EA041373B1 - METHOD AND COMPOSITION FOR OBTAINING POLYMERIC PRODUCTS - Google Patents

Description

Technical field

The present invention relates to a method, according to the introductory part of paragraph 1 of the claims, for the production of thermoplastic polymers by melt processing. In this process, a crosslinked polyolefin, such as polyethylene, is blended with a matrix polymer to form a meltable polymer composition that is processed from the melt.

The present invention also relates to compositions and products according to the introductory part of claims 5 and 9 of the claims.

State of the art

Recycling of polymeric materials is often costly and difficult. This is especially true for cross-linked polymers, since cross-linking makes the material resistant to high temperatures. Remelting such material is difficult, if not impossible. Therefore, waste polymeric materials are usually incinerated.

Recycling of waste polymers is proposed in DE 4236802 and DE 19503519. DE 4236802 describes the grinding of waste polymers to provide a homogeneous mixture that can be used for molding. DE 19503519 proposes the use of recycled cross-linked polyethylene pipes in finely cut form in combination with another recycled polymer to obtain a polymer blend that is included in petroleum product streams.

In addition, a method is known in the art for recycling cross-linked polyethylene by grinding the material into a powder form and mixing the resulting powder with a base material to obtain plastic products. Reference may be made to EP 0847842. In the known process, the proportion of shredded cross-linked polyethylene used with the polyethylene is low, less than 30% by weight, but preferably only about 10% by weight. It is only at these low loads that the mixture mixes successfully and the cross-linked polyethylene powder mixed with the base material will not adversely affect the finished product, despite the fact that it does not melt.

Other prior art implementations are disclosed in US 2009/0075004 and WO 2016/102341.

US 2009/0075004 describes mixing PEX particles with cross-linked polyethylene. This thermoset product is neither weldable nor recyclable.

WO 2016/102341 describes mixing mineral fillers such as calcium carbonate or talc with PEX electric cable pellets, about 1 mm in size, and with polyethylene, and compounding the mixture before injection molding or pressing into moulds. Obviously, in particular at higher loads of PEX filler, there is no improvement in the mechanical properties of the products compared to pure polyethylene. Due to the fact that the content of mineral filler is up to 40% by weight, when such polymers are burned, a large amount of ash remains.

As is apparent from the above, the proportion of crosslinked polyethylene should be kept low in the art, since it has been found that crosslinked polymer components are not easily compatible with thermoplastic materials, which has a negative effect on melt processing.

Brief description of the invention

The object of the present invention is to at least partially eliminate the problems of the prior art and provide a new method and composition for the production of polymer products.

According to the present invention, cross-linked polyethylene (PEX) is ground to a powder state containing fine particles, which are then mixed with a thermoplastic polymer, usually a non-crosslinked polyolefin, such as raw polyethylene (PE), to obtain a mixture.

Thus, in one aspect of the present invention, fine PEX powder with a particle size of less than 600 µm and typically a D ₅₀ of 200 to 400 µm, for example about 300 µm, is used as a component of melt-processing polymer blends.

In another aspect, crosslinked polyethylene is blended in a finely dispersed form with a thermoplastic polymer and compounded to form a master batch of granules containing from about 30% to about 80% crosslinked polyethylene, based on the total weight of the composition.

Other aspects of the present invention include products such as pipes and polymer profiles made from blends of cross-linked polyethylene and non-cross-linked thermoplastic polymers and subjected to further processing of the polymers by conventional means such as welding.

It has also been found that fine crosslinked polyethylene can be used as a filler for polymers. By incorporating PEX into thermoplastic polymers as a filler, traditional mineral fillers can be at least partially replaced. In addition, the adhesion between PEX filler and thermoplastics is good. Thus, by using PEX as a filler instead of a mineral filler, the weight of the filler-containing polymeric material can be reduced and strength properties can be improved.

In another aspect, it has been found that the proportion of PEX can be 10% by weight or more, even

- 1 041373 up to 60% by weight, relative to the total weight of the polymeric material, without significant deterioration in the weldability of products obtained from the specified mixture.

More specifically, the present invention is characterized by the content of the characterizing parts of the independent claims.

The present invention provides a number of significant advantages. In this way, the cross-linked polyolefin can be used in an economical and simple manner, whereby products usually considered as waste, such as PEX pipe cuts or unusable PEX, for example, from pipe production processes, can be recycled and used as additional material in the production of polymer products. .

When small PEX particles are incorporated into the polymer matrix, they serve as a filler material. Traditional mineral fillers can be partially or completely eliminated from use.

