Polysaccharide derivatives containing aldehyde groups on an aromatic ring, their preparation from the corresponding acetals and use in paper

Polysaccharide aldehydes having the formula ##STR1## or Sacch--O--CH.sub.2 --Ar--CHO (II) such as starch, cellulose, and gum aldehydes, are useful as paper additives for imparting strength and as the granular or gelatinized portion of a corrugating adhesive. Those having formula I are prepared by a nonoxidative method which involves reacting the polysaccharide base, in the presence of alkali, with a derivatizing acetal reagent having the general structure ##STR2## and then hydrolyzing the acetal by adjusting the pH to less than 7, preferably 2-4. In the formula Ar is an aryl group, optionally containing an ether linkage, or an alkaryl group and A and A' are lower alkyls or together form at least a 5-membered cyclic acetal. The polysaccharide aldehydes are crosslinked by the addition of selected polyfunctional crosslinkers such as an aliphatic primary polyamine or polyketone.

BACKGROUND OF THE INVENTION 
The present invention relates to polysaccharide derivatives containing 
aldehyde groups on an aromatic ring and to the acetal derivatives used in 
the preparation of some of the aldehyde-containing polysaccharide 
derivatives. It also relates to a non-oxidative process for introducing 
aldehyde groups into polysaccharides, particularly granular 
polysaccharides. It further relates to the use of the cationic 
polysaccharide derivatives as paper additives and the use of the starch 
derivatives in corrugating adhesives. 
As used herein, the term "paper" includes sheet-like masses and molded 
products made from fibrous cellulosic materials which may be derived from 
natural sources as well as from synthetics such as polyamides, polyesters, 
and polyacrylic resins, and from material fibers such as asbestos and 
glass. In addition, papers, made from combinations of cellulosic and 
synthetic materials are applicable herein. Paper-board is also included 
within the broad term "paper", with "corrugated paperboard" referring to a 
fluted medium and a facing adhesively joined to the tips on one or both 
sides of the fluted medium. 
Oxidative and non-oxidative methods have been used to introduce aldehyde 
groups into polysaccharides such as starches, gums, and celluloses. The 
oxidative methods used have included treatment with periodic acid, 
periodates, or alkali metal ferrates. See U.S. Pat. No. 3,086,969 (issued 
Apr. 23, 1963 to J. E. Slager) which discloses an improved process for the 
preparation of a dialdehyde polysaccharide, (e.g., starch) using periodic 
acid; U.S. Pat. No. 3,062,652 (issued Nov. 6, 1962 to R. A. Jeffreys et 
al.) which discloses the preparation of dialdehyde gums (e.g., gum acacia, 
pectin, and guar) using periodate or periodic acid; and U.S. Pat. No. 
3,632,802 (issued Jan. 4, 1972 to J. N. BeMiller et al.) which discloses a 
method for oxidizing a carbohydrate, (e.g., starch or cellulose) with an 
alkali metal ferrate. 
In the above methods the aldehyde groups are formed by the oxidation of the 
hydroxyl groups on the ring and/or side chain. Treatment with periodic 
acid or periodate selectively oxidizes the adjacent secondary hydroxyl 
groups on the ring carbon atoms (e.g., the 2,3-glycol structures), cleaves 
the ring, and results in a "so-called" dialdehyde derivative which is 
principally a hydrated hemialdal and intra- and intermolecular 
hemiacetals. Treatment of carbohydrates with alkali metal ferrates 
selectively oxidizes the primary alcohol group on the side chains without 
ring cleavage or oxidation of the ring hydroxyls. 
The disadvantages of the oxidative method include degradation to lower 
molecular weight products and the formation of carboxyl groups due to 
further oxidation of the aldehyde groups. U.S. Pat. No. 3,553,193 (issued 
Jan. 5, 1973 to D. H. LeRoy et al.) describes a method for oxidizing 
starch using an alkali metal bromite or hypobromite under carefully 
controlled conditions. The resulting dialdehyde is reported to have a 
substantially greater proportion of carbonyl groups (i.e., aldehyde 
groups) than carboxyl groups. It also discloses a method for selectively 
oxidizing the side chains of starch derivatives (e.g., an alkoxylated 
starch such as dihydroxypropyl starch) under the same process conditions 
whereby the underivatized starch hydroxy groups on the rings are 
substantially non-oxidized. 
The presence of carboxylic groups in aldehyde starches has several 
disadvantages in addition to the obvious reduction in the degree of 
aldehyde substitution. These include the introduction of hydrophilic 
properties due to the carboxyl groups, an upset in the cationic/anionic 
ratio when a cationic starch base is used (as in most papermaking wet end 
uses), and the possible formation of salts (in the above papermaking end 
use) which could give rise to ionic crosslinking. 
The non-oxidative methods typically involve the reaction of the 
polysaccharide with an aldehyde-containing reagent. See U.S. Pat. No. 
3,519,618 (issued July 7, 1970 to S. M. Parmerter) and U.S. Pat. No. 
3,740,391 (issued June 19, 1973 to L. L. Williams et al.) which cover 
starch derivatives and U.S. Pat. No. 2,803,558 (issued Aug. 20, 1957 to G. 
D. Fronmuller) which covers a gum derivative. The starch derivative of 
Parmerter is prepared by reaction with an unsaturated aldehyde (e.g., 
acrolein) and has the structure Starch-O--CH(R.sup.1)--CH(R.sup.2)--CHO 
where R.sup.1 and R.sup.2 are hydrogen, lower alkyls or halogen. The 
starch derivative of Williams is prepared by reaction with acrylamide 
followed by reaction with glyoxal and has the structure 
##STR3## 
The gum derivative of Fronmuller is prepared by treating the dry gum 
(e.g., locust bean or guar gum) with peracetic acid to reduce the 
viscosity, neutralizing, and then reacting with glyoxal. Water-soluble 
cellulose ethers (e.g., hydroxyethylcellulose) have also been reacted with 
glyoxal or ureaformaldehyde to give aldehyde-containing derivatives. 
One of the disadvantages of introducing the aldehyde groups directly using 
an aldehyde-containing reagent is the possibility of the derivative 
crosslinking prior to use. The Williams patent (cited above) alludes to 
this problem when it notes that solutions of the glyoxalated polymers "are 
stable for at least a week when diluted to 10% solids by weight and 
adjusted to pH 3" (see Col. 3, lines 60-63). The Parmerter patent notes 
that the starch aldehyde is "a substantially non-crosslinked granular 
starch derivative" and discusses the importance of the non-crosslinked 
character (see Col. 2, lines 40-45). 
The crosslinking of a starch derivative containing two or more aldehyde 
groups (e.g., dialdehyde starch) with compounds containing two or more 
isocyanate groups (e.g., polymethylenepolyphenylene polyisocyanate) 
provides a water-resistant adhesive composition. See Japan. Kokai 
57-202,362 published Dec. 11, 1982, Hohnen Oil Co., Ltd. (C.A. 98: 200152m 
1983). The crosslinking of dialdehyde starch with an alkylene diamine such 
as an aliphatic diamine (e.g., hexamethylene diamine), and/or an aromatic 
alkylene diamine (e.g., methylene dianiline) is disclosed in U.S. Pat. No. 
3,706,633 issued Dec. 19, 1972 to E. Katchalski et al. However, the 
crosslinking cannot be controlled because the granular dialdehyde starch 
is reactive toward the starch hydroxyls, thus leading to premature 
self-crosslinking rather than crosslinking via the diisocyanate or 
diamine. 
Polysaccharides modified with acetals, such as dimethoxyethyl methyl 
chloroacetamide (DMCA), as described in Ser. No. 758,634 (cited 
previously), have been shown to possess some very unique properties. Once 
the polysaccharide is dispersed and the acetal is converted to aldehyde by 
lowering the pH to less than 7, crosslinking can occur between the 
aldehyde and any available hydroxyl group. This system is extremely 
effective as a strength additive in paper where the aldehydes can 
crosslink the fibers through the cellulose hydroxyls. The main drawback of 
these aldehydes is their tendency to crosslink the supporting 
polysaccharide backbone, as evidenced by a large increase in viscosity of 
a dispersion at greater than 5% non-converted starch solids. This makes 
their use in coating and adhesive applications, where high solids are 
required, impractical. 
