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Патент USA US2059343

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Nov. 3, 1936.
Filed July 25. 1930
atented Nov. 3, i~93? I
Frank Had?eld, Chillicothe, Ohio, assignor, by
mesne assignments, to The Mead Corporation,
Dayton, Ohio, a corporation of Ohio
Application July 25, 1930, Serial No. 470,594
1 Claim. (01. 91-568)
This invention relates to the manufacture of
paper, and particularly to the manufacture of’
coated paper.
One of the principal objects of the invention is
The cost of casein is relatively high-in fact
more than double the cost of a. good quality of
starch. It is therefore desirable from the eco
nomical aspect to use a cheaper size, such as
starch, along-with casein; The mixing of starch
having a superior surface which is suitable for and casein in a coating color for the coating of
oifset printing, which method is economical and magazine and book grades of paper has not been
effective in operation, and is simple and easily heretofore practical in economical commercial
operation, as an objectionable reaction readily
takes place in the sizing solution or coating mix.Still another object of the invention is to pro
‘vide a superior coated paper having a surface‘ ture which renders the resultarrt product pracl
tically worthless for coating work. The present
coating sized with a mixedstarch-casein size.
Another object of the invention is to provide invention provides‘ a method whereby starch may
a method of preparing a mixed, starch-casein be incorporated with casein in controlled pro
15 sizing solution, and of preparing a coating com . portions to form a mixed starch-casein size while
maintaining the solution properties of the same,
position containing sucha sizing solution. ‘ v
and to permit the incorporation of this mixed
Still another object of the invention is to pro
starch-casein size with a ?ller suspension to
vide apparatus for carrying out the above‘ meth
7 provide a coating mixture suitable for the pro
od and for forming the above product.
duction-of a superior coated paper which is sufOther objects and advantages ‘of the inven
?ciently damp proof and in which the ?ller and
tion will be apparent from the following descrip
to provide a method of preparing a coated paper
tion, the accompanying drawing and appended
1n the drawing, in which a preferred embodi
other ingredients are e?ectively held on the sur
face of the sheet for various kinds of printing,
including magazine, book and o?set printing.
Referring, to the drawing, a casein solution
ment of apparatus is illustrated, the single ?gure
is an elevational view, partially _tic tank is indicated at I 0, this tank having a ‘jacket
and partly in section, of apparatus constructed II with suitable inlet and outlet connections l2
in accordance with this invention.
' According to this invention, the uncoated paper
and I3 having therein ‘control valves I4 and I5
respectively‘for the introduction of steam into
the jacket in order to heat the contents of the 30
tank Ill. The jacket H is also provided with
inlet and outlet connections‘ l6 and I‘! provided
with valves l8 and I9 respectively for the intro
duction of‘a. cooling medium such as cold water
‘ into ‘the jacket. A central vertical shaft '20 35
30 or raw stock as received from the paper machine
is given a surface coating with a coating compo
sition containing a mixed starch-casein size. It
has heretofore been quite the common practice
in the coating of paper to employ casein as a size
for binding the ?ller and other ingredientsof the
at coating
composition effectively on .the surface of - mounted in suitable bearings carries agitating
the paper sheet. It is well‘ recognized that a paddles 2| which cooperate with suitable ba?ies
highly e?ective size is necessary for surface coat- ' 22 protruding from the wall of the tank inter
ing work-that is, a size which has more bind
mediatethe paddles ‘2| to permit an effective
ing power than is ordinarily necessary for use agitation of the contents of the tank. The upper 40
in binding the ?bers together in the body of the ' end of the shaft 20 is provided with a bevel gear paper as formed. Especially is this so in the case .23 meshing with a bevel pinion 24 carried on the
of printing paper, where the mineral ?ller and extended end of an armature shaft of a motor
other ingredients are apt to “pick of!" or become 25 seating on the cover 26 of the tank.
dislodged during the printing operation. Starch
Inthe preparation of the casein solution,‘ the 45
of itself does not possess su?icient binding power tank lil is supplied with the desired amount of
to'hold the mineral ?ller effectively on the sur
cold or tepid water, generally water at a tem
face ‘oi a sheet for coated paper used in high perature about 32’ F. to 80° F. being satisfactory.
