JP2010173326A - Hot-melt propylene-based polymer laminated film and use thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hot-melt propylene-based polymer laminated film which is excellent in low-temperature heat-sealing property, sealing property and laminate strength at a high speed under a low pressure, and has shock-resistance, slipping property, transparency, brilliance property, etc. suited for antiblocking packaging material. <P>SOLUTION: The hot-melt propylene-based polymer laminated film is made by laminating a lamination layer obtained from a propylene-α-olefin copolymer (A) via an intermediate layer obtained from a linear low-density polyethylene (B) on one surface of a hot-melt layer obtained from the propylene-α-olefin copolymer (A) in which the peak temperature (Tp) determined from a crystal melting curve based on DSC is 110 to 140°C, and a difference (Te-Ts) between melting starting temperature (Ts) and melting ending temperature (Te) is less than 45°C. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is a heat-sealable propylene-based polymer having excellent high-temperature, low-temperature heat-sealability at low pressures, sealing properties, and laminate strength, and has anti-blocking properties, slip properties suitable for packaging materials, transparency, impact strength, and the like. The present invention relates to a combined laminated film and its use.

Films obtained from propylene random copolymers are heat-seal strength, transparency, waist strength, blocking resistance compared to films obtained from ethylene polymers such as low-density polyethylene and linear low-density polyethylene. Excellent hot tack, scratch resistance, heat resistance, etc., so it is widely used as a packaging material for foods such as confectionery, bread, vegetables, noodles, and daily goods such as clothing such as shirts and pants. Has been. And since a film made of such a propylene-based random copolymer is inferior in low-temperature heat-sealability as compared with a film made of an ethylene-based polymer such as low-density polyethylene and linear low-density polyethylene, its improvement is always required. Yes. Examples of the method for improving the low temperature heat sealability include a composition of a crystalline propylene random copolymer and a 1-butene random copolymer (Patent Document 1), and a propylene-polymer obtained by a polymerization method using a metallocene catalyst. Various α-olefin random copolymers (for example, Patent Document 2) have been proposed. However, none of the films has a good balance of low-temperature heat sealability and rigidity, sealing properties, laminate strength, blocking resistance, and the like.

JP-A-61-106648 (Claims) JP 2002-20430 A (Claims)

  Therefore, the present invention is a heat-fusible propylene having excellent high-temperature, low-temperature heat-sealability under low pressure, sealing properties, and laminate strength, and having anti-blocking properties, slip properties suitable for packaging materials, transparency, impact resistance strength, and the like. Various studies were conducted for the purpose of obtaining a polymer-based multilayer film.

  That is, in the present invention, the peak temperature (Tp) determined from the DSC-based crystal melting curve is 110 to 140 ° C., and the difference (Te−Ts) between the melting start temperature (Ts) and the melting end temperature (Te) is 45 ° C. Propylene / α-olefin copolymer (A) on one side of the heat-sealing layer obtained from the propylene / α-olefin copolymer (A) via an intermediate layer obtained from linear low density polyethylene (B) ( The present invention relates to a heat-fusible propylene-based polymer laminated film, which is obtained by laminating a laminate layer obtained from A), and its use.

The heat-fusible propylene-based polymer laminated film of the present invention is a heat-fusible propylene having low-temperature heat sealability, blocking resistance, impact resistance suitable for packaging materials, slip properties, flexibility, transparency, etc. As a polymer-based polymer laminated film, it can be suitably used as a packaging film, especially as a packaging film for breads such as bread and confectionery bread, fresh foods such as fruits and vegetables, textiles, clothing, stationery and mail order magazines. .
The heat-fusible propylene-based polymer laminated film of the present invention further has excellent impact resistance, anti-blocking properties, slip properties suitable for packaging materials, transparency, etc., and a heat-sealed portion. A package with a beautiful appearance can be obtained. Taking advantage of these features, other than the above, sweets such as rice cakes, rice crackers, chocolate confectionery, chocolate confectionery, luxury goods such as delicacy, ham It is also suitable for packaging materials (standard bags, for automatic packaging) such as sausages, meat storage products such as livestock meat, socks, daily goods such as cosmetics.

