JP2000248247A - Adhesive resin composition and structured material for metal coating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an olefinic resin composition excellent in adhesive property to a metal and also in adhesion-holding property at a high temperature. SOLUTION: This adhesive resin composition contains (1) 40-88 wt.% (based on 3 components) homopolymer of propylene or its copolymer, (2) 1-10 wt.% (based on 3 components) homopolymer of propylene or its copolymer modified with an unsaturated carboxylic acid or its derivatives and (3) 7-50 wt.% (based on 3 components) poly(4-methyl-1-pentene)-based polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polypropylene-based adhesive resin composition, and more particularly, to an adhesive resin composition having excellent adhesiveness to a metal, high adhesiveness at high temperature (peeling resistance), and The present invention relates to a resin composition excellent in cathode peeling resistance, particularly to an adhesive resin composition for metal coating. The present invention also relates to a metal-coated structure in which a layer of the resin composition is provided on a metal substrate.

[0002]

2. Description of the Related Art Olefin resin-coated metal pipes are excellent in cold resistance, corrosion resistance, water resistance, weather resistance, and impact resistance. Therefore, they are used for transportation pipes for gas or liquid such as gas, oil and water. Or, it is widely used as a pipe for protecting cables.

However, since olefin resins have poor adhesion to metals, it has been already proposed to use acid-modified olefin resins having excellent adhesion to metals, for example, Japanese Patent Publication No. 1-50595. No. 100
Modified ethylene having a content of 88 to 25%, a density of 0.880 to 0.900 g / cm ³ and a melting point of 65 to 90 ° C, which is graft-modified with an unsaturated carboxylic acid or an anhydride thereof on a metal body preheated to not more than 100 ° C. A method for producing a metal body coated with an ethylene copolymer, wherein the α-olefin copolymer (A) is heated and bonded at a temperature not lower than the melting point of the copolymer is described.

[0004]

The above-mentioned acid-modified ethylene.
The α-olefin copolymer has an advantage that when used for coating steel pipes, low-temperature bonding is possible,
As is evident from the above melting point, there is a problem that adhesion retention (peeling resistance) at high temperatures is poor.

[0005] The various pipes exemplified above are generally used as buried pipes, and it is recognized that when a conventional coated metal pipe is used for this purpose, a trouble called cathode peeling often occurs. That is, when a metal tube is used as a cathode and an electrolyte is present between the cathode and an external anode, and electricity is supplied,
Peeling of the coating from the metal tube and corrosion of the surface of the metal tube progress, and this cathode peeling is considered to be a major cause of metal tube corrosion when the coated metal tube is actually buried.

Accordingly, an object of the present invention is to provide an olefin-based resin composition which is excellent in adhesiveness to metal and excellent in adhesiveness and retention at high temperatures. Another object of the present invention is to provide a resin composition which is excellent in adhesion to a metal and has excellent adhesion retention at high temperatures (exfoliation resistance) and cathodic exfoliation resistance, particularly an adhesive resin composition for metal coating. Objects and metallized structures.

[0007]

According to the present invention, (1)
Propylene homopolymer or copolymer 40 to 88
% (Based on three components), (2) 1 to 10% by weight (based on three components) of a polymer obtained by modifying a propylene homopolymer or copolymer with an unsaturated carboxylic acid or a derivative thereof, and (3) poly-4- An adhesive resin composition comprising 7 to 50% by weight (based on three components) of a methyl-1-pentene polymer is provided. The propylene copolymer used in the present invention is preferably a propylene random copolymer containing 10 mol% or less of an olefin unit having 2 or 4 to 20 carbon atoms. According to the present invention also
There is provided a metal-coated structure comprising a layer of an adhesive resin composition provided on a metal substrate. The metal tube coating material of the present invention may be used in the form of a laminate in which the layer of the adhesive resin composition is disposed on the side in contact with the metal, and the layer of propylene homopolymer or copolymer is disposed on the opposite side. preferable.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The adhesive resin composition of the present invention comprises the following three components: (1) a propylene homopolymer or copolymer, and (2) a propylene homopolymer or copolymer. A polymer modified with a saturated carboxylic acid or a derivative thereof, and (3) a poly-4-methyl-1-pentene-based polymer, wherein (1) is 40 to 88% by weight, particularly 50 to 70% by weight, based on three components. (2) 1 to 10% by weight, especially 2 to 8% by weight, and component (3) 7 to 50% by weight,
Particularly, 10 to 40% by weight is contained as an essential component.

