JPS58109547A - Ethylene polymer composition for extrusion coating - Google Patents

Abstract

PURPOSE:To provide the titled composition improved in extrusion laminating processability without determined to mechanical properties or heat sealability, comprising a low pressure ethylene/alpha-olefin copolymer and high-pressure polyethylene. CONSTITUTION:20-80wt% low-pressure ethylene/alpha-olefin copolymer (A) with density of 0.910-0.940g/cc and melt index of 1.0-20g/10min and 80-20pts.wt. high-pressure polyethylene (B) with density of 0.910-0.930g/cc and melt index of 2.0-15g/10min are compounded to obtain an ethylene polymer composition for extrusion coating. By blending the polymer B, the reduction in the load of an extruder, the stabilization of film formation and the improvement in high speed draw-down property can be carried out without dertemined to mechanical properties or heat sealability of the polymer A.

Description

[Detailed description of the invention] It is related to body composition.

Melt index y obtained by radical polymerization under high pressure
．． 2. 0 to 1 5. Polyethylene with a density of 0 f710 min and a density of 0.910 to 1930 f can be used for paper, plastic film, etc. Non-woven fabric. It is generally well known that extrusion lamination is applied to metal foils and the like.

The reason why high-pressure polyethylene is used for extrusion lamination is that it can be easily extruded using a regular extruder, a very stable molten film can be obtained using a T-die, and the molten film has sufficient drawdown properties. This is because the slanted surface has good adhesion to the base material.

However, products made by extrusion lamination using voltage-processed polyethylene usually have a coating thickness of 15 to 40μ, but the heat sealing strength of the polyethylene layer is insufficient for applications where the weight of the contents is relatively large compared to the volume of the packaging material, such as water packaging. It cannot be said that it is sufficient.

In order to improve these drawbacks, ethylene-vinyl acetate resin is widely used in extrusion coatings. However, ethylene-vinyl acetate resin lacks thermal stability at high temperatures, and the extrusion mesh temperature exceeds 250°C. It cannot be extruded and laminated at high temperatures because it causes thermal decomposition. For this reason, commonly used anchor coating agents, such as
Even if polyethylinimine, organic titanate, urethane, etc. are used, the adhesion to the substrate is worse than that of high-pressure polyethylene. Therefore, when extrusion laminating ethylene-vinyl acetate resin, a double lamination method is used in which high-pressure polyethylene is extrusion coated to improve adhesion to the base material, and then ethylene-vinyl acetate resin is extruded onto that coating layer. has been taken.

It is necessary to use complicated processing methods. Furthermore, the extrusion temperature of the ethylene-vinyl acetate resin must be kept at 250° C. or lower, which results in poor drawdown properties during extrusion lamination, making it difficult to reduce the coating thickness.

On the other hand, an ethylene-α olefin copolymer that is ionically polymerized using a low pressure method is known as a polyethylene that has high heat seal strength and impact strength that is equal to or higher than that of ethylene-vinyl resin.

However, compared to high-pressure polyethylene of the same melt index, this ethylene-α-olefin copolymer has
The shear viscosity in the extruder is high and extrusion processability is extremely poor. In addition, the elongational viscosity is very low and the melt tension is low.

For this reason, in extrusion lamination processing, a high load is placed on the extruder, and the film formation property with the T-die is unstable, that is, the stability of the edge portion is deteriorated, which is a decisive drawback. When high temperature processing is performed to lower the melt shear viscosity and improve extrusion processability, the stability of the molten film extruded from the T-die becomes increasingly poor. In many cases, extrusion processing at temperatures above 290° C. deteriorates the stability of the molten film, exhibits variations in thickness and neck-in, and makes uniform extrusion coating difficult.

The present invention reduces the load on the extruder without impairing the mechanical properties or heat sealability of an ethylene-α olefin copolymer that is ionically polymerized using a low-pressure method.

As a result of various studies aimed at improving cavity forming stability, high-speed drawdown property (hereinafter referred to as extrusion lamination processability), it was discovered that the objective could be achieved by blending 20 to 80 times high-pressure polyethylene. It is something.

