JP2002309099A - Electret material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electret material having a high trapped electric charge at a high-temperature side, stably retaining the charge for a long time and having excellent heat resistance and colorability. SOLUTION: This heat-resistant electret material comprises at least one kind selected from a hindered amine-based, nitrogen-containing hindered phenol- based, metallic-salt hindered phenol-based, phenolic, hindered phenol-based and phenolic sulfur weatherability improving agent in an amount of 0.01-10 pts.wt. based on 100 pts.wt. of a high-molecular-weight polymer. The weatherability improving agent is prepared by formulating an alkylphosphinic acid compound represented by general formula (1) or (2) (wherein, R<1> and R<2> denote each an organic group or a halogen atom; m and n denote each an integer of 0-4; the R<1> and R<2> may be same or different when the m or n is an integer of 2-4; and A is a same or different organic group from the R<1> and R<2> ) and a fatty acid metallic salt in an amount of 0.01-10 pts.wt. based on 1 pt.wt. thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electret material excellent in heat stability and permanent charging property. In particular, it is suitable for use in equipment for removing tobacco smoke, filters for indoor air purifiers, dust masks for work, and the like.

[0002]

2. Description of the Related Art As a method for imparting an electret effect by adding a compound to a polymer, for example, Japanese Patent Application Laid-Open No. 60-196922 discloses a method in which a fatty acid metal salt is added as a compound to an insulating polymer. A method of blending and corona discharge treatment is described. In Japanese Patent Publication No. 4-42812, at least one selected from hindered amine-based, nitrogen-containing hindered phenol-based, metal salt hindered phenol-based, and phenol-based stabilizers is blended to improve heat resistance. Is described.

[0003] However, these compounds have improved heat resistance, but do not have a semi-permanent durability and are not always satisfactory.

On the other hand, alkyl phosphinic acid compounds used in the present invention for high polymers are described in, for example,
As described in Japanese Patent Application No. 0-181146, it is described that addition to an olefin resin composition contributes to improvement in anti-coloring properties, rigidity, and impact strength at low temperatures. In recent years, Japanese Patent Application Laid-Open No. 4-351669 describes that an olefin-based antioxidant is used in combination with a phenol-based antioxidant.

[0005] However, these inventions are directed to the prevention of oxidation and the improvement of rigidity of the high molecular polymer, and do not disclose the chargeability by the combined use with the fatty acid metal salt and the continuation of the semi-permanent property.

[0006]

SUMMARY OF THE INVENTION The present invention provides an electret material having a high surface charge density on a high-temperature side and having excellent heat resistance and coloring properties for stably retaining charges for a long time.

[0007]

According to the present invention, there is provided a polymer comprising 0.01 to 1 part by weight per 100 parts by weight of the polymer.
0 parts by weight of at least one selected from hindered amines, nitrogen-containing hindered phenols, metal salt hindered phenols, phenols, hindered phenols, phenolic sulfur-based weathering agents, and the hindered amine System, nitrogen-containing hindered phenol system,
Metal salt hindered phenol-based, phenol-based, hindered phenol-based, phenol-based sulfur-based weathering agent 1
The following general formula (1) of 0.01 to 10 parts by weight per part by weight
Or a heat-resistant electret material comprising the alkylphosphinic acid compound represented by (2) and a fatty acid metal salt.

[0008]

Embedded image (Wherein R ¹ and R ² represent an organic group or a halogen atom,
m and n each represent an integer of 0 to 4, and when m or n is an integer of 2 to 4, R ¹ and R ² may be the same or different. )

Hindered amines, nitrogen-containing hindered phenols, metal salt hindered phenols, phenolic sulfur-based weathering agents, and the above-mentioned hindered amines, nitrogen-containing hindered phenols, metal salt hindered phenols, phenols By adding an alkylphosphinic acid compound to a hindered phenol-based, phenol-based sulfur-based weathering agent, the chargeability and heat resistance,
The coloring property was remarkably improved, and these effects were maintained for a long time.

Further, for example, Japanese Patent Application Laid-Open No. 4-42812 discloses effects of various antioxidants, but in the present invention, the effect of coloring resistance even under a high temperature atmosphere and the moldability at the time of sheet production are remarkably improved. Improved.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The polymer used in the present invention is polypropylene, polyethylene, polystyrene, polyester, polycarbonate, polyamide, polyphenylene sulfite, fluorine resin, chlorine resin, vinyl resin and / or a blend, A spinnable resin such as a polymerized resin is used. Particularly, as an electot material, polypropylene is preferable from the viewpoint of insulating properties.

