Adhesive tape for jacketing elongate items such as especially cable hamesses and method for jacketing

Abstract

The invention relates to an adhesive tape in particular for wrapping cables, consisting of a preferably textile carrier and of a pressure sensitive adhesive, applied on at least one side of the carrier, in the form of a dried polymer dispersion, the polymer having been synthesized from: (a) 70.0 to 90.0 wt % of n-butyl acrylate and/or 2-ethylhexyl acrylate (b) 10.0 to 20.0 wt % of one or more ethylenically unsaturated monomers, where at least 50.0 wt % of the ethylenically unsaturated monomers (monomer (b)) comprises methyl methacrylate (c) 0 to 10.0 wt % of a further ethylenically unsaturated monomer, different from monomer (b) (d) 0 to 5.0 wt % of an ethylenically unsaturated monomer having an acid or acid-anhydride function
and the pressure sensitive adhesive comprises between 3 and 20 parts by weight of tackifiers (based on the mass of the dried polymer dispersion), the tackifiers having a softening point of more than 90 C. according to ASTM E29-99 (2009).

Claims

1. Adhesive tape in particular for wrapping cables, consisting of a preferably textile carrier and of a pressure sensitive adhesive, applied on at least one side of the carrier, in the form of a dried polymer dispersion, the polymer having been synthesized from: (a) 70.0 to 90.0 wt % of n-butyl acrylate and/or 2-ethylhexyl acrylate (b) 10.0 to 20.0 wt % of one or more ethylenically unsaturated monomers, where at least 50.0 wt % of the ethylenically unsaturated monomers (monomer (b)) comprises methyl methacrylate (c) 0 to 10.0 wt % of a further ethylenically unsaturated monomer, different from monomer (b) (d) 0 to 5.0 wt % of an ethylenically unsaturated monomer having an acid or acid-anhydride function and the pressure sensitive adhesive comprises between 3 and 20 parts by weight of tackifiers (based on the mass of the dried polymer dispersion), the tackifiers having a softening point of more than 90 C. according to ASTM E28-99 (2009).

2. Adhesive tape according to claim 1, characterized in that n-butyl acrylate and 2-ethylhexyl acrylate are used in a ratio of 2:1 to 1:2, preferably of 1.25:1 to 1:1.25, more preferably in a ratio of 1:1.

3. Adhesive tape according to either of claims 1 and 2, characterized in that the tackifiers have a softening point of more than 100 C. in accordance with ASTM 28-99 (2009).

4. Adhesive tape according to at least one of claims 1 to 3, characterized in that monomer (b) and monomer (c) used comprise alkyl (meth)acrylates, preferably C.sub.1 to C.sub.20 alkyl (meth)acrylates with the exception of the monomers forming (a); aromatic vinyl monomers such as styrene, -methylstyrene and vinyltoluene, C.sub.1 to C.sub.10 hydroxyalkyl (meth)acrylates such as in particular hydroxyethyl or hydroxypropyl (meth)acrylate, vinyl esters of carboxylic acids containing up to 20 carbon atoms, such as vinyl acetate or vinyl laurate, vinyl ethers of alcohols containing up to 10 carbon atoms, such as vinyl methyl ether or vinyl isobutyl ether, vinyl halides such as vinyl chloride or vinylidene dichloride, acid amides such as acrylamide or methacrylamide, and unsaturated hydrocarbons having 2 to 8 carbon atoms such as ethylene, propene, butadiene, isoprene, 1-hexene or 1-octene; and more particularly ethyl acrylate.

5. Adhesive tape according to at least one of the preceding claims, characterized in that monomer (d) used comprises acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid and/or maleic anhydride.

6. Adhesive tape according to at least one of the preceding claims, characterized in that the adhesive is admixed with 5 to 15 parts by weight of tackifier (based on the mass of the dried polymer dispersion), preferably 5 to 12, more preferably 6 to 10 parts by weight of tackifier (based on the mass of the dried polymer dispersion).