There is therefore a need for an aldehyde system that is non-reactive 
towards the hydroxyls on the polysaccharide backbone and which will 
crosslink when desired. 
The particular adhesive employed in the corrugating process is selected on 
the basis of several factors, including the type of bond required in the 
final application of the finished corrugated product. Starch-based 
adhesives are most commonly used due to their desirable adhesive 
properties, low cost and ease of preparation. 
It is often desired or necessary in the manufacture of corrugated 
paperboard that the adhesive yield water-resistant bonds which can 
withstand extended exposure to high humidity, liquid water, melting ice 
and the like. A number of approaches have been devised to produce 
water-resistant corrugating adhesives. One method involves the preparation 
of an acidic, starch-based adhesive wherein urea-formaldehyde resin is 
added to the composition, together with an acidic catalyst such as 
aluminum sulfate, to produce water-resistant bonds in the corrugated board 
manufactured therewith. The adhesive composition itself, however, is 
deficient in other important properties such as corrugator bonding speeds, 
viscosity stability, and pot life and exhibits excessive formaldehyde 
odor. In addition, acidic corrugating adhesives tend to be corrosive. 
The many disadvantages associated with the acidic corrugating adhesives led 
to the development of water-resistant alkaline curing starch-based 
adhesives for use in the corrugating industry. In the preparation thereof, 
a thermosetting resin, such as, e.g., ureaformaldehyde, 
resorcinol-formaldehyde, melamine-formaldehyde, phenolformaldehyde, 
acetone-formaldehyde, ketone-aldehyde and urea-acetone-formaldehyde 
condensate, has been added to the adhesive as a cross-linking additive for 
the amylaceous components to produce water-resistant bonds. 
In using thermoset resins of the type mentioned above, crosslinking occurs 
immediately upon addition of the resin. This causes thickening of the 
cooked portion and inhibition of the uncooked portion, both of which 
result in poor speeds on the corrugator after the adhesives age for a 
number of hours. 
The corrugating industry is still searching for means for providing water 
resistance to corrugated paperboard products prepared from alkaline curing 
starch-based adhesives which are formaldehyde-free and which do not 
crosslink immediately. 
SUMMARY OF THE INVENTION 
The present invention provides polysaccharide ether derivatives wherein an 
aldehyde group is present on an aromatic ring of the ether substituent of 
the derivative, with the derivative having the formula 
##STR4## 
or Sacch-O--CH.sub.2 --Ar--CHO (II). It also provides an acetal-containing 
polysaccharide ether derivative which has the formula 
##STR5## 
It further relates to a crosslinked product having the structure 
##STR6## 
In the above formulas Sacch-O-- represents a polysaccharide molecule 
(wherein the hydrogen of a hydroxyl group of a saccharide unit has been 
replaced as shown); Ar is a divalent aryl group which can contain an ether 
linkage, or an alkaryl group; A and A' are independently a lower alkyl or 
A and A' together form at least a 5-membered cyclic acetal and P 
represents a divalent group. As used herein, the term alkaryl is intended 
to denote a divalent group linked to the polysaccharide through the alkyl 
portion of the alkaryl group and linked to the aldehyde (--CHO) group or 
acetal group 
##STR7## 
through the aromatic portion of the alkaryl group, and the term aromatic 
ring is intended to include not only conjugated hydrocarbons but also 
conjugated heterocyclic systems. The polysaccharide molecule may be 
modified by the introduction of cationic, anionic, nonionic, amphoteric, 
and/or zwitterionic substituent groups. As used herein, the terms 
"cationic" and "anionic" are intended to cover cationogenic and 
anionogenic groups. 
The aromatic aldehydes of formula I are prepared by hydrolyzing the 
corresponding acetal at a pH of less than 7, preferably 5 or less, most 
preferably 2-3. The acetals are prepared by reacting the polysaccharide 
with an acetal reagent having the general structure 
##STR8## 
where Z is an organic group capable of reacting with the saccharide 
molecule to form an ether derivative and selected from the group 
consisting of an epoxide, a halohydrin, an ethylenically unsaturated 
group, or a reactive halogen. 
A typical reagent is as follows: 
##STR9## 
It can be prepared by converting an alcohol-containing aldehyde (e.g., 
5-hydroxymethyl furfuraldehyde) to the acetal by treatment with an excess 
of an anhydrous alcohol (e.g., methanol) in the presence of a trace amount 
of an acid. The acetal is then reacted with an epihalohydrin (e.g., 
epichlorohydrin) under conditions that will not affect the acetal group 
(i.e., under alkaline conditions). The epihalohydrin reaction is described 
in an article by R. Pozniak and J. Chlebicki entitled "Synthesis of Higher 
N-(2-Hydroxy-3-alkoxypropyl) ethanolamines and 
N-(2-Hydroxy-3-alkoxypropyl)diethanolamines", Polish J. Chem. 52, p. 1283 
(1978). 
The aromatic aldehydes of the formula II are prepared by the 
chloromethylation of an aromatic aldehyde and the subsequent 
derivatization of a polysaccharide with the reaction product. The 
chloromethylation procedure described in C.A. 31, 7412: 6 (1937) is 
suitable for the chloromethylation of o-anisaldehyde and 
m-nitrobenzaldehyde. The procedure is modified in that concentrated 
hydrochloric acid is used rather than dry hydrogen chloride gas. For 
example, a mixture of o-anisaldehyde aldehyde, concentrated hydrochloric 
acid, and p-formaldehyde is stirred for 48 hours at room temperature, the 
precipitated product is filtered off, and the resulting product is washed 
with a sodium bicarbonate solution (0.5%) and then with distilled water 
until neutral, and dried in vacuum. The choromethylation of benzene and 
naphthalene are carried out in a similar manner as described in Organic 
Reactions, edited by Roger Adams, Vol. I, pp. 67 and 70, John Wiley and 
Sons, Inc., New York 1942. 
The crosslinked products are prepared by dispersing the aldehyde-containing 
polysaccharide derivative in water and reacting the dispersed 
polysaccharide with an effective amount of a multifunctional crosslinker. 
When used with the polysaccharide derivative as a paper additive, the 
amount used is typically about 0.5 to 100% by weight, preferably 50%, 
based on polysaccharide. When used with the starch derivative in a 
corrugating adhesive, the amount used is typically 0.5-10%, based on 
starch. When the crosslinker is an aliphatic polyamine (containing at 
least two primary amine groups), a polyhydrazine, a polyhydrazide, a 
polysemicarbazide, or a polythiol, the pH at which the aldehyde-containing 
derivative is crosslinked is typically about 2.5 to below about 13. When 
the crosslinker is a cyclic or noncyclic polyketone, the pH must be above 
11. The crosslinked products may also be prepared using the 
acetal-containing polysaccharide and the polyamine crosslinker; however, 
the pH must then be about 2 to 9. 
The aldehyde-containing and aetal-containing polysaccharide derivatives are 
useful in conventional applications where water-soluble or water-swellable 
polysaccharide derivatives are useful, for example, as coatings, 
adhesives, and paper and textile additives. When used as a paper additive, 
the derivatives, typically contain cationic and cationogenic groups in 
addition to the aldehyde groups. These include diethylaminoethyl ether 
groups introduced by reaction with 2-diethylaminoethyl chloride 
hydrochloride (DEC) or 3-(trimethylammonium chloride)-2-hydroxylpropyl 
ether groups introduced by reaction with 3-chloro-2-hydroxypropyl 
trimethylammonium chloride. The polysaccharides modified with the aromatic 
acetal reagents are unique in that conversion to the aldehyde, by cooking 
at pH 2.5, does not cause the increase in viscosity typically seen with 
polysaccharides modified with aliphatic acetal reagents e.g., an amioca 
starch modified with N-(2,2-dimethoxyethyl)-N-methyl-2-chloroacetamide 
(DMCA). 
