CN111253879A

CN111253879A - Low-unwinding-force polyethylene low-viscosity protective film and preparation method thereof

Info

Publication number: CN111253879A
Application number: CN202010097838.2A
Authority: CN
Inventors: 邓隽; 李代珍; 邓建成
Original assignee: Foshan Shunyuan Plastic Products Co ltd
Current assignee: Foshan Shunyuan Plastic Products Co ltd
Priority date: 2020-02-17
Filing date: 2020-02-17
Publication date: 2020-06-09
Anticipated expiration: 2040-02-17
Also published as: CN111253879B

Abstract

The invention relates to the technical field of high-molecular plastic films, in particular to a low-unwinding-force polyethylene low-viscosity protective film and a preparation method thereof. A low uncoiling force polyethylene low-viscosity protective film comprises a surface layer, a core layer and a self-adhesive layer; the surface layer comprises polyethylene wax, organic silicon modified polyolefin, dendritic toughening agent, propenyl elastomer and polyethylene resin; the core layer comprises POE, mLLDPE, LLDPE, LDPE and color master batch; the self-adhesive layer comprises one or two of POE, SEBS, hydrogenated C5 resin or hydrogenated C9 resin or hydrogenated C5-C9 copolymer resin. The adhesive layer materials are uniformly mixed and then granulated, and then the mixture and the respective uniformly mixed materials of the surface layer and the core layer are sent to a three-layer co-extrusion film blowing machine for co-extrusion, and the production process is simple and feasible. The invention solves the problem of large uncoiling force of the existing polyethylene protective film, and is convenient for production enterprises to use the protective film for processing and production.

Description

Low-unwinding-force polyethylene low-viscosity protective film and preparation method thereof

Technical Field

The invention relates to the technical field of high-molecular plastic films, in particular to a low-unwinding-force polyethylene low-viscosity protective film and a preparation method thereof.

Background

The high molecular protective film is a film with pressure-sensitive adhesive on one surface, the products of the high molecular protective film are all in the form of a coiled plate, the pressure-sensitive adhesive of the film is tightly contacted with the back surface of the film, when the protective film is opened from a coiled state, the pressure-sensitive adhesive of the protective film is tightly connected with the back surface of the film and has strong tension, so that the protective film can be separated by a certain force, and the separated force is called unwinding force.

If the uncoiling force of the protective film is too high, the protective film deforms when uncoiled or the protective film is not flat after being attached to the protective film so as to seriously affect the quality of a product in the film attaching process of a user by using the protective film. Particularly, when the protective film is mechanically separated and applied to a product to be protected in an automatic production line, the unwinding force of the protective film is very important, and the smoothness of feeding and the stability of the application process are directly affected. The protective film with high bonding strength can even cause the phenomenon of film delamination of the protective film in the using process, thereby causing the rejection of the protective film.

In the prior art, polyethylene films without tie layers generally use small molecular compounds as anti-blocking agents to reduce unwinding force, such as anti-blocking agents, opening agents, lubricants, slip agents, etc. However, for the protective film with an adhesive layer, these small molecular compounds are not suitable for being used as an anti-sticking agent to reduce unwinding force, because after the surface layer is contacted with the adhesive layer, these small molecular compounds in the surface layer are easy to dissociate out to enter the adhesive layer due to the action of the adhesive, so that the adhesive force of the adhesive layer is greatly reduced and even fails. If silicone or the like is used, since it cannot be incorporated into the polyethylene protective film, it is only possible to coat the surface layer of the protective film with a solvent, which consequently requires two additional steps, which are time-consuming, laborious and costly. These solvents tend to remain or corrode upon contact with the products to which the films have been applied, causing unnecessary troubles and increasing the difficulty of processing and production.

Disclosure of Invention

Aiming at the problems of the defects of the prior art, the invention provides a polyethylene low-viscosity protective film with low uncoiling force.

The silicone modified polyolefin is a good anti-sticking substance, has relatively poor compatibility with polyethylene resin because of containing a silicone functional group, but can improve the compatibility of the silicone modified polyolefin in the polyethylene resin through the dispersing function of polyethylene wax.

The polyethylene wax with the dispersibility function can ensure that the organic silicon modified polyolefin is easily blended and compatible with the polyethylene resin; in the melting co-extrusion process, the high molecular long chains of the polyethylene wax and the organic silicon modified polyolefin and the high molecular chains of the dendritic flexibilizer are mutually interpenetrated and entangled to form a firm whole, and the polyethylene wax and the organic silicon modified polyolefin are anchored in the surface layer of the protective film, so that the adhesion-resistant substances can be prevented from freely running to the bonding layer from the surface layer, the uncoiling force of the protective film can be reduced, and the viscosity of the self-adhesive layer of the protective film is not influenced.

