JPH06172657A - Latex composition excellent in antistatic properties - Google Patents

Abstract

PURPOSE:To provide the subject composition containing a latex, a smectite-based clay mineral and a condensed phosphate salt in a specified ratio, excellent in antistatic properties and useful, e.g. as a filler for a coating material in the fields of textile industry or coating material. CONSTITUTION:The objective composition contains (A) 100 pts.wt. latex, (B) 5 to 50 pts.wt. smectite-based clay mineral (e.g. hectorite) and (C) a condensed phosphate (e.g. pyrophosphate) in an amount of 3 to 10 pts.wt. based on 100 pts.wt. component (B).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a latex composition having a smectite clay mineral as an active ingredient and having an excellent antistatic property, and is useful in the fields of textile processing and coatings.

[0002]

2. Description of the Related Art Latex generally has a diameter of 0.1 to 10.
A spherical polymer having a diameter of about 0.5 μm is dispersed in water. The constituent components are roughly divided into latex particles and an aqueous phase. The latex particles are formed of polymer particles and a protective layer, and the polymer particles may be simply composed of a polymer or may occlude a film forming aid or a plasticizer. The protective layer is divided into an adsorption protective layer and a chemical adsorption protective layer, and the adsorption protective layer is formed by adsorbing a surfactant or a water-soluble polymer in the aqueous phase. The chemical adsorption protection layer is formed by chemically bonding various hydrophilic groups to the polymer particles.

On the other hand, the aqueous phase is added with water, a surfactant used for emulsion polymerization, a water-soluble polymer and an electrolyte (mainly a polymerization initiator), oligosoap or water-soluble polymer produced in the polymerization process, and if necessary. It is composed of a solvent. Of these, the surfactant having surface activity and the water-soluble polymer maintain adsorption equilibrium with those of the protective layer. Dispersion stability of the polymer particles in water is due to the function of the protective layer, which is divided into an electric double layer and a steric hindrance of the hydration layer depending on the adsorbed water-soluble substance and the hydrophilic group to be bonded.

Types of latex include natural latex, synthetic latex and artificial latex. Natural latex is an emulsion of a polymer produced in nature and is limited to natural rubber latex. Synthetic latex refers to a synthetic polymer emulsion produced by emulsion polymerization, and examples thereof include polymer emulsions such as styrene-butadiene rubber, acrylonitrile, butadiene, and vinyl chloride. Artificial latex is a emulsion that cannot be produced by emulsion polymerization, but after it is produced by another polymerization method, it is artificially emulsified using an emulsifier, etc.
It is a version of the Day Sparge. Examples of this type of latex include isoprene rubber, butadiene rubber, urethane resin and the like.

Further, the characteristics of the latex are: (l) Since it is basically formed of polymer particles and water, it is easy to handle and safe. (2) Since the viscosity of latex depends on the size of particles at a constant concentration, the viscosity does not increase even if the molecular weight is increased. Therefore, it becomes possible to polymerize and improve the performance such as adhesiveness. Further, it is possible to increase the concentration by enlarging the particles.

Taking advantage of these advantages, latex is used in various fields such as adhesives, paints, fiber processing, tire cords, etc. , "Emulsion Latex Handbook," published by Taisei Co., Ltd.).

[0007]

However, since the latex is composed of polymer particles and water as described above, it has the same characteristics as ordinary polymer products after drying. Generally, a polymer product has a volume resistivity of more than 10 ¹³ Ωcm and a surface resistivity of more than 10 ¹³ Ω, and its electrical insulation is one of the characteristics of the polymer product.

Although this feature has greatly contributed to the expansion of demand for polymer products, on the other hand, electrostatic damage due to electrification occurs. For example, in the field of paints, stains are attached after painting, and the value of the product is remarkably reduced in appearance.

In order to solve such a problem, it is generally conceivable to use a conductive surfactant, but latex has a risk of impairing its dispersion stability and is not in practical use.

As described above, a latex composition having an excellent antistatic property has not yet been obtained, and such a latex composition has been strongly demanded.

From this point of view, the present invention has been made for the purpose of obtaining a latex composition having excellent antistatic properties without impairing the original characteristics of the latex.

