JPH0859917A - Polypropylene-based resin composition and laminate - Google Patents

Abstract

PURPOSE: To obtain a polypropylene-based resin composition excellent in low- temperature heat sealability, hot tackiness and transparency and further adhesion to paper or a synthetic resin film. CONSTITUTION: This polypropylene-based resin composition comprises (A) 95-40wt.% polypropylene and (B) 5-60wt.% polyethylene-ethylene/butene- polyethylene triblock copolymer having >=100- -J/m<2> critical strain energy release rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a low temperature heat sealability,
The present invention relates to a polypropylene-based resin composition having excellent transparency as well as excellent adhesion to paper or a synthetic resin film, and a laminate using the polypropylene-based resin composition.

[0002]

2. Description of the Related Art Polypropylene is widely used because it has excellent properties such as heat resistance, rigidity, scratch resistance, moisture resistance and water resistance, and is inexpensive. For example, biaxially oriented polypropylene film, polyester film,
It can be bonded to polyamide films, aluminum foils, etc. by dry lamination and is used as a packaging material for food packaging. In addition, it is used for release paper, printing paper, thermal transfer paper, process paper for manufacturing artificial leather, etc. by laminating it with paper by extrusion lamination molding. However, polypropylene having such characteristics generally has a drawback that it has poor adhesion to a base film. Various methods have been proposed to solve this problem.

For example, polypropylene is non-polar,
There is a method of oxidizing the polypropylene surface because it is difficult to adhere to a polar substrate such as paper. Oxidation of the resin surface is mainly performed during lamination molding while polypropylene is in contact with air in a molten state, but a relatively high temperature is required to sufficiently perform oxidation. In the case of a polyolefin resin, this temperature is generally 300 ° C. or higher, and therefore, it is necessary to carry out laminating at a high temperature of 300 to 345 ° C. However, polypropylene is decomposed by heat at a high temperature of 300 ° C. or more and its molecular weight is lowered, so that not only the adhesiveness with a polar substrate such as paper is not improved but also problems such as chill roll contamination and smoke generation occur. . On the other hand, if molding is performed at a temperature of less than 300 ° C. in order to avoid thermal decomposition, there is a problem that the adhesiveness to the base material is insufficient and it cannot be put to practical use. Furthermore, even if it was formed at the upper limit temperature that does not cause thermal decomposition and some improvement in the adhesiveness to polar substrates such as paper could be achieved, this method is almost effective for polyolefin-based resin films. Does not bring

There is also a method of blending low-density polyethylene and high-density polyethylene in order to impart moldability at high temperature, but this method is not preferable because it causes a problem of decreasing the transparency of the polypropylene film.

A lot of other attempts have been made to date in which molding is performed at a temperature that does not cause thermal decomposition and yet adhesion to a substrate is imparted. For example, there is a method in which an adhesive called an anchor coat material is used in combination, but not only is the coating process complicated, but sufficient adhesive strength cannot be obtained when the polypropylene is little oxidized. There is also a method of applying corona discharge to the base material. However, in this case, it is necessary to separately prepare a special device.

Further, an ethylene-based copolymer resin such as an ethylene-propylene copolymer, a copolymer of ethylene-maleic anhydride- (meth) acrylic acid and its ester produced by a high pressure method capable of high temperature molding is used. Using the method of laminating once at high temperature and then laminating polypropylene at low temperature for the second time, ethylene-based copolymer resin at high temperature,
A coextrusion laminating method of laminating polypropylene at once at a low temperature, an ozone treatment method of blowing ozone to the polypropylene discharged from a die to oxidize the surface, and the like are performed. Of these, the method of laminating twice has the drawbacks that two laminating equipments are required in the production line, the process is complicated, and the laminating thickness becomes thick. Also,
In the case of coextrusion laminate with a temperature difference, the combined type in the die cannot make a sufficient temperature difference, and the combined type outside the die has a direct adverse effect on the product, that is, deterioration, odor, etc. are improved, Cannot solve the problems caused by smoking. Ozone treatment can oxidize only the surface that requires adhesion at low temperature, but ozone has problems such as odor and corrosiveness.
Its use is still limited.

[0007] As described above, in the laminate molding using polypropylene, it is difficult in the conventional technique to directly laminate the paper, the metal foil or the synthetic resin film with an economical method to provide sufficient adhesiveness. Is.

