Use of crystalline, crosslinked synthetic resins as a storage material in latent heat stores

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eutectic salt mixtures, if only because the number of

USE OF CRYSTALLINE, CROSSLINKED eutectics is limited. Furthermore, some eutectic melt SYNTHETIC RESINSAS A STORAGE MATERIAL temperatures can only be obtained by choosing unusual IN LATENT HEAT STORES expensive salts, which a priori precludes the practical realisation of such eutectics.

This is a continuation of application Ser. No. 680,263, It is the object of the invention to provide a storage filed on Apr. 26, 1976, now abandoned. material, for latent heat stores based on heat of fusion It is known to utilise the phenomenon of absorption and heat of crystallisation, which does not suffer from and re-release of latent heat during melting or crystalli the known disadvantages of salts and salt solutions. The sation of bodies for the storage of heat energy. Installa 10 melting point or melting range must be controllably tions of this type are classified amongst the so-called adjustable. Any faults due to demixing phenomena or "latent heat accumulators'. This method has two im corrosion problems must be excluded. Furthermore, the portant advantages over the storage of heat by simple cost price of such a storage material must lie within heating of a solid body or of a liquid, without change in reasonable limits.

the state of aggregation (in so-called "capacity accumu 15 The invention relates to the use of crystalline, cross lators'). Firstly, it is possible to choose, as the storage material, a body having a relatively low melting point, linked synthetic resins as a storage material in latent heat stores. By a crystalline plastic, synthetic resin and which largely eliminates heat losses. Secondly, this epoxide resin there is to be understood, in the present method gives a substantially greater heat storage capac document and in accordance with the present inven ity, that is to say, per unit weight of the storage material, 20 tion, a product which is usually partially crystalline. a much larger amount of heat can be accommodated The synthetic resins used according to the invention within the range of temperatures usable in practice. have either only one crystallite melting point or several, For latent heat accumulators, in which the heat of preferably two, crystallite melting points.

fusion is stored, it is primarily salt solutions, salt mix In comparison to salts and organic low-molecular tures and crystalline organic low-molecular substances 25 crystals, the synthetic resins used according to the in which are used as the storage medium. vention exhibit the peculiarity (and the advantage) that At the present time, the development of latent heat when they are used no change in the state of aggrega accumulators has not yet progressed very far. This poor tion state of development is astonishing and also regrettable versa)(that is to say from "solid' to "liquid' and vice occurs. It is true that the crystallites contained in in as much as at the present time, especially because of 30 the synthetic resins melt in the region of the crystallite energy crises and because of marked trends to pass melting point. However, adverse judgment on the generation of energy by resins remains preserved.theAtsolid the state of the synthetic same time, in most atomic fission, the call for installations for utilisation of cases the synthetic resin turns transparent, and there solar energy, and similar substitute solutions, is every may be a transition to the rubbery-elastic state, with where very pronounced. 35 simultaneous absorption of the latent heat of fusion.

If the state of development of latent heat accumula According to the invention, it is in particular epoxide tors is analysed in more detail, it is found that, in prac resins which are used. A particularly preferred form of tice, the greatest technical shortcomings are due to the the invention storage media of the state of the art, especially the salt thane resins oris polyester the use of epoxide resins or polyure resins or mixtures of these solutions and salt mixtures. Inter alia, the following synthetic resins which contain, as crystallite-forming disadvantages may be singled out as being serious. blocks, radicals of long-chain dicarboxylic acids or When using salt solutions and salt melts, as well as low-molecular weight organic crystals, there are al dialcohols of the formula I ways severe corrosion problems. For this reason, it is X-A-X? (I) predominantly corrosion-resistant metal containers 45 which are used to contain the salts, but these containers are heavy and conduct heat well. From the point of in which XI and X2 each represent a -CO.O- group or a -O-group and in which A denotes a substan view of heat storage, both properties are disadvanta tially linear radical, in which polymethylene chains geous, quite apart from the fact that such containers alternate regularly with ether oxygen atoms or carbox make the total installations expensive. Furthermore, 50 ylic acid ester groups, and the quotient Z/Q, wherein Z fractures and leaks of the containers and pipelines must is the number of CH2 groups present in the recurring always be expected, and this results in undesirable exu structural element of the radical A and Q is the number dation of the solutions or melts. of oxygen bridges present in the recurring structural The literature states that practically any desired melt element of the radical A, must be at least 3 and prefera ing point can be obtained by appropriate choice of the 55 at least 5 or 6 and wherein, furthermore, the total salt or by mixing different salts. In reality, however, the bly number of the carbon atoms present in the radical A in situation is not quite so favourable, because if a salt alternating carbon chains is at least 30. mixture which does not correspond to an eutectic com Such special epoxide resins include, in particular, position is chosen, demixing phenomena always occur crystalline, crosslinked epoxide resins (J), which are when the melt solidifies. Only purely eutectic mixtures manufactured by reaction of epoxide compounds, con crystallise in a constant composition. They are, there taining two or more epoxide groups, fore, for practical purposes the only storage material (a) with polyester-polycarboxylic acids D, which used at the present time. However, eutectic melts have essentially contain segments of the formula II a great tendency to supercooling and must therefore be seeded. This, in turn, however, has the consequence 65 -O-(CH2)-O.CO-(CH2)n-CO)- (II) that here again demixing phenomena gradually manifest themselves. It is not possible to realise, by continuous in which n and m are identical or different and denote 2 progression, any desired salt temperature by choosing or a higher number than 2, and to which the condition 3 n-i-m-6 to 30 applies, and in which p denotes a number that in such cases the crystallite melting point manifests from 2 to 40, which, however, is sufficiently large that itself as a two-stage melting point. the segment contains at least 30 -CH2-groups, and Preferably, the procedure followed in the manufac (b) if appropriate, with curing agents C, and if appro ture of the epoxide resins (J) and (K) is such that 0.7 to priate in the presence of accelerators, in a ratio such that 1.2, especially 0.9 to 1.1, equivalents of polyester 0.5 to 1.2 equivalents of polyester-polycarboxylic acid polycarboxylic acid are present per equivalent of epox are present per equivalent of epoxide compound and up ide compound.

to 0.6 equivalent of curing agent C are present per The polyester-polycarboxylic acids D and D used in equivalent of epoxide compound, with the proviso that, O the reaction for the manufacture of the epoxide resins in the cases in which only difunctional epoxide com (J) and (K) can for practical purposes be manufactured pounds and difunctional polyester-polycarboxylic acids by the same basic process, by esterification of corre D are employed, the epoxide groups must be present in sponding aliphatic dialcohols and aliphatic dicarboxylic excess and the reaction with a curing agent C is essen acids these or by esterification between suitable derivatives of alcohols and dicarboxylic acids, such as, for exam tial.