As a filler, ground PEX has distinct advantages over mineral fillers. Thus, when blended with polyolefin matrices such as polyethylene, PEX will increase the strength of the matrix due to its good compatibility with polyolefin backbones compared to mineral-filled PE products. Therefore, a polymer composition obtained by mixing PEX and, for example, polyethylene has better mechanical properties than a corresponding composition containing a mineral filler mixed with polyethylene.

The fillers according to the present invention stabilize and strengthen the polymer structures.

So less shrinkage will also reduce the formation of mechanical stresses within the material. This advantage is particularly important for the mechanical strength properties of structures made from extruded stretched thermoplastic pipes and profiles, which are bent or rolled after extrusion and cooling of the stretched structure.

Also receive advantages in the manufacture of massive polymer products by processing from the melt. Solid polymer articles typically have a thinnest thickness of over 10 mm and typically include parts that are at least over 25 mm. Such articles can be produced, for example, by pressing in a mould. Traditionally, shrinkage of a material caused by cooling will cause cavities in the material, such as internal closed cells. Through the use of fillers according to the present invention, the formation of such internal cavities can be avoided.

In addition, when filled plastic materials are recycled and incinerated, ash generation will be reduced. Bottom ash are the minerals that remain in the combustion process and mineral fillers represent the single main cause of bottom ash formation. Thus, by replacing mineral fillers with PEX, significant savings can be made through the disposal of ash.

The PEX-filled resin composition is lighter than the mineral-filled composition. For example, a composition containing 30% mineral filler is 20% heavier than a corresponding composition containing 30% PEX.

The cross-linked polyethylene composition can be melt-processed into products in the form of tubes or pipes. This is surprising since, based on the thermosetting properties of PEX, it was expected that high loads of said material would impair the weldability of the thermoplastic material. However, in the present invention, it has been found that if the polymer matrix is formed by a thermoplastic material such as a polyolefin, such as polyethylene, there is still enough thermoplastic on the surface of polymer articles made from said material to allow the products to be welded. As will be discussed below, it is also possible to improve weldability by providing additional cover layers of weldable materials, such as thermoplastics, in particular polyolefins, such as polyethylene, on the products.

In this regard, it can also be noted that for polymers containing mineral fillers, weldability is notoriously poor.

In preferred embodiments, the implementation of the polymer compositions according to the present invention do not contain or essentially do not contain mineral fillers. In particular, the content of mineral fillers is less than 1% by weight (of the total weight of the composition).

Due to at least sufficiently good weldability, the PEX-filled thermoplastic can be produced using traditional plastic processing methods into polymer products such as pipes and profiles that can be welded together.

In one embodiment, polymer profiles are provided that can be welded together to form objects in the form of pipes or plates.

In one particular embodiment, polymer profiles are provided having a rectangular or square, or other non-circular, cross section. Such profiles provide the building blocks or raw materials for downstream products such as double sided pipes.

- 2 041373 walls, obtained by twisting profiles into coils, which are welded together by the sides.

The following embodiments of the present invention will be discussed in more detail with the aid of the accompanying drawings.

Brief description of the drawings

Fig. 1 is a schematic representation of a wall structure according to one embodiment of the present invention, and FIG. 2 is a microscope image showing a partial cross-section of a wall of a polymer profile obtained by extrusion molding a polymer mixture according to one embodiment of the present invention.

Definitions

In the present description, the abbreviation PEX stands for cross-linked polyethylene. The terms cross-linked polyethylene and PEX include different grades of PEX, regardless of how the cross-linking was done. So cross-linked polyethylene and PEX, respectively, cover grades PEXA, PEXB and PEX _C .

Polyolefin is a term describing a class of polyalkenes such as polyethylene and polypropylene.

Welding in the context of the present description and in relation to polymers means the permanent connection of two parts of a thermoplastic to each other, in which the contacting parts at least partially melt the polymer material and, optionally, add more polymer melt.

Thermoplastics are polymers that soften and mold when exposed to heat, and become hard and strong when cooled.

Base material or base polymer refers to a thermoplastic material used, for example, in the form of granules or pellets, to obtain polymer products by processing from the melt, so that said base material, after solidification of the melt, forms a continuous matrix of products. The thermoplastic material may be a pure polymer or a mixture of polymers.

Masterbatch means a certain amount of material, consisting of a polymer mixture, in an isolated form, prepared for use, in particular for incorporation into the polymer.

