JP3305373B2 - Conductive inorganic powder, method for producing the same, and antistatic polymer material filled with the conductive inorganic powder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive inorganic powder, a method for producing the same, and an antistatic polymer material filled with the conductive inorganic powder. The present invention relates to a conductive inorganic powder having good properties, being inexpensive and easy to handle, a method for producing the same, and an antistatic polymer material filled with the conductive inorganic powder.

[0002]

2. Description of the Related Art In general, polymer materials such as plastic, rubber, paint, paper, etc. are highly insulating and are easily charged by contact or friction. In recent years, the above-mentioned polymer materials themselves have become noticeable due to static electricity damage due to themselves being a high insulator, and there is a demand for a countermeasure. Heretofore, it has been attempted to obtain an antistatic effect by filling or applying a conductive material such as conductive black carbon, metal fiber, metal oxide, or resin in the above-mentioned polymer material.

[0003]

However, since these conductive materials are black or colored, products filled with these materials cannot be colored freely, so that their use is restricted depending on the use. Lack of fashion. In addition, since these conductive materials are expensive, products filled or coated with these materials are expensive. Furthermore, the surface of a product filled or coated with a conductive resin tends to be sticky, and its antistatic effect is unstable, and its effect decreases with time, and the effect is significantly lost by washing with water or the like. Since it is difficult to uniformly disperse many conductive materials in the above-described polymer material, a sufficient antistatic effect cannot be obtained.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result of conducting a surface treatment with a specific polymer, a conductive inorganic powder capable of solving the above problems at once. Is provided. That is, according to the present invention, the surface of at least one kind of inorganic powder (A) selected from the group consisting of calcium carbonate and silicate mineral is represented by the following general formula (I):

[0005]

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Wherein R ₁ is a hydrogen atom or a methyl group;
Is an alkali metal, ammonium or amine. A) a conductive inorganic powder having a structural unit containing a sulfonate represented by the formula (1), wherein the content of the sulfonate is at least 30 mol%; And an antistatic polymer material filled with the conductive inorganic powder.

[0007] The inorganic powder (A) used in the present invention is at least one selected from the group consisting of calcium carbonate and silicate minerals. Preferred silicate minerals are talc and mica. , Clay and mixtures of two or more of these. Specific examples of the polymer (B) used in the present invention are as follows. (1) Salt of Sulfonated Polystyrene Polystyrene includes homopolymers and copolymers of styrene or α-methylstyrene. Monomers copolymerized with styrene or α-methylstyrene include hydrophobic monomers such as methyl acrylate, ethyl acrylate,
Aliphatic monomers such as butyl acrylate, ethylhexyl acrylate, methyl methacrylate, butyl methacrylate, stearyl methacrylate, and vinyl acetate; aromatic monomers such as vinyl naphthalene and vinyl toluene; and hydrophilic monomers such as acrylic acid and methacrylic acid Examples thereof include acids, maleic anhydride, and itaconic anhydride, which are used alone or in combination of two or more. The content of the sulfonate in the sulfonated polystyrene salt is preferably at least 30 mol%, more preferably at least 50 mol%. Sulfonate content of 30
If it is less than mol%, the conductivity tends to decrease. Sulfonation is performed by a known method in a solvent using a general sulfonating agent. As the sulfonating agent, sulfuric anhydride (hereinafter referred to as SO ₃ ) chlorosulfonic acid or the like is used. Particularly SO ₃ is liquid SO _3, inert gas and 1,2-dichloroethane, such as nitrogen, dry air, either SO ₃ or the like diluted with number 1-2 aliphatic halogenated hydrocarbons carbon atoms, such as ethyl chloride used it can. The amount of the sulfonating agent to be used is generally 0.5 to 2 mol, preferably 0.6 to 1. mol per mol of the styrene monomer in the raw polystyrene.
5 moles. When the molar amount used is small, the degree of sulfonation is insufficient and the insoluble content increases, while when the molar amount used is large, by-products such as bow salt increase. As the solvent, an aliphatic halogenated hydrocarbon having 1 to 2 carbon atoms is usually used.
Specific examples of such halogenated hydrocarbons include 1,2
-Dichloroethane, methylene dichloride, ethyl chloride,
Carbon tetrachloride, 1,1-dichloroethane, 1,1,2,2
-Inert sulfonating agents such as tetrachloroethane, chloroform, ethylene dibromide and the like are used, and these are used alone or in combination of two or more. The amount of the solvent used depends on the molecular weight of the polystyrene, but is usually 1 to 30 parts by weight, preferably 2 to 30 parts by weight, based on the raw material polystyrene.
-20 parts by weight. Sulfonation temperature is usually 0-50 ° C
It is. After sulfonation of polystyrene, it is neutralized with hydroxides, carbonates, etc. of alkali metals, alkaline earth metals, etc., and the solvent is separated by filtration, distillation, etc., and powdered or aqueous sulfonated polystyrene is obtained. To obtain the salt.

