CN114055891A

CN114055891A - Heat-shrinkable polyamide film and preparation method and application thereof

Info

Publication number: CN114055891A
Application number: CN202111247542.5A
Authority: CN
Inventors: 贾露; 李智尧; 陈曦; 颜艺林
Original assignee: Xiamen Changsu Industrial Co Ltd
Current assignee: Xiamen Changsu Industrial Co Ltd
Priority date: 2021-10-26
Filing date: 2021-10-26
Publication date: 2022-02-18
Anticipated expiration: 2041-10-26
Also published as: CN114055891B

Abstract

The invention relates to the technical field of plastic packaging materials, in particular to a heat-shrinkable polyamide film and a preparation method and application thereof. The heat-shrinkable polyamide film comprises a first polyamide surface layer, a polyamide core layer and a second polyamide surface layer; the first polyamide surface layer comprises the following components in percentage by mass: a semi-aromatic polyamide copolymer, polyamide 6, a polyamide elastomer, and an opening slipping agent; the polyamide core layer comprises a semi-aromatic polyamide copolymer, polyamide 6, a polyamide elastomer and an antistatic agent; the second polyamide surface layer comprises a semi-aromatic polyamide copolymer, polyamide 6, a polyamide elastomer and an opening slipping agent; the semi-aromatic polyamide copolymer is a polyamide 6I/6T copolymer. The heat-shrinkable polyamide film prepared by the invention has good comprehensive performance and is particularly suitable for the packaging fields of labels, electronic products and the like.

Description

Heat-shrinkable polyamide film and preparation method and application thereof

Technical Field

The invention relates to the technical field of plastic packaging materials, in particular to a heat-shrinkable polyamide film and a preparation method and application thereof.

Background

Biaxially oriented polyamide films (BOPA) have characteristics such as high tensile strength, excellent puncture resistance, and excellent gas barrier properties, pinhole resistance, transparency, printability, and other properties, and are therefore widely used in the packaging field of foods, pharmaceuticals, cosmetics, and mechatronics.

The heat-shrinkable film is mainly characterized by being stable at normal temperature, shrinking by heating (> Tg temperature or higher), and having a shrinkage rate of 70% or more in one direction. Relative to a common film: firstly, the body is transparent, and the product image is embodied; secondly, the packing materials are tightly bound, so that the scattering resistance is good; thirdly, rain, moisture and mildew are prevented; fourthly, the product has no recoverability and has certain anti-counterfeiting function. The main materials of the heat-shrinkable type film on the market at present are PVC (polyvinyl chloride), PS (polystyrene) and PETG (polyethylene terephthalate-1, 4-cyclohexanedimethanol), but there are only few reports on the heat-shrinkable polyamide film.

With the development of the scientific and technological society, the method has more and more individualized requirements on products, develops the heat shrinkable polyamide film with strong mechanics, is used for the fields of labels and electronic products, and has important significance.

Chinese patent application publication No. CN113370625A, published 2021, 09/10 discloses a heat-shrinkable high-cation polyamide co-extruded composite film and a preparation method thereof, wherein the composite film is of a sandwich structure and is sequentially provided with a first polyamide functional layer, a polyamide barrier layer and a second polyamide functional layer from top to bottom; the first polyamide functional layer and the second polyamide functional layer are composed of, by mass, 80-88.9% of polyamide, 10-15% of polycarbonate, 0.5-2% of a liquid transparent flame retardant, 0.5-2% of an antistatic agent and 0.1-1% of an opening agent; the polyamide barrier layer is composed of, by mass, 78-86.9% of polyamide 6I, 5-10% of polycarbonate, 0.1-2% of a transparent flame retardant and 5-10% of a nano material. The composite film disclosed by the invention has good heat shrinkage, optical transparency, puncture resistance and mechanical properties, and simultaneously has excellent barrier property, flame retardance and antistatic property, and fills the blank of polyamide heat shrinkage films. But the cost is higher, and the whole film is made of different materials, so that the subsequent recycling is not favorable.

