CROSS-LINKED PLASTOMERS AS A REPLACEMENT FOR RUBBER

Abstract

Articles comprising a polymer composition, wherein the polymer composition is obtainable by grafting an ethylene copolymer with comonomer units comprising hydrolysable silane groups, wherein the polymer composition shows high gel content and low compression set at −25° C. These articles have applications in automotive weather-stripping, such as sealing systems for doors, trunks and hoods.

Claims

1: An article comprising: a polymer composition, wherein the polymer composition is obtainable by grafting an ethylene copolymer with comonomer units comprising hydrolysable silane groups, and wherein, the polymer composition has an amount of more than 0.5 wt. % of the comonomer units comprising hydrolysable silane groups, based on the total weight amount of monomer units in the polymer composition, wherein the said ethylene copolymer comprises alpha-olefin comonomer units having from 6-12 carbon atoms, and wherein the said ethylene copolymer is characterized as having: a density of from 840 to 890 kg/m.sup.3, a total unsaturation of from 20 to 100 unsaturated bonds per 100,000 CH.sub.n groups.

2: The article according to claim 1, wherein the ethylene copolymer comprises from 10 wt. % to 50 wt. % of alpha olefin comonomer units having from 6 to 12 carbon atoms based on the total amount of monomer units in the ethylene copolymer (as determined using NMR).

3: The article according to claim 1, wherein the alpha olefin comonomer units are selected from 1-octene or 1-hexene.

4: The article according to claim 1, wherein the ratio of vinyl groups to total unsaturated groups in the ethylene copolymer is less than 0.6.

5: The article according to claim 1, wherein the ratio of cis to trans groups in the ethylene copolymer is greater than 1.

6: The article according to claim 1, wherein the ethylene copolymer has a crystallinity between 5 and 8% when measured by DSC using 50° C./min cooling and heating rates.

7: The article according to claim 1, wherein the polymer composition comprises further polymer components.

8: The article according to claim 1, wherein the polymer composition has been cross-linked after forming the article by hydrolysing the silane groups in the presence of a silanol condensation catalyst (SCC).

9: The article according to claim 8, wherein after crosslinking the article has a compression set (ISO 815-1:2010-9 at −25° C.) of from 0% to 5% when measured at −25° C.

10: The article according to claim 8, wherein after crosslinking the article has a compression set (ISO 815-1:2010-9 at 23° C.) of from 0 to 20%, when measured at 23° C.

11: The article according to claim 8, wherein the composition after crosslinking has a gel content of from 75% to 99%.

12: The article according to claim 8, wherein the ethylene copolymer has an MFR.sub.2 (ISO 1133; 190° C.; 2.16 kg) in the range of from 0.01 to 5.0 g/10 min.

13: A process for the production of an article comprising the steps of: a) providing an ethylene copolymer, wherein the ethylene copolymer comprises alpha-olefin comonomer units having from 6-12 carbon atoms, wherein the ethylene copolymer is characterized as having: a density of from 840 to 890 kg/m.sup.3, a total unsaturation of from 20 to 100 unsaturated bonds per 100,000 CH.sub.n groups, b) obtaining a polymer composition by grafting comonomer units comprising hydrolysable silane groups into the ethylene copolymer with a grafting agent to obtain a polymer composition with from 0.5 wt. % to 10 wt. % comonomer units comprising hydrolysable silane groups, c) blending the silane grafted polymer composition from step b) with a silanol condensation catalyst, d) forming the composition from step c) into an article.

14: The process according to claim 13, wherein after step d) the article is cross-linked in the presence of water, to obtain a gel content (measured according to ASTM D 2765-01, Method A) of 75% to 99%.

15. (canceled)

16: The article according to claim 8, wherein the silanol condensation catalyst (SCC) used in the cross-linking step is a sulphonic acid.

