DE102007035657B4 - Pipe and / or connector made of a thermoplastic material - Google Patents

Abstract

Tube of extruded or injection-molded thermoplastic material for pipelines carrying hot or cold fluids comprising at least three layers whose middle layer is reinforced by mineral fibers, characterized in that the middle layer in the thermoplastic matrix contains oxidation-inhibiting additives or a mixture of antioxidant additives which can migrate into the adjacent layers and whose proportion is greater than that in the adjacent layers and of which at least 50% of a molecule having a molecular weight below 740 g / mol are formed to form a "reservoir" containing it makes it possible to compensate for the losses of oxidation-inhibiting additives over time, the middle layer in its thermoplastic matrix initially having a mass fraction of an antioxidant additive of 0.1 to 1% above that of the inner layer.

Description

The present invention relates on the one hand a pipe on the other hand, a connector, each made of an extruded or injection-molded thermoplastic material for piping and in particular for pipelines that carry warm or cold fluids. The pipes and connectors made of a thermoplastic material offer numerous outlets. Their use is important in numerous areas and especially for the drinking water supply, in heating systems or in the food industry.

In the prior art, there are various types of pipes for conveying liquids and gases. These tubes can be made of metal or plastic. The commonly used metal pipes are, for example, copper pipes. Copper pipes have good wear resistance and are insensitive to light. However, their execution is difficult because they must be welded. In addition, the use of the welding torch can cause the risk of burning or a fire.

Consequently, the use of plastic tubes is increasing more and more. The advantages associated with the use of such pipes are known in the art and are in particular a lower weight, a simplified assembly and installation technique, the hygienic properties (few deposits) or also an improved insulation. However, plastic tubes also have disadvantages. Contact with liquids and gases, such as oxidizing and reducing liquids, and gases that carry them may interfere with the chemical and mechanical properties of the polymer or polymers making up the conduits. To remedy this problem, one solution is to introduce additives into the amorphous regions of the polymer, that is, into the regions of the polymer which do not have a crystalline structure. The additives are mobile in these areas, a property that can be used to protect the pipe at the desired locations where it will contact the liquids and gases. However, a major disadvantage of plastic pipes with anti-oxidant additives is that the additives, which are located near the inner surface of the pipe, are gradually removed from the liquids and gases. As a result, there are fewer and fewer additives on the inner surface of the pipe to ensure protection of the thermoplastic matrix, which is thereby chemically decomposed slowly (by oxidation, hydrolysis, etc.), leading to embrittlement of the pipe over time.

In the pamphlets DE 100 18 324 A1 and DE 11 45 844 A is attempted to remedy this problem by 10 to 50% fillers are introduced into the middle layer of a multilayer pipe of polypropylene random copolymer and additionally conventional additives, which form a barrier and are intended to reduce the migration of additives from the inner layer or completely avoided. Fillers are glass fibers, glass beads or glass flour (or a combination of these substances). A binder allows for better adhesion of these ingredients to the polymer.

In this plastic, the material of the barrier layer, the polypropylene random copolymer, however, due to its molecular structure, a very low migration resistance, so that the barrier effect is achieved only by the carefully selected fillers that can inhibit the additives in the thermoplastic matrix.

In the publication EP 1 598 179 A1 For example, a tube or fitting of a thermoplastic material is described that includes at least an outer layer, a middle layer, and an inner layer that contacts the aggressive medium. The middle layer, which forms a barrier to the migration of the additives out of the inner layer, is in this case made up of a crystalline, nucleated polymer and thus has substantially smaller crystalline regions of the thermoplastic material. This results in a middle layer with a finer microstructure that limits the migration of antioxidant additives into the tube.

However, the device described does not make it possible to completely compensate for the removal of the additives from the inner layer by the aggressive medium over time.

