JP3393734B2 - Metal laminate structure - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated structure of metal and polyethylene. More specifically, the present invention relates to a metal laminated structure particularly useful for the purpose of coating steel pipes for transporting crude oil, natural gas, etc., which are placed under severe environmental conditions.

[0002]

2. Description of the Related Art Since steel, which is the most common metal material, has a drawback that it is easily corroded, it is usually used by being subjected to various anticorrosion treatments before or during use. As an anticorrosion treatment for steel materials, a method of using a plastic coating material such as polyethylene is often used for coating steel pipes and the like arranged outdoors.

For example, Japanese Patent Application Laid-Open No. 56-10537 discloses a steel pipe coating material using a specific polyethylene composition.

In general, a covering material made of a material such as polyethylene has poor adhesion to a metal surface,
Usually, an adhesive layer is interposed between the metal surface and the plastic coating material for coating to perform adhesion, thereby preventing the plastic coating material from being detached from the metal surface.

As the above-mentioned adhesive, it is known to laminate (bond) a modified polyolefin obtained by grafting an unsaturated dicarboxylic acid on a polyolefin such as polyethylene or polypropylene.

For example, Japanese Patent Publication No. 62-2871 discloses a method of coating a metal surface using a modified polyolefin obtained by grafting a linear low-density polyethylene with unsaturated dicarboxylic acids as an adhesive.

Further, JP-A-4-300933 discloses a composition containing a modified product of an α-olefin random copolymer with an unsaturated carboxylic acid and a polypropylene resin, or JP-A-5-50556. JP-A-5
No. -50557 discloses a method of using a composition containing a modified product of a polyolefin random copolymer having a specific structure and physical properties with an unsaturated carboxylic acid as an adhesive.

In recent years, the development of energy in polar regions has progressed,
Pipeline laying work has started to be performed at extremely low temperatures of 60 ° C or less. Since the coating may be damaged due to contact between pipes during construction, it is an important issue to improve the low-temperature impact resistance of the polyethylene coating at such extremely low temperatures.

When the crude oil to be collected is heavy oil,
In order to reduce the viscosity, it may be heated to 40 ° C. or higher and transported. Therefore, in a pipeline or the like which is operated at a high temperature in an extremely cold region, it is important to secure the adhesive strength at a high temperature in addition to the low temperature impact resistance of the coating.

However, conventional modified polyolefins have low adhesive strength to metals such as steel, iron, aluminum and the like, and their impact resistance at low temperatures is insufficient, so that improvement is desired.

Further, conventionally, when an ethylene-α-olefin copolymer has a narrow molecular weight distribution, although mechanical properties such as impact properties and tensile properties are improved, on the other hand, the molding processability tends to be deteriorated. No product with satisfactory characteristics has been obtained.

[0012]

DISCLOSURE OF THE INVENTION According to the present invention, an adhesive polyethylene composition having high adhesive strength with a metal and excellent low temperature impact resistance is used as an adhesive layer, and a specific polyethylene composition is used as a coating layer. When used, especially when coating steel pipes for the purpose of anticorrosion, it has excellent impact resistance at extremely low temperatures (-60 ° C or lower) and has excellent adhesive performance at relatively high temperatures (40 ° C or higher). It is to provide a metal laminated structure.

[0013]

Means for Solving the Problems The first aspect of the present invention is to provide a metal layer (A), 5 to 50% by weight of a modified polyethylene obtained by grafting an unsaturated carboxylic acid on a linear low density polyethylene, and an ethylene-α-olefin. Copolymer 95-50% by weight
A polyethylene composition adhesive layer (B) consisting of 80% by weight or more of high-middle / low-pressure polyethylene and having a density of 0.
A metal laminated structure comprising a polyethylene composition coating layer (C) of 92 to 0.95 g / cm ³ , wherein the ethylene-α-olefin copolymer has a molecular weight distribution (Mw / M
n) is 2.5 or less, and the melt flow ratio (MI
₁₀ / MI _2.16 ) is in the range of 5 to 15 (where MI ₁₀ is 1
Melt index at 90 ° C, load of 10 kg, MI
_2.16 represents a melt index at a load of _2.16 Kg at 190 ° C. ) Is a metal laminated structure.

Secondly, the present invention relates to a polyethylene composition contact.
The adhesive layer (B) is the adhesive polyethylene composition according to claim 1.
Ethylene-propylene copolymer based on 100 parts by weight
Characterized in that it contains less than 50 parts by weight of rubber
Metal laminated structure Is.

As the metal layer material (A) of the metal laminated structure of the present invention, various materials are used, but typical ones are:
Examples include iron, zinc, tin, aluminum, copper, nickel and the like.

