JP2003129018A - Easily peelable adhesive for polyethylene and its structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adhesive capable of being extruded and molded and having good detachability for polyethylenes in spite of a polyolefin-based resin. SOLUTION: The easily peelable adhesive for polyethylenes comprising a polyethylene-based resin (A) of 60-70 wt.%, a crystalline polybutene resin (B) of 10-25 wt.% and low molecular weight wax (C) of 5-20 wt.% is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive having a peelable property with respect to a component such as a container or a sheet having polyethylene as an adherend and a structure thereof. More specifically, the polyethylene-based resin (A) is 60 to 70 wt%, the crystalline polybutene resin (B) is 10 to 25 wt%, and the low molecular weight wax (C) is 5 to 20 wt%, which is excellent in processability. The present invention relates to an easily peelable adhesive for polyethylene and a structure thereof.

[0002]

2. Description of the Related Art In recent years, due to the problem of industrial waste, food containers have been replaced with polystyrene or vinyl chloride from polyethylene or polypropylene, which does not generate harmful gas during combustion. In particular, a container using polyethylene or a container in which polyethylene is laminated on paper has been used. Examples thereof include a cup-shaped yogurt container obtained by extruding and laminating polyethylene on paper, a multilayer container mainly containing polyethylene for mayonnaise, ketchup, a polyethylene container such as a drip bottle, and the like.

The above-mentioned container requires an adhesive which can be safely handled without breaking the bag during transportation and has a peelable property so that even a woman or a child can open it when opening the container. As an adhesive therefor, for example, 1) a resin that is basically difficult to adhere to polyethylene (for example, polypropylene) and a resin that can adhere to polyethylene (for example,
Polyethylene, ethylene-vinyl acetate copolymer, etc.) mixed, 2) ethylene-vinyl acetate copolymer mixed with tackifier, low molecular weight wax, etc., so-called hot melt, 3) hot melt type can be extruded 4) a composition obtained by blending high-molecular-weight polybutene with low-density polyethylene proposed in JP-A-1-315443.

[0004]

However, the above-mentioned compound has various problems and is not satisfactory as an easily peelable adhesive for a polyethylene container. That is, the composition of 1) has poor processability because it mixes resins that are hardly compatible with each other, and it does not have enough flexibility to fill the step required for sealing the paper cup container, preventing liquid leakage. Not suitable for. In addition, when the adhesive strength is increased, a so-called stringing phenomenon occurs in which the adhesive is broken into streaks, and the appearance after peeling is deteriorated. The composition of 2) has sufficient fluidity and sealing strength to fill the step of the paper cup container, but requires a special coater at the time of processing, and since it has poor heat resistance, it adheres to the inside of the container during heat sealing. There is a risk of mixing the agent. Although the composition of 3) has excellent heat resistance, it has high adhesive strength with polyethylene and does not have easy peeling property. Since heat sealing at low temperature results in low adhesion, a method of sealing by limiting the operating temperature is conceivable. However, since the temperature dependence is high, there is a large variation in sealing strength, and there is a problem with credibility as a product. In the composition of 4), JI of low density polyethylene
When the melt mass flow rate (hereinafter referred to as MFR1) described in SK6922-1 is 20 g / 10 minutes or less, the peel strength is too high for a paper container or sheet laminated with polyethylene, which is one of the objects of the present invention. This causes the so-called paper peeling, which destroys the paper. In order to maintain the peelability, MFR1 of low density polyethylene is 20-
When it is 70 g / 10 minutes, the melt tension is low and the extrusion laminating processability becomes poor.

Therefore, the present invention provides a polyethylene container,
Extrusion lamination processing is possible for components such as sheets, paper containers laminated with polyethylene, multilayer containers with polyethylene adhered surface, multilayer sheets, etc., and sufficient heat seal strength to protect the contents is provided. It is an object of the present invention to provide an adhesive having the easy peeling property and its structure.

[0006]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that the polyethylene resin (A) is 60 to 70 wt% and the crystalline polybutene resin (B) is 10 to 10 wt%. 25 wt%, low molecular weight wax (C)
It has been found that an easily peelable adhesive for polyethylene characterized by comprising 5 to 20 wt% is excellent in workability and is excellent as an easily peelable adhesive for an adherend having at least one surface made of polyethylene, The present invention has been completed.

The polyethylene resin (A) used in the present invention is not limited as long as it is a polyethylene resin such as low density polyethylene, linear low density polyethylene or high density polyethylene. The blending amount of the polyethylene resin (A) is 60 to 70 wt%. If the blending amount is less than 60 wt%, the adhesiveness to the adherend polyethylene is poor,
If it exceeds 70 wt%, the adhesive strength will be too high and easy peeling will not occur. Among the polyethylene-based resins, it is preferable to use low-density polyethylene, which is a homopolymer of ethylene produced by the high-pressure method, because it has excellent workability in extrusion lamination. Further, a mixture of two or more kinds of low density polyethylene and another polyethylene resin can also be used. MFR1 when low density polyethylene is used
Is 3 to 20g considering the extrusion lamination processability.
/ 10 minutes is preferable.

