AU632952B2

AU632952B2 - Resin laminates

Info

Publication number: AU632952B2
Application number: AU80435/91A
Authority: AU
Inventors: Shinji Kawamura; Hiroshi Kudo
Original assignee: Idemitsu Petrochemical Co Ltd
Current assignee: Idemitsu Petrochemical Co Ltd
Priority date: 1988-07-30
Filing date: 1991-07-15
Publication date: 1993-01-14
Anticipated expiration: 2009-07-26
Also published as: AU8043591A

Description

S F Ref: 183714

AUSTRALIA

COMPLETE SPECIFICATION ACT 19 COMPLETE SPECIFICATION FOR A STANDARD PATENT S0 0

ORIGINAL

o c( 0 CO 0 C 0 0 0 0 0 0 00 0 .00 0 c Name and Address of Applicant: Actual Inventor(s): Address for Service: Invention Title: Idemitsu Petrochemical Company Limited 1-1, Marunouchi 3-chome Chiyoda-ku Tokyo

JAPAN

Hiroshi Kudo and Shinji Kawamura Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Maiket Street Sydney, New South Wales, 2000, Australia Resin Laminates The following statement is a full description of this invention, including the best method of performing it known to me/us:- 5845/3 1 BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin laminate and, more particularly, to a resin laminate which is excellent in heat sealability and suitable for packing liquid, powdery or granular matters such as various foods, beverages, chemicals and the like.

2. Description of Related Art Heretofore, as packaging materials for liquid, powdery or granular matters, such as various foods, beverages, chemicals, cement, sand or the like, there have been employed paper, synthetic resin sheets or films, a laminated material consisting of paper and synthetic resin sheets or films or the like. Packaging materials made up of synthetic So° resins, particularly polyolefin sheets or films, are employed in many 'o o industrial fields because of their excellent formability, water 15 resistance and chemical resistance as well as their high productivity.

For packaging films for packing various goods such as foods and beverages, a good heat sealability is required. In order for there to be 0000 a good heat sealability, for instance, the sealing temperature should be low, the range of sealing temperatures should be wide, the sealing strength should be high, the sealability of foreign matters particularly containing liquid matters should be sufficient, and little or no o shrinkage in sealing should occur.

oo° o In addition, packaging films require properties which would not interfere with a good heat sealability, such as good film stability and 25 high rigidity for convertibility. In summary, good packaging films require properties particularly in a favorable balance of convertibility with heat sealability.

Various attempts have heretofore been made to improve packaging materials in heat sealability, transparency, rigidity, impact resistance and the like.

For example, Japanese Patent Publication (laid-open) No.

12,008/1980 discloses packaging bags made up of a multilayer film consisting of inner and outer layers, in which there is employed as an 3 inner layer a random copolymer having a density of 0.915 to 0.940 g/cm3, obtained by copolymerizing ethylene with an ac-olefin having KXN:1422y 2 Sto 10 inclusive carbon atoms in the presence of a catalyst consisting of a titanium catalyst component (containing a titanium compound and a magnesium compound) and an organoaluminium compound in order to provide the inner layer with an improved heat sealability. This publication states that the random copolymer has a density ranging preferably from 0.920 to 0.935 g/cm 3 a melt index ranging preferably from 1.0 to and a film thickness ranging preferably from 5 to 40[m. It further states that, as an outer layer, there may be employed paper, aluminium foil, and a film of a polymer capable of forming a film, such as polyethylene, polypropylene, poly[vinyl chloride], poly[vinylidene chloride], nylon and polyethylene terephthalate. The inner and outer layers are laminated to form a multilayer film, and both the inner layers S, of the multilayers are heat-sealed to each other to form a packaging bag.

Japanese Patent Publication (laid-open) Nos. 59,943/1982 and 36,549/1985 disclose ethylene-a-olefin copolymers with a good heat sealability as raw materials for laminating. The former discloses a o°9 composition comprising a mixture of an ethylene-a-olefin copolymer having a smaller melt index with an ethylene-a-olefin copolymer having a larger melt index, having a wide distribution of molecular weights, and improved convertibility. The latter discloses a composition of polymers for heat sealing, which comprises a mixture of an ethylene-a-olefin copolymer with an ethylenic polymer such as a low density or a high 9 o density polyethylene.

