JPS59197486A - Composition for heat energy storage - Google Patents

Abstract

PURPOSE:To provide a thermal energy storage composition which has cooling ability approximating a theoretical amount of latent heat and has excellent persistent stability, consisting mainly of Glauber's salt and containing a carboxyl group-containing water-soluble synthetic resin and a specified silicon dioxide as thickeners. CONSTITUTION:The thermal energy storage composition consists of 100pts.wt. sodium sulfate decahydrate (or eutectic salt thereof), 1-10pts.wt. sodium borate decahydrate, 1-10pts.wt. carboxyl group-containing water-soluble synthetic resin (e.g. polysodium acrylate having a pH of about 7.5-9.5 and a viscosity of about 3,000-50,000 as measured with a 0.5% aqueous solution at 25 deg.C) and 1-5pts.wt. inorganic substance consisting mainly of silicon dioxide which has a linseed oil absorption of 50-400mg/100g, a BET specific surface area of 7,000- 300,000cm<2>/g and a pH of 8-11 as measured with 0.5% aqueous dispersion.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to heat storage compositions with improved long-term durability.

As a means of solar heat utilization or waste heat recovery, heat storage materials are based on weight, and in particular, latent heat storage materials using hydrated salts have traditionally been used.Sensible heat storage feed such as water, concrete, gravel, etc. It has the advantage of high heat storage density, and is attracting attention.

The hydrated salt used for this purpose absorbs and releases a large amount of latent heat during the solidification-melting phase change, and the phase change temperature is within the usable temperature range, i.e., 15°C to 6°C.
It must satisfy the condition of being in the 0°C range.

Such hydrated salts include sodium sulfate decahydrate (
(hereinafter referred to as Glauber's Salt) is considered promising. Glauber's salt has low corrosivity to metals and has no harmful effects on the human body or property, making it extremely suitable as a heat storage agent, especially for building materials.

However, when using Glauber's salt as a heat storage agent,
Various problems have existed in the past.

First, sodium borate 1 is used as a nucleating agent to prevent supercooling.
Although 0-hydrate salt (hereinafter referred to as borax) is dispersed, the borax separates and settles and no longer functions effectively as a nucleating agent.

@2: When Glauber's Salt melts, the solubility of sodium sulfate in water is low, and the entire amount does not dissolve in the free crystal water, but a portion separates and precipitates as sodium sulfate, returning to the original hydrated salt. There was a problem that made it impossible to do so.

As a solution to these problems, it has been conventionally practiced to use thickeners to increase the viscosity of the system in the molten state.For example, fine silica powder, sodium polyacrylate, etc. have been used as thickeners. It is already known to do so.

However, although sodium polyacrylate has an extremely excellent thickening effect, it has a large water retention property and cannot reversibly release the water taken in during melting of Glauber's salt during recrystallization. Although increasing the amount of polyacrylic acid added, there is a problem in that the amount of latent heat of Glauber's salt decreases. In addition, fine silica powder has little thickening effect,
Therefore, in order to obtain the desired thickening effect, it is necessary to add a large amount, but in this case, gelation occurs significantly, and it is difficult to fill the container with the heat storage agent or mix it with the hardening resin. There are some problems that may interfere with the operation.

As a result of intensive studies to solve the above problems, the present inventors combined a water-soluble synthetic resin having a carboxyl group as a thickener with an inorganic material mainly composed of silicon dioxide having specific properties. By using this heat storage agent composition, it is possible to obtain a composition that exhibits an extremely good thickening effect and has suitable fluidity, and that this heat storage agent composition exhibits performance close to the theoretical latent heat amount and has excellent stability over time. The present invention was completed based on the discovery of this method, which is also excellent.

