JPH0649770B2 - Spherical fine powder of inorganic-containing thermoplastic resin and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of industrial application) The present invention relates to a spherical fine powder of a thermoplastic resin containing an inorganic substance and a method for producing the same, which is used in cosmetics or electrophotography. Various new applications can be expected in the field of advanced technology such as electronic parts and ceramics.

(Prior art) Cosmetics use petroleum jelly, paraffin, etc. as excipients, and inorganic powders such as titanium oxide, zinc oxide, and talc, as well as resin powders such as polyethylene for the purpose of improving the sliding effect when applied to the skin. Is blended separately as an ingredient. Further, various additives and resin powders are separately blended in the fields of electrophotography, ceramics for electronic parts, etc., but uniform mixing of the additives is not always easy.

(Problems to be Solved by the Invention) Conventionally, for example, when manufacturing cosmetics, inorganic substances such as titanium oxide, zinc oxide, and talc, which are added to cosmetics, have been added and mixed separately from the other additive resin. However, in the present invention, since these inorganic substances can be added by being contained in the thermoplastic resin powder such as polyethylene, the dispersibility in cosmetics is improved, and thus the ultraviolet dispersing effect, the coloring effect, etc. possessed by the inorganic substances are better than before. In addition, since the resin particle size is sufficiently small and it can be manufactured in a spherical shape, it is possible to reduce the rough feeling of the inorganic material on the skin by the slipping feeling of the resin.

[Structure of Invention]

(Means for Solving the Problem) (Function) The present inventors have conducted extensive studies on the compounding of the inorganic substance and the true spherical thermoplastic resin fine powder, and as a result, have completed the compounding. The gist of this is that when a thermoplastic resin containing an inorganic substance (excluding carbon black) is made into a fine powder, water is used as a medium and the presence of an ethylene oxide-propylene oxide copolymer and, if necessary, an ethylene-acrylic acid copolymer. Under, heating, under pressure to melt stirring to obtain an emulsion,
This is a method for pulverizing a thermoplastic resin into fine particles, which comprises cooling this to a temperature below the softening point of the inorganic-containing thermoplastic resin.

The thermoplastic resin used here is polyethylene, polypropylene, ethylene-propylene copolymer, polysulyene, styrene-acrylic copolymer, or the like, and acrylic acid as acrylic monomer copolymerizable with styrene is acrylic acid, Methyl acrylate, Ethyl acrylate, Butyl acrylate, Dodecyl acrylate, Octyl acrylate,
Examples include phenyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, and acrylamide.

The inorganic substance contained in the thermoplastic resin may have a diameter of 2 μm or less, preferably 0.5 μm or less, depending on the particle diameter of the target thermoplastic resin true spherical fine powder. Any kind of inorganic substance can be used as long as it can be mixed with the thermoplastic resin, but in the present invention, various inorganic substances are used except carbon black. Examples of particles satisfying the above particle size are granular metal (iron, copper, nickel, cobalt, silver, silver-palladium and their alloys, particle size 0.03 to 2 microns) zinc white (about 0.1 micron) Alumina (0.02-0.8 micron) Chromium oxide (about 0.01 micron) Titanium oxide (0.01-0.3 micron) Tungsten oxide (0.3-0.8 micron) Oxidation Iron (0.003-
1.0 micron) magnetite (about 0.01 micron) molybdenum oxide (0.5 to 2 micron) anhydrous silica (0.07 to 2 micron) white carbon (0.015 to 0.04 micron) zirconia (0.
01-0.1 micron) Titanium black (about 0.05
Micron) Magnesia (0.01-0.3 micron)
Tin oxide (about 0.1 micron) Oxide ceramic (0.005-0.01 micron) Ferrite (0.
002-0.1 micron) Al-Mg-based spinel (approx.
33 microns) Silicon carbide (0.004 to 0.1 microns) Titanium nitride (about 0.045 microns) Aluminum hydroxide (about 0.2 microns) Magnesium hydroxide (about 0.38 microns) Talc (about 1.5) micron)
And so on. However, the particle diameters of the above exemplified materials are only one example, and are not restricted thereto.
Any material can be used as long as it can be adjusted to a micron or less and can be mixed with the thermoplastic resin substantially uniformly. The amount of the inorganic material used is determined depending on the desired physical properties and cannot be generally stated, but 1 to 20 parts by weight is suitable for 100 parts by weight of the thermoplastic resin.

