CN117341314A - Three-layer co-extrusion heat shrinkage film - Google Patents

Three-layer co-extrusion heat shrinkage film Download PDF

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CN117341314A
CN117341314A CN202210735032.0A CN202210735032A CN117341314A CN 117341314 A CN117341314 A CN 117341314A CN 202210735032 A CN202210735032 A CN 202210735032A CN 117341314 A CN117341314 A CN 117341314A
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layer
polyethylene resin
density
parts
film
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Inventor
郭锐
王日辉
王群涛
李延亮
许平
高凌雁
王跃平
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China Petroleum and Chemical Corp
Qilu Petrochemical Co of Sinopec
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China Petroleum and Chemical Corp
Qilu Petrochemical Co of Sinopec
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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
    • 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
    • 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
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D65/00—Wrappers or flexible covers; Packaging materials of special type or form
    • B65D65/38—Packaging materials of special type or form
    • B65D65/40—Applications of laminates for particular packaging purposes
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/04—Oxygen-containing compounds
    • C08K5/09—Carboxylic acids; Metal salts thereof; Anhydrides thereof
    • C08K5/098—Metal salts of carboxylic acids
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
    • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L23/04—Homopolymers or copolymers of ethene
    • C08L23/06—Polyethene
    • 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
    • B32B2250/242—All polymers belonging to those covered by group B32B27/32
    • 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
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/40—Properties of the layers or laminate having particular optical properties
    • B32B2307/412—Transparent
    • 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
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/70—Other properties
    • B32B2307/732—Dimensional properties
    • B32B2307/734—Dimensional stability
    • B32B2307/736—Shrinkable
    • 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
    • B32B2553/00—Packaging equipment or accessories not otherwise provided for
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2207/00—Properties characterising the ingredient of the composition
    • C08L2207/06—Properties of polyethylene
    • C08L2207/062—HDPE

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Abstract

A three-layer co-extrusion heat-shrinkable film belongs to the technical field of three-layer co-extrusion heat-shrinkable films. The transparency of the film is improved, and the haze reducing effect can only be improved along with the thickness reduction of the film, so that the haze of the heat-shrinkable film cannot be directly reduced to improve the transparency. The three-layer co-extrusion heat shrinkage film comprises an inner layer, a middle layer and an outer layer in sequence, wherein the inner layer and the outer layer respectively contain 20-50wt% of metallocene polyethylene resin, 0.06-0.1wt% of calcium hexahydrophthalate and 50-80wt% of high-pressure polyethylene, the middle layer contains 50-99.9wt% of metallocene polyethylene resin and 0.06-0.1wt% of calcium hexahydrophthalate, and the metallocene polyethylene resin contains 0.04-0.08wt% of maleimide oxide. Under the coordination effect of maleimide oxide and calcium hexahydrophthalate, the heat shrinkage film greatly improves the transparency, reduces the haze and avoids the condition of sacrificing the thickness.

Description

Three-layer co-extrusion heat shrinkage film
Technical Field
A three-layer co-extrusion heat-shrinkable film belongs to the technical field of three-layer co-extrusion heat-shrinkable films.
Background
The heat-shrinkable film is also called a shrink film, and most polyethylene heat-shrinkable films in the previous market are processed and produced by singly using high-pressure polyethylene or blending high-density polyethylene and high-pressure polyethylene, and although the heat-shrinkable film has higher contractibility and mechanical properties, the film product is thicker, usually more than 100 mu m, and meanwhile, the transparency is poor, so that the appearance of the packaged goods is affected. With the development of the heat-shrinkable film processing technology, thinning and anti-reflection of the heat-shrinkable film become a new development trend, metallocene polyethylene gradually becomes one of the main raw materials for processing the heat-shrinkable film, the mechanical property of the heat-shrinkable film is further improved by adding metallocene polyethylene resin, the thickness of the film is reduced, but the transparency of the film is improved, the haze reducing effect can only be linearly improved along with the thickness reduction of the film, at present, the haze of the heat-shrinkable film is not directly reduced, the transparency is improved, the strength and the thickness are sacrificed to further obtain better transparency, and the application scene of the heat-shrinkable film is greatly limited.
Disclosure of Invention
The technical problems to be solved by the invention are as follows: overcomes the defects of the prior art and provides a three-layer co-extrusion heat-shrinkable film with low haze and high shrinkage capability.
