REMOVABLE PRESSURE-SENSITIVE ADHESIVE STRIP

Abstract

Disclosed is a pressure-sensitive adhesive strip comprising a carrier and a pressure-sensitive adhesive compound layer HS1 on one of the surfaces of said carrier, wherein (i) the carrier has a breaking elongation of at least 250% in the longitudinal direction and/or transverse direction, and (ii) the pressure-sensitive adhesive compound layer HS1 consists of a pressure-sensitive adhesive compound which contains, as the base polymer, at least one solid acrylonitrile-butadiene rubber as well as at least one adhesive resin, wherein the proportion of adhesive resin is in total 30 to 130 phr.

Claims

1. A pressure-sensitive adhesive strip comprising a carrier and a layer HS1 of pressure-sensitive adhesive that is disposed on one of the surfaces of the carrier, where: (i) the carrier in the longitudinal direction and/or the transverse direction has an elongation at break of at least 250% and (ii) the layer HS1 of pressure-sensitive adhesive consists of a pressure-sensitive adhesive which comprises as base polymer at least one solid acrylonitrile-butadiene rubber and further comprises at least one tackifier resin, with the fraction of tackifier resin totaling 30 to 130 phr.

2. The pressure-sensitive adhesive strip as claimed in claim 1, wherein disposed on the surface of the carrier opposite the layer HS1 of pressure-sensitive adhesive is a layer HS2 of pressure-sensitive adhesive.

3. The pressure-sensitive adhesive strip as claimed in claim 2, wherein the layer HS2 of pressure-sensitive adhesive likewise consists of a pressure-sensitive adhesive which comprises as base polymer at least one solid acrylonitrile-butadiene rubber and further comprises at least one tackifier resin, with the fraction of tackifier resin totaling 30 to 130 phr.

4. The pressure-sensitive adhesive strip as claimed in claim 1, wherein the acrylonitrile content in the solid acrylonitrile-butadiene rubber of the layer HS1 pressure-sensitive adhesive is between 10 and 45 wt %.

5. The pressure-sensitive adhesive strip as claimed in claim 1, wherein the pressure-sensitive adhesive based on solid acrylonitrile-butadiene rubber of the layer HS1 pressure-sensitive adhesive comprises as further base polymer at least one liquid acrylonitrile-butadiene rubber, with the acrylonitrile content in the at least one liquid acrylonitrile-butadiene rubber between 10 and 45 wt %.

6. The pressure-sensitive adhesive strip as claimed in claim 1, wherein in the pressure-sensitive adhesive based on solid acrylonitrile-butadiene rubber of the layer HS1 pressure-sensitive adhesive, the base polymer consists exclusively of acrylonitrile-butadiene rubber, with no polymer other than the acrylonitrile-butadiene rubber being present in the pressure-sensitive adhesive.

7. The pressure-sensitive adhesive strip as claimed in claim 1, wherein in the pressure-sensitive adhesive based on solid acrylonitrile-butadiene rubber of the layer HS1 pressure-sensitive adhesive, there is a blend of at least three synthetic nitrile rubbers S1, S2, and S3, where: (a) the blend is microphase-separated, characterized by at least three different glass transition temperatures in the DSC, (b) at least one glass transition temperature is greater than 10 C. and one glass transition temperature is less than 20 C., (c) the nitrile rubber or rubbers S1 has/have an acrylonitrile fraction of greater than or equal to 35 wt %, (d) the nitrile rubber or rubbers S2 has/have an acrylonitrile fraction of greater than 25 wt % and less than 35 wt %, and (e) the nitrile rubber or rubbers S3 has/have an acrylonitrile fraction of less than or equal to 25 wt %.

8. The pressure-sensitive adhesive strip as claimed in claim 1, wherein in the pressure-sensitive adhesive based on solid acrylonitrile-butadiene rubber of the layer HS1 pressure-sensitive adhesive, the fraction of tackifier resin totals 40 to 120 phr.

9. The pressure-sensitive adhesive strip as claimed in claim 1, wherein in the pressure-sensitive adhesive based on solid acrylonitrile-butadiene rubber of the layer HS1 of pressure-sensitive adhesive, the tackifier resin used comprises terpene-phenolic resin and/or polyterpene.

10. The pressure-sensitive adhesive strip as claimed in claim 2, wherein the layers HS1 and HS2 of pressure-sensitive adhesive have an identical composition.