Generally, the powdering method of a thermoplastic resin is roughly classified into three methods: a mechanical grinding method, a dissolution method and a dispersion method. In the mechanical pulverization method, an irregularly-shaped powder can be produced by using a high-step-stage pulverizing device, but the average particle size is 100 to 30.
It is 0 micron, and only particles having a relatively large particle size can be obtained.

The dissolution method is a method in which a thermoplastic resin is dissolved in a solvent, a poor solvent is added if necessary, and the powder is precipitated by cooling or the solvent is evaporated to obtain the powder.

In this case, a method of obtaining fine powder by giving strong stirring is often adopted, but even in that case, the average particle diameter is at most about 20 to 50 microns, and a spherical shape cannot be obtained.

Dispersion method is a method of obtaining a powder of a thermoplastic resin by the action of various dispersants, there is a method of dissolving the thermoplastic resin in a solvent, there is a method of dispersing by mixing the dispersion liquid and water,
It is most preferable and advantageous to disperse the solvent only in an aqueous medium which is industrially unnecessary to recover the solvent.

In view of such a situation, the inventors of the present invention have diligently studied a method of pulverizing a thermoplastic resin, and using water as a medium,
Heating in the presence of an ethylene oxide-propylene oxide copolymer and, if necessary, an ethylene-acrylic acid copolymer,
The thermoplastic resin is melted and stirred under pressure to obtain an emulsion, which is cooled to a temperature below the softening point of the thermoplastic resin, filtered and dried by a conventional method to give an average particle diameter of 50 microns or less. The present invention has been completed by finding a method for obtaining a fine spherical thermoplastic resin powder containing an inorganic substance.

The thermoplastic resin used in the present invention means the above-mentioned polyethylene, polypropylene, ethylene-propylene copolymer,
Polystyrene, styrene-acrylic copolymer, etc., and the melting index of the raw material thermoplastic resin at the emulsification temperature is 2
The one used is 0 or more, preferably 50 or more. (JIS
Measured by the method described in K 7210, test load 2.16 kg
/ 10 minutes) What is an ethylene oxide-propylene oxide copolymer? X = 2-150, Y = 10-90,
It is a general term for copolymers having Z = 2 to 150. For example, the ethylene oxide-propylene oxide copolymer used in the present invention is as follows: X = 60 to 130, Y = 30 to 70, Z = 6
Those in the range of 0 to 130 are suitable.

The amount used is 3 to 100 parts by weight of the raw material thermoplastic resin.
60 parts by weight is suitable, and more preferably 8 to 50 parts by weight. If it is less than that, it is difficult to carry out sufficient emulsification, and if it is used more than that, the product is often mixed in the fine powder, which is not preferable in many cases.

Further, if necessary, an ethylene-acrylic acid copolymer is used (see Japanese Patent Application No. 59-69635). The ethylene-acrylic acid copolymer used in this case means that ethylene and acrylic acid are polymerized under high pressure, for example. With the polymer obtained by It has a structure of, and irregularly bonds with acrylic acid to ethylene, and contains 3 to 20% by weight of acrylic acid. (Trade name: EAA, manufactured by Dow Chemical Co.) The ethylene-acrylic acid copolymer used in the present invention may be partially neutralized with caustic soda, caustic potash, ammonia or the like. The degree of neutralization can be from 0 to 20%, but is preferably from 0 to 15%. When the degree of neutralization is higher than that, the ethylene-acrylic acid copolymer is dissolved in water and loses its function as an emulsifier, which is not preferable. For neutralization, caustic soda, caustic potash, ammonia, etc. can be added in a separate container in advance. In a pressure resistant autoclave charged with ethylene-acrylic acid copolymer, only the required amount of caustic soda, caustic potash,
It can also be used by adding ammonia or the like. The latter is industrially simpler and often advantageous. The amount of ethylene-acrylic acid copolymer used during emulsification is in the range of 1 to 20% by weight based on the raw material thermoplastic resin.

