The invention relates to a heat-insulating coating which comprises one or more cholesteric IR-reflecting layers and to processes for its preparation and to its use.

The invention relates to a heat-insulating coating which comprises one or more cholesteric IR-reflecting layers.
The problem of screening against thermal radiation is important in particular in connection with the insulation of residential, office or industrial buildings. Buildings with a generous expanse of windows heat up rapidly, especially in summer and in southerly regions in particular, to such an extent that they have to be cooled at considerable energy cost by air conditioning units.
Common techniques of heat insulation, especially for screening against thermal radiation in the wavelength range between 800 nm and 2000 nm, are based on the absorption of the radiation by appropriate dyes or pigments. However, a large part of the energy absorbed is passed on by conduction to the area or item which is to be insulated.
The use of materials which substantially reflect thermal radiation is also known.
For this purpose there is widespread use of special dyes or pigments, but also graphite or gold, as broadband absorbers or reflectors.
Examples of dyes employed in this context are naphthalocyanines having broadband absorption in the infrared (IR), or else laked polymethine dyes. However, a serious disadvantage of the IR-absorbing dyes is that they exhibit marked absorption in the visible wavelength range as well, with the result that a considerable reduction in transparency is observed. The radiative energy absorbed is transformed into thermal energy which is dissipated by conduction.
Graphite, gold, silver or indium-tin oxide (ITO), which are also employed as absorbers or reflectors for IR radiation, have comparable disadvantages. Here too, especially in the visible region of the spectrum, there is very little transparency. Only highly precise and hence extensive production of extremely thin layers ensures a sufficiently uniform and high level of transmission in the visible wavelength range. Metal layers of this kind are generally applied by chemical or physical vapor deposition techniques (CVD or PVD), which are highly complex.
It is likewise known that cholesteric liquid-crystalline substances are also able to reflect light in the IR region of the electromagnetic spectrum. Cholesteric (chiral nematic) liquid crystals have already long been known. The first example of such a material was discovered by the Austrian botanist F. Reinitzer (Monatshefte Chemie, 9 (1888), 421). It is the chirality which determines the existence of cholesteric phases. The chiral moiety can either be present in the liquid-crystalline molecule itself or can be added as a dopant to the nematic phase, thereby inducing the chiral nematic phase. 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 nematic layer. A consequence of this is that not more than 50% of the incident light having the reflection wavelength is reflected. The remainder passes through without interacting with the medium. The direction of rotation of the reflected light is determined by the handedness of the helix: a right-handed helix reflects right-circularly polarized light, a left-handed helix left-circularly polarized light. By altering the concentration of a chiral dopant it is possible to vary the pitch and hence the wavelength range of selectively reflected light of a chiral nematic layer. There is a direct relationship here between the reciprocal of the observed pitch p and the concentration of the chiral compound (xch):
1/p=HTP xch
where HTP denotes the helical twisting power of the chiral dopant.
U.S. Pat. No. 4,637,896 discloses cholesteric liquid-crystalline compounds, based on cholesterol derivatives, and photopolymerized cholesteric coatings which comprise these compounds in copolymerized form. The cholesteric films described have reflection maxima which are predominantly within the visible wavelength range. However, two examples are also given of colorless films whose reflection maxima lie at 950 and 1260 nm respectively. Owing to the narrow breadth of reflection, however, these films are not suitable as a heat-insulating coating.
U.S. Pat. No. 5,629,055 discloses solid cholesteric films based on cellulose. The films are obtainable from colloid suspensions of cellulose crystallites, said colloid suspensions being prepared by acidic hydrolysis of crystalline cellulose. The solid films have cholesteric properties and their reflection wavelength is said to be adjustable over the entire spectral range from infrared to ultraviolet. The materials described are proposed in particular for use as optical authentification materials, since printing or photocopying techniques are unable to reproduce the cholesteric effect.
U.S. Pat. No. 5,352,312 describes a method of insulating rocket engines against heat and corrosives. The method comprises the use of an ablative insulating material which comprises a thermoplastic liquid-crystalline polymer. The liquid-crystalline material, however, is not cholesteric and the insulating action is based on the ablative effect and not on the reflection of thermal radiation.
U.S. Pat. No. 5,016,985 discloses an infrared filter comprising a broadband infrared filter element and a cholesteric liquid-crystalline filter element. The significance of the cholesteric filter element lies in particular in its ability to block infrared wavelengths in a precise, narrow band. The infrared filter can be used, for example, in night vision equipment.
It is an object of the present invention to provide heat insulation media which are easy to prepare, which are almost completely transparent in the visible range of the electromagnetic spectrum and which absorb very little in the near infrared and in the visible wavelength range of the electromagnetic spectrum.
We have found that this object is achieved by coatings which comprise at least one cholesteric IR-reflecting layer.
The present invention therefore provides a heat-insulating coating comprising one or more cholesteric layers and reflecting at least 40%, in particular at least 45%, of the incident radiation in the infrared wavelength range, preferably above 750 nm and, in particular, in the wavelength range from 751 nm to about 2000 nm.
The heat-insulating coating of the invention has a series of surprising advantages:
a) incident radiation in the visible wavelength range is transmitted almost completely, so that the coating appears transparent.
b) Incident light in the infrared region of the electromagnetic spectrum is very largely reflected and not absorbed, so that the object to be insulated does not heat up through conduction.
c) There is broadband reflection of incident thermal radiation, allowing the efficient insulation of articles.
d) The thickness and uniformity of the coating can be varied within a wide range without significantly effecting its insulating properties, with the result that its preparation is considerably less complex than that, for example, of metal-containing reflective coatings.
e) The use of ecologically and toxicologically objectionable metals is avoided.
f) The starting compounds for preparing the coating are readily available industrially; their use is thus generally less expensive than that of, say, gold or silver in reflective coatings.
The heat-insulating coating of the invention preferably transmits at least 80%, in particular at least 90%, of the incident radiation in the wavelength range of visible light, i e. approximately in the range from 390 nm to 750 nm.
Particular preference is given to a heat-insulating coating of the invention which comprises two or more, preferably from about 2 to 20 and, in particular, about 2 to 10 cholesteric IR-reflecting layers. With particular preference the layers have different reflection maxima in the wavelength range  greater than 750 nm. With very particular preference the heat-insulating coating of the invention comprises two or more cholesteric layers, preferably a number of cholesteric layers which can be divided by 2, such as 2, 4, 6, 8 or 10, the pitch of the helical superstructures of 2xe2x80x94preferably adjacentxe2x80x94layers in each case being identical but their handedness being different. Very particular preference is likewise given to a heat-insulating coating of the invention which between layers having a helical superstructure of identical pitch and identical handedness has a medium which reverses the direction of rotation of the transmitted circularly polarized light, especially what is known as a xcex/2 film or plate.
The use of layers of different handedness, or of a medium which reverses the direction of rotation of the transmitted circularly polarized light between layers of identical handedness, is able to increase considerably the reflection of the heat-insulating coating of the invention. In this way degrees of reflection of at least 75%, in particular at least 85%, based on the incident radiation are achieved preferably, in the wavelength range above 750 nm, in particular in the wavelength range from 751 nm to about 2000 nm.
The only restriction on the composition of the heat-insulating coating of the invention is that it must include compounds which, alone or through their interaction, give it cholesteric IR-reflecting properties. In principle, virtually all known cholesteric monomers or monomer mixtures or polymers or polymer mixtures can be adjusted in the pitch of their helical superstructure, by varying the chiral component,din such a way that their reflection maximum lies within the IR.