grade printing work in magazine and book grade. A predetermined amount of casein is then added
'50 Casein has been considered superior to starch tn the tank during agitation of the contents. 50
. for coating work, because of the high binding This preliminary treatment in cold or tepid
power‘ of casein and because casein sized coated water serves to swell the grains and makes them
paper is practically damp proof and therefore Vmore receptive for the alkali which is later
can be used where the humidity is high without added. It is desirable not to add water at a tem
undue cockling or curling of the sheet.
perature materially higher than 80° _1". at ?rst, 5B
as a partial cooking of the outside of the granules
is apt to result at higher temperatures, and a
lumpy mixture may result. A solution contain
ing from about six parts of water to one part
of casein by weight up to about twelve parts of
water to one of casein gives a satisfactory solu
tion which will blend well with the starch solu
tion which is separately prepared, while at the
same time undue dilution is avoided. . After the
casein has been allowed to stand in the cold or
tepid water for about ?ve minutes with agitation,
then an alkaline material, such as sodium car
bonate, sodium hydroxide, borax, or other simi
lar alkaline compound, is added.
Sodium car
15 bonate is preferred for this purpose, and is pref
erably ?rst made up into a solution containing
about three parts of water to one part of sodium
carbonate by weight. Sui?oient alkaline solu
tion is added to the casein mix to effect the solu
20 tion of the casein. When sodium carbonate vis
used, about 12% to 15% of NazCOa on- the dry
weight of the casein gives satisfactory results.
The mixture is then heated with agitation until
solution is effected. Accurate' control of the
heating, while avoiding unduly high tempera-v
tures or direct steam injection which isinjurious,
is obtained by means of the heating jacket with
valve controlled steam connections. The mix
ture is not heated above 172° F., as above this
30 temperature the binding properties of the casein
are apt to be deleteriously affected. However,
below 150° F. it is dif?cult and requires a long
time to eiiect solution of the casein. Conse
quently it is preferred to heat the solution be
35 tween 168° F. and 172° F., within which tempera
ture range a satisfactory clear solution is ob
tained in about thirty minutes with effective agi
A starch solution tank 30 having an exterior
40 jacket 3| is also provided with a central vertical
shaft 32 containing suitable agitating paddles 33
cooperating with stationary baffles 34 ?xed to
the wall of the tank 30. The shaft 32 is provided '
with a bevel gear 36 meshing with a bevel pinion
45 31 carried by the armature shaft of a motor 38
seating on the cover 39 of the starch solution
tank. Inlet and outlet connections 4|! and 4|
having control valves 42 and 43 respectively are
provided for introducing a cooling medium into
50 the jacket 3| of the starch solution tank. A
steam supply pipe 44 having a control valve 45
extends down into the interior of_ the tank 30,
and opens into the interior thereof as indicated
at 46 in order to introduce steam directly into
55 the contents of the tank 30 for heating purposes,
direct steam injection not being injurious to the
The starch to be dissolved is added to a meas
ured quantity of cold water with agitation. A
60 modi?ed or oxidized starch, or one which is ren
dered readily soluble and free ?owing, and which
forms what is termed “a thin boiling” solution,
is used. The starch-water mixture is then
heated up by the direct injection of steam to a
65 temperature above‘ 170° F., preferably approach
ing the boiling point in order to obtain quick
solution. About one part by weight of starch to
three to six parts by weight of water gives a
sults are obtained by the addition to the gum of
a small amount, such as about 1/2% by'weight,
of an alkaline material such as borax, soda ash
and the like, giving ‘a better mixing and more
adhesive gum solution. This alkali is preferably
added to the cold water in which the starch is
to be dissolved, prior to the cooking or heating
The casein solution is then mixed with the
starch solution with agitation. The casein so 10
lution can be ?owed into the starch solution, or
vice versa, this depending upon the relative
proportions of the ingredients. Thus, when a
relatively large proportion of starch is used with
reference to casein, the latter is ?owed into the
starch solution.‘ For this purpose, the casein
tank I0 is preferably positioned at a higher ele
vation than the starch solution tank 30, and is
provided with a bottom outlet 41 connected by a
gravity feed pipe 48 having a control valve 49 20
with the upper portion of the starch solution tank
30. In order to avoid injuring the binding prop
erties of the casein, particularly where using
more starch than casein, the starch solution
which has been previously heated up to about 25
200° F. or above to effect solution is then quickly
cooled by introducing a cooling medium into the
jacket 3|. The temperature of the starch solu~
tion is preferably brought down to approximate
ly that of the casein solution, so that the two so 30
lutions are mixed when at approximately the
same temperature. A temperature range of
about 150° F. to 172° F. gives satisfactory results
for the'mixing of these solutions, a temperature
approaching 170° F. being preferred. The tem 35
perature is kept high enough to avoid objection
able thickening and bad blending, while at the
same time the temperature is maintained below
that which will injure the binding properties of
the casein. It is to be noted that one solution is 40
?owed slowly with agitation into the other solu
tion under controlled temperature conditions,
which is found to permit in practical operation
the effective mixing of these solutions while
maintaining the solution properties thereof.