11. The pressure-sensitive adhesive strip as claimed in claim 1, wherein disposed on the surface of the carrier opposite the layer HS1 of pressure-sensitive adhesive is a layer HS2 of pressure-sensitive adhesive which consists of a pressure-sensitive adhesive whose base polymer consists exclusively of polymer which is different from acrylonitrile-butadiene rubber, with the pressure-sensitive adhesive comprising as base polymer at least one vinylaromatic block copolymer.

12. The pressure-sensitive adhesive strip as claimed in claim 11, wherein in the pressure-sensitive adhesive of the layer HS2 of pressure-sensitive adhesive, the base polymer consists exclusively of vinylaromatic block copolymer, with no polymer other than the vinylaromatic block copolymer being present in the pressure-sensitive adhesive.

13. The pressure-sensitive adhesive strip as claimed in claim 11, wherein the pressure-sensitive adhesive of the layer HS2 of pressure-sensitive adhesive further comprises at least one tackifier resin.

14. The pressure-sensitive adhesive strip as claimed in claim 1, wherein the layer HS1 of pressure-sensitive adhesive are outer layers of pressure-sensitive adhesive.

15. The pressure-sensitive adhesive strip as claimed in claim 1, wherein the layer HS1 of pressure-sensitive adhesive has a thickness of 10 to 200 m.

16. The pressure-sensitive adhesive strip as claimed in claim 1, wherein the carrier in the longitudinal direction and/or the transverse direction has an elongation at break of at least 300%.

17. The pressure-sensitive adhesive strip as claimed in claim 1, wherein the carrier in the longitudinal direction and/or the transverse direction, has a resilience of above 50%.

18. The pressure-sensitive adhesive strip as claimed in claim 1, wherein the carrier in the longitudinal direction and/or the transverse direction has a 50% elongation stress of less than 20 N/mm2.

19. The pressure-sensitive adhesive strip as claimed in claim 1, wherein the carrier has at least one layer which consists of polyurethane.

20. The pressure-sensitive adhesive strip as claimed in claim 1, wherein the carrier consists only of a single layer. pg,46

21. The pressure-sensitive adhesive strip as claimed in claim 1, wherein the carrier is 10 to 200 m.

Description

FIGURES

[0145] In the figures

[0146] FIG. 1 shows a three-layer pressure-sensitive adhesive strip of the invention and

[0147] FIG. 2 shows a three-layer pressure-sensitive adhesive strip of the invention in an alternative embodiment.

[0148] FIG. 1 shows a pressure-sensitive adhesive strip of the invention, composed of three layers 1, 2, 3, which is redetachable without residue or destruction, without tearing, by extensive stretching, at an angle of more than 45 relative to the bond plane, for example. The strip consists of a stretchable carrier 1, i.e., a carrier having an elongation at break of at least 250% in the longitudinal and/or transverse directions, preferably in both the longitudinal and the transverse directions, the carrier 1 being of single-layer embodiment. Present on the carrier on both sides are outer layers 2, 3 of adhesive that can be used in accordance with the invention. The protruding end of the carrier layer 1 may serve as a grip tab, but is not mandatorily present.

[0149] FIG. 2 shows the pressure-sensitive adhesive strip of the invention in an alternative variant. The pressure-sensitive adhesive strip consists of three layers 1, 2, 3, which are disposed congruently one above another, namely the single-layer stretchable carrier 1 and the double-sidedly outer layers 2 and 3 of adhesive employable in accordance with the invention. In order to produce a grip tab for pulling to achieve the extensive stretching (particularly at an angle of more than 45 relative to the bond plane), one end of the pressure-sensitive adhesive strip is made nonadhesive on both sides, by the application of preferably siliconized pieces of film or paper 4.

EXAMPLES

Inventive Example 1Production of an Inventive Pressure-Sensitive Adhesive Strip

[0150] The pressure-sensitive adhesive (PSA) containing 62 wt % of the solid acrylonitrile-butadiene rubber Nipol 401, 5 wt % of the liquid acrylonitrile-butadiene rubber Nipol 1312 LV, and 33 wt % of the tackifier resin Dertophene T, based in each case on the dry weight of the PSA, were homogenized as a solvent-based compound in a kneading apparatus with double-sigma kneading hook. The solvent used was methyl ethyl ketone. The kneading apparatus was cooled by means of water cooling. The stated constituents of the adhesive are characterized as follows:

[0151] Nipol 401: solid acrylonitrile-butadiene rubber having an acrylonitrile content of 18.5 wt %, a Mooney viscosity (ML 1+4 at 100 C., as per DIN 53523) of 73 to 83, and a T.sub.g of 37 C.

