Re: oil-print-glyoxal??

From: Katharine Thayer <kthayer@pacifier.com>
Subject: Re: oil-print-glyoxal??
Date: Mon, 27 Dec 2004 11:29:14 +0000

> For one thing, it seems that fewer paper manufacturers are using
> gelatin for sizing than were at that time,

I also read the same thing stated in industrial chem literature.

> This morning I've been asked privately to produce detailed
> information about these conversations, who I talked to and whether I
> kept a written record of the conversations and so forth.

Did the questioner have anything useful to add to the discussion?
Or did s/he say why that piece of info is important?

> I can't imagine why paper manufacturers would lie to me about
> this. You'd think that if they were going to lie about it, they
> would lie in the other direction. I can't think of any reason it
> would be to their advantage to tell me that they don't harden the
> gelatin, if they do.

Often people are involved with dozen different projects and get
confused when they get questions. Often people believe something
wrong. Often people don't know but they decide it for you.

I personally don't think figuring out the details of exactly what they
do is important or relevant to what we are doing here. More of the
question is which sizing has good adhesion, good chemical barrier
property and robust enough not to get damaged during coating and
processing.

We use the term "harden" to mean crosslink, and what it means is to
crosslink gelatin macromolecules at amino, carboxyl or maybe some
hydroxyl residues. The reason we do this is to reduce swelling of
gelatin without diminishing hydrophilic nature of the molecules.
There are other ways to achieve the same/similar goal of reducing
swelling if reduction of hydrophilicity is acceptable. Manufacturing
paper of good wet strength involves reduction of hydrophilicity
(therefore using sizing material that makes cellulose more
hydrophobic, like aquapel), so I'm not surprised if they somehow
achieve their goals in ways different from crosslinking gelatin
molecules.

--
Ryuji Suzuki
"People seldom do what they believe in.  They do what is convenient,
then repent." (Bob Dylan, Brownsville Girl, 1986)