Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
1999-08-06
2001-09-18
Boykin, Terressa M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
Reexamination Certificate
active
06291629
ABSTRACT:
The invention relates to liquid crystalline chiral nematic polyesters.
Liquid crystalline phases, called mesophases, may occur on heating substances with shape anisotropy. The individual phases differ by the spatial arrangement of the centers of mass of the molecules on the one hand and by the arrangement of the molecules with respect to the long axes on the other hand (G. W. Gray, P. A. Winsor, Liquid Crystals and Plastic Crystals, Ellis Horwood Limited, Chichester 1974). The nematic liquid crystalline phase is distinguished by parallel orientation of the long axes of the molecules (one-dimensional order state). Provided that the molecules forming the nematic phase are chiral, the result is a chiral nematic (cholesteric) phase in which the long axes of the molecules form a helical superstructure perpendicular thereto (H. Baessler, Festkörperprobleme XI, 1971). The chiral moiety may be present in the liquid crystalline molecule itself or else be added as dopant to the nematic phase, inducing the chiral nematic phase. This phenomenon was first investigated on cholesterol derivatives (eg. H. Baessler, M. M. Labes,
J. Chem. Phys
. 52 (1970) 631).
The chiral nematic phase has special optical properties: a high optical rotation and a pronounced circular dichroism resulting from selective reflection of circularly polarized light within the chiral nematic layer. If the pitch of the helical superstructure corresponds to the wavelength of visible light, there is formation of what is called a Grandjean texture. The colors appear different depending on the angle of view and depend on the pitch of the helical superstructure, which in turn depends on the twisting ability of the chiral component. It is possible in this case, in particular by altering the concentration of a chiral dopant, to vary the pitch and thus the wavelength range of the selectively reflected light of a chiral nematic layer. Chiral nematic systems of this type have interesting possibilities for practical use. Thus, a stable, colored network can be produced by incorporating chiral moieties into mesogenic acrylates and orienting in the chiral nematic phase, eg. after photocrosslinking, but the concentration of chiral component therein can no longer be changed (G. Galli, M. Laus, A. Angelon,
Makromol. Chemie
187 (1986) 2289). Admixing noncrosslinkable chiral compounds to nematic acrylates makes it possible to prepare, by photocrosslinking, a colored polymer which still contains large amounts of soluble components (I. Heyndricks, D.
J. Broer, Mol. Cryst. Liq. Cryst
. 203 (1991) 113). It is furthermore possible, by random hydrosilylation of mixtures of cholesterol derivatives and acrylate-containing mesogens with defined cyclic siloxanes and subsequent photopolymerization, to obtain a chiral nematic network in which the chiral component may form a proportion of up to 50% of the material employed; however, these polymers still contain marked amounts of soluble materials (F. H. Kreuzer, R. Mauerer, Ch. Müller-Rees, J. Stohrer, Contribution No. 7, 22nd Liquid Crystals Meeting, Freiburg, 1993).
DE-A-35 35 547 describes a process in which a mixture of cholesterol-containing monoacrylates can be processed, by photocrosslinking, to chiral nematic layers. However, the total amount of the chiral component in the mixture is about 94%. Although a material of this type, as pure side chain polymer, does not have very high mechanical stability, the stability can be increased by highly crosslinking diluents.
Many chiral nematic polyesters in which the mesogenic structures are incorporated into the main chain are also known, eg. from S. Vilasagar, A. Blumstein,
Mol. Cryst. Liq. Cryst
. (1980), 56 (8), 263-9; A. Blumstein, S. Vilasagar, S. Ponratham, S. B. Clough, R. B. Blumstein, G. Maret,
J. Polym. Sci. , Polym. Phys. Ed
. (1982), 20 (5), 877-92; E. Chiellini, G. Galli, C. Malanga, N. Spassky,
Polym. Bull
. (1983), 9 (6-7), 336-43); H. J. Park, J. I. Jin, R. W. Leng,
Polymer
(1985), 26 (9), 1301-6; J. I. Jin, E. J. Choi, K. Y. Lee,
Polym. J
. (1986), 18 (1), 99.101; J. I. Jin, S. C. Lee, S. D. Chi, J. H. Chang;
Pollimo
(1986), 10 (4), 382-8; J. I. Jin, E. J. Choi, B. W. Jo,
Pollimo
(1986), 10 (6), 635-40; J. M. G. Cowie, H. H. Wu,
Makromol. Chem
. (1988), 189 (7), 1511-16; V. V. Zuev, I. G. Denisov, S. S. Skorokhodov,
Vysokomol. Soedin., Ser. A
(1989, 31 (5), 1056-61; A. S.
