ADHESIVE TAPE FOR JACKETING ELONGATE ITEMS SUCH AS ESPECIALLY CABLE HARNESSES AND METHODS FOR JACKETING

Abstract

Adhesive tapes comprise a textile carrier and a pressure-sensitive adhesive, applied on at least one side of the carrier, in the form of a thickened dried polymer dispersion, wherein the unthickened dried polymer dispersion comprises: (a) 30.0 to 98.0 wt % of monomeric acrylates; (b) 0 to 50.0 wt % of ethylenically unsaturated comonomers which are not acrylates; (c) 1.0 to 10.0 wt % of tackifier; and (d) 1.0 to 10.0 wt % of kaolin, wherein a rheological additive is added to the polymer dispersion so that the polymer dispersion has a viscosity before drying of 40 to 100 Pa*s at a shear rate of 10/s and a viscosity of 3000 to 8000 Pa*s at a shear rate of 0.01/s.

Claims

1. Adhesive tape for wrapping cables, comprising: a carrier; and a pressure-sensitive adhesive, applied on at least one side of the carrier, in the form of a thickened dried polymer dispersion, wherein the unthickened dried polymer dispersion comprises: (a) 30.0 to 98.0 wt % of monomeric acrylates; (b) 0 to 50.0 wt % of ethylenically unsaturated comonomers which are not acrylates; (c) 1.0 to 10.0 wt % of tackifier; and (d) 1.0 to 10.0 wt % of kaolin, wherein a rheological additive is added to the polymer dispersion such that the polymer dispersion has a viscosity before drying of 40 Pa*s up to 100 Pa*s at a shear rate of 10/s and a viscosity of 3000 Pa*s up to 8000 Pa*s at a shear rate of 0.01/s.

2. Adhesive tape according to claim 1, wherein the monomeric acrylates are selected from alkyl (meth)acrylates, acid amides, and a mixture thereof.

3. Adhesive tape according to claim 1, wherein the ethylenically unsaturated comonomers are selected from ethylene, aromatic vinyl monomers, divinylbenzene, vinyl esters of carboxylic acids containing up to 20 carbon atoms, vinyl ethers of alcohols containing up to 10 carbon atoms, vinyl halides, itaconic acid, maleic acid, fumaric acid and/or maleic anhydride, acrylonitrile and/or methacrylonitrile, unsaturated hydrocarbons having 3 to 8 carbon atoms, and at least one mixture thereof.

4. Adhesive tape according to claim 1, wherein the ethylenically unsaturated comonomers have an acid or acid hydride function and are at least one selected from the group of acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, and maleic anhydride.

5. Adhesive tape according to claim 1, wherein the polymer dispersion has a gel content of greater than or equal to 40% determined via Soxhlet extraction.

6. Adhesive tape according to claim 1, wherein the pressure-sensitive adhesive is admixed with 3 to 7 wt % of kaolin.

7. Adhesive tape according to claim 1, wherein the pressure-sensitive adhesive is admixed with 3 to 8 wt % of tackifier.

8. Adhesive tape according to claim 1, wherein the glass transition temperature of the pressure-sensitive adhesive is below +15° C. (determined by DSC (Differential Scanning calorimetry) in accordance with DIN 53765 at a heating rate of 10 K/min).

9. Adhesive tape according to claim 1, wherein at least one of: the pressure-sensitive adhesive has a peel adhesion on steel according to ASTM D3330 of at least 2.0 N/cm (for a surface weight of the adhesive of 100 g/m.sup.2 on woven polyester fabric carrier); and the pressure-sensitive adhesive has an unwind force of 3.0 N/cm to 9.0 N/cm at 30 m/min.

10. Adhesive tape according to claim 1, wherein the carrier is a textile carrier comprising a nonwoven material or a woven fabric.

11. Adhesive tape according to claim 10, wherein the woven fabric is a woven polyester fabric.

12. A method of jacketing an elongate item, the method comprising: leading an adhesive tape according to claim 1 in a helical line around the elongate item.

13. A method of jacketing an elongate item, the method comprising: enveloping the elongate item in the axial direction by an adhesive tape according to claim 1.

14. Elongate item jacketed with an adhesive tape according to claim 1.

15. A vehicle comprising an elongate item according to claim 13.

16. Adhesive tape according to claim 2, wherein at least one of: the alkyl (meth)acrylates comprise at least one of C.sub.1 to C.sub.20 alkyl (meth)acrylates and C.sub.1 to C.sub.10 hydroxyalkyl (meth)acrylates; and the acid amides comprises an acrylamide or a methacrylamide.

