Paper making and fiber liberation – Processes and products – Non-fiber additive
Reexamination Certificate
1998-12-31
2002-02-12
Silverman, Stanley S. (Department: 1731)
Paper making and fiber liberation
Processes and products
Non-fiber additive
C162S179000, C162S111000, C162S112000, C162S129000, C162S183000, C162S168100, C428S172000, C428S156000
Reexamination Certificate
active
06346169
ABSTRACT:
BACKGROUND OF THE PRIOR ART
1. Technical Field
This invention relates to a paper bulking promoter with which the sheets of paper obtained from a pulp feedstock can be bulky without impairing paper strength.
2. Description of the Prior Art
Recently, there is a desire for high-quality paper, e.g., paper excellent in printability and voluminousness. Since the printability and voluminousness of paper are closely related to the bulkiness thereof, various attempts have been made to improve bulkiness. Examples of such attempts include a method in which a crosslinked pulp is used (JP-A 4-185792, etc.) and a method in which a mixture of pulp with synthetic fibers is used as a feedstock for papermaking (JP-A 3-269199, etc.). Examples thereof further include a method in which spaces among pulp fibers are filled with a filler such as an inorganic (JP-A 3-124895, etc.) and a method in which spaces are formed (JP-A 5-230798, etc.). On the other hand, with respect to mechanical improvements, there is a report on an improvement in calendering, which comprises conducting calendering under milder conditions (JP-A 4-370298).
However, the use of a crosslinked pulp, synthetic fibers, etc. makes pulp recycling impossible, while the technique of merely filling pulp fiber spaces with a filler and the technique of forming spaces result in a considerable decrease in paper strength. Furthermore, the improvement in mechanical treatment produces only a limited effect and no satisfactory product has been obtained so far.
Also known is a method in which a bulking promoter is added during papermaking to impart bulkiness to the paper. Although fatty acid polyamide polyamines for use as such bulking promoters are on the market, use of these compounds results in a decrease in paper strength and no satisfactory performance has been obtained therewith.
SUMMARY OF THE INVENTION
The inventors have made intensive investigations in view of the problems described above. As a result, they have found that by incorporating at least one compound selected among specific cationic compounds, amine compounds, acid salts of amine compounds, amphoteric compounds, amide compounds, quaternary ammonium salts, and imidazoline derivatives, optionally together with at least one specific nonionic surfactant into a pulp feedstock, e.g., a pulp slurry, in the papermaking step, the sheet made from the feedstock can have improved bulkiness without detriment to paper strength. This invention has thus been achieved.
Namely, this invention provides a process for producing a bulky paper, comprising the step of making paper from pulp in the presence of a bulking promoter comprising at least one compound selected from the group consisting of a cationic compound, an amine compound, an acid salt of an amine compound, an amphoteric compound, an amide compound, a quaternary ammonium salt, and an imidazoline derivative.
The term “paper bulking promoter” used herein means an agent with which a sheet of paper obtained from a pulp feedstock can have a larger thickness (can be bulkier) than that having the same basis weight obtained from the same amount of a pulp feedstock.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Examples of the cationic compounds for use in this invention include compounds represented by the following formulae (a
1
) and (b
1
):
wherein R
11
and R
12
are the same as or different from each other, and an alkyl, alkenyl or &bgr;-hydroxyalkyl group having 8 to 24 carbon atoms; R
13
, R
14
and R
15
are the same as or different from each other, and an alkyl or hydroxyalkyl group having 1 to 8 carbon atoms, benzyl or —(AO)n
11
-Z
11
wherein AO is an oxyalkylene unit having 2 or 3 carbon atoms, Z
11
is a hydrogen atom or an acyl group and n
11
is an integer of 1 to 50; R
16
is an alkyl, alkenyl or &bgr;-hydroxyalkyl group having 8 to 36 carbon atoms; and X
−
is an anionic ion.
In the formula (a
1
), R
11
and R
12
, which are the same or different, each preferably is an alkyl or alkenyl group having 10 to 22 carbon atoms. R
13
and R
14
, which are the same or different, each preferably is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Examples of X
−
, which is an anionic ion, include hydroxy, halide, and monoalkyl (C1-C3) sulfate ions and anions derived from inorganic or organic acids. X
−
is preferably a halide ion, especially Cl
−
.