The gist of the present invention is sulfuric acid) 100 parts by weight of IJium decahydrate or its eutectic salt, 1 to 10 parts of sodium borate decahydrate.
parts by weight, 1 to 10 parts by weight of a carboxyl-based water-soluble resin, and linseed oil absorption of 50 to 400 mg/
1009, and the BET specific surface area value is 7.000 to 30.
The present invention relates to a heat storage agent composition comprising 1 to 5 parts by weight of an inorganic substance whose main component is silicon dioxide having a particle diameter of 0,000 m/P.

An example of the present invention will be described below.

In the present invention, the heat storage agent is mainly composed of Monoke's salt or its eutectic salt. Glauber's salt is a monoclinic crystal with a temperature of 32°C and a latent heat of solidification of 60 m'/y (93eA/cc). This is advantageous for directly and indirectly absorbing and dissipating heat.

By making a eutectic salt with mirabilite, for example, sodium chloride or ammonium chloride, the melting point can be arbitrarily controlled within the range of 15 to 32°C.

For example, when natural energy such as solar heat is stored to provide simple heating, the melting point of the heat storage agent is preferably 15 to 25°C.

Smooth solidification and crystallization of Glauber's salt or its eutectic salt is an essential condition for preventing supercooling. In the present invention, sand is used as a nucleating agent in mirabilite or its eutectic salt. Borax is used in an amount of 1 to 10 parts by weight per 100 parts by weight of the eutectic salt of Glauber or Keso. When the mirabilite or its eutectic salt is coagulated and crystallized, the mirabilite or its eutectic salt comes into contact with the solid grains of borax and grows on the surface of the borax.

In the present invention, a water-soluble resin having a monocarboxylic group is used as the thickener.

As a water-soluble synthetic resin having a carboxyl group, polyacrylic acid, polymethacrylic acid, acrylic acid-methacrylic acid copolymer, carboxyl cellulose, styrene-maleic acid polymer 1 or potassium thereof,
Alkali metal salts such as sodium and lithium are preferred. Further, these water-soluble resins having carboxyl groups may be lightly crosslinked to the extent that water solubility is not impaired. Among the water-soluble resins mentioned above, sodium polyacrylate and potassium polyacrylate are particularly preferably used. The viscosity of a 0.5% aqueous solution of these water-soluble resins at 20°C is 3,000~so, o o
o centiboise range, and preferably has a pH in the range of 7.5 to 9.5.

In the present invention, an inorganic material containing silicon dioxide as a main component in combination with a water-soluble resin having a carboxyl group is used. Silicon dioxide has particularly good affinity with organic substances compared to conventionally used silica fine powder, and has an affinity with water-soluble resins to increase the thickening effect. Inorganic substances whose main component is silicon dioxide are used with specific properties, and the range is linseed oil absorption of 50 to 400 me/10
09, and the 13ET specific surface area value is 7,000-3
00,000 cd/y.

It is composed of an inorganic substance whose main component is silicon dioxide.

``Linseed oil absorption amount'' refers to the value measured in accordance with Japanese Industrial Standards K-5101.
Q) Drop a small amount of linseed oil into the center of the sample from a bilulet, knead the whole thing thoroughly each time, and see if the sample suddenly becomes soft with a drop of linseed oil and sticks to the glass plate. The end point is just before the oil reaches the oil level, and the oil amount is 1. If the linseed oil absorption amount of the "k'J/k" product whose main component is silicon dioxide is less than 50 me/1009, it is necessary to combine it with the above-mentioned organic thickener, a water-soluble resin having a carboxyl group. Due to lack of compatibility, a synergistic effect cannot be obtained when used in combination with silicon dioxide. On the contrary, the oil absorption amount of linseed oil is 400rnI! /100g! If it exceeds this, the thickening effect will decrease. Linseed oil absorption amount is 50-400d/
) When using an inorganic material whose main component is silicon dioxide in the range of Thickening; effect is exhibited.

Furthermore, as will be described later, when an unsaturated polyester resin is mixed into the system, a favorable affinity is created between the inorganic material containing silicon dioxide as a component and the unsaturated polyester resin.