A preferred heat-insulating coating of the invention can comprise, for example, in the cured state cholesteric compounds or mixtures of compounds selected from
a) at least one cholesteric polymerizable monomer;
b) at least one achiral, nematic, polymerizable monomer and a chiral compound;
c) at least one cholesteric crosslinkable polymer;
d) at least one cholesteric polymer in a polymerizable diluent or a mixture of polymerizable diluents;
e) at least one cholesteric polymer whose cholesteric phase can be frozen in by rapid cooling to below the glass transition temperature; or
f) at least one achiral, liquid-crystalline crosslinkable polymer and a chiral compound.
For the purposes of the present invention, crosslinking means the covalent linking of polymeric compounds and polymerization means the covalent linking of monomeric compounds to form polymers. By curing is meant crosslinking, polymerization or the freezing-in of the cholesteric phase.
Curing fixes the uniform orientation of the cholesteric molecules in the cholesteric layer.
Preferred monomers of group a) are described in DE-A-196 02 848 and in DE-A-4 342 280, the full content of which is incorporated herein by reference. In particular, the monomers a) comprise at least one chiral, liquid-crystalline, polymerizable monomer of the formula I
[Z1xe2x80x94Y1xe2x80x94A1xe2x80x94Y2xe2x80x94M1xe2x80x94Y3xe2x80x94]nXxe2x80x83xe2x80x83(I)
where
Z1 is a polymerizable group or a radical which carries a polymerizable group,
Y1, Y2, Y3 independently are chemical bonds, oxygen, sulfur,
xe2x80x94COxe2x80x94Oxe2x80x94, xe2x80x94Oxe2x80x94COxe2x80x94, xe2x80x94Oxe2x80x94COxe2x80x94Oxe2x80x94,
xe2x80x94COxe2x80x94Sxe2x80x94, xe2x80x94Sxe2x80x94COxe2x80x94
xe2x80x94COxe2x80x94N(R)xe2x80x94, xe2x80x94N(R)xe2x80x94COxe2x80x94, CH2O or OCH2,
A1 is a spacer,
M1 is a mesogenic group,
X is an n-valent chiral radical,
R is hydrogen or C1-C4-alkyl,
n is 1 to 6
and the radicals Z1, Y1, Y2, Y3, A1 and M1 can be identical or different if n is greater than 1.
Preferred radicals Z1 are:
where each R can be identical or different and is hydrogen or C1-C4-alkyl, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl or tert-butyl. Of the reactive polymerizable groups, the cyanates are able to trimerize spontaneously to cyanurates and are therefore preferred. Polymerization of the other groups indicated requires further compounds having complementary reactive groups. Isocyanates, for example, are able to polymerize with alcohols to give urethanes and with amines to give urea derivatives. Similar comments apply to thiiranes and aziridines. Carboxyl groups can be condensed to give polyesters and polyamides. The maleimido group is particularly suitable for free-radical copolymerization with olefinic compounds such as styrene. Said complementary reactive groups can be present either in a second compound of the invention, which is mixed with the first, or can be incorporated into the polymeric network by means of auxiliary compounds containing 2 or more such complementary groups.
Particularly preferred groups Z1-Y1 are acrylate and methacrylate.
Y1-Y3 can be as defined above, the term chemical bond meaning a single covalent bond.
Suitable spacers A1 are all groups known for this purpose. The spacers contain generally from 2 to 30, preferably from 2 to 12 carbon atoms and consist of linear aliphatic groups. They may be interrupted in the chain by nonadjacent O, S, NH or NCH3, for example. Other suitable substituents for the spacer chain are fluorine, chlorine, bromine, cyano, methyl and ethyl.
Examples of representative spacers are:
where
m is 1 to 3 and
p is 1 to 12.
The mesogenic group ml preferably has the structure
(Txe2x80x94Y8)sxe2x80x94T
where Y8 is a bridge in accordance with one of the definitions of Y1, s is 1 to 3 and T is identical or different at each occurrence and is a divalent isocycloaliphatic, heterocycloaliphatic, isoaromatic or heteroaromatic radical. If s is  greater than 1, the bridges Y8 can be identical or different.
The radicals T can also be ring systems substituted by C1-C4-alkyl, C1-C4-alkoxy, fluorine, chlorine, bromine, cyano, hydroxyl or nitro. Preferred radicals T are:
Particular preference is given to the following mesogenic groups M1:
Of the chiral radicals X of the compounds of the formula I particular preference is given, not least on account of their availability, to those derived from sugars, from binaphthyl or biphenyl derivatives and from optically active glycols, dialcohols or amino acids. In the case of the sugars, particular mention should be made of pentoses and hexoses and derivatives thereof.
Examples of radicals X are the following structures, the lines at the end in each case denoting the free valences.
Particular preference is given to
Also suitable, furthermore, are chiral groups having the following structures:
Further examples are set out in the German Application P 43 42 280.2.
n is preferably 2.
Preferred monomers of group a), furthermore, are chiral polymerizable cholesterol derivatives as are described in DE-A-35 35 547 and in U.S. Pat. No. 4,637,896, the full content of which is incorporated herein by reference.
Examples of preferred monomers of group b) are described in the dissertation by H. Jonsson, Department of Polymer Technology, Royal Institute of Technology, S-10044 Stockholm, Sweden, of Jan. 25, 1991, in DE-A-4 408 171, DE-A-4 408 170 and DE-A-4 405 316, the full content of which is incorporated herein by reference. The cholesteric mixture preferably comprises at least one achiral liquid-crystalline polymerizable monomer of the formula II
Z2xe2x80x94Y4xe2x80x94A2xe2x80x94Y5xe2x80x94M2xe2x80x94Y6xe2x80x94A3xe2x80x94Y7xe2x80x94Z3)nxe2x80x83xe2x80x83(II)
where
Z2,Z3 are identical or different polymerizable groups or radicals which contain a polymerizable group,
n is 0 or 1
Y4,Y5,Y6,Y7 independently are chemical bonds, oxygen, sulfur,
xe2x80x94COxe2x80x94Oxe2x80x94, xe2x80x94Oxe2x80x94COxe2x80x94, xe2x80x94Oxe2x80x94COxe2x80x94Oxe2x80x94,
xe2x80x94COxe2x80x94Sxe2x80x94, xe2x80x94Sxe2x80x94COxe2x80x94
xe2x80x94COxe2x80x94N(R)xe2x80x94, xe2x80x94N(R)xe2x80x94COxe2x80x94, CH2O or OCH2
A2,A3 are identical or different spacers and
M2 is a mesogenic group.
The polymerizable groups, the bridges Y4 to Y7, the spacers and the mesogenic group are subject to the same preferences as the corresponding variables of the formula I.
In addition, the mixture of group b) includes a chiral compound. The chiral compound brings about the twisting of the achiral liquid-crystalline phase to form a cholesteric phase. In this context, the extent of twisting depends on the twisting power of the chiral dopant and on its concentration. Consequently, therefore, the pitch of the helix and, in turn, the reflection wavelength depend on the concentration of the chiral dopant. As a result, it is not possible to indicate a generally valid concentration range for the dopant. The dopant is added in the amount at which the desired reflection is produced.
Preferred chiral compounds are those of the formula Ia
[Z1xe2x80x94Y1xe2x80x94A1xe2x80x94Y2xe2x80x94Maxe2x80x94Y3xe2x80x94]nXxe2x80x83xe2x80x83(Ia),
where Z1, Y1, Y2, Y3, A1, X and n are as defined above and Ma is a divalent radical which comprises at least one heterocyclic or isocyclic ring system.
