Thermally curable adhesive tape and method for jacketing elongated items, especially leads

Abstract

An adhesive tape for jacketing elongated items may comprise a tape-like carrier provided on at least one side with a self-adhering adhesive layer which consists of a pressure-sensitive adhesive. The tape-like carrier may additionally be provided on at least one side with a binder that is thermally curable at a temperature of up to 110 C.

Claims

1. Adhesive tape for jacketing elongated items, comprising a tapelike carrier provided on at least one side with a self-adhering adhesive layer which consists of a pressure-sensitive adhesive, wherein the tapelike carrier is additionally provided on at least one side with a binder that is thermally curable at a temperature of up to 110 C.

2. The adhesive tape of claim 1, wherein the binder that is thermally curable at a temperature of up to 110 C. comprises a polymer which is composed to an extent of at least 5 wt % of an ethylenically unsaturated monocarboxylic acid, an ethylenically unsaturated dicarboxylic acid or an ethylenically unsaturated dicarboxylic anhydride and also of mono- or polyfunctional epoxide compounds as curing agents, and additionally of a polyol or an alkanolamine having at least two hydroxyl groups.

3. The adhesive tape of claim 1, wherein the binder is thermally curable at a temperature between 60 C. and 110 C.

4. The adhesive tape of claim 1, wherein the binder is a formaldehyde-free resin solution composed of modified polyacrylic acid and a polyhydric alcohol.

5. The adhesive tape of claim 1, wherein the carrier material comprises a polyester nonwoven.

6. The adhesive tape of claim 1, wherein the adhesive has been absorbed to an extent of more than 10% into the carrier.

7. A method for jacketing an elongated item such as more particularly leads or cable sets, where an adhesive tape comprising a tape-like carrier provided on at least one side with a self-adhering adhesive layer consisting of a pressure-sensitive adhesive is guided in a helical line around the elongated item or the elongated item is wrapped in an axial direction by the adhesive tape, the elongated item together with the adhesive tape wrapping is brought into the desired disposition, more particularly into the cable set plan, the elongated item is held in this disposition, the curable adhesive is brought to cure by the supply of thermal energy at a temperature of up to 110 C.

8. The method according to claim 7, wherein curable adhesive is brought to cure by the supply of thermal energy at a temperature of 60 C. to 110 C.

9. The method of claim 7, wherein the thermal energy is supplied over a period of 0.5 sec to 10 min.

10. A cable harness jacketed with an adhesive tape produced by the method of claim 7.

11. The method according to claim 8, wherein the thermal energy is supplied over a period of 0.5 sec to 10 min.

12. A cable harness jacketed with an adhesive tape according to claim 1.

Description

EXAMPLES

Example 1Production of an Adhesive Tape

[0057] A woven PET fabric carrier 20 mm wide, 220 m thick and with a basis weight of 130 g/m.sup.2 was coated with Acrodur 950 L having a viscosity of around 8 Pa.Math.s, adjusted by means of the Rheovis PU 1291 thickener (90 wt % Acrodur 950 L +10 wt % Rheovis PU 1291). In a second coating step, an aqueous, polymeric dispersion-based adhesive, prepared from 99 wt %, based on the total weight of the polymer, of 1-butyl acrylate monomer and 1 wt %, based on the total weight of the polymer, of acrylic acid, was applied to the still-wet impregnation. The dispersions were dried at 60 C.

Example 2Bending Test for Ascertaining the Stiffness

[0058] A test specimen consisting of 250 individual leads with a lead cross section of 0.35 mm.sup.2 was bundled using an adhesive tape 9 mm wide (tesa 51618) to form a specimen lead set, and so the specimen lead set had a diameter of 235 mm and a length of 30050 mm. This specimen lead set was wrapped spirally with the stiffening material, and an overlap of 50% was ensured. The stiffening material was subsequently cured using heat.

[0059] The cured specimen lead set was subjected to a bending test in order to determine the influence of the stiffening material on the stiffness. The bending test was performed on a tensile testing machine. For this test, the specimen lead set was placed onto two jaws with a spacing of 70 mm and pressed in centrally with a crosshead by a distance of 30 mm and loaded. The force required for the deformation of the measurement travel was recorded by a tensile testing machine in newtons. The testing velocity was 100 mm/min, both during loading and during unloading of the specimen lead set. The test was carried out at three different points on the lead set (start, middle and end). The bending force results from the mean value of the three individual measurements, and was evaluated in three categories as follows:

[0060] Evaluation Categories, Three-Point Bending Test

[0061] + highly suitable for the application (500-750 N)

[0062] of limited suitability for the application (400-500 N and 700-800 N)

[0063] not suitable for the application (<400 and >800 N)

[0064] For comparison, a commercially available adhesive tape, tesa 51036, was subjected to the same test. The results are set out in table 1 hereinafter.

