JP2003321581A - Antistatic rubber latex composition and antistatic rubber glove - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antistatic rubber latex composition stably holding carbon black as an antistatic agent in a rubber latex over a long period, and an antistatic rubber glove using the composition. <P>SOLUTION: The antistatic rubber latex composition is obtained by compounding a rubber latex with an acidic treated carbon black. Not only the resistivity of a film on the glove prepared therefrom can be reduced but also the composition can be stored for a longer period than that of the conventional composition without causing aggregation and gelation of the carbon black in the state of the composition. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an antistatic rubber latex composition and an antistatic rubber glove for preventing electrostatic damage.

[0002]

2. Description of the Related Art Rubber gloves are made of rubber latex with sulfur,
A vulcanizing agent or cross-linking agent such as zinc oxide, a vulcanization accelerator, an antioxidant, a pigment, and a thickener are added to a glove mold (or glove base material) by a coagulation method or a heat-sensitive method. It is manufactured by dipping or coating, heat-treating, and then releasing and leaching the product. At that time, as a countermeasure against static electricity, conductivity is introduced by kneading a surfactant, a plasticizer, etc. into the coating layer to reduce the surface resistivity and volume resistivity to a value smaller than × 10 ^9. There is.

[0003]

However, even if a surfactant, a plasticizer or the like is internally added to the coating layer as described above, it is easily extracted during leaching or during work of handling oil or solvent, and has a low resistivity. Is difficult to maintain. Further, since the resistivity depends on the humidity, the antistatic effect becomes insufficient in the low humidity period when static electricity is likely to occur in winter.

Therefore, it is considered that carbon black, which has been widely used in recent years as an antistatic agent, is kneaded into the coating layer. Carbon black can lower the resistivity with a relatively small addition amount, and with the same addition amount, D
It is well known that carbon black having a larger BP (dibutyl phthalate) oil absorption amount or specific surface area has a larger effect of lowering the resistivity.

However, if the amount of carbon black added is increased in order to obtain a large antistatic effect, the glove film becomes hard and loses its flexibility, and there is a problem in workability that it is difficult to grasp an object. Further, carbon black has poor processability after being added to latex, and has a problem of processability that it becomes an aggregate or gel in a relatively short period of time.

The present invention solves the above-mentioned problems, and carbon black as an antistatic agent can be stably held in a rubber latex for a long period of time, and the resistivity can be effectively reduced by adding a small amount of carbon black. An object is to provide an antistatic rubber latex composition and an antistatic rubber glove using the same.

[0007]

In order to solve the above problems, the present invention provides an antistatic rubber latex composition in which rubber latex is mixed with acid-treated carbon black. Not only the resistivity of the film can be lowered, but also the composition can be stored for a long period of time without causing aggregation and gelation of carbon black in the composition state.

Further, the antistatic rubber latex composition is blended with polyvinyl alcohol or polyether modified silicone, and the amount of acid-treated carbon black added can be reduced to give the coating flexibility. Addition amount of polyvinyl alcohol is rubber latex 1
About 1 to 20 parts by weight, preferably 5 parts by weight or less is suitable for 100 parts by weight, and if it is more than this range, the film strength becomes insufficient. An appropriate amount of the polyether-modified silicone added is about 0.1 to 5 parts by weight, preferably 0.5 parts by weight or less, based on 100 parts by weight of the rubber latex. If the amount is larger than this, the stability of the compound becomes insufficient. And may cause agglomeration and gelation.

The rubber latex used in the present invention includes natural rubber, isoprene, chloroprene, acrylic acid ester, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, urethane, butyl rubber, polybutadiene rubber, silicone rubber, etc. A homopolymer, a copolymer, or a latex of 10% by weight or less of a copolymer having a carboxyl-modifying group is blended to form a well-known crosslinking agent, vulcanization accelerator, antioxidant, thickener, organic or Inorganic fillers, plasticizers, etc. are added.
It is possible to use the degree of polymerization, the mixing ratio, and the amount of addition of additives within the range conventionally used for gloves.