Propylene / α-olefin random copolymer (A)
The propylene / α-olefin copolymer (A) according to the present invention has a peak temperature (Tp) determined from a crystal melting curve based on DSC of 110 to 140 ° C., preferably 115 to 130 ° C., and a melting start temperature (Ts). ) And the melting end temperature (Te) (Te−Ts) is less than 45 ° C., preferably in the range of 30-40 ° C., preferably the difference between the melting start temperature (Ts) and the peak temperature (Tp) ( Tp−Ts) is less than 35 ° C., more preferably in the range of 25 to 34 ° C. The α-olefin content of the propylene / α-olefin copolymer (A) is not particularly limited as long as it has the above-mentioned heat melting characteristics, but usually the α-olefin content is 1.0 to 20% by weight, more Preferably it exists in the range of 1.5 to 15 weight%. Examples of the α-olefin include ethylene, 1-butene, 1-hexene, 4-methyl / 1-pentene, 1-octene and the like. In these, the random copolymer with ethylene and / or 1-butene is preferable. The MFR (melt flow rate; ASTM D-1238 load 2160 g, temperature 230 ° C.) is not particularly limited as long as it can be made into a film, but is usually 0.5 to 20 g / 10 minutes, preferably 2 to 10 g / 10. In the range of minutes. The propylene / α-olefin copolymer (A) according to the present invention usually has a molecular weight distribution (expressed by a ratio of the weight average molecular weight Mw and the number average molecular weight Mn) in the range of 2 to 3.
The propylene / α-olefin copolymer (A) according to the present invention is a raw material for the heat-fusible layer of the heat-fusible propylene-based polymer laminated film and a raw material for the laminate layer.
The peak temperature (Tp), melting start temperature (Ts) and melting end temperature (Te) of the propylene / α-olefin copolymer (A) according to the present invention were measured by the following methods. About 5 mg of propylene / α-olefin copolymer (A) is weighed, and using a differential scanning calorimeter (type DSC220 module) manufactured by Seiko Denshi Kogyo Co., Ltd., the heating rate is 200 ° C./min. When the temperature was raised to 0 ° C. and held at 200 ° C. for 5 minutes, the temperature was lowered to 0 ° C. at a rate of temperature decrease of 100 ° C./min, and again raised to 0 to 200 ° C. at a rate of temperature increase of 10 ° C./min From this melting curve, the peak temperature (Tp), the melting start temperature (Ts), and the melting end temperature (Te) were determined from the melting curve according to the method of ASTM D3419. In the present invention, (Tpm1) described in ASTM D3419 is (Tp), (Tim) is (Ts), and (Tefm) is (Te).

Linear low density polyethylene (B)
The linear low density polyethylene (B) according to the present invention usually has a density of 0.900 to 0.940 g / cm ³ , preferably 0.905 to 0.935 g / cm ³ , MFR (ASTM D1238 load 2160 g, Ethylene and propylene, butene-1, heptene-1, hexene-1, octene-1, 4-methyl-pentene-1 at a temperature of 190 DEG C. for 0.5-20 g / 10 min, preferably 1-10 g / 10 min. Or the like, and a random copolymer with an α-olefin having 3 to 10 carbon atoms, preferably an α-olefin having 6 or more carbon atoms. In addition, the linear low density polyethylene (B) has a molecular weight distribution (weight average molecular weight: Mw, number average molecular weight: Mn, ratio: Mw / Mn) is usually 1.5 to 4.0, Preferably it exists in the range of 1.8-3.5. This Mw / Mn can be measured by gel permeation chromatography (GPC).
The linear low-density polyethylene (B) has one or more sharp peaks obtained from an endothermic curve measured at a heating rate of 10 ° C./min with a differential scanning calorimeter (DSC). The temperature, that is, the melting point is usually in the range of 70 to 130 ° C, preferably 80 to 120 ° C. The linear low density polyethylene (B) according to the present invention is a raw material for the intermediate layer of the heat-fusible propylene polymer laminated film.

The linear low density polyethylene (B) as described above can be prepared by a conventionally known production method using a Ziegler catalyst, a single site catalyst or the like. For example, the linear low density polyethylene (B) can be prepared using a catalyst containing a metallocene compound of a transition metal. The catalyst containing the metallocene compound is preferably formed from (a) a transition metal metallocene compound, (b) an organoaluminum oxy compound, and (c) a carrier, and if necessary, these components and (D) It may be formed from an organoaluminum compound and / or an organoboron compound.
An olefin polymerization catalyst containing such a metallocene compound and a method for adjusting linear low density polyethylene (B) using the catalyst are described in, for example, JP-A-8-269270.

