KR102350805B1 - Modified polyethylene resin powder composition for inner surface coating of steel pipe for water - Google Patents

Abstract

The present invention relates to a modified polyethylene powder resin composition for coating the inner surface of a water steel pipe, and more specifically, to an improved modified polyethylene powder resin composition for coating the inner surface of a water steel pipe, in which a decrease in adhesion and mechanical properties of a coating layer is prevented when an end of the modified polyethylene powder coated on the inner surface of the water steel pipe is expanded at room temperature. The present invention can provide a coating layer that can prevent a decrease in physical properties such as adhesion of an inner coating layer even when an end of the water steel pipe is expanded by using a low-density thermoplastic elastomer excellent in ductility at room temperature, metal oxide, and the like in an efficient mixing ratio.

Description

Modified polyethylene resin powder composition for inner surface coating of steel pipe for water}

The present invention relates to a modified polyethylene powder resin composition for coating the inner surface of a steel pipe for water service, and more particularly, to a water service that does not reduce the adhesion and mechanical properties of the coating layer when the end of the modified polyethylene powder coated on the inner surface of the water service pipe is expanded at room temperature. It relates to an improved modified polyethylene powder resin composition for inner coating of steel pipes.

Steel pipe is an optimal product for fluid transport and is evaluated as an excellent pipe structure by providing excellent external pressure strength and structural stability, durability, economy, and convenient construction when used as a pipe for waterworks civil engineering and industrial offshore plant pipe.

Steel pipe is coated with epoxy or polyethylene fluorine on the inside to prevent corrosion. Coated steel pipe is used for water supply pipe and gas pipe buried underground in civil engineering field, supply of agricultural and industrial water, and chemical plant pipe.

If the inner surface of the water pipe is coated with modified polyethylene powder, it has excellent corrosion resistance and is widely used as a method to maintain clean water quality.

However, when mechanical force is applied at room temperature to expand the tube, the adhesion and mechanical properties of the modified polyethylene layer coated therein are deteriorated, so it is necessary to improve these problems.

Republic of Korea Registration No. 10-0841607 (June 30, 2008) Republic of Korea Registration No. 10-0855751 (August 26, 2008)

The present inventors solve the problems of the prior art accompanying the expansion of the steel pipe for water supply, and apply mechanical force at room temperature to prevent the deterioration of the adhesion and mechanical properties of the modified polyethylene layer coated therein when the steel pipe for water supply is expanded. As a result of intensive research in order to provide a powder resin composition with excellent physical properties, it was found that the modified polyethylene powder resin composition for inner coating of a steel pipe for water supply manufactured as described below can satisfy the above requirements, and completed the present invention came to

Accordingly, an object of the present invention is to provide a modified polyethylene powder resin composition for coating the inner surface of a steel pipe for water service in which the problem of deterioration of physical properties such as adhesion of the inner surface coating layer when the end of the steel pipe for water service is expanded is improved.

The above object of the present invention is

In the modified polyethylene powder resin composition for inner surface coating of steel pipe for water supply,

100 parts by weight of maleic anhydride-grafted modified polyethylene powder;

5 to 40 parts by weight of a thermoplastic elastomer; and

SiO ₂ , TiO ₂ , MgO, or a metal oxide selected from the group consisting of 0.1 to 3 parts by weight of a metal oxide selected from the group consisting of; can

According to the present invention, by using a low-density thermoplastic elastomer excellent in ductility at room temperature and metal oxide in an efficient mixing ratio, even when the end of a steel pipe for water supply is expanded, physical properties such as adhesion of the inner coating layer are reduced. can

The present invention, in one aspect,

In the modified polyethylene powder resin composition for inner surface coating of steel pipe for water supply,

100 parts by weight of maleic anhydride-grafted modified polyethylene powder;

5 to 40 parts by weight of a thermoplastic elastomer; and

SiO ₂ , TiO ₂ , MgO, or a metal oxide selected from the group consisting of 0.1 to 3 parts by weight of a mixture thereof; provides a modified polyethylene powder resin composition for inner surface coating for the end expansion of the steel pipe for water service, characterized in that it contains.

The present invention, in a further aspect,

The maleic anhydride-grafted modified polyethylene powder has a melt index (190° C.) of 3 to 6 g/10 min, a density of 0.918 to 0.925 g/cm 3 , 99% by weight of a polyethylene homopolymer, 0.05% by weight of maleic anhydride, and 1 It provides a modified polyethylene powder resin composition for inner surface coating for end expansion of a steel pipe for water service, characterized in that it contains 0.95 wt% of a primary oxidation stabilizer.

The present invention, in another further aspect,

The thermoplastic elastomer has a melt index of 5.0 g/10 min. and a density of 0.868 g/cm 2 of a thermoplastic polyolefin rubber (POE). Provide a modified polyethylene powder resin composition for inner surface coating for end expansion of steel pipe for water use do.

