JPH09169087A - Laminated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve extremely a low temperature heat sealing characteristics (extrusion moldability, drawdown property, neck-in, heat resistance, hot tack property, and heat-sealing strength). SOLUTION: An ethylene resin composition composed of 100 pts.wt. of straight chain low density ethylene/α-olefin copolymer manufactured by using a Ziegler catalyst or a Phillips catalyst, 30-70 pts.wt. of ethylene/α-olefin copolymer manufactured by using a single site catalyst, and 50-100 pts.wt. high pressure method low density polyethylene, is extruded on a base material film of a single layer or a plurality of layers which contain a polyamide, a polyester, polyvinyliden chloride, an ethylene/vinylalcohol copolymer or aluminum as the base material, and the base film is coated with the ethylene resin composition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated film, and more specifically, it is used for food packaging, which is excellent in extrusion coating processability during film production, and which is excellent in heat resistance, low temperature heat sealability and hot tackiness. The present invention relates to a laminated film suitable as.

[0002]

2. Description of the Related Art As a food packaging material, a gas barrier material such as an ethylene-vinyl alcohol copolymer has been used for the purpose of preventing invasion of oxygen gas which deteriorates food, and various foods can be stored for a long period of time. It is possible. In general, gas barrier materials are difficult to heat seal,
A laminated film in which a polyethylene resin having an easily heat-sealing property is extrusion coated on the gas barrier layer is used.
Conventionally, as such a polyethylene resin, a high-pressure method low-density polyethylene having a good drawdown property and a small neck-in has been used, but the high-pressure method low-density polyethylene has low heat resistance and cannot be sterilized by boiling. Hot tack property (also called hot seal property, if this property is inferior, the seal part peels off when the contents are filled immediately after heat sealing) is insufficient, and when filling heavy items Had drawbacks such as insufficient heat seal strength. In order to improve these drawbacks, a linear low-density ethylene-α-olefin copolymerization produced by using a Ziegler-based catalyst or a Phillips-based catalyst instead of the above high-pressure low-density polyethylene as an extrusion coating resin. Although the use of a coalesced product was investigated, extrusion coating with the copolymer alone had drawbacks such as an extremely high extrusion load, a surging phenomenon during extrusion, and a large neck-in. For this reason, the present situation is to extrusion coat the compounded composition of the linear low-density ethylene-α-olefin copolymer and the high-pressure low-density polyethylene.

[0003]

[Problems to be Solved by the Invention] However, since automatic filling and packaging of food packaging films have become more popular recently, and the speeding up of processing has progressed, reliable heat sealing at low temperatures, that is, low temperature heat A laminated film excellent in sealing property has been demanded, but a gas barrier layer is extrusion-coated with a compounded composition of the linear low-density ethylene-α-olefin copolymer and the high-pressure low-density polyethylene. So, we are not able to meet that request. Therefore, the present invention, good extrusion processability, drawdown property, neck-in, which are excellent properties of the prior art,
It is an object to provide a laminated film in which a gas barrier layer is extrusion-coated with an ethylene-based resin that has improved the low-temperature heat-sealing property, which has been a conventional problem, while maintaining heat resistance, hot tack property, heat sealing strength, and the like. And

[0004]

Means for Solving the Problems The present inventors have selected various resins and confirmed by experiments. As a result, the linear low-density ethylene-α-olefin copolymer and the high-pressure low-density polyethylene It was found that the above-mentioned problems can be solved by further adding an ethylene-α-olefin copolymer produced by using a single-site catalyst to the compounding composition of No. 1, and further studies have been made, which is required for a laminated film. The present invention has been completed by finding out a specific blending ratio of the above three components capable of exhibiting excellent performance.

That is, the present invention comprises 100 parts by weight of a linear low density ethylene-α-olefin copolymer produced by using a Ziegler type catalyst or a Phillips type catalyst,
Ethylene-α produced using a single-site catalyst
-An ethylene resin composition comprising 30 to 70 parts by weight of an olefin copolymer and 50 to 100 parts by weight of a high-pressure low density polyethylene, a polyamide resin, a polyester resin, a polyvinylidene chloride resin, an ethylene-vinyl alcohol copolymer resin, and The present invention relates to a laminated film formed by extrusion coating on a single-layer or multi-layer base film made of at least one selected from the group consisting of aluminum.