The controlled reactivity of the polysaccharide derivatives containing the 
aromatic aldehydes offers some very important advantages. Since the 
viscosity does not increase, no restriction is placed on the percent 
solids used and crosslinking can be carried out when desired, e.g., to 
impart water resistance and strength by the addition of multifunctional 
materials capable of crosslinking with the aromatic aldehydes or aromatic 
acetals. Suitable crosslinkers include aliphatic polyamines containing 
primary amine groups, cyclic and noncyclic polyketones, polythydrazines, 
polyhydrazides, polysemicarbazides, polythiols and the like. Aromatic 
polyamines do not crosslink with the aldehydes, nor do aliphatic secondary 
amines. The polyketones only crosslink at a high pH (&gt;11). 
The use of this modified uncooked starch in a corrugating adhesive 
eliminates any potlife considerations since the reaction with the 
crosslinker only occurs when the modified starch gelatinizes during the 
bonding operation and not before. Further, the crosslinking mechanism is 
not based on formaldehyde chemistry as are most of the thermoset resins 
used in corrugating adhesives and hence there is no release of 
formaldehyde vapors during preparation or use. 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
When the polysaccharide is starch, applicable starch bases which may be 
used herein may be derived from any plant source including corn, potato, 
sweet potato, wheat, rice, sago, tapioca, waxy maize, sorghum, high 
amylose corn, or the like. Starch flours may also be used as a starch 
source. Also included are the conversion products derived from any of the 
former bases including, for example dextrins prepared by the hydrolytic 
action of acid and/or heat; oxidized starches prepared by treatment with 
oxidants such a sodium hypochlorite, fluidity or thinboiling starches 
prepared by enzyme conversion or mild acid hydrolysis; and derivatized and 
crosslinked starches. The starch base may be a granular starch or a 
gelatinized starch, i.e. non-granular starch. 
When the polysaccharide is gum, applicable bases which may be used herein 
are polygalactomannans, which are heteropolysaccharides composed 
principally of long chains of 1.fwdarw.4 .beta.-D-mannopyranosyl units to 
which single unit side chains of .alpha.-D-galactopyranosyl units are 
joined by 1.fwdarw.6 linkages and hereafter referred to as "gums". Also 
included are degraded gum products resulting from the hydrolytic action of 
acid, heat, shear, and/or enzyme; oxidized gums; and derivatized gums. The 
preferred gums include gum arabic, as well as guar gum and locust bean gum 
because of their commercial availability. 
When the polysaccharide is cellulose, applicable bases useful herein 
include cellulose and cellulose derivatives, especially water-soluble 
cellulose ethers such as alkyl and hydroxylalkyl celluloses, specifically 
methylcellulose, hydroxypropylmethyl cellulose, 
hydroxybutylmethylcellulose, hydroxyethylmethylcellulose, and 
ethylhydroxyethylcellulose. 
Methods for preparing the modified polysaccharide bases are well-known to 
those skilled in the art and discussed in the literature. See, for 
example, R. L. Whistler, Methods in Carbohydrate Chemistry, Vol. IV, 1964, 
pp. 279-311; R. L. Whistler et al., Starch-Chemistry and Technology, Vol. 
II, 1967, pp. 293-430; R. L. Davidson and N. Sittig, Water-Soluble Resins, 
2nd Ed., 1968, Chapter 2; and R. L. Davison, Handbook of Water-Soluble 
Gums and Resins, 1980, Chapters, 3, 4, 12 and 13 directed to cellulose 
derivatives, Chapters 6 and 14 directed to gums, and Chapter 22 directed 
to starch. 
The starch reactions with the derivatizing reagents that introduce the 
acetal groups are carried out using the general procedure described in 
U.S. Pat. No. 3,880,832 issued Apr. 29, 1975 to M. M. Tessler. Granular 
reactions are typically carried out in water at 20.degree.-50.degree. C., 
preferably about 40.degree.-45.degree. C. Non-granular starch reactions 
may be carried out at higher temperatures (e.g., up to 100.degree. C.). 
The reaction mixture is preferably agitated. Reaction time may vary from 
about 0.5-40 hours, preferably 8-24 hours, for aqueous reactions or from 
about 1-8 hours for reactions carried out in a substantially dry reaction 
medium. It will depend on such factors as the amount of reagent employed, 
the temperature, the scale of the reaction, and the degree of substitution 
desired. The pH is maintained at about 10-13, preferably 11-12, during the 
reagent addition and during the entire reaction using a base such as 
sodium, potassium, or calcium hydroxide. Sodium sulfate is typically added 
to the reaction mixture to reduce swelling of the granular starch; it is 
not used when calcium hydroxide is the base. Potassium or sodium iodide is 
a good catalyst for reacting the chloroacetylated amine derivatives, but 
it is not necessary for a satisfactory reaction with the starch. After 
completion of the reaction, the excess alkali is neutralized and the pH 
adjusted to about 4-8, preferably 7-8, using any conventional acid prior 
to recovery of the starch. 
The gum reactions with the acetal reagents are carried out in a two-phase 
reaction system comprising an aqueous solution of a water-miscible solvent 
and the water-soluble reagent in contact with the solid gum. The water 
content may vary from 10 to 60% by weight depending upon the 
water-miscible solvent selected. If too much water is present in the 
reaction system, the gum may swell or enter into solution thereby 
complicating recovery and purification of the derivative. The 
water-miscible solvent is added in the amount sufficient for the 
preparation of a slurry which can be agitated and pumped. The weight ratio 
of water-miscible solvent to gum may vary from 1:1 to 10:1, preferably 
from 1.5:1 to 5:1. Suitable water-miscible solvents include alkanols, 
glycols cyclic and acrylic alkyl ethers, alkanones, dialkylformamide and 
mixtures thereof. Typical solvents include methanol, ethanol, isopropanol, 
secondary pentanol, ethylene glycol, acetone, methylethylketone, 
diethyl-ketone, tetrahydrofuran, dioxane, and dimethylformamide. The 
reaction times and temperatures used for the aqeuous reactions are 
suitable for the solvent reaction. 
The cellulose reactions with the acetal reagents are conveniently carried 
out using the procedure of U.S. Pat. No. 4,129,722 (issued Dec. 12, 1978 
to C. P. Iovine et al.) The cellulose or cellulose derivative is suspended 
in an organic solvent and a water solution of the derivatizing reagent is 
added thereto. Derivatization in the resultant two-phase mixture is 
ordinarily carried out with agitation at temperatures of 30.degree. to 
85.degree. C., adding alkali if necessary to effect reaction. At least one 
of the initial phases (i.e., the suspended celulose or cellulose 
derivative or the aqueous reagent solution) contains a suitable 
surfactant. It is important that the organic solvent used in the initial 
cellulose phase be immiscible with the aqueous derivatizing reagent phase, 
that it not dissolve the cellulose derivative as it is formed, that it 
have a boiling point at or above the temperature of the derivatizing 
reaction, that it be insensitive to alkali and not participate in the 
derivatization reaction. 
The two phase procedure may also be used to prepare starch or gum 
derivatives as well as cellulose derivatives. It may also be used to 
prepare derivatives containing substituents derived from different 
reagents without isolating the substitution product from each reagent. 
This multiple substitution may be accomplished by the addition of several 
different reagents to the substrate-surfactant alkali mixture at the same 
time or sequentially. 
After completion of the acetal reaction the solid polysaccharide acetals 
may be separated, if desired, from the reaction mixture by centrifugation 
or filtration. Preferably, the derivative is purified by washing in a 
solvent in which the reagent is soluble and the polysaccharide insoluble. 
In the case of starch derivatives, water and/or a solvent are used. In the 
case of the gum derivatives, a solvent is used. In the case of the 
cellulose derivatives, an aqueous solution of water-miscible solvent is 
used. Further washing with a more anhydrous form of the same solvent may 
be desired for the gum derivatives. The derivatives are then dried using 
conventional methods, as in a vacuum, drum, flash, belt, or spray drier. 
