JPS6317946A - Modified linear low-density polyethylene composition - Google Patents

Abstract

PURPOSE:The titled composition having improved high-temperature adhesiveness, comprising a linear low-density polyethylene derived from 5-10C alpha-olefin and a modified linear low-density polyethylene derived from 3-4C alpha-olefin. CONSTITUTION:(A) A linear low-density polyethylene which contains 0.1-10mol% unit derived from 5-10C alpha-olefin, has 0.1-10g/10min melt index and 0.91-0.94g/cm<3> density and/or a modified material thereof with an alpha,beta-unsaturated carboxylic acid is blended with (B) a modified material obtained by grafting 0.1X10<-4>-4.5X10<-4>mol alpha,beta-unsaturated carboxylic acid onto 1g linear low-density polyethylene which contains 0.1-10mol% unit derived from 3-4C alpha-olefin (preferably butene-1), has 0.1-20g/10min melt index and 0.9-0.95g/cm<3> density in the weight ratio of the component A:B=60:40-99:1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a novel modified linear low density polyethylene composition with improved adhesive performance at high temperatures.

[Background of the Invention] Linear low-density polyethylene is a thermoplastic resin with excellent properties such as thermal stability, chemical resistance, moldability, and weather resistance, and is used in blow molded products, injection molded products, films, fibers, and It is widely used as laminated film for food packaging. For example, laminated films used for food packaging etc. have α-carbon atoms of 3 to 4.
A laminated film of linear low-density polyethylene copolymerized with olefin and a polymer compound such as nylon is used. In the case of such a laminated film, since the adhesion of linear low-density polyethylene to a polymer compound such as nylon is poor, linear low-density polyethylene that has been graft-polymerized with a polar substance such as maleic anhydride, Alternatively, a material to which an adhesive component such as a rubber-like substance is added is used.

Recently, laminated films using linear low-density polyethylene as mentioned above have been used for retort food or simple retort food (
In the present invention, they are increasingly being used for packaging food products (hereinafter, both may be collectively referred to as "retort food").

Retort food is generally made into a bag by heating and press-bonding a laminated film formed into a cylinder with a linear low-density polyethylene layer on the inside and a nylon layer on the outside. After filling the contents, heat and press the inlet to seal it, then place it in a pressure cooker or the like in this state for heat sterilization (for retort food, heat sterilize it for 12 hours).
The product is packaged and sterilized by heating water at a temperature of around 0°C, or in the case of simple retort food, around 100°C. Therefore, the laminated film used for such packaging must not only have good heat resistance but also good adhesive strength even at high temperatures. Furthermore, in addition to such heat resistance and adhesion at high temperatures, a unique characteristic required for laminated films for packaging retort food is that the crimped and heated portions do not peel off due to contact with heated water during heat sterilization. Considering the heat sterilization method, laminated films for packaging retort foods are usually immersed in heated water of 100°C or higher under pressure for at least 30°C. It is necessary to have hot water-resistant adhesion to the extent that the heat-pressed portion does not peel off even when contacted for minutes.

When forming a laminated film using linear low-density polyethylene in this way, a composition is used in which a rubber-like substance is added to a modified product obtained by graft polymerization of an α, β-unsaturated carboxylic acid component such as maleic anhydride. (For example, see Japanese Patent Publication No. 60-11056).

This composition contains a modified linear low-density polyethylene and a rubbery substance, so it has properties that allow it to be used for packaging retort foods. It has been found that there is a problem in that blocking is likely to occur. Therefore, when producing a laminated film using this composition, there is a problem in that it is necessary to make special improvements to the equipment or to add an anti-blocking agent to prevent the films from adhering to each other.

Therefore, the present inventor developed a linear low-density polyethylene that has heat-press bonding properties that can be advantageously used for packaging retort food while maintaining the excellent properties of linear low-density polyethylene without adding any rubbery substances. When we examined the composition, we found that the base linear low-density polyethylene was an α-olefin with a carbon number in the range of 5 to 10, rather than the conventionally used α-olefin with a carbon number of 3 to 4. Linear low-density polyethylene, which is a copolymer of I found out that there is. Furthermore, it has been found that this linear low-density polyethylene is equivalent to or better than conventional linear low-density polyethylene in other properties that linear low-density polyethylene inherently has, such as moldability.