The sieve size refers to particles that have passed through a sieve with a predetermined mesh size. So a sieve size of 600 µm means that the particles pass through a sieve having the indicated opening size.

D ₅₀ is the median diameter or average of the particle size distribution. It represents the diameter of 50% of the particles. Once the sieved material has been isolated, the particle size can be determined optically or by X-ray analysis, for example with Sedigraph. Particle size can also be determined using a set of sieves with predetermined hole sizes. For example, the ground material can be screened using at least 2, preferably 3 to 15, sieves with different opening sizes.

Industrial waste is defined as waste resulting from an industrial process.

Waste products are waste materials received from manufacturers, such as offcuts from cutting.

Percentages correspond to % by weight, unless otherwise indicated.

Implementation Options

According to a first embodiment, the present invention relates to a method for producing polymer products, in particular thermoplastic polymer products, from thermoplastic polymers by melt processing, in which cross-linked polyethylene is mixed with at least one thermoplastic base polymer to obtain a polymer composition that is processed from melt. Cross-linked polyethylene is a fine powder. The polymer composition does not contain cross-linking agents. Therefore, it is able to provide thermoplastic material by melt processing.

Suitable cross-linked polyethylene material is obtained from recycled waste, such as materials selected from the group of industrial waste or production waste. Examples include defective products such as pipes and offcuts. This will be discussed below.

Cross-linked polyethylene (abbreviated as PEX) is widely used in the construction, plumbing and mining industries, and in general for pipelines for infrastructure facilities. It is also used as a material for electrical cables, storage tanks and radiant heating products, as well as in the fields of medicine and dentistry. Most waterproof polymer-containing commercial products contain PEX, optionally with barrier materials, as will be discussed below.

Due to the widespread use of PEX, wastes containing PEX are also plentiful. Industrial

- 3 041373 waste is a suitable source of PEX material. Waste PEX material from industrial manufacturing processes can be collected and reused. Examples include PEX pipes, which are of poor quality and are thrown away. Another source of PEX is production waste, said materials, such as cutting offcuts, are obtained from manufacturers and the volume is increasing. Usually PEX waste is incinerated. The present invention provides an efficient recycling of PEX by incorporation into polymeric products.

In one embodiment of the present invention, PEX from various sources is recycled as a material to make polymeric products such as pipes and profiles that retain good strength properties, which means that significant amounts of raw polymers can be replaced with recycled material.

As stated above, any PEX material can be used according to the present invention. However, in terms of filler application, it has been found that particularly good results are obtained for grades PEXA and PEX _C , PEXA was used in the example below (see Fig. 2), in which a good balance was obtained between the internal strength of the filled material and suitable polymer weldability .

PEX material, in particular waste PEX, is crushed to obtain a fine material. Grinding can be carried out using any pulverizing equipment and mill suitable for grinding or pulverizing polymer resins, in particular thermoplastic materials. Examples of suitable equipment include disc mills, ball mills, impact mills, high shear rotary mills, and cutting machines such as knife mills. In one embodiment, since grinding or grinding generates heat, grinding is carried out under cooling conditions, such as cryogenic conditions.

Grinding is continued until a powder is obtained. The material is screened to remove particles larger than about 600 microns. Such particles can be returned for grinding.

Preferably, grinding and sieving is carried out in such a way that a powder is obtained with an average particle diameter, D ₅₀ , of about 300 µm, or, in general, a D ₅₀ of 200 to 400 µm. In the present description, about 300 µm means 300 µm±10%, in particular 300 µm±5%.

In one embodiment, up to 30% by weight of all particles have a sieve size of less than 400 microns. In one embodiment, up to 8% by weight of all particles have a sieve size of less than 200 microns.

Typically, fine crosslinked polyethylene contains particles with a narrow size distribution. In such a size distribution, the amount of particles having a sieve size of less than 200 µm is less than 10%, in particular less than 5% by weight, and the amount of particles having a sieve size of more than 400 µm is less than 10%, in particular less than 5 % by weight.

In one embodiment, the fine crosslinked polyethylene is provided in the form of a dry powder. In particular, the fine crosslinked polyethylene is provided as a powder having a moisture content of less than 10% by weight, in particular less than about 7.5% by weight, typically from about 0.1 to 5% by weight.

In one embodiment, the PEX powder described above is mixed with a base polymer, such as a polyolefin, capable of forming a polymer product matrix, in amounts up to 60% by weight.

While the polyolefin forms the matrix of the polymeric article, the powder is used as a polymeric additive or filler to form a composition that can be melt-processed into plastic articles.