17. Adhesive tape according to claim 3, wherein at least one of: the ethylene, aromatic vinyl monomers are selected from styrene, α-methylstyrene, and vinyltoluene; the vinyl esters of carboxylic acids are selected from vinyl laurate; the vinyl ethers of alcohols are selected from vinyl methyl ether or vinyl isobutyl ether; the vinyl halides are selected from vinyl chloride or vinylidene dichloride; and the unsaturated hydrocarbons are selected from propene, butadiene, isoprene, 1-hexene or 1-octene.

18. Adhesive tape according to claim 5, wherein the gel content of the polymer dispersion is greater than or equal to 45% determined via Soxhlet extraction.

19. Adhesive tape according to claim 11, wherein the woven polyester fabric has a construction as follows: the thread count in the warp is 10 to 60/cm; the thread count in the weft is 10 to 40/cm; the warp threads possess a yarn weight of between 40 and 400 dtex; and the weft threads possess a yarn weight of between 40 and 660 dtex.

20. Adhesive tape according to claim 19, wherein at least one of: the yarn weight of the warp threads is between 44 and 330 dtex; and the yarn weight of the weft threads is between 44 and 400 dtex.

Description

[0218] In the figures:

[0219] FIG. 1 shows the adhesive tape in a lateral section;

[0220] FIG. 2 shows a detail of a cable loom which is composed of a bundle of individual cables and is jacketed with the adhesive tape of the invention;

[0221] FIG. 3 shows an advantageous application of the adhesive tape; and

[0222] FIG. 4 shows a ruler measuring a flagging value of the adhesive tape.

[0223] Shown in FIG. 1, in a section in the cross direction (transverse section), is the adhesive tape, consisting of a woven fabric carrier 1, one side of which bears an applied layer of a self-adhesive coating 2 based on an acrylate dispersion.

[0224] The adhesive has been absorbed to an extent of 20% into the carrier, thus resulting in optimum anchoring and at the same time improving the hand tearability of the carrier.

[0225] FIG. 2 shows a detail of a cable loom which is composed of a bundle of individual cables 7 and is jacketed with the adhesive tape 11 of the invention. The adhesive tape is passed in a helicoidal movement around the cable loom.

[0226] The detail of the cable loom shown has two turns I and II of the adhesive tape. Further turns will extend toward the left, but are not shown here.

[0227] In a further embodiment for jacketing, two tapes 60, 70 of the invention, furnished with an adhesive, are laminated with their adhesives at an offset (preferably by 50% in each case) to one another, producing a product as shown in FIG. 3.

EXAMPLES

Outline of the Examples

[0228] The adhesive tape of the invention is described below in a preferred embodiment by means of an example, without wishing thereby to subject the invention to any restriction whatsoever.

[0229] In addition, comparative examples are given, which show unsuitable adhesive tapes.

[0230] To illustrate the invention, example adhesive tapes were produced according to the following scheme:

[0231] The PSA dispersions were adjusted, by stirred incorporation of a polyurethane associative thickener (Borchigel 0625, OMG Borchers), to a viscosity of approximately 1000 Pa*s at a shear rate of 0.01 s.sup.−1 (measured using cone/plate geometry in rotation mode with a DSR 200 N rheometer from Rheometric Scientific).

[0232] The nonwoven web is a Maliwatt stitchbonded web with a basis weight of 55 g/m.sup.2, consisting of PET fibers with a length of 64 mm and a thickness of 3 den and with a PET stitching thread with a linear density of 50 dtex, stitched with 22 threads per inch (corresponding to 9 threads/centimeter of web width).

[0233] Using a film-drawing apparatus, the Maliwatt was coated with the thickened example PSA dispersion in such a way as to result, after drying in a forced-air oven at 85° C. for 5 minutes, in an adhesive coat weight of 90 g/m.sup.2.

Assessment Criteria

Implementation of Tests

[0234] Unless expressly stated otherwise, the measurements are carried out under test conditions of 23±1° C. and 50±5% relative humidity.

Measurement of Flagging Resistance by the SWAT Method

[0235] The SWAT test is utilized in order to investigate the flagging behavior of adhesive tapes after they have been wound spirally around a cable.

[0236] The test is carried out under standard conditions (23±1° C. and 50±5% relative humidity) and at 40° C. The elevated temperature simulates the more difficult requirements during transport.

[0237] The test uses an adhesive tape 19 mm wide. It is wound manually around a cable sheathed with ETFE (ethylene-tetrafluoroethylene) and having a diameter of 1 mm, four times) (1440°), without additional pressure. Scissors are used to cut the adhesive tape.

[0238] A flag on average 5 mm long is assumed to remain unless the end of the adhesive tape is pressed down.

[0239] A total of seven turns around the cable are produced.