The ethylene-α olefin copolymer according to the present invention is
It is a copolymer of ethylene and α-olefin having 4 to 10 carbon atoms. α-olefin toha, specifically 1-butene, 1
-Pentene, 1-hexene.

4-methyl-1-pentene, 1-octene, 1-decene or a mixture thereof.

The melt index of the low-pressure ethylene-α olefin copolymer is within the range of 1.0 to 20r710 minutes, and is optimally 2.0 to 409710 minutes.

If the melt index is less than 1.0, the melt shear viscosity will be high, impairing extrusion lamination processability, and if it exceeds 20, it will be 51i.
:! li! Stability deteriorates.

Further, the density of the low-pressure ethylene-α olefin copolymer is suitably in the range of 0.910 to 0.940t7Cr. The density is determined by the amount of α-olefin to be copolymerized, and the density range is appropriately selected depending on the application.

On the other hand, high-pressure polyvinyl chiller, which is blended for the purpose of improving extrusion lamination processability, has a melt index of 2.
0 to 15f/10 min, preferably 3.0 to aO
The one with P/10 minutes is excellent in terms of workability balance. Also, the density range is 0910 to 0.930 f/
cC is suitable, but like the low-pressure ethylene-α olefin copolymer, it is appropriately selected depending on the application. The proportion of high pressure polyethylene blended with the low pressure ethylene-α olefin copolymer is 20 to 80%, preferably 30 to 70%.

If the low-pressure ethylene-α-olefin copolymer exceeds 80 mm, the melt shear viscosity will not be reduced sufficiently, and the lamination processability will not be improved. Strong electricity ↑ The heat sealability has not been sufficiently improved, and it is not suitable for packaging materials with large contents such as packaging for water products.

This patent will be shown below with Examples and Comparative Examples, but this patent is not restricted by these K.

Example 1 Low pressure ethylene-α olefin copolymer (density 2/gloss,
Mix pellets with melt index 50r and 25mm in a V-blender, and prepare -I with a screw diameter of 90φ.
:1 (It was extruded from a T-die while being melt-kneaded in an extruder. A straight manifold type T-die with a lip opening length of 760 m and a slit width of 0.7 mm was attached to the tip of the extruder.

The width of the composition extruded from the T-die is 3.
The temperature was 10° C., the discharge amount was 104 K9 Ar, and the drive load current of the extruder at that time was 260 A.

Composition f! formed into a film by T-dice! 5521mN
Drawdown properties were measured while extrusion coating was applied to kraft paper using a laminator.

The stability of the melt extruded from the T-die is good, there is no variation in thickness or neck-in, and the drawdown of film formation is 1
It was 52 Vmin.

Examples 2 to 3 The drawdown properties of molten films were measured in the same manner as in Example 1 by changing the mixture composition of the low-pressure ethylene-α-olefin copolymer and the high-pressure polyethylene. Table 1 shows the results of the results.

In all cases, the results of pancreatic development using T-Dice were good.

Comparative Example 1 In the same manner as in Example 1, extrusion was carried out using only the low-pressure ethylene-α-olefin copolymer, and the drawdown properties of the molten film were measured. The film formation stability was poor and lamination processing was difficult.

Comparative Example 2 The same method as in Example 1 was used. Polyethylene (density α924 t/ω, melt index 3)
．． The extrusion processability of a 0 P 10 knee 10 wt composition was measured.

As a result, F! i. Lamination is difficult due to poor film stability.

Example 4 75 wt% and high pressure polyethylene (density 0.917y
/cc, melt index B, O9710m1n
) The lamination processability of the 25 wt % mixture was measured in the same manner as in Example 1.

The discharge amount at that time was 106 K9/l-1r, and the extruder load was 250 A at a screw rotation speed of 60 rpm.

The stability of the molten film extruded from the T-die is good, there is no variation in thickness or neck-in, and the drawdown property is 238.
Comparative Example 3 Only the low-pressure ethylene-α-olefin copolymer of Comparative Example 1 was measured for extrusion processability at a resin molding temperature of 290°C.