7. Adhesive tape according to at least one of the preceding claims, characterized in that the glass transition temperature of the pressure sensitive adhesive is below +15 C. (determined by DSC (Differential Scanning Calorimetry) in accordance with DIN 53 765 at a heating rate of 10 K/min).

8. Adhesive tape according to at least one of the preceding claims, characterized in that the pressure sensitive adhesive has a peel adhesion on steel of at least 2.0 N/cm according to ASTM D3330 (for an adhesive coat weight of 100 g/m.sup.2 on woven polyester fabric carrier).

9. Adhesive tape according to at least one of the preceding claims, characterized in that the carrier is a textile carrier, preferably a nonwoven material or a woven fabric, more particularly a woven polyester fabric.

10. Adhesive tape according to at least one of the preceding claims, characterized in that the carrier is woven fabric, preferably a woven polyester fabric, and more preferably 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, more particularly between 44 and 330 dtex, very preferably of 167 dtex the weft threads possess a yarn weight of between 40 and 660 dtex, more preferably between 44 and 400 dtex, very preferably of 167 dtex.

11. Adhesive tape according to at least one of the preceding claims, characterized in that the textile carrier, preferably a nonwoven, has been provided on the underside with an applied film (film between textile carrier and adhesive).

12. Use of an adhesive tape according to at least one of the preceding claims for jacketing an elongate item, the adhesive tape being led in a helical line around the elongate item.

13. Use of an adhesive tape according to at least one of the preceding claims for jacketing an elongate item, the elongate item being enveloped in the axial direction by the tape.

14. Elongate item, such as in particular a cable harness, jacketed with an adhesive tape according to at least one of the preceding claims.

15. Vehicle comprising a jacketed elongate item according to claim 14.

Description

[0163] The purpose of the text below is to illustrate the adhesive tape in more detail using a number of figures, without wishing thereby to bring about any restriction of whatever kind.

[0164] FIG. 1 shows a cross-sectional view of the present adhesive tape in a lateral section,

[0165] FIG. 2 shows a side view of a cable loom which is composed of a bundle of individual cables and is jacketed with the present adhesive tape,

[0166] FIG. 3 shows a cross-sectional view of an advantageous application of the present adhesive tape,

[0167] FIG. 4 shows a top plan view of a ruler measuring flags after three days, ten days, and 30 days under standard conditions,

[0168] FIG. 5 shows a top plan view of a rectangular card adhered to a side of the present adhesive tape, and

[0169] FIG. 6 shows a schematic of bracing clamps of a tensile testing machine moving apart at speed and a distance.

[0170] 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.

[0171] 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 manual tearability of the carrier.

[0172] 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.

[0173] The detail of the cable loom shown has two turns I and II of the adhesive tape. Further turns would extend towards the left, but are not shown here.

[0174] 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

[0175] 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.

[0176] In addition, comparative examples are given, which show unsuitable adhesive tapes.

[0177] To illustrate the invention, example adhesive tapes were produced according to the following scheme:

[0178] 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).

[0179] Using a film-drawing apparatus, a woven polyester fabric (linear fibre density 167 dtex, warp thread count 43 1/cm, weft thread count 25 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 coat weight of 90 g/m.sup.2.

Assessment Criteria

[0180] The criteria for an application-compatible adhesive tape for the wrapping of cables are [0181] flagging resistance as per the SWAT test [0182] cable compatibility according to LV 312 in respect of embrittlement and discoloration [0183] fraying as per the test specified below.

Procedure of the Tests

[0184] Unless expressly stated otherwise, the measurements are carried out under test conditions of 231 C. and 505% relative humidity.

Measurement of Flagging Resistance by the SWAT Method

[0185] The SWAT test is utilized in order to investigate the flagging behaviour of adhesive tapes after they have been wound spirally around cable.

[0186] The test is carried out under standard conditions (231 C. and 505% relative humidity) and at 40 C. The elevated temperature simulates the more difficult requirements during transport.

[0187] 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.

[0188] A flag on average 5 mm long is assumed to remain unless the end of the adhesive tape is pressed down.

[0189] A total of seven wraps are produced around the cable.

[0190] 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.

