JPS58166049A - Linear polyethylene shrinkable film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-shrinkable, thermoplastic packaging film. In particular, the present invention relates to shrink films using linear low density ethylene or linear intermediate density polyethylene resins to constitute the core and/or intermediate layer of the multilayer film.

The present invention relates to new and useful heat-shrinkable film compositions. One of the distinguishing characteristics of a shrinkable film is the film's ability to shrink when heated to a certain temperature and, when that shrinkage is restrained, to generate shrinkage tension within the film.

As is well known in the manufacturing industry, shrinkable film is manufactured by heating a resin-like material from its flow temperature to its melting temperature and extruding it into a cylindrical or flat shape through an extrusion die. It is coupled from k. After extrusion, the extrudate is rapidly cooled and then reheated to its orientation temperature WK. The orientation temperature range for a given film will vary with different resinous polymers and formulations from which the film is made. However, the orientation temperature range is generally said to be above room temperature and below the melting point of the film.

In this specification, the term "orientated J-axis r-oriented 1" means that after stretching a film heated to an orientation temperature range,
Tun refers to the process of immediately quenching to physically align the molecules to modify the molecular arrangement of the material and improve the physical properties of the film, such as shrinkage tension and orientational relaxation stress, or the product obtained thereby. shall be. These two properties can be measured in seconds according to AsTM D 2839-69 (revised 1975). When a stretching force is applied in one direction, a -axial orientation is obtained. When stretching forces are applied in two directions K, a biaxial orientation is obtained. As used herein, the term orientation is also used interchangeably with heat shrinkability. The term heat-shrinkable is used to describe materials that are heat-set by being stretched and cooled in their stretched dimensions. Oriented or heat-shrinkable materials tend to return to their original unstretched dimensions when heated to a suitable temperature below their melting point range.

The basic process for producing the film described above is that the film, once extruded and quenched, is then reheated to its orientation temperature and oriented.

The stretching and orientation of K can be carried out in many dimensions, for example by the blown bubble method or the tenter-free method. These words! ! & It is well known to experts in the eastern world and is called the orientation process.

In this case, the material is stretched in the transverse direction (TD) and in the at or machine direction (MD). The stretched bale and film are quickly quenched to fix the oriented molecular morphology.

After fixing the oriented molecular morphology, the film can be stored as rolls and used for tight packaging of various articles. In this regard, the product to be packaged is first encapsulated within the heat-shrinkable material by first optionally heat-malting the shrink film on itself. Thereafter, the wrapped product can be heated to a high temperature, for example by passing it through hot air or a hot water bath. This causes the film to shrink around the product, producing a rigid package that closely conforms to the contours of the product.

The above general overview regarding the manufacture of films is not exhaustive as this method is well known in the art. For example, U.S. Patent No. 4.274900;
, 18 to No. 443, No. 4,048゜428, No. 3,8
See No. 21,182 and No. 3.022°543.

It will be appreciated by those skilled in the art that many variations can be made to the general method described above, depending on the end use of the film and the desired properties to be imparted to the film. can be cross-linked during the process to improve the anhydrite properties and other properties of the film. Cross-linking and methods for doing so are known in the art. Cross-linking can be done by irradiating the film or alternatively by This can be achieved chemically using peroxides. Another possible modification method is to coat the inside of the newly extruded material with a fine mist of silicone spray to improve the subsequent processability of the material. There is a method for making a kernel-like inner coating.
It is described in No. 18.

Shrink films of 4-lyolefins and 41-IK-diethylenes have a shrinkage force (the force exerted by the film on its cross section during shrinkage), a degree of free shrinkage (a certain amount that the material exhibits when heated to a high temperature without restraint), and a degree of decrease in linear dimension f), tensile strength (maximum force that a unit area of film K can achieve before the film is torn), sealability, shrinkage temperature curve (curve representing shrinkage vs. temperature) ), tear initiation point and tear resistance (the force at which the film begins to tear and continues to tear), optical properties (material gloss,
It provides a wide range of physical and use properties such as haze, clarity) and dimensional stability (the ability of the film to retain its original dimensions under different types of storage conditions). Film properties play an important role in choosing a particular film;
It varies depending on the purpose of each packaging and each packaged product. Consideration must be given to the size, weight, shape, stiffness of the product, number of product components, other packaging materials used with the film, and available packaging materials.