These epoxide resins (J) have only one crystallite 5 ple, the anhydrides, acid chlorides and the like. The melting point. dicarboxylic acids must be present in excess. Such special epoxide resins also include crystalline, Where minor amounts of aliphatic polyalcohols with crosslinked epoxide resins (K) which are manufactured at least 3 OH groups, especially glycerol, are also used, by reaction of epoxide compounds, containing two or 20 branched, that is to say at least 3-functional, polyester more epoxide groups, polycarboxylic acids D and E are obtained. Branched (a) with polyester-polycarboxylic acids D which polyester-polycarboxylic acids D and E which are ob-, essentially contain segments of the formula II tained if small amounts of polycarboxylic acids, or their anhydrides, with at least 3 carboxyl groups (such as, for -O-(CH2)n-O.CO-(CH2)n-CO- (II) 25 example, trimellitic acid) are also present during the manufacture of the polyester-polycarboxylic acids, are in which n and mare identical or different and denote 2 equally suitable for the manufacture of the epoxid or a higher number than 2, and to which the condition resins (J) and (K).

n-i-m-6 to 30 applies, and in which p denotes a number However, it is also possible to employ branched from 2 to 40, which, however, is sufficiently large that 30 polyester-polycarboxylic acids D and E, which are the segment contains at least 30 -CH2-groups, and obtainable by esterification of the terminal OH groups (b) with polyester-polycarboxylic acids E which es of long-chain polyester-polyols, especially of polyester sentially contain segments of the formula III diols, with polycarboxylic acids which contain at least 3 -CO.OH groups, such as, for example, trimellitic acid, -O-(CH2)-O.CO-(CH2)-CO)- (III) 35 or with corresponding anhydrides. in which s and rare identical or different and denote 2

The basic rules for the manufacture of the polyester polycarboxylic acids D and E used as starting materials or a higher number than 2, and to which the condition for the epoxide resins (J) and (K) in other respects en s+r-2sn+m applies, and in which q represents a tirely correspond to those which have to be observed number from 2 to 40, which, however, is sufficiently for the manufacture of the "long-chain dicarboxylic large that the segment contains at least 30 -CH2 acids' employed according to British Pat. No. groups, and 1,164,584, and which are described in detail in this Brit (c) if appropriate, with curing agents C, and, if appro ish patent. Further data on the basic principles of the priate, in the presence of accelerators, in a ratio such manufacture of such long-chain, aliphatic polyester that 0.5 to 1.2 equivalents of polyester-polycarboxylic 45 polycarboxylic acids are also to be found in a publica acid are present per equivalent of epoxide compound, tion by Hans Batzer et al. in "Die Angewandte Mak that 1/10 to 9/10 of these 0.5 to 1.2 equivalents are romolekulare Chemie” 1973, page 349-412. attributable to the polyester-polycarboxylic acid D and Examples of suitable polyester-polycarboxylic acids the remaining 9/10 to 1/10 to the polyester-polycar D are those based on the following polyalcohols and boxylic acid E, and that up to 0.6 equivalent of curing 50 polycarboxylic acids:

agent C is present per equivalent of epoxide compound, 11 mols of adipic acid-10 mols of hexanediol with the proviso that in the cases in which only difunc 11 mols of sebacic acid-10 mols of hexanediol tional epoxide compounds and difunctional polyester 5 mols of decanedicarboxylic acid-4 mols of polycarboxylic acids D and E are employed, the epox dodecanediol ide groups must be present in excess and the reaction 55 11 mols of dodecanedicarboxylic acid-10 mols of bu with a curing agent C is essential. tanediol

Preferably, the condition n--ms-8 to 24 applies in th 16 mols of adipic acid-15 mols of hexanediol formula II for the polyester-polycarboxylic acids. 11 mols of dodecanedicarboxylic acid-10 mols of hex The epoxide resins (K) are distinguished by a feature anediol which was previously not known for such synthetic 11 mols of dodecanedicarboxylic acid-10 mols of pro resins. This is that they exhibit two pronounced crystal pane-1,3-diol lite melting points Tm and Tm2. Tm is in the range 11 mols of dodecanedicarboxylic acid-10 mols of do from 20' to 70° C., preferably 25 to 60° C., and Tm2 is decane-1,12-diol.

in the range from 50' to 120° C., preferably 50 to 100' 5 mols of dodecanedicarboxylic acid-4 mols of dodec C. The crystallite-forming elements for Tm and Tm2 65 ane-1,12-diol are the polyester-polycarboxylic acids D and E em 11 mols of sebacic acid-10 mols of butanediol ployed in the manufacturing process. Sometimes, the ll mols of sebacic acid-0 mols of dodecanediol particular crystallite melting point is split. This means 5 mols of sebacic acid-4 mols of dodecanediol

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Examples of suitable polyester-polycarboxylic acids and at the same time a polycarboxylic acid anhydride is E are those based on the following polyalcohols and added.

polycarboxylic acids: In the multi-stage method, an adduct containing ep 11 mols of sebacic acid-10 mols of hexanediol oxide groups is initially manufactured, in a first stage, 11 mols of adipic acid-10 mols of hexanediol 5 from the epoxide compounds and the polyester 11 mols of succinic acid-10 mols of butanediol polycarboxylic acids, preferably using 0.5 to 1 equiva 17 mols of succinic acid-14 mols of butanediol lent of polyester-polycarboxylic acid per 2 equivalents 21 mols of succinic acid-20 mols of butanediol of epoxide compounds. In a second reaction stage, the 22 mols of succinic acid-21 mols of butanediol crosslinking is then carried out, by reaction of the ad Glycerol-succinic acid-butanediol (1:24:21) O ducts with the remainder of the polyester-polycarboxy Trimethylolpropane-succinic acid-butanediol (1:30:27) lic acids. It is also possible to proceed by carrying out Glycerol-succinic acid-butanediol (1:17:14) the crosslinking in the second stage in the presence of Glycerol-succinic acid-butanediol (1:30:27) customary curing agents. It is also possible additionally 31 mols of succinic acid-30 mols of butanediol to introduce yet further monomeric epoxide com 16 mois of adipic acid-15 mols of hexanediol 15 pounds and correspondingly larger amounts of curing 11 mols of sebacic acid-10 mols of butanediol agents.

