DE2024152A1 - Method for preventing condensation from forming on a surface - Google Patents

Description

Patent attorney Woifgang Schönherr

TRIER, Christophsir, 23

Trier, I3.5.I97O D 112

Richard Delano Setauket, New York, USA

and

Chad Joseph Raseuan Setauket, New York, USA

Method for preventing condensation from forming on a surface

The invention relates to a method for preventing condensation from forming on the inner surface of greenhouse walls or »ceilings, swimming pool, hoods, tennis halls and other types of plastic or glass enclosures.

0Ö9848 / 1648

Greenhouse plants require a fairly high temperature. The plants also need sunlight for photosynthesis "To make full use of sunlight." the greenhouses are generally made essentially of glass or clear plastic. During photosynthesis, or when the plants are warmed by solar radiation or other means, they give off water vapor into the atmosphere. This water vapor rises. Since the temperature outside the greenhouse is often lower than the temperature inside the greenhouse *, the water vapor tends to condense on the inside of the greenhouse glass or plastic surface and a slight haze towards it form." This vapor is disadvantageous because it reduced the penetration of the solar light through the glass or plastic Further, the condensed moisture settles and ₉ begins to drip onto the plants, persons or the floor "The dripping water damages the plant and reduces its market value." Plus, that's dripping for

009848/1849

those working in the greenhouse are unpleasant and the wet floor can be dangerous.

A similar problem exists with a swimming pool hood. Evaporation from the pool's large surface area causes its glass or plastic hood to be covered with a slight haze. The haze looks unpleasant from _o even more "is term} that an arresting uncomfortable by the drops of water inside the hood ·

The invention has the object of the to avoid this disadvantage. The method according to the invention causes the inner surface of the Greenhouse or the walls and ceilings of a swimming pool hood are hydrophilic, which prevents water will drip from them.

According to the method of the invention, the interior glass and plastic surfaces of the greenhouse walls are made and the roof with an anti-haze Treated «The fabric is either a spray or a

009848/1649

Liquid brought to the area · In the latter Trap he is either with an absorption applicator or applied with a roller applicator · Once applied, the fabric dries up an invisible capillary net-like fi 1λ Der Film acts like a drain for moisture. The rising moisture condenses and becomes in caught in the gaps of the network-like film. It is caused by the capillary action on the Side walls of the greenhouse run down The fabric used in the method according to the invention is applied consists of an aqueous dispersion of colloidal alumina, such as e.g. "Baymal" or »Alon" ·

"Alon", a registered trademark of Cabot Corporation, is a vaporized aluminum oxide of various crystallization forms, which are predominantly of the gamma modification. "Alon ¹¹ is produced by the hydrolysis of aluminum chloride in an annealing process.

0Q9848MB49

"Baymal", a registered trademark of DuPont, is a colloidal aluminum oxide · It is a white, free-flowing powder that consists of a lot of win « umpteen boehmite fibrils ALO (OH).

The high positive surface charge of the "Alort" and "Baymal" «Particles in an aqueous dispersion he« indicates that the particles interact rapidly with the negative hydrophobic surface, such as the glass or plastic hood a greenhouse or a swimming pool «have · The particles interact with the surface to to make a film about it. This film does the glass «or plastic surface is hydrophilic Film is microporous, quickly wet and slowly water permeable · In addition, the film is used for the

To give surface anti-static conditions »The f

positively charged fibrils of aluminum oxide who « those attracted to the negative surface. The absorption of the fibrils continues until the the whole surface is covered with a layer of alumina fibers. The surface is there « by changing from a negative to a positively charged one

00984 8 / 18.49-

202 A 1

State transformed · The film formed is porous and relatively resistant to abrasion due to hot treatment. Areas that were forgotten during the original application or that are later scraped off can be covered quickly by spraying or other application methods. The blowing out of aluminum oxide particles to the surface also depends on the concentration of the aluminum oxide used and on the pH conditions. However, it is relatively independent of the temperature conditions.The amount of aluminum oxide required to cover the surface when the aluminum oxide particles are thin is given by the following formula:
Percentage by weight of aluminum oxide (based on substrate) is equal to 0.1 times the particular upper »

2
Area of the substrate (in η / g) of "Baymal" and "Alon" or microporous material with a high specific surface. "Baymal" usad "Alon" are effective adsorbents. The colloidal aluminum oxide particles, which are naturally fibrils, tend to combine in water around a network of particles or are relatively dense

