JPH11291418A - Transparent cloth sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a transparent sheet being light in weight, intensive in strength, and having visible inside by laminating an ethylene.α-olefin copolymeric layer on one or both surfaces of a cloth of an ethylene.α-olefinic composition of a specific quantity manufactured in use of a metallocene catalyst having specific properties and a high density resin composition having a specific density. SOLUTION: An ethylene.α-olefin copolymer is manufactured by the use of a metallocene catalyst having properties of a melt-flow rate of 0.3-30 g/10 mn, a density of 0.90-0.94 g/cm<3> , a minimum peak temperature of 80-125 deg.C by DSC, a molecular weight distribution (Mw/Nn) of 1.8-3.5, and a melt tension of 0.5-4 g. After that, this is woven or knitted by 50-90 wt.% by the use of flat yarn as warp and weft, which is made of resin composition consisting of 10-50 wt.% high density polyethylene with a density of 0.945 g/cm<3> so as to form cloth, and finally, an ethylene.α-olefin copolymeric layer is laminated on one surface or both surfaces thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to various kinds of covers,
The present invention relates to a transparent cloth sheet used for packaging bags, agricultural sheets, etc., and whose contents can be easily visually recognized.

[0002]

2. Description of the Related Art Hitherto, as a cloth sheet used for covers, packaging bags, agricultural sheets and the like, a large number of laminated sheets having a resin layer provided on one or both sides of a fiber cloth are known. Sheets for these applications include high strength that can withstand the tensile force during sheet expansion and the gravitational force of the contents of the package, and the flexibility and ease of handling as covers and agricultural sheets that fit well with the object. In addition, transparency or the like that allows the contents to be covered or packaged to be visually recognized from the outside is required. As a sheet for such an application, a cross sheet obtained by laminating a film made of polyvinyl chloride or the like on a cloth made of nylon or polyester fibers is often used.
These cloth sheets are made of multifilaments such as nylon and polyester fibers to maintain high strength and flexibility, and form a laminated sheet by laminating highly transparent polyvinyl chloride. Multifilaments such as polyester and polyester have a problem that light scattering and refraction often reduce transparency.
Polyvinyl chloride has not been satisfactory because of problems such as bleeding of plasticizer, generation of toxic gas during incineration, and poor workability due to large specific gravity.

[0005] As an alternative to these, a polyolefin resin is frequently used in that it is lightweight, has excellent moldability, has no problem of toxic gas generation, and is inexpensive. A cloth sheet obtained by laminating low-density polyethylene, linear low-density polyethylene, low-melting polypropylene or the like on one or both sides of a cloth obtained by using the above method is well known. However, these cloth sheets are inferior in transparency and flexibility, and when used for applications such as covers, lack in visibility of contents, and have insufficient fit to covered materials, etc., so that covers, packaging bags, It was not satisfactory for applications such as agricultural sheets.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a lightweight, high-strength, highly flexible, and transparent cross sheet which allows the coated contents to be easily viewed. Aim.

[0005]

SUMMARY OF THE INVENTION In order to technically solve the above-mentioned problems, the present invention provides an ethylene α-catalyst produced by using a metallocene catalyst having the following properties (1) to (5).
50 to 90% by weight of the olefin copolymer and a density of 0.9
One or both sides of a cloth formed by weaving and knitting a flat yarn formed using a resin composition comprising 10 to 50% by weight of a high-density polyethylene of 45 g / cm ³ or more on a weft yarn, the above-mentioned ethylene-α- An object of the present invention is to provide a transparent cloth sheet formed by laminating olefin copolymer layers and to solve the above-mentioned problems. (1) Melt flow rate is 0.1 to 30 g / 10 mi
n. (2) Density 0.90 to 0.94 g / cm ³ (3) Maximum peak temperature (Tm) by DSC of 80 to 1
25 ° C (4) Molecular weight distribution (Mw / Mn) is 1.8 to 3.5 (5) Melt tension is 0.5 to 4 g

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The ethylene / α-olefin copolymer produced by using the metallocene catalyst used in the present invention refers to ethylene having the following properties (1) to (5) and ethylene having 3 or more carbon atoms. Ethylene consisting of
It is an α-olefin copolymer.