The inorganic substance containing silicon dioxide as a main component in the present invention is B
A material having an ET specific surface area value in the range of 7,000 to 50,000 d/y is used, and a material having an appropriate surface area is used. The BET specific surface area value is Brunauer −
This value is calculated from the multilayer adsorption theory proposed by Emmett-Teller and is based on the theory of J.
nuclear of American Chemica
l 5ociet 60, 309 (1938)
;59.2682 (1937), etc.

The BET specific surface area value is the amount of gas adsorbed on the surface of an inorganic material whose main component is silicon dioxide. This value is calculated by multiplying this by the average cross-sectional area of the adsorbed gas molecules. As the adsorbed gas, nitrogen gas, oxygen gas, argon gas, 1 tung gas, etc. are used. According to this method, the surface area value of the inside of an inorganic substance containing silicon oxide as a main component including silk can be measured.

If the surface area value of the inorganic substance containing silicon dioxide as the main component is less than 7,000ad/Y, the thickening effect cannot be obtained satisfactorily because the active surface area for thickening is small; ,000erI/P, gelation occurs and the fluidity of the composition becomes extremely poor when the heat storage agent is melted. Those exhibiting a linseed oil absorption amount and a BET specific surface area value can be used, but it is preferable that the aqueous suspension thereof exhibits alkalinity. One of the reasons for this is that for water-soluble resins that have carboxyl groups, when inorganic substances mainly composed of silicon dioxide are alkaline in water dispersion, they increase the chemical activity of carboxyl groups and have a thickening effect on the system. Another reason is that when an unsaturated polyester resin (described later) is added to the system, it contributes to the activation of the functional groups of the resin.

That is, the terminal carboxyl group of the unsaturated polyester is activated and has surfactant-like properties, so that the unsaturated polyester is arranged to surround the heat storage agent particles.

A particularly suitable inorganic material having the above-mentioned characteristics and having silicon dioxide as its main component is one obtained by refining natural algae.

In the heat storage agent composition of the present invention, the water-soluble resin having a carboxyl group is contained in 1 to 10-QJL parts of Glauber's salt or its eutectic salt.
5 parts by weight are used.

If the water-soluble resin having a carboxyl group is less than 1 part by weight per 100 parts by weight of Glauber's salt or its eutectic salt, the thickening effect will be small, and microdispersion of Glauber's salt or its eutectic salt will not be prevented. If the amount exceeds 1 part by weight, the heat storage agent composition will become too viscous and the latent heat amount of the entire heat storage agent composition will decrease.

If the inorganic substance containing silicon dioxide as a main component is less than 1 part by weight per 100 parts by weight of Glauber's salt or its eutectic salt, the effect of increasing the viscosity on water-soluble resins having carboxyl groups will be diminished, and if it exceeds 5 parts by weight, The affinity for water-soluble resins having carboxyl groups becomes excessive, resulting in gelation and poor fluidity in the molten state of the heat storage agent.

resistant, inorganic substances whose main component is silicon dioxide) ■ Desirable.

The heat storage agent composition of the present invention includes 100 parts by weight of Glauber's salt or its eutectic salt, 1 to 10 parts by weight of borax, 1 to 10 parts by weight of a water-soluble resin having a carboxyl group, and 1 to 5 parts by weight of an inorganic material whose main component is silicon dioxide. However, this composition can be used as a heat storage agent as it is filled in a hollow container.

The heat storage agent composition of the present invention can be used more stably by adding an unsaturated polyester resin, mixing it, and polymerizing and curing the unsaturated polyester resin with the heat storage agent particles dispersed in the unsaturated polyester resin. I can do it.

In this way, in the case where the heat storage agent is dispersed and fixed in the resin matrix, separation of the above-mentioned nucleating agent and anhydrous salt from the heat storage agent composition is more effectively suppressed, and heat storage performance is stably obtained. Used as a heat storage body with excellent mechanical strength.

