Record receiver having plural interactive leaves or a colorless – Having a colorless color-former – developer therefor – or...
Patent
1990-10-15
1992-07-14
Schwartz, Pamela R.
Record receiver having plural interactive leaves or a colorless
Having a colorless color-former, developer therefor, or...
503207, 503226, B41M 5132
Patent
active
051302896
DESCRIPTION:
BRIEF SUMMARY
This invention relates to pressure sensitive record material and especially to such record material using base paper made using a particular combination of filler and sizing agent.
As is well known in the art, pressure sensitive record material typically functions by separating the colour reactive components by a pressure rupturable barrier. Most commonly this barrier is provided by microencapsulating a solution in a suitable organic solvent of one of the reactive components. On application of imaging pressure the microcapsules are ruptured, liberating the solution of one of the reactive components into reactive contact with the other component thereby forming a coloured mark or image corresponding to the applied imaging pressure. It is also known to use other forms of pressure rupturable barrier such as a dispersion of a solution in a waxy or other continuous layer or a honeycomb structure instead of microcapsules.
Most commonly, in pressure sensitive record material the reactive components are present in coatings on facing surfaces of upper and lower sheets, the coating on the lower surface of the upper sheet comprising the isolated and usually microencapsulated solution of electron donating chromogenic material and the coating on the upper surface of the lower sheet comprising the electron accepting coreactant.
Sheets carrying microencapsulated material on their lower surfaces are usually referred to as "CB" (coated back) sheets and the sheets carrying a reactive coating on their upper surfaces are usually referred to as "CF" (coated front) sheets. Intermediate sheets carrying both microencapsulated material and a reactive coating (on their opposed surfaces) are usually also provided, and these are usually referred to as "CFB" (coated front and back) sheets. In an alternative system, the microcapsules and the reactive material are carried within the paper as a loading.
The base paper used in the manufacture of such pressure sensitive record material (carbonless copying paper) is generally a conventional fine paper (apart from special grades on other bases).
The present invention addresses a problem which has been found to arise if the base paper is made using an acid sizing system. This problem, termed "base reactivity", manifests itself as an undesirable localised or general colouration of the base paper after application of microencapsulated chromogenic materials thereto. This colouration may arise immediately on contact with the microencapsulated chromogenic materials or at a later stage, and is thought to be due to one or more of the following factors: solution mixed with the microcapsules; use of the microcapsule coated paper; and of the sheet below when microcapsules are ruptured by imaging pressure. Hitherto, it had been assumed that the prime cause of base reactivity was the acidic nature of the alum used in acid sizing systems, since most chromogenic materials used in pressure sensitive record material are electron donating and hence develop colour in an acidic environment. Consequently, it had further been assumed that the choice of filler used in the base paper would not affect the base reactivity of the paper to a significant extent.
It has now surprisingly been found that the use of sulphate based fillers in place of the kaolin or other clay fillers used hitherto in acid sized base paper for pressure sensitive record material gives rise to substantially reduced base reactivity.
Sulphate salts of alkali earth metals, for example gypsum or blanc fixe have been proposed previously for use as papermaking fillers e.g. as described in TAPPI Monograph 19; "Paper Loading Materials", Chapter V, but the applicants are not aware of any previous disclosure or use of such fillers in base paper for pressure sensitive recording materials. The term "sulphate based filler" used herein means a filler which is a sulphate salt of an alkali earth metal.
Accordingly, the present invention provides pressure sensitive record material comprising an acid sized base paper carrying isolated droplets of a solution of c
REFERENCES:
patent: 2505470 (1950-04-01), Green
patent: 2505471 (1950-04-01), Green
patent: 3803074 (1974-04-01), Jenkins
patent: 4348234 (1982-09-01), Cespon
patent: 4422671 (1983-12-01), Cespon
patent: 4431213 (1985-02-01), Hofer et al.
Cooper John B.
Doman Tracey A.
Schwartz Pamela R.
The Wiggins Teape Group Limited
LandOfFree
Pressure sensitive record material does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Pressure sensitive record material, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Pressure sensitive record material will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-334616