JP2006052312A - Polypropylene composition and sealant film obtained therefrom - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polypropylene composition for sealant films, and to provide a sealant film. <P>SOLUTION: This polypropylene composition is characterized by having an MFR (230°C, 2.16 kgf) of 1 to 50 (g/10 min), an n-decane-soluble fraction of ≤3 wt.%, one or more melting peaks (namely, melting points) determined by DSC on each of a high temperature side of ≥130°C and a low temperature side of ≤125°C, and a semi-crystallization time of ≤6 min. And a 1 to 100 μm-thick sealant film is obtained from the polypropylene composition. In addition, a laminate is characterized by being a laminate comprising the layer (X) of the sealant film and at least one film layer (Y) selected from the group consisting of polyolefin films, polystyrene films, polyester films, polyamide films, the laminate films of polyolefins to gas-barrier resin films, aluminum foils, paper, and vapor-deposited films. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polypropylene composition and a molded product obtained therefrom, and more particularly to a polypropylene composition for sealant and a sealant film obtained therefrom.

  Polypropylene is used for food packaging or industrial sheets or films because it has high mechanical strength, electrical insulation, and excellent food hygiene and optical properties. Since polypropylene has a relatively high melting point, when used in sealants, in order to improve heat sealability at low temperatures, generally propylene is copolymerized with ethylene or an α-olefin having 4 to 10 carbon atoms to produce propylene / α -Used as an olefin copolymer. Conventionally, various polymers have been proposed for heat seal applications, but conventionally known heat seal materials such as high and low density polyethylene have a problem of poor transparency, and ethylene / vinyl acetate copolymers. Alternatively, existing ethylene / α-olefin copolymers generally have a problem of poor blocking resistance. Further, a packaging film made of a conventionally known propylene / α-olefin copolymer is excellent in transparency as compared with a film made of high and low density polyethylene, but heat sealability at a low temperature is not sufficient. It is known that the heat sealability at low temperatures is improved by increasing the α-olefin component to be copolymerized, while the increase in the α-olefin component leads to a decrease in blocking resistance. For this reason, the appearance of a propylene / α-olefin copolymer which is excellent in transparency, heat sealability at low temperature, and blocking resistance and can be used as a heat seal material is desired.

  The present invention is to provide a polypropylene composition for a sealant film, and a sealant film, in which various problems of the prior art are improved.

  The polypropylene composition of the present invention has an MFR (230 ° C., 2.16 kgf) of 1 to 50 (g / 10 min), an n-decane soluble content of 3% by weight or less, and a melting peak determined by DSC ( That is, it is a polypropylene composition characterized in that one or more melting points are present on the high temperature side of 130 ° C. or higher and the low temperature side of 125 ° C. or lower, respectively, and the half-crystallization time is 6 minutes or less.

  As will be described later, the unstretched film of the polypropylene composition has a Δhaze of 2% or less, which is a measure for deterioration of transparency in storage at high temperatures, and a heat seal strength at 120 ° C. seal temperature of 2.5 N / The characteristic that it is 15 mm or more is shown.

  A preferred embodiment of the polypropylene composition of the present invention is that the polypropylene composition comprises two or more different propylene polymers, and a more preferred embodiment is that the propylene polymer is a propylene polymer in the presence of a metallocene catalyst. It is a propylene-based (co) polymer obtained by homopolymerization or copolymerization of propylene and an α-olefin having 2 to 20 carbon atoms excluding propylene. A particularly preferred embodiment of the polypropylene composition of the present invention includes 5 to 80 parts by weight of a propylene polymer (A) whose melting point determined by DSC is 130 ° C. or higher, and a propylene system whose melting point determined by DSC is 125 ° C. or lower. It is a polypropylene composition which is a polymer (A) 20-95 weight part.

  The sealant film of the present invention comprises the polypropylene composition and has a thickness of 1 to 100 μm.

  The laminate of the present invention comprises a layer (X) of the sealant film, a polyolefin film, a polystyrene film, a polyester film, a polyamide film, a laminate film of a polyolefin and a gas barrier resin film, aluminum foil, paper, and vapor deposition. A laminate comprising at least one film layer (Y) selected from the group consisting of films.

  According to the present invention, a polypropylene composition excellent in transparency, suppressing deterioration of transparency in storage at high temperatures, having high heat seal strength, excellent blocking resistance, and suitably used for a heat seal material, and the composition It becomes possible to provide a sealant film obtained from a product. Moreover, since the semi-crystallization time is short while having a composition with a low melting point, high-speed film formation and high-speed bag making are possible.