Furthermore, the invention also provides a preparation method of the polyethylene low-viscosity protective film with low unwinding force. The self-adhesive layer materials are uniformly mixed and then granulated, the problem that the materials of the self-adhesive layer penetrate into other film layers to generate anti-adhesion and uncoiling force failure in the co-extrusion process can be solved through granulation, and then the materials of the self-adhesive layer and the core layer are sent to a three-layer co-extrusion film blowing machine for co-extrusion. The preparation method adopted by the invention has controllable and effective production process and simple and easy operation.

In order to achieve the above object, the present invention adopts the following aspects.

The low-unwinding-force polyethylene low-viscosity protective film is composed of a surface layer, a core layer and a self-adhesive layer, wherein the core layer is positioned between the surface layer and the self-adhesive layer; the raw materials of the surface layer comprise polyethylene wax, organic silicon modified polyolefin and a dendritic flexibilizer;

the surface layer comprises the following components in parts by weight:

the surface layer of the protective film comprises one or two of LLDPE and LDPE, and the polyethylene resin does not contain micromolecular substances such as an opening agent, a slipping agent and the like.

Further, the polyethylene wax is selected from polyethylene wax with the average molecular weight of more than 4000.

Further, the silicone-modified polyolefin is a silane-modified amorphous a-polyolefin.

Further, the dendritic toughening agent is a dendritic polymer with a flexible polyolefin long segment.

Further, the core layer comprises the following components in parts by weight:

further, the self-adhesive layer comprises the following compositions in parts by weight:

and (3) 10-30 parts of POE,

30-60 parts of an adhesive agent,

10-50 parts of a tackifier.

Further, the adhesive is SEBS linear triblock copolymer;

further, the tackifier is one or two of hydrogenated C5 resin, hydrogenated C9 resin and hydrogenated C5-C9 copolymer resin.

Furthermore, POE in the components of the core layer and the self-adhesive layer adopts POE thermoplastic elastomer with the same mark.

Further, according to the technical scheme, the invention provides a preparation method of the low-unwinding force polyethylene low-viscosity protective film, which comprises the following steps:

step S1, uniformly mixing the raw materials on the surface layer to obtain a mixture M1;

step S2, uniformly mixing the raw materials of the core layer to obtain a mixture M2;

step S3, uniformly mixing the raw materials of the self-adhesive layer, and then blending and granulating to obtain granules M3;

and step S4, sending the granules M3 prepared in the step S3, the mixture M2 prepared in the step S2 and the mixture M1 prepared in the step S1 to a three-layer co-extrusion film blowing machine for extrusion film blowing to prepare the low-viscosity protective film of the low-unwinding-force polyethylene.

Based on the disclosure of the technical scheme, the invention has the following beneficial effects:

the invention provides a low unwinding force polyethylene protective film with a three-layer structure of a surface layer, a core layer and a self-adhesive layer, wherein polyethylene wax, organic silicon modified polyolefin and a dendritic flexibilizer are added into the surface layer, and the unwinding force is reduced by the anti-sticking property of the polyethylene wax and the organic silicon modified polyolefin; the organic silicon modified polyolefin and the polyethylene resin are blended and compatible through the dispersibility function of the polyethylene wax; the dendritic toughening agent can be mutually interpenetrated and entangled with the high-molecular long chains of the polyethylene wax and the organic silicon modified polyolefin to form a molecular chain net structure of the surface layer protective film, so that the polyethylene wax and the organic silicon modified polyolefin are anchored in the molecular chain net structure of the surface layer, and the adhesion resistance of the polyethylene wax and the organic silicon modified polyolefin is continuously and effectively achieved.

Through adding POE with the same trade mark of self-adhesive layer in the sandwich layer with the sandwich layer and the firm adhesion of self-adhesive layer as an organic whole, through POE, SEBS and hydrogenation C5 resin, hydrogenation C9 resin and/or hydrogenation C5-C9 copolymerization resin's synergism strengthens the adhesive force of protection film self-adhesive layer, protection film self-adhesive layer has powerful and controllable adhesive force to the external appearance this moment, make protection film self-adhesive layer and sandwich layer combine closely, the shock resistance of protection film has been promoted, consequently, can not appear coming unstuck in the use, tear, opening and layering phenomenon.

