Cement admixture, concrete, and process for producing...

Details Cement admixture, concrete, and process for producing... Cement admixture, concrete, and process for producing...

1999-05-28

2002-01-22

Richter, Johann (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Oxygen containing

C568S045000, C568S606000

Reexamination Certificate

active

06340779

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a cement admixture which comprises specific fluorine-containing compounds and concrete containing said cement admixture. The present invention further relates to a method for producing specific fluorine-containing compounds. The present invention still further relates to a novel surface active agent.
BACKGROUND ART
In order to improve the strength of the hardened product of concrete, it is most effective to reduce the water content of concrete. However, there are drawbacks that if the water content is reduced, fluidity of fresh concrete may decrease, whereby workability at the work site may significantly deteriorate.
In recent years, along with the increase in high-rise buildings, labor-saving is required, and fluidity of fresh concrete is thereby required. Simultaneously, the hardened product of concrete is required to have high strength including anti-earthquake property. Accordingly, concrete is required to satisfy both of the two performances which are in an antinomic relation to each other.
The following methods have been proposed for such requirements.
(1) A method to add, as an air-entraining agent (AE agent), a compound having terminal hydroxyl groups of (polyoxyethylene)aryl ether substituted by alkoxy groups to concrete to improve workability and freezing damage property, and to add an emulsion stabilizer for latex to prevent cracks.
(2) A method to use a block copolymer of oxyethylene and oxypropylene as a water reducing agent and a dispersing agent for concrete.
(3) A method to use an addition product of higher alcohol alkylene oxide, as an air-entraining agent and an emulsion stabilizer for latex.
(4) A method to use polyoxyalkylene glycol as a dispersing agent for e.g. asbestos or glass wool, which are fibers to be incorporated in concrete, and a method to use polyoxyalkylene glycol together with a cement dispersing agent such as lignin sulfonic acid, to further raise dispersibility of the fibers.
Further, the following methods have been proposed to reduce the shrink of the hardened product of concrete.
(5) A method to add an alkylene oxide compound to concrete (JP-A-2-1789).
(6) A method to add a compound having a higher carboxylic acid and alkylene oxide added thereto, to concrete (JP-A-5-70196, JP-A-3-290342).
Further, the following method has been proposed to obtain high hardness.
(7) A method to add a surface active agent containing an anionic surface active agent which comprises a hydrocarbon compound as a main component, to concrete.
Further, the following methods have been proposed to prevent reduction in fluidity of concrete when the water content is reduced.
(8) A method to add a surface active agent of fluorine type which comprises a compound having e.g. a sulfonyl bond, an ester bond or an amide bond, inserted between a perfluoroalkyl group and an oxyalkylene group (JP-A-7-17752).
(9) A method to use a surface active agent of hydrocarbon type together with the surface active agent of fluorine type as mentioned in (8) (JP-A-2-1789, JP-A-1-53215).
On the other hand, as the method for producing a compound containing a perfluoroalkyl group and an oxyalkylene group, the following methods have been proposed.
(10) A method in which a compound having a perfluoroalkyl group and a hydroxyl group connected therewith by means of an ethylene group (hereinafter referred to as perfluoroalkyl ethanol) is used as an initiator, and when ring opening polymerization of the alkylene oxide therewith is conducted, a three way catalyst made of NaI/I
2
/NaBH
4
is used (WO95-35272).
(11) A method to react a tosylate of polyalkylene glycol with a perfluoroalkyl ethanol (JP-B-7-103059).
(12) A method in which perfluoroalkyl ethanol is used as an initiator, and when ring opening polymerization of the alkylene oxide compound therewith is conducted, a double metal cyanide complex is used as a catalyst (JP-A-3-290430).
However, there are following drawbacks in the above-mentioned proposals.
In the methods (1) to (4), both performances of strength after concrete is hardened and fluidity of fresh concrete are inadequate.
In proposals (5) and (6), in the case where the water content is reduced, a drawback is confirmed such that fluidity of fresh concrete decreases.
In the method (7), in order to obtain performance, it is required to add a large amount of surface active agent, and even if a large amount of surface active agent is added, strength and fluidity are inadequate.
In the methods (8) and (9), when the surface active agent is added to concrete, a problem of foaming phenomenon (a phenomenon such that foams are likely to foam, and formed foams hardly disappear) is confirmed. Further, concrete is likely to involve air during mixing, whereby apparent density after hardened decreases, and as a result, a problem such that the strength of the hardened product of concrete decreases is confirmed. Particularly in the case of employing a conventional fluorine-containing surface active agent having an amide bond or an ester bond between a perfluoroalkyl group and an oxyalkylene group, foaming phenomenon is significant, and depending upon the conditions of use of concrete, a problem such that the fluorine-containing surface active agent is hydrolyzed is confirmed. Further, among fluorine-containing surface active agents as described in the above references, some are hardly available practically, and some are extremely expensive even if they are available, whereby some of the fluorine-containing surface active agents can not be used practically.
Further, there are following problems in the above-mentioned method.
In the method (10), a special catalyst is used, and the control of the reaction is difficult. Further, it is disadvantageous in view of cost, and the method can not be industrially used practically. Further, the foaming phenomenon is confirmed.
In the method (11), the side reaction occurs, whereby the yield of the desired compound will be extremely low.
In the method (12), purification after the reaction takes a lot of time and labor. Further, in the case where the metal complex remains in the compound obtained by said method, performance as a cement admixture tends to decrease.
In each method (10) to (12), if it is attempted to change the structure of the initiator or to change the kind of the oxyalkylene group, the reaction is less likely to proceed, and such methods can not be used widely.
DISCLOSURE OF THE INVENTION
The present inventors have studied on a cement admixture, i.e. compounds having an excellent performance as an additive to be added to concrete for the purpose of improving fluidity, and found a mixture of the following fluorine-containing compounds. Further, they have found a method for effectively producing specific fluorine-containing compounds among said compounds, and a novel surface active agent.
Namely, the present invention provides a cement admixture which is a mixture of fluorine-containing compounds represented by the formula (1), and which is fluorine-containing compounds having a ratio of the weight average molecular weight (M
w
) to the number average molecular weight (M
n
) (i.e. M
w
/M
n
) of at least 1.1:
R
f
—Q
1
—O—(A
1
—O)
k
—R
1
  (1)
wherein R
f
is a C
1-22
polyfluoroaliphatic hydrocarbon group which may contain ethereal oxygen atoms or thioethereal sulfur atoms, Q
1
is a C
1-5
linear or branched alkylene group, k is an integer of from 1 to 100, A
1
is a C
2-4
linear alkylene group or a group having at least one hydrogen atom of said alkylene group substituted by a hydrocarbon group which may contain ethereal oxygen atoms, provided that when k is from 2 to 100, the plurality of A
1
may be the same or different, and R
1
is a hydrogen atom, a C
1-18
hydrocarbon group or a C
1-18
acyl group, concrete which contains the cement admixture, a method for producing fluorine-containing oxyalkylene compounds and a novel surface active agent.
The mixture having a ratio of the weight average molecular weight (M
w
) to the number average molecular weight (M
n
) (M
w
/M
n
) of at least 1.1 o

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