FIBER COMPRISING A PROPYLENE BASED POLYMERS COMPOSITION

Abstract

 A fiber comprising propylene based polymer composition comprising:
A) from 90 wt% to 65 wt% of a propylene homopolymer having a Xylene Soluble fraction at 25°C,determined according to ISO 16152: 2005, ranging from 1.5 wt% to 6.0 wt% ;
B) from 10 wt% to 35 wt% a recycled polypropylene composition being a Post-Industrial Resin (PIR) or Post-Consumer Resin (PCR) ;
wherein the propylene based polymer composition has a Melt Flow Rate, determined according to the method ISO 1133 (230° C, 2.16 kg), ranging from 15.0 g/10 min to 50.0 g/10 min and a distribution of molecular weight Mw/Mn ranging from 4.5 to 7.5 and the propylene based polymer composition being obtainable with a visbreaking process wherein the visbreaking degree MFRfin/MFRinit is comprised between 3.0 and 10.0 wherein MFRfin is the final Melt Flow Rate of the propylene based composition and MFRinit is the Melt Flow Rate of the propylene based composition before the visbreaking process.

Description

FIELD OF THE INVENTION

[0001] The present disclosure relates to fiber comprising a propylene based polymer composition comprising a propylene homopolymer and from 10 wt% to 35 wt% of a recycled polypropylene composition.

BACKGROUND OF THE INVENTION

[0002] In recent years, there has been increased interest in using recycled materials or fibers in disposable products, such as wipers. Generally, the thought is that using recycled materials are better for the environment and that the use of natural resources for disposable products leads to a waste of natural resources. In addition, increasing expenses associated with obtaining raw materials and constantly increasing consumption of various products provide a strong economic incentive for developing methods for recycling surplus or unused material, which would otherwise go to waste by being burned or placed in a landfill. However, the use of recycled materials and fibers has drawbacks. It is generally recognized in the art that recycled materials and fibers often result in products that have physical properties which are generally less acceptable than products made from virgin materials or fibers. As a result, the amount of recycled materials or fibers used in products is often limited due to the lost in physical properties of products prepared from recycled fibers.

[0003] Thus there is a need in the art for fibers which are at least partially prepared from recycled materials which have properties at least comparable to those products made with virgin materials.

SUMMARY OF THE INVENTION

[0004] Thus an object of the present disclosure is a fiber comprising propylene based polymer composition comprising:

A) from 90 wt% to 65 wt% of a propylene homopolymer having a Xylene Soluble fraction at 25°C, determined according to ISO 16152: 2005, ranging from 1.5 wt% to 6.0 wt% ;

B) from 10 wt% to 35 wt% a recycled polypropylene composition being a Post-Industrial Resin (PIR) or Post-Consumer Resin (PCR) ;

[0005] Wherein the propylene based polymer composition has a Melt Flow Rate, determined according to the method ISO 1133 (230° C, 2.16 kg), ranging from 15.0 g/10 min to 50.0 g/10 min and a distribution of molecular weight Mw/Mn ranging from 4.5 to 7.5 and

the propylene based polymer composition being obtainable with a visbreaking process wherein the visbreaking degree MFRfin/MFRinit is comprised between 3.0 and 10.0

wherein MFRfin is the final Melt Flow Rate of the propylene based composition and MFRinit is the Melt Flow Rate of the propylene based composition before the visbreaking process.

DETAILED DESCRIPTION OF THE IN VENTION

[0006] Thus an object of the present disclosure is a fiber comprising propylene based polymer composition comprising:

A) from 65 wt% to 90 wt% preferably from 68 wt% to 85 wt% of a propylene homopolymer having a Xylene Soluble fraction at 25°C,determined according to ISO 16152: 2005, ranging from 1.5 wt% to 6.0 wt%; preferably from 2.0 wt% to 5.0 wt%; more preferably from 2.2 wt% to 4.0 wt%.

