JPH06263935A - Polyolefin composition - Google Patents

Abstract

PURPOSE:To obtain a polyolefin composition having excellent low-temperature heat sealability, transparency and anti-block property and useful as a heat- sealing layer of a polypropylene film. CONSTITUTION:This polyolefin composition contains (A) 95-5 pts.wt. of a propylene.1-butene random copolymer having a propylene content of 55-85mol%, a heat of crystal fusion of 10-80 Joule/g and an intrinsic viscosity of 0.02-0.7dL/g and (B) 5-95 pts.wt. of an isotactic polypropylene.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyolefin composition, and more particularly to a polyolefin composition excellent in low temperature heat sealability, transparency, blocking resistance and scratch resistance and suitable for a heat seal layer of a polypropylene film.

[0002]

2. Description of the Related Art Propylene / 1-butene random copolymers are low density polyethylene, ethylene / propylene copolymers, ethylene / vinyl acetate copolymers, soft vinyl chloride resins and other soft plastics. It has excellent properties such as heat resistance, scratch resistance, abrasion resistance, and adhesion to polypropylene film, and also has good low temperature heat sealability, so it is considered to be used for heat seal layer of polypropylene film. Has been.

This propylene / 1-butene random copolymer has a drawback that if it is attempted to further improve the heat sealability at low temperature, only a film having poor blocking resistance and scratch resistance can be obtained. To remedy this drawback, it has been proposed to use a blend of isotactic polypropylene and a propylene / 1-butene random copolymer with a specific MFR in the heat seal layer of the film. (Japanese Patent Publication 57-24374
Issue)

In recent years, a laminated film in which a heat-sealing layer is provided on both sides or one side of a biaxially oriented polypropylene film has been used for overlapping packaging of boxes such as cigarettes and confectionery boxes and cases of cassette tapes. There is. This heat seal layer is conventionally formed of a composition containing a propylene / ethylene random copolymer, a propylene / 1-butene random copolymer, an ethylene / butene random copolymer, etc. as a main component.

[0005]

However, with the above blend of isotactic polypropylene and propylene / 1-butene random copolymer, a heat-sealable film having sufficient transparency and blocking resistance cannot be obtained. It was In addition, the composition containing the propylene / ethylene random copolymer, the propylene / 1-butene random copolymer, the ethylene / butene random copolymer, etc. as a main component has a too high heat seal strength, so the packaging is removed. Sometimes it becomes difficult to peel off the heat seal part,
Alternatively, even if it can be peeled off, the heat seal strength becomes larger than the tear strength of the biaxially oriented polypropylene film as the base material, and there is a drawback that not only the heat seal portion but also other portions are torn.

Therefore, an object of the present invention is to provide excellent low-temperature heat sealability, transparency and blocking resistance,
It is to provide a polyolefin composition suitable as a heat-sealing layer for a polypropylene film.

[0007]

In order to solve the above-mentioned problems, the present invention has a propylene content of 55 to 85 mol%, a heat of fusion of crystal of 10 to 80 Joule / g and an intrinsic viscosity of 0.0.
Provided is a polyolefin composition containing 5 to 95 parts by weight of an isotactic polypropylene (B) with respect to 95 to 5 parts by weight of a propylene / 1-butene random copolymer (A) of 2 to 0.7 dl / g. It is a thing.

It is preferable that the propylene / 1-butene random copolymer (A) has a propylene content of 60 to 82 mol%.

It is preferable that the propylene / 1-butene random copolymer (A) has a heat of crystal fusion of 20 to 70 Joule / g.

Hereinafter, the polyolefin composition of the present invention will be described in detail.

The polyolefin composition of the present invention (hereinafter,
The propylene / 1-butene random copolymer (A), which is the main component of the "composition"), has a repeating structural unit derived from propylene and a repeating structural unit derived from 1-butene in the molecular chain. It is a copolymer randomly distributed in.

The propylene content of the propylene / 1-butene random copolymer (A) has a good compatibility with the isotactic polypropylene which is the component (B) described later and has a good compatibility. Therefore, a composition having excellent optical characteristics can be obtained.
˜85 mol%, preferably 60 to 82 mol%.