In the publication WO 2005/080077 A2 is a tube with at least two layers, in particular with at least one inner layer and at least one outer layer described. An embodiment having an inner layer, a middle layer, and one or more outer layers is also provided. WO 2005/080077 A2 deals almost exclusively with the formulation of the inner layer. The inner layer is preferably a layer containing thermoplastic polymer comprising filler, the fillers having polar groups. The middle layer may comprise aluminum, copper, stainless steel. Various thermoplastic materials such as polyolefin are also provided.

In the publication EP 0 174 611 A2 is a three-layer pipe described for the transport of warm water. The inner layer comprises a net-like polyolefin. The middle class comprises Saponification products of ethylene-vinyl-acetate copolymers. The outer layer comprises polybutene or a net-like polyolefin.

It is an object of the invention to propose a new tube based on a thermoplastic material, which avoids the entirety or part of the aforementioned disadvantages.

For this purpose, the subject of the invention on the one hand a pipe according to claim 1 and on the other hand, a connector according to claim 2, each of an extruded or injection-molded thermoplastic material for pipelines carrying hot or cold fluids (liquids and gases) comprising at least three layers, the middle layer of which is reinforced by mineral fibers, possibly combined with other fillers, characterized in that the middle layer in the thermoplastic matrix contains antioxidant additives or a mixture of antioxidant additives capable of migrating to the adjacent layers and whose proportion is greater than that in FIG the adjacent layers and of which at least 50% and preferably at least 75% of a molecule having a molecular weight of less than 740 g / mol are formed to form a "reservoir" which allows the losses of ox recorded over time to be reduced To balance idungshemmenden additives.

The memory of the middle layer is thus intended to allow the oxidation-inhibiting additives to circulate more or less rapidly from the middle layer into the inner layer. In fact, the low molecular weight additives will be able to migrate from the middle layer to the inner layer and make it possible to compensate for the losses caused by the fluids (liquids and gases) carried in the line by extracting the additives present in the inner layer.

The thermoplastic material of the layers is preferably a polyolefin and / or a polyamide and / or a polyvinylidene fluoride and / or a polyvinyl chloride and / or a post-chlorinated polyvinyl chloride and preferably a polypropylene random copolymer (PP-R).

According to the invention, the middle layer in its thermoplastic matrix initially contains a mass fraction of an oxidation-inhibiting additive of 0.1 to 1% above that of the inner layer.

According to a feature of the invention, the middle layer also contains in its thermoplastic matrix an oxidation-inhibiting additive which is composed of a molecule whose molecular weight is above 740 g / mol. This additive has the advantage of having low migratability and giving the matrix higher oxidation-induction times (OIT). The oxidation-induction time is a unit by which the thermal stability of a polymer and / or the effectiveness of the polymer-protecting stabilizers can be measured. Preferably, the middle layer in its thermoplastic matrix initially contains a mixture of antioxidant additives comprising molecules of different molecular weights ranging from 500 to 4100 g / mol.

The inner layer, which comes into contact with the medium to be transported, is preferably made of polypropylene random copolymer (PP-R).

The inner layer initially preferably contains from 0.1 to 0.5 mass percent of antioxidant additives.

According to a feature of the invention, at least 50% of the antioxidant additives contained in the inner layer have a molecular weight above 740 g / mol, so that a very low migration of the additives into the water is achieved.

Preferably, the inner layer initially contains 0.1 to 0.6% by mass of antimicrobial and / or antibacterial agents.

Preferably, the outer layer contains additives that prevent the penetration of UV rays.

In one aspect of the invention, the outer layer initially contains 0.4% by weight of antioxidant additives.

In the course of the following description of particular embodiments of the invention, given by way of illustration and not of limitation, the invention may be better understood and the other objects, details, features and advantages of the invention more apparent.

As already mentioned, the tube and / or connector of an extruded or injection molded thermoplastic material for pipelines conveying warm or cold fluids (liquids and gases) comprises at least three layers: an inner layer, a middle layer and an outer layer.