[0008]

Polypropylene has excellent properties such as heat resistance, scratch resistance, hardness and rigidity, but it has no polarity and is easily decomposed at high temperature.
There is a drawback that it is difficult to impart high adhesiveness to the base material.
In view of such circumstances, it is an object of the present invention to provide a polypropylene resin composition that does not impair the excellent properties of polypropylene such as transparency and that has excellent adhesiveness to a substrate.

[0009]

As a result of intensive studies, the present inventors have found that the above object can be achieved by blending polypropylene with a specific polyolefin-based elastomer, and based on this finding, The invention was completed. That is, the above-mentioned problems are (A) polypropylene 95 to 40% by weight and (B) polyethylene-ethylene / butene-polyethylene triblock copolymer 5 to 60 having a critical strain energy release rate of 100 J / m ² or more.
This is solved by a polypropylene-based resin composition containing 10% by weight. Hereinafter, the present invention will be described in detail.

As the polypropylene which is the component (A) used in the present invention, a propylene homopolymer or a propylene copolymer is used. The propylene copolymer refers to a block or random copolymer of propylene and α-olefin, and examples thereof include a propylene-ethylene copolymer and a propylene-1-butene copolymer. The copolymerization ratio of α-olefin is not particularly limited as long as it does not impair the properties of polypropylene, but is usually 1 to 20% by weight, preferably 2 to 10% by weight. Also, these copolymers contain a small amount of polyfunctional olefins such as 1,
9-decadiene, 1,4-hexadiene, isoprene,
A copolymer obtained by adding 1,3-butadiene or the like can also be used.

Melt flow rate of polypropylene (J
According to IS K6758, hereinafter referred to as MFR. ) Is generally 0.01 to 200 g / 10 min, 0.1 to 100
g / 10 minutes is preferable, and 1.0 to 50 g / 10 minutes is particularly preferable.

These polypropylenes may be used alone or in combination of two or more.

The polyethylene-ethylene / butene-polyethylene triblock copolymer (hereinafter referred to as triblock copolymer) which is the component (B) in the present invention is
The ethylene / butene copolymer block is located in the central part of the molecule, and the polyethylene blocks are located on both sides of the copolymer block. Generally, it can be produced by hydrogenating a polymer of butadiene. The length of each block unit cannot be specified, but the molecular weight is 400
It is preferably 0 or more.

The critical strain energy release rate (hereinafter also referred to as Gc) of this triblock copolymer is 100 J / m ^2.
It is necessary to be above, and 150 J / m ² or above is preferable. When Gc is less than 100 J / m ² , sufficient adhesive strength cannot be exhibited.

Here, the critical strain energy release rate is M
An asymmetric double critical strain energy release rate of a crack at a flat interface with FR of 30 g / 10 min, Mw / Mn of 7, and stereoregularity of 98% homo polypropylene (hereinafter referred to as standard polypropylene). The value measured in the cantilever beam method with a phase difference of −2 to −12 °. The asymmetric double cantilever beam method (hereinafter referred to as ADCB) was used to measure Gc in order to cause the crack to run along the interface. The parameter that determines the crack growth direction is the phase angle ψ defined by the following equation. ψ = tan ⁻¹ (K _II / K _I ) where K _I and K _II are stress intensity factors for mode I and mode II. The phase angle ψ depends on the geometry of ADCB, elastic modulus of each material, Poisson's ratio, and crack length.
Numerically, the boundary element method (BEM) and the finite element method (FE
Evaluated by M). In the present invention, Gc has a phase angle of −2.
It is necessary to measure in the range of -12 °. If the phase angle is less than -12 °, cracks at the interface penetrate into the thinner material, and Gc cannot be evaluated accurately. On the other hand, when the phase angle exceeds −2 °, the growth of cracks at the interface is unstable, and similarly, Gc cannot be evaluated accurately. Gc is also considered as a measure of the ease of adhesion between the triblock copolymer and polypropylene.

The melting peak temperature by DSC of the triblock copolymer as the component (B) is generally 50 to 105 ° C.
And is preferably 70 to 105 ° C. (B) Component DS
When the melting peak temperature by C is less than 50 ° C, the hot tack property is deteriorated, and when it exceeds 105 ° C, the low temperature heat seal property is poor.

