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

Abstract

An adhesive tape has 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 (a) 5% to 25% by weight, preferably 10% to 22% by weight, of ethylene, (b) 30% to 69% by weight, preferably 40% to 60% by weight, of alkylacrylic ester having C.sub.4 to C.sub.12 alkyl radicals, (c) 20% to 55% by weight, preferably 28% to 38% by weight, of vinyl acetate, (d) 0% to 10% by weight of other ethylenically unsaturated compounds, 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 for jacketing an elongate material, the method comprising: providing an adhesive tape consisting of a textile carrier and a pressure-sensitive adhesive by applying the pressure-sensitive adhesive, in a form of a dried polymer dispersion, onto at least one side of the textile carrier, wherein the polymer is synthesized from: a) 5% to 25% by weight of ethylene, b) 30% to 69% by weight of alkylacrylic ester having C.sub.4 to C.sub.12 alkyl radicals, c) 20% to 55% by weight of vinyl acetate, and d) 0% to 10% by weight of other ethylenically unsaturated compounds, wherein the pressure-sensitive adhesive comprises between 30 and 50 parts by weight of a tackifier, based on the mass of the dried polymer dispersion, wherein the tackifier used is tackifier resins based on terpene phenols and/or rosin esters having a softening point of more than 80° C. and equal to or less than 99° C., in accordance with ASTM E28-99 (2009); and jacketing the elongate material with the adhesive tape by passing the adhesive tape in a helical line around the circumference of the elongate material such that the adhesive tape is bonded around the elongate material, wherein the adhesive tape has an unwinding force value in the range from about 3 to 9 N/cm, at a take-off speed of 30 m/min and a threshold flagging time value of at least 2001 minutes.

2. The method according to claim 1, wherein monomers (d) include alkyl (meth)acrylates, C.sub.1 to C.sub.20 alkyl (meth)acrylates with the exception of the monomers forming (b), aromatic vinyl monomers, α-methylstyrene and vinyltoluene, C.sub.1 to C.sub.10 hydroxyalkyl (meth)acrylates, hydroxyethyl or hydroxypropyl (meth)acrylate, vinyl esters of carboxylic acids containing up to 20 carbon atoms, vinyl ethers of alcohols containing up to 10 carbon atoms, vinyl halides, acid amides, and unsaturated hydrocarbons having 3 to 8 carbon atoms.

3. The method according to claim 1, wherein monomer (b) comprises n-butyl acrylate and/or 2-ethylhexyl acrylate.

4. The method according to claim 1, wherein a di- or polyfunctional monomer is added to the polymer as monomer (e), at 0% to 2% by weight.

5. The method according to claim 1, wherein the pressure-sensitive adhesive further comprises 20 to 80 parts by weight of tackifiers.

6. The method according to claim 5, wherein the softening point is more than 83° C. in accordance with ASTM E28-99 (2009).

7. The method according to claim 5, wherein the softening point is more than 90° C. in accordance with ASTM E28-99 (2009).

8. The method according to claim 1, wherein the polymer is synthesized from 10% to 22% by weight of ethylene.

9. The method according to claim 1, wherein the polymer is synthesized from 40% to 60% by weight of alkylacrylic ester.

10. The method according to claim 1, wherein the polymer is synthesized from 28% to 38% by weight of vinyl acetate.

11. The method according to claim 1, wherein a di- or polyfunctional monomer is added to the polymer as monomer (e), at 0% to 1% by weight.

12. The method according to claim 1, wherein the carrier is a woven fabric.

13. The method according to claim 1, wherein the carrier is a woven polyester fabric.

14. The method according to claim 1, further comprising: preparing the polymer dispersion of the pressure-sensitive adhesive by emulsion polymerization prior to applying the polymer dispersion onto the textile carrier.

15. A method for jacketing an elongate material, the method comprising: providing an adhesive tape consisting of a textile carrier and a pressure-sensitive adhesive by applying the pressure-sensitive adhesive, in a form of a dried polymer dispersion, onto at least one side of the textile carrier, wherein the polymer is synthesized from: a) 5% to 25% by weight of ethylene, b) 30% to 69% by weight of alkylacrylic ester having C.sub.4 to C.sub.12 alkyl radicals, c) 20% to 55% by weight of vinyl acetate, and d) 0% to 10% by weight of other ethylenically unsaturated compounds, wherein the pressure-sensitive adhesive comprises between 30 and 50 parts by weight of a tackifier, based on the mass of the dried polymer dispersion, wherein the tackifier used is tackifier resins based on terpene phenols and/or rosin esters having a softening point of more than 80° C. and equal to or less than 99° C., in accordance with ASTM E28-99 (2009); and jacketing the elongate material with the adhesive tape by wrapping the adhesive tape in an axial direction around the circumference of a portion of the elongate material, wherein the adhesive tape has an unwinding force value in the range from about 3 to 9 N/cm, at a take-off speed of 30 m/min and a threshold flagging time value of at least 2001 minutes.