A linear low-density ethylene-α-olefin copolymer (hereinafter referred to as L) produced by using the Ziegler type catalyst or Phillips type catalyst used in the present invention.
(Also referred to as LDPE) is a copolymer of ethylene and an α-olefin, for example, an α-olefin having 3 to 12 carbon atoms, which is produced using any of the above catalysts. Specific examples of α-olefins include propylene,
Butene-1, hexene-1, 4-methylpentene-1,
Octene-1, decene-1, dodecene-1 etc. can be mentioned.

One of the catalysts used in the production of LLDPE is called Ziegler type catalyst, which is a main catalyst composed of transition metal compounds such as titanium compounds and vanadium compounds,
A catalyst composed of a co-catalyst composed of an organometallic compound such as organoaluminum and a catalyst carrier composed of an oxide or chloride such as silicon, titanium, or magnesium. The other catalyst is called a Phillips catalyst and is composed of a main catalyst made of chromium oxide and a catalyst carrier made of oxides of silicon, aluminum and the like.

For the polymerization of LLDPE, a solution polymerization method, a suspension polymerization method, a slurry polymerization method, a gas phase polymerization method or the like can be used. The temperature during the polymerization is 0-2
50 ° C., pressure is high pressure (50 MPa or more), medium pressure (10 to 50 MPa) or low pressure (normal pressure to 10 MPa)
It is.

The LLDPE used in the present invention preferably has the following physical properties: melt flow rate 1 to 20 g / 10 min and density 0.91 to 0.93 g / cm ³ . Here, the melt flow rate is JIS K72.
Measured in accordance with 10, it is not preferable that the amount is less than 1 g / 10 minutes because the motor load of the extruder is excessively applied during extrusion coating, and if it exceeds 20 g / 10 minutes, the heat-sealing property is deteriorated. Moreover, the density is measured according to JIS K7112 and is 0.91 g.
If it is less than / cm ^3, it is not preferable because heat resistance is poor.
If it exceeds 0.93 g / cm ³ , the heat-sealing property is deteriorated, which is not preferable.

The ethylene-α-olefin copolymer (hereinafter also referred to as SSC-PE) produced by using the single-site catalyst used in the present invention is mixed with ethylene produced by using the above catalyst. It is a copolymer with an α-olefin, for example, an α-olefin having 3 to 12 carbon atoms. Specific examples of the α-olefin include propylene, butene-1, hexene-1, 4-methylpentene-1, octene-1, decene-1, dodecene-1, and the like. Among these, octene-1 is particularly preferable in terms of mechanical properties and workability.

The above SSC-PE has the following physical properties: melt flow rate 1 to 20 g / 10 minutes, density 0.88 to 0.9.
Those having ³ g / cm ³ and a ratio (Mw / Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn) of 3.0 or less are preferable. Here, the melt flow rate is JIS
It is measured according to K7210, and when it is less than 1 g / 10 minutes, it is not preferable because it is inferior in extrudability.
If it exceeds 0 minutes, mechanical properties are deteriorated, which is not preferable. The density is measured according to JIS K7112,
If it is less than 0.88 g / cm ^3, it is not preferable because it is inferior in heat resistance, and if it exceeds 0.93 g / cm ³ , it is not preferable because it is inferior in heat sealing property. Furthermore, the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) (Mw / Mn)
Is measured by size exclusion chromatography,
It is preferably 3.0 or less, and particularly preferably 2.5 or less. When Mw / Mn exceeds 3.0, mechanical properties are deteriorated, which is not preferable. This Mw / Mn is a value that serves as an index of the molecular weight distribution, and the smaller the value, the smaller the molecular weight distribution.