The protective film provided by the invention has good low uncoiling force, adhesiveness and tear resistance, can be widely used in industrial production, and is particularly suitable for production enterprises using the protective film to perform assembly line continuous operation.

The preparation method of the low-unwinding-force polyethylene low-viscosity protective film provided by the invention adopts a manufacturing and production process that the self-adhesive layer materials are uniformly mixed according to the weight part ratio and then granulated, and then the materials uniformly mixed with the surface layer and the core layer according to the material ratio are sent to a three-layer co-extrusion film blowing machine for co-extrusion, and the operation is simple and easy.

The polyethylene low-viscosity protective film with low uncoiling force provided by the invention solves the problem of large uncoiling force of the existing polyethylene protective film, and is convenient for production enterprises to use the protective film to perform assembly line operation processing production.

Detailed Description

The technical solution of the present invention is further illustrated by the following specific embodiments.

The low-unwinding-force polyethylene low-viscosity protective film is composed of a surface layer, a core layer and a self-adhesive layer, wherein the core layer is positioned between the surface layer and the self-adhesive layer; the raw materials of the surface layer comprise polyethylene wax, organic silicon modified polyolefin and a dendritic toughening agent.

The polyethylene wax and the organic silicon modified polyolefin contained in the surface layer have good lubricating property, scratch resistance, wear resistance, polishing resistance, imprint resistance and anti-adhesion performance, can prevent and overcome adhesive degumming between the coiled surface layer and the self-adhesive layer, and play a role in reducing uncoiling of the protective film.

The dendritic flexibilizer, the organic silicon modified polyolefin and the polyethylene wax are combined into a net structure, the organic silicon modified polyolefin and the polyethylene wax are anchored in the surface layer of the polyethylene low-viscosity protective film, and the polyethylene wax and the organic silicon modified polyolefin are prevented from dissociating to influence the bonding effect of the self-adhesive layer.

The surface layer comprises the following components in parts by weight:

the polyethylene resin included in the protective film of the invention refers to one or two of LLDPE and LDPE, and does not contain micromolecular substances such as an opening agent, a slipping agent and the like.

The surface layer takes polyethylene resin as a matrix, the impact resistance and tensile strength of the surface layer are improved by adding the propenyl elastomer, the flexibility and toughness of the surface layer polyethylene protective film are improved, the lubricity and glossiness of the surface protective film are improved by adding polyethylene wax and organic silicon modified polyolefin, the polyethylene wax and the organic silicon modified polyolefin are combined with a molecular chain of the dendritic flexibilizer into a net structure, the net structure can prevent the polyethylene wax and the organic silicon modified polyolefin from being separated out from the surface layer protective film to the adhesive layer, and the lower uncoiling force between the surface layer and the self-adhesive layer is kept continuously effective.

The propylene-based elastomer is an olefin-based elastomer mainly composed of isotactic polypropylene repeating units and randomly distributed polyethylene, is a low-density semicrystalline polyolefin having a soft point much lower than that of conventional polyethylene or polypropylene resins, and has excellent adhesion properties to various polyolefin substrates. The propylene-based elastomer is a unique propylene-ethylene semi-crystalline copolymer, belongs to the class of polyolefin elastomers, and is characterized in that a propylene-based elastomer takes a polypropylene crystal section as a hard section, ethylene and propylene are randomly arranged into a telescopic soft section, and the effects of elastic recovery and toughness increase are achieved through soft and hard arrangement, so that excellent elasticity is represented.

The propylene-based elastomer is Vidamia 6202FL, and good adhesion and good machining performance can be obtained by adding a small amount of Vidamia 6202 FL;

the widame 6202FL propylene-based elastomer combines elasticity, softness, adhesiveness, drapability and toughness, and has excellent mutual compatibility with other polymers, lower initial sealing temperature and higher heat seal strength and sealing strength. Can be combined with extensive polyolefine, and has good adhesive property, optical property, adhesive property, higher recoverability, toughness, chemical resistance, aging resistance and extremely low peculiar smell sensory property, so that the extruded composite soft film can be made into a protective film with better adhesive force, higher tear strength and impact resistance.

The polyethylene resin adopted by the surface layer comprises one or two of LLDPE and LDPE.