The moiety Ma here resembles the mesogenic groups described, since in this way a particularly good compatibility with the liquid-crystalline compound is achieved. Ma, however, need not be esogenic, since the compound Ia is intended to bring about an appropriate twisting of the liquid-crystalline phase merely by virtue of its chiral structure. Preferred ring systems present in a are the abovementioned structures T, preferred structures Ma being those of the abovementioned formula (Txe2x80x94Y8)sxe2x80x94T. Further monomers and chiral compounds of group b) are described in WO 97/00600 and its parent DE-A-195 324 08, the full content of which is incorporated herein by reference.
Preferred polymers of group c) are cholesteric cellulose derivatives as described in DE-A-197 136 38, especially cholesteric mixed esters of
(VI) hydroxyalkyl ethers of cellulose with
(VII) saturated, aliphatic or aromatic carboxylic acids and
(VIII) unsaturated mono- or dicarboxylic acids.
Particular preference is given to mixed esters in which the hydroxyalkyl radicals of component VI that are attached by way of ether functions comprise straight-chain or branched C2-C10-hydroxyalkyl radicals, especially hydroxypropyl and/or hydroxyethyl radicals. Component VI of the suitable mixed esters preferably has a molecular weight of from about 500 to about 1 million. Preferably, the anhydroglucose units of the cellulose are etherified with hydroxyalkyl radicals in an average molar degree of substitution of from 2 to 4. The hydroxyalkyl groups in the cellulose can be identical or different. Up to 50% of them can also be replaced by alkyl groups (especially C1-C10-alkyl groups). One example of such a compound is hydroxypropyl-methylcellulose.
Compounds which can be used as component VII of the mixed esters that are employable are straight-chain aliphatic C1-C10 carboxylic acids, especially C2-C6 carboxylic acids, branched aliphatic C4-C10 carboxylic acids, especially C4-C6 carboxylic acids, or straight-chain or branched halocarboxylic acids. Component VII can also comprise benzoic acid or aliphatic carboxylic acids with aromatic substituents, especially phenylacetic acid. Component VII is selected with particular preference from acetic, propionic, n-butyric, isobutyric and n-valeric acid, in particular from propionic, 3-chloropropionic, n-butyric and isobutyric acid.
Component VIII is preferably selected from unsaturated C3-C12 mono- or dicarboxylic acids or monoesters of such a dicarboxylic acid, especially xcex1,xcex2-ethylenically unsaturated C3-C6 mono- or dicarboxylic acids or monoesters of the dicarboxylic acids.
With particular preference, component VIII of the employable mixed esters is selected from acrylic, methacrylic, crotonic, vinylacetic, maleic, fumaric and undecenoic acid, especially from acrylic and methacrylic acid.
Component VI is preferably esterified with component VII and VIII in an average degree of molar substitution of from 1.5 to 3, in articular from 1.6 to 2.7 and, with particular preference, from 2.3 to 2.6. Preferably about 1 to 30%, in particular from 1 to 20% or 1 to 10%, with particular preference from about 5 to 7%, of the OH groups of component VI are esterified with component VIII.
The proportion of component VII to component VIII determines the reflection wavelength of the polymer.
Highly suitable polymers of group c), moreover, are the propargyl-terminated cholesteric polyesters or polycarbonates described in DE-A-197 17 371.
Among these compounds, preference is given to polyesters or polycarbonates having at least one propargyl end group of the formula R3Cxe2x89xa1Cxe2x80x94CH2xe2x80x94, where R3 is H, C1-C4-alkyl, aryl or Ar-C1-C4-alkyl (e.g. benzyl or phenethyl) which is attached to the polyesters or polycarbonates directly or via a linker. The linker is preferably selected from
where R4 is H, C1-C4-alkyl or phenyl, X is O, S or NR2 and R2 is H, C1-C4-alkyl or phenyl.
In the polyesters the propargyl end group is preferably attached
The polyesters preferably comprise
(IX) at least one aromatic or araliphatic dicarboxylic acid unit and/or at least one aromatic or araliphatic hydroxy carboxylic acid unit and
(X) at least one diol unit.
Preferred dicarboxylic acid units are those of the formula
especially those of the formula
it being possible for each of the phenyl groups, or the naphthyl group, to contain 1, 2 or 3 substituents selected independently of one another from C1-C4-alkyl, C1-C4-alkoxy, halogen and phenyl and where, in the above formulae,
W is NR, S, O, (CH2)pO(CH2)q, (CH2)m or a single bond,
R is alkyl or hydrogen,
m is an integer from 1 to 15 and
p and q independently are integers from 0 to 10.
Preferred hydroxy carboxylic acid units are those of the formula
where each phenyl group or the naphthyl group can have 1, 2 or 3 substituents selected independently of one another from C1-C4-alkyl, C1-C4-alkoxy, halogen and phenyl.
Preferred diol units are those of the formula
especially those of the formula
where, in the above formulae,
L is alkyl, alkoxy, halogen, COOR, OCOR, CONHR or NECOR,
X is S, O, N, CH2 or a single bond,
A is a single bond, (CH2)n, O(CH2)n, S(CH2)n, NR(CH2)n,
R is alkyl or hydrogen,
R1 is hydrogen, halogen, alkyl or phenyl and
n is an integer from 1 to 15.
Preference is given to polyesters comprising at least one dicarboxylic acid unit of the formula
and at least one diol unit of the formula
H, halogen, C1-C4-alkyl, especially CH3 or C(CH3)3, or phenyl.
Further preferred compounds are diesters of the formula P-Y-B-CO-O-A-O-CO-B-Y-P, where P is a propargyl end group of the above-defined formula, Y is O, S or NR2 (R2=C1-C4-alkyl), B is
where each phenyl group or the naphthyl group can have 1, 2 or 3 substituents selected independently of one another from C1-C4-alkyl, C1-C4-alkoxy, halogen and phenyl, and A (together with the adjacent oxygen atoms) is one of the abovementioned diol units.
Particularly preferred diesters are those of the abovementioned formula in which B is
and especially diesters of the formula
HCxe2x89xa1CCH2Oxe2x80x94Bxe2x80x94COxe2x80x94Oxe2x80x94Axe2x80x94Oxe2x80x94COxe2x80x94Bxe2x80x94OCH2xe2x80x94Cxe2x89xa1CH, where

Further preferred compounds are polycarbonates comprising at least one incorporated diol unit of the abovementioned formulae, espcially of the formulae
Preference is given here to those polycarbonates which comprise as diol units at least one mesogenic unit of the formula
at least one chiral unit of the formula
with or without a non-chiral unit of the formula
R1 being as defined above and in particular being H or CH3.
Particularly preferred polycarbonates are those having propargyl end groups of the formula HCxe2x89xa1CCH2Oxe2x80x94R5xe2x80x94CO, where R5 is
Further suitable polymers of group c) are cholesteric polycarbonates containing photoreactive groups even in a non-terminal position. Such polycarbonates are described in DE-A-196 31 658 and are preferably of the formula XIII
where the molar ratio w/x/y/z is from about 1 to 20/from about 1 to 5/from about 0 to 10/from about 0 to 10, particularly preferably from about 1 to 5/from about 1 to 2/from about 0 to 5/from about 0 to 5.
In the formula XIII
A is a mesogenic group of the formula
B is a chiral group of the formula
D is a photoreactive group of the formula
and
E is a further, non-chiral group of the formula
where, in the above formulae,
L is alkyl, alkoxy, halogen, COOR, OCOR, CONHR or NHCOR,
X is S, O, N, CH2 or a single bond,
R is alkyl or hydrogen,
A is a single bond, (CH2)n, O(CH2)n, S(Cu2)n, NR(CH2)n,
R1 is hydrogen, halogen, alkyl or phenyl and
n is an integer from 1 to 15.