The present invention, in another further aspect,

Additionally, based on 100 parts by weight of the maleic anhydride-grafted modified polyethylene powder, 0.01 to 0.05 parts by weight of at least one anti-blocking agent selected from the group consisting _{of kaolin, calcium carbonate (CaCO 3 ), talc, aluminum silicate and silicon beads.} and 0.001 to 0.05 parts by weight of a slip agent consisting of an acrylate oligomer having a weight average molecular weight of 1,000 to 100,000.

Hereinafter, the modified polyethylene powder resin composition for inner surface coating for expanding the end of the steel pipe for water use according to the present invention will be described in more detail.

The terms or words used in the present specification and claims are not to be construed as limited in their ordinary or dictionary meanings, and on the principle that the inventor can appropriately define the concept of the term in order to best describe his invention. It should be interpreted as meaning and concept consistent with the technical idea of the present invention.

Therefore, since the embodiments described herein and the configurations shown in the drawings are only the most preferred embodiment of the present invention, it is understood that there may be various equivalents and modifications that can be substituted for them at the time of the present application. shall.

The modified polyethylene powder resin composition for inner surface coating for end expansion of a steel pipe for water use according to the present invention is based on a modified polyethylene powder grafted with maleic anhydride as a base, and a low-density thermoplastic elastomer excellent in ductility at room temperature and a metal oxide, etc., are used in an efficient mixing ratio By doing so, the problem that physical properties such as adhesion of the inner surface coating layer is reduced when the end of the steel pipe for water supply is expanded is improved.

The modified polyethylene powder resin composition for inner surface coating for end expansion of the steel pipe for water service according to the present invention contains the maleic anhydride-grafted modified polyethylene powder, a thermoplastic elastomer, and a metal oxide in a preferable mixing ratio, thereby providing desired physical properties. .

The modified polyethylene powder grafted with maleic anhydride used as the base may preferably have a melt index (190° C.) of 3 to 6 g/10 min and a density of 0.918 to 0.925 g/cm 3 .

In particular, a polyethylene homopolymer (Cas No. 9002-88-4) 99% by weight, maleic anhydride (Cas No. 108-31-6) 0.05% by weight and 0.95% by weight of the primary oxidation stabilizer can be preferably used. and it can be obtained under the product name NB870PD (manufacturer: Woosung Chemical Co., Ltd., located in Yeongcheon, Gyeongbuk).

The thermoplastic elastomer may preferably have a density of 0.89 g/cm 3 or less. In particular, it is more preferable that the melt index (190° C.) is 4 to 6 g/10 min, and the density is 0.86 to 0.89 g/cm 3 .

The most preferable thermoplastic elastomer is a thermoplastic polyolefin rubber (POE) having excellent ductility and low shrinkage at room temperature, and a melt index of 5.0 g/10 min and a density of 0.868 g/cm 2 can be used, Product name: ENGAGE™ 8200 Polyolefin Elastomer (CAS No. 26221-73-8, manufactured by DuPont DOW Elastomers).

The thermoplastic elastomer is preferably included in an amount of 5 to 40 parts by weight, preferably 10 to 30 parts by weight, more preferably 20 parts by weight based on 100 parts by weight of the maleic anhydride-grafted modified polyethylene powder.

If the content of the thermoplastic elastomer is out of the above range, there may be a problem in that the adhesive strength of the coating layer is significantly lowered.

The metal oxide is preferably used in an amount of 0.1 to 3 parts by weight based on 100 parts by weight of the maleic anhydride-grafted modified polyethylene powder selected from the group consisting _{of SiO 2} , TiO _{2 , MgO or a mixture thereof, and used before and after 1 part by weight} It may be more preferable to

The modified polyethylene powder resin composition for inner surface coating for end expansion of the steel pipe for water supply of the present invention may further include additives such as an anti-blocking agent and a slip agent in order to double the functionality.

The anti-blocking agent is a component for preventing blocking that sticks to each other and interferes with operation, and may preferably contain 0.01 to 0.05 parts by weight based on 100 parts by weight of the maleic anhydride-grafted modified polyethylene powder.

The antiblocking agent can be suitably applied in the present invention as long as it is commonly used. Examples include, but are not limited to, AB1305PM3 manufactured by Jungil Pracom, kaolin, calcium carbonate CaCO ₃ , talc, aluminum silicate, and silicon beads. These antiblocking agents can be used independently, of course, 2 or more types can also be mixed and used for it.

The slip agent is a component that exudes to the surface during or immediately after processing and acts as a lubricating component necessary to reduce the coefficient of friction. can

The slip agent can be suitably applied in the present invention as long as it is commonly used. For example, but not limited thereto, it may include an acrylate oligomer. Examples of suitable acrylate oligomers include those having a weight average molecular weight of about 1,000 to 100,000.

Preferred acrylate oligomers are polyester (meth) acrylate, urethane (meth) acrylate, alkoxylated (meth) acrylated oligomer, epoxy (meth) acrylate, amination (meth) acrylate, (meth) acrylated (meth) acrylate ) acrylics, or a combination of two or more thereof.

