SK8589Y1 - Thermoplastic composite and multilayer pipe made of it - Google Patents

Abstract

It is described a thermoplastic composite of a vinyl acetate/vinyl alcohol/ethylene copolymer with inorganic fillers and/or reinforcements containing 3 to 15 % by weight of carbon fiber and up to 9.9 % by weight of basalt fiber. Also described is a multilayer tube wherein at least one layer is a thermoplastic composite.

Description

The invention relates to a thermoplastic composite of a vinyl acetate / vinyl alcohol / ethylene / vinyl alcohol copolymer with inorganic fillers and / or reinforcements and a multilayer pipe made therefrom.

BACKGROUND OF THE INVENTION

Thermoplastic composites are produced with various organic fillers, e.g. wood flour, but mainly with inorganic fillers, the most common of which are calcium carbonate, and / or reinforcements which are mainly glass fibers and talc.

The use of inorganic fillers and reinforcements in thermoplastic composites is currently a widespread technology. However, if the fillers are to be truly effective and have a significant effect on mechanical and other physical properties, they should be used in concentrations of at least 20 to 30% by weight. However, this can be costly, especially if the increased density of the material filled or reinforced with inorganic substances is considered. The densities of polyolefins, especially polypropylene and polyethylene, as typical representatives, are usually in the range of 890-960 kg / m ³ and the densities of inorganic fillers and reinforcements are usually in the range of 2250 to 2600 kg / m ³ .

In thermoplastic composites, the tendency is to improve the mechanical properties of the material. Less common is the attempt to improve and / or desirable change in other physical properties. It can go eg. changes in electrical properties. In this case, it is usually intended to reduce the surface and / or volume electrical resistance. Usually one of the forms of carbon - electrical soot - is used for this. Thermo-plastic composites with carbon blacks, and not only electrically conductive ones, are used to produce heat exchange elements, usually in the form of tubes or bags, due to the increased absorption of heat radiation or the transfer of heat contained in soil, water or air. Liquid, most often water, flows through these heat exchange elements, thus transferring energy for further use, for example for heating buildings and service water.

Other forms of carbon are already carbon fiber. Its use as a reinforcement for plastics usually aims to improve the mechanical properties of the resulting composite. The use of carbon fiber leads to a curve having a reduced linear thermal expansion coefficient, as already described in Czech Utility Model No. 27,700 (granted January 12, 2015). Another physical property of plastic tubes is the diffusion of oxygen through the tube wall into the transported liquid. The reduction of this diffusion is usually solved by a multi-layered tube construction in which a layer of polyvinyl alcohol or polyamide is incorporated. These polymers may also be supplemented with layered fillers, e.g. montmorillonite

The essence of the technical solution

The object of the present invention is to provide a thermoplastic composite having a reduced linear thermal expansion coefficient (hereinafter abbreviated as CLTE), particularly useful for the manufacture of tubes, which will also form a barrier for oxygen diffusion through the tube wall into the transported liquid. According to the invention, this is achieved by a thermoplastic composite of vinyl acetate-vinyl alcohol-ethylene copolymer with inorganic fillers and / or reinforcements, which consists essentially of 3 to 15% by weight carbon fiber and up to 9.9% by weight basalt fiber .

From the point of view of dosing with and it seems advantageous, the carbon fiber used is ground.

In terms of processability, it is advantageous when the carbon fiber used is chopped.

In order to reduce the CLTE, it is expedient for the pipe to contain at least one layer of carbon fiber which forms the middle layer of the three-layer pipe.

Materials for internal water distribution are usually based on polypropylene and its copolymers with ethylene. The copolymers may be heterophasic or random. Polypropylene homopolymer can also be used.

Since polyvinyl alcohol and its vinyl acetate copolymers are chemically polar polymers and the materials based on polypropylene and its copolymer with ethylene are chemically polar polymers, it is necessary to modify one or the other, or both, of the polymers so as not to separate the layers in multilayer pipes or tubes. delamination. The modification is carried out by a grafted polar comonomer, for example maleic anhydride. The content of the modified copolymer is then 15 to 35% by weight.

