Archive for the ‘Newsletters’ Category

Environmentally Aware Printing – Types of Adhesives (continued)

Wednesday, March 10th, 2010

Environmentally Aware Printing – Types of Adhesives (continued) – 11th March 2010
d) Reactive hot melts adhesives

Undoubtedly one of the most likely technologies to have an impact in the replacement of solvent-based products and recyclability in general is that of reactive hot melt adhesives.

Conventional hot melts are made of relatively low molecular weight thermoplastic materials, to ensure melting and application at moderate temperatures. This leads to obvious limitations with heat resistance and strength which can be exploited in the high temperature, high shear repulping process giving rise to small average particle size.

To overcome this, moisture-curing polyurethane hot melts have been developed utilising a cross-linking reaction which raises heat resistance and strength to previously unattainable levels whilst maintaining flexibility and low temperature adhesion. This unusual blend of properties makes this type of product ideal for recycling purposes since the high cohesive strength and excellent flexibility allows the product to remain intact rather than deforming/ breaking down under heat and shear to be forced through screens or shattering as a hard, highly cohesive conventional hot melt might.

Laboratory work on these products suggests that the adhesive does indeed remain as a discrete film and is filtered out completely in the process. These laboratory results have been borne out in typical recycling mills where complete spines of directories/ books have been removed at the first coarse screening stage, with no trace of the adhesive further down the line.

This approach is gaining in mills from a safety viewpoint since there is little or no chance of adhesive contamination in the papermaking process. The technique obviously still involves disposal of the rejected adhesive, probably in landfill, but the amount compared with conventional hot melts is halved.

To be continued…

Peter Harrison is Joint Managing Director of The Printing House Ltd, and Print Buying Direct of Crewe, Cheshire, UK.

NEW: We now sell Large Poster Printing and Banner printing online (A1 Posters, A0 Posters etc) and Banner Stands

Also – checkout our new online print prices Print Buying Direct are UK market Leaders in Leaflet Printing | Brochure Printing. For more free articles on Printing and Graphic Design see our Online Printing | Print Buying Direct Website. For more information on printing and graphic design please see some of our recent blog articles;

Print Buying Direct is the online division and a Trading Name of The Printing House Ltd. One of the UK’s leading quality printing companies for graphic design, short run, long run and large format colour printing. Based in Crewe, Cheshire (Cheshire Printers), in the North West of England – delivering to customers across the UK and Ireland.

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Environmentally Aware Printing – Types of Adhesives (continued)

Monday, March 8th, 2010

Environmentally Aware Printing – Types of Adhesives (continued) – 9th March 2010
C) Water-dispersible hot melt polymers

A wealth of literature exists describing supposedly water-dispersible or soluble polymers which can be used as adhesive bases for a range of market applications. Polymers such as functionalised polyesters, acrylic acid homopolymers/ copolymers, vinyl methyl ethers, maleic anhydride/ acids, polyvinyl alcohols and vinyl-pyrolidone copolymers are among those investigated, but such polymers from inherent problems which are usually related to the thermal and oxidative stability of the product during manufacture/ application and/ or the water sensitivity/ humidity resistance of the glue film when applied. Obviously, poor humidity resistance could give rise to a rapidly degradable spine if used in a bookbinding application.

To overcome these problems, patented technology has emerged where hot melt adhesives are based on a unique class of graft copolymers of various vinyl monomers. These products can be considered as dispersible in the mill system under shear; pH and temperature but remain stable to moisture at ambient temperatures.

Rather than forming tacky agglomerates and therefore stickies, the finely divided particles of the vinyl graft copolymer-based hot melt may then become incorporated into the reclaimed paper without any adverse effects.

To be continued…

Peter Harrison is Joint Managing Director of The Printing House Ltd, and Print Buying Direct of Crewe, Cheshire, UK.

