JPS5851822B2 - Crystalline polypropylene stretched composite film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stretched crystalline polypropylene composite film that is transparent and has good heat sealability.

More specifically, the present invention relates to a stretched crystalline polypropylene composite film having excellent heat sealability and transparency and having a composition containing a butene-1 polymer and a bisamide as a coating layer.

As is well known, oriented polypropylene films, especially biaxially oriented polypropylene films, are used as packaging materials and insulating materials due to their excellent physical and chemical properties.

It is used for various purposes such as cosmetic materials and container materials.

However, polypropylene biaxially stretched film has poor heat sealability, and it is difficult to obtain a heat seal with practical strength without causing heat shrinkage.To improve this drawback, it is coated with a resin that has good heat sealability. A laminated composite film is used.

These methods specifically use polyethylene, ethylene-vinyl acetate copolymer, ethylene/propylene copolymer, acrylic copolymer, polyvinyl chloride, polyvinylidene chloride, 1,2-polybutadiene, etc. as the coating layer resin. This uses an easily heat-sealable material.

However, biaxially stretched polypropylene films coated with these substances are only suitable for use in flexible packaging films in terms of heat seal strength, and cannot necessarily be said to have sufficient strength for rigid packaging.

This heat sealing strength depends not only on the fusion strength between the coating layer resins but also on the bonding strength between the coating layer resin and the polypropylene of the base layer.

Polybutene-1 has a lower softening point than polypropylene,
Since it has good bondability with polypropylene due to the similarity in molecular structure, it is suitable as a heat-sealable coating resin for biaxially stretched polypropylene films without using an adhesive.

However, the poor transparency of polybutene-1 has been a major hindrance, which has prevented its use as the above-mentioned coating resin.

The present inventors have found that by adding bisatto to polybutene-1, the transparency is improved, and surprisingly, the heat sealability of polypropylene stretched film coated with this is improved, and it can also be used for solid packaging. The present invention was achieved by discovering that the material has a strength that can be improved.

That is, the present invention contains a bisamide represented by the following (1) or (11) on at least one side of a base layer of crystalline polypropylene oriented in at least one direction, and contains 5% by weight or more of a butene-1 polymer and 95% by weight of a butene-1 polymer. % by weight of an olefin polymer.

(i) R, -CONH-R2-NHCO-R3(i
i) R1-NH-CO-R2-CO-NH-R3(
Here, R1 and R3 are alkyl groups having 3 to 21 carbon atoms,
Alkenyl group or substituted or unsubstituted Ryl group; R2
represents a methylene group or polymethylene group having 1 to 20 carbon atoms, a group in which these groups are substituted with an alkyl group, an alkenyl group, or an aryl group, or a substituted or unsubstituted arylene group.

Specific examples of bisamides used in the present invention are shown below.

Those of formula (i) include N,N'-methylenebisoctadecanamide, N,N'-methylenebishexadecanamide, N,N'-methylenebisoctadecanamide, N,N'-methylenebisoctadecanamide;
'-Ethanediylbisoctadecanamide, N, N'-1
, 4-butanediylbisdodecanamide, N, N'-1,
4-Butanediylbisoctadecanamide, N, N'-1
, 6-hexanediyl bistetradecanamide, N, N'
-1,4-phenylenebisoctadecanamide, NjN'
-[1,1'-biphenyl'J4,4'-diylbisdecanamide, N,N'1,8-octanediylbis[4
-(1,1-dimethylethyl)-benzamide IN, N
'-(1-ethylenyl)ethanediylbisdodecanamide.

N-12-[(1-oxododecyl)amino]ethyl]
-Octadecanamide, N-[6-('(1-oxooctyl)amino]hexyl]-octadecenamide, N-C
4-C(1-oxooctadecenyl)amino]phenyl]-octadecanamide, N,N'-(1-octadecyl)ethanediylbisdodecanamide, as those of formula (ii), N,N'- Didodecyl-hexanediamide, N,N'-ditetradecyl-hexanediamide, N,N'-dihexadecyl-hexanediamide, N,N'-dioctadecyl-hexanediamide, N
, N'-diphenyl-hexanediamide, N,N'-diphenyl-hexanediamide, N,N'-didodecyl-nonanediamide, N,N'-ditetradecylnonanediamide, NjN'-dihexadecylnonane Diamide, N, N'-dioctadecyl-nonanediamide, N
, N'-diphenyl-nonanediamide, N,N'-bis-[4-(1,1-dimethylethyl)phenyliononanediamide, N,N'-di(phenyl)methylnonanediamide)", N,N '-Didecyl-3-ethylenylhexanediamide, N,N'-dimxadecyl-3-ethylenylhexanediamide, N,N'-di(phenyl)
Methyl-3-ethylenylhexanediamide, N-noenyl-N-phenylmethyl-1,4-benzenedicarboxamide, N-44-(1,1-dimethylethyl)phenyl] N/-phenylmethyl-1,4-benzene Dicarboxamide, N, N'-dioctyl-5-methylenenonanediamide, N.

