JPH07188431A - Pliable polypropylene-based film for face material - Google Patents

Abstract

PURPOSE:To obtain a film excellent in pliability, transparency, heat resistance, low-temp. impact resistance, and elastic recovery from elongation. CONSTITUTION:This film comprises a polypropylene copolymer and 10-60wt.% hydrogenated copolymer comprising at least one polymer block formed mainly from a vinylaromatic compound and at least one polymer block formed mainly from a hydrogenated conjugated diene compound. It preferably has recesses on at least one side which have a depth of 5mum or larger and the density of which along at least a line extending in one direction on the surface is 1-200.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible polypropylene film for skin material. More specifically, the present invention relates to a flexible polypropylene film which is excellent in flexibility, transparency, heat resistance, low-temperature impact resistance and tensile elastic recovery property and is suitable as a skin material such as automobile interior materials and building materials such as wallpaper.

[0002]

2. Description of the Related Art Conventionally, polypropylene films are excellent in transparency, mechanical properties, moisture resistance, etc., and are widely used for packaging applications, automobile parts, especially interior material skin materials, etc. As an alternative to soft vinyl chloride sheet, flexibility, transparency, heat resistance (especially above 120 ° C)
There is a demand for a polyolefin film which has both low temperature impact resistance and excellent tensile elastic recovery. As a conventional technique proposed as a solution to these problems, a polypropylene copolymer composition to which an ethylene / propylene copolymer rubber or an ethylene / butene copolymer rubber is added (Japanese Patent Laid-Open No. 62-74951), or styrene-ethylene-
Polypropylene composition added with butylene-styrene copolymer (Japanese Patent Publication No. 62-19461, Japanese Patent Publication No. 63-95)
46), and as an improvement in heat resistance, styrene-ethylene-
Highly crystalline polypropylene homopolymer composition containing butylene-styrene copolymer (Japanese Patent Publication No. 4-80060)
Is mentioned.

[0003]

However, in the polypropylene film according to the above-mentioned prior art, the flexibility,
It has transparency, heat resistance, low temperature impact resistance, and tensile elasticity recovery, and it also provides slipperiness between films.
It is difficult to satisfy all these characteristics. That is, the method of adding a large amount of ethylene / propylene copolymer rubber or the like to impart flexibility tends to impair the transparency, and the method of adding a large amount of styrene-ethylene-butylene-styrene copolymer tends to impair the heat resistance, In addition, the extrusion moldability is likely to be poor, and this improved formulation is Japanese Patent Publication No. 4-800.
No. 60 is not preferable because it tends to be inferior in flexibility.

The present invention solves the above problems and provides a flexible polypropylene film having flexibility, transparency, heat resistance (especially 120 ° C. or higher), low temperature impact resistance and tensile elastic recovery. It is a thing.

[0005]

As a result of careful investigation, in order to solve the above problems, a polypropylene copolymer (a) and a polymer block A containing at least one vinyl aromatic compound as a main component and at least 1 A hydrogenated block copolymer (b) comprising 10 to 60% by weight of a polymer block B mainly composed of hydrogenated conjugated gen compound, and a flexible polypropylene film for skin material. This is what constitutes the invention.

The polypropylene copolymer (a) of the present invention is a copolymer of propylene and an α-olefin monomer and has a different copolymerization form, that is, a mixture of a random copolymer and a block copolymer. is there. It is preferable to use a mixture of the two in terms of heat resistance, low temperature impact resistance, and tensile elasticity recovery. The polypropylene random copolymer is a random copolymer of propylene and an α-olefin monomer, and the α-olefin is ethylene,
Butene-1, pentene-1, 4-methylpentene-1,
Hexene-1, octene-1 and the like, ethylene,
Butene-1 is particularly preferred. In this case, the polypropylene random copolymer preferably has a melting point in the range of 135 to 150 ° C. from the viewpoint of flexibility, and the copolymer having a melting point in this range may be prepared by mixing one or more kinds of α-olefin monomers with 2 It is available from polypropylene copolymerized in the range of about 15% by weight. The melt flow index (MFI) is preferably in the range of 0.5 to 30 g / 10 minutes, more preferably 1 to 10 g / 10 minutes. The polypropylene block copolymer is typically a block copolymer of a polymer block component mainly consisting of propylene monomer and a polymer block component mainly consisting of ethylene monomer, and each polymer is The composition and the molecular weight of the block can be controlled at the polymerization stage. Generally, it can be obtained by a polymerization method of two or more stages as shown in JP-A-59-115312.
The polypropylene block copolymer has a melting point of 165 to 15
Those in the range of 0 ° C. are preferable in the present invention.