If the polysaccharide is in solution when derivatized, other methods of 
purification will have to be used, e.g. precipitation. 
The conversion of the polysaccharide acetals to the aldehydes is carried 
out under acidic conditions, typically at a pH of 7 or less, preferably 5 
or less, most preferably at about 2-3. It may be carried out directly 
without isolation of the acetal or the acetal may be isolated as above and 
resuspended in water prior to conversion. If desired, the derivatives may 
be recovered as described above. 
In addition to preparing the above acetals or aldehydes, modified 
derivatives may be prepared which contain other substituent groups, 
hydroxyalkyl groups (e.g., hydroxypropyl ether groups), carboxyalkyl ether 
groups (e.g., carboxymethyl), ester groups (e.g., acetate groups), 
tertiary amino groups (e.g., diethylaminoethyl ether groups), and 
quaternary amine groups, (e.g. 3-(trimethylammonium 
chloride)-2-hydroxypropyl groups or 4-(trimethylammonium 
chloride)-2-butenyl groups), introduced prior to or subsequent to reaction 
with the acetal derivatizing reagent or introduced simultaneously by 
reaction with the acetal reagent and other derivatizing reagent. The 
practitioner will recognize that reactions with reagents introducing 
labile ester groups should be carried out after the other derivatizations 
to avoid ester hydrolysis under the alkaline conditions used to prepare 
other derivatives. 
The aldehyde derivatives used as paper additives preferably contain 
cationic groups, such as the quaternary ammonium and tertiary amine group 
discussed above, amphoteric, and/or zwitterionic groups. These derivatives 
are dispersed in water before use. The granular starch derivatives are 
cooked to provide the dispersed derivative. 
The starch may be cooked prior to derivatization to form the acetal, 
subsequent to derivatization, after conversion to the aldehyde, or most 
conveniently during conversion of the acetal to the aldehyde. Cooking at a 
pH of less than 7 simultaneously converts the acetal to aldehyde and 
solubilizes and disperses the starch aldehyde. Any conventional cooking 
procedure may be used, such as cooking a slurry containing the 
water-soluble or water-swellable derivative in a boiling water bath for 
about 20 minutes, blowing in steam to heat the slurry at about 93.degree. 
C. (200.degree. F.), or jet cooking. If a water-dispersible or 
water-soluble starch base is used for the prepration of the acetal, it 
will not be necessary to cook the acetal during the acid hydrolysis. 
Crosslinking of the aldehyde groups may be affected using polyamines 
ranging in molecular weight from the low molecular weight diethylene 
triamine (about 100) to the high molecular weight polyethyleneimines 
(about 100,000). The acetal-modified polysaccharides, e.g., starch, are 
cooked at pH 2.5 for about twenty minutes to convert the acetal to the 
aldehyde and disperse the polysaccharide. Crosslinking occurs as the 
polyamine (typically 0.1-1 g. of polyamine per 100 g. of the 
aldehyde-containing polysaccharide) is being added to the polysaccharide 
cook, but it occurs more rapidly at higher temperatures. The pH range at 
which the polysaccharide aldehyde crosslinking occurs is between about 2.5 
to 13. 
Under certain conditions (i.e., between pH 2.5 and 9.0) the polysaccharide 
acetal will crosslink upon the addition of the polyamine. The 
polyaccharide acetal is cooked at pH 7 and cooled prior to the polyamine 
addition. Above pH 9.0, no crosslinking of the dispersed polysaccharide 
acetal occurs even after 24 hours. 
Crosslinking may also be effected using polyketones, e.g., 2,5-hexanedione. 
The polysaccharide acetal is cooked at pH 2.5 to disperse the starch and 
convert the acetal groups to the aldehydes. The pH is then adjusted to 
12-13 and a small amount of the diketone (about 0.5 g.) is added. 
Crosslinking occurs rapidly if the diketone is added to the hot 
polysaccharide. It occurs more slowly if the polysaccharide is allowed to 
cool before the addition of the diketone. 
Three methods are available for controlling the crosslinking process. The 
first involves adding the polyamine to a stable dispersion of the cooked 
aldehyde-containing polysaccharide at the time of use. For example, the 
dispersion is added to the pulp in the wet end and the polyamine is added 
(such as at the head box). It is thus possible to afford permanent wet 
strength, wet web strength, and dry strength. 
The second method involves protecting the polyamine, e.g., by encapsulating 
it in a starch matrix. The encapsulated polyamine is added to the 
dispersed polysaccharide (i.e., cooked at pH 2.5). The dispersion shows 
very little change in viscosity until the mixture is placed in a boiling 
water bath. Upon heat the encapsulating material swells releasing the 
polyamine. A very firm gel (indicating crosslinking) forms in several 
minutes. If the mixture is not heated, but allowed to stand overnight, a 
slight release of the polyamine causes some crosslinking. 
The third method involves protecting the aldehydes by converting the acetal 
to the aldehyde while still in the granular form (i.e., without dispersing 
the polysaccharide by cooking it). Polysaccharides containing aliphatic 
aldehydes are so inhibited (i.e., crosslinked) that they can not be 
dispersed by cooking. The polysaccharides containing the aromatic 
aldehydes can be readily dispersed by cooking. The presence of the 
aldehyde can be demonstrated by cooking the aldehyde-containing 
polysaccharide and then adding the polyamine. A gel forms almost 
instantly. A cook of the polysaccharide containing the acetal groups shows 
no change upon addition of polyamine. 
It is assumed that high molecular weight polyethyleneimine (molecular 
weight of 45,000 to 100,000) cannot penetrate the surface of the starch 
granule. There is spectroscopic data which suggests that the 
polyethyleneimine exists as a spheroid type structure, which if big 
enough, will not be capable of fitting through the pores on the surface of 
the granule. If the high molecular polyethyleneimine is mixed with an 
aromatic aldehyde-containing starch in the granule form and the mixture is 
cooked in a boiling water bath, the starch will begin to disperse and then 
gel (i.e., crosslink). If a lower molecular weight polyamine is used, 
penetration and crosslinking occurs before the starch can be completely 
dispersed. The minimum molecular weight necessary to prevent penetration 
into the granule will depend on variables such as the starch base used, 
pH, temperature, salt content, and the like. 
The polysaccharide aldehyde derivatives described herein may be used as 
beater additives, although their addition to the pulp may occur at any 
point in the paper-making process prior to the ultimate conversion of the 
wet pulp into a dry web or sheet. Thus, for example, they may be added to 
the pulp while the latter is in the hydropulper, beater, various stock 
chests, or headbox. The derivatives may also be sprayed onto the wet web. 
If the derivative is trapped in the wet fibers after spraying, it may not 
be necessary to use cationic derivatives but they are preferred. 
The aldehydes herein may be effectively used for addition to pulp prepared 
from any type of cellulosic fibers, synthetic fibers, or combinations 
thereof. Among the cellulosic materials which may be used are bleached and 
unbleached sulfate (Kraft), bleached and unbleached sulfite, bleached and 
unbleached soda, neutral sulfite, semi-chemical chemiground wood, ground 
wood or any combination of these fibers. Fibers of the viscous rayon or 
regenerated cellulose type may also be used if desired. 
Any desired inert mineral fillers may be added to the pulp which is to be 
modified with the aldehydes herein. Such materials include clay, titanium 
dioxide, talc, calcium carbonate, calcium sulfate and diatomaceous earths. 
Rosin or synthetic internal size may also be present if desired. 
The proportion of the aldehyde to be incorporated into the paper pulp may 
vary in accordance with the particular pulp involved and the properties 
desired (e.g., wet strength, temporary wet strength, or dry strength). In 
general, it is preferred to use about 0.1-15%, preferably about 0.25-5% of 
the derivative, based on the dry weight of the pulp. Within this preferred 
range the precise amount which is used will depend upon the type of pulp 
being used, the specific operating conditions, the particular end use for 
which the paper is intended, and the particular property to be imparted. 