The advantage of the thermoplastic composite and the tubes produced from it, according to the technical solution, is the saving of construction costs of piping systems. This savings is achieved by reducing the CLTE pipes, thereby reducing the number of expansion expansion joints in the piping system and the number of connection fittings. A further advantage, when polyvinyl alcohol and its copolymers with vinyl acetate is used, is to reduce the diffusion of oxygen through the tube wall into the transported medium (usually water).

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BRIEF DESCRIPTION OF THE DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS The technical solution will be explained in more detail using the drawings in which FIG. 1 is a cross-sectional view of a multilayer pipe.

EXAMPLES

Thermoplastic composites are preferably those based on polyvinyl alcohol and its copolymers with vinyl acetate with inorganic fillers and reinforcements.

Fillers are in the following meant inorganic or organic particles with approximately spherical symmetry, for example micronised calcium carbonate, wood flour or glass beads. In commonly used amounts, the reinforcements herein are meant inorganic or organic particles of approximately planar or fibrous shape, for example glass fibers, basalt fibers, carbon fibers, wollastonite, mica or talc. Again, unless otherwise indicated, in the amounts normally indicated, the same as the additives which are intended to include thermo-oxidizing stabilizers, UV stabilizers, lubricants, pigments and dyes, nozzle burn additives, deacidifiers, filler and reinforcement dispersants (e.g. (graft copolymers and modified waxes), means for binding fillers and / or reinforcements to a thermoplastic matrix (e.g., silanes) and others.

The samples in the form of tubes were measured in the tube production direction, i. j. in the longitudinal direction

The measurement was designed in a standard design on a test specimen with a length of 15 mm made from the working part of the injected multipurpose test specimen, which was dimensionally stabilized for 7 days at 95 ° C. The used DM A DXT04 device (RM1 CR) enables measurement by placing the test specimen in a pressure jig and subjected to a constant pressure of 4 kPa. In particular, Ah of the initial height of the body was measured during temperature scans.

Measurement conditions were selected, after adjustment based on measurement experience, as follows: heating to 95 ° C at 3 ° C / min, holding 20 min, cooling to 20 ° C at 1 ° C / min, writing 0 5 ° C, hold for 20 min., Heat to 95 ° C at 1 ° C / min. without endurance, cooling to 20 ° C at a rate of 10 ^o C / n., STOP, the course of temperature dependence Ah = h - is approximated by a line:

h = ho. [1+ a. (T = 23 ° C)].

The evaluation was performed for both the first sample cooling and the second heating. The values were uncompensated and the average value was calculated for each material.

Changes in the length of 1 test specimens at temperature were evaluated. The local coefficient of thermal expansion was calculated from these changes:

where the derivative calculation was replaced by locally translating a straight line of five consecutive corrected points. The calculations were performed for the first sample cooling, as for the second heating.

The values were compared and the average value was calculated for each material.

Oxygen permeability was measured according to DIN 4726: 2008 with reference to ISO 17455: 2005. It is expressed in mg / m ² . day.

The following examples show embodiments of a multilayer pipe according to the invention.

Example 1

A random copolymer of propylene and ethylene of the following characteristics is used as the basic thermoplastic matrix:

□ melt index 0.25 (g / 10 minutes), (230 ° C, 2.16 kg), (ISO 1133), n ethylene content 5% by weight, □ density 902 kg / m ³ (ISO 1183 / A) .

This plastic was modified by compounding in a melt of 15% by weight of a polar comonomer modified polypropylene. In this case it was a plastic of the properties listed in Table 1.

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Table 1 Properties of type I polar comonomer modified polypropylene

property method unit Value Melt flow index ISO 1133 (g / 10 min), (230 ° C, 2.16) 0.5 Starting plastic - - Random copolymer of propylene with ethylene Modifying comonomer - - Maleic anhydride Method of incorporating a modifying comonomer - - Grafted branches Content of grafted component Custom method, FTIR % weight 2

Further, a polymer comprising the following structural units in the backbone linear chain (hereinafter referred to as PVOH) was used to produce the multilayer pipe:

• ethylene, • vinyl acetate, • vinyl alcohol.