LLDPE is also called linear low density polyethylene, is non-toxic, tasteless, odorless milky white particles, has higher softening temperature and melting temperature, and is structurally different from general low density polyethylene, because the linear low density polyethylene has narrow molecular weight distribution and more short branched chains, the linear low density polyethylene has high tensile strength, penetration resistance, tear resistance and high elongation, and has certain oil resistance, and can resist acid, alkali, organic solvent and the like, so that the LLDPE is particularly suitable for manufacturing films. LDPE is also called high-pressure polyethylene, is a plastic material, is suitable for various molding processes of thermoplastic molding and processing, and has good molding processability.

The LLDPE contained in the surface layer is applicable to all types existing in the market, and is preferably LD 605;

the Yanshan petrochemical high-pressure polyethylene LD605 is LLDPE with good performance which is universally used in the existing market, has large yield, is easy to purchase and has strong universality.

The skin layer comprises LDPE suitable for all models currently on the market, preferably 2426H.

2426H is Low Density Polyethylene (LDPE), which is mainly used for film production, and is one of high pressure polyethylenes. LDPE2426H is colorless transparent disc-shaped particles and has high transparency.

Polyethylene wax, also known as high molecular wax or polyethylene wax, is a polyethylene with an average molecular weight of generally 2000-. The polyethylene wax with higher average molecular weight of about 5000 has chain polyethylene molecular chains which are easy to be entangled with the network chains of the dendritic toughening agent to form a whole, so that the polyethylene wax is difficult to be dissociated from the surface layer of the membrane.

Furthermore, the polyethylene wax is applicable to all types in the market, preferably HONEYWELL A-C6A with the average molecular weight of 3000-4500 or BASF A wax with the average molecular weight of 6000 or so with more concentrated average molecular weight.

The polyethylene wax Honeywell A-C6A has the molecular weight of 3000-4500, is mainly applied to extrusion, injection, extension, film blowing and blow molding of various plastics, and is an ideal external lubricant; the HONEYWELL polyethylene wax A-C6A has extremely high external lubrication and demolding effects, and does not influence the Vicat thermal change temperature and the impact strength of products; the extrusion rate of the product can be improved, and the surface of the product keeps luster; the HONEYWELL POLYETHYLENE WALT A-C6A can delay the accumulation of frictional heat, thereby improving the thermal stability at high temperature and having good electrical characteristics.

The Basff A wax is a low-density polyethylene wax homopolymer, is produced by adopting a synthesis method, has extremely narrow molecular weight distribution concentrated at about 6000, has good thermal stability, low hot melt viscosity and good fluidity, has good wetting and dispersing effects, and is widely used for processing various plastics.

The method selects the Bass A wax with more concentrated average molecular weight of about 6000, the chain-shaped molecular structure of the Bass A wax is very easy to be entangled with the network chain of the dendritic flexibilizer to form a whole, and the network chain of the structure is more uniform and has high tensile strength due to more concentrated molecular weight distribution, so that the polyethylene wax is more difficult to dissociate from the surface layer of the membrane.

The organic silicon modified polyolefin is silane modified amorphous alpha-polyolefin (APAO), preferably VestoplastEP 2412;

vestoplast EP2412 silane modified amorphous a-polyolefin is an organosilicon modified polyolefin, is a novel anti-sticking product developed by VESSTOPLAST company, has an average molecular weight of 12000-15000, can improve the release property of polyethylene, and particularly can prevent and overcome the adhesion of a film to play a role in reducing the unwinding force.

The flexible polyolefin long-chain-segment dendritic toughening agent has the functions of integral connection and buffering with chain molecular chains combined among polyethylene resin, polyethylene wax and organic silicon modified polyolefin molecules, and improves the impact strength of a surface layer system of the protective film. A large number of flexible long chain segments on the surface of the dendritic flexibilizer are in a spatial three-dimensional stretching state, and are combined with polyethylene resin, polyethylene wax and organic silicon modified polyolefin to form a three-dimensional net structure. Thereby further improving the stability of the polyethylene wax and the organic silicon modified polyolefin in the protective film, and achieving the purposes of reducing the uncoiling force of the protective film and not causing the anti-sticking substance to dissociate to influence the viscosity of the self-adhesive layer.

The dendritic flexibilizer is suitable for all types in the market, preferably CYD-6100;

the dendritic flexibilizer CYD-6100 has excellent flexibilizing effect due to the special dendritic structure, can obviously improve the melt flow property of polypropylene or polyethylene, has smaller hydrodynamic radius, can improve the impact resistance of all components in the protective film, and improves the stability of various polymers contained in the protective film.

