JPH0369361A - Composite biaxially oriented polypropylene resin film and manufacture of the film - Google Patents

Abstract

PURPOSE:To obtain a film having heat-seal characteristics at a low temperature and excellent operating characteristics by forming a low melting-point resin layer of a mixed resin containing specific quantities of a resin composed of a specific ethylene-vinyl ester copolymer or ethylene-unsaturated carboxylic acid based copolymer and a polyethylene resin and bringing the surface of the low melting-point resin layer to the state of a roughened surface. CONSTITUTION:A composite biaxially oriented polypropylene resin film consists of a polypropylene resin film layer and a low melting-point resin layer laminated on the film layer. When the melt flow rate (g/ten min) of a resin [A] made up of an ethylene-vinyl ester copolymer or an ethylene-unsaturated carboxylic acid copolymer is represented by MFR(a) and the melt flow rate (g/ten min) of a polyethylene resin [B] by MFR(b), the low melting-point resin layer is formed of a mixed resin containing the 60-90 pts. wt. resin [A] and the 40-10 pts. wt. resin [B] satisfying the conditions of formulae (I)-(III). The surface of the low melting-point resin layer is brought to the state of a roughened surface.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to packaging materials for obtaining food and other packaging bodies,
It relates to a composite biaxially oriented polypropylene resin film used as a cosmetic protective film for paper, and a method for producing the film, which has heat-sealing properties at low temperatures, as well as slipperiness and anti-blocking properties. The object of the present invention is to provide a composite biaxially stretched polypropylene resin film having excellent properties in terms of characteristics, and a method for producing the same.

[Prior Art] Biaxially stretched polypropylene resin films have excellent properties such as transparency and mechanical strength, and are frequently used as packaging films and cosmetic protective films for paper.

However, the biaxially oriented polypropylene resin film does not have sufficient heat-sealing performance;
A film with heat sealing properties is attached to an axially stretched polypropylene resin film, or
A composite biaxially oriented polypropylene resin film obtained by extruding and laminating resins having heat-sealing properties has been used.

Furthermore, in recent years, by laminating a low melting point resin on an unstretched or uniaxially stretched polypropylene resin film and stretching this in the biaxial direction in the former case,
In the latter case, composite biaxially oriented polypropylene having a heat-sealing resin layer can be produced by uniaxially stretching in a direction perpendicular to the previously introduced stretching method, that is, by stretching in at least one axis. Methods for obtaining resin films based on the above-mentioned methods are beginning to be used.

[Problems to be Solved by the Invention] By the way, a composite biaxially oriented polypropylene resin film in which a film having heat-sealing properties is attached to a biaxially oriented polypropylene resin film has extremely poor manufacturing efficiency, and , a composite biaxially oriented polypropylene resin film in which a resin having heat sealing performance is extruded and laminated on a biaxially oriented polypropylene resin film cannot have the thickness of the extruded laminated resin layer less than 1Oμ, However, it has the disadvantage of being relatively expensive due to poor productivity and other factors.

On the other hand, a composite biaxially stretched polypropylene resin film obtained by stretching a laminate of an unstretched or uniaxially stretched polypropylene resin film layer and a low melting point resin layer in at least one axis, As the production efficiency is high and the thickness of the laminated resin layer (heat-sealing resin layer) can be made thin, it can be supplied at low cost.
ethylene-propylene) copolymer, polybutene-1゜poly(ethylene-butene) copolymer, poly(propylene-
(butene) copolymers, and even resins made of mixtures thereof, have the disadvantage that resins that can be heat-sealed at a low temperature of 80° C. or lower cannot be used.

In other words, many resins with a melting point of 80°C or lower are similar to rubber, and are sticky even at room temperature, which can cause them to get caught on rolls or block the wound film, making it impossible to unwind it. Furthermore, the resulting film has no slip properties, resulting in poor handling and workability, and the actual situation is that this method has not been put to practical use as a laminated resin.

