CN110303740B - Multilayer coextrusion biaxially oriented composite film - Google Patents
Multilayer coextrusion biaxially oriented composite film Download PDFInfo
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
- B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/34—Layered products comprising a layer of synthetic resin comprising polyamides
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
- B32B7/04—Interconnection of layers
- B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2250/00—Layers arrangement
- B32B2250/24—All layers being polymeric
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2439/00—Containers; Receptacles
Landscapes
- Shaping By String And By Release Of Stress In Plastics And The Like (AREA)
- Laminated Bodies (AREA)
Abstract
A multilayer heat-sealable co-extruded biaxially oriented composite film is characterized in that: the composite film is formed by compounding a barrier layer, a first stretching transition bridge, an adhesive layer, a second stretching transition bridge and a heat sealing layer in the thickness direction through coextrusion and biaxial stretching. Wherein the first and second stretch bridges are not zero at the same time. The first stretching transition bridge is positioned between the barrier layer and the adhesive layer, and the two-way stretching multiplying power of each transition layer material is in gradient transition between the barrier layer and the adhesive layer. The second stretching transition bridge is positioned between the heat sealing layer and the bonding layer, and the two-way stretching multiplying power of each transition layer material is in gradient transition between the heat sealing layer and the bonding layer. The forming of the film under the condition of the same biaxial stretching multiplying power is realized by reducing the interface stress between the barrier layer and the adhesive layer and between the heat sealing layer and the adhesive layer. The scheme solves the problem that the co-extrusion biaxial stretching of the non-homogeneous material cannot be realized due to large stretching multiplying power difference between the materials.
Description
Technical Field
The invention relates to a plastic packaging composite film, in particular to a multilayer coextrusion biaxially oriented composite film. The composite film can realize simultaneous coextrusion and biaxial stretching between heterogeneous materials through structural design.
Background
The composite film is a polymer material formed by compounding two or more layers of films with different materials, and is mainly used for packaging. By compounding, materials with the comprehensive properties of all the single materials can be obtained, and the base materials used mainly comprise plastic films (such as polyethylene PE, polypropylene PP, polystyrene, polyvinyl chloride PVC, polyester PET and the like), cellophane, paper, metal foil AL and the like. The substrate may be compounded by extrusion compounding or adhesive compounding with the aid of an adhesive. The multilayer coextrusion technology is different from the dry process compounding technology, and the like, so that plastic particles do not need to be made into a film-shaped intermediate product, and the multilayer coextrusion technology is more economical and environment-friendly.
Because the polar polymer compound and the nonpolar polymer compound have very different properties, the properties can complement each other, and the high-performance composite film can be prepared by the complementation of the properties of the materials of each layer, so that the multilayer coextrusion technology is commonly used for producing the high-barrier composite film. According to investigation, the multilayer coextrusion technology is widely applied to Chinese soft package production enterprises, and the application rate of 76.9% is achieved.
At present, the multilayer coextrusion technology mostly adopts different plastic coextrusion compounding, which is developed according to the principle of molecular compatibility, and only plastics with the same or similar molecular structure, such as PE/PE, PE/PP and the like, can be well bonded. If plastics with completely different molecular structures are compounded, another resin compatible with both must be introduced as an adhesion-promoting layer.
The multilayer coextrusion compounding is to extrude the same or different resin into one compounding die head simultaneously with several extruders, and the resin layers are integrated inside or outside the die head to form the composite film after extrusion compounding and cooling forming. The main characteristics of the coextrusion composition are as follows: the multilayer film is formed by one-step extrusion, the process is simple, the energy is saved, the production efficiency is high, and the cost is low; the composite film is soft and comfortable in hand feeling; the adhesive is not needed between the layers, so that the problem of residual solvent does not exist, the film has no peculiar smell, and the packaging method is suitable for packaging food and medical appliances.
There are various molding methods for plastic films, such as calendaring, casting, blow molding, stretching, etc. The biaxial stretching method is to stretch the film in two directions, namely longitudinal and transverse under the action of a certain temperature condition (higher than the glass transition temperature Tg of the resin and lower than the melting point Tm) and mechanical force, so that polymer molecules are oriented to improve the strength and transparency of the film. The film forming method can be generally classified into two major types, namely, an inflation method (bubble tube method) and a T-die film forming method (flat film method). The flat film method biaxially oriented film manufacturing device has two kinds of stretching by a two-step method and synchronous Faraday stretching. The two-step method is to carry out two stretching forming steps when producing the film, generally longitudinal stretching is carried out first, then two sides of the film are clamped by film clamps, and transverse stretching is carried out in a stenter. The synchronous method is that the plastic sheet extruded during the film production is in the same stretcher, and the longitudinal stretching and the transverse stretching are completed simultaneously.