The present inventor has developed a method for imparting adhesive properties to linear low-density polyethylene, which is obtained by copolymerizing α-olefin with a larger number of carbon atoms than the above-mentioned conventional products, while maintaining its excellent properties. Initially, a method was attempted in which this linear low-density polyethylene was modified by graft polymerization with an α,β-unsaturated carboxylic acid modifier, and the modified product was used as an adhesive component.

However, in conventional methods, as the number of carbon atoms in the α-olefin increases, the grafting efficiency of the α, β-unsaturated carboxylic acid modifier tends to decrease, and α-olefins with a large number of carbon atoms tend to copolymerize. It has been difficult to produce a modified product with sufficient adhesive properties using linear low-density polyethylene. Furthermore, when modification is carried out at a high concentration by increasing the amount of α, β-unsaturated carboxylic acid modifier added, the decomposition reaction of linear low-density polyethylene progresses, producing a modified product with the desired properties. It was difficult to do so. That is, it is difficult to produce an α,β-unsaturated carboxylic acid modified product of linear low-density polyethylene that has the property of imparting good adhesion to a composition using a conventional method. could not be used. Also, α.

An attempt was also made to use alone a linear low-density polyethylene modified product in which a β-unsaturated carboxylic acid modified component was graft-polymerized at a low concentration, but although this product had sufficient adhesion even under normal conditions, It turns out there isn't.

[Objective of the Invention 1 The object of the present invention is to provide a novel adhesive modified linear low-density polyethylene composition with improved adhesive performance at high temperatures.

More specifically, the present invention provides a modified linear low-density polyethylene composition that maintains the essential properties of linear low-density polyethylene and has both good adhesive strength at high temperatures and hot water-resistant adhesive strength. The purpose is to

[Summary of the Invention] The present invention provides a linear low density polyethylene I containing repeating units derived from an α-olefin I having 5 to 10 carbon atoms and/or an α,β-unsaturated carboxylic acid modified product thereof; α, β of linear low density polyethylene II containing repeating units derived from α-olefin II of number 3 or 4
-Unsaturated carboxylic acid modified product: 60:40-99:
The modified linear low-density polyethylene composition is characterized in that the composition contains the following:

[Effects of the Invention] The modified linear low-density polyethylene composition of the present invention can be obtained by selecting an α,β-unsaturated carboxylic acid modified product of linear low-density polyethylene II (second component) as an adhesive component. In addition to showing good adhesive performance, the addition of this second component improves the excellent properties of linear low-density polyethylene I (first component) such as heat resistance, moldability, thermal stability, chemical resistance, and weather resistance. properties are not impaired.

The composition of the present invention exhibits excellent hot water-resistant adhesion without peeling even if the heat-pressed portion comes into contact with heated water for a long time.

Furthermore, the good adhesion performance of the composition of the present invention is particularly noticeable at high temperatures, and when it is based on ordinary linear low-density polyethylene, a significant decrease is seen at 100°C.
Adhesive strength is less affected by temperature than conventional adhesives.

[Detailed Description of the Invention] The modified linear low-density polyethylene composition of the present invention comprises, as a first component, linear low-density polyethylene I or its repeating unit derived from an α-olefin having 5 to 10 carbon atoms. Linear low-density polyethylene II containing an α, β-unsaturated carboxylic acid modified product and, as a second component, a repeating unit derived from an α-olefin having 3 or 4 carbon atoms.
α of

It contains a β-unsaturated carboxylic acid modified product in a specific weight ratio.

The linear low-density polyethylene I, which is the first component, consists of ethylene and α-carbon atoms having 5 to 10 carbon atoms (preferably 6 to 8 carbon atoms).
A linear low density polyethylene containing repeating units derived from olefins. The α-olefin I constituting the linear low-density polyethylene may be linear or branched;
As examples, mention may be made of pentene-1, hexene-1,4-methyl-pentene-1 and octene-1.