(2) Styrene sulfonate polymer The styrene sulfonate polymer includes a homopolymer and a copolymer. Examples of the monomer copolymerized with the styrene sulfonate include hydrophobic monomers such as methyl acrylate, ethyl acrylate, butyl acrylate, ethylhexyl acrylate, methyl methacrylate, butyl methacrylate, stearyl methacrylate, and vinyl acetate. Group monomers and aromatic monomers such as styrene, vinylnaphthalene, vinyltoluene, p-methylstyrene, and hydrophilic monomers such as acrylamide, acrylic acid, methacrylic acid, maleic anhydride, hydroxyethyl acrylate, hydroxyethyl methacrylic acid Examples thereof include esters, vinyl sulfonic acid, and 2-acrylamidopropyl sulfonic acid, which are used alone or in combination of two or more. The content of the styrene sulfonic acid salt in the styrene sulfonic acid copolymer is at least 30.
Mol% or more, more preferably 50% or more.
Mol% or more. If the styrene sulfonate content is less than 30 mol%, the conductivity tends to decrease. The styrene sulfonate polymer can be easily produced by a known method.
For example, styrene sulfonate and, if necessary, other monomer, persulfate, a radical initiator such as azobisisobutylnitrile are used in an amount of 0.1 to 5% by weight based on the monomer, and water,
Alternatively, the polymerization is carried out at 50 to 150 ° C. in an alcohol solvent. If necessary, a chain transfer agent such as mercaptans is used. Examples of the salt of the polymer (B) include alkali metal salts such as sodium, potassium, and lithium; ammonium salts;
Examples thereof include amine salts such as ethanolamine and triethylamine, and preferred are sodium and potassium alkali metal salts. The polymer (B) is used alone or as a mixture of two or more. If necessary, known organic substances such as fatty acids for calcium carbonate and the like, resin acids and the like, or inorganic substances such as Mg and Zn may be used in combination, whereby the antistatic effect and the like are not lost.

The polymer (B) is composed of an inorganic powder (A) 1
It is preferably in the range of 0.1 to 10 parts by weight in terms of active ingredient per 100 parts by weight. If the added amount is less than 0.1 part by weight, the obtained conductive inorganic powder does not have sufficient antistatic effect, and if it exceeds 10 parts by weight, the conductive inorganic powder obtained even if added more than 10 parts by weight. Almost no difference in antistatic effect.

As a method of treating the surface of the inorganic powder (A) with the polymer (B), when (A) is a dry powder, a method such as a super mixer or a paddle dryer is used.
Using an apparatus capable of heating and stirring at a temperature of from 120 to 120 ° C., while heating and stirring the (A) to a temperature of from 80 to 120 ° C., mix one or more kinds of (B) per 100 parts by weight of (A) to obtain a mixture of 0.1 or more. 1
-10 parts by weight, and further heated and stirred, (A)
The conductive inorganic powder is obtained by adhering and adsorbing (B) to the particle surface of (1). The inorganic powder to be used may be a surface-treated powder.

When (A) is a paste or an aqueous suspension, the above-mentioned treatment is carried out after dehydration, drying and pulverization to obtain a powder, or the mixture is stirred as it is (A). ) One or two or more kinds of (B) are added in an amount of 0.1 to 10 parts by weight per 100 parts by weight, and the mixture is further stirred, dehydrated, dried and pulverized to obtain a conductive inorganic powder.
In addition, dehydration is performed in order to increase drying efficiency, and drying may be performed directly without performing dehydration using a drying device such as a spray drier.

