Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Adhesive outermost layer
Reexamination Certificate
1999-02-19
2002-08-13
Zirker, Daniel (Department: 1771)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Adhesive outermost layer
C428S343000, C428S346000, C428S3550RA, C442S150000, C442S151000, C427S208200, C427S208400
Reexamination Certificate
active
06432529
ABSTRACT:
The invention relates to a non-fogging adhesive tape and to its use.
The test in accordance with DIN 75 201 is used to determine the fogging behaviour of materials used in the interior of motor vehicles. Using this method it is also possible to determine the fogging behaviour of liquid, pastelike, pulverulent and solid raw materials, of which the abovementioned materials consist or from which they are produced.
According to the Standard, fogging describes the condensation of evaporated volatile constituents from the interior trim of the motor vehicle onto the windows and especially the windscreen. Under adverse lighting conditions, the fogging may impair the view through the windscreen.
The fogging number F according to DIN 75 201 is the quotient, in per cent, of the 60°-reflectometer reading of a glass plate with fogging and the 60°-reflectometer reading for the same glass plate without fogging.
The condensable component G is the difference obtained from weighing an aluminium foil with and without fogging.
There follows a brief description of the methods used to measure the fogging number.
Method A
The specimen or sample is placed at the bottom of a spoutless glass beaker (referred to below simply as beaker) of defined dimensions.
The beaker is covered with a glass plate on which volatile constituents from the sample specimen or sample are able to condense. This glass plate is cooled.
The beaker prepared in this way is placed for three hours in a bath thermostatted to a test temperature of (100±0.3)° C.
The effect of the fogging on the glass plate is detected via the measurement of the 60° reflectometer values. The reference used is the 60° reflectometer readings for the same glass plate without fogging, this glass plate having been carefully cleaned prior to the test.
Method B
The specimen or sample is placed at the bottom of a spoutless glass beaker (referred to below simply as beaker) of defined dimensions.
The beaker is covered with an aluminium foil on which volatile constituents from the sample specimen or sample are able to condense. This aluminium foil is cooled.
The beaker prepared in this way is placed for 16 h in a bath thermostatted to a test temperature of (100±0.3)° C.
The mass of the fogging deposit on the aluminium foil is determined quantitatively by weighing the foil before and after the fogging test.
The precise procedure for the tests, together with the test apparatus to be used, is set out in detail in DIN 75201. The content of that Standard is therefore included in the disclosure content of this document by reference.
Determining the fogging behaviour is becoming increasingly important in the automotive industry, because the customer's desire from an ecological standpoint is increassingly to have raw materials in the vehicle which do not give rise to any health hazard.
In addition, such procedures lend themselves very well to exploitation for marketing purposes.
In the motor vehicle industry as well, there are numerous test methods for determining the fogging behaviour. All of these test methods are set down in internal works standards, although these are based to a greater or lesser extent on DIN 75201. Hence, in accordance with Volkswagen AG Central Standard PV 3015, 55 11 6 “Non-metallic materials of the interior trim; determination of condensable components (G)”, first published March 1989, the fogging condensate value of materials of the interior vehicle trim is determined by measuring the condensable component as the difference obtained from weighing an aluminium foil with and without a fogging deposit. Volvo, in turn, in accordance with Corporate Standard STD 1027,2711, published August 1994, determines the fogging number by comparing a clean glass plate (degree of light transmission 100%) with a plate covered by outgassed material (degree of light transmission less than 100%). Also known is the Ford Laboratory Test Method (BO 116-03), published May 14, 1990, which likewise measures the outgassed deposit of a test specimen on a plate. All of the documents mentioned and available to the public are incorporated by reference into the disclosure content of this invention.
One segment of those parts of a motor vehicle that are to be tested for fogging behaviour is represented by self-adhesive tapes, which are used, for example, to bandage cable harnesses.
In the cable industry, the use of self-adhesive tapes is widespread. Depending on the task at hand and the field of use, articles with a woven, with a nonwoven or with films of different materials are employed. The coating of these backings with pressure-sensitive self-adhesive compositions is known. From experience, both solvent compositions and hotmelt compositions based on synthetic or natural rubber with tackifier resins and, optionally, fillers are employed here. This type of adhesive tape is installed in all regions of the motor vehicles (for example, engine compartment or interior). A disadvantage affecting all the known articles is the evaporation of volatile constituents on heating. In the interior of the motor vehicles, this process results in a covering on the windows, such that an impairment of the view is classified as a safety risk. In the automotive industry, as already indicated above, this process of evaporation is termed “fogging”.
Furthermore, double-sided adhesive tapes based on acrylate adhesive compositions have been known for a long time. For products having a balanced profile of properties, acrylate polymers prepared in solution are mostly employed. The advantage of this procedure is
a) by way of controlled monomer compositions, to tailor the properties of the composition to meet certain profiles of properties;
b) by way of the selection of suitable preparation parameters, to establish desired molecular weights.
In the light of the issue of highly volatile constituents, however, these compositions all have marked disadvantages:
a) Unless the drying operation has been excellent, adhesive tapes prepared with these compositions generally have solvent residues of greater than 1% by weight, which are emitted to the environment over the course of time. When sensitive backings are employed, or with thick layers of composition, 100% drying is virtually impossible. Furthermore, with these compositions—and especially when they are applied in thick layers—insufficient drying results in residual contents of unreacted monomers.
b) The polymers prepared by standardized polymerization processes, moreover, have relatively broad molecular mass distributions. As a result, the low molecular mass constituents in particular tend to evaporate out.
U.S. Pat. No. 5,681,654 (“Low-fogging pressure-sensitive adhesive”) describes a low-fogging self-adhesive tape. As the adhesive, it is proposed to use a rubber composition whose crosslinking system is based on sulphur. Especially in the context of cable bandaging, this tape also does not protect against interactions with the PVC core insulation. The adhesive tape is not non-fogging but only low-fogging.
The invention is based on the object of providing a non-fogging self-adhesive tape which does not have the disadvantages of the prior art, or at least not to the same extent, and yet is not restricted in its usefulness like the products known to date.
To achieve this object, the invention proposes a non-fogging self-adhesive tape comprising a non-fogging backing to at least one side of which a non-fogging, pressure-sensitive adhesive composition has been applied.
Backings employed here are preferably wovens, nonwovens, films, paper, felts, foams and coextrudates.
As the adhesive composition it has also proved advantageous to use one based on an acrylate hotmelt which has a K value of at least 20, in particular more than 30 (measured in each case in 1% strength by weight solution in toluene, 25° C.), obtainable by concentrating a solution of such a composition to give a system which can be processed as a hotmelt. Concentration can be carried out in appropriately equipped vessels or extruders; in the case of the associated degassing, parti
Dietz Bernd
Ganschow Frank
Harder Christian
Kummer Andreas
Sievers Jürgen
Norris & McLaughlin & Marcus
tesa AG
Zirker Daniel
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