In contrast, the first invention is a composite biaxially oriented polypropylene resin film comprising a laminated resin layer that can be sufficiently thermally bonded at a heat sealing temperature of 80° C. or less, and furthermore, the polypropylene resin layer and the polypropylene resin layer have a low temperature. To provide a composite biaxially oriented polypropylene resin film which can be manufactured by using a method of stretching a laminated sheet with a melting point resin layer in at least one axial direction and has good working properties. It is something.

Moreover, the second invention provides a method for easily and efficiently obtaining the composite biaxially stretched polypropylene resin film of the first invention.

Means for Solving Problem C] The first invention provides a composite biaxially oriented polypropylene consisting of a polypropylene resin film layer to which biaxial stretching has been introduced and a low melting point resin layer laminated to the film layer. system resin film, wherein the low melting point resin layer has the following (
60 to 90 parts by weight of a resin [A] consisting of an ethylene-vinyl ester copolymer or an ethylene-unsaturated carboxylic acid copolymer that satisfies the conditions of formulas 1) to (3) and a polyethylene resin [B] 40 to 10 parts by weight. The low melting point resin layer has a rough surface.

The second invention also provides a resin comprising a polypropylene resin layer and an ethylene-vinyl ester copolymer or an ethylene-unsaturated carboxylic acid copolymer that satisfies the conditions of formulas +11 to (3) below. After obtaining a laminate with a resin layer melted and extruded with a mixed resin containing 60 to 90 parts by weight of [A] and 40 to 10 parts by weight of polyethylene resin [B],
If the polypropylene resin layer in the laminate is not stretched in either the longitudinal or lateral directions, the laminate may be stretched in two axial directions. When uniaxial stretching has already been introduced, the polypropylene resin film can be stretched by uniaxial stretching in a direction perpendicular to the previously introduced stretching direction, that is, by stretching at least in the l-axis direction. A composite biaxially stretched polypropylene resin film in which biaxial stretching is introduced is obtained.

Ethylene-vinyl ester copolymer or ethylene-
The melt flow rate (g/10 minutes) of the resin [A] made of an unsaturated carboxylic acid copolymer is MFRla), and the melt flow rate (g/10 minutes) of the polyethylene resin [B] is MFR (b). When displaying, 3, 0
≦MFR(al≦50.0-------(110
, 2≦MFR(b)≦5.0 (2)
4, 0≦MFRfal/MFR(bl≦70.0・
(3) In each of the present inventions having the above configuration, the polypropylene resin used for the polypropylene resin layer is a polypropylene homopolymer, a copolymer of polypropylene and a small amount of ethylene, or These mixed resins, etc., as in the case of normal biaxially stretched polypropylene film,
Mixed resins with other resins may also be used within a range that does not impair the properties of the polypropylene film.

In addition, when forming the polypropylene resin layer,
Additives commonly used in the production of polypropylene resin films, such as antioxidants, slip agents, anti-blocking agents, antistatic agents, ultraviolet absorbers, etc., may be added and contained as necessary. Of course it is.

In addition, the resin used for the low melting point resin layer [AI is composed of an ethylene-vinyl ester copolymer or an ethylene-unsaturated carboxylic acid copolymer; teeth,
Ethylene-vinyl acetate copolymer resin is most preferred;
In addition, examples of ethylene-unsaturated carboxylic acid copolymer resins include ethylene-acrylic acid copolymer, ethylene-acrylic acid copolymer,
Ethylene-unsaturated carboxylic acid ester copolymers such as meccrylic acid copolymer, ethylene-methyl acrylate copolymer and ethylene-ethyl acrylate copolymer, and further,
A terpolymer obtained by copolymerizing each of the above copolymers with maleic anhydride or the like is used.

The ethylene-vinyl ester copolymer or ethylene-unsaturated carboxylic acid copolymer resin preferably has a sufficiently low melting point,
A copolymer resin having an ethylene component of 60 to 90% by weight and a vinyl ester or acrylic acid (ester) component of 10 to 40% by weight is preferred.

Furthermore, as the other polyethylene resin [B] used for the low melting point resin layer, low density polyethylene, 1 m-shaped low density polyethylene, medium density polyethylene, high density polyethylene, etc. are used.

