JPH0512020B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a water-in-oil (hereinafter referred to as W/O) emulsion composition, and more particularly to a W/O emulsion composition that has excellent storage stability over a wide temperature range. [Prior Art] Conventionally, as cosmetics such as creams, milky lotions, and foundations, so-called W/O emulsion compositions, in which water particles are dispersed in oil, are generally used as oil-in-water type (hereinafter referred to as O/W) compositions. It is known that it has many characteristics compared to emulsified compositions, such as protecting the skin, imparting flexibility, and being difficult to remove when bathed in water. However, W/O emulsion compositions have the disadvantage of poor quality stability compared to O/W emulsion compositions. Separation of emulsified compositions generally occurs through creaming (or settling), agglomeration, and coalescence of emulsified particles. In W/O emulsion compositions, water droplets tend to aggregate at low temperatures, resulting in syneresis, in which the continuous oil phase tends to separate into the upper phase, while at high temperatures, water droplets coalesce and the particle size decreases. increases, and as a result, the water droplets settle, leaving only the oil phase in the upper phase, which tends to separate the oil phase. If the coalescence proceeds further, separation of the aqueous phase will occur. Therefore, it has been difficult to obtain a W/O emulsion composition that is stable over a wide temperature range. For example, POE3, a well-known W/O emulsifier.
W/O of paraffin oil emulsified using a low HLB lipophilic nonionic emulsifier having an ethylene oxide chain as a hydrophilic group such as oleyl ether
The emulsified composition is relatively stable at low temperatures, but tends to coalesce at high temperatures, and when stored at 50° C. for one month, it separates into two phases. Moreover, when olive oil was emulsified using this product, it became O/W, and a W/O emulsified composition could not be obtained. Japanese Patent Publication No. 48-15798 and Japanese Unexamined Patent Publication No. 55-31037 describe stable W/O emulsion compositions in which a fatty acid partial ester of a polyhydric alcohol is used as an emulsifier and a polyhydric alcohol is added thereto. ing.
However, when the present inventor actually prepared an emulsified composition of paraffin oil, it was found that the stability at high temperatures was improved, but the stability at low temperatures was poor, and water droplets agglomerated, resulting in separation of the oily composition. Ivy. Similarly, even when an olive oil emulsion composition was prepared at room temperature, particles coalesced within 10 days, the aqueous phase separated, and it was extremely unstable. Other emulsifiers for W/O emulsion compositions include:
Lipophilic substances with low HLB values, such as sorbitan fatty acid partial ester, polyoxyethylene sorbitan fatty acid partial ester, glycerin fatty acid partial ester, diglycerin fatty acid partial ester,
Polyoxyethylene sorbitol fatty acid partial esters, polyoxyethylene alkyl ethers, lanolin derivatives, etc. are generally known. but,
As shown in the example above, W/O emulsion compositions using these emulsifiers are relatively stable with respect to non-polar oils such as paraffin oil, but lack stability over a wide temperature range. Furthermore, with regard to polar oils such as olive oil, even the stability at room temperature was not satisfactory (see Comparative Examples below). [Means for Solving the Problems] Therefore, the present inventors improved the drawbacks of the prior art and created a W/O emulsion composition of polar oil that is extremely stable over a wide temperature range. As a result of intensive research to obtain the following general formula
The inventors have discovered that the above object can be achieved by using the propylene oxide/ethylene oxide adduct represented by (1), and have completed the present invention. [Means for solving the problem] That is, the present invention solves the problem by solving the general formula (1) (In the formula, a is an integer from 7 to 19, b is an integer from a+2, m
represents an average number of added moles of 5 to 30, and n represents an average number of added moles of 5 to 30. This is a water-in-oil emulsion composition containing a propylene oxide/ethylene oxide adduct represented by ) and a polar oil. Next, the configuration of the present invention will be described. The carbon number (a+b) of the alkyl group of the propylene oxide/ethylene oxide adduct represented by the above general formula (1) used in the present invention is 18 to 40, preferably 20 to 36. If a carbon number less than 18 is used, the stability will not be satisfactory. m is alcohol 1 having the above-mentioned branched alkyl group