/IJ Considering the above physical properties of ethylene films, as well as the many applications that have already been used for these films, and the many applications that can be envisaged,
It will be readily seen that there is a great need to improve any or all of the above physical properties of these films, and this must still be done.

Accordingly, it is a general object of the present invention to provide a heat-shrinkable polyolefin film that is improved over films used in prior art methods.

Another object of the invention is to provide a polyolefin film with improved shrinkage tension.

Yet another object of the present invention is to provide an I-lyolefin shrink film with improved optical properties.

Yet another object of the present invention is to provide an I-lyolefin shrink film with a wide range of shrink temperatures.

Yet another object of the present invention is to provide an I-lyolefin shrink film with improved sealing properties.

Yet another object of the present invention is to provide a polyolefin shrink film with improved tear propagation resistance.

Yet another object of the present invention is to provide an I-lyolefin shrink film with improved machinability.

Yet another object of the present invention is to provide an improved polyethylene shrink film in which linear low density ethylene or linear intermediate density polyethylene resin is used to constitute the core and/or intermediate layer of the multilayer film. be.

The above and other objects are accomplished by providing a 4 lyolefin shrink film as described herein.

Unless otherwise stated, defined, or limited in the following description, the term polymer or polymer resin as used herein refers to homopolymers, copolymers, terpolymers, block polymers, graft polymers. It shall include polymers, disordered polymers, and alternating polymers.

r melt flow j% or "melt flow coefficient 1" as described herein
The term is the amount (in II units) of thermoplastic resin that can be extruded from 900 ml at a given pressure and temperature as per ASTM D 1238.

The term "core" as used herein refers to a layer in a multilayer film that is surrounded on both sides by another layer.

The term "epidermis" or "epidermal layer" as used herein refers to the outer layer of the multilayer film. (i.e. surface) layer.

As used herein, the term "intermediate" or "interlayer" refers to a layer of a multilayer film that is neither a core layer nor a skin layer.

As used herein, the term "low density polyethylene J (LDPE)" refers to a homogeneous polymer of ethylene having a density of 0.910 to 0.925.

The linear low density polyethylene (LLDP) described herein
The term FI: ) refers to ethylene, 8- or less butenes, octenes,
Or it means a copolymer with hexene.

r linear intermediate density/IJ ethylene” (L
The word MDPE) has a density of 0.926 to 0.940.
refers to a copolymer of ethylene and 8- or less butene, octene, or hexene in which the molecule has little or no branching or crosslinking along the polymer chain.

“Ethylene vinyl acetate copolymer, 1 (E
The term VA) refers to a copolymer made from ethylene and vinyl acetate in which units derived from ethylene are present in a large amount and units derived from vinyl acetate are present in a small amount.

“Ethylene-propylene copolymer J (E
The term PC) refers to a copolymer made from ethylene phosphor and propylene monomer, in which units derived from propylene are present as the main component, and units derived from ethylene are present only in a minor amount. .

"Propylene homopolymer"(PP') as described herein
The term refers to a thermoplastic resin having a density of about 0.90 and obtained by polymerizing propylene using a suitable catalyst by methods known in the art.

In the present invention, flexible, heat-shrinkable packaging thermoplastics with desired combinations of physical properties such as shrink tension, optical properties, cuttability, sealability, shrink temperature range, and tear resistance are used. It has been found that films can be obtained with the multilayered flexible thermoplastic packaging film of the present invention. This multilayer film has a core layer comprising a linear low density I-lyeethylene resin. It is believed that a linear medium density 4-ethylene resin can be used in place of a linear low-density ethylene resin. In a preferred three-layer embodiment, in addition to the core layer described above, two layers each comprising a pro2-lene homopolymer and an ethylene-propylene copolymer blend.
Contains two epidermal layers. Preferably, the multilayer film is oriented to be heat shrinkable in at least one direction.