Further, alloys of these metals, those plated with these metals, those plated with these metals, and the like can be mentioned. Particularly, a steel plate and a TSF steel plate are preferable.

The form of the metal material is not particularly limited, and a metal material formed into any shape such as a flat plate shape, a rod shape, or a tubular shape can be used.

It is desirable that the surface of these metals is previously subjected to a cleaning treatment such as degreasing treatment or a roughening treatment such as grid blasting, as conventionally known.

It is also preferable to subject the metal surface to a base treatment consisting of a chromate film and an epoxy primer layer, since a laminate having a larger adhesive force and a better anticorrosion property can be obtained.

First, a chromate treatment agent is applied to the surface of a metal that has been subjected to cleaning treatment such as degreasing treatment or roughening treatment such as grid blasting with a roll or brush and then heated and baked to form a chromate film. .

The chromate-treating agent is, for example, a reduced aqueous solution obtained by partially heating the aqueous solution of chromic anhydride with an organic reducing agent to partially reduce hexavalent chromium in the aqueous solution to trivalent chromium. To a reduced aqueous solution in which a part of hexavalent chromium in the aqueous solution is partially reduced to trivalent chromium by adding an organic reducing agent or the like to a mixture in which is added and dispersed, or a mixed aqueous solution of chromic anhydride and phosphoric acid, A mixture in which fine particles of silica are added and dispersed is used.

The epoxy primer coating is formed by applying a primer consisting of a mixture of epoxy, a pigment and a curing agent onto the chromate coating on the metal surface by a method such as spray coating or ironing, followed by heat curing.

As the epoxy resin, diglycidyl ether of bisphenol A or bisphenol F alone,
Alternatively, a mixture is preferred.

As the pigment, an inorganic pigment such as silica or titanium oxide is used. As the curing agent, alicyclic amine, aliphatic amine, dicyandiamide, modified imidazole or the like is used.

Good results are obtained when the chromate film has a thickness of 1000 mg / m ² or less in terms of the total amount of chromium deposited after heating and baking.

If it exceeds 1000 mg / m ² , the adhesion between the epoxy primer and the metal will be reduced. Good results are obtained when the epoxy primer layer has a thickness of 200 μm or less. If it exceeds 200 μm, the low temperature impact resistance decreases.

In the present invention, the above metal layer (A)
To form a polyethylene composition adhesive layer (B) consisting of 5 to 50% by weight of modified polyethylene obtained by grafting unsaturated carboxylic acids on linear low-density polyethylene and 95 to 50% by weight of ethylene-α-olefin copolymer. To do.

The linear low-density polyethylene in the present invention is a solution polymerization of ethylene and α-olefin in the presence of a Ziegler-type or chromium-type etchant under medium and low pressure.
It is an ethylene-α-olefin copolymer having a relatively wide molecular weight distribution that can be produced by copolymerization by a method such as gas phase polymerization or slurry polymerization.

As the comonomer for copolymerization, propylene, butene-1, pentene-1,4-methylpentene-
1, α-olefins having 3 or more carbon atoms such as octene-1.

The repeating unit derived from the α-olefin of linear low density polyethylene is 0.1 to 10 moles.
% Is preferable.

As the linear low density polyethylene, those having the following physical properties are particularly preferable. The melt index at 190 ° C. is 0.1 to 10 g / 10 minutes or less, and more preferably 0.5 to 5 g / 10 minutes. The molecular weight distribution (Mw / Mn) is 3 or more, more preferably 4 to 30.

The modified polyethylene of the present invention is obtained by grafting an unsaturated dicarboxylic acid on the above linear low density polyethylene.

Examples of the unsaturated carboxylic acids include unsaturated dicarboxylic acids such as maleic acid, itaconic acid and citraconic acid, and anhydrides of these acids.

The amount of unsaturated carboxylic acids to be grafted on the linear low density polyethylene is preferably 0.01 to 5% by weight, more preferably 0.04 to 1% by weight.

As a method for grafting the unsaturated carboxylic acids onto the linear low-density polyethylene, for example, the composition and the unsaturated dicarboxylic acids can be produced by melt-kneading in the presence of a reaction initiator.

As the reaction initiator, an organic peroxide type reaction initiator such as t-butyl-hydroperoxide can be used. In addition, cumene dimers such as 2,3-dimethyl-2,3-diphenylbutane and derivatives thereof can be used.

The ethylene-α-olefin copolymer in the present invention is obtained by copolymerizing ethylene and α-olefin in the presence of a single site catalyst.

