JPS60190444A - Hydrophilic-hydrophobic thermally reversible material - Google Patents

Abstract

PURPOSE:To provide a hydrophilic-hydrophobic thermally reversible material composed essentially of an aqueous solution of poly(acrylpiperidine), and having lower transition temperature than the know material. CONSTITUTION:The objective poly(acrylpiperidine) having a hydrophilic-hydrophobic transition temperature of 4-6 deg.C is prepared by irradiating acrylpiperidine or a proper solvent solution of acrylpiperidine with radiation, or by heating acrylpiperidine in the presence of a radical polymerization initiator. The intrinsic viscosity of the poly(acrylpiperidine) is preferably 0.01-6, espectially 0.1-3.

Description

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

Skating rinks, transparent walls in low-temperature warehouses, skylights for lighting, etc. can cause the internal temperature to rise more than necessary, except in winter, so in such cases, take some measure to block direct sunlight. This is desirable. Until now, such light shielding means has been carried out by covering a predetermined transparent part with a light shielding body such as a curtain, blind, or blind to shield the interior from direct sunlight. However, this method is cumbersome because it requires determining whether or not light blocking is necessary and then attaching or removing the light blocking body each time. Therefore, at low temperatures it allows light to pass through, but when the internal temperature rises,
If the transparent portion is formed of a temperature-sensitive material that does not transmit this, the above-mentioned troublesomeness can be eliminated.

The present inventors have conducted various studies to develop materials that meet these requirements, and have previously developed materials such as N-isopropylacrylamide, N-isopropylmethacrylamide, N-n-propylacrylamide, N-n-propylmethacrylamide, Polymers of N-cyclopropylacrylamide, N-cyclopropylmethacrylamide or N,N-diethylacrylamide are hydrophilic below a certain temperature;
Although the aqueous solution is transparent, they found that it becomes hydrophobic and opaque when the temperature rises above that temperature, and proposed that this property could be used to make it into a light-shielding material.

Not possible.

The present inventors continued their research to develop materials with different transition temperatures and an expanded range of applications for low-temperature storage. As a result, poly(acrylic piperidine) has a combination of hydrophilic and hydrophobic properties. It was discovered that scales constitute a temperature-sensitive material having a transition temperature of 4 to 6 DEG C., which is considerably lower than that of conventional materials, and based on this knowledge, the present invention was accomplished.

That is, the present invention provides a hydrophilic-hydrophobic thermoreversible material having a transition temperature of 4 to 6°C consisting essentially of an aqueous solution of poly(acrylic piperidine).

The poly(acrylic piperidine) used in the present invention is
For example, it is produced by irradiating acrylic piperidine alone or by dissolving it in a suitable solvent and heating it in the presence of a radical polymerization initiator. It undergoes a reversible hydrophilic-hydrophobic transition at a temperature of 4 to 6°C, and in differential scanning calorimetry in its aqueous solution,
．． It is characterized by an endothermic peak at 7°C.

Further, poly(acrylic piperidine) having an appropriate high molecular weight, for example, using chloroform, has a practical intrinsic viscosity of about 0.01 to 6.0 at 30°C, particularly 0.1 to 3. 0 is preferred.

The hydrophilic-hydrophobic thermoreversible material of the present invention requires preparing poly(acrylic piperidine) into a composition with water such as an aqueous solution. The concentration at this time varies depending on the purpose of use, but is usually selected in the range of 0.05 to 30% by weight.

The hydrophilic-hydrophobic thermoreversible material prepared in this way is widely used as a light-shielding material, water-soluble adhesive, coating material, dyeing agent, etc. by taking advantage of its temperature reversibility of light transmission. be done. 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. The material of the transparent plate-like body used at this time is as follows:
There is no particular restriction as long as it has the strength to withstand this (,
Any material can be selected from materials that have been widely used for transparent walls, windows, etc., such as glass and plastic.

The method of laminating the composition on this transparent plate-like body includes, for example, in the case of an aqueous solution or hydrogel, a method of encapsulating the composition between two transparent plate-like bodies, and in the case of a microcapsule,
There is a method of coating the surface of a transparent plate with a suitable binder.

The light-shielding material thus obtained is suitable as a transparent material for automatically preventing the indoor temperature of a low-temperature warehouse 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.

Reference Example 1 Put 50.98 ml of triethylamine and 450 ml of acetone into an 11-volume Erlenmeyer flask, cool the Erlenmeyer flask with ice to keep the content below 10°C, and add 41.5 ml of acrylic acid chloride to the flask while stirring. A mixed solution with 5QmJ of acetone was added to the dropping funnel to give a boiling point of 85.
A fraction of ~86 °C/1 mmT (g) was collected, yielding 41.6 g of a colorless and transparent liquid. In the mass spectrum of this substance, the parent peak was 138, which matched the molecular weight of acrylic piperidine, and the substance was confirmed. It was done.

Example: Put 4.99 g of acrylpiperidine obtained in the reference example, 20 WIl of benzene, and 0.2 g of azobisisobutyronitrile into an ampoule, perform vacuum degassing using liquid nitrogen to remove air, and then heat the upper part with a burner. Sealed.

This was heated at 70°C for 30 minutes to effect polymerization.

Next, the reaction solution in the ampoule was poured into a benzene-n-hexane mixed solution, and poly(acrylpiperidine) was precipitated and isolated to obtain 4.66 g of polymer.

The viscosity of the resulting polymer was measured using chloroform at a temperature of 30°C, and the intrinsic viscosity was found to be 0.19.

The obtained poly(acrylic piperidine) was dissolved in water to prepare a 1% by weight aqueous solution, and this aqueous solution was heated at a heating rate of 1°C.
5001 using a spectrophotometer while increasing the temperature at /min.
The transmittance of m was measured, and the relationship between the temperature of the aqueous solution and the transmittance was determined. The results are shown in FIG. 1 as a graph.

As is clear from this graph, poly(acrylpiperidine) in aqueous solution dissolves at low temperatures;
It can be seen that the precipitation starts from C, and the amount of precipitation increases rapidly as the temperature rises, and at 6° C., the transmittance at 5 Q Q nm becomes O, making it insoluble in water.

In addition, the obtained poly (acrylic piperidine) 3.2■
A sample was prepared by placing 59.11 V of water and 59.11 V of water in a sealed container made of 1 cum aluminum, covering the container with a sealed cell lid, and sealing the container with a sample sealer. The sample was subjected to calorimetric SC measurement using a differential scanning calorimeter at a heating rate of 1°C/min. The results are shown in FIG. Looking at this, the endothermic peak is about O''
A broad curve is drawn starting from C and ending at 15'C. The temperature at the top of this endothermic peak was 4.7°C. These results show that the poly(acrylpiperidine) aqueous solution has a transition temperature of 4 to 6°C.

[Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between the temperature and transmittance at 5 Q Q nm of a 1% by weight aqueous solution of poly(acrylic piperidine), and Figure 2 is a graph showing the DSC curve of an aqueous solution of poly(acrylic piperidine). be. Patent applicant Kawaguchi, Director of the Agency of Industrial Science and Technology] Hirobe (%) *
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Claims (1)

[Claims] (1) A hydrophilic-hydrophobic thermoreversible material with a transition temperature of 4 to 6°C consisting essentially of an aqueous solution of poly(acrylic piperidine).