JPS62215638A - Porous polyamide powder - Google Patents

Abstract

PURPOSE:Porous spherical powder, having a great pore volume and specific surface area and remarkable absorption and holding ability for various solvents and oily materials and particularly suitable as a base for cosmetics, etc. CONSTITUTION:Spherical porous polyamide powder, obtained by dissolving a polyamide resin in, e.g. a lower alcoholic solvent, e.g. methanol, etc., containing an anhydrous chloride of an alkaline earth metal, e.g. anhydrous calcium chloride, etc., while heating, slowly cooling the solution, separating deposited polyamide particles from the solvent, washing the separated particles with water, and drying the washed particles, etc., having >=0.25cc/g, preferably 0.25-1.5cc/g total pore volume, >=4m<2>/g, preferably 4-30m<2>/g specific surface area and 2-200mum particle diameter when used as a cosmetic base and 10-100mum particle diameter when used as a powder coating material.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to spherical porous polyamide powder.

[Prior art J: Problems with it] Conventionally, polyamide powder has been used in powder coatings, powder molded products,
Although it is widely used as a material for adsorbents and the like, in recent years, polyamide powder has been increasingly used as a base for cosmetics, especially for makeup.

This takes advantage of the characteristics of polyamide powder, which is harmless to the human body, and because the refractive index of light is similar to that of polyamide resin and sweat, the entire face shines evenly and gives a glossy glow to the skin. . In particular, polyamide powders have been developed in which each particle is spherical to improve slippage and feel.

Methods for producing such polyamide powder include, for example, Japanese Patent Publication No. 48-24812 and Japanese Patent Application Laid-Open No. 58-2192.
There is a method disclosed in No. 40. Each particle of polyamide powder obtained by these methods has a shape close to a true sphere, and its surface is smooth with almost no irregularities. Therefore, each particle itself has almost no adsorption capacity, and the absorption capacity of the powder as a whole is extremely low.

Generally, in the process of manufacturing paste cosmetics or semi-solid cosmetics, when kneading each component of the cosmetic with oil, it is easier to knead the more oil it contains.

However, if this oil remains in the cosmetic product as it is, the face with makeup will look greasy and the person wearing the makeup will feel sticky and uncomfortable.

When using the aforementioned perfectly spherical polyamide powder as a base for cosmetics, the powder itself has almost no absorbency;
In order to absorb excess oil, it is necessary to separately mix inorganic adsorbents, inorganic fibers, etc. These inorganic adsorbents and inorganic fibers must be selected in a shape and PH that are comfortable to the touch and do not cause skin irritation, and there are factors that cannot be ignored, such as pressure on manufacturing costs and time and effort in the manufacturing process.

As a result of intensive research to solve the drawbacks of the polyamide powder having a true spherical shape, the present inventors found that each particle itself is porous and has excellent absorption capacity, and the total pore volume is large. Moreover, we succeeded in obtaining polyamide powder with a large specific surface area.

[Means and effects for solving the problems] The present invention has the following features:
The total pore volume is 0.25 cc/g or more, and the specific surface area is 4.
0112/G or higher and is characterized by being spherical.

Here, the total pore volume refers to the total volume of pores present in powder particles per gram of polyamide powder, and can serve as a barometer indicating the degree of porosity of the powder. Therefore, when the total pore volume and specific surface area are large, the powder particles have a large ability to accommodate other substances and, in turn, have excellent absorption capacity.

For comparison, the total pore volume of commercially available polyamide powder (nylon powder manufactured by Toshi Co., Ltd.) was measured to be 0.14 cc10, and the specific surface area was 1.24 m2/g, and its absorption capacity was It is about 1/3 to 1/2 of the absorption capacity of the polyamide powder of the invention. Similarly, the total pore volume of organosol (nylon powder manufactured by Atochemi) is 0.24 CC/CI and the specific surface area is 3.4010210.
The absorption capacity is about 1/1 of that of the polyamide powder of the present invention.
It is 2.

As mentioned above, the larger the total pore volume and specific surface area, the more
The greater the degree of porosity of the powder, the greater its absorption capacity, but if the degree of porosity becomes too great, the powder will have poor mechanical strength and may break during handling. Therefore, in order to exhibit excellent absorption capacity without impairing its mechanical strength, the total pore volume of polyamide powder should be adjusted to 0.25 to 1.50 cc/
g, and the specific surface area is preferably 4.0 to 30.0 m2/g.

