RU2705584C1 - Adhesive polyethylene composition for steel pipe insulation coating - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to an adhesive polyethylene composition used in multilayer coatings of steel pipes used for transportation, including gas and oil products. Composition contains base linear low density polyethylene, medium density polyethylene and elastomer or rubber. Base polyethylene used is a mixture of linear low-density polyethylene (LLDPE) with MFR _{2.16 kg/190 °C} in range of 0.5 to 3.5 g/10 min and linear low-density polyethylene grafted with maleic anhydride ((MA)LLDPE), with functional monomer content of 1.0 to 1.5 wt% and MFR _{2.16 kg/190 °C} in range from 1.0 to 1.5 g/10 min, as average density polyethylene (ungrafted) (ADPE) with MFR _{2.16 kg/190 °C} in range from 3.0 to 4.0 g/10 min. Elastomer or rubber is selected from a group comprising a copolymer of propylene with ethylene with MFR _{2.16 kg/190 °C} in range from 1.4 to 1.5 g/10 min. or copolymer of ethylene with butene-1 with MFR in range from 1.1 to 1.4 g/10 min or copolymer of ethylene with hexene-1 with MFR _{2.16 kg/190 °C} in range from 1.1 to 1.4 g/10 min or butyl rubber.

EFFECT: disclosed composition has high operational characteristics and is applicable for industrial coating application.

1 cl, 3 tbl, 9 ex

Description

The invention relates to the field of production of adhesives used, in particular, in multilayer coatings of steel pipes used for transportation, including gas and oil products.

Compositions for protecting oil and gas pipelines containing various compositions of polyethylene obtained both on Ziegler-Natta catalysts and on metallocene catalysts are rather widely described in the literature. Various catalytic systems used for the production of polyethylene, allow to obtain certain types of polymers, combining which, it is possible to ensure that the properties that the adhesive compositions used in multilayer coatings of steel pipes have to provide good adhesion with the layers directly associated with them, both at room temperature and at high temperature, and, in addition, their application on an industrial scale should be easily carried out under normal conditions.

Known binder composition, which includes a mixture of polyethylene with a density of from 0.935 to 0.980 g / cm ³ with a polymer selected from elastomers, polyethylene of very low density, and where this mixture is jointly grafted with unsaturated carboxylic acid and diluted with polyethylene with a density of from 0.93 to 0 95 g / cm ³ (US patent No. 6746738, publ. 08.06.2004, IPC B32B 1/02). The specified binder composition based on a mixture of polyethylene can be used to obtain a multilayer structure, for example, flexible or rigid packaging (bottles, containers, etc.), but it cannot be used in anti-corrosion coatings of oil and gas pipelines.

Known adhesive polymer composition containing a) non-elastomeric polyethylene in an amount of from 40 to 97 wt. % of the total weight of the composition and b) an elastomer containing an elastomeric ethylene copolymer with polar comonomer groups, where component a) was obtained by the method using a catalyst with one active center, and component a) or components a) and b) were vaccinated together using acid grafting agent (EA patent No. 007577, publ. 12/29/2006, IPC C09J 151/06). The composition is used to obtain an adhesive layer on the pipe and provides a high degree of adhesion. However, the “basic" component of the composition (40-97 wt.%) Is a copolymer of ethylene with α-olefins obtained on a metallocene catalyst. Polyethylene obtained on a metallocene catalyst is more expensive and today has not found such widespread use as polyethylene obtained on Ziegler-Natta catalysts.

A grafted polyethylene-based adhesive composition is known containing, with respect to the total weight of the composition, from 1 to 40% polyethylene (A) grafted with a functional monomer, or a mixture of polyethylene (A1) obtained by metallocene catalysis, with a second polymer (A2) obtained by catalysis according to Ziegler-Natta, and different from (A1), wherein said mixture of (A1) and (A2) is grafted together with an unsaturated functional monomer, such as unsaturated carboxylic acid or unsaturated anhydride of said acid, where the mass content of nogo monomer with respect to (A) is in the range of from 30 to 100,000 pieces / m; from 25 to 98% unvaccinated polyethylene (B) obtained using metallocene catalysis and having a density in the range from 0.900 to 0.965 g / cm ³ , and from 1 to 35% elastomeric product (C). Component (C) is selected from ethylene-alkyl (meth) acrylate copolymers or ethylene-alkyl (meth) acrylate-maleic anhydride copolymers or a copolymer of ethylene with alpha-olefin, the bending modulus of which is below 100 MPa, and the density is in the range from 0.860 to 0.90 g / cm ³ (EA patent No. 018678, publ. 09/30/2013, IPC C08L 23/06, C08L 23/08, C09J 123/06, C09J 123/08). This composition is used to obtain an adhesive layer on the pipe and provides a high degree of adhesion. However, its disadvantage is that the "basic" component of the composition (40-97 wt.%) Is a copolymer of ethylene with α-olefins obtained on a metallocene catalyst, this narrows and increases the cost of the raw material base to obtain an adhesive composition.

