Paper making and fiber liberation – Processes and products – Non-uniform – irregular or configured web or sheet
Reexamination Certificate
1998-11-25
2001-08-14
Silverman, Stanley S. (Department: 1731)
Paper making and fiber liberation
Processes and products
Non-uniform, irregular or configured web or sheet
C162S112000, C162S116000, C162S127000, C162S138000, C162S158000, C162S199000, C162S070000, C162S071000, C162S075000, C162S076000, C162S005000, C252S175000, C252S391000, C252S391000, C252S182280, C516S069000, C528S370000
Reexamination Certificate
active
06273995
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a paper bulking promoter with which sheets of paper obtained from a pulp feedstock can be bulky without impairing paper strength.
2. Statement of Related 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.
DISCLOSURE OF THE INVENTION
3. 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 a specific alcohol and/or a polyoxyalkylene adduct thereof into a pulp feedstock, e.g., a pulp slurry, in the papermaking step, the sheet made from the feedstock can have low density (improved bulkiness) without detriment to paper strength. This invention has thus been achieved.
Namely, this invention provides a paper bulking promoter which comprises a compound represented by the following formula
RO(XO)
a
H
wherein R represents a linear or branched alkyl or alkenyl group having 6 to 22 carbon atoms or an alkylaryl group in which the alkyl group has 4 to 20 carbon atoms; X's are the same or different and each represents a linear or branched alkylene group having 2 or 3 carbon atoms; and a indicates the average number of moles added in the range of 0≦a≦20.
This invention relates to a paper bulking promoter containing at least one compound (1) represented by formula (1):
RO(EO)
m
(PO)
n
H (1)
wherein R represents a linear or branched alkyl or alkenyl group having 6 to 22 carbon atoms or an alkylaryl group in which the alkyl group has 4 to 20 carbon atoms; E represents an ethylene group; P represents a propylene group; and m and n respectively indicate the average number of moles added in the ranges of 0≦m≦20 and 0≦n≦50; provided that (EO)
m
(PO)
n
may have any of block and random arrangements and may begin with any of EO and PO.
In formula (1), R is preferably a linear or branched alkyl or alkenyl group having 8 to 18 carbon atoms.
The compound (1) includes one obtained by causing a mixture of two or more ROH's to add at least either of EO and PO An alcohol represented by ROH is also included.
This invention further provides a paper bulking promoter composition which comprises the compound (1) and at least one nonionic surfactant based on a polyhydric alcohol.
The nonionic surfactant based on a polyhydric alcohol is preferably at least one member selected among sugar alcohol/EO (ethylene oxide, the same applies hereinafter) adducts, fatty acid esters of the adducts, fatty acid esters of sugar alcohols, sugar/EO adducts, fatty acid esters of the adducts, sugar/fatty acid esters, and fat/EO adducts. Especially preferred are fatty acid esters of sugar alcohol/EO adducts and fat/EO adducts.
The proportion of the compound (1) to the nonionic surfactant based on a polyhydric alcohol is desirably from 5/5 to 10/0 (by weight), preferably from 5/5 to 99/11 (by weight).
This invention also provides a process for producing a highly bulky pulp sheet which comprises adding the bulking promoter or composition in any of the papermaking process steps to thereby produce a highly bulky pulp sheet which has a bulk density lower by at least 5% than the product not containing the paper bulking promoter and a tearing strength as measured according to JIS P 8116 of at least 90% of that of the product. The highly bulky pulp sheet obtained by this process is also included. It is preferred that the bulking promoter or composition be mixed with water and a pulp feedstock to obtain a homogeneous slurry, which is subjected to sheet forming.
Further, an aqueous emulsion containing 10 to 100 wt. % of the bulking promoter or composition may be mixed with a pulp feedstock to obtain a homogeneous slurry, which is subjected to sheet forming.
In the bulking promoter composition, m and n are desirably in the ranges of 0≦m≦2 and 0≦n≦50, and the proportion of the compound (1) to the nonionic surfactant based on a polyhydric alcohol is desirably from 5/5 to 99/1 (by weight). Preferably, m and n each is zero and the proportion of the compound (1) to the nonionic surfactant based on a polyhydric alcohol is from 5/5 to 99/1 (by weight). The especially preferred range is from 7/3 to 95/5 (by weight).
This invention furthermore provides a highly bulky sheet which comprises the bulking promoter or composition and a pulp paper and which has a bulk density lower by at least 5% than the product not containing the paper bulking promoter and a tearing strength as measured according to JIS P 8116 of at least 90% of that of the product.
DETAILED EXPLANATION OF THE INVENTION
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.
The compound represented by the formula (1) is one obtained by causing a higher alcohol, an alkylphenol, or the like in which the alkyl has 6 to 22 carbon atoms to add an alkylene oxide such as ethylene oxide (EO) or propylene oxide (PO). In this invention is used the compound in which the average number of moles of ethylene oxide added is in the range of 0≦m≦20 . The range of the average number of moles added, m, is desirably 0≦m≦10 , preferably 0≦m≦5 . If m exceeds 20, the effect of imparting bulkiness to paper is lessened. Further, the compound used is one in which the average number of moles of propylene oxide (PO) added, n, is in the range of 0≦n≦50 , preferably 0≦n≦20 . When n exceeds 50, such a compound is economically disadvantageous although the decrease in performance is little.
R in the formula (1), which represents a linear or branched alkyl or alkenyl group having 6 to 22 carbon atoms or an alkylaryl group in which the alkyl has 4 to 20 carbon atoms, is preferably a linear or branched alkyl or alkenyl group having 8 to 18 carbon atoms. If R is an alkyl or alkenyl group in which the number of carbon atoms is outside the range of from 6 to 22 or if R is an alkylaryl group in which the number of carbon atoms of the alkyl group is outside the range of from 4 to 20, then the compound is less effective in imparting bulkiness to paper.
E and P in the formula (1) each represents a linear or branched alkylene group having 2 or 3 carbon atoms. Examples thereof include ethylene and propylene. When the group (EO)
m
(PO)
n
in the general formula (1) is composed of a combination of polyoxyethylene and polyoxypropylene, the
Hamaguchi Koji
Ikeda Yasushi
Sowa Toshiki
Takahashi Hiromichi
Birch, Stewart, Kolasch and Birch LLP
Halpern Mark
Kao Corporation
Silverman Stanley S.
LandOfFree
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