Japanese Patent Publication (laid-open) No. 160,147/1983 discloses S 25 a heat-sealable coextruded multilayer film, in which its inner layer is composed of a layer of an ethylene-a-olefin copolymer having a density ranging from 0.92 to 0.94 g/cm 3 its core layer is composed of a layer of a low-density polyethylene having a density ranging from 0.92 to 0.93 3 g/cm manufactured by high-pressure method and its outer layer is composed of a layer of an ethylene-a-olefin copolymer having a density 3 ranging from 0.91 to 0.93 g/cm.

Japanese Patent Publication (laid-open) No. 54/283/1978 discloses a multilayer film in which an ethylene-vinyl acetate copolymer layer having a lower melting point is laminated on a polyethylene layer having a melting point higher than that of the ethylene-vinyl acetate copolymer and a film thickness from 1 to 10 m and the ethylene-vinyl acetate copolymer layer is further laminated on a base film such as a nylon layer.

KXW:1422y L- I -3- The ethylene-a-olefin copolymer layers as have been described hereinabove have good heat sealability, however, they are insufficient to sealability at low temperatures, sealability when with impurities, a range of sealing temperatures, sealing shrinkage and the like. The conventional multilayer films as have been described hereinabove are good in heat sealability, but they are poor in film forming and rigidity as well as inferior in formability, thus leading to insufficient packaging materials. Furthermore, a film containing vinyl acetate may generate an odor and shrink in a large degree during sealing so that it is insufficient in these respects.

SUMMARY OF THE INVENTION Therefore, the present invention has the object to provide a resin L laminate which is superior to sealability at low temperatures, oo 0 sealability of Impurities, and a resistance to pinholes and good in film 0 0 forming and convertibility. The resin laminate according to the present invention is particularly suitable for packing liquid materials.

'According to a broad form of the present invention there is provided a resin laminate comprising: a heat-sealable layer containing a random copolymer obtainable by copolymerizing ethylene with an a-olefin having from 4 to inclusive carbon atoms, having a density ranging from 0.900 to 0.915 g/cm and a melt index ranging from 5 to 50 grams per 10 minutes (190 0 and a polyolefinic resin layer having a tensile modulus of 4,000 S 25 kg/cm or higher and a melting point higher than that of the heat-sealable layer and a base film layer selected from the group consisting of an orientated or non-orientated film or sheet of a nylon, a polyester, a S polyvinyl alcohol or polypropylene, polycarbonate film, a metallic foil, and paper; wherein the heat-sealable layer is laminated on the polyolefinic resin layer and the polyolefinic resin layer is laminated on the base film on the surface of the polyolefin resin layer opposite to the surface thereof on which the heat-sealable layer is laminated.

BRIEF DESCRIPTION OF THE DRAWING FIGURE 1 is a cross-sectional view showing one example of the resin laminate according to the present invention.

KXW:1422y -r 4 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The resin laminate according to the present invention will be described more in detail.

The heat-sealable layer is composed of a layer of a random copolymer obtainable by copolymerizing ethylene with an a-olefin having from 4 to 10 inclusive carbon atoms. Such an a-olefin may include, for example, butene-l, pentene-l, hexene-l, 4-methylpentene-l, cotene-1, nonene-l, decene-1 or the like. The a-olefin as a comonomer unit of the random copolymer may be used singly or in combination thereof.

In accordance with the present invention, the random copolymer having the density and melt index within the specified ranges may be suitably chosen from the random copolymers constituted by the a-olefin S or a-olefins. A preferred random copolymer is a linear low density 4 polyethylene (LLDPE) containing an a-olefin unit.

