Monofilament or multifilament HPPE yarns

Abstract

Treated HPPE yarns include elemental metal which forms a layer that adheres to the surface of the HPPE yarn and covers at least partly the surface of the HPPE yarn. The elemental metal is deposited onto the outer surface of a HPPE yarn via sputtering, preferably plasma sputtering. Articles comprising the treated HPPE yarn, a device comprising the treated HPPE yarn or the article as well as processes for preparing the treated HPPE yarn or treated HPPE yarn structure or treated HPPE yarn configuration and use of the treated HPPE yarn or an article or a device comprising the treated HPPE yarn for automotive applications, marine applications, aerospace applications, medical applications, defense applications, sports/recreational applications, architectural applications, clothing applications, bottling applications, machinery applications are also disclosed.

Claims

1. A treated high performance polyethylene (HPPE) yarn comprising an elemental metal deposited onto an outer surface of the yarn via plasma sputtering, wherein the elemental metal forms a continuous layer that partly covers the surface of the yarn so as to present bare parts and localized layer surface defects, and wherein the continuous layer of elemental metal has a thickness of at least 5 nm and at most 550 nm that adheres to an outer surface of the HPPE yarn and covers at least 75% of the outer surface of the HPPE yarn, and wherein the elemental metal is present in an amount of at least 1.6% w/w and at most 95% w/w of the total weight of the treated HPPE yarn, and wherein the treated HPPE yarn has a tenacity of 15 cN/dtex or more which is comparable to within +/15% of the tenacity of an untreated HPPE yarn.

2. The treated HPPE yarn according to claim 1, wherein the elemental metal is selected from the group consisting of elemental metals with atomic number Z equal to 13 (Al), 22 (Ti), 24 (Cr), 25 (Mn), 26 (Fe), 28 (Ni), 29 (Cu), 30 (Zn), 40 (Zr), 46 (Pd), 47 (Ag), 78 (Pt), 79 (Au) and mixtures thereof.

3. The treated HPPE yarn according to claim 1, wherein the elemental metal is silver (Ag).

4. An article comprising the treated HPPE yarn as defined in claim 1.

5. A device comprising the article as defined in claim 4.

6. A device comprising the treated HPPE yarn as defined in claim 1.

7. The device according to claim 6, wherein the device is a device for an application selected from the group consisting of automotive applications, marine applications, aerospace applications, medical applications, defense applications, sports/recreational applications, architectural applications, clothing applications, bottling applications and machinery applications.

8. The device according to claim 6, wherein the treated HPPE yarn is present in an amount such that the treated HPPE yarn exhibits at least one property selected from the group consisting of electrical conductivity, antimicrobial properties, radio opacity, anti-thrombogenic properties and anti-fouling properties.

9. A process for making a treated high performance polyethylene (HPPE) yarn having a tenacity of 15 cN/dtex of more which is comparable to within +/15% of the tenacity of an untreated HPPE yarn, the method comprising the steps of: depositing a layer of elemental metal to a surface of a HPPE yarn via plasma sputtering using the HPPE yarn as a substrate and an elemental metal or metal alloy as target material to thereby obtain a treated HPPE yarn such that the deposited layer of elemental metal partly covers the surface of the yarn so as to present bare parts and localized layer surface defects; and optionally converting the treated HPPE yarn into a yarn structure selected from the group consisting of a braid structure, a textile structure, a woven structure, a non-woven structure and a knitted structure.

10. A method for indicating retirement or failure detection of a treated high performance polyethylene (HPPE) yarn, the method comprising: (i) providing the treated HPPE yarn as defined in claim 1; (ii) measuring electrical conductivity or electrical resistivity between at least two longitudinally distant points on the treated HPPE yarn; (iii) comparing electrical conductivity or electrical resistivity measurements acquired at different times; (iv) detecting a failure of the treated HPPE yarn if a change in electrical conductivity is equal or lower than the electrical conductivity recommended for the treated HPPE yarn.

Description

(1) The present invention will now be described in detail with reference to the following non limiting examples which are by way of illustration only.

(2) FIG. 1 presents a schematic representation of sputtering [in the scheme argon (Ar) gas (sputtering gas) is used to generate the primary particles].

(3) FIG. 2 presents a Scanning Electron Microscopy (SEM) image of the untreated HPPE yarn of Example 1.