The use of amounts greater than 5%, based on the dry weight of the pulp, 
is not precluded, but is ordinarily unnecessary in order to achieve the 
desired results. 
In granular form the aromatic aldehyde derivartives herein are particularly 
useful as the granular portion of the corrugating adhesive. The most 
fundamental of starch corrugating adhesives is an alkaline adhesive which 
is comprised of raw ungelatinized starch suspended in an aqueous 
dispersion of cooked starch. The adhesive is produced by gelatinizing 
starch in water with sodium hydroxide (caustic soda) to yield a primary 
mix of gelatinized or cooked carrier starch, which is then slowly added to 
a secondary mix of raw (ungelatinized) starch, borax and water to produce 
the full-formulation adhesive. 
The gelatinized carrier starch portion of the adhesive composition herein 
may be selected from any of the several starches, native or converted, 
typically employed in starch corrugating adhesive compositions. Suitable 
starches include, for example, those starches derived from corn, potato, 
waxy maize, sorghum, wheat, as well as high-amylose starches, i.e., 
starches which contain 30% or more by weight of amylose, and the various 
derivatives of these starches. Hence, among the applicable starches are 
included the various starch derivatives such as ethers, esters, 
thin-boiling types prepared by known processes such as mild acid 
treatments, oxidation, and the like and those derivatives of these 
starches which have high amylose contents. The preferred starches are 
those typically employed in corrugating adhesives of the alkaline type. 
The starch content of the adhesive can vary considerably depending on 
several factors such as the intended end-use application and the type of 
starch used. The total amount of starch employed, including the 
gelatinized and ungelatinized portions of starch, ordinarily will be in 
the range of about 10-40% by total weight of the adhesive. 
The remainder of the adhesive composition is composed of about 0.3-5% of an 
alkali such as sodium hydroxide, based on total weight of starch, and 
about 54-89% of water, based on total weight of the adhesive. The 
preferred amounts of all ingredients are 10-35% starch, 1-4% alkali, and 
60-80% water. The alkali (base) employed herein is preferably sodium 
hydroxide; however, other bases may be employed in partial or full 
replacement of the sodium hydroxide and include, e.g., alkali metal 
hydroxides such as potassium hydroxide, alkaline earth hydroxides such as 
calcium hydroxide, alkaline earth oxides such as barium oxide, alkali 
metal carbonates such as sodium carbonate, and alkali metal silicates such 
as sodium silicate. The alkali may be employed in aqueous or solid form. 
In the corrugating process, the adhesive is applied (usually at between 
25.degree. and 55.degree. C.) to the tips of the fluted paper medium or 
single-faced board, whereupon the application of heat causes the raw 
starch to gelatinize, resulting in an instantaneous increase in viscosity 
and formation of the adhesive bond. The procedures employed in the 
production of corrugated paperboard usually involve a continuous process 
whereby a strip of paperboard is first corrugated by means of heated, 
fluted rolls. The protruding tips on one side of this fluted paperboard 
strip are then coated with an adhesive, and a flat sheet of paperboard, 
commonly known in the trade as a facing, is thereafter applied to these 
tips. By applying heat and pressure to the two paperboard strips thus 
brought together, an adhesive bond is formed therebetween. The 
above-described procedure produces what is known to those skilled in the 
art as a single-faced board in that the facing is applied to only one 
surface thereof. If a double-faced paperboard is desired, in which an 
inner fluted layer is sandwiched between two facings, a second operation 
is performed wherein the adhesive is applied to the exposed tips of the 
single-faced board and the adhesive-coated tips are then pressed against a 
second facing in the combining section of the corrugator under the 
influence of pressure and heat. The typical corrugating process and the 
use of operation of corrugators in general are described in U.S. Pat. Nos. 
2,051,025 and 2,102,937 issued on Aug. 18, 1936 and Dec. 21, 1937, 
respectfully to Bauer. 
It can be appreciated by the practitioner that a large number of variations 
may be effected in selecting the acetal derivatizing reagents, reacting 
them with the bases, converting them to the aldehydes, and utilizing the 
aldehyde derivatives as paper wet end additives or in corrugating 
adhesives in accordance with the procedure described above without 
materially departing from the scope and spirit of the invention. Such 
variations will be evident to those skilled in the art and are to be 
included within the scope of the invention. 
In the examples which follow, all parts and percentages are given by weight 
and all temperatures are in degrees Celsius unless otherwise noted. 
Reagent percentages are based on dry polysaccharide. 
The nitrogen content of the cationic bases and resulting acetals was 
measured by the Kjeldahl method and is based on dry polysaccharide. The 
presence of aldehyde groups are determined qualitatively by the viscosity 
increase of a cooked slurry and/or gel formation upon the addition of the 
crosslinking agent and quantitatively by titration. The quantitative test 
is carried out by slurrying 5.0 g. of the polysaccharide acetal in 
sufficient distilled water to give 500 g. The pH is adjusted to 2.5 with 
hydrochloric acid. The polysaccharide is dispersed by cooking in a boiling 
water bath for 20 min. The dispersed polysaccharide is cooked and the 
solids determined. A 100 g. portion of the polysaccharide dispersion is 
weighed out, titrated with 0.1 NaOH to the first end point (inflection 
point is between pH 4 and 5) and the ml. of NaOH required is recorded 
(T.sub.1). An aqueous solution (50 ml.) of hydroxylamine hydrochloride 
(prepared by dissolving 34.75 g. of the hydroxylamine hydrochloride in 
1000 ml. volumetric flask and diluting to the mark with water) is added to 
a 100 g. portion of the polysaccharide dispersion, heated at reflux for 60 
min., and titrated with 0.1N NaOH to pH 4.5. The ml. of NaOH required to 
reach the inflection point (pH 3.0-3.5) is recorded (T.sub.2). 
##EQU1## 
Best results are obtained using an automatic titrator. A blank of base 
polysaccharide (i.e., unmodified by the introduction of acetal groups) may 
also be run. 
In the paper tests, the tensile strengths are reported as breaking length 
(m.). The breaking length is the calculated limiting length of a strip of 
uniform width, beyond which, if such as strip were suspended by one end, 
it would break of its own weight. The breaking length (air dry) in meters 
(m.) is calculated using the formula B.L.=102 000(T/R)=3,658(T'/R'), where 
T is tensile strength in kN./m., T' is tensile strength in lb./in., R is 
grammage (air dry) in g./m..sup.2, and R' is weight per unit area (air dry 
in lb./1000 ft..sup.2). Paper specimens are selected in accordance with 
TAPPI T 400 sampling procedure. Those evaluated for wet strength and 
temporary wet strength were saturated with distilled water by immersion 
and/or soaking until the paper sample was thoroughly wetted. The strength 
was evaluated in accordance with TAPPI T 494 om-82. The measurements were 
carried out using a constant rate of elongation apparatus, i.e., a Finch 
wet strength device, which is described in TAPPI Procedure T 465 om-82 
(1982). The dry strength was evaluated in accordance with TAPPI T 494 
om-81.

EXAMPLE I 
This example describes the preparation of an acetal-containing derivative 
having the structure 
##STR10## 
and an aldehyde derivative having the structure 
##STR11## 
Part A 
Preparation of 5-Hydroxymethyl Furfuraldehyde Dimethyl Acetal 
##STR12## 
A total of 5.0 g. (0.039 mole) of 5-hydroxymethyl furfuraldehyde was 
dissolved in 150 ml. of anhydrous methanol and placed in 250 ml. round 
bottom flask equipped with magnetic stir bar and drying tube. One drop of 
concentrated hydrochloric acid was added and the solution was allowed to 
stir overnight. The reaction mixture was then neutralized with sodium 
carbonate, filtered, and the solvent removed under vacuum. The resulting 
red-brown oil was determined by NMR to be 98% acetal. 