The content of the polypropylene copolymer (a) of the present invention is preferably 40% by weight or more of the film, and more preferably 50% by weight or more from the viewpoint of high temperature heat resistance.
Further, the content of the polypropylene copolymer (a) is 90% by weight, preferably 80% by weight or less of the film, and if it exceeds this range, the flexibility and tensile elastic recovery of the film are poor, which is not preferable. Further, polypropylene copolymer (a)
Is a mixture of a polypropylene block copolymer and a polypropylene random copolymer, and the proportion of the polypropylene block copolymer is preferably in the range of 50 to 80% by weight from the viewpoint of tensile elastic recovery of the film and flexibility.
When the proportion of the polypropylene block copolymer is less than 50% by weight, the film is inferior in tensile elasticity recovery and flexibility, and when it exceeds 80% by weight, it is inferior in transparency and flexibility.

The hydrogenated block copolymer (b) of the present invention is
It has a structure composed of at least one polymer block A mainly containing a vinyl aromatic compound and at least one polymer block B mainly containing a hydrogenated conjugated gen compound, for example, AB -A, B-A-B-A,
Examples thereof include hydrogenated block copolymers composed of BABABAB and mixtures thereof. The hydrogenated block copolymer preferably contains the vinyl aromatic compound in an amount of 5 to 30% by weight. When the vinyl aromatic compound component of the hydrogenated block copolymer is less than 5% by weight, it becomes an adhesive resin,
It is not preferable because the extrusion process during film forming becomes difficult.
On the other hand, if this component exceeds 30% by weight, the compatibility with other mixed resins is poor and it is not preferable.

Examples of the vinyl aromatic compound constituting the hydrogenated block copolymer include styrene and α-methylstyrene, and styrene is particularly preferable. Further, as the conjugated gen compound before hydrogenation constituting the hydrogenated conjugated gen compound, for example, butadiene, isoprene,
Examples include 1,3 pentagen, and butadiene is particularly preferable. It is preferable that 80%, preferably 90% or more, of the aliphatic double bond based on the conjugated gen compound of the vinyl aromatic compound-conjugated gen compound block copolymer is hydrogenated to form the olefin compound polymer block B. As a typical example of copolymer, styrene-ethylene-butylene-
Examples thereof include styrene copolymers, and the copolymerization amount of styrene is preferably 10 to 20% by weight.

The content of the hydrogenated block copolymer of the present invention is in the range of 10 to 60% by weight, preferably 20 to 50% by weight. When the content of the hydrogenated block copolymer is less than the range of the present invention, flexibility and tensile elastic recovery are deteriorated, which is not preferable. On the other hand, if it exceeds the range of the present invention, the film tends to be softened and deformed at a high temperature, which is not preferable.

Further, a softening aid (c) may be used in combination. The content of the softening aid is equal to or less than the content of the hydrogenated block copolymer, and the total amount of the softening aid (c) and the hydrogenated block copolymer (b) is a resin mixture constituting the film. 20 to 60% by weight is preferable. Specifically, for example, the content of the hydrogenated block copolymer is 10 to 3
It can be applied as a mixed resin in which 0% by weight and the softening aid are in the range of 10 to 30% by weight.

As the softening aid (c), low density polyethylene (LDPE), linear low density polyethylene (LLD)
PE), ethylene-propylene copolymer (EPR), ethylene-butene copolymer (EBR), and other ethylene-based polymers having no polar group are preferred. Among them, especially linear low density polyethylene (LLDPE), ethylene-butene-
1-copolymer (EBR) is preferred. It is preferable to use these softening aids in combination so long as the heat resistance of the film is not impaired, in order to reduce the raw material cost of the film.

In the present invention, the tensile elastic recovery rate of the film is preferably 50% or more. When the tensile elastic recovery rate of the film of the present invention is 50% or more, when the film is stressed to cause dents, the film has excellent resilience, which is preferable.

The film surface of the present invention has a dent depth of 5 μm or more on at least one side, and a dent density on a line in at least one direction of the surface of 1 to 200 pcs / cm, preferably 10 to 50 pcs / cm. It is preferable to have a range of depressions. When the depth of the recesses and the density of the recesses are less than this range, slippage between the film surfaces is likely to be poor. If it exceeds this range, the transparency of the film tends to deteriorate. The shape of the depressions can be any shape such as a lattice shape or a turtle shell shape.

