Adhesive tape for jacketing elongate material such as especially cable looms and jacketing method

Abstract

An adhesive tape, especially for wrapping cables, consisting of a preferably textile carrier and of a pressure-sensitive adhesive which is applied on at least one side of the carrier and is in the form of a dried polymer dispersion, the polymer being synthesized from: e) 90% to 99% by weight of n-butyl acrylate and/or 2-ethylhexyl acrylate f) 0% to 10% by weight of an ethylenically unsaturated monomer having an acid or acid-anhydride function g) 10% to 1% by weight of one or more ethylenically unsaturated monofunctional monomers different from (a) and (b) h) 0% to 1% by weight of a difunctional or polyfunctional monomer and the pressure-sensitive adhesive comprising between 15 and 100 parts by weight of a tackifier (based on the mass of the dried polymer dispersion).

Claims

1. A method of using an adhesive tape for jacketing elongate material, said method comprising either passing the adhesive tape in a helical line around the elongate material, or wrapping the elongate material in an axial direction with the adhesive tape, wherein the adhesive tape consists of (A) a textile carrier selected from the group consisting of polyester woven fabrics and (B) a pressure-sensitive adhesive that is applied on at least one side of the textile carrier, the pressure-sensitive adhesive comprising a dried mixture of two components A and B, wherein component A is a dispersion of a polymer and component B is a dispersion of at least one tackifier resin having a softening point of more than 80 C. in accordance with ASTM E28-99 (2009), the polymer being synthesized from: a) 90% to 99% by weight of n-butyl acrylate and/or 2-ethylhexyl acrylate, b) 0% to 10% by weight of an ethylenically unsaturated monomer selected from the group consisting of acrylic acid and methacrylic acid, and c) 10% to 1% by weight of one or more ethylenically unsaturated monofunctional monomers selected from the group consisting of (i) alkyl (meth)acrylates different from (a), (ii) acrylonitrile, (iii) methacrylonitrile, and (iv) vinyl acetate, the total of a)+b)+c) totalling 100% by weight of the polymer, the pressure-sensitive adhesive comprising in the dried mixture between 15 and 100 parts by weight of the tackifier relative to 100 parts by weight of the polymer, and the adhesive tape exhibiting unwind force compatibility and cable compatibility in accordance with LV 312-1 (October 2009) and an increased resistance to flagging score in accordance with the TFT method when adhered to a substrate compared to a comparison adhesive tape adhered to the same substrate under the same bonding conditions, said comparison adhesive tape being identical in all respects to the adhesive tape except that the comparison adhesive tape lacks any tackifier resin having a softening point of more than 80 C. in accordance with ASTM E28-99 (2009).

2. The method according to claim 1, wherein acrylonitrile and/or methacrylonitrile form the monomer (c) or at least part of the monomers (c).

3. The method according to claim 1, wherein 2-ethylhexyl acrylate forms monomer (a).

4. The method according to claim 1, wherein the monomer (a) consists of 2-ethylhexyl acrylate and at the same time the monomer (c) or at least part of the monomers (c) consists of acrylonitrile and/or methacrylonitrile.

5. The method according to claim 1, wherein 20 to 80 parts by weight of tackifiers have been added.

6. The method according to claim 1, wherein the pressure-sensitive adhesive according to ASTM D3330 has a bond strength to steel of at least 2.5 N/cm (for an adhesive coatweight of 100 g/m.sup.2 on a woven polyester fabric carrier).

Description

(1) The purpose of the text below is to illustrate the adhesive tape using a number of figures, without wishing thereby to bring about a restriction of whatever kind.

(2) FIG. 1 shows one embodiment of an adhesive tape according to the invention in a lateral section,

(3) FIG. 2 shows a cut-out section of a cable harness which is composed of a bundle of individual cables and is jacketed with the adhesive tape of the invention,

(4) FIG. 3 shows an advantageous application of the adhesive tape, shows a test specimen in schematic,

(5) FIG. 4 shows a test specimen with the assembly perforated,

(6) FIG. 5 shows a test specimen bonded centrally to strips of a broader adhesion base

(7) FIG. 6 so that the small piece of card still overlaps just at the end, and shows the finished test samples, in other words the test strips together with

(8) FIG. 7 adhesion base adhered to the card core in such a way that the upper end of the test specimen overaps the vertex point by a small amount.

(9) Shown in FIG. 1, in a section in the transverse direction (transverse section), is the adhesive tape, consisting of a woven fabric carrier 1, on one side of which a layer of a self-adhesive coating 2 is applied.

(10) FIG. 2 shows a cut-out section of a cable harness 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 harness.

(11) The cut-out section of cable harness shown has two turns I and II of the adhesive tape. Further turns would extend towards the left, but are not shown here.