Further, the core layer comprises the following components in parts by weight:

the POE thermoplastic elastomer and the mLLDPE metallocene polyethylene are added into the core layer, so that the elasticity and the impact resistance of the core layer can be effectively improved, and the overall flexibility of the protective film is improved.

The POE is a polyolefin thermoplastic elastomer, and is a thermoplastic elastomer which realizes in-situ polymerization of ethylene and octene by adopting a metallocene catalyst, and the POE plastic has narrow molecular weight distribution and better fluidity. The POE polyolefin thermoplastic elastomer is produced by a solution polymerization method, and has a physical crosslinking effect with polyethylene chain crystallization, and the introduction of a certain amount of octene weakens the crystallization property of the polyethylene chain and shows the amorphous characteristic of rubber elasticity. Because the molecular chain is saturated, the carbon atom is relatively less, and the heat aging resistance and the ultraviolet resistance are excellent.

The mLLDPE is applicable to all types existing in the market, preferably Exxon 3518 CB;

mLLDPE is metallocene polyethylene, is a novel thermoplastic, is the most important technical development of the polyolefin industry in the 90 s, is an important innovation following the LLDPE production technology, because it is polyethylene produced by using Metallocene (MAO) as a polymerization catalyst, the performance of mLLDPE is obviously different from that of polyethylene polymerized by using a traditional Ziegler-Natta catalyst, and the mLLDPE has more excellent stretchability and impact strength than the traditional Ziegler-Natta catalyst, surpasses the mechanical property requirement of a film mainly prepared from LLDPE, and also can obviously improve the toughness of a film mainly prepared from LDPE.

The Exxon 3518CB metallocene polyolefin is a polymer prepared by olefin polymerization reaction by using a metallocene coordination compound as a catalyst. The metallocene polymer has good processing performance, high strength, good rigidity and transparency, and obviously improves the performances of the mixture in the aspects of temperature resistance, chemical resistance and the like.

Color master batches with corresponding colors can be added into the core layer according to the requirements of users, and if the core layer is a transparent film, the color master batches are not added.

The core layer of the protective film comprises LLDPE which is suitable for all types on the market, preferably 7042 or 201;

in addition to the properties of conventional polyolefin resins, LLDPE is particularly excellent in tensile strength, tear strength, environmental stress cracking resistance, low temperature resistance, heat resistance and puncture resistance.

The LDPE included in the core layer of the protective film is suitable for all models currently on the market, preferably 2420H.

LDPE can be used alone or blended with other members of the polyethylene family. Films made from LDPE exhibit good optical properties, strength, flexibility, sealability, as well as slow odor diffusion and chemical stability. 2420H is one of the conventional general grades of LDPE, is convenient to purchase and has a good cost advantage.

10-30 parts of POE (polyolefin elastomer),

30-60 parts of an adhesive agent,

10-50 parts of a tackifier.

POE is added to the self-adhesive layer, and POE is good with other raw and other material compatibility of adhesive layer, has the bonding effect of adjustment sandwich layer and adhesive layer, and protection film sandwich layer and self-adhesive layer can combine more firmly.

The tackifier is added into the self-adhesive layer, so that the adhesive force of the self-adhesive layer can be further enhanced, and the adhesive force in the self-adhesive layer is stronger than that between the self-adhesive layer and the surface layer of the protective film, so that the phenomena of tearing and degumming of the protective film during uncoiling can be effectively avoided.

The protective film core layer and the self-adhesive layer comprise thermoplastic elastomer POE which has the function of adjusting the bonding effect of the adhesive layer and a protected product. The adhesive force of the core layer and the adhesive layer of the protective film is enhanced, so that the film cracking and separation phenomenon during the roll splitting of the protective film can be more effectively reduced.

The POE of the core layer of the protective film is applicable to all types in the market, preferably Vistamaxx 3020 FL;

vistamaxx 3020FL specialty elastomers polymerized using proprietary metallocene technology exhibit excellent compatibility by increasing flexibility, improving impact resistance, improving adhesion, and reducing or eliminating stress whitening while maintaining clarity. Low Vistamaxx 3020FL density makes the weight/thickness of the composite thinner

Further, the adhesive is SEBS linear triblock copolymer;

The adhesive SEBS adopted by the invention is a linear triblock copolymer which takes polystyrene as a tail end section and takes an ethylene-butylene copolymer obtained by hydrogenation of polybutadiene as a middle elastic block, and the SEBS does not contain unsaturated double bonds, so that the adhesive SEBS has good thermal stability and aging resistance, and is widely used for producing high-grade elastomers and adhesives.