The above-mentioned natural rubber means not only natural rubber alone but also latex such as natural rubber-methyl methacrylate copolymer and epoxidized modified natural rubber copolymer. The term "acrylic ester" refers to n-butyl acrylate, n-butyl methacrylate, iso.
-Butyl acrylate, iso-butyl methacrylate, ethyl acrylate, ethyl methacrylate, 2-
Ethylhexyl acrylate, 2-ethylhexyl methacrylate, iso-propyl acrylate, iso-
Means a homopolymer such as propyl methacrylate, or a copolymer, acrylonitrile, methyl methacrylate,
It includes a copolymer containing allyl methacrylate, N-methylol acrylamide, acrylic acid, methacrylic acid and the like.

The acid-treated carbon black has a pH <7 in which oxygen functional groups such as a phenol group, a carbonyl group, a carboxyl group and a lactone are added to the surface of the carbon black by oxidation treatment such as gas phase oxidation or liquid phase oxidation. . The larger the DBP oil absorption amount, the more effectively the resistivity can be lowered with a small addition amount.

The polyvinyl alcohol may be a completely saponified product or a partially saponified product, and may have a silanol-, carboxyl-, or thiol-modified part. As the polyether-modified silicone, for example, a copolymer of ethylene oxide and propylene oxide having a polysiloxane content of 5% by weight or less can be used. Preferably, the ratio of ethylene oxide and propylene oxide is 50% by weight / 50% by weight to 40% by weight / 60% by weight
It is a ratio of.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to examples. (Examples 1 to 7) As shown in Table 1, acid-treated carbon black (C
B) 20 parts by weight of the compound, and 0.12 parts by weight of polyether-modified silicone (TPA4380, Toshiba Silicone Co., Ltd./TPA)), the first polyvinyl alcohol (P).
VA117, Kuraray Co., Ltd., saponification degree 95-99 mol
%, Polymerization degree 1700 / PVA (I)) 1 part by weight of a compound added with the second polyvinyl alcohol (P
VA217, Kuraray Co., Ltd., saponification degree 76-89 mol
%, Polymerization degree 1700 / PVA (II)) 1 part by weight of the compound added.

Formula 1 and Formula 2 are as follows:
The acid-treated carbon blacks of Examples 1, 2 and 6, Examples 3 and 7, Examples 4 and 5 have carboxyl, carbonyl, lactone, and phenol functional groups, respectively.

[Compound 1] NBR latex (Nippon Zeon Corporation Lx550) 100 parts by weight G-15 (Kao Corporation anionic emulsifier) 0.2 parts by weight Colloidal sulfur 1.5 parts by weight Zinc oxide 1.5 parts by weight Part Vulcanization accelerator (dithiocarbamate type) 0.5 part by weight Anti-aging agent (bisphenol type) 0.5 part by weight Pigment appropriate amount Thickener (polyacrylic ester type) appropriate amount [Compound 2] NR latex 100 parts by weight G -15 (Kao Corporation anionic emulsifier) 0.2 parts by weight Colloidal sulfur 1.0 parts by weight Zinc oxide 0.8 parts by weight Vulcanization accelerator (dithiocarbamate type) 0.3 parts by weight Anti-aging agent (bisphenol type) ) 0.5 parts by weight Pigment Appropriate amount Thickener (sodium alginate) Appropriate amount (Comparative Examples 1 to 5) Rubber latex having the composition shown in Table 1, untreated carbon black not subjected to acid treatment Use the,
The compounds of Comparative Examples 1 to 5 were prepared. (Test) Each of the compounds of Examples 1 to 7 and Comparative Examples 1 to 5 was placed in a reaction container and stirred at 120 rpm with a three-one motor stirrer in a water bath at a liquid temperature of 30 ° C. to stabilize with or without aggregates and gelation. Tested for sex. The results are shown in Table 1.

