U.S. patent number RE29,960 [Application Number 05/881,843] was granted by the patent office on 1979-04-10 for method of sizing paper.
This patent grant is currently assigned to National Starch and Chemical Corp.. Invention is credited to Walter Maliczyszyn, Emil D. Mazzarella, Leonard J. Wood, Jr..
United States Patent |
RE29,960 |
Mazzarella , et al. |
April 10, 1979 |
**Please see images for:
( Certificate of Correction ) ** |
Method of sizing paper
Abstract
A size mixture comprising a substituted cyclic dicarboxylic acid
anhydride and polyoxyalkylene alkyl or alkylaryl ether or the
corresponding mono- or di-ester is used to size paper products. In
accordance with a preferred embodiment the liquid size mixture is
added directly to the paper stock system without prior
emulsification.
Inventors: |
Mazzarella; Emil D.
(Mountainside, NJ), Wood, Jr.; Leonard J. (Berkeley Heights,
NJ), Maliczyszyn; Walter (Somerville, NJ) |
Assignee: |
National Starch and Chemical
Corp. (Bridgewater, NJ)
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Family
ID: |
27103096 |
Appl.
No.: |
05/881,843 |
Filed: |
February 27, 1978 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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535443 |
Dec 23, 1974 |
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471230 |
May 20, 1974 |
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Reissue of: |
683405 |
May 5, 1976 |
04040900 |
Aug 9, 1977 |
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Current U.S.
Class: |
162/158; 162/184;
427/391 |
Current CPC
Class: |
D21H
17/53 (20130101); D21H 17/15 (20130101) |
Current International
Class: |
D21H
17/15 (20060101); D21H 17/00 (20060101); D21H
17/53 (20060101); D21D 003/00 () |
Field of
Search: |
;162/158,184
;260/346.8R,346.3 ;252/312 ;427/391 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Schwartz, "Surface Active Agents and Detergents", vol. II, p.
121..
|
Primary Examiner: Bashore; S. Leon
Assistant Examiner: Chin; Peter
Attorney, Agent or Firm: James & Franklin
Parent Case Text
This application is a continuation-in-part of our copending U.S.
Application, Ser. No. 535,443 filed Dec. 23, 1974 which application
is a continuation-in-part of U.S. application Ser. No. 471,230
filed May 20, 1974, both now abandoned.
Claims
What is claimed is:
1. A method for sizing paper products comprising the steps of
1. providing a paper stock system;
2. forming, in the absence of high shearing forces and under normal
pressures, a sizing emulsion consisting essentially of:
a. from 80 to 97 parts of substituted cyclic dicarboxylic acid
anhydride corresponding to the formula ##STR5## wherein R
represents a dimethylene or trimethylene radical and wherein R' is
a hydrophobic group containing more than 5 carbon atoms which may
be selected from the class consisting of alkyl, alkenyl, aralkyl,
or aralkenyl groups; ##STR6## wherein R.sub.x is an alkyl radical
containing at least 4 carbon atoms and R.sub.y is an alkyl radical
containing at least 4 carbon atoms, and R.sub.x and R.sub.y are
interchangeable; ##STR7## wherein R.sub.x is an alkyl radical
containing at least 5 carbon atoms and R.sub.y is an alkyl radical
containing at least 5 carbon atoms and R.sub.x and R.sub.y are
interchangeable;
b. from 3 to 20 parts of a polyoxyalkylene alkyl or polyoxyalkylene
alkyl-aryl ether or the corresponding mono- or diester selected
from the group consisting of: ##STR8##
wherein x and n are integers in the range of 8 to 20; R is an aryl
radical; m is an integer in the range of 5 to 20; and i is 0 or 1;
and
3. forming a web from the paper stock system .[.change.].
.Iadd. c. water; .Iaddend.
4. intimately dispersing said emulsion within the paper stock
either before or after formation of said web but prior to passing
said web through the drying stage of the paper making operation in
an amount sufficient to provide a concentration of the substituted
cyclic dicarboxylic acid anhydride of from 0.1 to 2.0%, based on
dry fiber weight.
2. The method of claim .[.2.]. .Iadd.1 .Iaddend.wherein the sizing
emulsion is formed in situ within the paper stock system.
3. The method of claim 1 wherein the sizing emulsion is formed
prior to introduction into the paper stock system.
4. The method of claim 3 wherein the size mixture is emulsified
with water in a sufficient quantity to yield an emulsion containing
the substituted cyclic dicarboxylic acid anhydride in a
concentration of from 0.1 to 20%, by weight of the total emulsified
size mixture, prior to addition to the paper stock system.
5. The method of claim 3 wherein the size mixture in the form of an
aqueous emulsion is sprayed onto the formed web prior to the drying
operation.
6. The method of claim 1 wherein there is dispersed within the
paper stock prior to the conversion of the paper stock into a dry
web at least 0.01%, based on dry fiber weight, of a cationic
retention agent.
7. The method of claim 1 wherein the sizing emulsion is formed with
a polyoxyalkylene alkyl-phenyl ether selected from the group
consisting of: ##STR9## wherein n is an integer in the range of 8
to 20; m is an integer in the range of 5 to 20; and i is 0 or 1.
Description
BACKGROUND OF THE INVENTION
I. Field of the Invention
This invention relates to an improved method for the sizing of
paper products. More particularly, the invention relates to an
improved method for sizing paper and paperboard products under
specified conditions using a mixture comprising hydrophobic
substituted cyclic dicarboxylic acid anhydrides and specific
polyoxyalkylene alkyl or alkyl-aryl ethers or the corresponding
mono- or di-esters. The invention also has as a preferred
embodiment a method for sizing paper products directly in the paper
stock preparation system without the need for prior emulsification
of the size agent.
As used herein, the term "paper and paperboard" includes sheet-like
masses and molded products made from fibrous cellulosic materials
which may be derived from both natural and synthetic sources. Also
included are sheet-like masses and molded products prepared from
combinations of cellulosic and non-cellulosic materials derived
from synthetics such as polyamide, polyester and polyacrylic resin
fibers as well as from mineral fibers such as asbestos and
glass.
