JPH09143339A - Propylene block copolymer composition and its use - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate having good antiblocking properties, excellent peelability, heat-sealability and transparency. SOLUTION: This laminate is prepared by laminating a layer comprising a propylene block copolymer composition comprising 100 pts.wt. propylene block copolymer comprising 1-70wt.% polypropylene component or propylene random copolymer component containing above 90mol% units derived from propylene and 30-99wt.% propylene/ethylene random copolymer component comprising 10-40 mol % units derived from ethylene and 90-60mol% units derived from pyopylene and having a weight-average molecular weight (Mw)/number- average molecular weight (Mn) ratio of 1-4 and 5-70 pts.wt. petroleum resin on at least either surface of a base layer.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a propylene block copolymer composition and its use, more specifically, a propylene block copolymer composition suitable as a material for a heat seal layer and a material for a heat seal layer. It relates to a laminate used as.

[0002]

2. Description of the Related Art When an article is wrapped in a film and sealed,
Heat-sealing of film packaging pieces is performed. At that time, it is known to use a film obtained by laminating a heat-sealing layer made of a polyolefin-based thermoplastic resin such as polypropylene or polyethylene on the surface of a base material layer.

[0003]

By the way, in such a heat-sealing package, the joint portion between the heat-sealed package pieces has an appropriate strength such that the package can be easily opened by hand when the package is opened. Is required.

Further, it is required that the joint portion has good peelability when the package is opened. That is, in a laminated film having a heat seal layer made of the polyolefin-based thermoplastic resin, usually, when the bonding portion is to be peeled, stringing and fuzzing are likely to occur,
Smooth peeling does not occur at the interface between the package pieces to be welded or inside the heat seal layer, and the joint portion does not separate again into the original package pieces, and the thickness of either one of the package pieces in the middle of the joint portion. The base layer is torn in the direction. Such a phenomenon leads to poor appearance of the article at the time of opening and lowers the commercial value of the article. In addition, there is a risk that the film is largely broken and the contents fall during the opening process, starting from the torn portion.

For these reasons, it has been desired to solve the above-mentioned drawbacks and to develop a heat-sealing film having excellent peelability, heat-sealing property and unsealing property.

In the background described above, in order to solve the above-mentioned problems, the present inventors have designed a block copolymer having a specific composition, that is, a) a polypropylene component or a propylene-based monomer unit to be 90 mol. % Of propylene-based random copolymer component 1 to 70% by weight, b) 10 to 40 mol% of ethylene-based monomer units and 90 to 60 mol% of propylene-based monomer units propylene-ethylene Random copolymer component 30 to 99% by weight, weight average molecular weight (Mw) / number average molecular weight (M
A laminated heat-sealing film was proposed in which a resin layer made of a propylene-based block copolymer in which n) is 1 to 4 is laminated on at least one film surface (Japanese Patent Application No. 7-52983).

This laminated heat-sealing film is excellent in peelability, heat-sealing property, and transparency, and when peeling off the bonded portion which is heat-sealed after heat-sealing, both films are bonded at the interface or surface layer portion. It is an extremely excellent packaging film that peels well.

However, in view of the long-term stock of the film and the machine running property such as automatic packaging, the laminated heat-sealing film had some room for improvement in the blocking prevention property of the film. To solve these problems,
It is possible to add a relatively large amount of an anti-blocking agent, a lubricant or the like to the propylene-based block copolymer, but in that case, although the blocking prevention property is improved,
The adverse effect that the transparency is deteriorated occurs.

In view of the above background, it is an object of the present invention to provide a laminate having good anti-blocking properties and excellent peelability, heat sealability and transparency.

[0010]

[Means for Solving the Problems] The present inventors have conducted extensive studies to solve the above problems. As a result, they have found that the above problem can be solved by using a propylene-based block copolymer composition in which a block copolymer having a specific composition and a petroleum resin are mixed in a specific ratio, and have completed the present invention.

That is, the present invention relates to A) a) a polypropylene component, or 1 to 70% by weight of a propylene-based random copolymer component containing more than 90 mol% of propylene-based monomer units, and b) a monomer based on ethylene. Propylene-ethylene random copolymer component containing 10 to 40 mol% of monomer units and 90 to 60 mol% of propylene-based monomer units. 30 to 99% by weight, and weight average molecular weight (Mw) / number average molecular weight. A propylene block copolymer composition comprising 100 parts by weight of a propylene-based block copolymer having (Mn) of 1 to 4 and 5) to 70 parts by weight of B) petroleum resin.