The conductive inorganic powder of the present invention thus obtained is not only conductive itself, but also has high whiteness, is uniformly dispersed in each medium, is inexpensive, and is easy to handle. When filled in a polymer material such as plastic, rubber, paint, paper, etc., an excellent antistatic effect is obtained, and the effect is stable and long-lasting. Especially polyolefins,
The effect is great for plastics such as PVC. Further, it is possible to prevent a decrease in workability due to static electricity generated when a plastic is processed into a sheet or a fibrous form or when the plastic is blended with another. In addition, since the whiteness is good, the antistatic product of the above-mentioned polymer material can be freely colored and has fashionability, and there is no limitation on the application due to coloring, and there is no problem such as surface stickiness. It is inexpensive and does not lose the effect originally obtained by using the inorganic powder.

When the polymer (B) is directly charged into the above-mentioned polymer material, an excellent antistatic effect can be obtained at first, but the effect is inferior to the conductive inorganic powder of the present invention. The antistatic effect tends to decrease with time, and other physical properties such as heat resistance are also inferior. The reason for this is that, in the case of the conductive inorganic powder of the present invention, since the polymer (B) is treated by adhering and adsorbing the polymer (B) to the surface of the inorganic powder particles, when the polymer powder is filled in a polymer material, It is easy to uniformly disperse the polymer (B). Therefore, the antistatic effect is exhibited not only on the surface of the polymer material but also on the inside. It is also believed that this prevents the polymer (B) itself from bleeding out to the surface of the polymer material.

[0014]

The present invention will now be described in more detail with reference to examples and comparative examples, but the present invention is not limited thereto. Example 1 100 parts by weight of heavy calcium carbonate (specific surface area: 11,000 cm ² / g, measured by an air permeation method, the same applies hereinafter) 100 parts by weight of sodium sulfonated polystyrene while heating and stirring at 80 to 100 ° C. with a super mixer 2 parts by weight of a 30% aqueous solution of a salt (sulfonate content = 60 mol%) was added, and the mixture was further heated and stirred, and the surface of the calcium carbonate particles was treated to obtain conductive calcium carbonate. In addition,
The final temperature in the supermixer tank was 100-120C.

Example 2 In place of the sodium salt of the sulfonated polystyrene used in Example 1, the sodium salt of a sulfonated styrene-maleic anhydride copolymer (styrene / maleic anhydride molar ratio = 2/1, sulfonic acid A conductive calcium carbonate was obtained in the same manner as in Example 1 except that the salt content was 55 mol%.

Example 3 A sodium styrenesulfonate-sodium acrylate copolymer (molar ratio of sodium styrenesulfonate / sodium acrylate = 7/3) was used in place of the sodium salt of sulfonated polystyrene used in Example 1. A conductive calcium carbonate was obtained in the same manner as in Example 1 except for using.

Comparative Example 1 The untreated heavy calcium carbonate (specific surface area: 11,000 cm ² / g) used in Example 1 was prepared.

Example 4 Sulfonated styrene used in Example 2 per 100 parts by weight of calcium carbonate per 100 parts by weight of calcium carbonate with respect to an aqueous suspension having a solid content of 15% by weight of a precipitated calcium carbonate having a primary particle diameter of 0.1 μm. The sodium salt of maleic anhydride copolymer
After the addition by weight, the mixture was sufficiently stirred. The obtained calcium carbonate-treated water suspension was dehydrated, dried and pulverized, and the surface of the calcium carbonate particles was treated to obtain conductive calcium carbonate.

Example 5 The untreated aqueous suspension of the untreated precipitated calcium carbonate having a primary particle diameter of 0.1 μm and having a solid content of 15% by weight used in Example 4 was used as it was in Example 4 without treatment. In the same manner as in Example 1, dehydration, drying, and pulverization were performed, and 100 parts by weight of the obtained untreated calcium carbonate powder was mixed with a supermixer in the same manner as in Example 1 using a super mixer.
While heating and stirring at １００100 ° C., 2 parts by weight of the sodium salt of the sulfonated polystyrene used in Example 1 was added, and the mixture was further heated and stirred, and the surface of the calcium carbonate particles was treated to form conductive calcium carbonate. Obtained.
The final temperature in the supermixer tank is 100 to 12
It was 0 ° C.

Comparative Example 2 The untreated precipitated calcium carbonate powder having a primary particle diameter of 0.1 μm used in Example 4 was prepared.

Comparative Example 3 A conductive calcium carbonate powder was prepared in the same manner as in Example 4 except that a fatty acid soap was used instead of the sodium salt of the sulfonated styrene-maleic anhydride copolymer used in Example 4. did.