Such repeating units derived from α-olefin I are contained in the linear low-density polyethylene I at a content usually within the range of 0.1 to 10 mol% (preferably 1 to 5 mol%). . The repeating unit derived from α-olefin I may be present alone or in combination in the linear low density polyethylene I.

Linear low density polyethylene I containing repeating units derived from α-olefin I usually has a melt index of 0.1 to log/10 min (preferably 1 to 6 g/l).
1 minute) and the density is within the range of 0.91 to 0-9
4g/c (preferably 0.91~(193g/c)
Linear low density polyethylene within the range of Furthermore, the melting point of this linear low density polyethylene I is usually 115
~'230°C.

Such a method for producing linear low density polyethylene is already known, and in the present invention, one produced by a known method can be used.

In addition to the linear low-density polyethylene I described above, the first component of the present invention may be an α,β-unsaturated carboxylic acid modified product of the linear low-density polyethylene I; and linear low-density polyethylene I.

However, according to studies by the present inventors, as the number of carbon atoms in the α-olefin constituting the linear low-density polyethylene I increases, the α,β-unsaturated carboxylic acid modifier tends to make graft polymerization difficult. When modified at a high concentration, it becomes difficult to maintain the properties of linear low-density polyethylene I, so this α,β-unsaturated carboxylic acid modified product is usually used as a linear low-density polyethylene I of Ig. A modified product in which not more than 0,1×10 −' moles of α,β-unsaturated carboxylic acid modifying component is graft-polymerized with respect to the target is used. If the amount of grafting of the α,β-unsaturated carboxylic acid modification component is too large, properties such as heat resistance may deteriorate, the melt index will further decrease, and the gelation content will increase, so the resulting composition may be molded. Sexuality may decrease.

The melt index of this α,β-unsaturated carboxylic acid modified product tends to be somewhat lower than that of the base linear low density polyethylene, but it is usually within the above range. Furthermore, the density and melting point of the modified product are generally within the same range as those of the linear low-density polyethylene I, since the density and melting point are not significantly changed by the above-mentioned low concentration of modification.

Note that the modifier used to produce the α,β-unsaturated carboxylic acid modified product of linear low-density polyethylene I is the same as that used for producing the α,β-unsaturated carboxylic acid modified product of linear low-density polyethylene II, which will be described later. The modifier used in the process can be used, and the production can be carried out in the same manner.

Note that linear low-density polyethylene I is composed of ethylene and α
- In addition to the repeating unit derived from olefin I, it may contain other monomer components within a range that does not impair its properties.

This first component allows the composition of the invention to have good heat resistance.

The second component of the modified linear low density polyethylene composition of the present invention is an α,β-unsaturated carboxylic acid of linear low density polyethylene II containing repeating units derived from α-olefin II having 3 or 4 carbon atoms. It is a denatured product.

α-Olefin that constitutes linear low-density polyethylene■
has 3 or 4 carbon atoms.

Therefore, α-olefin ■ is propylene and butene-
It is 1. The linear low-density polyethylene (■) may contain a single repeating unit derived from α-olefin II or may contain two types of repeating units, and α-olefin (■) may be butene-1. preferable. Such α−
The repeating unit derived from olefin II is contained in the linear low density polyethylene (2) at a content usually in the range of 0.1 to 10 mol% (preferably 1 to 5 mol%).

Linear low density polyethylene (2) containing repeating units derived from such α-olefin II usually has a melt index of 0.1 to 20g710min (preferably l-1
01 to 1O min), and the density is 0.90
~0.95g/c (preferably 0.91~0.93g)
It is a linear low density polyethylene within the range of /c). Furthermore, the melting point of such linear low density polyethylene II is usually within the range of 115 to 230''.

Such a method for producing linear low density polyethylene is already known, and in the present invention, one produced by a known method can be used.