The present invention also provides a laminate comprising a base material layer and a layer comprising the propylene block copolymer composition laminated on at least one surface of the base material layer.

The propylene-based block copolymer which is the main component of the composition of the present invention comprises a) a polypropylene component or a propylene-based random copolymer component containing more than 90 mol% of propylene-based monomer units, b) A propylene-ethylene random copolymer component containing 10 to 40 mol% of ethylene-based monomer units and 90 to 60 mol% of propylene-based monomer units. Here, the ratio of the a) polypropylene component or the propylene random copolymer component and the b) propylene-ethylene random copolymer component is 1 to 70% by weight in the former case.
It is preferably 3 to 60% by weight, and the latter is 30 to 99% by weight, preferably 40 to 97% by weight. If the content of the a) polypropylene component or propylene-based random copolymer component is less than 1% by weight, the mechanical strength of the resulting laminate, particularly the heat seal film, will decrease, and if it exceeds 70% by weight, it will be obtained. It is not preferable because the peelability, heat sealability, and transparency of the resulting laminate, particularly the heat seal film, are reduced.

As the monomer unit other than the propylene-based monomer unit in the propylene random copolymer component a), units based on other known monomers copolymerizable with propylene are not limited. Can be adopted. Preferably, a monomer unit based on ethylene and an α-olefin having 4 to 12 carbon atoms is used, and these may be used alone or in combination of two or more. Particularly, a monomer unit based on ethylene and an α-olefin having 4 to 8 carbon atoms is preferable. The content ratio of the monomer units other than the monomer unit based on propylene needs to be less than 10 mol%. When the content ratio is 10 mol% or more and the content ratio of the propylene-based monomer unit is 90 mol% or less, the resulting laminate has a strong tackiness and becomes difficult to handle. Further, the content ratio of the monomer unit other than the propylene-based monomer unit is preferably 2 mol% or more.

In the propylene-ethylene random copolymer component b), the content ratio of each of the ethylene-based monomer unit and the propylene-based monomer unit is
10 to 40 mol%, preferably 15 to 35 mol%, of monomer units based on ethylene; 90 to 60 mol%, preferably 85 to 65 mol%, of monomer units based on propylene
It is. The content ratio of ethylene-based monomer units is 10
When it is less than mol% and the content ratio of the monomer unit based on propylene exceeds 90 mol%, the resulting laminate has insufficient peelability, which is not preferable. On the other hand, when the content ratio of ethylene-based monomer units exceeds 40 mol% and the content ratio of propylene-based monomer units is less than 60 mol%, the blocking resistance of the resulting laminate decreases, It is not preferable because handling becomes difficult.

The propylene-ethylene random copolymer component contains a small amount of other α-olefin, for example, 5 mol% or less, as long as it does not impair the physical properties of the propylene block copolymer of the present invention. It may be polymerized and contained. The other α-olefin is not particularly limited, and may be one or more α-olefins having 4 to 12 carbon atoms, and is preferably an α-olefin having 4 to 8 carbon atoms.

The propylene block copolymer of the present invention is preferably 10% by weight in addition to the above a) polypropylene component or propylene random copolymer component and b) propylene-ethylene random copolymer component.
In the following range, other α-olefin polymer components may be contained. As the α-olefin, those described above are used without limitation. Preferably, the polybutene component is good.

In the propylene block copolymer used in the present invention, a) a polypropylene component or a propylene random copolymer component and b) a propylene-ethylene random copolymer component are usually arranged in one molecular chain. A so-called block copolymer molecular chain and a molecular chain consisting of a) a polypropylene component or a propylene-based random copolymer component and b) a propylene-ethylene random copolymer component alone cannot be achieved by mechanical mixing. It is considered that they are mixed in a micro degree to some extent.

In the present invention, it is necessary that the propylene block copolymer has a molecular weight distribution narrowed to a specific value. Specifically, the weight average molecular weight (Mw) / number average molecular weight (Mn) measured by gel permeation chromatography (hereinafter abbreviated as “GPC”) is 1 to 4, preferably 1.2 to 3.5, More preferably 1.
It is in the range of 5 to 3. Within this range, the resulting laminate has excellent strippability and is preferable in that it has no stickiness.

Further, as the propylene-based block copolymer, one having a weight average molecular weight (Mw) of 100,000 or more, generally 150,000 or more is generally used. The melt flow rate (hereinafter abbreviated as MFR) is preferably 0.1 to 20 g / 10 minutes, preferably 0.5 to 15 g / 10 minutes, in consideration of the film forming property. Further, the main peak in the differential scanning calorimetry (DSC) may be in the range of 120 to 160 ° C, preferably 125 to 155 ° C, in consideration of the heat sealing start temperature and the sticking property to the roll at the time of forming the laminate. It is good.

