JPS62119248A - Adhesive polyethylene composition - Google Patents

Abstract

PURPOSE:A composition, obtained by incorporating a specific modified polyethylene with (modified) high-density polyethylene and (modified) polyisobutylene and capable of exhibiting improved adhesive force and mechanical strength even when lowering the preheating temperature of an adherend. CONSTITUTION:An adhesive polyethylene composition obtained by incorporating (A) 10-90wt% modified polyethylene prepared by reacting linear low-density polyethylene having 7-50g/10min melt index with an unsaturated carboxylic acid (derivative) with (B) 0-85wt% unmodified polyethylene (except high-density polyethylene), (C) 5-50wt% high-density polyethylene and/or modified high- density polyethylene obtained by reacting the high-density polyethylene with an unsaturated carboxylic acid (derivative) and (D) 5-50wt% polyisobutylene and/or modified polyisobutylene prepared by reacting the polyisobutylene with an unsaturated carboxylic acid (derivative).

Description

[Detailed description of the invention] The present invention relates to modified polyethylene compositions.

Conventional technology In the past, polyethylene was coated on the inner and outer surfaces of metal pipes, metal plates, electric wire cables, steel wires, etc. to improve the corrosion resistance, appearance, and food hygiene of metals, or to overcome the drawbacks of various synthetic resins. In order to improve this, composites made by laminating polyethylene are known. In this case, the polyethylene is a composition of modified polyethylene, which is obtained by modifying polyethylene with an unsaturated carboxylic acid or a derivative thereof to give adhesive properties, and synthetic rubber in order to improve its adhesion to metals and various synthetic resins. Are known.

For example, a composition consisting of a hydrocarbon synthetic rubber and a modified ethylene polymer that is substantially a medium-low pressure ethylene polymer having a specific melt index ratio grafted with an unsaturated carboxylic acid or a derivative thereof (JP-A-56-120750) (No. Publication), polyethylene modified with an unsaturated carboxylic acid or its anhydride to which a specific ethylene-α-olefin random copolymer has been added is heat-bonded to a metal body coated with an epoxy resin adhesive and heat-treated. Method (Unexamined Japanese Patent Publication No. 1983-
168628), a laminate laminated with metal foil through a sheet made of modified polyethylene and polyisobutylene (Japanese Unexamined Patent Publication No. 1983-93541), modified high-density polyethylene, copolymer of ethylene and α-olefin Multilayer laminate structure of polyamide and polyethylene composition combined and blended with a rubbery polymer as needed (Japanese Unexamined Patent Publication No. 55-1
No. 21058) and the like have been proposed. On the other hand, in order to improve the adhesion between metals and thermoplastic resins and polyethylene and their durability, compositions of polyethylene and synthetic rubber, in which specific linear low-density polyethylene is modified with unsaturated carboxylic acids or derivatives thereof ( Japanese Unexamined Patent Publication No. 57-16
5415) and a composition modified by reacting an unsaturated carboxylic acid or a derivative thereof with a mixture of a specific linear low-density polyethylene and synthetic rubber (Japanese Unexamined Patent Publication No. 57-16
No. 5469) has also been proposed.

Problems to be Solved by the Invention Although the composition and method proposed above improve the adhesive strength between polyethylene and adherends such as metals and thermoplastic resins, the adhesion at low preheating temperatures of the adherends is poor. There wasn't enough about sex. That is, the modified polyethylene or its composition will not exhibit sufficient adhesion unless it is applied to an adherend at a temperature equal to or higher than the melting point of the resin. Therefore,
Usually, the adherend is preheated to near the melting temperature of the resin, and its surface is coated with the molten resin.

However, when coating a metal body multiple times, for example when coating the inner and outer surfaces of a steel pipe, if the steel pipe whose inner surface is coated first is preheated to near the melting point of the resin, the already coated surface will soften and become damaged. Therefore, a resin was needed that could be bonded even if the preheating temperature of the steel pipe was lowered. Furthermore, if the preheating temperature of the adherend cannot be lowered, the coating is performed by slowing down the cooling rate after coating, resulting in a problem that the line speed (production speed) decreases.

In order to maintain sufficient adhesion even when the preheating temperature of the adherend is lower than in the past, the present inventors first developed a modified linear low-density polyethylene having a specific melt index and polyethylene. A modified polyethylene composition made of isobutylene (Japanese Patent Application No. 60-99621) was proposed.

However, although this composition has sufficient adhesion even when the preheating temperature is lowered, the mechanical strength after cooling, such as threading of pipe ends or There remained room for improvement in the practical strength against the torque applied by tightening with a pipe wrench during piping.