If R1 is alkyl or halogen and A is a single bond, or if R1 is H or alkyl and A is
the groups are solubility-improving groups. Examples thereof are
Isosorbide, isomannide and/or isoidide is the preferred chiral component.
The proportion of the chiral diol structural units is preferably within the range from 1 to 80 mol-% of the overall content of diol structural units, with particular preference from 2 to 20 mol-%, depending on the desired reflection behavior.
Examples of preferred polymers of group d) are crosslinkable cholesteric copolyisocyanates as described in U.S. Pat. No. 5,847,068, the full content of which is incorporated herein by reference. Such copolyisocyanates have repeating units of the formulae
and, if appropriate, of the formula
where
R1 is a chiral aliphatic or aromatic radical,
R2 is a crosslinkable radical and
R3 is an achiral radical.
Unless specified otherwise alkyl here (including definitions such as alkoxy, dialkyl, alkylthio, etc.) means a branched or unbranched C1-C12-alkyl, preferably C3-C12-alkyl, with particular preference C4-C10-alkyl and, in particular, C6-C10-alkyl.
R1 is selected preferably from (chiral) branched or unbranched alkyl, alkoxyalkyl, alkylthioalkyl, cycloalkyl, alkylphenyl or C3-C9-epoxyalkyl radicals or radicals of esters of C1-C6 fatty acids with C1-C6-alkanols or C3-C6-dialkyl ketones. The ester radical can be attached to the nitrogen either by way of the fatty acid component or by way of the alkanol radical. The radical R1 can have 1, 2 or 3 substituents which are identical or different and are selected from alkoxy, di-C1-C4-alkylamino, CN, halogen or C1-C4-alkylthio groups.
R1 is preferably selected from alkyl, alkoxyalkyl, radicals of esters of C1-C6 fatty acids with C1-C6-alkanols, C3-C6-dialkyl ketones and epoxidized C3-C6-epoxyalkyl radicals, where R1 can be substituted by 1 or 2 radicals which are identical or different and are selected from alkoxy, halogen, CN and CF3. Preferred substituents of branched or unbranched alkyl or alkoxy radicals are selected from alkoxy groups, halogen atoms or CN; for esters of C1-C6 fatty acids with C1-C6-alkanols, from alkoxy groups, halogen atoms, CN and CF3, and for C3-C6-dialkyl ketones from alkoxy groups, halogen atoms and CN.
The main chain of the radical R1 has a length in particular of from 3 to 12, especially from 6 to 10 and, preferably, from 6 to 8 members (carbons, oxygens and/or sulfur atoms). Particular preference is given to radicals R1 selected from
With very particular preference, component III of the copolyisocyanates that can be employed is derived from 2,6-dimethylheptyl isocyanate.
The radical R2 of the copolyisocyanates that can be employed is preferably selected from C3-C11-alkenyl radicals, C4-C11-vinyl ether radiclas (=vinyl C2-C9-alkyl ethers), ethylenically unsaturated C3-C11 carboxylic acid radicals and esters of ethylenically unsaturated C3-C6 monocarboxylic acids with C2-C6-alkanols, the bond to the nitrogen atom being by way of the alkanol radical of the ester with particular preference the radical is selected from methyl, ethyl, propyl, n-butyl, isobutyl and 2-ethylhexyl acrylate and from methyl, ethyl, propyl, n-butyl, isobutyl and 2-ethylhexyl methacrylate, in particular from ethyl acrylate and ethyl methacrylate.
The radical R3 preferably has the same meanings as the radical R1. However, it is achiralxe2x80x94in other words, it has no center of chirality, or is present as a racemic mixture.
With particular preference, the main chain of the radical R3 has a length from 4 to 12, in particular from 6 to 10 and, preferably, from 6 to 8 members (carbon, oxygen and/or sulfur atoms). With very particular preference, component V of the copolyisocyanates of the invention is derived from n-hexyl, n-heptyl or n-octyl isocyanate.
Components III, IV and v are preferably present in a molar ratio III:IV:V of from about 1 to 20:1 to 20:50 to 98, in particular from about 5 to 15:5 to 15:65 to 90 and, with particular preference, about 15:10:75.
The units III, IV and V can be in random distribution within the copolyisocyanates that can be employed.
Suitable polymers of group e) are chiral nematic polyesters having flexible chains, which comprise isosorbide, isomannide and/or isoidide units, preferably isosorbide units, and for chain flexibilization comprise at least one unit selected from (and derived from)
(a) aliphatic dicarboxylic acids,
(b) aromatic dicarboxylic acids with a flexible spacer,
(c) xcex1, xcfx89-alkanediols,
(d) diphenols with a flexible spacer and
(e) condensation products of a polyalkylene terephthalate or polyalkylene naphthalate with an acylated diphenol and an acylated isosorbide,
as are described in DE-A-197 04 506.
The polyesters are noncrystalline and form stable cholesteric phases which can be frozen in on cooling to below the glass transition temperature. The glass transition temperatures of the polyesters, in turn, despite the flexibilization are above 80xc2x0 C., preferably above 90xc2x0 C. and, in particular, above 100xc2x0 C.
The polyesters that can be employed include as units (a) preferably those of the formula
xe2x80x94OCxe2x80x94(CH2)nxe2x80x94COxe2x80x94
where n is 3 to 15, especially 4 to 12, and with particular preference adipic acid;
as units (b) preferably those of the formula
where
A is (CH2)n, O(CH2)nO or (CH2)oxe2x80x94Oxe2x80x94(CH2)p,
n is 3 to 15, especially 4 to 12 and, with particular preference, 4 to 10, and
o and p independently are from 1 to 7;
as units (c) preferably those of the formula
xe2x80x94Oxe2x80x94(CH2)nxe2x80x94Oxe2x80x94 or xe2x80x94Oxe2x80x94(CH2xe2x80x94CH2xe2x80x94O)mxe2x80x94
where
n is 3 to 15, especially 4 to 12 and, with particular preference, 4 to 10, and
m is 1 to 10; and
as units (d) preferably those of the formula
where
A is (CH2)n, O(CH2)nO or (CH2)oxe2x80x94Oxe2x80x94(CH2)p,
n is 3 to 15, especially 4 to 12 and, with particular preference, 4 to 10, and
o and p independently are 1 to 7.
The polyesters that can be employed comprise additionally, as nonflexible acid component, preferably dicarboxylic acid units of the formula
and as nonflexible alcohol component diol units of the formula
where, in the above formulae,
L is alkyl, alkoxy, halogen, COOR, OCOR, CONHR or NHCOR,
X is S, O, N, CH2 or a single bond,
A is a single bond,
where
R1 is hydrogen, halogen, alkyl or phenyl and
R is alkyl or hydrogen.
The polyesters that can be employed may include additional flexible diol units of the formula
R1 is hydrogen, halogen, alkyl or phenyl,
A is (CH2)n, O(CH2)n, S(CH2)n or NR(CH2)n, and
n is 1 to 15.
Examples of preferred polymers of group f) are crosslinkable liquid-crystalline polyorganosiloxanes as are described in EP-A-066 137 and in EP-A-358 208. The mixture of group f) additionally comprises a chiral compound. Suitable chiral compounds are, in particular, the chiral dopants of the formula Ia described for the mixtures of group b).
With very particular preference, the heat-insulating coating of the invention comprises chiral compounds and nematic monomers of group b), especially chiral compounds of the formula 2:
and/or of the formula 5:
and nematic monomers of the formula 1:
of the formula 3:
or of the formula 4:
in the cured state, where n1 and n2 in the formulae 1 and 3 are independently 2, 4 or 6 and the monomers of the formula 1 or 3 are preferably employed as mixtures of compounds with n1/n2=2/4, 2/6, 4/2, 6/2, 4/4, 4/6, 6/4 or 6/6, and R in formula 4 is H, Cl or CH3.