In the present invention, such a propylene-based block copolymer may be polymerized by any known method as long as it has the above-mentioned properties. Further, it may be obtained by decomposing a polymerized propylene-based block copolymer with an organic peroxide.

On the other hand, the petroleum resin used in the composition of the present invention is not particularly limited, but specific examples thereof include an aliphatic hydrocarbon resin, an alicyclic hydrocarbon resin, a rosin derivative, a terpene resin and a terpene. Phenol resins and the like and hydrogenated resins thereof and the like can be mentioned. Of these, hydrogenated hydrocarbon resins are particularly preferable because they have good transparency. The softening point of these hydrocarbon resins is 60 when the operability and blending processability of the resin are taken into consideration.
To 160 ° C. is preferable, and further 70 to 15
The temperature is more preferably 0 ° C. The melt viscosity is 160 ° C when blending processability and extrusion characteristics of the composition are taken into consideration.
Is preferably 500 to 200,000 cps,
More preferably, it is 700 to 100,000 cps.

Taking into consideration blending processability, extrusion properties of the composition, antiblocking property of the laminate, and strippability, the blending amount of the petroleum resin in the composition is based on 100 parts by weight of the propylene block copolymer. Suitably 5 to 70 parts by weight, preferably 10 to 60 parts by weight. The propylene block copolymer and the petroleum resin may be blended by any method, but it is usually preferable to mix them by an extrusion kneader in a heating and melting state.

The propylene-based block copolymer composition may further contain known antistatic agents, antifogging agents, antiblocking agents, antioxidants, light stabilizers, crystal nucleating agents, lubricants, etc., if necessary. You may mix and use an additive material.
Further, other resins can be mixed to the extent that the physical properties of the present invention are not impaired. The resin to be mixed is not particularly limited, but, for example, a homopolymer or a copolymer of olefins such as propylene, ethylene, and butene, or a mixture of two or more of these is preferable. The amount added is not particularly limited, but is preferably 50% by weight or less, more preferably 40% by weight or less.

Next, in the present invention, the propylene block copolymer composition described above may be used for any purpose. It is preferable to use a layer of the propylene block copolymer composition laminated on at least one surface of the base material layer. In that case, this laminate is suitable for heat-sealing applications because of the excellent strippability, heat-sealing property, and transparency of the propylene-based block copolymer composition of the present invention. Further, since the propylene-based block copolymer composition is also excellent in antiblocking property, this laminate also has excellent properties. In particular, the laminate is preferably a laminated film for heat sealing.

In such a laminate, the base material layer may be of any type, but preferably in consideration of moldability, the main peak in DSC is 120 to 250 ° C., more preferably 130 to 170 ° C. It is preferably composed of a resin layer. Generally, a resin layer made of a polyolefin is preferable, and specifically, ethylene, propylene, butene, a homopolymer of an olefin such as methylpentene, or a copolymer can be mentioned. Among these, polypropylene is preferable. It is particularly suitable. These resins that can be used as the base material layer may be used alone or in combination of two or more.

As the polypropylene used for the base material layer,
Propylene homopolymer, 90 mol% or more of propylene and α-olefin other than propylene, such as ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 4-methyl-1-pentene, etc. 10 or more seeds
Random or block copolymers with up to mol% can generally be used. Considering the moldability, the MFR is preferably in the range of 0.5 to 20 g / 10 minutes.

The resin used for such a base material layer may include an antistatic agent, an antifogging agent, an antiblocking agent, if necessary.
Known additives such as antioxidants, light stabilizers, crystal nucleating agents and lubricants may be added.

In the present invention, the thickness of the laminate is not particularly limited, but it is usually 10 to 1000 μm, preferably 15 to 600 μm. In addition, the thickness of the surface layer formed of the propylene block copolymer composition is generally selected from the range of 0.1 to 100 μm.