The heat of fusion of crystals of the propylene / 1-butene random copolymer (A) is excellent in transparency, low temperature heat sealability and blocking resistance, and a composition which does not have a sticky feeling when molded is obtained. 10 to 80 J in terms of points obtained
oule / g, preferably 20 to 70 Joule / g. This heat of crystal fusion is an amount that correlates with the crystallinity of the polymer, and is a specific heat curve in a completely melted state of the copolymer measured by a differential scanning calorimeter (preferably a specific heat of 160 ° C. or higher and 240 ° C. or lower). It is a value obtained by using a straight line obtained by extrapolating the (curve) directly on the low temperature side as a baseline. The melting point or the heat of fusion of the sample is 200 ° C.
After leaving it for 5 minutes at -40 ℃ at a cooling rate of 10 ℃ / min
Cool to 40 ° C and leave at -40 ° C for 5 minutes. Then 20
It is carried out under the measurement condition that the temperature is raised from -40 ° C to 200 ° C at a heating rate of ° C / min.

Furthermore, the intrinsic viscosity [η] of the propylene / 1-butene random copolymer (A) is
0.02 to 0 in that the compatibility between the 1-butene random copolymer (A) and the isotactic polypropylene is good, the composition has excellent optical properties, and a suitable heat seal strength is obtained. It is 0.7 dl / g, preferably 0.1 to 0.7 dl / g. This intrinsic viscosity [η]
Is the value measured in decalin at 135 ° C.

In the present invention, the propylene / 1-butene random copolymer (A) has a propylene content of 60.
-82 mol%, heat of fusion of crystal 20-70 Joule / g and intrinsic viscosity [η] 0.1-0.7 are blended with isotactic polypropylene (B) to obtain optical properties and low temperature heat seal. It is particularly preferable in that a composition having excellent properties can be obtained.

The propylene / 1-butene random copolymer (A) used in the present invention can be produced, for example, by (a) a complex containing at least magnesium, titanium and halogen, (b) Group 1 of the periodic table. ~ It can be carried out by a method in which propylene and 1-butene are randomly copolymerized using a catalyst composed of an organometallic compound of a metal element of Group 3 and (c) an electron donor. Part or all of the electron donor (c) may be fixed to part or all of the composite (a), or may be pre-contacted with the organometallic compound (b) prior to use. Good.
Particularly preferred is a mode in which a part of the electron donor (c) is fixed to the composite (a), and the rest is added to the polymerization system as it is, or pre-contacted with the organometallic compound (b). It is a catalyst. With such a catalyst system, a copolymer with less methyl acetate solubles is obtained. In this case, the electron donor fixed to the composite (a) may be the same as or different from the electron donor used as it is in addition to the polymerization system or used in pre-contact with the organometallic compound (b). It may be one.

In the above polymerization reaction, a propylene / 1-butene random copolymer having a desired molecular weight can be obtained by appropriately selecting the polymerization conditions such as the polymerization temperature and the use ratio of the catalyst component. Adding hydrogen to the polymerization system is effective in controlling the molecular weight. Particularly, propylene having an intrinsic viscosity [η] of 0.02 to 0.7 dl / g.
In order to obtain a 1-butene random copolymer, it is effective to add a large amount of hydrogen.

Further, propylene-1 used in the present invention
-The butene random copolymer (A) may be directly produced by the above-mentioned polymerization reaction, but by the above-mentioned polymerization reaction, first,
After producing a propylene / 1-butene random copolymer having an intrinsic viscosity higher than a desired range, for example, an intrinsic viscosity [η] of 1 to 6, the propylene / 1-butene random copolymer is thermally decomposed to obtain an ultimate viscosity. Viscosity [η] is 0.02 to 0.7
A dl / g propylene / 1-butene random copolymer (A) can also be produced. According to this method by thermal decomposition, compared with the method of directly producing by polymerization reaction,
There is an advantage that a desired propylene / 1-butene copolymer can be obtained with high yield and high efficiency. This thermal decomposition is carried out in an inert atmosphere such as nitrogen in a propylene having an intrinsic viscosity higher than a desired range, for example, an intrinsic viscosity [η] of 1 to 6
It can be carried out by a method of thermally decomposing the 1-butene random copolymer. The temperature of thermal decomposition is 360 to 43.
The temperature is 0 ° C, preferably 380 to 410 ° C. Further, the method of thermal decomposition is propylene having an intrinsic viscosity [η] of 1 to 6
1-butene random copolymer is fed to the extruder, heated,
A method of thermally decomposing while kneading and extruding; a method of charging a propylene / 1-butene random copolymer having an intrinsic viscosity [η] of 1 to 6 into a thermal decomposition reactor, and thermally decomposing it with stirring in a batch method. Can be mentioned.