The second component of the composition of the present invention is a modified product of linear low density polyethylene II modified with α,β-unsaturated carboxylic acid, and the α,β-unsaturated carboxylic acid modifier used for this modification is By way of example, mention may be made of acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid and their possible acid anhydrides, as well as their derivatives. In addition, two or more kinds of modifiers can also be used. Among these, maleic acid or maleic anhydride is preferably used as the α,β-unsaturated carboxylic acid modifier.

The second component is usually 0, I X 10-' to 5
This is a modified product in which an α,β-unsaturated carboxylic acid modifying component is graft-polymerized in an amount within the range of 4 moles. Zarani o, l
A modified product in which an α,β-unsaturated carboxylic acid modification component is graft-polymerized in an amount within the range of
α, β- in amounts ranging from 0-' to 2-OXIO-' molar
A modified product in which an unsaturated carboxylic acid modified component is graft-polymerized is suitable. This modified substance mainly imparts adhesive properties to the composition of the present invention, so if the amount of grafting is small, the resulting composition may have insufficient adhesive strength; If too much of the modified substance is used, it may gel during the graft polymerization reaction and the melt index may decrease, resulting in a decrease in moldability of the resulting composition.

The melt index of this linear low density polyethylene II (7) α, β-unsaturated carboxylic acid modified product is usually 0.1 to
20g710min (preferably o, i~10g710min)
The density is usually within the range of 0.90 to 0-95g/c
(preferably 0.91 to 0.93 g/CrrI''), and the melting point is usually within the range of 115 to 230°C.

In addition, linear low density polyethylene ■ is α-olefin I
In addition to the repeating unit derived from I, it may contain other monomer components within a range that does not impair its properties.

Such an α,β-unsaturated carboxylic acid modified product of linear low density polyethylene II is usually prepared by combining the linear low density polyethylene II and the α,β-unsaturated carboxylic acid modifier in the presence of a reaction initiator. It can be manufactured by melt-kneading.

The amount of α, β-unsaturated carboxylic acid modifier to be used is determined by the high reactivity of the linear low density polyethylene ■ with the modifier.
Usually, use ml-1.5 times the amount of grafting planned.

As the reaction initiator, a commonly used organic peroxide-based reaction initiator such as t-butyl hydroperoxide is used. In addition to organic peroxides, 2,3-
It is also possible to use dimeric dimers and derivatives thereof, such as dimethyl-2,3-diphenylbutane. Since such a reaction initiator has a milder reaction initiation mechanism than an organic peroxide-based reaction initiator, it is possible to reduce the occurrence of gelation and decrease in melt index due to denaturation. As a two-component reaction initiator (and
It is suitable as a reaction initiator when an α,β-unsaturated carboxylic acid modified product of linear low density polyethylene I is used as the first component.

The reaction initiator is used in an amount within the usual range of usage (usually 0.01 to 0.1 times the molar ratio of the modifier used). By carrying out the graft polymerization reaction in this manner, more than % by weight of the normally used α,β-unsaturated carboxyl side modifier is graft-polymerized.

The modified linear low-density polyethylene composition of the present invention comprises linear low-density polyethylene I and/or its α, β-, β-carboxylic acid modified product as a first component, and a linear low-density polyethylene composition as a second component. Contains an α,β-unsaturated carboxylic acid modified product of polyethylene II in a weight ratio of 60:40 to 99:l, particularly when the weight ratio of the first component to the second component is 70:1.
: By setting the ratio within the range of 30 to 95:5, the adhesion at normal temperatures between the polymer compound and the composition of the present invention in a laminated film with another polymer compound such as nylon tends to be improved.

In the composition of the present invention, if the first component is small, the heat resistance will not be sufficiently improved, and if the second component is small, the adhesion will not be sufficiently developed. The effect of having good heat-resistant water adhesiveness and the effect of having good hot water adhesiveness are achieved by the composition of the present invention containing the first component and the second component within the above ranges.

The modified linear low density polyethylene composition of the present invention usually has a melt index of Ig 710 minutes or more (preferably 1 to
(within the range of 20g710min) and has a melting point of 115-13
Since it is within the range of 0°C, it has good extrusion molding performance. Furthermore, the density is usually 0.915-0.930g
/c is within the range.