NEW: We now sell Large Poster Printing and Banner printing online (A1 Posters, A0 Posters etc) and Banner Stands

Also – checkout our new online print prices Print Buying Direct are UK market Leaders in Leaflet Printing | Brochure Printing. For more free articles on Printing and Graphic Design see our Online Printing | Print Buying Direct Website. For more information on printing and graphic design please see some of our recent blog articles;

Print Buying Direct is the online division and a Trading Name of The Printing House Ltd. One of the UK’s leading quality printing companies for graphic design, short run, long run and large format colour printing. Based in Crewe, Cheshire (Cheshire Printers), in the North West of England – delivering to customers across the UK and Ireland.

See our other websites The Printing House, Print Buying Direct, Prospectus printing, Golf Club Centenary Books

See Our Latest Press Release about our Web to Print Solution.

Environmentally Aware Printing – Types of Adhesives – part 3

Sunday, March 7th, 2010

Environmentally Aware Printing – Types of Adhesives – part 3 – 8th March 2010

3. Hot melts

a)    EVA-based hot melts.

Hot melt adhesives based on conventional synthetic polymers such as ethylene vinyl acetate (EVA) represent a potentially significant source of contamination in the recycling process. Such adhesives generally soften and partially disintegrate but do not disperse under the influence of temperature and shear. Contamination can originate from anywhere in the adhesive composition, i.e. polymer, wax, pigment, plasticiser or resin.

These EVA-based hot melts are removed reasonably efficiently by modern mill systems, indeed in some cases relatively soft, low melting point adhesives can be used without problems due to the effectiveness of the screening, cleaning and dispersing systems.

Unfortunately, in many mills which have limited cleaning capacity and/or a high attrition pulping phase, small particles of adhesives can find their way into the high finished product already described. An interesting and somewhat disturbing thought is that less than 1kg of adhesives can totally ruin over 100 tonnes of stock unless adequate precautions are taken.

Acceptability standards for conventional hot melts vary widely in different countries and within different mills.  This is related to be varying mill systems and wide range of difficult test employed. Requirements and standards also differ depending on whether paper recycling or board recycling is the issue.

Higher cohesive strength EVA-based hot melts are available which optimise the strength/ flexibility balance in order to maximise filterability and minimise risk of stickie contamination but these will only really be effective in low attrition systems.

b)    Acrylic/ pressure sensitive adhesive systems

As previously stated, the term ‘stickies’ was originally used to refer to pressure sensitive adhesives in the papermaking process. In one sense these types of materials have the potential to cause significant problems in that they are likely to be permanently tacky (if they remain intact) and do not need heat reactivation. Having said this, most of the methods described for removal of conventional EVA hot melts can also be applied to pressure sensitive adhesives (PSA), i.e. chemical and/ or mechanical treatment.

Work has shown that if the PSA product has the right balance of cohesive strength and flexibility, then screening is relatively simple, as with EVA based products. Both high-cohesive, cross-linked (by radiation curing) and water-dispersible PSA products have been developed which are potentially beneficial to the recycling process.

Peter Harrison is Joint Managing Director of The Printing House Ltd, and Print Buying Direct of Crewe, Cheshire, UK.

NEW: We now sell Large Poster Printing and Banner printing online (A1 Posters, A0 Posters etc) and Banner Stands

Also – checkout our new online print prices Print Buying Direct are UK market Leaders in Leaflet Printing | Brochure Printing. For more free articles on Printing and Graphic Design see our Online Printing | Print Buying Direct Website. For more information on printing and graphic design please see some of our recent blog articles;

Print Buying Direct is the online division and a Trading Name of The Printing House Ltd. One of the UK’s leading quality printing companies for graphic design, short run, long run and large format colour printing. Based in Crewe, Cheshire (Cheshire Printers), in the North West of England – delivering to customers across the UK and Ireland.

See our other websites The Printing House, Print Buying Direct, Prospectus printing, Golf Club Centenary Books

See Our Latest Press Release about our Web to Print Solution.