The single-site catalyst used in the production of SSC-PE has the same kind of active sites (single site) and has a high polymerization activity for ethylene. This single-site catalyst is a metallocene catalyst,
It is also called Kaminsky catalyst from the inventor's name.
The catalyst used in the present invention is a further improvement thereof, for example, a catalyst having an appropriately constrained geometrical shape.
(Constrained Geometry Catalysts), Periodic Table No. 3 ~ 1
What contains a metal coordination complex containing a group 0 or lanthanoid (lanthanum series) metal atom and an atomic group having a delocalized π (pi) bond substituted with an atomic group that induces binding preferable. A preferred catalyst complex has the formula:

Embedded image (In the formula, M is a metal atom of Group 3 to 10 of the periodic table or a lanthanoid, and Cp * is a cyclopentadienyl group or a substituted cyclopentadienyl group bonded to M in a η ⁵ bond mode, Z is an atomic group containing boron or an element of Group 14 of the periodic table, and optionally a sulfur atom or an oxygen atom, the atomic group having up to 20 atoms other than hydrogen atom, or Cp * And Z together form a fused ring system, X independently of one another is an anionic ligand or a neutral Lewis base ligand having up to 30 atoms other than hydrogen atoms and n is 0 1, 2, 3 or 4 and 2 less than the valence of M,
And Y is an anionic or non-anionic ligand that binds to Z and M, contains a nitrogen, phosphorus, oxygen or sulfur atom and has up to 20 atoms other than hydrogen. , Or optionally Y and Z together form a fused ring system).

Specific compounds of the above catalyst complex include
(Tertiary butylamide) (tetramethyl-η ⁵ -cyclopentadienyl) -1,2-ethanediyl zirconium dichloride, (tertiary butylamide) (tetramethyl-η
⁵ -cyclopentadienyl) -1,2-ethanediyl titanium dichloride, (methylamide) (tetramethyl-
η ⁵ -Cyclopentadienyl) -1,2-ethanediylzirconium dichloride, (methylamide) (tetramethyl-η ⁵ -cyclopentadienyl) -1,2-ethanediyltitanium dichloride, (ethylamide) (tetramethyl- η ⁵ -cyclopentadienyl) methylene titanium dichloride, (tertiary butylamido) dibenzyl (tetramethyl-η ⁵ -cyclopentadienyl) silane zirconium dibenzyl, (benzylamido) dimethyl (tetramethyl-η ⁵ -cyclopentadiene (Phenyl) silane titanium dichloride, (phenylphosphide) dimethyl (tetramethyl-η ⁵ -cyclopentadienyl) silane zirconium dibenzyl, (tertiary butylamido) dimethyl (tetramethyl-η ⁵ -cyclopentadienyl) silane titanium dimethyl Etc. are examples It is.

The catalyst further contains an activating cocatalyst. As the cocatalyst, an aluminoxane having a high degree of polymerization or a low degree of polymerization, particularly methylaluminoxane is suitable. So-called modified methylaluminoxane is also suitable for use as the cocatalyst.

The polymerization of SSC-PE in the present invention is preferably carried out by a solution polymerization method, and the conditions for a usual solution polymerization method can be directly adopted. That is, the polymerization temperature is 0 to 250 ° C., and the polymerization pressure is from normal pressure to 100 MP.
a. If necessary, the polymerization can be carried out according to a suspension method, a slurry method, a gas phase method or another method. Although a carrier can be used, preferably the catalyst is used in a homogeneous (eg soluble) state. Of course, when the catalyst component and its cocatalyst component are added directly to the polymerization process and a suitable solvent or diluent (including concentrated monomer) is used in the polymerization process, an active catalyst system is formed in the reactor. Is preferred. However, the active catalyst may be formed in a separate step in a suitable solvent prior to its addition to the polymerization mixture, which method is also preferred. The details of the production method of this SSC-PE are described in JP-A-6-306121 and JP-A-7-500622.