In this adhesive resin composition, propylene homopolymer or copolymer (1) and poly-4-methyl-
A 1-pentene polymer (3) is combined with a fixed amount ratio, and a polymer (3) obtained by modifying a propylene homopolymer or copolymer with an unsaturated carboxylic acid or a derivative thereof is further added to the fixed amount. It is characterized in that they are combined in a ratio, whereby the adhesion to metal and the adhesion retention at high temperature (peeling resistance) can be improved, and the cathode peeling resistance can be improved.

When the content of the propylene homopolymer or copolymer (1) is less than the above range, the adhesion to metal tends to be significantly reduced as compared with the case where the content is within the above range. Large peeling tendency (Comparative Example 3 described later)
And 4). On the other hand, when the content of the poly-4-methyl-1-pentene-based polymer (3) is lower than the above range, the adhesive retention at high temperature (peeling resistance) is lower than in the case where the content is within the above range. In addition, the cathode peelability tends to increase (see Comparative Examples 1 and 2 described later).

The modified polymer (2) used in the present invention is an indispensable component from the viewpoint of adhesiveness to a metal. Property is obtained. That is, if the amount of the modified polymer is below the above range, the adhesion to metal tends to be unsatisfactory, while if the amount of the modified polymer exceeds the above range, the mechanical properties of the coating become insufficient, Moldability and thermal stability tend to be inferior, and it tends to be economically disadvantageous.

In the present invention, together with the modified polymer, propylene homopolymer or copolymer (1) and poly (4)
By using the -methyl-1-pentene polymer (3) at a specific quantitative ratio, the adhesion holding property at a high temperature and the cathodic peeling resistance were improved while maintaining the adhesion to a metal at an excellent level. Things.

[Adhesive Resin Composition] As the component (1): propylene homopolymer or copolymer, crystalline polypropylene and / or crystalline propylene copolymer is used. These propylene homopolymers or copolymers may have an isotactic structure or a syndiotactic structure.

The propylene homopolymer or copolymer used has a density of 0.890 to 0.920 g / cm ³ ,
In particular, it is preferably in the range of 0.900 to 0.915 g / cm ³ , while the melt flow rate (MFR)
Is from 0.1 to 80 g / 10, measured at a temperature of 260 ° C. and a load of 5 kg according to ASTM D1238.
Min, especially in the range of 0.3 to 50 g / 10 min.

In the present invention, it is preferable to use homopolypropylene, but a random or block copolymer with another olefin mainly composed of propylene is also used.
Other olefins copolymerizable with propylene include ethylene or 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-octene, Decene, 1-dodecene, 1-
Examples thereof include 1-olefins having 20 or less carbon atoms, such as hexadecene, among which copolymers with ethylene are preferably used. Such a copolymer component is usually 1
It is used in an amount of 0 mol% or less, preferably 5 mol% or less. This copolymer is preferably a random copolymer.

Component (2): The second component used in the present invention is a polymer obtained by modifying a propylene homopolymer or copolymer with an unsaturated carboxylic acid or a derivative thereof. The base polymer of the modified polymer basically has the composition and crystallinity described for the component (1). Of course, this base polymer may be the same as component (1) or different from each other.

Examples of unsaturated carboxylic acids or derivatives thereof grafted to the base polymer include maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid,
Unsaturated carboxylic acids such as citraconic acid, crotonic acid, isocrotonic acid, nadic acid, acrylic acid, methacrylic acid,
Alternatively, a derivative thereof, for example, an acid anhydride of the above-mentioned unsaturated carboxylic acid, imide, amide, ester and the like can be mentioned.

Specific examples of the derivative include maleimide, maleic anhydride, citraconic anhydride, monomethyl maleate, glycidyl maleate and the like. Among these, unsaturated carboxylic acids or acid anhydrides thereof are preferred, and maleic acid, nadic acid and their acid anhydrides are particularly preferred.

In order to produce a modified product by graft-copolymerizing a graft monomer selected from such unsaturated carboxylic acids or derivatives thereof with the homopolymer or copolymer of propylene, a conventionally known method is used. Can do
For example, a melt modification method in which a homopolymer or a copolymer of propylene is melted and a graft monomer is added to perform graft copolymerization, or a solution modification method in which a propylene homopolymer or a copolymer is dissolved in a solvent and a graft monomer is added to perform graft copolymerization is used. Can be done.