(4) FIG. 3 presents a Scanning Electron Microscopy (SEM) image of the titanium sputtered HPPE yarn of Example 5.

(5) FIG. 4 presents a Scanning Electron Microscopy (SEM) image of a HPPE yarn having only silver nanoparticles.

(6) FIG. 5 presents a top-down X-ray contrast image of a sample material consisting of a polyurethane matrix (simulating a body) within which two pieces of HPPE braids, a silver sputtered and a non-silver sputtered, both simulating an implant were incorporated.

EXAMPLES

(7) The following non limiting examples which are by way of illustration only, they refer to yarns and to a surgical repair articles for example a suture which in the Examples is referred as braid. For example Examples 2 and 4 refer to a surgical repair article, which in Examples 2 and 4 is a suture.

(8) Methods & Techniques for Assessing Properties Related to the HPPE Yarns and Braids

(9) The diameters of the HPPE yarns were calculated according to equation 1.

(10) Assessment of the Electrical Conductivity of the HPPE Braids

(11) The electrical resistance (Ohm) of an object is a measure of its opposition to the passage of a steady electric current. A digital electrical multimeter Voltcraft VC150 was used to measure the electrical DC resistance of an HPPE yarn construction. The construction was a braid of 161110 dtex. The electrical contacts were placed in the two ends of the braid over a distance of 1 m in between them. Resistance's reciprocal quantity is electrical conductance measured in siemens (S). Electrical conductance is a measure of how easily electricity flows through an object.

(12) Assessment of the Surface Tension of the HPPE Braids

(13) The assessment of the surface tension of HPPE yarn constructions, braids of 81110 dtex, was carried out according to a modified method based on ISO 8296 which measures the average wettability of PE (polyethylene) or PP (polypropylene) or PVC (polyvinylchloride) films. The modification used in the present invention is that instead of: a) using a PE film, b) depositing the test liquid (liquid of known surface tension) via a brush stroke and c) assessing the wetting of the surface after 2 seconds, the method has been modified by: a) using a surface of HPPE braid (see surface preparation below), b) dropping a droplet of the test liquid onto the HPPE braid surface and c) assessing the wetting of the surface after 3 seconds.

(14) More particularly, the HPPE braid to be tested was wound axially and on the width dimension around a glass plate measuring 8 cm4 cm0.3 cm (lengthwidthheight) in a manner such as each winding of the braid was in constant contact with the previous winding of the braid and that it resulted in complete coverage of the glass surface by a single layer of the wound HPPE braid. Once the single layer of the wound HPPE braid was secured into place, a droplet of 5 L of a liquid of known surface tension was placed on the surface with the help of a pipette. If the droplet spread out within 3 seconds, then the surface of the braid had a surface tension equal to that of the liquid of known surface tension. The experiment was initiated using the liquid with the lower surface tension and proceeded sequentially with liquids of increasing surface tension.

(15) The set of liquids of known surface tension was Series C (mixtures of ethanol and water) covering a surface tension range from 28 mN/m up to and including 72 mN/m, in steps of 2 mN/m. This set of liquids was supplied by TIGRES Dr. Gerstenberg GmbH (www.tigres.de).

(16) Assessment of Mechanical Properties of the HPPE Yarns

(17) The elongation at break (%), E-modulus (GPa), force-at-maximum break (F.sub.max)(N) of the tested of the Reference HPPE yarn and of Ag-HPPE yarn as well as of Ti-HPPE yarn were measured as follows: a specimen of yarn was extended until breakage using a tensile testing machine, and the breaking force and the elongation at break are recorded. The sample preparation and conditioning were done as follows: before testing, the bobbins are conditioned for at least two hours at 21 C.1 C. and relative humidity between 40 and 75%. The HPPE yarns were taken from the bobbin and placed directly into the clamps of the tensile testing machine. Any change in twist of the specimen is avoided as well as touching the part to be tested with bare hands. The actual tensile testing was carried out as follows: the tensile testing machine, Zwick 1435, was operated with a constant extension rate. The machine was equipped with Instron clamps 5681C and stainless steel clamping blocks. The clamping pressure was 6.8 bar. The extension rate was 250 mm/min and the gage length is 500 mm. A load cell with a maximum force of 1 kN was used. A pretension of 0.2 cN/dtex was applied to remove any slack from the yarn.