The present invention solves the above-mentioned problems, has excellent adhesion even when the preheating temperature of the adherend is lowered compared to conventional products, and has high practical mechanical strength. An object of the present invention is to provide an adhesive polyethylene composition having the following properties.

The inventors of the present invention conducted intensive studies to solve the above problems, and as a result, they discovered a specific range of melt index (hereinafter referred to as M
The present invention was completed based on the discovery that a composition comprising a modified linear low-density polyethylene, polyisobutylene and/or a modified product thereof, and high-density polyethylene achieves the object of the present invention.

That is, the present invention provides (A) a modified polyethylene 10-9 obtained by reacting an unsaturated carboxylic acid or a derivative thereof with a linear low-density polyethylene having an MI of 7-50 f710.
0% by weight, (B) unmodified polyethylene (excluding high-density polyethylene) 0-85%, (C) high-density polyethylene and/or unsaturated carboxylic acid in the high-density polyethylene 1-< is a derivative thereof and (D) polyisobutylene and/or 15 to 50% by weight of modified polyisobutylene obtained by reacting the polyisobutylene with an unsaturated carboxylic acid or a derivative thereof. The main subject is a polyethylene composition.

Linear low-density polyethylene (hereinafter referred to as LLDPIU) with a MI of 7 to 505F and 710 minutes used in the present invention is processed into ethylene by a low-pressure gas phase method, a solution method, or a liquid phase method in the presence of a chromium-based or Ziegler-based catalyst. α-olefins, such as butene-1, pente/-1, hexe/-1
, 4-methylpentene-1, heptene-1, octene-
It is manufactured by copolymerizing with a material selected from 1, etc., and has an MI of 7 to 501/10 minutes, preferably 8 to 20.
It is 1710 minutes long. The α-olefin is generally contained in an amount of 5 to 20% by weight. These I, LD
Among PE, the density of polymerized by low pressure gas phase method is α905
~0.950 f/ctt”.

It is desirable that the weight average molecule 11W/number average molecule n is 3 to 12. Is Ml of the above LLDPIIC 7? /
If the heating time is less than 10 minutes, the adhesion at low preheating temperatures of the adherend will be insufficient, while if it exceeds 50 f/10 minutes, the strength of the resin will be insufficient.

Moreover, polyethylenes other than MI 7-50F, LL/10 minutes, and DPE do not have sufficient adhesion to the adherend and their durability.

The unmodified polyethylene (excluding high-density polyethylene) used in the present invention is an ethylene homopolymer or copolymer, and preferably has a density of 1910 to [1L940f151
3 and MIo, 1 to 50j'/10 minutes. For example, linear low density polyethylene (LLI) P
Examples include low density polyethylene (hereinafter referred to as LDPE), medium density polyethylene (hereinafter referred to as MDPE), or a copolymer of ethylene and α-olefin or vinyl monomer with an ethylene content of 50% by weight or more. It will be done.

High density polyethylene (hereinafter HDPE) used in the present invention
) is an HDPE with a density α941~(L 970 f/al) obtained by polymerization using a medium-low pressure method as is well known.
By blending a specific amount of , mechanical strength can be improved without reducing adhesiveness.

Commercially available polyisobutylene can be used as the polyisobutylene used in the present invention, but Mooney viscosity (ML, +4.100°C, JI
SK-6300 (same below) is 10 to 150, and crystallinity (X-ray diffraction method) is preferably 30% or less. Furthermore, synthetic rubbers other than polyisobutylene do not have sufficient adhesion to adherends.

Examples of the unsaturated carboxylic acids used in the present invention include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, and methacrylic acid.
,2.1 ] -1,4,5,6,7,7-hexachloro-5-hebutene-2,! l -dicarboxylic acid, endo-pcyclo[:2,2.1]-5-hebutene-2,
S-dicarboxylic acid, cis-4-cyclohexene-1,2
- dicarboxylic acids, etc. In addition, examples of derivatives of unsaturated carboxylic acids include acid anhydrides and esters, such as maleic anhydride, citraconic anhydride, and endo-PcycloC2v2y']-'*'t567
7-hexachloro-5-heptene-2,3-dicarboxylic anhydride, cyclo/Dobycyclo[:2t2tt]-s-heptene-2,3-dicarboxylic anhydride, cis-4-cyclohexene-1,2-dicarboxylic anhydride Acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate,
Examples include maleic acid esters (monoesters, diesters).