[0016]

[Table 1] As can be seen from Table 1, all the compounds of Comparative Examples 1 to 5 caused gelation after 2 days, while Examples 1 to 1
Each compound of No. 7 was very stable without forming aggregates and gelation even after 1 week. Polyether-modified silicone (TPA), polyvinyl alcohol (PVA (I)
) And the addition of polyvinyl alcohol (PVA (II)) did not impair the stability. (Example 8) As shown in Table 2, a compound obtained by adding 10, 20, 30, 40 parts by weight of the same acid-treated carbon black (CB) as that used in Example 2 to the rubber latex of the compound 1 respectively. , 20 parts by weight of acid-treated carbon black and polyether modified silicone (TPA)
0.12 parts by weight of the compound, 20 parts by weight of acid-treated carbon black and polyvinyl alcohol (P
VA (I)) 1 part by weight, a compound containing 20 parts by weight of acid-treated carbon black and 1 part by weight of polyvinyl alcohol (PVA (II)), a total of 7 types of compounds were prepared individually. .

Each compound prepared (1000 g)
Then, preheat to 60 ° C and coagulant (100 parts by weight of methanol:
Dip a pottery mold soaked in 50 parts by weight of calcium nitrate) and pull up the pottery mold to face upward at 75 ° C x 60
Heat treatment for 120 minutes x 60 minutes,
After cooling sufficiently, reversal release, leaching at 30 ° C. × 1 hour, and drying at 75 ° C. × 20 minutes were performed to prepare a glove. (Example 9) A compound was prepared in the same manner as in Example 8 except that the same acid-treated carbon black as that used in Example 3 was used, and a glove was produced from each compound. (Example 10) A compound was prepared in the same manner as in Example 8 except that the compound 2 was used, and a glove was produced from each compound. (Example 11) A compound was prepared in the same manner as in Example 9 except that the compound 2 was used, and a glove was produced from each compound. (Comparative Example 6) Acid-treated carbon black was not added 4
Type of compound, ie compound consisting of blend 1, blend 1 with TPA = 0.12 parts by weight, PVA (I)
= 1 part by weight, or PVA (II) = 1 part by weight, a compound was prepared, and a glove was produced from each compound. (Comparative Example 7) No addition of acid-treated carbon black 4
Type of compound, ie compound consisting of formulation 2, TPA = 0.12 parts by weight in formulation 2, PVA (I)
= 1 part by weight, or PVA (II) = 1 part by weight, a compound was prepared, and a glove was produced from each compound. (Test) A test piece of 10 cm × 10 cm was cut out from each glove produced in Examples 8 to 11 and Comparative Examples 6 and 7, and the humidity was set to 4
Under the conditions of 7% and room temperature of 24 ° C., the surface resistivity (Ω / sq) which is the resistivity in the surface direction and the volume resistivity (Ω · cm) which is the resistivity in the volume direction are measured by Monro Electronics, Model 272.
It was measured with an A measuring machine. Further, four test pieces per one glove were punched out with dumbbell No. 3, and 100% modulus was measured according to JIS K6301. The results are shown in Table 2. It is evaluated that the lower the resistivity, the better the electrical conductivity and the greater the antistatic effect. The lower the 100% modulus value, the more flexible it is evaluated.

[0018]

[Table 2] As can be seen from Table 2, Example 8, Example 9, and Example 1
0, in Example 11, as the amount of acid-treated carbon black added increased, the surface resistivity and volume resistivity decreased and the antistatic effect increased, while the 100% modulus increased and the coating became harder.

In Examples 8 and 9 using Formulation 1, 20 parts by weight of acid-treated carbon black and TP
A = 0.12 parts by weight, PVA (I) = 1 part by weight, or P
The surface resistivity and volume resistivity of the glove obtained by adding VA (II) = 1 part by weight are almost the same as those of the glove obtained by adding about 40 parts by weight of acid-treated carbon black, The 100% modulus value is quite low.