  Hereinafter, the best mode for carrying out the present invention will be described in detail from the viewpoint of a polypropylene composition, a film and a laminate.

Polypropylene composition The polypropylene composition of the present invention has [1] MFR (230 ° C., 2.16 kgf) of 1 to 50 (g / 10 min) and [2] n-decane soluble content of 3% by weight or less. Yes, [3] One or more melting peaks (ie, melting points) determined by DSC are present on the high temperature side of 130 ° C or higher and low temperature side of 125 ° C or lower, and [4] Half-crystallization time is 6 minutes or less. It has the feature of being.

  MFR (230 degreeC, 2.16kgf) of the polypropylene composition of this invention exists in the range of 1-50 (g / 10min), Preferably it is 2-20, More preferably, it is 5-15. If the MFR is less than 1, extrusion characteristics are not preferable, and if it exceeds 50, T-die film formation is difficult, which is not preferable.

  The n-decane soluble content of the polypropylene composition of the present invention is 3% by weight or less, preferably 2.5% by weight or less, more preferably 2% by weight or less. When the amount of n-decane solubles exceeds 3% by weight, blocking resistance is insufficient, which is not preferable.

  The polypropylene composition of the present invention has at least two melting peaks (that is, melting point Tm) determined by DSC. In the general embodiment of the polypropylene composition of the present invention, one or more melting points are usually present on the high temperature side of 130 ° C. or higher and on the low temperature side of 125 ° C. or lower. The function of increasing the rigidity of the film and increasing the crystallization speed can be expressed by the Tm on the high temperature side, and the heat seal temperature can be lowered by the Tm on the low temperature side.

  The half crystallization time of the polypropylene composition of the present invention is 6 minutes or less, preferably 5.5 minutes or less, more preferably 5 minutes or less. If the half crystallization time exceeds 6 minutes, solidification becomes insufficient when the film is formed at high speed, which causes a problem of film formation and deteriorates the appearance of the film.

  As will be described later, the unstretched film of the polypropylene composition of the present invention has a Δhaze of 2% or less, preferably 1% or less at the same time at 120 ° C. sealing temperature, which is a measure of transparency reduction in storage at high temperatures. The heat seal strength is 2.0 N / 15 mm or more, preferably 2.3 N / 15 mm or more.

  A preferred embodiment of the polypropylene composition of the present invention is that the polypropylene composition is composed of two or more different propylene polymers. The “two or more different propylene polymers” refers to propylene polymers having different melting points (Tm) at least. In a preferred embodiment of the polypropylene composition of the present invention, the propylene polymer is obtained by homopolymerization of propylene or copolymerization of propylene and an α-olefin having 2 to 20 carbon atoms excluding propylene in the presence of a metallocene catalyst. Propylene-based (co) polymer. After each such (co) polymer is prepared separately, it may be in a blended form or in a form produced by multistage polymerization, but the important point is (co) polymerization. All proceed in the presence of a metallocene catalyst. In the present invention, two or more different propylenes in the polypropylene composition of the present invention are used as long as at least two melting peaks (that is, melting points) are present when the polypropylene composition is subjected to DSC measurement. Although there is no limitation on the proportion of the polymer, the preferred polypropylene composition of the present invention has 5 to 80 parts by weight of the propylene polymer (A) having a melting point of 130 ° C. or higher determined by DSC, and DSC. It is a polypropylene composition which is 20-95 weight part of propylene-type polymer (A) whose melting | fusing point calculated | required by 125 or less.

  The metallocene catalyst used in the present invention includes at least one compound selected from metallocene compounds and compounds capable of reacting with organometallic compounds, organoaluminum oxy compounds and metallocene compounds to form ion pairs. Furthermore, a metallocene catalyst which can be subjected to stereoregular polymerization such as an isotactic or syndiotactic structure, if necessary, is preferably a metallocene catalyst comprising a particulate carrier. Among the metallocene compounds, crosslinkable metallocene compounds that have already been published (WO01 / 27124) by the international application filed by the present applicant are preferably used.