[0191] In FIG. 4, therefore, the flagging value is 23 mm (28 mm5 mm).

[0192] The flagging value reported as the result is the result of the mean flagging values of the seven wraps. The test at 40 C. is carried out analogously in customary drying cabinets.

[0193] The adhesive tape of the invention is evaluated below at 40 C. in a drying cabinet by the SWAT method specified.

[0194] Here, a value of 10 mm is deemed to be the lower limit of resistance to flagging.

[0195] 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 T3-PVC Insulation, Based on LV 312

[0196] Cables with T3-PVC insulation are not tested in LV 312. The measurement is carried out in analogy to the measurement method specified in LV 312. The measurements are made in each case at 125 C. (T3).

Embrittlement

[0197] If there is no embrittlement after 3000 h at 150 C. on bending around a mandrel with a diameter of 2 mm, cable compatibility is considered to exist, and is given a score of 2. If the sample undergoes embrittlement, the specimen receives a score of 0.

Discoloration

[0198] The absence of discolorations, or the incidence of marginal discolorations, after 3000 h at 150 C. is considered to denote high cable compatibility and is given a score of 2. Clearly visible discolorations which are nevertheless not too dark may possibly be classed as sufficiently compatible, and receive a score of 1. Black or dark brown discolorations are considered not to be cable compatible, and receive a score of 0.

Measurement of Peel Adhesion

[0199] For measuring the peel adhesion 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 coat weight of 30 g/m.sup.2.

[0200] Using a cutter knife, strips 20 mm wide and 25 cm long were cut from this sheet.

[0201] For measuring the peel adhesion 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. The peel adhesion on steel was measured in accordance with ASTM D3330.

Measurement of Glass Transition Temperatures

[0202] The glass transition temperatures were determined on the DSC 204 F1 Phnix Dynamic Differential 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 of analysis was the 2nd heating curve. The method is based on DIN 53 765.

Dynamic Viscosity Measurement

[0203] 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.

Measurement of Fraying Resistance by the Tear Continuation Method

[0204] The method of the continued tearing of warp threads is utilized in order to investigate the fraying performance of the adhesive tapes.

[0205] The test takes place using an adhesive tape 19 mm wide and bearing, at a coat weight of 90 g/m.sup.2, a pressure sensitive adhesive, the carrier being a woven polyester fabric (48 warp threads per cm and 23 weft threads per cm, in each case polyester threads with a linear density of 167 dtex). A sample with a length of 10 cm is cut from this adhesive tape. Using tweezers, five warp threads are parted from the assembly over a length of 3 cm at one end on one side. The five parted warp threads are convoluted with one another. Subsequently, for reinforcement, a rectangular card with a thickness of 0.3 mm, a length of 6 cm and a width of 3 cm is adhered to the side of the adhesive tape bearing the adhesive. The card is positioned on the adhesive tape in such a way that the card overhangs the adhesive tape only on the long side on which no warp threads have been parted. The distance to the long side on which the warp threads have been parted is to be exactly 3 mm. The distance to the short side on which no warp threads have been parted is to be exactly 1 cm, so that the opposite side of the card lies in a line with the start of the parted warp threads (see FIG. 5).

[0206] The adhesive tape is subsequently clamped into a CRE tensile testing machine (Zwick) equipped with bracing clamps 6 cm wide. A characteristic of the tensile testing machine is that the lower bracing clamp is stationary, while the other one moves at constant speed during the test, and another characteristic is that the loading frame of the machine does not exhibit any sagging at all. In this arrangement, the card applied to the adhesive tape in order to provide it with reinforcement is clamped into the lower clamping jaw. The threads parted and convoluted beforehand are clamped to the outer edge of the upper clamping jaw. The distance between the two effective clamping points of the test installation for this purpose is exactly 1 cm before the start of measurement. The tensile testing machine is subsequently moved apart with a constant speed of 5 cm/min by a distance of exactly 3.5 cm (see FIG. 6). As a result, a force is applied to the parted threads. This force is introduced at the start of the measurement at right angles to the longitudinal side of the adhesive tape.

