JP3461951B2 - Polyolefin composition - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyolefin composition having excellent weather resistance, and more particularly to a porous sheet having excellent weather resistance, air permeability and waterproofness.

[0002]

2. Description of the Related Art In recent years, polyolefin resins have been widely used in various industrial products such as automobile parts and household electric appliances. Further, the composition containing a polyolefin resin as a main component is also used in various waterproof sheets such as civil engineering sheets and agricultural multi-sheets used at various construction sites.

As such a waterproof sheet, a non-porous sheet having no breathability has been conventionally used for the purpose of waterproofing as a first purpose. In recent years, however, water vapor and air inside are discharged to the outside, and A porous sheet having a waterproof property against external water such as rainwater is being used.

As such a porous sheet, it is generally known that a polyolefin is blended with an inorganic filler and stretched, and the manufacturing method thereof is, for example, Japanese Patent Publication No. 3-62738.
Japanese Patent Publication No. 5-45618.

[0005]

Since these waterproof sheets are widely used outdoors, deterioration due to ultraviolet rays poses a problem. In order to prevent deterioration due to ultraviolet rays, it is usual to add a triazole-based, benzophenone-based or salicylate-based ultraviolet absorber or a hindered amine-based weathering stabilizer. Further, various inorganic fillers are added to improve not only weather resistance but also other physical properties such as moldability and air permeability due to porosity.

However, when various inorganic fillers are added to the polyolefin resin, the weather resistance may not be improved even if a triazole-based, benzophenone-based or salicylate-based UV absorber or a hindered amine-based weathering stabilizer is added. . Moreover, even if some weather resistance is imparted, it does not last for a long time.

Therefore, an object of the present invention is to provide a polyolefin composition having good weather resistance for a long period of time, and a porous sheet obtained by molding the composition.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the inventors of the present invention have conducted extensive studies and as a result, as a result, a polyolefin resin and an inorganic filler are coated with silica and / or alumina to form titanium oxide and a benzoate-based ultraviolet absorber. It was found that the polyolefin composition obtained by adding the agent in a specific amount and the porous sheet obtained by molding the composition retain good weather resistance for a long period of time,
The present invention has been proposed.

That is, the present invention comprises: (1) 100 parts by weight of a polyolefin resin (2) 50 to 400 parts by weight of an inorganic filler (3) 1 to 20 parts by weight of titanium oxide surface-coated with silica and / or alumina and ( 4) Benzoate-based UV absorber A polyolefin composition comprising 0.2 to 10 parts by weight, and a porous sheet comprising the polyolefin composition.

As the polyolefin resin in the present invention, a homopolymer of α-olefin such as ethylene or propylene or a copolymer thereof can be used without particular limitation. Of these, medium / low pressure polyethylene such as high density polyethylene, medium density polyethylene, linear low density polyethylene, polypropylene, and propylene-ethylene copolymer are preferable. In particular, when the density is 0.89 to 0.94 g / cm ³ , the melt flow index (MFR) is 0.1 to 10 g /
A linear low density polyethylene of 10 minutes, preferably 1 to 5 g / 10 minutes is preferably used. Also, flexibility and tension
For applications that require tear strength, the crystallinity by X-ray is 5
A copolymer of ethylene and another α-olefin having a density of ˜25% and a density of 0.86 to 0.90 g / cm ³ can be preferably used. In the present invention, two or more kinds of the above polymers or copolymers may be mixed.

The inorganic filler used in the present invention is not particularly limited, but an inorganic filler usually mixed in rubber or plastic can be used. For example, calcium carbonate, gypsum, calcium sulfite, calcium phosphate, magnesium carbonate, basic magnesium carbonate, magnesium sulfate, hydrated silicic acid, silicic acid anhydride, soda ash, sodium chloride, barium sulfate, clay, various cements, volcanic ash, shirasu, Examples thereof include titanium oxide, iron oxide, carbon black, various metal powders, other inorganic substances or organic metal salts mainly composed of inorganic substances.

The size of the inorganic filler is not particularly limited, but when the average particle size is too small, stretching unevenness occurs,
On the other hand, if it is too large, the size of the pores in the porous sheet becomes too large, so it is generally 50 μm or less, preferably in the range of 0.05 to 30 μm, particularly 0.1 μm.
It is preferably about 5 μm.

The blending ratio of the inorganic filler is 50 to 400 parts by weight, preferably 60 to 300 parts by weight, based on 100 parts by weight of the polyolefin resin, and when less than 50 parts by weight, the composition is obtained by using the composition. Since the number of communicating holes of the porous sheet is small, the air permeability is small, and when it is 400 parts by weight or more, it is difficult to form and stretch the sheet-like material, which is not preferable.