(12) 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

(13) Outline of the Examples

(14) The adhesive tape of the invention is described below in a preferred embodiment by means of a number of examples, without wishing thereby to subject the invention to any restriction whatsoever.

(15) In addition, comparative examples are given, which show unsuitable adhesive tapes.

(16) To illustrate the invention, example adhesive tapes were produced according to the following scheme:

(17) The PSA dispersions were mixed from polymer dispersion and resin dispersion in line with the example formulas, and were intimately homogenized using a stirrer. The PSA dispersions were subsequently adjusted, by stirred incorporation of a polyurethane associative thickener (Borchigel 0625, OMG Borchers), to a viscosity of approximately 5000 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).

(18) Using a film-drawing apparatus, a woven polyester fabric (linear fibre density 167 dtex, thread count warp 48.5 1/cm, thread count weft 23 1/cm) 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 coatweight of approximately 20 g/m.sup.2.

(19) In a second work-step, the fabric impregnated in this way was coated analogously with the same dispersion, so as to result, after drying in a forced-air oven at 85 C. for 10 minutes, in a total adhesive coatweight of 100 g/m.sup.2.

Assessment Criteria

(20) The criteria for an application-compatible adhesive tape for the wrapping of cables are unwind force from rolls after storage at 40 C. for 4 weeks flagging resistance as per the TFT test cable compatibility according to LV 312

Procedure of the Tests

(21) Unless expressly stated otherwise, the measurements are carried out under test conditions of 231 C. and 505% relative humidity.

(22) Measurement of Unwind Force to LV312

(23) Here, a value in the range from about 3 to 9 N/cm at a take-off speed of 30 m/min is considered to be compatible with the application and is scored as 1. Values outside the range receive a score of 0.

(24) Measurement of Flagging Resistance to LV312 or TFT Method (Threshold Flagging Time)

(25) For determining the flagging behaviour by the TFT method, a test is employed in which an additional flexural stress is generated by the application of the test specimens, prepared in a flat format, to a 1 core. The combination of tensile load by a test weight and flexural stress causes flagging-like detachment of the adhesive tape starting from the bonded upper end, and ultimate failure by dropping of the test specimens (see FIG. 4, which also shows the schematic construction).

(26) The time in minutes before dropping is the result.

(27) The critical parameters for the holding time of the test specimens are weight and temperature, the weight being selected such as to result in values of at least 100 minutes.

(28) The cylindrically shaped test mandrel is a 1 card core with an external diameter of 422 mm, provided with a marking line 5 mm adjacent to the vertex line.

(29) The adhesion base is the adhesive tape's own reverse face.

(30) The manual roller has a weight of 2 kg.

(31) The test weight is 1 kg.

(32) The test conditions are 231 C. and 505% relative humidity, or 40 C. in the heating cabinet.

(33) The test is carried out on strips of adhesive tape 19 mm wide. A strip with a length of 400 mm is adhered to release paper and cut to form three strips with a length of 100 mm each. This should be done using a fresh cutter blade. The reverse face must not be touched.

(34) A small piece of card is adhered beneath one of the ends of each strip, and the assembly is perforated (see FIG. 5).

(35) The test strips are then individually bonded centrally to strips of the broader adhesion base (adhesive tape with a width 1 times that of the adhesive tape under test), so that the small piece of card still overlaps just (2 to 3 mm) at the end (see FIG. 6).

(36) The test specimens are rolled down using the 2 kg manual roller at a rate of 10 m/min in 3 cycles.

(37) The finished test samples, in other words the test strips together with adhesion base, are then adhered to the card core in such a way that the upper end of the test specimen overaps the vertex point by 5 mm (see FIG. 7). In this operation, only the adhesion base, and not the test specimen, must be pressed on.

(38) The test specimens fully prepared are left for 204 hours without weight loading in a controlled-climate chamber at 40 C.

(39) Weights with a mass of one kilogram are then hung onto the specimens, and the stopwatches are started.

(40) The measurement ends after failure of all three test specimens of one sample.

(41) The median of the three individual measurements is reported in minutes.

(42) The holding time is reported in minutes.

(43) In this context, a TFT value of >1200 minutes is considered to be a lower limit with regard to resistance to flagging.

(44) Values below this receive a score of 0, values from 1201 to 2000 minutes receive a score of 1, values from 2001 to 5000 minutes receive a score of 2, and values above 5001 minutes receive a score of 3. These gradations reflect increasing security against flagging.

(45) Measurement of Cable Compatibility to LV312

(46) Cable compatibility is considered to exist when there is no embrittlement after 3000 hours at 150 C. on bending around a mandrel with a diameter of 2 mm, and this is given a score of 1. Values outside this receive a score of 0.