The SEBS is suitable for all models in the market, preferably G1645;

SEBS G1645 produced by the American Keteng has excellent ageing resistance, plasticity and high elasticity, can be processed and used without vulcanization, can be recycled by leftover materials, and is widely used for producing high-grade elastomers, plastic modification, adhesives, lubricating oil tackifiers, fillers and sheath materials of wires and cables and the like. The SEBS has good weather resistance, heat resistance, compression deformation resistance and excellent mechanical property.

The self-adhesive layer of the protective film comprises hydrogenated C9 resin which is suitable for all models existing in the market, and preferably KD-F1095;

the hydrogenated C9 resin has better thermal stability and good compatibility with resins such as EVA, SEBS, SEIS and the like, and is widely used in the fields of hot melt adhesives and pressure sensitive adhesives.

The KD-F series hydrogenated C9 petroleum resin is suitable for hot melt adhesive and pressure sensitive adhesive. The adhesive has good compatibility with styrene polymers such as SIS, SBS, SEBS, SEPS and the like, natural rubber, synthetic rubber, EVA and the like, has good compatibility with natural tackifying resin (terpene, rosin and derivatives thereof), and improves various performances of the adhesive to different degrees.

The tackifier hydrogenated C5 resin is suitable for all types existing in the market, preferably LH 100-1Y;

the hydrogenated C5 resin has good tackifying property, compatibility, thermal stability and light stability, can improve the adhesive property of the adhesive, and is suitable for hot melt adhesive and pressure-sensitive adhesive as tackifying resin. The adhesive has various improved performances, has outstanding initial adhesive performance, and is an indispensable tackifying component.

Hydrogenated C5 resin produced by bluing LH100-1 has good tackifying property, compatibility, thermal stability and light stability, can improve the adhesive property of adhesiveness, and is an indispensable tackifying component of many adhesives. The coating is widely applied to the industries of thermosol, pressure-sensitive adhesive, structure and decoration of the building industry, automobile assembly, tires, commodity packaging, book binding, hygienic products, shoemaking, hot-melt road sign paint, colored asphalt and the like.

The hydrogenated C5-C9 copolymer resin is applicable to all models in the market, and Escorez5600 is preferred.

The hydrogenated C5-C9 copolymer resin has good compatibility with Natural Rubber (NR), synthetic rubber, styrene polymer (such as SIS, SBS, SEBS, EVA) and the like, has the advantages of hydrogenated C5 petroleum resin and hydrogenated C9 petroleum resin, and is widely applied to the fields of hot melt adhesives and pressure sensitive adhesives.

High performance tackifying resins, Escorez, are a series of tackifying resins produced by exxon mobil and are useful in a variety of adhesive applications including packaging, nonwovens, tapes, labels, book binding, woodworking, sealants, road signs, carpet underlay, tires, and the like. Escorez5600 series are super light color alicyclic hydrocarbon resins, used for enhancing the viscosity of various adhesives, including EVA, styrene block copolymer (SIS, SBS, SEBS), Amorphous Polyolefin Polymer (APP) and amorphous poly-a-olefin (APAO), especially suitable for packaging application, not only can enhance the initial viscosity and the adhesive force of the whole material, but also can improve the mechanical and optical properties of the blended polymer.

The POE with the same mark in the components of the core layer and the self-adhesive layer can further strengthen the adhesive force of the core layer and the self-adhesive layer, so that the three layers of films form a whole which is difficult to separate.

According to the technical scheme provided by the invention, the effectiveness of the technical scheme of the invention is illustrated by preparing the low-viscosity protective film examples and the comparative examples and testing the uncoiling force of the protective film, and the specific method is as follows:

1. the raw materials of the low-unwinding-force polyethylene low-viscosity protective film prepared in the examples and the comparative examples are specifically selected as follows:

1) the polyethylene wax included in the surface layer of the protective film is Bassfer A wax or Honeywell A-C6A, the organosilicon modified polyolefin is Vestoplast EP2412, the dendritic toughening agent is CYD-6100, the propenyl elastomer is Widamei 6202FL, the LLDPE is LD605, and the LDPE is 2426H;

2) the POE of the core layer of the protective film is Vistamaxx 3020FL, the mLLDPE is Exxon 3518CB, the LLDPE is 7042, and the LDPE is 2420H;

3) the self-adhesive layer of the protective film comprises POE (polyolefin elastomer) selected from Vistamaxx 3020FL, SEBS (polyethylene terephthalate) selected from G1645, hydrogenated C5 resin selected from LH100-1Y, hydrogenated C9 resin selected from KD-F1095, and hydrogenated C5-C9 copolymer resin selected from Escorez 5600;

4) the low adhesion protective film formulations of the examples are shown in table 1;

5) the formulation of the low adhesion protective film of the comparative example is shown in table 2.