Water used as a medium during emulsification is 100% of the raw material thermoplastic resin.
It is in the range of 50 to 3000 parts by weight, preferably in the range of 100 to 2000 parts by weight, based on parts by weight.

If the amount of water used is less than that, it is difficult to stably obtain a thermoplastic resin having a desired particle size containing an inorganic substance, and a thermoplastic resin having a coarse particle size may be generated, which is not preferable. If it is more than that, the efficiency of obtaining the fine powder with respect to the volume of the reactor becomes poor, which is industrially disadvantageous.
If necessary, the emulsification method is to put water or steam into a pressure-resistant autoclave that has been replaced with an inert gas such as N ₂ , and
Then, by using a roll, a kneader or the like in advance, a raw material thermoplastic resin in which inorganic substances are sufficiently uniformly mixed, an ethylene oxide-propylene oxide copolymer, and if necessary, an ethylene-acrylic acid copolymer are added, the system is hermetically closed, and a predetermined temperature is set. Up to.

Normally, oil, steam, etc. are fed into the jacket for heating, and if necessary, stirring is performed to promote melting.

Alternatively, a raw material thermoplastic resin containing an inorganic substance by a method such as pumping in a pressure-resistant autoclave in which water and steam are heated to a predetermined temperature, an ethylene oxide-propylene oxide copolymer, and an ethylene-acrylic acid copolymer if necessary. The method of adding can also be adopted.

Temperature and pressure conditions differ depending on the type of thermoplastic resin used. In general, finer powders that meet the purpose are often obtained at higher temperature and higher pressure, but the conditions may be selected in consideration of the decomposition of the polyolefin and the decomposition of the dispersant.
The heating is performed until the melting index of the raw material thermoplastic resin at the emulsification temperature becomes 20 or more. For example, the temperature of the above-mentioned thermoplastic resin is usually raised to 100 to 230 ° C, preferably 150 to 200 ° C. The pressure in the system at that time generally indicates the vapor pressure of water corresponding to the temperature. The stirring of the contents after the temperature rise varies depending on the size of the autoclave, the amount charged, etc., but usually the stirring blade tip speed of 1 to 5 m / sec is sufficient for 2 minutes to 2 hours, and particularly strong stirring is not required. The content thus obtained is in an emulsion state and can be filtered and dried by a conventional method to obtain the inorganic substance-containing true spherical thermoplastic resin fine powder of the present invention. The present invention will be described below with reference to examples.

〔Example〕

Example 1 93 mm inner diameter equipped with a propeller-type stirring blade having a diameter of 52 mm,
In a pressure-resistant autoclave with a height of 240 mm and an internal volume of 1, 304 g of pure water and white carbon were previously used with a kneader (manufactured by Mizusawa Chemical Co., Ltd .: trade name Shilton R-2 particle size 25 to 3).
Polyethylene (trade name: Sumikasen G807, manufactured by Sumitomo Chemical Co., Ltd.) 60 g of ethylene oxide-propylene oxide copolymer [molecular formula (Asahi Denka: product name Pluronic F-108) 30g
And ethylene-acrylic acid copolymer (manufactured by Dow Chemical Co .:
6 g of trade name EAA XO-2375-33) and 0.07 g of caustic soda are charged and sealed. Next, heating was performed from the outside of the autoclave to raise the temperature inside the autoclave to 200 ° C. The pressure was 17 kg / cm ² as a gauge pressure. The stirrer was started and stirred at 1000 rpm for 15 minutes. The stirring blade tip speed is 2.7 m / sec. Then, cooling was performed, and when the internal temperature reached 90 ° C., the contents were taken out from the autoclave. The content was in an emulsion state and was filtered and dried to obtain a true spherical fine powder. When this was analyzed, the true spherical fine powder had an average particle diameter of 8.6 microns.