Environmentally Aware Printing – Types of adhesives – part 2

Thursday, March 4th, 2010

Environmentally Aware Printing – Types of adhesives – part 2 – 5th March 2010

2. Animal glue

Animal based adhesives have been used reasonably successfully for some time in the bookbinding industry and in recent times have been favoured on the grounds of water solubility. This type of adhesive suffers from inherent problems which are of significance to both the converter and the mill.

Relatively slow production speeds, limited moisture and heat stability capital outlay for specialised equipment are not attractive to the binders. Problems for the mill are related to the fact that the adhesive is effectively a protein which will have a high biological oxygen demand (BOD). This will have an adverse affect on bacteria in effluent disposal systems.

Another factory worth mentioning, which is sometimes overlooked, is that of ethnic minority and animal rights groups who abhor the use of animal by products.

Peter Harrison is Joint Managing Director of The Printing House Ltd, and Print Buying Direct of Crewe, Cheshire, UK.

NEW: We now sell Large Poster Printing and Banner printing online (A1 Posters, A0 Posters etc) and Banner Stands

Also – checkout our new online print prices Print Buying Direct are UK market Leaders in Leaflet Printing | Brochure Printing. For more free articles on Printing and Graphic Design see our Online Printing | Print Buying Direct Website. For more information on printing and graphic design please see some of our recent blog articles;

Print Buying Direct is the online division and a Trading Name of The Printing House Ltd. One of the UK’s leading quality printing companies for graphic design, short run, long run and large format colour printing. Based in Crewe, Cheshire (Cheshire Printers), in the North West of England – delivering to customers across the UK and Ireland.

See our other websites The Printing House, Print Buying Direct, Prospectus printing, Golf Club Centenary Books

See Our Latest Press Release about our Web to Print Solution.

Environmentally Aware Printing – Types of adhesives – part 1

Thursday, March 4th, 2010

Environmentally Aware Printing – Types of adhesives – part 1 – 4th March 2010
Adhesive technologies in use within the printing industry can be broadly classified into the following groups for the purposes of this discussion:

  1. Aqueous/ emulsions e.g. PVA, dextrine, starch, latex, PVOH etc.
  2. Animal glue – water soluble
  3. Hot melts
  1. a)    EVA based.
  2. b)    Acrylic/ pressure sensitive’s.
  3. c)    Water-disperible hot melts polymers.
  4. d)    Reactive systems.

1.    Aqueous systems

The need for recyclability centres mostly around polyvinyl acetate (PVA) emulsions, the other categories generally being considered as repulpable.  Currently, PVA is treated using one or several of the techniques already described to inhibit the formation of stickies.

Patented technology is, however, available which allows vinyl acetate homopolymers and copolymer-based emulsion adhesives to become almost totally water-dispersible. This is achieved by the addition of specific water soluble ionic salts, such as magnesium chloride.

To be continued…

Peter Harrison is Joint Managing Director of The Printing House Ltd, and Print Buying Direct of Crewe, Cheshire, UK.

NEW: We now sell Large Poster Printing and Banner printing online (A1 Posters, A0 Posters etc) and Banner Stands

Also – checkout our new online print prices Print Buying Direct are UK market Leaders in Leaflet Printing | Brochure Printing. For more free articles on Printing and Graphic Design see our Online Printing | Print Buying Direct Website. For more information on printing and graphic design please see some of our recent blog articles;

Print Buying Direct is the online division and a Trading Name of The Printing House Ltd. One of the UK’s leading quality printing companies for short run, long run and large format colour printing. Based in Crewe, Cheshire (Cheshire Printers), in the North West of England – delivering to customers across the UK and Ireland.

Also see our other websites The Printing House, Print Buying Direct, Prospectus printing, Golf Club Centenary Books

See Our Latest Press Release about our Web to Print Solution

Environmentally Aware Printing – Dealing with the stickies problem Part 3

Monday, March 1st, 2010

Environmentally Aware Printing – Dealing with the stickies problem Part 3 – 2nd March 2010

Stickies which remain in the product can cause sheets adjoining layers in a reel to block together and can also cause problems during printing. This makes the finished products generally unacceptable for many printings and writings.