The unsaturated polyester resin for dispersing and fixing the heat storage agent composition of the present invention is a condensation polymer of an unsaturated polybasic acid and G1, COL, L, or a crosslinkable monomer! - or a combination of an unsaturated polybasic acid and a saturated polybasic acid, and a condensation polymer of glycol and a crosslinking monomer are used. 1. As the Japanese polybasic acid, maleic anhydride,
Tuma, ~j acid, itaconic acid, etc. are used, and saturated polybasic acids: h4t, heptatalic anhydride, isophthalic acid, terephthalic acid, etc. are used. Glycols include propylene glycol, ethylene glycol, diethylene glycol, dipropylene glycol, neopentyl glycol, butanediol 1.3, gukundiol, le 1,4.2
．． 2'di(4-hydroxypropoxyphenyl)gronohen and the like are used.

As the crosslinking monomer, styrene, metal methacrylate, methyl acrylate, acrylonitrile, diallyl phthalate, etc. are used. The crosslinkable hexamer is added in a ratio of 0 to 50 parts by weight based on 100 parts by weight of the above-mentioned bonded polymer.

The curing reaction is caused by polymerization of the unsaturated polyester resin, and catalysts and accelerators are used.

As a catalyst, penzoyl oxide, U1F,
Dicumyl l<-oxide, t-ref l 1 trouble, L
The promoter is a substance that decomposes the catalyst through a redox reaction and facilitates the generation of active radicals, such as cobalt acid,
Cobalt octoate, naphthene + ptmanganese, dimethylaniline, phenylmol monophosphate, phenylphosphinic acid, etc. are used for larel.

Addition of catalyst and accelerator to unsaturated polyester resin 1
00 parts by weight, the catalyst is used in the range of 0.2 parts by weight to 2.0 parts by weight, and the promoter is used in the range of 0.05 parts by weight to 2.0 parts by weight.

As a means for mixing the heat storage agent composition of the present invention and the unsaturated polyester plum fat, the heat storage agent composition is melted into a liquid state and the unsaturated polyester plum fat is mixed liquid/liquid and then stirred with a stirrer. A method of polymerizing and curing a heat storage agent composition suspended in an unsaturated polyester resin by mixing, and a method of forming a heat storage agent composition into particles in advance by means such as crushing or pellet molding. Any method of polymerization or curing while solid/liquid mixing with the unsaturated polyester resin may be used.

The dispersion units of the heat storage agent composition dispersed in the unsaturated polyester resin greatly influence the heat storage performance. It is preferable that the dispersion unit of the heat storage agent composition is in the range of 0 μ to 2 fl. If the nucleating agent is less than θμ, the heat storage performance will be decreased because the nucleating agent will not be incorporated uniformly into each dispersed particle, and conversely, ~ or more, the solidifying effect of the resin disappears.

1-1 (A heat storage body in which the heat storage agent composition of the present invention is fixed with an unsaturated polyester resin is filled in a moisture-impermeable hollow container, or a surface material made of a moisture-impermeable material is placed inside the heat storage body) Used by attaching it to a surface.

For hollow containers or surface materials, polyethylene, polypropylene, ethylene-propylene copolymer, polyvinyl chloride, polyethylene terephthalate, polybutylene terephthalate, unsaturated polyester resin, epoxy resin,
and synthetic resin materials such as composites of these resins and glass fibers, laminates of these resins and aluminum, metal materials such as aluminum, stainless steel, copper, and brass, and inorganic materials such as ceramics, porcelain, and cement. used.

The heat storage body composition obtained by the present invention uses a water-soluble resin having a carboxyl group as a thickener and an inorganic material mainly composed of silicon dioxide having an appropriate range of oil absorption and surface area, so that it has excellent thickening properties. effect, and there is no viscosity deterioration over time, so the conventional problems of heat storage performance remaining at a low level and the problem of heat storage performance decreasing over time are completely resolved. Ta.