In the above general formula [I], R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ are It is selected from hydrogen, a hydrocarbon group, and a silicon-containing group, and each may be the same or different. Such hydrocarbon groups include methyl, ethyl, n-propyl, allyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n- Linear hydrocarbon groups such as nonyl group and n-decanyl group; isopropyl group, tert-butyl group, amyl group, 3-methylpentyl group, 1,1-diethylpropyl group, 1,1-dimethylbutyl group, 1 -Branched hydrocarbon groups such as methyl-1-propylbutyl group, 1,1-propylbutyl group, 1,1-dimethyl-2-methylpropyl group, 1-methyl-1-isopropyl-2-methylpropyl group; Cyclic saturated hydrocarbon groups such as cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, norbornyl group and adamantyl group; cyclic unsaturated carbonized groups such as phenyl group, tolyl group, naphthyl group, biphenyl group, phenanthryl group and anthracenyl group A hydrogen group; Saturated hydrocarbon group substituted with cyclic unsaturated hydrocarbon group such as benzyl group, cumyl group, 1,1-diphenylethyl group, triphenylmethyl group; methoxy group, ethoxy group, phenoxy group, furyl group, N-methylamino A heteroatom-containing hydrocarbon group such as a group, N, N-dimethylamino group, N-phenylamino group, pyryl group and thienyl group. Examples of the silicon-containing group include a trimethylsilyl group, a triethylsilyl group, a dimethylphenylsilyl group, a diphenylmethylsilyl group, and a triphenylsilyl group. Further, the adjacent substituents of R ⁵ to R ¹² may be bonded to each other to form a ring. Examples of such substituted fluorenyl groups include benzofluorenyl group, dibenzofluorenyl group, octahydrodibenzofluorenyl group, octamethyloctahydrodibenzofluorenyl group, octamethyltetrahydrodicyclopentafluorenyl group, etc. Can be mentioned.

In the general formula [I], R ¹ , R ² , R ³ and R ⁴ substituted on the cyclopentadienyl ring are preferably hydrogen or a hydrocarbon group having 1 to 20 carbon atoms. Examples of the hydrocarbon group having 1 to 20 carbon atoms include the hydrocarbon groups described above. More preferably, R ³ is a hydrocarbon group having 1 to 20 carbon atoms.

In the general formula [I], R ⁵ to R ¹² substituted on the fluorene ring are preferably hydrocarbon groups having 1 to 20 carbon atoms. Examples of the hydrocarbon group having 1 to 20 carbon atoms include the hydrocarbon groups described above. The adjacent substituents of R ⁵ to R ¹² may be bonded to each other to form a ring.

In the general formula [I], Y that bridges the cyclopentadienyl ring and the fluorenyl ring is preferably a group 14 element, more preferably carbon, silicon, or germanium, and further preferably a carbon atom. R ¹³ and R ¹⁴ substituted for Y are preferably hydrocarbon groups having 1 to 20 carbon atoms. These may be the same or different from each other, and may be bonded to each other to form a ring. Examples of the hydrocarbon group having 1 to 20 carbon atoms include the hydrocarbon groups described above. More preferably, R ¹⁴ is an aryl group having 6 to 20 carbon atoms. Examples of the aryl group include the above-mentioned cyclic unsaturated hydrocarbon group, a saturated hydrocarbon group substituted with a cyclic unsaturated hydrocarbon group, and a heteroatom-containing cyclic unsaturated hydrocarbon group. R ¹³ and R ¹⁴ may be the same or different, and may be bonded to each other to form a ring. As such a substituent, a fluorenylidene group, a 10-hydroanthracenylidene group, a dibenzocycloheptadienylidene group, and the like are preferable.

  In the general formula [I], M is preferably a Group 4 transition metal, more preferably Ti, Zr, Hf and the like. Q is selected from the same or different combinations from halogen, a hydrocarbon group, an anionic ligand, or a neutral ligand capable of coordinating with a lone pair of electrons. j is an integer of 1 to 4, and when j is 2 or more, Qs may be the same or different from each other. Specific examples of the halogen include fluorine, chlorine, bromine and iodine, and specific examples of the hydrocarbon group include those described above. Specific examples of the anionic ligand include alkoxy groups such as methoxy, tert-butoxy and phenoxy, carboxylate groups such as acetate and benzoate, and sulfonate groups such as mesylate and tosylate. Specific examples of neutral ligands that can be coordinated by a lone pair include organophosphorus compounds such as trimethylphosphine, triethylphosphine, triphenylphosphine, diphenylmethylphosphine, tetrahydrofuran, diethyl ether, dioxane, 1,2-dimethoxy And ethers such as ethane. At least one Q is preferably a halogen or an alkyl group.