The cost of the problems caused by stickies is very difficult to quantify accurately, but it is certain that this cost will increase as the waste paper convent in the mill is increased, unless adequate measures are taken to prevent them occurring.

Removal of stickies within the paper mill system is based primarily on mechanical methods which exploit physical difference between the stickies and the fibres. Slotted pressure screens are employed to remove contraries in their first pass through the process if possible. Maintaining relatively large particle sizes here is important. If contraries are broken down to size of less then 0.15mm then they can pass through the smallest slots. This indicates that purely mechanical methods are unlikely to achieve 100% removal of contraries and that other techniques should also be employed.

Through-flow centrifugal cleaners are sometimes employed which are designed to reject material with specific gravity lower than the pulp suspension. In fact, work has indicated that a specific gravity window exists, within which removal is difficult. Outside this window it would appear separation of stickies is possible. It has been reported that this specific gravity range is from 0.98 to 1.05 for efficient removal. Flotation techniques, generally used in the de-inking process, have also proven beneficial. Collection of the ‘skimmed froth’ from dissolved air flotation units, and subsequent analysis has revealed quite high stickie concentrations of up to 20%.

Peter Harrison is Joint Managing Director of The Printing House Ltd, and Print Buying Direct of Crewe, Cheshire, UK.

NEW: We now sell Large Poster Printing and Banner printing online (A1 Posters, A0 Posters etc) and Banner Stands

Also – checkout our new online print prices Print Buying Direct are UK market Leaders in Leaflet Printing | Brochure Printing. For more free articles on Printing and Graphic Design see our Online Printing | Print Buying Direct Website. For more information on printing and graphic design please see some of our recent blog articles;

Print Buying Direct is the online division and a Trading Name of The Printing House Ltd. One of the UK’s leading quality printing companies for short run, long run and large format colour printing. Based in Crewe, Cheshire (Cheshire Printers), in the North West of England – delivering to customers across the UK and Ireland.

Also see our other websites The Printing House, Print Buying Direct, Prospectus printing, Golf Club Centenary Books

Environmentally Aware Printing – Dealing with the stickies problem Part 2

Sunday, February 28th, 2010

Environmentally Aware Printing – Dealing with the stickies problem – Part 2 – 1st March 2010

A number of factors, both chemical and physical, influence the solid. Colloidal content in the system. Increasing agitation during pulping will increase the colloidal particle concentration and reduce solid particle size, thus making effective screening more difficult. A similar situation may occur when pH is raised during the de-inking process.

Low attrition systems, utilising a much lower shear pulpling stage, will obviously favour products which can be effectively removed by screening. This type of system is commonly employed in the more modern European mills and is increasingly accompanied by a closed loop water recirculation system. These are becoming more prevalent as a result of tighter restrictions on disposal of contaminated water. Within the recirculation system problems with dispersed particle concentration may develop over a period of time causing saturation, agglomeration and possible formation of secondary stickies. In these cases, efficient screening of adhesive particles is preferred.

Stickies can potentially cause problems both at the wet end and dry of the paper machines where they may build up on forming fabrics, the press section, calendars, blades and drying cylinders. This leads to recued efficiency, web breaks and regular cleaning necessitating costly downtime.

Peter Harrison is Joint Managing Director of The Printing House Ltd, and Print Buying Direct of Crewe, Cheshire, UK.

NEW: We now sell Large Poster Printing online (A1 Posters, A0 Posters etc) and Banner Stands

Also – checkout our new online print prices Print Buying Direct are UK market Leaders in Leaflet Printing | Brochure Printing. For more free articles on Printing and Graphic Design see our Online Printing | Print Buying Direct Website. For more information on printing and graphic design please see some of our recent blog articles;

Print Buying Direct is the online division and a Trading Name of The Printing House Ltd. One of the UK’s leading quality printing companies for short run, long run and wide format colour printing. Based in Crewe, Cheshire, in the North West of England – delivering to customers across the UK and Ireland.