In the actual production process, since there is a difference in properties between the amorphous polymer (heat-seal layer) and the crystalline polymer (barrier layer), the stretching method and the step are different. For amorphous polymers (heat-seal layers), they are heated above the softening point to a viscous flow state and then cooled uniformly to about the glass transition temperature suitable for stretching, and biaxially stretched at a constant or reduced temperature gradient. The crystalline polymer (barrier layer) is heated to a temperature higher than the melting point and maintained until the crystallization disappears, and is quenched to a temperature lower than the large crystallization rate and then heated to a temperature higher than the glass transition temperature (lower than the melting point) to biaxially stretch the crystalline polymer when the crystalline polymer is amorphous or almost amorphous. The difference in stretching process characteristics between the amorphous polymer and the crystalline polymer results in that the amorphous polymer and the crystalline polymer are greatly different in stretching ratio under the same stretching process conditions, and thus it is difficult to stretch simultaneously. Compared with the stretching by the synchronous method, the stretching by the two-step method is performed by firstly stretching longitudinally and then stretching transversely, and particularly, when the crystalline polymer is required to be heated to be more than the melting point for two times and kept until crystallization disappears, and is quenched to be amorphous or almost amorphous at a temperature lower than the large crystallization rate, the stretching process is performed by heating to be more than the vitrification temperature (below the melting point) more difficult.
In the industry, the biaxial stretching method is mainly used for preparing a single film, but only a multilayer homogeneous composite film can be prepared by adopting the coextrusion biaxial stretching method, and a multilayer heterogeneous composite film cannot be prepared. The multi-layer homogeneous composite film cannot have multiple functions such as blocking and heat sealing at the same time because the materials of all layers are the same. And the heterogeneous material cannot form a composite film with good performance after being subjected to coextrusion biaxial stretching. The non-homogeneous material with large stretching multiplying power has different property advantages and can improve various properties of the composite film. At present, a preparation technology for performing two-step coextrusion biaxial stretching by using two or more materials with greatly different stretching multiplying powers is not seen in the market.
Therefore, the problem that the bi-directional stretching cannot be realized after the non-homogeneous material is co-extruded in the prior art is solved, and the method has urgent practical significance and wide market prospect.
Disclosure of Invention
In view of the defects in the prior art, the invention provides a multilayer coextrusion biaxially oriented composite film, which aims to solve the problem that coextrusion biaxially oriented can not be realized due to large draw ratio difference between materials after coextrusion of non-homogeneous materials, particularly amorphous polymers and crystalline polymers.
In order to achieve the above object, the first technical scheme adopted by the invention is as follows: a multilayer coextrusion biaxially oriented composite film is characterized in that: the composite film is formed by compounding a barrier layer, a first stretching transition bridge, an adhesive layer, a second stretching transition bridge and a heat sealing layer in the thickness direction through coextrusion biaxial stretching, wherein:
the first stretching transition bridge is positioned between the barrier layer and the adhesive layer, and consists of three layers, and the two-way stretching multiplying power of each layer of material is in gradient transition between the barrier layer and the adhesive layer;
The second stretching transition bridge is positioned between the heat sealing layer and the bonding layer, and consists of two layers, and the two-way stretching multiplying power of each layer of material is in gradient transition between the heat sealing layer and the bonding layer;
the structural expression of the composite film is as follows:
(PA 6/Polyamide modifier) n/PA6/EVOH,38% ethylene content/PA 6+G21/TIE/PE +POP/PE +PP/PO
Wherein the formula is shown in sequence from left to right:
(PA 6/polyamide modifier) n represents a barrier layer composed of nylon 6 and polyamide modifier arranged crosswise; wherein, the longitudinal stretching multiplying power of nylon 6 is 3, and the transverse stretching multiplying power is 3; the polyamide modifier is composed of anhydride grafted copolymer, the longitudinal stretching multiplying power is 5, and the transverse stretching multiplying power is 6; wherein n is an integer, and the value range is 1-3;
PA6 represents a first layer in the first stretch transition bridge, the first layer being made of nylon 6, having a longitudinal stretch ratio of 3 and a transverse stretch ratio of 3.5;
EVOH,38% ethylene content represents a second layer in the first stretch transition bridge, the second layer being composed of an ethylene-vinyl alcohol copolymer having 38% ethylene content and having a longitudinal stretch ratio of 4 and a transverse stretch ratio of 4.5;
pa6+g21 represents a third layer in the first stretch transition bridge, the third layer being composed of a blend of nylon 6 and an amorphous semi-crystalline polyamide having a longitudinal stretch ratio of 5 and a transverse stretch ratio of 6;
TIE represents an adhesive layer composed of a maleic anhydride-grafted polyethylene copolymer having a longitudinal stretch ratio of 4 and a transverse stretch ratio of 6;
PE+POP represents a first layer in a second stretch transition bridge, the first layer is formed by mixing polyethylene and propylene elastomer, the longitudinal stretch ratio is 4, and the transverse stretch ratio is 6;
PE+PP represents a second layer in a second stretch transition bridge, the second layer is formed by mixing polyethylene and polypropylene, the longitudinal stretch ratio is 5, and the transverse stretch ratio is 6.5;
PO represents a heat sealing layer which is composed of polyolefin, wherein the polyolefin is polyethylene or/and polypropylene, the longitudinal stretching multiplying power range is 4-5, and the transverse stretching multiplying power range is 6-9.