The technical scheme adopted for solving the technical problems is as follows: the three-layer co-extrusion heat shrinkage film sequentially comprises an inner layer, a middle layer and an outer layer, and is characterized in that: the inner layer and the outer layer respectively contain 20-50wt% of metallocene polyethylene resin, 0.06-0.1wt% of calcium hexahydrophthalate and 20-50wt% of high-pressure polyethylene, and the middle layer contains 50-99.9wt% of metallocene polyethylene resin and 0.06-0.1wt% of calcium hexahydrophthalate;
wherein the metallocene polyethylene resin contains 0.04-0.08wt% of maleimide oxide.
In the three-layer co-extrusion heat-shrinkable film, the high-pressure polyethylene provides heat shrinkage characteristics; the metallocene polyethylene can play a role in enhancing, so that the thickness of the film is reduced while the strength is ensured, and further, the haze is reduced and the transparency is improved; the maleimide oxide is added into the metallocene polyethylene, so that the transparency of the film with the same thickness can be effectively improved, the maleimide oxide can be used for carrying out a crosslinking reaction with the polyethylene resin, the branching degree of the polyethylene resin can be effectively improved, the number of long-chain branches can be increased, the crystallinity of the resin can be reduced, and the technical effect of improving the transparency can be obtained; meanwhile, although the maleimide oxide can improve the transparency of the material, the crystallinity is reduced due to the fact that the crystallinity is reduced by improving the branching degree of the material, so that the crystallinity of the material is slightly reduced again, calcium hexahydrophthalate is added in the film production process to compensate the crystallinity of the material, the grain size is reduced, the mechanical property, particularly the tensile property, of the film can be enhanced, the transparency and the haze of the film can be further improved by reducing the grain size, and under the cooperation of the maleimide oxide and calcium hexahydrophthalate, the transparency is greatly improved, the haze is reduced and the thickness is prevented from being sacrificed by the heat-shrinkable film with the same thickness.
Preferably, the total weight of the metallocene polyethylene resin in the three-layer co-extrusion heat-shrinkable film is 40-60%.
The total content of the specific modified metallocene polyethylene resin in the heat-shrinkable film is ensured, the strength can be ensured, a sufficient amount of maleimide oxides can be provided, the crosslinking reaction with the polyethylene resin is ensured, and the high transparency of the heat-shrinkable film is obtained.
Preferably, the metallocene polyethylene resin is extruded and granulated at the temperature of 245-255 ℃.
The higher granulating temperature is set for the purpose that maleimide oxide can fully carry out crosslinking reaction with polyethylene resin, so that the branching degree of the polyethylene resin is further improved, and long-chain branches are increased, thereby reducing the crystallinity of the resin, playing a role in improving the transparency of the material, fully relying on calcium hexahydrophthalate for forming crystal grains, fully playing a synergistic effect and improving the transparency.
Further preferably, the water cooling temperature in the extrusion granulation process is 45-55 ℃. So that the polyethylene can keep stable and good crystal form.
Further preferably, the obtained granules are subjected to heat preservation for 2-4 hours at the temperature of 85 ℃ after extrusion and granulation.
Because the residence time of the resin in the granulator is short, the crosslinking reaction can be further carried out, so that the granulated resin is required to be kept at a constant temperature of 85 ℃ for 2-4 hours, and the branching degree and the long-chain branch content of the resin are further improved. In addition, the increase of the branching degree and the content of the long-chain branched chain, especially the long-chain branched chain can improve the heat shrinkage rate of the film.
Preferably, the inner layer and the outer layer respectively comprise 10-40 wt% of high-density polyethylene resin.
The high-density polyethylene resin can provide better mechanical properties including tensile strength, tear resistance and the like, but if the high-density polyethylene resin is excessive, the high-density polyethylene resin can cause crystal orientation and is easy to tear longitudinally, and the three-layer co-extrusion heat-shrinkable film prepared by the preferable dosage has higher mechanical properties.
Preferably, the metallocene polyethylene resin composition further comprises 90-99.9wt% of a medium-density metallocene polyethylene resin.
The metallocene polyethylene resin adopts the medium density metallocene polyethylene, so that the rigidity and toughness balance of the material can be considered, and the better tensile property and tear resistance can be kept.
Further preferably, the medium-density metallocene polyethylene resin is a copolymer of ethylene and 1-hexene, the density is 0.934-0.938 g/cm < 3 >, and the mass flow rate of 2.16kg melt is 0.4-0.8 g/10min.
Preferably, the metallocene polyethylene resin further comprises 0.06-0.22wt% of an antioxidant and 0.04-0.08wt% of an acid absorber.
