JPH07118439A - Microcapsule composition of lower cyclic alkane - Google Patents

Abstract

PURPOSE:To obtain the subject composition capable of substituting Flone(R), having low flammability and low explosive property and useful as a blowing agent for an urethane foam by capsulating a specific powder of a metal oxide carrying a lower cyclic alkane. CONSTITUTION:The objective composition is obtained by capsulating (C) porous micro powders of (B) inorganic or metal oxide carrying (A) a lower cyclic alkane with (D) a higher paraffin. Further, preferable conditions for the process are as follows. The component A is a 3-8C cyclic alkane, preferably cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane or cyclooctane. The component D is selected from paraffinic hydrocarbons having a melting point of 40-80 deg.C and a boiling point of >=300 deg.C. 100g of the component C can absorb 200-300mL of oil.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a microcapsule composition of a lower cyclic alkane and a method for producing the same. The microcapsule composition is useful as a foaming agent for urethane foam used as a heat insulating material instead of CFC.

[0002]

Urethane foam is used for various purposes, for example, as a heat insulating material inside the wall surface of an electric refrigerator. As a foaming agent for forming this urethane foam, a specific CFC such as CFC 11, CFC 12, CFC 113 or an improved CFC alternative is widely used at present. After forming the bubbles of the urethane foam, these freons fill the inside of the bubbles to enhance the heat insulating effect of the urethane foam. CFCs are non-flammable, non-explosive, non-toxic, chemically stable and do not corrode metals, and are therefore useful for applications such as foaming agents and refrigerants of the above heat insulating materials. However, in recent years, the ozone layer has been discovered over the Antarctic, and destruction of the ozone layer has become a problem, and the use of CFCs, which is the cause, is being regulated worldwide. Therefore, the development of CFC substitutes has become an urgent scientific issue.

The use of hydrocarbons as a substitute for CFCs is being studied mainly in Western Europe. For example, it has been attempted to use propane, butane, or lower cyclic alkanes as a foaming agent for urethane foam, which is a heat insulating material for refrigerators, but accidents such as ignition and explosion occur continuously during the manufacturing process, and There are many problems above.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional drawbacks, and its purpose is to substitute for CFCs and to be useful as a foaming agent for urethane foam and the like, which has a low flammability and an explosive property. The object is to provide a microcapsule composition of a substance, specifically, a lower cyclic alkane. Another object of the present invention is to provide a method for microencapsulating lower cyclic alkanes.

[0005]

The microcapsule composition of the present invention carries a lower cyclic alkane,
It is a composition in which a porous micropowder formed from an inorganic or metal oxide is encapsulated with higher paraffin.

The lower cyclic alkane used in the microcapsule composition of the present invention is preferably a cyclic alkane having 3 to 8 carbon atoms.
Examples thereof include cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane and cyclooctane.

The higher paraffin used in the present invention has a melting point of preferably 40 ° C to 80 ° C, more preferably 40 ° C.
It is a paraffin hydrocarbon having a boiling point of ~ 54 ° C and a boiling point of 300 ° C or higher. Paraffin hydrocarbons have the general formula C _n H _{2n + 2}
It is a saturated chain hydrocarbon represented by. Generally, carbon number n
The small (lower) paraffin hydrocarbons are gases at room temperature, the intermediate ones (n is about 5 to 15 in a straight chain compound) are liquids, and the higher paraffins with large n are solids at room temperature. The higher paraffin used in the present invention may be used alone or as a mixture of two or more paraffins. These paraffins are used by being dissolved in the lower cyclic alkane in the microcapsule composition manufacturing process. When paraffin having a melting point of 54 ° C. or higher, particularly 80 ° C. or higher is used, the solubility of the paraffin in the cyclic alkane becomes low, and when the melting point is 40 ° C. or lower, the rate at which the paraffin solidifies in the cooling step described later is slow. Therefore, the cyclic alkane to be encapsulated easily volatilizes, resulting in a large loss.

Examples of the inorganic or metal oxide forming the porous micropowder used in the present invention include silica (silicon oxide), iron oxide, copper oxide, zinc oxide, aluminum oxide, titanium oxide and zirconium oxide. . The porous micropowder used in the present invention is
The oil absorption amount per 100 g is preferably 100 to 500
ml, more preferably 200 ml to 300 ml of micropowder. In the present specification, "oil absorption" means
It represents the volume (ml) of the oily substance that can be carried by 100 g of the micropowder. This oil absorption is JIS K5101 19
It is measured according to. Oil absorption is 100 (ml / 100
g) In the following micropowder, the amount of the lower cyclic alkane supported in the pores of the micropowder is small and simply adheres to the outside of the micropowder.
Such micropowder is unsuitable for encapsulation. When the microcapsule composition of the present invention is used as a foaming agent for urethane foam, it is preferable that the particle size of the porous micropowder used is small in order to uniformly disperse the microcapsule composition. Preferably, the particle size of the micropowder is 0.5 μm to 1.8 μm. The porous micropowder used in the present invention is a gas phase method,
It can be obtained by any known method such as a liquid phase method.