II. Brief Description of the Prior Art
It is recognized that paper and paperboard are often sized with
various hydrophobic materials including, for example, rosin, wax
emulsions, mixtures of rosin with waxes, ketene dimers, isocyanate
derivatives, fatty acid complexes, fluorocarbons, certain
styrene-maleic anhydride copolymers, as well as the substituted
cyclic dicarboxylic acid anhydrides more particularly described
hereinafter. These materials are referred to as sizes or sizing and
they may be introduced during the actual paper making operation
wherein the process is known as internal or engine sizing. On the
other hand, they may be applied to the surface of the finished web
or sheet in which case the process is known as external or surface
sizing.
In order to obtain good sizing with any of the previously described
sizing compounds, it is desirable that they be uniformly dispersed
throughout the fiber slurry in as small a particle size as is
possible to obtain. In accordance with the known methods of adding
these sizing compounds to the paper stock prior to web formation,
therefore, the sizing compound is added in the form of an aqueous
emulsion prepared with the aid of emulsifying agents including, for
example, cationic or ordinary starches, carboxymethyl cellulose,
natural gums, gelatin, cationic polymers or polyvinyl alcohol, all
of which act as protective colloids.
These prior art techniques which utilized emulsifying agents with
or without added surfactants did, however, suffer from several
inherent deficiencies in commercial practice. A primary deficiency
concerned the necessity of utilizing relatively complex, expensive
and heavy equipment capable of exerting high homogenizing shear
and/or pressures, together with rigid procedures regarding
emulsifying proportions and temperatures, etc., for producing a
satisfactory stable emulsion of the particular size. Additionally,
the use of many surfactants in conjunction with protective colloids
was found to create operational problems in the paper making
process such as severe foaming of the stock and/or loss in
sizing.
With particular reference to the procedures of the prior art which
utilized substituted cyclic dicarboxylic acid anhydrides as sizing
agents, it has been necessary in commercial practice to
pre-emulsify with cationic starch or other hydrocolloids using
relatively rigid procedures with elevated temperatures to cook the
starch or hydrocolloids and high shearing and/or high pressure
homogenizing equipment. Unless these complicated procedures are
carefully followed, the methods result in process difficulties such
as deposition in the paper system, quality control problems and
generally unsatisfactory performance.
Although it has been proposed to use such surfactants as
polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitol
hexaoleate or polyoxyethylene sorbitol oleatelaurate, the use
thereof as sole emulsifying agents has not proved satisfactory
since it has not been possible to form a stable, small size
particle emulsion and/or the emulsion did not produce sufficient
sizing performance. Moreover, in some instances, the resultant
emulsion detrimentally affected other properties of the size paper,
for example, loss of wet strength. Another drawback noted with
various emulsions prepared with certain surfactants, is
demonstrated where on aging of the treated paper, many small
hydrophilic spots were formed as evidenced by an ink dip test.
Thus, the use of these surfactants together with the substituted
cyclic dicarboxylic acid anhydrides has been limited to very minor
amounts used only in conjunction with protective colloids and under
rigorously controlled conditions.
There is thus a need in the art for a method for sizing paper and
paperboard products which will eliminate the difficult procedures
and complex high shear homogenizing equipment now required for
producing an emulsion and will result in more flexibility in
preparing and handling the size mixture. There is also a need for a
method for producing emulsions of smaller particle size and
superior functionality in the paper making process to those
prepared by the methods of the prior art, the use of which will
result in improved sizing performance and improved operability.
SUMMARY OF THE INVENTION
In accordance with the method of the present invention, a size
mixture is prepared by combining 80-97 parts, preferably 90-95
parts, by weight, of at least one substituted cyclic dicarboxylic
acid anhydride and 3-20 parts, preferably 5-10 parts, by weight, of
a polyoxyalkylene alkyl or polyoxyalkylene alkyl-aryl ether or the
corresponding mono- or di-ester. These size mixtures are easily
emulsifiable with water in the absence of high shearing forces and
under normal pressure by merely stirring, passing through a mixing
valve or common aspirator or by the usual agitation present in a
stock preparation system. By stating that these components are
emulsified in the absence of high shearing forces is meant that the
use of high shearing forces such as are present in Waring blenders,
turbine pumps, or other extremely high speed agitators etc. are not
required; the use of normal pressures means that such pressures as
are found in piston or other types of homogenization equipment are
also not required. At least one of the latter techniques was
required in forming emulsions in accordance with prior art
teachings. The emulsion thus produced in accordance with the
process of our invention is adequately stable for commercial
purposes and possesses a sufficiently small particle size to
produce excellent sizing of the resultant web.
In carrying out the present invention the emulsion, formed in the
absence of high shearing forces and under normal pressures, is
intimately dispersed within the paper stock system prior to its
passing through the drying stage of the paper making operation in
an amount sufficient to provide a concentration of the substituted
cyclic dicarboxylic acid anhydride of from 0.01 to 2.0% based on
dry fiber weight. In accordance with the embodiments of the
invention, the sizing emulsion may be formed prior to introduction
into the paper stock system or the emulsion may be formed in situ
within the paper stock system in the presence of good agitation at
any point during preparation thereof.
In accordance with the latter and preferred embodiment, the size
mixtures disclosed herein may be used in the sizing method without
any prior emulsification step. In accordance with this variation,
the components are premixed without water and added to the paper
stock preparation system at any point during preparation where good
agitation can be achieved. It has been found that the required
degree of "good agitation" is achieved when passing through
refiners, pumps and other operating equipment, thereby producing
the emulsion in situ and excellent sizing properties in the
resultant sized web.
It is a feature of the present invention that the resultant
emulsions of the specific size mixtures are characterized by a
smaller particle size than is generally achieved by the methods of
the prior art. Additionally, the use of the size mixtures and
method of the present invention result in significantly improved
sizing performance (i.e. improved sizing is achieved with a given
concentration of size), and also results in the improved
operability as evidenced by reduced build-up of fiber and sizing
agent on the press rolls of the paper machine.