Examples 2 to 6 Inorganic substances shown in Table 1 were used instead of white carbon, and emulsification was performed in the same manner as in Example 1 to obtain spherical fine powders.

Example 7 An emulsion liquid was obtained in the same manner as in Example 1 except that the ethylene-acrylic acid copolymer was not added. When this was analyzed, the average particle size of the true spherical fine powder was 12.6 microns.

Example 8 Instead of polyethylene, polystyrene (manufactured by Sanyo Kasei Co., Ltd.,
Emulsification was performed in the same manner as in Example 1 except that the temperature in the autoclave was raised to 150 ° C. using a trade name: Heimer ST-95), and the contents were taken out after cooling. The content was in an emulsion state, and when analyzed, it was found that the true spherical fine powder had an average particle diameter of 11.8 microns.

Example 9 Emulsification was performed in the same manner as in Example 8 except that a styrene-acrylic copolymer (manufactured by Sanyo Kasei Co., Ltd., trade name: Hymer SBM-100) was used instead of polystyrene, and the contents were taken out after cooling. . The content was in an emulsion state, and when analyzed, it was found that the true spherical fine powder had an average particle diameter of 13.1 microns.

〔The invention's effect〕

According to the present invention, a true spherical fine powder of a thermoplastic resin containing an inorganic substance substantially uniformly can be obtained. Further, since there is no problem at all during production, a method industrially advantageous can be provided.

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Claims (11)

[Claims] 1. A thermoplastic resin in which 1 to 20 parts by weight of an inorganic substance (excluding carbon black) is substantially uniformly contained in 100 parts by weight of a thermoplastic resin is used as an ethylene oxide-propylene oxide copolymer in an aqueous medium. In the presence of the polymer,
Of an inorganic-containing thermoplastic resin having an average particle size of 50 microns or less obtained by melting and stirring under heat and pressure to obtain an emulsion, and cooling the emulsion to the softening temperature of the thermoplastic resin containing the inorganic or less. True spherical fine powder. 2. The true spherical fine powder according to claim 1, wherein the thermoplastic resin is polyethylene. 3. The true spherical fine powder according to claim 1, wherein the thermoplastic resin is polystyrene. 4. The true spherical fine powder according to claim 1, wherein the thermoplastic resin is a styrene-acrylic copolymer. 5. The true spherical fine powder according to claim 1, wherein the particle size of the inorganic material is 2 microns or less. 6. A thermoplastic resin containing 1 to 20 parts by weight of an inorganic substance (excluding carbon black) substantially uniformly with respect to 100 parts by weight of a thermoplastic resin is used as an ethylene oxide-propylene oxide copolymer in an aqueous medium. In the presence of the polymer,
An inorganic-containing thermoplastic resin having an average particle diameter of 50 microns or less, characterized in that it is melted and stirred under heating and pressure to obtain an emulsion, and the emulsion is cooled to a temperature not higher than the softening temperature of the inorganic-containing thermoplastic resin. The method for producing a true spherical fine powder. 7. The production method according to claim 6, wherein the thermoplastic resin is polyethylene. 8. The method according to claim 6, wherein the thermoplastic resin is polystyrene. 9. The method according to claim 6, wherein the thermoplastic resin is a styrene-acrylic copolymer. 10. The method according to claim 6, wherein the particle size of the inorganic material is 2 microns or less. 11. The method according to claim 6, wherein an ethylene-acrylic acid copolymer is used during emulsification.