IES80901B2

IES80901B2 - A printing ink

Info

Publication number: IES80901B2
Authority: IE
Inventors: Milo Slattery; James Lacey; John Downing
Original assignee: Inx Res & Dev Ltd
Priority date: 1998-07-17
Filing date: 1998-07-17
Publication date: 1999-06-16
Also published as: IES980580A2; GB2339786B; GB9816247D0; GB2339786A

Description

A printing ink This invention relates to a printing ink and to a process for preparing a printing ink.

More particularly, the invention relates to the preparation of a printing ink for printing on envelope blanks. Printing on envelopes is becoming increasingly more common. Printing is provided on an inside of the envelope to make the envelope opaque. Printing is also increasingly provided on an exterior of an envelope, typically with some type of advertisement. An envelope often provides the first point of contact between a company and customers and for this reason, use of advertising on envelopes is increasing. However, it is important to create a good impression and it is therefore essential to have a good quality design printed on the envelope. This presents a problem in that, generally speaking, for the production of envelopes, relatively poor quality paper is used and the blank or web used to produce the envelope is often relatively thin. Thus, when the blank or web is wetted, it tends to curl and distort. For this reason, to produce good designs on the envelopes, it is usually necessary to use more expensive, better quality and thicker paper. Even then, the distortion caused by curling may restrict the quality of the design printed on the envelope. Many envelope printing inks are solvent base dye based inks. Water based inks allow better print quality to be achieved as the dye is solubilised. However, significant curling problems can arise with water based inks.

The present invention is directed towards overcoming these problems.

B.-tSTT'T» S 8 09 01 - 2 According to the invention, there is provided a printing ink comprising an emulsion based acrylic varnish, the varnish being neutralised to render the varnish water miscible, the varnish being combined with a dispersion colour and one or more conditioning additives and an anticurl agent, the anti-curl agent being either urea or a glycol ether.

In another embodiment, the varnish is an acrylic polymer having a low tg in the range -23°C to 5°C.

In a further embodiment, the varnish is a colloidal acrylic emulsion having an MFT in the range 1O-2O°C.

According to another aspect of the invention, there is provided a process for preparing a printing ink, comprising the steps preparing an emulsion based acrylic varnish which is neutralised to render it water miscible, adding a dispersion colour to the varnish, together with one or more conditioning additives and mixing the varnish, dispersion colour and additives to form a varnish mixture, and adding an anti-curl agent to the varnish mixture to produce the printing ink, the anti-curl agent being either urea or a glycol ether.

In one embodiment, the varnish is an acrylic polymer having a low tg (glass transition temperature) in the range -23°C to 5°C.

In another embodiment, the varnish is a colloidal acrylic emulsion having an MFT (minimum film forming temperature) in the range 10-20°C.

In a further embodiment, the conditioning additives 5 include a wax, an antifoam agent and water.

In another embodiment, the process includes the step of neutralising the emulsion based acrylic varnish with triethylaminoethanol.

It is envisaged that, if desired, two base varnishes may be provided - one associated with exterior printing and the other associated with interior printing. A selected dispersion colour could subsequently be added to either base varnish when required to produce printing ink of a desired colour.

In another aspect, the invention provides a printing ink base varnish and process for producing the base varnish.

The process comprises the steps :preparing an emulsion based acrylic varnish which is neutralised to render it water miscible, adding one or more conditioning additives to the varnish and mixing the varnish and additives to form a varnish mixture, adding an anti-curl agent to the varnish mixture to produce the base varnish, the anti-curl agent being either urea or a glycol ether.

In a further embodiment, the varnish is a colloidal acrylic emulsion having an MFT in the range 10-20°C.

In another embodiment, the conditioning additives include a wax, an antifoaming agent and water.

The invention will be more clearly understood by the following description of some embodiments thereof, given by way of example only.

Example 1 wt. % Varnish 46-51 Dispersion colour 5-10 Wax 3 Antifoam 1 Water 10 Urea 30 The varnish, dispersion colour, wax, antifoam and water are mixed together. The urea is subsequently added and mixed with the other ingredient materials to form an homogenous printing ink of the invention.

Preferably the varnish is an acrylic polymer having a low tg in the range -23°C to 5°C.

This ink is particularly useful for printing on a blank face which forms an inside of an envelope without any unacceptable curling of the blank after application of the ink.

Example 2 Varnish Glycol ether Antifoam Wax Dispersion colour wt. % 40-44 46-50 The varnish is prepared as follows :wt. % Triethylaminoethanol 5 Antifoam 1 Colloidal acrylic emulsion 55 Water 36 Triethylene glycol 3 The above-mentioned ingredient materials are mixed to form the varnish. The triethylaminoethanol neutralises the emulsion and the triethylene glycol assists in retarding drying of the ink. The colloidal acrylic emulsion preferably has an MFT in the range 10-20°C and a solids content in the range 40-50%. The varnish produced is then mixed together with the antifoam, wax and dispersion colour. The glycol ether is subseguently added and mixed with the other ingredient materials to form an homogenous printing ink of the invention.

This printing ink is particularly useful for printing on a blank surface which will form an exterior of an envelope. It has been found to give a high quality printing definition even for relatively complex designs, while at the same time the blank or web onto which the ink is printed in use accepts the ink without undue curling or distortion of the blank or web.

The invention is not limited to the embodiments hereinbefore described which may be varied in both construction and detail.

Claims

1. A printing ink comprising an emulsion based acrylic varnish, the varnish being neutralised to render the varnish water miscible, the varnish being combined 5 with a dispersion colour and one or more conditioning additives and an anti-curl agent comprising either urea or a glycol ether.

2. A printing ink substantially as hereinbefore described with reference to the examples. 10

3. A process for preparing a printing ink comprising the steps : preparing which is miscible, an emulsion neutralised based acrylic varnish to render it water adding a dispersion colour to the varnish, together with one or more conditioning additives and mixing the varnish, dispersion colour and additives to form a varnish mixture, and adding an anti-curl agent to the varnish mixture to produce the printing ink, the anti-curl agent being either urea or a glycol ether.

4. A process for preparing a printing ink substantially as hereinbefore described with reference to the examples . 25

5. A printing ink whenever produced by the process as claimed in claim 3 or 4.