B) from 10 wt% to 35 wt% preferably from 15 wt% to 32 wt% of a recycled polypropylene composition being a Post-Industrial Resin (PIR) or Post-Consumer Resin (PCR);

wherein the propylene based polymer composition has a Melt Flow Rate, determined according to the method ISO 1133 (230° C, 2.16 kg), ranging from 15.0 g/10 min to 50.0 g/10; preferably ranging from 18.0 g/10 min to 38.0 g/10;more preferably from 20.0 g/10 min to 35.0 g/10 mint and a distribution of molecular weight Mw/Mn ranging from 4.5 to 7.5; preferably from 5.0 to 7.2; more preferably from 5.5 to 6.8 and

the propylene based polymer composition being obtainable with a visbreaking process wherein the visbreaking degree MFRfin/MFRinit is comprised between 3.0 and 10.0; preferably from 4.0 and 9.0; more preferably 5.0 and 8.0;

wherein MFRfin is the final Melt Flow Rate of the propylene based composition and MFRinit is the Melt Flow Rate of the propylene based composition before the visbreaking process.

[0007] The recycled polypropylene composition contains preferably at least 50 wt%; more preferably at least 60 wt% ; even more preferably at least 70 wt% of derived units of propylene. The remaining comonomers can be ethylene; 1-butene; 1-hexene or 1-octene derived units; ethylene being preferred. Examples of propylene based polymer can be propylene homopolymer, propylene, ethylene heterophasic polymer, propylene ethylene 1-butene, propylene ethylene 1-hexene terpolymers and mixtures thereof.

[0008] Post-Industrial Resin (PIR) is the waste generated from the manufacturing process that is reclaimed or used again in the same material.

[0009] Post-Consumer Resin (PCR) defined as a resin used by the consumer for its intended purpose, that has reached its end of use, and then tossed into a recycling bin is excluded.

[0010] Preferably for the fiber of the present disclosure Post-Industrial Resin (PIR) is used.

[0011] Preferably The recycled polypropylene composition does not contains limonene.

[0012] Preferably the recycled polypropylene composition has the following features:

i) ethylene derived units content, measured by ¹³C-NMR, ranging from 0.3 mol% to 1.8 mol%, preferably ranging from 0.4 mol% to 1.7 mol%, more preferably ranging from 0.6 mol% to 0.4 mol%,;

ii) 1-butene derived units content, measured by ¹³C-NMR, ranging from 0.4 mol% to 2.5 mol%, preferably ranging from 0.5 mol% to 2.0 mol%, more preferably ranging from 0.7 mol% to 1.5 mol%;

iii) the C¹³ NMR sequences XEX wherein X can be a propylene derived unit or a 1-butene derived unit, ranging from 0.20 mol% to 0.55 mol%; preferably ranging from 0.25 mol% to 0.50 mol%, more preferably ranging from 0.32 mol% to 0.46 mol%;

iv) the C¹³ NMR sequences EEE ranging from 0.05 mol% to 0.40 mol%; preferably ranging from 0.10 mol% to 0.35 mol%, more preferably ranging from 0.15 mol% to 0.30 mol%;

v) the C¹³ NMR sequences XBX , X can be a propylene derived unit or a 1-butene derived unit ranging from 0.50 mol% to 2.20 mol%, preferably ranging from 0.68 mol% to 1.90 mol%, more preferably ranging from 0.75 mol% to 1.64 mol%;

vi) the C¹³ NMR sequences BBE are not present;

vii) melt flow rate, MFR, measured according to ISO 1133 at 230 °C with a load of 2.16 kg, ranging from 3.6 g/10 min to 11.4 g/10 min, preferably ranging from 5.6 g/10 min to 9.4 g/10 min, more preferably ranging from 6.6 g/10 min to 9.0 g/10 min;

viii) xylene soluble fraction at 25°C ranging from 4.8 wt% to 10.7 wt%, preferably ranging from 5.3 wt% to 9.8 wt%, more preferably ranging from 6.2 wt% to 9.2 wt%.

[0013] Preferably in the process of the present invention Post-Industrial Resin (PIR) is used.

[0014] Preferably component B contains only propylene ethylene and 1-butene as comonomers.

[0015] As reported above the propylene based polymer composition of the present disclosure is obtainable with a visbreaking process. With this process it is possible to increase the MFRfin and to narrow the molecular weight distribution so that the quality of the fibers is increased. The visbreakign process is preferably a chemical visbreaking.

[0016] The chemical visbreaking of the propylene based polymer composition of the present disclosure is carried out in the presence of free radical initiators, such as the peroxides.

[0017] The peroxides which are most conveniently used in the polymer visbreaking process have a decomposition temperature preferably ranging from 150°C to 250°C. Examples of said peroxides are di-tert-butyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, all of which are commercially available.

[0018] The quantity of peroxide necessary for the visbreaking process preferably ranges from 0.001 to 0.5% by weight of the polymer, more preferably from 0.01 to 0.2 wt%.

