JPS62119247A - Modified polyethylene composition - Google Patents

Abstract

PURPOSE:To obtain a composition having excellent mechanical strength and exhibiting high adhesivity even by lowering the preheating temperature of adherend, by compounding a specific modified polyethylene with unmodified polyethylene, (modified) polyisobutylene and an inorganic filler. CONSTITUTION:The objective composition can be produced by compounding (A) 10-94(wt)% modified polyethylene produced by reacting a linear low-density polyethylene having a melt index of 7-50g/10min with an unsaturated carboxylic acid (derivative) with (B) 0-84% unmodified polyethylene, (C) 5-50% polyisobutylene and/or modified polyisobutylene produced by reacting a polyisobutylene with an unsaturated carboxylic acid (derivative) and (D) 1-30% inorganic filler. The unsaturated carboxylic acid (derivative) is acrylic acid, methacrylic acid, etc., or its anhydride, etc., and its amount added to the polymer is preferably 0.01-3%.

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 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-a-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 in which metal foil is laminated with sheets of modified polyethylene and polyisoptylene interposed therebetween (Japanese Unexamined Patent Publication No. 56-93541), etc. 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 ( JP-A-57-165415) and compositions modified by reacting a mixture of specific linear low-density polyethylene and synthetic rubber with an unsaturated carboxylic acid or a derivative thereof (
JP-A-57-165469) 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, unless the modified polyethylene or its composition is wetted onto an adherend at a temperature equal to or higher than the melting point of the resin, sufficient adhesiveness will not be exhibited. 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. In order to avoid peeling or peeling, 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 before, the present inventors first developed a modified linear low-density polyethylene having a specific melt index and polyisobutylene. We have proposed a modified polyethylene composition (Japanese Patent Application No. 60-99621) consisting of:

However, although this composition has sufficient adhesion even when the preheating temperature is lowered, it has poor mechanical strength after cooling, such as threading of pipe ends when used for coating steel pipes. Alternatively, there was still room for improvement in practical strength against the torque received 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. The object of the present invention is to provide a modified polyethylene acid 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
It has been discovered that a composition comprising a linear low density polyethylene modified product, polyisobutylene and/or sono-modified product, and an inorganic filler blended in a specific amount achieves the object of the present invention, and the present invention has been accomplished by completed.

That is, the present invention provides (A) a modified polyethylene 10-9 obtained by reacting a linear low-density polyethylene with an MI of 7-509/10 with a monounsaturated carboxylic acid or a derivative thereof;
4% by weight, 03) Unmodified polyethylene 0-84% by weight
, (C) polyisobutylene and/or 5 to 50% by weight of a modified polyisobutylene obtained by reacting the polyisobutylene with an unsaturated carboxylic acid or a derivative thereof, and (D)
The gist of the invention is a modified polyethylene composition comprising 1 to 30% by weight of an inorganic filler.

The linear low density polyethylene (hereinafter referred to as LLDPg) used in the present invention has an MI of 7 to 5 CM'/10 minutes,
In the presence of a chromium-based or Ziegler-based catalyst, ethylene and α-olefins, such as butene-1, pentene-1, hexene-1,
4-methylpentene-1, heptene-1, octene-1
It is manufactured by copolymerizing with selected materials such as
MI is 7-505F/10 minutes, preferably 8-20
It is 9/10 minutes. The α-olefin is generally contained in an amount of 3 to 20% by weight. These LLDP
In g, the density polymerized by low pressure gas phase method is CL905
~α950t/cWs.

Weight average molecular weight Mw/number average molecular weight Mn is 3 to 12
Preferably. MI of above LLDPE is 7f/
If the heating time is less than 10 minutes, the adhesion at a low preheating temperature of the adherend will be insufficient, and if the heating time exceeds 10 minutes, the strength of the resin will be insufficient. Also, MI 7-50 f7
Polyethylene other than 10-minute LLDFE does not have sufficient adhesion to the adherend and its durability.

The unmodified polyethylene used in the present invention is an ethylene homopolymer or a copolymer of ethylene with an ethylene content of 50% by weight or more and an α-olefin or a vinyl monomer, and preferably has a MICL of 1 to 50 f/10 min. Things can be given. For example, linear low density polyethylene (LL
DPg), low density polyethylene (LDPE)
), medium density polyethylene (hereinafter referred to as MDPE), and high density polyethylene (hereinafter referred to as HDPR), among which LLDPIIC is preferred. Note that each unmodified polyethylene may be used in combination.

Commercially available polyisobutylene can be used as the polyisobutylene used in the present invention, but Mooney viscosity (ML1+4.100℃, JI
It is preferable that the crystallinity (S K-6400 or less) is 10 to 150 and the crystallinity (X-ray diffraction method) is 30% or less. Also,
Synthetic rubbers other than polyisobutylene do not have sufficient adhesion to adherends.

Examples of inorganic fillers used in the present invention include calcium carbonate, talc, clay, epicenter, calcium sulfite, calcium sulfate, calcium silicate, glass powder, glass fiber,
Examples include asbestos, gypsum fiber, or a mixture thereof.