It is another feature of the compositions and method of the present
invention that the resultant sized paper product is characterized
by reduced water and ink absorption as well as by increased
resistance to aqueous acid and alkaline solutions.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The sizing compounds contemplated for use in our size mixtures are
substituted cyclic dicarboxylic acid anhydrides. More specifically,
the sizing compounds correspond to the following structural
formulas: ##STR1## wherein R represents a dimethylene or
trimethylene radical and wherein R' is a hydrophobic group
containing more than 5 carbon atoms which may be selected from the
class consisting of alkyl, alkenyl, aralkyl, or aralkenyl groups;
##STR2## wherein R.sub.x is an alkyl radical containing at least 4
carbon atoms and R.sub.y is an alkyl radical containing at least 4
carbon atoms, and R.sub.x and R.sub.y are interchangeable; and
##STR3## wherein R.sub.x is an alkyl radical containing at least 5
carbon atoms and R.sub.y is an alkyl radical containing at least 5
carbon atoms and R.sub.x and R.sub.y are interchangeable.
Specific examples of sizing compounds falling within structure (A)
include iso-octadecenyl succinic acid anhydride, n-hexadecenyl
succinic acid anhydride, dodecenyl succinic acid anhydride, dodecyl
succinic acid anhydride, decenyl succinic acid anhydride, octenyl
succinic acid anhydride, triisobutenyl succinic acid anhydride,
etc. Sizing compounds in which R' contains more than twelve carbon
atoms are preferred. The sizing compounds of structure (A) are
fully described in U.S. Pat. No. 3,102,064 issued Aug. 27,
1963.
Specific examples of sizing compounds falling within structure (B)
include (1-octyl-2-decenyl)-succinic acid anhydride and
(1-hexyl-2-octenyl)-succinic acid anhydride. The sizing compounds
of structure (B) are fully described in U.S. Pat. No. 3,821,069
assigned to the assignees of the present invention.
Specific examples of sizing compounds falling within structure (C)
include those non-polymeric sizes prepared by the reaction of
maleic acid anhydride with vinylidene olefins such as
2-n-hexyl-1-octene, 2-n-octyl-1-dodecene, 2-n-octyl-1-decene,
2-n-dodecyl-1-octene, 2-n-octyl-1-octene, 2-n-octyl-1-nonene,
2-n-hexyl-decene and 2-n-heptyl-1-octene. The sizing compounds of
structure (C) are fully described in copending application assigned
to the assignees of the present invention, Ser. No. 569,816 filed
Apr. 21, 1975.
The polyoxyalkylene alkyl or polyoxyalkylene alkyl-aryl ethers or
corresponding mono- or di-esters useful herein comprise
polyoxyethylene or polyoxypropylene alkyl and alkyl-aryl ethers or
esters containing five to twenty polyoxyethylene (or
polyoxypropylene) units wherein the alkyl radical contains from
eight to twenty carbon atoms and the aryl radical is preferably
phenyl. The specific ethers or mono- or di-esters used in the
present invention are those derived from polyoxyethylene or
polyoxypropylene diols in which one or both of the terminal
hydroxyl groups are etherified or esterified. The generic formulae
of the compounds operable in the invention are: ##STR4##
wherein x and n are integers in the range of 8 to 20; R is an aryl
radical; m is an integer in the range of 5 to 20; and i is 0 or
1.
The preparation of these materials is also known to those skilled
in the art. Typical commercially available products useful in the
method of this invention include Renex 690 sold by ICI America,
Incorporated, Wilmington, Delaware; Triton X-100, Triton X-101,
Triton X-165 and Triton N-57 sold by Rohm and Haas Company,
Philadelphia, Pennsylvania; Tergitol NP-27, Tergitol NP-33 and
Tergitol TMN sold by Union Carbide Corporation, New York, New York;
and Igepal CO-630 sold by GAF Corporation, New York, New York as
well as PEG 400 Mono-oleate supplied by Finetex, Incorporated and
PEG 600 Dilaurate sold by Armak Chemical Division of Akzona,
Inc.
In accordance with the method of this invention, the size mixture
is formed by mixing 80 to 97 parts by weight, preferably 90 to 95
parts, of the aforementioned substituted cyclic dicarboxylic acid
anhydride with 3 to 20 parts, preferably 5 to 10 parts, of the
selected polyoxyalkylene alkyl or alkyl-aryl ethers or esters. The
use of the latter component in excess of about 15-20 parts becomes
uneconomical in terms of cost since much of the material may be
wasted, while amounts in excess of about 20 parts may even be
detrimental in terms of the papermaking operation.
It is to be recognized that mixtures of various combinations of
substituted cyclic dicarboxylic acid anhydrides and/or
polyoxyalkylene alkyl or alkyl-aryl ethers or esters may be used in
preparing a particular size mixture, as long as they fall within
the scope of this invention.
If pre-emulsification of the size mixture is desired, it may be
readily accomplished by adding the sizing components to water in
sufficient quantity so as to yield an emulsion containing the
substituted cyclic dicarboxylic acid anhydride in a concentration
of from about 0.1 to 20% by weight. The aqueous mixture is
thereafter sufficiently emulsified merely by stirring with moderate
speed agitation or by passing it through a mixing valve, aspirator
or orifice so that the average particle size of the resultant
emulsion will be less than about 3 microns. It is to be noted that
in preparing the emulsion, it is also possible to add the
components of the size mixture to the water separately, and that
the emulsion may be prepared using continuous or batch methods.
Emulsification of the mixture readily occurs at ambient
temperatures and no advantage is found in elevating the mixture
above about 25.degree. C. and, in fact, higher temperatures are to
be avoided due to the possibility of hydrolysis of the anhydride.
Thus, the emulsification will occur directly in cold water and
heating of the water prior to addition of the sizing mixture is
unnecessary and can even be detrimental.
As to actual use, no further dilution of the emulsion is generally
necessary. The thus-prepared emulsion is simply added to the wet
end of the paper making machine or to the stock preparation system
so as to provide a concentration of the substituted cyclic
dicarboxylic acid anhydride of from about 0.01 to about 2.0% based
on dry fiber weight. Within the mentioned range, the precise amount
of size which is to be used will depend for the most part upon the
type of pulp which is being treated, the specific operating
conditions, as well as the particular end use for which the paper
product is destined. For example, paper which will require good
water resistance or ink holdout will necessitate the use of a
higher concentration of size than paper which will be used in
applications where these properties are not critical.
In another embodiment of this invention, instead of adding the size
emulsion to the stock preparation system, the size emulsion may be
sprayed onto the surface of the formed web at any point prior to
the drying step. In accordance with this embodiment, the emulsion
is used in the concentrations as prepared and is sprayed onto the
web so as to provide the required size concentration.