In order to achieve the above purpose, the second technical scheme adopted by the invention is as follows: a multilayer coextrusion biaxially oriented composite film is characterized in that: the composite film is formed by compounding a barrier layer, an adhesive layer, a second stretching transition bridge and a heat sealing layer in the thickness direction through coextrusion biaxial stretching, wherein:
The second stretching transition bridge is positioned between the heat sealing layer and the bonding layer, and consists of two layers, and the two-way stretching multiplying power of each layer of material is in gradient transition between the heat sealing layer and the bonding layer;
the structural expression of the composite film is as follows:
(PA 6/Polyamide modifier) n/TIE/PE+POP/PE+PP/PO
Wherein the formula is shown in sequence from left to right:
(PA 6/polyamide modifier) n represents a barrier layer composed of nylon 6 and polyamide modifier arranged crosswise; wherein, the longitudinal stretching multiplying power of nylon 6 is 3, and the transverse stretching multiplying power is 3; the polyamide modifier is composed of anhydride grafted copolymer, the longitudinal stretching multiplying power is 5, and the transverse stretching multiplying power is 6; wherein n is an integer, and the value range is 1-3;
TIE represents an adhesive layer composed of a maleic anhydride-grafted polyethylene copolymer having a longitudinal stretch ratio of 4 and a transverse stretch ratio of 6;
PE+POP represents a first layer in a second stretch transition bridge, the first layer is formed by mixing polyethylene and propylene elastomer, the longitudinal stretch ratio is 4, and the transverse stretch ratio is 6;
PE+PP represents a second layer in a second stretch transition bridge, the second layer is formed by mixing polyethylene and polypropylene, the longitudinal stretch ratio is 5, and the transverse stretch ratio is 6.5;
PO represents a heat sealing layer which is composed of polyolefin, wherein the polyolefin is polyethylene or/and polypropylene, the longitudinal stretching multiplying power range is 4-5, and the transverse stretching multiplying power range is 6-9.
The relevant contents and changes of the technical scheme are explained as follows:
1. In the above scheme, in the first stretching transition bridge, the bi-directional stretching multiplying power of each layer of material is in gradient transition between the barrier layer and the adhesive layer, wherein each layer of material refers to the bi-directional stretching multiplying power of each transition layer of material before stretching, and the bi-directional stretching multiplying power of each transition layer of material is also the stretching characteristic of the material before stretching. By reducing the interface stress between the barrier layer and the adhesive layer, the film is formed under the condition of the same biaxial stretching multiplying power. Similarly, the second stretch transition bridge has the same meaning.
2. In the above scheme, the biaxial stretching ratio of each layer of material in the composite film is in an oblique line shape in a plane rectangular coordinate system, wherein the ordinate of the plane rectangular coordinate system represents the longitudinal stretching ratio, and the abscissa represents the transverse stretching ratio.
3. In the above scheme, the biaxial stretching ratio of each layer of material in the composite film is in a fold line shape in a plane rectangular coordinate system, wherein the ordinate of the plane rectangular coordinate system represents the longitudinal stretching ratio, and the abscissa represents the transverse stretching ratio.
4. In the above scheme, the biaxial stretching of the composite film is two-step stretching, longitudinal stretching is performed first, and then transverse stretching is performed.
5. In the scheme, the composite film can be heat-sealed, and the heat-sealing strength is more than or equal to 5N/15mm.
6. In the scheme, the thickness of the composite film is 10 micrometers to 100 micrometers.
7. In the above solution, the basic structure of the composite film includes a barrier layer, an adhesive layer and a heat-sealing layer, which must exist at the same time. Wherein the barrier layer is a functional layer composed of a barrier material with the functions of blocking gas, smell, moisture, grease and the like and a polyamide modifier. The barrier layers in the two technical schemes are (nylon 6/polyamide modifier) n, wherein n is an integer in the (PA 6/polyamide modifier) n, and the value range is 1-3. The (PA 6/polyamide modifier) n represents a cross arrangement of PA6 and polyamide modifier. In a first technical solution, when n=1, the film structure is PA 6/polyamide modifier/PA 6/EVOH,38% ethylene content/PA 6+ G21/TIE/PE + POP/PE + PP/PO; when n=2, the film structure is PA 6/polyamide modifier/PA 6/EVOH,38% ethylene content/PA 6+ G21/TIE/PE + POP/PE + PP/PO; when n=3, the film structure is PA 6/polyamide modifier/PA 6/EVOH,38% ethylene content/PA 6+ G21/TIE/PE + POP/PE + PP/PO. In the second variant, (PA 6/polyamide modifier) n has the same meaning. The heat seal layer is a functional layer composed of a material that can be sealed by heating and pressurizing. The heat sealing layers in the two technical schemes are all polyolefin, the polyolefin is polyethylene or/and polypropylene, the polypropylene is polypropylene copolymer, and the polyethylene and the polypropylene can be mixed in any proportion. The adhesive layer is a functional layer that adheres the barrier layer and the heat seal layer together. The adhesive layer in the two technical schemes is maleic anhydride graft copolymer.
8. In the above scheme, the polyamide modifier is a modified polymer which is functionalized (generally grafted by maleic anhydride), and comprises a modified ethylene acrylic ester carbon monoxide terpolymer, an ethylene-vinyl acetate (EVA) polymer, a grafted copolymer of polyethylene, metallocene polyethylene, ethylene propylene rubber, polypropylene and the like. The interfacial tension between two phase components is reduced by means of the bonding force between polymer molecules, so that the film structure is homogenized and the phase interface bonding is strengthened. The main function of the polyamide is to improve the ductility of the polyamide, and when the polyamide is placed between polyamide layers (such as PA 6/polyamide modifier/PA 6/polyamide modifier), the polyamide modifier plays a role of a hinge and contributes to the uniformity and the effectiveness of the whole polyamide layer when the polyamide is stretched. The polyamide modifier increases the adhesion and compatibility of the interface between the polar (polyamide) and non-polar (polyolefin) layers in the composite film structure.