In addition, when looking at the entire composition of the present invention, it is usually 0-IXlo-8 to 0.8 per gram of polyethylene component in the composition.
It is a composition in which X10-' moles of α, β-, β-carboxylic acid modifying components are graft-polymerized, and it not only has good adhesion to steel plates etc. (adhesion under static conditions), but also has good adhesion to steel plates etc. In the laminated film obtained by molding the composition of the present invention in the state of the present invention and another polymer compound such as nylon using an extrusion forming device, the adhesion between the polymer compound and the composition of the present invention ( Excellent adhesion under dynamic conditions).

In particular, the composition of the present invention has extremely superior adhesive performance under high temperature conditions when compared to conventional compositions.

In normal cases, adhesive performance at high temperatures is determined by bonding a laminated film under heat and pressure at a predetermined temperature (for example, 100°C).
It is evaluated by measuring the tension required to peel off the heat-pressed portion. However, when used for packaging retort food, for example, simply having high adhesive strength at high temperatures as described above is insufficient as a property, and evaluation using normal adhesive strength at high temperatures as described above is insufficient. In addition, the same conditions as for heat sterilization are required, i.e., the pressure contact area must not peel off even after a certain period of time in contact with high-temperature water, i.e., it must have good hot water-resistant adhesion. become.

The composition of the present invention has the following characteristics compared to conventional modified polyethylene compositions and modified linear low density polyethylene compositions:
This hot water resistant adhesive property is particularly excellent. Specifically, when heat-compression bonding is performed using the composition of the present invention as an adhesive layer,
It has an excellent property that the heat-pressed portion does not peel off for at least 30 minutes even when it comes into contact with 103° C. heated water in a pressure vessel. Therefore, when the composition of the present invention is used as an adhesive, the heat-pressed portion will not peel off due to contact with heated water during heat sterilization, etc., and the contents will not leak out.

Furthermore, for example, two laminated films obtained by extrusion molding nylon (polyamide resin) and the composition of the present invention so that the layer thicknesses are 201 Lm and 401 Lm, respectively, are placed so that the composition of the present invention faces each other. The test piece was heat-sealed under normal conditions (e.g., temperature 170°C, pressure 2 kg/c, time 1 second), and the T layer was peeled off at a temperature of 100°C and a peeling speed of 50 mm. When the test was conducted, the adhesive strength of the composition of the present invention was higher than the resin strength, so the resin (laminated film of nylon and the composition of the present invention) was cut before the heat-pressed portion peeled off. In other words, when such a laminated film is subjected to a tension of 1.0 kg/l-5 cm or more at 100°C, resin breakage occurs, but the adhesive strength of the heat-pressed portion is
Usually, it is 1-0 kg/l, 5 cm or more, and the heat-pressed part will not peel off before resin breakage occurs.

Therefore, the composition of the present invention is suitable for use as an adhesive for a laminated film for packaging retort food, which requires high hot water resistant adhesive strength and high adhesive strength at high temperatures.

The modified linear low-density polyethylene composition of the present invention can be produced by triblending the first component and the second component, and then melting the mixture and kneading it.

For triblending, a normal mixing device such as a Henschel mixer can be used, and for melt mixing, a normal melt mixing device such as a single screw extruder can be used.

In addition, for melt mixing, when using a single screw extruder, for example, the heating temperature is usually set within the range of 180 to 260°C, the residence time is set to 0.1 to 5 minutes, and nitrogen etc. It is carried out in an inert gas atmosphere.

In addition, at the time of melt mixing, other resin components or commonly used additives may be added in addition to the first component and second component to the extent that the characteristics of the composition of the present invention are not impaired. You can also do it.

Next, Examples and Comparative Examples of the present invention will be shown.

[Example 1] Melt index (MI) 2 + 2 g/10 minutes,
Linear low density polyethylene-I (LLD) with a density of 0.918 g/c, a melting point of 125 °C, and a content of 3.1 mol% of repeating units derived from 4-methyl-pentene.
PE-I) was prepared. The Vicat softening point of this LLDPE-I was 107°C.