The film of the present invention preferably contains a heat stabilizer, an antioxidant, an inorganic or organic lubricant, an antistatic agent, a flame retardant, etc., if necessary. In particular, 0.1 to 5 parts by weight, more preferably 0.2 to 2 parts by weight, of an organic lubricant such as silicone oil or natural wax is added to 100 parts by weight of the resin composition of the film. Is preferable because it tends to improve. In addition, it is preferable because fingerprints and the like are prevented from becoming soiled, and the skin feel such as sliminess is easily added. Examples of silicone oil include dimethylpolysiloxane (dimethyl type silicon), alkyl- or phenyl-modified type silicon, and polyether-modified type silicon. Especially, the polyether-modified type silicon maintains film transparency and the slipperiness between films is high. Are particularly preferred because they are easily imparted. Examples of natural waxes include carnauba wax, beeswax, and rice wax.

The film thickness of the present invention is 50 to 500 μm.
Is preferred.

Next, the method for producing the film of the present invention will be described.

First, the resin of the present invention and the additive are mixed in a predetermined composition ratio to prepare raw materials, which are then fed to an extruder, and then 230-
It is melt extruded at a temperature of 280 ° C., passed through a filtration filter, shaped into a sheet from a die, wound around a metal drum, cooled and solidified to obtain a soft polypropylene film. As a method of engraving indentations on the film surface, a method of transferring with a metal drum having a desired indentation shape in the cooling stage of the extrusion sheet, and a small diameter roll that can be cooled by passing water and has a desired indentation shape are used. , A method of transferring an extruded sheet by pressing it on a metal drum, a method of transferring a formed film under pressure at a temperature of 40 to 130 ° C. with a metal roll having a desired concave shape, or another substrate. And heating laminate,
Alternatively, there is a method of performing embossing at the processing stage such as simultaneous press molding, and any of these methods may be used, or two or more may be used in combination. The embossed film is excellent in slipperiness between the films, and is improved in handleability when wound in a roll shape or when laminating with another substrate. Further, when it is used as a skin material, the touch feeling is improved, and the effect of preventing fingerprint stains can be seen.

The film of the present invention can be usefully used as a skin material. For example, it can be laminated on a base material such as a nylon film, a polyester film, various foam sheets, various non-woven fabrics, woven fabrics, and cellulose paper to be used for automobile interiors, wallpaper, floor materials, various packaging materials and the like.

[0020]

The film of the present invention is a mixed film containing a specific polypropylene copolymer and a specific hydrogenated block copolymer in a specific range, thereby providing flexibility that cannot be achieved conventionally.
A film satisfying at the same time transparency, heat resistance, low temperature impact resistance and tensile elastic recovery could be obtained. Further, by adding a lubricant or forming a recess in the film, the sliding property between the films is improved, and the touch feeling as a skin material such as an automobile interior material is imparted, which is desirable.

[0021]

EXAMPLES The characteristic values of the present invention are based on the following measuring methods.

(1) Young's modulus of film (flexibility) A test piece having a width of 10 mm and a length of 50 mm was pulled at a speed of 20.
A stress-strain curve was obtained at mm / min and a chart speed of 500 mm / min, and the stress-strain curve was obtained from the linear gradient within the elastic limit elongation.

(2) Haze of Film (Transparency) A film having a thickness of 200 μm was measured according to ASTM D1003.

(3) Heat resistance of film A film having a thickness of 200 μm is 10 mm wide and 150 m long.
A load of 10 g in weight was applied to the test piece of m and heated in a hot air oven at a temperature of 120 ° C. for 15 minutes, then the sample was cooled, and the deformation elongation of the sample was displayed according to the following criteria.

Evaluation Level Thermal Deformation Elongation (mm) 0 to 10 Δ 11 to 20 × 21 to Melt Cutting Δ The above is the level at which there is no problem in heat resistance in practical use.

(4) Impact strength of film A thickness of 5 in a device capable of adjusting the measurement temperature of a sample to 5 ° C.
Attach a 0 μm film to a circular frame with a diameter of 10 cm,
A metal ball having a weight of 500 g was dropped from the height of 2.5 m to the center of the film, and the velocity V ₁ of the metal ball immediately after the film was broken by the photoelectric tube was measured. Next, a metal ball was dropped under the same conditions as above except that nothing was attached in a circular shape, and the velocity V ₂ of the metal ball at the same height as V ₁ was measured. From this result, the impact energy-E of the film was determined using the following formula. E = m (V ₂ ² −V ₁ ² ) / ² gd (kg · cm /
mil) where m is the weight of the metal sphere (kg) g is the acceleration of gravity (980 cm / sec ² ) d is the thickness of the sample (mil) (5) Film tensile elastic recovery rate Tensile tester in an environment of 23 ° C Width 10 mm, trial length 10
A 0 mm test piece was attached to the test piece, which was stretched at a rate of 5 mm / min to an elongation of 50% (50 mm) of the test length, held for 3 minutes, and then returned at the same rate to obtain a load cell with zero stress. The elastic recovery length was divided by the extension length (50 mm) of the trial length, and the percentage (%) was expressed as the tensile elastic recovery rate.