11 mols of dodecanedicarboxylic acid-10 mols of pro As customary curing agents for epoxide resins it is panediol possible to employ all the substances which are de 7 mols of dodecanedicarboxylic acid-6 mols of pro scribed in the numerous publications and patents relat panediol 20 ing to epoxide resins. Inter alia, the following sub 7 mols of dodecanedicarboxylic acid-6 mols of butane stances may be listed here: compounds with amino diol groups, polyalcohols, polycarboxylic acids and their 5 mols of sebacic acid-4 mols of hexanediol. anhydrides, acid amides, polyesters, phenol-formalde As epoxide compounds containing two or more epox hyde condensates and amino-resin precondensates. Ter ide groups it is possible to employ practically all the 25 tiary amines and imidazoles may be mentioned as exam polyepoxy compounds known to those skilled in the art, ples of suitable accelerators.

from publications and patent specifications. In princi The reaction in which the epoxide resins (J) and (K) ple, one or more different epoxide compounds can be are manufactured is preferably carried out in the melt. reacted. Triglycidyl isocyanurate and triglycidyl com For this, preferably temperatures of between 50 and pounds, which contain one or more hydantoin groups 30 200° C. and reaction times of more than 1 hour and up and/or dihydrouracil groups, especially epoxide com to about 20 hours are required. In principle, the reaction pounds of the formula IV according to the invention can also be carried out in

H3 to O CH3 (IV)

solution.

are particularly suitable. Before or during this reaction, a blowing agent for In principle, the reaction for the manufacture of the the manufacture of foams can also be added. epoxide resins (J) and (K) can be carried out either in 1 50 The crystalline, crosslinked plastic products (J) and stage or in several stages. If the epoxide compounds (K) are as a rule manufactured with simultaneous shap used have at least 3 epoxide groups, and polyester ing to give castings, foamed articles, pressings, lacquer dicarboxylic acids D, or D and E, are employed, it is films, laminates, adhesive bonds, granules and the like. possible, for example, to carry out the reaction in 1 Of course, other customary additives, such as fillers, stage, that is to say to start from a reaction mixture 55 reinforcing agents, mould release agents, agents to pro which contains all the reactants simultaneously. It is tect against aging, flameproofing substances, dyestuffs also possible to proceed in exactly the same way (that is or pigments, can be added to the moulding composi to say in 1 stage) if, instead of the dicarboxylic acids, tions.

polyester-polycarboxylic acids D, or D and E, which Suitable fillers or reinforcing agents are fibrous or each have at least 3 carboxyl groups are employed. In 60 pulverulent inorganic or organic substances. Quartz the converse case, that is to say when using polyester powder, aluminium oxide trihydrate, mica, aluminium polycarboxylic acids containing at least 3 carboxyl powder, iron oxide, ground dolomite, chalk powder, groups, and using diepoxy compounds, working in 1 gypsum, slate powder, unburnt kaolin (bolus), burnt stage is again possible and is the normal method of kaolin, glass fibres, boron fibres and asbestos fibres may reaction for such cases. 65 be mentioned. A content of materials, in the form of If only diepoxy compounds and only polyester-dicar fibres and powders, which assist the heat conductivity boxylic acids are employed, it is possible to work in one has also proved advantageous. Examples of such mate stage only if an excess of epoxide compounds is used rials are metals (for example aluminium powder), car 5 bon, such as carbon black and graphite in powder form, (c) if appropriate, with curing agents C, and, if appro and carbon fibres, , priate, in the presence of accelerators, in a ratio such For the purpose of optimum and accelerated devel that 0.5 to 1.2 equivalents of polyesterpolycarboxylic opment of the crystal structure of the polymers it is also acid are present per equivalent of epoxide compound, advisable to add nucleating agents, such as phthalocya that 5/10 to 9/10 of these 0.5 to 1.2 equivalents are nines, carbon black, a-naphthoic acid or the like. attributable to the polyester-polycarboxylic acid A and When using the crystalline, crosslinked epoxide resins the remaining 5/10 to 1/10 to the polyester-polycar (K) as a storage material in latent heat accumulators it is boxylic acid B, and that up to 0.6 equivalent of curing possible either to utilise the enthalpy of melting of only agent C is present per equivalent of epoxide compound, one of the two crystallites, or of both. Preferably, how O with the proviso that, in the cases in which only difunc ever, only the enthalpy of melting of the crystallite type tional epoxide compounds and difunctional polyester which melts at the lower temperatures (Tm) is utilised. polycarboxylic acids A and B are employed, the epox This utilises the following valuable property of the ide groups must be present in excess and the reaction present epoxide resins (K): in fact, these resins exhibit with a curing agent C is essential. excellent toughness and flexibility which, in contrast to 15 Preferably, the condition n--ms- 6 to 24 applies to previously known epoxide resins, are also retained the formula V.

above Tm). This advantageous behaviour can be im For the manufacture of these epoxide resins (L), the proved yet further by using, in the process of manufac manufacture of the polyester-polycarboxylic acids used ture, those polyester-polycarboxylic acids E which as starting materials, the reaction conditions for the result in a particularly high Tm2. In this way, controlled 20 manufacture of the epoxide resins (L) and the possibli variation of toughness and flexibility can be achieved. ties of using a one-step procedure and a multi-step pro According to the invention, it is also possible to use cedure, virtually the same as has been stated above, crystalline, crosslinked epoxide resins with more than 2 under the description of the epoxide resins (J) and (K), crystallite melting points as a storage material for latent applies. The same epoxide compounds, curing agents heat stores. Such products can be manufactured by a 25 and accelerators can be employed. An admixture of process which is analogous to the manufacture of the additives customary in such mixtures, especially of fill epoxide resins (K). However, the difference from the ers, is also possible. Foams can be manufactured by latter process is that the reaction takes place in the adding blowing agents.