The antioxidant is preferably a compound composition of hindered phenol antioxidants and phosphite antioxidants; the content of the hindered phenol antioxidant is 0.03-0.1wt%, preferably 0.05-0.06wt%, and the hindered phenol antioxidant is preferably 1010 or 1076, and most preferably 1076; the content of the phosphite antioxidant is 0.03-0.12wt%, preferably 0.05-0.06wt%, and the phosphite antioxidant is preferably 628.
The acid absorber is preferably 0.05. 0.05 wt% and is zinc stearate or calcium stearate, preferably zinc stearate.
Preferably, the maleimide oxide is 4-maleimide-tetramethylpiperidine oxide.
Compared with the prior art, the invention has the following beneficial effects: in the three-layer co-extrusion heat-shrinkable film, the high-pressure polyethylene provides heat shrinkage characteristics; the metallocene polyethylene can play a role in enhancing, so that the thickness of the film is reduced while the strength is ensured, and further, the haze is reduced and the transparency is improved; the maleimide oxide is added into the metallocene polyethylene, so that the transparency of the film with the same thickness can be effectively improved, the maleimide oxide can be used for carrying out a crosslinking reaction with the polyethylene resin, the branching degree of the polyethylene resin can be effectively improved, the number of long-chain branches can be increased, the crystallinity of the resin can be reduced, and the technical effect of improving the transparency can be obtained; meanwhile, although the maleimide oxide can improve the transparency of the material, the crystallinity is reduced due to the improvement of the branching degree of the material, so that the stretching of the material is slightly reduced, and in order to improve the crystallinity of the material again, calcium hexahydrophthalate is added in the film production process, so that the crystallinity of the material can be compensated, the grain size is reduced, the mechanical property, particularly the tensile property, of the film can be enhanced, the transparency of the film can be further improved, the haze is reduced, and under the cooperation of the maleimide oxide and calcium hexahydrophthalate, the transparency is greatly improved, the haze is reduced, and the thickness sacrificing condition is avoided by the heat-shrinkable film with the same thickness; in addition, in practical application experiments of the invention, the heat-shrinkable film obtained by the means can be seen to obtain better performance improvement in terms of shrinkage rate, in particular to improve transverse shrinkage rate.
Detailed Description
The present invention will be further described with reference to the following examples, with example 1 being the best mode of carrying out the invention.
Example 1
The three-layer co-extrusion heat shrinkage film sequentially comprises an inner layer, a middle layer and an outer layer, wherein the formula of each layer comprises the following components:
an inner layer: 30 parts of metallocene polyethylene resin mPE and high-density polyethylene resin HDPE (density 0.950 g/cm) 3 ，MFR 21.6 10g/10 min) 30 parts, a high pressure polyethylene resin LDPE (density 0.924 g/cm) 3 ，MFR 2.16 0.8g/10 min) 40 parts, calcium hexahydrophthalate 0.06 parts.
Middle layer: 100 parts of mPE and 0.06 part of calcium hexahydrophthalate.
An outer layer: 30 parts of mPE, HDPE (density 0.950 g/cm) 3 30 parts of LDPE (density 0.924 g/cm) with MFR21.6 of 10g/10min 3 MFR2.16 at 0.8g/10 min) 40 parts, calcium hexahydrophthalate 0.06 parts.
Wherein the metallocene polyethylene resin comprises the following components: 100 parts of medium-density metallocene polyethylene with the density of 0.935g/cm 3 ，MFR 2.16 0.5g/10min, a copolymer of ethylene and 1-hexene, 0.05 part of antioxidant 1076, 0.05 part of antioxidant 628, 0.05 part of zinc stearate and 0.05 part of 4-maleimide-tetramethylpiperidine oxide.
The preparation method of the metallocene polyethylene tree comprises the following steps: gao Jiaohun and granulating by a double screw extruder with length-diameter ratio of 50 at 250 deg.C, extruding and granulating, cooling with cooling water at 50deg.C, and oven-maintaining at 85deg.C for 3 hr.
Example 2
The three-layer co-extrusion heat shrinkage film sequentially comprises an inner layer, a middle layer and an outer layer, wherein the formula of each layer comprises the following components:
an inner layer: mPE 50 parts, HDPE (density0.950g/cm 3 ，MFR 21.6 25 parts of LDPE (density 0.924 g/cm) 3 ，MFR 2.16 0.8g/10 min) 25 parts, 0.06 parts of calcium hexahydrophthalate.