[0207] During the measurement, a determination is made of the force in millinewtons which must be expended in order to cause further separation of the five warp threads. In this case, the force also alters over the measurement time as a result of the changing angle of pull-out of the threads. For comparison between different adhesive tapes, the maximum force required (peak) is employed. The tear value as a measure of the fraying resistance, which is reported as the result, is the result of the mean value of the maximum tear force from measurements on five samples. Product specimens which are evaluated positively from the customer viewpoint, and whose fraying is normal, have maximum tear force values of at least 1400 mN.

Composition of Example Polymer Dispersions

[0208] To illustrate the concept of the invention, polymer dispersions having the following comonomer composition were trialled:

TABLE-US-00001 A1 A2 B1 B2 and C D Comparative Example 1 93 0 0 3 4 Comparative Example 2 51 0 0 47 2 Comparative Example 3 0 98.5 0 0 1.5 Comparative Example 4 0 96 0 0 4 Comparative Example 5 41 41 8 9 1 Comparative Example 6 36 44 12 5 3 Comparative Example 7 38 42 10 8 2 Inventive Example 1 48 40 5 5 2 Inventive Example 2 41 41 8 9 1 Inventive Example 3 36 44 12 5 3 Inventive Example 4 38 42 10 8 2 Comparative Example 8 48 40 5 5 2 Comparative Example 9 35 35 8 18 4 Comparative Example 10 41 41 8 9 1 A1 2-ethylhexyl acrylate A2 n-butyl acrylate B1 methyl methacrylate B2 and C ethylenically unsaturated monomer (vinyl ester) D acrylic acid

[0209] These polymer dispersions were trialled with different tackifiers:

TABLE-US-00002 Polymer Resin fraction fractions [weight [weight R&B fractions] fractions] Chemistry Tradename [ C.] Comparative Example 1 100 30 rosin ester Snowtack 100G 96 Comparative Example 2 100 20 rosin ester Snowtack 782G 72 Comparative Example 3 100 0 X x x Comparative Example 4 100 15 rosin ester Icatack 1070 93 Comparative Example 5 100 0 X x x Comparative Example 6 100 2.5 rosin ester Emultrol E185 82 Comparative Example 7 100 4 rosin ester Snowtack 110X 105 Inventive Example 1 100 5 rosin ester Aquatac 2600 98 Inventive Example 2 100 7.5 rosin ester Snowtack 110X 105 Inventive Example 3 100 10 terpene phenol Snowtack TP600G 100 Inventive Example 4 100 15 terpene phenol TSR1009X50 112 Comparative Example 8 100 17.5 rosin ester Aquatac 2600 98 Comparative Example 9 100 22 rosin ester Emultrol E185 82 Comparative Example 10 100 28 rosin ester Snowtack 100G 96

[0210] The results of testing are shown below:

TABLE-US-00003 SWAT Fraying [mm] [mN] Cable compatibility Comparative Example 1 2 3500 0 Comparative Example 2 1 1800 0 Comparative Example 3 2 1100 2 Comparative Example 4 1 1300 0 Comparative Example 5 0 1100 2 Comparative Example 6 1 1200 2 Comparative Example 7 1 1300 2 Inventive Example 1 2 1450 2 Inventive Example 2 2 1500 2 Inventive Example 3 2 1600 2 Inventive Example 4 2 1700 2 Comparative Example 8 1 1800 1 Comparative Example 9 1 2300 0 Comparative Example 10 1 3000 0 tesa 51026 1 1600 2

[0211] For an application-compatible adhesive tape for cable jacketing, all three test criteria are vital. Inventive Examples 1 to 4 show an adhesive tape corresponding to the concept of the invention, whereas the comparative examples are unsuitable.

[0212] Even the commercially available cable bandaging adhesive tape Tesa 51026 does not meet all of the criteria. Tesa 51026 is a woven polyester fabric adhesive tape for cable wrapping. It consists of a woven polyester fabric with a basis weight of 125 to 135 g/m.sup.2 and an adhesive coat of 80 to 100 g/m.sup.2. Warp and weft threads have the same linear yarn density of approximately 167 dtex.