In the formula (b
1
), R
13
, R
14
, and R
15
, which are the same or different, each is preferably an alkyl group having 1 to 3 carbon atoms or a benzyl group. R
16
is preferably an alkyl group having 10 to 22 carbon atoms. Examples of the anionic ion X
−
are the same as those in the formula (a
1
). X
−
is preferably a halide ion, especially Cl
−
.
In the present invention, the cationic compounds may include quaternary ammonium salts.
Hereinafter X
−
may be an anionic ion as an anionic ion.
Examples of the amine compounds and the acid salts of amine compounds for use in this invention include compounds represented by the following formulae (a
2
) to (f
2
):
wherein R
21
is an alkyl, alkenyl or &bgr;-hydroxyalkyl group having 8 to 36 carbon atoms; R
22
and R
23
are the same as or different from each other, and a hydrogen atom, an alkyl group having 1 to 24 carbon atoms or an alkenyl group having 2 to 24 carbon atoms; R
24
and R
25
are the same as or different from each other, and a hydrogen atom or an alkyl group having 1 to 3 carbon atoms; HB represents an inorganic acid or an organic acid; AO is an oxyalkylene unit having 2 or 3 carbon atoms; l
21
and m
21
are 0 or a positive integer, and the sum in total of l
21
and m
21
is in an integer ranging from 1 to 300; and n
2
is a number of 1 to 4.
In the formulae (a
2
) to (f
2
), R
21
is preferably an alkyl group having 10 to 22 carbon atoms. R
22
and R
23
, which are the same or different, each preferably is a hydrogen atom or an alkyl group having 1 to 22 carbon atoms. In HB in the acid salts of amine compounds, B is preferably a halogen or a carboxylate having 2 to 5 carbon atoms, especially preferably a carboxylate having 2 or 3 carbon atoms. Preferred amine compounds and preferred acid salts of amine compounds are the compounds represented by the formulae (a
2
) and (b
2
), respectively.
The acid salt represented by the formula (b
2
) may be signified by the following formula (b
21
):
wherein R
21
, R
22
and R
23
are same as above-mentioned; H is hydrogen atom; and B
−
represents a base.
That is, the acid salt may be an ionized compound.
Examples of the amphoteric compounds for use in this invention include compounds represented by the following formulae (a
3
) to (j
3
):
wherein R
31
, R
32
and R
33
are the same as or different from each other, and an alkyl group having 1 to 24 carbon atoms or an alkenyl group having 2 to 24 carbon atoms; R
34
is an alkyl, alkenyl or &bgr;-hydroxyalkyl group having 8 to 36 carbon atoms; M is a hydrogen atom, an alkali metal atom, a half a mole of an alkaline earth metal atom or an ammonium group; Y
31
is R
35
NHCH
2
CH
2
—, wherein R
33
is an alkyl group having 1 to 36 carbon atoms, or an alkenyl or a hydroxy alkyl group having 2 to 36 carbon atoms; Y
32
is a hydrogen atom or R
35
NHCH
2
CH
2
—, R
35
being defined above; Z
31
is —CH
2
COOM, M being defined above; and Z
32
is a hydrogen atom or —CH
2
COOM, M being defined above.
In the formulae (a
3
) to (j
3
), R
31
, R
32
, and R
33
, which are the same or different, each preferably is an alkyl group having 1 to 22 carbon atoms. Especially preferably, R
31
is an alkyl group having 10 to 20 carbon atoms, and R
32
and R
33
each is an alkyl group having 1 to 3 carbon atoms. R
34
is preferably an alkyl group having 10 to 22 carbon atoms. Preferred amphoteric compounds are those represented by the formulae (a
3
) and (b
3
).
Examples of the other amine compounds and the other acid salts of an amine compound for use in this invention include compounds represented by the following formulae (a
4
) to (d
4
):
wherein R
41
is an alkyl, alkenyl or &bgr;-hydrox
Ikeda Yasushi
Ishibashi Yoichi
Tadokoro Takaaki
Takahashi Hiromichi
Halpern Mark
Kao Corporation
Silverman Stanley S.
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