Middle layer: 60 parts of mPE, HDPE (density 0.950 g/cm) 3 ，MFR 21.6 20 parts of LDPE (density 0.924 g/cm) 3 ，MFR 2.16 0.8g/10 min) 20 parts, 0.06 parts of calcium hexahydrophthalate.
An outer layer: 50 parts of mPE, HDPE (density 0.950g/cm 3 ，MFR 21.6 25 parts of LDPE (density 0.924 g/cm) 3 ，MFR 2.16 0.8g/10 min) 25 parts, 0.06 parts of calcium hexahydrophthalate.
Other conditions such as metallocene formulation composition and preparation method are the same as in example 1.
Example 3
A three-layer co-extrusion heat-shrinkable film is prepared by adopting 245 ℃ for extrusion granulation in a metallocene polyethylene tree preparation method based on the example 1, and other conditions are the same as in the example 1.
Example 4
A three-layer co-extrusion heat-shrinkable film is prepared by adopting 255 ℃ for extrusion granulation in a metallocene polyethylene tree preparation method based on the example 1, and other conditions are the same as the example 1.
Example 5
Based on the example 1, the extrusion granulating temperature in the preparation method of the metallocene polyethylene tree is 240 ℃, and other conditions are the same as in the example 1.
Example 6
Based on the example 1, the extrusion granulating temperature in the preparation method of the metallocene polyethylene tree is 260 ℃, and other conditions are the same as in the example 1.
Example 7
A three-layer co-extrusion heat-shrinkable film is prepared by the method for preparing metallocene polyethylene tree based on the example 1, wherein the extrusion granulation is cooled down by water cooling, and then the film is naturally cooled without heat preservation, and other conditions are the same as the example 1.
Example 8
A three-layer co-extrusion heat-shrinkable film is prepared by adopting the preparation method of metallocene polyethylene tree, wherein the temperature of the extrusion granulation, water cooling and heat preservation is set to 80 ℃ based on the embodiment 1, and other conditions are the same as the embodiment 1.
Comparative example 1
The three-layer co-extrusion heat shrinkage film sequentially comprises an inner layer, a middle layer and an outer layer, wherein the formula of each layer comprises the following components:
an inner layer: 30 parts of mPE, HDPE (density 0.950 g/cm) 3 ，MFR 21.6 30 parts of LDPE (density 0.924 g/cm) 3 ，MFR 2.16 0.8g/10 min) 40 parts.
Middle layer: 100 parts of mPE.
An outer layer: 30 parts of mPE, HDPE (density 0.950 g/cm) 3 ，MFR 21.6 30 parts of LDPE (density 0.924 g/cm) 3 ，MFR 2.16 0.8g/10 min) 40 parts.
The metallocene polyethylene resin has the same formula, preparation method and other conditions as those of the example 1.
Comparative example 2
A three-layer co-extrusion heat-shrinkable film was obtained by copolymerizing ethylene and 1-hexene as the metallocene polyethylene resin based on example 1 (density 0.935 g/cm) 3 ，MFR 2.16 0.6g/10 min), the modification of 4-maleimide-tetramethylpiperidine oxide was not performed, and the other conditions were the same as in example 1.
Comparative example 3
A three-layer co-extrusion heat-shrinkable film was prepared on the basis of comparative example 2, wherein no calcium hexahydrophthalate was added to each of the inner layer, the middle layer and the outer layer, and the other conditions were the same as those of comparative example 2.
Comparative example 4
On the basis of comparative example 2, the formulation of each layer was set as follows:
an inner layer: medium density metallocene ethylene (density 0.935 g/cm) 3 ，MFR 2.16 0.5g/10 min) 50 parts, HDPE (density 0.946g/cm 3 ，MFR 21.6 10g/10min) 25 parts of LDPE (density 0.920 g/cm) 3 ，MFR 2.16 1.9g/10 min) 25 parts.
Middle layer: medium density metallocene ethylene (density 0.935 g/cm) 3 ，MFR 2.16 60 parts of HDPE (density 0.946 g/cm) 3 ，MFR 21.6 20 parts of LDPE (density 0.920 g/cm) 3 ，MFR 2.16 1.9g/10 min) 20 parts.
An outer layer: medium density metallocene ethylene (density 0.935 g/cm) 3 ，MFR 2.16 0.5g/10 min) 50 parts, HDPE (density 0.946g/cm 3 ，MFR 21.6 25 parts of LDPE (density 0.920 g/cm) 3 ，MFR 2.16 1.9g/10 min) 25 parts.