The propylene / α-olefin copolymer (A) and linear low-density polyethylene (B) according to the present invention are usually used as antioxidants, weathering stabilizers, and antistatics, as long as the object of the present invention is not impaired. Additives such as an agent, an antifogging agent, an antiblocking agent, a lubricant, a nucleating agent, and a pigment, or other polymers can be blended as necessary.
Among them, the propylene / α-olefin copolymer (A) constituting the heat-sealing layer of the heat-fusible propylene-based polymer laminated film is obtained by firing silica, talc, mica, zeolite, and further metal alkoxide. 0.01 to 1% by weight of various known anti-blocking agents such as inorganic compound particles such as metal oxides, organic compound particles such as polymethyl methacrylate, melamine formalin resin, melamine urea resin, and polyester resin. Further, it is preferable because a film having further improved blocking resistance can be obtained. Among these, silica and polymethyl methacrylate are particularly preferable in terms of blocking resistance and transparency.

The propylene / α-olefin copolymer (A) constituting the heat-sealing layer of the heat-fusible propylene-based polymer laminated film includes hydrocarbon-based, fatty acid-based, higher alcohol-based, aliphatic amide. It is preferable to add 0.01 to 1% by weight of various known lubricants such as a system, a metal soap system, and an ester system because a film with improved slip properties can be obtained. Of these, the combination of immediate action erucic acid amide and slow-acting bisoleic acid amide or behenic acid amide can be used immediately after film formation and at the time of subsequent cutting, as well as printing, lamination and bag making. Etc. can be improved in a balanced manner.
Further, the propylene / α-olefin copolymer (A) constituting the heat-fusible layer of the heat-fusible propylene-based polymer laminated film includes high-density polyethylene, dibenzylidene sorbitol, chloro-substituted dibenzylidene sorbi. Various known nucleating agents (crystallization nucleating agents) such as tolu, methyl-substituted dibenzylidene sorbitol, hydroxy-di-aluminum, bissorbicyl, bissodium methylene bisacid phosphate sodium salt, etc. Addition of 0.01 to 1.0% by weight is preferable because it can suppress the occurrence of a roll mark during film formation and can provide a film with improved slip and blocking properties immediately after. Among these, the use of a polyethylene crystallization nucleating agent that is relatively easy to add and has no problem with odor can improve the quality and processability immediately after film formation in a well-balanced manner.
When 0.01 to 1% by weight of various known anti-blocking agents are added to the propylene / α-olefin copolymer (A) constituting the laminate layer of the heat-fusible propylene polymer laminated film, A film with improved blocking resistance is obtained, which is preferable. Also, it is preferable to add 0.01 to 1% by weight of various known lubricants because a film with improved slip properties can be obtained.

Production method of propylene / α-olefin copolymer (A) The propylene / α-olefin copolymer (A) according to the present invention is prepared by various known methods, for example, typically a solid titanium catalyst component and an organometallic compound. It can be produced using a catalyst formed from a catalyst component, or a catalyst formed from both of these components and an electron donor.

As a solid titanium catalyst component, titanium trichloride or a titanium trichloride composition produced by various methods, or magnesium, halogen, an electron donor, preferably an aromatic carboxylic acid ester or an alkyl group-containing ether and titanium are essential components. And a supported titanium catalyst component having a specific surface area of preferably 100 m ² / g or more. In particular, a polymer produced using the latter supported catalyst component is preferred. The organometallic compound catalyst component is preferably an organoaluminum compound, and specific examples include trialkylaluminum, dialkylaluminum halide, alkylaluminum sesquihalide, alkylaluminum dihalide, and the like. Among these compounds, a suitable organometallic compound catalyst component varies depending on the type of the titanium catalyst component used.
The electron donor is an organic compound containing nitrogen, phosphorus, sulfur, oxygen, silicon, boron, and the like. Suitable specific examples include organic esters and organic ethers having these elements.
With respect to the method for producing a polymer using a catalyst component with a carrier, for example, JP-A-50-108385, JP-A-50-126590, JP-A-51-20297, JP-A-51-28189, JP It is disclosed in each publication such as Sho 52-151691.