Examples of suitable commercially available acrylate oligomers include, for example, at least one selected from the group consisting of acrylate oligomers under the trademark SR454®, SR494®, SR9020®, SR9021® or SR9041® manufactured by the Sartomer company. These may be used alone or in combination.

If the content of the additive is out of the above range, the anti-blocking property and slip property may not be sufficient, and adhesive performance and mechanical properties may be deteriorated.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples. However, these examples are intended to illustrate the present invention with specific examples, and are not intended to limit the present invention thereby.

Examples 1 to 4 and Comparative Examples: Preparation of modified polyethylene powder resin composition

Based on 100 parts by weight of the maleic anhydride-grafted modified polyethylene powder, the thermoplastic elastomer, metal oxide and additives are put into a twin screw extruder based on the following mixing ratio (based on parts by weight), and then melted at about 500 rpm to melt the end of the steel pipe for water supply. A modified polyethylene powder resin composition for inner surface coating for tube expansion was prepared. As a comparative product, only maleic anhydride-grafted modified polyethylene powder was used.

ingredient content Example 1 Example 2 Example 3 Example 4 Comparative Example 1 base NB870PD) 100 100 100 100 100 POE (ENGAGE™ 8200 ) 20 - 20 20 - Metal oxide (SiO ₂ ) - One One One - Anti-blocking agent (AB1305PM3) - - - 0.05 - Slip agent (SR9021®) - - - 0.005 -

Test Example 1: Adhesion test of coating layer

A test piece of a steel pipe for water supply was coated to a thickness of 0.1 mm using the composition obtained in Examples 1 to 4 and Comparative Example, and the end portion was expanded twice, and then the adhesion of the coating layer was compared, and the results are shown in the table. 2 is shown.

Adhesion (kgf/cm) before expansion After 1st visit After the 2nd expansion comparative example 21.5 13.4 8.2 Example 1 23.6 16.5 14,4 Example 2 21.8 13.7 8.5 Example 3 26.8 21.5 20.2 Example 4 27.3 22.6 20.8

From the above test results, in the case of Example 3, the adhesive force was maintained at 20.2 kgf/cm even after the second expansion, and in the case of Example 4, it was maintained at 20.8 kgf/cm, which satisfies the construction standards.

Test Example 2: Mechanical Elongation Test

A test piece of a steel pipe for water supply was coated to a thickness of 1.0 mm using the composition obtained in Examples 1 to 4 and Comparative Example, and the extension of the coating layer was compared in accordance with KS D3589 regulations after performing pipe expansion at the end a second time. , the results are shown in Table 3.

Elongation (%) before expansion After 1st visit After the 2nd expansion comparative example 700 600 450 Example 1 730 620 530 Example 2 710 640 510 Example 3 850 720 680 Example 4 870 760 720

From the test results, the elongation of the comparative sample was at 700%, and the elongation was at the level of 600% of the primary expanded tube portion and 450% of the second elongated tube portion depending on the area of expansion, but the sample of Example 3 had an elongation of 850% at the area of expansion Accordingly, the elongation showed the level of 720% of the first expanded part and 680% of the second expanded part, and the sample of Example 4 had an elongation of 870%, and the elongation was 760% of the first expanded part, 720% of the second expanded part, depending on the part of the expansion. % level, indicating satisfactory results.

As can be seen from the above test results, the powder resin compositions (Examples 3 and 4) of the present invention not only maintain the adhesive strength when expanding the steel pipe at room temperature compared to those of Comparative Examples, but also mechanical strength such as elongation was found to be excellent.

These results show that, by using metal oxides and additives that are compatible with materials with low shrinkage and easy stretching even at room temperature in an ideal mixing ratio, the adhesive strength and deterioration of mechanical properties during expansion of steel pipes for water service are improved, resulting in excellent on-site constructability. Simplicity of construction and construction efficiency.

Although the technical aspects have been described above and in the accompanying drawings, the technical idea of the present invention is for the description, and does not limit the invention, and those of ordinary skill in the art It will be understood that various modifications and changes of the present invention can be made without departing from the technical scope of the present invention as set forth in the claims to be described below.

Claims (4)

In the modified polyethylene powder resin composition for inner coating of steel pipe for water supply,
100 parts by weight of maleic anhydride-grafted modified polyethylene powder;
5 to 40 parts by weight of a thermoplastic elastomer; and
SiO ₂ , TiO ₂ , MgO, or 0.1 to 3 parts by weight of a metal oxide selected from the group consisting of a mixture thereof; contains;
The maleic anhydride-grafted modified polyethylene powder has a melt index (190° C.) of 3 to 6 g/10 min, a density of 0.918 to 0.925 g/cm 3 , 99% by weight of a polyethylene homopolymer, 0.05% by weight of maleic anhydride, and 1 Contains 0.95 wt% of a primary oxidation stabilizer,
The thermoplastic elastomer has a melt index of 5.0 g/10 min and a density of 0.868 g/cm 2 of a thermoplastic polyolefin rubber (POE). delete delete delete