The ethylene-α-olefin copolymer of the present invention has a molecular weight distribution (Mw / Mn) of preferably 2.5 or less, more preferably 1.9 to 2.3. The melt flow ratio (MI ₁₀ / MI _2.16 ) is 5
In the range of -15 to 15, preferably in the range of 6.8 to 11.5 (where MI ₁₀ represents the melt index at 190 ° C. and the load of 10 kg, and MI _2.16 represents the melt index at 190 ° C. and the load of _2.16 kg). Is.

Examples of the α-olefin constituting the ethylene-α-olefin copolymer include propylene and butene-
1, pentene-1, hexene-1, 4-methylpentene-1, octene-1 and the like can be mentioned, but α-olefins having 4 or more carbon atoms are preferable, and α-olefins having 5 to 10 carbon atoms are more preferable.

In this case, the number of tie molecule bonds may be increased, and the mechanical strength is expected to be improved. For example, Octene-1 can be preferably used.

Α in the ethylene-α-olefin copolymer
-The repeating unit derived from an olefin is usually 3
The content is 0 wt% or less. The α-olefin may be used alone or in combination of two or more kinds in the ethylene-α-olefin copolymer.

Ethylene-α-olefin copolymerization of the present invention
As the body, one having the following physical properties is particularly preferable. 1
Melt index of 1.16Kg load at 90 ℃ is 1
0 g / 10 minutes or less, more preferably 0.5 to 5 g
/ 10 minutes. Density 0.94g / cm³Below
More preferably 0.86 to 0.92 g / cm³ And
It The molecular weight distribution (Mw / Mn) is 2.5 or less,
More preferably, it is 1.9 to 2.3.

The ethylene-α-olefin copolymer of the present invention can be produced with a single-site catalyst. As the single-site catalyst, a combination of a metallocene compound of a transition metal of Group IV or V of the Periodic Table with an organoaluminum compound and / or an ionic compound is used.

Titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V) and the like are preferable as the group IV or V transition metal of the periodic table.

The metallocene compound means at least one cyclopentadienyl group and a substituted cyclopentadienyl group (for example, an alkyl-substituted cyclopentadienyl group such as methyl, dimethyl and pentamethyl, an indenyl group,
Fluorenyl group) as a ligand, or a cyclopentadienyl group thereof as a hydrocarbyl group (eg, alkylene group, substituted alkylene group), hydrocarbyl silicon (eg, silanylene group, substituted silanylene group, silaalkylene group, substituted Silaalkylene) and the like, further cyclopentadienyl group is oxygen,
Those bridged to nitrogen or phosphorus atom (for example, oxasilanylene group, substituted oxasilanylene group, oxasilaalkylene group, substituted oxasilaalkylene group, aminosilyl group,
Any known metallocene compound having a monosubstituted aminosilyl group, a phosphinosilyl group, or a monosubstituted phosphinosilyl group) as a ligand can be used.

Specific examples thereof are disclosed in Japanese Patent Laid-Open No. 58-1.
No. 9309, No. 60-35006, No. 61-
130314, 61-264010, 61-296008, 63-222177, 63-251405, and JP-A-1-6621.
No. 4, gazette 1-74202, gazette 1-27560
No. 9, 1-301704, No. 1-3194
No. 89, No. 2-41303, No. 2-1314
No. 88, No. 3-12406, No. 3-1395.
No. 04, No. 3-179006, No. 3-185.
No. 005, No. 3-188092, No. 3-19
No. 7514, No. 3-207703, No. 5-2
Examples thereof include those described in Japanese Patent Application Publication No. 09013, Japanese Patent Publication No. 1-501950, Japanese Patent Publication No. 1-502036, and Japanese Patent Publication No. 5-505593.

In the present invention, as a single-site catalyst other than the above, Japanese Patent Laid-Open No. 61-130314,
61-264010, 63-142004, JP-A-1-129004, and 1-3017.
No. 04, No. 2-75605, No. 3-1240.
6 gazette, the same 3-12407 gazette, the same 4-22770
No. 8, JP-A 4-268308, and JP-A 4-3008.
Examples thereof include metallocene compounds as described in JP-A-87 and JP-A-6-25343.

Further, the constrained geometry type catalyst described in JP-A-3-163088 can be used.

Specific examples of these metallocene compounds include dimethylsilyl (2,4-dimethylcyclopentadienyl) (3 ', 5'-dimethylcyclopentadienyl) zirconium dichloride and dimethylsilyl (2.
Silicon-bridged metallocene compounds such as 4-dimethylcyclopentadienyl) (3 ', 5'-dimethylcyclopentadienyl) hafnium dichloride, ethylenebisindenylzirconium dichloride, ethylenebisindenylhafnium dichloride, ethylenebis (methylindene) Examples thereof include indenyl-based crosslinkable metallocene compounds such as (nil) zirconium dichloride and ethylenebis (methylindenyl) hafnium dichloride.