presence of at least one further aliphatic polyester 30 The difference between the manufacture of the epox polycarboxylic acid, which differs from the polyester ide resins (L) and the manufacture of the epoxide resins polycarboxylic acids D and E and results in the devel (K) is that in the two processes different polyester opment of at least one further (third) crystallite melting polycarboxylic acids are employed. point, Examples of suitable polyester-polycarboxylic acids The abovementioned special epoxide resins, used A are those based on the following polyalcohols and preferentially in accordance with the invention, further 35 polycarboxylic acids:

more include crystalline, crosslinked, elastomeric epox 16 mols of adipic acid-15 mols of hexane-1,6-diol ide resins (L) which are manufactured by reaction of 21 mols of succinic acid-20 mols of butane-1,4-diol epoxide compounds, containing two or more epoxide 11 mols of sebacic acid-10 mols of hexane-1,6-diol groups, (a) with polyester-polycarboxylic acids A which es 40 Glycerol-succinic acid-butanediol (1:24:21) 11 mols of succinic acid-10 mols of butanediol sentially contain segments of the formula V 11 mols of dodecanedicarboxylic acid-10 mols of hex anediol -(O-(CH2)n-O.CO-(CH2)n-CO- (V) 11 mols of dodecanedicarboxylic acid-10 mols of bu in which n and m are identical or different and denote 2 45 tanediol or a higher number than 2, and to which the condition 11 mols of dodecanedicarboxylic acid-10 mols of pro n-m = 6 to 30 applies, and in which p is a number from pane-1,3-diol 2 to 40 which, however, is sufficiently large that the 7 mols of dodecanedicarboxylic acid-6 mols of hex segment contains at least 30-CH2-groups, and anediol (b) with polyester-polycarboxylic acids B which es 50 7 dodecanediol mols of dodecanedicarboxylic acid-6 mols of sentially contain segments of the formula VI 7 mols of sebacic acid-6 mols of dodecanediol -O-R-O.CO-R-CO)- (VI) 11 mols of sebacic acid-6 mols of dodecanediol in which R1 and R2 are identical or different and denote 55 (1:30:27) an alkylene radical with at least 2 C atoms in the chain 11 mols of dodecanedicarboxylic acid-10 mols of eth and in which, per O bridge, an average of at least 3.5 ylene glycol and at most 30 C atoms, without taking into account the 5 mols of decanedicarboxylic acid-4 mols of C atoms of the -CO.O- radicals, are present in the dodecanediol chain, and wherein the radicals R1 and R2 together 60 11 mols of decanedicarboxylic acid-10 mols of hexane contain at least one alkyl group or cycloalkyl group or diol one aryl group as a substituent for one H atom or one Examples of suitable polyester-polycarboxylic acids ring-forming optionally substituted alkylene group as a B are those based on the following polyalcohols and substituent for two H atoms of a chain, and in which q polycarboxylic acids:

denotes a number from 2 to 40, which however is suffi 65 11 mols of sebacic acid-10 mols of neopentylglycol ciently large that the segment contains at least 30 C 8 mols of adipic acid-7 mols of neopentylglycol atoms, without taking into account the C atoms of the 13 mols of adipic acid-12 mols of neopentylglycol -CO.O- radicals, in the chain, and 8 mols of adipic acid-7 mols of trimethylhexanediol

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8 mols of trimethyladipic acid-7 mols of neopentyl ally unhampered in one direction, but exhibit strong glycol heat insulation in the opposite direction. In general, 14 mols of adipic acid-13 mols of neopentylglycol such installations advantageously utilise not only the 4 mols of dimerised fatty acid-3-mols of diethylene enthalpy of melting of the actual storage material but in glycol addition also the enthalpy of vaporisation of a liquid 4 mols of dimerised fatty acid-3 mols of hexanediol contained therein. Further details of such complicated 3 mols of dimerised fatty acid-2 mols of hexanediol heat recifiers are described in the Journal of the World Glycerol-adipic acid-butanediol-neopentylglycol Wild-Life Fund Foundation (Switzerland) “PANDA', (1:9:3:3) No. 1, 8th year of publication, February 1975, on pages Trimethylhexanediol-adipic acid-hexanedi O 38 to 45.

ol-neopentylglycol (1:8:2:3) By means of the use according to the invention, the 14 mols of succinic acid-13 mols of neopentylglycol heat rectifying installations can be simplified to an ex 4 mols of hexahydrophthalic anhydride-3 mols of ceptional degree. The essential element is in general a neopentylglycol

The abovementioned special epoxide resins which 15 or wall panel ofinthe self-supporting, most cases dark-coloured, roof panel synthetic resin used according to according to the invention are used preferentially also the include those which are manufactured according to the the surface of the panelplate invention. A glass is in general located above which faces the solar radiation, processes claimed in British Pat. Nos. 1,164,584 and and at a small distance therefrom. The outward release 1,283,653. of heat can be retarded by a suitable spacer. During the It should be emphasized once again that a main ad 20 solar irradiation, the energy is collected as latent heat in vantage of the use according to the invention resides in the fact that by selecting the crystalline crosslinked the panel. When the external air cools, in the evening synthetic resins which are used, melting points at which and again during the night, or on cool days, the storage panel releases the heat, to the interior of the building.