This multilayer film can be combined with other polymeric materials in specific applications. For example, relatively thin layers can be added to one or both sides of the matrix of a suitable three-layer structure to improve seal strength or reduce gas and moisture permeability.

In other embodiments of the invention, a five layer film structure is realized. A preferred five-layer structure has the same core layer and skin layer as the three-layer structure described above, with the addition of ethylene/acetate Kurayoshi light vinyl copolymer and ionomer resin or linear low density 11J, respectively. Contains two intermediate layers containing a blend with ethylene. It is currently believed that linear intermediate density 4-lyethylene can be used in place of linear low density polyethylene in the intermediate layer.

Referring to FIG. 1, which shows a cross-section of a preferred three-layer embodiment of the invention, this embodiment consists of a core porosity 2 and skin layers 1 and 3.

FIG. 1 illustrates that the preferred thickness ratio of the three layers is 1/3/1. A preferred core layer 2 composition consists of a linear medium density I-lyeethylene polymer. However, it is believed that the use of linear intermediate density polyethylene polymers as the core mat composition does not substantially alter the properties of the final film product. The core layer 2 is made of linear low-density polyethylene (or linear medium-density ethylene), or consists of linear low-density polyethylene (or linear medium-density ethylene) and (a) an ethylene-propylene copolymer; or (b) ethylene/vinyl acetate copolymer, or (c
) a blend of ethylene/vinyl acetate copolymer and an ionomer resin; or (d) a blend of copolymer with low density polyethylene. According to the invention, therefore:
Various formulation compositions for layer 2 of the core can be selected from the following groups:

(1110~1001 (iDLLDPE and o~9oes
Blends with EPC (2) 10-100% LMDPE and 0-90% R
Blends with PC (3110-801 (Blends of DLLDPE with 20-9oIs EVA (4) 10-80LsOLMDPE with 20-909
Blend with gv person (5) to ~80ch LLDPE and 10~80ch EV
Blends with A and 10-80 ionomer resins (6110-805 LMDPE and 10-80 EV
Blends with A and 10-80 ionomer resins (7) 10-801 g (DLLDPE and 20-90
Blends of Is with LDPE (8) 10-80-O80-0L and 20-9oIs
where LLDPE ii is an abbreviation for linear low density ethylene as defined above. ][, MDPE is an abbreviation for linear medium density polyethylene as defined above. EPC is an abbreviation for ethylene-propylene copolymer as defined above. EV
A#i is an abbreviation for the ethylene/vinyl acetate copolymer defined above. The term ionomer resin is intended to broadly encompass the group of ionomer resins. One of the most prominent ionomer resins is commercially available from Du Pont under the tradename Surlyn.

Testing has shown that the most preferred core layer composition consists essentially of linear low density polyethylene.

This material is manufactured by Dow Chemical.
Dowlex (I) owlex) 20
The city is known for 45 product names.

Returning to Figure 1, % skin layers 1 and 3, suitable skin layer compositions are selected from the following group:

(1) EPC (2170-90es EPC and 10-30qb PP
Blends with (3170-90 *LL of ogpc and lO-30Is
Blend with DPE (4) EPC of 70-90- and LMD of 10-301G
All abbreviations for formulations with PE are the same as mentioned above for the composition of the core layer. Additionally, PP is an abbreviation for propylene homopolymer as defined above. Experience has also shown that a particularly preferred skin layer composition consists essentially of a blend of 209I PP and 80-0 EPC.

Propylene homopolymer is manufactured by Hercules Chemical (He
It is commercially available from Rcules Chemical under the trade name PDO64. Ethylene-propylene copolymer is manufactured by Soltex Chemical (Soltex Cheml).
Cal ') under the trade name 42XO1, or Solvay Chemi-c
It is commercially available under the trade name KS400 from the company Al.

Throughout the specification and claims, all proportions are by weight, in units of density II'ig/CC.

Summarizing past experience, a particularly preferred embodiment of the present invention is such that the core layer consists of essentially linear low density polyethylene and the skin layer consists essentially of [209G propylene homopolymer and 80G]. It consists of a blend of ethylene and propylene copolymers.

