JPS58179256A - Thermally reversible material between hydrophilic and hydrophobic - Google Patents

Abstract

PURPOSE:To provide the titled material composed of an aqueous solution of poly(N-n-propylacrylamide) having low transition temperature between hydrophilic and hydrophobic, and widely useful as a light-shielding material, coating material, etc. taking advantage of the temperature reversibility of light transmission. CONSTITUTION:Poly(N-n-propylacrylamide) which changes reversibly from hydrophilic to hydrophobic at 16-19 deg.C, is prepared by irradiating (a solution of) N-n-propylacrylamide with radiation or by heating in the presence of a radical polymerization initaitor. The polymer is dissolved in water at a concentration of 0.05-10wt%. When the material is used as the aqueous solution or is laminated to a transparent plate in the form of a hydrogel or microcapsule, and heated at or above the transition temperature, the polymer is changed to hydrophobic and opaque. Accordingly, the mateiral can be used as a light- shielding material for automatically preventing the unnecessary increase of the room temperature with direct sunlight.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel hydrophilic-hydrophobic thermoreversible material.

Transparent walls such as greenhouses, frames, show windows, and skylights for lighting in houses and factories can cause the internal temperature to rise more than necessary under the scorching sun in summer, so in such cases, It is necessary to block direct sunlight by some means. In this device 1, the light shielding means used was to cover a predetermined transparent portion with a light shielding body such as a curtain, blind, or blind to shield the interior from direct sunlight.

However, such a method is cumbersome in that it is necessary to determine whether or not light shielding is necessary, and then to install or remove the entire light shield each time.

Therefore, when the sunlight is weak, the light passes through well, but when the sunlight is stronger than necessary and the internal temperature rises, it is possible to form a transparent part with a temperature-sensitive material that does not allow the light to pass through. , the above-mentioned troublesomeness can be eliminated.

The inventor of the present invention has conducted various researches to develop materials for such a demanding industry.
It was discovered that it is hydrophilic and its aqueous solution is transparent below a certain temperature, but it becomes hydrophobic and becomes opaque when the temperature rises above a certain temperature, and this property can be used to make a light-shielding material. I suggested that.

However, since the polymer of N-isopropylacrylamide or N-isopropyl methacrylamide has a high transition temperature between hydrophilicity and hydrophobicity of about 29 to 44°C, its range of use is considerably limited. do not have.

The present inventors continued their research to develop a material with an even lower transition temperature and a wider range of applications. As a result, poly(N-n-propylacrylamide) has a combination of heptophilicity and hydrophobicity. It has been discovered that the transition temperature is as low as 16 to 19 DEG C., making it a much more useful temperature-sensitive H charge structure than conventional ones, and based on this knowledge, the present invention has been accomplished.

That is, the present invention provides a hydrophilic-hydrophobic thermoreversible mold material PI having a transition temperature of 16 to 19[deg.] C., which consists essentially of an aqueous solution of N-(n-propylacrylamide).

N-(,n-propylacrylamide) used in the present invention can be obtained by, for example, treating N-n-propylacrylamide alone or by dissolving it in an appropriate solvent and irradiating it with radiation.
Alternatively, it is produced by heating in the presence of a radical polymerization initiator. This material undergoes a reversible lignophilic-hydrophobic transition at a temperature of 16 to 19°C, and exhibits an endothermic peak at 16.5°C in differential scanning calorimetry in an aqueous solution. . Further, the intrinsic viscosity at 30°C is in the range of 0.01 to 6.0, preferably 0.1 to 3.0.

The hydrophilic-hydrophobic thermoreversible material of the present invention is poly(N-n
-Propylacrylamide] must be prepared in the form of a composition with water, such as an aqueous solution.

The concentration at this time varies depending on the purpose of use, but is usually 0.0
It is selected within the range of 5 to 10% by weight.

The hydrophilic-hydrophobic thermoreversible material prepared in this way can be used in a wide range of applications such as light-shielding materials, water-soluble adhesives, coating materials, and dyes by taking full advantage of its temperature-reversible properties regarding light transmission. used. For example, the hydrophilic-hydrophobic thermoreversible material of the present invention is laminated on a transparent plate-like body in the form of an aqueous solution, or in the form of a hydrogel or microcapsule. There are no particular restrictions on the material of the transparent plate-like body used in this case, as long as it has enough strength to withstand the desired use.
Any material can be selected from among the materials used for transparent walls, windows, etc., such as glass and plastic.