LLDPE, ) (DPE or polyisobutylene can be reacted with an unsaturated carboxylic acid or its derivatives by various known methods. For example, LLI) PE,
HDPE or polyisobutylene and an unsaturated carboxylic acid or a derivative thereof in the presence or absence of a solvent and an organic peroxide initiator, such as ditert-butyl peroxide, dicumyl peroxide, benzoyl peroxide, 2 ,5-dimethyl-2,5-di(tert-butylperoxy)-hexyne-5,2,5-
Add dimethyl-2,5-di(tertiary-butylperoxy)-hexane/etc., mix in advance with a mixer such as a shell mixer or ribbon blender, and mix this mixture with a Banbury mixer 1 single-screw or multi-screw mixer. The mixture is melt-kneaded using an extruder at a temperature above the melting point of polyethylene or polyisobutylene and below 280°C. Alternatively, LLDPE, HDPE or polyisobutylene may be dissolved in a solvent, and an unsaturated carboxylic acid or its derivative and a reaction initiator may be added to the solution to cause the reaction.

Here, the amount of unsaturated carboxylic acid or its derivative added to LLDPE, HDPE or polyisobutylene is 0.
．． 01 to 5% by weight is preferred. Therefore, the amount of the unsaturated carboxylic acid or its derivative and the organic peroxide reaction initiator added is 105 to 5 parts by weight of the unsaturated carboxylic acid or its derivative to 100 parts by weight of unmodified LLDPE, HDPE or polyisobutylene. part, reaction initiator a001~(
15 parts by weight is preferred. It should be noted that if the content of unsaturated carboxylic acid or its derivative in the modified polyethylene or modified polyisobutylene obtained is less than LL01% by weight, the strong adhesive strength of the present invention cannot be obtained, while if it exceeds 3% by weight, the adhesion will be poor. No increase in force is observed, and the generation of gel-like substances and discoloration increase, which is economically disadvantageous.

Next, the adhesive polyethylene composition of the present invention contains 10 to 90% by weight of modified polyethylene, preferably 20 to 50% by weight, and 0 to 85% by weight of unmodified polyethylene (with the exception of I (excluding DPE), preferably 0% by weight). ~70wt%, HDP
E and/or modified HDPE 5 to 50 wt%, preferably 5 to 40 wt9I; and polyisobutylene and/or modified polyisobutylene 5 to 50 wt%, preferably 5
~40% by weight. If the content of modified polyethylene, unmodified polyethylene, polyisobutylene and/or modified polyisobutylene is outside the above range, adhesion to adherends with low preheating temperatures will be insufficient. Also H
If the content of DPE is less than 5% by weight, the mechanical strength will be insufficient, while if it exceeds 50% by weight, the adhesion to adherends with low preheating temperatures will be insufficient, and the object of the present invention cannot be achieved.

The composition of the present invention can be produced by mixing modified LLDPE, polyisobutylene and/or modified polyisobutylene, and furthermore, these and unmodified polyethylene in the above-mentioned mixing ratio.

In order to uniformly disperse each of the above components and make a composition with palatable properties, for example, pre-mix using a Henschel mixer, ribbon blender, etc., and then mix this mixture using a Banbury mixer, roll, extruder, etc. From above the melting point of the composition 28
A method of melting and kneading at a temperature of 0° C. or lower is desirable. In addition,
When the polyisobutylene is in the form of a veil, it is desirable to heat and melt-knead it using a Banbury mixer, rolls, or the like.

Further, the composition of the present invention may be one in which an unsaturated carboxylic acid or a derivative thereof is reacted with a mixture of LLDPE, HDPR, and polyisobutylene in the above-mentioned mixing ratio. Furthermore, unmodified polyethylene, HDPK and/or unmodified polyisobutylene may be mixed into this modified mixture at the above-mentioned mixing ratio.

The compositions of the present invention contain various additives, such as heat stabilizers,
Ultraviolet absorbers, nucleating agents, antistatic agents, coloring agents, and various fillers such as inorganic fillers and plasticizers can be blended. These additives and the like may be mixed during or after the preparation of the composition.

The modified polyethylene compositions of the present invention can then form suitable laminates with metals or thermoplastics.

The metal in the laminate using the modified polyethylene composition of the present invention may be iron, aluminum, copper, zinc, nickel, tin, stainless steel, brass, tinplate, galvanized iron, etc. in the form of a plate, foil, cylinder, tube, wire or Other shapes are also available. Examples of thermoplastic resins include polyamides such as nylon 6, nylon 66, nylon 11, nylon 12, and nylon 6-10, and polyolefins such as olefin homopolymers such as polyethylene, polypropylene, and polybutene, or copolymers thereof. , 41 (vinylon), a partially hydrolyzed resin of ethylene-vinyl acetate copolymer (EVAL), polyesters such as polyethylene terephthalate and polyethylene terephthalate, Examples include polyvinyl chloride, but nylon and vinylon are particularly preferred.