The organoaluminum compound used in combination with the metallocene compound in the present invention has a general formula:
A linear or cyclic polymer represented by (—Al (R) O—) _n (wherein R is a hydrocarbon group having 1 to 10 carbon atoms and partially substituted with a halogen atom and / or an RO group) And n is a degree of polymerization and is 5 or more, preferably 10 or more), and specific examples thereof are methylalumoxane, ethylalumoxane and isobutylethylalumoxane in which R is a methyl, ethyl or isobutyl group, respectively. And so on.

Examples of other organoaluminum compounds include trialkylaluminum, dialkylhalogenoaluminum, sesquialkylhalogenoaluminum, alkenylaluminum, dialkylhydroaluminum and sesquialkylhydroaluminum.

Specific examples thereof include trialkylaluminums such as trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum and trioctylaluminum, dialkylhalogenoaluminums such as dimethylaluminum chloride and diethylaluminum chloride, sesquimethylaluminum chloride, Examples include sesquialkylhalogenoaluminum such as sesquiethylaluminum chloride, ethylaluminum dichloride, diethylaluminum hydride, and sesquiethylaluminum hydride.

These organoaluminum compounds can be used in combination with the above organoaluminum oxy compounds.

[0054] As the ionic compound of the general formula, C ⁺ A ^-
In indicated, C ⁺ is an organic compound, an organometallic compound, or oxidizing cations of an inorganic compound, or a blanking lens slashed.nsted acid consisting of a Lewis base and a proton, the metallocene cation reacts with the anion of metallocene ligands Can be generated.

A ⁻ is a bulky, non-coordinating anion and can stabilize the metallocene cation without coordinating to the metallocene.

Specific examples thereof are disclosed in Japanese Patent Application Laid-Open No. 4-25
Those described in 3711, No. 4-305585, No. 5-507756, and No. 5-502906 can be used.

Particularly, an ionic compound of a tetrakis (pentafluorophenyl) borate anion and a triphenylcarbonium cation or a dialkylanilinium cation is preferable.

These ionic compounds can be used in combination with the above organoaluminum compounds.

As a method for copolymerizing ethylene and α-olefins using a single-site catalyst, various well-known methods can be adopted, and fluidized bed gas phase polymerization in an inert gas or stirred gas polymerization can be used. Phase polymerization, slurry polymerization in an inert solvent, bulk polymerization using a monomer as a solvent and the like can be mentioned.

The polymerization temperature is usually 10 to 150 ° C., preferably 20 to 90 ° C., and the polymerization time is usually 0.1 to 150 ° C.
10 hours.

When a metallocene compound and an organoaluminum compound are used as the single-site polymerization catalyst of the present invention, aluminum (A
l) The molar ratio of the atom to the transition metal atom of the metallocene compound (Al / transition metal atom molar ratio) is usually 10 to 1
It is 0,000, preferably 10 to 1,000.

As the single-site polymerization catalyst of the present invention, an ionic compound may be used alone or in combination with the organoaluminum compound instead of the organoaluminum compound. The ionic compound / transition metal atom molar ratio is usually
It is 0.1 to 50, preferably 0.5 to 5.

The blending ratio of the modified polyethylene obtained by grafting unsaturated carboxylic acids to the linear low density polyethylene and the ethylene-α-olefin copolymer in the present invention is:
Modified polyethylene 5 to 50% by weight, preferably 10 to
40% by weight, and 95 to 50% by weight, preferably 90 to 60% by weight, of the ethylene-α-olefin copolymer. The adhesive polyethylene composition of the present invention further improves the adhesiveness and the low temperature characteristics by containing the respective components in the above proportions.

The adhesive polyethylene composition of the present invention may further contain an ethylene-propylene copolymer rubber. The amount of the ethylene-propylene copolymer rubber compounded is usually 50 parts by weight or less, more preferably 4 parts by weight, based on 100 parts by weight of the adhesive polyethylene composition.
It is 0 parts by weight or less.

By blending the ethylene-propylene copolymer rubber, the low temperature characteristics of the adhesive polyethylene composition are further improved.

The adhesive polyethylene composition of the present invention comprises an antioxidant, an ultraviolet absorber, a flame retardant, an inorganic
Organic fillers, pigments, antistatic agents, etc. can be added.

The adhesive polyethylene composition of the present invention is formed into a powder, pellet, film or sheet in any desired form by the same method as for ordinary polyethylene, and laminated on the metal layer (A). Then, the fusion is performed by heat fusion or preheating applied to the metal surface. Polyethylene composition adhesive layer (B) thus formed
The layer thickness is not particularly limited, but is usually 50 to 500 μ.
m.

