Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Including a second component containing structurally defined...
Reexamination Certificate
1999-07-23
2001-10-23
Le, Hoa T. (Department: 1773)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Including a second component containing structurally defined...
C428S403000, C423S306000, C423S308000, C423S327100, C423S395000, C423S397000, C423S419100, C423S420200, C423S430000, C423S431000, C423S554000, C423S556000, C423S594120, C423S595000, C423S596000, C423S600000, C423S604000, C423S625000
Reexamination Certificate
active
06306494
ABSTRACT:
DETAILED DESCRIPTION OF THE INVENTION
Industrially Applicable Field
This invention relates to novel, fine particulate synthetic chalcoalumite compounds, process for their production, and heat insulator and agricultural film containing the fine particulate synthetic chalcoalumite compounds. The invention also relates to inorganic heat insulator which can impart to agricultural film excellent heat insulating property, ultraviolet and visible light transmission, mechanical strength and elongation, agricultural film containing the heat insulator, and processes for production thereof. More specifically, the invention relates to synthetic chalcoalumite compounds having average secondary particle diameter of not more than about 3 &mgr;m and BET specific surface area of not more than about 30 m
2
/g and/or the same synthetic chalcoalumite compounds which are surface treated; resin compositions containing them; and agricultural film provided by processing the resin compositions into film structure.
Prior Art
Agricultural films have been widely used for greenhouse cultivation or tunnel cultivation of agricultural products. Those agricultural films are required to concurrently exhibit transmittance and heat insulating property. That is, temperatures within a greenhouse or tunnel which are raised by the daytime sunbeams rapidly drop in night, in particular, fine weather night, due to radiational cooling. Such rapid temperature drop inside a greenhouse or tunnel incurs adverse effect on growth of crops.
For preventing such rapid temperature drop inside a greenhouse or tunnel, used is heat insulating film formed of a resin in which a material having infrared-absorbing ability, i.e., a heat insulator such as, for example, silica, silicate; hydroxide, oxide, aluminate, borate or sulfate of lithium, calcium, magnesium or aluminum; or a hydrotalcite compound, is blended.
We have earlier discovered that natural chalcoalumite compounds or those synthetic chalcoalumite compounds which are disclosed in Japanese Patent Kokai No. 1311/98 A have refractive indices close to those of thermoplastic resins used for agricultural film in general and exhibit excellent infrared absorbing ability over the broad infrared region of about 2.5-25 &mgr;m; and hence are useful as inorganic heat insulators. However, natural chalcoalumite compounds are not uniform in their particle diameters because of their natural origin, have large particle sizes and are difficult of acquisition. Also those synesthetic chalcoalumite compounds disclosed in Kokai 1311/98 A have large average secondary particle diameters and large BET specific surface area. Hence, when those natural or synthetic chalcoalumite compounds are blended in the film, they exhibit very poor dispersibility and develop white blisters, whereby impairing appearance of the film product and reducing its infrared absorbing ability, visible light transmission, mechanical strength and elongation. Thus, the compounds cannot be used as heat insulators for agricultural film.
Problems to be Solved by the Invention
The object of the present invention is to provide a heat insulator which exhibits good dispersibility in thermoplastic resins useful for agricultural film and hence does not form white blisters in film made from said resins, excells in infrared absorbing ability and ultraviolet and visible light transmission, and causes no reduction in mechanical strength and elongation of the film and the film containing said heat insulator.