[0240] The flags are measured with a ruler after three days, ten days and 30 days under standard conditions. This is shown by FIG. 4. The absolute flagging value is computed by subtracting 5 mm from the flag length actually measured.

[0241] In FIG. 4, therefore, the flagging value is 23 mm (28 mm−5 mm).

[0242] The flagging value reported as the result is the result of the mean flagging values of the seven turns. The test at 40° C. is carried out analogously in customary drying cabinets.

[0243] The adhesive tape of the invention is evaluated subsequently at 40° C. in a drying cabinet by the SWAT method specified.

[0244] Here, a value of 10 mm is deemed to be the lower limit of resistance to flagging.

[0245] Means <5 receive a score of 2, means from 5 to 10 receive a score of 1 and means >10 receive a score of 0.

Measurement of Cable Compatibility for Cables Having T2-PVC Insulation, Based on LV 312

[0246] The measurement is carried out in analogy to the measurement method specified in LV 312. The measurements take place in each case at 105° C. (T2).

Measurement of Peel Adhesion

[0247] The peel adhesion on steel was measured according to ASTM D3330.

Unwind Force

[0248] Measurement of unwind force to LV 312 at a take-off speed of 30 m/min.

Softening Point

[0249] Measurement according to ASTM E28-99 (2009)

Measurement of Glass Transition Temperatures

[0250] The glass transition temperatures were measured on the DSC 204 F1 “Phönix” Dynamic Scanning calorimeter from Netzsch, Germany, in 25 μl aluminum crucibles with a perforated lid, under a nitrogen atmosphere (20 ml/min gas flow rate). The initial sample mass was 8±1 mg. The samples were measured twice from −140° C. to 200° C. with a heating rate of 10 K/min. The subject of analysis was the 2nd heating curve.

[0251] The method is based on DIN 53 765.

Dynamic Viscosity Measurement

[0252] The viscosity measurement is carried out with a DSR 200 N rheometer from Rheometric Scientific at room temperature and in rotation mode at a shear rate of 0.01 s.sup.−1 using a cone-plate system having a diameter of 50 mm, and alternatively with a shear rate of 10 s.sup.−1.

Gel Content

[0253] The gel content is determined by Soxhlet extraction, which extracts soluble constituents from polymers in a continuous extraction. In the case of determination of the gel content of (aqueous) polyacrylate PSAs, a suitable solvent such as tetrahydrofuran, for example, extracts the soluble fractions of a polymer—the so-called sol—from the insoluble fractions—the so-called gel. Preparation: the composition for extraction is applied to siliconized release paper as a thin film—generally with a layer thickness of 120 μm—and dried for around 12 h at 80° C. (forced-air drying cabinet). The films are kept in a desiccator over desiccant. The Whatman 603 extraction sleeves are dried at 80° C. for 12 h, the empty weight of the sleeves is ascertained, and they are stored in a desiccator prior to use.

Gel Content Determination

[0254] Around 1 g of PSA is weighed into an extraction sleeve. A 100 ml round-bottom flask of the Soxhlet apparatus is filled with 60 ml of tetrahydrofuran and heated to boiling. THF vapors ascend through the vapor tube of the Soxhlet apparatus and condense in the condenser, and THF drips into the extraction sleeve and extracts the sol fraction. In the course of the extraction, the THF I runs back into the flask with the extracted sol. Dissolved sol accumulates increasingly in the flask. After 72 h of continuous extraction, the sol is completely dissolved in the THF. After cooling of the apparatus to room temperature, the extraction sleeve is then removed and dried at 80° C. over 12 h. The sleeves are kept in the desiccator until their mass is constant, after which they are weighed.

[0255] The gel content of the polymer is calculated according to the following formula:

[00002]$\mathrm{Gel}\mathrm{content}=\frac{m_3-m_1}{m_2-m_1}.Math.100\%$

where [0256] m.sub.1: mass of extraction sleeve, empty [0257] m.sub.2: mass of extraction sleeve+polymer [0258] m.sub.3: mass of extraction sleeve+gel

Flexural Stiffness

[0259] The flexural stiffness is determined using a Softometer KWS basic 2000 mN (from Wolf Messtechnik GmbH). (MD) stands for machine direction, meaning that the flexural stiffness is determined in the machine direction.

[0260] The criteria for an application-competent adhesive tape particularly suitable for the wrapping of cables are as follows: [0261] peel adhesion on steel [N/cm]; [0262] unwind force (30 m/min) [N/cm]; and [0263] cable compatibility [h].

[0264] For these criteria, five ranges are stipulated in each case, and the results are assigned to these ranges.