(18) The maximum force-at-break (F.sub.max)(cN, centiNewton) was the maximum force applied to rapture the sample. The elongation at break (%) was determined by 100 times the displacement of the clamps (L) expressed in mm divided by the gage length (L.sub.o) (500 mm). The elongation at break was not corrected for the pretension. The E-modulus (GPa) was determined by the specific stress difference (F, measured in cN/dtex) between 0.3 and 1% elongation divided by the difference in elongation (0.7%) multiplied by 10.sup.1 and subsequently multiplied the linear density of the material (measured in g/cm.sup.3) the yarn is made of. Average values for the elongation at break, E-modulus, force-at-maximum break were calculated using data from five individual tensile tests. The specific stress is determined according to the Handbook of Fibre Rope Technology, as follows:

(19) specific stress=tension/(linear density), measured in MN/(kg/m) equal to N/tex.

(20) Assessment of Antimicrobial Activity of the HPPE Braids

(21) The assessment of the antimicrobial activity of the HPPE braids can be done as follows: Escherichia coli ATCC 11105 can be cultured from frozen stock in sterile Luria Bettani medium. The bacterial suspension has concentration of about 10.sup.9 CFU/mL. LB agar plates can be inoculated with 100 L of this bacterial suspension. The HPPE yarn constructions, braids of 161110 dtex can be cut into approximate 5 cm lengths; straight sections of the braids are to be used. Each braid can be pressed in the agar with sterile forceps to optimise contact with the agar surface. The agar plates can be subsequently incubated at 37 C. for 24 h in an exicator filled with a saturated salt solution to prevent dehydration of the agar. The width of the zone of growth inhibition at right angles to the braid length is to be recorded to nearest 1 mm at three spots along the braid and photographic images of the agar plates are to be generated.

(22) Assessment of Radio Opacity of the HPPE Braids

(23) The radio opacity of the Reference HPPE and Ag-HPPE yarn constructions, braids of 161110 dtex, was assessed by X-ray irradiation on a Toshiba Infinix VC-i vascular imaging system, of a sample material consisting of a polyurethane matrix (simulating a body) within which a piece of Reference HPPE and Ag-HPPE braid (simulating an implant) were incorporated. The difference in X-ray absorption (contrast) between the polyurethane matrix which is non-radio opaque and the pieces of Reference HPPE and Ag-HPPE braids were captured by a picture (see FIG. 4).

(24) Scanning Electron Microscopy (SEM) Analysis

(25) SEM analysis was used to visualize the differences amongst the surface morphologies of the treated HPPE yarn of Example 5 and the untreated HPPE yarn of Example 1 as well as of the HPPE yarn of Example 6 which had only silver nanoparticles. From each of the three yarns intended for SEM analysis, a piece of yarn was used. The yarn sample of Example 2 (untreated HPPE braid) was fixed with double sided adhesive tape onto a SEM sample holder and then it was coated with a conductive Au/Pd alloy layer. The other two yarn samples were fixed with double sided adhesive tape onto a SEM sample holder without been coated with a conductive layer. Imaging was done using a Philips CPSEM XL30 at an acceleration voltage of 15 kV.

(26) Transmission Electron Microscopy (TEM) Analysis

(27) TEM analysis was used to measure the thickness of silver and titanium films of the treated HPPE yarns of Examples 3 and 5. The yarns of Examples 3 and 5 were placed individually and together with an epoxy resin in separate moulds. Subsequently, the epoxy resin was cured forming a hardened matrix. The hardened matrix contained the hardened epoxy resin and the braid embedded within the hardened matrix. The hardened matrix was sliced perpendicular to the braid's direction with the help of a microtome into 70 nm thick slices containing part of the braids. This operation was carried out at 120 C. Imaging of the 70 nm slices on the crossection side of the braids was done using a Philips CM200 transmission electron microscope at an acceleration voltage of 120 kV.

Examples 1-5

Example 1: Dyneema Purity SGX 110 Dtex TS100: Reference HPPE Yarn

(28) Dyneema PuritySGX 110 dtex TS100 is a surface untreated HPPE yarn. Dyneema PuritySGX 110 dtex TS100 was used as a reference HPPE yarn. The F.sub.max, tenacity, elongation at break, E-modulus of these yarns are presented in Table 1.