the heat storage is intended to take place can be selected The heat insulation in an outward direction can option over a wider temperature range. This is because the ally be increased crystallite melting point of the synthetic resins can be polystyrene foamyet further by temporarily mounting a varied in a controlled manner, for example, in the case crystalline polymers as aover sheet the glass plate. The use of structural foam is particularly of the use of epoxide resins, through the choice of the polyester-polycarboxylic acids in respect of the ali advantageous since in that case the storage action is phatic acids and alcohols contained therein and their 30 assisted by the insulating action. When applying the invention in heat rectifiers, the ratios, and through the length of the polyester-polycar boxylic acid segments. combination with an auxiliary liquid, as described in the Compared to salts, salt solutions and organic crystals abovementioned publication in "PANDA', is in gen it must also be emphasised, as a technical advance, that eral superfluous. However, this does not mean that this the synthetic resins used according to the invention in 35 combination should be fundamentally excluded when each case can not only take over the task of heat storage applying the invention in heat rectifiers. Thus, for ex but at the same time also can take over the function of ample, it is entirely possible technically to improve the a constructional material. Obviously, in such cases, it is system described in detail in PANDA, by means of the no longer necessary to hold the synthetic resins in a use according to the invention, whilst retaining the container, let alone in a corrosion-resistant expensive combination with the auxiliary liquid. metal container. In the application according to the invention in heat The crystalline, crosslinked epoxide resins (K) dis rectifiers, the heat-storing panels can consist solely of cussed above, which exhibit two crystallite melting the storage material containing black dyestuffs and points, are particularly suitable for use as the storage optionally fillers and other additives if, as in the case of material in latent heat stores whilst simultaneously as 45 the use of the crystalline, crosslinked epoxide resin (K), suming the additional function of a constructional mate the panels are inherently sufficiently dimensionally sta rial. Since these resins retain their good mechanical ble (tough and elastic). If this is not the case, it is appro properties even far above the Tm, they can, for exam priate to use a fibre laminate (preferably a glass fibre ple, also be employed as self-supporting elements (for laminate). For example, glass fibre-reinforced Venetian example in the form of panels). a 50 blinds which have mounted on the inside of the win A preferred form of the use according to the inven dow, are of interest. These not only act as a protection tion is to use the crystalline, crosslinked synthetic resins against the sun but at the same time as room heaters, and in latent heat stores, which are used for the storage and even after the solar irradiation has ceased and after rerelease of solar energy. In installations which sepa rolling up the blind, a certain heat output still continues. rately comprise solar energy collectors, exposed to the 55 In some cases the use of synthetic resin foams can also sun, in addition to the actual accumulators, and in be of advantage, according to the invention. which the heat is transferred by liquids, through pipes, The invention is not restricted to the use of the crys from one element to the other, the synthetic resins used talline, crosslinked synthetic resins in installations for according to the invention are contained in the accumu storing solar energy. According to the invention, the lators either as self-supporting elements (for example 60 synthetic resins can also be employed in latent heat panels) or in containers, in the form of powders or gran accumulators which serve for the storage and re-release ules. W. W. of types of energy other than solar energy. In this con However, the use according to the invention is also text, waste steam energy and off-gas energy from indus feasible for so-called "heat-rectifiers' which are used trial installations, power stations and drive units should for air conditioning of buildings and especially for cli 65 be mentioned particularly. There should also be men matic control of greenhouse. Heat rectifiers of the state tioned, quite generally, all types of heating energies in of the art are elements of relatively complicated con which economical utilisation can be improved by buff struction which allow the flow of heat to proceed virtu ering by means of latent heat accumulators. Thus, stor 7 age of electrical current at the cheap night rate is also can also be realised in full in extra-terrestrial regions, possible by means of the use according to the invention. such as, for example, in space, and in a vacuum. The invention also makes it possible quite generally EXAMPLE 1 to protect bodies against overheating or against over cooling. For this, the procedure followed is either that 5 (Epoxide resin (J)) the crystalline, crosslinked synthetic resins, used ac (a) Manufacture of the latent heat accumulator in a cording to the invention, are embedded as granules or panel form powders in the material to be protected, if appropriate in the parts of the body which are exposed to heat or 1,555 g (1.0 equivalent) of an acid polyester prepared cold, or that the synthetic resins are applied externally 10 from 11 mols of sebacic acid and 10 mois of hexanediol as a "protective packing' to the surfaces which are by the melt process are warmed to 110' C. and mixed exposed to heat or cold. In both cases, the crystallite well with 167 g (1.0 equivalent) of the following trie melting point is so chosen that it approximately corre poxide compound sponds to the desired normal temperature of the body which is to be protected. For example, batteries, bear the system is evacuated and the mixture is poured into ings of crankshafts, household equipment and the like Anticorodal moulds (internal dimensions 200x200x36 can be protected in the manner described. 30 mm), which have been treated with mould-release Following the same basic principle, bridges, roads, agents and pre-warmed to 120 C. The mixture was ramps and the like can also be kept free from ice by the cured for 16 hours at 140 C. A panel which is rubbery use according to the invention. elastic when hot and crystalline after cooling and which For the sake of completeness it should be mentioned has a crystallite melting point of 62 C. was obtained. that the use according to the invention is also feasible 35 The enthalpy of melting, measured with a DSC-2 differ for simpler systems, such as, for example, hotplates, ential calorimeter from Perkin-Elmer, was 20 cal/g. heated pillows ("hot-water bottles') and the like. Fur thermore, the use according to the invention is also (b) Test to determine the suitability for storing the feasible for medical-therapeutic treatments or for tem enthalpy of melting perature control, for example in photographic develop The panel obtained according to (a) was covered ment technology. with a thin sheet of foam and, on top of this, a thin By means of the invention it is also possible to release material. It was warmed at 70 C. in a drying cabinet heat in metered amounts to other bodies, at any desired until all the crystals had melted. Subsequently, the temperature, whilst keeping the selected temperature curve for the fall in temperature at the surface of the constant, and even given unfavourable circumstances in 45 panel was recorded at room temperature by means of a respect of space and size. Such prerequisites and re quirements apply, for example, when curing curable thermocouple, and a chart recorder. The valves ob tained from the measurements are summarised in Table synthetic resin mixtures in cable end seals or curing 1.

dental fillings or dental adhesives based on synthetic TABLE resins. If the bodies which are to take up the heat from 50 the storage material are structures of very complicated Time (hours) Temperature (C.), panel surface shape, it is appropriate to produce a negative mould 70 from the crystalline, crosslinked synthetic resin used 57 according to the invention. This ensures sufficiently 50 intensive contact during the subsequent heat transfer. In 55 47 many cases (such as, for example, in the case of cable 47 and sealing) it suffices, on the other hand, if the body to 48 be warmed is surrounded by the heat-charged storage 48 material in the form of a powder or granules. Here, as 47 also in use in dental technology, the use of rubbery-elas O 47 tic bodies, preferably panels, especially of the epoxide 12 resin (L), is also conceivable. Generally, panels of this type are easily deformable in the heated state, so that in this special use according to the invention they adapt in It can be seen from the temperature pattern that, an advantageous manner closely to the body to be 65 because of the heat of crystallisation which is released, heated. the system remains at 47-48 C., that is to say the re The use according to the invention is not restricted to crystallisation point of the system, for 6 hours and then terrestrial spaces and to the terrestrial atmosphere, but releases further heat in a delayed manner.