Also see our other websites The Printing House, Print Buying Direct, Prospectus printing, Golf Club Centenary Books

Environmentally Aware Printing – Dealing with the stickies problem – Part 1

Wednesday, February 24th, 2010

Environmentally Aware Printing

Dealing with the stickies problem – Part 1

Consumers and therefore the industry will not accept lowering of finished product standards and at the same time there is a clearly identified need to increase the waste/ virgin stock usage ratio. This means that dealing with contraries satisfactorily in recycling will become an increasingly important issue. As concentrations increase, control and removal efficiency of contraries must be improved in order to take advantage of the commercial opportunities presented.
The typical repulping mill will contain a vast array of contraries in the system and, certainly in the newer mills, an associated complex system of methods either to remove or minimise the effects of these impurities. It is fair to say that in many mills permanently high background levels of contraries exist, but these are known and controllable. This perhaps highlights the impact of non-adhesive entities such as pigments, fillers, plastic films etc. adhesives, however, in the form of ‘stickies’, still constitute the major problem in most mills.

Traditionally, the term stickies has been applied to permanently tacky pressure sensitive adhesives but has latterly encompassed all adhesives types which are considered reactivatible at elevated temperatures. In some cases the intrinsic tack of the adhesive may be non-existent or acceptably low, but complexed with components of other coatings and/ or chemical paper additives, the adhesives components may be chemically activated. Common constituents of adhesives and therefore stickies are ethylene vinyl acetate (EVA), polyvinyl acetate (PVA), acrylic and styrene containing polymers. Deposits will often contain rosin or rosin-based tackifying resins but it is not always clear whether it originates from the adhesives or waste paper fibres themselves.

If the stickie particles remain in the solid form during processing they are comparatively easy to deal with using the sophisticated screening systems of modern mills. However, if the particle is soluble or colloidal in nature, it becomes more difficult to handle.

Peter Harrison is Joint Managing Director of The Printing House Ltd, and Print Buying Direct of Crewe, Cheshire, UK.

NEW: We now sell Large Poster Printing online (A1 Posters, A0 Posters etc) and Banner Stands

Also – checkout our new online print prices Print Buying Direct are UK market Leaders in Leaflet Printing | Brochure Printing. For more free articles on Printing and Graphic Design see our Online Printing | Print Buying Direct Website. For more information on printing and graphic design please see some of our recent blog articles;

Print Buying Direct is the online division and a Trading Name of The Printing House Ltd. One of the UK’s leading quality printing companies for short run, long run and wide format colour printing. Based in Crewe, Cheshire, in the North West of England – delivering to customers across the UK and Ireland.

Also see our other websites The Printing House, Print Buying Direct, Prospectus printing, Golf Club Centenary Books

Environmentally Aware Printing – Definition of recyclability of Adhesives

Tuesday, February 16th, 2010

Environmentally Aware Printing – Definition of recyclability of Adhesives – 16th February 2010

For an adhesive to be truly recyclable is must either be:
(i)    Re-used completely – this requires the adhesive to be totally separated from fibres, re-formed and used again in a secondary application. Or
(ii)    Fully incorporated into the finished product- this implies that all the adhesives must travel through the mill system to give 100% retention on the fibres in finished paper.

A combination of (i) and (ii) may also be acceptable.

Currently as a result of technological limitations, the term recyclable is applied to adhesives which are dispersed or soluble in alkali or water or indeed, filterable in the pulping process.

In both cases adhesives must be removed from the system and disposed of. With dispersed or soluble adhesives, build-up and removal from the backwater system is the main problem, involving costly water treatment programmes. In the case of adhesives which are screened out during the process, screen rejects, usually attached to fibre, must be disposed of either in landfill sites or by incineration.

Whilst these approaches cannot be considered to produce a totally recyclable adhesive, they are certainly a step forward from the traditional problems with soft, tacky adhesives in mill systems. These approaches, one can say, allow the finished products to be recycled more effectively.