The heat storage body composition invented by Mengi can be used, for example, in housing systems such as heat storage wall materials, heat storage floor materials, trompe walls, auxiliary heaters using heat pipes or heat pumps, and waste heat utilization. It can be used as a heat storage material.

<Example 1> After heating and melting 1 piece of Glauber's salt at 50°C, 602 pieces of borax was melted.
As a thickener, the viscosity of a 0.5% aqueous solution is 11,000 centipoise, the pH value is 8.6, sodium polyacrylate is used as a thickener, and the linseed oil absorption is 170 centipoise.
/ 100 f, and the BET surface bond value is 50,0
00d/y and the pH of the 5% aqueous dispersion is 7.0.20y
The mixture was added and stirring continued for approximately 90 minutes. The thus obtained heat storage body composition was filled into a cylindrical polyvinyl chloride container with an inner diameter of 40 m and a height of 70 mm, and the container was sealed tightly with a CA thermocouple for temperature measurement enclosed therein. By alternately immersing this polyvinyl chloride container in a constant temperature water bath of 40°C on the high temperature side and 10°C on the low temperature side for 162 hours each, the heat storage agent composition sealed in the healing container was subjected to repeated heat cycles, and the heat storage agent composition was repeatedly cooled and heated for 10 times. The amount of latent heat was measured after 100 times, 100 times, and 1000 times. The results are shown in Figure 1. Latent heat amount and its stability over time 1. It was good for males.

Example: Glauber's salt 1 to 9 and chloride) After heating and melting IJ Kumu 502 at 50°C, borax fI: 60y, 0 as a thickener
．． The viscosity of a 5% aqueous solution is 11. 6 in OOO centipoise
D. A total of 209 inorganic substances whose main component is silicon dioxide derived from diatomaceous earth was added to the mixture, and stirring was continued for about 90 minutes.

Example 1 of the heat storage body composition thus obtained
The amount of latent heat was measured using the same method. The results are shown in FIG. 1, and both the amount of latent heat and its stability over time were good.

<Example 3> The heat storage body composition prepared in Example 1 was kept in a molten state at 45°C, 430 g of an unsaturated polyester resin composition having the following composition was added to this composition IKS+, and the composition was mixed using a homomixer. 3. After stirring for 20 seconds at a rotation speed of OOORPM, it was cured.

- Figure 1 shows the measured values of the latent heat amount of the obtained heat storage body composition by the same method as in Example 1. Both the amount of latent heat and its stability over time were good, and no change over time was particularly observed.

<Comparative Example 1> After heating and melting I kg of dead nitric acid at 50°C, borax was added to 6 kg.
02, the viscosity of the 0.5% aqueous solution as a thickener is 11.00
5 oy of sodium polyacrylate f having a pH of 8.6 and 0 centipoise was added, and stirring was continued for about 90 minutes. The amount of latent heat of the heat storage composition thus obtained was measured in the same manner as in Example 1. The result is the first
As shown in the figure, the latent heat content deteriorated significantly due to repeated cooling and heating cycles.

[Brief explanation of the drawing]

FIG. 1 is a rough graph showing the heat storage performance of Examples and Comparative Examples. Patent applicant Director of the Institute of Industrial Science and Technology Stone
0\

Claims (1)

[Claims] 1 100 parts by weight of sodium sulfate 1o hydrate or its eutectic salt, boric acid) 1 to 10 parts by weight of IJ cum 1o hydrate, 1 to 1°M nail portion of a water-soluble resin having a carboxyl group , and the linseed oil absorption amount is 50 to 400 mei and 100 pT,
BET specific surface approximate value is 7,000 ~ aoo, ooOm/y
Particularly, the heat storage agent composition is composed of 1 to 5 parts by weight of an inorganic substance whose main component is silicon dioxide. The heat storage agent composition according to claim 1, which is 8 to 11.