Note that when high-density polyethylene is used as the polyethylene resin [B], the surface of the low-melting point resin layer obtained by stretching becomes more rough, so composite 2, which has excellent handling properties, is used. Since the low-temperature heat-sealing performance of the low-melting point resin layer tends to deteriorate after becoming an axially oriented polypropylene film, it is preferable to use low to medium density polyethylene.

In the low melting point resin layer, the resin [AI and resin [B] are composed of 60 to 90 parts by weight of resin [A] and 40 to 1 part by weight of resin [B].
0 parts by weight, preferably from a mixed resin containing 65 to 75 parts by weight of m fat [A] and 35 to 25 parts by weight of resin [B].

In addition, in the mixing ratio of the resin [AI and resin [B] described above in the low melting point resin layer, if the resin [AI is 60% by weight ungrooved, the low temperature heat sealing performance of the resulting composite film will not be sufficient. Moreover, if it exceeds 90% by weight, the degree of roughening of the surface of the low melting point resin layer obtained by stretching will not be sufficient.
It becomes difficult to obtain a film with good working properties.

Furthermore, the resin [A] made of an ethylene-vinyl ester copolymer or an ethylene-unsaturated carboxylic acid copolymer used in the low melting point resin layer and the polyethylene resin [B] are ethylene-vinyl ester copolymers or ethylene-vinyl ester copolymers. MFR is the melt flow rate (g/lo min) of resin [A] made of an ester copolymer or an ethylene-unsaturated carboxylic acid copolymer.
(a) When the melt flow rate (g/10 min) of polyethylene resin [B] is expressed as MFRfbl, 3.0≦MFR(al≦50.0・−・−・・(110
,2≦MFR(bl≦5.0...(2)4
．． 0≦MFR(al/MFRlb)≦70.0...
It is necessary that each of the relational expressions in (3) be satisfied.

In addition, the resin consisting of the ethylene-vinyl ester copolymer or the ethylene-unsaturated carboxylic acid copolymer [
A] melt flow rate (6710 minutes), i.e.
MFRfa) is determined according to JIS K 6730, and the melt flow rate (g/
10 minutes), that is, MFR (bl is JIS K67
60, respectively, and JIS K72
Since it is measured according to condition 4 in Table 1 of 10, it has the same meaning as the melt flow index shown in JIS K 6900 (plastic term).

MFR (a) of resin [A] used in the low melting point resin layer
If l exceeds 50.0, the flow of the resin in the molten state is too good, making it difficult to form a low melting point resin layer consisting of an extruded resin layer with a uniform thickness;
．． If it is less than 0, the surface of the low melting point resin layer obtained by stretching will not be sufficiently roughened.

Furthermore, M of the resin [B] used in the low melting point resin layer
When FR(b) exceeds 5.0, the degree of roughening of the surface of the low melting point resin layer obtained by stretching becomes insufficient, and when it becomes less than 0.2, the resin [A
] and resin [B] become difficult to form a uniform dispersion state,
Since the resin [B] exists in the form of particles, unevenness is likely to occur due to the thickness of the low melting point resin layer and roughening of the surface during the stretching process of the laminate.

Furthermore, if MFR (al/MFR (bl) is less than 4.0, the degree of roughening of the surface of the low melting point resin layer obtained by stretching will not be sufficient, and if it exceeds 70.0, , it becomes difficult to form a uniform dispersion state of resin [A] and resin [B], and resin [B] exists in the form of particles. Unevenness tends to occur due to roughening.

The resin [A] and the resin [B] in the low melting point resin layer may each be a mixed resin, for example, ethylene-vinyl acetate resin (MFR(a
l = 15) 35 parts by weight, ethylene-methyl methacrylate resin (MFR (al = 20)) 35 parts by weight, low density polyethylene resin (MFR (b) = Q, 6) 30
A low melting point resin layer based on parts by weight, etc. can be used.

However, in the method for producing a composite biaxially oriented polypropylene resin film of the present invention, the roughness of the surface of the low melting point resin layer is limited.