On the surface of the polyethylene composition adhesive layer (B), a polyethylene composition coating layer (C) having a density of 0.92 to 0.95 g / cm ³ comprising 80% by weight or more of high-middle- and low-pressure polyethylene is then formed. To form.

As the high-pressure polyethylene, an ethylene polymer obtained by polymerizing ethylene or an ethylene and a comonomer are polymerized in the presence of a catalyst generating a free radical at a polymerization pressure of 1000 atm or more and a polymerization temperature of 100 to 300 ° C. The resulting ethylene copolymer is included.

As the ethylene copolymer, ethylene-
Examples thereof include a propylene copolymer, an ethylene-butene-1 copolymer, an ethylene-vinyl acetate copolymer, an ethylene-acrylic acid ester copolymer, an ethylene-methacrylic acid ester copolymer , and the ethylene-vinyl acetate copolymer is preferably used.

The vinyl acetate-derived repeating units of the ethylene-vinyl acetate copolymer are preferably 0.
It is 5 to 30% by weight.

The medium- and low-pressure polyethylene is a copolymer of ethylene and α-olefin in the presence of a Ziegler-type or chromium-type catalyst at medium and low pressure by a method such as solution polymerization, gas phase polymerization or slurry polymerization. Polyethylene having a molecular weight distribution (Mw / Mn) of 3 to 30 that can be produced by

As the polyethylene composition coating layer (C) used in the present invention, in addition to the above-mentioned high , medium and low pressure polyethylene, an antioxidant, an ultraviolet absorber, a flame retardant,
Inorganic / organic fillers, pigments, antistatic agents, etc. can be added.

For example, carbon black of 0.5 to 10
% By weight, as antioxidant, phenolic antioxidant,
Sulfide-based antioxidants, phosphite-based antioxidants and the like can be added in an amount of 0.01 to 2% by weight.

In the present invention, the polyethylene composition for forming the coating layer comprises the above-mentioned high-middle-pressure low-pressure polyethylene 80% by weight.
The composition is blended in an amount of not less than wt%. If the blending ratio is less than 80% by weight, the properties of polyethylene are deteriorated, which is not preferable.

In the present invention, it is necessary that the density of the polyethylene composition is 0.92 to 0.95 g / cm ³ . If the density is out of the above range, characteristics such as deformation resistance and moldability are deteriorated, which is not preferable.

The polyethylene composition coating layer (C) is laminated on the polyethylene composition adhesive layer (B) by molding into a desired shape such as powder, pellet, film or sheet, followed by heat fusion or fusion. The fusion is performed by utilizing the preheating applied to the metal surface.

The layer thickness of the polyethylene composition coating layer (C) thus formed is not particularly limited, but usually 5
It is from 00 to 5000 μm.

The present invention will be described in detail below with reference to examples.

[0080]

【Example】

(A) Low temperature impact test (1) Preparation of metal laminated structure (low temperature impact test piece) Steel plate (SS-41: 10) rust removed by grid blasting
0 mm × 150 mm × 9 mm (t)) is immersed in acetone and ultrasonically cleaned for 30 minutes to degrease it.

After air drying with air, a chromate treatment agent (the weight ratio of trivalent chromium to total chromium in the aqueous solution was 0.4,
A weight ratio of silica is 2.0 and a weight ratio of phosphoric acid is 1.0) is applied with a brush so that the total amount of deposited chromium is 550 mg / m ^2, and dried.

The chromate-treated steel sheet was placed in an oven at 140 ° C., kept for 30 minutes or more, and then placed on a hot plate heated at 180 ° C. to obtain an epoxy primer (100 parts by weight of diglycidyl ether of bisphenol A, fine particle silica 3). A mixture of 1 part by weight and 50 parts by weight of an alicyclic amine-based curing agent) is applied with a bar coater to a thickness of 50 μm, and cured and cured for 30 seconds.

Next, a T-die forming sheet of adhesive polyethylene composition (100 mm × 150 mm × 0.2 mm
(T) is pasted and cured and melted for 1 minute, then,
T-die molding sheet (100 mm × 150 mm × 2.5 mm) of high-middle- and low-pressure polyethylene composition as a coating
(T)) is pasted.

Further, a polyester film (Mylar film), the above-mentioned grid-blasted steel sheet preheated to 160 ° C., a weight of 10 kg were placed in that order and crimped for 3 minutes, then placed in water and cooled to produce a metal laminated structure. did. This metal laminated structure was used as a test piece for a low temperature impact test.

The high, medium and low pressure polyethylene composition used for the above coating layer has a density of 0.935 containing 2% by weight of carbon black in an ethylene-vinyl acetate copolymer.
A high pressure polyethylene composition of g / cm ³ was used.