S 15 The heat-sealable layer may additionally contain a low-crystallinity or non-crystalline ethylene-a-olefin copolymer in an amount ranging up to 30% by weight with respect to the total weight of the heat-sealable layer in order to improve an impact resistance as long as its heat-sealability is not impaired. Such a low-crystallinity or non-crystalline ethylene-a-olefin copolymer may include, for example, ethylene-propylene rubber (EPR), ethylene-propylene-diene rubber (EPDM), and low-crystallinity ethylene-butene-l copolymer.

The heat-sealable layer has a density ranging generally from 0.900 to 0.915 g/cm 3 and a melt index ranging generally from 5 to grams per 10 minutes (190 0 preferably from 6 to 20 grams per minutes (190 0

C).

If the heat-sealable layer has a density below the lower limit of 0.900 g/cm 3 rigidity and heat sealability of a laminated film may be reduced, while the heat-sealable layer having a density above an upper limit of 0.920 g/cm makes the resulting laminated film poor in heat sealability at low temperatures and impact strength. If the heat-sealable layer has a melt index smaller than the lower limit of g/10 minutes, its melt viscosity becomes too large and formability is impaired and, if it has a melt index larger than the upper limit of g/10 minutes, strength between the heat-sealed portion of the resulting film becomes too weak, thereby reducing a film strength. It is further to be noted that, although a melt index for a usual film grade is lower KXW:1422y 5 than 4 g/10 minutes (190 0 the heat-sealable layer having a melt index larger than 4 g/10 minutes (190°C) is of note to be used for the resin laminate according to the present invention. A provision of the heat-sealable layer having a melt index larger than the usual film grade serves as achieving the object of the present invention.

A film thickness of the heat-sealable layer may range generally from 2 to 15[m, preferably from 2 to 10.m. The heat-sealable layer having a film thickness thinner than the lower limit becomes poor in film forming while a film thickness larger than the upper limit may cause shrinkage during sealing.

It is further preferred that the heat-sealable layer has a 2 tensile modulus ranging preferably from 1,000 to 4,000 kg/cm 2 The heat-sealable layer having a tensile modulus below the lower limit 1,000 kg/cm makes film strength weaker, while the heat-sealable layer S 15 having a tensile modulus greater than the upper limit 4,000 kg/cm may adversely affect its heat sealability.

The polyolefinic resin layer is composed of a layer of a polyolefic resin which may include, for example, a polyethylene such as a high density polyethylene, middle density polyethylene, low density polyethylene or linear low density polyethylene, a polypropylene such as an isotactic polypropylene, syndiotactic polypropylene or atactic polypropylene, a polybutene, or poly-4-methylpentene-1 etc. A copolymer of an olefin with a vinyl monomer may be used which may include, for example, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, 25 ethylene-vinyl chloride copolymer or propylene-vinyl chloride copolymer etc. As polyolefins may be used the polyolefins which are chemically denatured by an unsaturated carboxylic acid or an anhydride thereof or a Soe.4° derivative thereof. Preferred are a high density poly-ethylene, a linear low density polyethylene (LLDPE), a polypropylene, polybutene-1 and poly-4-methylpentene-l, each having a density of 0.920 g/cm or.higher.

The polyolefinic resin layer has a tensile modulus or 4,000 kg/cm 2 or higher, preferably from 4,000 to 12,000 kg/cm If its 2 tensile modulus becomes smaller than the lower limit of 4,000 kg/cm, the film strength of the resulting film becomes smaller. If it exceeds 2 the upper limit of 12,000 kg/cm 2 its heat sealability may become poor.

The heat-sealable layer and the polyolefinic resin layer (B) may additionally contain a variety of additives as long as they do not KXW:1422, I 6 Sadversely affect the object sought to be achieved by the present invention. The additives may include, for example, a lesser soluble azo dye, a red colorant, a colorant such as cadmium yellow, chrome yellow, white titanium pigment, an antioxidant such as of a triazole, salicylate, or acrylonitrile type, a plasticizer such as phthalate diester, butanol diester, phosphate diester or the like, and a thermal stabilizer.