The propylene / α-olefin copolymer (A) according to the present invention can be produced particularly using a single site catalyst. The single site catalyst is a catalyst having a uniform active site (single site), and examples thereof include a metallocene catalyst (so-called Kaminsky catalyst) and a Brookhart catalyst. For example, a metallocene catalyst is a catalyst comprising a metallocene transition metal compound, at least one compound selected from the group consisting of an organoaluminum compound and a compound that forms an ion pair by reacting with the metallocene transition metal compound, and an inorganic substance. It may be carried on.
Examples of the metallocene transition metal compound include JP-A-5-209014, JP-A-6-1005209, JP-A-1-301704, JP-A-3-193966, JP-A-5-148284, and JP-A-2000-20431. And the like, and the like.

Examples of the organoaluminum compound include alkylaluminum, chain or cyclic aluminoxane, and the like. The chain or cyclic aluminoxane is produced by bringing alkylaluminum into contact with water. For example, it can be obtained by adding alkylaluminum at the time of polymerization and adding water later, or by reacting crystallization water of a complex salt or adsorbed water of an organic or inorganic compound with alkylaluminum.
Examples of the compound that reacts with the metallocene transition metal compound to form an ion pair include compounds described in JP-A-1-501950, JP-A-3-207704, JP-A-2002-20431, and the like. . Examples of the inorganic substance that supports the single-site catalyst include silica gel, zeolite, diatomaceous earth, and the like. Examples of the polymerization method include bulk polymerization, solution polymerization, suspension polymerization, gas phase polymerization and the like. These polymerizations may be batch processes or continuous processes. The polymerization conditions are usually a polymerization temperature: −100 to + 250 ° C., a polymerization time: 5 minutes to 10 hours, a reaction pressure; a normal pressure to 300 Kg / cm ² (gauge pressure).

Heat-fusible propylene-based polymer laminated film The heat-fusible propylene-based polymer laminated film of the present invention comprises a heat-fusible layer obtained from a propylene / α-olefin copolymer (A), a linear low-density polyethylene ( It consists of an intermediate layer obtained from B) and a laminate layer obtained from the propylene / α-olefin copolymer (A). Such an intermediate layer may be a single layer or a multilayer of two or more layers. The thickness of the heat-fusible propylene polymer laminated film is variously determined depending on the application, but in the case of a three-layer structure, the thickness of the heat-sealing layer is usually 1 to 80 μm, preferably 2 to 50 μm, and the intermediate layer Is 8 to 498 μm, preferably 16 to 96 μm, the thickness of the laminate layer is 1 to 80 μm, preferably 2 to 50 μm, and the total thickness of the laminated film is 10 to 500 μm, preferably 20 to It is in the range of 100 μm. The heat-fusible propylene polymer laminated film of the present invention has an intermediate layer obtained from a linear low-density polyethylene (B), so that the heat-fusible propylene polymer laminated film has heat resistance and blocking resistance. The strength of the linear low-density polyethylene, such as impact resistance, drop bag breaking strength, puncture strength, and low-temperature impact strength, and vinylon-like flexibility are maintained without degrading performance such as stability, lubricity, and gloss. Can be granted.
The propylene / α-olefin copolymer (A) used for the laminate layer is a resin in the same category as the propylene / α-olefin copolymer (A) used for the heat seal layer. It may be the same as or different from the propylene / α-olefin copolymer (A) used.
The heat-fusible propylene-based polymer laminated film of the present invention can be applied to the surface of the laminate layer, for example, corona treatment, flame treatment, plasma, in order to improve printability, adhesion to other films, slipperiness, etc. Surface activation treatment may be performed by treatment, undercoat treatment or the like.
In addition, depending on the application, a base material layer described later can be bonded to the laminate layer of the heat-fusible propylene polymer laminated film, and used for various applications.