Example 2: Dyneema Purity Braid: Reference HPPE Braid

(29) Some Reference HPPE yarns of Example 1 were constructed in braids of 161110 dtex with 14.9 stitches per cm. The surface tension, electrical conductivity, antimicrobial activity and radio opacity of these braids are presented in Table 1.

Example 3: Silver Sputtered Dyneema PuritySGX 110 Dtex TS100 Yarn: Ag-HPPE Yarn

(30) Dyneema PuritySGX 110 dtex TS100 was magnetron sputtered with silver as follows: A pretreatment of the yarn (substrate) in Ar plasma (pressure equal to 10 Pa and power input equal to 0.04 W/cm.sup.2) was performed for 25 sec. Subsequently the target material [elemental silver (Ag)] (sputtering target) was bombarded with primary particles generated by Ar gas (sputtering gas), under a pressure was 0.8 Pa and a power input of 0.3 W/cm.sup.2. The exposure time of the yarn (substrate) was 10 min.

(31) The amount of silver was 5.25% w/w of the total weight of the yarn plus the weight of the silver.

(32) The thickness of the silver film was 19 nm measured by Transmission Electron Microscopy.

(33) The F.sub.max, tenacity, elongation at break, E-modulus of these yarns are presented in Table 1.

Example 4: Silver Sputtered Dyneema Purity Braid: Aq-HPPE-Braid

(34) Some Ag-HPPE-yarns of Example 3 were constructed in braids of 161110 dtex with 14.9 stitches per cm. The surface tension, electrical conductivity, antimicrobial activity and radio opacity of these braids are presented in Table 1.

Example 5: Titanium Sputtered Dyneema PuritySGX 110 Dtex TS100 Yarn: Ti-HPPE-Yarn

(35) Dyneema PuritySGX 110 dtex TS100 was magnetron sputtered with titanium as follows: A pretreatment of the yarn (substrate) in Ar plasma (pressure equal to 10 Pa and power input equal to 0.04 W/cm.sup.2) was performed for 25 sec. Subsequently the target material [elemental titanium (Ti)] (sputtering target) was bombarded with primary particles generated by Ar gas (sputtering gas), under a pressure was 0.8 Pa and a power input of 1.0 W/cm.sup.2. The exposure time of the yarn (substrate) was 20 min.

(36) The amount of titanium was 8.6% w/w of the total weight of the yarn plus the weight of the silver.

(37) The thickness of the titanium film was 100 nm measured by Transmission Electron Microscopy.

(38) The F.sub.max, tenacity, elongation at break, E-modulus are presented in Table 1.

Example 6: Preparation of HPPE Yarn Having Only Silver Nanoparticles: NanoAq-HPPE-Yarn (Comparative Sample for the SEM Analysis)

(39) Dyneema PuritySGX 110 dtex TS100 is a surface untreated HPPE yarn and it was used to prepare a HPPE yarn having only silver nanoparticles as follows: A Dyneema PuritySGX 110 dtex TS100 yarn was dipped into a commercially available silver nanoparticles suspension under the name of Ag 506-Terpineol-50% (provided by Nano-Size Ltd., in Migdal Ha'Emek, Israel, www.nano-size.com) at room temperature. The liquid medium of the silver nanoparticles suspension was terpineol, the solid content of the suspension was 50% w/w and the suspension contained a dispersant of up to 3% w/w. The yarn remained in the silver nanoparticles suspension for 10 seconds. Subsequently, the yarn was removed from the silver nanoparticles suspension and excess of the suspension was squeezed out from the yarn by applying a gentle pressure equal to 1.8 bar, in between rubber rolls. The yarn was then dried by heating it in an oven at 50 C. for 30 minutes.