17: The article according to claim 16, wherein the silanol condensation catalyst is an aromatic organic sulphonic acid, which is an organic sulphonic acid and which comprises the structural element:
Ar(SO.sub.3H).sub.x  (IV) wherein, Ar is an aryl group which may be substituted or non-substituted, and if substituted, then substituted with at least one hydrocarbyl group comprising up to 50 carbon atoms, and wherein x is at least 1; or, wherein said structural element is a precursor of the sulphonic acid of formula (IV) including an acid anhydride thereof or a sulphonic acid of formula (IV) that has been provided with hydrolysable protective groups, an acetyl group that is removable by hydrolysis.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0216] FIG. 1: Correlation of VTMS wt. % in the polymer composition with compression set % over a range of temperatures, corresponding to example 1 (values shown in table 4).

[0217] FIG. 2: Comparison of the compression set properties of 2 different base resins at temperatures from −23° C. to 100° C. corresponding to example 2 (values shown in table 5).

EXAMPLE SECTION

[0218] The following Examples are included to demonstrate certain aspects and embodiments of the invention as described in the claims. It should be appreciated by those of skill in the art, however, that the following description is illustrative only and should not be taken in any way as a restriction of the invention.

[0219] Determination Methods

[0220] a) Melt flow rate: The melt flow rate MFR.sub.2 was measured in accordance with ISO 1133 at 190° C. and a load of 2.16 kg for ethylene homo and copolymers.

[0221] b) Density is measured according to ISO 1183-187. Sample preparation is done by compression moulding in accordance with ISO 1872-2:2007.

[0222] c) Quantitative nuclear-magnetic resonance (NMR) spectroscopy:

[0223] The content (wt. % and mol %) of polar comonomer present in the polymer:

[0224] Quantitative nuclear-magnetic resonance (NMR) spectroscopy was used to quantify the comonomer content of the polymer in the polymer composition.

[0225] Quantitative .sup.1H NMR spectra recorded in the solution-state using a Bruker Advance III 400 NMR spectrometer operating at 400.15 MHz. All spectra were recorded using a standard broad-band inverse 5 mm probehead at 100° C. using nitrogen gas for all pneumatics. Approximately 200 mg of material was dissolved in 1,2-tetrachloroethane-d.sub.2 (TCE-d.sub.2) using ditertiarybutylhydroxytoluen (BHT) (CAS 128-37-0) as stabiliser. Standard single-pulse excitation was employed utilising a 30 degree pulse, a relaxation delay of 3 s and no sample rotation. A total of 16 transients were acquired per spectra using 2 dummy scans. A total of 32 k data points were collected per FID with a dwell time of 60 μs, which corresponded to a spectral window of approx. 20 ppm. The FID was then zero filled to 64 k data points and an exponential window function applied with 0.3 Hz line-broadening. This setup was chosen primarily for the ability to resolve the quantitative signals resulting from vinyltrimethylsiloxane copolymerization when present in the same polymer.

[0226] Quantitative .sup.1H NMR spectra were processed, integrated and quantitative properties determined using custom spectral analysis automation programs. All chemical shifts were internally referenced to the residual protonated solvent signal at 5.95 ppm.

[0227] When present characteristic signals resulting from the incorporation of vinylacytate (VA), methyl acrylate (MA), butylacrylate (BA) and vinyltrimethylsiloxane (VTMS), in various comonomer sequences, were observed (see J Randall). All comonomer contents calculated with respect to all other monomers present in the polymer.

[0228] The ethylene comonomer content was quantified using the integral of the bulk aliphatic (bulk) signal between 0.00-3.00 ppm. This integral may include the 1VA (3) and αVA (2) sites from isolated vinylacetate incorporation, *MA and αMA sites from isolated methylacrylate incorporation, 1 BA (3), 2BA (2), 3BA (2), *BA (1) and αBA (2) sites from isolated butylacrylate incorporation, the *VTMS and αVTMS sites from isolated vinylsilane incorporation and the aliphatic sites from BHT as well as the sites from polyethylene sequences. The total ethylene comonomer content was calculated based on the bulk integral and compensating for the observed comonomer sequences and BHT:

E=(¼)*[I.sub.bulk−5*VA −3*MA −10*BA −3*VTMS −21*BHT]

[0229] It should be noted that half of the α signals in the bulk signal represent ethylene and not comonomer and that an insignificant error is introduced due to the inability to compensate for the two saturated chain ends (S) without associated branch sites.

