WO2021043785A1

WO2021043785A1 - A pipe containing carboxylic acid amide for the transport of water containing chlorinated disinfectant

Info

Publication number: WO2021043785A1
Application number: PCT/EP2020/074387
Authority: WO
Inventors: Patrick Elisabeth Luc Voets; Mark Johannes Boerakker
Original assignee: Sabic Global Technologies B.V.
Priority date: 2019-09-03
Filing date: 2020-09-02
Publication date: 2021-03-11

Abstract

The present invention relates to a pipe suitable for the transport of water containing chlorinated disinfectant wherein the pipe comprises a polymer composition wherein the polymer composition comprises a polyolefin and a carboxylic acid amide. The present invention further relates to a process to prepare the pipe and the use of the pipe. The present invention further relates to the use of the polymer composition in a pipe for the transport of water containing chlorinated disinfectant.

Description

A pipe containing carboxylic acid amide for the transport of water containing chlorinated disinfectant

Description

The term “pipe” is herein understood as a hollow elongated article. The cross section may be of various shapes e.g. be circular, elliptical, square, rectangular or triangular. Pipes for the transport of gas, for sanitation and for water supply may be produced with polyolefin compositions, for example polyethylene or polypropylene compositions. Pipes based on a polyolefin have a very good resistance to water. However their lifetime is shortened when the pipes come into contact with chlorinated disinfectants which are often added to water for hygienic reasons. Chlorine is present in most disinfected drinking-water at concentrations of 0.2 to 1 mg/litre (White GC. Current chlorination and dechlorination practices in the treatment of potable water, wastewater and cooling water. In: Jolley RL, ed. Water chlorination: environmental impact and health effects. Vol. 1. Ann Arbor, Ml, Ann Arbor Science, 1978:1-18.) . Chlorine dioxide used as disinfectant in water degrades most materials including polyolefin (Colin, Aging of polyethylene pipes transporting drinking water disinfected by chlorine dioxide, part I, Chemical aspects; Polymer engineering and Science 49(7); 1429-1437; July 2009). Other chlorinated solvents are for example chloramine and chlorine. It is known in the art to use additives, for example antioxidants and stabilizers to prevent said degradation.

WO2017055253 discloses a pipe for the transport of water with improved resistance to chlorinated disinfectants. The pipe is produced with a polymer composition comprising a polyolefin and styrene isoprene block copolymer. WO2017133918 discloses a pipe for the transport of water with improved resistance to chlorinated disinfectants. The pipe is produced with a polymer composition comprising polyethylene and zinc sulfide.

It is the object of the present invention to provide a pipe suitable for the transport of water containing chlorinated disinfectant, “suitable for the transport of water containing chlorinated disinfectant” is meant the pipe for the transport of water containing chlorinated disinfectants has improved lifetime, wherein the chlorinated disinfectant can for example be chlorine dioxide, chloramine and chlorine, wherein the improvement is characterized in that the polymer composition according to the invention has a retention value of at least 80 %, wherein the retention value is calculated as the ratio between the elongations at break as measured according to ISO IS0527-1 :2012 at room temperature (23 °C) at a strain rate of 50 mm/min of an aged specimen and of a non-aged specimen, wherein the aging can be conducted in continuous water flow at a temperature of 70 ^eC with a chlorine dioxide concentration maintained at 4.4 ppm and a pH maintained at 6.8 22.71 L/h as flow rate and 1000 hrs as age duration.

This object is achieved by a pipe suitable for the transport of water containing chlorinated disinfectant, wherein the pipe comprises a polymer composition wherein the polymer composition comprises a polyolefin and a carboxylic acid amide wherein the amount of polyolefin is at least of 95 wt% to the total amount of the polymer composition and the amount of carboxylic acid amide is in the range of 0.08 to 3 wt% based on the total amount of the polymer composition.

In the present invention, it was surprisingly found that the the pipe for the transport of water containing chlorinated disinfectants according to the invention has improved lifetime.