It is estimated that this occurs due to stress concentration due to differences in compatibility and fluidity between the resins during the stretching process during film production, and the above-mentioned resin [A] and resin [
If resin [A] or resin [B] is a mixed resin, the intermediate component will produce a "snag" effect, which will reduce the degree of roughening of the obtained surface. When used in a mixed resin, care must be taken to use within a range that allows sufficient roughening to occur.

The low melting point resin layer may contain other additives within the range that does not impair the characteristics of the low melting point resin layer, that is, the characteristics of heat sealing at low temperatures and surface roughening due to stretching. For example, it goes without saying that slip agents, anti-blocking agents, tackifiers such as petroleum resins and terpene resins may be added as appropriate.

In particular, adding a fatty acid amide-based slip agent to the low melting point resin layer is useful when the laminate comes into contact with a metal roll before the stretching process of the laminate during the manufacturing process of the composite biaxially stretched film. In other words, when coming into contact with metal rolls such as casting rolls or tenter entrance rolls,
This results in better peeling between the roll and the surface of the laminate, improving workability.

The method for producing a composite biaxially stretched film of the present invention includes at least 4J1 of the biaxially stretched polypropylene resin layer.
Before the completion of the direction stretching process, the lamination of the polypropylene resin layer and the melted and extruded resin layer made of a low melting point mixed resin is completed. A method in which a laminated resin sheet is biaxially stretched, a method in which a low melting point resin layer is extruded and laminated onto a polypropylene film stretched in the longitudinal direction, and then stretched in the transverse direction, etc. can be used.

The low melting point resin layer used in the present invention literally has a low melting point.

Therefore, in the former method of using a laminated resin sheet of a polypropylene resin layer and a low melting point resin layer by coextrusion, when the laminated resin sheet is stretched by a roll, the low melting point resin layer melts and adheres to the roll. This makes the heating method during stretching difficult, so a melted and extruded resin layer made of a low melting point mixed resin is laminated on the l-axis stretched polypropylene resin film after the stretching process using rolls. It is preferred to stretch in the transverse direction using a tenter.

Further, the surface of the low melting point resin layer in the laminate of the polypropylene resin layer and the low melting point resin layer is roughened when the laminate is subjected to a stretching process, and the resulting composite 2 The slipperiness between the axially oriented films and the slipperiness between the film and the roll are improved, resulting in a composite biaxially oriented polypropylene resin film having excellent properties in terms of workability.

The degree of surface roughening of the low melting point resin layer obtained by stretching the laminate of the polypropylene resin layer and the low melting point resin layer has good sliding properties and blocking resistance,
In order to obtain a biaxially oriented polypropylene resin film with good properties in terms of working properties, the ten-point average surface roughness defined by JISBO601 (Rzl is 2.0 to lOμ
It is preferable that the

Note that the degree of roughening obtained depends on the blending ratio of resin [A] and resin [B] in the low melting point resin layer, and the MF
Melt flow rate (g/lo min) of resin [A] expressed by R(a) and resin [B] expressed by MFR (b).
] in combination with the melt flow rate (g/10 minutes).

That is, a resin consisting of an ethylene-vinyl ester copolymer or an ethylene-unsaturated carboxylic acid copolymer [
A] and polyethylene resin [B], the resin [A] is 60 to 90 parts by weight, and the resin [B] is 40 to 10 parts by weight.
Mixed in proportions of parts by weight, 3.0≦MF
R(a)≦50.0, and 0.2≦MFR(b
In the case of l≦5.0, the larger the amount of resin [B] added, the more.

The larger MFRfa)/MFR(b), the higher the roughness of the surface of the resulting low melting point resin layer.

Furthermore, polyethylene resin [B] in the low melting point resin layer
The smaller the amount added, the higher the molar ratio of vinyl ester or unsaturated carboxylic acid (ester) in the resin [A] made of ethylene-vinyl ester copolymer or ethylene-unsaturated carboxylic acid copolymer. The higher the temperature, the better the low-temperature heat sealing properties of the low melting point resin layer.

Therefore, resin [A] and resin [
By appropriately selecting the type of B] and the mixing ratio of both resins, the degree of roughness of the surface of the low melting point resin layer and the low temperature heat sealing properties of the low melting point resin layer can be determined as desired. It's something you get.