For example, in the case of an aqueous solution or hydrogel, a method of encapsulating TLF between two transparent plate-like bodies is used, and in the case of microcapsules, a suitable binder is used to laminate the aggregate on this transparent plate-like body. The method of applying the coating to the surface of a transparent plate-like object will be explained.

The thus obtained light-shielding material f' is suitable as a transparent material for automatically preventing the room temperature from increasing more than necessary due to direct sunlight, for example.

Next, the present invention will be explained in more detail with reference to Examples. .

Add 58.9 ml of triethylamine to a wing angle flask containing Reference Example 1.
, n-propylamine (CHllCI(2CH2NH) 25.'61 and benzene 350m7!'((input n5
Cool the flask with ice to keep the content below 10°C, and add 35% of acrylic acid chloride to the flask while stirring.
A mixed solution of - and 155+++ g of benzene was slowly added dropwise from the dropping funnel over about 3 hours. After completion of the dropwise addition, the reaction solution was placed in a refrigerator and cooled for one day and night, then filtered, and the filtrate was concentrated to remove benzene using a rotary evaporator. Then, it is distilled under reduced pressure to a boiling point of 102℃/
A 1 mm Hg fraction was collected and a colorless transparent liquid 402
Total gain fc. In this mass spectrum, the parent peak is 113
corresponds to the molecular weight of N-n-propylacrylamide,
The substance was confirmed.

7HN-n-propylacrylamide 5- obtained in Example Reference Example
and acetone 15- were placed in an ampoule and all air was removed by vacuum degassing using n1 liquid nitrogen, and the upper part was sealed with a burner. In this case, r-rays from cobalt-60 are applied at a temperature of 2
Polymerization was carried out at 8° C. and irradiated for 40.8 hours at a dose of 1,5×to4 or less.

Next, the entire reaction solution in the ampoule was poured into diethyl ether, and polyN-n-propylacrylamide was precipitated and isolated to obtain a total of 2.57 polymers.

The viscosity of the obtained Am polymer was measured using an Ubbelohde viscometer at a temperature of 30°C, and the intrinsic viscosity [η] of 7 was 020.
There was ``'C.

The obtained nJcN-n-propylacrylamide was dissolved in water to prepare a 1% by weight aqueous solution, and the total layer temperature rate of this aqueous solution was 1.
500 using a spectrophotometer 4 while increasing the temperature at °C/mjn.
The light transmittance in nm was measured, and the relationship between the temperature of the aqueous solution and the light transmittance was determined. The results are shown in FIG. 1 as a graph.

As is clear from this graph, poly(N-
Although n-propylacrylamide is kept in a low temperature range, it begins to precipitate at 17°C, and the amount of precipitation increases rapidly as the temperature rises, and at 19°C, the light transmittance becomes 0 and it becomes insoluble in water. .

Also, poly(N-n-propylacrylamide) 40m
g and y 11.5 m? 'c The anus was placed in a sealed aluminum container, covered with a sealed cell lid, and sealed with a sample roller. Full sample differential scanning calorimeter? Using, heating rate fl
Calorimetry was carried out at 1° C./min and the results are shown in FIG. Looking at this t''L, the endothermic peak starts from the temperature of about 1θ℃ and shows a broad curve at about 23℃.The peak top of this endothermic peak.If you calculate the temperature,
．． The temperature was 5°C. Further, the amount of heat of transition (ΔH) determined from the area of the endothermic peak of the sample was 8.520 al/r. From the measured light transmittance and differential scanning calorific value, poly(N-
n-propylacrylamide) aqueous solution at 16-18°C
It can be seen that it has a transition temperature of .

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between temperature and light transmittance of an aqueous solution of the polymer of the present invention, and FIG. 2 is a graph showing the relationship between temperature and amount of heat. Police applicant Makoto Ishizaka, Director-General of the Agency of Industrial Science and Technology - Government Office
Procedures Procedures Amendment Book June 25, 1980 L Display of the case Showa 7 Patent application 9554880@2 Title of the invention Hydrophilic-Hydrophobic thermoreversible material & Person making the amendment Relationship to the case Patent application 1-3-1 Kasumigaseki, Chiyoda-ku, Tokyo (l l 4) Director of the Agency of Industrial Science and Technology Kawa 1) Hirobemoto Designated Agent Voluntary (1) I9J Specification Page 7 lI 2nd line ``Obtained summer - n -Propylacrylamide" will be corrected to "Original limit (M-mk-Propylacrylamide)"1.

Claims (1)

[Claims] ■ Wood-loving material with a transition temperature of 16 to 19°C consisting essentially of an aqueous solution of poly(N-n-propylacrylamide).
Hydrophobic thermoreversible material.