The microcapsule composition of the present invention can be obtained by microencapsulating a lower cyclic alkane supported on a porous micropowder. The method for producing the microcapsule composition of the present invention comprises the steps of dissolving higher paraffin in a lower cyclic alkane, adding porous micropowder formed from an inorganic or metal oxide to the obtained solution, A step of supporting the solution on a powder, and a step of cooling the micropowder supporting the solution to −10 ° C. or lower to solidify the higher paraffin are included.

In order to prepare the composition of the present invention, first, the lower cyclic alkane to be encapsulated is used as a solvent, and the higher paraffin is dissolved therein at room temperature. If the melting point of the paraffin used at this time is higher than the above temperature range, the solubility in the cyclic alkane is low, which is not preferable. Higher paraffin is preferably used in a proportion of 20 to 60 parts by weight with respect to 100 parts by weight of the cyclic alkane. While stirring the mixed solution thus obtained,
A porous micropowder formed of an inorganic or metal oxide is put therein. The micropowder carries the mixed solution. As used herein, the expression that a micropowder “carries” a substance such as a solution means any mechanism by which the substance is retained by the powder, including absorption and adsorption of the solution by the powder. To do. Since the above micropowder carries the solution almost completely, the powder carrying the solution remains as a powder in appearance. The micropowder is preferably used in an amount of 20 to 60 parts by weight based on 100 parts by weight of the solution.

By rapidly cooling the solution-supported micropowder thus obtained to -10 ° C or lower, the higher paraffin in the mixed solution is solidified and a film is formed on the surface of the micropowder. The paraffin film encapsulates the porous micropowder supporting the lower cyclic alkane to obtain the microcapsule composition of the present invention. If the melting point of the paraffin used is lower than the above-mentioned temperature range, the rate at which the paraffin film is formed becomes slow in this cooling step, resulting in a large loss of the cyclic alkane, which is not preferable.

The microcapsule composition obtained as described above may be further double-coated. As coating material for the double coating, the same higher paraffins as used for the first microencapsulation can be used. In this case, the higher paraffin for double coating can be used by dissolving it in a solvent such as a cyclic alkane as in the case of using the above first encapsulation. In addition to the higher paraffin, liquid polypropylene glycol, polyvinyl alcohol, polyamide resin, etc. may be used as the double coating material. Double coating can be performed by further adding the double coating material as described above to the above microcapsule composition encapsulated with higher paraffin and stirring. The obtained double-coated microcapsule composition of the present invention may be in the form of powder or paste. Preferably, this double-coating material is 50 times its volume relative to the microcapsule composition to be double-coated.
Used in a volume of over%. This double coating can reduce the loss and risk of volatilization of the encapsulated cyclic alkane during storage. The obtained double-coated microcapsule composition can also be used as a foaming agent for urethane foam described later.

The lower cyclic alkane microencapsulated by the method of the present invention hardly volatilizes at room temperature, is stably held, and is easy to handle. For example, cyclopentane reaches an explosion point when it reaches a concentration of about 1.4% or more in air, and therefore the microencapsulation according to the method of the present invention reduces the risk during storage and during storage.

The microcapsule composition of the present invention is useful as a foaming agent when forming a urethane foam used as a heat insulating material or the like. The microcapsule composition of the present invention is used in the same manner as a usual foaming agent for urethane foam. For example, the microcapsule composition of the present invention is mixed and dispersed with polyether and isocyanate. Due to the exothermic reaction between the polyether and the isocyanate, the temperature rises to about 60 ° C to 130 ° C, and the higher paraffin in the film of the microcapsule composition melts. Then, the encapsulated lower cyclic alkane is vaporized and released from the porous micropowder. This vaporized cyclic alkane causes urethane to foam. In this way, a urethane foam is obtained, and the gas of the cyclic alkane is enclosed in the generated bubbles, so that the obtained urethane foam has a high heat insulating effect. Therefore, such urethane foam is useful as a heat insulating material inside the wall surface of a refrigerator. When used for such a purpose, a mixture of a urethane liquid, an isocyanate and a microcapsule composition may be injected into the wall surface in advance and reacted at that location to form a urethane foam.

[0015]

EXAMPLES The present invention will be described below based on examples. (Example 1) The components shown below were placed in a beaker, sealed, and stirred for 10 minutes. As a result, paraffin was completely dissolved.