Carboxylic acid amide is a widely used polymer additive. For example, US4701487A discloses a processing aid which comprises an amide of a saturated or unsaturated carboxylic acid or a saturated or unsaturated alkylene bis-amide of a saturated or unsaturated dicarboxylic acid. In another example, US8865809B2 disclosed a fatty acid amide, its application areas are as a slip and/or anti-blocking agent or mold release agent.

Polyolefin In the present invention, the polyolefin in the polymer composition in the pipe may be a polyethylene for example high density polyethylene or a polypropylene.

For example, the density of high density polyethylene according to the present invention is at least 0.935 g/cm³, at least 0.938 g/cm³, at least 0.940 g/cm³, at least 0.942 g/min³ and/or at most 0.960 g/cm³ according to ISO 1183-1 :2004.

In the present invention, it is preferable that the polyolefin is a polypropylene, for example heterophasic polypropylene or homogeneous polypropylene. The melt flow index (MFI) of the polypropylene is in the range of 0.01 to 3.0 dg/min, more preferably in the range of 0.05 to 2.5 dg/min, even more preferably in the range of 0.1 to 1 .8 dg/min measured according to IS01133- 1 :2011 (2.16 kg/230°C).

The catalyst used to produce the polypropylene according to the present invention is known to the people skilled in art, for example Ziegler-Natta catalyst or metallocene catalyst. Preferably, the polypropylene according to the present invention is produced with a catalyst which is free of phthalate.

In the present invention, it is preferable that the polypropylene is a homogeneous polypropylene. The homogeneous polypropylene may be a propylene homopolymer or a propylene random copolymer, the propylene random copolymer is prepared from propylene and at least one comonomer chosen from a group consisting of ethylene, a-olefin having 4 to 10 carbon atoms or mixtures thereof.

In the present invention, it is preferable that the propylene random copolymer comprises ethylene comonomer, wherein the amount of ethylene comonomer is from 0.50 to 5.0 wt%, more preferably from 1.4 to 4.5 wt%, more preferably from 3.0 to 4.2 wt% based on the total amount propylene random copolymer.

For example, the propylene random copolymer comprises ethylene and 1 -hexene comonomer.

Preferably the propylene random copolymer is a propylene-ethylene copolymer. The amount of the polyolefin in the polymer composition in the pipe is at least 95.0 wt%, more preferably at least 97.0 wt%, more preferably at least 98.5 wt% based on the total amount of the polymer composition.

Carboxylic acid amide

The carboxylic acid amide in the polymer composition in the pipe according to the invention is preferably an aliphatic carboxylic acid amide with an amide group CONH₂ group and an alkyl tail. The carboxylic acid amide is represented by the formula F -CONhb, wherein R¹ is a linear or branched alkyl group containing 9 to 29 carbon atoms. The aliphatic carboxylic acid amide can be saturated carboxylic acid amides or unsaturated carboxylic acid amides or mixtures thereof. In the unsaturated carboxylic acid amides at least one carbon-carbon double bond is present in the alkyl tail.

Examples of saturated carboxylic acid amides are stearamide, palmitamide, cocamide, lauricamide, myristamide, capricamide, tallowamide, myristicamide, margaric (daturic) amide, arachidic amide, behenic amide, lignoceric amide, cerotic amide, montanic amide, melissic amide, lacceroic amide, ceromelissic (psyllic) amide, geddic amide, 9-octadecen amide or mixtures thereof.

Preferably, the carboxylic acid amide is an unsaturated aliphatic carboxylic acid amide selected from the group of oleamide, linoleic amide, erucamide, myristoleic amide, palmitoleicamide, sapienic amide, elaidic amide, vaccenic amide, arachidonic amide, eicosapentaenoic amide, docosahexaenoic amide or mixtures thereof.

The number of carbon atoms in the carboxylic acid amides is preferably from 10 to 30, preferably from 12 to 28, more preferably from 14 to 26, most preferably from 16 to 24.

