JP2007224280A - Propylene-based resin unstretched film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a propylene-based resin unstretched film which is excellent in impact resistance, transparency, stiffness, blocking resistance, slip characteristics and low-temperature heat-sealing characteristics. <P>SOLUTION: This propylene-based resin unstretched film is obtained by processing, into a film, a propylene-based resin composition obtained by blending not more than 1.0 pt.wt. of an anti-blocking agent and not more than 1.0 pt.wt. of a higher fatty acid amide with 100 pts.wt. of a propylene-α-olefin random copolymer whose main component is propylene having predetermined values as following seven physical properties: (1) melt flow rate, (2) memory effect, (3) melting peak temperature, (4) the difference of a melting completion temperature and the melting peak temperature, (5) α-olefin content in the propylene-α-olefin random copolymer, (6) the amount of the extract at each temperature in the temperature rising elution fractionation measurement, and (7) Olsen flexural modulus. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a propylene-based resin film. More specifically, the present invention relates to an unstretched propylene-based resin film excellent in impact resistance and excellent in transparency, rigidity, blocking resistance, slipperiness, and heat sealability.

  Conventionally, polypropylene film has been widely used as a film for food packaging because it has various excellent properties such as transparency and rigidity, but on the other hand, it has poor impact resistance and heat sealability, In particular, applications are limited due to low low temperature impact.

  For the purpose of improving such drawbacks, it is known that a non-crystalline or partially crystalline ethylene / α-olefin copolymer is blended with a polypropylene resin, but the blend of these copolymers is satisfactory. In order to obtain the impact resistance to be obtained, a large amount of blending of several percent or more is necessary. By blending such a large amount of copolymer, the film becomes weak, and the blocking resistance and slippage are reduced. The film resistance is significantly reduced, and the frictional resistance during film processing hinders the speeding up of the film processing, the film is scratched, the opening of the resulting film bag is extremely lowered, and the packaging film There was a drawback that a suitable product could not be obtained.

  In addition, for the purpose of improving the impact resistance of crystalline polypropylene resin, a method of randomly copolymerizing ethylene as a copolymer component with propylene as a main component has been carried out, but as the copolymerization ratio of ethylene increases. Ethylene is easy to block copolymerize with propylene, and when such a copolymer is used, the transparency of the film is remarkably lowered, and a satisfactory packaging resin film cannot be obtained.

  In view of the above-mentioned problems of the prior art, the present inventors provide an unstretched propylene-based resin film excellent in impact resistance, transparency, rigidity, blocking resistance, slipperiness, and excellent in low-temperature heat sealability. It is in.

  As a result of intensive studies to solve such problems, the present invention has found that the above-mentioned problems can be solved by a specific propylene-based resin film, and has completed the present invention.

That is, the unstretched propylene-based resin film of the present invention is a propylene-based resin composition composed of a propylene / α-olefin random copolymer mainly composed of propylene that satisfies the following physical properties (1) to (7). It is characterized by being melt extruded and processed into a film.
Physical property (1): Melt flow rate (MFR) is 0.5 to 50.0 g / 10 minutes,
Physical property (2): Memory effect (ME) is 0.9 to 1.4,
Physical property (3): The temperature [TP] of the main melting peak determined with a differential scanning calorimeter (DSC) is 100 to 150 ° C.,
Physical property (4): Melting end temperature [TE] (° C.) determined by a differential scanning calorimeter (DSC) is [TE] − [TP] ≦ 8,
Physical property (5): Random copolymer in which an α-olefin component having 2 or 4 to 20 carbon atoms and propylene are combined, and at least one α-olefin component and the content of the α-olefin component [E] (Mol%) is within the range represented by the following formula [I] and formula [II],
(140− [TP]) / 10.2 ≦ [E] ≦ (160− [TP]) / 2.6
Formula [I]
0 <[E] ≦ 23 Formula [II]
Physical property (6): Extraction amount extracted at 40 ° C. or less is 2.0% by weight or less and extraction amount extracted at 50 ° C. or less is 5.0% in the measurement by temperature rising elution fractionation (TREF) using orthodichlorobenzene as a solvent. The extraction amount extracted at 60% or less, and 20.0% by weight or less,
Physical property (7): Olsen bending elastic modulus [M] (MPa) is in a range represented by formula [III],
16.5 × [TP] −1, 530 ≦ [M] ≦ 16.5 × [TP] −1,300
Formula [III]

  The unstretched propylene-based resin film obtained by the method of the present invention is excellent in impact resistance, transparency, rigidity, blocking resistance, slipperiness, and excellent low-temperature heat-sealability due to a specific propylene-based resin. It has practical value.