The MFR of the triblock copolymer as the component (B) is generally 0.01 to 20 g / 10 minutes, and 1 to 10 g / 10 minutes is suitable for molding.

In the present invention, the triblock copolymer as the component (B) can be used alone or in combination of two or more.

In the present invention, the compounding ratio of the polypropylene as the component (A) and the triblock copolymer as the component (B) is generally such that the weight ratio is (A) component / (B) component 40 to 95/60. -5, preferably 50-90 / 50
-10, more preferably 60-80 / 40-20. 40% by weight of (A) component polypropylene
If it is less than 1, the hot tack property and heat resistance at high temperature are deteriorated, which is not preferable. On the other hand, if it exceeds 95% by weight, the adhesiveness to the substrate cannot be improved, which is not preferable.

Further, if desired, the composition of the present invention contains additives for general synthetic resins such as plasticizers, lubricants, various stabilizers, antiblocking agents, antistatic agents, dyes, pigments,
Various fillers may be added.

Specific examples of the plasticizer include dimethyl phthalate, diethyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, di-n-octyl phthalate, diisooctyl phthalate, butylbenzyl phthalate, and phosphoric acid. Trioctyl, tricresyl phosphate, dioctyl adipate, dioctyl sebacate, epoxidized soybean oil, dioctyl epoxyhexahydrophthalate, chlorinated paraffin and the like can be used.

As the lubricant, stearic acid, stearic acid amide, oleic acid amide, higher alcohol, liquid paraffin and the like are used.

As the stabilizer, BHT, 2,2'-methylenebis (4-methyl-6-t-butylphenol), 2
-Hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2,4-dihydroxybenzophenone, 2 (2'-hydroxy-5-
Methylphenyl) benzotriazole, substituted benzotriazole, 2-ethylhexyl-2-cyano-3,3-
Diphenyl acrylate, ethyl-2-cyano-3,3
-Diphenyl acrylate, phenyl salicylate, 4
-T-Butylphenyl salicylate or the like is used.

Examples of antiblocking agents include aluminum silicate, magnesium silicate, calcium carbonate, silicon dioxide, silica and the like.

As the antistatic agent, alkyl amine and its derivative, higher alcohol, glycerin ester of higher fatty acid, pyridine derivative, sulfated oil, soap, sulfate ester salt of olefin, alkyl sulfate ester, fatty acid ethyl sulfonate , Alkyl sulfonate,
Alkyl naphthalene sulfonate, alkyl benzene sulfonate, naphthalene sulfonate, succinate sulfonate, phosphate ester salt, partial fatty acid ester of polyhydric alcohol, ethylene oxide adduct of fatty alcohol, ethylene oxide addition of fatty acid And ethylene oxide adduct of fatty amino or fatty acid amide, ethylene oxide adduct of alkylphenol, ethylene oxide adduct of alkylnaphthol, ethylene oxide adduct of partial fatty acid ester of polyhydric alcohol, polyethylene glycol and the like.

As the filler, carbon black, white carbon, calcium carbonate, magnesium carbonate, silicate, talc, clay, sericite, mica, bentonite, calcium silicate, diatomaceous earth, silica sand, alumina hydrate, Barium sulfate, calcium sulfate and the like are used.

In order to obtain the composition of the present invention, a conventionally known mixing method, for example, a method of kneading using an open roll, a Banbury mixer, a kneader, an extruder or the like may be appropriately used. The kneading temperature is generally 17
It is 0 to 350 ° C, preferably 180 to 300 ° C.

In the present invention, other polymers can be blended within the range not impairing the object of the present invention.
Specific examples of such a polymer include branched low-density polyethylene, linear low-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ethylene- (meth) acrylic acid copolymer, ethylene- (meth). Examples include acrylic acid alkyl ester copolymers, ethylene-maleic anhydride copolymers, ethylene-maleic anhydride- (meth) acrylic acid alkyl ester terpolymers, and the like.

The polypropylene resin composition of the present invention is
A multilayer film or sheet can be formed by extrusion laminating on a substrate. Further, another synthetic resin film layer or the like may be further laminated on the polypropylene resin composition layer to form a multilayer laminate.