Although the three-layer compositions described above are generally preferred from a manufacturing economic standpoint to structures with four or more layers, various five-layer compositions may also be made which are satisfactory from a physical property standpoint. Ta. However, manufacturing costs for five-layer films are generally higher than for three-layer films.

Referring to FIG. 2, which is a cross-sectional view of a preferred five layer film of the present invention, a preferred five layer thickness ratio of 2/2/1/2/2 is shown. Core layer 6 may be comprised of any of the core layer compositions previously described for the core layer of the three layer embodiment. The core layer can also consist essentially of K (1) ethylene propylene copolymer (EPC) or (2) ethylene vinyl acetate copolymer (EVA).

Skin layers 4 and 8 of the five layer embodiment can be comprised of any of the same skin layer compositions as previously described for skin layers 1 and 3 of the three layer embodiment of FIG.

The five layer embodiment of FIG. 2 also includes intermediate layers 5 and 7. The core layer 2 of these intermediate layer embodiments may consist of any of the compositions previously described.

The compositions of the intermediate layers 5 and 7 can also be selected from the following group:

(11EVA (2) Blend C3 of 20-80% LLDPE and 20-80q4 ionomer resin) Blends of 20-80% LMDPE and 20-809g ionomer resin Experience shows that a suitable Five-Layer Structure: Skin layers 4 and 8 consisting essentially of ethylene-propylene copolymer (EPC), and an intermediate layer consisting essentially of a blend of 90 parts ethylene-vinyl acetate copolymer and 10 parts ionomer resin. 5 and 7, and a core layer 6 consisting essentially of linear low density/IJ ethylene. EPC is commercially available from '5o-1tex Chemical under the trade name 42XO1. EVA is commercially available from Du Pont Chemical Company under the trade name Ethylene (Ala-1hon) 3137.

Ionomer resins are commercially available from du p Chemical under the trade names Surlyn and Surlyn 1601.
It is commercially available from Ont Chemical Co., Ltd.

LLDPE is manufactured by Dow Chemical.
Dowlex (1) owlex) 20 from a l) company
It is commercially available under 45 product names.

As will be readily apparent to those skilled in the art, all of the above weight proportions may vary slightly.

These proportions can also be varied slightly as a result of the addition or coating of additives, such as the silicone casts mentioned above, and slip agents (S11 agents) or antiblocking agents. A suitable antiblocking agent is available from Johns Manville under the trade name White Mist.
The silica is commercially available from Manville. A suitable slip agent is Erucamide (Humco Chemical (Hu
Chemamide (Ke
(commercially available under the trade name of mamide) E), stearamide (
(Commercially available from Humco Chemical Company under the trade name Chemamide S)
, and N,N-dioleoylethylenediamine (commercially available from Qlyco Chemical under the tradename Acrawax'C). A preferred silicone propellant is General Electric 5F18/Rydimethylsiloxane from General Electric.

The general range of addition of these additives is as follows.

α) Silica: 250-3000ppm (2) Acra Wax C: 200-4000ppm (
3) Erucamide = 200 to 5,000 ppm (4) Stearamide: 200 to 5,000 ppm (5) Silicone propellant: 0.5'q square foot or more Throughout this specification and claims, "consisting essentially of"
The term does not exclude slight variations in the proportions by weight or of such additives.

Although further layers and/or small amounts of additives of the type described above may be added to the three- or five-layer structures of the invention as desired, the desired shrinkage tension of the multilayer film of the invention;
Care must be taken not to adversely affect shrinkage properties, optical properties and other properties.

In the preferred method of manufacturing multilayer linear low density polyethylene or linear intermediate density polyethylene shrink films of the present invention, the basic steps are to compound the polymers used in the various layers and coextrude the layers to form the multilayer film. This is a step in which the film is stretched and then biaxially oriented. These steps and additional desirable steps are described in detail below.