  Examples of such bridged metallocene compounds include isopropylidene (3-tert-butyl-5-methyl-cyclopentadienyl) (fluorenyl) zirconium dichloride, isopropylidene (3-tert-butyl-5-methyl-cyclopentadienyl). ) (3,6-ditert-butylfluorenyl) zirconium dichloride, diphenylmethylene (3-tert-butyl-5-methyl-cyclopentadienyl) (fluorenyl) zirconium dichloride, diphenylmethylene (3-tert-butyl- 5-methyl-cyclopentadienyl) (2,7-ditert-butylfluorenyl) zirconium dichloride, diphenylmethylene (3-tert-butyl-5-methyl-cyclopentadienyl) (3,6-ditert -Butyl fluoreni ) Zirconium dichloride are preferably used.

  In the metallocene catalyst according to the present invention, ions react with the organometallic compound, organoaluminum oxy compound, and transition metal compound (A) used together with the Group 4 transition metal compound represented by the general formula [I]. At least one compound selected from compounds forming a pair, and a particulate carrier used as necessary are disclosed in the above-mentioned publications (WO01 / 27124) and JP-A-11-315109 by the present applicant. The used compounds can be used without limitation.

  Preferable specific examples of the α-olefin used together with propylene in the copolymerization according to the present invention include ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene and the like. These can be used at the same time, and among them, ethylene and 1-butene are preferably used.

  In the present invention, an additive such as an antioxidant, a heat stabilizer, a weather stabilizer, a slip agent, an antiblocking agent, a crystal nucleating agent, etc. is included as necessary, as long as the performance as a polypropylene composition is not impaired. May be.

  In addition, after blending each of the above components and, if necessary, various additives with a mixer such as a Henschel mixer, a Banbury mixer, a tumbler mixer, etc., the film formation described later as a pellet using a uniaxial or biaxial extruder However, it can also be used in a film forming machine in a state where the above components are blended.

Film By forming a film from the polypropylene composition of the present invention, a film of a packaging material that requires high heat seal strength and low temperature heat sealability can be formed at high speed. The film may be formed by a cast forming method or an inflation forming method, and a film having a good uniform film thickness can be produced usually under a resin temperature of 200 to 260 ° C. The thickness of the film is usually in the range of 1 to 100 μm, preferably 3 to 80 μm.

  Since the film of the present invention has high heat seal strength and low temperature heat sealability, it is suitably used as a sealant film for packaging materials when used as a laminate described later.

Laminate The film can be used alone, but is generally used as a packaging film or a packaging sheet in the construction of a laminate laminated on a substrate.

  Although it does not specifically limit as a base material, Polyolefin films, such as polyethylene and a polypropylene, A film of styrene resin, Polyester films, such as a polyethylene terephthalate and a polybutylene terephthalate, Nylon 6, nylon 6,6 Polyamide films, or stretched films of these, laminated films of polyolefin films and resin films with gas barrier properties such as polyamide films and ethylene-vinyl alcohol copolymer films, metal foils such as aluminum, aluminum, silica, etc. A vapor-deposited film, paper or the like on which is vapor-deposited is appropriately selected and used depending on the intended use of the packaging material. This base material can be used not only in one type but also in combination of two or more types.

  The film layer obtained from the polypropylene composition of the present invention is preferably located in at least one outermost layer of the laminate to form a sealant layer. In the production of the laminate, a method of directly extruding and laminating the resin composition of the present invention on a base material, dry laminating a base material and a sealant film, or co-extrusion of resins constituting both layers. Can be adopted.

  As one embodiment of a laminated body, the structure of sealant film layer (X) / polyolefin film layer (Y1) / other film layers (Y2) can be mentioned. Here, as another film layer, a layer selected from the group consisting of the aforementioned polystyrene film, polyester film, polyamide film, laminated film of polyolefin film and gas barrier resin film, aluminum foil, vapor deposition film, and paper is used. Can be mentioned.

  When the polyolefin layer and the other film layer cannot be bonded with sufficient adhesive strength, a structure of sealant film layer / polyolefin film layer / adhesive layer / other film layer can be employed. As an adhesive layer, an anchor coating agent such as a urethane-based or isocyanate-based adhesive, or a modified polyolefin such as an unsaturated carboxylic acid grafted polyolefin may be used as an adhesive resin to firmly bond adjacent layers. it can.

