Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
2000-09-13
2002-09-03
Boykin, Terressa M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C528S272000
Reexamination Certificate
active
06444780
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a method of producing polyetherester monomer and cement dispersion agents (or cement dispersants). It has been known to produce polyetherester monomer as an intermediate product by an esterification reaction of polyalkyleneglycol with a closed end and unsaturated carboxylic acid and to copolymerize this polyetherester monomer with vinyl monomers which are copolymerizable therewith to obtain vinyl copolymers that can be used widely as a dispersant, an antistatic agent, an antifogging agent, an emulsifier or an adherent. In such applications, the quality of the monomer to be used in such a copolymerization reaction, and in particular the quality of polyetherester monomer, is known to significantly affect the quality of the produced vinyl copolymer serving as a dispersant, an antistatic agent, an antifogging agent, an emulsifier or an adherent. In other words, if the quality of polyetherester monomer obtained as the intermediate product is not sufficiently high, vinyl copolymers produced therefrom cannot function satisfactorily as a dispersant, an antistatic agent, an antifogging agent, an emulsifier or an adherent.
U.S. Pat. Nos. 4,962,173 and 5,362,829, for example, disclosed water-soluble vinyl copolymers having polyalkyleneglycol chain as a side chain serving as cement dispersants capable of providing a superior fluidity characteristic with a small slump loss to hydraulic cement compositions such as mortar and concrete. Such a water-soluble vinyl copolymer is usually produced by first preparing polyetherester monomer as an intermediate product by an esterification reaction of polyalkyleneglycol with a closed end and unsaturated carboxylic acid and then copolymerizing it with vinyl monomers capable of copolymerizing therewith. In this case, the quality as a cement dispersant of the water-soluble vinyl copolymer which is obtained is significantly dependent on the quality of the monomer, and in particular that of polyetherester monomer, that is used in the copolymerization reaction. In other words, if the polyetherester monomer serving as an intermediate product is of a poor quality, fluidity cannot be provided to a satisfactory manner to a hydraulic cement composition when the water-soluble vinyl copolymer obtained therefrom is used as a cement dispersant. The fluidity which has been provided has a large slump loss in such a case, and products obtained by hardening such a hydraulic cement composition have a low compressive strength.
As disclosed in Japanese Patent Publication Tokkai 11-71151, such polyetherester monomers as described above have conventionally been produced by using an organic solvent with a low boiling point such as benzene in an esterification reaction of polyalkyleneglycol with a closed end and unsaturated carboxylic acid. Use of such an organic solvent with a low boiling point is advantageous in that it is possible to obtain polyetheresters of a fairly high quality. On the other hand, the solvent which has been used for the reaction must be collected and the cost of equipment therefor adds to the total production cost of the polyetherester, or that of the vinyl copolymer to be used as the intermediate product and that of the water-soluble vinyl copolymers serving as a cement dispersant. In addition, the workers will be forced to work in an undesirable environment due to some of the properties of these substances.
SUMMARY OF THE INVENTION
It is therefore an object of this invention to provide a method of producing polyetherester monomer of a high quality without using a solvent.
It is another object of this invention to provide water-soluble vinyl copolymers capable of serving as a cement dispersant with improved properties, obtainable from such polyetherester monomer.
The present inventors discovered, as a result of work in view of the above objects, firstly that polyetherester monomer of a high quality can be obtained by an esterification reaction of polyalkyleneglycol with a closed end and unsaturated carboxylic acid under a specified condition in the presence of a specified amount of p-benzoquinone and/or phenothiazine and in the absence of any solvent, and secondly that water-soluble vinyl copolymers obtained by a radical copolymerization reaction of this polyetherester monomer with vinyl monomers which are copolymerizable therewith in an aqueous solution have improved properties as a cement dispersant.
DETAILED DESCRIPTION OF THE INVENTION
This invention relates, on one hand, to a method of producing polyetherester monomer shown by Formula 3 given below, by causing an esterification reaction of polyalkyleneglycol with a closed end shown by Formula 1 given below and unsaturated carboxylic acid shown by Formula 2 given below by using an acid catalyst under a heated and reduced-pressure condition in the absence of solvents and in the presence of p-benzoquinone and/or phenothiazine in an amount of 0.03-0.5 weight % of polyalkyleneglycol with a closed end while distilling away generated water, where Formulas 1, 2 and 3 are respectively:
where R
1
and R
2
are each H or methyl group, R
3
is alkyl group with 1-22 carbon atoms, benzyl group, phenyl group or alkylphenyl group having alkyl group with 1-12 carbon atoms, and A is residual group obtained by removing all hydroxyl groups from polyalkyleneglycol of which the repetition number of oxyalkylene units (consisting either only of oxyethylene units or of both oxyethylene units and oxypropylene units) being 5-250. This invention relates, on the other hand, to cement dispersants characterized as comprising water-soluble vinyl copolymer obtained by a radical copolymerization reaction of polyetherester monomer produced by a method described above and vinyl monomers that can be copolymerized therewith.
According to this invention, explained more in detail, polyalkyleneglycol with a closed end shown by Formula 1 and unsaturated carboxylic acid shown by Formula 2 are caused to undergo an esterification reaction in the absence of a solvent to obtain polyetherester monomer shown by Formula 3. Examples of R
3
in Formula 1 for polyalkyleneglycol with a closed end include (1) alkyl groups with 1-22 carbon atoms such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, hexyl group, octyl group, decyl group, dodecyl group, tetradecyl group, hexadecyl group, octadecyl group, eicosanyl group and docosanyl group; (2) benzyl group; (3) phenyl group; and (4) alkylphenyl groups having alkyl group with 1-12 carbon atoms such as methylphenyl group, ethylphenyl group, propylphenyl group, isopropylphenyl group, butylphenyl group, hexylphenyl group, octylphenyl group, nonylphenyl group and dodecylphenyl group. Among these, however, alkyl groups with 1-12 carbon atoms and benzyl group are preferable and alkyl groups with 1-3 carbon atoms are even more preferable.
As for A in Formulas 1 and 3, examples thereof include (1) residual groups obtained by removing all hydroxyl groups from polyethyleneglycol of which the oxyalkylene units are all oxyethylene units and (2) residual groups obtained by removing all hydroxyl groups from polyethylene-polypropyleneglycol of which the oxyalkylene units include both oxyethylene units and oxypropylene units, but residual groups obtained by removing all hydroxyl groups from polyethyleneglycol are preferred. If residual groups obtained by removing all hydroxyl groups from polyethylene-polypropyleneglycol are used as A, the repetition of its oxyethylene and oxypropylene units may be by random and/or block connections. The repetition number of the oxyalkylene units in the residual group representing A is 5-250, and is preferably 7-90.
Examples of polyalkyleneglycol with a closed end shown by Formula 1 include methoxy polyethyleneglycol, methoxy polyethyleneglycol-polypropyleneglycol, ethoxy polyethyleneglycol, ethoxy polyethyleneglycol-polypropyleneglycol, propoxy polyethyleneglycol, propoxy polyethyleneglycol-polypropyleneglycol, butoxy polyethyleneglycol, lauryloxy polyethyleneglycol, butoxy polyethyleneglycol-polypropylenegl
Kinoshita Mitsuo
Okada Kazuhisa
Beyer Weaver & Thomas LLP
Boykin Terressa M.
Takemoto Yushi Kabushiki Kaisha
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