The method of the present invention begins by blending the raw materials (also polymer resin) in the desired proportions and ranges described above. Resins are usually purchased in pellet form from manufacturers and can be compounded in one of the many commercially available compounders known in the art. During the compounding process, additives and/or reagents that are desired to be used may be incorporated.

The blended resin and additives and/or reagents are then fed into the extruder hopper and then into the coextrusion die. For three layer films, at least three extruders need to be used if different compositions are used in each layer. Two extruders are fed with the material desired for the inner and outer skin layers, and the other extruder is fed with the example linear low density or linear medium density polyethylene material desired for use in the core layer. Other extruders can be used as needed. Preferably, the materials are coextruded as a tube with a diameter depending on the racking ratio and the desired final diameter. This coextruded tube is relatively thin and is referred to as tape. Circular coextrusion dies are well known in the art and can be purchased from many manufacturers. In addition to co-extruding in the form of a strip, a single-slot die can be used to extrude the material in a planar form. Known single layer or multilayer extrusion coating methods can be used if desired.

Other additional processes that may be used include bombarding the tape, or unexpanded tube, or sheet with high energy electrons generated from an accelerator to cross-link the tape material. When the film material consists primarily of ethylene, such as polyethylene or ethylene-vinyl acetate copolymers, cross-linking significantly increases the structural strength of the film, ie, the force with which the material can be stretched before tearing.

Irradiation destroys the optical properties of the t9 film and changes the properties of the film at elevated temperatures. When using the irradiation process, the preferred J-& irradiation amount is 0.5MR~12. It is OMR. MR is an abbreviation for Megarad, and Megarad is lXl.
0@rand, and 1 rad is the amount of ionizing radiation resulting from the absorption of 100 ergs of energy per gram of irradiated material, regardless of the source. If the
The multilayer film may be first stretched and then irradiated, or, in sequential coatings, a layer or layers may be irradiated and other layers may be applied before the final stretching or orientation step. be able to.

As previously mentioned, an optional additional step is to spray finely powdered silicone onto the interior of the newly extruded tape. Details of this process are available on July 31, 1981.
U.S. Pat.

Co-extrusion is followed by quenching, irradiation if necessary, reheating of the extruded tape, and continuous expansion with internal air pressure to produce thick-walled narrow tapes to the desired film thickness. into a thin, wide film with four walls.

This process is often referred to as the oriented r-trapping bubble method or Fir racking. After stretching, the air bubbles are deflated and the film is rolled onto semi-finished rolls called mill rolls.The racking process orients the film laterally and to some extent vertically, rearranging the molecules. This imparts shrinkability to the film and modifies the physical properties of the film.The additional longitudinal or machine direction stretch is applied to the reheated "tape" by racking or blowing it into a chamber of bubbles. This can be achieved by rotating a contraction roll, which serves to collapse the blown air bubbles, at a faster speed than the roll, which serves to transport the bubbles.

All these orientation methods are known in the art.

The following examples are included to clearly convey the scope of this invention to those skilled in the art.

Example 1 A five-layer structure with a layer thickness ratio of approximately 2/2/1/2/2 was extruded using four extruders. Die-shaped orifices t-4 for both intermediate layers 7'hN0.1+7) 901 in the extruder! Ethylene-vinyl acetate copolymer (vinyl acetate 12%') C ethylene 3xa7 (melt M coefficient 0.5)) and 10 ionomer resin [Surlyn 1601 (density 0.94 n, melt coefficient 1.4)] A formulation of This formulation also contains 1 l 100 ppm erucamide [chemamide E] and 11 nOppm stearamide [
Chemamide S]. The extruder No. 2, which has a die-shaped orifice for the core layer, is equipped with linear low-density polyethylene [Dowlex 2045 (density 0
．． 920, melting coefficient 1.0'l] was supplied. No. 3 and N. with die-shaped orifice to the epidermal layer
In the extruder of 014, ilooppm of erucamide [Chemamide E] and 1l of 100pp of stearamide [
Chemamide S] and 1100 ppm silica [White Mist] mixed with 100% ethylene-propylene/copolymer (&5% ethylene) [Tsultex 42]
XO1 (melt flow table 5)] was supplied.