The crystalline polybutene (B) used in the present invention is a homopolymer of 1-butene or a copolymer containing 50-wt% or more of 1-butene, and the compounding amount is 10%.
It is necessary to be ˜25 wt%. Mixing amount is 10w
If it is less than t%, the polyethylene component will increase and the adhesive strength with the adherend polyethylene will increase. Further, if the blending amount exceeds 25 wt%, the adhesive strength is reduced, but a so-called stringing phenomenon occurs during peeling, and the appearance after peeling is deteriorated. It is necessary to maintain the incompatibility with low density polyethylene, and the crystalline polybutene AST
Melt flow rate described in M D1238E (hereinafter M
FR2) is preferably 0.3 to 5 g / 10 minutes.

The low molecular weight wax (C) used in the present invention is low density polyethylene, high density polyethylene,
Any one or more of polypropylene and ethylene-vinyl acetate copolymer can be used. Among them, low crystalline low density polyethylene is particularly preferable from the viewpoint of maintaining proper adhesive strength and reducing the stringing phenomenon. 5 to 2
It is necessary to be 0 wt%. If the blending amount is less than 5 wt%, a stringing phenomenon occurs at the time of peeling, and if it exceeds 20 wt%, the workability is deteriorated. Low molecular weight wax (C)
The molecular weight of is preferably 4000 to 10,000 by the viscosity method in view of compatibility and its effect.

The adhesive of the present invention may optionally contain an antioxidant, a lubricant, an antiblocking agent, an antistatic agent and the like which are generally used in packaging materials.

The adhesive of the present invention is prepared by preparing a polyethylene resin (A), a crystalline polybutene resin (B), a low molecular weight wax (C) and, if necessary, a lubricant, an antioxidant,
An antistatic agent is dry blended in a predetermined amount, melt-kneaded with a single-screw or twin-screw extruder, extruded into a strand with a diameter of about 2 to 3 mm, cooled and solidified, and then cut with a rotary blade, and a pelletized adhesive Can be obtained.

When the present adhesive is used, a laminate with another film having heat resistance higher than that of polyethylene such as polyester film or polyamide film can be preferably used as an adherend. The adhesive film and the laminate are produced, for example, by using the pelletized adhesive as described above, a method usually used for molding a polyethylene resin, that is, a single layer film by cast molding or inflation molding, or Density polyethylene, linear low-density polyethylene, and high-density polyethylene can be formed into a multilayer film with polyester, polyamide or the like via an adhesive resin. In the case of extrusion lamination, it can be laminated with various plastic films, aluminum foils, etc. by applying an anchor coating agent (AC agent) to the substrate in advance or performing ozone treatment during processing. In addition, it is also possible to directly extrude and laminate a substrate on which a polyethylene resin has been laminated in advance. In addition, a multilayer film is formed by coextrusion with polyethylene, polypropylene, etc., and then laminated by stretching or unstretched film such as a polyester film, a polyamide film, a polypropylene film or the like, which is a base material, by dry lamination or sand lamination. You can get things. For example, an isocyanate-based anchor coating agent (Citabond T12 manufactured by Nippon Soda Co., Ltd.) is applied to a biaxially stretched 12 μm thick polyester film.
0) was used to laminate low-density polyethylene (PETROSEN 213 manufactured by Tosoh Corporation) in advance, and the adhesive was extruded and laminated thereon by 10 μm, and a biaxially stretched 15 μm-thick polyamide film and 3
This adhesive film cast to a thickness of 0 μm was used as a polyester adhesive (Daika Seika Seika Bond E26
Dry-laminated in 3), or a 12 μm-thick polyester film and aluminum vapor-deposited 12 μm
A film obtained by sticking the polyester film of 1. to the film coated with an isocyanate-based anchor coating agent (Citabond T120 manufactured by Nippon Soda Co., Ltd.) and the adhesive film of 30 μm, a low-density polyethylene (Petrosene 213 manufactured by Tosoh Co., Ltd.) Examples include sandwich-laminated products by extrusion.

In the structure in which the laminated film and the adherend are heat-bonded, as the adherend having at least one surface made of polyethylene, a polyethylene single layer such as a yogurt which is a polyethylene laminated container or a paper cup for ice cream is used. Blow container such as detergent container, infusion bag, etc.
Examples include multi-layer blow containers such as ketchup and mayonnaise containers, but at least the adherend surface should be polyethylene, and packaging materials with barrier properties such as vinylidene chloride, ethylene-vinyl alcohol copolymer or aluminum in the composition. It may be a container or sheet in which is used.

[0014]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples.