Based on the above, in one embodiment, a plastic product is provided that is obtained by extrusion or molding, containing a base material, such as a polyolefin or a mixture of polyolefins, which forms the matrix of the material, and cross-linked polyethylene (PEX) which forms the material filler.

In one embodiment, a thermoplastic material containing PEX powder as a filler is used in extrusion to produce extruded elongated products, in injection molding or compression molding to produce molded products.

In some embodiments, the PEX fine particles for inclusion in the polymer matrix are irregularly shaped and vary in size within a predetermined range.

Shrinkage usually occurs in melt-processed articles upon cooling, and the degree of shrinkage is affected by various factors such as cooling time, mold temperature, or resin melt temperature, and is often also sensitive to injection pressure. Shrinkage of extruded or molded articles is undesirable because it causes uncompensated volumetric contraction of the articles. It has been found that by varying the amount of PEX powder added to the composition, the degree of thermal shrinkage can be reduced and controlled.

In all of the above embodiments, cross-linked polyethylene and base polymer(s) are mixed in a ratio of from about 5 to 60, in particular from 10 to 50, for example from 15 to 40 parts by weight.

- 4 041373 cross-linked polyethylene k from 40 to 95, in particular from 50 to 90, for example from 60 to 85 wt.h. base polymer.

The base polymer is preferably a thermoplastic polymer.

One particularly interesting class of thermoplastic polymers for use in blending with cross-linked polyethylene are polyolefins. As known in the art, polyolefins are a class of polymers derived from olefin monomers such as ethylene, propylene, methylpentene, and butene, yielding polyolefins such as polyethylene, polypropylene, polymethylpentene, and polybutene-1. Polyolefins are widely used in industry due to their thermoplastic properties. They can be layered or molded above certain temperatures. That is, they can be molded into a desired configuration that solidifies upon cooling.

In particular, the base polymer is formed from non-crosslinked polyolefins selected from the group of polyethylene and polypropylene. The polyethylene may be selected from the group of low density, medium density and high density polyethylene. Optionally, the polyethylene may be a linear low density polyethylene.

The base material is preferably provided in the form of a raw material, although recycled thermoplastic materials may also be used.

The crosslinked polyethylene fine material can then be melt processed directly or blended with the base material to form a masterbatch for subsequent use in melt processing.

Thus, in the first embodiment, cross-linked polyethylene powder is included in the flow of polymer raw materials in plastics processing equipment. Typically, the polymer feed stream contains or consists of pellets of thermoplastic material. In particular, the crosslinked polyethylene powder is mixed with a base polymer containing a non-crosslinked polyolefin to form a mixture which is processed by subjecting it to heat and optionally shear and pressure forces to form the mixture into a desired shape. Such a process may be selected in particular from the group consisting of extrusion, injection molding, molding and rotational molding.

The cross-linked polyethylene powder can be mixed in a ratio of 5 to 60, in particular 10 to 50, for example 15 to 40 parts by weight. cross-linked polyethylene to from 40 to 95, in particular from 50 to 90, for example from 60 to 85 wt.h. non-crosslinked polyethylene, for example in the form of granules. The mixture obtained in this way can be supplemented with pigments and traditional polymer additives, for example, in amounts up to 10% by weight of the polymers.

In a second embodiment, the pulverized PEX is compounded with the base material, i.e. with non-crosslinked polyethylene to form a masterbatch (MB) which is then fed at a predetermined ratio into a non-crosslinked polyolefin feed stream to form a mixture from which polymer products are obtained using conventional plastics processing technology.

One implementation option includes obtaining a masterbatch by creating a mixture of from 10 to 95, in particular from 30 to 80, for example from 50 to 75 wt.h. non-crosslinked polyethylene, for example in the form of granules, and from 5 to 90, in particular from 20 to 70, for example from 25 to 50 wt.h. cross-linked polyethylene powder, optionally together with pigments and traditional polymer additives, for example, in an amount up to 25% by weight of the polymers. The mixture is heated to a temperature ranging from 105 to 180° C. or higher, depending on the density of the non-crosslinked polyethylene, to melt the non-crosslinked polyethylene. Typically, melt blending is carried out with sufficient shear to ensure intimate contact between the components. After melt blending, the mixture is cooled and optionally cut into pellets. The melt blending of the masterbatch compounding mixture is generally carried out by extrusion. It has been found that a masterbatch of the above kind can be obtained even in a single screw extruder, although multi-screw extruders can also be used.