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EXAMPLE 2 have been pre-treated with a silicone mould-release agent and have been pre-warmed to 120° C. The mix

(Epoxide resin (JD) ture is cured for 16 hours at 140 C. Crystalline, tough (a) Manufacture of the latent heat accumulator mouldings with the following properties are obtained: 1,000 g (0.93 equivalent) of an acid polyester pre pared from 11 mols of adipic acid and 10 mols of hex Tensile strength according to anediol by the melt process are warmed to 110' C, and VSM 77,101 (moulding No. 1)* Elongation at break mixed well with 104 g (0.93 equivalent) of triglycidyl Crystallite melting point Tm" - 27 C. isocyanurate and 11 g of a black dye paste, the system is 10 Crystallite melting point Tm2 a 50 C. evacuated and the mixture is poured into Anticorodal "The mouldings are punched from the imm thick panel using a punching tool, The moulds (internal dimensions 200x200x24mm), which tensile test also corresponds to ISO R 527. have been treated with mould-release agents and pre nute), "Determined with a differential scanning calorimeter (heating rate = 10 C/mi warmed to 120° C. The mixture is cured for 16 hours at 140 C. A panel which is rubbery-elastic when hot and 15 crystalline after cooling and which has a crystallite The panel has two melting points which are ascribed melting point of 44' C. is obtained. The enthalpy of to the two polyesters used. Above the melting points, melting, measured with a DSC-2 differential calorime the moulding is soft and rubbery-elastic. It is suitable as ter from Perkin-Elmer, is 14.4 cal/g. a storage material for latent heat accumulators. (b) Use of the panel according to (a) as a heat rectifier 20 EXAMPLE 4

The experiment is carried out using the following (Epoxide resin (L) model climatic chamber: It consists of a box which is 77 g (0.05 equivalent) of an acid polyester prepared, made of a rigid plastic foam and which has, at the top, by the melt process, from 21 mols of succinic anhydride a square opening with dimensions of 200X200 mm. The 25 and 20 mols of butanediol and 35 g (0.05 equivalent) of wall thickness of the box is 10 mm, the internal height is an acid polyester prepared, by the melt process, from 8 120 mm and the internal widths are 240 mm. The latent heat store manufactured according to (a) is let into the molswarmed of adipic acid and 7 mols of neopentylglycol are square opening. A glass plate is fitted above the panel at equivalent) of triglycidyl isocyanurate and the mixture a distance of 5 mm. A thermocouple is fitted in the is poured into Anticorodal moulds which have internal

The following tests on climatic conditioning of the adimensions of 150X 150X 1 mm, have been treated with silicone mould-release agent and have been pre inner space of the box were carried out in Basle on warmed to 140 C. After removing the air, the mixture

The box was exposed to solar radiation from 11 a.m. is cured in vacuo for 16 hours at 140 C. Crystalline, soft The temperature measured by the thermocouple was 35 and tough mouldings are obtained, on which the follow recorded by means of a chart recorder. A temperature ing characteristics are determined:

pattern which is illustrated in Table 2 was obtained,

TABLE 2 Tensile strength according to VSM 77,101

Temperature (C.) Temperature (C.) 40 (moulding No. 1)* = 7.3 N/mm2 Time (hours) Blank test Heat rectifier Elongation at break according to VSM 77,101 a 350%

O 22 22 Crystallite melting point (T)" 100 C,

2 43 29 *The mouldings are punched from the 1 mm thick panel using a punching tool. (The 3 4. 33 tensile test also corresponds to ISOR 527) 4. 39 34 45 Determined with a differential scanning calorimeter (heating rate = 10/minute)

in The material obtained is suitable as storage material 6 9 24 for latent heat accumulators.

Example 5

The table also gives the values for a blank test. In this 189.2 g (=0.1 equivalent) of an acid polyester ob blank test a box was used which was of exactly the same tained from 10 mois dodecanedioic acid and 9 mols of construction as that employed in the main experiment, dodecanediol are warmed to 10 C, and mixed well the only difference being that the latent heat store was with 16.7 g (=0.1 equivalent) of the heterocyclic trie omitted. poxide compound of the formula IV and 1 g of 1 The temperature pattern on the simplified model 55 methylimidazole, the system is evacuated and the mix shows the rectifying effect of the heat rectifier pattern. ture is poured into a pre-warmed mould with dimen EXAMPLE 3 sions of 200=200=4 mm. After a heat treatment for 16 hours at 130°C., panels which are soft and rubbery-elas

(Epoxide resin (K)) 60 tic when hot and white and crystalline after cooling are 108 g (0.1 equivalent) of an acid polyester, prepared obtained: crystallite melting point: 81. C., enthalpy of from 11 mols of adipic acid and 10 mols of hexanediol melting 23 cal/g.

and 155 g of an acid polyester prepared from 11 mols of Two Anticorodal sheets 25 mm wide are stuck to Sebacic acid and 10 mols of hexanediol (both prepared gether using a cold-curing epoxide resin based on di by the melt process) was warmed to 100° C. and mixed phenylolpropane diglycidyl ether (1.0 equivalent) and well with 22 g (0.2 equivalent) of triglycidyl isocyanu diethylenetriamine (1.0 equivalent). After coating the rate and the mixture is poured into Anticorodal moulds surfaces to be stuck, the latter are joined together, plac which have internal dimensions of 150X 150x1 mm, ing on top a panel, which has been described above and 9 has been warmed to 100° C., of crystalline epoxide EXAMPLE 8 resin. After 1 hour, 30 minutes, the resin in the joint coated with adhesive is crosslinked and hard. A com 1.0 equivalent of the polyester having hydroxyl ter parison test is carried out with a panel, which is warmed minal groups (OH equivalent weight = 1,006), which is to 100', of a rubbery-elastic epoxide resin which does 5 described in Example 7, is reacted at 150 with 1 mol of not crystallise (reaction product obtained from 1 equiv maleic anhydride, a polyester with terminal carboxyl alent of sebacic acid-neopentylglycol (11:10) polyester groups resulting (equivalent weight 32 1,070). 70 g of with 1.3 mols of hexahydrophthalic acid diglycidyl the resulting polyester are mixed, at 70° C., with 30 g of ester and 0.3 mol of hexahydrophthalic anhydride). A styrene and 2 g of 50% strength benzoyl peroxide and, gelling time of 2 hours 30 minutes results. An analogous 10 after evacuating the system, the mixture is poured into experiment with accelerated trimethylhexame a tube 3.5 cm in diameter. After curing for 2 hours at thylenediamine as the curing agent gives a curing time 70, for 2 hours at 120 and for 2 hours at 140, a mould of 20 minutes with the crystalline epoxide resin, in con ing which is rubbery-elastic when hot and which trast to 40 minutes with the amorphous epoxide resin. changes into the crystalline state on cooling is obtained. The release of the heat of crystallisation accordingly 15 effects substantial acceleration of curing.