As a result, the extrusion load was large and the film formation stability was poor, making measurement difficult.

Comparative Example 4 Only high-pressure polyethylene (density 0.917 f/ω, melt index aO 110 min) was used at a resin temperature of 290°C.
Extrusion processability was measured.

The extruder drive load is 2 at a screw rotation speed of 120 rpm.
The discharge amount was 10A and the discharge amount was 206 K9/Hr. The molten film is stable without surging, and there is no neck-in fluctuation. 1q o Vmin'! I was able to pick it up.

Comparative Example 5 Low-pressure ethylene-α olefin copolymer (density 2.70, 919 f/CC, Melt Indef 221 companies ÷
9/10m1n) 10 wt% and high pressure method IJI
L/7 (density 0.917 t/(1:,, melt index aO9/ 10m1n) 90 wt% mixture ffi flip Monowoki MW /'i7. Ice2
Extrusion processability was measured at 90°C.

The extruder drive load was 240 A at a screw rotation speed of 120 r'pm. The melting state was stable without surging, and it was possible to draw up to 180 Vmin.

Example 5 Low pressure Tirin-α olefin copolymer (density 2.70, 919 f/CC, melt index ≠≠ fl
/10m1n) and room pressure polyethylene (density 0.917
゜melt index 8.0 t710mln'') were mixed in a ■-blender in the proportions shown in Table 2, and extruded from a T-die using the same extruder as in Example 1 to form a 15μ thick nylon base material. (manufactured by Toyobo Co., Ltd.) was extrusion coated with 30μ of the blend resin.

Nylon pile material was coated with the following anchor coating agent using a conventional method, and the solvent was removed by drying in an arch dryer at 90°C.This anchor coating agent coating was performed as a series of systems using a laminator. This is the normal method.

Anchor coating agent blended Titabond T-120 (manufactured by Nippon Soda) 60 parts Titabond T-hardening agent CI) 6 parts ethyl acetate
934 parts extrusion laminated fC2
1i! The laminated product No. 1 was aged for 24 hours at a room temperature of 40° C. and a humidity of 60 m, and the adhesive strength, heat seal strength, and compression bag tear strength were measured. Table 2 shows the measurement results.

Table 2 *1 Measurement conditions Schopper tensile tester tensile speed Ij 300 WrIn/min*2 Heat sealing conditions Cool pressure 1.0Kg/cm' Sealing time 1. OsθC Tensile condition 300/min *3 Make a loan with a sample shape of 140 x 140 (m), add 160 ml of water,
Close your mouth.

Same conditions as each seal *2 Heat seal temperature: 160℃ Compression speed: 50 cod/min The following can be said from the measurement results of product physical properties.

The adhesive strength of high-pressure polyethylene alone is higher than that of a mixture of low-pressure ethylene-α-olefin copolymer and high-pressure polyethylene [2]. However, if the adhesive strength is 500 f/15 tx or more, there will be no defects in practical use.

The mixture composition ratio of low-pressure θ ethylene-α olefin copolymer and high-pressure polyethylene is 75 to 25 wt% (sample AI, 2.3), which has heat seal strength and compression bag tearing strength that are higher than that of high-pressure polyethylene alone. On the other hand, even in a mixed composition, when the composition of high-pressure polyethylene exceeds 90 wt% (sample I6.5), the heat seal strength and compression bag tearing strength are almost the same as that of high-pressure polyethylene alone. They become equivalent and lose their superiority as a mixed composition.

Patent Dekijin Toyo Soda Kogyo Co., Ltd.

Claims (1)

[Claims] 1) FiO, 910 to [194 o'y/cc,
, +' Root index 1.0 and 20? /
10mln low-pressure ethylene-α-olein copolymer 2
0 to 80% by weight and density 0. '910 strength 0.93
0°melt index 2.0 to 159/10m1
Ethyline polymer set for extrusion coating consisting of 20 to 80 wt % of high-pressure polyethylene of n, an acid compound.