[I] Propylene resin composition
(1) Component
(a) Propylene-based polymer The propylene-based polymer constituting the propylene-based resin composition used in the unstretched propylene-based resin film of the present invention is mainly propylene satisfying the following physical properties (1) to (7). It is a propylene / α-olefin random copolymer as a component.
The propylene / α-olefin random copolymer containing propylene as a main component is composed of propylene as a main component and α-olefin having 2 or 4 to 20 carbon atoms, preferably 4 to 10 carbon atoms, or ethylene and carbon. Random copolymerization with an α-olefin of several 4 to 20, preferably 4 to 10, and satisfies the following physical properties (1) to (7).

Objects of physical properties (1): Melt flow rate (MFR: Melt Flow Rate) is 0.5~50.0g / 10 min, preferably in the range of 1.0~20.0g / 10 min.
When the melt flow rate is lower than the lower limit of the above range, the extrudability of the film becomes poor. When the melt flow rate is higher than the upper limit, the impact strength of the film is remarkably reduced.

Physical property (2): Memory effect (ME) is in the range of 0.9 to 1.4.
When the memory effect is lower than the lower limit of the above range, the extrusion moldability is poor, and when higher than the upper limit, the transparency of the film is lowered.

Physical property (3): The melting peak temperature [TP] determined by a differential scanning calorimeter (DSC) is 100 to 150 ° C, preferably 110 to 140 ° C.
When the main melting peak temperature obtained by the differential scanning calorimeter is lower than the lower limit of the above range, the blocking resistance is poor and the rigidity is lowered. Moreover, when higher than the upper limit of the said range, impact resistance will fall.

Physical property (4): The melting end temperature [TE] (° C.) determined by a differential scanning calorimeter is in the range of [TE] − [TP] ≦ 8.
When the above [TE]-[TP] exceeds 8 ° C., the temperature at which complete heat sealing is obtained increases.

Physical property (5): The content [E] (mol%) of the α-olefin component used as a comonomer is within the range represented by the following formula [I].
Propylene · α− that finds the effects of the present invention, such as a poor balance between rigidity and impact resistance, except that the melting peak temperature [TP] determined by the differential scanning calorimeter is outside the range represented by the following formula [I]. Production of an olefin random copolymer is difficult.
(140− [TP]) / 10.2 ≦ [E] ≦ (160− [TP]) / 2.6
Formula [I]
Further, the content [E] (mol%) of the α-olefin component is within the range represented by the following formula [II].
0 <[E] ≦ 23, preferably 0 <[E] ≦ 18, particularly preferably 0 <[E] ≦ 10 Formula [II]
When higher than the upper limit of the said range, blocking resistance is bad and rigidity falls.

Physical property (6): Extraction amount extracted at 40 ° C. or less is 2.0% by weight or less, preferably 1.0% by weight as measured by temperature rising elution fractionation (TREF) using orthodichlorobenzene as a solvent. The extraction amount extracted at 50 ° C. or less is 5.0% by weight or less, preferably 4.0% by weight or less, and the extraction amount extracted at 60 ° C. or less is 20.0% by weight or less, preferably 10%. 0.0% by weight or less.
When orthodichlorobenzene is used as a solvent and any of the extraction amounts extracted at each temperature is larger than the above range, blocking resistance and slipping property are lowered.
The extraction with orthodichlorobenzene can be measured by temperature rising elution fractionation (TREF) using orthodichlorobenzene as a solvent.
In addition, the measurement of temperature rising elution fractionation (TREF) can be performed with the apparatus and method as described in Journal of Applied Polymer Science Vol. 26, 4217-4231 (1981).

Physical property (7): Olsen bending elastic modulus [M] (MPa) is in a range represented by formula [III],
16.5 × [TP] −1530 ≦ [M] ≦ 16.5 × [TP] −1300
Formula [III]
Outside the range represented by the above formula [III], it is difficult to produce a propylene-based polymer that finds the effects of the present invention.

Specific examples of the propylene · alpha-olefin random copolymer composed mainly of types such as propylene, for example, propylene as a main component of propylene and other 1-alkene (ethylene, 1-butene, 1-pentene, A binary copolymer with 1-hexene, 4-methylpentene-1, etc.), or propylene and ethylene and other 1-alkenes (1-butene, 1-pentene, 1-hexene) mainly composed of propylene, And terpolymers with 4-methylpentene-1 etc.).