The present invention additionally provides a process for producing a heat-insulating coating, which comprises applying to a transparent substrate at least one cholesteric IR-reflecting layer, curing it, applying, if desired, one or more further cholesteric IR-reflecting layers and, if desired, a medium which reverses the direction of rotation of the transmitted circularly polarized light, curing said layer(s) and so completing the heat-insulating coating.
The transparent substrate to which the IR-reflecting layer(s) is(are) applied can be, for example, a glazed unit, a window pane or a film which is to be bonded adhesively to a window pane for insulation purposes.
The cholesteric IR-reflecting layer can be applied to the substrate by customary techniques: for example, by means of techniques selected from air knife coating, bar coating, squeeze coating, impregnating, reverse roll coating, transfer roll coating, gravure coating, kiss coating, casting, spraying, spin coating or printing techniques, such as letterpress, flexographic, intaglio, offset or screen printing.
The IR-reflecting layer(s) can be applied in the form of low-gap or high-viscosity mixtures to the substrate, but preferably as low-viscosity mixtures. To this end the cholesteric mixtures can be applied to the substrate in undiluted or minimally diluted form at an elevated temperature or in highly diluted form at a low temperature.
The cholesteric mixtures and the formulations comprising absorption pigments can be diluted with any suitable diluent prior to their application to the substrate.
Examples of diluents which can be employed in the process of the invention for the compounds of groups a) or b) are linear or branched esters, especially acetic esters, cyclic ethers and esters, alcohols, lactones, aliphatic and aromatic hydrocarbons, such as toluene, xylene and cyclohexane, and also ketones, amides, N-alkylpyrrolidones, especially N-methylpyrrolidone, and, in particular, tetrahydrofuran (THF), dioxane and methyl ethyl ketone (MEK).
Examples of suitable diluents for the polymers of group c) are ethers and cyclic ethers such as tetrahydrofuran or dioxane, chlorinated hydrocarbons such as dichloromethane, 1,1,2,2-tetrachloroethane, 1-chloronaphthalene, chlorobenzene or 1,2-dichlorobenzene. These diluents are particularly suitable for polyesters and polycarbonates. Examples of suitable diluents for ellulose derivatives are ethers, such as dioxane, or ketones, such as acetone. Where copolyisocyanates are employed as polymers of group d) it is advisable to use polymerizable diluents as described in U.S. Pat. No. 5,847,068. Examples of such polymerizable diluents are
esters of xcex1,xcex2-unsaturated mono- or dicarboxylic acids, especially C3-C6 mono- or dicarboxylic acids, with C1-C12-alkanols, C2-C12-alkanediols or their C1-C6-alkyl ethers and phenyl ethers, examples being acrylates and methacrylates, hydroxyethyl or hydroxypropyl acrylate or methacrylate, and 2-ethoxyethyl acrylate or methacrylate;
vinyl C1-C12-alkyl ethers, such as vinyl ethyl, hexyl or octyl ether;
vinyl esters of C1-C12 carboxylic acids, such as vinyl acetate, propionate or laurate;
C3-C9 epoxides, such as 1,2-butylene oxide, styrene oxide;
N-vinylpyrrolidone, N-vinylcaprolactam, N-vinylformamide;
vinylaromatic compounds, such as styrene, xcex1-methylstyrene, chlorostyrene, and
compounds having two or more crosslinkable groups, such as diesters of diols (including polyethylene glycols) with acrylic or methacrylic acid or divinylbenzene.
Examples of preferred polymerizable diluents are 2-ethoxyethyl acrylate, diethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, diethylene glycol monomethyl ether acrylate, phenoxyethyl acrylate and tetraethylene glycol dimethacrylate. A particularly preferred polymerizable diluent is styrene.
The mixtures of groups a), b) or c) may also include polymerizable diluents in small amounts. Preferred polymerizable solvents which can be added to a), b) or c) are acrylates, especially acrylates of relatively high functionality such as bis-, tris- or tetraacrylates and, with particular preference, high-boiling oligoacrylates. The preferred amount added is approximately 5% by weight, based on the overall weight of the mixture.
For photochemical polymerization, the cholesteric mixture may include customary commercial photoinitiators. For curing by electron beams, such initiators are not required. Examples of suitable photoinitiators are isobutyl benzoin ether, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 1-hydroxycyclohexyl phenyl ketone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-furan-1-one, mixtures of benzophenone and 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, perfluorinated diphenyltitanocenes, 2-methyl-1-(4-Cmethylthiolphenyl)-2-(4-morpholinyl)-1-propanone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 4-(2-hydroxyethoxy)phenyl 2-hydroxy-2-propyl ketone, 2,2-diethoxyacetophenone, 4-benzoyl-4xe2x80x2-methyldiphenyl sulfide, ethyl 4-(dimethylamino)benzoate, mixtures of tip 2-isopropylthioxanthone and 4-isopropylthioxanthone, 2-(dimethylamino)ethyl benzoate, d,l-camphorquinone, ethyl-d,l-camphorquinone, mixtures of benzophenone and 4-methylbenzophenone, benzophenone, 4,4xe2x80x2-bisdimethylaminebenzophenone, (xcex75-cyclopentadienyl)(xcex76-isopropylphenyl)iron(II) hexafluorophosphate, triphenylsulfonium hexafluorophosphate or mixtures of triphenylsulfonium salts, and butanediol diacrylate, dipropylene glycol diacrylate, hexanediol diacrylate, 4-(1,1-dimethylethyl)cyclohexyl acrylate, trimethylolpropane triacrylate and tripropylene glycol diacrylate.
In order to adjust the viscosity and the leveling behavior it is possible for the cholesteric mixtures to be mixed with additional components.
For example, it is possible to employ polymeric binders and/or monomeric compounds which can be converted into a polymeric binder by polymerization. Examples of suitable such compounds are organic-solvent-soluble polyesters, cellulose esters, polyurethanes and silicones, including polyether- or polyester-modified silicones. It is particularly preferred to employ cellulose esters such as cellulose acetobutyrate.
The addition of small amounts of suitable leveling agents may also be advantageous. It is possible to employ from about 0.005 to 1% by weight, in particular from 0.01 to 0.5% by weight, based on the amount of cholesteric employed. Examples of suitable leveling agents are glycols, silicone oils and, in particular, acrylate polymers, such as the acrylate copolymers obtainable under the name Byk 361 or Byk 358 from Byk-Chemie and the modified, silicone-free acrylate polymers obtainable under the name Tego flow ZFS 460 from Tego.
The cholesteric mixture may also include stabilizers to counter the effects of UV and weather. Examples of suitable such additives are derivatives of 2,4-dihydroxybenzophenone, derivatives of 2-cyano-3,3-diphenyl acrylate, derivatives of 2,2xe2x80x2, 4,4xe2x80x2-tetrahydroxybenzophenone, derivatives of ortho-hydroxyphenylbenzotriazole, salicylic esters, ortho-hydroxyphenyl-s-triazines or sterically hindered amines. These substances can be employed alone or, preferably, as mixtures.
The IR-reflecting layer(s) applied can be cured thermally, photochemically or by a beam of electrons.
Curing must of course take place in the cholesteric phase and with retention of the cholesteric phase.