[Examples] Hereinafter, specific configurations of the composite biaxially stretched polypropylene resin film of the present invention and the method for producing the film will be described based on Examples.

Examples 1 to 4 A uniaxially stretched film was obtained by longitudinally l-axis stretching a sheet having a thickness of about 1000 μm obtained by melt-extruding the polypropylene resin composition shown below using a T-die.

Polyethylene isotactic polypropylene (MFR2, Og/10 minutes)...99.2 parts by weight Alkylamine ethylene oxide adduct...0.25 parts by weight Glycerin monostearate ester... ...0.35 parts by weight Stearamide ...0.05 parts by weight Silica fine powder ...0.15 parts by weight On the surface of the uniaxially stretched film obtained above, another From the extruder,
70 parts by weight of resin [A] and resin [B] shown in Table 1 below.
] 30 parts by weight of a resin composition for a low melting point resin layer, in which 0.2 parts by weight of stearic acid amide and 0.2 parts by weight of fine silica powder were added to 99.6 parts by weight of the mixed resin,
By extrusion lamination, a laminated sheet having a low melting point resin layer with a thickness of about 50 μm was obtained.

Next, the laminated sheet was introduced into a Tenku machine and stretched about 9 times in the transverse direction to obtain a composite biaxially stretched polypropylene resin film having a thickness of about 25 μm and serving as an example of the present invention.

Comparative Examples 1 to 3 In the procedure of Example 1, 70 parts by weight of resin [A] and resin [
All the steps were the same as the corresponding steps in Example 1, except that 99.6 parts by weight of the resin component described below was used instead of 99.6 parts by weight of the mixed resin with 130 parts by weight of B130. A composite biaxially stretched polypropylene resin film was obtained for comparison.

Comparative example 1 Resin same as resin [A] used in Example 1 Comparative example 3 Resin same as resin [B] used in Example 1 Comparative example 3 Resin same as resin [B] used in Example 1 In Examples 1 to 4 above The obtained composite biaxially oriented polypropylene resin film has a roughened surface of the low melting point resin layer, which is a laminated resin layer, and has excellent properties in terms of slipperiness and blocking resistance, and good work characteristics. In addition, it had good heat sealing performance at low temperatures.

However, the composite biaxially stretched polypropylene resin film of Comparative Example 1 had a severe blocking phenomenon, and the winding of the composite biaxially stretched polypropylene resin film after the stretching process was at its limit, and it could not be rewound. .

Further, the composite biaxially stretched polypropylene resin film obtained in Comparative Example 2 had poor heat sealing performance at low temperatures.

Furthermore, the composite biaxially stretched polypropylene resin film obtained in Comparative Example 3 did not cause roughening on the surface of the laminated resin layer, had poor slip properties and anti-blocking properties, and could not be put to practical use. There wasn't.

Table 2 shows various physical property values of each composite biaxially stretched polypropylene resin film.

In addition, the physical property values of each film obtained in Examples and Comparative Examples were measured as follows.

l) Haze (%) Measured in accordance with JIS B 6718 using a digital haze meter NDH-20D [Nippon Heavy Industry Co., Ltd.].

2) Surface roughness Measured according to JIS B 0601 using a surface profile measuring instrument Surfcom 554A [Tokyo Seimitsu Co., Ltd.],
It was expressed as ten-point average roughness (Rz).

3) Slip property In accordance with ASTM D 1894 (Method B), each composite 2
The coefficient of friction between the laminated resin layer surface and the polypropylene resin film layer surface in the axially stretched polypropylene resin film was measured.

In addition, those with a friction coefficient exceeding 2 were indicated as unmeasurable.

4) Blocking resistance Each composite biaxially stretched polypropylene resin film was cut out to 5' OX 50 mm, and the two samples were stacked so that the laminated resin layer surface and the polypropylene resin film layer surface were in contact, and further 2K
24 g in an atmosphere of 40°C and 70% RH.
After leaving it for a while, pick up the two overlapping samples with your thumb and forefinger, and sensory-evaluate the state of blocking when peeling them off with the force of your fingertips. ○... Easily peeled off with your fingertips. Δ: Considerable resistance is felt, but peeling with fingertips is possible ×: Peeling with fingertips is not possible.