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 illustrates a cross-sectional view of an adhesive tape in an embodiment,

(3) FIG. 2 illustrates a side view of a cut-out section of a cable harness which is composed of a bundle of individual cables and is jacketed with an adhesive tape in an embodiment, and

(4) FIG. 3 illustrates a cross-sectional view of an application of an adhesive tape in an embodiment.

(5) FIG. 4 illustrates a schematic of a system for measuring flagging resistance of an adhesive tape in an embodiment.

(6) FIG. 5 illustrates a test strip assembly in an embodiment.

(7) FIG. 6 illustrates a test strip assembly having an adhesive tape in an embodiment.

(8) FIG. 7 illustrates a test mandrel with a test strip assembly having an adhesive tape in an embodiment.

(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, first tape 60, and second tape 70, 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 90 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) Measurement of Unwind Force to LV312

(22) 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”.

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

(24) 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 400, prepared in a flat format, to a 1½″ core 402. The test specimens 400 may be 10 cm long and bonded to 5 mm above the highest point. The combination of tensile load by a test weight 404 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). The test weight 404 may be attached to the reverse face of the test specimens 402 at a location at least 1½ times the width of the test specimens 400.

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

(26) The critical parameters for the holding time of the test specimens 400 are weight and temperature, the weight being selected such as to result in values of at least 100 minutes.

(27) The cylindrically shaped test mandrel is a 1½″ card core 402 with an external diameter of 42±2 mm, provided with a marking line 5 mm adjacent to the vertex line.

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

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

(30) The test weight 404 is 1 kg.

(31) The test conditions are 23±1° C. and 50±5% relative humidity, or 40° C. in the heating cabinet.

(32) 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.

(33) A small piece of card 500 is adhered beneath one of the ends of each strip of test tape 502, the assembly is perforated and a release paper 504 is provided (see FIG. 5).

(34) The test strips are then individually bonded centrally to strips of the broader adhesion base tape 600 (i.e., adhesive tape with a width 1% times that of the adhesive tape under test), so that the small piece of card 500 still overlaps just (2 to 3 mm) at the end (see FIG. 6).

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

(36) The finished test samples, in other words the test strips 502 together with adhesion base tape 600, are then adhered to the card core of a test mandrel 700 in such a way that the upper end of the test strips 502 overlaps a vertex point of the test mandrel 700 by 5 mm (see FIG. 7). In this operation, only the adhesion base tape 600, and not the test strips 502, must be pressed on.

(37) The test specimens fully prepared are left for 20±4 hours without weight loading in a controlled-climate chamber at 40° C.

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

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

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

(41) The holding time is reported in minutes.

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

(43) 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.

Measurement of Bond Strength

(44) 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 μm, 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.

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

(46) 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.

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

Composition of Example Polymer Dispersion

(48) The example polymer dispersion was prepared according to Example 1 of EP 0 017 986 B1 and accordingly contained 46.7% by weight of 2-ethylhexyl acrylate, 31.1% by weight of vinyl acetate, 18% by weight of ethylene, 2.6% by weight of acrylamide and 1.6% by weight of acrylic acid.

(49) This polymer dispersion was used to formulate the pressure-sensitive adhesives (PSAs) listed in Table 1. The number here indicates the parts by weight of tackifier relative to 100 parts by weight of polymer (in each case of dry matter).

(50) TABLE-US-00001 TABLE 1 Softening Comparative point Inventive examples examples Tackifier type ° C. 1 2 3 4 5 6 Rosin ester resin 99 45 5 Snowtack 100G, Lawter Rosin ester resin 83 40 Snowtack 780 G, Lawter Rosin acid resin 64 40 Snowtack 765A, Lawter Terpene phenolic resin 96 35 Dermulsene TR 602, DRT

(51) Table 2 sets out the test results for the example specimens:

(52) TABLE-US-00002 TABLE 2 Inventive examples Compartive examples 1 2 3 4 5 6 Unwind force 1 1 1 1 1 1 Flagging resistance 3 2 3 0 0 0 Cable compatibility 1 1 1 1 1 1

(53) 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.