9. In the scheme, the number of layers used for the second stretching transition bridge is two. The second stretching transition bridge of both technical schemes uses materials and structures of polyethylene and propylene elastomer/polyethylene and polypropylene.
10. In the above scheme, in the first technical scheme, there is a first stretching transition bridge, and the first stretching transition bridge is three layers, wherein the first layer is nylon 6, the second layer is ethylene-vinyl alcohol copolymer with 38% ethylene content, and the third layer is formed by mixing nylon 6 and amorphous semi-crystalline polyamide. In the second technical solution, the first stretching transition bridge is not present.
11. In the above solutions, the functions and materials of the barrier layer, the adhesive layer and the heat sealing layer, and the basic structure using the barrier layer, the adhesive layer and the heat sealing layer as the composite film are all known in the art, and are familiar to those skilled in the art.
12. In the above scheme, the two-step stretching method of stretching in the longitudinal direction and then stretching in the transverse direction is the prior art, and is the prior art familiar to those skilled in the art.
The design principle and the conception of the invention are as follows: in order to solve the problem that after the non-homogeneous material, in particular the amorphous polymer and the crystalline polymer are co-extruded, the co-extrusion biaxial stretching can not be realized due to the large stretching multiplying power difference between the materials. The invention adopts the technical conception that: the composite film is formed by compounding a barrier layer, a first stretching transition bridge, an adhesive layer, a second stretching transition bridge and a heat sealing layer in the thickness direction through coextrusion and biaxial stretching. The first and second stretch bridges are not zero at the same time. And a first stretching transition bridge is inserted between the barrier layer and the bonding layer, a second stretching transition bridge is inserted between the heat sealing layer and the bonding layer, and the technical means of the stretching transition bridge is utilized to enable the biaxial stretching multiplying power gradient of the barrier layer to be transited to the biaxial stretching multiplying power of the bonding layer, and the biaxial stretching multiplying power gradient of the heat sealing layer is transited to the biaxial stretching multiplying power of the bonding layer. The forming of the film under the condition of the same biaxial stretching multiplying power is realized by reducing the interface stress between the barrier layer and the adhesive layer and between the heat sealing layer and the adhesive layer. Therefore, the aim of preparing the functional composite film by adopting the coextrusion biaxial stretching method is fulfilled.
Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages and effects:
In the industry, the biaxial stretching method is mainly used for preparing a single film, but only a multilayer homogeneous composite film can be prepared by adopting the coextrusion biaxial stretching method, and a multilayer heterogeneous composite film cannot be prepared. Wherein, the multi-layer homogeneous composite film can not simultaneously have a plurality of functions such as blocking, heat sealing and the like because the materials of each layer are homogeneous. In order to reduce the difference of stretching multiplying power difference between materials, which can not be carried out simultaneously by coextrusion biaxial stretching, a flat film two-step stretching method is adopted, a first stretching transition bridge is designed between a barrier layer and an adhesive layer in a basic structure (barrier layer/adhesive layer/heat seal layer) of a functional composite film, and a second stretching transition bridge is designed between the heat seal layer and the adhesive layer. The technical means of the first stretching transition bridge and the second stretching transition bridge are adopted to realize the process transition of the barrier layer and the heat sealing layer materials with large stretching multiplying power difference in the coextrusion biaxial stretching of the heterogeneous materials, so that the difficult problem in the prior art of the industry is overcome. The invention adopts a coextrusion biaxial stretching method to prepare the functional composite film, and provides an effective technical approach for realizing the coextrusion biaxial stretching of non-homogeneous materials, in particular amorphous polymers and crystalline polymers.
Drawings
FIG. 1 is a schematic structural diagram of layers in a composite film according to example 1 of the present invention.
FIG. 2 is a schematic structural diagram of the layers in the composite film of example 2 of the present invention.
FIG. 3 is a schematic structural diagram of the layers in the composite film of example 3 of the present invention.
FIG. 4 is a schematic structural diagram of the layers in the composite film of example 4 of the present invention.
FIG. 5 is a schematic view showing the structure of each layer in the composite film of example 5 of the present invention.
FIG. 6 is a schematic structural diagram of the layers in the composite film of example 6 of the present invention.
Fig. 7 is a plane graph of biaxial stretching magnification of each layer of material in the composite film of embodiment 1 of the present invention. Wherein, the x-axis is the transverse stretching multiplying power, and the y-axis is the longitudinal stretching multiplying power.
Fig. 8 is a plane graph of biaxial stretching magnification of each layer of material in the composite film of embodiment 2 of the present invention. Wherein, the x-axis is the transverse stretching multiplying power, and the y-axis is the longitudinal stretching multiplying power.
Fig. 9 is a plane graph of biaxial stretching magnification of each layer of material in the composite film of embodiment 3 of the present invention. Wherein, the x-axis is the transverse stretching multiplying power, and the y-axis is the longitudinal stretching multiplying power.
Fig. 10 is a plane graph of biaxial stretching magnification of each layer of material in the composite film of embodiment 4 of the present invention. Wherein, the x-axis is the transverse stretching multiplying power, and the y-axis is the longitudinal stretching multiplying power.