The volume resistivity of the high-molecular polymer is 10 ¹²
Ωcm or more, preferably 10 ¹⁴ Ωcm or more.
Below this, the effect of the charging property is small, and conversely, 10 ¹⁴
If it is Ωcm or more, the effect is almost constant.

As an example of the antioxidant used in the present invention, in the case of hindered amine, poly [｛(6- (1,1)
(1,3,3-tetramethylbutyl) imino-1,3,
5-triazine-2,4-diyl) {(2,2,6,6
-Tetramethyl-4-piperidyl) imino {hexamethylene} (2,2,6,6-tetramethyl-4-piperidyl) imino} (Chimasov 9 under the trade name of Ciba-Geigy)
44LD), dimethyl-1-hydroxyethyl succinate] -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate (Tinuvin 622LD under the trade name of Ciba Geigy), 2- (3,5-di- Bis (1,2,2,6,6-pentamethyl-4-piperidyl) (t-butyl-4-hydroxybenzyl) -2-n-butylmalonate (Tinuvin 144 under the trade name of Ciba Geigy) and the like.

In the nitrogen-containing hindered phenol, 1,
3,5-tris (4-t-butyl-3-hydroxy-
2,6-dimethylbenzyl) isocyanuric acid (trade name Cyanox 1790, Nippon Cyanamid Co.) or
1,3,5-tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanuric acid (IR3114 under the trade name of Ciba Geigy).

In the metal salt hindered phenol, 3,5
Calcium di-tert-butyl-4-hydroxy-benzyl-mono-ethyl-phosphonate (IR1425W
L), nickel of 3,5-di-t-butyl-4-hydroxy-benzyl-mono-ethyl-phosphonate (Ilgastab 2002 under the trade name of Ciba-Geigy), or a magnesium salt of the above compound.

In the phenol type, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4
-Hydroxyl) benzene (Ciba-Geigy trade name I
R1330), pentaerythrityl-tetrakis [3-
(3,5-di-t-butyl-4-hydroxyphenyl)
Propionate (IR101 under the trade name of Ciba Geigy)
0).

In the hindered phenol system, 2,6-di-t-butyl-4-methylphenol (Sumilyzer B)
HT), n-octadecyl-3- (3 ', 5'-di-t
-Butyl-4'-hydroxyphenyl) propionate, 2,2'-methylene-bis- (4-methyl-6-t
-Butylphenol), 2-t-butyl-6- (3′-
t-butyl-5'-methyl-2'-hydroxybenzyl) -4-methylphenylacrylate, 1,3,5-
Tris (4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate, tetrakis- [methylene-3- (3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate] -Methane (Sumilyzer BP-101), 3,9-bis- [2-3- (3
-T-butyl-4-hydroxy-5-methylphenyl)
Propionyloxy] -1,1-dimethylethyl]-
2,4,8,10-tetraoxaspiro [5,5] undecane and the like.

Examples of the sulfur-based stabilizer include dilauryl thiodipropionate (DLTDP), dimyristyl thiodipropionate, distearyl thiodipropionate (DSTDP), and pentaerythritol-tetrakis-
(Β-laurylthiopropionate) and 2-mercaptobenzimidazo.

In the present invention, 0.01 to 10 parts by weight, preferably 0.01 to 10 parts by weight, of at least one selected from these weathering agents is blended with 100 parts by weight of the polymer. The alkylphosphinic acid compound represented by the following general formula (1) is added in an amount of 0.01 to 10 parts by weight, preferably 0.01 to 10 parts by weight, based on the weathering agent. 8 parts by weight or more
By blending not more than parts by weight, heat resistance is imparted, the colorability is excellent, and the dust removing effect can be maintained for a long time.

[0020]

Embedded image (Wherein, R ¹ and R ² represent an organic group or a halogen atom, m and n each represent an integer of 0 to 4, and m or n represents 2 to 4)
R ¹ and R ² may be the same or different, respectively. A represents the same or different organic group as R ¹ and R ² . )

Specific examples of the alkylphosphinic acid compound include 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (HCA),
8-dichloro-9,10-dihydro-9-oxa-10
-Phosphaphenanthrene-10-oxide, and other chemical formulas (a) to (z) and (α) to (σ). In particular, 9,10-dihydro-9-oxa-10
-Phosphaphenanthrene-10-oxide is preferable because it has less bleed-out. If the amount is less than the range, the effect is small, and if the amount is more than the range, the effect is almost the same and bleed out tends to occur, which is not preferable.