(40) TABLE-US-00001 TABLE 1 Mechanical and other properties of Reference HPPE yarn and Reference HPPE braid, Ag-HPPE-yarn, Ag-HPPE-braid as well as Ti-HPPE-yarn. Example 1 Example 2 Example 4 Reference Reference HPPE Example 3 Ag-HPPE- Example 5 Properties HPPE yarn braid Ag-HPPE-yarn braid Ti-HPPE-yarn Mechanical F.sub.max 36N 512N 33N 485N 33N Elongation at break 3.50% 3.40% 3.50% 3.50% 3.50% E-modulus 97 GPa not measured 97 GPa not measured 97 Gpa Other Surface tension not measured 34-36 mN/m not measured 40-42 mN/m not measured Electrical not measured 10.sup.7 S not measured 17 10.sup.3 S not measured conductivity Radio opacity not measured Non-Radio not measured Radio Opaque not measured Opaque

(41) Upon comparing the mechanical properties such as F.sub.max, elongation at break and E-modulus of the Ag- and Ti-HPPE yarns to those of the Reference HPPE yarn, it is evident that the Ag- and Ti-HPPE yarns presented surprisingly comparable mechanical properties to those of the Reference HPPE yarn (see Table 1).

(42) Upon comparing the mechanical properties such as F.sub.max, and elongation at break of the Ag-HPPE braid to those of the Reference HPPE braid, it is evident that the Ag-HPPE braid presented surprisingly comparable mechanical properties to those of the Reference HPPE braid (see Table 1).

(43) Upon comparing the surface tension (which is associated to the coatability of a yarn or a braid) of the Ag- and Ti-HPPE braid to those of the Reference HPPE braid, it becomes obvious that the Ag- and Ti-HPPE braids presented substantially increased surface tension of approximately 17%, over that of the Reference HPPE braid.

(44) Upon comparing the surface tension, electrical DC conductivity, antimicrobial activity and radio opacity of the Ag-HPPE braids to those of the Reference HPPE braid, it becomes obvious that the Ag-HPPE braid presented improved properties over those of the Reference HPPE braid.

(45) Therefore, the treated HPPE yarns or braids of the present invention such as the Ag- and Ti-HPPE yarns presented surprisingly comparable mechanical properties to those of the Reference HPPE yarn and at the same time the Ag- and Ti-HPPE braids presented not only enhanced coatability but also an array of improved properties over the corresponding properties of the Reference HPPE braid.

(46) FIG. 2 presents a Scanning Electron Microscopy (SEM) image of the untreated HPPE yarn of Example 1. The surface of the untreated HPPE yarn bears no signs of elemental metal forming a layer that adheres to the surface of the HPPE yarn.

(47) FIG. 3 presents a Scanning Electron Microscopy (SEM) image of the titanium sputtered HPPE yarn of Example 5. As it can be clearly seen the surface of the treated HPPE yarn of Example 5 has a layer of the elemental metal (titanium in this case) that adheres to the surface of the HPPE yarn. In this sample, the layer of titanium was continuous.

(48) FIG. 4 presents a Scanning Electron Microscopy (SEM) image of the HPPE yarn of Example 6 having only silver nanoparticles. The surface of this HPPE yarn bears clear signs of the presence of the silver nanoparticles as the latter are depicted as distinct almost round-like white spots on a dark background, the latter been attributed to the HPPE yarn. On each individual filament, randomly deposited silver nanoparticles with diameters varying between 48.2 and 114 nm, can be clearly seen. When this yarn upon its preparation as described in Example 6, is subjected to the peel-off adhesion test with a 3M Scotch tape, the vast majority of the silver nanoparticles are removed.

(49) Upon comparing the SEM images of FIGS. 2, 3 and 4, the differences amongst the surface morphologies of the treated HPPE yarn of Example 5 and the untreated HPPE yarn of Example 1 as well as of the HPPE yarn of Example 6 having only silver nanoparticles, the difference amongst these yarns become evident. More particularly, the difference is that these yarns (untreated HPPE yarn, treated HPPE yarn according to the present invention and a HPPE yarn having only silver nanoparticles) are distinctively different yarns because not only their surface morphologies are different but also the adhesion of the elemental metal to a HPPE yarn is very different.

(50) FIG. 5 presents a top-down X-ray contrast image of a sample material consisting of a polyurethane matrix (simulating a body) within which two pieces of HPPE braids, a silver sputtered and a non-silver sputtered, both simulating an implant were incorporated. In position 5, there is an untreated (non-silver sputtered) reference HPPE braid (Reference HPPE yarn, see Example 1) and in position 9 there is a treated (silver sputtered) HPPE braid according to the invention (Ag-HPPE braid, see Example 2). The exact position of the silver sputtered braid is clearly visible in FIG. 5, whereas the untreated HPPE braid is invisible.