Polyurethane PSA for sensitive surfaces

Active Publication Date: 2006-08-15
TESA SE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0033]It is an object of the invention to provide a pressure-sensitive adhesive which adheres well to polar plastics surfaces and smooth metal surfaces and also to glass, which in particular is easy to remove, without damaging surfaces during its detachment, particularly when the surfaces are sensitive to mechanical influences, and which does not display the above-described drawbacks of the p

Problems solved by technology

Although polyurethanes occupy position five in the list of plastics, in terms of the amounts produced, PSAs of this material play only a very minor role economically.
PSAs of this kind generally have the drawback of not attaching selectively only to certain surfaces.
Moreover, following a prolonged period of bonding, they unite—usually strongly—with the surfaces and therefore often cannot be removed.
A drawback is the oxidative sensibility of these PSAs, caused by the double bonds in the polymer main chain.
In addition the majority of PSAs of this type additionally contain resins, with the disadvantages already described earlier on above.
The compositions, however, are moisture-curing, consequently obtain a high ultimate cohesive strength and cannot be used more than once, so that they are unsuitable for reversible adhesive bonding of paper.
A drawback there is the need for electron beam crosslinking, which involves a considerable level of technical complexity.
These PSAs generally feature a heightened tack and are therefore difficult to remove from sensitive substrates without damaging them.
In principle, as a result of the enlargement of surface area, foamed polyurethanes have the drawback of a heightened oxidative sensitivity and also of a heightened light sensitivity.
In practice it has been found that they exhibit strong peel increase on the majority of surfaces and either cannot be removed without damage or else, particularly in the case of the foams made hydrophilic by additions of superabsorbent, interact with the sub

Method used

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  • Polyurethane PSA for sensitive surfaces

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0098]The composition of the inventive polyurethane PSA is as follows:

[0099]

NCO / OH ratio: 1.02Ratio of number of diol OH / number of triol OH: 1.5Number of OH orWeightNCO groupsfractionbased on the[% bypercentage weightIngredientweight]fractionA componentDesmophen 1262 BD ®12.156.3 mmol OHAcclaim 6320 N ®75.137.5 mmol OHBismuth0.3trisneodecanoateTinuvin 292 ®0.3Tinuvin 400 ®0.6Aerosil R202 ®1.0B componentVestanat IPDI ®10.695.7 mmol NCO

[0100]The test specimens (50 g / m2 polyurethane PSA on 26 μm polyester film; see above) achieved the following bond strengths:[0101]0.15 N / cm on steel,[0102]0.23 N / cm on ABS,[0103]0.36 N / cm on PS,[0104]0.41 N / cm on PVC.

[0105]The tack measurement (on steel) gave a figure of 0.4 N. After two weeks of irradiation with the sunlight lamp there were no changes, either in colour or in bond strength. The adhesion to paper and paperboard was extremely low. The PSA was removable from the substrates simply by shaking. The PSA was stuck into a number of b

example 2

[0106]The composition of the inventive polyurethane PSA is as follows:

[0107]

NCO / OH ratio: 1.02Ratio of number of diol OH / number of triol OH: 1.5Number of OH orWeightNCO groupsfractionbased on the[% bypercentage weightIngredientweight]fractionA componentDesmophen 1262 BD ®12.357.4 mmol OHAcclaim 6320 N ®76.638.3 mmol OHBismuth0.3trisneodecanoateB componentVestanat IPDI ®10.897.6 mmol NCO

[0108]The test specimens (50 g / m2 polyurethane PSA on 26 μm polyester film; see above) achieved the following bond strengths:[0109]0.17 N / cm on steel,[0110]0.22 N / cm on ABS, 0.31 N / cm on PS,[0111]0.44 N / cm on PVC.

[0112]The tack measurement (on steel) gave a figure of 0.4 N. After two weeks of irradiation with the sunlight lamp there were no changes, either in colour or in bond strength. After two weeks of irradiation there were no colour changes, but the inherent tack was now distinctly perceptible. The bond strength (on steel) was now 1.6 N / cm.

[0113]The adhesion to paper and paperboard w

example 3

[0114]The composition of the inventive polyurethane PSA is as follows:

[0115]

NCO / OH ratio: 1.02Ratio of number of diol OH / number of triol OH: 2.5Number of OH orWeightNCO groupsfractionbased on the[% bypercentage weightIngredientweight]fractionA componentDesmophen 1262 BD ®17.9 83.3 mmol OHAcclaim 6320 N ®66.7 33.3 mmol OHBismuth0.3trisneodecanoateTinuvin 292 ®0.3Tinuvin 400 ®0.6Aerosil R202 ®1.0B componentVestanat IPDI ®13.2119.0 mmol NCO

[0116]The test specimens (50 g / m2 polyurethane PSA on 26 μm polyester film; see above) achieved the following bond strengths:[0117]0.19 N / cm on steel,[0118]0.25 N / cm on ABS,[0119]0.47 N / cm on PS,[0120]0.53 N / cm on PVC.

[0121]The tack measurement (on steel) gave a figure of 0.5 N. After two weeks of irradiation with the sunlight lamp there were no changes, either in colour or in bond strength. The adhesion to paper and paperboard was extremely low. The PSA was removable from the substrates simply by shaking. The PSA was stuck into a number o

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Abstract

Polyurethane-based pressure-sensitive adhesive which attaches strongly to polar plastic surfaces, smooth metal surfaces and glass, but which has weak, if any, adhesion to paper, paperboard or skin and is easily detachable without damaging surfaces during its removal, and is reusable. The adhesive comprises a polyurethane formed by reacting an aliphatic or alicyclic polyisocyanate having a functionality of equal to or less than three with a combination of diol and triol.

Description

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Claims

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Application Information

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Owner TESA SE
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