The masterbatch is usually mixed in a predetermined ratio with a non-crosslinked polyolefin, the latter usually provided in the form of granules. The weight ratio of masterbatch to non-crosslinked polyolefin is, depending on the predetermined content of crosslinked polyethylene in the finished product, usually from 1:100 to 100:1, in particular from 1:10 to 10:1, for example from 1:2.5 to 1:5.

The advantage of making a masterbatch is that the recycled PEX can be stored as a masterbatch without the need to strictly control storage conditions.

Melt processing of the combined masterbatch feedstock and polymer base material can be accomplished by heating and optionally applying shear and pressure forces to mold the mixture into a predetermined shape. As discussed above, this can be done using a method selected from the group consisting of extrusion, injection molding, compression molding and rotational molding.

It should be noted that PEX waste, depending on the application of the material, contains other polymer components such as barrier materials, in particular barrier layer materials for plastic products, which give the products properties of reduced permeability to gases such as oxygen, nitrogen, carbon dioxide. and helium. One common component is ethyl vinyl alcohol (EVOH) copolymer. Typically, EVOH may be present in an amount of up to 10% by weight, in particular from about 0.01 to 5%, based on the weight of the PEX material.

Surprisingly, it has been found that EVOH does not adversely affect the use of PEX powder as a component of polymer blends with non-crosslinked thermoplastics, in particular polyolefins. Thus, in general, the polymer composition according to one embodiment contains, in addition to crosslinked polyethylene and non-crosslinked polyolefin, also some EVOH, in particular from 0.001 to 5% by weight of EVOH, relative to the total weight of the remaining polymers.

Traditionally, EVOH films are bonded to adjacent materials such as PEX with adhesives (polymeric thermosets). Consequently, recycled PEX grades will often contain residue from such adhesives. Typically, the amount of residue of any adhesives is less than 0.0001 to 2.5% by weight relative to the weight of cross-linked polyethylene. According to the present invention, it has also been found that such residues do not adversely affect the use of PEX in the polymer blends described above.

In one embodiment, polymeric compositions containing up to 60% by weight, in particular from 10 to 50% by weight, crosslinked polyethylene, together with polymers having thermoplastic properties, such as non-crosslinked polyolefins, are used to obtain polymeric articles that can be welded.

Although the crosslinked polyethylene does not substantially melt at the same temperatures as the non-crosslinked polyolefin, it has surprisingly been found, as mentioned briefly above, that due to the presence of a matrix of polymer particles formed by the non-crosslinked polyolefin and due to the incorporation of the crosslinked polyethylene in powder form into said polyolefin matrix , at least sufficiently good welding properties are achieved.

In one embodiment, polymer compositions are provided having a density of less than 1000 kg/m ³ , in particular less than 980 kg/m ³ , typically 900 to 960 kg/m ³ , eg 940 to 960 kg/m ³ .

In one embodiment, polymeric compositions are provided containing 70% by weight or less of a thermoplastic polymer that forms the matrix of the composition and 30% by weight or more of a polymeric filler, said filler comprising cross-linked polyethylene in a finely dispersed form, and said composition being weldable.

In one embodiment, polymer compositions are provided containing 70% by weight or less of a thermoplastic polymer that forms the matrix of the composition and 30% by weight or more of a polymeric filler, said filler comprising cross-linked polyethylene in finely dispersed form, said composition being weldable, and said composition has a density of 900 to 960 kg/m ³ , for example 940 to 960 kg/m.

Welding of polymeric articles obtained from the polymeric compositions of the present invention can be carried out, as is known in the art, by melting a portion, usually at least a portion, of the surfaces of the polymeric articles to be joined. The molten surfaces of the products are placed in close contact, and when the melt solidifies, the products are fastened together. It is also possible to apply the molten polymer to the junction between the surfaces that are joined together. The molten polymer will adhere to the surfaces and at least partially melt them to form a strong bond.

As used herein, the term weldable in relation to polymeric articles and polymeric products means that the articles or products, when welded, produce a weld having equal or greater strength than adjacent portions of the articles or products. So usually, when a welded structure is exposed to mechanical forces, the destruction of the structure will primarily occur not in the area of the welded joint.

Traditionally, plastics can be welded by extrusion welding, resistance welding, friction welding, rapid deposition welding, hot plate welding, high frequency welding, induction welding, ultrasonic welding, and laser welding.