The SSC-PE in the present invention contains 0.01 to 3 long chain branches per 1000 carbon atoms in the main chain. Since SSC-PE contains this long chain branch, it has a small molecular weight distribution,
Good extrudability and low temperature heat sealability. A small molecular weight distribution means excellent mechanical properties. Conventional linear low density ethylene-α-
In the compounded composition of the olefin copolymer and the high-pressure low-density polyethylene, good mechanical properties, good processability, and low-temperature heat sealability could not be achieved at the same time. However, in the present invention, by further adding SSC-PE, , It is possible to achieve both of these.

The high-pressure low density polyethylene (hereinafter also referred to as HP-LDPE) used in the present invention is
Reaction temperature 150-350 ° C, reaction pressure 100-300M
Under the condition of Pa, ethylene is polymerized using a radical polymerization catalyst such as an organic peroxide.

This HP-LDPE has the following physical properties: melt flow rate 1 to 20 g / 10 min and density 0.91 to 0.91.
Those having 0.93 g / cm ³ are preferred. here,
The melt flow rate is measured according to JIS K7210, and it is not preferable if it is less than 1 g / 10 minutes because drawdown property is poor, and if it exceeds 20 g / 10 minutes, neck-in and heat seal properties are poor. The density is measured in accordance with JIS K7112, it is not preferable since heat resistance is less than 0.91 g / cm ³ is inferior, since heat-sealing property is inferior exceeds 0.93 g / cm ³ is not preferable.

In the present invention, LLDPE, SSC-PE and HP-LDP constituting the ethylene resin composition.
The blending amount of each of E is 30 to 70 parts by weight with respect to 100 parts by weight of LLDPE, and H
P-LDPE is 50 to 100 parts by weight. SSC-P
When the compounding amount of E is less than 30 parts by weight, the low temperature heat-sealing property and the hot tack property are deteriorated, which is not preferable.
If the amount is more than 0 parts by weight, the neck-in is inferior, which is not preferable. If the compounding amount of HP-LDPE is less than 50 parts by weight, extrusion coating becomes difficult, and if it exceeds 100 parts by weight, the heat-sealing property and the hot tack property are deteriorated, which is not preferable.

The substrate film used in the present invention is a single layer composed of at least one selected from the group consisting of polyamide resin, polyester resin, polyvinylidene chloride resin, ethylene-vinyl alcohol copolymer resin and aluminum, or It is a multi-layer film and forms a gas barrier layer in the case of a food packaging film. Polyamide resins include those by ring-opening polymerization of lactam, those by polycondensation of diamine and dicarboxylic acid, those by polycondensation of aminocarboxylic acid, and those by copolymerization of raw material monomers of various polyamides. Nylon 6, nylon 6,6, nylon 6,1
0, nylon 6,12, nylon 2,6, nylon 4,
6, nylon 8,6, nylon 10,6, nylon 6 /
9, nylon 6/12, nylon 6 / 6,6, nylon MXD6 and the like are exemplified. As a polyester resin,
This is due to the polycondensation of diol such as acetylene glycol and dicarboxylic acid such as terephthalic acid.
Examples include polyethylene terephthalate, polyethylene naphthalate, poly (ethylene terephthalate / isophthalate), poly (ethylene glycol / cyclohexanedimethanol / terephthalate) and the like. The polyvinylidene chloride resin, vinylidene chloride as a main component, a monomer copolymerizable with this, for example, vinyl chloride, acrylonitrile, acrylic acid, methacrylic acid, acrylic acid alkyl ester, methacrylic acid alkyl ester,
Examples thereof include maleic anhydride, maleic acid, maleic acid alkyl ester, itaconic acid, itaconic acid alkyl ester, copolymers with vinyl acetate, ethylene, propylene, isobutylene, butadiene and the like. Examples of the ethylene-vinyl alcohol copolymer resin include saponified products of ethylene-vinyl alcohol copolymer, those containing 20 to 60 mol% of ethylene units are preferable, and the saponification degree of vinyl ester is 90%. The above is preferable. Examples of the film made of aluminum include an aluminum foil, and an aluminum vapor-deposited film obtained by subjecting the film made of the gas barrier resin to vapor deposition treatment.