5) Heat sealing temperature (''C) By using a thermally inclined heat sealer (Toyo Seiki Seisakusho),
The laminated resin layer surfaces of the composite biaxially stretched film were heat-sealed to each other at various temperatures (at intervals of 5°C) under heat and pressure conditions for 2 kg/Cm'', 1,0 seconds, and the strength of the resulting sealed portion was determined. , Tensilon (manufactured by Orientic)
The seal strength is 200g/15++un.
The lowest temperature that exceeds the width is indicated.

Examples 5-7. Comparative Examples 4 to 5 In the procedure of Example 1, 370 parts by weight of resin [A and 130 parts by weight of resin MFR (ethylene-vinyl acetate resin with an al of 15 [
Evaflex Nimitsui DuPont Polychemical: Resin [A] consisting of 19% by weight vinyl acetate component, MFR (b
) is a mixed resin consisting of a linear low-density polyethylene resin [B] consisting of Showa Denko 1 (Showa Denko 1) with a ratio of 0.8, and the blending ratio of both is shown in Table 3. Mixed resin 9
All the steps other than using 9.6 parts by weight were the same as the corresponding steps of Example 1, and the composite biaxially stretched polypropylene resin film, which is an example product of the present invention,
A composite biaxially stretched polypropylene resin film was obtained for comparison.

Table 4 Table 4 shows various physical property values of each composite biaxially stretched polypropylene resin film obtained.

From Table 4, it is clear that as the proportion of resin [B] made of low density polyethylene resin increases, the degree of roughening of the surface of the laminated resin layer increases, and at the same time, the heat sealing temperature increases. has been done.

Note that the degree of surface roughness is closely related to the work characteristics shown by the film's friction coefficient and blocking resistance, and in order to have good workability, resin [A] and wood 1it! [B
] It has been confirmed that 10 parts by weight or more of resin [B] is required in the mixed resin.

Furthermore, in order to obtain low-temperature heat sealability, resin [B
] has been confirmed to have to be suppressed to 40 parts by weight or less.

Therefore, in order to have both good work properties and low-temperature heat sealing properties, in a mixed resin of resin [A] and resin [B], resin [A] should be 60 to 90 parts by weight, and resin [B] should be 40 to 40 parts by weight. It is necessary that the amount is mixed within the range of 10 parts by weight.

Examples 8-15. Comparative Examples 6 to 16 In the procedure of Example 1, 170 parts by weight of resin [A] and resin [
Instead of 99.6 parts by weight of the mixed resin with 130 parts by weight of B, 70 parts by weight of resin [A] shown in Table 5 and resin [B
] Except for using 99.6 parts by weight of the mixed resin with 30 parts by weight, all the steps were the same as the corresponding steps in Example 1, and the composite biaxially oriented polypropylene system which is the actual height measurement of the present invention was A resin film and a composite biaxially stretched polypropylene resin film for comparison were obtained.

The abbreviations for resin [AI and resin [B] shown in Table 5 are as follows.