Other conditions were the same as in comparative example 2.
Comparative example 5
On the basis of comparative example 2, the formulation of each layer was set as follows:
an inner layer: medium density metallocene ethylene (density 0.935 g/cm) 3 ，MFR 2.16 33 parts of HDPE (density 0.950 g/cm) 3 ，MFR 21.6 33 parts of LDPE (density 0.920 g/cm) 3 ，MFR 2.16 0.8g/10 min) 33 parts.
Middle layer: medium density metallocene ethylene (density 0.935 g/cm) 3 ，MFR 2.16 80 parts of LDPE (density 0.920 g/cm) 3 ，MFR 2.16 0.8g/10 min) 20 parts.
An outer layer: medium density metallocene ethylene (density 0.935 g/cm) 3 ，MFR 2.16 33 parts of HDPE (density 0.950 g/cm) 3 ，MFR 21.6 33 parts of LDPE (density 0.920 g/cm) 3 ，MFR 2.16 0.8g/10 min) 33 parts.
Other conditions were the same as in comparative example 2.
Comparative example 6
On the basis of comparative example 2, the formulation of each layer was set as follows:
an inner layer: medium density metalloceneEthylene (density 0.935 g/cm) 3 ，MFR 2.16 0.5g/10 min) 50 parts, HDPE (density 0.946g/cm 3 ，MFR 21.6 25 parts of LDPE (density 0.920 g/cm) 3 ，MFR 2.16 0.8g/10 min) 25 parts.
Middle layer: medium density metallocene ethylene (density 0.935 g/cm) 3 ，MFR 2.16 0.5g/10 min) 50 parts, HDPE (density 0.946g/cm 3 ，MFR 21.6 25 parts of LDPE (density 0.920 g/cm) 3 ，MFR 2.16 0.8g/10 min) 25 parts.
An outer layer: medium density metallocene ethylene (density 0.935 g/cm) 3 ，MFR 2.16 0.5g/10 min) 50 parts, HDPE (density 0.946g/cm 3 ，MFR 21.6 25 parts of LDPE (density 0.920 g/cm) 3 ，MFR 2.16 0.8g/10 min) 25 parts.
Other conditions were the same as in comparative example 2.
Comparative example 7
On the basis of the embodiment 1, the formula composition of each layer of the inner layer, the middle layer and the outer layer is as follows:
an inner layer: 10 parts of metallocene polyethylene resin mPE and high-density polyethylene resin HDPE (density 0.950 g/cm) 3 ，MFR 21.6 10g/10 min) 30 parts, a high pressure polyethylene resin LDPE (density 0.924 g/cm) 3 ，MFR 2.16 0.8g/10 min) 60 parts, 0.06 parts of calcium hexahydrophthalate.
Middle layer: 100 parts of mPE and 0.06 part of calcium hexahydrophthalate.
An outer layer: 10 parts of mPE, HDPE (density 0.950g/cm 3 30 parts of LDPE (density 0.924 g/cm) with MFR21.6 of 10g/10min 3 MFR2.16 at 0.8g/10 min) 60 parts, calcium hexahydrophthalate 0.06 parts.
Other conditions such as metallocene formulation composition and preparation method are the same as in example 1.
Comparative example 8
On the basis of the embodiment 1, the formula composition of each layer of the inner layer, the middle layer and the outer layer is as follows:
an inner layer: 50 parts of mPE, HDPE (density 0.950g/cm 3 ，MFR 21.6 25 parts of LDPE (density 0.924 g/cm) 3 ，MFR 2.16 0.8g/10 min) 25 parts, 0.06 parts of calcium hexahydrophthalate.
Middle layer: 40 parts of mPE, HDPE (density 0.950 g/cm) 3 ，MFR 21.6 30 parts of LDPE (density 0.924 g/cm) 3 ，MFR 2.16 0.8g/10 min) 30 parts, calcium hexahydrophthalate 0.06 parts.
An outer layer: 50 parts of mPE, HDPE (density 0.950g/cm 3 ，MFR 21.6 25 parts of LDPE (density 0.924 g/cm) 3 ，MFR 2.16 0.8g/10 min) 25 parts, 0.06 parts of calcium hexahydrophthalate.
Other conditions such as metallocene formulation composition and preparation method are the same as in example 1.
Comparative example 9
A three-layer co-extrusion heat-shrinkable film was prepared in which the calcium hexahydrophthalate content of each of the inner layer, the middle layer and the outer layer was set to 0.05 parts based on example 1, and the other conditions were the same as in example 1.