The method for forming the laminate is not particularly limited and any method may be used. Generally,
The powder or pellets of the propylene-based block copolymer composition, alone or as the case may be, is sufficiently mixed with powders or pellets of other resins, and then coextruded with the resin component of the base material layer to obtain a temperature-controlled chill roll. Rapidly cooled to form a film without stretching, or further uniaxially or biaxially stretched, or melt-extruded one layer of resin and uniaxially stretched, melt-extruded the resin of the other layer on it and uniaxially stretched A method of stretching in a direction substantially perpendicular to the direction is adopted. As an example of longitudinal uniaxial stretching, generally, a film is passed between a roll that rotates at a low speed at the forefront and a roll that rotates at a high speed at the rearmost part, and stretched according to the rotation speed ratio of both rolls. On the other hand, as an example of lateral uniaxial stretching, it is preferable to perform the tenter method. In addition, longitudinal and transverse sequential biaxial stretching by the method shown above,
Simultaneous biaxial stretching and the like are also possible. The stretching ratio is preferably 5 to 60 times, more preferably 30 to 50 times in terms of area ratio.

The above is the case of the flat shape, but in addition to this, it is also possible to perform longitudinal uniaxial, lateral uniaxial, simultaneous biaxial stretching etc. on the tube-shaped original fabric by the inflation method. In this case, the raw fabric is heated to, for example, 80 to 150 ° C., pressurized air is fed into the tubular film to form a film without stretching, or uniaxially stretched in the longitudinal or transverse directions, or simultaneously biaxially in the longitudinal and transverse directions. It may be stretched.

The propylene-based block copolymer composition used in the present invention is compatible with polypropylene at an arbitrary ratio and also has good compatibility with polyethylene. Therefore, in the laminate of the present invention, the non-conforming product of the surface layer portion at the time of molding can be regenerated and reduced as the material of the base material layer when such polypropylene or polyethylene is used as the material of the base material layer. However, it can also be recycled for other uses of polypropylene-based or polyethylene-based molded products. Furthermore, when the material resin of the base material layer is polypropylene or polyethylene, the incompatible product of the laminate can be melt-kneaded to uniformly mix the composition of the surface layer with the polypropylene or polyethylene of the base material layer, Similarly, it is easy to recycle.

[0033]

EFFECT OF THE INVENTION The polyolefin composition of the present invention is not only heat-sealed to form a structure having excellent sealing reliability, but also is excellent in peelability, easy-opening property and antiblocking property. Therefore, a laminate in which a layer made of such a propylene-based block copolymer composition is laminated on at least one surface of the base material layer can be favorably used for heat sealing applications. In particular, this laminate, when peeling off the fusion bonded portion after heat sealing, both laminates do not peel at the interface or surface layer portion, and one of the base layers is torn and separated. Is suppressed. The surface layer of this laminate is
The transparency is also good, and therefore, when a material having a good transparency such as polypropylene is used as the material resin for the base material layer, the laminate also has a good transparency.

[0034]

EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples.

The compositions used as the surface layer in the examples and comparative examples are shown in Table 1.

[0036]

[Table 1]

The measuring method used in the following examples and comparative examples was carried out by the following method.

(1) Number average molecular weight (Mn), weight average molecular weight (Mw) It was measured by GPC (gel permeation chromatography) method. This was carried out at 135 ° C. using GPC-150C manufactured by Waters, using O-dichlorobenzene as a solvent. The column used was Tosoh TSK gel GMH
6-HT, gel size 10-15 μm. The calibration curve has a weight average molecular weight of 950, 2900,
It was prepared using 10,000, 50,000, 49,980, 2.7, and 6.75 million polystyrene.

(2) Measurement of Ratio of Monomer Units Based on Ethylene and Monomer Units Based on Propylene in Propylene-Ethylene Random Copolymer Component Each was calculated using a ¹³ C-NMR spectrum chart.
That is, the respective proportions of the monomer units based on ethylene and the monomer units based on propylene in the propylene-ethylene random copolymer component are first determined by the polymer (P
polymer, Vol. 29 (1988), p. 1848, and then the assignment of peaks was determined, followed by the method described in Macromolecules, Vol. 10, (1977) p. 773. The respective proportions of the monomer units based on ethylene and the monomer units based on propylene were calculated.

Next, the weight and proportion of the polybutene component were calculated from the integrated intensity ratio of the peak derived from methyl carbon in the monomer unit and the peak derived from methyl carbon in the polybutene component based on propylene.

(3) Melt flow rate (MFR) Measured according to JIS K7210.

(4) Softening point Measured according to JIS K2207 (ring and ball method).

(5) Melt viscosity Measured by a viscosity method (B-type viscometer).

(6) Measurement of main peak by DSC After weighing about 5 to 6 mg of sample, the sample was sealed in an aluminum pan and heated from room temperature to 235 ° C. or 270 ° C. in a nitrogen flow of 20 ml / min with a differential calorimeter. Raise the temperature to 1 at these temperatures
Hold for 0 minutes, then cool to room temperature at 10 ° C / min. Thereafter, the temperature of the main peak was measured by a melting curve obtained at a heating rate of 10 ° C./min.