Table 2 Properties of PVOH polymer 1

property method unit Value Melt flow index ISO 1133 (g / 10 minutes), (190 ° C, 2.16) 4.4 density ISO 1183-3 kg / m ³ 1180 Melting Point (DSC) ISO 11357 ° C 183 Glass transition temperature (DSC) ISO 11357 ° C 60

From this PVOH, a thermoplastic composite (designated as PVOHKOMP1) with 3% by weight carbon fiber was prepared with the parameters listed in Table 3.

Table 3 Properties of chopped carbon fiber

property Value Surface treatment of fibers aminosilane Thread diameter (pm) 7.2 Length of fibers before compounding (mm) 6 Carbon content (% by weight) 95

From the thermoplastic composite with 3% by weight of carbon fiber according to Table 3, a three-layer pipe with the dimensions given in Table 4 was prepared.

Table 4 Dimensions of three - layer pipe

Outside diameter (mm) 20 Inner diameter (mm) 12 Total wall thickness (mm) 4 Outer layer thickness - statistical copolymer of propylene and ethylene (mm) 1.00 Middle layer thickness-COMPOSITE PVOHKOMP1 (mm) 2.00 Inner layer thickness - statistical copolymer of propylene and ethylene (mm) 1.00

The linear thermal expansion coefficient (CLTE) was measured by this procedure, reaching a [10 ^_6 / ° C] = = 18.

Oxygen permeability was measured according to DIN 4726: 2008 with reference to ISO 17455: 2005. It is expressed in mg / m ² . day and is 0.22 mg / m ² . day.

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Example 2

Example 1 was followed with the differences shown in Tables 5 and 6 below.

Table 5 Properties of polar comonomer modified polypropylene type 2

property method unit Value Melt flow index ISO 1133 (g / 10 minutes), (230 ° C, 2,16 kg) 4.5 Starting plastic - - Random copolymer of propylene with ethylene Modifying comonomer - - Maleic anhydride Method of incorporating a modification comonomer - - Grafted branches Content of grafted component Custom method, FTIR % by weight 0.4

From the PVOH, a thermoplastic composite with 15% by weight ground carbon fiber was prepared with the parameters given in Table 6 and referred to below as PVOHKOMP2.

As a binding agent, polypropylene grafted with maleic anhydride (properties Table 5) was added in an amount of 50% by weight to the unmodified polypropylene material (random copolymer of propylene and ethylene) already mentioned in Example 1.

Table 6 Properties of ground carbon fiber

property Value Surface treatment of fibers aminosilane Fiber diameter (mm) 7.4 Length of fibers before compounding (mm) 0.2 Carbon content (% by weight) 98

A three-layer pipe with the same dimensions as shown in Table 4 was prepared. Schematically, a cross-section of such a pipe is shown in Figure 1, wherein the PVOHKOMP2 composite forms the middle layer 2, see Table 5.

The linear thermal expansion coefficient (CLTE) was measured by this procedure, reaching a [10 ^_6 / ° C] = = 15.

Oxygen permeability was measured according to DIN 4726: 2008 with reference to ISO 17455: 2005. It is expressed in mg / m ² . day and is 0.42 mg / m ² . day.

Example 3

The procedure of Example 1 was followed except that a propylene homopolymer of the following characteristics was used as the thermoplastic matrix:

□ melt index 0.30 (g / 10 minutes), (230 ° C, 2.16 kg), (ISO 1133), n density 905 kg / m ³ (ISO 1183 / A).

The linear thermal expansion coefficient (CLTE) was measured as described, reaching a [10 ^_6 / ° C] = = 32.

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

Example 4

The procedure of Example 1 was followed except that a heterophasic copolymer of propylene and ethylene having the following characteristics was used as the thermoplastic matrix:

□ melt index 0.25 (g / 10 minutes), (230 ° C, 2.16 kg), (ISO 1133), ety ethylene content 7% by weight, n density 900 kg / m ³ (ISO 1183 / A) .

This plastic was modified by melt compounding of 35% by weight of polar comonomer modified polypropylene

The linear thermal expansion coefficient (CLTE) was measured as described, reaching a [10 ^_6 / ° C] = = 46.

Oxygen permeability was measured according to DIN 4726: 2008 with reference to ISO 17455: 2005.

