Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
1998-12-30
2001-01-16
Trinh, Ba K. (Department: 1612)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C549S511000, C428S084000, C493S186000
Reexamination Certificate
active
06175022
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to ketene multimer sizing agents and more particularly it relates to nucleophilic group terminated ketene multimer sizing agents.
BACKGROUND OF THE INVENTION
Sizing agents are added to fine paper to improve the runnability of the paper machine and improve the performance of the paper in end-use applications. Alkyl ketene dimer (AKD, e.g., Aquapel®364 dimer available from Hercules), alkenyl ketene dimer (AlkKD, e.g., Precis® 787 dimer available from Hercules), and alkenyl succinic anhydride (ASA) are the most commonly used internal sizing agents for paper made under alkaline conditions. Traditional AKD's are made by the dimerization of two saturated, straight-chain fatty acid chlorides (e.g., palmitic or stearic acid chlorides). Liquid AlkKDs can be made by dimerization of unsaturated or branched fatty acids (e.g., oleic or isostearic acid). ASA-based sizing agents are made by the reaction of maleic anhydride with an internal olefin (typically C
14
-C
18
). All three types of sizing agents—AKD, AlkKD, and ASA—have a reactive functional group that covalently bonds to cellulose pulp, and a hydrophobic tail that is oriented away from the pulp once the reaction has taken place. The nature and orientation of the hydrophobic tails causes the paper to repel water.
Although AKD, AlkKD, and ASA are all commercially successful, each has its shortcomings. Poor emulsion stability and deposits on the paper machine are the two most commonly cited shortcomings of ASA. ASA cannot be shipped and stored in emulsion form for long periods of time. The papermaker must make the ASA emulsion in the paper mill immediately before use. More importantly, even moderate addition levels of ASA can cause deposits on the paper machine, web breaks, and holes in the paper. ASA addition levels above 1.0-1.25 kg/metric tonne of paper general lead to unacceptable paper machine runnability and paper quality problems. Addition levels greater than 1.0-1.25 kg/metric tonne are often required to meet end-use sizing requirements, or to size paper grades made with high levels of filler.
Rate of sizing development is the most frequently cited shortcoming of AKD-based sizing agents. An extended period of curing is often required before sizing development is complete. In most cases, AKD sizing is completed by the time the paper has reached the winder. AKD-based sizing agents have also been associated with alkaline paper handling problems in high speed converting applications. Typical problems encountered with alkaline fine paper include: reduced operating speed, double feeds or jams in high speed copiers, paper welding, and registration errors on envelope folding and high speed printing equipment.
Commercial evaluations have consistently shown that liquid AlkKD's give sized paper with better handling performance than paper sized with traditional AKD's. Unfortunately, the improved paper handling performance generally comes at the expense of reduced sizing efficiency. Pilot scale testing has shown that none of the three commonly used reactive sizes—AKD, AlkKD, or ASA—can be used in size press applications without paper handling problems.
Polymeric surface sizing agents, such as Scripset 740 styrene maleic anhydride copolymer or Chromoset 600 styrene acrylate ester (available from Hercules Incorporated) have several advantages over reactive sizing agents added at the wet end. Adding the sizing agent at the size press develops sizing at the surface of the sheet where it is needed to obtain good black and white ink jet print quality, or resist the penetration of fountain solution on an offset press. Due to their high molecular weight, polymeric sizing agents generally do not cause the paper handling problems on high speed converting equipment or high speed copiers associated with reactive sizing agents. And finally, polymeric surface sizes added at the size press do not cause wet end deposit problems that can significantly reduce the productivity of the paper machine.
Sizing efficiency and cost are the most commonly cited disadvantages of polymeric surface sizing agents. On a pound-for-pound basis, AKD, AlkKD and ASA are 30% less expensive than a typical polymeric surface size. The high sizing efficiency of AKD, AlkKD, and ASA further increases the relative cost of obtaining sizing with polymeric surface sizes. All three reactive sizing agents are 50-100% more efficient than any commercial polymeric surface sizing agent on a pound-for pound basis.
Pilot paper machine testing has shown that liquid ketene multimer added at the size press offers a better balance of sizing efficiency, paper machine cleanliness, paper ink jet print quality, and paper runnability on high speed converting equipment than AKD, AlkKD, or ASA added at the wet end, or any polymeric surface sizing agent. Ketene multimer sizing agents have also shown advantages in paper grades, such as liquid packaging board, where wet strength is required.
Ketene multimer sizing agents based on aliphatic and alicyclic dicarboxylic acids are described in U.S. Pat. No. 5,685,815 and WO97/30218 and Brungardt, Riehle and Zhang 1, U.S. Ser. No. 08/601,113, filed Feb. 16, 1996, the entire disclosure of which references are incorporated by reference herein.
SUMMARY OF THE INVENTION
According to the present invention there is provided a sizing agent comprising a nucleophilic group (such as alcohol) terminated 2-oxetanone multimer.
Further provided is a process for preparing the nucleophic group terminated ketene multimer of the present invention comprising (a) providing a compound having at least one nucleophilic group (b) reacting said compound with a molar excess of dicarboxylic acid chloride in the presence of a base, e.g., triethylamine and optionally (c) removing the triethylamine hydrochloride salt byproduct of the reaction.
Still further provided according to the present invention is a method of sizing paper comprising sizing paper with the nucleophilic group terminated 2-oxetanone multimer of the present invention and paper sized with such surface sizing agent.
DETAILED DESCRIPTION OF THE INVENTION
A new class of sizing agent was made by reacting a compound having a nucleophilic group, such as an alcohol with a molar excess of a dicarboxylic acid chloride in the presence of a base that is suitable to catalyze the formation of ketene monomer and ketene dimer from carboxylic acid chlorides. Practically any tertiary amine is suitable, e.g. triethylamine, tripropylamine, tributylamine, dimethylaniline, etc. The preferred catalysts are the tertiary amines and the most preferred catalyst is triethyl amine.
Tertiary amines disclosed in U.S. Pat. No. 5,502,218 are suitable for use in the present invention. Accordingly the tertiary amine used in the present process can be a monoamine or diamine. The tertiary amine should be liquid at the reaction conditions. The tertiary amine is suitably a monoamine of the formula R
1
R
2
R
3
N, wherein R
1
, R
2
and R
3
independent of each other can be alkyl, alkenyl, aralkyl such as benzyl, or cycloalkyl groups having from 1 to 10 carbon atoms, or R
1
and R
2
together can form an alkylene chain having up to 6, preferably 4 to 5 carbon atoms, whereby the amines are selected so that the total number of carbon atoms give an amine which is liquid at the reaction conditions. Aliphatic amines are preferred and they preferably have from 1 to 6 carbon atoms in each R group. Suitable amines can be selected from triethylamine, diethylmethylamine, dimethylcyclohexylamine, di-isopropylethylamine, tripropylamine, N-methylpyrrolidine and N-methylpiperidine. The use of blends of two or more amines is, of course, also within the scope of the invention. Triethylamine (TEA) is the preferred tertiary amine, mainly for its physical properties and for economic reasons.
Although a monofunctional carboxylic acid chloride, such as those described in WO97/3018, can be incorporated into the reaction, it is not needed to control the molecular weight of the ketene multimer. Since no monofunctional carboxylic a
Brungardt Clement L.
Riehle Richard J.
Vallance Ian
Zhang Jian Jian
Hercules Incorporated
Samuels Gary A.
Trinh Ba K.
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