Disclosure of Invention

In order to solve the problem that a BOPA film with excellent heat shrinkage performance, antistatic performance and mechanical performance is required in the packaging field of labels, electronic products and the like, the invention provides a heat-shrinkable polyamide film, which comprises a first polyamide surface layer, a polyamide core layer and a second polyamide surface layer;

the first polyamide surface layer comprises the following components in percentage by mass: a semi-aromatic polyamide copolymer, polyamide 6, a polyamide elastomer, and an opening slipping agent;

the polyamide core layer comprises a semi-aromatic polyamide copolymer, polyamide 6, a polyamide elastomer and an antistatic agent;

the second polyamide skin layer comprises a semi-aromatic polyamide copolymer, polyamide 6, a polyamide elastomer and an opening slipping agent.

In one embodiment, the first polyamide surface layer comprises, by mass, 44% to 64.9% of a semi-aromatic polyamide copolymer, 620% to 30% of polyamide, 15% to 25% of a polyamide elastomer, and 0.1% to 1% of an opening slipping agent.

The polyamide core layer comprises 43-64.5% of semi-aromatic polyamide copolymer, 620-30% of polyamide, 15-25% of polyamide elastomer and 0.5-2% of antistatic agent by mass percent.

The second polyamide surface layer comprises, by mass, 44-64.9% of a semi-aromatic polyamide copolymer, 620-30% of polyamide, 15-25% of a polyamide elastomer and 0.1-1% of an opening slipping agent.

In one embodiment, the semi-aromatic polyamide copolymer is a polyamide 6I/6T copolymer.

In one embodiment, the viscosity of the polyamide 6 is between 2.6 and 2.8.

In one embodiment, the polyamide elastomer is one or a combination of polyether copolyamide PA6-b-PEG, PA6-b-PPG and PA 6-b-PTMG.

In one embodiment, the opening slipping agent is selected from one or a combination of cross-linked silicone microspheres, Polytetrafluoroethylene (PTFE) micropowder or spherical silica.

In one embodiment, the antistatic agent is selected from one or a combination of ethoxylated amine, fatty acid ester and alkyl trimethyl ammonium ethyl lactone.

In one embodiment, the thickness of the first polyamide surface layer and the second polyamide surface layer is controlled to be 1-2 um, and the thickness of the polyamide core layer is controlled to be 10-30 um.

The present invention also provides a method for preparing the heat-shrinkable polyamide film as described in any of the above, comprising the steps of:

a1, uniformly mixing the components of each layer in proportion, extruding for granulation, drying and packaging for later use;

a2, feeding the materials prepared in A1 in proportion, melting the materials by respective extruders, uniformly flowing out through a die head, and cooling to form an unstretched sheet;

a3, biaxially stretching and heat-setting the unstretched sheet to obtain the heat-shrinkable polyamide film.

The specific steps and parameters are as follows:

and B1, uniformly mixing the components in the first polyamide surface layer, the polyamide core layer and the second polyamide surface layer in a high-speed mixer according to a certain proportion, extruding and granulating by using a double-screw extruder, drying and packaging for later use. The temperature of the extruder is 180-240 ℃, the water temperature of the water tank is 35-55 ℃, the temperature of the oven is 60-90 ℃, and the water content of the particles is less than or equal to 800 ppm.

And B2, melting the materials of the first polyamide surface layer, the polyamide core layer and the second polyamide surface layer prepared by the B1 in a feeding scale supply mode according to a proportion, uniformly flowing out through a T-shaped die after being melted by respective extruders, and cooling on a cold roll to form an unstretched sheet, wherein the temperature of the extruders is 220-260 ℃, the temperature of the cold roll is 15-35 ℃, and the thickness of the unstretched sheet is 120-400 mu m.

And B3, longitudinally stretching the unstretched sheet under a heating state, and then transversely stretching, wherein the stretching temperature is 80-110 ℃, and the stretching ratio is 2.5 x 3.0-3.0 x 4.5.

And B4, performing heat setting on the stretched film, wherein the setting temperature is 120-140 ℃, the setting time is 5-15 s, and finally obtaining the heat-shrinkable polyamide film, and the thickness of the film is 10-30 um.

Preferably, the polyamide film after stretching and shaping is packaged by adopting an aluminum foil, is subjected to aging treatment for 24 hours at the temperature of 50-70 ℃, and then is cut and packaged.