As the substrate, a polyolefin such as polypropylene or polyethylene, a synthetic resin film made of polyester, polyamide or the like, a metal foil such as aluminum, paper or the like is selected as necessary, but biaxially stretched polypropylene is particularly preferable. Film (OPP) and paper are preferred. The substrate may be subjected to pretreatment such as printing, anchor coating and corona treatment, if necessary.

The extrusion laminate mentioned here is to laminate a molten resin film extruded by using a T-die with a base material and cool and solidify it. To laminate the base material and the molten resin film, two rolls are pressed together. In this case, for the roll on the side that directly contacts the molten resin film, a cooled metal roll having a diameter of 300 mm to 1000 mm is used in order to rapidly cool and solidify the molten resin film. The other roll is typically a rubber roll to complete the crimp. In this way, a two-layer extruded laminated film is made, but another substrate is inserted on the metal roll side of the molten resin film,
It is also possible to make a three-layer extruded laminated film at once.

As such an extrusion laminating machine, an ordinary extrusion laminating machine for polyethylene or polypropylene can be used. The molding conditions at this time are generally a resin temperature of 260 to 300 ° C. and an air gap of 60 to 14
0 mm, cooling roll temperature 10 to 50 ° C., molding speed 50 to
It is 300 m / min.

[0033]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples.

The types of components (A) and (B) used in the examples and comparative examples are shown below. In addition, G of the component (B)
c is a value measured by the following method. The component (B) was press-molded to obtain a film having a thickness of about 10 μm. The film was sandwiched between sheets of standard polypropylene formed by pressing and having different thicknesses, and the temperature was 180 ° C. and the pressure was 3.5.
Fusion was performed under conditions of kg / cm ² and time of 10 minutes to form a planar interface. The interface was cracked with a razor blade with a thickness of 0.25 mm, and Gc was measured by the ADBC method (Closed).
Loop magazine, 1990, 23, page 3929). The phase angle was controlled by the thickness ratio of the polypropylene sheet and evaluated using the boundary element method. The measurement was performed at a phase angle of -7 °.

Component (A): A-1: Propylene homopolymer having MFR of 18 g / 10 min A-2: Ethylene-propylene random copolymer having MFR of 5 g / 10 min and ethylene content of 4% by weight. Combined (B) component: B-1: MFR 0.6 g / 10 minutes, density 0.88 g
/ Cm3, melting peak temperature in DSC is 99 ° C, G
Polyethylene-ethylene / 1-butene-polyethylene triblock copolymer in which c is 220 B-2: MFR is 1.5 g / 10 minutes and density is 0.88 g.
/ Cm ³ , the melting peak temperature in DSC is 102 ° C,
Polyethylene-ethylene / 1-butene-polyethylene triblock copolymer having Gc of 200 B-3: MFR of 1.2 g / 10 minutes and density of 0.88 g
/ Cm ³ , melting point temperature in DSC 60 ° C, G
polyethylene in which c is 50-ethylene / 1-butene-
Polyethylene triblock copolymer LDPE: Density 0.926 g / cm ³ , MFR 20
g / 10 min SHIO-REX M227 (Showa Denko KK)
Made)

The physical properties were measured as follows. (1) Adhesive Strength The laminated sample was peeled at the interface between the paper or biaxially oriented polypropylene film and the laminated film, and the adhesive strength was defined as the sample width of 15 mm, the peeling speed of 300 mm / min, and the peeling strength at 150 ° peeling. (2) Heat sealing strength Sealing pressure 2 kg / cm ² , sealing time 1 second, double-sided heating,
Heat sealing was performed at a seal temperature of 100 ° C. The heat seal strength was expressed in g / 15 mm width. (3) Hot tack property With a sealing pressure of 2 kg / cm ² , a sealing time of 1 second and a sealing width of 5 mm, heat sealing is performed at a temperature of 160 ° C., and the heat sealing bar is peeled off with a load of 46 g immediately after being separated from the film. The peeling distance at that time was expressed in mm. The shorter the peeling distance, the better. (4) Haze Measured according to JIS-K7105.

(Example 1) A-1 (70% by weight), B-
1 (30% by weight) was mixed with a Henschel mixer for 5 minutes, and then melt-kneaded at a temperature of 240 ° C. by an extruder with a vent to form pellets. 90 for each pellet obtained
Extrusion laminate molding was performed using a mmφ extrusion laminate molding machine. Extrusion laminating conditions are as follows: extruder 90 mmφ (50 rpm), T-die width 750 mm,
The air gap is set to 120 mm, a biaxially oriented polypropylene film is used as the base material, and the resin temperature is 280.
A sample was obtained by extrusion laminating at a molding temperature of 130 mm / min. Strong adhesion and heat seal strength, and good hot tack. The haze was also good in the 7% range.