[0230] d) Comonomer (C8) Content Quantification of Poly(Ethylene-Co-1-Octene) Copolymers

[0231] Quantitative .sup.13C{.sup.1H} NMR spectra recorded in the molten-state using a Bruker Advance III 500 NMR spectrometer operating at 500.13 and 125.76 MHz for .sup.1H and .sup.13C respectively. All spectra were recorded using a .sup.13C optimised 7 mm magic-angle spinning (MAS) probe-head at 150° C. using nitrogen gas for all pneumatics. Approximately 200 mg of material was packed into a 7 mm outer diameter zirconia MAS rotor and spun at 4 kHz. This setup was chosen primarily for the high sensitivity needed for rapid identification and accurate quantification.{klimke01, parkinson02, castignolles03, NMR04} Standard single-pulse excitation was employed utilising the transient NOE at short recycle delays of 3 s {pollard05, klimke01} and the RS-HEPT decoupling scheme.{Filif06, Griffin07} A total of 1024 (1 k) transients were acquired per spectrum. This setup was chosen due to its high sensitivity towards low comonomer contents.

[0232] Quantitative .sup.13C{.sup.1H} NMR spectra were processed, integrated and quantitative properties determined using custom spectral analysis automation programs. All chemical shifts are internally referenced to the bulk methylene signal (5+) at 30.00 ppm.{Randall08}Characteristic signals corresponding to the incorporation of 1-octene were observed {Randall08, Liu09, Qiu10, Busisco11, Zhou12} and all comonomer contents calculated with respect to all other monomers present in the polymer.

[0233] Characteristic signals resulting from isolated 1-octene incorporation i.e. EEOEE comonomer sequences, were observed. Isolated 1-octene incorporation was quantified using the integral of the signal at 38.32 ppm. This integral is assigned to the unresolved signals corresponding to both *B6 and *βB6B6 sites of isolated (EEOEE) and isolated double non-consecutive (EEOEOEE) 1-octene sequences respectively. To compensate for the influence of the two *βB6B6 sites the integral of the ββB6B6 site at 24.7 ppm is used:

O=I.sub.*B6+*βB6B6−2*I.sub.ββB6B6

[0234] Characteristic signals resulting from consecutive 1-octene incorporation, i.e. EEOOEE comonomer sequences, were also observed. Such consecutive 1-octene incorporation was quantified using the integral of the signal at 40.48 ppm assigned to the ααB6B6 sites accounting for the number of reporting sites per comonomer:

OO=2*I.sub.ααB6B6

[0235] Characteristic signals resulting from isolated non-consecutive 1-octene incorporation, i.e.

[0236] EEOEOEE comonomer sequences, were also observed. Such isolated non-consecutive 1-octene incorporation was quantified using the integral of the signal at 24.7 ppm assigned to the ββB6B6 sites accounting for the number of reporting sites per comonomer:

OEO=2*I.sub.ββB6B6

[0237] Characteristic signals resulting from isolated triple-consecutive 1-octene incorporation, i.e. EEOOOEE comonomer sequences, were also observed. Such isolated triple-consecutive 1-octene incorporation was quantified using the integral of the signal at 41.2 ppm assigned to the ααγB6B6B6 sites accounting for the number of reporting sites per comonomer:

OOO=3/2*I.sub.ααγB6B6B6

[0238] With no other signals indicative of other comonomer sequences observed the total 1-octene comonomer content was calculated based solely on the amount of isolated (EEOEE), isolated double-consecutive (EEOOEE), isolated non-consecutive (EEOEOEE) and isolated triple-consecutive (EEOOOEE) 1-octene comonomer sequences:

O.sub.total=O+OO+OEO+OOO

[0239] Characteristic signals resulting from saturated end-groups were observed. Such saturated end-groups were quantified using the average integral of the two resolved signals at 22.84 and 32.23 ppm. The 22.84 ppm integral is assigned to the unresolved signals corresponding to both 2B6 and 2S sites of 1-octene and the saturated chain end respectively. The 32.23 ppm integral is assigned to the unresolved signals corresponding to both 3B6 and 3S sites of 1-octene and the saturated chain end respectively. To compensate for the influence of the 2B6 and 3B6 1-octene sites the total 1-octene content is used:

S=(½)*(I.sub.2S+2B6+I.sub.3S+3B6−2*O.sub.total)

[0240] The ethylene comonomer content was quantified using the integral of the bulk methylene (bulk) signals at 30.00 ppm. This integral included the γ and 4B6 sites from 1-octene as well as the δ.sup.+ sites. The total ethylene comonomer content was calculated based on the bulk integral and compensating for the observed 1-octene sequences and end-groups:

E.sub.total(½)*[I.sub.bulk+2*O+1*OO+3*OEO+0*OOO+3*S]

[0241] It should be noted that compensation of the bulk integral for the presence of isolated triple-incorporation (EEOOOEE) 1-octene sequences is not required as the number of under and over accounted ethylene units is equal.

[0242] The total mole fraction of 1-octene in the polymer was then calculated as:

fO=(O.sub.total/(E.sub.total+O.sub.total)

[0243] The total comonomer incorporation of 1-octene in weight percent was calculated from the mole fraction in the standard manner:

O[wt %]=100*(fO*112.21)/((fO*112.21)+((1−fO)*28.05)) [0244] Klimke01 [0245] Klimke, K., Parkinson, M., Piel, C., Kaminsky, W., Spiess, H. W., Wilhelm, M., Macromol. Chem. Phys. 2006; 207:382. [0246] Parkinson02 [0247] Parkinson, M., Klimke, K., Spiess, H. W., Wilhelm, M., Macromol. Chem. Phys. 2007; 208:2128. Castignolles03 [0248] Castignolles, P., Graf, R., Parkinson, M., Wilhelm, M., Gaborieau, M., Polymer 50 (2009) 2373 [0249] NMR04 [0250] NMR Spectroscopy of Polymers: Innovative Strategies for Complex Macromolecules, Chapter 24, 401 (2011) [0251] Pollard05 [0252] Pollard, M., Klimke, K., Graf, R., Spiess, H. W., Wilhelm, M., Sperber, O., Piel, C., Kaminsky, W., Macromolecules 2004; 37:813. [0253] Filip06 [0254] Filip, X., Tripon, C., Filip, C., J. Mag. Resn. 2005, 176, 239 [0255] Grifin07 [0256] Griffin, J. M., Tripon, C., Samoson, A., Filip, C., and Brown, S. P., Mag. Res. in Chem. 2007 45, S1, S198 [0257] Randall08 [0258] J. Randall, Macromol. Sci., Rev. Macromol. Chem. Phys. 1989, C29, 201. [0259] Liu09 [0260] Liu, W., Rinaldi, P., McIntosh, L., Quirk, P., Macromolecules 2001, 34, 4757 [0261] Qiu10 [0262] Qiu, X., Redwine, D., Gobbi, G., Nuamthanom, A., Rinaldi, P., Macromolecules 2007, 40, 6879 [0263] Busico11 [0264] Busico, V., Carbonniere, P., Cipullo, R., Pellecchia, R., Severn, J., Talarico, G., Macromol. Rapid Commun. 2007, 28, 1128 [0265] Zhou12 [0266] Zhou, Z., Kuemmerle, R., Qiu, X., Redwine, D., Cong, R., Taha, A., Baugh, D. Winniford, B., J. Mag. Reson. 187 (2007) 225

[0267] e) Quantitative Nuclear-Magnetic Resonance (NMR) Spectroscopy was Used to Quantify the VTMS Content and Derived Properties of the Polymers.