The production method for the propylene-based polymer used in manufacturing the present invention is not particularly limited, as a catalyst system used, mention may be made of so-called Ziegler-Natta catalysts. Specifically, a transition metal compound (for example, a titanium-containing compound) as a main catalyst, or a carrier-supported catalyst obtained by loading a transition metal compound on a support (for example, a magnesium-containing compound or a processed product thereof) Examples of the catalyst include those obtained by using an organometallic compound (for example, an organoaluminum compound).

  In addition, a homogeneous catalyst may be used, and examples include a conventionally known catalyst composed of a vanadium compound and an organoaluminum compound, or a new homogeneous catalyst such as a Kaminsky catalyst or a metallocene catalyst found recently. Can do.

The polymerization mode can be any mode as long as the catalyst component and each monomer are in efficient contact. Specifically, the slurry method using an inert solvent, the bulk method using propylene as a solvent substantially without using an inert solvent, the solution polymerization method, or the monomers are substantially gaseous without using a liquid solvent substantially. For example, a gas phase method can be used. It is also applied to continuous polymerization and batch polymerization. In the case of slurry polymerization, a saturated aliphatic or aromatic hydrocarbon such as hexane, heptane, pentane, cyclohexane, benzene and toluene is used alone or as a mixture as a polymerization solvent.

[II] Preparation of Composition The propylene-based resin composition can be prepared by blending a propylene-based polymer with various additive components as necessary and kneading with an extruder.

  There are no particular restrictions on the extruder, and examples thereof include screw extruders such as single-screw extruders and multi-screw extruders, elastic extruders, hydrodynamic extruders, ram-type continuous extruders, roll-type extruders, and gear-type extruders. Non-screw extruders such as a machine can be mentioned, and among these, it is preferable to use a screw extruder.

Additives and the like The propylene-based resin composition can contain known additives such as antioxidants, weathering agents, lubricants, antiblocking agents, antistatic agents, antifogging agents, pigments, and fillers. Elastomers can also be blended.

[III] Production of propylene-based resin film The propylene-based resin film of the present invention can be produced using the above-mentioned propylene-based resin composition as a raw material resin. Specifically, a sheet, a film (unstretched film, stretched) Film) can be produced by a known technique such as a casting method or an inflation method.

  As a casting method for producing extruded products such as sheets and films (unstretched films), a resin melt-kneaded by an extruder is extruded from a T-die and brought into contact with a roll through which a coolant such as water is passed. When cooled, it is generally possible to produce a film with good transparency and good thickness accuracy. Such a method is a preferable manufacturing method for the film.

  In the film of the present invention, when it is formed and used as a single layer film, the thickness is usually 5 to 500 μm, preferably 10 to 200 μm. If the thickness is less than this range, it is difficult to process, and handling becomes difficult when laminating. On the other hand, if it is too thick, it is difficult to process and heat sealability is not exhibited.

  Moreover, a stretched film can be manufactured with a well-known stretching apparatus using the sheet | seat or film which consists of a propylene polymer of this invention. Examples of these stretching apparatuses include a tenter method, a simultaneous biaxial stretching method, and a uniaxial stretching method. In the case of a biaxially stretched film, the stretch ratio of the stretched film is desirably 10 to 70 times. In the case of a uniaxially stretched film, it is desirably 2 to 10 times. The thickness of the stretched film is usually preferably 5 to 200 μm.

[VI] Film characteristics The film of the present invention has the same characteristics as the propylene polymer, such as transparency, rigidity, and impact resistance. It is the film which consists of a polypropylene resin composition which has not been able to improve conventionally.

  In addition, the film of the present invention can be used for a composite film with another substrate in order to sufficiently exhibit its excellent transparency, rigidity, impact resistance, heat seal and the like.

  The substrate can be selected from, for example, any polymer capable of film forming, cellophane, paper, fiber structure, aluminum foil, and the like.

  Examples of the polymer capable of film forming include polyamide resins, polyester resins, polyethylene, ethylene-vinyl acetate copolymers, polyolefin resins such as ethylene-methacrylic acid copolymers, polyvinyl chloride, polyvinylidene chloride, From the vinyl alcohol copolymer, etc., it can be selected according to the purpose of making the composite film in consideration of the transparency, rigidity, adhesiveness, printability, gas barrier property and the like.

  When the substrate is stretchable, it may be uniaxially or biaxially stretched. The composite film can be produced by a known technique such as a lamination method, an extrusion lamination method, or a combination thereof. In the case of the extrusion lamination method, the thickness of the film of the present invention in the composite film constituting layer is preferably 0.5 to 100 μm.