[0019] The fibers according to the present invention can be stable fibers or spunbond fibers.

[0020] The fibers of the present invention can also contain additives commonly employed in the art, such as antioxidants, light stabilizers, heat stabilizers, nucleating agents, colorants and fillers.

[0021] The fibers of the invention typically exhibit a value of tenacity at least equal to or higher than 20.0 cN/tex, preferably higher than 23.0. cN/tex, more preferably higher than 24.0 cN/tex.

[0022] Typically, the fibers according to the present disclosure have a titre ranging from 1 to 8 dtex, preferably from 1.5 to 4.0 dtex.

[0023] The fibers of the present disclosure can be efficiently spun at speeds that are typically higher than 3000 m/min, preferably higher than 3300 m/min, more preferably higher than 3500 m/min.

[0024] The fibers of the present disclosure can be spun at temperatures generally varying from 200° to 300° C. Preferably, the spinning temperature is lower than 250°C, even more preferably, the spinning temperature is comprised between 230° and 250°C.

[0025] The fibers of the present disclosure preferably have an elongation at breack higher than 200 %; preferably higher than 220 %.

[0026] The fibers of the present invention can be used for the manufacture of non-woven fabrics showing excellent properties.

[0027] Such non-woven fabrics may be produced with various methods, preferably through the well-known spunbonding technique. The spunbonding process is a non-woven manufacturing technique, whereby polymers are directly converted into endless filaments and stochastically deposited to form a non-woven material.

[0028] The following examples are given in order to illustrate, but not limit the present disclosure.

EXAMPLE

Characterization methods

Xylene-soluble (XS) Fraction at 25 °C

[0029] Xylene Solubles at 25°C have been determined according to ISO 16 152; with solution volume of 250 ml, precipitation at 25°C for 20 minutes, 10 of which with the solution in agitation (magnetic stirrer), and drying at 70°C.

DSC method for melting temperature and crystallization temperature

[0030] Melting point has been measured according to ISO 11357-3, at scanning rate of 20C/min both in cooling and heating, on a sample of weight between 5 and 7 mg., under inert N2 flow. Instrument calibration made with indium

Melt Flow Rate (MFR)

[0031] Measured according to ISO 1133 at 230 °C with a load of 2.16 kg, unless otherwise specified.

Comonomer content (NMR)

[0032] For determining the content of comonomers via 13C-NMR analysis, it was worked according to the following procedure. 13C NMR spectra were acquired on a Bruker AV600 spectrometer equipped with cryo probe, operating 150.91 MHz in the Fourier transform mode at 120°C. The peak of the Sδδ carbon (nomenclature according C.J. Carman, R.A. Harrington and C.E. Wilkes, Macromolecules, 10, 3, 536 (1977)) was used as internal reference at 29.9 ppm. About 30 mg of sample were dissolved in 0.5 ml of 1,1,2,2 tetrachloro ethane d2 at 120 °C w. 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 65 K data points using a spectral window of 9000 Hz. Triad distribution was obtained using the following relations:















wherein:

• Σ = I₈+ I₅ + I₄+I₃ + I₂+I₉ + I₁+ 0.5 I₇ + 0.25 I₆;
• I are the areas of the corresponding carbon as reported in Table;
• and X can be propylene or 1-butene.

[0033] The molar content of ethylene (E), propylene (P) and 1-butene (B) is obtained from triads using the following relations:

[0034] Molar content was transformed in weight content using monomers molecular weight.

Assignments of the ¹³C NMR spectrum of Ethylene/Propylene/1-Butene terpolymers

[0035] 

Number	Chemical Shift (ppm)	Carbon	Sequence
1	37.64 - 37.35	Sαδ	PEE
2	37.35 - 37.15	Tβδ	XBE
3	35.27 - 34.92	Tββ	XBX
4	33.29 - 33.15	Tδδ	EPE
5	30.93 - 30.77	Tβδ	XPE
6	30.35 - 30.26	Sγδ	PEEE
7	29.97 - 29.85	Sδδ	EEE
8	29.14 - 28.31	Tββ	XPX
9	24.88 - 24.14	Sββ	XEX

Tensile modulus, and elongation at break

[0036] Tensile modulus, and elongation at break has been measured according to ISO 527-2, and according to ISO 1873-2.

Charpy impact at 23°C

[0037] Charpy impact has been measured according to ISO 179-1eA, and ISO 1873-2.