Means to Solve the Problems
We have engaged in concentrative studies keeping the above problems in mind, to discover that agricultural film free of white blisters and free of reduction in infrared absorbing ability, ultraviolet and visible light transmission, mechanical strength and elongation could be provided by using synthetic chalcoalumite compound represented by the formula (1) below:
(M
1
2+
)
a−x
(M
2
2+
)
x
Al
3+
4
(OH)
b
(A
n−
)
c
. mH
2
O
(1)
(in which M
1
2+
stands for Zn
2+
or Cu
2+
,
M
2
2+
is at least one of divalent metal ion selected from Ni
2+
, Co
2+
, Cu
2+
, Zn
2+
and Mg
2+
,
a is 0.3<a <2.0 (provided M
1
and M
2
are not the same),
x is 0≦x<1.0, and x<a,
b is 10<b <14,
A
n−
is at least one selected from SO
4
2−
, HPO
4
2−
, CO
3
2−
, SO
3
2−
, HPO
3
2−
, NO
3
−
, H
2
PO
4
−
, Cl
−
, OH
−
and silicate ion,
c is 0.4<c <2.0 and
m is 0-4),
which has an average secondary particle diameter of not more than about 3 &mgr;m and a BET specific surface area of not more than about 30 m
2
/g; and/or the same synthetic chalcoalumite compound which has been surface treated, as the heat insulator in said agricultural film.
Such synthetic chalcoalumite compound having an average secondary particle diameter not more than about 3 &mgr;m and BET specific surface area of not more than about 30 m
2
/g can be prepared by a process comprising coprecipitating a water-soluble aluminium salt; a Zn and/or Cu compound which is water-soluble in the pH range of from about 4 to about 7, and if necessary one or more compounds of at least an element selected from Ni, Co and Mg which are water-soluble in the pH range of from about 4 to about 7, at a pH of from about 4 to about 7 and a temperature within a range of from about 10 to about 50° C.; filtering the coprecipitate, washing it with water and subjecting the so washed product to hydrothermal reaction in an aqueous solution of sulfuric acid salt of at least one element selected from Zn, Cu, Ni and Co at a concentration of at least 0.02 mol/liter, at temperatures ranging from about 80 to 170° C.
Embodiments of the Invention
This invention relates to synthetic chalcoalumite compounds having an average secondary particle diameter of not more than about 3 &mgr;m and BET specific surface area of not more than about 30 m
2
/g, which are represented by the formula (1) and can be prepared by the following process.
The process comprises the steps of coprecipitating a water-soluble aluminium salt; a Zn and/or Cu compound which is water-soluble in the pH range of from about 4 to about 7; and if necessary one or more compounds of at least an element selected from Ni, Co and Mg which are water-soluble in the pH range of from about 4 to about 7, at a pH of from about 4 to about 7 and at temperatures ranging from about 10° to 50° C., preferably from about 20 to 40° C.; filtering the coprecipitate and washing it with water; and then subjecting the washed product to hydrothermal reaction in an aqueous solution of sulfuric acid salt of at least one element selected from Zn, Ni, Cu and Co at a concentration of at least 0.02 mol/liter, preferably ranging from about 0.02 to 1 mol/liter, inter alia, from about 0.05 to 0.5 mol/liter, at temperatures ranging from about 80° to 170° C., preferably from about 100° to 150° C.
The characteristic feature of the synthesizing process of this invention lies in subjecting the coprecipitate obtained through the coprecipitation reaction which is recovered by filtration and washed with water, to the hydrothermal reaction in an aqueous solution of a sulfuric acid salt of at least an element selected from Zn, Cu, Ni and Co at a concentration of at least about 0.02 mol/liter, preferably about 0.02-1 mol/liter, inter alia about 0.05-0.5 mol/liter. When this method is used, the intended fine particulate, highly dispersible synthetic chalcoalumite compounds can be obtained because nearly no unnecessary ion is present at the time of crystal growth in the hydrothermal reaction.
Examples of starting materials for preparing the synthetic chalcoalumite compounds of the invention; i.e., water-soluble aluminium salt and Zn, Cu, Ni, Co and Mg compounds which are water-soluble in the pH range of from about 4 to 7 include:
aluminium compounds such as aluminium chloride, aluminium sulfate, aluminium nitrate and sodium aluminate;
zinc compounds such as zinc chloride, zinc nitrate,
Okada Akira
Takahashi Hideo
Kyowa Chemical Industry Co Ltd
Le Hoa T.
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