The isotactic polypropylene which is the component (B) of the composition of the present invention is a homopolymer of propylene having a boiling n-heptane extraction residue of 85% or more, or propylene as a main component. It is a copolymer with α-olefin, and the content of other α-olefin is 10 mol% or less, preferably 5 mol% or less. Examples of the other α-olefin include ethylene and 1-butene.

Propylene / 1- in the composition of the present invention
The blending ratio of the butene random copolymer (A) and the isotactic polypropylene (B) is such that 95 to 5 parts by weight of the propylene / 1-butene random copolymer (A) is equivalent to 5 parts of the isotactic polypropylene (B). ~ 95 parts by weight.

In the composition of the present invention, in addition to the propylene / 1-butene random copolymer (A) and the isotactic polypropylene (B), if necessary,
You may mix | blend various compounding agents, such as a well-known heat stabilizer, a weather stabilizer, a nucleating agent, an antiblocking agent, an antifogging agent, a pigment, a dye, a filler, a lubricant, an antistatic agent, and a flame retardant.

The composition of the present invention can be produced according to a conventional method and is not particularly limited. For example,
The propylene / 1-butene random copolymer (A) and isotactic polypropylene (B) and, if necessary, the above compounding ingredients were mixed using a mixer such as a V-type blender, a tumbler mixer, a Henschel mixer. After that, it can be produced by supplying to an extruder, a kneader, a Banbury mixer or the like and kneading.

The composition of the present invention is best used as a heat seal layer for films. In addition, the film can be formed according to a conventional method and is not particularly limited. For example, a method of supplying the composition of the present invention to an extruder and melting it, extruding the melt into a film form from a T-die, and cooling and solidifying with a cooling roll to obtain a single film composed of only the composition of the present invention. (Also, a method of laminating this single film to a film made of another polymer to obtain a composite film);
-In the flow pipe before entering the die, or in the T-die or T
Immediately after being extruded from the die, by joining with a melt of another polymer (eg polypropylene) which constitutes the substrate,
It can be carried out by any method such as a method of obtaining a composite film comprising the composition of the present invention and another polymer. When the composition of the present invention is used for the heat-sealing layer of a film, it may be formed on both surfaces of the composite film, or may be formed on only one surface. Furthermore, a single film or a composite film can be used as a stretched film obtained by stretching in a longitudinal or lateral direction or in both directions. The composition of the present invention is particularly preferably used as a heat seal layer of a stretched composite film.

[0024]

EXAMPLES Examples and comparative examples of the present invention will be given below.
The present invention will be specifically described, but the present invention is not limited to these examples. Further, in the following, the physical properties of the film were evaluated according to the following methods.

Haze Measured according to the method of ASTM D1003.

Glossiness Measured according to the method of ASTM D523.

Blocking resistance: Measured according to ASTM D1893.

Heat-seal adhesive strength Films are superposed on each other, and 90 ° C, 100 ° C, 110
Samples were prepared by heat-sealing the seal bar at a width of 5 mm for 1 second at temperatures of 120 ° C., 120 ° C., 130 ° C., 140 ° C. and 150 ° C. and at a pressure of ² kg / cm ² , and then allowing to cool. A test piece having a width of 15 mm was cut from the obtained sample, and the strength when the heat-sealed portion was peeled off was measured at a crosshead speed of 200 mm / min. Also,
Visually observe the state of the release surface, the base film does not tear,
The peeled layers were represented by ◯, and the layers that were broken up to the base film were represented by x.

(Example 1) [Production of propylene / 1-butene random copolymer] 200 g of anhydrous magnesium chloride, 46 ml of ethyl benzoate
Then, 30 ml of methyl polysiloxane and 30 ml of methyl polysiloxane were charged into a ball mill, kneaded in a nitrogen atmosphere, and then added to titanium tetrachloride to prepare a suspension. The solid content obtained by filtering this suspension had a titanium concentration of 0.01 mmol / l.
So that the concentration of triethylaluminum in the polymerization vessel is 1.0 mmol / l, and the concentration of methyl p-toluate is 0.33 mmol / l in the polymerization vessel.
So as to be charged into a stainless steel polymerization vessel having an internal volume of 20 l equipped with a stirrer, and n-heptane as a polymerization solvent, mixed gas of propylene and 1-butene (68 mol% of propylene, 32 mol of 1-butene). %) 4k / h
It was supplied at a flow rate of 1 and a copolymerization reaction was carried out at 70 ° C. The nuclear magnetic resonance spectrum of the obtained propylene / 1-butene random copolymer was measured to determine the propylene content, which was 71.0 mol%. Further, when the melting point, the heat of fusion and the intrinsic viscosity [η] were measured, each was 110
C., 50 Joule / g, 20, dl / g.