The thermoplastic material of the layers is a polyolefin and / or a polyamide and / or a polyvinylidene fluoride and / or a polyvinyl chloride and / or a post-chlorinated polyvinyl chloride and preferably a polypropylene random copolymer (PP-R). The inner layer comes into contact with the aggressive liquids and gases. The Liquids and gases carry oxygen, which causes premature aging of the pipeline. They wash the inner layer and gradually remove the antioxidant additives contained in this layer. As a result of the oxidation, the pipe will spit and crack, possibly damaging the pipe over time.

The inner layer is made of polypropylene random copolymer (PP-R). It generally contains initially from 0.1 to 0.5% of a mixture of antioxidant additives. At least 50% of the antioxidant additives used have very little migration into the water, that is, their molecular weight is above 740 g / mol to more difficult to migrate out of the amorphous regions of the polymer and thus through the aggressive ones carried in the pipeline Media to reduce losses. It is also possible to use a mixture of antioxidant additives. For example, it is possible to cite a mixture containing molecules with a high resistance to extraction by the conveyed medium of the type CAS no. 1709-70-2 (Irganox® 1330) or CAS no. 27676-62-6 (Irganox® 3114) and molecules of the type CAS no. 6683-19-8 (Irganox® 1010), which give the matrix high oxidation induction times (O-IT), or of the type CAS no. 31570-04-4 5 (Irgafos® 168) combined.

It will be obvious to those skilled in the art that the invention is not limited to the aforesaid antioxidant additives and that other antioxidant additives may be used.

The inner layer may also contain antimicrobial and / or antibacterial agents, preferably in the range of 0.1 to 0.5 mass percent. These agents are for example of the type Irgaguard® B5000 and / or B6000 and have the task of preventing the growth of microbes or bacteria on the inner wall of the tube. In addition, the addition of 0.1 to 0.2% Irganox® MD1024 type metal preservatives may be considered to protect the inner layer from the catalytic action of the metal ions (copper ions) contained in the media carried by the pipeline ,

The outer layer, which comes into contact with the air, initially contains a proportion of 0.4% by mass of anti-oxidation additives of the type CAS no. 6683-19-8 (Irganox® 1010). It may also contain UV protective additives, for example titanium dioxide or organic molecules which absorb the UV rays, whose purpose is to limit the decomposition of the polymer by the UV rays. The proportion of UV protection agents is dependent on the applicable legislation and known in the art. In general, a share of the order of 0.3% is used.

The middle layer, which can be reinforced by mineral fibers possibly combined with other fillers, initially contains in a thermoplastic matrix a mass fraction of an antioxidant additive of 0.1 to 1% above that of the inner layer.

The additive consists of 50%, preferably 75%, of a molecule with a molecular weight of less than 740 g / mol, which is provided with a higher ability to migrate in the thermoplastic matrix and gives it higher oxidation-induction times. This feature thus makes it possible to form a reservoir with antioxidant additives in the middle layer. The low molecular weight molecules will then migrate into the inner layer over time and be able to replace the additives that may be "washed out" over time by the aggressive media flowing in the pipeline.

A low molecular weight additive useful in the present invention may be of the type CAS no. 2082-79-3, which can be found under the trade name Irganox® 1076, or a HALS of the type Tinuvin® 622.

In another preferred embodiment, an additional low molecular weight antioxidant additive may be added to the inner layer to the limit of the remaining at most 25% in the form of a molecule whose molecular weight is above 740 g / mol. An oxidation-inhibiting additive of the type CAS no. 6683-19-8, which is available, for example, under the trade name Irganox® 1010, is suitable for the present invention.

The middle layer then contains a mixture of antioxidant additives comprising molecules whose different molecular weights range from 500 to 4100 g / mol. Thus, the additives will work together with a different molecular weight. The low molecular weight additives can migrate into the adjacent layers and form a reservoir to compensate for the losses of additives extracted from the inner layer aggressive media. By contrast, the higher molecular weight additives can fulfill their role as antioxidants in the middle layer.

The middle layer may also contain antimicrobial and / or antibacterial agents. The proportion of the antimicrobial and / or antibacterial agents is preferably in the range of 0.1% to 0.5% above that of the inner layer to form a reservoir for the inner layer.