Extruder No. 1 #1 was maintained at a temperature range of 1390-425"F. Extruder No. 62 was maintained at a temperature range of 410-470"F. Extruder N013 was maintained at a temperature range of 350-3701. Extruder No. 4 is 345~365″F'
temperature range. The circular die type is 390-435.
? Between the temperatures of i! ! I kept it.

After extruding the layer through a 10 inch circular die orifice, the cylindrical extrudate with a tape thickness of about 15 mils and a tube width of about 9 inches is passed through cold water at a rate of about 37 feet per minute. It was rapidly cooled. The cylinder was then reheated and oriented by passing it through a heating chamber or furnace at a rate of 3.8 feet/minute. The furnace was heated by horizontal, vertical, and steam heating elements. In this example, the horizontal heating element is 200mm. I kept it. Vertical heating element is 3001
2 PL!
i of water vapor was supplied.

After heating as described above, the cylindrical extrudate was expanded and stretched by about 4.8-1 times in the transverse direction and about 4.3-1 times in the longitudinal direction. Thereafter, the film was cooled by quenching with water to fix the orientation structure. The final film gauge was approximately 75 gauge.

The experimental data obtained for this film composition are listed in Table 1 along with data for other examples.

Example 2 A five-layer structure with layer thicknesses of approximately 2/2/1/2/2 was extruded using four extruders. No. 1 extrusion 4'lK 110 with die-shaped orifices for both intermediate layers
50% ethylene-vinyl acetate copolymer (vinyl acetate 12%) containing 0 ppm erucamide [chemamide E]
A blend of (ethylene 3137 (melt coefficient 0.5')) and 50 inches of linear low density polyethylene (Dowlex 2045 (density 0.920, melt coefficient 1.0)) was provided. NO12 with die-shaped orifice for core layer
The extruder was filled with 100 inches of linear low-density I-polyethylene [Dowlex 2045 (density 0.920, melting coefficient 1.0)].
] was supplied. Both NO3 and N014 extruders, each with a die-shaped orifice running into the skin layer, have a 1 liter
100 pp of erucamide [chemamide E] and 110
100-silkworm tyrene propylene copolymer (2,7
-ethylene) [ARCO') K-193 (melt flow 23)] was supplied.

Extruder No. 1 #'i 405~415''F Temperature maintained at 21! Extruder No. 2 Fi 400~475?
temperature range. Extruder No. 3 is 355-435
The temperature was maintained at F. Extruder NO64 is 355-41
The temperature was maintained at 0'F. The circular die type is 390~
A temperature range of 425″F was maintained.

After extruding the layer through a 10-inch circular die-shaped orifice, the cylindrical extrudate, about 17 mils thick and about 8% inches wide, is quenched by passing it through cold water at a rate of about 39 feet/minute. Cooled.

The tubular extrudate was then reheated and oriented by passing it through a heating zone or furnace at a rate of about 38 feet/minute.

The furnace was heated by horizontal, vertical, and steam heating elements. In this example, the horizontal heating element is 212"F'
I kept it. The vertical heating element was maintained at 343''F' and the steam heating element, which provided heat by passing through pipes or cans placed inside the furnace, was supplied with 7 psi steam.

- Expand the cylindrical extrudate after heating as described in
It was stretched about 4.8-1 times in the transverse direction and about 4.5-1 times in the longitudinal direction. Thereafter, the oriented molecular structure is fixed by cooling by quenching with water. The final film thickness is approximately 75 gauge.

The data obtained for this film composition are listed in Table 1.

Example 3 A three-layer structure with a layer thickness ratio of approximately 1/3/1 was extruded using four extruders. 3300 for No. 1 and 2 extruders with die-type orifices for core IIIK.
1oo10 containing ppm of Erucamide [Chemamide E]
Linear low density I-lyeethylene [Dowlex 2045 (density 0.920, melting coefficient 1.0) 1 was supplied. Extruders 9N003 and NO,4 with die-shaped orifices for the skin layer were both mixed with 80% 3300 ppm Erucamide [Chemamide E], 1l 100 ppm silica [Holloyt Mist], and 1650 ppm Acrawax C. ethylene-propylene copolymer (3.5% ethylene) [Tsurtex 42XO1 (melt flow 4.5)] and 20% propylene homopolymer [Hercules PDO 64 (density 0.906, melt coefficient 3.5)
) 1 was provided.

