JPH1017785A - Low-molecular weight polytetrafluoroethylene composite powder and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a low-molecular weight polytetrafluoroethylene (PTFE) composite powder that can sufficiently develop inherent properties of mother particles, BN, talc, mica and sericite, provide water- and oil-repellency originated from daughter particles, low-molecular weight PTFE, and be used suitably as a cosmetic material, paint additive, and the like by a homogeneous complexing treatment efficiently and in a good working environment. SOLUTION: This low-molecular weight polytetrafluoroethylene (PTFE) composite powder is obtained by subjecting surfaces of at least one kind of mother particles selected from hexagonal boron nitride, talc, mica and sericite to surface modification treatment to electrostatically charge the particles with a positive charge, and then subjecting the particle surfaces to complexing treatment with daughter particles composed of polytetrafluoroethylene powder of average degree of polymerization of 200 or less, so that low-molecular weight polytetrafluoroethylene composite powder whose particle surfaces are modified to positively charged condition is formed by complexing treatment of mother particle surfaces with polytetrafluoroethylene powder of average degree of polymerization of 200 or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention is capable of exhibiting excellent water repellency and oil repellency in addition to exhibiting the original properties of hexagonal boron nitride, talc, mica or sericite which are base particles.
Low molecular weight polytetrafluoroethylene (hereinafter referred to as P) which can be suitably used as a cosmetic raw material, a paint additive, and the like.
(Referred to as TFE) and a method for producing the same.

[0002]

2. Description of the Related Art Inorganic powders having a plate-like particle shape such as hexagonal boron nitride (hereinafter referred to as BN), talc, mica, and sericite have excellent lubricity, Attention is paid to having hiding power, color,
It is used as a raw material for cosmetics and as a paint additive.

However, since these inorganic powders have poor water repellency, when they are used as cosmetic raw materials, their makeup may be destroyed by sweat or rainwater, and when bathing or swimming, it is necessary to redress their makeup each time. Practical problems arise.

Therefore, as a method for improving the water repellency,
The present inventors have proposed in Japanese Patent Application No. 7-48017 a method of compounding fluorinated graphite powder on the surface of BN particles. However, although this method greatly improves water repellency, improvement in oil repellency is not satisfactory. For this reason, since this composite powder does not have the property of repelling the sebum component generated by metabolism of the human body, it has an affinity with sebum and may have insufficient makeup retention.

In order to solve the above problems, water repellency,
It is necessary to develop a powder raw material having both excellent oil repellency. As a method therefor, the present inventors have disclosed Japanese Patent Application No. 7-161.
No. 887 proposed a method of silylating BN powder with a silazane compound having a perfluoroalkyl group. According to this method, it is possible to improve both the water repellency and the oil repellency of the inorganic powder raw material, so that the above problem can be solved. There is a problem that the environment deteriorates.

On the other hand, high water-repellent and oil-repellent powders which can be obtained without any problem of working environment include low molecular weight P having a degree of polymerization of 200 or less.
A composite powder using TFE as a child particle has been considered, and various studies have been made using the water and oil repellency of low molecular weight PTFE. JP-A-4-283268, 4-2
No. 85199 proposes dispersing a low-molecular-weight PTFE powder in a metal plating solution to perform plating on the surface of the base material or the base particles. Also, Japanese Patent Application Laid-Open No. 6-296
No. 924 proposes a method in which a liquid resin is coated on the surface of a base material, and then a low molecular weight PTFE powder is adhered and solidified.

However, according to these methods, the original characteristics of the base particles are lost, the color is changed, and the like, and the resulting composite powder is difficult to apply as a cosmetic raw material. Therefore, development of a high-quality low-molecular-weight PTFE composite powder that can be used as a cosmetic raw material and a method for producing the same are desired.

The present invention has been made in view of the above circumstances, and provides a low-molecular-weight PTFE composite powder capable of exhibiting excellent water repellency and oil repellency in addition to being able to satisfactorily exhibit the inherent properties of the mother particles. An object of the present invention is to provide a method for producing the above composite powder, which can be produced efficiently and in a good working environment by a composite treatment.

[0009]

Means for Solving the Problems and Embodiments of the Invention The present inventors have made intensive studies to achieve the above object, and as a result, have found that BN, talc,
A low-molecular-weight PTFE composite powder obtained by subjecting at least one type of base particle selected from mica and sericite to a composite process with a PTFE powder having an average degree of polymerization of 200 or less is used as a base particle having lubricity, hiding power, color, and the like. In addition to maintaining the properties of, it can exhibit high water and oil repellency, and can be effectively used as a cosmetic raw material, a paint additive, and the like.Moreover, at least one selected from BN, talc, mica, and sericite After the surface of one kind of base particles is subjected to a surface modification treatment to be in a positively charged state, the surface of the powder is subjected to an average degree of polymerization of 2
By performing the compounding process with the PTFE powder having a particle size of 00 or less, the powder surface can be uniformly and efficiently compounded without aggregation of the particles and adhesion of the particles to the processing equipment.
Moreover, they have found that the composite powder can be produced without deteriorating the working environment, and have accomplished the present invention.