[0022]

Embedded image

[0023]

Embedded image

[0024]

Embedded image

[0025]

Embedded image

[0026]

Embedded image

[0027]

Embedded image

Further, as the alkylphosphinic acid compound, other than the above, the compound represented by Chemical Formula 11 is also effective. Specifically, there are sodium phenylphosphinate, potassium phenylphosphinate, lithium phenylphosphinate, calcium phenylphosphinate, magnesium phenylphosphinate and the like.

[0029]

Embedded image (In the formula, R represents an alkyl group having 1 to 22 carbon atoms, a phenyl group, a naphthyl group, and an anthracene group, and X represents a metal ion, an ammonium ion, and a phosphonium ion.)

The fatty acid metal salt used in the present invention preferably has a linear fatty acid group. The fatty acid group preferably has 10 to 20 carbon atoms. For example, aluminum laurate, aluminum myristate, aluminum palmitate, aluminum stearate, magnesium laurate, magnesium myristate, magnesium palmitate, magnesium stearate, and the like can be given. The amount of addition is 0.1 to the polymer.
It may be from 01% by weight to 5% by weight, preferably 0.02% by weight and 1% by weight. Below this range, the effect is small. Conversely, above this range, bleed-out may occur.

The addition of the alkyl phosphinic acid compound and the fatty acid metal salt of the present invention has a high trapped charge amount at a high temperature side and is excellent in heat resistance, coloring property, and rigidity for stably retaining the charge for a long time. Although the exact cause is not yet known, mutual exclusion works due to the difference in compatibility between the alkyl phosphinic acid compound, the fatty acid metal salt and the polymer, and in particular, the fatty acid metal salt is pushed onto the polymer surface, resulting in electretization. It is presumed that the air-proofing agent easily interacts with these air-resistance imparting agents.

The electret properties of the high-molecular polymer to which the above-mentioned additives are added are excellent in thermal stability. Further, the surface charge density is 1.0 × 10 ⁻¹⁰ coulomb / cm ² or more, and the decrease is slight even when used under severe conditions for a long time.

When the electret material is used as a filter, the surface charge density is 1.0 × 10 ^-10 coulomb / c.
An electret material of at least m ² is desirable, more preferably at least 3.5 × 10 ⁻¹⁰ coulomb / cm ² .

The weather resistance of the high molecular weight electret material to which the above-mentioned compounding agent has been added is remarkably improved as compared with the conventional one, and there is no coloring during spinning and excellent heat stability.
In addition, there is almost no coloring after long use.

According to the present invention, a fiber aggregate, a so-called nonwoven fabric, may be directly electretized by a known method, or the fibers may be electretized and then nonwoven fabrics. It may be made into a nonwoven fabric later.

The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The melt-blown non-woven fabric is obtained by melt-blending a predetermined additive into a polypropylene resin by melt extrusion using a melter by a melt-blowing method so that the basis weight is 30 g / m ² , the average fiber diameter is 2.0 μm, and the thickness is 0.3 mm. The fiber was spun to obtain a nonwoven fabric.

The charging method for the nonwoven fabric obtained above is as follows. The nonwoven fabric is placed on an earth plate on which a semiconductor sheet is laid, and +20 Kv is applied to a needle electrode (charged electrode manufactured by Kasuga Electric Co., Ltd.) placed 1 cm above the earth plate. Was applied to generate corona positive ions, followed by electretization for 10 seconds.

The evaluation of the particle collection efficiency was performed using a DOP particle having a particle diameter of 0.3 μm by a particle collection efficiency measuring instrument shown in FIG. The electret nonwoven fabric 3 is installed in a duct, and the flow meter 4 is controlled by the valve 5 so that the filter ventilation speed becomes 5.3 cm / sec, and the number of DOP particles upstream and downstream of the electret nonwoven fabric is measured by a particle measuring device 7 (Co., Ltd.). It was measured by RION KC-14). The collection coefficient was calculated using Equation 1.

(Equation 1) Particle collection efficiency (%) = (1−number of downstream particles / number of upstream particles) × 100

The higher the particle collection efficiency, the better the performance of the electret nonwoven fabric as an air filter.