Where two or more layers are applied, they can in each case be applied, driedxe2x80x94if desiredxe2x80x94and cured individually. However, it is likewise possible to apply two or more, or all, of the layers to be applied in one application procedure, wet-on-wet, to the article that is to be coated, to carry out conjoint drying if desired and then to carry out conjoint curing. A prerequisite for the simultaneous application of the cholesteric layers, however, is that there is no interdiffusion between different layers having a different reflection behavior.
Casting techniques are particularly suitable for the simulotaneous application of cholesteric layers, especially knife or bar casting techniques, cast-film extrusion or stripper casting techniques, and the cascade casting process. These casting techniques are described, for example, in DE-A-19 504 930, EP-A-431 630, DE-A-3 733 031 and EP-A-452 959, which are expressly incorporated herein by reference.
The present invention additionally provides a multicomponent coating system comprising components which are capable of forming cholesteric layers having mutually different reflection maxima in the wavelength range  greater than 750 nm. By means of such a coating system of the invention, whose components can be employed, for example, as coating formulations, it is possible to provide any-desired substrate with a heat-insulating coating of the invention.
The heat-insulating coating of the invention is particularly suitable for producing insulated windows or heat-insulating transparent construction materials, or for insulating residential, office or industrial buildings against thermal radiation. In addition, the heat-insulating coating of the invention is also particularly suitable for use in the automotive sector, especially for producing heat-insulating laminated glass screens. Its use for these purposes is therefore also provided for by the present invention.
The Examples which follow illustrate the invention without limiting it to them.
Examples 1 to 3 used a nematic liquid-crystalline mixture of the formula 1 which is present up to 5xc2x0 C. in the smectic phase, up to 68xc2x0 C. in the nematic phase and above 68xc2x0 C. in the isotropic phase (S 5 N 68 I).
The chiral dopant employed in Examples 1 and 2 was the compound of the formula 2 and in Example 3 the compound of the formula 5.
Cellulose acetobutyrate in a concentration of 0.8% by weight based on the cholesteric mixture was added to the mixtures employed in Examples 1 to 3 in order to improve layering, and the overall mixture was dissolved in butyl acetate. 2,4,6-Trimethylbenzoyldiphenylphosphine oxide as photoinitiator was added in a concentration of 1.5% by weight, based on the cholesteric mixture. This mixture was applied with a doctor blade in a wet-film thickness of 30 xcexcm to a glass plate. In all three examples, a homogeneous transparent layer was formed in each case following the evaporation of the solvent. This layer was crosslinked photochemically using a UV light source.


The invention relates to thermoplastic compositions that contain reactive isocyanate groups and that are suitable for use as desiccants for packaging moisture-sensitive goods, especially for polyurethane hotmelt adhesives that are cross-linked upon exposure to moisture. The compositions are formed by the reaction of hydroxy- or amino-containing polyols, including sugars, with an excess of polyisocyanates, and admixing the resulting product with polyurethane catalysts.

1. Field of the Invention
This invention relates to the use of thermoplastic polymer compositions containing reactive isocyanate groups as a drying agent for protecting moisture-sensitive goods.
Various goods and products of everyday life have to be protected against moisture, more particularly moisture from the surrounding atmosphere. These include in particular highly reactive one-component moisture-curing adhesive systems such as, for example, one-component moisture-curing polyurethane adhesives, moisture-curing systems based on reactive silane groups and the like.
2. Description of the Related Art
A typical method of protecting such moisture-sensitive reactive adhesive/sealant systems comprises packing them in water-impermeable containers such as, for example, flanged metal cartridges, airtight drums or casks, optionally using inner packs of laminated films consisting of a layer of metal foil and one or more layers of plastic films. Packs such as these are described, for example, in DE-A-3605422, EP-A-413049 or in DE-U-9912012.
Moisture-reactive polyurethane hotmelts are particularly sensitive to moisture. It is known that moisture-sensitive polyurethane hotmelts are produced in such a way that they contain very few reactive isocyanate groups which react even with traces of moisture and form crosslinked infusible polymers. Accordingly, moisture-sensitive polyurethane hotmelts have to be packed and stored in the strict absence of moisture, as illustrated by the following example: in order completely to harden 1 kg of a polyurethane hotmelt with an isocyanate content of 1%, i.e. to react all the isocyanate groups, takes ca. 1 gram of water. Accordingly, a skin is formed on the surface of such a hotmelt even if only fractions of this amount of water pass to the surface of the product.
Consequently, where moisture-sensitive polyurethane hotmelts are packed in drums, casks, cartridges or laminated film bags, even traces of penetrating moisture are sufficient to render the entire contents of the container unusable through skin formation.
In order to achieve a shelf life of 9 months or longer for a packed polyurethane hotmelt, the imperviousness of the packs has to meet very stringent requirements, particularly in regard to the tightness of the seal used and the dimensional stability of the container. Since the tightness of the container can never be satisfactorily tested, even with 100% incoming goods control, it happens fairly frequently in the present state of the art that individual containers are only detected as leaky after they have been filled with the hotmelt. It is a serious disadvantage that the customer and user is also unable to detect such faulty packs because the crosslinked infusible skin is difficult to tell apart from the uncrosslinked fusible reactive hotmelt at room temperature. Although it is possible to melt the surface every time the container is changed in order to assess whether a skin has already formed, this is a labor-intensive and time-consuming step, especially since in industrial application very little time is generally available for changing containers. As a rule, the processor only notices skin formation in the container through a steep fall in the quantity of hotmelt delivered through the installation. Since the crosslinked skin can block the throughflow pipes, faulty bonding and expensive, time-consuming breaks in production are the outcome.
There has been no shortage of attempts to develop suitable packs for reactive polyurethane hotmelts where the skin formation and surface hardening mentioned above are avoided. Thus, DE-A-4404631 describes a process for the self-sealing of containers in which moisture-sensitive fusible materials, such as polyurethane hotmelts for example, are covered with an insert consisting of a heat-resistant plastic film impermeable to water vapor and a plastic disk of a thermoplastic material with a linear expansion coefficient of 6.10xe2x88x925/K. This cover enables the surface of such moisture-sensitive fusible materials to be self-sealed. In addition, in one particular embodiment of the process in question, a small bag filled with molecular sieve as a moisture adsorber is placed on the insert after the fusible material has been sealed and the container is then closed with a lid.
The use of molecular sieves, silica gels or sharply dried, hygroscopic inorganic salts with a tendency towards hydrate formation as a water collector or water adsorber has been repeatedly proposed in the prior art, cf. DE-A-19722789, US-A-5900226, JP-02760769 B2 or JP-07048546 A.
All these adsorbers are either used to dry the raw materials used or are incorporated in the pack as a drying agent. For the second of these two applications, however, the adsorbers in question perform their function to only a very limited extent. This is because the adsorption of water onto molecular sieves, silica gels or inorganic salts containing water of crystallization is reversible, i.e. the water initially adsorbed desorbs again and is then able to react irreversibly with the reactive groups, such as the isocyanate groups, of a polyurethane hotmelt adhesive in a crosslinking reaction. This water is thus irreversibly removed from the adsorption/desorption equilibrium and ultimately leads to optionally complete crosslinking of the packed material.
Accordingly, there is still a need to find improved ways of protecting moisture-sensitive goods.
The solution to this problem as provided by the invention is defined in the claims and consists essentially in the use of thermoplastic polymer compositions containing reactive isocyanate groups as a drying agent in the packaging of moisture-sensitive goods.
In a preferred embodiment, these thermoplastic polymers have a content of reactive NCO groups of 0.3 to 20% by weight and preferably 0.6 to 15% by weight, based on the composition as a whole.