[0152] Nipol 1312 LV: liquid acrylonitrile-butadiene rubber having an acrylonitrile content of 26.5 wt %, a Brookfield viscosity of 9000 to 16 000 mPa*s, measured with spindel 4, 12 rpm, 50 C., and a T.sub.g of 23 C.

[0153] Dertophene T: terpene-phenolic resin having a softening point of 95 C.

[0154] First of all, in a first step, the solid acrylonitrile-butadiene rubber Nipol 401 was preswollen with the same amount of methyl ethyl ketone for 12 hours at 23 C. This so-called preliminary batch was subsequently kneaded for 2 hours. Thereafter, again, the above-selected amount of methyl ethyl ketone and the liquid acrylonitrile-butadiene rubber Nipol 1312 LV were added in two steps and kneaded in each case for 10 minutes. The Dertophene T tackifier resin was subsequently added as a solution in methyl ethyl ketone with a solids content of 50 wt %, with homogeneous kneading for a further 20 minutes. The final solids content of the PSA was adjusted to 30 wt % by addition of methyl ethyl ketone.

[0155] The PSA was subsequently coated onto a liner 23 m thick, using a coating knife, on a commercial laboratory coating table (for example, from SMO (Sondermaschinen Oschersleben GmbH)). The methyl ethyl ketone was evaporated off at 105 C. in a forced-air drying cabinet for 10 minutes, and hence the PSA was dried. The slot width during coating was set so that the thickness of the PSA layer, achieved after evaporation of the solvent, was 35 m. A polyurethane carrier having an elongation at break of more than 250%, in both the longitudinal and the transverse directions, and a thickness of 80 m was subsequently laminated on both sides with a layer of this PSA freed from the solvent. The result was a double-sided adhesive tape having a stretchable polyurethane carrier and two PSA layers based on solid acrylonitrile-butadiene rubber.

Comparative Example 2Production of a Noninventive Pressure-Sensitive Adhesive Strip

[0156] A 40 wt % strength adhesive solution in benzine/toluene/acetone was prepared from 50.0 wt % of the vinylaromatic block copolymer Kraton D1102AS, 45.0 wt % of the tackifier resin Dercolyte A115, 4.5 wt % of the tackifier resin Wingtack 10, and 0.5 wt % of the aging inhibitor Irganox 1010. The weight fractions of the dissolved constituents are based in each case on the dry weight of the resultant PSA. The stated constituents of the PSA are characterized as follows:

[0157] Kraton D1102AS: styrene-butadiene-styrene triblock copolymer from Kraton Polymers with 17 wt % diblock, block polystyrene content: 30 wt %

[0158] Dercolyte A 115: solid a-pinene tackifier resin having a ring and ball softening temperature of 115 C. and a DACP of 35 C.

[0159] Wingtack 10: liquid hydrocarbon resin from Cray Valley

[0160] Irganox 1010: pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate) from BASF SE

[0161] The PSA was subsequently coated onto a liner 23 m thick, using a coating knife, on a commercial laboratory coating table (for example, from SMO (Sondermaschinen Oschersleben GmbH)). The solvent was evaporated off at 105 C. in a forced-air drying cabinet for 10 minutes, and hence the PSA was dried. The slot width during coating was set so that the thickness of the PSA layer, achieved after evaporation of the solvent, was 35 m. A polyurethane carrier having an elongation at break of more than 250%, in both the longitudinal and the transverse directions, and a thickness of 80 m was subsequently laminated on both sides with a layer of this PSA freed from the solvent. The result was a double-sided adhesive tape having a stretchable polyurethane carrier and two PSA layers based on vinylaromatic block copolymer.

[0162] Results:

[0163] The double-sided adhesive tape from example 1, with a stretchable polyurethane carrier and two PSA layers based on solid acrylonitrile-butadiene rubber, relative to the double-sided adhesive tape from example 2, with a stretchable polyurethane carrier and two PSA layers based on vinylaromatic block copolymer, exhibits a significantly reduced susceptibility to tears on extensive stretching at an angle of 90 relative to the bond plane (see table 1). While approximately every third pressure-sensitive adhesive strip tears on stripping of the comparative example, all of the pressure-sensitive adhesive strips from example 1 were strippable without tearing. Surprisingly, therefore, in an adhesive tape having a stretchable carrier, the replacement of PSA layers based on vinylaromatic block copolymer by PSA layers based on solid acrylonitrile-butadiene rubber leads to a significant reduction in the susceptibility to tears, even at a removal angle of 90 relative to the bond plane.