The closest is the composition of the thermoplastic adhesive containing 15-30 wt. including medium-density polyethylene grafted with maleic anhydride with a content of grafted maleic anhydride -1.5-2.1%, 40-85 wt. including the base polymer based on linear low density polyethylene (LLDPE) with a MF of 0.8 g / 10 min and 5-30 wt. including an elastomer based on amorphous alpha olefins, butyl acrylate, styrene thermoplastic elastomer or ethylene propylene rubber. In addition, the composition may additionally contain target additives in an amount of 0.01-10.00% by weight of polyethylene (RF patent 2505574, publ. 01/27/2014, IPC C09J 151/06, C09J 123/06). These declared adhesives of CJSC Metaclay were produced on the basis of Metallen's own graft polymer (MDPE-g-MAH). The disadvantage of this composition is the use in the formulation of from 15 to 30 wt. % medium density polyethylene (PESP) grafted with functional groups, which narrows the raw material base to obtain an adhesive layer.

An object of the invention is to provide an adhesive composition based on available grades of polyethylene having high performance characteristics and the possibility of industrial application to the pipe under normal conditions.

The technical problem is solved by the composition of the adhesive composition containing a basic linear low density polyethylene (LLDPE), medium density polyethylene (PESP), elastomer or rubber, more specifically, in which a mixture of linear low density polyethylene (LLDPE) with melt flow rate ( PTR 2.16 kg / 190 ° C) in the range from 0.5 to 3.5 g / 10 min and grafted with maleic anhydride linear low density polyethylene ((MA) LLDPE), with a functional monomer content of from 1.0 to 1, 5 wt. %, with a melt flow rate (MFR of 2.16 kg / 190 ° C) in the range from 1.0 to 1.5 g / 10 min, as medium density polyethylene (ungrafted) (MESP) with a melt flow rate (MFR 2 , 16 kg / 190 ° C) in the range from 3 to 4 g / 10 min, while the elastomer or rubber is selected from the group comprising a copolymer of propylene with ethylene with a melt flow index (MFR 2.16 kg / 190 ° C) in the range from 1.4 to 1.5 g / 10 min or a copolymer of ethylene with butene-1 with a melt flow index (MFR of 2.16 kg / 190 ° C) in the range from 1.1 to 1.4 g / 10 min or copolymer of ethylene with hexene-1 with an indicator of t nditions melt (MFR 2.16 kg / 190 ° C) ranging from 1.1 to 1.4 g / 10 min or butyl rubber or ethylene-propylene rubber, the following component weight. %:

linear low density polyethylene (LLDPE) 50-80 grafted linear low density polyethylene ((MA) LLDPE) 5-15 medium density polyethylene (PESP) 5-15 an elastomer or rubber selected from the group including copolymer of propylene with ethylene, copolymer of ethylene with butene-1, a copolymer of ethylene with hexene-1,  ethylene propylene rubber, butyl rubber 5-20

The difference of the claimed composition from the prototype is that as the base polyethylene use a mixture of linear low density polyethylene (LLDPE) with a melt flow rate (MFR of 2.16 kg / 190 ° C) in the range from 0.5 to 3.5 g / 10 min and grafted with maleic anhydride linear low density polyethylene ((MA) LLDPE), with a functional monomer content of from 1.0 to 1.5 wt. %, with a melt flow rate (MFR of 2.16 kg / 190 ° C) in the range from 1.0 to 1.5 g / 10 min, as medium density polyethylene (ungrafted) (MESP) with a melt flow rate (MFR 2 , 16 kg / 190 ° C) in the range from 3 to 4 g / 10 min, while the elastomer or rubber is selected from the group comprising a copolymer of propylene with ethylene with a melt flow index (MFR 2.16 kg / 190 ° C) in the range from 1.4 to 1.5 g / 10 min or a copolymer of ethylene with butene-1 with a melt flow index (MFR of 2.16 kg / 190 ° C) in the range from 1.1 to 1.4 g / 10 min or copolymer of ethylene with hexene-1 with an indicator of t nditions melt (MFR 2.16 kg / 190 ° C) ranging from 1.1 to 1.4 g / 10 min or butyl rubber or ethylene-propylene rubber, the following component weight. %:

linear low density polyethylene (LLDPE) 50-80 grafted linear low density polyethylene ((MA) LLDPE) 5-15 medium density polyethylene (PESP) 5-15 an elastomer or rubber selected from the group including copolymer of propylene with ethylene, copolymer of ethylene with butene-1, ethylene-hexene-1 copolymer, ethylene-propylene rubber, butyl rubber 5-20

This ratio of specially selected claimed components allows to obtain a homogeneous adhesive composition by industrial methods, which has the necessary performance characteristics and is applied on an industrial scale to the surface of steel pipes under normal conditions.

Obtaining an adhesive polyethylene composition according to the invention for the insulation coating of steel pipes is carried out in 3 stages by:

1. mechanical mixing of the components under any environmental conditions;

2. melting and mixing the components in an extruder;

3. cooling the melt and obtaining the finished product with the desired properties in any known form.

The homogenization of the components of the composition is carried out in mixing devices of any type. Melting and mixing of the melt composition can be carried out in single screw extruders or extruders with two co-directional or multidirectional rotating screws. The temperature in the working area of laboratory or industrial equipment should be in the range from 130 to 280 ° C, more preferably from 130 to 220 ° C. If necessary, a flat-slit head can be installed on the extruder, which allows melt the film with a given thickness.

The composition is used in a multilayer structure as an adhesive. In the molten state, it is in direct contact with at least one polymer layer, which is preferably polyethylene. It is more effective to use it as a bonding layer between polyethylene and either an epoxy primer deposited on a metal substrate or directly with the metal. Such a multilayer structure is effectively used, for example, in the corrosion protection of metal oil and gas pipelines.

To obtain the compositions of the present invention, a standard TSE 24 MS twin screw extruder from TermoFisher Scientific with co-rotating rotary screws was used. The temperature regime of processing was in the range of 180 ÷ 200 ° C.

Table 1 shows the characteristics of the components that were used in the manufacture of adhesive polymer compositions. In the examples below, 3 types of basic LLDPE (types 4-6), 3 types of grafted with maleic anhydride (MA) LLDPE (types 1-3), 3 types of PESP (types 7-9) and 3 types of polyolefin elastomers (types 10-12 were used) ), as well as ethylene propylene rubber and butyl rubber. The adhesive composition of the present invention may optionally include various additives, for example, antioxidants, antistatic agents, processing and glidants, nucleators, fillers, etc.

Standard methods were used to analyze the properties of the components and the resulting composition. Density was determined using a gradient column at a temperature of 23 ° C according to ASTM D 1505; melt flow rate (MFR) - according to ASTM D 1238 at 190 ° C. The content of maleic anhydride is analyzed by determining the content of succinic acid residues using infrared spectroscopy with Fourier transform.

The main indicator of the quality of the adhesive polyethylene composition applied to the steel pipe is the amount of adhesion, which is determined on the finished product according to GOST 31448, GOST 411 (method A). To obtain the correct results, examples are given, including, in comparison with the prototype, in which the samples are tested under the same conditions, and using the same primer and top layer in a three-layer composition.

To determine the adhesion, a three-layer system was chosen, which is the 3M Scotchkote 226N epoxy primer applied to the polyethylene substrate as the first layer, adhesive according to the invention and prototype, and high-density carbon black filled PE 6146KM grade manufactured by PAO as the top layer Nizhnekamskneftekhim. At the first stage, an epoxy primer was applied to a metal substrate with a surface temperature of 210-220 ° C, then an adhesive layer was applied using a Brabender PL 2000 single-screw extruder with a flat-slot head. The temperature in the zones of the extruder was 210/220/230/230 ° C. At the final stage, polyethylene was applied using a PolylabOS RheomaxPTW16 / 40 XL twin-screw extruder with a temperature in the extruder zones of 245/250/250/250/250/250/250/250/250/250 ° С. The three-layer coating is rolled using a roller and cooled in a water bath.

Tests for determining adhesion were carried out after conditioning the samples at 23 ° C for 24 hours. For testing, the tongue (layer of polyethylene and adhesive) with a width of 10 mm and a length sufficient to fix the sample in the clamps of the RMI 250 bursting machine was peeled from the epoxy primer. Speed clamp discrepancies selected 100 mm / min. The test results of adhesion values are presented in table 2. The same table shows comparative data for measuring the adhesion of a sample of the prototype, performed under the same conditions as the samples according to the invention.