[0012]

Means and Actions for Solving the Problems The present inventors have
As a result of accumulated research, latex contains smectite-based clay minerals and further contains a fixed proportion of condensed phosphate with respect to the contained smectite-based clay minerals, thereby impairing the original characteristics of latex described above. The inventors have found that the object of obtaining a latex composition having excellent antistatic properties can be achieved without any problem, and have completed the present invention.

That is, the feature of the present invention is that latex 10 is used.
5 to 50 of smectite clay mineral to 0 part by weight
10 parts by weight of the smectite clay mineral 10
3 to 10 parts by weight of the condensed phosphate is contained in 0 part by weight.

The latex used in the present invention is not particularly limited, and any one exhibits an antistatic effect.

The smectite clay mineral added to the latex in the present invention has the following general formula:

[0016]

[Chemical 1]

Is a clay mineral having This clay mineral naturally occurs, but it is also available as a synthetic product. Examples of smectite clay minerals include montmorillonite, sauconite, banderite, and hectorite, and any of them may be used, but hectorite is particularly preferable. Further, either a natural product or a synthetic product may be used.

Each layer of the crystal structure in the layered structure of such a smectite clay mineral forms a two-dimensional plate-like shape having a thickness of about 1 mμ, and the magnesium atom and the aluminum atom present in this plate-like unit are lower. It is isomorphic with the atoms of the valence cation, and the platelet unit is negatively charged. In the dry state, this negative charge balances the displaceable cations (usually sodium ions) outside the lattice structure of the plate surface, and in the solid layer these particles are bound together by the van der Waals force to form a bundle of flat plates. There is.

When this is dispersed in latex, the replaceable cations are hydrated and the particles swell and the platelets separate. In an ionic state such as water, the platelets have a negative surface charge and the edges have a positive charge. A stable sol state is obtained under conditions where the surface negative charge is much larger than the edge positive charge. However, the repulsive force due to the surface negative charges decreases due to the increase in the particle concentration and the ion concentration, and the so-called card house structure is formed by the attraction of the surface negative charges and the edge positive charges to cause thickening or gelation. When such a phenomenon occurs, the ease of handling, which is a characteristic of latex, is impaired.

On the other hand, when attention is paid to the antistatic property, the higher the concentration of the smectite clay mineral, which is the conductive particle, the more effective it is. In order to solve this contradictory problem, it is necessary to use a deflocculant, which is a condensed phosphate.
Although it is not known, the condensed phosphate ion-dissociates in the latex to form a phosphate ion which is a large anion and a metal cation such as sodium or a cation such as ammonium ion. This phosphate ion electrically adsorbs to the positively charged portion at the end and inhibits the formation of the card house structure, and thus acts as a peptizing agent. Therefore, it becomes possible to add the smectite-based clay mineral to the latex while suppressing the increase in viscosity, and to provide an excellent antistatic effect.

In order to obtain a latex composition having excellent antistatic properties, it is preferable to contain 5 to 50 parts by weight of smectite clay mineral per 100 parts by weight of latex. If it is less than the above range, the antistatic effect is inferior, and if the smectite clay mineral is contained in excess of the above range, the amount of clay rises and the workability deteriorates.

The condensed phosphate is preferably contained in an amount of 3 to 10 parts by weight based on 100 parts by weight of the smectite clay mineral. If the amount is less than the above range, it becomes difficult to mix the smectite clay mineral at a high concentration, and the antistatic effect becomes poor. If the condensed phosphate is contained in excess of the above range, the dispersion stability of the latex may be impaired, which is not preferable.

As the condensed phosphate, for example, sodium pyrophosphate, potassium pyrophosphate, sodium tripolyphosphate, potassium tripolyphosphate, sodium hexametaphosphate and the like can be used, but the pyrophosphate is particularly preferable.

To the latex composition of the present invention, in addition to the above-mentioned essential components, vulcanizing agents, vulcanization accelerators and the like, which are usually added to this type of composition, can be added, if necessary.