It is further to be noted that the melting point of the polyolefinic resin be higher than the heat-sealable layer having 2 2 4,000 kg/cm 2 preferably 4,000 to 12,000 kg/cm 2 A difference of the melting point of the polyolefinic resin from that of the heat-sealable layer may vary with the composition of the heat-sealable layer The melting point of the polyolefinic resin layer may range generally from 120 0 C to 1600C.

The polyolefinic resin layer may have a film thickness ranging generally from 5 to 200gm, preferably from 10 to 100gm.

The resin laminate according to the present invention may be prepared by coextruding the heat-sealable layer with the polyolefinic layer by means of T-die extrusion forming, inflation extrusion forming or the like at a resin temperature ranging from 180 0 C to 300°C and cooling the laminated material by means of chill rolls at a temperature of 20 0 C to 80°C. In laminating the heat-sealable layer (A) on the polyolefinic layer it is preferred that a surface of the polyolefinic layer to be laminated is surface-treated by means of surface oxidation treatment such as corona discharge treatment, chromate i 25 treatment, flame treating, hot-air treating, treatment with ozone or i ultraviolet rays or the like, or surface abrasion treatment such as sand blasting. Preferred is corona discharge treatment.

S, The resin laminates according to the present invention comprise a three-layer laminate in which a base film is laminated on a surface L 30 of the polyolefinic resin layer opposite to the surface thereof on which the heat-sealable layer is laminated. The base film may include, for example, a nylon such as nylon-6, a polyester such as polyethylene terephthalate, a polyvinyl alcohol such as a saponified ethylene-vinyl acetate copolymer, a oriented or non-oriented film or sheet of polypropylene or the like, polycarbonate film, aluminium foil or other metallic foil, or paper. The base film may be of a single layer or multiple layers. It may vary with usage of the resin laminates, however, it may have a film thickness generally from 10 to 100gm.

KXW:1422y

I

-7- The multilayer resin laminates according to the present invention may be prepared by means of any laminating procedures forming a laminated structure in a film or sheet, such as coextrusion laminating, dry i laminating, hot laminating, hot melt laminating, extrusion laminating or the like. It is to be noted herein that, when the base film is laminated on the polyolefinic resin layer it is preferred to subject a laminating surface thereof to surface treatment as have been described hereinabove, particularly corona discharge treatment.

The base film serves as providing the resin laminate with an improved mechanical strength such as rigidity and the heat-sealable layer containing the random copolymer is excellent in heat sealability.

Thus the packaging bags formed from the laminates are suitable for packing granular or liquid matters such as food, beverages, cement, sand or the like.

The present invention provides resin laminates which are excellent in sealability at low temperatures, sealability having impurities and sealing for filling liquid matter and which shrink little in sealing.

The heat-sealed products give a favorable outlook of a heat-sealed portion without pinholes, a high sealing strength, and a good impact strength. The resin laminates according to the present invention are remarkably favorable in film forming, laminating, printability, and forming into packaging materials although they are highly sealable at low temperatures. Thus the resin laminates according to the present invention can be employed effectively for a sealant for multilayer films as packaging materials and for packing various matters as packaging bags.

The present invention will be described by way of examples.

SExample 1: *'Using a resin as shown in Table 1 below, there was formed a resin S laminate having a heat-sealable layer and a polyolefinic resin layer in the following manner.

The heat-sealable layer and the polyolefinic resin layer (B) were each molten and extruded through an extruder having a 50mm nozzle and a 65mm nozzle, respectively, to a multi-manifold multilayer T-die (a die width: 800 mrm) which, in turn, coextruded at the die temperature of 250°C and cooled by means of chill rolls at 40°C, thereby forming a multilayer film comprising the heat-sealable layer having a film thickness of 7[m and the polyolefinic resin layer having a film thickness of 43|Lm.