Separately, the melt index is 2.0 g/10 minutes, the density is 0.
Linear low density polyethylene-n (LLDPE-n) with a melting point of 123 °C and a content of 3.6 mol% of repeating units derived from butene-1, and LLDP of Ig.
1 x 1 O-4 mol of maleic anhydride and 0.32 x 10-4 mol of 2,3-dimethyl-2,
3-diphenylbutane was mixed with a Henschel mixer, and the resulting mixture was extruded using a single screw extruder (screw diameter =
50 mm, L/D = 24), heated to 260° C. under a nitrogen atmosphere, and subjected to melt mixing for a residence time of about 1 minute to produce a maleic acid-modified linear low-density polyethylene-H.

The obtained maleic acid-modified product of LLDPE-n has a graft polymerization of o, 8 x 10-' mol of maleic anhydride to LLDPE-n of Ig, and has a melt index of (16 g, 710 minutes, and a density of 0.917 g). /crn”,
And the melting point was 119°C.

To the above 90 parts by weight of LLDPE-H, LLDPE-n
10 parts by weight of the maleic acid modified product was added and mixed, and melt blending was performed using the above-mentioned single screw extruder to produce a modified linear low density polyethylene composition.

The melt index of the obtained modified linear low density polyethylene composition was 1 to 9 g/710 min, and the density was 0.918 g/min.
crn'' and the melting point was 125°C.

[Example 2] In Example 1, the following is substituted for LLDPE-I. A modified linear low-density polyethylene composition was produced in the same manner except that LLDPE-I having the physical properties shown in Table 1 was used.

Melt index: 4-2g710 min Density: 0.92
2g/C melting point: 126°C Content of repeating units derived from octene-1: 2.4 mol% Vicat softening point: 109°C Melt index of the obtained modified linear low density polyethylene composition is 3.5g /10 minutes, density is 0.922g/
C, and the melting point was 126°C.

[Example 3] Using 0.1 x 10-4 mol of maleic anhydride and 0.1 x 10-4 mol of t-butyl hydroperoxide in LLDPE-I used in Example 2, the heating temperature was A maleic acid modified product of LLDPE-I was prepared by carrying out maleic acid modification in the same manner as in Example 1 except that the temperature was 220°C. The obtained maleic acid-modified product of LLDPE-I has a -(0-
06.times.10@4 moles of maleic anhydride were grafted, the melt index was 3-2 g710 min, the density was 0-922 g/cm", the melting point was 126 DEG C., and the Vikaft softening point was 109 DEG C.

Next, 90 parts by weight of the maleic acid modified product of LLDPE-I and 10 parts by weight of the maleic acid modified product of the linear low density polyethylene-H used in Example 1 were prepared in the same manner as in Example 1. A modified linear low-density polyethylene composition was produced by mixing and melt mixing.

The melt index of the obtained modified linear low density polyethylene composition was 2-8 g/10 min, and the density was 0.921 g/10 min.
cm'' and the melting point was 126°C.

[Example 4] A modified linear low-density polyethylene composition was prepared in the same manner as in Example 1, except that the amount of LLDPE-I used was 98 parts by weight, and the amount of LLDPE-H modified with maleic acid was changed to 2 parts by weight. manufactured something.

The melt index of the obtained modified linear low density polyethylene composition was 2-1 g710 min, and the density was 0.918 g/min.
C, and the melting point was 125°C.

[Comparative Example 1] In Example 1, instead of LLDPE-H, LLD
PE-I (Mel) (7 de, Cu 4-0g 710 minutes, density 0-935g/Crn'', melting point 123℃, butene-1
A modified linear low-density polyethylene composition was produced in the same manner except that the content of repeating units derived from (1.9 mol %) was used.

The melt index of the obtained modified linear low density polyethylene composition was 2.1 g 710 min, and the density was 0.918
g/c, and the melting point was 125 °C.