As described above, the porous polyamide powder of the present invention has the above-mentioned specific properties that were completely unknown heretofore. Therefore, when this is used as a base for cosmetics, it absorbs the excess oil that occurs during cross-contamination, so that the product cosmetics are not sticky and give a rough texture.

In addition, in this specification, the total pore volume and specific surface area of polyamide powder each mean a value measured by the following method.

(Total pore volume W1) This is a value measured by Bore Sizer 9310 manufactured by Shimadzu Corporation by a mercury intrusion method.

The principle of this measurement method is simply as follows.

That is, when the sample cell containing the polyamide powder to be measured is evacuated and mercury is injected, then pressure is applied to the mercury. Since the mercury level decreases by the volume of
The volume of the pores is determined by reading the change in the amount of mercury before and after this pressurization.

The contact angle of mercury for most substances is between 90' and 180'.
°, which indicates that mercury does not wet the substance. Therefore, in order for mercury to penetrate into the pores, it is necessary to apply pressure, and the relationship between the pressure applied to mercury and the minimum pore diameter through which mercury can penetrate is shown by the following equation. be.

P-[)cC-4δcosθ (Washburn
(Formula) Here, P is the applied pressure, DG is the pore diameter, δ is the surface tension of mercury, and θ is the contact angle of mercury with the sample.

As shown in the above equation, the pressure applied to mercury is inversely proportional to the pore size through which mercury can penetrate, and the greater the pressure applied, the more fine pores can be penetrated.

Furthermore, the amount of mercury that has entered the pores due to pressurization can be determined from the displacement of the mercury surface in the cell, and the amount of mercury intruded into the cell is the pore volume that is determined.

However, what was observed with this method was that the mercury level decrease due to pressurization appeared in three stages. That is, when mercury starts to be pressurized, (A) first, mercury invades the voids created by the alignment of powder particles, and (B)
Next, mercury enters into the voids between the aligned particles, and (C) finally, mercury enters into the pores on the particle surface. Therefore, (C
) The mercury haze that decreased to 30 OOpsia under pressure conditions at step ) was taken to represent the pore volume of the powder defined in the present invention. And the total pore volume of this powder (
CC) per 1 kg of polyamide powder is the total pore volume (cc/g) defined in the present invention.

(Specific surface area) Determined by nitrogen adsorption method. 6. Polyamide powder to be measured
Use one that has been dried at 0'C for 10 minutes.

Although the particle diameter of the polyamide powder of the present invention is not particularly limited, it is preferably 2 to 20 μm when used as a base for cosmetics. Moreover, when used as a powder coating, it is preferable that it is 10-100 micrometers.

Examples of the method for producing the porous polyamide powder of the present invention include the following polyamide resin reprecipitation method.

(1) A method in which a polyamide resin is heated and dissolved in a lower alcohol solvent containing an anhydrous chloride of an alkaline earth metal, and then slowly cooled.

(2) A method in which polyamide resin, calcium chloride, and water are heated and dissolved in methanol together with ethylene glycol or glycerin, and then cooled.

<3> A method in which polyamide resin is heated and dissolved in ethylene glycol containing calcium chloride and then cooled.

In either case, the polyamide particles precipitated by cooling are separated from the solvent, washed with water, and then dried.
It contains 1 q of porous polyamide powder of the present invention.

Any polyamide resin may be used in the present invention, and examples thereof include nylon 6, nylon 12, nylon 66, and nylon 610.

[Example] Next, the present invention will be described in detail in Examples.

Example 1 Nylon 12 (manufactured by Ube Industries, Ltd., molecular weight 20.00
0) 0.9 kg, anhydrous calcium chloride 2.7 ka and methanol 15.3 kQ were placed in an autoclave with a volume constant of 25λ, the atmosphere was replaced with nitrogen, and the temperature was raised to 136°C while stirring the contents to dissolve the polymer. It was slowly cooled at a rate of 10° C./Hr while rotating at 500 revolutions per minute. The precipitate was suction filtered to separate the solvent, washed with water, and then dried under reduced pressure to obtain a powder consisting of porous spherical particles with an average particle size of 12 to 13 μm.

FIGS. 1 and 2 show electron micrographs of this polyamide powder.

The total pore volume of this polyamide powder is determined by Shima tlF Co., Ltd.
0.64cc when measured with Pore Sizer 9310 manufactured by J Seisakusho
/g. Figure 3 shows the measurement chart at that time, and the measurement curve of the polyamide powder of this example is 1
It is.