Part B 
Modification of The 5-Hydroxymethyl Furfuraldehyde Dimethyl Acetal with 
Epichlorohydrin 
A total of 6.0 g. (0.035 mole) of 5-hydroxymethyl furfuraldehyde dimethyl 
acetal (HMFA) was added to 1.54 g. sodium hydroxide (0.038 mole) in a 100 
ml. round bottom flask equipped with magnetic stir bar, reflux condenser, 
and nitrogen inlet. After stirring for 30 mins., 3.89 g. (0.042 mole) of 
epichlorohydrin in 50 ml. of methyl ethyl ketone was added quickly, and 
the reaction mixture was allowed to reflux overnight under a nitrogen 
atmosphere. The resulting oil was mixed with 250 ml. of toluene, and the 
toluene was then distilled off at atmospheric pressure to remove any 
residual epichlorohydrin. The sample was freed of toluene by subjecting it 
to high vacuum overnight. 
Part C 
Preparation of The Acetal-Containing Starch Derivatives 
The following procedure was used to prepare the starch derivatives. A 
solution of 9.0 g. sodium sulfate (36% based on starch) was dissolved in 
40 ml. of distilled water and 0.375 g. sodium hydroxide (1.5% based on 
starch) was dissolved in the salt solution. A total of 25 g. of starch was 
added quickly and shaken to a uniform consistency. The indicated reagent 
was added and the container was sealed and placed in a tumbler and heated 
at 45.degree. C. for 30 hours. The starch slurry was cooled to room 
temperature and adjusted to pH 7.5 with HCl. The starch was then filtered, 
washed three times with 100 ml. of water and twice with 100 ml. 
isopropanol, and air dried. It was analyzed by titration. 
The reactions are summarized below: 
______________________________________ 
Cationic 
Starch Acetal NaOH Reaction 
CHO by 
Base* Reagent (%) (%) Time (hr.) 
Titration % 
______________________________________ 
waxy maize 
10 2.25 6 0.16 
waxy maize 
10 2.25 18 0.50 
waxy maize 
10 2.25 30 0.88 
______________________________________ 
*Treated with 3% dimethylaminoethyl chloride hydrochloride (DEC) prior to 
treatment with the acetal reagent. The DEC reaction was carried out 
according to the method described in Example III of U.S. Pat. No. 
4,243,479 issued Jan. 6, 1981 to M. M. Tessler. The starch contained 0.27 
N. 
Part D 
Preparation of The Aldehyde-Containing Starch Derivatives 
The starch acetals were converted to the corresponding aldehydes by 
slurrying the acetal in water (e.g., 100 parts of water/1 part of starch) 
and adjusting the pH to 2.5-3.0 with a dilute solution of hydrochloric 
acid. The starch acetals were cooked in a boiling water bath, prior to, 
after, or during the acidification to gelatinize the starch. The total 
cooking time was about 20 mins. The slurry was stirred during the acid 
addition and/or initial cooking. The cook was cooled rapidly. 
EXAMPLE II 
The cellulose acetal and aldehyde was prepared from alpha-cellulose and 
5-glycidoxy furfuraldehyde dimethyl acetal (GMFA) using 10% reagent on 
cellulose following the procedure described in Example I--Part C. The % 
CHO by titration was 0.15%. 
EXAMPLE III 
This example describes the preparation of an acetal-containing derivative 
having the structure 
##STR13## 
and an aldehyde-containing derivative having the structure 
##STR14## 
Part A 
Preparation of 4-Glycidoxybenzaldehyde Dimethyl Acetal 
##STR15## 
A 250 ml. three neck flask was equipped with magnetic stir bar, reflux 
condenser, addition funnel and nitrogen inlet. Dry nitrogen was swept 
through the apparatus while it was heated with a heat gun. After the 
apparatus was cooled, 5.95 g. of a 60% oil dispersion of sodium hydride 
(0.149 mole) was added and triturated three times with 25 ml. of petroleum 
ether to remove the oil. A solution of 36.6 g. (0.3 mole) 
4-hydroxybenzaldehyde in 100 ml. of tetrahydrofuran was added dropwise to 
the sodium hydride over 30 mins. When the addition was complete, 1.1 g. 
(0.0003 mole) tert-butyl ammonium iodide was added along with 30.7 g. 
(0.33 mole) epichlorohydrin. The reaction mixture was refluxed overnight, 
cooled, filtered, and the solvent removed under vacuum. Excess 
epichlorohydrin was removed by azeotropic distillation using a ten fold 
excess of toluene. Yield was 40% of 4-glycidoxy benzaldehyde. 
A total of 8.5 g. (0.0477 mole) of the above aldehyde and 8.5 g. (0.0574 
mole) of triethylorthoformate was then added to a 50 ml. round bottom 
flask equipped with magnetic stir bar and reflux condenser. A solution of 
0.25 g. (0.003 mole) ammonium nitrate was dissolved in 5 ml. of warm 
ethanol and added rapidly to the reaction mixture. The mixture was stirred 
for 6 hrs. at room temperature, neutralized with excess sodium carbonate, 
filtered, and the solvent removed under vacuum. The resulting oil (100% 
yield) had no residual aldehyde as determined by NMR. No further 
purification was needed. 
Part B 
Preparation of Guar Gum Acetal and Aldehyde 
To 2 ml. of sodium hydroxide (20% solution) in a solution of 80% 
acetone/20% water were added 3.0 g. of 5-glycidoxymethyl furfuraldehyde 
dimethyl acetal (12% Reagent based on gum). Then 25 g. of guar gum was 
mixed in rapidly. The reaction mixture was refluxed for 4 hours, HCl was 
added quickly, and the product was filtered. The filter cake was washed 
three times with 100 ml. of acetone, then three times with 100 ml. of 
acetone/water (1:1), and finally three times with 100 ml. of acetone. The 
cake was air dried overnight and analyzed by titration. It contained 0.88% 
CHO as determined by titration. 
EXAMPLE IV 
The following charts show a list of the reagents (Chart A) which, when 
reacted, will give aromatic reaction products that can then be reacted 
with polysaccharides (e.g., starch, gum, and cellulose) using the 
indicated procedure polysaccharide shown in Chart B should result. 
Conversion to the polysaccharide aldehyde should occur upon acidification. 
CHART A 
__________________________________________________________________________ 
Reagents Reaction Product 
__________________________________________________________________________ 
##STR16## 
##STR17## 
##STR18## 
##STR19## 
##STR20## 
##STR21## 
##STR22## 
##STR23## 
##STR24## 
##STR25## 
##STR26## 
##STR27## 
##STR28## 
##STR29## 
##STR30## 
##STR31## 
__________________________________________________________________________ 
(1) Tetrahydrofuran, reflux 18 hrs. 
(2) Methanol, 5.degree. C. to room temperature, 4 hrs. 
(3) Trace ptoluenesulfonic acid 
(4) Methylethyl ketone, reflux 18 hrs. 
CHART B 
__________________________________________________________________________ 
Reaction Product Polysaccharide Acetal 
__________________________________________________________________________ 
##STR32## 
##STR33## 
##STR34## 
##STR35## 
__________________________________________________________________________ 
(1) Acetone, reflux 4 hrs., 2% NaOH based on polysaccharide 
(2) Water, 24 hrs., 45.degree. C., 2% NaOH based on polysaccharide, 30% 
Na.sub.2 SO.sub.4 based on polysaccharide 
EXAMPLE V 
This example describes the direct preparation of an aldehyde-containing 
starch derivative. 
Part A 
Preparation of 5-Chloromethyl-2-Anisaldehyde (CMAA) 
##STR36## 
A total of 34 g (0.25 moles) of o-anisaldehyde was dried to a two-necked 
250 ml. round bottom flask equipped with an overhead stirrer. To this was 
added 150 ml. concentrated HCl and 13.5 g. paraformaldehyde (0.15 moles). 
The reaction mixture was stirred at room temperature for 48 hrs. The 
precipitated benzyl chloride was filtered off, washed with water several 
times, resuspended in methylene chloride, washed with 100 ml. of 0.5% 
NaHCO.sub.3 solution three times, and then with water until neutral. It 
was dried under vacuum. The yield was 87%. The .sup.13 C NMR and 'H NMR 
analyses were consistant with the above structure (C.sub.9 H.sub.9 O.sub.2 
Cl). 