KXW:1422y ~l~ll~__a_7 -8- The multilayer film was measured for its tensile modulus and sealing temperature. The results are shown in Table 2 below. It is noted herein that the sealing temperature was measured as its heat-sealing strength has amounted to 300 grams per 15mm in substantially the same manner as will be described below as "Idemitsu Test Method".

The multilayer film thus obtained was then laminated on an oriented nylon film with 15 Lm thickness, yielding a laminated film. The resulting resin laminate has a structure as shown in FIGURE 1 in which reference numeral 1 denotes the heat-sealable layer containing the ethylene-a-olefin random copolymer, reference numeral 2 denotes the polyolefinic resin layer and reference numeral 3 denotes the base film The properties of the laminated film are shown in Table 2 below.

Example 2: 15 A heat-sealable layer containing the random copolymer as shown in Table 1 above and the polyolefinic resin layer were laminated in the same manner as in Example 1 to give a multilayer film.

A surface of the polyolefinic resin layer of the resulting multilayer film was then subjected to corona discharge treatment at 28W/m2/minute. The surface of the polyolefinic resin layer was coated with an adhesive and then laminated in dry manner with an oriented Snylon film having a film thickness of 15Rm, thereby producing a laminated film. The resulting laminated film has a three-layer structure as shown in FIGURE 1.

The properties of the resulting laminated film are shown in Table 2 below.

Example 3: *4 A heat-sealable layer containing the random copolymer as shown in Table 1 below and the polyolefinic resin layer were laminated in the same manner as in Example 1 to give a multilayer film.

The multilayer film was measured for its tensile modulus and sealing temperature. The results are shown in Table 2 below. It is noted herein tlat the sealing temperature was measured as its heat-sealing strength has amounted to 300 grams per 15mm in substantially the same manner as will be described below as "Idemitsu Test Method".

The multilayer film was then laminated on an oriented nylon film to give a laminated film as shown in FIGURE 1. The properties of the KXN:1422y _LC I_ I C=rci -9laminated film are shown in Table 2 below.

Comparative Examples 1 In the same manner as in Examples 1 to 3, a heat-sealable layer (A) containing the resin as shown in Table 1 below was laminated on the polyolefinic resin layer by coextrusion, thus yielding a multilayer film which, in turn, was laminated on an oriented nylon film so as to bring the polyolefinic resin layer to come in contact with the nylon film in the same manner as in Examples 1 to 3, thereby giving a laminated film.

In Comparative Examples 1 and 4, the resulting multilayer film was measured for its tensile strength and sealing temperature. The sealing temperature was measured in accordance with the "Idemitsu Test Method" as oo will be described hereinbelow. The results are shown in Table 2 below.

OoOo In Comparative Examples 2, 3 and 5, the resulting multilayer film S 15 was then laminated on a drawn nylon film yielding a laminated film.

The properties of the laminated film are shown in Table 2 below.

0oo° As will be apparent from Table 2 below, the resin laminates o, obtained in Examples 1 to 3 have a sealing temperature lower than, a range of sealing temperatures wider than, and a sealing shrinkage smaller than those obtained in Comparative Examples 1 to Evaluation Procedures: The multilayer film having a two-layer structure consisting of the heat-sealable layer and the polyolefinic resin layer as well as the laminated film having at least three layers containing the base film S 25 in addition to the above two layers have been evaluated for their properties by the following procedures: *1.Sealing Temperature (Idemitsu Test Method): 0 One sheet of the multilayer film was laminated on another sheet of the multilayer film such that their respective heat-sealable layers (A) were heat-sealed at a pressure of 2 kg/cm 2 over the period of 1 second. The sealing temperature was measured using a heat gradient tester (Toyo Seiki K. as the temperature when a heat-sealing strength between the respective heat-sealable layers reached 2,000 grams per *2.Sealabilitv of Foreign Matter When salad oil was filled as foreign matter, the sealing temperature was measured in substantially the same conditions as above.

KXW:1422y _7 10 *3.Sealabilitv of Foreign Matter (II): When soy sauce was filled as foreign matter, the sealing temperature was measured in substantially the same conditions as above.