  The film layers of the laminate described above are faced to each other, or the film layer of the laminate is faced to another film, and then at least a part of the periphery is heat-sealed so as to have a desired container shape from the outer surface side Thus, the container can be manufactured. Moreover, the sealed bag-shaped container can be manufactured by heat-sealing the entire periphery. When this bag-shaped container molding process is combined with the contents filling process, that is, the bottom and sides of the bag-shaped container are heat sealed, then the contents are filled, and then the top is heat sealed to produce a package. can do. Therefore, this laminate film can be used in an automatic packaging apparatus for solids such as confectionery and bread, powder, or liquid material.

EXAMPLES Next, although this invention is demonstrated in detail based on an Example, this invention is not limited to this Example. The measuring method of the physical property in an Example is as follows.
1) n-decane soluble amount A sample was completely dissolved by adding 200 ml of n-decane to 5 g of the sample and heating with stirring. It was cooled to 20 ° C. over about 3 hours and left for 30 minutes. Thereafter, the precipitate was filtered off. The filtrate was put in 1000 ml of acetone to precipitate the components dissolved in n-decane. The precipitate and acetone were filtered off and the precipitate was dried. Even when the filtrate side was concentrated to dryness, no residue was observed. The amount of soluble n-decane was determined by the following formula.
n-decane soluble content (wt%) = [precipitate weight / sample weight] × 100

2) Melting point (Tm)
It measured using the DSC measuring device.
Equipment: Seiko Instruments Inc. DSC6200,
Sampling: Finely chop the pellet and insert it into the specified container.
Condition: The temperature is raised to 230 ° C. at 10 ° C./min, and preheated in an atmosphere at 230 ° C. for 10 minutes. Thereafter, the temperature at the top of the crystallization peak obtained by lowering the temperature at 10 ° C./min is defined as the crystallization temperature. When the temperature was lowered to 50 ° C., the temperature was raised again to 230 ° C. at 10 ° C./min, and the melting point was determined from the melting curve obtained at that time.

3) Melt flow rate (MFR)
Measurement was performed at 230 ° C. and a load of 2.16 kg by the method of ASTM D-1238. Without introducing nitrogen into the cylinder, the pellets were directly charged into the cylinder and melted.

4) Half crystallization time (T _1/2 )
DSC measuring instrument: Perkin Elmer Co., Ltd. DSC-7
Sampling: The pellet is heated and pressed at 230 ° C. to form a thin sheet, cut into a predetermined size, and inserted into a predetermined container.
Measurement conditions: The temperature is raised to 230 ° C. at 40 ° C./min and preheated for 10 minutes in an atmosphere at 230 ° C. Thereafter, the temperature is lowered to 105 ° C. at 320 ° C./min and held in an atmosphere of 105 ° C. The time required to reach 1/2 of the total amount of crystallization heat obtained at that time is T _1/2 .

5) Haze
Measured according to ASTM D-1003.

6) Heat seal strength The film was sampled to a width of 5 mm and sealed at a seal time of 1 second and a pressure of 0.2 MPa. Both ends of the sealed film were pulled at 300 mm / min, and the peel strength was measured. The upper part of the seal bar was set at 120 ° C., and the lower part was performed at 70 ° C.

Obtained by polymerizing with a catalyst combining diphenylmethylene (3-t-butyl-5-methylcyclopentadienyl) (2,7-di-t-butylfluorenyl) zirconium dichloride and methylaluminoxane as a metallocene compound. The
Propylene copolymer (A1); ethylene content 1.5% by weight, melting point 138 ° C., and propylene copolymer (B1); ethylene content 5.1% by weight, melting point 115 ° C.,
50 parts by weight of each, and 0.1 parts by weight of tetrakis [methylene-3 (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane as an antioxidant, 2,4-bis ( 1,1-dimethyl) -phosphate phenol 0.1 parts by weight, calcium stearate 0.1 parts by weight as a neutralizing agent, synthetic silica 0.15 parts by weight, erucic acid amide 0.1 parts by weight Using a KTX-30 twin screw extruder, polypropylene was pelletized by melt-kneading at a resin temperature of 250 ° C. Table 1 summarizes the measured physical properties of the obtained pellets.

  The polypropylene composition pellets thus obtained were melted at 250 ° C. with a 65 mmφ extruder, extruded from T die, and a chill roll maintained at 15 ° C. yielded a film with a take-up speed of 30 m / min and a thickness of 30 μm. It was.