N'-dioctyl-5-methyl-4-nonenediamide,
N,N'-dioctadecyl-5-methylenenonanediamide and N,N'-dioctadecyl-5-methyl-4-nonenediamide are shown.

The content of bisamide is preferably in the range of 0.01 to 10% by weight based on the resin composition of the coating layer.

Below this range, the effect is not sufficient! If it exceeds this range, problems such as drawdown tend to occur during molding.

The butene-1 polymer used in the present invention includes not only a butene-1 homopolymer but also a butene-1 component containing 75
Copolymers of butene-1 and other copolymerizable comonomers, such as vinyl heptamers or diolefins, or butene-1 polymers grafted with one or more of the above comonomers. -Also includes graft polymers.

The properties of these butene-1 polymers are that the average molecular weight is 200,000 ~
2 million, toughness by ether insolubility ratio is 60% or more, melt index (190℃).

2.16 to 9.10 minutes i.e. ASTM D-1238E
Under these conditions, the melt index under these conditions is MI
It is abbreviated as

) is preferably 0.1 to 50.

Specific examples of these polymers include, in addition to polybutene-1, comonomers such as ethylene, fluoropylene, butene-2, isobutyne, butadiene, 4-methylpentene-1, ethylene/propylene (final total of three components), and butene-1. Each copolymer also contains maleic anhydride, methyl methacrylate, N,N'-didecyl-3-
Examples include various graft copolymers in which polybutene-1 is grafted with ethylenylhexanediamide or the like.

In the present invention, examples of olefin polymers that can be mixed with the butene-1 polymer as the coating layer resin include high-pressure polyethylene, medium-low pressure polyethylene, polypropylene, polyisobutyne, 1,2-polybutadiene, 1,4-polybutadiene, and poly-4 -Methylpentene-1, polyhexene-
1. Homopolymers such as polystyrene, copolymers such as ethylene/propylene, butene-1/ethylene, phthene-1/7" lopylene, ethylene/butene-1/7" lopylene, ethylene/propylene/diene monomers, polyethylene /maleic anhydride, polypropylene/methyl methacrylate, polypropylene/N,N'-(1-ethylenyl)ethanediylbisophtatecanamide, and special graft copolymers.

The amount of this olefin polymer mixed is 95 weight downwind, preferably 90 weight downwind of the total amount with the butene-1 polymer.

That is, an amount of the butene-1 polymer of 5% by weight or more is effective in improving heat sealability, but in order to obtain an even better effect, an amount of 10% by weight or more is desirable.

The effect of the bisamide in the coating layer resin composition is to improve the compatibility (bondability) of the resin layer with the crystalline polypropylene base layer, and to improve the heat sealability between the resin layers. Improves heat sealability of film.

Another effect of the bisamide in the composition is to suppress the decrease in transparency due to recrystallization of polybutene-1.

The temperature at which the composite film of the present invention can be stretched is in the range from the glass transition point to the melting point of the base polypropylene, preferably from 100°C to 150°C, and when heat treatment is performed. The temperature range is 145°C or higher and 160°C.

Therefore, when polybutene-1 is contained as a component of the coating resin in a composite film, it is inevitable that the melting point will be exceeded during its thermal history, resulting in a whitening phenomenon in the coating resin layer due to recrystallization of the resin. As a result, transparency is reduced.

In contrast to these drawbacks, when the bisamide is added, the transparency is much better than when the bisamide is not used, even if the melting point may be exceeded during the thermal history.

Such phenomena and effects also occur with the other butene-1 polymers.

The composition thus imparts low temperature heat sealability and excellent heat seal strength to the polypropylene film without substantially reducing its original transparency.

The coating layer resin composition and the base layer crystalline polypropylene may contain additives commonly used within the scope of the present invention, such as stabilizers, slip agents, antiblock agents, antistatic agents, flame retardants, Nucleating agents, crosslinking agents, blowing agents, pigments, fillers, plasticizers, waxes, rosins, etc. can be added.

The coating layer resin or crystalline polypropylene composition can be prepared by any processing method.

Taking the coating layer resin composition as an example, each component may be kneaded and granulated in advance before molding, or only the bisamide may be included in a given composition before, during, or after molding.

Of course, each component may be mixed during molding.

A masterbatch containing a predetermined proportion of polybutene-1 and other components containing a large amount of bisamide may be granulated in advance and used by diluting it with the other components during molding to obtain the desired composition ratio. Good.

Of course, in these methods, the content form of bisamide is not limited to a mere mixed state, but also chemical bonding through copolymerization, graft polymerization, etc. with the component polymers in one composition, functional groups of the component polymers, or additives. It goes without saying that it means the form of inclusion in a physical and chemical bond state such as a coordinate bond between.

The composite film of the present invention has a coating resin layer on at least one side of a biaxially oriented base polypropylene film, but the manufacturing method thereof is not particularly limited. For example, it may be manufactured by the following method. .

That is, the crystalline polypropylene sheet for the substrate and the resin composition sheet for the coating layer are bonded together by the following method: (1) A method of bonding both in a heated molten state, that is, in or near the exit of an extrusion die for forming the sheet; Alternatively, it can be pasted while it is still molten during the calender roll or at the final stage.