EXAMPLE 6 Crystallite melting point = 33 C.

Enthalpy of melting = 8 cal/g 159 g of an adipic acid-hexanediol (11:10) polyester, 134 g of a succinic acid-butanediol polyester branched 20 Mouldings of this type can also be employed for by means of a glycerol molecule and 50.1 g of an epox ide resin of the formula IV (corresponding to a ratio of storing energy.

1.0:1.0:2.0 equivalents) are warmed to 110° C. and We claim:

mixed well with 0.9 g of i-methylimidazole and 1.7 g of 1. An improved process of absorbing and releasing Cuphthalocyanine and the system is evacuated. The 25 thermal energy in a latent heat accumulator using a mixture is poured into pre-warmed moulds which have latent heat storage material, wherein the improvement dimensions of 200X200X7 mm and which contain 3 comprises layers of a 1 mm thick glass fleece. After heat treatment employing as the latent heat storage material a crys for 16 hours at 130 C. a tough, elastic, blue-coloured 30 talline crosslinked synthetic resin selected from the laminate which has crystallite melting points of 43' and group consisting of epoxide resins, polyurethane 54 C. is obtained. When set up in the vicinity of a resins, polyester resins and mixtures thereof which window inside a room, the laminate is warmed to 48 by contain, as crystallite-forming blocks, radicals of solar radiation. The low-melting crystallite is thus long-chain dicarboxylic acids or dialcohols of the melted by the solar radiation and serves as a heat store 35 formula I until the solar radiation decreases, whilst the higher X-A-X2 (I) melting crystal assists in maintaining the mechanical strength. Laminates of this type are therefore of particu in which X and X2 each represent a -CO-O-group lar interest as Venetian blinds inside rooms or as ceiling or a -O-group in which A denotes a substantially panels, for example as heat rectifiers for greenhouses.

40 linear radical, in which polymethylene chains alternate

EXAMPLE 7 regularly with ether oxygen atoms or carboxylic acid 1.0 equivalent of a polyester of 10 mols of sebacic ester groups, and the quotient Z/Q, wherein Z is the acid and 11 mols of hexane-1,6-diol and 1.2 mols of number of CH2 groups present in the recurring struc toluylene 2,4-diisocyanate are reacted hot (70° C.), with 45 tural element of the radical A and Q is the number of the exclusion of moisture and in a nitrogen atmosphere. oxygen bridges present in the recurring structural ele The adduct has an isocyanate equivalent weight of 862 ment of the radical A, must be at least 3 and wherein the (theory 868). 86.2 g (0.1 equivalent) of the resulting total number of carbon atoms present in the radical A in alternating carbon chains is at least 30, and wherein the adduct are warmed to 80' and mixed with 4.46 g (0.1 crosslinked crystalline synthetic resin has at least one equivalent) or hexanetriol, the system is evacuated and 50 crystallite melting the mixture is poured into a casting mould which has point. dimensions of 150X 150X1 or 150X 150X4 mm. After 2. A process to claim 1, characterised in that crystal curing for 2 hours at 70', for 2 hours at 120 and for 2 line, crosslinked synthetic resins which have only one hours at 140, a panel which is rubbery-elastic when hot crystallite melting point are used. 3. A process to claim 1, characterised in that crystal is obtained; at room temperature this changes into the partially crystalline state, with release of the heat of 55 line, crosslinked synthetic resins which contain several, different types of crystallite having, accordingly, sev crystallisation. The following characteristics are mea eral crystallite melting points are used. sured:

4. A process to claim 1, characterised in that epoxide resins are used.

Crystallite melting points = 5 C. 5. A process according to claim 1, characterised in

Enthalpy of melting = 16 cal/g that crystalline, crosslinked epoxide resins which are Tensile strength (ISO) = 24 N/mm2 obtained by reacting polyester-dicarboxylic acids with polyepoxide compounds having at least 3 epoxide groups, about 1 equivalent of polycarboxylic acid being

The advantageous mechanical properties and the 65 present per equivalent of epoxide compound, are used. thermal properties make it possible to use this panel as 6. A process according to claim 1, characterised in energy stores, such as, for example, heated pillows or that crystalline, crosslinked epoxide resins which are heat rectifiers. obtained by reacting polyester-polycarboxylic acids 10 having at least 3 carboxyl groups with epoxide com in which n and m are identical or different and pounds having at least 2 epoxide groups, about 1 equiva denote 2 or a higher number than 2, and to which lent of polyester-carboxylic acid being present per the condition n--m= 6 to 30 applies, and in which equivalent of epoxide compound, are used. p denotes a number from 2 to 40, which, however, 7. A process according to claim 1, characterised in 5 is sufficiently large that the segment contains at that crystalline, crosslinked epoxide resins which are least 30-CH2-groups, and obtained by reacting diepoxide compounds with polyes (b) with polyester-polycarboxylic acids E which es ter-dicarboxylic acids and with dicarboxylic acid anhy sentially contain segments of the formula III drides in an equivalent ratio of 1:0.4 to 0.9:1 to 0.6 are used. 10 -O-(CH2)-O.CO-(CH2)-CO- (III) 8. A process according to claim 1, characterised in that crystalline, crosslinked epoxide resins which are in which s and rare identical or different and de obtained by reacting polyester-polycarboxylic acids note 2 or a higher number than 2, and to which the with epoxide compounds of the group comprising tri- condition s+r-2 sn+m applies, and in which q glycidyl isocyanurate and triglycidyl compounds which 15 represents a number from 2 to 40, which, however, contain one or more hydantoin groups or dihydrouracil is sufficiently large that the segment contains at groups, are used. least 30-CH2-groups, and 9. A process according to claim 8 wherein the crystal- (c) with curing agents C, in a ratio such that 0.5 to 1.2 line, crosslinked epoxide resin is obtained by reacting a equivalents of polyester-polycarboxylic acid are polyester-polycarboxylic acid with the compound of 20 present per equivalent of epoxide compound, that formula IV 1/10 to 9/10 of these 0.5 to 1.2 equivalents are