D 0 9 8 4 8/1 6 4 9

packed fibrils of colloidal alumina to yield · The fibrils are believed to have passed through hydrogen bond tied to each other

Colloidal dispersions of 10 to 40 % aluminum oxide are very gelatinous liquids or heavy thixotropic pastes with a pH value of 4. Their viscosity can increase considerably when a strong acid or base is added · The high viscosity of the highly concentrated dispersion, for example 10 % or higher, makes the preparation of a homogeneous dispersion difficult. However, good homogeneity can be obtained by using a stirrer. However, for convenient processing it is advantageous to reduce the viscosity of the concentrated dispersion. This is easily achieved by making the dispersion more pure . The use of a colloid mill in this case is difficult ([

highly recommended «When preparing the aluminum ·· Miniumoxyddispersion must be taken to ensure that the water is essentially free of salts, i.e. pure of sulfates, phosphates or silicates, since it is difficult to disperse aluminum oxide in water,

009848M649

which contains salts. The presence of salts, particularly the salts of polyvalent anions, tends to increase viscosity and thixotropy. Aluminum salts are the worst culprits. When preparing the aluminum oxide dispersion, it should be noted that if only hard water is present, a small percentage of acid, for example 0.1 % acetic acid, is added to the water in order to aid the dispersion. If there is a higher concentration of sulfates in the water, addition of barium acetate to precipitate the sulfates and filtration of the insoluble sulfates is required

The glass »or plastic surface that comes with the Fabric is covered by the method of the invention, often contains a grease-like film »This film acts on the moistening of the surface with the aluminum oxide dispersion and accordingly on the adhesion of the aluminum oxide to the glass or plastic disturbing. It has been found that this problem by adding an anionic

009848/1049

or non-ionic humidifying agent can be dissolved to the aluminum oxide dispersion «

A preferred surfactant found for this purpose is "Tergitol TMN", a non-ionic surfactant. Another suitable surfactant is "Tergitol 15-S-7". "Tergitol TMN" is a trimethyl nonyl polyethylene glycol ether _8, a non-ionic surfactant. "Tergitol 1>S-7" is a polyethylene glycol ether of linear alcohol, also a non-ionic surfactant. Other suitable surfactants are "Sipex BOS", a product of Alcolac Chemical Co., which is a sodium 2-ethylexyl sulfate and "Igepal CO 430" which is a nonylphenoxy-poly (ethyleneoxy) -ethanol · cationic

surface active «Agents should be avoided because"

they are incompatible with the electropositive colloidal alumina.

The dispersion is preferably applied at a heat of over 71 ° C, for example # tw · 9 ^ ° C «

so that the dried coating remains on the surface · Alternatively, the disper « sion are applied and the plastic or other surface is heated while the persion is still wet ο for example art can » material film can be sprayed with cold liquid dispersion »Then the film is up to 71 ° C heated by a wallpaper remover with a warming device. The plastic is thereby on a Wall temperature of 100 C heated and each side®. the plastic film can be heated o The heat helps to keep the coating on the surface after the water of the dispersion has dried »

The following example is given and represents to illustrate the method according to the invention no limitation of the invention *

Example:

An Alon dispersion is prepared as follows: 30 g of Alon are dispersed in 100 ml of water o The Alon aluminum oxide powder is quickly

009848/1649

-libel added to moisten it and give a uniform, thin-bodied paste before the aluminum oxide particles begin to swell · The movement is maintained as the viscosity develops · The air drawn in is removed by increasing the vacuum by allowing the dispersion to occur The quality of the dispersion can be determined by spreading a layer of dispersion a few millimeters thick on a glass surface. A good dispersion should be translucent. The pH of the dispersion is established by adding acetic acid to to bring the pH to 4.0. The dispersion is then used as part of a concentrate for the preparation of the final product. The concentrate can be transported, sold and the final diluted solution prepared by the final consumer. The concentrate is prepared as follows: 51 cc of water are poured into a suitable container did. Then O ₉ Qj cc of an anti-foam agent are poured into the solution. i cc of the surfactant