Example 6 Conductive calcium carbonate was obtained in the same manner as in Example 1 except that heavy calcium carbonate having a specific surface area of 25,000 cm ² / g was used instead of heavy calcium carbonate used in Example 1. Was.

Example 7 A conductive talc was obtained in the same manner as in Example 1 except that talc (specific area: 11,000 cm ² / g) was used instead of the heavy calcium carbonate used in Example 1.

Comparative Example 4 The untreated talc powder used in Example 7 was prepared.

The inorganic powders obtained in Examples 1 to 7 and Comparative Examples 1 to 4 were measured for volume resistivity and whiteness.
The inorganic powder was dried at 105 ° C. for 2 hours in advance, then allowed to cool in a desiccator, and then pressurized to form a tablet and measured immediately. The measuring instrument is Yokogawa Hewlett-Packard Co., Ltd. Model 4329A HIG-H RESIST
Using Ance Meter, the whiteness of the powder was measured with a Kette photoelectric whiteness meter. The results are shown in Table 1. The inorganic powders of Comparative Examples 1 to 4 are highly insulating, whereas the conductive inorganic powders of Examples 1 to 7 of the present invention are in the conductive region.

[0026]

[Table 1]

* Measurement conditions Measure the volume resistivity after charging at 30 ° C., 60% RH 500 V, 60 seconds. Leaving condition 20 ° C., 60% RH. (The above measuring and leaving conditions are the same in the following.)

Examples 8 to 14 and Comparative Examples 6 to 9 Soft vinyl chloride sheets containing the inorganic powders obtained in Examples 1 to 7 and Comparative Examples 1 to 4 were prepared according to the following composition and sheet preparation conditions. did. One day later, the volume resistivity value of the prepared sheet was measured. The results are shown in Table 2.

Comparative Example 10 The heavy calcium carbonate of Comparative Example 1 (specific surface area: 11,000 cm ²
/ G) at the time of blending when preparing a soft vinyl chloride sheet, except that 2 parts by weight of the same amount of the sodium salt of the sulfonated polystyrene used in Example 1 was added.
4. In the same manner as in Comparative Examples 6 to 9, soft vinyl chloride sheets were prepared, and their volume resistivity was measured. Table 2 shows the results
Shown in

[0030]

[Table 2]

The soft vinyl chloride sheets obtained in Example 8 and Comparative Example 10 were subjected to a washing test according to the following washing test method. The results are shown in Table 3. "Rinse sample method" Rinse conditions Leave the sample sheet in running water Rinse time 1 day, 7 days, 1 month Measurement method Measure the volume resistivity value of the sample sheet after each water wash by the above method

[0032]

[Table 3]

The soft vinyl chloride sheets obtained in Example 8 and Comparative Examples 6 and 10 were subjected to a thermal stability test according to the following thermal stability test method. Table 4 shows the results of the whiteness and thermal stability of the sheet immediately after the sheet was prepared. The whiteness of the sheet was measured with a digital gloss meter GM-3D manufactured by Murakami Color Research Laboratory. “Thermal stability test method” Heating device Gear oven, with fan Heating temperature 180 ° C Heating time 10, 20, 30, 40, 50, 60 minutes Measurement method The degree of discoloration of the sample sheet was evaluated as ○, △, Display with ×

[0034]

[Table 4]

From Table 2, it can be seen that the soft vinyl chloride sheets obtained in Comparative Examples 6 to 9 containing the inorganic powders of Comparative Examples 1 to 4 are highly insulating, The soft vinyl chloride sheets obtained in Examples 8 to 14 in which powder was blended had a low volume resistivity value of the order of 10 ⁹ Ω-cm, and an excellent antistatic effect was recognized. In addition, the soft vinyl chloride sheet obtained in Comparative Example 10 in which untreated heavy calcium carbonate and the polymer (B) were added at the time of blending contained the same amount of the polymer (B) as in Example 8. Nevertheless, its volume resistivity was in the order of 10 ¹⁰ Ω-cm, which is one order higher than that of Example 8, and the antistatic effect was inferior to that of Example 8. Also, from Table 3, the antistatic effect of the soft vinyl chloride sheet obtained in Example 8 in which the inorganic powder of Example 1 was blended was maintained for a long time and was not lost even by washing with water. On the other hand, the volume resistivity of the soft vinyl chloride sheet obtained in Comparative Example 10 increased with time, and the antistatic effect decreased. Further, the volume resistivity of the soft vinyl chloride sheet was increased to about 10 ¹² Ω-cm by washing with water, and the antistatic effect was significantly reduced. Furthermore, from Table 4,
The soft vinyl chloride sheet obtained in Example 8 in which the inorganic powder of Example 1 was blended had high whiteness, and the thermal stability was slightly lower than that of Comparative Example 6 in which the inorganic powder of Comparative Example 1 was blended. Low but not much difference. Also, despite the addition of the same amount of polymer (B) as in Example 8, the soft vinyl chloride sheet obtained in Comparative Example 10 had lower whiteness than that of Example 8 and was thermally stable. The properties were significantly inferior to those of Example 8.