Preferable the carboxylic acid amide comprises at least 50 wt%, perferably 100 wt% of erucamide based on the total amount of the carboxylic acid amide.

The amount of carboxylic acid amide in the polymer composition is in the range from 0.08 to 3.0 wt%, preferably from 0.10 to 2.5 wt%, more preferably from 0.20 to 2.0 wt%, even more preferably from 0.30 to 1 .5 wt% based on the total amount of the polymer composition. Other components in the polymer composition

The polymer composition in the pipe according to the invention may contain other components. Components suitable for use in pipes include but are not limited to nucleating agents, stabilizers, anti-oxidants pigments and/or colorants, impact modifiers, flame retardants, acid scavengers, anti-microbials and the like. Such additives are well known in the art. The skilled person will choose the type and amount of additives such that they do not detrimentally influence the aimed properties of the composition.

Process and use

The invention further relates to a process for the preparation of the polymer composition in the pipe according to the invention, wherein said process preferably comprises a step of melt mixing the polyolefin, the carboxylic acid amide and optionally other components in an extruder. There are two advantageous points of such process: The polymer composition is obtainable in the form of pellet or granular which is easy to be processed into a shaped article; The obtained polymer composition is homogeneous and has well-defined concentrations of the additives.

Suitable conditions for melt-mixing, such as temperature, pressure, amount of shear, screw speed and screw design when an extruder is used are known to the skilled person.

The present invention further relates to a process for the preparation of a pipe comprising a step of extruding the polymer composition of the invention to obtain a pipe.

The amount of the polymer composition is at least 95 wt%, preferably at least 97 wt%, more preferably at least 98 wt% based on the total amount of the pipe.

The present invention further relates to the use of the the aforementioned polymer composition for preparation of a pipe for the transport of water containing chlorinated disinfectant.

The present invention further relates to the use of the aforementioned pipe for the transport of water containing chlorinated disinfectant. Although the invention has been described in detail for purposes of illustration, it is understood that such detail is solely for that purpose and variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined in the claims.

It is further noted that the invention relates to all possible combinations of features described herein, preferred in particular are those combinations of features that are present in the claims.

It is further noted that the term ‘comprising’ does not exclude the presence of other elements. However, it is also to be understood that a description on a product comprising certain components also discloses a product consisting of these components. Similarly, it is also to be understood that a description on a process comprising certain steps also discloses a process consisting of these steps.

The range of values “A to B” used herein is understood to mean “at least A and at most B”.

The invention is now elucidated by way of the following examples, without however being limited thereto.

Examples

SABIC PP 9421 (Resin) was used as base polymer in all the examples and a propylene random copolymer with MFI of 0.28 g/10min measured according to IS01133-1 :2011 (2.16 kg / 230 °C) and total ethylene content of 3.9 wt% determined by ¹³C-NMR. The resin was melt-mixed with the following components as examples for the present invention:

• Styrene-isoprene-styrene block copolymer: Kraton D1113PT obtained from Kraton Polymers U.S. LLC;

• Carboxylic acid amide: Crodamide ER from Croda.

• ZnS in the form of powder. Neat SABIC PP 9421 was used as reference, amount of the styrene-isoprene-styrene block copolymer, Carboxylic acid amide and ZnS is shown in Table 1 , “wt%” in table 1 is based on the total amount of the example. Exampless were compression molded using IS01872-2:2007 into plaques, then plaques were cut into tensile bars according to IS0527-1 :2012 (4 mm thick) as testing specimens.

Ageing test: The testing specimens were aged in a continuous water flow at a temperature of 70 ^eC with a chlorine dioxide concentration maintained at 4.4 ppm and a pH maintained at 6.8. Flow rate was regulated at 22.71 L/h. The testing samples were aged for 1000 hrs.

Tensile tests according to Plastics- Determination of tensile properties IS0527-1 :2012 at room temperature (23 °C) at a strain rate of 50 mm/min on aged and non-aged specimens were performed, the elongation at break are reported in Table 1.