^009848/1649 UDOWW

Tergitol TMN and 0.225 Sipon ES are added. This is followed by 36 cc of 30% Alon dispersion added and the mixture mixed in the meantime · The anti-foam agent is advantageous Dow-Cornings-Anti-Foam-C. The mixture is stirred until uniform. The concentrate of about 0.085 l when ready to use is diluted with water to give a final amount of 3.785 l · This diluted end product is then ready to be sprayed or applied to the Glass or plastic surface

An alternative anti-foam agent is Dow-Comings B anti-foam or other silicone emulsion anti-foam agent. In the example given above, the appropriate amount of anti-foam is 0.05 cc to 0.25 cc, which is about 0.01 to 0.06 percent by volume of the final diluted solution is _0. The amount of surfactant can be from 2 cc to 20 cc, which is an amount of 0.052 to 0.5 percent by volume relative to the weight of the final diluted solution.

009848/1649

common in the amount of 0.01 % to 1 % · The dispersion of the alumina powder can be from 80 cc (not specified in the example) to 20 cc, which is an amount of 0.5 to 2.0% by volume of the final diluted solution although the amount can be from 0.2 % to k% .

0.085 l of the above concentration is diluted with water to a final volume of 3.785. This dilution is sprayed onto glass and plastic such as polyethylene and vinyl. 3.785 1 thinner can cover Tk up to 93 qm of the surface. In all cases the diluted agent dries to an invisible film

A greenhouse was made with the above

Dilution under high humidity conditions'

sprayed «The agent successfully prevented a drip · The water condensation was from the greenhouse surface away and down the walls · The greenhouse was then dried out and the humidity rose accordingly up

009848/1649

to a level equal to the humidity conditions under which the agent was initially sprayed. No reapplication of the diluted agent was necessary. The invisible film was effective again by removing the condensed moisture to prevent dripping.

It should be noted that another surface, for example made of styrene, acrylic acid, glass fiber, Plexiglas (TM) and also a metal surface can be processed, although the agent is intended for use on glass, polyethylene and vinyl ( Polyvinyl chloride) surface indicated was ₀

It should also be noted that the method of the invention can be used in conjunction with solar distillation system can be used · With a solar distillation system · sea water is in a container closed, which is covered at the top by a clear plastic film. The sea water is through the Sun rays heat, evaporate and leave behind

009848/1649

dissolved impurities such as salt · The evaporated moisture condenses on the inner surface the plastic film and drips down in many drops This makes the collection of the condensate difficult. According to the method of the invention, the plastic film surface with the means according to the Example treated The condensed moisture will now drain on the sides of the envelope where it will can be easily collected ·.

The method according to the invention results in an increase in light transmission and an increase in temperature. For example, tests have shown that in a plastic greenhouse or a solar distillation system an increase in light transmission of 50 % can be expected for some plastics under the same conditions. The increase in light transmission as a result of the method of the invention is important, for example when growing greenhouse crops

009848/1649

Claims (2)

202 A 1 claims 1. A method for preventing the formation of condensation on an inner surface of a casing which is exposed to high humidity, characterized in that a substance of 0.2 to k percent by volume of colloidal aluminum oxide, from 0.01 to 0, is used to form a layer , 5 percent by volume of an anionic or non-ionic surface »active agent and the rest of water is applied to the surface« 2. The method according to claim 1, characterized in that that the envelope is a greenhouse or a swimming pool hood and is mainly made of flexible or rigid plastic material. 3 «Method according to claim 1, characterized in that that the substance has 0.01 to 0.06 percent by volume of an anti-foam agent " 009848/1649 4β method according to claim 1, characterized in that that the surfactant is sodium lauryl ethyl sulfate with 3.5 mol of ethylene oxide and that the anti-foam agent is a silicone emulsion. 5. The method according to claim 1, characterized in that that the surfactant is a trimethyl _Λ nonyl ether of polyethylene glycol with 6 mol Is ethylene oxide and that the anti-foam agent is a silicone emulsion 6. The method according to claim 1, characterized in that that the agent is applied by spraying o 7 · The method according to claim I ₁ characterized that the envelope is a solar distillation system g is and the extracted moisture in an up «· collecting container is collected. 8. The method according to claim 1, characterized in that that the agent is applied with a heat above 71 ° C. . 009848/1649 A method according to claim 1, characterized in that the surface is heated above 71 ° C after the fabric applied and while it is still wet. 009848/1649