• - die Innenschicht, die 99 Massenprozent PP-R, 0,30 Massenprozent primäres Oxidationsschutzmittel Irganox® 1330, 0,10 Massenprozent primäres Oxidationsschutzmittel Irganox® 1010, 0,1 Massenprozent sekundäres Oxidationsschutzmittel Irgafos® 168 und möglicherweise Pigmente, 0,3 Massenprozent Biozide enthält;
• - die Mittelschicht, die 99 Massenprozent PP-R, 0,5 Massenprozent primäres Oxidationsschutzmittel Irganox® 1076, 0,2 Massenprozent Irganox® 1010 und 0,1 Massenprozent sekundäres Oxidationsschutzmittel Irgafos® 168 enthält,
• - und die Außenschicht, die 99 Massenprozent PP-R, 0,1 Massenprozent primäres Oxidationsschutzmittel Irganox® 1010 und 0,3 Massenprozent UV-Schutzmittel enthält.

According to a first embodiment of the invention, the plastic tube comprises three layers of polypropylene random copolymer (PP-R):

• - the inner layer containing 99% by mass of PP-R, 0.30% by mass of Irganox® 1330 primary antioxidant, 0.10% by mass of Irganox® 1010 primary antioxidant, 0.1% by mass of Irgafos® 168 secondary antioxidant and possibly pigments, 0.3% by mass of biocides ;
• the middle layer containing 99% by weight of PP-R, 0.5% by weight of Irganox® 1076 primary antioxidant, 0.2% by weight of Irganox® 1010 and 0.1% by weight of Irgafos® 168 secondary antioxidant,
• and the outer layer containing 99% by mass of PP-R, 0.1% by mass of primary antioxidant Irganox® 1010 and 0.3% by mass of UV protectant.

• - die Innenschicht enthält 99 Massenprozent PP-R, 0,2 Massenprozent primäres Oxidationsschutzmittel Irganox® 1330, 0,3 Massenprozent primäres Oxidationsschutzmittel Irganox® 1010, 0,1 Massenprozent sekundäres Oxidationsschutzmittel Irgafos® 168 und möglicherweise Pigmente;
• - die Mittelschicht enthält 99 Massenprozent PP-R, 0,5 Massenprozent Irganox® 1076, 0,2 Massenprozent Irganox® 1010 und 0,1 Massenprozent Irgafos® 168;
• - die Außenschicht enthält 99 Massenprozent EVOH mit einer Dicke im Bereich von 0,1 - 0,3 mm, um das spätere örtlich begrenzte Abschälen zu ermöglichen, 0,1 Massenprozent Irganox® 1010, Irgafos® 168 und 0,3 Massenprozent UV-Schutzmittel;
• - die Haftschicht, die zwischen der Mittelschicht aus PP-R und der Außenschicht aus EVOH angeordnet ist, enthält 99 Massenprozent eines mit Maleinsäureanhydrid gepfropften Polypropylen-Copolymers.

According to a second embodiment of the invention, the plastic pipe comprises four layers of PP-R and ethylene-vinyl alcohol copolymer (EVOH):

• - the inner layer contains 99% by mass of PP-R, 0.2% by mass of Irganox® 1330 primary antioxidant, 0.3% by mass of Irganox® 1010 primary antioxidant, 0.1% by mass of Irgafos® 168 secondary antioxidant and possibly pigments;
• the middle layer contains 99 mass% PP-R, 0.5 mass% Irganox® 1076, 0.2 mass% Irganox® 1010 and 0.1 mass% Irgafos® 168;
• the outer layer contains 99% by mass of EVOH having a thickness in the range of 0.1-0.3 mm to allow subsequent localized peeling, 0.1% by mass Irganox® 1010, Irgafos® 168 and 0.3% by mass UV protectant ;
• The adhesive layer disposed between the PP-R middle layer and the EVOH outer layer contains 99% by mass of a maleic anhydride-grafted polypropylene copolymer.