Part B 
Preparation of The Starch Derivative 
##STR37## 
To a three necked 500 ml. round bottom flask equipped with a stirrer, 
heating mantel, and condenser were added 150 ml. distilled water, 30 g. 
sodium sulfate, and 0.8 g. sodium hydroxide (0.02 mole). The mixture was 
stirred for about 5 minutes, and 100 g. corn starch were added. The pH was 
about 11.5. 
A total of 10 g. of the 5-chloromethyl-2-anisaldehyde was weighed in a 100 
ml beaker and 45 ml. of tetrahydrofuran were added. The solution was added 
dropwise to the starch slurry with mixing. No pH change was observed after 
stirring for 10 min. at room temperature. The reaction mixture was heated 
to 50.degree. C. The pH slowly dropped but was maintained above 11.0 by 
the slow addition of 3% NaOH. After 20 minutes the pH remained constant at 
11.1-11.9. The slurry was maintained at 50.degree. C. with stirring 
overnight. The starch was recovered by adjusting the pH to 7.0 with 3% 
HCl, filtering, resuspending the cake, and filtering three times using 200 
ml. of water. The product was then washed twice with 200 ml. of acetone 
and air dried overnight. 
EXAMPLE VI 
This examples describes the direct preparation of an aldehyde-containing 
starch derivative by reaction of starch with 5-chloromethyl furfuraldehyde 
to give 
##STR38## 
To a 1 l. three neck flask equipped with an overhead stirrer and 
additional funnel was added a slurry of 100 g. of corn starch in 190 ml of 
anhydrous acetone. Sodium hydroxide (2.5g.-0.0625 mole) was dissolved in 
enough water (10 ml) to account for 5% of the total solvent volume. The 
solution of sodium hydroxide was then added to the acetone slurry with 
vigorous stirring. Pure 5-chloromethyl furfuraldehyde (5.0 g.) (prepared 
according to the procedure described in the article "An Improved Method 
For The Conversion of Saccharides Into Furfural Derivative" by Kazuhiko 
Hamada et al. reported in Chemistry Letters, pp. 617-618, 1982) was added 
quickly to the mixture and the mixture was allowed to stir overnight. The 
reaction mixture was then dumped into 1 l. of water at pH 3. The pH of 
this slurry, which was about 11.5, was adjusted to 7.0-8.0 with dilute 
HCl. The starch derivative was recovered by filtration, washed three times 
with 200 ml. of water, twice with 200 ml. of isopropanol, and then air 
dried. Analysis by titration showed 0.53% CHO (53% reaction efficiency). 
EXAMPLE VII 
The following chart (C) shows a list of reactants which, when reacted, will 
give aromatic aldehyde-containing reagents of the type used in Example IV 
that can be reacted with polysaccharide (e.g., starch, gum, and 
cellulose). The indicated polysaccharide aldehyde should result. 
EXAMPLE VIII 
This example describes the crosslinking of the derivatives of Examples I, 
IV, and VI using various polyethyleneimines (PEI), diethylene triamine 
(DETA), 2,5-hexanedione (HD), and adipic dihydrazide (ADIH). The 
derivatives were cooked for 20 minutes at the indicated pH in a boiling 
water bath to disperse the starch. In the case of the GMFA derivatives 
cooked at pH 2.5 the acetal was thus converted to the aldehyde. The 
results are shown in Table I. 
CHART C 
__________________________________________________________________________ 
Aldehyde-Containing 
Reactants Reaction Product 
Polysaccharide 
__________________________________________________________________________ 
Aldehyde 
##STR39## 
##STR40## 
##STR41## 
##STR42## 
m-Nitrobenzaldehyde 
##STR43## 
##STR44## 
##STR45## 
##STR46## 
Benzaldehyde 
##STR47## 
##STR48## 
##STR49## 
##STR50## 
and/or and/or 
##STR51## 
##STR52## 
__________________________________________________________________________ 
(1) Room temperature, 48 hrs. 
(2) ZnCl.sub.2, 60.degree. C., 20 mins. 
(3) H.sub.3 PO.sub.4 syrupy, CH.sub.3 COOH glacial, 100.degree. C., 4.5 
hrs. 
TABLE I 
______________________________________ 
Appearance of Cook 
Corn After After 
Starch Addition 
Standing 
Treated Crosslinking of Over- 
with pH Initiator Initial 
Crosslinker 
night 
______________________________________ 
GMFA 2.5 PEI Creamy Gel Gel 
(Mw=1200) 
GMFA 2.5 PEI Creamy Gel Gel 
(Mw=10,000) 
GMFA 2.5 PEI Creamy Gel Gel 
(Mw=60,000) 
GMFA 2.5 DETA Creamy Gel Gel 
GMFA 2.5 HD Creamy Creamy Gel 
CMAA 2.5 PEI Creamy Gel Gel 
(Mw=60,000) 
GMFA 2.5 ADIH Creamy Gel Gel 
GMFA 7.0 PEI Creamy Gel Gel 
(Mw=60,000) 
CMF 7.0 PEI Creamy Gel Gel 
(Mw 60,000) 
GMFA 9.0 PEI Creamy Gel Gel 
(Mw=60,000) 
GMFA 11.0 PEI Creamy Creamy Creamy 
(Mw=60,000) 
______________________________________ 
GMFA indicates 5glycidoxymethyl furfuraldehyde dimethyl acetal 
CMAA indicates 5chloromethyl-2-anisaldehyde 
CMF indicates 5chloromethyl-2-furfuraldehyde 
The results show that polyethyleneimines varying in molecular weight from 
1200-60,000 were effective as crosslinkers as were diethylene triamine an 
adipic dihydrazide. The results also show that hexanedione was effective 
as crosslinker but that the crosslinking did not occur as rapidly. The 
results further show that the GMFA derivative can be crosslinked while in 
the acetal form at pH 7-9, but not at pH 11. 
EXAMPLE IX 
This examples describes the wet and dry tensile strength provided by the 
cationic aromatic aldehydes. The aldehydes were evaluated for tissue 
applications. 
The cationic aromatic acetal starch derivative of Example I (waxy maize 
starch treated with 3% DEC and 10% GMFA). The starch derivatives was jet 
cooked at 270.degree. C. and pH 2.5 to disperse the starch and convert the 
acetal to the aldehyde. For comparison, a cationic non-aromatic 
acetal-containing derivative, i.e., a waxy maize starch treated with 3% 
DEC and 10% N-2,2-dimethoxyethyl)-N-methyl-2-chloroacetamide (DMCA), was 
evaluated. The starch was likewise dispersed and the acetal groups 
converted to the aldehyde groups. Also evaluated was a synthetic polymer. 
A polyethyleneimine (PEI) crosslinker (mol. wt. 60,000) was used with the 
aromatic acetal starch derivative. It was added to the pulp at 30 lb./ton 
after the starch dispersion and just before the headbox. The starch and 
polymer dispersions were then added to the paper furnish at 10 lb./ton. 
The furnish was a bleached softwood Kraft. The paper sheets were prepared 
on the Noble and Wood Sheet Mold. The paper weight was about 5 lb./1000 
ft..sup.2. The wet and dry tensile strength results are shown in Table II. 
The wet web strength results are shown in Table III. 
TABLE II 
______________________________________ 
Dry Wet Tensile 
Tensile 
Strength De- 
Strength 
5 sec. 30 min. cay 
Sample B.L. (m.) 
B.L. (m.) (%) 
______________________________________ 
Cationic Starch 5480 220 123 55 
(Control - No Aldehyde 
Groups) 
Cationic Aromatic Aldehyde- 
5103 257 232 10 
Containing Starch Derivative 
(Control - Aldehyde Groups 
but No Crosslinker)* 
Cationic Aromatic Aldehyde- 
6029 1085 1075 1 
Containing Starch Derivative* 
Crosslinked with PEI 
Cationic Non-Aromatic 
5288 931 322 65 
Aldehyde-Containing Starch 
Derivative** (comparative) 
Synthetic Polymer*** 
5092 1194 1134 5 
(comparative) 
______________________________________ 
*Waxy maize treated with 3% DEC and 10% GMFA. 