The present invention also provides a packaging material using the heat-shrinkable polyamide film as described in any of the above.

The heat-shrinkable polyamide film provided by the invention has the following beneficial effects:

1. compared with the conventional polyamide, the semi-aromatic polyamide copolymer has better heat resistance, insulativity and chemical stability, has the advantages of low water absorption rate and the like, and can enhance various performances of the composite film.

2. The polyamide 6I/6T is preferably selected from the semi-aromatic polyamide copolymer, and the polyamide 6, the polyamide 6I/6T copolymer and the polyamide elastomer are adopted for multi-element blending alloy modification, so that the composite film has good processing and forming performance, impact toughness and puncture resistance, and meanwhile, has good heat shrinkage performance and durable antistatic performance.

3. The combination of the traditional opening agent (silicon dioxide, calcium carbonate and the like) and the slipping agent (erucamide, PE wax and the like) is replaced by the opening slipping agent, so that a lower friction coefficient can be ensured, and the composite strength cannot be reduced due to the precipitation of the slipping agent.

4. The polyether copolyamide is added as a polyamide elastomer, so that the toughness of the film is improved, and the excellent lasting antistatic performance of the film is improved together with the core layer antistatic agent.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts; in the following description, the drawings are illustrated in a schematic view, and the drawings are not intended to limit the present invention.

FIG. 1 is a schematic structural view of a heat-shrinkable polyamide film provided by the present invention.

Reference numerals:

1 first polyamide skin layer 2 polyamide core layer 3 second polyamide skin layer

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments; the technical features designed in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other; all other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it is to be noted that all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs, and are not to be construed as limiting the present invention; it will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Example 1

The heat-shrinkable polyamide film is of a three-layer structure, and the structure of the film sequentially comprises a first polyamide surface layer, a polyamide core layer and a second polyamide surface layer from outside to inside;

the first polyamide surface layer comprises the following components in percentage by mass: 54.5 percent of polyamide 6I/6T copolymer, 625 percent of polyamide, 20 percent of PA6-b-PEG and 0.5 percent of organosilicon crosslinking microspheres.

The polyamide core layer comprises the following components in percentage by mass: 54% of polyamide 6I/6T copolymer, 625% of polyamide, 20% of PA6-b-PEG and 1% of fatty acid ester.

The second polyamide surface layer comprises the following components in percentage by mass: 54.5 percent of polyamide 6I/6T copolymer, 625 percent of polyamide, 20 percent of PA6-b-PEG and 0.5 percent of organosilicon crosslinking microspheres.

The preparation method comprises the following steps:

and C1, uniformly mixing the components in the first polyamide surface layer, the polyamide core layer and the second polyamide surface layer in a high-speed mixer according to the proportion, extruding and granulating through a double-screw extruder, drying and packaging for later use. The temperature of the extruder is 180-240 ℃, the water temperature of the water tank is 35-55 ℃, the temperature of the oven is 60-90 ℃, and the water content of the particles is less than or equal to 800 ppm.

And C2, melting the materials of the first polyamide surface layer, the polyamide core layer and the second polyamide surface layer prepared by C1 in a feeding scale supply mode according to a proportion, uniformly flowing out through a T-shaped die after being melted by respective extruders, and cooling on a cold roll to form an unstretched sheet, wherein the temperature of the extruders is 220-260 ℃, the temperature of the cold roll is 15-35 ℃, and the thickness of the unstretched sheet is 120-400 mu m.

And C3, longitudinally stretching the unstretched sheet under a heating state, and then transversely stretching, wherein the stretching temperature is 80-110 ℃, and the stretching ratio is 2.5 x 3.0-3.0 x 4.5.

And C4, performing heat setting on the stretched film, wherein the setting temperature is 120-140 ℃, the setting time is 5-15 s, and finally obtaining the heat-shrinkable polyamide film, and the thickness of the film is 10-30 um.

Example 2

the first polyamide surface layer comprises the following components in percentage by mass: 44% of polyamide 6I/6T copolymer, 630% of polyamide, 25% of PA6-b-PEG and 1% of organosilicon crosslinked microspheres.