According to a third embodiment of the invention, the plastic pipe PP-R 6 can comprise layers of which an EVOH layer is added by means of adhesive layers between the middle layer, the antioxidant additives having a molecular weight of less than 74 0 g / mol, and the outer layer , The outer layer of PP-R allows assembly by hot welding.

Although the invention will be described in conjunction with several particular embodiments, it is to be understood that it is in no way limited and includes all technical equivalents of the means described, as well as their combinations, if they come within the scope of the invention. For example, the EVOH layer could be replaced by a polyamide layer or PVDF fluorinated polymer layer without providing any innovation.

Claims (11)

Tube of extruded or injection molded thermoplastic material for pipelines carrying hot or cold fluids comprising at least three layers whose middle layer is reinforced by mineral fibers, characterized in that the middle layer in the thermoplastic matrix contains oxidation inhibiting additives or a mixture of antioxidant additives which can migrate into the adjacent layers and whose proportion is greater than that in the adjacent layers and of which at least 50% of a molecule having a molecular weight below 740 g / mol are formed to form a "reservoir" containing it makes it possible to compensate for the losses of oxidation-inhibiting additives over time, the middle layer in its thermoplastic matrix initially having a mass fraction of an antioxidant additive of 0.1 to 1% above that of the inner layer. Connector made of an extruded or injection molded thermoplastic material for pipelines carrying hot or cold fluids comprising at least three layers whose middle layer is reinforced by mineral fibers, characterized in that the middle layer in the thermoplastic matrix contains oxidation inhibiting additives or a mixture of antioxidant additives which can migrate into the adjacent layers and whose proportion is greater than that in the adjacent layers and of which at least 50% of a molecule having a molecular weight below 740 g / mol are formed to form a "reservoir" containing it makes it possible to compensate for the losses of oxidation-inhibiting additives over time, the middle layer in its thermoplastic matrix initially having a mass fraction of an antioxidant additive of 0.1 to 1% above that of the inner layer. Device made of an extruded or injection-molded thermoplastic material according to Claim 1 or 2 , characterized in that the mineral fibers are combined with other fillers. Device made of an extruded or injection-molded thermoplastic material according to one of Claims 1 to 3 , characterized in that the proportion of antioxidant additives is greater than that in the adjacent layers, wherein at least 75% of a molecule having a molecular weight of less than 740 g / mol are formed. Device made of an extruded or injection-molded thermoplastic material according to one of Claims 1 to 4 , characterized in that the thermoplastic material of the layers is a polyolefin and / or a polyamide and / or a polyvinylidene fluoride and / or a polyvinyl chloride and / or a post-chlorinated polyvinyl chloride and preferably a polypropylene random copolymer (PP-R). Device made of an extruded or injection-molded thermoplastic material according to one of the preceding claims, characterized in that the middle layer also contains in its thermoplastic matrix an oxidation-inhibiting additive which is composed of a molecule whose molecular weight is above 740 g / mol. Device made of an extruded or injection-molded thermoplastic material according to any one of the preceding claims, characterized in that the middle layer contains in its thermoplastic matrix a mixture of antioxidant additives comprising molecules whose different molecular weights range from 500 to 4100 g / mol. Device of extruded or injection-molded thermoplastic material according to any one of the preceding claims, characterized in that the inner layer which comes into contact with the medium to be transported initially contains 0.1 to 0.5% by mass of antioxidant additives. Device made of an extruded or injection-molded thermoplastic material according to Claim 7 , characterized in that at least 50% of the additives in the inner layer have a molecular weight of more than 740 g / mol. Device made of an extruded or injection-molded thermoplastic material according to one of the preceding claims, characterized in that the inner layer also contains an initial mass fraction of 0.1% to 0.6% antimicrobial and / or antibacterial agents. Device made of an extruded or injection-molded thermoplastic material according to Claim 1 or 2 , characterized in that the outer layer initially contains 0.4% by mass of antioxidant additives and additives which prevent the penetration of UV rays.