Compounds, process for their manufacture, as well as a...

Details Compounds, process for their manufacture, as well as a... Compounds, process for their manufacture, as well as a...

1999-12-17

2001-10-16

Warden, Jill (Department: 1743)

Compositions

Liquid crystal compositions

C522S170000, C522S181000, C526S318250

Reexamination Certificate

active

06303050

ABSTRACT:

BACKGROUND AND SUMMARY OF THE INVENTION
This application claims the priority of 197 14 119.6, filed Apr. 5, 1997, the disclosure of which is expressly incorporated by reference herein.
The invention relates to compounds, to a process for their manufacture as well as to a process for manufacturing liquid-crystalline polymers using these compounds.
Liquid-crystalline polymers are used mainly in the manufacture of polymer coatings and colored paints.
Polymer coatings and colored paints are very important for coating surfaces and the aesthetic designing of objects. Many different color impressions and particularly color effects, can be achieved in various ways. Current polymer coatings contain particles or pigments in a carrier polymer for providing color or special effects, such as metallic gloss. In order to achieve certain reflection effects, for example, metal tinsels, coated mica particles or interference pigments on the basis of liquid-crystalline compounds are worked into a clear paint body as the carrier polymer. For a free design of the color impression, additional other pigments may also be added.
Another possibility of effectively providing color consists of the use of liquid-crystalline polymers, copolymers, oligomers (macromonomers) or monomers. Some of these liquid-crystal materials are suitable for forming cohesive polymer films. They polymerize in the liquid-crystal phase and, in the process, produce a paint layer with a special color effect. A working into a carrier material, for example, into a clear paint, is not required.
In principle, numerous substances are known which show a liquid-crystalline state. These are, as a rule, elongated organic molecules which are suitable for taking up a certain molecular order condition. As a function of the order condition of the liquid-crystalline phase, only those wavelengths are reflected by the impinging light which interfere with the equidistant interplanar spacing of the liquid-crystalline materials. This produces certain color and reflection effects. The formation of certain liquid-crystalline phases takes place in defined temperature ranges whose position and width, in turn, depend on the chemical structure of the materials. In addition, color appearance of the liquid-crystal phases within the phase is frequently a function of the temperature; that is, during the heating and cooling of the liquid-crystalline phase, different wavelengths are reflected. In order to produce paints or other polymer coatings which have certain wavelength reflections and light effects, it is therefore necessary to fix or mechanically stabilize the liquid-crystalline phase. As a result, certain color or reflection effects can be durably retained. A liquid-crystalline phase can be fixed by a polymerization or chemical cross-linking of the starting molecules to form a dense network. For this purpose, the starting materials must contain cross-linkable reactive groups.
From the literature, liquid-crystalline monomer compounds are known which have two identical terminal reactive groups:
J. Lub, D. J. Broer, R. A. M. Hikmet, K. G. J. Nierop,
Liq. Cryst.
18/2, 319 (1995);
D. J. Broer, J Lub, G. N. Mol,
Macromolecules
26, 1244 (1993);
R. A. M. Hikmet, J. Lub, J. A. Higgins,
Polymer
34, 1736 (1993);
S. Jarohmi, J. Lub, G. N. Mol,
Polymer
35, 622 (1994). As a rule, the cross-linking of such monomers takes place photochemically by photocyclo-addition or with the addition of a photoinitiator to the monomer mixture. Likewise, thermally initiated radical cross-linkages or thermally initiated addition or condensation reactions are known. For forming a polymer film, the known liquid-crystal monomers are applied to the corresponding substrates and the polymerization reaction is initiated, in which case the terminal groups polymerize simultaneously and the finished end product is created.
The application and adhesiveness of the starting monomers on the substrate to be coated may cause serious difficulties. As a rule, liquid crystal monomers are crystalline, which is why their adhesiveness on the substrate is poor. Furthermore, application of a uniform thickness layer is difficult. In addition, with respect to the hardness, elasticity and adhesion of the end product, specifically of the polymer film, the known liquid-crystal materials are relatively invariable and unable to adapt to the requirements of certain applications.
From German Patent Application 196 43 048.8, filed on Oct. 18, 1996, liquid-crystalline compounds are known which have various terminal polymerizable radicals. During polymerization, these compounds permit a two-step process because the different reactive radicals can be cross-linked by polymerization reactions of different initiation and reaction mechanisms. As a result, prepolymers can first be produced in the form of homopolymers or copolymers with polymerization straight lines (oligomers) which are not excessive. These prepolymers can be handled more easily than the monomers themselves.
However, it is still a disadvantage in this case that the range of the compositional variation of the prepolymers is limited or hard to control. Furthermore, the transition temperature will rise with the degree of polymerization, and this is not advantageous for all applications.
It is therefore an object of the invention to provide compounds and a process for their manufacture as well as a process for manufacturing liquid-crystalline polymers on the basis of these compounds which have a larger range of variational composition while they can be handled better and permit better control of the composition.
This object is achieved by compounds and a process for their manufacture for use as a nematic phase in cholesteric liquid polymers of the general formula C—A
m
, wherein
m≧2, such that
when m=2, C is a radical of the general formula C
n
H
2n
, in which n is a whole number from 1 to 40 and at least one methylene group may be substituted by oxygen or at least one hydrogen may be substituted by alkyl or alkoxy groups, said alkyl or alkoxy groups having 1 to 20 carbon atoms,
when m>2, C is a branched and multifunctional radical and is selected from the group consisting of oligopropylene oxide, oligobutylene oxide, branched alkyls with 4 to 40 Carbon atoms, trimethylol propane, pentaerythrite, cyclohexane tricarboxylic acid, cyclohexane triole, aromatic carboxylic acids with two carboxyl groups and phenolene with at least two OH— groups, wherein
A are identical or different radicals of the general formula Y—B—M, wherein
Y is a polymerizable radical,
B are identical or different radicals of the general formula C
n
H
2n
in which n is a whole number from 0 to 20 and at least one methylene group may be substituted by oxygen, and
M has the general formula
R
1
—X
1
—R
2
—X
2
—R
3
—X
3
—R
4
—, wherein
R
1
, R
2
, R
3
and R
4
are identical or different double-bonding radicals selected from the group consisting of —O—, —COO—, —CONH, —CO—, —S—, —C≡C—, —CH═CH—, —CH═N—, —CH
2
—, —N═N—, and —N═N(O) and R
2
—X
2
—R
3
, X
3
—R
4
or R
2
—X
2
—R
3
—X
3
may be a C—C bond,
X
1
, X
2
, and X
3
are identical or different radicals selected from the group consisting of 1,2-, 1,3- or 1,4-phenylene, and 1,2-, 1,3- or 1,4-cyclohexene with at least one B radical being a substituted aryl alkane or heteroaryl alkane with 6 to 10 atoms in the aryls core, the substitution being from 1 to 3 heteroatoms selected from the group consisting of O, N, and S, and another at least one B radical being a substituted 3 to 10 carbon cycloalkane, said substituted group of the another at least one B radical being at least one identical or different substituent selected from the group consisting of —H, linear or branched C
1
- to C
20
-alkyl, C
1
- to C
20
-alkoxy, C
1
- to C
20
-alkylthio, C
1
- to C
20
-alkyl carbonyl, C
1
- to C
20
-alkoxycarbonyl, C
1
- to C
20
-alkylthiocarbonyl, —OH, —F, —Cl, —Br, —I, —CN, —NO
2
, cycloalkyl, formyl, and linear or branched alkyl, alkoxy or alkylthio radicals with 1 to 20 carbon atoms which are interrupted by ether

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