The polyamide core layer comprises the following components in percentage by mass: 43% of polyamide 6I/6T copolymer, 630% of polyamide, 25% of PA6-b-PEG and 2% of fatty acid ester.

The second polyamide surface layer comprises the following components in percentage by mass: 44% of polyamide 6I/6T copolymer, 630% of polyamide, 25% of PA6-b-PEG and 1% of organosilicon crosslinked microspheres.

The preparation method is the same as that of example 1.

Example 3

the first polyamide surface layer comprises the following components in percentage by mass: 64.9 percent of polyamide 6I/6T copolymer, 620 percent of polyamide, 15 percent of PA6-b-PEG and 0.1 percent of organosilicon crosslinking microspheres.

The polyamide core layer comprises the following components in percentage by mass: 64.5 percent of polyamide 6I/6T copolymer, 620 percent of polyamide, 15 percent of PA6-b-PEG and 0.5 percent of fatty acid ester.

The second polyamide surface layer comprises the following components in percentage by mass: 64.9 percent of polyamide 6I/6T copolymer, 620 percent of polyamide, 15 percent of PA6-b-PEG and 0.1 percent of organosilicon crosslinking microspheres.

The preparation method is the same as that of example 1.

Example 4

the first polyamide surface layer comprises the following components in percentage by mass: 54.5 percent of polyamide 6I/6T copolymer, 625 percent of polyamide, 20 percent of PA6-b-PTMG and 0.5 percent of spherical silicon dioxide.

The polyamide core layer comprises the following components in percentage by mass: 54% of polyamide 6I/6T copolymer, 625% of polyamide, PA6-b-PTMG 20% and 1% of alkyl trimethyl ammonium ethyl lactone.

The second polyamide surface layer comprises the following components in percentage by mass: 54.5 percent of polyamide 6I/6T copolymer, 625 percent of polyamide, 20 percent of PA6-b-PTMG and 0.5 percent of spherical silicon dioxide.

The preparation method is the same as that of example 1.

Comparative example 1

the first polyamide surface layer comprises the following components in percentage by mass: polyamide 699.5, ordinary silica 0.5%.

The polyamide core layer comprises the following components in percentage by mass: 6100% of polyamide.

The second polyamide surface layer comprises the following components in percentage by mass: polyamide 699.5, ordinary silica 0.5%.

The preparation method is the same as that of example 1.

Comparative example 2

the first polyamide surface layer comprises the following components in percentage by mass: 99.5 percent of polyamide 6I/6T copolymer and 0.5 percent of spherical silicon dioxide.

The polyamide core layer comprises the following components in percentage by mass: 99% of polyamide 6I/6T copolymer and 1% of alkyl trimethyl ammonium ethyl lactone.

The second polyamide surface layer comprises the following components in percentage by mass: 99.5 percent of polyamide 6I/6T copolymer and 0.5 percent of spherical silicon dioxide.

The preparation method is the same as that of example 1.

Comparative example 3

the first polyamide surface layer comprises the following components in percentage by mass: 79.5 percent of polyamide 6I/6T copolymer, 20 percent of PA6-b-PTMG and 0.5 percent of organic silicon microsphere.

The polyamide core layer comprises the following components in percentage by mass: 79% of polyamide 6I/6T copolymer, 20% of PA6-b-PTMG and 1% of alkyl trimethyl ammonium ethyl lactone.

The second polyamide surface layer comprises the following components in percentage by mass: 79.5 percent of polyamide 6I/6T copolymer, 20 percent of PA6-b-PTMG and 0.5 percent of organic silicon microsphere.

The preparation method is the same as that of example 1.

Each performance test was conducted on each example and each comparative example, and the test items and the test standards are shown in Table 1, and the test results are shown in Table 2.

Table 1 test item table

TABLE 2 test results table

As can be seen from Table 2, in examples 1 to 4, compared with comparative example 1, examples 1 to 4 have excellent heat shrinkage, lower friction coefficient and surface resistance, high tensile strength, large elongation at break, and excellent performance indexes.