Similarly, in Examples 10 and 11 using Formulation 2, 20 parts by weight of acid-treated carbon black, TPA = 0.12 parts by weight, PVA (I) = 1 part by weight, or PVA ( II) = 1 part by weight, the surface resistivity and volume resistivity of the glove made of the compound are almost the same as those of the glove made of the compound added with about 30 parts by weight of acid-treated carbon black, but 100%. The modulus value is quite low.

In Comparative Examples 6 and 7, TPA =
0.12 parts by weight, PVA (I) = 1 part by weight, or PVA
Even if 1 part by weight of (II) is added, the surface resistivity, volume resistivity and 100% modulus value are almost the same as when not added, and TPA, PVA (I) or PVA (II) alone is added. In other words, it can be seen that the resistivity does not decrease when the acid-treated carbon black is not added. (Example 12) A seamless nylon knit glove was attached to a glove mold as a base material, and the compound of Example 2 (compound 1,
Acid-treated carbon black (20 parts by weight, PVA (II) 1 part by weight) is applied, and the temperature is 75 ° C. for 60 minutes, then 120 ° C.
After heat treatment for 60 minutes and cooling to room temperature, the gloves were removed from the glove mold, subjected to warm water leaching at 30 ° C. × 60 minutes, and dried at 75 ° C. × 40 minutes to prepare rubber gloves with a back cloth. (Example 13) A seamless mixed nylon knitted glove in which conductive fibers and non-conductive fibers are mixed and knitted in a glove mold (Sunderlon SS-N yarn (conductive fiber manufactured by Japan Silkworm Co., Ltd.))
And gloves are woven with nylon yarn in a ratio of 2: 1 and immersed in a coagulant, and then the compound of Example 2 (compound 1, acid-treated carbon black 20 parts by weight, PVA (I
I) 1 part by weight), and after pulling up, heat treatment was carried out at 75 ° C. for 60 minutes and then at 120 ° C. for 60 minutes. After cooling to room temperature, remove from the glove mold, 30 ℃ x 6
After leaching for 0 minutes in warm water and drying for 40 minutes at 75 ° C., a rubber glove with a back cloth was produced. (Test) For each glove of Example 12 and Example 13, the surface resistivity (Ω / sq) was performed in the same manner as described above.
And the volume resistivity (Ω · cm) were measured. The results are shown in Table 3.
Shown in.

[0022]

[Table 3] As can be seen from Table 3, even in the gloves with the back cloth produced in Examples 12 and 13, the surface resistivity and the volume resistivity are x1.
The value was lower than ^09, and the target antistatic effect was obtained.

It should be noted that the above-mentioned embodiments are merely examples and are not intended to limit the present invention. The term “parts by weight” can be read as “parts by weight”.

[0024]

As described above, according to the present invention, by using an acid-treated product in the carbon black to be added to the antistatic rubber latex composition as an antistatic agent, the composition can be stored in a composition state for a relatively long period of time. Even carbon black agglomeration,
Gelation does not occur and stable processing is possible. By adding polyvinyl alcohol or polyether-modified silicone in addition to acid-treated carbon black, the amount of acid-treated carbon black up to the desired resistivity can be suppressed compared to when added alone, and the glove coating can be made flexible. It is possible to improve workability.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C09K 3/16 101 C09K 3/16 101B F term (reference) 3B033 AB10 AB14 AC03 4J002 AC011 AC031 AC061 AC071 AC081 AC091 BE022 BG041 CK021 CP031 CP182 DA036 FD102 FD106

Claims (4)

[Claims] 1. An antistatic rubber latex composition for gloves, wherein the rubber latex is blended with acid-treated carbon black. 2. An antistatic rubber latex composition comprising a rubber latex blended with acid-treated carbon black and polyvinyl alcohol. 3. An antistatic rubber latex composition comprising a rubber latex blended with acid-treated carbon black and a polyether-modified silicone. 4. An antistatic rubber glove obtained by heat molding using the antistatic rubber latex composition according to any one of claims 1 to 3.