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Re: [BKARTS] PVA



PVA is an extraordinarily versatile adhesive used
in a multitude of applications in a host of industries -
bookbinding, printing, packaging, woodworking,
electronics, and other types of manufacturing, as
well as being packaged for retail customer use
(e.g., Elmer's).

As reported below, its development arose out of
adhesive shortages during WW II.

Also noted is that formulations of PVA-based
adhesives include different types application-specific
additives suited to the specific needs of those
applications.

Bookbinding is one such application, having particular
requirements and requiring special types of additives
and formulations.

For hand bookbinding, we want an adhesive that :
flows smoothly and can be applied in thin layers, can
be thinned with water to adjust tack time, will bond
pyroxlin-coated bookcloths (used to repel water, dirt,
etc.), will dry within a reasonable time, is strong, won't
age, is not affected by environmental factors (e.g.,
won't absorb atmospheric humidity or pollutants), is
flexible and transparent when dry, etc. We'd also like
it to be reversible, but...

Contrast these properties with woodworking formulations
that are stronger than the wood they bond, include dyes to
match wood colors, dry hard so they can be worked
like wood, etc.

Also contrast hand binding requirements with those
specific to machine binding (see Tony Clark's
"Bookbinding with Adhesives," McGraw-Hill (1988).

Consequently, while there are many PVA-adhesives
available, we use those that are specially formulated
for bookbinding (e.g., check Talas's catalog online).
In a pinch, something like Elmer's can be a satisfactory
substitute, but woodworking adhesives usually can't.

The same can be said for methyl-cellulose based
adhesives (an important ingredient in Gummy Bears,
laxatives, and pharmaceuticals).

Alan Shalette


-----------------------------
Kantrowitz, Morris S.
Miscellaneous Bookbinding Adhesives
GPO-PIA Joint Research Bulletin,
Bindery Series No. 4 (1953)
Government Printing Office - Printing Industries Association

Because of wartime restrictions placed on the quantities of animal glue 
available for use in the pro­duction of adhesives in the Government Printing 
Office, a study was made of various synthetic resins early in 1943 for the 
purpose of ascertaining whether or not some of these might prove satisfactory as 
substitutes for the glue compositions employed by the bindery.





This investigation led to the development of several resinous adhesive formulas 
employing as the principal constituent a water emulsion of polyvinyl acetate 
resin. This compound, manufactured commercially as a heavy milky white emulsion 
similar in consistency to liquid glue, exhibits excellent adhesive qualities, 
drying out into a hard but brittle film. In view of its brittle nature when dry, 
it proved unsuitable in its manufac­tured form as a substitute for the flexible 
glue com­pounds employed for bookbinding operations such as gluing-off, 
lining-up, perfect binding, and padding.





Experiments revealed that the addition of a soften­ing agent or plasticizer to 
the polyvinyl acetate emul­sion, in an amount equivalent to 8 percent of the 
total weight of emulsion, produced dry resinous films per­manently flexible and 
ideally suited for padding and notebook work. It was observed in the course of 
this research that the addition of varying amounts of a dibutyl phthalate 
plasticizer to polyvinyl acetate emul­sion increased the viscosity or thickened 
the padding compound in proportion to the quantity added. The increase in 
viscosity was so noticeable when 10 percent of the plasticizer was added that 
bookbinders who ap­plied the adhesive to the pads complained that the com­pound 
was too thick for easy application. The thick compound did not brush on readily 
and more time was consumed in working the thick mixture. Preliminary tests made 
with a padding compound of low viscosity demonstrated that a thin compound of 
uniform vis­cosity could be more readily applied than a viscous one.





Small amounts of water were accordingly added to the plasticized polyvinyl 
acetate emulsion in order to thin out the mixture sufficiently for easy 
application by the bookbinder. A viscosity range lying between 5 and 7 poises 
was found to be best for padding work.





A number of experiments were conducted using various chemical plasticizers in 
arriving at the present formulas used in this Office but only a few of these 
were found suitable in properties or of reasonable cost foruse as softening 
agents. Those which best met the requirements were dibutyl phthalate, glyceryl 
triacetate, sold under the trade name "Triacetin," and 2-methyl 2'4 pentanediol, 
sold under the trade name "Hexylene Glycol." The incorporation of small amounts 
of any of these chemicals into polyvinyl acetate emulsion pro­duces a very good 
bookbinding adhesive which remains flexible upon drying of the adhesive film.





Some advan­tages of polyvinyl acetate emulsion over other resinous adhesives are 
that it is readily diluted with water as required by the bookbinder, it is easy 
to apply, and safe to use since it contains no flammable solvents. It is also 
easily washed out of brushes and containers with water while still moist. When 
this plastic sets, it becomes water resistant.





The ordinary bindery glues and pastes are not satisfactory for adhering 
pyroxylin treated fabrics in some bindery operations and in many instances 
binders or cases glued with these adhesives pull loose or fail to remain glued 
after they have dried. The white resinous polyvinyl acetate adhesive has been 
found excellent for the pyroxylin treated fabrics and has been used in this 
Office with complete success. This adhesive can be used for many hand operations 
in­cluding gluing-off, lining-up, and the application of rides or labels. One of 
the uses found for this adhesive was that of affixing oil cloth linings to 
pyroxylin coated binders. The adhesive for this operation was applied by a 
machine to the back of an oil cloth strip, which was then applied to the inside 
of the binder. This ad­hesive produced a strong permanent bond between the 
tumed-in edges of the pyroxylin coated film and the oil cloth. Previous 
operations of this nature using hide glue as the adhesive were not satisfactory 
unless the turned-in edges of the coated fabric were first washed with alcohol, 
adding another operational cost to the production.





There is no necessity for the use of preservatives with this adhesive since it 
does not deteriorate upon aging nor is it subject to molds or fungus growths, 
even though it may be exposed to the air for many months. How­ever, freezing 
destroys the emulsion, and therefore pre­caution must be taken to avoid exposing 
it to freezing temperatures before using.





This formula produces an adhesive which will firmly fasten paper, leather, or 
such fabrics as pyroxylin treated, starch filled, rubberized, or plain muslin 
cloths to cellulose acetate surfaces. It has been used in this Office in the 
production of transparent cellulose ace­tate envelopes for the protection of 
maps and photo­graphs upon exhibition. The cloth binding used on this type of 
work is glued-off by hand, permitted to dry for about two minutes, and then 
applied to the cellulose acetate surfaces.  In preparing this adhesive add the 
water to the polyvinyl acetate emulsion and then follow with the dibutyl 
phthalate and gamma valerolactone with constant stirring. Either hexylene glycol 
or tri-acetin may be substituted for dibutyl phthalate as the plasticizer.

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