Various tubular products can be formed into various configurations by welding, i.e. a flat structure with a plurality of elongated profiles of thermoplastic material can be positioned so that adjacent hollow profiles fit snugly against each other. One of the benefits of incorporating PEX into a thermoplastic material is its resistance to shrinkage while maintaining weldability. Optionally, a layer of polyolefin may be placed on the surface of the tubular profiles to further assist the welding process.

Thus, in one of the embodiments, a polymer product is proposed in the form of a molded object having an inner surface and an outer surface, and a cross section, and said pipe contains a polymer material containing up to 60% by weight of finely dispersed cross-linked polyethylene mixed with at least one polyolefin , and the specified cross-linked polyethylene has particles with a sieve size of less than 600 microns and a D ₅₀ from 200 to 400 microns.

The present invention also provides for the production of multilayer products. In one embodiment, the polymer article has a cover layer on the inner surface, the outer surface, or both surfaces, said cover layer being formed by, or

- 6 041373 is made of a thermoplastic material such as raw polyolefin material or other weldable thermoplastic polymer. Such a cover layer will improve the weldability of the products. Thus, in one embodiment, by co-extrusion of a PEX-filled core with polyolefin, such as non-crosslinked polyethylene, covers on one or both sides, the extrusion of the covers will help maintain reasonable extruder throughput despite some increase in core viscosity. during extrusion.

In one embodiment, a polymer article is provided in the form of a polymer pipe or polymer profile having a hollow cross section, said pipe or profile having a wall formed by said polymer material. This embodiment also includes the alternative that the polymer pipe or profile has a multilayer wall with a cover layer on at least the outside of the product.

It is possible to provide pipes suitable, for example, as conduits for fluids. The molded pipes can be welded with the following pipes, such as end-to-end welding or butt welding, to make longer pipes.

In another embodiment, pipes or profiles are provided that are side-welded. Such profiles may be hollow and, for example, have a non-circular cross section, such as a rectangular cross section. The side-welded profiles can form a substantially flat surface consisting of a plurality of pipes, suitable for example for slabs, planes and panels in various buildings and structures. Boards and panels made from side welded profiles are manufactured and sold under the names Wehopanel and Wehoboard by Uponor Infra Oy.

In addition, the hollow profiles of the present invention may be helically wound in one or more turns to provide a polymeric product. The outer surfaces of the pipe can be side welded along the turns of the helix to provide a pipe having a double wall construction. The subsequent elongated pipe profile can be described as having a double wall construction around the opening. This double wall construction is a very useful feature for pipe products, providing additional structural integrity. Pipes of this type are manufactured and sold under the name Weholite from Uponor Infra Oy.

Considering FIG. 1, it can be noted that the pipe wall according to one embodiment of the present invention comprises a middle layer 2 located between two cover layers 1,3 on each side. The middle layer 2 consists of a thermoplastic polymer forming a continuous matrix 4 and also contains cross-linked polyethylene particles 5 dispersed in said polymer matrix.

The cover layers 1 and 3 on both sides of the profile consist of a non-crosslinked polyolefin. The integumentary layer completely covers the underlying surface of the middle layer.

In FIG. 2 shows a cross section of a hollow profile made in accordance with one embodiment of the present invention. Obviously, the polymer wall contains a layer 12, which is micrographed between two glass plates (not shown). Layer 12 is formed from a thermoplastic polymer, preferably polyethylene 14, filled with particles of cross-linked polyethylene 15.

In the embodiment shown in FIG. 2, the top layers (ie, the surface portions of layer 12) do not contain these particles. The cross-linked polyethylene contains industrial waste or production waste (PEX/EVOH) crushed into irregularly shaped particles (< 600 µm) which are evenly distributed in the polyethylene layer 12. The amount is 30% by weight.

Since the crosslinked material contains polyethylene backbones, the compatibility of the particulate material 15 with the matrix material 4 is good.

The following non-limiting examples illustrate the present invention.

Example 1

PEX trims were used in powder form (particles with a sieve size of less than 600 μm) as a filler in rotational molding chambers. PEX powder was added at 5%, 10% and 20% by weight to the mold along with untreated polyethylene (1741 Black). The residence time in the oven was about 20 minutes.

The results are shown in table. 1

- 7 041373

1 2 3 4 PEX 0 5 % 10 % 20% RE1741 100 95% 90% 80% Mass of the meter g/m 7359 7235 7238 7377 Ring stiffness kN/m ² 0.36 0.37 0.39 0.38 e avg. Mm 5.72 5.54 5.85 6.34 Yield strength MPa 20.3 20.1 19.1 18.4 Tensile Strength MPa P,2 P,2 9.6 9.1 Elongation at Break % 402 310 128 75 Elongation at break, art. off % 55 60 93 54 Tensile modulus MPa 972 970 824 826 Density kg/l 0.925 0.940 0.916 0.903

Table 1

Based on the results obtained and taking into account the gentle mixing method in the rotational molding chamber, it can be established that there is sufficiently good compatibility and adhesion between the PEX particles and the PE matrix.