Fig. 11 is a plane graph of biaxial stretching magnification of each layer of material in the composite film of embodiment 5 of the present invention. Wherein, the x-axis is the transverse stretching multiplying power, and the y-axis is the longitudinal stretching multiplying power.
Fig. 12 is a plane graph of biaxial stretching magnification of each layer of material in the composite film of embodiment 6 of the present invention. Wherein, the x-axis is the transverse stretching multiplying power, and the y-axis is the longitudinal stretching multiplying power.
The labels in the above figures are illustrated as follows:
in fig. 1 to 6, "PA 6/polyamide modifier" is a barrier layer, wherein "PA6" is a skin layer and "polyamide modifier" is a secondary layer.
In fig. 7 to 12, the contents in brackets appearing in the coordinate system, such as (3×4), indicate the biaxial stretching magnification of the material itself used for the point, the former "3" representing the longitudinal stretching magnification and the latter "4" representing the transverse stretching magnification. In the coordinate system, the abscissa is the lateral stretch ratio, and the ordinate is the longitudinal stretch ratio.
Detailed Description
The invention is further described below with reference to the accompanying drawings and examples:
for the sake of clarity and brevity, the following examples are described with reference to the materials referred to in the examples using their english numerals. The Chinese meanings of the related English code numbers are as follows: PA is polyamide (nylon), PA6 is nylon 6, G21 is amorphous semi-crystalline polyamide, EVOH is ethylene-vinyl alcohol copolymer, PE is polyethylene, POP is propylene elastomer, PP is polypropylene.
Example 1: multilayer coextrusion biaxially oriented composite film
As shown in fig. 1, the structural expression of the composite film is as follows:
PA 6/Polyamide modifier/PA 6/EVOH,38% ethylene content/PA 6+G21/TIE/PE+POP/PE+PP/PE
In the above formula:
the "PA 6/polyamide modifier" is a barrier layer, wherein the "PA6" is a skin layer and the "polyamide modifier" is a secondary layer.
"PA6/EVOH,38% ethylene content/PA 6+G21" is the first stretched bridge, where "PA6" is the first layer of the first stretched bridge, "EVOH,38% ethylene content" is the second layer of the first stretched bridge, and "PA6+G21" is the third layer of the first stretched bridge.
"TIE" is an adhesive layer, which in this example uses maleic anhydride grafted polyethylene copolymer.
The PE+POP/PE+PP is a second stretching transition bridge, wherein the PE+POP is a first layer of the second stretching transition bridge, and the PE+PP is a second layer of the second stretching transition bridge.
"PE" is the heat-seal layer.
The composite film can be heat-sealed, and the heat-sealing strength is more than or equal to 6N/15mm.
The biaxial stretching ratio of the material itself used for the basic functional layer in this embodiment is as follows:
the "PA 6/polyamide modifier" had a draw ratio of 3 x 4, the "TIE" had a draw ratio of 4*6, and the "PE" had a draw ratio of 4*6.
After the stretching transition bridge is inserted, the biaxial stretching multiplying power of each layer of material of the composite film is as follows:
The "PA 6/polyamide modifier" had a draw ratio of 3 x 4, a "PA6" draw ratio of about 3 x 3.5, an "EVOH,38% ethylene content" draw ratio of about 4 x 4.5, a "PA6+ G21" draw ratio of 5*6, a "TIE" draw ratio of about 4*6, a "PE + POP" draw ratio of about 4*6, a "PE + PP" draw ratio of about 5 x 6.5, and a "PE" draw ratio of about 4*6.
Referring to fig. 7, the biaxial stretching ratio of the composite film from left to right according to the structural expression is: 3*4,3*3.5,4*4.5,5*6,4*6,4*6,5*6.5,4*6.
Example 2: multilayer coextrusion biaxially oriented composite film
As shown in fig. 2, the structural expression of the composite film is as follows:
PA 6/Polyamide modifier/PA 6/EVOH,38% ethylene content/PA 6+G21/TIE/PE+POP/PE+PP/PP
In the above formula:
the "PA 6/polyamide modifier" is a barrier layer, wherein the "PA6" is a skin layer and the "polyamide modifier" is a secondary layer.
"PA6/EVOH,38% ethylene content/PA 6+G21" is the first stretched bridge, where "PA6" is the first layer of the first stretched bridge, "EVOH,38% ethylene content" is the second layer of the first stretched bridge, and "PA6+G21" is the third layer of the first stretched bridge.
"TIE" is an adhesive layer, which in this example uses maleic anhydride grafted polyethylene copolymer.
The PE+POP/PE+PP is a second stretching transition bridge, wherein the PE+POP is a first layer of the second stretching transition bridge, and the PE+PP is a second layer of the second stretching transition bridge.
"PP" is the heat seal layer.
The composite film can be heat-sealed, and the heat-sealing strength is more than or equal to 10N/15mm.
The biaxial stretching ratio of the material itself used for the basic functional layer in this embodiment is as follows:
The "PA 6/polyamide modifier" had a draw ratio of 3 x 4, the "TIE" had a draw ratio of 4*6, and the "PP" had a draw ratio of 5*9.