*4.Range of Sealing Temperatures for Filling: A packaging bag (600 mm x 70 mm) was filled with soy sauce at the filling rate of 80 bags per minute in a single roll system using a filling packer (half-folding, three-sided sealing filler: Model "KS 324"; Komatsu Seisakusho To the bag filled with soy sauce was then applied a load of 100 kg, and a range of sealing temperatures was measured at which the sealing temperatures can endure the load of 100 kg for five minutes or longer.

Shrinkage: The multilayer films were laminated at the sealing temperature of 145*C at the above filling conditions to give a packaging bag. The sealing shrinkage was calibrated as follows: Sealing Thickness of Sealed Portion o a 0 0 o o S* 0 ft S Shrinkage x 100 Total thickness of laminate 0I, 0 4 4 KXW:1422y I 2 11 TABLE 1 tft ft tftt (ft Density Melt g/cm 3 Index Tensile Melting min, Strength Point RESINS (1900C) kg/cm 2 (OC) Ethyl ene-axolefin copolymer LLDPE I (Idemitsu 0.905 9 2,100 118 Sekiyu Kagaku) MORETEC 1018C (08) ditto LLDEP 2 MORETEC 02580 0.930 2 6,400 125 (C8) -ditto- LLDEP 3 MORETEC 0238C 0.920 2 4,300 122 (C8) High Density Polyethyl ene HDPE (Idemritsu 0.954 0.9 11,000 131 Sekiyu Kagaku)

IDEMITSU

POLYETHY 440M Ethyl ene-butene-l EBC *1 copolymner*) 0.88 4 Ethylene- EVA*2 vinyl acetate 0.927 3 96 copol ymer *2: Mooney viscosityM L 1+4 18 (1f-DOC) Content of vinyl acetate unit is 7 wt% in the copolymer.

KXW': 1422y C -CC

L*

p r I

OII~

D00 .011 ftl 111 -9n r err r TABLE 2 MULTILAYER FILM LAMINATED FILM (ORIENTED NYLON/MULTILAYER FILM 15/50pnmn) (R L L S T C K T II IC K NESS =7/43pm) COMPOSITION BY WT) ROLLSTOCK PROPERTIES PRACTICAL PROPERTIES IN-INPURITIES PROPERTIES TENSILE SEALING 1 2 3 4 LAYER A LAYER B MODULUS TEMP. SEALING SEALABILITY SEALABILITY RANGE OF SEALING (Kg/cm TEMP. IN-INPURITIES IN-INPURITIES SEALING TEMP. SHRINKAGE REMARKS (oC) (II) FOR FILIG EX. 1 LLDPE 1 LLDPE 2 4500 97 100 114 117 125~150 95 DRY LAMINATED FILM LLDPE 1,(80) EX. 2 LLDPE 2 4300 92 95 110 113 120,150 80 DRY LAMINATED FILM EBC, (20) EX. 3 LLDPE 1,(90) HDPE 8500 95 98 112 115 123-150 90 DRY LAMINATED FILM CO.EX. LLDPE 2 LLDPE 3 2200 122 125 135 138 145-150 90 DRY LAMINATED FILM 1 CO.EX. LLDPE 2 LLDPE 2 5000 123 126 135 138 145-150 90 DRY LAMINATED FILM 2 CO.EX. LLDPE 3 LLDPE 3 1800 106 110 120 130 140'-150 70 DRY LAMINATED FILM 3 CO.EX. LLDPE 2 HDPE 9000 125 128 137 139 145-150 90 DRY LAMINATED FILM CO.EX. EVA EVA 1500 94 98 120 125 145 ~160 45 DRY LAMINATED FILM 5 KXW:1422y ~I i i 13 Example 4 The CA-1 and LLDPE 2 resin were used and there was formed a resin laminate having a CA-1 resin layer and a LLDPE 2 resin layer in the same manner as Example 1 of the present application.

The CA-1 corresponds to the resin used in Comparative Example 3 of CA 1124216. The properties of the CA-1 re-sin is shown in Table 3.