Angeloni, D. Caretti, C. Carlini, E. Chiellini, G. Galli, A. Altomare, R. Solaro, M. Laus,
Liq. Cryst
. (1986), 4 (5), 513-27; K. Fujishiro, R. W. Lenz,
Macromolecules
(1992), 25 (1), 88-95; K. Fujishiro, R. W. Lenz,
Macromolecules
(1992), 25 (1), 81-7; V. V. Zuev, I. G. Denisov, S. S. Skorokhodov,
Vysokomol. Soedin., Ser. B
(1992), 34 (3), 47-54); V. V. Zuev, I. G. Denisov, 40 S. S.
Skorokhodov Vysokomol. Soedin., Ser. B
(1989), 31 (2), 130-2.
These polyesters as a rule have narrow ranges of existence of the chiral nematic phase and contain mainly open-chain chiral components which have a low twisting ability so that relatively large contents of these components are necessary in order to obtain a color. This limits the choice of the remaining polyester constituents, eg. in respect of their mechanical properties.
DE-A-19504913.6 describes chiral nematic polyesters with strongly twisting chiral diol components, in particular dianhydro sugars, and wide liquid crystalline phase ranges.
EP-A-682 092 describes surface coatings based on chiral nematic polymers. Examples mentioned are polyesters prepared by polycondensation of dicarboxylic acids and diols.
DE-A-19631658 describes chiral nematic polycarbonates prepared by various types of polycondensation of diols with phosgene or diphosgene.
DE-A-44 41 651 discloses a process for the surface coating of substrates with a coating composition which contains at least one polymerizable low molecular weight liquid crystalline compound. The use of, in particular, photochemically polymerizable, low molecular weight liquid crystalline compounds (oligoesters) in printing inks, other inks and surface-coating systems, is also described.
WO-A-96 02 597 likewise describes a process for coating or printing substances with a coating or printing composition which contains a chiral or achiral liquid crystalline monomer and a non-liquid crystalline chiral compound. The liquid crystalline monomers are preferably photochemically polymerizable bisacrylates.
WO-A-95 29 962 describes aqueous coating compositions for producing coatings whose apparent color depends on the angle of inspection and which contain pigments in platelet form from oriented, three-dimensionally crosslinked substances with a liquid crystalline structure with a chiral phase. Substances described as particularly preferred are three-dimensionally crosslinkable polyorganosiloxanes.
WO-A-95 29 961 discloses coating compositions whose apparent color depends on the angle of inspection, and use thereof in basecoats for multilayer coatings. The compositions contain pigments in platelet form, which have a color depending on the angle of inspection and consist of oriented, three-dimensionally crosslinked substances with a liquid crystalline structure with a chiral phase. Substances described as preferred are three-dimensionally crosslinkable polyorganosiloxanes.
DE-A-44 18 076 describes an effect coating composition and an effect coating using liquid crystalline interference pigments. The interference pigments consist of esterified cellulose ethers, in particular acylated hydroxypropylcellulose.
EP-A-724 005 discloses a pigment with a color which depends on the angle of inspection, its preparation and use in a surface coating composition. The pigment is obtained by three-dimensional crosslinking of oriented substances with a liquid crystalline structure with a chiral phase. Preferred substances are three-dimensionally crosslinkable polyorganosiloxanes. In order to make the pigment retain its color at elevated temperatures, it is proposed to carry out the crosslinking in the presence of at least one other compound of neutral color which contains at least two cross
Gerken Andreas
Krawinkel Thorsten
Kricheldorf Hans R.
Schuhmacher Peter
BASF - Aktiengesellschaft
Boykin Terressa M.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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