[0265] Furthermore, a determination is made of those ranges which defined very good or good performance, those which characterized acceptable performance, and those which characterized unacceptable performance.

TABLE-US-00001 Peel adhesion on Unwind force Cable steel [N/cm] (30 m/min) [N/cm] compatibility [h] ASTM D3330 LV312: LV312: 1 >2.5 1 4-6 1 >2500 2 2.0-2.5 2 3-4, 6-9 2 2000-2500 3 1.5-2.0 3 2-3, 9-12 3 <2000 4 1.0-1.5 4 1-2, 12-15 5 <1.0 5 <1, >15

[0266] The mandates for the four properties are as follows:

TABLE-US-00002 Very good or good Unacceptable Peel adhesion on steel Ranges 1 and 2 Ranges 3 to 5 Unwind force Ranges 1 and 2 Ranges 3 to 5 Cable compatibility Range 1 Ranges 2 and 3

[0267] To illustrate the inventive idea, polymer dispersions with the following comonomer composition were tested:

TABLE-US-00003 Comonomer composition 2-EHA BA MMA AA AcN EA HEA VAc Styrol Polymer 1 (P1) 45 46 x 5 4 x x x x Polymer 2 (P2) 98 x x 2 x x x x x Polymer 3 (P3) 51 x x x x 41 x 4 4 Polymer 4 (P4) 41 41 8   1.2 x x 1.9 8 x 2-EHA: 2-Ethylhexylacrylate BA: n-Butylacrylate MMA: Methylmethacrylate AA Acrylic acid AcN Acrylnitrile EA. Ethylhexylacrylate HEA 2-Hydroxyethylacrylate VAc Vinylacetate

[0268] These polymers are blended with different resins for which the softening temperature is specified.

TABLE-US-00004 Chemical R&B Name Composition [° C.] Resin 1 (H1) Snowtack 100G E Colophony ester resin  95.5 Resin 2 (H2) Snowtack 110X E Pentaerythritol ester 104.8 of colophony Resin 3 (H3) Snowtack TP 600G E Terpenic phenol  92.8 Resin 4 (H4) Snowtack FH 95G E fully hydrogenated  90 rosin ester

TABLE-US-00005 Ac dispersion Resin Phyllosilicate Thickener Visc. 10/s Visc. 0.01/s Peel Unwind Cable Example [wt %] [wt %] [wt %, type] [Product] [Pa*s] [Pa*s] adhesion force compatibility 1 P1, 82 H1, 15 3, Kaolin Tubivis DL600 41.9 3471 1 4 3 2 P2, 88 H2, 0 12, Kaolin Borchi Gel 0625 63.0 3365 4 3 1 3 P3, 94 H3, 6 0, Kaolin Rheo-Byk 425 12.8 1102 4 3 1 4 90 5 5, Kaolin Evo Dot VD2 8.9 1314 4 4 1 5 91 9 0, Kaolin Borchi Gel 0625 + 40.7 3685 2 3 2 Evo Dot VD2 6 89 8 3, Kaolin Tubivis DL600 41.2 3471 1 2 1 7 89 6 5, Kaolin Rheovis PU1191 + 53.6 3917 1 1 1 Rheovis AS1130 8 88 4 8, Kaolin Borchi Gel 0625 + 46.6 3594 1 1 1 Evo Dot VD2 9 94 0 6, Kaolin Rheovis PU1191 + 72.3 5217 2 1 1 Rheovis AS1130 10 91 4 5, Kaolin Borchi Gel 0625 + 121.5 9319 1 4 1 Evo Dot VD2 11 90 5 5, Laponite Byk 425 32.7 9221 5 5 1 SL-25 12 91 5 4, Smektit Rheovis PU1191 + 39.3 2976 3 2 1 Rheovis AS1130 Tubivis DL600 (CHT R. Beitlich): Thickener based on acrylic acid Borchigel 0625 (OMG Borchers): Polyurethane associative thickener Rheo-Byk 425 (Byk): Thickener based on a urea modified polyurethane Evo Dot VD2 (DyStar Colours Germany): Thickener based on a polyacrylic acid derivative Rheovis PU1191 (BASF): Polyurethane associative thickener Rheovis AS1130 (BASF): Thickener based on an acrylate copolymer

[0269] As the examples show, the use of 1 to 10 wt % of kaolin (not Laponite SL-25 or smectite!) optimizes the unwind force and leads surprisingly to a higher peel adhesion. Accordingly, as a result of the positive peel adhesion effect of kaolin, the quantity of resin can be kept low, specifically at less than 10 wt %.

[0270] Examples 5 to 9 show the best trade-off in terms of the product properties.

[0271] Examples 1 to 4 and 10 to 12 are comparative examples.