  The present invention will be described in more detail with reference to the following examples and comparative examples, but the present invention is not limited to these examples.

〔Evaluation methods〕
In addition, the evaluation method of the film made in the Example and the comparative example was performed as described in the method of (1)-(8) shown below.

(1) Melt flow rate (MFR)
It was measured according to the melt flow rate (conditions: 230 ° C., load 2.16 kgf) of the polypropylene test method of JIS-K6758 (unit: g / 10 minutes).

(2) Memory effect (ME)
The cylinder temperature of the melt indexer is set to 190 ° C., and the orifice has a length of 8.00 mm, a diameter of 1.00 mmφ, and L / D = 8. Also, place a graduated cylinder containing ethyl alcohol directly under the orifice (the distance between the orifice and the ethyl alcohol liquid surface is 20 ± 2 mm).
In this state, the sample is put into the cylinder, the load is adjusted so that the extrusion amount per minute becomes 0.1 ± 0.03 g, and the extrudate after 6 to 7 minutes is dropped into ethanol and solidified. And then collect. Measure the maximum and minimum values of the diameter of the strand-like sample of the collected extrudates at 1 cm from the upper end, 1 cm from the lower end, and the difference between the center and 3 places. .

(3) Melting peak temperature by differential scanning calorimeter (DSC), melting end temperature Using a Seiko DSC, a sample amount of 5.0 mg was taken, held at 200 ° C. for 5 minutes, and then 10 ° C./min to 40 ° C. Crystallization was performed at a temperature lowering speed of 5 ° C., and the melting peak temperature and melting end temperature when melted at a temperature rising speed of 10 ° C./min were evaluated (unit: ° C.).

(4) Comonomer concentration Determined by 13C-nuclear magnetic resonance spectroscopy.
Apparatus: JEOL-GSX270 (manufactured by JEOL Ltd.)
Concentration: 300mg / 2ml
Solvent: Orthodichlorobenzene

(5) Extraction amount measurement by temperature rising elution fractionation (TREF) Device: CFC T150A model manufactured by Mitsubishi Chemical Co., Ltd. Column: 3 AD80M / S manufactured by Showa Denko KK Concentration: 40 mg / 10 ml
Solvent: Orthodichlorobenzene

(6) Olsen flexural modulus Measured according to JIS K7106 (unit: kg / cm ² ).

(7) Transparency (haze)
In accordance with ASTM-D1003, the obtained film was measured with a haze meter (unit:%).
A low haze value means excellent transparency. If the haze is 4.0% or less, it is judged good.

(8) Rigidity (tensile modulus)
In accordance with ISO-R1184, the obtained film was measured with an Instron type autograph (unit: kg / cm ² ).
The higher the elastic modulus, the better the rigidity.

(9) Impact (punch impact strength)
In accordance with JIS-8134, the obtained film was allowed to stand for 24 hours or more in an atmosphere at 23 ° C., and after adjusting the state, measurement was performed in the same atmosphere (unit: kg · cm / cm).
It means that impact resistance is excellent, so that this value is large.

(10) Blocking property From the obtained film, the same surface of a sample film of 2 cm (width) × 15 cm (length) was overlapped over a length of 5 cm, and the sample film was placed under an atmosphere of 40 ° C. under a load of 100 g / cm ^2. After adjusting the time state, after removing the load and sufficiently adjusting the temperature to 23 ° C., the tensile tester was opened and the force required for shearing the sample at a rate of 200 mm / min was determined (unit: g / 10 cm ² ). .
The smaller this value, the better the blocking resistance.

(11) Slip property Based on ASTM-D1894, the obtained film was evaluated by the static friction coefficient by the slip tester method.
The smaller this value, the better the slipperiness.

(12) Heat sealability Using a heat seal bar of 5 mm x 200 mm, a 15 mm wide sample is taken from a sample sealed under conditions of a heat seal pressure of 1 kg / cm ² and a heat seal time of 10 seconds at each temperature setting. Using a testing machine, it was pulled away at a tensile speed of 500 mm / min, and the load was read. The heat sealability was evaluated at the seal temperature at which the load was 300 g (unit: ° C). It means that heat sealability is excellent, so that this value is small.

Reference example 1
Production of Composition Tetrakis [methylene-3- (3 ′, 5′-di-t-butyl-4) as an antioxidant with respect to 100 parts by weight of the propylene homopolymer described in Reference Example 1 of Table 1. -Hydroxyphenyl) propionate] 0.05 parts by weight of methane, 0.05 parts by weight of tris- (2,4-di-t-butylphenyl) phosphonite, and calcium stearate (Ca-St) as a neutralizing agent in an amount of 0. After adding 1 part by weight, the mixture was high speed mixed at room temperature for 2 minutes with a Henschel mixer, then melted, kneaded, cooled and cut with a 50 mmφ extruder at a temperature of 230 ° C. to obtain a pellet-shaped resin composition.