(2) A method in which both are formed into a solid sheet and then stacked on top of each other.

(3) A method in which a base polypropylene is preheated and stretched uniaxially, and a coating composition is laminated onto the stretched film in a molten state or a film state.

The thus bonded film is further uniaxially or biaxially stretched.

In the case of biaxial stretching, sequential stretching or simultaneous stretching may be used.

After stretching after bonding, heat treatment may be performed to prevent shrinkage during heat sealing or to relax the orientation of the coating layer.

Alternatively, the coating resin composition is laminated in a molten state or in a solid film state to a polypropylene film that is already in a biaxially oriented state, and the coating resin composition is laminated under tension or under no tension substantially above the melting point of the coating layer, In addition, the desired composite film can also be obtained by heat treatment in a temperature range in which the orientation of the base film is not released.

Examples are shown below.

In addition, the method of measuring the physical properties in the examples is as follows.

MFI r L according to the method of ASTM D-1238
Melt flow index measured under different conditions.

2.16kg, 230℃, 10 minutes value Haze:
Values obtained by the method of ASTM D-1003.

The unit is the person in charge. Peel strength: Strength when material films with a width of 15 mm are overlapped, heat-sealed over the gold mine, and the heat-sealed portion is peeled off at a tensile speed of 300 myx/min.

Unless otherwise specified, the heat sealing conditions are 135° C. and 2 kg/cIrL for 21 seconds.

Example 1 A 1.5 mm thick sheet of polypropylene (MFI=1) was stretched 5 times in the machine direction.

The sheet was subsequently coated with polybutene-1 (MI=1.5)
100 parts by weight and N in the weight proportions shown in Table 1,
A 60μ thick T-die film obtained from a composition consisting of N'-ethanediylbisoctadecanamide was laminated between a pressure roll and stretched 8 times in the transverse direction in an open environment at 150°C, and then stretched at 160°C under tension. Gai was processed.

The thus obtained retrieval film having a thickness of 45 μm had the properties shown in Table 1.

From this table, the effect of improving the transparency and heat sealing strength of the composite film is clear.

Example 2 A 1.5 mrn thick sheet of polypropylene (MFI=1) was stretched 5 times in the machine direction.

The sheet was then treated with an ethylene/propylene copolymer (M
F = 7), polybutene-1 (MI = 4) and N,
A 60μ thick T-die film obtained from a composition made from N'-ethanediylbisoctadecanamide was laminated between pressure rolls, stretched 8 times in the transverse direction in an open environment at 150°C, and then stretched under tension. and heat-treated at 1600°C.

The thus obtained composite film having a thickness of 45 μm had the properties shown in Table 2.

From this table, the effect of improving the transparency and heat sealing strength of the composite film is clear.

Example 3 A 1.5 mm thick sheet of polypropylene (MFI=2) was stretched 5 times in the machine direction.

The sheet was then coated with 100μ of a composition consisting of polypropylene (MFI=8), polybutene-1 (MI=4) buttons and N,N'-dioctadecyl-7 nonani/diamide in the proportions shown in Table 3. It was laminated between thick T-dyne*4 film pressure rolls, stretched 8 times in the transverse direction (8 times) in the open at 145°C, and heat-treated at 150°C under tension.

The composite film thus obtained with a thickness of 50 μm had the properties shown in Table 3.

From this table, the transparency of the composite film. The effect of improving heat seal strength is clear.

Example 4 A 1,1-thick sheet of polypropylene (MFI = t) and polybutene-1 (MI =
1.8) sheets with a thickness of 70 μm were overlapped and stretched 6 times in length and width in a simultaneous biaxial stretching device in an atmosphere at a temperature raised from 110° C. to 150° C.1.

After stretching, each direction was loosened by an inch and then heat treated at 155°C.

The 33μ composite film thus obtained has excellent transparency (Haze 2.0%) and does not peel off at all in a peel test with an adhesive tape.

Also, the polybutene-1 plane was combined, 1300, 1.
The peel strength of the sealed part is 455f715mm when sealed under heat sealing conditions of 5kg/cIrL2.1 seconds
and excellent.

For comparison, when polybutene-1 does not contain bisamide, the composite film obtained by the same method as above has poor transparency (Haze 4.2%) and peel strength of the heat-sealed part of 350 fj. / 15 rnw is low.

Claims (1)

[Claims] 1. The following (1) or (11) is provided on at least one side of a crystalline polypropylene base layer oriented in at least one direction.
A stretched crystalline polypropylene composite film containing a bisamide represented by the formula and coated with a layer of a resin composition comprising 5% by weight or more of a butene-1 polymer and 95% by weight of an olefin polymer. (i) RQ-CONH-R2-NHCO-R3(i
f) R1-NH-CO-R2-CO-NH-R. (However, here, R1 and R3 are alkyl groups, alkenyl groups, or substituted or unsubstituted aryl groups having 3 to 21 carbon atoms; R2 is methylene groups, polymethylene groups having 1 to 20 carbon atoms, and represents a substituted alkyl group, alkenyl group, or aryl group, or a substituted or unsubstituted arylene group.)