In order to efficiently graft the modifying monomer to the base polymer to obtain a homopolymer or copolymer (2) of graft-modified propylene, the reaction is preferably carried out in the presence of a radical initiator. In this case, the grafting reaction is usually carried out at a temperature of 60 to 350 ° C. The usage ratio of the radical initiator is usually in the range of 0.001 to 2 parts by weight based on 100 parts by weight of the base polymer.

Examples of the radical initiator include dicumyl peroxide, di-tert-butyl peroxide, 2,
5-dimethyl-2,5-di (tert-butylperoxy) hexyne-3,2,5-dimethyl-2,5-di (t
Organic peroxides such as tert-butylperoxy) hexane and 1,4-bis (tert-butylperoxyisopropyl) benzene are preferred.

The graft-modified polymer (2) used in the present invention is preferably modified in a modification amount of 0.01 to 10% by weight, particularly 1 to 5% by weight as graft monomer weight. When the graft modification amount is within the above range, when the metal tube is coated or laminated with the metal tube, the interlayer adhesion is good.

The acid-modified polymer (2) used in the present invention comprises:
Usually, the intrinsic viscosity as an index of the average molecular weight, that is, the intrinsic viscosity at 135 ° C. in a decalin solvent is 0.1 to 5 dl.
/ G, particularly preferably 0.2 to 2 dl / g.

Further, the acid-modified polymer (2) is usually DS
The melting point measured at 130 ° C. or higher, preferably 140 ° C.
° C or higher.

Component (3): In the present invention, component (3)
Is a homopolymer of 4-methyl-1-pentene, or 4-methyl-1-pentene and another α-olefin, for example, ethylene, propylene, and the like. -Butene, 1-hexene,
A copolymer with an α-olefin having 2 to 20 carbon atoms such as 1-octene, 1-decene, 1-tetradecene, and 1-octadecene, usually containing 4-methyl-1-pentene in an amount of 85 mol% or more, preferably 4-methyl- containing 90 mol% or more
It is a copolymer mainly composed of 1-pentene. When the amount of 4-methyl-1-pentene is within this range, the composition obtained is excellent in heat resistance, adhesive strength and cathodic peeling resistance.

The 4-methyl-1-pentene polymer (3) used in the present invention has a melt flow rate (MFR) of A
According to STM D1238, temperature 260 ° C, load 5kg
Is preferably in the range of 1 to 400 g / 10 min, particularly preferably in the range of 10 to 300 g / 10 min.

Composition and Preparation Thereof: The adhesive resin composition of the present invention comprises the above three components, namely (1) propylene homopolymer or copolymer, and (2) propylene homopolymer or copolymer. Is modified with an unsaturated carboxylic acid or a derivative thereof, and (3) a poly-4-methyl-1-pentene-based polymer, and
%, Especially 50 to 70% by weight, and (2) is 1 to 10%.
%, Especially 2 to 8% by weight, and the component (3) as an essential component in a ratio by weight of 7 to 50% by weight, especially 10 to 40% by weight.

There is no particular order in the mixing of the three components, and all the three components may be mixed at the same time. Alternatively, any two components may be mixed first, and then the remaining one component may be mixed. Good. The composition may be a dry blend of the above three components or a melt blend. Dry blending can be performed using, for example, various mixers such as a tumbler, ribbon blender, conical blender, and Henschel mixer, while melt blending can be performed using a single-screw or twin-screw extruder, a kneader, a Banbury mixer, a roll, etc. It can be performed using: Generally, it is preferred to dry blend the three components followed by melt blending.

The composition used in the present invention contains a compounding agent for resins known per se, for example, a filler, a colorant, a heat stabilizer,
Weathering stabilizers, antioxidants, antioxidants, antistatic agents, lubricants such as metal soaps and waxes, modifying resins or rubbers,
A well-known resin compounding agent such as sulfur for chlorine-resistant water can be compounded according to a well-known formulation.

[Coating Structure and Method for Producing the Same] The adhesive resin composition (A) of the present invention can be used for coating a metal substrate such as a metal tube in the form of a single layer, or other resins such as propylene. It can also be used for coating a metal substrate such as a metal tube in the form of a laminate with the system polymer (B). In the case of the latter laminated coating, another resin (B) such as a propylene-based polymer is located on the side where the adhesive resin composition (A) of the present invention is in contact with the metal substrate, that is, on the inner layer side. It is better to do it.