(1) Melt flow rate (hereinafter referred to as MFR)
Is abbreviated as 0.1 to 30 g / 10 min., But 0.1 to 10 g / 10 m for flat yarn formation.
in., more preferably 0.5 to 5 g / 10 min. If the MFR is less than 0.1 g / 10 min., The molding processability is inferior, and if it exceeds 10 g / 10 min., High strength cannot be obtained even if the stretching ratio is increased. 5-30 g / 10m for lamination on cloth
in., more preferably 10 to 20 g / 10 min. If the MFR is less than 5 g / 10 min., The molding processability for lamination is inferior, and if it exceeds 30 g / 10 min., The strength is undesirably reduced.

(2) Density is 0.90 to 0.94 g / c
m ³ , preferably 0.91 to 0.93 g / cm ³ .
If the density is less than 0.90 g / cm ³ , the stretchability is inferior and the strength is insufficient, and if it exceeds 0.94 g / cm ³ , the flexibility is inferior, which is not preferable.

(3) The maximum peak temperature (T
m) is from 80 to 125 ° C, preferably from 90 to 120 ° C. If the maximum peak temperature (Tm) by DSC is less than 80 ° C, the difference from the stretching temperature is too small, and if it exceeds 125 ° C, the optimal stretching temperature is too high, which is not preferable.

(4) The molecular weight distribution (Mw / Mn) is 1.8
To 3.5, preferably 2.2 to 3.0. Mw / Mn
If it is less than 1.8, the moldability is poor, and if it is 3.5 or more, the stretchability is poor, which is not preferable.

(5) a melt tension of 0.5 to 4 g,
Preferably it is 1.0 to 3 g. Melt tension is 0.
If it is less than 5 g, the molding stability of the flat yarn is inferior and 4 g
Those exceeding the above are difficult to manufacture.

The process for producing the ethylene / α-olefin copolymer is described in JP-A-58-19309 and JP-A-5-19309.
JP-A-9-95292, JP-A-60-35005, JP-A-60-35006, JP-A-60-35
No. 007, JP-A-60-35008, JP-A-60-35009, etc., by copolymerizing ethylene and an α-olefin using a metallocene catalyst.

The metallocene catalyst is, for example, bis (cyclopentadienyl) zirconium dichloride (Cp
2ZrCl2) and a catalyst composed of a co-catalyst such as a metallocene compound represented by methylaluminoxane (MAO).

The metallocene compound includes a ligand having a cyclopentadienyl ring, a substituted cyclopentadienyl ring substituted with an alkyl group, an indenyl ring, and the like, and hydrogen, a halogen atom, an alkyl group, and the like having zirconium, titanium, or the like. Compounds bonded to transition metals such as hafnium, and specific examples thereof include bis (cyclopentadienyl) zirconium dichloride, bis (methylcyclopentadienyl) zirconium dichloride, and bis (ethylcyclopentadienyl) zirconium dichloride. , Bis (cyclopentadienyl) titanium dichloride, bis (methylcyclopentadienyl) titanium dichloride, bis (ethylcyclopentadienyl) titanium dichloride, bis (cyclopentadienyl) hafnium dichloride, bis (methyl) Cyclopentadienyl) hafnium dichloride, bis (ethyl cyclopentadienyl)
Hafnium dichloride and the like can be mentioned.

An aluminoxane or boron compound can be used as a co-catalyst for the metallocene compound. As the aluminoxane, usually, a chain or cyclic aluminoxane produced by bringing a trialkylaluminum into contact with water is preferable. Representative methylaluminoxane (MAO) can be obtained by reacting trimethylaluminum with water. Further, the metallocene catalyst can be used by being supported on an inorganic oxide or the like.

The polymerization method is not particularly limited, and it is produced by a high pressure method, a solution method, a gas phase method, a slurry method or the like.

The α-olefin to be copolymerized with ethylene is an α-olefin having 3 or more carbon atoms, such as propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene. And the like. Of these, one or two or more α-olefins are
0%, preferably 10-30% by weight of ethylene 5
It may be copolymerized with 0 to 95% by weight, preferably 70 to 90% by weight.

The high-density polyethylene used in the present invention has a density of 0.945 g / cm ³ or more and is formed by a known process such as a slurry method, a solution method or a gas phase method using a known Ziegler catalyst or the like. In the produced ethylene homopolymer or copolymer of ethylene and α-olefin having 3 to 12 carbon atoms and a mixture thereof, specific α
Examples of the olefin include propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-dodecene, and the like. Its density is 0.945-0.9
The range is preferably 80 g / cm ³ and the MFR is 0.1 to 5
0 g / 10 min., Preferably 0.5 to 30 g / 10 m
It is better to select from the range of in.