[Thermal Decomposition of Copolymer] The propylene / 1-butene random copolymer obtained above is fed to a twin-screw extruder (screw diameter: 30 mmφ) and heated at 400 ° C. for 2 hours.
It was thermally decomposed while being extruded at a screw rotation speed of 5 rpm. When the intrinsic viscosity [η] of the obtained pyrolyzed propylene / 1-butene random copolymer was measured in decalin at 135 ° C., it was 0.4 dl / g.

[Preparation of Composition] Propylene / ethylene random copolymer (ethylene content: 3.3 mol%, melt index (230 ° C.): 5.8, melting point: 142
° C., Density: 0.91g / cm ³⁾ (hereinafter, "PP-1"
Abbreviated), and the intrinsic viscosity [η] obtained above: 0.4 dl / g of pyrolyzed propylene.
After mixing 10 parts by weight of pellets of butene random copolymer (hereinafter, abbreviated as "PBC-1") with a tumbler blender for 10 minutes, the mixture was supplied to a 40 mmφ extruder.
A polyolefin composition was prepared while kneading at a resin temperature of 210 ° C.

Polypropylene (Propylene content: 10
0 mol%, melt index (230 ° C): 3.0
g / 10 min) and the olefin composition obtained above are fed to separate extruders and heated to 250 ° C. and 230 ° C., respectively.
Melt at 0 ° C., guide the resulting melt to a multi-manifold type T-die, merge the two melts at the outlet of the manifold, and extrude from the T-die, from the base material layer made of polypropylene and the olefin composition. A composite sheet having a two-layer structure having the following heat seal layer (base material layer / heat seal layer thickness ratio: 9/1) was molded and solidified by cooling in a drum at 40 ° C. The thickness of the obtained composite sheet is 1.5 m.
It was m.

Next, the composite sheet was heated to 13 with a heating roll.
After heating to 0 ° C. and stretching 5 times in the longitudinal direction to form a stretched film, the film is cooled to room temperature. The end portion of the obtained stretched film is held by a clip, introduced into a heating oven at 150 ° C., stretched 10 times in the width direction, and further heat-fixed while being relaxed by 5% in the width direction at 155 ° C. 30 μm
A composite film of The haze of the obtained composite film,
Gloss, blocking power and heat seal properties were evaluated or measured. The results are shown in Table 1.

(Examples 2 and 3) A polyolefin composition was produced in the same manner as in Example 1 except that PP-1 and PBC-1 were used in the compounding ratio shown in Table 1, and the obtained polyolefin was obtained. A composite film was formed using the composition in the same manner as in Example 1, and the physical properties thereof were evaluated or measured. The results are shown in Table 1.

(Examples 4 and 5) Instead of PP-1, propylene homopolymer (melt index (230 ° C):
6.2, melting point: 165 ° C., density: 0.91 g / cm ³ )
A polyolefin composition was produced in the same manner as in Example 1 except that the compounding ratio between (hereinafter, abbreviated as "PP-2") and PBC-1 obtained in Example 1 was as shown in Table 1. Then, using the obtained polyolefin composition, a composite film was formed in the same manner as in Example 1, and its physical properties were evaluated or measured. The results are shown in Table 1.

(Example 6) [Production of propylene / 1-butene random copolymer] In a mixed gas of propylene and 1-butene, the mixing ratio of propylene and 1-butene was 60 mol% of propylene and 1-butene, respectively. A copolymerization reaction was performed in the same manner as in Example 1 except that the amount was 40 mol% to produce a propylene / 1-butene random copolymer. Propylene obtained 1
The nuclear magnetic resonance spectrum of the butene random copolymer was measured to determine the propylene content, which was 68.1 mol%. Further, melting point, heat of fusion, intrinsic viscosity [η],
When the boiling n-heptane-insoluble matter and boiling methyl acetate-soluble matter were measured, they were respectively 103 ° C., 41 Joule / g,
0.55 dl / g, 0.5% and 0.6%.

[Film Forming] The propylene / 1-butene random copolymer obtained above (hereinafter referred to as "PBC-
2 ”) and PP-1 used in Example 1 except that the compounding ratio was as shown in Table 1, a polyolefin composition was produced in the same manner as in Example 1, and the composition was further prepared. The composite film was molded using the same method as in Example 1 and the physical properties were evaluated. The results are shown in Table 1.