(2) Low temperature impact test of metal laminated structure The test piece of the above (1) was put into a low temperature tank kept at -60 ° C by dry ice / ethanol, and after 30 minutes or more, coating of the test piece Place it horizontally with the polyethylene layer facing up.

At this time, the amount of ethanol is adjusted so that ethanol is 10 mm or more from the upper part of the test piece.

A steel punch having a tip with R = 19 mmφ was placed on the test piece, and a 4 kg weight was allowed to fall freely from a predetermined height (the distance from the bottom of the weight to the top of the punch). Collide with the top of the punch.

The test piece is taken out and inspected for penetration or cracks (the test is performed 10 times to indicate the presence or absence of penetration or cracks).

(3) Production of polyethylene-coated steel pipe Steel pipe (SGP200A × 5500 mm length × 5.8 mm)
The outer surface of (thickness) is grid blasted to remove rust, and a chromate treatment agent (weight ratio of trivalent chromium to total chromium in the aqueous solution is 0.4, weight ratio of silica is 2.0, and weight ratio of phosphoric acid is 1. 0) is applied with a brush so that the total amount of deposited chromium is 550 mg / m ^2, and dried.

An epoxy primer (a mixture of 100 parts by weight of diglycidyl ether of bisphenol A, 3 parts by weight of fine particle silica and 50 parts by weight of an alicyclic amine-based curing agent) is applied to the outer surface of the chromated steel pipe to a thickness of 50 μm. As described above, the steel pipe is heated and hardened by high frequency induction heating so that the surface temperature becomes 220 ° C.

Two layers of the adhesive polyethylene composition and the high, medium and low pressure polyethylene composition were extruded from the T die on the surface, and the thickness of the adhesive polyethylene composition layer was 250 μm.
m, the thickness of the high, medium, low pressure polyethylene composition layer is 2.5 m
A polyethylene-coated steel pipe was manufactured by spirally coating so as to have a thickness of m.

The high, medium and low pressure polyethylene composition used for the above coating layer has a density of 0.935 containing 2% by weight of carbon black in an ethylene-vinyl acetate copolymer.
A high pressure polyethylene composition of g / cm ³ was used.

(4) Low temperature impact test of polyethylene-coated steel pipe It was carried out in accordance with the standard of ASTM G14.

(B) Adhesive Strength Test (1) Preparation of Metal Laminated Structure (Adhesive Strength Measurement Specimen) T-die forming sheet (100 of adhesive polyethylene composition)
mm × 150 mm × 0.2 mm (t)) is laminated in the same manner as in A- (1), and then the adhesive polyethylene composition sheet and the high-middle / low-pressure polyethylene composition sheet (100 mm × 150 mm × 2. 5 mm (t)) to form a partially unbonded portion.
Stack mylar up to 0 mm, then A-
Similar to (1), the high-middle- and low-pressure polyethylene composition sheets are laminated to prepare a test piece for measuring adhesive strength.

(2) Measurement of adhesive strength of metal laminated structure The test pieces prepared in B- (1) were cracked in the long direction at intervals of 10 mm with a cutter knife, and a tensile strength tester equipped with a thermostatic chamber was used. Using, the polyethylene layer of the unbonded part was sandwiched between chucks and mounted on a jig for 90 ° peeling, and the peeling speed was 50 mm / mi after the test piece was sufficiently heated to 40 ° C.
A 90 degree peel test was performed at n to measure the adhesive strength.

(3) Measurement of Adhesive Strength of Polyethylene Coated Steel Pipe The adhesive strength of the polyethylene coated steel pipe manufactured in A- (3) was measured according to the standard of DIN 30670.

[0098]

Example 1 Melt index (MI) produced using Ziegler type catalyst 1.9 g / 10 minutes, density 0.91
For linear low density polyethylene having 9 g / cm ³ , molecular weight distribution (Mw / Mn) of 4.2 and butene-1 content of 8 wt%,
0% by weight of maleic anhydride and 0.1% as a radical generator.
25% by weight of 2,3-dimethyl-2,3-diphenylbutane was mixed in a Henschel mixer and melt-kneaded at 260 ° C. in a nitrogen stream in a twin-screw extruder to obtain 0.95.
Graft-polymerized maleic anhydride (wt%) gave a modified polyethylene.

As an ethylene-α-olefin copolymer, a melt index (MI) produced using a single-site catalyst was 1.1 g / 10 minutes and a density was 0.902 g.
/ Cm ³ , molecular weight distribution (Mw / Mn) 2.1, melt flow ratio (MI ₁₀ / MI _2.16 ) 7.6, and an octene-1 content of 12 wt% copolymer of ethylene and octene-1 was used.