  The same procedure as in Example 1 was performed except that the blend ratio of the propylene-based copolymers (A1) and (B1) used in Example 1 was changed to (A1) :( B1) = 30: 70. Table 1 summarizes the measured physical properties of the obtained pellets.

  Propylene copolymer (A1) used in Example 1, and diphenylmethylene (3-t-butyl-5-methylcyclopentadienyl) (2,7-di-t-butylfluorenyl) as a metallocene compound ) Propylene copolymer (B2) obtained by polymerizing with a catalyst combining zirconium dichloride and methylaluminoxane (ethylene content 5.7 wt%, melting point 110 ° C.), (A1) :( B2) = The same procedure as in Example 1 was performed except that the blending ratio was 50:50. Table 1 summarizes the measured physical properties of the obtained pellets.

  It is obtained by polymerization with a catalyst combining diphenylmethylene (3-t-butyl-5-methylcyclopentadienyl) (2,7-di-t-butylfluorenyl) zirconium dichloride and methylaluminoxane as a metallocene compound. The propylene-based polymer (A2) [ethylene content 0% by weight, melting point 147 ° C.] and the propylene-based copolymer (B1) used in Example 1 were prepared as follows: (A2) :( B1) = 20: 80 The same procedure as in Example 1 was performed except that the blend ratio was used. Table 1 summarizes the measured physical properties of the obtained pellets.

[Comparative Example 1]
The same procedure as in Example 1 was performed except that 100 parts by weight of the propylene copolymer (A1) used in Example 1 was used. Table 1 summarizes the measured physical properties of the obtained pellets.

[Comparative Example 2]
Instead of a catalyst comprising a combination of diphenylmethylene (3-t-butyl-5-methylcyclopentadienyl) (2,7-di-t-butylfluorenyl) zirconium dichloride and methylaluminoxane, dimethylsilylene bis- (2 -Methyl-4-phenylindenyl) obtained by polymerizing with a catalyst combining zirconium dichloride and methylaluminoxane,
Propylene copolymer (A3); ethylene content 1.4 wt%, melting point 138 ° C., and propylene copolymer (B3); ethylene content 4.9 wt%, melting point 115 ° C.,
Were performed in the same manner as in Example 1 except that 50 parts by weight of each was blended. Table 1 summarizes the measured physical properties of the obtained pellets.

[Comparative Example 3]
Example 1 except that 100 parts by weight of a raw material having an ethylene content of 3% by weight, a butene content of 1.8% by weight, and a melting point of 139 ° C. was obtained by polymerizing polypropylene using an MgCl ₂ -supported TiCl ₄ catalyst and triethylaluminum. And performed in the same manner. Table 1 summarizes the measured physical properties of the obtained pellets.

Claims (7)

  MFR (230 ° C., 2.16 kgf) is 1 to 50 (g / 10 min), n-decane soluble content is 3% by weight or less, and melting peak (ie, melting point) determined by DSC is 130 ° C. or higher. A polypropylene composition characterized by having one or more of each on the high temperature side and a low temperature side of 125 ° C. or lower, and having a half-crystallization time of 6 minutes or less.   2. The polypropylene composition according to claim 1, wherein the unstretched film has a heat seal strength at a sealing temperature of 120 ° C. of 2.0 N / 15 mm or more.   The polypropylene composition according to claim 1 or 2, comprising two or more different propylene-based polymers.   The propylene polymer is a (co) polymer obtained by homopolymerization of propylene or copolymerization of propylene and an α-olefin having 2 to 20 carbon atoms excluding propylene in the presence of a metallocene catalyst. The polypropylene composition according to claim 3.   5 to 80 parts by weight of a propylene-based (co) polymer (A) having a melting point determined by DSC of 130 ° C. or higher, and a propylene-based (co) polymer (A) 20 having a melting point determined by DSC of 125 ° C. or lower. The polypropylene composition according to claim 4, which is -95 parts by weight.   The sealant film which consists of a polypropylene composition in any one of Claims 1-5, and whose thickness is 1-100 micrometers.   The layer (X) of the sealant film according to claim 6, and a polyolefin film, a polystyrene film, a polyester film, a polyamide film, a laminated film of a polyolefin and a gas barrier resin film, an aluminum foil, paper, and a vapor deposition film. A laminate comprising at least one film layer (Y) selected from the group.