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It is expressed in ing / m ² . day and is 1.02 ing / m ² . day.

Example 5

A random copolymer of propylene and ethylene of the following characteristics is used as the basic thermoplastic matrix:

t: · melt index 0,25 (g / 10 minutes), (230 ° C, 2,16 kg), (ISO 1133), ety ethylene content 5% by weight, □ density 902 kg / m ³ (ISO 1183 / A).

This material was used to make the multilayer pipe as shown in Figure 1. There, the material forms layers 1 and 3.

Further, a polymer comprising the following structural units in the backbone linear chain (hereinafter referred to as PVOH) was used to produce the multilayer pipe:

• ethylene.

• vinyl acetate; • vinyl alcohol.

Table 7 Properties of PVOH 2 polymer

property method unit Value Melt flow index ISO 1133 (g / 10 minutes), (190 ° C, 2.16) 1.6 density ISO 1183-3 kg / m ³ 1180 Melting Point (DSC) ISO 11357 ° C 183 Glass transition temperature (DSC) ISO 11357 ° C 60

From this PVOH, a thermoplastic composite (designated as PVOHKOMP3) with 10% by weight carbon fiber was prepared with the parameters given in Table 8.

Table 8 Properties of PVOH composite (PVOHKOMP3) modified with polar comonomer type 1

property method unit Value Melt flow index PVOH ISO 1133 (g / 10 minutes), (230 ° C, 2,16 kg) 0.5 Modifying plastic - - Random copolymer of propylene with ethylene Content of modifying plastic in composite - - 35 Modifying comonomer - - Maleic anhydride Method of incorporating a modifying comonomer - - Grafted branches Content of the grafted component in the modifying sheath Custom method, FTIR % by weight 10 Carbon fiber content (parameters in Table 3) - % by weight 10

From the thermoplastic composite PVOHKOMP3 with 10% by weight of carbon fiber according to Table 8, a three-layer pipe with the dimensions given in Table 9 was prepared. Schematically, a cross-section of such a pipe is shown in Figure 1 in which the thermoplastic composite is only in one layer 2.

Table 9 Dimensions of three - layer pipe according to example 5

Outside diameter (mm) 20 Inner diameter (mm) 12 Total wall thickness (mm) 4 Outer layer thickness-statistical copolymer of propylene and ethylene (mm) 1.00 Middle layer thickness-COMPOSITE PVOHKOMP3 (mm) 2.00 Inner layer thickness - statistical copolymer of propylene and ethylene (mm) 1.00

The linear thermal expansion coefficient (CLTE) was measured by this procedure. [alpha] [ ^10-6 / ° C] = 21.

Oxygen permeability was measured according to DIN 4726: 2008 with reference to ISO 17455: 2005.

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It is expressed in ing / m ² . day and is 0.72 ing / m ² . day.

Example 6

The procedure of Example 5 was followed except that ground carbon fiber having the properties listed in Table 6 was used.

A thermoplastic composite (designated as PVOHKOMP4) with 10% by weight carbon fiber was prepared from PVOH (see Table) with the parameters set forth in Table 10.

Table 10 Properties of PVOH composite (PVOHKOMP4) modified with polar type 1 comonomer

property method unit Value Melt flow index PVOH ISO 1133 (g / 10 minutes), (230 ° C, 2,16 kg) 0.5 Modifying plastic - - Random copolymer of propylene with ethylene Modifying comonomer - - Maleic anhydride Method of incorporating a modification comonomer - - Grafted branches Content of the grafted component in the modification sheath Custom method, FTIR % by weight 5 Carbon fiber content (parameters in Table 6) - % by weight 15

From the thermoplastic composite PVOHKOMP4 with 10% by weight of carbon fiber according to Table 5, a three-layer tube with the dimensions given in Table 9 was prepared. Schematically, a cross-section of such a tube is shown in Figure 1 in which the thermoplastic composite is only in one layer 2.

The linear thermal expansion coefficient (CLTE) was measured by this procedure, reaching a [10 ^_6 / ° C] = 12.

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

Example 7

The procedure of Example 5 was followed except that a polypropylene homopolymer as described in Example 3 was used.