The surface charge density is determined by placing the nonwoven fabric on an earth plate, measuring the surface potential of the nonwoven fabric from above with a detection probe of a surface potentiometer (Surface potentiometer S-211 manufactured by Kawaguchi Electric Co., Ltd.), and 1 was calculated.

(Equation 2) Surface charge density (C / cm ² ) =
εs ・ εo ・ V / t

Here, εs is a relative dielectric constant of the electret nonwoven fabric of approximately 1, and εo is a vacuum dielectric constant of 8.8.
5 × 10 ⁻¹⁴ F / cm, V is the surface potential (V), and t is the thickness (cm) of the nonwoven fabric. The value of the surface charge density means the electrification amount of the electret nonwoven fabric, and a higher value indicates a higher electrification amount.

As for coloring, the state after use was visually judged, and no change was indicated by ◎, slight change was indicated by ○, change was indicated by △, and discolored was indicated by x.

Examples 1 to 6 show specific additives and their amounts, and Table 1 shows the amount of trapped charge, coloring and dust removal efficiency. In any case, by adding the alkyl phosphinic acid compound and the fatty acid metal salt, it has a high surface charge density on the high-temperature side, and has excellent heat resistance and colorability, which stably retain the charge for a long time. Understand. This electret material showed almost no change in performance even after 6 months had passed after production.

[0046]

[Table 1]

[0047]

[Table 2]

[0048]

[Table 3]

[0049]

[Table 4]

[0050]

[Table 5]

[0051]

[Table 6]

[0052]

According to the present invention, by adding an alkylphosphinic acid compound and a fatty acid metal salt, it has a high surface charge density on the high-temperature side, and has excellent heat resistance and colorability in which charges are stably retained for a long time. Understand. It is thought that some interaction with the weathering agent works.

[Brief description of the drawings]

FIG. 1 is a schematic view of a particle collection efficiency measuring device.

FIG. 2 is a schematic diagram of a surface potential measuring device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 DOP particle generator 2 Duct 3 Electret nonwoven fabric 4 Flow meter 5 Valve 6 Blower 7 Particle measuring instrument 8 Sampling tube 9 Surface electrometer 10 Ground plate 11 Surface potential detection probe

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) F24F 7/00 F24F 7/00 A F term (reference) 4D019 AA01 BA13 BB01 BB03 BC01 DA01 4J002 AA001 BB021 BB031 BB111 BB121 BC021 BC031 BD021 BD121 CF001 CG001 CL001 CN011 EG038 EG048 EJ016 EJ026 EJ036 EJ046 EN036 EU196 EW116 EW137 FD076 FD207 GD05 GQ00

Claims (5)

[Claims] 1. A high molecular weight polymer comprising 0.01 to 10 parts by weight of a hindered amine, a nitrogen-containing hindered phenol, a metal salt hindered phenol, a phenolic, and a hindered per 100 parts by weight of the polymer. A phenol-based, phenol-based sulfur-based weathering agent, at least one compound selected from the group consisting of the hindered amines,
Nitrogen-containing hindered phenol-based, metal salt hindered phenol-based, phenol-based, hindered phenol-based, phenol-based sulfur-based weathering agent 0.01 per part by weight
A heat-resistant electret material comprising 10 to 10 parts by weight of an alkylphosphinic acid compound represented by the following general formula (1) and a fatty acid metal salt. Embedded image (Wherein R ¹ and R ² represent an organic group or a halogen atom,
m and n each represent an integer of 0 to 4, and when m or n is an integer of 2 to 4, R ¹ and R ² may be the same or different. ) 2. The heat-resistant electret material according to claim 1, which has a surface charge density of 1.0 × 10 ⁻¹⁰ coulomb / cm ² or more. 3. The high volume polymer has a volume resistivity of 10 ¹² Ωcm.
The heat-resistant electret material according to claim 1, comprising: 4. A dust filter comprising the heat-resistant electret material according to claim 1 and having excellent insulating properties and chargeability. 5. A heat-resistant electret material, wherein the alkylphosphinic acid compound according to claim 1 is represented by the general formula (2). Embedded image (Wherein, R ¹ and R ² represent an organic group or a halogen atom, m and n each represent an integer of 0 to 4, and m or n represents 2 to 4)
R ¹ and R ² may be the same or different, respectively. A represents the same or different organic group as R ¹ and R ² . )