(6) Slidability between films Evaluation was made on the slidability between the films under a load of 50 g by stacking two films, each having a width of 5 cm and a length of 10 cm, with their edges displaced from each other in an area of 5 × 5 cm 2. However, it was displayed based on the following criteria. For embossed films, we saw slippage between the embossed and non-embossed surfaces.

Evaluation status display The film is stretched without slipping. × The film is slippery, but requires a considerable amount of force. △ The film is easily slippery. ○ The present invention will be explained with reference to examples.

Examples 1 to 5 and Comparative Examples 1 to 4 As the polypropylene copolymer (a), the amount of ethylene was 3.
7% by weight of ethylene / propylene random copolymer (melting point, 139 ° C., EPC-1), and 8% by weight of ethylene
Ethylene / propylene block copolymer (melting point, 16
2 ° C.), and as the hydrogenated block copolymer (b),
Hydrogenated styrene-butadiene copolymer (SEBS) "Dyalon 1320P (manufactured by Nippon Synthetic Rubber Co., Ltd., styrene content 10% by weight, melt index 3.5 g /
10 minutes) and low density polyethylene "Sumikasen α" FZ202-0 (Sumitomo Chemical Co., Ltd.) as a softening aid.
Manufactured by LLDPE), blended into the powder in Table 1, supplied to an extruder, melt-extruded at a temperature of 260 ° C., led to a slit-shaped die and molded into a sheet, and then a temperature of 40 ° C. It was wound around a metal drum of No. 3 and cooled to obtain a flexible polypropylene film. The thickness of the film was changed to 200 μm and 50 μm by changing the speed of the metal drum. The properties of the obtained film are shown in Table 2.

Example 6 0.7 parts by weight of polyether-modified silicon was mixed with 100 parts by weight of the resin mixture of Example 2, supplied to a twin-screw extruder, melt-mixed at 260 ° C., and pelletized. Cut and
It was processed into chips and raw materials were prepared. Using this raw material, a film was obtained in the same manner as in Example 2. The characteristics of this film are shown in Table 2. The slidability between the films of the film of Example 2 was x, but the slidability between the films of the film of Example 6 was Δ, and the slidability between the films could be imparted.

Example 7 Using a pair of nip rolls (embossing device) of a metal roll and a rubber roll with a grid pattern having a depth of 50 μm and 2 mm intervals, a metal roll temperature of 60 ° C. and a linear pressure. 10 kg /
thickness of Example 2 at a pressure of cm and a speed of 1 m / min of 200 μm
One side of the film was embossed, and the film was rolled into a roll. The slidability between the films was significantly improved (sliding property between the films = ○), and the handling became easier. In addition, the film was not sticky to the touch, and could be made into a film with excellent touch and flexibility.

[0032]

[Table 1]

[Table 2] Examples 1 to 5 can be films that simultaneously satisfy transparency, flexibility, heat resistance, low temperature impact resistance, and tensile elastic recovery, but in Example 6, slipperiness between the films is further imparted. , The handling property of the film is improved. Further, in the comparative example, it is not preferable because one of transparency, heat resistance, impact strength, and tensile elasticity recovery cannot be satisfied.

[0033]

Industrial Applicability According to the present invention, the resin to be mixed and the content thereof are set in a specific range, so that the transparency, flexibility, heat resistance, low temperature impact resistance and tensile elastic recovery of the film are simultaneously satisfied. As a substitute for the soft vinyl chloride sheet, a flexible polypropylene film suitable for various skin materials and the like can be obtained by laminating it with other base materials.

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Claims (4)

[Claims] 1. A polypropylene copolymer (a), a polymer block A mainly containing at least one vinyl aromatic compound, and a polymer block B mainly containing at least one hydrogenated conjugated gen compound. A film for a flexible polypropylene-based skin material, which comprises 10 to 60% by weight of a hydrogenated block copolymer (b) consisting of 2. A resin mixture containing the softening aid (c) in an amount equal to or less than the content of the hydrogenated block copolymer (b), and the total amount of the components (b) and (c) constitutes a film. Body 1
20-60 weight% with respect to 00 weight part, The film for flexible polypropylene skin materials of Claim 1 characterized by the above-mentioned. 3. The flexible polypropylene-based skin material according to claim 1, wherein the lubricant is contained in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the resin mixture constituting the film. Film. 4. The film according to claim 1, wherein the film has a dent depth of 5 μm or more on at least one surface, and a dent density on a line in at least one direction of the surface of 1 to 200 pcs / cm. Soft polypropylene film for skin materials.