After the stretching transition bridge is inserted, the biaxial stretching multiplying power of each layer of material of the composite film is as follows:
The "PA 6/polyamide modifier" had a draw ratio of 3 x 4, a "PA6" draw ratio of about 3 x 3.5, an "EVOH,38% ethylene content" draw ratio of about 4 x 4.5, a "PA6+ G21" draw ratio of 5*6, a "TIE" draw ratio of about 4*6, a "PE + POP" draw ratio of about 4*6, a "PE + PP" draw ratio of about 5 x 6.5, and a "PP" draw ratio of about 5*9.
Referring to fig. 8, the biaxial stretching ratio of the composite film from left to right according to the structural expression is: 3*4,3*3.5,4*4.5,5*6,4*6,4*6,5*6.5,5*9.
Example 3: multilayer coextrusion biaxially oriented composite film
As shown in fig. 3, the structural expression of the composite film is as follows:
PA 6/Polyamide modifier/PA 6/EVOH,38% ethylene content/PA 6+G21/TIE/PE+POP/PE+PP
In the above formula:
the "PA 6/polyamide modifier" is a barrier layer, wherein the "PA6" is a skin layer and the "polyamide modifier" is a secondary layer.
"PA6/EVOH,38% ethylene content/PA 6+G21" is the first stretched bridge, where "PA6" is the first layer of the first stretched bridge, "EVOH,38% ethylene content" is the second layer of the first stretched bridge, and "PA6+G21" is the third layer of the first stretched bridge.
"TIE" is an adhesive layer, which in this example uses maleic anhydride grafted polyethylene copolymer.
The PE+POP/PE+PP is a second stretching transition bridge, wherein the PE+POP is a first layer of the second stretching transition bridge, and the PE+PP is a second layer of the second stretching transition bridge.
The PE+PP is a heat sealing layer, the PP is a copolymerized PP, and the PE and the PP can be mixed in any proportion.
The composite film can be heat-sealed, and the heat-sealing strength is more than or equal to 8N/15mm.
The biaxial stretching ratio of the material itself used for the basic functional layer in this embodiment is as follows:
the aspect ratio of the PA 6/polyamide modifier is 3 x 4, the aspect ratio of the TIE is 4*6, and the aspect ratio of the PE+PP is 4.5 x 7.5.
After the stretching transition bridge is inserted, the biaxial stretching multiplying power of each layer of material of the composite film is as follows:
The "PA 6/polyamide modifier" had a draw ratio of 3 x 4, a "PA6" draw ratio of about 3 x 3.5, an "EVOH,38% ethylene content" draw ratio of about 4 x 4.5, a "PA6+ G21" draw ratio of 5*6, a "TIE" draw ratio of about 4*6, a "PE + POP" draw ratio of about 4*6, a "PE + PP" draw ratio of about 5 x 6.5, and a "PO" draw ratio of about 4.5 x 7.5.
Referring to fig. 9, the biaxial stretching ratio of the composite film from left to right according to the structural expression is: 3*4,3*3.5,4*4.5,5*6,4*6,4*6,5*6.5,4.5*7.5.
Example 4: multilayer coextrusion biaxially oriented composite film
As shown in fig. 4, the structural expression of the composite film is as follows:
PA 6/Polyamide modifier/TIE/PE+POP/PE+PP/PE
In the above formula:
the "PA 6/polyamide modifier" is a barrier layer, wherein the "PA6" is a skin layer and the "polyamide modifier" is a secondary layer.
"TIE" is an adhesive layer, which in this example uses maleic anhydride grafted polyethylene copolymer.
The PE+POP/PE+PP is a second stretching transition bridge, wherein the PE+POP is a first layer of the second stretching transition bridge, and the PE+PP is a second layer of the second stretching transition bridge.
"PE" is the heat-seal layer.
When the polyamide modifier is used in the same material as the adhesive layer, the polyamide modifier may not be added.
The composite film can be heat-sealed, and the heat-sealing strength is more than or equal to 6N/15mm.
The biaxial stretching ratio of the material itself used for the basic functional layer in this embodiment is as follows:
the "PA 6/polyamide modifier" had a draw ratio of 3 x 4, the "TIE" had a draw ratio of 4*6, and the "PE" had a draw ratio of 4*6.
After the stretching transition bridge is inserted, the biaxial stretching multiplying power of each layer of material of the composite film is as follows:
The "PA 6/polyamide modifier" had a draw ratio of 3 x 4, the "TIE" had a draw ratio of 4*6, the "pe+pop" had a draw ratio of about 4*6, the "pe+pp" had a draw ratio of about 5 x 6.5, and the "PE" had a draw ratio of about 4*6.
Referring to fig. 10, the biaxial stretching ratio of the composite film from left to right according to the structural expression is: 3*4,4*6,4*6,5*6.5,4*6.
Example 5: multilayer coextrusion biaxially oriented composite film
As shown in fig. 5, the structural expression of the composite film is as follows:
PA 6/Polyamide modifier/TIE/PE+POP/PE+PP/PP
In the above formula:
the "PA 6/polyamide modifier" is a barrier layer, wherein the "PA6" is a skin layer and the "polyamide modifier" is a secondary layer.
"TIE" is an adhesive layer, which in this example uses maleic anhydride grafted polyethylene copolymer.
The PE+POP/PE+PP is a second stretching transition bridge, wherein the PE+POP is a first layer of the second stretching transition bridge, and the PE+PP is a second layer of the second stretching transition bridge.