As another resin (B) used in combination with the adhesive resin composition (A) of the present invention, a propylene-based polymer is used in terms of mechanical properties, heat resistance, environmental stress cracking resistance and the like. As the propylene-based polymer, those already described as the component (1) of the adhesive resin composition, that is, propylene homopolymers and copolymers are suitably used. Of course, the propylene-based polymer applied as the outer layer and the component (1) of the adhesive resin composition may be the same or different from each other. It goes without saying that other resin (B) can also be blended with a resin compounding agent known per se.

The coating material used in the present invention varies depending on the use of the coated metal structure and the required degree of coating.
Generally 10 μm to 50 mm, especially 100 μm to 10 mm
mm. When the coating material is a laminate, the ratio of the thickness of the adhesive resin composition layer (A) to the thickness of the other resin layer (B) is as follows: A: B = 1: 100 to 1: 5, especially 1 : 50 to 1:10.

The metal substrate is coated with the lining by extrusion coating the adhesive resin composition or a laminate of the adhesive resin composition and another resin on the metal substrate in a molten state. . That is, the adhesive resin composition is kneaded in an extruder, and the kneaded product is passed through a die head,
Melt extrusion on metal substrate. When using a laminate,
It is preferable to use a number of extruders corresponding to the types of resin layers of the laminate, knead the respective resin layers in this extruder, and then melt-extrude the respective resin layers in a laminated state through a multilayer dies.
When the metal substrate is a metal tube, it is preferable to use a cross die head as the die head and extrude the resin melt around the metal tube.

The metal substrate used in the present invention has a plate shape, a cylindrical shape, a tubular shape, a rod shape or other shapes made of iron, steel, aluminum, nickel, cobalt, tin, zinc or an alloy containing these as a main component. Things. The present invention
Particularly useful for lining coating of metal pipes, for example, buried pipes such as sewer pipes, civil engineering / agricultural pipes, and water pressure pipes such as water pipes, gas pipes, hot water pipes, hydraulic pneumatic pipes, and air pressure pipes. Can be applied to The material of the pipe is generally steel or cast iron, but galvanized pipe, copper pipe,
Further, the present invention is of course applicable to light metal pipes such as aluminum and alloys thereof.

When the metal substrate is coated with the adhesive resin composition, it is sufficient that the surface of the metal body is clean, but it is more effective to perform a blast treatment, an acid washing treatment, a chemical conversion treatment, or the like. . Although not usually required, a primer such as an epoxy resin-based adhesive, particularly a low-temperature curing type epoxy resin-based adhesive may be applied to the surface of the metal body in advance.

It is also advantageous to preheat the metal substrate before extrusion coating in terms of workability and to increase the adhesive strength. In general, the metal substrate is heated to 100 ° C. or lower, particularly 40 to 90 ° C. It is desirable to heat to a temperature of ° C. By extrusion-coating the adhesive resin composition of the present invention on the metal substrate thus preheated, a metal-coated structure having excellent adhesive strength can be obtained without troublesome operations such as reheating and melting. it can. Thus, according to the present invention, a sufficient adhesive strength can be obtained even after the laminate is cooled immediately after the resin composition is coated on the metal substrate.

The method of coating the metal substrate with the adhesive resin composition of the present invention is not limited to the extrusion coating method. For example, various other known methods can be applied. Using a resin composition powder of the electrostatic coating method,
A method of coating by a fluid immersion method or the like, a method of fusing a previously formed film or sheet adhesive resin composition or a laminate thereof to a metal body, and the like can also be used.

[0038]

The present invention will be described with reference to the following examples.

Example 1 5 parts by weight of a modified polypropylene (hereinafter abbreviated as modified PP) obtained by grafting 2% by weight of maleic anhydride onto polypropylene (melt index 12, density 0.91 g / cm ³ ), Index 0.5, density 0.91 g / cm ³ ,
60 parts by weight of 4-methylpentene-1 polymer (melt index: 20, density: 0.1).
89 g / cm ³ , hereinafter abbreviated as PMP-1), 35 parts by weight, and mixed by a tumbler blender.
Granulation was performed at 0 ° C. to obtain a compound (hereinafter, abbreviated as CON-1). Subsequently, polypropylene (melt index
3, the density of 0.91 g / cm ³ ) and the CON obtained above
-1 was extrusion-coated on the surface of a 45 cm long steel pipe (SGP15A, surface bite polished product) preheated to 80 ° C. with a multilayer round die, and after 1 second of coating, water-cooled to produce a two-layer coated steel pipe. . Next, the adhesive strength of the coated steel pipe was measured by the following method.