Satisfactory results are secured with mixtures
of various proportions when prepared in ac
cordance with this invention. A sizing compo
sition containing as little as 10% by weight of
casein together with 90% by weight of starch
has been used in actual commercial operations
with very satisfactory results. The mixed starch
casein solution is then cooled further by the in
troduction of .cooling water into the jacket 3|
preparatory to the mixing of the size solution
with a water suspension of filler, particularly
where ?llers other than clay are used. For this
purpose, branch pipes 50 and 5| having control
valves 52 and 53 respectively are preferably pro
vided for introducing a cooling medium, such as 60
cold water, into jacket 3| of tank 30. Of course,
where time and storage conditions permit, at-v
mospheric cooling may be used.
"The ?ller suspension of the coating composi
tion may be prepared in any conventional man
ner. As illustrated, a ?ller suspension tank 55
is, provided with a central shaft 56 carrying stir
ring blades 51 which cooperate with bailles 58
satisfactory thin boiling solution while avoiding carried by the wall of the tank in securing an
70 undue dilution. Preferably about one part of effective mixing of the ?ller and suspension liq 70
starch to four parts of water by weight is used. uid such as water which is added thereto by the
Continuous agitation at high temperatures ef
pipe 60 having the control valve 6!. The agi
vfects rapid dissolving of the modified starch. tator is driven by means of cooperating bevel
with certain modified viscous starches having an gears 62 and 63 from a motor 64 seating on the
76 acid reaction, so-called acid gums. improved re
cover 65 of the tank.
- 75
- 3
tional tiller suspension tanks, ‘such as
>' -A measured quantity of ?ller is added .to' the
tank I
indicated ‘at 80, may also be used depending upon
tank 55, and then a'proportioned quantity of
water is introduced by the pipe 60 in orderto
make a- suspension. of the desired‘ consistency
the requirements ot'the installation. The starch
sol'utiontank ‘III is connected by a feed pipe 13
having control valve ‘ll with the ?ller suspension
tank 80. Each ?ller suspension tank is provided
with a bottom outlet 1!. controlled by a valve ‘II
-5 depending on the weight or coat required. The
‘usual ?llers may be used; clay, satin‘white, blanc
?xe, and carbonate illlers'iare preferred tor the
coating of printing paper-such as'book'or maga for supplying the coating mixture to the coating
zine paper. The starch-casein solution having »‘ machine.
~10 been cooled down to a. temperature preferably 5 Heretoi‘ore-it has been the general-practice to‘ 10
employ a special sizing treatment for paper [in
order tolprepare it for o?set printing, in which
’ below 140° F. by the introductionoi' cooling me
dium into the jacket 3| is then allowedjto ?ow
' slowly through the outlet ii‘llcontrolled by valve ' method of printing .the paper comes in contact
‘ 68 into"the ?ller suspension tank. 55, while, the with awater dampened rubber blanket. Coated
15 ?ller suspension isb'eing agitated. ‘By the addi-\ , paper inaype prepared in<.accordanoe with the
tion of the size slowly and ate. fairly constant present invention which is ‘very satisfactory‘ for '
. temperature, a satisfactory vmixing of the size
oflsetprinting, without employing such a s cial
and ?ller suspension without objectionable thick
sizing treatment. Where a coated paper to on
, ening or coagulation is secured. When Su?icient > set printing is desired, the coating composition is
20‘ size making ‘and storage facilities are available, k prepared as outlined above, except that a coating 20
com osition which is substantially-neutral in ree
it is desirable to cool the sizing solution to tem
peratures as lowas 770° F. before introduction* _actlo is used to provide a coated paper having a ' Q
.into the ?ller suspension,.thereby obtaining in- I substantially neutral surface, which gives no
creased sizing efficiency. ‘The sizing. solution is
'25 ‘stirred during the cooling thereof.
deleterious acid or alkali effects upon being
‘dampened in offset printing. This neutral reac--r 25'
I ‘The proportions
_ of mineral ?ller to size may ‘ tion is obtained by proper control of the solution .
