc, calcium carbonate, silica, alum, titanium dioxide, calcium oxide, magnesium oxide, carbon black, mica, and the like can be mentioned.

In a more preferred embodiment, the inorganic nucleating agent is calcium carbonate, silica.

In the invention, the fineness of the nucleating agent is 800-2000 meshes.

In a preferred embodiment, the fineness of the nucleating agent is 1000-1500 meshes.

In a more preferred embodiment, the nucleating agent has a fineness of 1250 mesh.

In the present invention, the source of the nucleating agent is not particularly limited, and 1250 mesh silica, purchased from Henan Taiji chemical products Co., Ltd, can be mentioned.

In the invention, the weight ratio of the polyethylene and/or the ethylene-vinyl acetate copolymer to the nucleating agent is (10-30): 1.

in a more preferred embodiment, the weight ratio of the polyethylene and/or ethylene vinyl acetate copolymer to the nucleating agent is 20: 1.

in the invention, the average grain diameter of the microbubbles in the polyethylene core layer is 1 to 50 μm.

The inventor unexpectedly discovers in the research process that the nucleating agent with the fineness of 800-2000 meshes, particularly 1000-1500 meshes can improve the dispersibility of the nucleating agent in a system, ensure the density and the size of cells in a film to be moderate, control the pore diameter of the cells to be 5-30 mu m and be beneficial to improving the light transmittance. If the grain diameter of the nucleating agent is too small, the nucleating agent can agglomerate in the system, so that the cells are not uniformly dispersed; if the grain diameter of the nucleating agent is too large, the size and the density of the cells are small, the refraction and the scattering of light are not facilitated, and the heat insulation performance and the oxygen resistance performance of the film are greatly reduced.

Other auxiliaries

In the present invention, the other additives are not particularly limited, and include, but are not limited to, a heat insulating agent, a light stabilizer, a light absorber, and the like.

In the present invention, the polyethylene core layer has a thickness of 30 to 150 μm.

In a preferred embodiment, the polyethylene core layer has a thickness of 50 to 100 μm.

In the present invention, the film further comprises a polyethylene skin layer attached to at least one side surface of the polyethylene core layer.

In a preferred embodiment, the raw materials for preparing the polyethylene surface layer comprise polyethylene and an auxiliary agent; the auxiliary agent at least comprises at least one of antistatic agent, light stabilizer, light absorber, anti-dripping agent and heat preservation agent.

In the present invention, the density of the film is 0.4 to 0.9g/cm³。

The second aspect of the present invention provides a method for preparing the gas-phase core microbubble scattering film, which at least comprises the following steps:

(1) respectively mixing the polyethylene core layer and the polyethylene surface layer, and uniformly mixing by a mixer;

(2) respectively pumping the uniformly mixed raw materials of the polyethylene core layer and the polyethylene surface layer into corresponding extruders;

(3) extruding the raw materials onto a co-extrusion film head by an extruder, cooling by adopting a long-neck air ring, wherein the primary cooling blow-up ratio is 1-1.5, the secondary cooling blow-up ratio is not less than 2, and blowing to a bubble film with a corresponding diameter;

(4) and (3) gradually forming the film bubble into a sheet film under the traction of a traction machine through the action of a bubble stabilizing frame and a propeller strut, and rolling and packaging to obtain the film bubble.

The third aspect of the invention provides application of the gas-phase core scattering film, which is applied to the fields of packaging bags, vacuum heat-sealing films, low-temperature packaging films, composite films, medical and health products and agricultural films.

The invention also provides a gas-phase core microbubble film which comprises an upper polyethylene surface layer, a polyethylene core layer and a lower polyethylene surface layer.

In a preferred embodiment, the film is applied to the field of agricultural films.

Upper polyethylene skin layer

In the invention, the thickness of the upper polyethylene surface layer is 10-50 μm.

In a preferred embodiment, the upper polyethylene skin layer has a thickness of 20 to 40 μm.

In a more preferred embodiment, the upper polyethylene skin layer has a thickness of 30 μm.

In the invention, the raw materials for preparing the upper polyethylene surface layer at least comprise the following components in parts by weight: 70-90 parts of polyethylene, 1-5 parts of antistatic agent, 5-10 parts of light stabilizer and 1-5 parts of light absorber.

In a preferred embodiment, the raw material for preparing the upper polyethylene surface layer comprises the following components in parts by weight: 85 parts of polyethylene, 3 parts of antistatic agent, 6 parts of light stabilizer and 2 parts of light absorber.

In a preferred embodiment, the polyethylene is a low density metallocene polyethylene.

In a more preferred embodiment, the low density metallocene polyethylene has a melt flow rate of from 0.5 to 2g/10 min.

In a most preferred embodiment, the low density metallocene polyethylene has a melt flow rate of 1g/10 min.

In the present invention, the source of the low-density metallocene polyethylene is not particularly limited, and there may be mentioned exxonmobil chemical industry, 1018 HA.

In the present invention, the antistatic agent, the light stabilizer and the light absorber in the upper polyethylene surface layer are not particularly limited, and commercially available materials are suitable for use in the present invention.

Lower polyethylene skin layer

In the invention, the thickness of the lower polyethylene surface layer is 10-50 μm.

In a preferred embodiment, the lower polyethylene skin layer has a thickness of 20 to 40 μm.

In a more preferred embodiment, the lower polyethylene skin layer has a thickness of 30 μm.

In the invention, the raw materials for preparing the lower polyethylene surface layer at least comprise the following components in parts by weight: 65-80 parts of polyethylene, 5-15 parts of anti-dripping agent, 1-10 parts of heat preservation agent, 5-10 parts of light stabilizer and 1-5 parts of light absorbent.

In a preferred embodiment, the raw material for preparing the lower polyethylene surface layer comprises the following components in parts by weight: 70 parts of polyethylene, 10 parts of anti-dripping agent, 5 parts of heat preservation agent, 7 parts of light stabilizer and 3 parts of light absorbent.

In a preferred embodiment, the polyethylene is a low density metallocene polyethylene.

In a more preferred embodiment, the low density metallocene polyethylene has a melt flow rate of from 0.5 to 2g/10 min.

In a most preferred embodiment, the low density metallocene polyethylene has a melt flow rate of 1g/10 min.

In the present invention, the source of the low-density metallocene polyethylene is not particularly limited, and there may be mentioned exxonmobil chemical industry, 1018 HA.

In the present invention, the anti-dripping agent, the heat retaining agent, the light stabilizer and the light absorber in the lower polyethylene surface layer are not particularly limited, and commercially available ones are suitable for the present invention.

The present invention will be specifically described below by way of examples. It should be noted that the following examples are only for illustrating the present invention and should not be construed as limiting the scope of the present invention, and that the insubstantial modifications and adaptations of the present invention by those skilled in the art based on the above disclosure are still within the scope of the present invention.

In addition, the starting materials used are all commercially available, unless otherwise specified.