The shape and size of these inorganic fillers are not particularly limited, but fine particles with a particle size of 50 μm or less are desirable. By blending this inorganic filler, the solid elastic modulus of the composition increases, and the practical strength can be improved.

Examples of unsaturated carboxylic acids used in the present invention include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, endo-pyclicol 2,2
．． 1]-1,4゜5.6,7,7-hexachloro-5-
Examples include hebutene-2,3-dicarboxylic acid, endo-cyclo[2,2,1]-]5-hepten-2,5-dicarboxylic acid, cis-4-cyclohexene-1°2-dicarboxylic acid, and the like. Further, examples of derivatives of unsaturated carboxylic acids include acid anhydrides and esters, such as maleic anhydride, citraconic anhydride, endo-bicyclo-(
2,2゜1)-1,4,5,6,7,7-hexachloro-5-heptene-2,3-dicarboxylic anhydride, endo-
pcyclo(2,2,1)-5-hebutene-2,3-
Dicarboxylic anhydride, cis-4-cyclohexene-1,2
- Dicarboxylic anhydride, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, maleate ester (monoester, diester), etc.

Various known methods can be used to react LLDPg or polyinobutene with an unsaturated carboxylic acid or a derivative thereof. For example, LLDPE or polyisobutylene and an unsaturated carboxylic acid or a derivative thereof are reacted in the presence or absence of a solvent with an organic peroxide initiator, such as ditert-butyl peroxide, dicumyl peroxide, benzoyl bicarbonate. Side, 2,5-dimethyl-2
, 5-di(tert-butylperoxy)-hexane-3,2,5-dimethyl-2,5-di(tert-butylperoxy)-hexane, etc., and mixer such as a shell mixer or ribbon blender. This mixture is heated to a temperature higher than the melting point of polyethylene or polyisobutylene using a Banbury Mixer-1 single-screw or multi-screw extruder.
Melt and knead at a temperature of 80°C or less.

Alternatively, LLDPE or polyisobutylene may be dissolved in a solvent, and an unsaturated carboxylic acid or a derivative thereof 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 or polyisobutylene is 0.01 to 3% by weight.
is preferred. Therefore, the amount of the reaction initiator of unsaturated carboxylic acid or its derivative and organic peroxide should be
Unsaturated carboxylic acid or its derivative (1L05 to 5 parts by weight,
1001 to 05 parts by weight of the reaction initiator is preferred. Note that if the content of the unsaturated carboxylic acid or its derivative in the modified polyethylene or modified polyisobutylene is less than 101% by weight, the strong adhesive strength of the present invention cannot be obtained, while if it exceeds 3% by weight, the adhesive strength 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 modified polyethylene composition of the present invention comprises modified polyethylene in an amount of 10 to 94% by weight, preferably 20 to 50% by weight.
, unmodified polyethylene 0 to 84 wt #%, preferably 0 to 84 wt.
64% by weight and polyisobutylene and/or modified polyisobutylene 5-50% by weight, preferably 10-40% by weight x inorganic filler 1-50% by weight, preferably 1-10% by weight
Consists of X. If the content of modified polyethylene, unmodified polyethylene and/or modified polyisobutylene is outside the above range, adhesion to adherends with low preheating temperatures will be insufficient. Furthermore, if the content of the inorganic filler is less than 1% by weight, the mechanical strength will be insufficient, while if it exceeds 30% by weight, the adhesiveness 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, an inorganic filler, 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, the mixture is premixed using a Henschel mixer, a ribbon blender, a ribbon blender, etc.
+ A method in which the composition is melt-kneaded using a mixer, roll, extruder, etc. at a temperature from above the melting point of the composition to 210° C. or below 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 includes a mixture of LLDP]liX, polyisobutylene, and an inorganic filler in the above-mentioned mixing ratio.
It may also be one obtained by reacting an unsaturated carboxylic acid or a derivative thereof. Furthermore, unmodified polyethylene 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, plasticizers, etc. 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 metals used in the laminate using the modified polyethylene composition of the present invention include iron, aluminum, copper, zinc, nickel, tin, stainless steel, brass, tinplate, galvanized iron, etc. in the form of plates, dips, cylinders, tubes, etc. Examples include lines or other shapes. 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 polybutylene, or copolymers thereof. , polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyesters such as polyethylene terephthalate and polybutylene terephthalate, Examples include vinyl 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 thermo-compression bonding, a method of laminating it outside the mold, a method of co-extruding it inside a die, and a method of laminating it in the form of a tube. Known methods such as extrusion coating or powder coating in a shape or sheet 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 mentioned above. Various combinations can be made depending on the situation.

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.