The mixing ratio of the ethylene / α-olefin copolymer produced using the metallocene catalyst and the high-density polyethylene is 50-90% by weight of the ethylene / α-olefin copolymer and 50-90% by weight. 10
50% by weight, preferably 60 to 80% by weight of the ethylene / α-olefin copolymer, and 20 to 40% by weight of the high-density polyethylene. That is, when the high-density polyethylene exceeds 50% by weight, the transparency is lowered, and the flexibility is insufficient, so that the fit is poor when used as covers, and when it is less than 10% by weight, the strength is inferior.

In the present invention, a flat yarn is formed by melt-extruding a mixture of the above-mentioned ethylene / α-olefin copolymer and high-density polyethylene as a raw material by using an extruder, and forming a film by a T-die method or an inflation method. After the film is cooled and solidified, the film is slit, stretched by reheating to a temperature at which stretching is possible, and then heat-treated to form a flat yarn. Among these, the T-die method which is excellent in transparency is preferable. The stretching temperature here is preferably 70 to 120 ° C., more preferably 8 to 120 ° C.
0 to 110 degrees. If the stretching temperature is lower than 70 ° C., whitening occurs or the stretchability decreases, and if it exceeds 120 ° C., the stretchability decreases, which is not preferable. The stretching ratio is preferably 5 to 12
And more preferably 8 to 10 times. If the draw ratio is less than 5 times, the strength becomes insufficient, and if it is more than 12 times, yarn cracks occur, which is not preferable. As a heating method at the time of stretching, any method such as a hot roll method, a hot plate method, an infrared method, and a hot air method can be adopted. The flat yarn preferably has a single yarn fineness of 100 to 3000 denier (hereinafter, d
), And more preferably 500 to 2,000 d.

The above-described flat yarn is woven and knitted using warp yarns to form a cloth. Weaving methods include circular looms, sulzer looms, water jet looms,
It can be woven using a known loom such as an air jet loom, and various shapes such as plain weave, twill weave and leno weave are applied as the weave structure. The knitting method may be either horizontal knitting or vertical knitting, and specific examples include tricot knitting, Milanese knitting, and Russell knitting.

In the present invention, a cloth sheet is formed by providing an ethylene / α-olefin copolymer layer produced using the metallocene catalyst on one or both sides of the cloth. Examples of the method for laminating the ethylene / α-olefin copolymer layer include a dry laminating method and a calendering laminating method, but the extrusion laminating method is preferably used from the viewpoint of high-speed and stable productivity. The thickness of the resin layer provided is preferably 20 to 100 μm on one side,
0 to 60 μm is more preferable. If it is less than 20 μm, the welding strength in post-processing becomes insufficient, and if it exceeds 100 μm, flexibility is lost, which is not preferable.

In forming the ethylene / α-olefin copolymer layer, other polyethylene resins may be used in combination without departing from the spirit of the present invention. As other polyethylene resins, low-density polyethylene by a high-pressure radical method usually used for extrusion lamination,
Examples include linear low-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-alkyl acrylate copolymer, and the like.

The polyethylene resin used in the present invention includes an antioxidant, a lubricant, an ultraviolet absorber, a light stabilizer, a flame retardant, an antistatic agent, a pigment within a range not departing from the gist of the present invention depending on the purpose of use. Further, additives such as an inorganic filler, an organic filler, a crosslinking agent, a foaming agent, and a nucleating agent may be blended.

[0025]

EXAMPLES Test method 1. Maximum peak temperature (Tm) by DSC: JISK7
121 molecular weight distribution (Mw / Mn): GPC method 3. Melt tension: Measured by a melt tension tester manufactured by Toyo Seiki Co., Ltd. (measuring temperature 190 ° C.) 4. Tensile strength: JISZ1651 5. Tensile elongation: JISZ1651 6. Tear strength: JISZ1651 compliant 7. Haze: JISK7105 compliant 8. Bend softness: JISL1096 compliant 9. Puncture resistance: A sheet is fixed to a wooden frame having an opening of 82 mm, and 3/4 inch at the center. A jig provided with a hemispherical tip was pierced at a speed of 500 mm / min., And the maximum load until the jig penetrated was indicated in kgf.