30% by weight of the modified polyethylene and 70% by weight of the ethylene-α-olefin copolymer were mixed and melt-kneaded with a twin-screw extruder to obtain an adhesive polyethylene composition.

This adhesive polyethylene composition was molded using a T-die molding machine, width 150 mm, thickness 0.2 mm.
A metal laminated structure was produced using the sheet of.

Using this, a low temperature impact test A- (2),
And the adhesive strength test B- (2). In the low temperature impact test, the test was performed 10 times under the conditions of an impact energy of −60 ° C. and 5 kg · m.

The polyethylene coating layer penetrated and no cracking occurred. The adhesive strength at 40 ° C is 16 kg /
It was cm.

[0104]

Example 2 A polyethylene composition used as an adhesive layer was prepared by adding 100 parts by weight of a mixture of 20% by weight of the modified polyethylene of Example 1 and 80% by weight of the ethylene-α-olefin copolymer of Example 1 at 230 ° C. A metal laminated structure was prepared in the same manner as in Example 1, except that 10 parts by weight of ethylene-propylene copolymer rubber having a melt flow rate of 0.7 g / 10 minutes and a propylene content of 27 wt% was blended.

Using this, a low temperature impact test A- (2),
And the adhesive strength test B- (2). In the low temperature impact test, the test was performed 10 times under the conditions of an impact energy of −60 ° C. and 5 kg · m. The polyethylene coating layer penetrated and no cracks occurred. The adhesive strength at 40 ° C. was 15 kg / cm.

[0106]

Example 3 A polyethylene-coated steel pipe was produced using the adhesive polyethylene composition used in Example 1.

This coated steel pipe was subjected to a low temperature impact test A- (4),
And the adhesive strength test B- (3). The impact test was performed 20 times at -60 ° C.

The impact energy required for penetrating the coating layer was 4.8 kg · m, and the polyethylene coating layer was never cracked. The adhesive strength at 40 ° C. was 16 kg / cm.

[0109]

Comparative Example 1 Melt index (MI) produced using Ziegler type catalyst 1.9 g / 10 minutes, density 0.91
0.1% by weight of linear low density polyethylene having 9 g / cm ³ , molecular weight distribution (Mw / Mn) of 4.2, melt flow ratio (MI ₁₀ / MI _2.16 ) of 7.1, butene-1 content of 8 wt%.
Maleic anhydride and 0.04% by weight of t-butyl hydroperoxide as a radical generator were mixed in a Henschel mixer, and then mixed in a nitrogen stream in a twin-screw extruder.
Melt kneading was carried out at 20 ° C., and 0.09% by weight of maleic anhydride was graft-polymerized to obtain modified polyethylene.

Using the modified polyethylene as an adhesive layer, a metal laminated structure was prepared in the same manner as in Example 1.

Using this, a low temperature impact test A- (2),
And the adhesive strength test B- (2). In the low temperature impact test, the test was performed 10 times under the conditions of an impact energy of −60 ° C. and 5 kg · m.

The polyethylene coating layer penetrated and cracks occurred 6 times. The adhesive strength at 40 ° C. was 19 kg / cm.

[0113]

Comparative Example 2 Melt index (MI) produced using Ziegler type catalyst 1.9 g / 10 minutes, density 0.91
For linear low density polyethylene having 9 g / cm ³ , molecular weight distribution (Mw / Mn) of 4.2 and butene-1 content of 8 wt%,
0% by weight of maleic anhydride and 0.1% as a radical generator.
25% by weight of 2,3-dimethyl-2,3-diphenylbutane was mixed in a Henschel mixer and melt-kneaded at 260 ° C. in a nitrogen stream in a twin-screw extruder to obtain 0.95.
30% by weight of modified polyethylene graft-polymerized with 50% by weight of maleic anhydride, and a melt index (MI) of 0.9 g / MI produced by using a Ziegler-based catalyst instead of the ethylene-α-olefin copolymer of Example 1. 10 minutes, density 0.920 g / cm ³ , molecular weight distribution (Mw / Mn)
3.9, melt flow ratio (MI ₁₀ / MI _2.16 ) 7.0,
Butene-1 linear low density polyethylene 70 containing 8 wt%
20 parts by weight of the ethylene-propylene copolymer rubber used in Example 2 was mixed with 100 parts by weight of the mixture with 100% by weight and melt-kneaded with a twin-screw extruder to obtain an adhesive polyethylene composition.

Using this adhesive polyethylene composition as an adhesive layer, a metal laminated structure was prepared in the same manner as in Example 1.

Using this, low temperature impact test A- (2),
And the adhesive strength test B- (2).