**Waxy maize treated with 3% DEC and 10% DMCA. 
***Kymeme/Dowstrength a synthetic acrylamide. 
The results show that the crosslinked starch derivative provided permanent 
wet tensile strength (decay of only 1%) whereas the same derivative which 
had not been crosslinked provided very little wet strength. The 
crosslinked starch dervative was superior to the synthetic polymer in dry 
tensile strength (6029 vs. 5092) and decay (1% vs. 5%) but slightly lower 
in wet tensile strength (1085 vs. 1194 at 30 min.). 
A comparison of the aromatic aldehyde-containing starch derivative (used 
with no crosslinker) and the non-aromatic aldehyde-containing derivative 
shows that the aromatic derivative provided comparable dry tensile 
strength (5103 vs. 5288) but significantly less wet tensile strength (257 
vs. 931 after 5 sec. and 232 vs. 322 after 30 min.) than the non-aromatic 
derivative. The use of the crosslinker provided permanent wet tensile 
strength. 
TABLE III 
__________________________________________________________________________ 
Dry 
Tensile 
No. of Presses - % Moisture 
Strength 
Sample 1st-66% 
2nd-63% 
3rd-40% 
4th-31% 
5th-24% 
(lb./in.) 
__________________________________________________________________________ 
Blank 738 713 3106 5905 8625 
53482 
Cationic Aromatic Alde- 
728 827 7778 11993 
27282 
77977 
hyde-Containing Starch 
Derivative crosslinked 
with PEI 
Cationic Non-Aromatic 
663 718 4087 8129 18830 
87617 
Aldehyde-Containing 
Starch Derivative** 
(comparative) 
__________________________________________________________________________ 
*Waxy maize treated with 3% DEC 
**Waxy maize treated with 3% DEC 
The results show that the crosslinked aromatic aldehyde-containing starch 
derivative provided superior wet web strength at moisture contents below 
63%. The non-aromatic aldehyde-containing starch derivative showed lower 
wet web strength which was not significantly better than the blank until 
the 40% moisture level was reached. 
EXAMPLE X 
This example illustrates the water-resistant properties of bonds formed 
with corrugating adhesives prepared using a granular (i.e., non-dispersed) 
aromatic aldehyde-containing starch derivative as the uncooked portion of 
a corrugating adhesive. 
Preparation of The Carrier Starch 
To 2835.6 g of water was added 1360 g. of corn starch. The resultant slurry 
was heated to 72.degree. C. with stirring. About 238.6 g. of water 
containing 108.8 g. of sodium hydroxide was then added to the slurry and 
heating was continued for about 15 minutes, after which about 2835.6 g. of 
water was added to cool and dilute the resultant dispersion. 
Preparation of The Full-Formulation Adhesive 
The carrier starch dispersion prepared above was added over a 20-minute 
period to a slurry of 4760 g. of the aromatic aldehyde-containing corn 
starch derivative, 108.8 g. borax (Na.sub.2 B.sub.4 O.sub.7.10H.sub.2 O) 
and 8506.8 g water. The acetal-containing corn starch derivative (prepared 
using the procedure of Example I and 10% GMFA) was converted to the 
aldehyde in granular form by maintaining the 10% starch slurry at 
35.degree. C. and pH 2.2 for 18 hours. The carrier starch/granular starch 
mixture was stirred for 30 minutes. The starch aldehyde was used in 
combination with polyethyleneimine (mol. wt. 60,000) as the crosslinker 
(1% based on starch on a dry basis). The acetal-containing corn starch 
derivative. 
The adhesive was employed in the preparation of a double-faced bond in 
corrugated paperboard via the following method which simulates conditions 
on the double-back section of a corrugator. The adhesive was applied at 6 
mil thickness by a Bird applicator to a glass plate and was transferred to 
sheets of single-face web (of 62 lb./1000 ft..sup.2 (0.302 kg./m..sup.2) 
wet strength liner and 30 lb./1000 ft..sup.2 (0.146 kg./m..sup.2) wet 
strength medium) by means of direct hand pressure. The single-face samples 
were then placed on top of 62 lb./1000 ft..sup.2 (0.302 kg./m..sup.2) wet 
strength liner and the resultant double-faced board was bonded at 0.25 psi 
on a hot plate at 177.degree. C. for 4 seconds. The bonded boards were 
then placed in a conditioning atmosphere of 22.degree. C., 50% relative 
humidity for 24 hours, after which 2.times.4 inch samples of each of the 
boards were placed in water at 22.degree. C. for the indicated time. 
At the end of this period the samples were evaluated by a wet pin adhesion 
test based on that of the TAPPI Standard UM 802 (formerly R 337) using a 
Hinde and Dauch Crush Tester obtainable from Testing machines 
Incorporated, Mineola, N.Y. The test results were recorded in pounds (per 
8 sq. in. of board sample at the point of initial bond failure of the 
double-face liner from the single-face web. 
The results are shown in Table IV. 
TABLE IV 
______________________________________ 
Raw Portion 1 hr. 4 hr. 17 hr. 
24 hr. 
______________________________________ 
Corn Blank 0 0 0 0 
Corn/GMFA/PEI 7 6 5 5 
______________________________________ 
The results indicate that only the adhesive based on the 
aldehyde-containing starch derivative exhibited water resistance. 
EXAMPLE XI 
This example illustrates that adhesive bonds can be formed using the 
aromatic aldehyde-containing starch derivative. This indicates that the 
derivative can also be used as the cooked portion of a corrugating 
adhesive. 
Preparation of The Cooked Starch 
The indicated starch was slurried in distilled water at 10% solids and the 
pH of the slurry adjusted to 2.5. The starch was cooked for 20 minutes in 
a boiling water bath, quickly cooled to room temperature and the pH 
readjusted to desired value (typically 5 to 13). Films were drawn using a 
0.0015 inch applicator. The indicated cross-linking material was added to 
the starch cook directly before application of the adhesive film. The 
paper used was 62 lb./1000 ft..sup.2 wet strength liner board and 30 
lb./1000 ft..sup.2 medium. The film was applied to the medium and the 
liner board was pressed to the medium between two glass plates for 30 
seconds. The single face sample was cured by placing it on a hot plate 
preheated to 177.degree. C. (350.degree. F.) for 5 seconds. The samples 
were cooled, dried overnight, and soaked in distilled water for the 
indicated amount of time. The joint was pulled apart by hand and evaluated 
for fiber tear. The results are shown in Table V. 
TABLE V 
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Cooked Tear 
at pH after Tear Tear 
2.5 and Soak after after 
Sample 
adjusted to 
Cross- Time Soak Time 
Soak Time 
No. pH linker of 5 min. 
of 1 hr. 
of 24 hr. 
______________________________________ 
1 8.3 -- paper rip 
None N.D. 
2 5.0 -- N.D. paper rip 
None 
3 8.3 DETA fiber tear 
slight fiber 
N.D. 
tear 
4 5.0 DETA N.D. fiber tear 
slight fiber 
tear 
5 8.3 PEI paper rip 
slight fiber 
N.D. 
tear 
6 5.0 PEI N.D. fiber tear 
slight fiber 
tear 
______________________________________ 
DETA--diethylene triamine 
PEI--polyethyleneimine (mol. wt. 1200) 
N.D.--not determined 
The results show that no permanent water-resistance is imparted when the 
crosslinker is absent. The results show that the use of the polyamine 
crosslinkers DETA and PEI imparted permanent water-resistance under both 
alkaline and acid conditions. 
Now that the preferred embodiments of the invention have been described in 
detail, various modifications and improvements thereon will become readily 
apparent to those skilled in the art. Accordingly, the spirit and scope of 
the present invention are to be limited only by the appended claims and 
not by the foregoing specification.