Titre of filaments

[0038] From a 10 cm long roving, 50 fibers are randomly chosen and weighed. The total weight of the 50 fibers, expressed in mg, is multiplied by 2, thereby obtaining the titre in dtex.

Molecular weights and molecular weight distribution

[0039] Molecular weights and molecular weight distribution were measured at 150°C using a Waters Alliance GPCV/2000 instrument equipped with four mixed-bed columns PLgel Olexis having a particle size of 13 µιη. The dimensions of the columns were 300 x 7.8 mm. The mobile phase used was vacuum distilled 1,2,4-trichlorobenzene (TCB) and the flow rate was kept at 1.0 ml/min. The sample solution was prepared by heating the sample under stirring at 150°C in TCB for one to two hours. The concentration was 1 mg/ml. To prevent degradation, 0.1 g/1 of 2,6-di-ie/ -butyl-/?-cresol were added. 300 µḯ (nominal value) of solution were injected into the column set. A calibration curve was obtained using 10 polystyrene standard samples (EasiCal kit by Agilent) with molecular weights in the range from 580 to 7 500 000. It was assumed that the K values of the Mark-Houwink relationship were:

K = 1.21 × 10"⁴ dl/g and a = 0.706 for the polystyrene standards,

K = 1.90 × 10"⁴ dl/g and a = 0.725 for the experimental samples.

[0040] A third order polynomial fit was used for interpolate the experimental data and obtain the calibration curve. Data acquisition and processing was done by using Waters Empowers 3 Chromatography Data Software with GPC option.

Tenacity and Elongation at break of filaments

[0041] From a 500 m roving a 100 mm-long segment is cut and single fibers randomly chosen. Each single fiber is fixed to the clamps of a Dynamometer and tensioned to break with a traction speed of 20 mm/min for elongations lower than 100% and 50 mm/min for elongations greater than 100%, the initial distance between the clamps being of 20 mm. The ultimate strength (load at break) and the elongation at break are determined in machine (MD) direction.

[0042] The tenacity is calculated by way of the following equation:

Maximum spinning speed

[0043] The maximum spinning speed gives indication of the spinnability of the propylene polymer composition of the invention. The value corresponds to the highest spinning rate that can be maintained for 30 minutes with no filament break
dle weight is 0.1 mg

Component A

[0044] Component A is a propylene homopolymer having an MFR (230°C and 2.16 kg) of 2.5 g/10 min and a fraction soluble in xylene at 25°C of 3.0 wt%

Component B

[0045] Component B is a PIR recycled resin having the features reported in table 1

Table 1

		Ex1
Ethylene	Mol%	1.0.
1-butene	Mol%	0.8
XEX	Mol%	0.44
EEE	Mol%	0.29
XBX	Mol%	0.84
BBE	Mol%	0.00
MFR, 230 °C 2.16 kg,	g/10 min	8.3
Xs	Wt%	7.0

Preparation of the fibers comparative example 1 and example 2

Example 1

[0046] 70 wt% of component A and 30 wt% of component B) have been blended together to obtain an MFR of 3.8 g/10 min and visbreaked to MFR of 25.8 g/10 min thus achieving a visbreaking degree of 6.8 and a Mw/Mn of 6.3 pellettized. Pellets are extruded in a Leonard 25 spinning pilot line with screw LID ratio of 5. The line is marketed by Costruzioni Meccaniche Leonard-Sumirago (VA). The operative spinning conditions are here reported.

Operative conditions:

[0047] 

• Hole diameter: mm 0.4
• Hole number in the die: 41
• Die temperature (°C): 280

Comparative example 2

[0048] Comparative example 1 is a fiber prepared as above described by using HP561R a commercial grade sold by LyondellBasell having an MFR of 25.4 g/10 min.

[0049] The properties of the filaments are reported on Table 2.