In the low temperature impact test, -60 ° C., 5 kg · m
The test was performed 10 times under the conditions of impact energy of. The polyethylene coating layer penetrated and cracks occurred twice. The adhesive strength at 40 ° C. was 17 kg / cm.

[0117]

Comparative Example 3 Melt produced using Ziegler type catalyst
Index (MI) 1.9g / 10 minutes, density 0.91
9 g / cm³, Molecular weight distribution (Mw / Mn) 4.2, bute
-1 to linear low density polyethylene with a content of 8 wt%
0% by weight of maleic anhydride and 0.1% as a radical generator.
25% by weight of 2,3-dimethyl-2,3-diphenylbu
Mix the tongue with a Henschel mixer and use it in a twin-screw extruder.
And melt kneading at 260 ° C under a nitrogen stream to obtain 0.95
Modified Polyester Graft-Polymerized by Weight% Maleic Anhydride
30% by weight of ethylene and ethylene-α-olefin of Example 1
Manufactured using a Ziegler-based catalyst instead of a vinyl copolymer
Melt index (MI) 1.5g / 10 minutes, dense
Degree 0.905g / cm³, Molecular weight distribution (Mw / Mn)
4.4, Melt flow ratio (MI _Ten/ MI_2.16) 7.2,
Butene-1 linear low density polyethylene 7 with a content of 15 wt%
100 parts by weight of the mixture with 0% by weight are used in Example 2.
Add 20 parts by weight of ethylene-propylene copolymer rubber,
Melt kneading with a shaft extruder to obtain an adhesive polyethylene composition
It was

Using this adhesive polyethylene composition as an adhesive layer, a metal laminated structure was prepared in the same manner as in Example 1.

Using this, low temperature impact test A- (2),
And the adhesive strength test B- (2). In the low temperature impact test, the test was performed 10 times under the conditions of an impact energy of −60 ° C. and 5 kg · m. The polyethylene coating layer penetrated and cracks occurred twice. The adhesive strength test at 40 ° C is
It was 8 kg / cm.

[0120]

Comparative Example 4 A polyethylene-coated steel pipe was produced using the adhesive polyethylene composition used in Comparative Example 1.

This coated steel pipe was subjected to a low temperature impact test A- (4),
And the adhesive strength test B- (3). The impact test was conducted 20 times at -60 ° C.

The impact energy required to penetrate the coating layer was 4.1 kg · m, and the polyethylene coating layer was cracked five times. The adhesive strength at 40 ° C is 17k.
It was g / cm.

[0123]

The metal laminated structure of the present invention has a larger adhesive strength between the metal and the coating layer than the conventional metal laminated structure.
It exhibits excellent low-temperature impact resistance, and thus exhibits unprecedented excellent corrosion resistance over a wide temperature range. So, in particular,
It can be suitably used for coating the inner and outer surfaces of cables, metal plates and metal tubes used at extremely low temperatures.

─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hiroyuki Mimura 1 Kimitsu, Kimitsu-shi Nippon Steel Corporation Kimitsu Works (72) Inventor Shotaro Urawa 1-8, Iihara, Chiba Prefecture Ube Industries Ltd. Company Chiba Factory (72) Inventor Yasue Kamei 8-1 Goi Minami Kaigan, Ichihara City, Chiba Ube Kosan Co., Ltd. Chiba Factory (56) Reference JP 62-119245 (JP, A) JP 57 -165413 (JP, A) JP 57-53578 (JP, A) JP 7-186326 (JP, A) JP 7-186325 (JP, A) JP 7-102133 (JP, A) ) JP-B-62-2871 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) B32B 15/08 C09J 151/06

Claims (2)

(57) [Claims] 1. A polyethylene composition comprising a metal layer (A), 5 to 50 wt% of a modified polyethylene obtained by grafting an unsaturated carboxylic acid on a linear low density polyethylene, and 95 to 50 wt% of an ethylene-α-olefin copolymer. A metal laminated structure comprising an adhesive layer (B) and a polyethylene composition coating layer (C) having a density of 0.92 to 0.95 g / cm ³ comprising 80% by weight or more of high, medium and low pressure polyethylene. The molecular weight distribution (Mw / Mn) of the ethylene-α-olefin copolymer is 2.5 or less, and the melt flow ratio (MI ₁₀ / MI _2.16 ) is in the range of 5 to 15 (where MI ₁₀ is A metal laminated structure having a melt index of 190 kg at a load of 10 kg and MI _2.16 representing a melt index of 190 ° C. of a load of _2.16 kg). 2. The polyethylene composition adhesive layer (B) comprises:
A metal laminated structure comprising 50 parts by weight or less of an ethylene-propylene copolymer rubber, based on 100 parts by weight of the adhesive polyethylene composition of claim 1.