Other variables which must be considered when trying to produce a totally recyclability are mill systems and test methods. The wide range of different mills inevitably employs slightly different systems which can affect the ability to recycle certain materials with regards to handling contraries. Process variables such as pulping shear forces/ speeds, temperature, consistencies, pH, dispersion/ screening capabilities, de-inking processes and cleaner efficiency can have a major impact on the quality of the finished product and recycling efficiency in the mills. The bottom line here is that an adhesive which is acceptable to one mill may cause problems at other mills. This will become evident in subsequent sections.

Due to the complexity and variability of different mill systems, it is difficult to imagine how a standard test in the laboratory can be developed and validated. Many recyclability tests exist utilising both laboratory and small scale pilot plant equipment, but none really truly reflect the adhesives’ ability to be recycled since they cannot accurately simulate the whole mill treatment system. Tappi UM 666 is most widely quoted as an adhesive recycling test nevertheless this is still only a simplistic, laboratory scale test which can only be used as an initial guide or screening process. Currently, the only true test of a product’s recyclability is to run a full scale mill trial.

Development of a suitable standard test method is a project which industry research organisations, recycling mills and adhesive manufacturers must investigate if significant technical and economic advances are anticipated.

Peter Harrison is Joint Managing Director of The Printing House Ltd, and Print Buying Direct of Crewe, Cheshire, UK.

NEW: We now sell Large Poster Printing online (A1 Posters, A0 Posters etc) and Banner Stands

Also – checkout our new online print prices Print Buying Direct are UK market Leaders in Leaflet Printing | Brochure Printing. For more free articles on Printing and Graphic Design see our Online Printing | Print Buying Direct Website. For more information on printing and graphic design please see some of our recent blog articles;

Print Buying Direct is the online division and a Trading Name of The Printing House Ltd. One of the UK’s leading quality printing companies for short run, long run and wide format colour printing. Based in Crewe, Cheshire, in the North West of England – delivering to customers across the UK and Ireland.

Also see our other websites The Printing House, Print Buying Direct, Prospectus printing, Golf Club Centenary Books

Environmentally Aware Printing – Inks | Adhesives | Bookbinding adhesives

Monday, February 15th, 2010

Environmentally Aware Printing – Inks | Adhesives | Bookbinding adhesives - 15th February 2010

Requests from bookbinders and printers for spine adhesives that would not contaminate the waste from normal unsewn book production increased in 1990. Perhaps it was an attempt to maintain the selling price of the trimmed waste, but it also indicated that the waste collectors did not know what constituted a contaminant. By using the words ‘adhesives’ or ‘hot melts’, they were able to reduce the selling/ buying price of waste.

The green issued intensified as publishers stared to request products that were manufactured not only from recycled paper, but with a recycled adhesive. Confusion increased as bio or UV degradable was requested, with the caveat that books must still be able to withstand a long shelf life with increased library usage. In other words the market was, and it, totally confused.

The vast number of variables involved, the potential problems and the complexity of the different systems has meant no clear direction has been established, and everybody has different definitions and ideas on ‘recyclability’.

The term ‘recyclable’ is used frequently when referring to adhesives in paper conversion processes, but this is often somewhat misleading. It is therefore appropriate to briefly discuss a definition.

Peter Harrison is Joint Managing Director of The Printing House Ltd, and Print Buying Direct of Crewe, Cheshire, UK.

NEW: We now sell Large Poster Printing online (A1 Posters, A0 Posters etc) and Banner Stands

Also – checkout our new online print prices Print Buying Direct are UK market Leaders in Leaflet Printing | Brochure Printing. For more free articles on Printing and Graphic Design see our Online Printing | Print Buying Direct Website. For more information on printing and graphic design please see some of our recent blog articles;

Print Buying Direct is the online division and a Trading Name of The Printing House Ltd. One of the UK’s leading quality printing companies for short run, long run and wide format colour printing. Based in Crewe, Cheshire, in the North West of England – delivering to customers across the UK and Ireland.

Also see our other websites The Printing House, Print Buying Direct, Prospectus printing, Golf Club Centenary Books


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