Reactive polymers of the type in question may be obtained in known manner by reacting compounds or polymers containing OH or amino groups with an excess of polyisocyanates. These polyisocyanates should preferably have a high reactivity so that aromatic polyisocyanates are preferably used. The crude technical isomer and homolog mixture of diphenyl methane diisocyanate (MDI) is particularly suitable from the cost perspective. Suitable polyols are polyester polyols or polyether polyols solid at room temperature with a melting point below 150xc2x0 C. or fusible mixtures of polyester polyols, polyether polyols and sugars. Examples of sugars are mainly the monosaccharides or oligosaccharides such as, for example, glucose, galactose, mannose, fructose, arabinose, xylose, ribose or even cane sugar. In principle, other low molecular weight polyols or polyamines may also be at least partly used. It is important in this regard that the reaction product of polyisocyanate and polyalcohol is still fusible at temperatures below 180xc2x0 and preferably below 130xc2x0 so that it may readily be converted into the xe2x80x9csurface-richxe2x80x9d form. In order to achieve a high water adsorption capacity, the polyisocyanate is preferably used in a large stoichiometric excess. Chemically non-bound polyisocyanate is physically fixed in the solidifying matrix of the thermoplastic drying agent. After reacting off with water in the function of the moisture scavenger, the chemically non-bound polyisocyanate is chemically irreversibly bound to the drying agent, thus avoiding health hazards from unreacted monomeric isocyanate at the time of disposal of the thermoplastic polymer. Where polyisocyanates of relatively high functionality, such as crude MDI, or sugars are used, it can be useful to add monohydric C1-12 alcohols or corresponding secondary amines as chain terminators in order to prevent a high degree of crosslinking of the reaction mixture and hence the formation of a thermoset.
In order to obtain high reactivity of the drying agent to moisture, particularly preferred embodiments of the thermoplastic polymer drying agent compositions according to the invention have to be provided with a relatively large content of polyurethane catalysts.
Suitable catalysts are any of the various known polyurethane catalysts including, for example, tin(II) salts of carboxylic acids, such as tin(II) acetate, ethylhexoate and diethylhexoate, or dialkyltin(IV) carboxylates of which the carboxylic acids contain at least 2, preferably at least 10 and more particularly 14 to 32 carbon atoms. Dicarboxylic acids may also be used. The following are expressly mentioned as acids: adipic acid, maleic acid, fumaric acid, malonic acid, succinic acid, pimelic acid, terephthalic acid, phenylacetic acid, benzoic acid, acetic acid, propionic acid and in particular 2-ethylhexanoic, caprylic, capric, lauric, myristic, palmitic and stearic acid. Actual compounds are dibutyl and dioctyl tin diacetate, maleate, bis-(2-ethylhexoate), dilaurate, tributyl tin acetate, bis-(xcex2-methoxycarbonylethyl)-tin dilaurate and bis-(xcex2-acetylethyl)-tin dilaurate.
Tin oxides and sulfides and thiolates may also be used. Actual compounds are bis-(tributyltin)-oxide, bis-(trioctyltin)-oxide, dibutyl and dioctyl tin bis-(2-ethylhexylthiolate), dibutyl and dioctyl tin didoceyl thiolate, bis-(xcex2-methoxycarbonylethyl)-tin didodecyl thiolate, bis-(xcex2-acetylethyl)-tin-bis-(2-ethylhexylthiolate), dibutyl and dioctyl tin didoceyl thiolate, butyl and octyl tin tris-(thioglycolic acid-2-ethylhexoate), dibutyl and dioctyl tin bis-(thioglycolic acid-2-ethylhexoate), tributyl and trioctyl tin-(thioglycolic acid-2-ethyl hexoate) and butyl and octyl tin tris-(thioethyleneglycol-2-ethylhexoate), dibutyl and dioctyl tin bis-(thioethylenegeglycol-2-ethylhexoate), tributyl and trioctyl tin-(thioethyleneglycol-2-ethylhexoate) with the general formula Rn+1Sn(SCH2CH2OCOC8H17)3xe2x88x92n, where R is a C4xe2x88x928 alkyl group, bis-(xcex2-methoxycarbonylethyl)-tin-bis-(thioethyleneglycol-2-ethylhexoate), bis-(xcex2-methoxycarbonylethyl)-tin-bis-(thioglycoli acid-2-ethylhexoate), bis-(xcex2-acetylethyl)-tin-bis-(thioethyleneglycol-2-ethylhexoate) and bis-(xcex2-acetylethyl)-tin-bis-(thioglycolic acid-2-ethylhexoate).
Other suitable catalysts are aliphatic tertiary amines, more particularly with a cyclic structure. Among the tertiary amines, those which additionally contain isocyanate-reactive groups, more particularly hydroxyl and/or amino groups, are also suitable. Specific examples of such tertiary amines are dimethyl monoethanolamine, diethyl monoethanolamine, methyl ethyl monoethanolamine, triethanolamine, trimethanolamine, tripropanolamine, tributanolamine, trihexanolamine, tripentanolamine, tricyclohexanolamine, diethanol methyl amine, diethanol ethyl amine, diethanol propyl amine, diethanol butyl amine, diethanol pentyl amine, diethanol hexyl amine, diethanol cyclohexyl amine, diethanol phenyl amine and ethoxylation and propoxylation products thereof, diazabicyclooctane (Dabco), triethyl amine, dimethyl benzyl amine (Desmorapid DB, BAYER AG), bis-dimethylaminoethyl ether (Catalyst A 1, UCC), tetramethyl guanidine, bis-dimethylaminomethylphenol, 2,2xe2x80x2-dimorpholinodiethyl ether (DMDEE), 2-(2-dimethylaminoethoxy)-ethanol, 2-dimethylaminoethyl-3-dimethylaminopropyl ether, bis-(2-dimethylaminoethyl)-ether, N.N-dimethyl piperazine, N-(2-hydroxyethoxyethyl)-2-azanorbornane, Texacat DP-914 (Texaco Chemical), N,N,N,N-tetramethylbutane-1,3-diamine, N,N,N,N-tetramethylpropane-1,3-diamine, N,N,N,N-tetramethylhexane-1,6-diamine, 1-methylimidazole, 2-methyl-1-vinyl imidazole, 1-allyl imidazole, 1-phenylimidazole, 1,2,4,5-tetramethylimidazole, 1-(3-aminopropyl)-imidazole, pyrimidazole, 4-dimethylaminopyridine, 4-pyrrolidinopyridine, 4-morpholinopyridine, 4-methyl pyridine and N-dodecyl-2-methyl imidazole.
Particularly preferred catalysts are those which favor the isocyanate/water reaction over all other reactions of the NCO group. Such catalysts are in particular the cyclic and tertiary amino compounds, optionally in conjunction with tin compounds. The catalysts are used in a concentration of 0.05 to 15% by weight and more particularly 0.5 to 10% by weight, based on the sum of hydroxyl compounds and polyisocyanate.
It is important that the starting components and the production process for the drying agent according to the invention are selected so that, after reaction of the isocyanate groups with the hydroxyl groups or amino groups, the composition is still thermoplastic in character so that it can readily be made up by shaping in such a way that a large surface is available for the chemical adsorption of water. In a particularly preferred embodiment, the composition is made up into fine granules, thin flakes, a thin extruded film or an open-cell foam. Another embodiment of the drying agent according to the invention can be produced by spinning/spraying so that a kind of nonwoven material similar to a textile fleece or knitted fabric is formed.