LLDPE 2 is same resin used in the present application and its properties is shown in Table 1.

The produced resin laminate was measured for its tensile modulus and sealing temperature in the same manner as Example 1 of the present application. The results are shown in Table 4 below.

Moreover, an oriented nylon film is laminated on this produced resin laminate in the same manner as Example 2 of the present application. The resulting laminated film has a three-layer structure and the properties of the resulting three-layer laminated film are shown in Table 4 below.

Comparative Example 6 The RJ-l resin was used and there was formed a resin laminate having two RJ-1 resin layers in the same manner as Example 1.

The RJ-l corresponds to the resin used for a heat-sealable layer in the Examples of EP 258527. The properties of the RJ-1 resin is shown in Table 3.

QComparative Example 7 The MO-1 and the MO-2 resins were used and there was formed a resin laminate having a MO-1 resin layer and a MO-2 resin layer in the same manner as Example 1 of the present application.

The MO-1 and the MO-2 correspond to the resin used for a skin layer and a core layer in Example 1 of EP 2606, respectively. The properties of the MO-1 and the MO-2 resins are shown in Table 3.

KXN:1422y i I 14 The produced resin laminate was measured for its tensile modulus and sealing temperature in the same manner as Example 1 of the present application. The results are shown in Table 4 below.

Comparative Example 8 The MI-1 and the MI-2 resins were used and there was formed a resin laminate having a MI-l resin layer and a MI-2 resin layer in the same manner as Example 1 of the present application.

The MI-1 and the MI-2 corresponding to the resin used for a covering layer and a core layer in Example 1 of EPA 50,455, respectively. The properties of the MI-1 and the MI-2 resins are shown in Table 3.

The produced resin laminate was measured for its tensile modulus So and sealing temperature in the same manner as Example 1 of the present application. The results are shown in Table 4 below.

BOi, 25 Comparative Example 9 The MI-3 and the MI-4 resins were used and there was formed a resin laminate having a MI-3 resin layer and a MI-4 resin layer in the same manner as Example 1 of the present application.

The MI-3 and the MI-4 correspond to the resin used for a covering layer and a core layer in Example 4 of EPA 50,455, respectively. The properties of the MI-3 and the MI-4 resins are shown in Table 3.

The produced resin laminated was measured for its tensile modulus and sealing temperature in the same manner as Example 1 of the present application. The results are shown in Table 4 below.

KXW:1422y i I- I i 15 TABLE 3 RESINS Density Melt Index Tensile Melting g/cm 3 g/lOmin. Strength Point (190 0 C) kg/cm 2 CA-1 E4MP 0.910 2 2800 119 (94.3mol% ethylene/ 5.8 mol% 4-methyl- 1-pentene copolymer) RJ-l LD:HD LD 0.925 1.3 5500 115 =20:80 HD 0.960 1.15 12000 132 MO-1 98.0% ethylene 0.925 3.0 6000 124 4-methyl penten-1 copolymer MO-2 oriented 0.905 4.5 20000 160 polypropylene MI-1 EMC-I 0.922 2.48 4500 122 (ethylene/ 4methyl-1- -pentene copolymer) MI-2 HDPE-I 0.954 1.2 11000 131 MI-3 EMC-III 0.916 2.1 3500 120 MI-4 HDPE-III 0.952 0.8 11000 131 .CA-1 corresponds to the 1124216.

.RJ-1 corresponds to the or an intermediate layer .MO-1 corresponds to the 2606.

.MO-2 corresponds to the 2606.

.MI-1 corresponds to the Example 1 in EP 50455.

resin used in C resin used for in Examples in resin used for :omparative Example 3 in CA the heat-sealable surface EP 258527.

the skin layer in Example layer 1 in EP resin used for the core layer in Example 1 in EP resin used for the covering layer in KXN:1422y

I

2

V.

a It $2 16 .MI-2 corresponds to the resin used for the core layer in Example 1 in EP 50455.