That is, there has hitherto been no example in which low-molecular-weight PTFE is combined to improve the water repellency and oil repellency of powders useful as cosmetic raw materials such as BN, talc, mica, and sericite. This is because low-molecular-weight PTFE powder has a strong negative charge property, and therefore has a large particle cohesion and a large adhesion to the stainless steel inner wall of the composite processing equipment, and it is difficult to perform processing by a simple composite processing method. However, the present inventors treated the surfaces of BN, talc, mica, and sericite with a silane coupling agent having an amino group, a positively charged methyl methacrylate (hereinafter, referred to as MMA) polymer, and the like. And then mixed with a low polymerization degree PTFE powder to obtain BN,
PTFE with low polymerization degree on talc, mica and sericite surfaces
It has been found that the powder adheres firmly and the complexing process is performed favorably.

Therefore, according to the present invention, the surface of at least one kind of base particles selected from BN, talc, mica and sericite whose powder surface is modified to a positively charged state has an average degree of polymerization of 2
A low-molecular-weight PTFE composite powder characterized by being subjected to a composite treatment with PTFE powder of not more than 00, and at least one selected from BN, talc, mica and sericite.
After the surface modification treatment of the types of base particles and positively charged,
The present invention also provides a method for producing the low-molecular-weight PTFE composite powder, wherein the surface of the powder is composite-treated with secondary particles made of PTFE powder having an average degree of polymerization of 200 or less.

Hereinafter, the present invention will be described in more detail. The composite powder of the present invention uses at least one kind selected from BN, talc, mica and sericite as a base particle.

The average particle diameter of BN, talc, mica, and sericite used as the base particles is 3 μm or more.
In particular, it is preferably at least 5 μm. Average particle size is 3
If it is less than μm, the aggregated particles may be increased, or the difference in particle diameter from the child particles may be insufficient, which may hinder the compounding process. The upper limit of the average particle diameter is not particularly limited, but is practically about 30 μm.

Further, the above-mentioned base particles preferably have a small specific surface area and a smooth particle surface, and more specifically, a specific surface area of less than 10 m ² / g. If the specific surface area is 10 m ² / g or more and the particle surface is rough, the contact area between the mother particle and the child particle is small, and both particles after the composite treatment may be detached.

In addition, the properties of the base particles are preferably such that the required properties other than water / oil repellency are good when used alone, even when used after performing the compounding treatment of the present invention. .

Next, as the child particles, an average degree of polymerization of 200
The following PTFE powder is used. In this case, the average degree of polymerization of the PTFE powder as the child particles must be 200 or less, preferably 100 or less. The degree of polymerization is represented by the n value of (C ₂ F ₄ ) _n . If the average degree of polymerization exceeds 200, the number of CF ₃ groups at the terminal of the molecular chain becomes small, so that sufficient water / oil repellency cannot be imparted.

Further, it is preferable that the average particle diameter of the child particles is not more than the base particles, particularly not more than 1/5 of the base particles. When the average particle size exceeds the base particle, the relationship between the base particle and the child particle is reversed. Also, even if it is smaller than the base particle,
If it is larger than 5, the compounding process may not be performed uniformly.

In the composite powder of the present invention, the surface of the above-mentioned base particles whose surface has been modified to a positively charged state has a low molecular weight P of the child particles.
It is obtained by compounding with TFE powder.

In the present invention, the complexing method is not particularly limited, and a conventionally known hybridization method,
A mechanofusion method, a high-speed elliptical rotor method, or the like can be used to carry out the method in a usual manner. However, low molecular weight PTFE has a large negative charging property and the material of the powder contact member of the complex processing equipment is generally stainless steel. Therefore, P
TFE powder tends to agglomerate and adhere to the inner wall of the processing equipment. In order to prevent the phenomenon and uniformly perform the compounding process, a process of positively charging the base particles in advance is performed so that the base particles-child particles It is necessary to provide an electrical attraction to the surface.

Here, the treatment for positively charging the base particles includes a method of performing a surface modification treatment with a silane coupling agent having an amino group in an organic functional group, and a method of surface-coating a positively charged MMA polymer. Adopted effectively.

Specific examples of the silane coupling agent having an amino group in the organic functional group include those shown in Table 1.

[0022]

[Table 1]

As the surface modification treatment method using a silane coupling agent having an amino group in the organic functional group, a conventionally known wet treatment can be suitably applied. The treatment amount of the silane coupling agent can be appropriately adjusted in accordance with the specific surface area and other properties of the base particles. ~
10 parts.

On the other hand, the charging characteristics of the MMA polymer vary depending on the type of the polymerization initiator and the copolymer, and an azobis-based polymer having an amino group is used for positive charging, or DMA (dimethylamine) is used. Is effective.

The method of coating the MMA polymer on the surface of the mother particles is not particularly limited. For example, the MMA polymer is dissolved in a solvent in which the MMA polymer is soluble, such as toluene or acetone, and then the mother particles are added thereto. May be dispersed and dried. In addition, the coating amount of the MMA polymer is generally
0.1 to 10 parts per part.