Retention is defined as the ratio between elongation at break after aging and elongation at break before aging. A higher value of retention indicates that the example has better resistance against chlorine. For the purpose of the present invention, a polymer composition to be used in a pipe suitable for the transport of water containing chlorinated disinfectant has a retention value higher than 80 %.

Table 1 : Elongation at break before, after aging and retention According to table 1 , the inventive example with 0.3 wt% carboxylic acid amide has a higher retention value than the comparative examples which contain 0.5 wt% styrene-isoprene- styrene block copolymer and ZnS respectively. This indicates that the inventive example has better resistance against chlorine than comparative examples.

Clearly the composition according to the present invention is suitable to be used in a pipe for the transport of water containing chlorinated disinfectants, for example chlorine dioxide, chloramine and chlorine.

Claims

1. Pipe suitable for the transport of water containing chlorinated disinfectant, wherein the pipe comprises a polymer composition, wherein the polymer composition comprises a polyolefin and a carboxylic acid amide, wherein the amount of polyolefin is at least of 95.0 wt% to the total amount of the polymer composition and the amount of carboxylic acid amide is in the range of 0.08 to 3.0 wt% based on the total amount of the polymer composition, wherein the polyolefin is a polypropylene.

2. Pipe according to claim 1 wherein the amount of carboxylic acid amide is in the range from 0.10 to 2.5 wt%, more preferably from 0.20 to 2.0 wt%, even more preferably from 0.30 to 1 .5 wt% based on the total amount of the polymer composition.

3. Pipe according to claims 1 or 2 wherein the carboxylic acid amide is an unsaturated aliphatic carboxylic acid amide selected from the group of oleamide, linoleic amide, erucamide, myristoleic amide, palmitoleicamide, sapienic amide, elaidic amide, vaccenic amide, arachidonic amide, eicosapentaenoic amide, docosahexaenoic amide or mixtures thereof.

4. Pipe according to any one of the claims 1 to 3 wherein the carboxylic acid amide comprises at least 50 wt%, preferably 100 wt% erucamide based on the total amount of the carboxylic acid amide.

5. Pipe according to any one of the claims 1 to 4 wherein the amount of polyolefin is at least 97.0 wt%, more preferably at least 98.5 wt% based on the total amount of the polymer composition.

6. Pipe according to any one of the claims 1 to 5 wherein the polypropylene has a melt flow index (MFI) in the range of 0.01 to 3.0 dg/min measured according to IS01133-1 :2011 (2.16 kg/230°C)

7. Pipe according to any one of the claims 1 to 6wherein the polypropylene is a propylene random copolymer, wherein the propylene random copolymer is prepared from propylene and at least one comonomer chosen from a group consisting of ethylene, a-olefin having 4 to 10 carbon atoms or mixtures thereof.

8. Pipe according to any one of the claims 1 to 7, wherein the propylene random copolymer comprises ethylene comonomer, wherein the amount of ethylene comonomer is from 0.50 to 5.0 wt%, more preferably from 1 .4 to 4.5 wt%, more preferably from 3.0 to 4.2 wt% based on the total amount propylene random copolymer.

9. Pipe according to any one of the claims 1 to 8, wherein the propylene random copolymer comprises ethylene and 1 -hexene comonomer.

10. Pipe according to any one of the claims 1 to 9, wherein the propylene random copolymer is a propylene-ethylene copolymer.

11 . Pipe according to any one of the previous claims wherein the amount of the polymer composition is at least 95 wt%, preferably at least 97 wt%, more preferably at least 98 wt% based on the total amount of the pipe.

12. A process for the preparation of a pipe comprising a step of extruding the polymer composition of any one of claims 1 to 11 to obtain a pipe.

13. Use of the polymer composition of any one of claims 1 to 11 for the preparation of a pipe, preferably of a pipe for the transport of water containing chlorinated disinfectant.

14. Use of the pipe according to any one of claims 1 to 11 for the transport of water containing chlorinated disinfectant.