Measurement of Bond Strength

(47) For measuring the bond strength of the pure dispersions, coated-out samples of the adhesives were prepared first of all. For this purpose, the dispersions were applied to a PET film (polyethylene terephthalate) with a thickness of 23 m, and were drawn down using a film-drawing apparatus in such a way as to result, after drying for 5 minutes at 105 C. in a forced-air drying cabinet, in an adhesive coatweight of 30 g/m.sup.2.

(48) Using a cutter knife, strips 20 mm wide and 25 cm long were cut from this sheet.

(49) For measuring the bond strength of the formulations with resin, coated-out samples were drawn down as described above onto woven polyester fabrics, and likewise cut using a cutter knife into strips 20 mm wide and 25 cm long.

(50) The bond strength to steel was measured in accordance with ASTM D3330.

Measurement of Glass Transition Temperatures

(51) The glass transition temperatures were determined on the DSC 204 F1 Phnix Dynamic Differential Scanning calorimeter from Netzsch, Germany, in 25 l aluminium crucibles with a perforated lid, under a nitrogen atmosphere (20 ml/min gas flow rate). The initial sample mass was 81 mg. The samples were subjected to measurement twice from 140 C. to 200 C., with a heating rate of 10 K/min. The subject analysis was the 2nd heating curve.

(52) The method is based on DIN 53 765.

Composition of Example Polymer Dispersions

(53) To illustrate the concept of the invention, polymer dispersions having the following comonomer composition were trialled:

(54) TABLE-US-00001 Monomer Polymer 1 Polymer 2 Polymer 3 2-Ethylhexyl acrylate 93 92 Butyl acrylate 95 Acrylic acid 4 2 1 Acrylonitrile 3 Methyl methacrylate 6 Vinyl acetate 4

(55) The bond strengths to steel of polymers 1 to 3 were measured as follows (figure in N/cm):

(56) TABLE-US-00002 Polymer 1 Polymer 2 Polymer 3 2.8 1.4 1.9

(57) The glass transition temperatures of polymers 1 to 3 were measured as follows (figure in C.):

(58) TABLE-US-00003 Polymer 1 Polymer 2 Polymer 3 47 48 36

(59) Polymer 1 was used to formulate the pressure-sensitive adhesives (PSAs) listed in Table 1, by blending with dispersions of tackifier resin. The number here indicates the parts by weight of tackifier relative to 100 parts by weight of polymer 1 (based in each case on solids).

(60) TABLE-US-00004 TABLE 1 Adhesive formulations from polymer 1 Softening Inventive Comparative point examples examples Tackifier type C. B1 B2 B3 V1 V2 V3 Rosin ester resin 99 45 10 Snowtack 100G, Lawter Rosin ester resin 83 40 Snowtack 780 G, Lawter Rosin acid resin 69 40 Snowtack 781A*, Lawter Terpene phenolic resin 96 35 Dermulsene TR 602, DRT *Former designation: Snowtack SE 380.

(61) Serving as Inventive examples B4 and B5 are polymers 2 and 3, in each case blended with 40 parts by weight of the rosin ester resin Snowtack 100G with a softening point of 99 C.

(62) Counter-example V4 is the acrylate dispersion Primal PS 83 D from the manufacturer Dow Chemical Company, blended with 8 parts by weight of Snowtack 781A, with the former designation Snowtack SE 380. This example relates to Inventive example 1 of DE 44 19 169 A1.

(63) The bond strengths to steel of Inventive examples B1 to B5 and also of Counter-examples V1 to V4 were measured as follows (figure in N/cm):

(64) TABLE-US-00005 B1 B2 B3 B4 B5 V1 V2 V3 V4 4.6 4.3 3.9 3.8 3.4 2.2 1.9 1.8 2.1

(65) The glass transition temperatures of the pressure-sensitive adhesive formulations of Inventive examples B1 to B5 and also of Counter-examples V1 to V4 were measured as follows (figure in C.):

(66) TABLE-US-00006 B1 B2 B3 B4 B5 V1 V2 V3 V4 26 29 33 25 16 32 39 47 37

(67) Table 3 sets out the test results for the example specimens:

(68) TABLE-US-00007 TABLE 3 Inventive examples Comparative examples B1 B2 B3 B4 B5 V1 V2 V3 V4 Unwind force 1 1 1 1 1 1 1 1 1 Flagging 3 2 3 1 2 0 0 0 0 resistance Cable 1 1 1 1 1 1 1 1 1 compatibility

(69) All three test criteria are vital for an application-compatible adhesive tape for cable jacketing. The inventive examples therefore show adhesive tapes which conform to the concept of the invention; the comparative examples, in contrast, are unsuitable.