In accordance with a preferred embodiment of the present invention,
the ingredients of the size mixture may be premixed without water
and added to the paper making stock system. In this case, the
substituted cyclic dicarboxylic acid anhydride will then emulsify
in situ in the stock preparation system without the need for prior
emulsification in water. As in the case in which the size is
emulsified prior to use, the amount of size employed will vary
depending on conditions, however, it will generally be within the
range of about 0.01 to 2.0% substituted cyclic dicarboxylic acid
anhydride based on dry fiber weight.
An important factor in the effective utilization of the size
mixtures herein involves their use in conjunction with material
which is either cationic or is capable of ionizing or dissociating
in such a manner as to produce one or more cations or other
positively charged moieties. These cationic agents, as they
hereinafter will be referred to, have been found useful as a means
for aiding the retention of the substituted cyclic dicarboxylic
acid anhydride as well as for bringing the latter into close
proximity to the pulp fibers. Among the materials which may be
employed as cationic agents in the method of this invention, one
may list long chain fatty amines, amine-containing synthetic
polymers (primary, secondary, tertiary or quaternary amine),
substituted polyacrylamide, animal glue, cationic thermosetting
resins and polyamide-epichlorohydrin polymers. Of particular use as
cationic agents are various cationic starch derivatives including
primary, secondary, tertiary or quaternary amine starch derivatives
and other cationic nitrogen substituted starch derivatives, as well
as cationic sulfonium and phosphonium starch derivatives. Such
derivatives may be prepared from all types of starches including
corn, tapioca, potato, waxy maize, wheat and rice. Moreover, they
may be in their original granule form or they may be
.[.converted.]. .Iadd.converted .Iaddend.to pregelatinized, cold
water soluble products.
Any of the above noted cationic retention agents may be added to
the stock, i.e. the pulp slurry, either prior to, along with or
after the addition of the size mixture or size emulsion.
With respect to the amount of cationic retention agent necessary,
under ordinary circumstances, the cationic agent is added to the
stock system in an amount of at least about 0.01%, preferably 0.025
to 3.0%, based on dry fiber weight. While amounts in excess of
about 3% may be used, the benefits of using increased amounts of
retention aid for sizing purposes are usually not economically
justified.
Subsequent to the addition of the size emulsion and retention aid,
the web is formed and dried on the paper making machine in the
usual manner. While full sizing is generally achieved immediately
off the paper machine, further improvements in the water resistance
of the paper prepared with the size mixtures of this invention may
at times be obtained by curing the resulting webs, sheets or molded
products. This curing process generally involves heating the paper
at temperatures in the range of from 80.degree. to 150.degree. C.
for a period of from 1 to 60 minutes. It is to be noted that this
post-curing is not essential to the successful operation of the
improved sizing method described herein.
The size mixtures of the present invention may be successfully
utilized for the sizing of paper prepared from all types of both
cellulosic and combinations of cellosic with non-cellulosic fibers.
The hardwood or softwood cellulosic fibers which may be used
include bleached and unbleached sulfate (Kraft), bleached and
unbleached sulfite, bleached and unbleached soda, neutral sulfite
semi-chemical, groundwood, chemi-groundwood, and any combination of
these fibers. These designations refer to wood pulp fibers which
have been prepared by means of a variety of processes which are
used in the pulp and paper industry. In addition, synthetic
cellulosic fibers of the viscose rayon or regenerated cellulose
type can also be used, as well as recycled waste papers from
various sources.
All types of pigments and fillers may be added in the usual manner
to the paper product which is to be sized. Such materials include
clay, talc, titanium dioxide, calcium carbonate, calcium sulfate
and diatomaceous earths. Stock additives such as defoamers, pitch
dispersants, slimicides, etc. as well as other sizing compounds can
also be used with the size mixtures described herein.
The use of the size mixtures described herein in accordance with
the method of this invention has been found (as will be illustrated
by the examples which follow) to yield paper products having
improved size properties, for example, resistance to water or
acidic ink solutions. In other words, a specified degree of size
properties in paper products can be achieved with a smaller amount
of size when the size composition is utilized in accordance with
the method of this invention rather than by methods known in the
prior art.
Moreover, it is a further advantage that use of the size mixtures
herein is not limited to any particular pH range which thus allows
for their utilization in the treatment of neutral and alkaline
pulp, as well as acidic pulp. The size mixtures may thus be used in
combination with alum, which is very commonly used in making paper,
as well as other acid materials. Conversely, they may also be used
with calcium carbonate or other alkaline materials in the stock. A
further advantage of these size mixtures is that they do not
detract significantly from the strength of the paper in the normal
concentrations employed in the industry and when used with certain
adjuncts will, in fact, increase the strength of the finished
sheets. An additional advantage found in the use of these size
mixtures is that only drying or mild curing conditions are required
to develop full sizing value.
The following examples will further illustrate the embodiments of
the present invention. In these examples, all parts given are by
weight unless otherwise specified.
EXAMPLE I
This example illustrates the use of a size mixture representative
of the size mixtures of this invention utilized in the form of an
aqueous emulsion. This emulsion is compared, in terms of particale
size and water resistance of the resulting sized paper, with a
conventional emulsion wherein substituted cyclic dicarboxylic acid
anhydride is emulsified with cationic starch. A further comparison
is made with a rosin/alum sizing method as commonly employed in the
paper industry. The much greater ease of emulsification of the size
mixtures of this invention is also demonstrated by the procedure
used in preparing the sizing emulsions prior to their addition to
the paper stock system. The ability to size paper effectively with
or without alum in the stock is also shown.
The size mixture was prepared by combining (A) 10 parts of a
polyoxyalkylene alkyl-aryl ether wherein the alkyl group contained
9 carbon atoms, the aryl radical was phenyl and the polyoxyalkylene
moiety was formed with 10 moles of ethylene oxide (Renex 690) and
(B) 90 parts of substituted cyclic dicarboxylic acid anhydride
wherein the alkenyl groups of the mixed anhydrides contained 15 to
20 carbon atoms (hereinafter referred to as ASA). Other materials
equivalent to Renex 690 include Triton N-101 and Igepal CO-630. An
emulsion was then formed by agitating 2 parts of this mixture with
98 parts of water using a propeller-type mixer at moderate speed
(500 rpm) for 10 seconds (Emulsion No. 1). A similar emulsion was
also formed by passing this size mixture through a simple
aspirator, together with a constant stream of water, to yield 1%
concentration of size mixture in one pass. The aspirator had a
throat dimeter of 0.15 in. and the flow rate employed was 14 liters
per minute. The emulsion was thus formed almost instantaneously
(Emulsion No. 2).