The latex composition of the present invention can be preferably used for the use of latex required to have antistatic properties, and particularly preferably used as a filler for textile processing and paints.

[0026]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. In addition, viscosity measurement, test piece creation,
The measurement of electrical characteristics and the like were performed according to the following methods.

(Viscosity measurement) A predetermined amount of smectite clay mineral, condensed phosphate and vulcanizing agent was mixed with latex by a high speed mixer at 1000 rpm for 20 minutes, and then left at room temperature for 2 hours. Then, the viscosity was measured by a BL type viscometer (measurement temperature was 25 ° C., BL type viscometer 12
rpm value).

(Preparation of test piece) The composition was poured into a mold having a certain shape, and the NR latex was at 60 ° C.
24 hours, and the CR latex was vulcanized at 80 ° C. for 20 hours to prepare test pieces.

(Measurement of electrical characteristics) 4329A HIGH RE
SISTANCE METER (made by Yokogawa Hewlet Patz Card Co., Ltd.)
Was used to measure the surface resistivity.

(Appearance of coating film) The appearance of the latex coating film was judged by visual observation and indicated by ◯ and ×.

Example 1 100 parts by weight of NR latex (N.V. 60%) 5 parts by weight of a conjugated hectorite clay mineral containing 6% of sodium pyrophosphate (trade name Laponite S: manufactured by Lapolte Industries Ltd), a vulcanizing agent (S 1.3, ZnO; 1.0, BZ (vulcanization accelerator; zinc dibutylthiocarbamate); 4.0,
Water; 5.0, Vimotal (dispersant); 0.5, casein; 0.15 ... ・ Ball mill 72 hours mixed product) 3.
3 parts by weight were mixed, a test piece was prepared according to the above method, and an evaluation test was performed. The results are shown in Table 1.

Example 2 The compounding amount of the synthetic hectorite clay mineral used in Example 1 was changed to 50 parts by weight, and thereafter a test piece was similarly prepared and an evaluation test was carried out. The results are shown in Table 1.

Example 3: 100 parts by weight of CR latex (Skyprene latex LA-502: manufactured by Tosoh Corporation),
Synthetic smectite clay mineral containing 6% sodium pyrophosphate (trade name Laponite S: manufactured by Laporte Lndustries Ltd)
50 parts by weight, vulcanizing agent (water; 20, hard clay; 5.
0, ZnO; 5.0, S (colloid); 1.0, D (antiaging agent; 1,3-diphenylguanidine); 2.0,
NS6 (antiaging agent; 2,2'-methylenebis (4-methyl 6-tert-butylphenol)); 1.0, BZ
(Vulcanization accelerator); 1.0 ... Ball mill 72 hours mixed product) 9 parts by weight were mixed, and a test piece was prepared according to the above method, and an evaluation test was performed. The results are shown in Table 1.

Comparative Example 1: Sodium pyrophosphate 6 in Example 1
%, The compounding amount of the synthetic hectorite clay mineral was changed to 60 parts, and thereafter, a test piece was similarly prepared and an evaluation test was performed. The results are shown in Table 1.

Comparative Example 2: Sodium pyrophosphate 6 in Example 1
%, A synthetic hectorite clay mineral containing no sodium pyrophosphate (trade name Laponite B: manufactured by Lapolte Industries Ltd) was used in place of the synthetic hectorite clay mineral containing 100%, and the test pieces were prepared in the same manner as above for the evaluation test. Carried out. The results are shown in Table 1.

Comparative Example 3: In Example 1, the content of sodium pyrophosphate was changed from 6% to 15%, and the other test pieces were similarly prepared and the evaluation test was carried out. The results are shown in Table 1.

[0037]

[Table 1]

[0038]

As is apparent from the above description, according to the present invention, it is possible to provide a latex composition having excellent antistatic properties without causing the problem of impairing the characteristics of the latex due to thickening or gelation. There is an effect.

Claims (1)

[Claims] 1. A latex containing 100 to 5 parts by weight of a smectite-based clay mineral, and 100 parts by weight of a smectite-based clay mineral to 3 parts of a condensed phosphate.
To 10 parts by weight, which is excellent in antistatic property, latex composition