(Examples 2 to 3) The compounding ratio of the component (B) was 1
Lamination was performed in the same manner as in Example 1 except that the amount was 5 or 50% by weight. Strong adhesion and heat seal strength, and good hot tack. The haze was also good in the 7% range.

(Example 4) B-2 was used as the component (B),
Lamination molding was performed in the same manner as in Example 1 except that the component (B) was 40%. Strong adhesion and heat seal strength, and good hot tack. The haze was also good in the 7% range.

(Embodiment 5) Fine paper as a base material (with a basis weight of 53 g)
/ M ² . ) Was used, and laminate molding was performed in the same manner as in Example 1 except that the resin temperature was 295 ° C. Strong adhesion and heat seal strength. Since the base material was paper, hot tackiness and haze could not be measured.

(Example 6) Extrusion laminate molding was carried out in the same manner as in Example 5 except that the blending ratio of the component (B) was 10% by weight and LDPE was added at 10% by weight. Strong adhesion and heat seal strength. Since the base material was paper, hot tackiness and haze could not be measured.

(Example 7) Extrusion laminate molding was performed in the same manner as in Example 1 except that A-2 was used as the component (A).
Strong adhesion and heat seal strength, and good hot tack. The haze was also good in the 4% range.

(Example 8) The components (A) were changed to A-2 and (B).
Extrusion lamination molding was performed in the same manner as in Example 1 except that the component was B-2 and the compounding ratio was 55:45. Strong adhesion and heat seal strength, and good hot tack. The haze was good in the 5% range.

(Comparative Example 1) Extrusion lamination was carried out in the same manner as in Example 1 except that the component (B) was not used and LDPE was blended instead. Adhesive strength is weak and heat seal strength is not obtained. The haze was also bad.

(Comparative Example 2) Extrusion lamination was carried out in the same manner as in Example 5 except that the component (B) was not used and LDPE was blended instead. Adhesive strength is weak and heat seal strength is not obtained.

(Comparative Example 3) A-2 was used as the component (A),
Extrusion lamination was performed in the same manner as in Example 1 except that the component (B) was blended in an amount of 2% by weight. The adhesive strength was weak and the heat seal strength was not obtained.

(Comparative Example 4) The mixing ratio of the component (B) was 70.
Extrusion lamination molding was performed in the same manner as in Example 1 except that the weight percentage was changed. The heat seal strength was low and the transparency (haze) was extremely poor.

(Comparative Example 5) The mixing ratio of the component (A) was 100.
Extrusion lamination molding was carried out in the same manner as in Example 1 except that the blending ratio of the component (B) was 0% by weight, but the laminating film was not stable and molding was impossible.

(Comparative Example 6) The blending ratio of the component (A) was 70% by weight, B-3 was used as the component (B), and the blending ratio was 30.
Extrusion lamination molding was performed in the same manner as in Example 1 except that the weight percentage was changed. Adhesive strength is weak and heat seal strength is not obtained.

[0050]

[Table 1]

[0051]

According to the present invention, it is possible to improve the adhesiveness to a substrate, especially a biaxially stretched polypropylene film, the low temperature heat sealability and the hot tackiness while maintaining the advantages of polypropylene (particularly transparency). It is suitable for packaging materials and processed papers.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junichiro Washiyama 3-2 Chidori-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Akira Kawasaki Resin Research Laboratory, Waseda Electric Co., Ltd. (72) Hiroshi Takenouchi Chidori-cho, Kawasaki-shi, Kanagawa No. 3 No. 2 Showa Electric Co., Ltd. Kawasaki Resin Research Laboratory

Claims (2)

[Claims] 1. (A) polypropylene 95-40% by weight
And (B) the critical strain energy release rate is 100 J / m ²
A polypropylene resin composition comprising the above-mentioned polyethylene-ethylene / butene-polyethylene triblock copolymer in an amount of 5 to 60% by weight. 2. A laminate comprising a layer comprising the polypropylene resin composition according to claim 1 and a substrate.