The greatest feature of the present invention is that the above-mentioned polyolefin resin and inorganic filler are blended with titanium oxide whose surface is coated with silica and / or alumina, and a benzoate-based ultraviolet absorber. With such a composition, molding and stretching of a sheet material can be achieved very easily, and the resulting porous sheet has good weather resistance for a long period of time.

The titanium oxide surface-coated with silica and / or alumina used in the present invention is a titanium oxide having a rutile type or anatase type crystal structure obtained by a chlorine method or a sulfuric acid method, and the surface thereof is silica and / or alumina. Coated ones are preferred. The amount of silica and / or alumina coated is 2 to 20 parts by weight, preferably 4 to 10 parts by weight, based on 100 parts by weight of titanium oxide, for reasons such as weather resistance, hiding power and colorability of the resulting porous sheet. Coated ones are preferred. In particular,
When the rutile-type titanium oxide coated with 4 to 10 parts by weight of the composite of silica and alumina is used, the effect of weather resistance is most obtained.

The blending ratio of titanium oxide surface-coated with silica and / or alumina used in the present invention is 1 to 20 parts by weight based on 100 parts by weight of the polyolefin resin.
It is preferably 5 to 10 parts by weight. When the amount is less than 1 part by weight, the weather resistance of the porous sheet obtained by using the composition is lowered, and the weather resistance of the porous sheet obtained by adding 20 parts by weight or more is in an equilibrium state. And the effect of addition is not recognized.

In the present invention, a benzoate-based ultraviolet absorber is added to each of the above components in order to further improve weather resistance. When an ultraviolet absorber other than the benzoate-based ultraviolet absorber is used, the effect of improving weather resistance cannot be expected. Examples of the benzoate-based ultraviolet absorber include 2,4-di-t-butylphenyl-3 ′, 5′-di-t-butyl-
4-Hydroxybenzoate, 2,4-di-t-butylphenyl-3 ', 5'-di-t-butyl-4-benzoate, resorcinol monobenzoate, 4-octylphenyl-3', 5'-di-t. -Butyl-4-hydroxybenzoate and the like.

The blending ratio of the benzoate type ultraviolet absorber is 0.2 to 1 with respect to 100 parts by weight of the polyolefin resin.
It is 0 part by weight, preferably 0.5 to 5.0 parts by weight. If the amount is less than 0.2 parts by weight, the weather resistance cannot be exhibited, and if it is more than 10 parts by weight, bleeding (blooming) occurs on the surface of the porous sheet, which is not preferable.

In the present invention, in addition to the above-mentioned polyolefin resin, inorganic filler, surface-treated titanium oxide and benzoate-based UV absorber, metal soap, antioxidant and the like can be appropriately added.

The porous sheet of the present invention comprises the above-mentioned polypropylene composition. When using the porous sheet of the present invention as a waterproof sheet, it is required to have the property of having air permeability but not water permeability,
In this case, the degree of porosity is 10 to 5 in terms of air permeability.
It is preferably in the range of 000 seconds / 100 ml, and the water resistance is preferably 50 KPa or more. The thickness of the porous sheet is not particularly limited, but is 0.02
It is preferably in the range of 1.0 mm.

In the present invention, the polypropylene composition may be prepared by mixing the above-mentioned components in a general mixer, and it is not necessary to use a high-speed stirrer.

The porous sheet can be manufactured by a method of molding the above polypropylene composition into a sheet and then stretching the sheet at least uniaxially. The method for forming the polypropylene composition into a sheet is not particularly limited, but an inflation molding method or an extrusion molding using a tee die is generally preferable. Next, the sheet-like material is generally uniaxially stretched by a roll stretching method or uniaxially stretched, and then subsequently biaxially stretched laterally by a tenter stretching machine, an air-elevation stretching machine, a mandrel stretching machine or the like, or at the same time. A method of stretching in the machine direction and the transverse direction is adopted. The stretching temperature is generally room temperature or higher and lower than or equal to the melting point of the polyethylene resin, and particularly preferably 10 ° C. lower than the melting point. The draw ratio is 1.2 to 2.
The mechanical strength is 5 times, that is, 1.2 to 2.5 times in the longitudinal (MD) direction in the case of uniaxial stretching, and in the longitudinal (MD) and transverse (TD) directions in the case of biaxial stretching. Maintains balance and strength, as well as excellent breathability and waterproofness (water resistance)
Is particularly preferred to indicate Further, generally, it is preferable that after the stretching step, heat treatment is performed under tension, and then the sheet is cooled to room temperature below the stretching temperature and taken out.