The base metal tube is cleaned by surface treatment such as shot blasting, grid blasting, or pickling. Further, it is desirable to apply an epoxy adhesive or the like as a primer treatment thereon in order to obtain a resin layer with strong 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.
The composition is heated to 0°C and applied to the outer surface of the metal tube at a temperature above the melting point.
Preferably, it is coated by extruding it into a tube or winding it into a sheet at a temperature of 200 to 230°C. The thickness of the coating varies depending on the purpose, but is usually about [L3 mm]. Furthermore, an exterior material, such as polyolefin, preferably high-density polyethylene, is applied thereon to a melting point above the melting point, preferably 20 to 2
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 21
That's about it. 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 this metal tube is coated with the composition and polyolefin in the same manner as described above.

Effects of the Invention Compared to already proposed modified polyethylene compositions, the composition of the present invention can heat adherends such as metals and thermoplastic resins from a much lower preheating temperature to a higher temperature. Has excellent adhesive 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.

Furthermore, the composition of the present invention has improved mechanical strength after adhesion compared to conventional compositions, so it has practically sufficient strength, such as thread cutting resistance and pipe wrench torque resistance, in coated steel pipes, for example.

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 coatings on the inner and outer surfaces of steel pipes and cast iron pipes, steel plates, metal foils, 111m cables, @ wires, etc., tank linings, and multilayer films with various thermoplastic resins, sheets, bottles, Examples include laminates such as containers.

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 1i, Il,
The test method is as follows.

(1) Mr ASTM D-1258K (190℃, z16or)
(2) Peel strength pickled steel plate (ss-41) 100 x 101
After electrolytically degreasing 00XIL3, it was preheated to a predetermined temperature on a heating plate, and a sheet (thickness t) of the composition of the present invention was placed on top of this.
A test piece was prepared by heating a sheet of high-density polyethylene (thickness: 3 mm) to 220° C. to melt and fuse the sheet, and after leaving it for 10 seconds, it was cooled by immersing it in running water. The resin layer of the test piece was cut into a width of 10 g and a portion was peeled off to provide a gripping margin.
Using an Instron tensile tester, the peeling rate was SO,/min at 9
0° peel strength was measured at 23°C and 50°C.

(3) Tensile modulus JrS K 705 (Crosshead speed α5m/min) (4) Shear adhesive strength JIS K 6850 (5) Thread cutting test Japan Water Works Association standard JWW AK 132-1982 (
5G described in polyethylene powder-lined steel pipes for water supply)
Thread cutting method using P-PC pipe machine,
Measurements were taken while changing the ambient temperature, and the maximum temperature at which thread cutting was possible was determined.

(6) Tighten with a pipe wrench using a torque test, using the force and pipe wrench specified in Japan Water Steel Pipe Association Standard W8-033-84 (Polyethylene powder-lined steel pipes for water supply, single-layer polyethylene coating on the outside), and tightening with a vise. The fixed coated steel pipe was tightened with a pipe wrench, torque was applied, and the torque when the resin layer deformed was measured. The ambient temperature was kept at 10°C.

Examples 1 to 9, Comparative Examples 1 to 4 100 parts of each LLnpg (comonomer: butene-1) with different MI and 2 parts of oleic anhydride [1L and 45-
30,025 parts of dimethyl-2,5-di(tert-butylperococo)-hexyne were blended and mixed in a Henschel mixer, and this mixture was fed to a 651φ screw extruder at a set temperature of 250°C and a screw rotation speed. 6 Or-
Maleic anhydride-modified LLDP11i was melt-kneaded at pm.
: Got. This modified u, vpg and polyisobutylene [manufactured by Esso Chemical Co., Ltd., Vistanetx MML-80 (trade name)]
], unmodified polyethylene, and an inorganic filler were blended in the proportions shown in Table 1, and heated and melted and kneaded at 230°C to obtain a composition.

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, when LLDPE with MI 5 f710 minutes was used, when ethylene butene rubber [manufactured by Mikata Petrochemical Co., Ltd., A-4085 (trade name) (hereinafter referred to as EBR) was used instead of polyisobutylene, and when inorganic filler Even in the case where the composition was not added, a composition was prepared and a laminate was prepared in the same manner as in Example 1, and each physical property was measured, and the results are also shown in Table IK.

Example 10, Comparative Example 5 A 501φ8()P 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. The modified polyethylene composition used in step 5 was heated to a resin temperature of 22 mm using an extruder with a diameter of 65 mm.
The tube was extruded and coated at 0° C. to a thickness of 1 mm at a line speed of 1 m/min, and cooled in a water tank at a distance of 3 z from the die to obtain a resin-coated steel tube. 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 LLDPE used in Example 4, the inorganic filler and polyisobutylene in the proportions shown in Table 3, maleic anhydride was added to 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 peel strength was measured, and the results are shown in Table 5.

Table-5

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
4% by weight, (B) unmodified polyethylene 0 to 84% by weight,
(C) Modified polyethylene consisting of 5 to 50% by weight of polyisobutylene and/or modified polyisobutylene obtained by reacting the polyisobutylene with an unsaturated carboxylic acid or its derivative, and (D) 1 to 30% by weight of an inorganic filler. Composition.