[0268] Quantitative nuclear-magnetic resonance (NMR) spectroscopy was used to quantify the VTMS content of the polymers.

[0269] Quantitative .sup.1H NMR spectra recorded in the molten-state using a Bruker Avance III 500 NMR spectrometer operating at 500.13 MHz. All spectra were recorded using a .sup.13C optimised 7 mm magic-angle spinning (MAS) probehead at 150° C. using nitrogen gas for all pneumatics. Approximately 200 mg of material was packed into a 7 mm outer diameter zirconia MAS rotor and spun at 4 kHz. This setup was chosen primarily for the high sensitivity needed for rapid identification and accurate quantification {klimke06, parkinson07, castignolles09}. Standard single-pulse excitation was employed applying short recycle delay of 2 s. A total of 128 transients were acquired per spectrum.

[0270] Quantitative .sup.1H NMR spectra were processed, integrated and quantitative properties determined using custom spectral analysis automation programs. All chemical shifts are internally referenced to the polyethylene methylene signal at 1.33 ppm.

[0271] Characteristic signals resulting from grafting of vinyltrimethylsiloxane, in various comonomer sequences, were observed. The vinyltrimethylsiloxane grafting was quantified using the integral of the signal at 3.52 ppm assigned to the 1VTMS sites {brandolini01}, accounting for the number of reporting nuclei per comonomer:

gVTMS=I.sub.1VTMS/9

##STR00001##

[0272] The ethylene content (E) was quantified using the integral of the bulk aliphatic (bulk) signal between 0.00-3.00 ppm. This integral must be compensated by subtracting 4 times gVTMS (2 methylene groups, 2VTMS and 3VTMS) and add once gVTMS (*VTMS missing 1 proton) in total subtracting 3 times gVTMS.

E=(bulk−3*gVTMS)/4

It should be noted that an insignificant error is introduced due to the inability to compensate for the saturated chain ends without associated branch sites.

[0273] The total mole fractions of vinyltrimethylsiloxane in the polymer was calculated as:

fVTMS=gVTMS/(E+gVTMS )

The total comonomer incorporations of vinyltrimethylsiloxane in weight percent was calculated from the mole fractions in the standard manner:

cVTMS [wt %]=[100*(fVTMS*148.23)]/[(fVTMS*148.23)+((1−fVTMS)*28.05)]

[0274] The quantification of grafted vinyltrimethylsiloxane in weight percent cVTMS [wt %] by .sup.1H NMR as described is independent from additional alpha-co-olefins with even numbers of carbons e.g. C4, C6 or C8 which might be incorporated in the polyethylene chain. [0275] brandolini01 [0276] A. J. Brandolini, D. D. Hills, “NMR spectra of polymers and polymer additives”, Marcel Deker Inc., 2000 [0277] klimke06 [0278] Klimke, K., Parkinson, M., Piel, C., Kaminsky, W., Spiess, H. W., Wilhelm, M., Macromol. Chem. Phys. 2006; 207:382. [0279] parkinson07 [0280] Parkinson, M., Klimke, K., Spiess, H. W., Wilhelm, M., Macromol. Chem. Phys. 2007; 208:2128. [0281] castignolles09 [0282] Castignolles, P., Graf, R., Parkinson, M., Wilhelm, M., Gaborieau, M., Polymer 50 (2009) 2373

[0283] It is evident for a skilled person that the above principle can be adapted similarly to quantify content of any further polar comonomer(s) which is other than MA BA and VA, if within the definition of the polar comonomer as given in the present application, and to quantify content of any further silane group(s) containing units which is other than VTMS, if within the definition of silane group(s) containing units as given in the present application, by using the integral of the respective characteristic signal.

[0284] f) Quantitative Nuclear-Magnetic Resonance (NMR) Spectroscopy to Quantify the Content of Unsaturated Groups Present in the Polymer Compositions.