"PP" is the heat seal layer.
When the polyamide modifier is used in the same material as the adhesive layer, the polyamide modifier may not be added.
The composite film can be heat-sealed, and the heat-sealing strength is more than or equal to 10N/15mm.
The biaxial stretching ratio of the material itself used for the basic functional layer in this embodiment is as follows:
The "PA 6/polyamide modifier" had a draw ratio of 3 x 4, the "TIE" had a draw ratio of 4*6, and the "PP" had a draw ratio of 5*9.
After the stretching transition bridge is inserted, the biaxial stretching multiplying power of each layer of material of the composite film is as follows:
the "PA 6/polyamide modifier" had a draw ratio of 3 x 4, the "TIE" had a draw ratio of 4*6, the "pe+pop" had a draw ratio of about 4*6, the "pe+pp" had a draw ratio of about 5 x 6.5, and the "PP" had a draw ratio of about 5*9.
Referring to fig. 11, the biaxial stretching ratio of the composite film from left to right according to the structural expression is: 3*4,4*6,4*6,5*6.5,5*9.
Example 6: multilayer coextrusion biaxially oriented composite film
As shown in fig. 6, the structural expression of the composite film is as follows:
PA 6/Polyamide modifier/TIE/PE+POP/PE+PP
In the above formula:
the "PA 6/polyamide modifier" is a barrier layer, wherein the "PA6" is a skin layer and the "polyamide modifier" is a secondary layer.
"TIE" is an adhesive layer, which in this example uses maleic anhydride grafted polyethylene copolymer.
The PE+POP/PE+PP is a second stretching transition bridge, wherein the PE+POP is a first layer of the second stretching transition bridge, and the PE+PP is a second layer of the second stretching transition bridge.
The PE+PP is a heat sealing layer, the PP is a copolymerized PP, and the PE and the PP can be mixed in any proportion.
When the polyamide modifier is used in the same material as the adhesive layer, the polyamide modifier may not be added.
The composite film can be heat-sealed, and the heat-sealing strength is more than or equal to 8N/15mm.
The biaxial stretching ratio of the material itself used for the basic functional layer in this embodiment is as follows:
the aspect ratio of the PA 6/polyamide modifier is 3 x 4, the aspect ratio of the TIE is 4*6, and the aspect ratio of the PE+PP is 4.5 x 7.5.
After the stretching transition bridge is inserted, the biaxial stretching multiplying power of each layer of material of the composite film is as follows:
the "PA 6/polyamide modifier" has a draw ratio of 3 x 4, a "TIE" draw ratio of 4*6, a "pe+pop" draw ratio of about 4*6, a "pe+pp" draw ratio of about 5 x 6.5, and a "pe+pp" draw ratio of about 4.5 x 7.5.
Referring to fig. 12, the biaxial stretching ratio of the composite film from left to right according to the structural expression is: 3*4,4*6,4*6,5*6.5,4.5*7.5.
The following description is made with respect to other embodiments and structural variations of the present invention:
In the above examples, the barrier layers of the six examples are all "PA 6/polyamide modifier", but the present invention is not limited thereto, and "PA 6/polyamide modifier/PA 6/polyamide modifier" or "PA 6/polyamide modifier/PA 6/polyamide modifier" may be used as the barrier layer. Therefore, according to the design concept and features of the present invention, the embodiments of the present invention may also be the following structural expressions: "PA 6/Polyamide modifier/PA 6/EVOH,38% ethylene content/PA 6+G21/TIE/PE+POP/PE+PP/PO", "PA 6/Polyamide modifier/PA 6/polyamide modifier/PA 6/EVOH,38% ethylene content/PA 6+G21/TIE/PE+POP/PE+PP/PO", "PA 6/polyamide modifier/TIE/PE+POP/PE+PP/PO" and "PA 6/polyamide modifier/TIE/PE+POP/PE+PP/PO". Wherein, PO is polyolefin and consists of polyethylene or/and polypropylene, and the polyethylene and the polypropylene can be mixed in any proportion. The design principle of the above four structural expressions is the same as that of the embodiment specifically described in the present invention. Wherein, when the polyamide modifier connected with the adhesive layer in the latter two structural expressions uses the same material as the adhesive layer, the polyamide modifier may not be added.
The above embodiments are provided to illustrate the technical concept and features of the present invention and are intended to enable those skilled in the art to understand the content of the present invention and implement the same, and are not intended to limit the scope of the present invention. All equivalent changes or modifications made in accordance with the spirit of the present invention should be construed to be included in the scope of the present invention.