Production of Film Using this resin composition as a raw material, an extrusion resin temperature of 230 ° C., a chill roll temperature of 30 ° C. was manufactured using a T-die method film production apparatus equipped with an extruder having a diameter of 35 mmφ, a width of 300 mm T die, an air knife and a mirror chill roll. The film was formed at a film take-off speed of 21 m / min to obtain an unstretched film having a thickness of 25 μm.

  The physical properties of this film are shown in Table 1.

Example 1
The same procedure as in Reference Example 1 was performed except that the propylene / ethylene random copolymer having the contents described in Example 1 in Table 1 was used. The evaluation results of the obtained film are shown in Table 1.

Example 2
It was carried out in the same manner as in Reference Example 1 except that the propylene / ethylene random copolymer having the contents described in Example 2 in Table 1 was used. The evaluation results of the obtained film are shown in Table 1.

Example 3
It was carried out in the same manner as in Reference Example 1 except that the propylene / ethylene random copolymer having the contents described in Example 3 in Table 1 was used. The evaluation results of the obtained film are shown in Table 1.

Example 4
It was carried out in the same manner as in Reference Example 1 except that a propylene / ethylene / butene terpolymer random copolymer having the contents described in Example 4 in Table 1 was used. The evaluation results of the obtained film are shown in Table 1.

Comparative Example 1
It was carried out in the same manner as in Reference Example 1 except that the propylene / ethylene random copolymer having the contents described in Comparative Example 1 in Table 2 was used. The evaluation results of the obtained film are shown in Table 2.

Comparative Example 2
The same procedure as in Reference Example 1 was conducted except that a propylene / ethylene / butene terpolymer random copolymer having the contents described in Comparative Example 2 in Table 2 was used. The evaluation results of the obtained film are shown in Table 2.

Comparative Example 3
It was carried out in the same manner as in Reference Example 1 except that the propylene / ethylene random copolymer having the contents described in Comparative Example 3 in Table 2 was used. The evaluation results of the obtained film are shown in Table 2.

Comparative Example 4
The same procedure as in Reference Example 1 was carried out except that a propylene / ethylene random copolymer having the contents described in Comparative Example 4 in Table 2 was used. The evaluation results of the obtained film are shown in Table 2.

Comparative Example 5
The same procedure as in Reference Example 1 was carried out except that a propylene / ethylene random copolymer having the contents described in Comparative Example 5 in Table 2 was used. The evaluation results of the obtained film are shown in Table 2.

Claims (2)

Propylene-based resin composition comprising a propylene-based α-olefin random copolymer having propylene as a main component and satisfying the following physical properties (1) to (7) processed into a film shape. Stretched film.
Physical property (1): Melt flow rate (MFR) is 0.5 to 50.0 g / 10 minutes,
Physical property (2): Memory effect (ME) is 0.9 to 1.4,
Physical property (3): The temperature [TP] of the main melting peak determined with a differential scanning calorimeter (DSC) is 100 to 150 ° C.,
Physical property (4): Melting end temperature [TE] (° C.) determined by a differential scanning calorimeter (DSC) is [TE] − [TP] ≦ 8,
Physical property (5): Random copolymer in which an α-olefin component having 2 or 4 to 20 carbon atoms and propylene are combined, and at least one α-olefin component and the content of the α-olefin component [E] (Mol%) is within the range represented by the following formula [I] and formula [II],
(140− [TP]) / 10.2 ≦ [E] ≦ (160− [TP]) / 2.6
Formula [I]
0 <[E] ≦ 23 Formula [II]
Physical property (6): Extraction amount extracted at 40 ° C. or less is 2.0% by weight or less and extraction amount extracted at 50 ° C. or less is 5.0% in the measurement by temperature rising elution fractionation (TREF) using orthodichlorobenzene as a solvent. The extraction amount extracted at 60% or less, and 20.0% by weight or less,
Physical property (7): Olsen bending elastic modulus [M] (MPa) is in a range represented by formula [III],
16.5 × [TP] −1, 530 ≦ [M] ≦ 16.5 × [TP] −1,300
Formula [III] The propylene-based resin unstretched film according to claim 1, wherein a value obtained in the blocking property test is 300 g / 10 cm ² or less.