‘be varied depending upon the character of paper a of the casein’ by using ammonia‘to ldlgsolve the
required. ‘Satisfactory results for printing paper - ‘casein inplace of. soda, soda ash or'borax. The
- are secured by using about ‘70% to 85% by weight
excess ammonia used in effecting solution is re
30 of mineral ?ller to 15% ‘to 30% by weight. moved during‘ the heating oi-‘the material, so 30
of mixed starchecasein size. I Very satisfactory ‘that substantial neutrality of: the material is
results have been secured in commercial opera
. obtained. A substantially neutral starch solution
tion with a coating mixture containing by weight
approximately 72% to 77% of filler such 'as play,
is likeivise employed. O?set printing paperpre
pared in accordance with this invention is also
tree‘irom" any objection/due to “greasing”, which
mixed starch-casein size, the balance being alkali, is the term applied in the printing industry where
’ foam oil and other ingredients customarilylused portions of the cylinder of the printing press
in coating vmixtures. A mixture of ?ller ‘is pref-. '~ other. than the printing plate are affected by
35 satin white, or carbonate ?ller, 20% to‘ 25%v of
erably used, such as about one part by weight of ' some chemical in the papercoating, causing the
satin white to three parts by ‘weight ofa car
surrounding portion of the print to be smeared 40'
bonate ?ller, such as a precipitated calcium car ‘ withi k.
n ' economy is effected Fy the use 0! the . i
bonate, this giving’ a coated paper with a ‘high 1 Material
coating composition containing a substantial pro"- >
In order to obtain a substantially continuous “ 'portionx oiv starch. ‘ The resulting starchqcasein
operation for continuous coating work, ,a“ plural- - sized coated paper has a softer suri'ace than a‘ 45
i , ity of starch solution. tanks are provided. A s c
ond starch‘ solution tank is illustrated in the ac
companying drawing at 10 having a‘ gravity‘ feed
casein sized coated paper, and‘is superior tor
printing inasmuch as there is less wear upon the _ - a
_plates during the printing process and the surface
pipe 1 l-'controlled by a valve 12 tor-‘the supply or, to i the \paper has better ink ‘a?inity. The coated
50, casein solution from the casein tank In thereto. >'paper of the present invention is effectively damp
‘The .tank 10 is, constructed‘ similarly to the tank
‘30, .so that further detailed illustration and de-,
While‘ the forms of the invention herein de-.
scription is unnecessary. A considerable (plan' scribed constitute preferred embodiments there
. "tity pi caseinrsolution may’ be‘ initially made up for, it isto be‘ understood .that the invention is ‘
5'5. in t
.tank in and maintained at the desired . not» limited ‘to these precise form'sp and that
changes vmay be?made therein without departing
batch of. starch solution may-be made \_up in one "- from the scope or the invention which is defined
temperature range by means oi the Jacket II. A _
of the tanks 30 or 10, whilethe caseinrsolution
" is being allowed to flow slowly from the tank l0 1 ‘again?33:31:???
g 60 into the other starch solution'tahk containing a
A coatgd paper adapwd 1dr priming andxook
' previously prepared starchjsol'ution maintained ‘paper’.¢5mp?smg a sheet. having-a surface coat_
" at the‘desired temperature for mixing. The mix'- ‘mg containing approximately 70% to 85% by
June after agitation and cooling may then‘ be ' -weight of a mineral ?ller including a major pro
' ?owed into the ?ller suspension tank“ 55, and a
portion‘ of carbonate ?nefand a minor promp
cs fresh supbly‘bf Blanch arid Water theneddedito “ ‘tion of satin white, and a'pproximately'30% to
the starch solution tank or the preparatio'n’ot a ' 15" b Wei ht of a mixed starchwasem Si
‘ rresh
being batch,
to ?ow
slowly ‘from
tank Iii
is ca'sem_
“12m: _/apgmximately
. ‘ . v 90%
amzle ,
into theother starch solution tank III.
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