In this chart, the horizontal axis indicates the pore diameter (μm), and the pore diameter becomes smaller as it goes from the right side to the left side of the figure. The vertical axis indicates the cumulative pore volume (cclo), which represents the total intrusion 1 (cc) of mercury from the start of pressurization to the end of pressurization for sample powder 1Q.

In the measurement curve 1 of the polyamide powder of this example, point A indicates the point at which pressurization starts, and from there the pressurization progresses as it moves to the left, passing through inflection point 8 and C, pressurization is applied at the point. ends. Between the pressure start point A and the inflection point B, the powder particles are aligned in a close-packed manner due to the pressure.
Mercury enters the voids created by this. A remarkable rise is seen between the inflection point B and the inflection point C, which indicates that mercury enters the voids between the powder particles in the closest packed state.

At the point of inflection C, the voids between the powder particles are filled with mercury, so if the pressure is continued further, mercury begins to enter the pores on the powder surface. Therefore, between the inflection point C and the end point of pressurization, mercury actually enters the pores on the surface of the powder particles themselves, and the value on the vertical axis of the end point of pressurization (
In other words, the value obtained by subtracting the value on the vertical axis of the inflection point C from the integrated pore volume indicates the true total pore volume.

Regarding the polyamide powder of this example, the cumulative pore volume at the end point of pressure and at the inflection point C was 2.57, respectively.
22cc/IJ and 1.9351cc,'Q, and the difference between them, 0.6371cc10, is the total pore volume of the polyamide powder.

Example 2 Nylon 6 (manufactured by Ube Industries, Ltd., molecular weight 13.000
) 1.8 kg, calcium chloride dihydrate 3.6 kg (calcium chloride purity 2.7 + water 0.9 kg), glycerin 3.8 kg, water 1.8 klll, and methanol 8.
8ko to fi25J? The autoclave was purged with nitrogen, and the contents were heated to 136° C. while stirring to dissolve the polymer, and then cooled at a rate of decline of 50° C./Hr.

The precipitate was suction filtered to separate the solvent, washed with water, and then dried under reduced pressure to obtain a powder consisting of porous spherical particles with an average particle size of 8 to 10 μl.

FIG. 4 shows an electron micrograph of this polyamide powder.

The total pore volume of this polyamide powder was measured using Bore Sizer 9310 manufactured by Shimadzu Corporation in the same manner as in Example 1, and was found to be 0.28 cc/g.

The fifth factor shows the measurement chart at that time, and Δ' and B in measurement curve 2 of the polyamide powder of this example.
', C' and D' are A in measurement curve 1 of FIG.
, 8. Corresponding to C and D, respectively.

Therefore, in this case as well, the true total pore volume is the pressure end point D'
The difference between the cumulative pore volume at 1.7337cc/Q and the V4 calculated pore volume at the inflection point C', 1°4494cc/Q, is 0.2843CC/! It is J.

Comparative Example 1 An electron micrograph of a commercially available polyamide powder (Nylon Powder manufactured by Tanishi Co., Ltd.) is shown in FIG.

The total pore volume of this polyamide powder was measured in the same manner as in Examples 1 and 2, and was found to be 0.14 cc/g. 3 in Figure 3 is the measurement curve at that time, alb, c
and d correspond to A, B, C, and D in measurement time 11, respectively. Therefore, the true total pore volume is 0.1413 cc/g, which is the difference between the cumulative pore volume at pressure end point d, 1.0044 cc/g, and the cumulative pore volume at inflection point C, 0.8631 cc/Q. .

Comparative Example 2 "Organosol" (commercially available polyamide powder)
Fig. 7 shows an electron micrograph of nylon powder manufactured by Atochemi Co., Ltd.

The total pore volume of this polyamide powder was measured in the same manner as Comparative Example 1, and was found to be 0.24 cc/g. 4 in Figure 3 is the measurement curve at that time, a', b', C' and d
′ correspond to A, B, C, and D in measurement curve 1, respectively.

Therefore, the true total pore volume is 0.0 of the difference between the integrated pore volume 11.30.41 cc/g at the pressure end point d' and the integrated pore volume 1.0621 cc/9 at the inflection point C'. 242
It is 0cc/g.