Example 1 70 wt% of low density polyethylene (Petrosene 213 manufactured by Tosoh Corporation) having an MFR1 of 8 g / 10 min, MFR2
Is 1 g / 10 minutes of polybutene (Tufmer BL3110 manufactured by Mitsui Chemicals, Inc.) 19.9 wt%, viscosity method molecular weight 6
400 low molecular weight wax (Mitsui Chemicals Co., Ltd. high wax NL800) 10 wt% and stearic acid amide 0.1 wt% were added as a lubricant, melt-kneaded with a 40 mm single-screw extruder, and extruded into a strand shape with a diameter of 3 mm. ,
After cooling and solidifying, it was cut with a rotary blade to obtain a pellet-shaped adhesive. An isocyanate-based anchor coating agent (Citabond T120 manufactured by Nippon Soda Co., Ltd.) was applied to a polyester film (12 μm) that had been biaxially stretched in advance using this compound.
Was used and extrusion-laminated to a thickness of 10 μm on the low-density polyethylene surface of the film obtained by laminating 25 μm of low-density polyethylene (Petrosene 213 manufactured by Tosoh Corporation) to obtain a laminate. This laminated material is applied to cardboard with low-density polyethylene (PETROSEN 214 manufactured by Tosoh Corporation).
Is laminated so that it contacts the low-density polyethylene side of the 40 μm laminated sheet,
Heat bonding was performed under the conditions of 0 ° C., 0.2 MPa, and 1 second. This structure was cut into a width of 15 mm and its peel strength was measured. The results are shown in Table 1.

Example 2 The low-molecular-weight wax used in Example 1 was prepared by viscometric method with a molecular weight of 24.
Samples for peeling test were obtained in the same manner except that the wax No. 00 (NL100 manufactured by Mitsui Chemicals, Inc.) was used.

Example 3 The low density polyethylene, polybutene and low molecular weight wax used in Example 1 were 79.9 wt% and 10 wt, respectively.
%, 10 wt%, and a peel test sample was obtained in the same manner.

Example 4 The low density polyethylene, polybutene and low molecular weight wax used in Example 1 were 60 wt% and 19.9 wt, respectively.
%, 20 wt% and a peel test sample was obtained in the same manner.

Example 5 The polybutene used in Example 1 was replaced with polybutene having an MFR2 of 2 g / 10 min (Tufmer BL02 manufactured by Mitsui Chemicals, Inc.).
A sample for peeling test was obtained in the same manner as in 7).

Comparative Example 1 A sample for peeling test was obtained in the same manner as in Example 1 except that the low density polyethylene was 80 wt% and the polybutene was 19.9 wt%, and the low molecular weight wax was not used. Although the extrusion laminating processability was good, material destruction (paper peeling) occurred during peeling.

Comparative Example 2 A peeling test sample was obtained in the same manner as in Example 1 except that the low density polyethylene was 60 wt%, the polybutene was 29.9 wt% and the low molecular weight wax was 10 wt%. Although the extrusion laminating processability was good, a stringing phenomenon occurred during peeling.

Comparative Example 3 80 wt% of low-density polyethylene (Petrosene 208 manufactured by Tosoh Corporation) having MFR1 of 45, 19.9 wt% of polybutene used in Example 1, and 0.1 wt% of lubricant,
A sample for peel test was obtained in the same manner as in Example 1. This formulation was a sample in which the melt film was unstable during laminating, and the thickness varied greatly.

[0023]

[Table 1]

As described above, the adhesive of the present invention is extrudable, can be used as an easily peelable adhesive with polyethylene even though it is a polyolefin resin, and a container having at least one surface made of polyethylene, It is useful as an adhesive for sheets and the like.

The multi-layer structure using the adhesive of the present invention as an adhesive layer can be cohesively peeled off from the polyethylene to be adhered and have a stable adhesive performance not affected by the sealing temperature.

Continued front page    F-term (reference) 4F100 AJ11A AK04A AK04B AK04C                       AK05A AK06A AK07A AK09A                       AK68A AL05A BA02 BA03                       BA06 BA07 BA10A BA10B                       BA10C EC18A GB90 JA06A                       JA07A JA09A JA11A JL14                       JL14A YY00A                 4J040 BA182 DA011 DA052 DA102                       DA142 LA08 MA11

Claims (5)

[Claims] 1. A polyethylene resin (A) 60 to 70 wt.
%, Crystalline polybutene resin (B) 10 to 25 wt%,
An easily peelable adhesive for polyethylene, characterized by comprising 5 to 20 wt% of a low molecular weight wax (C). 2. The polyethylene resin (A) is a low density polyethylene produced by a high pressure method, and has a JIS K69 value.
22-1 has a melt mass flow rate of 3
The easily peelable adhesive for polyethylene according to claim 1, wherein the adhesive is about 20 g / 10 minutes. 3. ASTM of crystalline polybutene resin (B)
The melt flow rate described in D1238E is 0.3 to
It is 5 g / 10 minutes, The easy peeling adhesive agent for polyethylene of Claim 1 characterized by the above-mentioned. 4. The low molecular weight wax (C) is one or more of low density polyethylene, high density polyethylene, polypropylene, and ethylene-vinyl acetate copolymer, and has a molecular weight of 2000 to 10,000 by a viscosity method. The easily peelable adhesive for polyethylene according to claim 1, which is characterized. 5. A structure characterized in that the easily peelable adhesive for polyethylene according to any one of claims 1 to 4 is used as a heat-bonding surface, and at least one surface of an adherend is polyethylene.