Propylene-based composition for pipes

Abstract

A sheet or pipe system comprising a composition comprising a propylene based polymer having the melt flow rate (MFR) (ISO 1133 230°C, 5 kg) ranging from 0.2 to 10.0 g / 10 min, and sodium hypophosphite, monohydrate.

Description

TITLEPROPYLENE-BASED COMPOSITION FOR PIPESFIELD OF THE INVENTION

[0001] The present disclosure relates to sheets or pipe systems comprising a composition comprising a propylene based polymer and sodium hypophosphite, monohydrate having high values of full notch creep test.BACKGROUND OF THE INVENTION

[0002] Pipes, tubing and fittings are intended within the term of pipe systems.

[0003] The term sheets includes sheets for thermoforming and plates to be used in the preparation of semi-finished products such as those employed in chemical industry.

[0004] The sheets or plates are mainly being used in the production of articles such as containers for housewares and food, for example juice containers, yogurt cups, margarine tubs and others. Said sheets or plates can also be used in the production of automotive parts.

[0005] The pipe systems according to the present invention are particularly suitable to transport, outdoor and indoor, fluids under high pressure and / or gravity sewerage and their handling during installation is very easy.

[0006] Thus there is the need of materials having enhanced properties.

[0007] WO 2018 / 202791 relates to polypropylene composition comprising a propylene polymer and sodium hypophosphite, monohydrate. However this document is completely silent about sheet and pipe systems.SUMMARY OF THE INVENTION

[0008] The applicant found it is possible to obtain sheets or pipe systems having improved values of full notch creep test and heat aging test at 150°C. Thus an object of the present disclosure is a sheet or pipe system comprising a composition comprising a propylene based polymer having the melt flow rate (MFR) (ISO 1133 230°C, 5 kg) ranging from 0.2 to 10.0 g / 10 min, and sodium hypophosphite, monohydrate:DETAILED DESCRIPTION OF THE INVENTION

[0009] The applicant found it is possible to obtain sheets or pipe systems having improved values of full notch creep test and heat aging test at 150°C. Thus an object of the present disclosure is a sheet or pipe system comprising a composition comprising a propylene based polymer having the melt flow rate (MFR) (ISO 1133 230°C, 5 kg) ranging from 0.2 to 10.0 g / 10 min, preferably ranging from 0.5 to 7.0 g / 10 min more preferably from 0.7 to 2.5 g / 10 min from and sodium hypophosphite, monohydrate:

[0010] The propylene based polymer is a polymer containing from 50 wt% to 100 wt% of propylene derived units. Examples of propylene based polymer is selected from the group consisting of propylene homopolymer, propylene copolymers, random propylene copolymers, heterophasic propylene copolymers and propylene terpolymers. The comonomers in the propylene copolymers and terpolymers are ethylene, 1 -butene, 1 -hexene or 1 -octene. Preferably ethylene is used. Preferably the propylene based polymer is a propylene homopolymer or a propylene ethylene random copolymers having an ethylene content ranging from 0.2 wt% to 5.0 wt%. Wherein the random copolymers are copolymers having a content of isolated ethylene units 1(E) measured by13C- NMR higher than 30 wt%. Wherein 1(E) is calculated with the following relation:I(E)= (PEP / EEE+PEE+PEP)xl00;Wherein 1(E) is the relative content of isolated to block ethylene sequences (%); PEP is the mol fraction of propylene / ethylene sequences in the sample; PEE is the mol fraction of propylene / ethylene sequences in the sample; EEE is the mol fraction of propylene / ethylene sequences in the sample and wherein all sequence concentrations being based on a statistical triad analysis of13C-NMR data.

[0011] Sodium hypophosphite, monohydrate is a commercial additive know for example as Ultranox LC. In the propylene based composition, sodium hypophosphite, monohydrate ranges preferably from 0.0200 wt% to 0.1000 wt% based on the total weight of the composition, preferably ranges from 0.0300 wt% to 0.0800 wt%, more preferably from 0.0400 wt% to 0.0600 wt%.