Adhesive strength (kg / cm): 10 c of coating material
After partially peeling off with a width of m, a tensile tester (Instron universal tester TMM type 100 kg type, manufactured by Instron)
The adhesive strength was measured by peeling the coating material by a 90 ° peeling method at a peeling rate of 50 mm / min in an atmosphere of 23 ° C., 50 ° C., 80 ° C., and 100 ° C., respectively. Table 1 shows the results.

Further, a cathode peel test of the coated steel pipe was measured by the following method. An initial hole having a diameter of 3.2 mm was opened in the resin coating layer and immersed in a 3% NaCl electrolyte. Two types of electrolyte solutions, 65 ° C. and 23 ° C., were prepared. -1.
An applied voltage of 5 V was applied, the sample was taken out after a certain period of time, the coating resin near the initial hole was removed, and the peeled distance (determined by the discolored distance) was measured.

Examples 2 to 4 Two-layer coated steel pipes were produced in the same manner as in Example 1 except that the ratio of PP-1 to PMP-1 was changed to Table 1. Next, the adhesive strength and the cathode peel test of the coated steel pipe were measured in the same manner as in Example 1. Table 1 shows the results.

Comparative Examples 1 to 4 Two-layer coated steel pipes were produced in the same manner as in Example 1 except that the ratio of PP-1 to PMP-1 was changed to Table 2. Next, the adhesive strength and the cathode peel test of the coated steel pipe were measured in the same manner as in Example 1. Table 2 shows the results.

[0044]

Table 1 Unit Example 1 Example 2 Example 3 Example 4 Composition Modified PP parts by weight 5 5 5 5 PP-1 parts by weight 85 75 65 55 PMP-1 parts by weight 10 20 30 40 Adhesive strength 23 ° C Kg / cm 22 22 21 23 50 ° C Kg / cm 15 17 18 19 80 ° C Kg / cm 12 14 16 17 100 ° C Kg / cm 10 12 13 15 Cathode peel distance 23 ° C, 28 days mm 0.2 0.1 0.6 1.3 65 ° C, 3 days mm 0.5 0 0.1 0 65 ° C, 8 days mm 1.2 1.5 1.3 1.1

[0045]

[Table 2] Unit Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Composition Modified PP parts by weight 5 5 5 5 PP-1 parts by weight 95 90 25 5 PMP-1 parts by weight 0 5 70 90 Adhesive strength 23 ° C. Kg / cm 23 23 6 4 50 ° C Kg / cm 12 14 5 4 80 ° C Kg / cm 9 10 4 4 100 ° Kg / cm 6 8 5 3 Cathode peel distance 23 ° C, 28 days mm 5 6 3 4 65 ° C, 3 days mm 6 9 5 6 65 ° C, 8 days mm 10 13 8 10

[0046]

According to the present invention, (1) a homopolymer or copolymer of propylene, (2) a polymer obtained by modifying a homopolymer or copolymer of propylene with an unsaturated carboxylic acid or a derivative thereof, and (3) An olefin-based resin composition which is excellent in adhesiveness to metal and excellent in adhesiveness and retention at high temperature by combining a poly-4-methyl-1-pentene polymer at a specific quantitative ratio. Things can be provided. This composition is excellent in adhesiveness to metal, and also excellent in adhesive retention at high temperature (peeling resistance) and cathodic peeling resistance, and is used as a metal-coated structure, particularly as a coated metal tube. Useful for

Claims (5)

[Claims] (1) 40 to 88% by weight (based on three components) of (1) a propylene homopolymer or copolymer, and (2) a propylene homopolymer or copolymer modified with an unsaturated carboxylic acid or a derivative thereof. Characterized in that it contains 1 to 10% by weight (based on three components) of the obtained polymer and 7 to 50% by weight (based on three components) of (3) a poly-4-methyl-1-pentene polymer. Resin composition. 2. The adhesive resin composition according to claim 1, wherein the propylene copolymer is a propylene random copolymer containing 10 mol% or less of olefin units having 2 or 4 to 20 carbon atoms. 3. A metal-coated structure comprising a layer of the adhesive resin composition according to claim 1 provided on a metal substrate. 4. A (A) layer of the adhesive resin composition according to claim 1 or 2, and (B) a layer of a propylene homopolymer or copolymer are provided on a metal substrate in this order. A metal-coated structure, comprising: 5. The metal-coated structure according to claim 3, wherein the metal substrate is a metal tube.