Example 3C-shape Testing for Determining the Stiffness at Different Temperatures

[0065] For ascertaining the stiffness of a bent cable specimen, a test method was developed (C-cable specimen bending test). To produce a C-cable specimen (see FIG. 1) a cable lead (10) with a lead cross section of 0.35 mm.sup.2 is wound 100 times around a mount (1) to form a specimen lead set. The mount (1) has two opposite, semi-circular guides (2, 3) with a diameter of 120 mm, which are spaced apart with a spacing (A) of about 210 mm. The wound cable set is represented in FIG. 1.

[0066] The number of cable turns is 100. The resulting specimen lead set has a diameter of 155 mm and a perimeter of 690 mm. At the apices of the semicircle segments and at two linear sections (legs) in each case, the cable bundle (10) is tied together and fixed using cable ties (4, 5, 6, 7, 8, 9) with a tensile force of 21010 N, so that after removal from the mount the cable bundle (10) possesses sufficient stiffness not to deform. To further improve the stiffness of the cable bundle (10), a support (11) is positioned between the legs of the cable bundle and is fixed likewise using cable ties.

[0067] The cable bundle (10) thus produced is removed from the mount and wrapped, with a 50% overlap, with the adhesive tape under test (width 19 mm-20 mm). Wrapping for this purpose is commenced at a cable tie (e.g. (6) or (7)) of the leg in the circle segment direction ((6).fwdarw.(4) or (7).fwdarw.(5)). When the wrapping reaches the cable tie (4) or (5) at the apex of the semicircle segment, the tie is removed and the winding is continued up to the next cable tie ((4).fwdarw.(8) or (5).fwdarw.(9)) of the opposite leg. Exactly the same procedure is carried out on the other side, on the other semicircle segment.

[0068] The specimens thus prepared undergo the corresponding crosslinking method (thermal energy, 110 C.). Using wire cutters, the specimens are cut adjacent to the remaining cable ties, to give two C-shaped cable specimens (C-cable specimens), which each also have an unwrapped section on both sides of the semi-circular wrapped section. The cut is made at the distance of the diameter (120 mm) from the apex of the semicircle segment, projected onto the circle centre.

[0069] With one piece of cable respectively, loops are tied to the leg ends of the specimens, allowing the specimen to be hung up at one end and allowing a weight to be hung on at the other end. The remaining cable ties are now removed, since they can distort the result of testing. The distance between the legs is now determined.

[0070] One of the two specimens is stored at room temperature and the other at 60 C.

[0071] A 1 kg weight is hung from the respective lower leg of the C-test specimen. After an hour the deflection of the cable bundle is recorded (deflection behaviour with 1 h at RT and 60 C.) and the weight is removed. After one minute the deflection is determined again (resilience behaviour 1 min at RT or 60 C.). After an hour, the deflection is then determined again and recorded (resilience behaviour 1 h at RT or 60 C.)

[0072] The values ascertained for the C-shape deformation were graded into three categories: highly suitable for the application, of limited suitability for the application, and unsuitable for the application. The categories were evaluated as follows:

[0073] Evaluation Categories, C-shape Bending Test (Room Temperature)

[0074] + highly suitable for the application (<15% deflection)

[0075] of limited suitability for the application (>15-30%)

[0076] unsuitable for the application (>30%)

[0077] Evaluation Categories, C-shape Bending Test (60 C.)

[0078] + highly suitable for the application (<25% deflection)

[0079] of limited suitability for the application (>25-40%)

[0080] unsuitable for the application (>40%)

[0081] Evaluation Categories, C-shape Bending Test (Resilience Behaviour at RT and 60 C.)

[0082] + highly suitable for the application (<10% deflection)

[0083] of limited suitability for the application (10-30%)

[0084] unsuitable for the application (>30%)

[0085] For comparison a commercially available adhesive tape, tesa 51036, was subjected to the same test. The results are likewise set out in table 1 hereinafter.

TABLE-US-00001 TABLE 1 3-point C-shape deformation C-shape resilience bending test at RT behaviour at RT Example 1 + + + tesa 51036 C-shape deformation C-shape resilience at 60 C. behaviour at 60 C. Example 1 + + tesa 51036 Key: + highly suitable for the application of limited suitability for the application unsuitable for the application