[0012] Other additives commonly known in the art can be added to the composition used for forming sheet and pipe systems of the present disclosure, such as such as antioxidants, light stabilizers, heat stabilizers, colorants and fillers. Preferably Tris(2,4-ditert-butylphenyl)phosphate, sold for example as Irgafos 168, is added to the composition with an amount ranging from 1.0000wt% to 0.0500 wt% based on the total weight of the composition; more preferably from 0.5000 wt% to 0.1000 wt%; even more preferably from 0.3500 wt% to 0.1500 wt%.

[0013] With the composition of the present invention it is possible to obtain sheet or pipe systems having an enhanced full notch creep test, and heat aging test at 150°C.

[0014] The term sheets includes sheets for thermoforming and plates to be used in the preparation of semi-finished products such as those employed in chemical industry.

[0015] The sheets or plates are mainly being used in the production of articles such as containers for housewares and food, for example juice containers, yogurt cups, margarine tubs and others. Said sheets or plates can also be used in the production of automotive parts. The thickens of the sheet is higher than 0.2 mm; preferably higher than 0.5 mm, more preferably higher than 1.0 mm, being lower than 5.0 mm.

[0016] The term "pipe system" as used herein also includes pipe fittings, valves and all parts which are commonly necessary for e.g. a hot water piping system. Also included within the definition are single and multilayer pipes, where for example one or more of the layers is a metal layer and which may include an adhesive layer.

[0017] Such articles can be manufactured through a variety of industrial processes well known in the art, such as for instance moulding, extrusion, and the like.

[0018] The composition of the present disclosure can optionally comprise an inorganic filler agent in an amount ranging from 0.5 to 60 parts by weight with respect to 100 parts by weight of the said composition. Typical examples of such filler agents are calcium carbonate, barium sulphate, titanium bioxide and talc. Talc and calcium carbonate are preferred. A number of filler agents can also have a nucleating effect, such as talc that is also a nucleating agent. The amount of a nucleating agent is typically from 0.2 to 5 wt% with respect to the polymer amount.

[0019] Other additives commonly known in the art can be added to the composition used for forming sheet and pipe systems of the present disclosure, such as such as antioxidants, light stabilizers, heat stabilizers, colorants and fillers.

[0020] The value of full notch creep test, (80 °C, 4 MPa, Arkopal 2 % NIOO, ISO 16770), of the sheet and pipe system of the present disclosure can be higher than 600 h, preferably higher than 650 h, more preferably higher than 720 h. The value being lower than 2500 h.

[0021] The value of heat aging test at 150°C can be higher than 2160 h ; preferably higher than 2400 h, more preferably higher than 2640 h. The value being lower than 3192 h10022] The following examples are given to illustrate the present disclosure without limiting purpose.EXAMPLESCharacterization methodsMelting temperature and crystallization temperature: Determined by differential scanning calorimetry (DSC), weighting 6 ±1 mg, is heated to 220 ±1° C at a rate of 20 °C / min and kept at 220 ±1° C for 2 minutes in nitrogen stream and it is thereafter cooled at a rate of 20° C / min to 40 ±2° C, thereby kept at this temperature for 2 min to crystallise the sample. Then, the sample is again fused at a temperature rise rate of 20° C / min up to 220° C ±1. The melting scan is recorded, a thermogram is obtained, and, from this, melting temperatures and crystallization temperatures are read.Melt Flow Rate: Determined according to the method ISO 1133 (230° C, 5 kg).Solubility in xylene: Determined as follows.Xylene Solubles at 25°C have been determined according to ISO 16 152.Ethylene (C2) content13C NMR of propylene / ethylene copolymers

[0023] 13C NMR spectra were acquired on a Bruker AV-600 spectrometer equipped with cryoprobe, operating at 160.91 MHz in the Fourier transform mode at 120°C.