A laminate using the modified polyethylene composition of the present invention can be obtained by laminating the modified polyethylene composition of the present invention and one selected from the above metals or thermoplastic resins.

The method of obtaining the laminate is not particularly limited, and examples include a method of forming each into a film or sheet and then thermocompression bonding, a method of laminating outside the die, a method of laminating (coextrusion) inside a die, a method of forming a tube or sheet, etc. Known methods such as extrusion coating or powder coating can be used. In addition, when laminating with metal, pre-treatments such as solvent degreasing, pickling, shot blasting, zinc phosphate treatment, calcium phosphate, etc. are usually performed, and furthermore, as a primer treatment, an epoxy resin primer is used to make the product stronger. A laminate with adhesive strength can be obtained. As the epoxy resin primer, a one-component or two-component modified epoxy resin primer is preferred from the viewpoint of heat resistance or stability.

The structure of the laminate using the modified polyethylene composition of the present invention is basically a two-layer structure in which the modified polyethylene composition of the present invention is laminated with a material selected from the metals or thermoplastic resins described above, but as necessary. Various combinations can be made.

For example, modified polyethylene composition (hereinafter referred to as the composition)/metal, the composition/thermoplastic resin, the composition/metal/
The composition, a combination of metal/wire acid/metal, metal/wire acid/thermoplastic resin, thermoplastic resin/wire acid/thermoplastic resin, etc., and further combinations of these or other combinations. It can also be combined with other materials such as fibers, paper, wood boards, etc.

The composition of the present invention forms a suitable composite (coating, lamination, etc.) with metal or thermoplastic resin as described above, and is particularly useful for coating metal pipes. An example of manufacturing will be explained.

Metal pipes made of grass are cleaned by surface treatment such as shot blasting, grid blasting, or pickling. Furthermore, it is desirable to apply an epoxy adhesive or the like on this as a primer treatment in order to obtain a resin layer with stronger adhesive strength.

The pretreated metal tube is heated to a desired temperature, for example, 100°C or higher, preferably 110 to 15°C, by high-frequency induction heating or the like.
(Heat the IC, and coat the outer surface of the metal tube by extruding it into a tube or wrapping it into a sheet at a temperature above the melting point, preferably 200 to 250°C. The thickness of the coating varies depending on the purpose, but is usually is in the key of α5.Furthermore,
On top of that, an exterior material such as polyolefin, preferably high density polyethylene with melting point or higher, preferably 200 to 200
After extrusion into a tube or wrapping into a sheet at a temperature of 30° C., the product is immediately cooled with water. The thickness of the exterior material is usually about 2 mm. Note that the covering of the exterior material may be omitted as appropriate depending on the application.

In addition, when the above-mentioned metal tube coating is applied to both the inner and outer surfaces of the metal tube, the pretreated metal tube is heated to 100 to 150°C, and the composition and polyolefin, preferably polyethylene, are coated on the inner surface in that order. Paint is applied to form a resin layer.

Next, this inner-coated metal tube is heated to a temperature of 100° C. to less than the melting point of the inner-coated resin, and the outer surface of the metal tube is coated with the composition and polyolefin in the same manner as described above.

Effects of the Invention The composition of the present invention is superior to modified polyethylene compositions that have already been proposed, from lower preheating temperatures to higher temperatures for adherends such as metals and thermoplastic resins. It shows the adhesion strength. Therefore, in multilayer resin coating, there is no inconvenience caused by softening or melting of the already coated layer, and there is no need to slow down the cooling rate after coating, so there is no reduction in production rate.

In addition, the composition of the present invention has improved mechanical strength after adhesion compared to conventional compositions, so it can provide sufficient strength for practical use, such as thread cutting resistance and pipe wrench torque resistance, in coated steel pipes, for example. have

The composition of the present invention has the above-mentioned excellent properties,
Suitable for composites with metals and thermoplastic resins, especially multilayer composites. Examples of composites include the inner and outer surfaces of steel pipes and cast iron pipes. Examples include coatings of steel plates, metal foils, electric cables, steel wires, etc., tank linings, and laminates with various thermoplastic resins such as multilayer films, sheets, bottles, containers, etc.

EXAMPLES Next, the present invention will be explained in detail with reference to examples. In addition,
All parts and percentages in the examples are based on weight, and the test method is as follows.