For comparison, a conventional aqueous emulsion of ASA was prepared
by first cooking 10 parts of the beta-diethyl aminoethyl chloride
hydrochloride ether of corn starch, whose preparation is described
in Example I of U.S. Pat. No. 2,813,093, in 90 parts of water which
was heated in a boiling water bath. The dispersion of the cationic
starch derivative, after being cooked for 20 minutes, was cooled to
room temperature and transferred to a Cenco cup attachment No.
17246-2 on a Waring blender whereupon 5 parts of ASA were slowly
added to the agitated dispersion. Agitation was continued for about
3 minutes at 23,000 rpm and the resulting emulsion was then diluted
by the addition of water to equal a total of 1,000 parts, 0.5%
solids (Emulsion No. 3).
Calculated amounts of the emulsions prepared as described above
were added to aqueous slurries of bleached sulfate pulp having a
Williams freeness of 400, a consistency of 0.5% and a pH of about
7.6, so as to yield the following concentrations of ASA on dry
fiber weight: 0.10, 0.20 and 0.40%. The cationic starch used in
making Emulsion No. 3 was added to the respective pulp slurry
subsequent to the addition of Emulsions No. 1 and No. 2 in a
concentration of 0.4% on dry fiber weight to retain these materials
in the sheet. In another variation of this procedure, 4% alum,
based on dry fiber weight, was added to the pulp slurry before
addition of the sizing emulsions. Sheets were formed in accordance
with TAPPI standards, dryed on a rotary print drier (surface
temperature approx. 90.degree. C.) then cured for 1 hour at
105.degree. C. and conditioned overnight at 72.degree. F. and 50%
R.H. before testing. The basis weight of these sheets was 55
lbs./ream (24.times. 36 inch - 500 sheets).
In comparing the water resistance of these sheets, use was made of
a dye test employing crystals of potassium permanganate and an acid
ink penetration test. In the dye test several crystals of potassium
permanganate are placed on the upper surface of a swatch of test
paper which is then set afloat in distilled water at room
temperature. As the water is absorbed into the paper the crystals
are moistened and impart a characteristic deep violet color to the
paper. The time measured in seconds required for an end-point where
three colored spots first appear on the paper surface is noted and
is in direct relation to the water resistance since a more water
resistant paper will retard the moistening of the permanganate
crystals which has been placed upon its upper surface.
The acid ink penetration test is a comparison test wherein a swatch
of test paper is floated in a dish of acid ink (pH 1.5) at
100.degree. F. and the time measured in seconds required for the
ink to penetrate through the paper to reach an end-point where
about 50% of the paper is colored is noted.
The following table presents data on the various paper sheets which
were compared in the described testing procedures.
TABLE 1
__________________________________________________________________________
Average % Particle by Acid ink Size of Weight Penetration
KMnO.sub.4 Sheet Sizing Emulsion of Dry Alum (Time in (Time in No.
Emulsion (Microns) Pulp Addition Seconds) Seconds)
__________________________________________________________________________
1. Emulsion #1 <1 0.1 None 25 53 2. Emulsion #1 <1 0.2 " 275
72 3. Emulsion #1 <1 0.4 " 430 77 4. Emulsion #2 <1 0.1 " 70
53 5. Emulsion #2 <1 0.2 " 140 74 6. Emulsion #2 1 0.4 " 320 87
7. Emulsion #3 2-3 0.1 " 12 54 (Control) 8. Emulsion #3 2-3 0.2 "
40 67 (Control) 9. Emulsion #3 2-3 0.4 " 65 75 (Control) 10.
Emulsion #1 <1 0.1 4% 100 58 11. Emulsion #1 <1 0.2 4% 145 70
12. Emulsion #1 <1 0.4 4% 190 87 13. Emulsion #2 <1 0.1 4%
110 57 14. Emulsion #2 <1 0.2 4% 150 68 15. Emulsion #2 <1
0.4 4% 205 88 16. Emulsion #3 2-3 0.1 4% 90 65 (Control) 17.
Emulsion #3 2-3 0.2 4% 130 73 (Control) 18. Emulsion #3 2-3 0.4 4%
170 84 19. Rosin (Control) -- 1.0 4% 55 67 20. Blank -- None None 0
0
__________________________________________________________________________
The above data clearly shows the greater ease of preparation and
superiority of the size mixtures of this invention, both in terms
of the small particle size of emulsions formed with these
compositions and in terms of water resistance imparted to the sized
paper over a range in level of addition typically employed in the
industry. It is also clear that these compositions demonstrate
superior sizing both in near-neutral and alum-containing (acidic)
stock systems.
EXAMPLE II
This example illustrates the use of size mixtures of this invention
wherein various substituted cyclic dicarboxylic acid anhydrides are
utilized in mixtures with polyoxyalkylene alkyl and alkyl-aryl
ethers.
In this example, the polyoxyalkylene alkyl-aryl ether was the same
material described in Example I and was mixed in a ratio of 20
parts with 80 parts of the anhydride. The substituted cyclic
dicarboxylic acid anhydrides incorporated in the mixtures of this
example were then varied as follows: Mixture No. 1 - the ASA
described in Example I; Mixture No. 2 - iso-octadecenyl succinic
acid anhydride; Mixture No. 3 - hexapropylene succinic acid
anhydride; Mixture No. 4 - (1-octyl-2-decenyl)-succinic acid
anhydride, i.e. the reaction product of maleic anhydride and
octadecene-9. Emulsions of these mixtures were prepared in the same
manner used to prepare Emulsion No. 1 described in Example I.