Claims (6)
1. A multilayer coextrusion biaxially oriented composite film is characterized in that: the composite film is formed by compounding a barrier layer, a first stretching transition bridge, an adhesive layer, a second stretching transition bridge and a heat sealing layer in the thickness direction through coextrusion biaxial stretching, wherein:
the biaxial stretching of the composite film is two-step stretching, namely longitudinal stretching and transverse stretching;
the first stretching transition bridge is positioned between the barrier layer and the adhesive layer, and consists of three layers, and the two-way stretching multiplying power of each layer of material is in gradient transition between the barrier layer and the adhesive layer;
The second stretching transition bridge is positioned between the heat sealing layer and the bonding layer, and consists of two layers, and the two-way stretching multiplying power of each layer of material is in gradient transition between the heat sealing layer and the bonding layer;
the structural expression of the composite film is as follows:
(PA 6/Polyamide modifier) n/PA6/EVOH,38% ethylene content/PA 6+G21/TIE/PE +POP/PE +PP/PO
Wherein the formula is shown in sequence from left to right:
(PA 6/polyamide modifier) n represents a barrier layer composed of nylon 6 and polyamide modifier arranged crosswise; wherein, the longitudinal stretching multiplying power of nylon 6 is 3, and the transverse stretching multiplying power is 3; the polyamide modifier is composed of anhydride grafted copolymer, the longitudinal stretching multiplying power is 5, and the transverse stretching multiplying power is 6; wherein n is an integer, and the value range is 1-3;
PA6 represents a first layer in the first stretch transition bridge, the first layer being made of nylon 6, having a longitudinal stretch ratio of 3 and a transverse stretch ratio of 3.5;
EVOH,38% ethylene content represents a second layer in the first stretch transition bridge, the second layer being composed of an ethylene-vinyl alcohol copolymer having 38% ethylene content and having a longitudinal stretch ratio of 4 and a transverse stretch ratio of 4.5;
pa6+g21 represents a third layer in the first stretch transition bridge, the third layer being composed of a blend of nylon 6 and an amorphous semi-crystalline polyamide having a longitudinal stretch ratio of 5 and a transverse stretch ratio of 6;
TIE represents an adhesive layer composed of a maleic anhydride-grafted polyethylene copolymer having a longitudinal stretch ratio of 4 and a transverse stretch ratio of 6;
PE+POP represents a first layer in a second stretch transition bridge, the first layer is formed by mixing polyethylene and propylene elastomer, the longitudinal stretch ratio is 4, and the transverse stretch ratio is 6;
PE+PP represents a second layer in a second stretch transition bridge, the second layer is formed by mixing polyethylene and polypropylene, the longitudinal stretch ratio is 5, and the transverse stretch ratio is 6.5;
PO represents a heat sealing layer which is composed of polyolefin, wherein the polyolefin is polyethylene or/and polypropylene, the longitudinal stretching multiplying power range is 4-5, and the transverse stretching multiplying power range is 6-9.
2. A multilayer coextrusion biaxially oriented composite film is characterized in that: the composite film is formed by compounding a barrier layer, an adhesive layer, a second stretching transition bridge and a heat sealing layer in the thickness direction through coextrusion biaxial stretching, wherein:
the biaxial stretching of the composite film is two-step stretching, namely longitudinal stretching and transverse stretching;
The second stretching transition bridge is positioned between the heat sealing layer and the bonding layer, and consists of two layers, and the two-way stretching multiplying power of each layer of material is in gradient transition between the heat sealing layer and the bonding layer;
the structural expression of the composite film is as follows:
(PA 6/Polyamide modifier) n/TIE/PE+POP/PE+PP/PO
Wherein the formula is shown in sequence from left to right:
(PA 6/polyamide modifier) n represents a barrier layer composed of nylon 6 and polyamide modifier arranged crosswise; wherein, the longitudinal stretching multiplying power of nylon 6 is 3, and the transverse stretching multiplying power is 3; the polyamide modifier is composed of anhydride grafted copolymer, the longitudinal stretching multiplying power is 5, and the transverse stretching multiplying power is 6; wherein n is an integer, and the value range is 1-3;
TIE represents an adhesive layer composed of a maleic anhydride-grafted polyethylene copolymer having a longitudinal stretch ratio of 4 and a transverse stretch ratio of 6;
PE+POP represents a first layer in a second stretch transition bridge, the first layer is formed by mixing polyethylene and propylene elastomer, the longitudinal stretch ratio is 4, and the transverse stretch ratio is 6;
PE+PP represents a second layer in a second stretch transition bridge, the second layer is formed by mixing polyethylene and polypropylene, the longitudinal stretch ratio is 5, and the transverse stretch ratio is 6.5;
PO represents a heat sealing layer which is composed of polyolefin, wherein the polyolefin is polyethylene or/and polypropylene, the longitudinal stretching multiplying power range is 4-5, and the transverse stretching multiplying power range is 6-9.
3. The composite film according to claim 1 or 2, wherein: the biaxial stretching multiplying power of each layer of material in the composite film is in an oblique line shape in a plane rectangular coordinate system, wherein the ordinate of the plane rectangular coordinate system represents the longitudinal stretching multiplying power, and the abscissa represents the transverse stretching multiplying power.
4. The composite film according to claim 1 or 2, wherein: the two-way stretching multiplying power of each layer of material in the composite film is in a broken line shape in a plane rectangular coordinate system, wherein the ordinate of the plane rectangular coordinate system represents the longitudinal stretching multiplying power, and the abscissa represents the transverse stretching multiplying power.
5. The composite film according to claim 1 or 2, wherein: the composite film can be heat-sealed, and the heat-sealing strength is more than or equal to 5N/15mm.
6. The composite film according to claim 1 or 2, wherein: the thickness of the composite film is 10 micrometers to 100 micrometers.
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| CN211518752U (en) * | 2019-07-18 | 2020-09-18 | 江苏嘉浦特种薄膜有限公司 | Heat-sealable co-extruded biaxially oriented composite film |
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