[0023]

FUNCTION AND EFFECT The composition of the present invention comprising the polyolefin resin and the inorganic filler in which the titanium oxide surface-coated with silica and / or alumina and the benzoate-based ultraviolet absorber are added together has good weather resistance, and A sheet obtained by forming the composition into a sheet and stretching the sheet is a porous sheet having good uniform whitening properties, and particularly excellent weather resistance, air permeability and waterproofness.

Since the porous sheet molded from the polyolefin composition obtained by the present invention has the above-mentioned characteristics, it is used for agricultural multi-sheets, protective films for exteriors of automobiles, ships, etc., and covers for wood and metal products. Sheet,
Windproof sheet for house wrap, waterproof sheet for civil engineering, etc.
It is suitable for applications that are mainly used outdoors for a long period of time.

[0025]

EXAMPLES Examples and comparative examples are shown below, but the present invention is not limited to these examples. The physical properties of the examples and comparative examples were measured by the methods described below.

(1) Weather resistance: A porous sheet having a thickness of 0.035 mm was cut into a test piece of 25 mm × 150 mm, and this was subjected to an accelerated weathering test using a sunshine weather meter (black panel temperature 63 ° C.). The change in tensile elongation before and after the accelerated weathering test of the test piece is measured according to JIS P8.
The time required for the retention of tensile elongation to reach 50% after the accelerated weathering test was determined according to 113, and the weatherability was evaluated according to the following criteria.

◯: Retention rate is 50% for 2000 hours or more Δ: Retention rate is 50% for 1000 hours or more 20
Less than 00 hours x: Time when retention rate becomes 50% is less than 1000 hours (2) Air permeability; Air permeability is measured according to JIS P8117 Paper and paperboard air permeability test method.

(3) Waterproofness: Water resistance was measured in accordance with the JIS L1092 textile product waterproofness test method.

Examples 1 to 3 and Comparative Examples 1 to 7 Linear low density polyethylene (hereinafter abbreviated as LLDPE. Sumitomo Chemical Co., Ltd., trade name: Sumikasen-LFA2)
01-1, MFR = 2 g / 10 min, density 0.92 g / c
m ³ ) 100 parts by weight, and heavy calcium carbonate (manufactured by Shiraishi Calcium Co., Ltd., trade name: Ryton 200-B-1)
0, average particle size 1.0 μm higher fatty acid surface-treated product) 150
Various titanium oxides shown in Table 1 and ultraviolet absorbers or weathering stabilizers shown in Table 2 were blended in parts by weight in the proportions shown in Table 3, melted in a twin-screw kneading extruder at a cylinder temperature of 190 ° C, and pelletized. To obtain a kneaded product. Using an inflation extruder, the pellets were molded into a cylindrical sheet having a thickness of 45 μm and a folding diameter of 400 mm under the conditions of a cylinder temperature of 170 ° C., a die temperature of 180 ° C. and a take-up speed of 10 m / min.
The film was stretched 1.5 times in the longitudinal direction at a temperature of 60 ° C., and further stretched 1.4 times in the transverse direction using a mandrel stretching machine to obtain a porous sheet having a thickness of 35 μm. The physical properties of the porous sheet thus obtained are collectively shown in Table 3 by the results obtained by the physical property measuring method described above.

[0030]

[Table 1]

[0031]

[Table 2]

[0032]

[Table 3]

Examples 4 to 7 and Comparative Example 8 All or part of the resin is an ethylene-α-olefin resin having a density of 0.89 g / cm ³ (hereinafter abbreviated as ULDPE. Product of Mitsui Petrochemical Co., Ltd.) First name: Tuffmer A409
0, MFR = 3.6 g / 10 min (190 ° C.), crystallinity 20%), except that the amount of heavy calcium carbonate was changed, a stretched sheet was prepared in the same manner as in Example 1, and the results were obtained. Is shown in Table 4.

[0034]

[Table 4]

Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) C08L 23/00-23/36 C08K 3/00-13/08 C08J 9/00

Claims (2)

(57) [Claims] (1) Polyolefin resin 100 parts by weight (2) Inorganic filler 50-400 parts by weight (3) Titanium oxide surface-coated with silica and / or alumina 1-20 parts by weight and (4) Benzoate-based Ultraviolet absorber A polyolefin composition comprising 0.2 to 10 parts by weight. 2. A porous sheet comprising the polyolefin composition according to claim 1.