[0164] Also surprisingly, in the double-sided adhesive tape, replacing PSA layers based on vinylaromatic block copolymer by PSA layers based on solid acrylonitrile-butadiene rubber leads to an increase in the transverse impact strength, i.e., the shock resistance in the x,y-direction, and also in the penetrative impact strength, i.e., the shock resistance in the z-direction, as demonstrated by the results from the DuPont x,y and DuPont z measurements, respectively.

[0165] By means of the stated replacement of the PSA layers in the double-sided adhesive tape, it was also possible to boost the peel adhesion of the pressure-sensitive adhesive strip.

TABLE-US-00001 TABLE 1 Characteristics of an inventive and of a noninventive pressure-sensitive adhesive strip. Trial Peel adhesion DuPont x, y DuPont z Tears at 90 [N/cm] [mJ].sup.1 [mJ].sup.2 [%].sup.3 Inventive 1.1 1122 633 0 example 1 Comparative 0.4 963 584 35 example 2 .sup.1Transverse impact strength; .sup.2Penetrative impact strength; .sup.3Susceptibility to tears

Test Methods

[0166] All of the measurements were conducted at 23 C. and 50% relative humidity unless otherwise indicated. The mechanical data and technical adhesive data were ascertained as follows:

Softening Point T.SUB.s

[0167] The figures for the softening point T.sub.s, also called softening temperature, of oligomeric compounds, polymeric compounds, and resins are based on the ring & ball method according to DIN EN 1427:2007 with appropriate application of the provisions (investigation of the oligomer, polymer or resin sample instead of bitumen, with the procedure otherwise retained); the measurements are made in a glycerol bath.

Elongation at Break, Tensile Strength, 50% Elongation Stress

[0168] The elongation at Break, the Tensile Strength, and the stress at 50% elongation of a carrier were measured in a method based on DIN EN ISO 527-3, using a sample strip of the carrier, specimen type 2, having a width of 20 mm, at a separation rate of 100 mm per minute. The initial spacing of the clamping jaws was 100 mm. The test conditions were 23 C. and 50% relative humidity.

Resilience or Elasticity

[0169] The resilience was measured by stretching by 100%, holding in this stretch for 30 seconds, and then releasing. After a waiting time of 1 minute, the length was measured again.

[0170] The resilience is then calculated as follows: Rs=((L.sub.100L.sub.end)/L.sub.0).Math.100

[0171] where Rs =resilience in %

[0172] L.sub.100: length after stretching by 100%

[0173] L.sub.0: length before stretching

[0174] L.sub.end: length after the relaxation of 1 min.

[0175] The resilience here corresponds to the elasticity.

Susceptibility to Tears

[0176] 20 strips 10 mm wide and 40 mm long are punched from the adhesive tape under investigation. These strips are bonded over a length of 30 mm to a PC plate conditioned with ethanol, thus leaving a grip tab 10 mm long. A second PC plate is adhered to the second side of the bonded strips, in such a way that the two PC plates lie flush over one another. The assembly is rolled down 10 times using a 4 kg roller (five times backward and forward). After a peel increase time of 48 hours, the 20 strips are stripped manually from the bonded joint, using the grip tab,

[0177] a) at a 90 angle relative to the bond plane, or alternatively

[0178] b) at a 0 angle (i.e., in the bond plane).

[0179] An evaluation is made of how many of the 20 specimens tear on stripping at the selected angle, the result being reported in %.

Transverse Impact Strength (DuPont Test in the x-y Plane)

[0180] A sample of the pressure-sensitive adhesive strip under investigation was cut out in the form of a square frame (outer dimensions 33 mm33 mm; frame width 2.0 mm; inner dimensions (window cutout) 29 mm29 mm). This sample was adhered onto a PC frame (outer dimensions 45 mm45 mm; frame width 10 mm; inner dimensions (window cutout) 25 mm25 mm; thickness 3 mm). Adhered on the other side of the pressure-sensitive adhesive strip was a PC window of 35 mm35 mm. PC frame, adhesive tape frame, and PC window were bonded in such a way that the geometric centers and the diagonals lay over one another in each case (corner to corner). The bond area was 248 mm.sup.2. The bond was pressed at 248 N for 5 s and stored for 48 hours with conditioning at 23 C./50% relative humidity.