(7) Transparency The haze value was measured according to JIS-K6714.

(8) Heat-sealing property (heat-sealing start temperature) The heat-sealing surfaces of the laminated heat-sealing film are 5
Using a heat-seal bar of × 200 mm, at each set temperature (measured at every 5 ° C from 80 ° C to 155 ° C), the heat-sealing pressure is 1 kg / cm 2, and the heat-sealing time is 1.0.
A sample with a width of 15 mm is cut out from the sample sealed under the condition of 10 seconds, and the tensile speed is 100 mm /
Measured in minutes. The results were average values of five samples. From the heat seal curve obtained by the above method, the temperature at which the heat seal strength was 300 g / 15 mm was taken as the heat seal start temperature.

(9) Peelability Heat seal start temperature and further 5 ° C. and 10 ° C.
For samples heat-sealed at high temperatures, 10
Among the 30 samples in total, which were measured for each sample, the bonding portion was not peeled at the interface between the two films or the surface layer portion, and the number of those in which the base layer of one of the films was torn and separated was determined. The criteria are as follows.

[0048]

[Table 2]

(10) Anti-blocking property After the film was formed, it was cured at 40 ° C. for 2 days, and then two films (12
X 12 cm) and apply a load of 10 kg,
After leaving it in an atmosphere of temperature 40 ° C and humidity 90% RH for 24 hours,
A sample is cut into a size of 4 × 4 cm, and a tensile tester (speed:
Shear peel strength was measured at 100 mm / min).

Example 1 The resins for the base layer and the surface layer shown in Table 3 were coextruded under heating and melting at 260 ° C. using a three-layer T-die extruder, and a longitudinal direction of 4 by a tenter method biaxial stretching machine. A laminated film stretched 5 times and laterally 9 times was obtained. The thickness, haze, heat sealability, strippability, and blocking resistance of the obtained film were measured, and the results are shown in Table 4.

Example 2 The resins for the base layer and surface layer shown in Table 3 were coextruded under heating and melting at 260 ° C. using a three-layer T-die extruder, solidified by cooling on a chill roll, and two layers without stretching. I got a film. The thickness, haze, heat sealability, strippability, and blocking resistance of the obtained film were measured, and the results are shown in Table 4.

Example 3 The resin of the base layer shown in Table 3 was mixed with a T-die extruder to obtain 2
The mixture was extruded into a sheet under heating and melting at 80 ° C., cooled and solidified on a chill roll, and then stretched 4.5 times with a heating roll stretching machine to obtain a uniaxially stretched sheet. Then, the resin for the surface layer shown in Table 3 was extruded into a sheet form under heating and melting at 280 ° C. using a two-layer T-die extruder, and laminated with the uniaxially stretched sheet on a roll to obtain a three-layer sheet. Then, it was continuously stretched 9 times by a transverse stretching machine. The thickness, haze, heat sealability, strippability, and blocking resistance of the obtained film were measured, and the results are shown in Table 4.

Examples 4 to 8 In Example 3, as the resin for the base layer and the surface layer, Table 3
A film was obtained in the same manner as in Example 3 except that the above-mentioned one was used. The thickness of the obtained film, haze,
The heat sealability, strippability, and blocking resistance were measured, and the results are shown in Table 4.

Comparative Examples 1 to 3 In Example 3, as a resin for the base layer and the surface layer, Table 3
A film was obtained in the same manner as in Example 3 except that the above-mentioned one was used. The thickness of the obtained film, haze,
The heat sealability, strippability, and blocking resistance were measured, and the results are shown in Table 4.

[0055]

[Table 3]

[0056]

[Table 4]

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Claims (2)

[Claims] 1. A) a) a polypropylene component, or 1 to 70% by weight of a propylene-based random copolymer component containing more than 90 mol% of a propylene-based monomer unit, and b) an ethylene-based monomer unit. 10 to 40 mol%, propylene-ethylene random copolymer component containing 90 to 60 mol% of a propylene-based monomer unit 30 to 99 wt%, and the weight average molecular weight (Mw) / number average molecular weight (Mn) is A propylene block copolymer composition comprising 100 parts by weight of propylene-based block copolymer of 1 to 4 and 5 to 70 parts by weight of B) petroleum resin. 2. A laminate in which a layer made of the propylene block copolymer composition according to claim 1 is laminated on at least one surface of a base material layer.