.MI-3 corresponds to the resin used for the covering layer in Example 4 in EP 50455 .MI-4 corresponds to the resin used for the core layer in Example 4 in EP 50455.

KXW:1422y TABLE 4 TWO-LAYER RESIN LAMINATE (MULTILAYER FILM) THREE-LAYER LAMINATED FILM (ORIENTED NYLON/MULTI LAYER FILM =15/50jLmm) ROLLSTOCK THICKNESS I(B) 7/43un) COMPOSITION BY VIT) ROLLSTOCK PROPERTIES PRACTICAL PROPERTIES IN-INPURITIES'PROPERTIES TENSILE SEALING 1 2 *3 LAYER A LAYER B MODULUS TEMP. SEALING SEALABILIT', SEALABILITY RANGE OF SEALING (Kg/cm) TEMP. IN-INPURI'iES IN-IMPURITIES SEALING TEMP. SHRINKAGE REMARKS (IC) (II) (IC) FOR FILIG M% EX. 4 CA-i LLDPE 2 4600 98 100 115 118 125 v 150 95 DRY L.MINATED FILM CO.EX. RJ-1 RJ-1 10500 130 132 140 143 145-150 90 DRY LAMINATED FILM4 6 CO.EX. MO-i MO-2 17000 120 124 134 136 150 -'160 90 DRY LAINATED FILM 7 CO.EX. HI-1 MI-2 8800 108 112 122 125 140 -'i50 70 DRY LAMINATED FILM 8 MI-4 140-150 DRY LAMINATED FILM 8600 KXW: 14 2 2 y

Claims

1. A resin laminate comprising: a heat-sealed layer containing a random copolymer obtainable by copolymerizing ethylene with an a-olefin having from 4 to 10 inclusive carbon atoms, having a density ranging from 0.900 to 0.915 g/cm 3 and a melt index ranging from 5 to 50 grams per 10 minutes (190 0 and a polyolefinic resin layer other than a linear low-density polyethylene, said layer having a tensile modulus of 4,000 kg/cm 2 or higher and a melting point higher than that of the heat-sealable layer and a base film layer selected from a group consisting of an orientated or non-orientated film or sheet of a nylon, a polyester, a and paper; wherein the heat-sealable layer is laminated on the W polyolefinic resin layer and the polyolefinic resin layer is laminated on the base film on the surface of the polyolefin resin layer opposite to the surface thereof on which the heat-sealable layer is laminated.

2. A resin laminate as claimed in claim 1, wherein the heat-sealable layer comprises a linear low density polyethylene (LLDPE) containing an a-olefin unit or a mixture of a linear low density polyethylene (LLDPE) in an amount of 70% by weight or larger with respect to the total weight of the heat-sealable layer with a low-crystallinity ethylene-butene-l copolymer in an amount of 30% by weight or lower with respect to the total weight thereof.

3. A resin laminate as claimed in claim 1 or claim 2, wherein the base film layer is a nylon film.

4. A resin laminate as claimed in any one of claims 1 to 3, 4 30 wherein the heat-sealable layer has a film thickness ranging from 2 Sto 15 pm.

A resin laminate as claimed in any one of claims 1 to 4, wherein the heat-sealable layer has a film thickness ranging from 2 to 10 pm.

6. A resin laminate as claimed in any one of claims 1 to 1604F/jj 19 wherein the heat-sealable layer has a film thickness ranging from to 200 im.

7. A resin laminate as claimed in any one of claims 1 to 6, wherein the polyolefinic resin layer has a film thickness ranging from 10 to 100 Rm.

8. A resin laminate as claimed in any one of claims 1 to 7, wherein the base film has a film thickness ranging from 10 to 100 Rm.

9. A resin laminate as claimed in claim 1, substantially as hereinbefore described with reference to Fig. 1 or Example 3. DATED this SIXTH day of NOVEMBER 1992 Idemitsu Petrochemical Company Limited o a Patent Attorneys for the Applicant SPRUSON FERGUSON i '6 1604F/jj