Table 1 shows the measured values of total pore volume, specific surface area, particle diameter, and bulk specific gravity for each of the polyamide powders of Example 1.2 and Comparative Example 1.2. The value of total pore volume is
It was measured using the method described above. The specific surface area is a value measured using 70-SOAP 2300 manufactured by Shimadzu Corporation after drying the polyamide powder to be measured at 60° C. for 10 minutes. The particle diameter is a value read from a reference line using an electron microscope, and indicates the values of the smallest particle and the largest particle. The bulk specific gravity is a value measured according to JISK5101 ('50).

(The following is a blank space) Table 1 Next, the ability to absorb and retain various solvents and oily substances was measured for each of the polyamide powders of Example 1.2 and Comparative Example 1.2.

The absorption capacity of polyamide powder was determined as follows.

(1) Put a predetermined amount of dry polyamide powder into a test tube, add an excess of solvent or oil, and allow the test tube to be fully immersed.

(2) Next, this is separated into an upper liquid and an impregnated powder using a centrifugal valve mi.

(3) Find the difference between Ila (g) of the impregnated powder and the weight (9) of the original dry polyamide powder, and calculate this difference by absorbing fjl (a
), and the ratio (Q 2 /g) between this absorption ff1 ((J) and txfIi ((+ >) of the original dry polyamide powder is calculated.

Impregnated polyamide powder has a solvent or oily substance in the voids between powder particles and in the pores of powder particles, and the ratio of the above-mentioned absorption amount to dry powder weight (absorption amount/dry powder weight) is large. It can be said that the powder has a greater absorption capacity.

Table 2 shows the measured ratios of absorbed amounts and dry powder weights for various solvents.

(The following is a blank space) Table 2 The solvent retention ability of the polyamide powder was determined as follows.

(1) Disperse 2 g of polyamide powder in 10 mR of various solvents.

(2) Next, this is suction filtered using a glass filter (G3). Suction is performed for 10 minutes using a handheld aspirator.

(3) Calculate the ratio between the weight of the solvent II absorbed in this suction-filtered polyamide powder and the weight of the original dry polyamide powder.

It can be said that the larger this ratio (solvent mfi/dry powder weight) is, the greater the solvent holding capacity of the powder is.

Table 3 shows the measured weight ratios of solvent and dry powder for various solvents.

(Left below) Table 3 As is clear from Tables 1, 2, and 3, the polyamide powder of the present invention has a much larger total pore volume than conventional polyamide powders. Due to its properties, it has remarkable ability to absorb and retain solvents, etc.

[Effects of the Invention] As described above, the polyamide powder of the present invention has a remarkable ability to absorb and retain various solvents and oily substances. Therefore, when the polyamide powder of the present invention is used as a cosmetic base, the powder itself absorbs the excess oil added during kneading, so there is no need to separately mix inorganic adsorbents, inorganic fibers, etc. The manufacturing process can be simplified and manufacturing costs can be reduced. The feel of the cosmetic product is also very favorable.

It can also be advantageously used as an additive for resin molding materials, an additive for lubricants, a column filler for liquid additives, an adsorbent for food-related oils, powder coatings, and other adhesives.

[Brief explanation of drawings]

FIGS. 1 and 2 are electron micrographs showing the particle structure of an example of the porous polyamide powder of the present invention. FIG. 3 is an electron micrograph showing the particle structure of an example of the porous polyamide powder of the present invention and a polyamide for comparison. A characteristic diagram showing the relationship between the pore diameter and the calculated pore volume of the powder. FIG. 4 is an electron micrograph showing the particle structure of another example of the porous polyamide powder of the present invention. FIG. , a characteristic diagram showing the relationship between pore diameter and integrated pore volume of other examples of porous polyamide powder of the present invention, FIG. 6 is an electron micrograph showing the particle structure of polyamide powder for comparison, FIG. 7 is an electron micrograph showing the particle structure of another polyamide powder for comparison. Patent Applicant: Sekisui Plastics Co., Ltd. No. 7-IJ Bin (F lcl?3

Claims (1)

[Claims] 1. A porous polyamide powder having a total pore volume of 0.25 cc/g or more, a specific surface area of 4.0 m^2/g or more, and a spherical shape. 2. The porous polyamide powder according to claim 1, which has a total pore volume of 0.25 to 1.50 cc/g. 3. The porous polyamide powder according to claim 1, which has a specific surface area of 4.0 to 30.0 m^2/g.