(1) MI ASTM D-1238E (190℃, 21601)
12) Peel strength After electrolytically degreasing the pickled steel plate (38-41) 100
1)/22 sheets of high-density polyethylene (3 m thick)
It was heated to 0° C. to melt and fuse, and after being left to stand for 10 seconds, it was immersed in running water and cooled to prepare a test piece. The resin layer of the test piece was cut to a width of 10 m, part of it was peeled off as a gripping margin, and the test piece was peeled off at 90° at a peeling rate of 50 m/min using an Instron tensile tester.
Peel strength was measured at 23°C and 50°C.

(3) Tensile modulus JIE3 K 7113 (Crosshead speed I'1
5α/min) (4) Shear adhesive strength JIS K 6850 (5) Thread cutting test Japan Water Works Association standard JWW AK 132-1982
5 described in (Polyethylene powder-lined steel pipes for water supply)
Using the thread cutting method using a GP-PC pipe machine, the maximum temperature at which thread cutting is possible was measured by changing the atmosphere.

(6) Torque test for tightening with a pipe wrench Use a vise or pipe wrench as specified in the Japan Water Steel Pipe Association Standards WS-A53-A4 (polyethylene powder-lined steel pipes for water supply with single-layer polyethylene coating on the inner and outer surfaces), and fix with a vise. The coated steel pipe was tightened with a pipe wrench, torque was applied, and the torque at which the resin layer deformed was measured. The ambient temperature was 50°C.

Examples 1 to 9, Comparative Examples 1 to 4 LLDPE with different MI (comonomer Nibutene-1)
0.6 parts of maleic anhydride/acid and 50,025 parts of λ5-dimethyl-2.5-di(tertiary-butylperoxy)-hexyne were mixed in a Henschel mixer, and this mixture was mixed with 65 parts of φ- It was fed to a screw extruder and melted and kneaded at a set temperature of 230°C and a screw rotation speed of 6 orpm to modify it with maleic anhydride. Obtained LDPE. This modified LLDPE and polyisobutylene [manufactured by Esso Chemical Co., Ltd., Vistanex MML-80 (trade name)] unmodified LLDP
Blending E and HDPE in the proportions shown in Table 123
A composition was obtained by heating, melting and kneading at 0°C.

The physical properties of each of the obtained compositions and laminates with steel plates of each preheating temperature were prepared using each composition, and the peel strength and shear adhesive strength were measured, and the results are shown in Table 1.

For comparison, LLDPE with MI5r/jO content and ethylene butene rubber instead of polyisobutylene were used.
Manufactured by Mikata Petrochemical Co., Ltd., A-4085 (product name), hereinafter EB
R) and without HDPE, compositions were prepared and laminates were prepared in the same manner as in Example 1, and the physical properties and peel strength were measured, and the results are also listed in Table 1. .

Example 10, Comparative Example 5 A 50mm φ SGP black tube was descaled by pickling treatment as a test metal tube, and then heated to each temperature shown in Table 2 by high frequency induction heating, and this steel tube was used in Example 5. The modified polyethylene composition was heated to a resin hardness of 220 using an extruder with a diameter of 65 mm.
The resin-coated steel pipe was extruded and coated at 1° C. into a tube at a line speed of 1 m/min to a thickness of 1 m/min, and cooled in a water tank with a distance of 5 cm from the die to obtain a resin-coated steel pipe. The peel strength and physical properties of the obtained coated steel pipe are shown in Table 2.

For comparison, a resin-coated steel pipe was obtained in the same manner as in Example 10, except that the composition of Comparative Example 4 was used. The peel strength and physical properties of the obtained coated steel pipe are also listed in Table 2.

Table 2 Example 11.12 After mixing the unmodified LLDPE1HDPK and polyisobutylene used in Examples 1 and 4 in the proportions shown in Table 3, maleic anhydride was reacted with this mixture in the same manner as in Example 1. A modified polyethylene composition was obtained. A laminate with a steel plate was prepared using the obtained composition, and the physical properties and peel strength were measured, and the results are shown in Table 5.

Table-3

Claims (1)

[Claims] (1) (A) Modified polyethylene 10-9 made by reacting linear low-density polyethylene with a melt index of 7-50 g/10 min with an unsaturated carboxylic acid or a derivative thereof
0% by weight, (B) unmodified polyethylene (excluding high-density polyethylene) 0 to 85% by weight, (C) high-density polyethylene and/or the high-density polyethylene reacted with an unsaturated carboxylic acid or a derivative thereof. An adhesive polyethylene composition comprising 5 to 50% by weight of a modified high-density polyethylene and (D) 5 to 50% by weight of a modified polyisobutylene obtained by reacting polyisobutylene and/or the polyisobutylene with an unsaturated carboxylic acid or a derivative thereof. thing.