  The heat-fusible propylene-based polymer laminated film of the present invention can employ various known film forming methods. At that time, for forming a film, the propylene / α-olefin copolymer (A) having the above composition constituting the heat-sealing layer and the laminating layer and the linear low-density polyethylene (B) of the intermediate layer are provided. Quantitatively weigh it directly into the film forming machine. Such laminated films may be individually laminated after being molded, but a method by coextrusion molding using a multilayer die having a three-layer structure is most preferable.

Base material layer The base material layer according to the present invention is made of a sheet or film of thermoplastic resin, paper, aluminum foil or the like. As the thermoplastic resin, various known thermoplastic resins such as polyolefin (polyethylene, polypropylene, poly-4-methyl / 1-pentene, polybutene, etc.), polyester (polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc.), polyamide (Nylon-6, nylon-66, polymetaxylene adipamide, etc.), polyvinyl chloride, polyimide, ethylene / vinyl acetate copolymer or saponified product thereof, polyvinyl alcohol, polyacrylonitrile, polycarbonate, polystyrene, ionomer, or these And the like. Of these, thermoplastic resins having good stretchability and transparency, such as polypropylene, polyethylene terephthalate, and polyamide, are preferable. Further, the substrate made of such a thermoplastic resin film may be an unstretched film or a stretched film, and a laminate of one or more coextruded products, extruded laminate products, dry laminate products, etc. It may be the body.
Further, in order to improve the adhesion of one or both sides of the base material layer to the laminate layer of the heat-fusible propylene polymer laminated film of the present invention, for example, corona treatment, flame treatment, plasma treatment, undercoat Surface activation treatment such as treatment, primer coating treatment, and frame treatment may be performed. The thickness of the base material layer is usually 5 to 1000 μm, preferably 9 to 100 μm.

  EXAMPLES Next, although this invention is demonstrated through an Example, this invention is not limited by these Examples.

Various test methods and evaluation methods in the present invention are as follows.
(1) Heat seal strength (N / 15mm)
Before measuring the heat seal strength, the three-layer coextrusion laminated film was aged in a 38 ° C. oven for 15 hours and then allowed to cool. Three-layer co-extrusion laminated film is laminated with the heat-sealing layer surface, and at a predetermined temperature, with a seal bar having a width of 5 mm, at a pressure of 0.2 MPa for 1 second, perpendicular to the flow direction of the three-layer co-extrusion laminated film After heat sealing, it was allowed to cool. From this, a test piece having a width of 15 mm was cut, and the heat seal part was peeled off at a crosshead speed of 500 mm / min, and the strength was defined as the heat seal strength.
(2) Blocking property Before measuring the blocking property, the three-layer coextrusion laminated film was aged in a 38 ° C. oven for 15 hours and then allowed to cool. Cut out a strip-shaped test piece of length: 20 mm x width: 100 mm from a three-layer coextrusion laminated film, and make five pieces each with the heat-fusible surface overlapped, in the cross direction near the center of the test piece Use a commercially available preparation at a right angle. A load of 4 kg is applied to the 5.2 cm ² area where the test piece and the preparation overlap, and after aging for 2 days under a predetermined temperature condition, it is allowed to cool. Thereafter, the heat-sealing layer surfaces were overlapped and subjected to shear peeling at a crosshead speed of 300 mm / min, and the maximum strength was defined as a blocking force. The blocking force was evaluated at n = 5, and the average value was defined as the blocking force (N / 5.2 cm ² ).
(3) Impact impact strength (J)
Before measuring impact impact strength, the three-layer coextruded laminated film was aged in a 38 ° C. oven for 15 hours and then allowed to cool. A strip-shaped test piece of length: 3 m × width: 10 cm is cut out from the three-layer coextrusion laminated film, and an impact ball of 1 inch is used, using a plastic film and sheet impact strength tester manufactured by Toyo Seiki Co., Ltd. The impact strength was measured at n = 20 under the condition of full scale 1.47J, and the average value was taken as the impact impact strength.