Extruder N011 was maintained at a temperature range of 395-4851. Extruder No. 2 is 425-470? temperature range. The temperature range of extruder No. 3ti was maintained at 370 to 3751. The extrusion tpNO,4 was kept at a temperature range of 370-375"F. The circular die was kept at a temperature of 385"F'. For this example, the actual temperatures at which the extruder and die were held were not listed.

After extruding the layer through a 10 inch circular die orifice, the tubular extrudate was quenched by passing it through cold water at a rate of about 39.5 feet/minute. When extruding the tape, coat the inside of the extruded tube with two strokes of fine silicone at a rate of S~7q/ft. The cooled cylindrical extrudate was then reheated and oriented by passing it through a heating zone or furnace at a rate of about 37.7 feet/minute.

9. Heating the paper furnace by horizontal, vertical, and steam heating elements. In this example, the horizontal heating element is 20”FK
I kept it. The vertical heating element was kept at 30 seconds, and the pipes placed inside the furnace were passed through the can.The steam heating element, which supplied heat, was supplied with 3.5 p8i of steam.

After heating as shown in step 1, the cylindrical extrudate is horizontally
．． It was stretched 8 to 1 times and about 4.5 to 1 times in the longitudinal direction. Thereafter, the dyed film was quenched using water pressure to fix the oriented structure. The final film gauge was about 75 gauge.

The data obtained for this film composition are listed in Table 1.

Table 1 Tensile strength xloorpsi) (Note 1) MD 97.1 125.2 124.6T
D 110.5 105.1 130.7 Elongation (ts) (Note 2) Mo 86 98 113TD
65 107 102 Modulus X100 (
psiX Note 3) MD 90.3 98.3
96.5TD 101.4
99.4 97.6 Tear propagation (IIO note 4
) MD 410 4.33 9
．． 60TD 4.01 5.53
9.83 Tear resistance (4y) (Note 5) MD O, 700, 610, 60TD
O,900,83α67200'P
Contractile free contraction at K (Note 6) MD I6 14 12T
0 18 20 17 Contraction tension (psi) (Note) MD 239 304 288T
D 327 457! 509
Contractile free contraction at 260FK (6) (Note 6) MD 51! 49 4
8TD Sfu 57S
4 Contraction tension (psl) (Note 7) Mo 220 345 434T
D 365 422 53g28
Contractile free contraction in G”PK (-(Note 6) MD 71 66 62T
D 6F 68 64 Contraction tension (psi) (Note 7) MD 237 348 432T
D 304 362 584 Optical properties (Note 8) Cloudy C1b> 2.5 2.1
2.0 gloss (45”) 94 88
88 total transmittance 9L5 912
9L2 (Note) (11λSTM D 882 (21ASTM
D 882 (3) ASTM D 882 (
4)' ASTM D 1938 (5) ASTM D
1004 (6) ASTM D 2732 (
71ASTM D 2B3B (8)ASTM
All data in Table 1 of D 1003 is ASTM
This is the average value obtained by the standard method.

It will be apparent to those skilled in the art from the foregoing description and examples that many modifications and variations can be made within the spirit and scope of the invention; Please take a look at the specific example shown, which is for illustrating mK.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a preferred three-layer embodiment of the present invention, and FIG. 2 is a cross-sectional view of a preferred five-layer embodiment of the present invention. Patent Applicant D'Abriny R.IV4 X, & Co. FIG. 1 FIG. 2 271

Claims (1)