[0285] Quantitative .sup.1H NMR spectra were recorded in the solution-state using a Bruker Advance III 400 NMR spectrometer operating at 400.15 MHz. All spectra were recorded using a .sup.13C optimized 10 mm selective excitation probehead at 125° C. using nitrogen gas for all pneumatics. Approximately 250 mg of material was dissolved in 7,2-tetrachloroethane.sub.−c/2 (TCE.sub.−c/2) using approximately 3 mg of Hostanox 03 (CAS 32509-66-3) as stabilizer. Standard single-pulse excitation was employed utilizing a 30 degree pulse, a relaxation delay of 10 s and 10 Hz sample rotation. A total of 128 transients were acquired per spectra using 4 dummy scans. This setup was chosen primarily for the high resolution needed for unsaturation quantification and stability of the vinylidene groups. {he10a, busico05a} All chemical shifts were indirectly referenced to TMS at 0.00 ppm using the signal resulting from the residual protonated solvent at 5.95 ppm.

[0286] Characteristic signals corresponding to the presence of terminal aliphatic vinyl groups (R—CH═CH.sub.2) were observed and the amount quantified using the integral of the two coupled inequivalent terminal CH.sub.2 protons (Va and Vb) at 4.95, 4.98 and 5.00 and 5.05 ppm accounting for the number of reporting sites per functional group:

Nvinyl=IVab/2

[0287] Characteristic signals corresponding to the presence of internal vinylidene groups (RR(C═CH.sub.2)) were observed and the amount quantified using the integral of the two CH.sub.2 protons (D) at 4.74 ppm accounting for the number of reporting sites per functional group:

Nvinylidene=ID/2

[0288] When characteristic signals corresponding to the presence of internal cis-vinylene groups (E-RCH═CHR), or related structure, were observed, then the amount quantified using the integral of the two CH protons (C) at 5.39 ppm accounting for the number of reporting sites per functional group:

N.sub.cis=IC/2

[0289] When characteristic signals corresponding to the presence of internal cis-vinylene groups (E-RCH═CHR), or related structure, were not visually observed, then these groups were not counted and the parameter N.sub.cis was not used.

[0290] Characteristic signals corresponding to the presence of internal trans-vinylene groups (Z—RCH═CHR) were observed and the amount quantified using the integral of the two CH protons (T) at 5.45 ppm accounting for the number of reporting sites per functional group:

N.sub.trans=IT/2

[0291] Characteristic signals corresponding to the presence of internal trisubstituted-vinylene groups (RCH═CRR), or related structure, were observed and the amount quantified using the integral of the CH proton (Tris) at 5.14 ppm accounting for the number of reporting sites per functional group:

Ntris=ITris

[0292] The Hostanox 03 stabliser was quantified using the integral of multiplet from the aromatic protons (A) at 6.92, 6.91, 6.69 and at 6.89 ppm and accounting for the number of reporting sites per molecule:

H=IA/4

[0293] As is typical for unsaturation quantification in polyolefins the amount of unsaturation was determined with respect to total carbon atoms, even though quantified by .sup.1H NMR spectroscopy. This allows direct comparison to other microstructure quantities derived directly from .sup.13C NMR spectroscopy.

[0294] The total amount of carbon atoms was calculated from integral of the bulk aliphatic signal between 2.85 and −10.00 ppm with compensation for the methyl signals from the stabiliser and carbon atoms relating to unsaturated functionality not included by this region:

NCtotal=(Ibulk−42′H)/2+2*Nvinyl+2*Nvinylidene+2*Ncis+2*Ntrans+2*Ntris

[0295] The content of unsaturated groups (U) was calculated as the number of unsaturated groups in the polymer per thousand total carbons (kCHn):

U=1000*N/NCtotal

[0296] The total amount of unsaturated group was calculated as the sum of the individual observed unsaturated groups and thus, also reported with respect per thousand total carbons:

U.sub.total=U.sub.vinyl+U.sub.vinylidene+U.sub.cis+U.sub.trans+U.sub.tris

[0297] The relative content of a specific unsaturated group (U) is reported as the fraction of a given unsaturated group with respect to the total amount of unsaturated groups:

[00002]$\left[U\right]=\frac{U_x}{U_{total}}$

BIBLIOGRAPHIC REFERENCES

[0298] J. Randall: [0299] J. Randall et. al. Macromol. Sci., Rev. Macromol. Chem. Phys. 1989, C29, 201. [0300] he10a: [0301] He, Y., Qiu, X, and Zhou, Z., Mag. Res. Chem. 2010, 48, 537-542. [0302] busico05a: [0303] Busico, V. et. al. Macromolecules, 2005, 38 (16), 6988-6996 B) Examples

[0304] g) Melting temperature and degree of crystallinity: Melting temperature Tm, crystallization temperature Tcr, and the degree of crystallinity were measured with Mettler TA820 differential scanning calorimetry (DSC) on 5 to 10 mg, typically 8±0.5 mg samples. Both crystallization and melting curves were obtained during 50K/min cooling and heating scans between −70 C and 170° C. Melting and crystallization temperatures were taken as the peaks of endotherms and exotherms. The degree of crystallinity was calculated by comparison with heat of fusion of a perfectly crystalline polyethylene, i.e. 290 J/g.

[0305] h) Degree of crosslinking (Gel Content): Degree of crosslinking was measured by decaline extraction (Measured according to ASTM D 2765-01, Method A) on the crosslinked material.

[0306] i) Compression set: Compression set is a typical way to measure elasticity of the material. Compression set was measured according to ISO 815-1:2010-9. A plaque of the studied material is compressed at 25% for 24 hours at a given temperature. After that, the compression is removed and the material is let to relax 30 min at RT. The difference in height (set) is measured and reported in %.

[0307] j) Glass transition temperature: Tg is determined by dynamic mechanical analysis according to ISO 6721-7. The measurements are done in torsion mode on compression-moulded samples (40×10×1 mm3) between −100° C. and +150° C. with a heating rate of 2° C./min and a frequency of 1 Hz.

[0308] k) Number average molecular weight (M.sub.n), weight average molecular weight (M.sub.w) and molecular weight distribution (MWD) are determined by Gel Permeation Chromatography (GPC) according to the following method:

[0309] The weight average molecular weight Mw and the molecular weight distribution (MWD=Mw/Mn wherein Mn is the number average molecular weight and Mw is the weight average molecular weight) is measured by a method based on ISO 16014-1:2003 and ISO 16014-4:2003. A Waters Alliance GPCV 2000 instrument, equipped with refractive index detector and online viscosimeter was used with 3×TSK-gel columns (GMHXL-HT) from TosoHaas and 1,2,4-trichlorobenzene (TCB, stabilized with 200 mg/L 2,6-Di tert butyl-4-methyl-phenol) as solvent at 145° C. and at a constant flow rate of 1 mL/min. 216.5 μL of sample solution were injected per analysis. The column set was calibrated using relative calibration with 19 narrow MWD polystyrene (PS) standards in the range of 0.5 kg/mol to 11 500 kg/mol and a set of well characterised broad polypropylene standards. All samples were prepared by dissolving 5-10 mg of polymer in 10 mL (at 160° C.) of stabilized TCB (same as mobile phase) and keeping for 3 hours with continuous shaking prior sampling in into the GPC instrument.

[0310] l) Degree of crystallinity: the degree of crystallinity was measured with Mettler TA820 differential scanning calorimetry (DSC) on 5 to 10 mg, typically 8±0.5 mg samples. Crystallization curves were obtained during 50° C./min cooling and heating scans between −70° C. and 170° C.

Examples

[0311] The following Examples are included to demonstrate certain aspects and embodiments of the invention as described in the claims. It should be appreciated by those of skill in the art, however, that the following description is illustrative only and should not be taken in any way as a restriction of the invention.

TABLE-US-00001 TABLE 1 Materials used in the polymer compositions Materials Manufacturer/Supplier Queo 2M137.sup.1 Borealis AG Queo 6200.sup.2 Borealis AG Engage 8842 DOW VTMS Evonik resource efficiency GmbH CatMB SA Borealis AG

[0312] All commercially available materials refer to these materials available from the manufacturer in July 2018. .sup.1Commercially available as Queo 7001LA as of July 2018; .sup.2Not commercially available.