Further, among the base films used in the present invention, those made of resin may be unstretched, uniaxially stretched, biaxially stretched or the like.
Further, the base material film may be used by laminating another base material, a film or the like, if necessary.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Extrusion coating materials of the present invention, LLDPE, SSC-PE and HP-LDPE.
The ethylene-based resin composition consisting of the above is a method of dry-blending each individually produced resin using a conventional mixer, or a melt such as a Banbury mixer, a continuous mixer, a twin-screw kneader or an extruder. It can be produced by a method such as granulating after melt-kneading using a mixing and kneading machine.

Extrusion coating of the above-mentioned ethylene resin composition for extrusion coating onto a base film is carried out by a method known per se, for example, the above ethylene resin composition is subjected to a molding processing temperature of 280 to 280 by an extruder equipped with a T die. T at 340 ° C
It is carried out by melt-extruding in a film form from a die, allowing it to flow over a substrate film that is fed out, press-bonding it between a pressure roll and a cooling roll, cooling it, and taking it off. At this time, in order to enhance the adhesive force between the extrusion coating layer and the substrate film, extrusion coating may be performed after the anchor coating agent is applied to the substrate film. As the anchor coating agent, organic titanium-based agents, isocyanate-based agents, polyethyleneimine-based agents, polybutadiene-based agents, and the like are useful. Usually, the thickness of the extrusion coating layer is 5 to 1
00 μm.

The present invention also includes 100 parts by weight of LLDPE, SSC-, for extrusion coating substrate films.
PE 30-70 parts by weight and HP-LDPE 50-10
An ethylene resin composition comprising 0 parts by weight is provided. In addition, various additives and auxiliary materials can be added to the above-mentioned ethylene resin composition of the present invention within a range that does not impair the characteristics of the present invention, depending on the purpose of use. As these various additives and auxiliary materials, antioxidants, ultraviolet absorbers, light stabilizers, lubricants, antistatic agents, antiblocking agents, plasticizers, neutralizing agents, processing aids, crosslinking agents, crosslinking aids, Examples thereof include fillers, foaming agents, antifoaming agents, colorants or pigments. In addition, a small amount of another polymer compound may be added to the ethylene-based resin composition without departing from the spirit of the present invention.

[0025]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Physical properties in the following examples and comparative examples were measured by the following methods. 1) Drawdown Property Under the conditions of extruder 90 mmφ, T die width 570 mm, and screw rotation speed 105 rpm, the maximum take-up speed at which the extruded coating film is broken or surging is measured and used as a measure of drawdown property. 2) Neck-in Extruder 90 mmφ, T-die width 570 mm, screw rotation speed 105 rpm, take-up speed 140 m / min,
Binaural neck-in is measured at an air gap of 120 mm. 3) Heat-sealing strength A test piece obtained by cutting a sample heat-sealed into a strip with a width of 15 mm under the conditions of a pressure of 1.0 kg / cm ² , a sealing time of 1.0 second, and a sealing temperature of 150 ° C. with a heat sealer was used.
After conditioning in a constant temperature and humidity chamber at a temperature of 23 ° C. and a humidity of 50%, the strength when pulled at a tensile strength of 500 mm / min is measured and used as a measure of the heat seal strength. 4) Low-temperature heat-sealing property The heat-sealing strength is measured by changing the sealing temperature, and the temperature at which the heat-sealing strength shows 2.0 kg / 15 mm is measured and used as a measure of the low-temperature heat-sealing property. 5) Hot tack property A test piece having a width of 30 mm and a length of 650 mm is folded in two, one end is fixed to an upper grip of a heat sealer, and the other end is faced down to apply a peeling load. Insert the portion near the fold into a 300 mm long heat seal bar, and apply a pressure of 1.0 kg / cm ² , a sealing time of 1.0 second, and a peeling load of 90 g / 10 mm under each sealing temperature (120
C., 140.degree. C., 160.degree. C., 180.degree. C.) The peel length at the time of heat sealing is measured and used as a measure of hot tack property.