2. The preparation method of the low-viscosity protective film of the embodiment and the comparative example is the same, and specifically comprises the following steps:

step S1, uniformly mixing the raw materials on the surface layer of the protective film to obtain a mixture M1;

step S2, uniformly mixing the raw materials of the protective film core layer to obtain a mixture M2;

step S3, uniformly mixing the raw materials of the self-adhesive layer of the protective film, and blending and granulating to obtain granules M3;

step S4, sending the granules M3 prepared in the step S3, the mixture M2 prepared in the step S2 and the mixture M1 prepared in the step S1 to a three-layer co-extrusion film blowing machine for extrusion film blowing to prepare the low-viscosity protective film of the low-unwinding-force polyethylene;

step S5, winding the cylindrical film blown out by the three-layer co-extrusion film blowing machine through trimming to obtain a low-viscosity winding drum protective film;

step S6, label the prepared low-viscosity protective film example or comparative example number.

3. The unwinding force of the protective film prepared in the above examples and comparative examples is tested according to the GB/T4850-.

4. The protective films of the examples and comparative examples were left to stand for 30 days, and the roll protective film was unwound at a speed of 300mm/min, and the surface layer of the protective film was observed and wiped by hand to confirm whether or not wax was precipitated, and the results of the examination were recorded in tables 3 and 4.

TABLE 1 compositions of skin, core, and tie materials of examples 1-8

TABLE 2 compositions of the skin, core, and tie coat materials of comparative examples 1-7

Table 3 test results of the protective films obtained in examples 1 to 8

Table 4 test results of the protective films manufactured in comparative examples 1 to 7

The analysis of the above related data shows that:

1. the test results of the above examples and comparative examples show that the protective film was not torn and the substrate was delaminated and opened during unwinding;

2. the above examples 1 to 8 had unwinding force values of 175.34 to 274.10g/25mm, and comparative examples 1 and 2, to which no polyethylene wax or silane-modified amorphous a-polyolefin was added, had unwinding forces of 582.26 and 590.32g/25mm, respectively, from which it was seen that the unwinding force of the protective film after addition of polyethylene wax or silane-modified amorphous a-polyolefin was significantly reduced compared to that without addition, and the magnitude of the reduction in unwinding force was more than 50%, indicating that the addition of the polyethylene wax and silane-modified amorphous a-polyolefin had a significant effect on the reduction in unwinding force of the low viscosity protective film of the present invention.

3. In comparative examples 3, 4 and 5, the polyethylene wax, the silane-modified amorphous a-polyolefin and the dendritic toughening agent were not added at the same time, and the analysis and detection results showed that:

1) in comparative examples 3 and 4, only one polyethylene wax was added in a small amount, so that the unwinding force was reduced to 418.31,390.65g/25mm, respectively. 2) Comparative examples 3 and 5, in which no dendritic toughening agent was added, occurred in which a small amount of the anti-blocking agent was released from the surface layer after 30 days. The experiment shows that the problem that polyethylene wax or silane modified amorphous a-polyolefin is not dissociated while the unwinding force of the low-viscosity protective film is reduced can be effectively solved only by adding the dendritic toughening agent while polyethylene wax and silane modified amorphous a-polyolefin are added.

4. The polyethylene wax and silane-modified amorphous a-polyolefin added in comparative examples 6 and 7 in weight parts of 4, 6 and 10, 13, respectively, were added in greater amounts than in examples 1-8, corresponding to unwinding forces of 142.61, 129.07g/25mm, which were still significantly reduced from the minimum unwinding force of 175.34g/25mm in examples 5-6. If the polyethylene wax and the silane-modified amorphous a-polyolefin are added in an excessive amount, the strength of the protective film is affected although the unwinding force can be further reduced, and the amount thereof is preferably controlled to 15% or less of the total amount of the surface layer raw material.