TABLE-US-00002 TABLE 2 Properties of the raw ethylene copolymers MFR.sub.2 Base g/10 Density NMR- Crystallinity/ Material polymer Comonomer min Kg/m.sup.3 C.sub.8/wt. % Tg/° C. % Queo Ethylene 1-octene 1 870 Ca. 32 −49.8 Ca. 16.9 2M137 Queo Ethylene 1-octene 0.5 862 36 −57 Ca. 7.0 6200 Engage Ethylene 1-octene 1 857 39.2 −58 Ca. 9.4 8842

TABLE-US-00003 TABLE 3 Unsaturation levels of the raw ethylene polymers NMR [C = C/100 kCHn] R-CH = Vinyl RR(C = R-CH = CHRR E-RHC = Z-RHC = groups/Total CH2) CH2 Trisubstituted CHR CHR cis: unsaturated Material vinylidene vinyl vinylene (tris) cis trans Total trans groups Queo 6200 13.1 8.2 18.8 6.5 2.2 48.9 2.95 0.17 Engage 8842 0.9 5.4 0 0 1.7 7.9 0 0.68

Example 1 (Ex1)

[0313] Plastomers were prepared by mixing and grafting the polymer (Queo 2M137) with various amounts of vinyl trimethylsiloxane (VTMS) and peroxide and reacting them in a co-rotation twin screw extruder at 200° C. temperature with a residence time of 60 seconds, to obtain a grafted resin (see table 4).

[0314] As the weight percent of VTMS is increased, the gel content of the polymer composition also increases.

[0315] Compression set test specimens were made from tapes by compression moulding the tapes into a plaque. Tape samples were produced on a Collin extruder (Teach-Line E20T) with a temperature profile of 120-130-140° C., a thickness of 2 mm and a width of 40 mm. The materials were dry blended (mixed) with 4% CatMB SA and then extruded into tapes.

[0316] Plaque pressing was carried out using the non-cross-linked tapes to get a thickness of 6 mm for the compression set measurements. After pressing the plaques, they were placed in hot water at 50° C. for 24 h to get them fully cross-linked. The gel content of the cross-linked plaque was subsequently measured before compression set measurement using the method described above.

[0317] The compression set-% results for the plastomers in example 1 are shown in FIG. 1.

TABLE-US-00004 TABLE 4 Gel content of samples containing Queo 2M137 after grafting and cross-linking with different quantities of VTMS. Vinyl trimethylsiloxane/ Density/ Gel content/ Example % w/w Kg/m.sup.3 % w/w 1.1 0.5 874.4 71 1.2 1.8 877.3 94 1.3 2.9 880.1 93

Example 2 (Ex2)

[0318] Two different base resins, Queo 6200 and Engage 8842 were grafted with approximately the same amount of silane. Engage contains 3.5 wt. % more 1-octene derived units compared to Queo 6200. Compression set testing was carried out in an analogous manner to that described for example 1 (see above).

[0319] As may be seen, Queo has lower comonomer content compared to Engage. However, the very low, almost negligible crystallinity of Queo makes it very elastic also at low temperatures where all chains which are able to crystallise, will crystallise. At 100° C. there is no difference in the elasticity of Queo and Engage, because all crystals are molten.

TABLE-US-00005 TABLE 5 Compression set properties of the examples according to the present invention. Silfin 24 Gel Base wt. % in Density NMR-VTMS NMR-C.sub.8 Compression set content Example resin feed kg/m.sup.3 wt. % VTMS/kCbb wt. % −25° C. 23° C. 100° C. wt. % Example 2.1 Queo 2.91 864.2 1.76 2.38 38.5 2.3 10.7 7.7 95.7 6200 Comparative Engage example 2.2 8842 2.9 864.7 2.17 3.07 41.9 5.3 13.1 7.3 96.7