Comparative Example 1: High-density polyethylene (MFR =
1.0 g / 10 min. , Density = 0.961 g / cm ³ ,
(Tm = 132 ° C.), a film is formed by a T-die method, cooled, slit, and stretched at a stretching temperature of 115 ° C., an annealing temperature of 110 ° C. and a hot plate contact stretching method at 6.8-fold stretching and a fineness of 1000 d. Got a flat yarn. Using this flat yarn for warp yarn, the driving density is 8 × 8 /
A plain weave cloth is formed in inches, and low-density polyethylene (MFR = 12.0 g / 10 min.,
(Density = 0.916 g / cm ³ , Tm = 105 ° C) by extrusion lamination at a melt extrusion temperature of 290 ° C and a thickness of 30 µm each.
m, and a cross sheet was obtained. The obtained cross sheet was inferior in transparency and flexibility, and also poor in puncture resistance, and was not preferable for uses such as covers, packaging bags, agricultural sheets and the like. Table 1 shows the evaluation results.

Example 1: Metallocene-catalyzed ethylene / α-olefin copolymer (MFR = 2.5 g / 10 m
in., density = 0.926 g / cm ³ , Tm = 121 ° C.,
Mw / Mn = 2.5) 70% by weight and high-density polyethylene (MFR = 1.0 g / 10 min., Density = 0.961 g)
/ Cm ³ , Tm = 132 ° C.), a film was formed by a T-die method using a mixture with 30% by weight, cooled, slit, stretched at 115 ° C., annealed at 110 ° C., and subjected to hot plate contact stretching. By drawing 6.8 times, a flat yarn having a fineness of 1000 d was obtained. This flat yarn is used as a warp yarn to form a plain weave cloth at a driving density of 8 × 8 yarns / inch, and an ethylene / α-olefin copolymer produced using a metallocene catalyst on both sides of the cloth (MFR =
19 g / 10 min., Density = 0.915 g / cm ³ , T
m = 101 ° C., Mw / Mn = 2.8)
A cross sheet was obtained by providing a laminate layer having a thickness of 30 μm each at 70 ° C. by an extrusion lamination method. The obtained cross sheet was excellent in transparency, flexibility and mechanical properties, and was suitably used for applications such as covers, packaging bags and agricultural sheets. Table 1 shows the evaluation results.

COMPARATIVE EXAMPLE 2 As a flat yarn, an ethylene / α-olefin copolymer (M
FR = 2.5 g / 10 min., Density = 0.926 g / c
m ³ , Tm = 121 ° C., Mw / Mn = 2.5) 40% by weight and high-density polyethylene (MFR = 1.0 g / 10 mi)
n. , Density = 0.961 g / cm ³ , Tm = 132 ° C.)
The same procedure as in Example 1 was performed except that a mixture with 60% by weight was used. Although the obtained cross sheet had excellent mechanical properties, it was inferior in transparency and flexibility, and was insufficient for uses such as covers, packaging bags, agricultural sheets and the like. Table 1 shows the evaluation results.

Comparative Example 3: Low density polyethylene (MFR = 12.0 g / 1) was applied to both sides of the cloth used in Example 1.
0 min., Density = 0.916 g / cm ³ , Tm = 105
C) at a melt extrusion temperature of 290 ° C. by an extrusion lamination method to provide a 30 μm-thick laminate layer to obtain a cross sheet. The resulting cross sheet had poor mechanical properties due to thermal degradation during lamination, and was insufficient for uses such as covers, packaging bags, and agricultural sheets. Table 1 shows the evaluation results.

[0030]

[Table 1]

[0031]

As described above, according to the present invention, a flat yarn made of a resin composition containing a specific ethylene / α-olefin copolymer and a high-density polyethylene in a specific ratio is used as a warp yarn. A cross sheet in which a specific ethylene / α-olefin copolymer layer is provided on one or both sides of the prepared cloth, which is excellent in flat yarn molding stability, lightweight, high-strength, especially excellent in piercing resistance, and flexible It was possible to obtain a transparent cloth sheet having excellent properties and excellent transparency so that the coated contents could be easily visually recognized.

Claims (1)

[Claims] 1. An ethylene / α-olefin copolymer produced using a metallocene catalyst having the following properties (1) to (5): 50 to 90% by weight and a density of 0.945 g
/ Cm ³ or more of a high-density polyethylene of 10 to 50% by weight. A transparent cloth sheet obtained by laminating copolymer layers. (1) Melt flow rate is 0.1 to 30 g / 10 mi
n. (2) Density 0.90 to 0.94 g / cm ³ (3) Maximum peak temperature (Tm) by DSC of 80 to 1
25 ° C (4) Molecular weight distribution (Mw / Mn) is 1.8 to 3.5 (5) Melt tension is 0.5 to 4 g