[0024] The peak of the Spp carbon (nomenclature according to “Monomer Sequence Distribution in Ethylene-Propylene Rubber Measured by 13C NMR. 3. Use of Reaction Probability Mode ” C. J. Carman, R. A. Harrington and C. E. Wilkes, Macromolecules, 1977, 10, 536) was used as internal reference at 29.9 ppm. The samples were dissolved in 1, 1,2,2- tetrachloroethane-d2 at 120°C with a 8 % wt / v concentration. Each spectrum was acquired with a 90° pulse, 15 seconds of delay between pulses and CPD to remove 1H-13C coupling. 512 transients were stored in 32K data points using a spectral window of 9000 Hz.

[0025] The assignments of the spectra, the evaluation of triad distribution and the composition were made according to Kakugo (“Carbon- 13 NMR determination of monomer sequence distribution in ethylene-propylene copolymers prepared with 8-titanium trichloride-diethylaluminum chloride” M. Kakugo, Y. Naito, K. Mizunuma and T. Miyatake, Macromolecules, 1982, 15, 1150) using the following equations:PPP = 100 Tpp / S PPE = 100 Tps / S EPE = 100 Tss / SPEP = 100 Spp / S PEE= 100 Sps / S EEE = 100 (0.25 Syg+0.5 S55) / SS = Tpp + Tps + Tss + Spp + Sps + 0.25 Syg + 0.5 Sss

[0026] The molar percentage of ethylene content was evaluated using the following equation: E% mol = 100 * [PEP+PEE+EEE]The weight percentage of ethylene content was evaluated using the following equation:100 * E% mol * MWEE% wt. = >E% mol * MWE + P% mol * MWp

[0027] where P% mol is the molar percentage of propylene content, while MWE and MWp are the molecular weights of ethylene and propylene, respectively.

[0028] The content of isolated ethylene units 1(E) measured by13C- NMR is calculated with the following relationI(E)= (PEP / EEE+PEE+PEP)xl00;

[0029] The tacticity of Propylene sequences was calculated as mm content from the ratio of the PPP mmTpp (28.90-29.65 ppm) and the whole Tpp (29.80-28.37 ppm).

[0030] Ethylene C2 content of component b2 has been measured by measuring the C2 content on component B) and then calculated by using the formula C2tot=Xbl C2bl+Xb2C2b2 wherein Xbl and Xb2 are the amounts of components bl and b2 in the composition.Elongation at yield: measured according to ISO 527.Elongation at break: measured according To ISO 527Stress at break: measured according to ISO 527.Impact test: ISO 180-1 ASamples for the mechanical analysisSamples have been obtained according to ISO 1873-2:2007 excepting for the flexural modulus for which ISO 3167 has been used.Flexural ModulusDetermined according to ISO 178.Full notch creep test, FNTCFNTC is measured at 80 °C, 4 MPa, Arkopal 2 % N100, according to ISO 16770.Preparation of compositionHostalen PP H2150 is a commercial propylene homopolymer sold by Lyondellbasell having an MFR (230°C 5 kg) of 1.3. This homopolymer has been blended with the additives packages of table 1.Table 1AO1010 CAS 6683-19-8CaStearate High Quality CAS 85251-71-4DSTDP CAS 693-36-7MS 168 CAS 31570-04-4Sodium hypophosphite, monohydrate CAS 10039-56-2FNTC of example 1 and comparative example 2 has been measured the results are reported on table 2.Table 2Table 2 shows that the FNTC has been improved.Heat aging test

[0031] The composition of example 1 has been subjected to an heat aging test according to ISO 4577 :2019 with the following deviations: punched specimens: 38.5 mm x 13 mm instead of 50 mm x 10 mm; storage in the oven on silicone mats instead of specimen holder ; visual inspection weekly instead of daily ; instead of the mean time until damage in days at 150 °C for the five specimens, the time until damage of the first specimen is recorded with a tolerance of +0 / -7 days;Test specimen preparation for heat aging test (Table 2 of ISO 15013)

[0032] Pellets were pressed into a (400 x 400 x 1) mm compression molded sheet according to DIN EN ISO 293:2005 at 210 °C. From the sheet five test specimens (38.5 xl 3x 1) mm were punched out and an additional sheet (100 x 200 xl) mm were cut out for thermal ageing testing.