[0016]

[Table 1]

50 g (particle size 1.8 μm) of porous silica powder (oil absorption amount 300 ml / 100 g) was added to this solution and stirred. The powder was in the form of powder and supported the above solution. The powder carrying this solution was put in a freezer at -20 ° C and rapidly cooled to solidify the paraffin to form a film.
The obtained microcapsule composition was sealed in a sealed container having a volume of 300 ml and left at room temperature, and then the cyclopentane concentration in the air in the container was measured by a gas detector (manufactured by New Cosmo).
It was 1.2% when measured by. At this concentration, the cyclopentane in the container reached equilibrium and no further increase in concentration was observed. 60 ℃ to 80 ℃ with this closed container
When heated to the range of, the paraffin was melted, cyclopentane was released from the microcapsule composition, and the cyclopentane concentration in the container was 2% to 6%.

(Example 2) A microcapsule composition was obtained in the same manner as in Example 1 except that the following components were used. When the obtained microcapsule composition is sealed in a closed container, the cyclopentane concentration is 0.5% at room temperature,
It was 2% to 6% at 60 ° C.

[0019]

[Table 2]

Example 3 To 100 parts by weight of the microcapsule composition obtained in Example 2, 7 parts by weight of the same paraffin cyclopentane solution as that used in Example 2 was used.
The microcapsule composition was double-coated by adding 2.425 parts by weight and stirring. In this step, cyclopentane in the double coating solution volatilized rapidly and did not remain in the microcapsule composition. The obtained double-coated microcapsule composition was closed in a closed container in the same manner as in Examples 1 and 2, and the cyclopentane concentration was measured. As a result, it was 0.01% or less at room temperature and 2 at 60 ° C to 80 ° C. % Or more.

Example 4 30 cm x 30 cm x 3
A nylon bag was put in a 0 cm wooden box to prevent urethane foam from adhering thereto, and 300 g of polyether (ACTCOL RL-13, manufactured by Takeda Chemical Industries, Ltd.) whose temperature was adjusted to 20 ° C. was put therein. The polyether used here is a polyether whose main component is polypropylene glycol having a molecular weight of about 2000. To this, 30 g of the microcapsule composition of the present invention obtained in Example 3 was added, and the mixture was stirred and uniformly dispersed. Toluene diisocyanate 3 here
When 0 g was added, the polyether and isocyanate reacted to generate heat, and the temperature reached about 80 ° C to 130 ° C. This reaction heat melted paraffin in the microcapsule composition, vaporized cyclopentane, and foamed urethane.
In about 30 seconds, a wooden box filled with urethane foam was formed and cured. When the cyclopentane concentration in the outside and the inside of the obtained urethane foam was measured by a gas detector, cyclopentane was not detected outside and was 2% to 6% inside. It was confirmed that cyclopentane was not released to the outside of this urethane foam but was enclosed in the urethane bubbles.

[0022]

INDUSTRIAL APPLICABILITY According to the present invention, a CFC alternative can be used,
A microcapsule composition of a lower cyclic alkane having low flammability and explosiveness, which is useful as a foaming agent for urethane foam, is obtained. Such a composition is useful for the preparation of various urethane foams, for example, urethane foams used as heat insulating materials inside refrigerator wall surfaces.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location // C08J 9/14 CFF 9268-4F C08L 75:04 (72) Inventor Shigeo Yoshida Yasu-cho, Yasu-gun, Shiga Prefecture 6 Oshinohara, Nakato Research Institute Co., Ltd.

Claims (10)

[Claims] 1. A porous micropowder formed from an inorganic or metal oxide, which carries a lower cyclic alkane,
A microcapsule composition encapsulated with high-grade paraffin. 2. The microcapsule composition according to claim 1, wherein the lower cyclic alkane is a cyclic alkane having 3 to 8 carbon atoms. 3. The microcapsule composition according to claim 2, wherein the cyclic alkane is at least one selected from the group consisting of cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, and cyclooctane. 4. The higher paraffin has a melting point of 40 ° C. to 80 ° C.
The microcapsule composition according to claim 1, which is at least one selected from paraffin hydrocarbons having a boiling point of 300 ° C or higher. 5. The microcapsule composition according to claim 1, wherein the amount of oil absorption per 100 g of the porous micropowder is 200 to 300 ml. 6. A method for producing a microcapsule composition by microencapsulating a lower cyclic alkane supported on a porous micropowder, wherein a higher paraffin is dissolved in the lower cyclic alkane.
A step of adding a porous micropowder formed of an inorganic or metal oxide to the obtained solution to support the solution on the porous micropowder; and the micropowder supporting the solution at -10 ° C or lower. Cooling and solidifying the higher paraffin. 7. The method according to claim 6, wherein the lower cyclic alkane is a cyclic alkane having 3 to 8 carbon atoms. 8. The method according to claim 7, wherein the cyclic alkane is at least one selected from the group consisting of cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, and cyclooctane. 9. The melting point of the higher paraffin is 40 ° C. to 80 ° C.
7. The method according to claim 6, which is at least one selected from paraffin hydrocarbons having a boiling point of 300 ° C. or higher. 10. 100 g of the porous micropowder
The oil absorption amount per unit is 200 to 300 ml.
The method described in.