[Claims] 1. A multilayer 4-lyolefin film containing a core layer, the core layer containing Fi linear low-density polyethylene. 2. A multilayer polyolefin film containing a core layer consisting essentially of linear low density polyethylene. 3. #-shaped low density, ll 17 A core layer consisting essentially of ethylene and two sheets consisting essentially of a blend of 80% by weight ethylene-propylene copolymer and 20% by weight propylene homopolymer. A multilayer polyolefin film containing a skin layer of. 4. Core layer consisting essentially of #-shaped low-density I-lyeethylene; 90% by weight ethylene-vinyl acetate copolymer and 10%
A multilayer polyolein film containing two intermediate layers consisting essentially of a blend with a weight of ionomeric resin; and a skin layer consisting essentially of an ethylene-propylene copolymer. & A multilayer f-lyolefin film containing a core layer consisting essentially of linear medium density polyethylene. 6. A multilayer I olefin film comprising a core layer and at least two intermediate layers, the intermediate layer containing linear low density ethylene. 7. Claim 1 further comprising at least two intermediate layers, the intermediate layer containing linear low density polyethylene.
The multilayer I lithography film described in Section 1. & The core layer is 8, 10 to 100 weight - linear low density 4-lyeethylene and 0
Blends with ˜90 wt. of ethylene propylene copolymer; 6. Blends of 10 to 100 wt. of linear intermediate density polyethylene with θ˜90 wt. of ethylene propylene copolymer: 0.10 ~80 wt- linear low density 4-lyethylene and 20
Blends with ~90% by weight of ethylene-vinyl acetate copolymer; d. 10-80% by weight of linear medium density ethylene;
Blends with 0-90% by weight of ethylene-vinyl acetate copolymer; e, 10-80% by weight of linear low density 4-lyethylene, 10
Blends with ~80 wt. ethylene, vinyl acetate copolymer, and 10-80 wt.% ionomer resin; f. 10-80 wt.% linear medium density polyethylene; 1
Blends with 0-80% by weight of ethylene-vinyl acetate copolymer and 10-80% by weight of ionomer resin;
Blend with ~90 wt. low density ethylene; h, 10-80 wt. linear intermediate tube [dllJEthiV)
and 20 to 90% by weight of low density polyethylene; and 20 to 90% by weight of low density polyethylene. i further contains two skin layers, said skin layers comprising: a. ethylene propylene copolymer: h. 70 to 90 wt. ethylene propylene copolymer and 10 to 30 wt. propylene homopolymer. Blends with 0.70-90% by weight of ethylene-propylene copolymer and 10-30% by weight of linear low-density polyethylene; d, 70-90% by weight of ethylene-propylene copolymer and a linear intermediate density of 10 to 30 wt./l ethylene; 1. A multilayer polyolefin film on board a ship having a composition selected from the group consisting of: 10, further comprising an intermediate layer, the intermediate layer having 8.10 to
Blend of 100% by weight linear low density polyethylene with 0-90% by weight ethylene-Pt11fv copolymer; h, 10-10
0 wt% linear medium density polyethylene and 0 to 90 wt.
Blends with ethylene-vinyl acetate copolymers of 10-80% by weight; Blends of linear low density/17 ethylene with 20-90* amounts of ethylene-vinyl acetate copolymers d, 10 ~80 linear intermediate density of ginseng/l ethylene and 2
Blends with ethylene-vinyl acetate copolymers of 0 to 90 wt., 10 to 80 wt.
Blends with 10-80% by weight of ethylene-vinyl acetate copolymer and 10-80% by weight of ionomer resin; f, 10-80% by weight of linear intermediate tube 1/13 ethylene, 10-80% by weight % ethylene-vinyl acetate copolymer and 10 to 80 wt. ionomer resin; g, 10 to 80 wt. linear low density polyethylene and 20 g.
Blends with ~90 wt. % low density polyethylene; h, linear intermediate density of 10-80 wt. / Blends of 17 ethylene with 20-90 wt. low density polyethylene; i. ethylene-vinyl acetate Copolymer oligomer, 20 to 80 wt. linear low density/9 ethylene and 20
Blends with ~80 wt% ionomer resin; 20-80 wt% linear medium density polyethylene;
A multilayer polyolefin film according to claim 1 having a composition selected from the group consisting of: 0 to 80 wt. ionomer resin;