O ch - s. ch3 o / v / n

10. A process according to claim 1, characterised in attributable to the polyester-polycarboxylic acid D that crystalline, crosslinked epoxide resins (J), which and the remaining 9/10 to 1/10 to the polyester are manufactured by reaction of epoxide compounds, polycarboxylic acid E, and that zero to 0.6 equiva containing two or more epoxide groups, lent of curing agent C is present per equivalent of (a) with polyester-polycarboxylic acids D, which epoxide compound, with the proviso that, in the essentially contain segments of the formula II cases in which only difunctional epoxide com pounds and difunctional polyester-polycarboxylic -O-(CH2)n-0.CO-(CH2)n-CO- (II) acids D and E are employed, the epoxide groups in which n and m are identical or different and must be present in excess and the reaction with a curing agent C is essential are used.

denote 2 or a higher number than 2, and to which 45 12. A process according to claim 1, characterised in the condition n+m=6 to 30 applies, and in which that crystalline, crosslinked, elastomeric epoxide resins p denotes a number from 2 to 40, which, however, (L), which are manufactured by reaction of epoxide is sufficiently large that the segment contains at compounds, containing two or more epoxide groups, least 30-CH2-groups, and (a) with polyester-polycarboxylic acids A which es (b) with curing agents C, in a ratio such that 0.5 to 1.2 50 sentially contain segments of the formula V equivalents of polyester-polycarboxylic acid are present per equivalent of epoxide compound and -O-(CH2)n-O.CO-(CH2)n-CO)- (V) Zero to 0.6 equivalent of curing agent Care present per equivalent of epoxide compound, with the in which n and m are identical or different and proviso that, in the cases in which only difunctional 55 denote 2 or a higher number than 2, and to which epoxide compounds and difunctional polyester the condition n--m-6 to 30 applies, and in which polycarboxylic acids D are employed, the epoxide p denotes a number from 2 to 40 which, however, groups must be present in excess and the reaction is sufficiently large that the segment contains at with a curing agent C is essential, are used. least 30 -CH2-groups, and 11. A process according to claim 1, characterised in (b) with polyester-polycarboxylic acids B which es that crystalline, crosslinked epoxide resins (K), which sentially contain segments of the formula VI are manufactured by reaction of epoxide compounds, containing two or more epoxide groups. -O-R-O.CO-R-CO- (VI) (a) with polyester-polycarboxylic acids D which essentially contain segments of the formula II 65 in which R1 and R2 are identical or different and denote an alkylene radical with at least 2 C atoms in the chain and in which, per Obridge, an average of at least 3.5 and at most 30 C atoms, without 11 taking into account the C atoms of the 'CO.O- 15. A process according to claim 1, characterised in radicals, are present in the chain, and wherein the that the crystalline, crosslinked synthetic resins are used in the form of foams.

radicals R or R2 contain at least one alkyl group, 16. A process according to claim 1, characterised in or cycloalkyl group or one aryl group as a substitu that the crystalline, crosslinked synthetic resins are used ent for one H atom or one ring-forming optionally in the form of laminates.

substituted alkylene group as a substituent for two 17. A process according to claim 1, characterised in H atoms of a chain, and in which q denotes a num that the crystalline, crosslinked synthetic resins are used in the form of a powder or a granules, which are filled ber from 2 to 40, which, however, is sufficiently 10 into a container. - large that the segment contains at least 30 C atoms, without taking into account the C atoms of the that those crystalline, crosslinked1, synthetic 18. A process according to claim characterised in resins -CO.O-radicals in the chain, and which, after absorption of the heat of melting of the (c) with curing agents C, in a ratio such that 0.5 to 1.2 crystallites, are readily deformable and rubbery-elastic equivalents of polyester-polycarboxylic acid are 5 and are employed in the form of panels or mouldings. present per equivalent of epoxide compound, that 19. A process according to claim 1, characterised in 5/10 to 9/10 of these 0.5 to 1.2 equivalents are that the crystalline, crosslinked synthetic resins are used attributable to the polyester-polycarboxylic acid A in heat rectifiers, for controlling the absorption of solar and the remaining 5/10 to 1/10 to the polyester 20 energy in areas which are to be climatically controlled. 20. A process according to claim 1, characterised in polycarboxylic acid B, and that zero to 0.6 equiva that the crystalline, crosslinked synthetic resins are used lent of curing agent C is present per equivalent of in latent heat accumulators which serve to supply heat epoxide compound, with the proviso that, in the during the hot curing of curable synthetic resin mix cases in which only difunctional epoxide com tures in dental technology.

pounds and difunctional polyester-polycarboxylic 25 that21. those

A process according to claim 1, characterised in acids A and B are employed, the epoxide groups which containcrystalline, crosslinked synthetic resins nucleating agents, selected from phthalo must be present in excess and the reaction with a cyanines or a-naphthoic acid, are employed. curing agent C is essential, are used. 22. A process according to claim 1, characterised in 13. A process according to claim 1, characterised in 30 that those crystalline, crosslinked synthetic resins that the crystalline, crosslinked synthetic resins are used which contain fillers which assist the heat conductivity in latent heat accumulators which serve for the storage are selected from aluminium, carbon black and graphite, and re-release of solar energy. employed.

23. A process according to claim 1, characterised in 14. A process according to claim 1, characterised in 35 that those crystalline, crosslinked synthetic resins that the crystalline, crosslinked synthetic resins are used which contain flame-proofing fillers selected from alu in latent heat accumulators which serve for the storage minium oxide trihydrate, antimony trioxide and chlori and re-release of types of energy other than solar en nated paraffins are employed. k is it is ergy.

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United states patent and trademark office

Certificate of correction

Inventor(s) : ursula kreibich and rolf schmid

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby Corrected as shown below:

Claim 2, Column l8, Line l reads:

"A process to claim l, characterised in that crystal-" Should read:

"A process according to claim l, characterised in that crystal-" Claim 3, Column l6, Line ll reads:

"A process to claim l, characterised in that crystal-" Should read:

"A process according to claim l, characterised in that crystal-" Claim 4, Column l6, Line l reads:

"A process to claim l, characterised in that epoxide" Should read:

"A process according to claim l, characterised in that epoxide" eigned and scaled this

Tenth Day of November 1981

Seal

Gerald j. mossinghoff

Attesting Officer Commissioner of Patents and Trademarks