The polymers used in Examples and Comparative Examples are as follows.
(1) Propylene / ethylene random copolymer (1) (PER-1)
Ethylene content: 3.1 wt%, Ts: 94.0 ° C, Tp: 126.6 ° C, Te: 131.4 ° C, Te-Ts: 37.4 ° C, Tp-Ts: 32.6 ° C, Mw / Mn: 2.7 and MFR: 7 g / 10 min.
(2) Propylene / ethylene random copolymer (2) (PER-2)
Ethylene content: 2.8 wt%, Ts: 97.2 ° C, Tp: 125.6 ° C, Te: 134.2 ° C, Te-Ts: 37.0 ° C, Tp-Ts: 28.4 ° C, Mw / Mn: 1.9 and MFR: 7 g / 10 min.
(3) Propylene / ethylene random copolymer (3) (PER-3)
Ethylene content: 3.5 wt%, Ts: 89.2 ° C, Tp: 120.4 ° C, Te: 126.3 ° C, Te-Ts: 37.1 ° C, Tp-Ts: 31.2 ° C, Mw / Mn: 2.2 and MFR: 7 g / 10 min.
(4) Propylene / ethylene / 1-butene random copolymer (PEBR)
Ethylene content: 2.2 wt%, 1-butene content: 2.0 wt%, Ts: 95.4 ° C, Tp: 139.3 ° C, Te: 150.3 ° C, Te-Ts: 54.9 C, Tp-Ts: 43.9 ° C, Mw / Mn: 3.9 and MFR: 7 g / 10 min.
(5) Linear low density polyethylene (LL)
Density: 0.909 g / cm ³ , MFR: 3.6 g / 10 min, melting point: 116 ° C.

Example 1
PER-1 is prepared as a thermal fusion layer, LL as an intermediate layer, and PER-1 as a laminate layer, which are supplied to a separate extruder. The thermal fusion layer / intermediate layer / A three-layer coextrusion laminated film consisting of a laminate layer was obtained. The total thickness of the film was 50 μm, and the thickness of each layer was heat-fusion layer: intermediate layer: laminate layer = 12.5 μm: 25.0 μm: 12.5 μm.
The physical properties of the obtained three-layer coextrusion laminated film were evaluated by the method described above. The results are shown in Table 1.

Example 2
A three-layer coextrusion laminated film was obtained in the same manner as in Example 1 except that PER-2 was used instead of PER-1 used for the heat-sealing layer and the laminate layer of Example 1.
Table 1 shows evaluation results such as physical properties of the obtained three-layer coextrusion laminated film.

Example 3
A three-layer coextrusion laminated film was obtained in the same manner as in Example 1 except that PER-3 was used instead of PER-1 used for the heat-sealing layer and the laminate layer of Example 1.
Table 1 shows evaluation results such as physical properties of the obtained three-layer coextrusion laminated film.

Comparative Example 1
A three-layer coextrusion laminated film was obtained in the same manner as in Example 1 except that PEBR was used instead of PER-1 used for the heat-sealing layer and the laminate layer of Example 1.
Table 1 shows evaluation results such as physical properties of the obtained three-layer coextrusion laminated film.

Comparative Example 2
A three-layer coextrusion laminated film was obtained in the same manner as in Example 1 except that PER-1 was used instead of LL in the intermediate layer of Example 1.
Table 1 shows evaluation results such as physical properties of the obtained three-layer coextrusion laminated film.

  As is apparent from Table 1, a heat-fusible propylene-based polymer laminate having a specific propylene / α-olefin copolymer in the heat-fusible layer and the laminate layer and a linear low-density polyethylene layer in the intermediate layer The films (Example 1, Example 2 and Example 3) are excellent in low-temperature heat seal properties as compared with a laminated film (Comparative Example 1) using a conventional propylene / α-olefin copolymer. Nevertheless, it can be seen that the blocking resistance is excellent.

Claims (3)

  The peak temperature (Tp) obtained from the crystal melting curve based on DSC is 110 to 140 ° C., and the difference (Te−Ts) between the melting start temperature (Ts) and the melting end temperature (Te) is less than 45 ° C. -Obtained from the propylene / α-olefin copolymer (A) via an intermediate layer obtained from the linear low density polyethylene (B) on one side of the heat-sealed layer obtained from the olefin copolymer (A) A heat-fusible propylene-based polymer laminated film, wherein a laminate layer is laminated.   A heat-fusible propylene-based polymer laminated film according to claim 1, wherein the heat-fusible propylene-based polymer laminated film is for packaging.   A heat-fusible propylene-based polymer laminated film according to claim 2, wherein the heat-fusible propylene-based polymer laminated film is for packaging fibers.