Performance testing
Performance tests were performed on the three-layer coextruded heat shrink films obtained in examples and comparative examples, wherein:
film tensile properties: the stretching speed is 200mm/min according to GB/T1040.3-2006.
Tear resistance of the film: according to GB/T16578.2-2009.
Haze: according to GB/T2410-2008.
Shrinkage ratio: cutting the film into square sheets with the size of 10cm by 10cm, soaking the square sheets in an oil bath at 130 ℃ for 20 seconds, taking out the square sheets, testing the residual width and the length, and subtracting the initial length to calculate the shrinkage rate.
The final test results are shown in tables 1 and 2 below.
Table 1 example performance test results
。
Table 2 comparative example performance test results
。
According to the experimental results of examples 3-8, it can be seen that the transparency of the heat shrinkable film can be further effectively improved by using the specific high-temperature extrusion in combination with heat preservation. According to the experimental results of comparative examples 4 to 6, it was found that in the case where the modified metallocene polyethylene resin was not used in combination with calcium hexahydrophthalate, the haze of the final heat-shrinkable film could not be effectively reduced and the transparency could not be improved regardless of the adjustment of the metallocene polyethylene resin, the high-density polyethylene resin and the high-pressure polyethylene resin. According to the experimental results of comparative examples 7 to 8, it was found that the transparency of the heat-shrinkable film could not be effectively improved even when the content of the modified metallocene polyethylene resin in each layer did not reach reasonable and uniform dispersion. Comparative example 9 demonstrates that the compounding relationship of calcium hexahydrophthalate and metallocene polyethylene resin has a certain amount of requirement, and the synergistic effect can be effectively exerted only near 0.06 wt%.
In addition, from the performance test results, the heat-shrinkable film prepared by the method of the invention also has obviously improved shrinkage, especially transverse shrinkage.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the invention in any way, and any person skilled in the art may make modifications or alterations to the disclosed technical content to the equivalent embodiments. However, any simple modification, equivalent variation and variation of the above embodiments according to the technical substance of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims (10)

1. The three-layer co-extrusion heat shrinkage film sequentially comprises an inner layer, a middle layer and an outer layer, and is characterized in that: the inner layer and the outer layer respectively contain 20-50wt% of metallocene polyethylene resin, 0.06-0.1wt% of calcium hexahydrophthalate and 20-50wt% of high-pressure polyethylene, and the middle layer contains 50-99.9wt% of metallocene polyethylene resin and 0.06-0.1wt% of calcium hexahydrophthalate;
wherein the metallocene polyethylene resin contains 0.04-0.08wt% of maleimide oxide.
2. The three-layer coextruded heat shrink film of claim 1 wherein: the total weight of the metallocene polyethylene resin in the three-layer co-extrusion heat-shrinkable film is 40-60%.
3. The three-layer coextruded heat shrink film of claim 1 wherein: and extruding and granulating the metallocene polyethylene resin at 245-255 ℃.
4. A three layer coextruded heat shrink film as claimed in claim 3 wherein: the water cooling temperature in the extrusion granulating process is 45-55 ℃.
5. A three layer coextruded heat shrink film as claimed in claim 3 wherein: and (3) carrying out extrusion granulation to obtain granules, and carrying out heat preservation at the temperature of 85 ℃ for 2-4 hours.
6. The three-layer coextruded heat shrink film of claim 1 wherein: the inner layer and the outer layer respectively comprise 10-40wt% of high-density polyethylene resin.
7. The three-layer coextruded heat shrink film of claim 1 wherein: the metallocene polyethylene resin composition also comprises 90-99.9wt% of medium-density metallocene polyethylene resin.
8. The three layer coextruded heat shrink film of claim 7 wherein: the medium density metallocene polyethylene resin is a copolymer of ethylene and 1-hexene, and the density is 0.934-0.938 g/cm 3 2.16kg melt mass flow rate is 0.4-0.8 g/10min.
9. The three-layer coextruded heat shrink film of claim 1 wherein: the metallocene polyethylene resin also comprises 0.06-0.22wt% of an antioxidant and 0.04-0.08wt% of an acid absorber.
10. The three-layer coextruded heat shrink film of claim 1 wherein: the maleimide oxide is 4-maleimide-tetramethylpiperidine oxide.
CN202210735032.0A 2022-06-27 2022-06-27 Three-layer co-extrusion heat shrinkage film Pending CN117341314A (en)

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