Δyo EVA (11 Ethylene-vinyl acetate resin 11 m [Evaflex Nimitsui DuPont Polychemical: Vinyl acetate component io weight%: MFR (al = 701EVA (2) Ethylene-vinyl acetate resin [Evaflex Nimitsui DuPont Polychemical: Vinyl acetate component 19% by weight: MFRla) = 381EVA (31 Ethylene-vinyl acetate resin [Evaflex: Mitsui DuPont Polychemical: Vinyl acetate component 19% by weight: MFR(a) = 15] VAt41 Ethylene-vinyl acetate Resin [Evaflex: DuPont Mitsui Polychemical: Vinyl acetate component 19% by weight: 5IPR (a) = 3, 51EVA (
5) Ethylene-vinyl acetate resin [Evaflex: DuPont Mitsui Polychemicals: Vinyl acetate component 10% by weight: MFR (al=l, 9]MMA Ethylene-methyl methacrylate resin [Acrift: Sumitomo Chemical: Methyl methacrylate component 20% by weight %: MFR (a) = 7.01 Seedless raw and L D P E (11 Low density polyethylene resin [Mirason: DuPont Mitsui Polychemicals: MFR (b) = 6.01 L D P E (2) Low Density polyethylene resin [Mirason: DuPont Mitsui Polychemicals: MFR (bl = 3.0] L D P
E (31 Low density polyethylene resin [Mirason Nimitsui DuPont Polychemical: MFR (b) = 1, 0] L D P
E (4) Low-density polyethylene resin [Sumiyokusen: Sumitomo Chemical: MFR (bl=0.8] L D P E (51 Low-density polyethylene resin [Shorex: Showa Denko: &1FR (bl=0.6]) L D P E (6) Low density polyethylene resin [Mirason Nimitsui DuPont Polychemical: MFR (bl = 0.25) L D P E (7) Low density polyethylene resin [NUC Polyethylene Nippon Unicar: MFR (bl = 0) , 151 Various physical property values of each composite biaxially stretched polypropylene resin film obtained are shown in Table 6.

Further, the haze (%) of each composite biaxially stretched polypropylene resin film obtained is shown in the figure together with the value of MFR (at) of resin [Al] and the value of MFR (b) of resin [B].

In addition, the value close to ・ in the figure is haze (%),
× indicates a point where haze cannot be measured, and the shaded area is the range of resin [Al and resin [B] defined in the present invention.

In Comparative Example 7, the MFR (a
If a resin with a high l is used, the melt-extruded web will shake left and right and become unstable when the mixed resin is melt-extruded, and the thickness of the resulting laminated resin layer will be uneven in the width direction. It was not possible to obtain a uniform stretched film.

In addition, in Comparative Example 15, that is, the MFR of resin [Al
(When a resin with low Al was used, it was not possible to roughen the surface of the laminated resin layer, and it was not possible to obtain a composite film with good workability.

Furthermore, in Comparative Example 8, the MFR of resin [B]
When a resin with high (b) was used, the surface of the laminated resin layer could not be roughened, and a composite film with good workability could not be obtained.

Furthermore, in Comparative Example 11 and Comparative Example 13, when a resin with a low MFR (bl) of resin [B] was used, uniform mixing between resin [Al and resin [B] could not be achieved. The dispersion state of the resin in the mixed resin was poor, and undispersed resin [B] remained in one laminated resin layer, resulting in a poor appearance of the film.

In Comparative Examples 10, 12, and 14, that is.

MFR of resin [Al (MFR of al and resin [B] (bl
Ratio [MFR (at/MFR (b))] (7) For low-resin T-toilet.

In this case, the surface of the laminated resin layer could not be roughened, and a composite film with good workability could not be obtained.

Also, Comparative Example 7. That is, MFR of resin [Al (al
and the MFR (b) of resin [B], that is, [MF
When using a resin with a high R(al/MFR(blF) (7), resin [Al] and resin [B] cannot be mixed uniformly, and the dispersion state in the mixed resin is poor, causing unresolved problems. Since the dispersed resin [B] remained in the laminated resin layer, the appearance of the film was poor.

On the other hand, resin [Al and resin [B].

3.0≦MFR(a)≦50. 0-・・・・・・+1
10, 2≦MFRfbl≦5.0 (
2) 4.0≦MFR(al/MFR(b)≦70.0
・・・・・・・・・・・・ In the case of the example method of the present invention that satisfies the condition (3), a uniform laminated resin layer made of mixed resin is obtained, and the surface is sufficiently roughened. A composite film with good workability was obtained.

[Operations and Effects of the Invention] The first invention provides a composite biaxially oriented polypropylene resin comprising a polypropylene resin film layer to which biaxial stretching has been introduced and a low melting point resin layer laminated to the film layer. A film, wherein the low melting point resin layer has the following (
1) A resin consisting of an ethylene-vinyl ester copolymer or an ethylene-unsaturated carboxylic acid copolymer satisfying the conditions of formulas 1) to (3) [A160 to 90 parts by weight and a polyethylene resin [B110 to 40 parts by weight] The low melting point resin layer has a rough surface.