5. Examples 7 and 8 differ from examples 5 and 6 only in that the polyethylene wax has been replaced by a honewire a-C6A instead of a basf a wax, the remaining starting components being identical. The unwinding force of the examples 5 and 6 is 185.43 and 175.34g/25mm, the unwinding force of the examples 7 and 8 is 231.63 and 213.28g/25mm, and the unwinding force of the examples 5 and 6 is reduced by 20% and 18% compared with that of the examples 7 and 8, which shows that the polyethylene wax basf A wax has better effect of reducing the unwinding force of the protective film than the HONEYWELL A-C6A under the same conditions.

In summary, the invention provides a low unwinding force polyethylene protective film with a three-layer structure of a surface layer, a core layer and an adhesive layer, wherein polyethylene wax, organic silicon modified polyolefin and a dendritic toughening agent are added into the surface layer, the unwinding force of the protective film is reduced through the anti-adhesion property of the polyethylene wax and the organic silicon modified polyolefin, the dendritic toughening agent, the polyethylene wax and the high molecular chain of the organic silicon modified polyolefin are mutually interpenetrated and entangled to construct a molecular chain network structure of the surface layer protective film, and the polyethylene wax and the organic silicon modified polyolefin are anchored in the molecular chain network structure of the surface layer, so that the anti-adhesion property of the polyethylene wax and the organic silicon modified polyolefin is continuously effective.

Through adding in the sandwich layer with the POE of the same trade mark of self-adhesive layer with sandwich layer and the firm adhesion of self-adhesive layer as an organic whole, through POE, SEBS and hydrogenation C5 resin, hydrogenation C9 resin and/or hydrogenation C5-C9 copolymerization resin's synergism strengthens the adhesive force of protection film self-adhesive layer, make protection film self-adhesive layer have powerful and controllable adhesive force to the external appearance, the inside impact resistance who has promoted the protection film with the inseparable combination of sandwich layer of protection film self-adhesive layer simultaneously, consequently come unstuck in the use can not appear, tear, opening and layering phenomenon.

The protective film disclosed by the invention has the advantages of good low unwinding force, adjustable adhesiveness and tear resistance, can be widely used in industrial production, and is particularly suitable for production enterprises using the protective film to perform assembly line continuous operation.

The technical principle of the present invention is described above in connection with specific embodiments. The description is made for the purpose of illustrating the principles of the invention and should not be construed in any way as limiting the scope of the invention. Based on the explanations herein, those skilled in the art will be able to conceive of other embodiments of the present invention without inventive effort, which would fall within the scope of the present invention.

Claims

1. The low-unwinding-force polyethylene low-viscosity protective film is characterized by comprising a surface layer, a core layer and a self-adhesive layer, wherein the core layer is positioned between the surface layer and the self-adhesive layer;

the raw materials of the surface layer comprise polyethylene wax, organic silicon modified polyolefin and a dendritic toughening agent.

2. The low unwinding force polyethylene low-viscosity protective film according to claim 1, wherein the surface layer comprises the following components in parts by weight:

3. the low unwind force polyethylene low adhesion protective film of claim 1 wherein said polyethylene wax is a polyethylene wax having an average molecular weight greater than 4000.

4. The low unwind force polyethylene low adhesion protective film of claim 1 wherein said silicone modified polyolefin is a silane modified amorphous a-polyolefin.

5. The low unwind force polyethylene low adhesion protective film of claim 1 wherein said dendritic toughening agent is a dendritic polymer having long segments of flexible polyolefin.

6. The low unwinding force polyethylene low adhesion protective film according to claim 1, wherein the core layer comprises the following components in parts by weight:

7. the low unwinding force polyethylene low-viscosity protective film according to claim 6, wherein the self-adhesive layer comprises the following composition in parts by weight:

10-30 parts of POE (polyolefin elastomer),

30-60 parts of an adhesive agent,

10-50 parts of a tackifier.

8. The low unwind force polyethylene low adhesion protective film of claim 7 wherein said adhesive is a SEBS linear triblock copolymer;

the tackifier is one or two of hydrogenated C5 resin, hydrogenated C9 resin and hydrogenated C5-C9 copolymer resin.

9. The low unwinding force polyethylene low-viscosity protective film according to claim 7, wherein POE in the components of the core layer and the self-adhesive layer is POE thermoplastic elastomer with the same grade.

10. The method for preparing the low-unwinding force polyethylene low-viscosity protective film according to any one of claims 1 to 9, comprising the following steps: