RU197757U1 - Multilayer pipe - Google Patents

Abstract

The utility model relates to a multilayer pipe consisting of three layers. The outer and inner layers are made of a copolymer of propylene and ethylene modified with a polar comonomer — maleic acid anhydride, the middle layer is made of a thermoplastic composite consisting of a copolymer of vinyl acetate and vinyl alcohol with ethylene and 3-15 wt. % carbon fiber. The technical result is to reduce the coefficient of thermal expansion of the pipe and reduce diffusion of oxygen through the wall of the pipe. 4 s.p. crystals, 1il., 10 tablets, 13 ave.

Description

Technical field

The technical field relates to a thermoplastic composite of a vinyl acetate and vinyl alcohol copolymer with ethylene with inorganic fillers and (or) reinforcing components, as well as multilayer pipes made of a thermoplastic composite.

The current level of technology

Thermoplastic composites are made with various organic fillers, for example wood flour, but mainly with inorganic fillers, the most common of which is calcium carbonate and (or) reinforcing components, which include mainly fiberglass and talc.

The use of inorganic fillers and reinforcing components in thermoplastic composites is currently common practice. However, in order to ensure real effectiveness and significant impact of the properties of fillers on the mechanical and other physical characteristics, fillers should be used in concentrations of at least 20-30% by weight. This can be costly, especially given the increased density of the material, filled or reinforced with inorganic components. The density of polyolefins, in particular polypropylene and polyethylene, as typical representatives of the class, as a rule, is in the range of 890-960 kg / m ³ , and the density of inorganic fillers and reinforcing components, as a rule, is in the range of 2250-2600 kg / m ³ .

In thermoplastic composites, as a rule, they strive to improve the mechanical characteristics of the material. Less common are cases where it is necessary to improve and (or) it is advisable to change other physical characteristics. Changes in electrical properties, for example, may also occur. In this case, as a rule, intentionally reduce the surface and (or) volume electric resistance. For this, as a rule, one of the forms of carbon is used - highly conductive soot. Thermoplastic composites containing soot, not only electrically conductive, produce heat-conducting elements, usually in the form of pipes or bags - this is possible due to the increased absorption or transfer properties of heat contained in soil, water or air. A liquid - usually water - flows through heat-exchange elements and transfers energy for further use, for example for heating buildings and heating industrial water.

Of the other forms of carbon, carbon fiber can also be considered. Its use as a plastic reinforcing component usually aims to increase the mechanical properties of the resulting composite. The use of carbon fiber reduces the coefficient of linear thermal expansion of pipes, as already described in the Czech patent for utility model No. 27700 (issued January 12, 2015). Another physical property of plastic pipes is the diffusion of oxygen through the pipe wall into the transported liquid. Reducing this diffusion, as a rule, is achieved by using a multilayer pipe design, which includes a layer of polyvinyl alcohol or polyamide. These polymers can also be complemented by layered fillers such as montmorillonite.

The basis of the technical solution

The aim of the present invention is to develop a thermoplastic composite with a reduced coefficient of linear thermal expansion (hereinafter referred to as "KLTR") for use mainly in the production of pipes; however, such a composite will create a barrier to oxygen diffusion through the pipe wall into the transported liquid. According to the technical solution, this is achieved by using a thermoplastic composite of vinyl acetate and vinyl alcohol copolymer with ethylene and inorganic fillers and (or) reinforcing components mainly on the basis that its composition contains 3-15 wt.% Carbon fiber by weight. %, and basalt fiber - 0-9.9 wt. %

In terms of dosage, the use of ground carbon fiber is preferable.

In terms of technological characteristics, it is preferable to use chopped carbon fiber.

With respect to reducing CTE, it is important to have at least one carbon fiber layer in the pipe forming the middle layer of the three-layer pipe.

Materials for the internal distribution of water, as a rule, are made on the basis of polypropylene and its copolymers with ethylene. The copolymers may be heterophasic or statistical. A polypropylene homopolymer may also be used.

Since polyvinyl alcohol and its copolymers with vinyl acetate are chemically polar polymers and materials based on polypropylene and its copolymers with ethylene are chemically polar polymers, it is necessary to change one or both polymers in such a way as to avoid separation of layers in multilayer pipes - the so-called “delamination”. Modification is carried out using a grafted polar comonomer, for example, maleic anhydride. The content of the modified copolymer is from 15 to 35 wt. %

The advantage of a thermoplastic composite and pipes made from it, in accordance with the technical solution, is to reduce costs in the construction of pipeline systems. This cost reduction is achieved by reducing the CTE of the pipes and a corresponding reduction in the number of expansion joints in pipeline systems, as well as the number of connecting fittings. Another advantage in the case of the use of polyvinyl alcohol and its polymers with vinyl acetate is the reduction of oxygen diffusion through the pipe wall into the transported medium (usually water).

Explanation of the drawings

A detailed description of the technical solution is presented using the drawings. In FIG. 1 is a cross-sectional view of a multilayer pipe.

Examples of technical solutions

Thermoplastic composites preferably include polyvinyl alcohol composites and their vinyl acetate copolymers with inorganic fillers and reinforcing components.

Fillers are hereinafter referred to as inorganic or organic particles with approximate spherical symmetry, for example, finely divided calcium carbonate, wood flour or glass granules. In a commonly used amount, the reinforcing components herein provide for the incorporation of inorganic or organic particles of approximately flat or fiber form, for example, fiberglass, basalt fiber, carbon fiber, wollastonite, mica or talc, as well as, unless otherwise indicated, in the amounts and additives indicated below in this document means thermal oxidizing stabilizers, UV stabilizers, lubricants, pigments and paints, additives against the formation of deposits on nozzles, deoxidants, dispersants of fillers and reinforcing components (i.e. grafted copolymers and modified paraffins), agents for binding fillers and ( or) reinforcing components in a thermoplastic matrix (e.g., silanes), etc.

Pipe-shaped samples were measured in the pipe manufacturing direction, i.e. in the longitudinal direction.

The measurement provided a standard version using a 15 mm test body made of a working element of an injection molded multipurpose test body that underwent dimensional stabilization by quenching for 7 days at 95 ° C. The equipment used DMA DXT04 (of RMI CR) allows you to measure by placing the test body in a medium under pressure and applying a constant pressure of 4 kPa. In the process of reading the temperature, the change in the initial body height h ₀ -Δh was measured.

The following measurement conditions were selected after making adjustments based on the experience of the measurements:

heating to 95 ° C at a rate of 3 ° C / min, duration - 20 min;

cooling to 20 ° C at a rate of 1 ° C / min, registration - every 0.5 ° C, duration - 20 min;

heating to 95 ° C at a rate of 1 ° C / min, duration - not determined;

cooling to 20 ° C at a rate of 10 ° C / min; STOP;

the temperature dependence Δh = h-h0 is approximately described by the line:

An assessment was made for both the first cooling of the sample and the second heating of the sample. A comparison of the obtained values was carried out, as well as the calculation of the average value for each material.

The change in length of 1 test bodies was evaluated as a function of temperature. Based on these change values, the coefficient of linear thermal expansion was calculated:

where the calculation according to the obtained formula was replaced by fitting a local line with five consecutive corrected points. Calculations were performed both for the first cooling of the sample and for the second heating of the sample.

A comparison of the obtained values was carried out, as well as the calculation of the average value for each material.

Oxygen permeability was measured according to DIN 4726: 2008 taking into account ISO 17455: 2005. It is expressed in the following units: mg / m ² day.

The following examples demonstrate the construction of a multilayer pipe in accordance with the technical solution.

Example No. 1

A statistical copolymer of propylene and ethylene with the following characteristics was used as the base thermoplastic matrix:

melt flow rate - 0.25 (g / 10 min, at 230 ° C, 2.16 kg), ISO 1133;

ethylene content by weight - 5%;

density - 902 kg / m ³ (ISO 1183 / A).

This plastic was modified by melt mixing with a weight percent of polypropylene modified with a polar comonomer of 15 wt. % In this case, the plastic showed the characteristics shown in table 1.

A polymer was also used in the production of a multilayer pipe, containing the following structural elements in the basic linear chain (hereinafter referred to as “PVA”):

• ethylene;

• vinyl acetate;

• vinyl alcohol.

A thermoplastic composite (marked as “PVSKOMP1”) was prepared from PVA with a carbon fiber content of 3 wt. %, with the parameters indicated in table 3.

From a thermoplastic composite with a carbon fiber content of 3 wt. %, according to Table 3, a three-layer pipe was manufactured with the dimensions indicated in Table 4. The cross-section of such a pipe is shown schematically in FIG. 1. In this case, the thermoplastic composite is represented by only one layer 2.

By the above procedure, the coefficient of linear thermal expansion (CTE) was measured, which reached α [10 ^-6 / ° C] = 18.

The oxygen permeability was measured according to DIN 4726: 2008 taking into account ISO 17455: 2005. It is expressed in mg / m ² day and reaches 0.22 mg / m ² day.

Example No. 2

The procedure was applied as described in example No. 1, with the differences indicated in tables 5 and 6 below.

A thermoplastic composite was made from PVA (hereinafter referred to as “PVSKOMP2”) with a content of ground carbon fiber of 15 wt. %, with the parameters indicated in table 6. As a binder component in the unmodified polypropylene material (statistical copolymer of propylene and ethylene) was added polypropylene grafted with maleic anhydride (the characteristics are presented in table 5), as described in example No. 1, in volume constituting 50% by weight.

A three-layer pipe of the given sizes was prepared; the dimensions are identical to those indicated in Table 4. A cross-section of such a pipe is shown schematically in FIG. 1. In this case, the composite PVSKOMP2 forms the central layer 2 (see table 5).

By the above procedure, the linear thermal expansion coefficient (CTE) was measured, which reached α [10 ^-6 / ° C] = 15.

The oxygen permeability was measured according to DIN 4726: 2008 taking into account ISO 17455: 2005. It is expressed in mg / m ² day and reaches 0.42 mg / m ² day.

Example No. 3

The procedure was applied as described in example No. 1, with the differences consisting in the fact that a propylene homopolymer with the following characteristics was used as a thermoplastic matrix:

Показатель текучести расплава - 0,30 (г/10 мин, при 230°С, 2,16 кг), ISO 1133;

The melt flow rate is 0.30 (g / 10 min, at 230 ° C, 2.16 kg), ISO 1133;

плотность - 905 кг/м³ (ISO 1183/А).

density - 905 kg / m ³ (ISO 1183 / A).

By the above procedure, the linear thermal expansion coefficient (CTE) was measured, which reached α [10 ^-6 / ° C] = 32.

Oxygen permeability was measured according to DIN 4726: 2008 taking into account ISO 17455: 2005. It is expressed in mg / m ² day and reaches 0.62 mg / m ² day.

Example No. 4

The procedure was used as described in example No. 1, with the differences consisting in the fact that a heterophasic copolymer of propylene and ethylene with the following characteristics was used as a thermoplastic matrix:

Показатель текучести расплава - 0,25 (г/10 мин, при 230°С, 2,16 кг), ISO 1133;

The melt flow rate is 0.25 (g / 10 min, at 230 ° C, 2.16 kg), ISO 1133;

содержание этилена по весу - 7 мас. %;

ethylene content by weight - 7 wt. %;

плотность - 900 кг/м³ (ISO 1183/А).

density - 900 kg / m ³ (ISO 1183 / A).

This plastic was modified by mixing in the melt with the content of polypropylene modified with a polar comonomer, comprising 35 wt. %

By the above procedure, the linear thermal expansion coefficient (CTE) was measured, which reached α [10 ^-6 / ° C] = 46.

Oxygen permeability was measured according to DIN 4726: 2008 taking into account ISO 17455: 2005. It is expressed in mg / m ² day and reaches 1.02 mg / m ² day.

Example No. 5

A statistical copolymer of propylene and ethylene with the following characteristics was used as the base thermoplastic matrix:

Показатель текучести расплава - 0,25 (г/10 мин, при 230°С, 2,16 кг), ISO 1133;

The melt flow rate is 0.25 (g / 10 min, at 230 ° C, 2.16 kg), ISO 1133;

содержание этилена по весу - 5%;

ethylene content by weight - 5%;

плотность - 902 кг/м³ (ISO 1183/А).

density - 902 kg / m ³ (ISO 1183 / A).

The material used in the manufacture of the multilayer pipe corresponds to that indicated in FIG. 1. In the drawing, the material forms layers 1 and 3.

A polymer was also used in the production of a multilayer pipe, containing the following structural elements in the basic linear chain (hereinafter referred to as “PVA”):

• ethylene;

• vinyl acetate;

• vinyl alcohol.

A thermoplastic composite (marked as “PVSKOMP3”) was prepared from PVA with a carbon fiber content of 10 wt. %, with the parameters indicated in table 8.

From the thermoplastic composite PVSKOMP3 with a carbon fiber content of 10 wt. %, according to Table 8, a three-layer pipe was manufactured with the dimensions indicated in Table 9. The cross-section of such a pipe is shown schematically in FIG. 1. In this case, the thermoplastic composite is represented by only one layer 2.

By the above procedure, the linear thermal expansion coefficient (CTE) was measured, which reached α [10 ^-6 / ° C] = 21.

Oxygen permeability was measured according to DIN 4726: 2008 taking into account ISO 17455: 2005. It is expressed in mg / m ² day and reaches 0.72 mg / m ² day.

Example No. 6

The procedure was applied as described in example No. 5, with the difference that ground carbon fiber with the characteristics indicated in table 6 was used.

From PVA (see table) a thermoplastic composite was prepared (marked as "PVSKOMP4") with a carbon fiber content of 10 wt. %, with the parameters indicated in table 10.

From the PVSKOMP4 thermoplastic composite with a carbon fiber content of 10 wt. %, according to Table 5, a three-layer pipe was manufactured with the dimensions indicated in Table 9. The cross-section of such a pipe is shown schematically in FIG. 1. In this case, the thermoplastic composite is represented by only one layer 2.

By the above procedure, the coefficient of linear thermal expansion (CTE) was measured, which reached α [10 ^-6 / ° C] = 12.

Oxygen permeability was measured according to DIN 4726: 2008 taking into account ISO 17455: 2005. It is expressed in mg / m ² day and reaches 0.95 mg / m ² day.

Example No. 7

The procedure was used as described in example No. 5, with the difference that the polypropylene homopolymer with characteristics similar to those specified in example No. 3 was used.

By the above procedure, the linear thermal expansion coefficient (CTE) was measured, which reached α [10 ^-6 / ° C] = 27.

The oxygen permeability was measured according to DIN 4726: 2008 taking into account ISO 17455: 2005. It is expressed in mg / m ² day and reaches 0.89 mg / m ² day.

Example No. 8

The procedure was used as described in example No. 5, with the difference that a heterophasic polypropylene copolymer with characteristics similar to those specified in example No. 4 was used.

By the above procedure, the linear thermal expansion coefficient (CTE) was measured, which reached α [10 ^-6 / ° C] = 32.

Oxygen permeability was measured according to DIN 4726: 2008 taking into account ISO 17455: 2005. It is expressed in mg / m ² day and reaches 1.09 mg / m ² day.

Example No. 9

The procedure was applied as described in example No. 5, with the difference that the basalt fiber in a concentration of 7% was also used in the middle layer.

By the above procedure, the coefficient of linear thermal expansion (CTE) was measured, which reached α [10 ^-6 / ° C] = 54.

Oxygen permeability was measured according to DIN 4726: 2008 taking into account ISO 17455: 2005. It is expressed in mg / m ² day and reaches 1.75 mg / m ² day.

Example No. 10

The procedure was used as described in example No. 6, with the difference that the basalt fiber was also used in the middle layer at a concentration of 7%.

By the above procedure, the linear thermal expansion coefficient (CTE) was measured, which reached α [10 ^-6 / ° C] = 30.

Oxygen permeability was measured according to DIN 4726: 2008 taking into account ISO 17455: 2005. It is expressed in mg / m ² day and reaches 2.05 mg / m ² day.

Example No. 11

The procedure was used as described in example No. 7, with the difference that the basalt fiber was also used in the middle layer at a concentration of 9.9%.

By the above procedure, the coefficient of linear thermal expansion (CTE) was measured, which reached α [10 ^-6 / ° C] = 18.

Oxygen permeability was measured according to DIN 4726: 2008 taking into account ISO 17455: 2005. It is expressed in mg / m ² day and reaches 1.09 mg / m ² day.

Example No. 12

The procedure was applied as described in example No. 8, with the difference that the basalt fiber was also used in the middle layer at a concentration of 9.9%.

By the above procedure, the linear thermal expansion coefficient (CTE) was measured, which reached α [10 ^-6 / ° C] = 21.

Oxygen permeability was measured according to DIN 4726: 2008 taking into account ISO 17455: 2005. It is expressed in mg / m ² day and reaches 1.19 mg / m ² day.

Example No. 13

The procedure was applied as described in example No. 9, with the difference that the modifier was used in the middle layer, as indicated in table 5, at a concentration of 35%.

By the above procedure, the coefficient of linear thermal expansion (CTE) was measured, which reached α [10 ^-6 / ° C] = 38.

Oxygen permeability was measured according to DIN 4726: 2008 taking into account ISO 17455: 2005. It is expressed in mg / m ² day and reaches 2.09 mg / m ² day.

Industrial applicability

The technical solution can be used in the production of plastic pipes or other pipeline elements from polypropylene or its copolymers with ethylene with a reduced coefficient of linear thermal expansion and reduced oxygen permeability. It can also be used in the production of coextruded pipelines used in pressure and pressureless systems. In addition, it can be used in the manufacture of panels or foils and mainly coextruded panels (two- and three-layer).

Claims (5)

1. A multilayer pipe consisting of three layers, where the outer and inner layers (1, 3) are made of a copolymer of propylene and ethylene modified by a polar comonomer - maleic acid anhydride, where the middle layer (2) is made of a thermoplastic composite consisting of a vinyl acetate copolymer and vinyl alcohol with ethylene and 3-15 wt. % carbon fiber. 2. A multilayer pipe according to claim 1, characterized in that the thermoplastic composite contains chopped carbon fiber. 3. A multilayer pipe according to claim 1, characterized in that the thermoplastic composite contains ground carbon fiber. 4. A multilayer pipe according to claim 1, characterized in that the outer and inner layers (1, 3) are made of a random copolymer of propylene and ethylene. 5. A multilayer pipe according to claim 1, characterized in that the outer and inner layers (1, 3) are made of a heterophasic copolymer of propylene and ethylene.

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