The linear thermal expansion coefficient (CLTE) was measured by this procedure, reaching a [10 ^_6 / ° C] = = 27.

Oxygen permeability was measured according to DIN 4726: 2008 with reference to ISO 17455: 2005. It is expressed in mg / m ² . day and is 0.89 mg / m ² . day.

Example 8

The procedure of Example 5 was followed except that a polypropylene heterophase copolymer polymer was used, as described in Example 4.

The linear thermal expansion coefficient (CLTE) was measured by this procedure, reaching a [10 ^_6 / ° C] = = 32.

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

Example 9

The procedure of Example 5 was followed except that a basalt fiber having a concentration of 7% by weight was also used in the middle layer.

The linear thermal expansion coefficient (CLTE) was measured by the above procedure, reaching a [10 ^_6 / ° C] = 54.

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

Example 10

The procedure of Example 6 was followed except that a basalt fiber having a concentration of 7% by weight was also used in the middle layer.

The linear thermal expansion coefficient (CLTE) was measured by this procedure, reaching a [10 ^_6 / ° C] = = 30.

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

Example 11

The procedure of Example 7 was followed except that basalt fiber with a concentration of 9.9% by weight was also used in the middle layer.

The linear thermal expansion coefficient (CLTE) was measured by this procedure, reaching a [10 ^_6 / ° C] = = 18.

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

Example 12

The procedure of Example 8 was followed except that basalt fiber with a concentration of 9.9% by weight was also used in the middle layer.

The linear thermal expansion coefficient (CLTE) was measured by this procedure, reaching a [10 ^_6 / ° C] = = 21.

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

Example 13

The procedure of Example 9 was followed except that the modifier shown in Table 5 at a concentration of 35% by weight was used in the middle layer.

The linear thermal expansion coefficient (CLTE) was measured by the above procedure, reaching a [10 ^_6 / ° C] = 38.

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

Industrial usability

The technical solution is applicable for the production of plastic pipes or other pipeline elements of polypropylene or its copolymers with ethylene with a reduced linear thermal expansion coefficient and a reduced oxygen permeability. It can be used for the production of coextruded tubes for pressure and non-pressure applications, as well as for the production of sheets or foils, especially coextruded (two to three layers) sheets.

Claims (15)

A thermoplastic composite of a vinyl acetate-vinyl alcohol / ethylene copolymer with inorganic plies, containing from 3 to 15% by weight of charcoal, characterized by having up to 4, characterized in that it contains only by the fact that the carbon fiber is a carbon fiber is characterized by floodplains and / or reinforcements, characterized by tuft fiber. Thermoplastic composite according to claim up to 9.9% by weight of basalt fiber. The thermoplastic composite of claim 1, chopped. The thermoplastic composite of claim 1, ground. The thermoplastic composite of any one of claims 1, comprising from 15% by weight to 35% by weight of a binder based on polypropylene and its copolymers with ethylene and polar comonomers. Multilayer pipe, characterized in that the at least one layer is a thermoplastic composite according to any one of claims 1 to 5. Multilayer pipe according to claim 6, characterized by a thermoplastic composite. Multilayer pipe according to claim 6, characterized in that the pipes comprise a random copolymer of propylene and ethylene. The multilayer pipe of claim 6, wherein the pipes comprise a heterophasic copolymer of propylene and ethylene. Multilayer pipe according to claim 6, characterized in that the pipes comprise homopolymers of polypropylene. Multilayer pipe according to claim 8, characterized in that the pipes comprise a random copolymer of propylene and ethylene modified by a grafted polar comonomer. Multilayer pipe according to claim 9, characterized in that the outer pipe layer (1, 3) comprises a heterophasic copolymer of propylene and ethylene modified by a grafted polar comonomer. Multilayer pipe according to claim 10, characterized in that the outer pipe layer (1, 3) comprises homopolymers of polypropylene modified by a grafted polar comonomer. A multilayer pipe according to any one of claims 11 to 13, characterized by the grafted polar comonomer is maleic anhydride. A multilayer pipe according to any one of claims 11 to 14, characterized in that the modified copolymer content is 15 to 35% by weight.