Example 2

Three-layer DN110 conduit pipes were produced using polyethylene (Marlex 5502) masterbatch containing PEX particles (< 600 µm) in the middle layer. The results are shown in table. 2

table 2

Reference Sample 1 Sample 2 Middle layer: PE (%) PEX-MB (%) PEX in the middle layer (%) 100 45 39 (20) 25 59 (thirty) Outer/inner layers: Marlex 5502 (%) 12/4 12/4 Density (kg/l) 0.955 0.948 0.946 Meter weight (g/m) 1575 1600 1478 LCD (kN/m ² ) 10.9 8.2 U shock resistance (-10С°/12.5 kg) >2m >2m Crowbar impact strength (-10 С°/10 kg) ~0.7m ~0.4m

As can be seen from the results, the impact resistance of PEX/Marlex 5502 pipes was excellent.

Example 3

Large diameter pipes, consisting of helically wound profiles that were side-welded to form a hollow wall of a large diameter pipe (products of this type supplied by Uponor Oyj under the name Weholite®), were made from 3-layer polymer profiles with a middle layer formed of polyethylene and containing PEX filler in powder form.

Polymer profiles were made by co-extrusion using a mixture of Hostalen 5052B and PEX powder, <600 µm, cut on a Pallmann cutter for the middle layer, and Liten PL10 for the outer layers of the profile. Liten PL 10 has also been used for profile welding.

The results are shown in table. 3.

Table 3

Recipe sample 1 Sample 2 Hostale 5052B % 80.0 70.0 PEX powder (< 600 µm) % 20.0 30.0 Trial Profile meter weight kg/m 0.765 0.757 Mass of a meter of pipe kg/m 54.8 59.6 Outside pipe diameter mm 1304 1305 Pipe inner diameter mm 1207 1208 Profile height mm 48.70 48.40 Profile width mm 71.20 70.70 Ring stiffness 3d kN/m ² 2.20 2.40 Ring Flexibility 30 % Yes Yes Tensile test for welding - internal H 1340 1320 Tensile test for welding - external n 1220 1200

-8041373

As can be seen from the obtained results, the rigidity of the sample ring was at a good level.

The weight standard for DN1200 SN2 is 58 kg/m. The total mass of the meter for the entire production and testing cycle was 57.8 kg/m.

Tensile weld tests have shown that the polymer profiles are weldable and have a tensile strength (EN13476-2) well above the required level of 1020 N.

Example 4

Large diameter pipes, consisting of helically wound profiles that were side-welded to form a hollow wall of a large diameter pipe (products of this type supplied by Uponor Oyj under the name Weholite®), were made from 3-layer polymer profiles with a middle layer formed of polyethylene and containing PEX filler in powder form (MB).

Polymer profiles with external dimensions of 62.5x93.75 mm were made from the following materials:

Secondary PE granulate for pressure pipes as reference pipe

PE100 HE3490-LS and 150616-W01-01.3 (50%/ CRP100+PEX/EVOH < 600 µm) in PEX profile

Marlex 5502+Polyon white in white layers and weldable interior; Total XS10B in the outer part to be welded.

Co-extrusion to obtain white layers on the inner and outer surfaces of the profiles was carried out by co-extrusion. The PEX content in the profiles was 30%.

The profiles were welded together as described in example 3.

The pipe containing PEX was compared to a reference pipe. In table. 4 shows formulations and test results.

Table 4

Recipe Comparison Sample Secondary PE granulate for pressure pipes % 100.0 5 NOT 3490-LS % 40.0 PEX-MB (50% PEX) % 60.0 PEX profile content thirty Content PEX to MW 50 50 Trial Mass of a meter of pipe kg/m 74.3 73.5 10 Outside pipe diameter Mm 1124 1123 Pipe inner diameter Mm 1005 1005 Ring stiffness kN/m ² 7.49 7.15 Ring Flexibility 30 % Yes Yes Tensile test for welding inner H 2415 2899 15 Tensile test for welding outer n 2199 2266

The test results showed that the mechanical properties of Weholite DN1600 SN4, with 30% PEX in the middle layer of the profile, are at a good level.