Next, in the above method, the compounding treatment can be carried out by a usual method as described above. In this case, the mixing ratio of the surface-treated mother particles / child particles at the time of the treatment can be appropriately adjusted according to the properties of both powders and the required characteristics of the final product. Particle 1
A range of 30 parts, especially 5 to 20 parts, is preferred.

In the present invention, if the base particles are positively charged by such a treatment, an electric attractive force acts between the mother particles and the negatively charged PTFE. Can be.

[0028]

As described above, the composite-treated powder of the present invention contains B
N, talc, mica and sericite can be satisfactorily expressed in their original properties, and the water repellency and oil repellency derived from the low molecular weight PTFE of the child particles are imparted. According to the production method of the present invention, The composite powder can be efficiently produced by a uniform composite treatment and in a good working environment.

Therefore, the composite powder obtained by the above treatment has both excellent water repellency and oil repellency. Therefore, when it is used as a cosmetic raw material, the makeup does not collapse due to sweat or rainwater, so that it does not take a bath. Or after swimming, it is not necessary to make up the makeup, and it also has the advantage that the sebum component generated by the metabolism of the human body is repelled and the makeup retention is also good, and it can be suitably used as a raw material for cosmetics.
It can be suitably used for applications requiring water repellency and oil repellency such as paint additives.

[0030]

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. All parts in each example are parts by weight.

Example 1 N-β (aminoethyl) γ-
3 parts of aminopropyltrimethoxysilane (KBM603, manufactured by Shin-Etsu Chemical Co., Ltd.) was dispersed in 100 parts of water and subjected to ultrasonic vibration for 1 hour to prepare a silane solution. The obtained silane solution and 100 parts of BN powder (KBN (h) -SR, manufactured by Shin-Etsu Chemical Co., Ltd.) having an average particle size of 5 μm were mixed with a gate mixer for 1 hour, and then mixed in a vacuum at 100 ° C. for 5 hours. After drying, an aminosilane-treated BN powder was obtained.

Next, the aminosilane-treated BN powder 10
0 parts and a PTFE powder having an average particle size of 1 μm and an average degree of polymerization of 25 (manufactured by Central Glass Co., Ltd., Sefrallube V), and a high-speed elliptical rotor-type compounding device (manufactured by Tokuju Corp.,
(Theta Composer) and treated at 5000 rpm for 1 hour.

The PTFE composite powder obtained by the above treatment was spread flat on a double-sided tape, and the contact angle with water and squalane was measured.

Example 2 A prototype was produced and evaluated in the same manner as in Example 1 except that mica powder having an average particle diameter of 10 μm was used instead of BN powder.

Comparative Example 1 Regarding untreated BN powder,
The same evaluation as in Example 1 was performed.

[Comparative Example 2] A prototype was produced and evaluated in the same manner as in Example 1 except that untreated BN powder was used.
The TFE powder adhered to the inner wall of the container, and the composite treatment could not be performed.

Example 3 93 mol% of MMA, DMA7
Mole% was suspension polymerized. MM with an average degree of polymerization of about 2000
After dissolving 5 parts of the polymer A in 500 parts of acetone, 100 parts of the BN powder used in Example 1 were dispersed and mixed, and the resulting slurry was spray-dried with a spray drier.
A trial production and evaluation were performed in the same manner as in Example 1 using the obtained powder as mother particles.

Comparative Example 3 PTFE having an average degree of polymerization of 250
A prototype was produced and evaluated in the same manner as in Example 1 except that powder was used. Table 2 shows the above results.

[0039]

[Table 2]

From the results shown in Table 2, the powder of the present invention (Examples 1 to 3)
3) shows that the water repellency and the oil repellency are greatly improved as compared with the powder before the compounding treatment (Comparative Example 1), and further, the amino silane treatment is not performed (Comparative Example 2), and the charging characteristics of PTFE Therefore, it was found that the composite treatment could not be performed, and that the characteristics hardly changed when PTFE having a high degree of polymerization was used (Comparative Example 3).

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Toshihiko Shindo 2-13-1 Isobe, Annaka-shi, Gunma Prefecture Shin-Etsu Chemical Industry Co., Ltd.

Claims (4)

[Claims] 1. A polytetrafluoroethylene powder in which at least one kind of base particle surface selected from hexagonal boron nitride, talc, mica and sericite whose surface is modified to a positively charged state has an average degree of polymerization of 200 or less. A low-molecular-weight polytetrafluoroethylene composite powder, which has been subjected to a composite treatment. 2. The low molecular weight polytetrafluoroethylene composite powder according to claim 1, wherein the mother particles are subjected to a surface modification treatment with a silane coupling agent having an amino group in an organic functional group. 3. The low molecular weight polytetrafluoroethylene composite powder according to claim 1, wherein the base particles are surface-coated with a positively charged methyl methacrylate polymer and subjected to a surface modification treatment. 4. The surface of at least one kind of base particles selected from hexagonal boron nitride, talc, mica and sericite is surface-modified and positively charged. The method for producing a low-molecular-weight polytetrafluoroethylene composite powder according to claim 1, wherein the composite treatment is carried out with a child particle composed of tetrafluoroethylene powder.