As can be seen from examples 1-4 and comparative example 2, the transverse heat shrinkage, the surface resistance and the strength index of comparative example 2 are all obviously reduced by only adding the polyamide 6I/6T copolymer. The polyamide elastomer not only improves the toughness of the film, but also improves the excellent lasting antistatic performance of the film together with the core layer antistatic agent. Meanwhile, the single use of the semi-aromatic polyamide copolymer for preparing the composite film can not meet the requirement.

Meanwhile, as can be seen from examples 1 to 4 and comparative example 3, in comparative example 3, the strength index is greatly reduced without adding polyamide 6, although the indexes such as the friction coefficient, the moisture absorption elongation, the transverse heat shrinkage and the surface resistance are close to those of examples 1 to 4. The modification of the polyamide 6, the polyamide 6I/6T copolymer and the polyamide elastic blending alloy is shown, so that the composite film obtains better physical properties.

In conclusion, the heat-shrinkable polyamide film prepared by the invention has excellent heat shrinkage rate, lower friction coefficient, heat shrinkage rate and surface resistance, high tensile strength, large elongation at break and better comprehensive performance, and is particularly suitable for the packaging fields of labels, electronic products and the like.

In addition, it will be appreciated by those skilled in the art that, although there may be many problems with the prior art, each embodiment or aspect of the present invention may be improved only in one or several respects, without necessarily simultaneously solving all the technical problems listed in the prior art or in the background. It will be understood by those skilled in the art that nothing in a claim should be taken as a limitation on that claim.

Although terms such as first polyamide skin layer, polyamide core layer, second polyamide skin layer, etc. are used more often herein, the possibility of using other terms is not excluded. These terms are used merely to more conveniently describe and explain the nature of the present invention; they are to be construed as being without limitation to any additional limitations that may be imposed by the spirit of the present invention; the terms "first" and "second" in the description and claims of the embodiments of the invention and the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A heat-shrinkable polyamide film characterized by: comprises a first polyamide surface layer, a polyamide core layer and a second polyamide surface layer;

2. The heat-shrinkable polyamide film according to claim 1, characterized in that: the first polyamide surface layer comprises, by mass, 44-64.9% of a semi-aromatic polyamide copolymer, 620-30% of polyamide, 15-25% of a polyamide elastomer and 0.1-1% of an opening slipping agent;

the polyamide core layer comprises 43-64.5% of semi-aromatic polyamide copolymer, 620-30% of polyamide, 15-25% of polyamide elastomer and 0.5-2% of antistatic agent by mass percent;

3. The heat-shrinkable polyamide film according to claim 1, characterized in that: the semi-aromatic polyamide copolymer is a polyamide 6I/6T copolymer.

4. The heat-shrinkable polyamide film according to claim 1, characterized in that: the viscosity of the polyamide 6 is between 2.6 and 2.8.

5. The heat-shrinkable polyamide film according to claim 1, characterized in that: the polyamide elastomer is one or a combination of polyether copolyamide PA6-b-PEG, PA6-b-PPG and PA 6-b-PTMG.

6. The heat-shrinkable polyamide film according to claim 1, characterized in that: the opening slipping agent is selected from one or a combination of cross-linked organic silicon microspheres, Polytetrafluoroethylene (PTFE) micro powder or spherical silicon dioxide.

7. The heat-shrinkable polyamide film according to claim 1, characterized in that: the antistatic agent is selected from one or a combination of ethoxylated amine, fatty acid ester and alkyl trimethyl ammonium ethyl lactone.

8. The heat-shrinkable polyamide film according to claim 1, characterized in that: the thickness of the first polyamide surface layer and the second polyamide surface layer is controlled to be 1-2 um, and the thickness of the polyamide core layer is controlled to be 10-30 um.

9. A method for producing a heat-shrinkable polyamide film according to any one of claims 1 to 8, comprising the steps of:

s1, uniformly mixing the components of each layer in proportion, extruding, granulating, drying and packaging for later use;

s2, feeding the materials prepared in the S1 according to a proportion, melting the materials through respective extruders, uniformly flowing out through a die head, and cooling to form an unstretched sheet;

and S3, biaxially stretching and heat-setting the unstretched sheet to obtain the heat-shrinkable polyamide film.

10. A packaging material comprising the heat-shrinkable polyamide film according to any one of claims 1 to 8.