Moisture-absorbing and desorbing polymer and compositions derived therefrom

Abstract

Disclosed herein is a moisture-absorbing and desorbing polymer, characterized in that, the said polymer is an organic high-molecular substance containing 1.0-8.0 meq / g of carboxyl group of a potassium type and having a cross-linking structure.

Description

[0001] The present invention relates to a moisture-absorbing and desorbing polymer having high moisture-absorbing and desorbing properties and particularly having high moisture-absorbing and desorbing rates and also relates to compositions containing the same.PRIOR ART[0002] With regard to a means for removing moisture in air, moisture absorbents such as lithium chloride, calcium chloride, magnesium chloride and phosphorus pentaoxide have been used. However, although such moisture absorbents have much moisture absorbing capacity and quick moisture absorbing rate, they are deliquescent and, therefore, there are disadvantages that they are liquefied after absorption of moisture and soil other substance, apt to be dissolved and difficult for their regeneration. Although other moisture absorbents such as silica gel, zeolite, sodium sulfate, active alumina and active carbon do not have such a problem, they have disadvantages that their moisture absorbing capacity is low, their moisture a...

AI Technical Summary

Benefits of technology

[0006] An object of the present invention is to offer a polymer having high moisture-absorbing and desorbing properties and being able to express such moisture-absorbing and desorbing properties within a short period or, in other words, a polymer having moisture-absorbing and desorbing rates and also to offer compositions containing the said polymer. The present inventor has carried out an intensive study concentrating to moisture-absorbing and desorbing properties or, especially, moisture-absorbing and desorbing rates of moisture-absorbing and desorbing materials. As a result, he has found that the type of the salt of a carboxyl group greatly affects the moisture-absorbing and desorbing rates and has been able to prepare an organic polymer having high moisture-absorbing and desorbing properties and exhibiting excellent moisture-absorbing and desorbing rates which have not been available up to now whereupon the present invention has been accomplished.MEANS FOR SOLVING THE PROLEMS

[0031] When the shape of the moisture-absorbing and desorbing polymer per se is fibrous, various processing to paper, nonwoven fabric, woven fabric, knitted product, processed fiber product, etc. can be easily conducted and the applicable use becomes wide whereby such a shape is useful. In the case of sheet, that is useful for the use as a filter which can be directly subjected to a processing such as corrugated paper.

[0032] When the moisture-absorbing and desorbing polymer of the present invention is made into a composition containing the same, its use spreads broadly. Especially when used as a processed product such as paper, nonwoven fabric, woven fabric, knitted product, sheet and foamed product, contacting area to gas is big and shape-holding property is good whereby it is useful as a material for moisture-absorbing and desorbing material. There is no particular limitation for the method for constituting them so far as the moisture-absorbing and desorbing polymer of the present invention is used and specific examples is that the form is constituted by the said polymer in a fibrous shape or the said polymer in particles is carried. However, in view of easy processing and low cost, good result is available when moisture-absorbing and desorbing polymer in particles is carried.

Problems solved by technology

However, although such moisture absorbents have much moisture absorbing capacity and quick moisture absorbing rate, they are deliquescent and, therefore, there are disadvantages that they are liquefied after absorption of moisture and soil other substance, apt to be dissolved and difficult for their regeneration.

Although other moisture absorbents such as silica gel, zeolite, sodium sulfate, active alumina and active carbon do not have such a problem, they have disadvantages that their moisture absorbing capacity is low, their moisture absorbing rate is slow, their regeneration require a high temperature and their repeated absorption and desorption of moisture result in pulverization which are causes that their practical use is disturbed.

However, in the case of such ultra water-absorbing resins, their water-absorbing property is very good but their moisture-absorbing property is not satisfactory.

The specific problems are that their retention of water is so high that desorption of moisture hardly occurs, an equilibrium moisture absorption capacity at low humidity is low, they become tacky with absorption of moisture and their moisture absorbing rate is slow.

However, slow moisture-absorbing and desorbing rates have been still pointed out as a problem.

However, the time necessary for moisture absorption is in a level of hours (in the Examples, a significant increase in moisture absorption is noted during ten hours) and such a method is not satisfactory for the use requiring the moisture absorbing rate in the level of minutes or even seconds such as a rotary dehumidifier.