[0033] Following ISO 4577 :2019 the test specimens are placed in an oven at a test temperature of 150°C ± 0.5°C for thermal aging. Samples are inspected weekly for signs of localized discoloration and embrittlement. Deviating from the standard, the period of time is determined in days until visible signs of local discoloration and embrittlement appear on the first sample.

[0034] After 2688 h visible signs of local discoloration and embrittlement appeared on the sample.

Claims

CLAIMSWhat is claimed is:

1. A sheet or pipe system comprising a composition comprising a propylene based polymer having the melt flow rate (MFR) (ISO 1133 230°C, 5 kg) ranging from 0.2 to 10.0 g / 10 min, and sodium hypophosphite, monohydrate.

2. The sheet or pipe system according to claim 1 wherein the propylene based polymer has the melt flow rate (MFR) (ISO 1133 230°C, 5 kg) ranging from 0.5 to 7.0 g / 10 min.

3. The sheet or pipe system according to any of claims 1-2 wherein the propylene based polymer has the melt flow rate (MFR) (ISO 1133 230°C, 5 kg) ranging from 0.7 g / 10 min to 2.5 g / 10 min.

4. The sheet or pipe system according to any of claims 1-3 wherein the propylene based polymer is propylene homopolymer or propylene ethylene copolymer.

5. The sheet or pipe system according to any of claims 1-4 wherein the propylene based polymer is propylene homopolymer.

6. The sheet or pipe system according to any of claims 1-5 wherein the propylene based polymer is a propylene ethylene random copolymers having an ethylene content ranging from 0.2 wt% to 5.0 wt%.

7. The sheet or pipe system according to any of claims 1-6 wherein the propylene based polymer is a propylene ethylene random copolymers having an ethylene content ranging from 0.2 wt% to 5.0 wt% and wherein the random copolymers are copolymers having a content of isolated ethylene units 1(E) measured by13C- NMR higher than 30 wt%; wherein 1(E) is calculated with the following relationI(E)= (PEP / EEE+PEE+PEP)xl00; wherein 1(E) is the relative content of isolated to block ethylene sequences (%); PEP is the mol fraction of propylene / ethylene sequences in the sample; PEE is the mol fraction of propylene / ethylene sequences in the sample; EEE is the mol fraction of propylene / ethylene sequences in the sample and wherein all sequence concentrations being based on a statistical triad analysis of13C-NMR data.

8. The sheet or pipe system composition according to any of claims 1-7 wherein in the propylene based composition, sodium hypophosphite, monohydrate ranges from 0.0200 wt% to 0.1000 wt% based on the total weight of the composition.

9. The sheet or pipe system comprising a polyolefin composition according to claims 1 to 8 wherein in the propylene based composition, sodium hypophosphite, monohydrate ranges from 0.0300 wt% to 0.0800 wt% based on the total weight of the composition.

10. The sheet or pipe system comprising a polyolefin composition according to claims 1 to 9 wherein in the propylene based composition, sodium hypophosphite, monohydrate range from 0.0400 wt% to 0.0600 wt% based on the total weight of the composition.

11. The sheet or pipe system comprising a polyolefin composition according to claims 1 to 10 wherein the propylene based composition further contains tris(2,4-ditert-butylphenyl)phosphate with an amount ranging from 1.0000 wt% to 0.0500 wt% based on the total weight of the composition.

12. The sheet or pipe system comprising a polyolefin composition according to claims 1 to 11 wherein the amount of tris(2,4-ditert-butylphenyl)phosphate ranges from 0.5000 wt% to 0.1000 wt%.

13. The sheet or pipe system comprising a polyolefin composition according to claims 1 to 12 wherein the amount of tris(2,4-ditert-butylphenyl)phosphate ranges from 0.3500 wt% to 0.1500 wt%.

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