(Example 7) [Production of propylene / 1-butene random copolymer] In a mixed gas of propylene and 1-butene, the mixing ratio of propylene and 1-butene was 70 mol% of propylene and 1-butene, respectively. A copolymerization reaction was performed in the same manner as in Example 1 except that the amount was 30 mol% to produce a propylene / 1-butene random copolymer. Propylene obtained 1
The nuclear magnetic resonance spectrum of the butene random copolymer was measured to determine the propylene content, which was 79 mol%. Further, the melting point, the heat of fusion, the intrinsic viscosity [η], the boiling n-heptane-insoluble matter and the boiling methyl acetate-soluble matter were measured to be 120 ° C., 57 Joule / g, and 0.
35 dl / g, 0.5% and 0.6%.

[Molding of Film] The propylene / 1-butene random copolymer obtained above (hereinafter referred to as “PBC-
3 ”) and PP-1 used in Example 1 except that the compounding ratio is as shown in Table 1, a polyolefin composition was produced in the same manner as in Example 1, and the composition was further prepared. The composite film was molded using the same method as in Example 1 and the physical properties were evaluated. The results are shown in Table 1.

(Examples 8 to 10) PP-1 / PBC-1
A polyolefin composition was produced in the same manner as in Example 1 except that the compounding ratio was changed to that shown in Table 1, and the composition was used to form a composite film in the same manner as in Example 1 to obtain various physical properties. Was evaluated. The results are shown in Table 1.

(Examples 11 and 12) Example 1 was repeated except that PP-2 was used in place of PP-1 and the mixing ratio of PP-2 / PBC-1 was as shown in Table 1. A polyolefin composition was produced by using the composition, and the composition was used to form a composite film in the same manner as in Example 1 to evaluate each physical property. The results are shown in Table 1.

(Example 13) PB instead of PBC-1
C-1 is used and the compounding ratio of PP-1 / PBC-2 is shown in Table 1.
A polyolefin composition was produced in the same manner as in Example 1 except that the above was performed, and a composite film was formed in the same manner as in Example 1 using the composition, and the respective physical properties were evaluated. The results are shown in Table 1.

(Example 14) PB instead of PBC-1
C-1 is used and the compounding ratio of PP-1 / PBC-3 is shown in Table 1.
A polyolefin composition was produced in the same manner as in Example 1 except that the above was performed, and a composite film was formed in the same manner as in Example 1 using the composition, and the respective physical properties were evaluated. The results are shown in Table 1.

Comparative Example 1 A composite film was formed in the same manner as in Example 1 except that PP-1 was used instead of the polyolefin composition without using the propylene / 1-butene random copolymer (PBC-1). Then, each physical property was evaluated. The results are shown in Table 1.

(Comparative Example 2) In Example 4, the propylene / 1-butene random copolymer (PBC-1) was not used, but only the propylene homopolymer (PP-2) was used instead of the polyolefin composition. A composite film was formed in the same manner as in Example 1 and each physical property was evaluated. The results are shown in Table 1.

Comparative Example 3 The propylene / 1-butene random copolymer used in Example 1 (hereinafter referred to as "PBC-
4 ”) was used without thermal decomposition.
A polyolefin composition was produced in the same manner as in 1., and a composite film prepared in the same manner as in Example 1 was formed by using the composition, and each physical property was evaluated. The results are shown in Table 1.

(Comparative Example 4) PBC-obtained in Example 1
Example 1 except that the compounding ratio of 1 was as shown in Table 1.
A polyolefin composition was produced in the same manner as in, and a composite film was formed using the composition in the same manner as in Example 1, and each physical property was evaluated. The results are shown in Table 1.

[0048]

[Table 1]

[0049]

[Table 2]

[0050]

[Table 3]

[0051]

The polyolefin composition of the present invention is excellent in low-temperature heat sealability, transparency and blocking resistance. Therefore, the polyolefin composition of the present invention is particularly suitable as a heat seal layer for polypropylene film.

Claims (3)

[Claims] 1. A propylene content of 55 to 85 mol%, a heat of crystal fusion of 10 to 80 Joule / g, and an intrinsic viscosity of 0.02.
A polyolefin composition containing 5 to 95 parts by weight of an isotactic polypropylene (B) with respect to 95 to 5 parts by weight of a propylene / 1-butene random copolymer (A) of 0.7 dl / g. 2. The polyolefin composition according to claim 1, wherein the propylene / 1-butene random copolymer (A) has a propylene content of 60 to 82 mol%. 3. The polyolefin composition according to claim 1, wherein the propylene / 1-butene random copolymer (A) has a heat of crystal fusion of 20 to 70 Joule / g.