To prove the feasibility of industrial production and the quality of the claimed adhesive polyethylene composition, industrial tests were carried out to apply a three-layer polyethylene anticorrosive coating to the pipe. The results are presented in table 3 for samples of metal pipes coated with Scotchkote 226N epoxy primer, adhesive manufactured by PJSC Nizhnekamskneftekhim and PE 6146KM polyethylene produced by PJSC Nizhnekamskneftekhim. The adhesion measurements in industrial application were carried out at room temperature (23 ° C), as well as at 40, 60 and 80 ° C according to GOST 31448, GOST 411 (method A). According to the current industry standards STO Gazprom 2-2.3-130 and OTT 25.220.60-KTN-103, the adhesion value for special coatings (the most stringent requirements) is considered to meet the requirements if it is at least 200-250 N / cm at 23- 25 ° С and not less than 75-100 N / cm - at 80 ° С.

Example 1. For the preparation of adhesive using LLDPE, grafted LLDPE, PESP, and propylene-ethylene polyolefin elastomer in the amount of 75, 5, 10 and 10 wt. %, respectively.

LLDPE is used with the following characteristics: density 0.918 g / cm ³ , _{MF 2.16 kg / 190 ° C} 3.5 g / 10 min. As grafted LLDPE use LLDPE with a content of maleic anhydride of 1.05 wt. %, density 0.918 g / cm ³ , _{MF 2.16 kg / 190 ° C} 1.5 g / 10 min. PESP is characterized by a density of 0.938 g / cm ³ , _{MF 2.16 kg / 190 ° C} 5.5 g / 10 min. As the polyolefin elastomer, a propylene-ethylene elastomer with a density of 0.862 g / cm ³ , a MFI of _{2.16 kg / 190 ° C of} 1.4 g / 10 min and a crystallinity of 0% is used. The characteristics of the initial components of the composition are presented in table 1, and the composition of the composition and the adhesion value of coatings based on them are shown in table 2.

The coating using the adhesive composition of Example 1 has an adhesion of 320 N / cm.

Examples 2-7. Carried out as described in example 1, but using components with different characteristics and in a different ratio. The characteristics of the initial components of the composition are presented in table 1, the composition of the composition and the adhesion value of coatings based on them are shown in table 2.

Example 8. For the correct comparison of the properties of the composition according to the invention and the prototype in example 8, an adhesive sample of the Metakley APE-1 brand of ZAO Metakley was used, similar to that described in RF patent No. 2505574.

Example 9. To prove the possibility of using the adhesive composition according to the invention on an industrial scale, the composition is prepared as described in examples 1-7 using the claimed components in an optimally selected ratio using high-performance industrial equipment. The conditions for applying a three-layer polyethylene coating to a metal pipe, as well as the test results are presented in table 3. As can be seen from the table, the adhesion value at 23 ° C was 320 N / cm, and at 80 ° C it was more than 100 N / cm.

As can be seen from the above examples, the proposed adhesive polyethylene composition can be successfully applied in the industrial application of a three-layer polyethylene coating on high-tech lines with a high value of adhesion to the epoxy primer and the upper polyethylene layer at 20 and 80 ° C.

Claims (2)

Adhesive polyethylene composition for insulating coating of steel pipes, including base polyethylene, medium density polyethylene, elastomer or rubber, characterized in that as the base polyethylene a mixture of linear low density polyethylene (LNEP) with melt flow rate (MFR _{2.16 kg / 190 ° C} ) in the range from 0.5 to 3.5 g / 10 min and grafted with maleic anhydride linear low density polyethylene ((MA) LLDPE), with the content of functional monomer from 1.0 to 1.5 wt.%, With an indicator melt flow rate (MFR _{2.1 6 kg / 190 ° C} ) in the range from 1.0 to 1.5 g / 10 min, as medium density polyethylene (ungrafted) (MESP) with a melt flow index (MFR of _{2.16 kg / 190 ° C} ) in the range from 3 to 4 g / 10 min, while the elastomer or rubber is selected from the group comprising a copolymer of propylene with ethylene with a melt flow index (MFR of _{2.16 kg / 190 ° C} ) in the range from 1.4 to 1.5 g / 10 min or a copolymer of ethylene with butene-1 with a melt flow index (MFR of _{2.16 kg / 190 ° C} ) in the range from 1.1 to 1.4 g / 10 min or a copolymer of ethylene with hexene-1 with a melt flow index ( MFR _{2.16 kg / 190 ° C)} Range area from 1.1 to 1.4 g / 10 min or butyl rubber or ethylene-propylene rubber, the following component wt.%: linear low density polyethylene (LLDPE) 50-80 grafted linear low density polyethylene ((MA) LLDPE) 5-15 medium density polyethylene (PESP) 5-15 an elastomer or rubber selected from the group including copolymer of propylene with ethylene,  ethylene butene-1 copolymer,  copolymer of ethylene with hexene-1,  ethylene propylene rubber, butyl rubber 5-20