A sufficiently thick layer can be extruded onto the profile by adding a second co-extruder providing the pipe containing Weholite PEX with a sufficiently good appearance of the inner and outer layers.

The mechanical properties of the PEX pipes were generally good.

Applicability in industry

At least some embodiments of the present invention find industrial application in the same areas as polymeric articles and products, in particular, thermoplastic articles and products. For example, PEX-filled polymer pipes can be used as pipelines for fluids such as wastewater and as various structural elements such as profiles, plates and welded profile pipes. Such pipes can be produced by extrusion and co-extrusion. In addition, PEX-filled polymeric materials can be solid (ie solid) parts such as chamber bottoms and various solid profiles. In one embodiment, such solid parts are obtained by pressing. Solid parts can also be produced by other techniques such as mold pressing and hollow parts by rotational molding.

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Claims (11)

List of abbreviations PEX - cross-linked polyethylene MB - master batch (masterbatch) PE - polyethylene D ₅₀ is the median diameter of the particle size distribution, in other words, the value of the particle diameter at 50% in the cumulative distribution. So D ₅₀ =3 00 μm means that half of the particles have a particle diameter greater than 300 μm and half of the particles have a particle diameter greater than specified. D ₅₀ = 200 to 400 µm means that the median diameter as defined above is in the range of 200 to 400 µm. EVOH - ethyl vinyl alcohol List of symbols 1, 3 - cover layers 2 - middle layer 4 - polymer matrix 5 - filler particles 12 - structural layer 14 - polyolefin material (matrix) 15 - particles of cross-linked polyethylene (filler) Citation list Patent Literature EP 0847842 DE 4236802 DE 19503519 US 2009/0075004 WO 2016/102341 CLAIM 1. A method for producing polymer products from thermoplastic polymers by melt processing, in which cross-linked polyethylene is mixed with non-cross-linked polyethylene to obtain a polymer composition, which is subjected to melt processing, and said cross-linked polyethylene is a fine powder formed by particles with a sieve size of less than 600 µm and D50 from 200 to 400 µm, where D50 is the median value of the particle size distribution and where the particle size is determined optically, or by X-ray analysis, or using a set of sieves with predetermined hole sizes. 2. The method according to claim 1, wherein said cross-linked polyethylene is obtained from waste materials selected from the group of industrial wastes or production wastes. 3. Process according to claim 1 or 2, wherein said cross-linked polyethylene is mixed with non-cross-linked polyethylene in an amount of up to 60% by weight, in particular from 5 to 50% by weight, in particular from 10 to 40% by weight. 4. Process according to any one of claims 1 to 3, wherein said cross-linked polyethylene powder is fed into the melt processing process directly or as a masterbatch. 5. A method according to any one of claims 1 to 4, wherein the resulting polymer products are weldable. 6. Process according to any one of claims 1 to 5, wherein the weight content of said cross-linked polyethylene powder is 10% or more, in particular 15 to 50% of the total weight of the polymer composition. 7. A process according to any one of claims 1 to 6, wherein said crosslinked polyethylene powder is compounded with non-crosslinked polyethylene to form a masterbatch that is metered into the melt process system. 8. Polymer composition for the production of polymer products, containing or consisting of cross-linked polyethylene and non-cross-linked polyethylene, mixed in a mass ratio of cross-linked polyethylene to non-cross-linked polyethylene up to 60:40, in which the cross-linked polyethylene is contained in the form of a fine powder with a sieve particle size of less than 600 microns and D ₅₀ from 200 to 400 μm, where D ₅₀ represents the median value of the particle size distribution and where the particle size is determined optically or using x-ray analysis, or using a set of sieves with predetermined hole sizes. 9. The polymer composition according to claim 8, where the specified cross-linked polyethylene contains a copolymer of ethyl vinyl alcohol (EVOH) in an amount of not more than 10%, in particular from 0.01 to 5% by weight, and optionally residues of any adhesives used to bond EVOH with cross-linked polyethylene. 10. A polymer composition according to claim 8 or 9, wherein said mixture is in the form of a masterbatch. 11. Construction of polymer products, containing a plurality of elongated polymer profiles, welded together by the sides, and these polymer profiles contain up to 60% by weight of finely dispersed cross-linked polyethylene mixed with non-cross-linked polyethylene, and the cross-linked polyethylene particles have a sieve size of less than 600 microns and D ₅₀ from 200 to 400 microns, where D ₅₀ is the median value of the particle size distribution and where the particle size is determined -