One-component or two-component reactive adhesive

Details One-component or two-component reactive adhesive One-component or two-component reactive adhesive

1997-03-03

1999-10-05

Dawson, Robert

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Cellular products or processes of preparing a cellular...

5262181, 5262196, C08J 902

Patent

active

059625406

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

This invention relates to a one-component or two-component reactive adhesive, to its production and to its use.


BACKGROUND OF THE INVENTION

Low-viscosity to medium-viscosity adhesives, for example Sicomet 85, Sicomet 77, omniFit 15 M and omniFit 200 M, are used for bonding substrates with narrow to medium-sized gaps (0.01 to 0.2 mm), according to the particular requirements and the material classification. These adhesives have a Brookfield viscosity of up to about 1,000 mPas at 20.degree. C. They are eminently suitable for filling the entire gap, particularly when the parts to be bonded are fitted together before application of the adhesive and good capillary effects are required for completely wetting the entire substrate surfaces. Where relatively large gaps (0.2 to 2 mm) or spaces are to be bridged or filled, high-viscosity or thixotropicized adhesives with gap-bridging properties (for example metallon FL and Stabilit express) are used. The viscosity of metallon FL is 110,000 to 120,000 mPas for the binder and 15,000 to 30,000 for the hardener (see Henkel KGaA's technical information sheet on "Sicomet/omniFit"). In view of the high viscosity or limited capillary effects, substrates which have already been fitted together with relatively large gaps are difficult or impossible to bond by subsequent application of adhesive.
The adhesives mentioned above are unsuitable for bonding substrates which have already been fitted together both with small and with relatively large gaps or spaces in between either because of inadequate capillary effects or incomplete wetting of the substrate surfaces or through the absence of gap-bridging or space-filling properties.
Against the background or this prior art, the problem addressed by the present invention was to provide low-viscosity to medium-viscosity reactive adhesives with gap-bridging or space-filling adhesive properties.


SUMMARY OF THE INVENTION

The solution provided by the invention is defined in the claims, lying essentially in a one-component or two-component reactive adhesive which becomes porous on curing.


DETAILED DESCRIPTION OF THE INVENTION

The viscosity of the reactive adhesive before curing is below 10, preferably below 2 and more preferably below 0.5 Pa.s at 20.degree. C., as measured with a Physica cone/plate viscosimeter (DIN 54453). It is preferably above 1 mPas.
The porosity of the cured adhesive is at least 3% by volume, preferably at least 10% by volume and more preferably at least 20% by volume. Porosity is determined by pouring the liquid adhesive into a test tube and measuring the height of the column of liquid. The adhesive is then cured, for example by heating. After curing, the height of the now solid adhesive in the test tube is determined. The difference between the height thus determined and the starting height is a measure of the porosity of the adhesive.
The pore system is produced by adding a blowing agent to the reactive adhesive. A blowing agent in the context of the invention is understood to be a substance which forms a gas during the curing process. In order to guarantee a relation between curing and the formation of a gas, the blowing agent should simultaneously be an initiator or catalyst for the curing reaction. The blowing agent may be mixed with the other components of the adhesive long before it is used (one-component adhesive). However, it may also be added shortly before the basic mixture is used, best in powder form (two-component adhesive). One example of such a substance is azo-bis-isobutyronitrile (AIBN). On heating, azo-bis-isobutyronitrile decomposes into nitrogen, which forms the pore system, and radicals which initiate the polymerization, for example of acrylates. Surprisingly, foamed cured adhesive polymers are thus obtained. Different quantities of gas bubbles or voids are obtained according to the curing temperature and the concentration of the blowing agent. It may be useful in some cases to add foam stabilizers.
The basic mixture of the reactive adhesive is preferably based o

REFERENCES:
patent: 3579163 (1971-05-01), Cronin
patent: 3986253 (1976-10-01), Harris
patent: 4439600 (1984-03-01), Moran
patent: 4695596 (1987-09-01), Berkowitz
patent: 4918119 (1990-04-01), Seltman et al.
patent: 5252617 (1993-10-01), Werner et al.
CA 941495, Feb., 1974.

Affiliated with

Also associated with

Rating

One-component or two-component reactive adhesive does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with One-component or two-component reactive adhesive, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and One-component or two-component reactive adhesive will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1172269