Mixtures of polysiloxane emulsions

Details Mixtures of polysiloxane emulsions Mixtures of polysiloxane emulsions

2003-01-14

2004-11-09

Moore, Margaret G. (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...

C008SDIG001

Reexamination Certificate

active

06815493

ABSTRACT:

This invention concerns compositions preparable by mixing two different dispersions of amino-functional polyorganosiloxanes. It further concerns the use of such compositions for treating fiber materials.
It is known to treat fiber materials, especially textile fabrics in the form of wovens, knits or nonwovens, with aqueous dispersions of polyorganosiloxanes. This treatment frequently forms part of the textile finishing stage. Judicious choice of the polyorganosiloxanes used will provide water-repellent properties and a pleasantly soft hand on the fiber materials. Especially polyorganosiloxanes containing moieties with amino groups will provide a soft hand. A particular advantage lies in the use of microemulsions. Microemulsions are transparent with a bluish to clear appearance and frequently contain the polyorganosiloxanes in the form of smaller particles than macroemulsions. While macroemulsions constitute a milkily turbid system, microemulsions are transparent to slightly opalescent.
Dispersions of amino-functional polyorganosiloxanes, their preparation and their use for treating textiles are known and described inter alia in U.S. Pat. Nos. 5,540,952 and 5,688,889 and also EP-A 441 530. The preparation and use of microemulsions of amino-functional polyorganosiloxanes is revealed in U.S. Pat. No. 4,620,878. A particularly suitable process for preparing such microemulsions is disclosed in U.S. Pat. No. 5,057,572.
EP-A 978 586 describes aqueous microemulsions containing an amino-functional polyorganosiloxane and a nonnitrogenous polyorganosiloxane. The reference states that such microemulsions are capable of providing fiber materials finished therewith not only with a smooth surface but also with “internal softness”. It would be desirable, according to the reference, to combine microemulsions of amino-functional polyorganosiloxanes with macroemulsions of dimethylpolysiloxane by mixing, but this fails because of the instability of the mixtures obtained.
It is an object of the present invention to provide aqueous polyorganosiloxane compositions that are preparable by simply mixing two separately prepared polyorganosiloxane dispersions and that confer not only a very pleasant internal softness but also a very smooth surface on textile fiber materials.
This object is achieved by a composition obtainable by combining a first aqueous dispersion A), which contains an amino-functional polyorganosiloxane, with a second aqueous dispersion B), which contains an amino-functional polyorganosiloxane, said polyorganosiloxane in said dispersion A) having a nitrogen content of at least 0.1% by weight and said polyorganosiloxane in said dispersion B) having a nitrogen content of at least 0.01% by weight, said dispersion A) being a microemulsion and said dispersion B) being a macroemulsion.
It was surprisingly found that simply mixing said dispersion A) with said dispersion B) provides a stable composition in the form of an aqueous dispersion. Such a composition provides not only an excellent internal softness, i.e., a very pleasantly soft hand, but also a very smooth surface on fiber materials treated therewith. This is believed to be because dispersion A) is a microemulsion which has small particles that are capable of penetrating into the fiber structure and lead to the soft hand, whereas macroemulsion B) has larger particles that remain behind on the surface of the fiber material. The exclusive use of amino-functional polyorganosiloxanes provides an even softer hand on textile fiber materials treated therewith than the additional use of a nonnitrogenous polysiloxane as described in EP-A 978 586.
To obtain the advantages described, dispersion A) must be a microemulsion. Only that will provide polyorganosiloxane particles small enough to be able to penetrate into the interior of the fiber material.
The polyorganosiloxane in the aqueous dispersion A) (microemulsion) must have a nitrogen content (reckoned as N) of at least 0.1% by weight. It has been determined that a lower nitrogen content will not provide suitable microemulsions, especially with regard to the stability of the emulsion.
By contrast, the polyorganosiloxane in the aqueous dispersion B) (macroemulsion) may have a lower nitrogen content. But the nitrogen content must be at least 0.01% by weight of N.
The polyorganosiloxane in dispersion A) can be the same as that in dispersion B), provided its nitrogen content is at least 0.1% by weight. Preferably, however, the polyorganosiloxane of dispersion A) has a higher nitrogen content than that of dispersion B), especially an at least 10% higher nitrogen content. For instance, the polysiloxane of dispersion B) may contain 0.3% by weight of N and that of dispersion A) 0.4% by weight of N, i.e., a 33% higher content.
In a further preferred-embodiment of compositions according to the invention, said polysiloxane of said dispersion A) has a nitrogen content of 0.1 to 1.5% by weight and said polyorganosiloxane of said dispersion B) has a nitrogen content of 0.01 to 1.5% by weight preferably of 0.01 to 1.3% by weight of N.
The aforementioned values of respectively 0.1% by weight and 0.01% by weight for the minimum nitrogen content are based on the total nitrogen present in the polyorganosiloxane of dispersion A) and in the polyorganosiloxane of dispersion B) respectively, regardless of whether these polysiloxanes contain only a single amino group or additionally further nitrogenous groups.
Compositions according to the invention are obtainable in a simple manner by combining a separately prepared microemulsion with a separately prepared macroemulsion. This makes it possible to prepare compositions according to this invention that do not have the stability problems described in EP-A 978 586.
Preferably not only the polysiloxane in dispersion A) but also that in dispersion B) is a polymer having an unbranched polysiloxane chain, i.e., substituents attached to the silicon atoms of the chain preferably do not contain any further silicon atoms.
In a further preferred embodiment in the polysiloxane of both said dispersion A) and said dispersion B) all silicon atoms in the chain other than the two terminal silicon atoms have attached to them only methyl groups or radicals that contain one or more amino groups. Normally not only in dispersion A) but also in dispersion B) every silicon atom sites at least one alkyl radical of 1 to 6 carbon atoms, preferably a methyl radical. Some of the silicon atoms within the chain may site two such alkyl radicals. However, at least one silicon atom in the chain must site a radical containing one or more amino groups; only in this case will an amino-functional polysiloxane be present for the purposes of the invention. This radical, containing one or more amino groups, is preferably an X radical of the hereinbelow specified kind. All alkyl radicals mentioned here are preferably methyl groups. The two silicon atoms at the ends of the polysiloxane chain may independently—not only in the case of dispersion A) but also in the case of dispersion B)—each possess three alkyl groups, especially three methyl groups or two alkyl groups, especially two methyl groups and one hydroxyl group or an OR group as substituents, in which case R is an alkyl radical of 1-14 carbon atoms, preferably a methyl radical. It is particularly preferable for the polysiloxane in dispersion B) to be an aminofunctional &agr;,&ohgr;-dihydroxypolyorganosiloxane and/or for the polysiloxane of dispersion A) to be an amino-functional &agr;,&ohgr;-trimethylsilylpolyorganosiloxane.
The polyorganosiloxanes of dispersion A) and dispersion B) may have the same or different chemical structures. But, in accordance with the statement made above and in claim 1, they must have a certain minimum content of nitrogen. Preferably either or both of the polyorganosiloxanes used for A) and B) has a structure of the general formula (I)
R
1
(CH
3
)
2
Si—O&Brketopenst;Si(CH
3
)(Y)—O&Brketclosest;
z
&Brketopenst;Si(CH
3
)
2
—O&Brketclosest;
m
&Brketopenst;Si(CH
3
)(X)—O&Brketclosest;
n
Si(CH
3
)
2
R
1
  (I)
where the i

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