Calculated amounts of the emulsions were added to separate aqueous
slurries of bleached sulfate pulp having a freeness of 400, a
consistency of 0.5% and a pH of about 7.6. The cationic starch of
Example I was also added to the separate pulp slurries. Sheets were
formed and dried in accordance to TAPPI standards and thereafter
conditioned and tested as described in Example I. The basis weight
of these sheets was 55 lbs./ream (24.times. 36 inches - 500
sheets). All additions were made at a concentration of 0.2%
substituted cyclic dicarboxylic acid anhydride and 0.4% cationic
starch by weight of dry pulp. Following were the results
obtained:
TABLE 2 ______________________________________ Average Acid Ink
Particle Size Penetration KMnO.sub.4 Size of Emulsion (Time in
(Time in Mixture No. (Microns) Seconds) Seconds)
______________________________________ 1 <1 225 73 2 1-2 100 40
3 <1 240 81 4 <1 600 86
______________________________________
Similar superior emulsions and sizing are obtainable employing the
polyoxyalkylene alkyl-aryl ether of Example I together with the
reaction product of maleic acid anhydride and
2-n-octyl-1-decene.
This example clearly shows that various substituted cyclic
dicarboxylic acid anhydrides may be used to prepare size mixtures
within the scope of this invention. Additionally mixtures or blends
of the anhydrides herein described may be employed and will produce
comparable sizing.
EXAMPLE III
This example illustrates the use of size mixtures of this invention
wherein different polyoxyalkylene alkyl or alkyl-aryl ether or the
corresponding mono- or diester compounds are utilized in the
mixture with substituted cyclic dicarboxylic acid anhydride.
In this example, the substituted cyclic dicarboxylic acid anhydride
was the same material (ASA) described in Example I while the
polyoxyalkylene alkyl and alkyl-aryl ether or ester compounds used
in the size mixtures were varied. Size mixtures used in this
example were prepared as follows: Mixture No. 1 - 5 parts of the
polyoxyalkylene alkyl-aryl ether described in Example I were mixed
with 95 parts ASA; Mixture No. 2 - 15 parts of the polyoxyalkylene
alkyl-aryl ether described in Example I were mixed with 85 parts
ASA; Mixture No. 3 - 10 parts of a polyoxyalkylene alkyl-aryl ether
wherein the alkyl group contains 9 carbon atoms, the aryl radical
is phenyl and the polyoxyalkylene moiety was formed with 5 moles of
ethylene oxide (Triton N-57) were mixed with 90 parts of ASA;
Mixture No. 4 - 10 parts of a polyoxyalkylene alkyl ether wherein
the alkyl group contains 12 carbon atoms and the polyoxyalkylene
moiety was formed with 6 moles of ethylene oxide (Tergitol TMN)
were mixed with 90 parts ASA; Mixture No. 5 - 10 parts of a
polyoxyalkylene alkyl-aryl ether wherein the alkyl group contained
9 carbon atoms, the aryl radical was phenyl and the polyoxyalkylene
moiety was formed with 15 moles of ethylene oxide (Tergitol NP-33)
were mixed with 90 parts ASA; Mixture No. 6 - 10 parts of a
polyoxyethylene monooleate ester wherein the molecular weight of
the polyoxyethylene moiety was 400 (PEG 400 Monooleate) were mixed
with 90 parts of ASA; and Mixture No. 7 - 10 parts of
polyoxyethylene dilaurate ester wherein the molecular weight of the
polyoxyethylene moiety was 600 (PEG 600 Dilaurate) were mixed with
90 parts of ASA. Each of these mixtures was then agitated in water
to yield emulsions containing 2 parts size mixture and 98 parts of
water. The emulsions were then added to a 0.5% consistency pulp
slurry containing bleached sulfate pulp beaten to a freeness of 400
and at a pH of approximately 7.6 to yield 0.2% ASA on weight of dry
fiber. The cationic starch described in Example I was then added to
the pulp to yield 0.4% cationic starch on weight of dry pulp.
Handsheets thereafter were formed, contitioned and tested in the
dye test as described in Example I. Following were the results
obtained.
TABLE 3 ______________________________________ Average Particle
Size of Emulsion KMnO.sub.4 Size Mixture No (Microns) (Time in
Seconds) ______________________________________ 1 1-2 98 2 <1 93
3 <1 104 4 Approx. 1 99 5 Approx. 1 96 6 Approx. 1 76 7 Approx.
1 86 ______________________________________
This example clearly shows that various polyoxyethylene alkyl and
alkyl-aryl ethers and the corresponding mono- and di-esters, within
the scope of this invention, can be used interchangeably in size
mixtures with substituted cyclic dicarboxylic acid anhydrides to
yield excellent sizing performance.
EXAMPLE IV
This example illustrates the use of our size mixtures by direct
addition to a papermaking stock system in unemulsified form.
Size Mixture No. 1 prepared from 90 parts ASA (described in Example
I) and 10 parts of polyoxyalkylene alkyl-aryl ether (described in
Example I) was added directly to a slurry of bleached sulfate pulp
at 1.5% consistency in a laboratory Valley beater and beaten very
lightly for a few minutes. Similarly, Size Mixtures No. 2 and No. 3
were prepared from 90 parts ASA and 10 parts PEG 400 Monooleate or
10 parts PEG 600 Dilaurate, respectively, and these mixtures were
also added directly to the slurry. The pulp was then diluted to
0.5% consistency, and 0.4% on dry fiber weight of the cationic
starch described in Example I was added separately to the slurry to
act as a retention aid during sheet formation. Sheets were then
formed, conditioned and tested in the dye test as described in
Example I. The basis weight of these sheets was 55 lbs./ream
(24.times. 36 inches - 500 sheets). Following are the results
obtained.
TABLE 4 ______________________________________ % ASA by Weight
KMnO.sub.4 Size Mixture No. on Dry Pulp (Time in Seconds)
______________________________________ 1 0.2 75 2 0.2 40 3 0.2 39
Blank None 0 ______________________________________
The self-emulsifying properties of these size mixtures are
demonstrated by the excellent sizing value achieved when they are
added to the stock without prior emulsification in water.
Consequently, the considerable ease .Iadd.and .Iaddend.versatility
in the use of the size .[.mixutres.]. .Iadd.mixtures .Iaddend.of
this invention can be readily seen.