The moisture-reactive thermoplastic drying agent thus produced is then placed in a moisture-proof container and arranged outside the moisture-sensitive product to be protected. In this moisture-proof container, the drying agent according to the invention acts like a xe2x80x9csacrificial hotmeltxe2x80x9d, i.e. the isocyanate groups bound therein are sacrificed to absorb the moisture present in the surrounding atmosphere so that the moisture-sensitive product is protected against reaction with moisture. In a cask, drum or cartridge, this may be the air gap above the product to be protected, for example a moisture-curing hotmelt adhesive in the gap between the surface of the adhesive and the lid of the container. If the moisture-sensitive product to be protected, for example a preformed hotmelt adhesive, is directly welded or sealed in a bag of laminated film, the thermoplastic drying agent made up as described above may also be introduced into and welded or sealed in the remaining air gap of the pack.


The invention concerns a method for creating an individual movement and load profile, where the absolute altitude is measured continuously, the movement and/or acceleration is recorded in all three directions in space, and the physiological load upon the test subject is calculated from the path and altitude profile and the cardial and pulmonary measured variables.

1. Technical Field of the Invention
The invention concerns a method for creating an individual movement and load profile using, for example, a portable ergospirometer for recording cardial and pulmonary measured variables for humans or animals and a portable ergospirometer.
2. Description of the Prior Art
Among other areas, movement and load profiles are necessary in occupational medicine, in training theory or for testing new materials for garments, e.g. for new footwear. Thereby, the movement of a test subject is usually recorded in the horizontal direction to record individual exertion or also to determine the scope of training. Effectively the load also depends on movement in the vertical direction as well as on the oxygen content of the ambient air, which changes with the absolute altitude.
Using ergospirometry, the tidal volume, the respiratory rate and the oxygen consumption of humans and animals can be measured under exertion. This allows the reaction of the cardiovascular system to exterior, generally defined, specific loads to be determined. Among other things, it is known to subject test persons on a bicycle ergometer to a certain physical exertion, for example, the test subject has to produce a continuous performance of 100 W. Using the ergospirometer, there is continuous measurement of the tidal volume, the composition of the expired air and various cardial parameters, such as the pulse. These allow the effective physiological loading of the test subject to be calculated, i.e. the effective biological performance the test subject must exert to produce 100 watts on the bicycle ergometer, whereby from experience a person has an efficiency ratio of approximately 30%, i.e. in the above mentioned example the person has to produce about 330 W. In a similar way, the test persons are subject to a defined load on a treadmill ergometer. Furthermore, portable ergospirometers are known, which are used especially for rehabilitation measures after cardiovascular diseases or in occupational or sports medicine, where the test subject carries a portable device, usually on his back, to record all cardial and pulmonary measured variables and where the physiological reaction to various loads, for example, different labour processes, can be recorded.
As concerns the methods known to date for creating egospirometric load profiles, it is to be considered disadvantageous that with stationary bicycle or treadmill ergometers respectively only a specific load can be exercised upon the test subject. To simulate realistic everyday situations and the physiological reactions of the test subject to such situations, these stationary devices are unsuitable. Although, portable ergospirometers can fulfil the task of a continuous measurement of the variables of interest under realistic conditions, for example, in the workplace or for a sports person during training, they are not able to record the effective, objective, external loads that a test person is subject to because they solely always only measure the physiological reaction of the test subject to such loads. As is known to a person skilled in the art, the reaction of the test subject, however, always depends on individual circumstances, i.e. when an objective, similar external load is applied, different test subjects show different physiological reactions.
Starting from the state-of-the-art, the invention has the object of providing a method for creating a movement and a load profile, and in a further development, an individual ergospirometric load profile, and a portable ergospirometer for executing the method. Thereby not only the physiological reactions of the test subject but also the effective physical loads can be measured, and the load can be recorded under the most varied environmental conditions and realistic everyday situations.
In accordance with the invention, this task is solved therein that the absolute altitude is continuously measured and the movement and/or acceleration is recorded in all three directions in space.
The central idea of the invention provides that to create a movement and a load profile, the movement and acceleration in all three directions must be recorded to receive complete information about the movement profile of the test subject. Thus it is possible that, for example, in occupational medicine, the movement sequences of the worker are recorded, or in training theory, the actual scope of the training of an athlete, as well as the durability of a new garment can be measured, if the absolute movement can be recorded, i.e. the actual distance a test subject has travelled using new footwear. Devices by means of which the acceleration and/or movement can be recorded, and which determine the absolute altitude, can be embodied in diverse ways, or as described further below.
Particularly advantageous is the method for creating an ergospirometric load profile by means of which not only the cardial and pulmonary measured variables of the test subject are recorded by a portable ergospirometer known per se, but also the movement of the test subject in space. To that end, the absolute altitude and the horizontal movement and acceleration are continuously recorded. Using these measured variables, a path and altitude profile can be created, which in conjunction with the cardial and pulmonary measured variables, yields the actual load upon the test subject. It is known to a person skilled in the art that, for example, going uphill at a certain speed represents a substantially greater physical exertion than walking on the level at the same speed. Likewise, the absolute altitude is an important influencing variable for the effective load, because the oxygen content of the air decreases as the altitude increases. The conversion of the measured values into a path and altitude profile and deriving the effective physical exertion of the test subject is possible for a person skilled in the art. For example, when going uphill additional lifting force must be used in contrast to walking on the level. Walking at different speeds, which can also be determined from the path profile, is expressed in the different reactions of the test subjects.
The advantage of the invention consists therein that with these methods not only the physiological reactions and the oxygen consumption of the test subject but also the effective movement through space is measured, which is of decisive importance for the magnitude of the actual load. Thus, realistic, measurement results are achieved which correspond to the natural conditions.
Portable ergospirometers to execute the method are the subject matter of the subclaims.
To execute the method a portable ergospirometer is necessary as known per se in the state of the art, i.e. cardial, pulmonary and motional physiological measured variables are recorded for humans or animals, and the ergospirometer has devices to record, store, evaluate or transmit such data. The energy supply is usually provided by batteries. To execute the inventive method, furthermore, devices are provided by means of which the absolute altitude of the test subject or the ergospirometer can be determined, as well as sensors to record the movement and/or acceleration in all three directions in space. These devices and sensors can be implemented in diverse ways, as explained below. Thereby, it is irrelevant in accordance with the invention whether the measured values are processed directly in the ergospirometer itself or whether they are solely stored and read out later. The person skilled in the art can create a path and altitude profile from the measured values and determine the respective current speed of the test subject, i.e. map the actual movement of the test subject in space. Furthermore, it is possible for the person skilled in the art, using this profile and the usual measured values, to convert the actual physical load into the biological exertion of the test subject, especially when climbing and descending.
To record the absolute altitude, it is proposed to use a barometer. They are well known in the state of the art and continuous recording of the absolute altitude, adjusted by the weather-related changing air pressure, is possible without problems. An especially simple embodiment consists therein to use an electronic barometer, in particular a piezoelectric one. It enables the direct further processing of the electric measured signals.
To record movement in the horizontal direction, acceleration detectors or sensors on a mechanical or electronic basis can be are used, which are well known in the state of the art. Here, too, continuous recording of the measured variables and their further processing is possible in a simple way.
The three-dimensional movement through space can be recorded especially simply using a GPS device. Especially when a differential GPS device is used, deviations of less than 1 m from the actual position can be achieved and guarantee sufficient measuring accuracy when recording movement through space. If the GPS device has an electronic interface, it is possible to read out the data and process it to obtain a path profile in an especially simple way.
Furthermore, it is proposed to provide the ergospirometer with an infrared interface to transmit all measured variables, and the data determined therefrom, to a further evaluation or storage unit. Corresponding devices are known to the person skilled in the art. Thus, the portable ergospirometer can be used in mobile applications as well locally as a stationary unit.

Method for creating an individual movement and load profile and a portable ergospirometer