[0181] Immediately after storage, the adhesive assembly of PC frame, pressure-sensitive adhesive strip, and PC window was clamped by the protruding edges of the PC frame into a sample mount in such a way that the assembly was aligned vertically. The sample mount was then inserted centrally into the holder provided on the DuPont Impact Tester. The impact head, weighing 300 g, was inserted such that the rectangular striking geometry with the dimensions of 20 mm3 mm lay centrally and flushly on the upwardly directed end-face side of the PC window.

[0182] A weight having a mass of 150 g was dropped from a height of 3 cm (measurement conditions 23 C., 50% relative humidity) vertically onto the corresponding arrangement of the assembly formed of sample mount, sample, and impact head, the weight being guided on two guide rods. The height of the drop weight was increased in steps of 3 cm until the impact energy introduced destroys the sample as a result of the transverse impact load, and the PC window parted from the PC frame.

[0183] In order to be able to compare trials with different samples, the energy was calculated as follows:

[0184] E[j]=height [m]*mass of weight [kg]*9.81 kg/m*s.sup.2

[0185] Five samples per product were tested, and the mean energy value was reported as the characteristic number for the transverse impact strength.

Penetrative Impact Strength (DuPont Test in the z Plane)

[0186] A sample of the pressure-sensitive adhesive strip under investigation was cut out in the form of a square frame (outer dimensions 33 mm33 mm; frame width 2.0 mm; inner dimensions (window cutout) 29 mm29 mm). This sample was adhered onto a PC frame (outer dimensions 45 mm45 mm; frame width 10 mm; inner dimensions (window cutout) 25 mm25 mm; thickness 3 mm). Adhered on the other side of the pressure-sensitive adhesive strip was a PC window of 35 mm35 mm. PC frame, adhesive tape frame, and PC window were bonded in such a way that the geometric centers and the diagonals lay over one another in each case (corner to corner). The bond area was 248 mm.sup.2. The bond was pressed at 248 N for 5 s and stored for 48 hours with conditioning at 23 C./50% relative humidity.

[0187] Immediately after storage, the adhesive assembly of PC frame, pressure-sensitive adhesive strip, and PC window was clamped by the protruding edges of the PC frame into a sample mount in such a way that the assembly was aligned horizontally. In this case, the PC frame lies flat on the protruding edges on the sample mount, so that the PC window was in free suspension (held by the adhesive tape specimen) beneath the PC frame. The sample mount was then inserted centrally into the holder provided on the DuPont Impact Tester. The impact head, weighing 150 g, was inserted in such a way that the circular striking geometry with a diameter of 24 mm lay centrally and flushly on the surface of the PC window, which was freely accessible from above.

[0188] A weight having a mass of 150 g was dropped from a height of 5 cm (measurement conditions 23 C., 50% relative humidity) vertically onto the corresponding arrangement of the assembly formed of sample mount, sample, and impact head, the weight being guided on two guide rods. The height of the drop weight was increased in steps of 5 cm until the impact energy introduced destroys the sample as a result of the penetrative impact load, and the PC window parted from the PC frame.

[0189] In order to be able to compare trials with different samples, the energy was calculated as follows:

[0190] E=height [m]*mass of weight [kg]*9.81 kg/m*s.sup.2

[0191] Five samples per product were tested, and the mean energy value was reported as the characteristic number for the penetrative impact strength.

Diameter

[0192] The average diameter of the cavities formed by the microballoons in a PSA layer is determined on the basis of cryofracture edges of the pressure-sensitive adhesive strip under a scanning electron microscope (SEM) at 500-times magnification. The diameter of each of the microballoons in the PSA layer under investigation that are visible on SEM micrographs of 5 different cryofracture edges of the pressure-sensitive adhesive strip is ascertained graphically, with the arithmetic mean of all diameters ascertained in the 5 SEM micrographs representing the average diameter of the cavities of the PSA layer that are formed by the microballoons, in the sense of the present patent application. Ascertaining the diameters of the microballoons visible on the micrographs graphically is done by taking the maximum enlargement in any (two-dimensional) direction for each individual microballoon in the PSA layer under investigation, from the SEM micrographs, and regarding that maximum enlargement as the diameter of said microballoon.