EXAMPLE V
This example illustrates the ability of size mixtures of this
invention to readily size paper containing high levels of inorganic
filler. In this example, the size mixture used was the same as
described in Example I. Prior to additon, the size mixture was
emulsified (Emulsion A) in the same manner as described for the
preparation of Emulsion No. 2 in Example I. For comparison
purposes, a conventional sizing emulsion (Emulsion B) was prepared
in accordance with the method described to prepare Emulsion No. 3
in Example I. Each emulsion was then added to 1) a 0.5% consistency
stock slurry containing bleached sulfate pulp with 20% Kaolin clay
and 4% alum on dry fiber weight; and 2) a 0.5% consistency stock
slurry containing bleached sulfate pulp with 20% calcium carbonate
on dry fiber weight. The pH of the calcium carbonate-containing
stock slurry was approximately 8.5, while the pH of the
clay-containing slurry was approximately 5.5. Each emulsion was
added to the stock at a level to yield 0.4% ASA on dry fiber
weight. For retention purposes, 0.8% of the cationic starch
described in Example I was added to the pulp slurry following
addition of Emulsion A. Sheets of 55 lbs./ream (24.times. 36 inches
- 500 sheets) basis weight were then formed and conditioned in the
manner described in Example I and tested accordingly. Following are
the results obtained:
TABLE 5 ______________________________________ Acid Ink KMnO.sub.4
Sheet Filler Penetration (Time in No. Size Added Added (Time in
Secs.) Secs.) ______________________________________ 1 Emulsion A
20% Clay 115 75 2 Emulsion A 20% CaCO.sub.3 450 68 3 Emulsion B 20%
Clay 100 70 (Control) 4 Emulsion B 20% CaCO.sub.3 325 56 (Control)
5 Blank 20% Clay 0 0 ______________________________________
The above data clearly shows the improved sizing achieved with the
size mixtures of this invention in highly filled sheets and under
both acid and alkaline stock conditions.
EXAMPLE VI
This example illustrates the use of a size mixture representative
of the size mixtures of this invention to size paper made with
different types of pulps.
In this example, the size mixture used was the same as described in
Example I and was emulsified in the same manner as described for
the preparation of Emulsion No. 2 in Example I. The emulsion was
then added to various pulp slurries prepared at 0.5% consistency, a
freeness of 400 and pH of approximately 7.6 in amounts to yield
0.2% ASA on dry fiber weight. In all cases, 0.4% on dry fiber
weight of the cationic starch described in Example I was added to
the pulp slurries separately to retain the size mixture during
sheet formation. Sheets of 55 lbs. ream (24.times. 36 inches - 500
sheets) basis weight were then formed from each pulp slurry
conditioned and tested in the dye test in the manner described in
Example I. Following are the results obtained:
TABLE 6 ______________________________________ KMnO.sub.4 Sheet No.
Type of Pulp (Time in Seconds)
______________________________________ 1 Bleached Hardwood Sulfate
69 2 Bleached Softwood Sulfite 83 3 Unbleached Softwood Sulfate 76
4 Groundwood 58 ______________________________________
The above data, together with data in other examples, clearly shows
that the size mixtures of this invention can be effectively used to
size various types of pulps commonly used in the manufacture of
paper.
EXAMPLE VII
This example illustrates the use of various types of cationic
agents in conjunction with the size mixtures of this invention. In
this example, the size mixture used was the same as described in
Example I and was emulsified, prior to the addition to the pulp
slurry, in the same manner described for the preparation of
Emulsion No. 2 in Example I. The emulsion was added to portions of
a 0.5% consistency pulp slurry containing bleached sulfate pulp
beaten to a freeness of 400. Subsequent to the addition of size
emulsion, different cationic agents were added to separate slurries
in order to retain the size emulsion in the web during sheet
formation. An amount of size emulsion was added so as to yield 0.2%
ASA on dry fiber weight in each case, while the amount of cationic
agent was varied. Sheets of 55 lbs./ream (24.times. 36 inches - 500
sheets) basis weight were then formed from each slurry, conditioned
and tested in the manner described in Example I. Following are the
results obtained:
TABLE 7
__________________________________________________________________________
Acid Ink % on Dry Penetration KMnO.sub.4 Sheet Fiber (Time in (Time
in No. Cationic Agent Weight Seconds) Seconds)
__________________________________________________________________________
1 Cationic corn starch 0.4 135 72 2 Polyaminoethyl acrylate resin
0.2 600 76 3 Polyamide-amine resin 0.2 600 85 4 Polyethylene imine
resin 0.2 85 50 5 Polyacrylamide-amine resin 0.2 30 68 6 Cationic
potato starch 0.4 120 70 7 Alum 4.0 65 77 8 None (Control) -- 0 0
__________________________________________________________________________
The above data clearly shows that various cationic agents can be
effectively employed to retain the size mixtures of this invention
in the web during the sheet forming stage.
EXAMPLE VIII
This example illustrates the improved operability of these size
mixtures when used on an actual papermaking machine. More
specifically this example illustrates the elimination of buildup
and picking tendencies created by sizing agents on the wet press
rolls of a paper machine. This buildup of fiber on the wet press
rolls causes disruption of the sheet surface and, in severe cases,
will actually tear the sheet causing the traveling web to break at
that point. Sizing was measured in this example by means of a Cobb
test run on the top side of the sheet in accordance with TAPPI
Standard Method T441 os-69. This test measures the amount of water
absorbed by the sheet surface in a specified period of time (in
this case, 2 minutes) and is expressed in terms of grams per sq.
meter. Thus, lower values represent greater .[.wate.]. .Iadd.water
.Iaddend.resistance and better sizing.
A series of tests were conducted on a Fourdrinier paper machine
wherein the press section consisted of two main presses followed by
a smoothing press, each press consisting of a top and bottom roll.
The first press consisted of a straight-through plain press with a
standard rubber covered top roll as commonly used in the industry
and the second press was a plain reversing press with a composition
(Microrok) covered top roll, also commonly used in the industry.
The smoothing press consisted of a straight-through set of rolls
with a metal surfaced (Press-Tex) top roll and composition-covered
(Micromate) bottom roll. The basic papermaking furnish consisted of
a very lightly refined mixture of approximately 80% bleached
hardwood kraft pulp and 20% bleached softwood kraft pulp. The
sizing agents were added continuously to the stock preparation
system and a sheet of paperboard was formed at approximately 123
lbs. per 3,000 sq. ft. basis weight. Buildup on the press rolls due
to picking was ascertained under the indicated conditions on each
of the press rolls and noted in descriptive terms: None, slight,
moderate, heavy, etc.