It is the number of moles of propylene oxide added per mole. Therefore, the value of m actually represents the average value of a distribution. Similarly, n is alcohol 1
It is the number of moles of ethylene oxide added per mole and also represents an average value. If m is 4 or less, the effect produced by adding propylene oxide will not be exhibited. n represents a number from 5 to 30, and conventional ethylene oxide addition type W/
It takes a larger value than the value for the O emulsifier (n=1 to 5). In conventional emulsifiers to which ethylene oxide is added, if the number of moles of ethylene oxide added is 5 to 30, an O/W emulsion composition is usually obtained, and a W/O emulsion composition cannot be prepared, or even if it can be made. Although it is very unstable, a propylene oxide chain exists in the propylene oxide/ethylene oxide adduct of the present invention,
And since the alkyl group is branched, W/O
It is believed that an emulsified composition can be obtained and stability is improved. Preferred specific examples of propylene oxide/ethylene oxide adducts include polyoxyethylene (15)
Polyoxypropylene (8)-2-tetradecyl-octadecyl ether, polyoxyethylene (10) polyoxypropylene (20)-2-decyl-tetradecyl ether, polyoxyethylene (8) polyoxypropylene-2-octyl-dodecyl Ether etc. can be mentioned. One or more types of propylene oxide/ethylene oxide adducts are arbitrarily selected and used,
Its blending amount is 0.1 to 20% of the total amount of W/O emulsion composition.
% by weight, preferably 0.5-5% by weight. If the amount is less than 0.1% by weight, it is difficult to stabilize the W/O emulsion composition. As the polar oil of the W/O emulsion composition of the present invention,
Natural animal and vegetable oils and fats such as olive oil, camellia oil, soybean oil, macadamia nut oil, castor oil, lanolin, carnauba wax, yellowtail wax, spermaceti wax, beeswax, jojoba oil, waxes, fatty acids with 10 to 35 carbon atoms,
Alcohols having 10 to 35 carbon atoms, synthesized esters having 16 or more carbon atoms, such as isopropyl myristate, isostearic acid diglyceride, 2
- Ethylhexanoic acid triglyceride, diisostearyl malate, myristyl myristate, etc. can be used. In addition to the propylene oxide adduct, polar oil, and water as essential components, the W/O emulsion composition of the present invention may optionally contain other surfactants, non-polar oils such as paraffin oil, squalane, paraffin wax, and ceresin. , moisturizers, dyes, pigments, ultraviolet absorbers, fragrances,
Medicinal agents, preservatives, antioxidants, etc. can be added as appropriate. In order to further understand the present invention, Examples and Comparative Examples are listed below. All parts in the examples are expressed by weight. Examples 1 to 8 The following components were heated to 70°C, stirred and mixed, and then emulsified to prepare a W/O emulsion composition. After preparation, the emulsion type was confirmed by electrical conductivity, and the emulsion particle size was observed using a microscope. Also stored at each temperature for 15 days,
The stability was investigated based on the state of separation and changes in particle size. The results are shown in Table 1. (Composition) Oil 47 (parts) Emulsifier 3 Water 50 For comparison, conventional W/O with the same composition as the example
Emulsified compositions were similarly prepared using an emulsifier, and their emulsion type, particle size, and stability were investigated (Comparative Examples 1 to 1).
Ten). The results are shown in Table 2.

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〔Effect of the invention〕

The W/O emulsion composition of the present invention has extremely good storage safety over a wide temperature range compared to conventional compositions. In particular, it has become possible to prepare polar oils such as triglyceride, which is a sebum-like component that could not be incorporated even if one wanted to, into an extremely stable W/O emulsion composition due to lack of stability even at room temperature. . Furthermore, when obtaining a non-flowable cream or stick-like W/O emulsion composition, it is essential to add solid waxes.
According to the present invention, not only hydrocarbon wax but also
Polar waxes such as wood wax, carnauba wax, candelilla wax, and spermaceti wax can also be added without impairing the stability of the emulsion. Furthermore, the emulsion composition according to the present invention has very good stability, so that it is possible to obtain a stable w/O emulsion with a very high internal phase ratio, which has been difficult with the prior art.

Claims (1)

[Claims] 1 General formula (1) (In the formula, a is an integer from 7 to 19, b is an integer from a+2, m
represents an average number of added moles of 5 to 30, and n represents an average number of added moles of 5 to 30. A water-in-oil emulsion composition containing a propylene oxide/ethylene oxide adduct represented by ) and a polar oil.