Examples 15 to 20, Comparative Examples 11 to 14 The inorganic powders of Examples 1 to 6 and Comparative Examples 1 to 4 were blended under the following composition and sheet preparation conditions to prepare polypropylene sheets. One day later, the volume resistivity value of the prepared sheet was measured. Table 5 shows the results. "Blending" Polypropylene resin (Mitsubishi Resin MH8) 70 parts by weight Inorganic powder 30 parts by weight

[0037]

[Table 5]

From Table 5, the volume resistivity values of the polypropylene sheets of Comparative Examples 11 to 14 containing the inorganic powders of Comparative Examples 1 to 4 are in the order of 10 ¹⁵ to 10 ¹⁶ , whereas those of Examples 1 to 6 are different. The polypropylene sheets of Examples 15 to 20 in which the inorganic powder was blended, had a volume resistivity value of the order of 10 ¹⁴ , and an excellent antistatic effect was recognized.

[0039]

The conductive inorganic powder of the present invention is not only conductive itself, but also has high whiteness, and exhibits excellent antistatic effect when blended in plastics such as soft vinyl chloride. The effect is stable and long-lasting without being lost by washing.

Continued on the front page (51) Int.Cl. ⁷ Identification code FI C08K 9/00 C08K 9/00 C09C 1/28 C09C 1/28 1/42 1/42 3/10 3/10 C09D 5/00 C09D 5 / 00 5/24 5/24 D21H 17/69 D21H 17/69 (72) Inventor Toshio Fujiwara 292-4, Oshio-cho, Himeji City, Hyogo Prefecture 1. Sanyo Kasei Kogyo Co., Ltd. (56) References JP-A-51-73540 (JP, A) JP-A-3-31347 (JP, A) JP-A-60-60140 (JP, A) JP-A-1- 231931 (JP, A) JP-A-3-103479 (JP, A) JP-A-62-191416 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09C 1/00-3 / 12 C08K 3/26 C08K 3/34 C08K 9/00 C09D 5/24 C01B 33/20 C01F 11/18 H01B 1/00-1/24

Claims (6)

(57) [Claims] 1. The surface of at least one kind of inorganic powder (A) selected from the group consisting of calcium carbonate and silicate minerals is represented by the following general formula (I): (Wherein, R ₁ is a hydrogen atom or a methyl group, M is an alkali metal, ammonium or an amine) having a structural unit containing a sulfonic acid salt, wherein the content of the sulfonic acid salt is at least 30 mol % Of a conductive inorganic powder treated with the polymer (B). 2. The conductive inorganic powder according to claim 1, wherein the silicate mineral is selected from the group consisting of talc, mica and clay. 3. An inorganic powder (A) selected from the group consisting of calcium carbonate and silicate minerals and at least one of the following general formulas (I): (Wherein, R ₁ is a hydrogen atom or a methyl group, M is an alkali metal, ammonium or an amine) having a structural unit containing a sulfonic acid salt, wherein the content of the sulfonic acid salt is at least 30 mol % Of the polymer (B) by stirring the polymer (B) on the surface of the inorganic powder (A) by stirring the polymer (B). 4. The production method according to claim 3, wherein the polymer (B) is used in a range of 0.1 to 10 parts by weight based on 100 parts by weight of the inorganic powder (A). 5. The method according to claim 3, wherein the silicate mineral is selected from the group consisting of talc, mica and clay. 6. An antistatic polymer material comprising a polymer material selected from plastic, rubber, paint and paper filled with the conductive inorganic powder according to claim 1.