Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1999-10-19
2001-11-20
Metzmaier, Daniel S. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S745000, C524S747000, C524S837000, C516S058000, C516S059000, C528S034000, C106S002000, C106S287140
Reexamination Certificate
active
06319980
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for preparing an organic silicon compound emulsion. More specifically, the invention relates to a method for preparing an organic silicon compound emulsion for quickly imparting excellent water-repellent properties to porous inorganic base materials such as concrete, mortar, and masonry.
BACKGROUND OF THE INVENTION
It is well known that organoalkoxysilanes are useful as water-repellent agents for porous inorganic base materials, i.e., construction materials such as concrete, mortar, and masonry. Such water-repellent agents are normally used in the form of organic solutions prepared by dissolving organoalkoxysilanes in organic solvents. However, the organic solvents used for the above purposes are toxic and easily flammable. Furthermore, since they raise a question of environmental pollution, a need exists for water-repellent agents in the form of water-based emulsions prepared by emulsifying organoalkoxysilanes with the use of water as a diluent.
It has been proposed to use water-repellent agents in the form of emulsion compositions prepared by emulsifying an alkylalkoxysilane with the use of nonionic surfactants having a HYDROPHILE-LIPOPHILE BALANCE (HLB) within the range of 4 to 15. In this regard, reference may be had to Japanese Examined Patent Application (Kokoku) HEI 3-13195/U.S. Pat. No. 4,648,904 issued Mar. 10, 1987. For emulsion compositions prepared by emulsifying an alkylalkoxysilane with the combined use of both nonionic surfactants and anionic surfactants, reference may be had to Japanese Unexamined Patent Application (Kokai) HEI 4-114979.
However, since the alkylalkoxysilane and water are separated from each other over time, the aforementioned compositions are inferior to the organic-solvent type water-repellent agents with regard to their storage properties. Furthermore, when they are applied onto the surfaces of porous inorganic base materials, they cannot impart sufficient water-repellent properties to these surfaces.
It was proposed, therefore, to solve these problems by means of an emulsion composition prepared by emulsifying an organoalkoxysilane and an organopolysiloxane of a specific structure with the use of an anionic emulsifier. In this regard, reference may be had to Japanese Unexamined Patent Application (Kokai) HEI 6-313167. However, this emulsion composition required a significant drying time until the coated surface could reach sufficient water-repellent properties. In addition, the obtained water-repellent properties quickly deteriorated.
BRIEF SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a method for preparing an organic silicon compound emulsion capable of quickly imparting excellent surface water-repellent properties to inorganic porous materials such as concrete, mortar, and masonry.
The first embodiment of the present invention provides a method for preparing an organic silicon compound emulsion comprising the steps of:
emulsifying a mixture of the following components:
(A) 100 parts by weight of an organoalkoxysilane represented by the following general formula:
R
1
a
Si(OR
2
)
4−a
where R
1
represents identical or different monovalent hydrocarbon groups having 1 to 20 carbon atoms, R
2
is an alkyl group having 1 to 3 carbon atoms, and a is 1 or 2;
(B) 1 to 200 parts by weight of an organopolysiloxane having in its molecule at least 2 alkoxy groups or hydroxyl groups bonded to a silicon atom;
(C) an anionic emulsifying agent;
(D) water; and
heat aging the obtained emulsion at a temperature below 100° C.
According to the second embodiment, the present invention provides a method for preparing an organic silicon compound emulsion comprising the steps of:
emulsifying a mixture of the following components:
(A) 100 parts by weight of an organoalkoxysilane represented by the following general formula:
R
1
a
Si(OR
2
)
4−a
where R
1
represents identical or different monovalent hydrocarbon groups having 1 to 20 carbon atoms, R
2
is an alkyl group having 1 to 3 carbon atoms, and a is 1 or 2;
(B) 1 to 200 parts by weight of an organopolysiloxane having in its molecule at least 2 alkoxy groups or hydroxyl groups bonded to a silicon atom;
(C) an anionic emulsifying agent;
(D) water; and
adding an acidic or alkaline substance to the obtained emulsion.
According to the third embodiment, the present invention provides a method for preparing an organic silicon compound emulsion comprising the steps of:
mixing the following components:
(A) 100 parts by weight of an organoalkoxysilane represented by the following general formula:
R
1
a
Si(OR
2
)
4−a
where R
1
represents identical or different monovalent hydrocarbon groups having 1 to 20 carbon atoms, R
2
is an alkyl group having 1 to 3 carbon atoms, and a is 1 or 2;
(B) 1 to 200 parts by weight of an organopolysiloxane having in its molecule at least 2 alkoxy groups or hydroxyl groups bonded to a silicon atom;
(C) an anionic emulsifying agent;
(D) water;
adding an acidic or alkaline substance to the obtained mixture; and
emulsifying the mixture.
DETAILED DESCRIPTION OF THE INVENTION
The organoalkoxysilane component (A) suitable for the purposes of the present invention is represented by the following general formula:
R
1
a
Si(OR
2
)
4−a
In this formula, R
1
represents monovalent hydrocarbon groups having 1 to 20 carbon atoms. These groups may be the same or different. The following are specific examples of such groups: alkyl groups such as methyl group, ethyl group, propyl group, tert-butyl group, pentyl group, n-hexyl group, heptyl group, 2-ethylhexyl group, octyl group, dodecyl group, and octadecyl group; aryl groups such as phenyl group, tolyl group, xylyl group, and naphthyl group; aralkyl groups such as benzyl group and phenethyl group; substituted alkyl groups such as fluoromethyl group, 3,3,3-trifluoropropyl group, 3,3,4,4,5,5,5-heptafluoropentyl group, and difluoromonochloropropyl group. Of these groups, alkyl groups having 4 to 10 carbon atoms are preferred, and alkyl groups having 6 to 10 carbon atoms are particularly preferred. This is because water repellency tends to become inadequate when alkyl chains which are hydrophobic components have less than four carbon atoms.
R
2
is an alkyl group having 1 to 3 carbon atoms. Specific examples include methyl groups, ethyl groups, and propyl groups. Of these groups, methyl groups or ethyl groups are preferred, although the ethyl group is most preferred when environmental considerations are taken into account. The subscript a is 1 or 2. One type of organoalkoxysilane (A) may be used alone as this component, or two or more types of organoalkoxysilane (A) may be mixed and used together.
Examples of organoalkoxysilane component (A) include methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, tert-butyltrimethoxysilane, tert-butyltriethoxysilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, decyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, tert-butylmethyldimethoxysilane, tert-butylmethyldiethoxysilane, n-hexylmethyldimethoxysilane, n-hexylmethyldiethoxysilane, octylmethyldimethoxysilane, octylmethyldiethoxysilane, decylmethyldimethoxysilane, decylmethyldiethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, methylphenyldimethoxysilane, methylphenyldiethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, 3,3,3-trifluoropropyltriethoxysilane, 3,3,3-trifluoropropylmethyldimethoxysilane, and 3,3,3-trifluoropropylmethyldiethoxysilane.
The organopolysiloxane component (B) which is the component designed to improve the emulsification stability of component (A), has at least two hydroxyl groups or alkoxy groups bonded to silicon atoms in each of its molecule. Examples include organopolysiloxanes represented by the general formula
In the formula, R
3
is a substituted or unsubstituted monovalent hydrocarbon group. The following are specific examples of such groups: methyl group
Ishikawa Hiroki
Muramoto Naohiro
Naganawa Tsutomu
Ona Isao
Sakuma Atsushi
Cesare James L. De
Dow Corning Toray Silicone Company, Ltd.
Metzmaier Daniel S.
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