In addition, the method for producing a composite biaxially stretched polypropylene resin film of the second invention uses an ethylene-vinyl ester copolymer or an ethylene-unsaturated carboxylic acid copolymer that satisfies the conditions of formulas (11 to (3)) below. 60 to 90 parts by weight of resin [A] consisting of a copolymer and 10 parts by weight of polyethylene resin [B]
Introducing biaxial stretching to the polypropylene resin film by stretching a laminate of a melted and extruded resin layer and a polypropylene resin layer in at least one direction with a mixed resin containing ~40 parts by weight, A composite biaxially stretched polypropylene resin film having a laminated resin layer consisting of a low melting point resin layer is obtained.

Ethylene-vinyl ester copolymer or ethylene-
Melt flow rate (g /
0 minutes) is displayed as MFRfb), 3.0≦MFR
(al≦50.0−・---・(110,2≦MFR(
bl≦5.0・・・・・・・・・(2)4.0≦MFR(
a)/MFR (bl≦70.0・・・・・・・・・・
・ (3) Therefore, the composite biaxially stretched polypropylene resin film of the first invention has heat-sealing properties at a low temperature of 80° C. or lower, and has a roughened surface. And, it can be manufactured by using a method of stretching a laminate of an unstretched or uniaxially stretched polypropylene resin film layer and a mixed resin layer, at least in the l-axis direction, and has excellent work characteristics and low temperature. It exhibits excellent sheet sealing properties.

In addition, since the method of the second invention utilizes a laminating means in the stretching process, the composite method of the first invention
An axially stretched polypropylene resin film can be produced extremely efficiently.

[Brief explanation of drawings]

The figure shows Examples 8 to 15. The haze (%) of the composite biaxially stretched polypropylene resin films obtained in Comparative Examples 6 to 16 was calculated based on the MFR of resin [A] (the value of at and the value of resin [B
] is a graph shown together with the numerical value of MFRfbl.

Claims (1)

[Scope of Claims] A composite biaxially stretched polypropylene resin film comprising a polypropylene resin film layer to which mono- and biaxial stretching has been introduced and a low melting point resin layer laminated to the film layer, wherein the low melting point The resin layer has the following (1) to (3)
60 to 90 parts by weight of a resin [A] made of an ethylene-vinyl ester copolymer or an ethylene-unsaturated carboxylic acid copolymer that satisfies the conditions of the formula; and a polyethylene resin [B].
] 10 to 40 parts by weight of a composite biaxially oriented polypropylene resin film, characterized in that the surface of the low melting point resin layer has a rough surface state. The melt flow rate (g/10 min) of resin [A] made of ethylene-vinyl ester copolymer or ethylene-unsaturated carboxylic acid copolymer is MFR (a), and the melt flow rate of polyethylene resin [B] is When rate (g/10 minutes) is expressed as MFR (b), 3.0
≦MFR(a)≦50.0 (1) 0.2≦
MFR(b)≦5.0 (2) 4.0≦
MFR(a)/MFR(b)≦70.0・・・・・・
...(3) 2. Resin [A] made of an ethylene-vinyl ester copolymer or an ethylene-unsaturated carboxylic acid copolymer that satisfies the conditions of formulas (1) to (3) below. By stretching a laminate of a resin layer and a polypropylene resin layer melted and extruded by a mixed resin containing 60 to 90 parts by weight and 40 to 10 parts by weight of polyethylene resin [B], the polypropylene A method for producing a composite biaxially stretched polypropylene resin film, the method comprising introducing biaxial stretching into a polypropylene resin layer. The melt flow rate (g/10 min) of resin [A] made of ethylene-vinyl ester copolymer or ethylene-unsaturated carboxylic acid copolymer is MFR (a), and the melt flow rate of polyethylene resin [B] is When rate (g/10 minutes) is expressed as MFR (b), 3.0
≦MFR(a)≦50.0 (1) 0.2≦
MFR(b)≦5.0 (2) 4.0≦
MFR(a)/MFR(b)≦70.0・・・・・・
・・・・・・(3)