Table 2

		Ex 1	Comp ex 2
Visbreaked composition
Xylene Solubles	wt%	4.3	3.2
Tm	°C	159.2	160.3
Tc	°C	109.6	113.3
Hc	J/g	-101.4	-93.8
Hm	J/g	95.2	91.3
Mw, GPC	g/mol	1.7E+05	1.7E+05
Mw/Mn, GPC	-	6.3	4.9
MFR 'L' pellets	dg/min	25.5	25.4
Fiber
Titre	dTex	2.25	2.25
Tenacity	cN/Tex	26.5	24.9
Elongation at break	%	300	250
Maximum speed	m/min	4500	4500

Claims

1. A fiber comprising propylene based polymer composition comprising:

A) from 90 wt% to 65 wt% of a propylene homopolymer having a Xylene Soluble fraction at 25°C,determined according to ISO 16152: 2005, ranging from 1.5 wt% to 6.0 wt% ;

B) from 10 wt% to 35 wt% a recycled polypropylene composition being a Post-Industrial Resin (PIR) or Post-Consumer Resin (PCR) ;

wherein the propylene based polymer composition has a Melt Flow Rate, determined according to the method ISO 1133 (230° C, 2.16 kg), ranging from 15.0 g/10 min to 50.0 g/10 min and a distribution of molecular weight Mw/Mn ranging from 4.5 to 7.5 and

the propylene based polymer composition being obtainable with a visbreaking process wherein the visbreaking degree MFRfin/MFRinit is comprised between 3.0 and 10.0 wherein MFRfin is the final Melt Flow Rate of the propylene based composition and MFR in it is the Melt Flow Rate of the propylene based composition before the visbreaking process.

2. The fiber according to claim 1 wherein component A) has a Xylene Soluble fraction at 25°C,determined according to ISO 16152: 2005, ranging from 2.0 wt% to 5.0 wt%.

3. The fiber according to any of claims 1-2 wherein component B) contains at least 50 wt%; of derived units of propylene; one or more of the remaining comonomers being selected from the group consisting of ethylene; 1-butene; 1-hexene or 1-octene derived units.

4. The fiber according to any of claims 1-3 wherein the visbreaking degree of the propylene based polymer composition MFRfin/MFRinit is comprised between from 4.0 and 9.0.

5. The fiber according to any of claims 1-4 wherein the Melt Flow Rate, determined according to the method ISO 1133 (230° C, 2.16 kg), of the propylene based polymer composition ranges from 18.0 g/10 min to 38.0 g/10 min.

6. The fiber to any of claims 1-6 wherein component B) is Post-Industrial Resin (PIR).

7. The fiber according to any of claims 1-6 wherein component B) does not contain limonene.

8. The fiber according to any of claims 1-7 wherein component B) has the following features:

i) ethylene derived units content, measured by ¹³C-NMR, ranging from 0.3 mol% to 1.8 mol%;

ii) 1-butene derived units content, measured by ¹³C-NMR, ranging from 0.4 mol% to 2.5 mol%;

iii) the C¹³ NMR sequences XEX wherein X can be a propylene derived unit or a 1-butene derived unit, ranging from 0.20 mol% to 0.55 mol%.

iv) the C¹³ NMR sequences EEE ranging from 0.05 mol% to 0.40 mol%.

v) the C¹³ NMR sequences XBX , X can be a propylene derived unit or a 1-butene derived unit ranging from 0.50 mol% to 2.20 mol%;

vi) the C¹³ NMR sequences BBE are not present;

vii) melt flow rate, MFR, measured according to ISO 1133 at 230 °C with a load of 2.16 kg, ranging from 3.6 g/10 min to 11.4 g/10 min;

viii) xylene soluble fraction at 25°C ranging from 4.8 wt% to 10.7 wt%.

9. The fiber according to any of claims 1-8 wherein component A) ranges from 68 wt% to 85 wt% and component B) ranges from 15 wt% to 32 wt%.

10. The fiber according to any of claims 1-9 wherein the propylene based polymer composition has the distribution of molecular weight Mw/Mn ranging from 5.0 to 7.2.

11. The fiber according to any of claims 1-10 wherein t component A) has the Xylene Soluble fraction at 25°C,determined according to ISO 16152: 2005, ranging from 2.2 wt% to 4.0 wt%.

12. The fiber according to any of claims 1-11 wherein in component B) the ethylene derived units content, measured by ¹³C-NMR, ranges from 0.6 mol% to 0.4 mol%.

13. The fiber according to any of claims 1-12 wherein in component B) 1-butene derived units content, measured by ¹³C-NMR, ranges from 0.7 mol% to 1.5 mol%.

14. The fiber according to any of claims 1-13 wherein in component B) the C¹³ NMR sequences XEX wherein X can be a propylene derived unit or a 1-butene derived unit, ranges from 0.32 mol% to 0.46 mol%.

15. The fiber according to any of claims 1-14 wherein in component B) the C¹³ NMR sequences EEE ranges from 0.15 mol% to 0.30 mol%;.