Glass Transition Temperature (T.SUB.g.)

[0193] Glass transition pointsreferred to synonymously as glass transition temperaturesare reported as the result of measurements by dynamic scanning calorimetry (DSC) in accordance with DIN 53 765, particularly sections 7.1 and 8.1, but with uniform heating and cooling rates of 10 K/min in all heating and cooling steps (compare DIN 53 765; section 7.1; note 1). The initial sample mass is 20 mg.

DACP

[0194] 5.0 g of test substance (the tackifier resin specimen under investigation) are weighed out in a dry test tube, and 5.0 g of xylene (isomer mixture, CAS [1330-20-7],98.5%, Sigma-Aldrich #320579 or comparable) are added. The test substance is dissolved at 130 C. and then cooled down to 80 C. Any xylene that escapes is made up with further xylene, to restore 5.0 g of xylene. Then 5.0 g of diacetone alcohol (4-hydroxy-4-methyl-2-pentanone, CAS [123-42-2], 99%, Aldrich #H41544 or comparable) are added. The test tube is shaken until the test substance has dissolved completely. For this purpose the solution is heated to 100 C. The test tube with the resin solution is subsequently inserted into a Novomatics Chemotronic Cool cloud point measuring instrument and heated therein to 110 C. It is cooled down with a cooling rate of 1.0 K/min. The cloud point is detected optically. For this purpose, the temperature at which the turbidity of the solution is 70% is recorded. The result is reported in C. The lower the DACP, the higher the polarity of the test substance.

Density

[0195] The density of unfoamed and foamed layers of adhesive is ascertained by forming the ratio of coatweight to thickness of the layer of adhesive applied to a carrier.

[0196] The coatweight can be determined by determining the mass of a section of a layer of adhesive of this kind applied to a carrier, the section being defined in terms of its length and its width, and subtracting the (known or separately ascertainable) mass of a section of the carrier used that has the same dimensions.

[0197] The thickness of a layer of adhesive can be determined by determining the thickness of a section of such a layer of adhesive, applied to a carrier, that section being defined in terms of its length and its width, and subtracting the (known or separately ascertainable) thickness of a section of the carrier used that has the same dimensions. The thickness of the layer of adhesive can be determined using commercial thickness gauges (sensor instruments) with accuracies of less than 1 m deviation. Where fluctuations in thickness are found, the mean value of measurements at not less than three representative sites is reported, hence in particular not including measurement at wrinkles, creases, nibs, and the like.

Coatweight

[0198] The coatweight of a PSA layer in g/m.sup.2 can be determined by determining the mass of a section of a layer of adhesive of this kind applied to a carrier, the section being defined in terms of its length and its width, and subtracting the (known or separately ascertainable) mass of a section of the carrier used that has the same dimensions.

Thickness

[0199] Like the thickness of the layer of adhesive already, the thickness of a pressure-sensitive adhesive strip or of a carrier may also be ascertained using commercial thickness gauges (sensor instruments) with accuracies of less than 1 m deviation. Where fluctuations in thickness are found, the mean value of measurements at not less than three representative sites is reported, hence in particular not including measurement at wrinkles, creases, nibs, and the like.

180 Peel Adhesion Test

[0200] The peel strength (peel adhesion) is tested in a method based on PSTC-1.

[0201] An adhesive tape in the form of a strip 0.5 cm wide, consisting of (i) a PET film 23 m thick and etched with trichloroacetic acid, and (ii) a pressure-sensitive adhesive strip applied to said film, in the form of a double-sided adhesive tape as described in the present patent application, is bonded to the test substrate in the form of an ASTM steel plate, the surface of which has been cleaned with acetone beforehand, by rolling down the tape back and forth five times using a 4 kg roller. The plate is clamped in and the adhesive tape is removed via its free end on a tensile testing machine with a velocity of 300 mm/min and at a peel angle of 180 from the plate, and the force required to achieve this is determined. The results of measurement are reported in N/cm (i.e. normalized to the width of the adhesive tape) and are averaged from three measurements.

Solids Content

[0202] The solids content is a measure of the fraction of unevaporable constituents in a PSA. It is determined gravimetrically, by weighing the PSA, then evaporating off the evaporable fractions in a drying cabinet at 120 C. for 2 hours, and weighing the residue.