Sizing emulsions were prepared as follows: Emulsion A (a control)
was prepared by cooking the cationic starch described in Example I
at 5% solids at 200.degree. F. for 30 minutes. The cooked starch
solution was then cooled to 130.degree. F. and mixed with the
substituted cyclic dicarboxylic acid anhydride of Example I (ASA)
and emulsified by passing through commercial homogenizing equipment
at 300 p.s.i. g. Emulsion B, representing an embodiment of this
invention, was prepared by continuously premixing through a static
mixer 90 parts of ASA with 10 parts polyoxyalkylene alkyl-aryl
ether (as described in Example I), then passing this size mixture
through an orifice with a continuous stream of water to yield an
emulsion containing 2 parts of size mixture in 98 parts of water.
For retention purposes, 0.35% cationic starch on weight of dry
fiber was added subsequent to the addition of Emulsion B. Five
pounds of alum per ton of stock were added to adjust stock pH to
approximately 5.5 when Emulsion A and B were used. For further
comparison, rosin was also used as a sizing agent in these tests.
Following are the results obtained:
TABLE 8
__________________________________________________________________________
Buildup Noted After Running 15 Min. Cobb Smoothing Sizing Addition
to Stock 1st Press 2nd Press Press (GM/M.sup.2)
__________________________________________________________________________
1. Base Sheet - No Additives None None Slight 402 2. 1% Rosin + 2%
Alum (Control) Moderate Moderate Moderate 34 3. 0.25% Emulsion A
(Control) Heavy Moderate Heavy 32 4. 0.25% Emulsion B None None
Slight 29
__________________________________________________________________________
The concentrations of the various ingredients listed in the above
table are expressed in terms of percent active ingredient by weight
of dry pulp.
The above results clearly illustrate the improved machine
operability and excellent water holdout imparted by the size
mixtures of this invention when compared to conventional sizing
methods employed in the industry.
EXAMPLE IX
This example illustrates the excellent resistance to acidic and
alkaline solutions which is displayed by the paper which has been
prepared with our novel size mixtures.
An aqueous emulsion prepared with the same size mixture and in the
same manner used to prepare Emulsion No. 2 in Example I was added
to a bleached sulfate pulp slurry having a freeness of 400 and a
consistency 0.5%. The cationic starch of Example I was then added
to the stock as a retention aid for the size. Sheets containing
0.4% ASA and 0.8% cationic starch were formed and conditioned as
described in Example I. The sheets were tested by means of a
modified potassium permanganate test wherein solutions of 10%
lactic acid in one case and 10% sodium hydroxide in another case
were used as the test fluid, along with distilled water as a
control. For a further comparison, sheets were formed and tested in
the same manner wherein 1% rosin and 4% alum on dry fiber weight
was added to the stock for sizing in place of our size mixture.
Following are the results obtained:
TABLE 9 ______________________________________ KMnO.sub.4
Penetration Time (Seconds) Sheet Distilled Lactic Sodium No.
Additive Water Acid Hydroxide
______________________________________ 0.4% ASA Mixture 111 95 65 2
1.0% Rosin/4% Alum 70 60 25
______________________________________
This example clearly shows the excellent resistance imparted by
these size mixtures to penetration by both acidic and alkaline
fluids.
EXAMPLE X
This example illustrates the criticality of the molecular structure
of the polyoxyethylene alkyl and alkyl-aryl ethers on the
performance of these materials in the mixtures of the present
invention.
The procedure and equipment used to produce Emulsion No. 2 in
Example I were employed in an attempt to produce emulsions using
the following surfactants of the same type which differ only in the
length of the alkyl chain and in the number of moles of ethylene
oxide.
The results are shown in Table 10.
TABLE 10 ______________________________________ Avg. Part- Alkyl
Aryl Moles Quality of icle Chain Group Ethyleneoxide Emulsion Size
______________________________________ octyl phenyl 3 very poor
stability 8.mu. nonyl phenyl 5 good stability 1.mu. tri- methyl
none 6 good stability 1.mu. nonyl nonyl phenyl 7 good stability
1.mu. octyl phenyl 9-10 good stability 1.mu. nonyl phenyl 6 very
good stability 1.mu. nonyl phenyl 15 good stability 1.mu. octyl
phenyl 16 good stability 1.mu. octyl phenyl 20 good stability 1.mu.
octyl phenyl 30 very poor stability 8.mu. nonyl phenyl 5 blend very
good stability 1.mu. of 50% octyl phenyl 9-10 of each
______________________________________
The above results show the necessity for employing polyoxyalkylene
alkyl or alkyl-aryl ethers containing 5 to 20 ethyleneoxide units
in order to produce the self-emulsifying size mixtures of the
present invention.
EXAMPLE XI
In order to show the necessity for employing only the specific
polyoxyalkylene alkyl or alkyl-aryl ethers or esters described
herein, the procedure used to prepare Emulsion No. 1 in Example I
was repeated using 10 parts of each of a variety of nonionic
surfactants with 90 parts of alkenyl succinic anhydride.
In Sample 1, the surfactant employed was polyoxyethylene sorbitan
trioleate (Tween 85). The resulting emulsion was so poor that it
could not even be tested for sizing properties.
In Sample 2, polyoxyethylene sorbitol hexaoleate (Atlox 1086) was
used as surfactant. In this sample, an emulsion could not even be
produced using the procedures of applicants' Example I.
In Sample 3, polyoxyethylene sorbitol laurate (Atlox 1045) was
employed. A relatively poor emulsion was formed (particle size up
to 5 microns) and tested for sizing in accordance with the method
of Example I. The sheets thus produced developed pin holes where
water or ink penetrated instantaneously and thus were completed
unacceptable in quality.
The above results show that the surfactants conventionally employed
in paper sizing systems cannot be employed with the succinic
anhydrides in the paper stock system without the need for either
rigid emulsification procedures including extremely high shear and
high pressure homogenization together with protective colloids.
In summary, the invention is seen to provide the practitioner with
a size mixture useful in the manufacture of sized paper products.
The size mixture is easily emulsified and the emulsion or size
mixture per se may be utilized under a wide variety of paper making
conditions to provide sized paper products characterized by their
reduced water and ink absorption as well as their increased
resistance to aqueous acid and alkaline solutions at low levels of
addition. Variations may be made in proportions, procedures and
materials without departing from the scope of this invention.
* * * * *