Evaluation item (i) Adhesive strength test between nylon and adhesive Using an inflation molding machine (guidance diameter: 100 mm, lip clearance: 1.25 mm), BUR: 1.3, folding diameter 200 mm, tensile speed 18 m, 7 minutes. , under the condition of 3 hours of water-cooled flakes, the outer layer is made of nylon (manufactured by Ube Industries, Ltd., grade name: 5033B) at 20 m long, and the middle layer and inner layer are made of modified linear low-density fabricated according to the example (or comparative example). A two-component three-layer laminated film made of a polyolefin composition (thickness: 20 pLm each) was formed into a cylindrical shape,
A cylindrical molded body was produced by cutting it into a length of 150 mm. The temperature of the extrusion molding machine was set at around 230° C. for the outer layer and around 210° C. for the intermediate and inner layers. Incidentally, when forming the laminated film, adhesion of the films to each other did not occur.

The obtained laminate was tested using an Instron tensile strength tester according to the method specified in JIS-6854.
T-type adhesion test between nylon and adhesive at a peeling speed of 50mm
I did it.

(ii) Hot water-resistant adhesion of heat-sealed part A cylindrical molded body with a length of 150 mm and a radius of 200 mm (inner surface is adhesive temperature 17 at one end of the
Heat sealing was performed under the conditions of 0°C, pressure of 2 kg/cm', and heating time of 1 second.

150 from the other end (inlet part) that is not heat sealed
After adding mJl of water, the inlet portion was heat-sealed under the same conditions as above to prepare a sample for a heat resistance test.

The obtained sample was placed in a pressure cooker heated to 90°C, and the inside of the cooker was maintained at 103°C for 30 minutes.

After 30 minutes, the sample was taken out and the state of the heat-sealed portion was observed.

(iii) Adhesive strength test of heat-sealed portion The adhesive strength of the heat-sealed portion bonded as described above was measured according to the method described in (i).

The evaluation results are shown in Table 1.

Table 1 (g/2.5cm) (g/l, 5c
Layer) Example 1 1250 No peeling 2-3 1.0
Above 2 1320 Same as above 2-2 1
．． 1 or more 3 1480 Same as above 2-0
11 or more 4380 Same as above 2-3
1.2 or more Comparative Example 1 1410 Peeling is observed 2-3 0.7
Note) In the adhesive strength (iii) in Table 1 above, the adhesive strength of the heat-sealed portion of "~ or more" indicates that the resin has broken at this point. This indicates that the actual adhesive strength is greater than this value.

Claims (1)

[Scope of Claims] 1. A linear low-density polyethylene I containing a repeating unit derived from an α-olefin I having 5 to 10 carbon atoms and/or an α,β-unsaturated carboxylic acid modified product thereof; and an α,β-unsaturated carboxylic acid modified product of linear low density polyethylene II containing repeating units derived from 3 or 4 α-olefin II in a weight ratio within the range of 60:40 to 99:1. A modified linear low-density polyethylene composition characterized by: 2. Linear low density polyethylene I has a melt index in the range of 0.1 to 10 g/10 minutes and a density in the range of 0.91 to 0.94 g/cm^3 The modified linear low-density polyethylene composition according to claim 1, which is polyethylene. 3. Linear low density polyethylene I becomes α-olefin I
2. The modified linear low-density polyethylene composition according to claim 1, which contains repeating units derived from 0.1 to 10 mol%. 4. Linear low density polyethylene II has a melt index in the range of 0.1 to 20 g/10 minutes and a density in the range of 0.90 to 0.95 g/cm^3 The modified linear low-density polyethylene composition according to claim 1, which is polyethylene. 5. Claim 1, characterized in that the linear low density polyethylene II contains repeating units derived from α-olefin II at a content within the range of 0.1 to 10 mol%. A modified linear low density polyethylene composition. 6. The alpha, beta-unsaturated carboxylic acid modified product of linear low density polyethylene II is 0.1 x 10^-^4 to 4.5 x 10^-^ per 1 g of linear low density polyethylene II. 2. The modified linear low-density polyethylene composition according to claim 1, wherein 4 moles of an α,β-unsaturated carboxylic acid modification component are graft-polymerized.