The following resins were used in the following examples and comparative examples. LLDPE: ethylene-butene-1 copolymer produced by the Unipole method using a Ziegler type catalyst. Melt flow rate 8.5 g / 10 minutes, density 0.922 g / cm
³ [NUC polyethylene-LL (trade name), manufactured by Nippon Unicar Co., Ltd.] SSC-PE: ethylene-octene-1 copolymer produced using a single-site catalyst. Melt flow rate 7.0 g / 10 minutes, density 0.900 g / cm ³ , Mw /
Mn = 2.4 [Affinity (trade name), manufactured by The Dow Chemical Co.] HP-LDPE: Melt flow rate 6.0 g / 10
Min, density 0.918 g / cm ³ [NUC polyethylene (trade name), manufactured by Nippon Unicar Co., Ltd.]

Example 1 An ethylene resin composition consisting of 100 parts by weight of LLDPE, 50 parts by weight of SSC-PE and 70 parts by weight of HP-LDPE was kneaded in a Banbury mixer at 180 ° C. for 10 minutes and then granulated to obtain pellets. . The obtained pellets were 570 T-die wide using an extrusion laminator of 90 mmφ.
mm, die slit 0.8 mm, screw rotation speed 68
The stretched nylon 6 film (thickness 20 μm) coated with an isocyanate-based anchor coating agent was extrusion-coated to form a laminated film under the conditions of rpm, take-up speed of 80 m / min, and molding temperature of 310 ° C., and each physical property of this laminated film. Was measured. Table 1 shows the measurement results. The thickness of the extrusion coating layer was 30 μm.

Examples 2 to 5 and Comparative Examples 1 to 4 The same method as in Example 1 was carried out except that the ethylene resin composition in Example 1 was replaced with the composition shown in Table 1, and the evaluation results are also shown in Table 1. It was described in 1.

From these evaluation results, it can be seen that the measured properties of all the examples according to the present invention are good.
On the other hand, in Comparative Example 1, a resin composition containing no SSC-PE was used, and the low temperature heat sealing property and hot tack property were insufficient. Comparative Example 2 is SS
Although C-PE was blended, the amount thereof exceeded the range of the present invention, and the neck-in was insufficient. Comparative Example 3
Is a compounding amount of HP-LDPE is less than the range of the present invention,
Drawdown and neck-in were insufficient. On the contrary, in Comparative Example 4, the compounding amount of HP-LDPE exceeded the range of the present invention, and the heat seal strength and the hot tack property were insufficient.

[0031]

[Table 1]

[0032]

The laminated film of the present invention is obtained by extrusion-coating a gas barrier material layer with an ethylene-based resin. As the ethylene-based resin, LLDPE and HP-LDP are used.
By adding SSC-PE in addition to E,
Extrusion processability, drawdown property
Neck-in, heat resistance, hot tack and heat seal strength are maintained, and the low temperature heat seal property, which has been a problem in the past, is greatly improved. For this reason,
The laminated film of the present invention can be reliably heat-sealed at a low temperature and is preferably used as a food packaging film and the like.

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location B32B 27/34 B32B 27/34 27/36 27/36 B65D 65/40 B65D 65/40 Z 75/26 75 / 26 // C08L 23/04 LCD C08L 23/04 LCD

Claims (2)

[Claims] 1. A linear low-density ethylene-α-produced by using a Ziegler type catalyst or a Phillips type catalyst.
100 parts by weight of olefin copolymer, 30 to 70 parts by weight of ethylene-α-olefin copolymer produced using a single-site catalyst, 50 to 50 of low-pressure polyethylene of high pressure method
100 parts by weight of an ethylene-based resin composition is used as a single layer or multiple layers of at least one selected from the group consisting of polyamide resin, polyester resin, polyvinylidene chloride resin, ethylene-vinyl alcohol copolymer resin and aluminum. A laminated film formed by extrusion coating on the base film of. 2. The laminated film according to claim 1, which is used as a food packaging film.