JPH10298295A - Aqueous dispersion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous dispersion which has good storage stability and can form a coating film excellent in antistatic properties, water resistance, etc., when applied to a substrate. SOLUTION: This dispersion comprises an aqueous dispersion (A) containing a potassium salt of an ethylene/(meth)acrylic acid copolymer having a (meth) acrylic acid content of 10-30 wt.% and a melt flow rate of 1-1,500 g/10 min (at 190 deg.C under a load of 2,160 g) and having a degree of neutralization of 75% or above and having a solids concentration of 2-50 wt.% and an aqueous polymer dispersion (B) having a mean particle diameter of 1 nm 20 μm as measured by light scattering, a solids concentration of 2-60 wt.% and a pH of 7 or above in an A/B ratio of 1/99 to 99/1 in terms of the weight of the solid content.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an aqueous dispersion capable of forming a coating film having excellent antistatic properties.

[0002]

2. Description of the Related Art Conventionally, various aqueous dispersions in which fine particles of various polymer compounds are dispersed in water have been developed and used as coating agents and adhesives. In applications where the adhesion of dirt and dust on the coating film is particularly unfavorable, it is desired that the coating film formed from such an aqueous dispersion has antistatic properties. However, most polymer compounds do not have sufficient antistatic properties, and thus coating films from aqueous dispersions containing no surfactant often do not have sufficient antistatic properties. In addition, in the case of a coating film from an aqueous dispersion containing a surfactant, although the surfactant may be incorporated into the film and exhibit antistatic properties, contamination of the film surface due to bleeding of the surfactant and volatilization of the surfactant may occur. There was a problem such as a decrease in antistatic property with time due to the loss, and it could not be said to be sufficiently satisfactory.

As one of such aqueous dispersions of polymer compounds, those based on an ionomer of an ethylene / (meth) acrylic acid copolymer have been known for a long time, and there have been many proposals for their use. It has been done. It is also known that an ionomer having a large (meth) acrylic acid content and a sufficiently large degree of neutralization can be a sufficiently stable aqueous dispersion without using a surfactant. Most of the aqueous dispersions in these proposals are mainly intended for aqueous dispersions using sodium ions or ammonia ions as an ion source, and mention the possibility of using potassium ions as an ion source. Many are used, but there are not many specific examples. A coating film obtained from an aqueous dispersion using sodium ions or ammonium ions as an ion source usually does not have sufficient antistatic properties.

However, among aqueous ionomer dispersions using potassium ions as an ion source, a coating film formed from one having a high (meth) acrylic acid content and a high degree of neutralization exhibits sufficient antistatic properties. Are known (see, for example, JP-A-60-240704 and JP-A-4-33984).
9, JP-A-8-231791), on the other hand, has the drawback that the water resistance of the coating film is poor, causing problems such as slimming and whitening of the coating film, and the field of use thereof is limited. You. In addition, the flexibility of the coating film is inferior, the coating film may be cracked by deformation, and the adhesion to polyester and polyolefin is poor. Heretofore, there has been almost no proposal for improving all of the above-mentioned disadvantages without impairing the antistatic property of a coating film formed from such a potassium ionomer aqueous dispersion.

[0005]

In view of such a situation, the present inventors mix an aqueous dispersion of a potassium ionomer as described above with an aqueous polymer dispersion in which a coating film does not exhibit antistatic properties. In this way, an attempt was made to impart antistatic properties to the coating film and at the same time to improve the properties of the coating film from the potassium ionomer aqueous dispersion. However, depending on the properties of the polymer compound aqueous dispersion, the mixture of the two does not become a stable aqueous dispersion, and even when a stable aqueous dispersion is obtained by mixing both, the antistatic property of the coating film is imparted. In view of this, the antistatic property cannot be imparted unless a considerable amount of potassium ionomer is blended, and thus the excellent properties inherent in the polymer compound coating film may be sacrificed in some cases. Also, from the viewpoint of improving the properties of the potassium ionomer coating film, it was found that sufficient improvement could not be achieved in some cases by blending a small amount of the aqueous polymer dispersion.

The present inventors have further studied these mixed systems. As a result, by appropriately selecting the properties and blending ratios of the aqueous dispersions of both, the present invention has antistatic properties and other excellent properties. It has been found that a mixed aqueous dispersion capable of forming a coating film having characteristics can be obtained. Therefore, an object of the present invention is to provide a mixed aqueous dispersion having excellent storage stability and capable of forming a coating film having antistatic properties and other excellent properties.

[0007]

According to the present invention, a (meth) acrylic acid content is 10 to 30% by weight and a melt flow rate (190 ° C., 2160 g load) is 1 to 1500 g / 10
% Of the potassium salt having a degree of neutralization of the ethylene / (meth) acrylic acid copolymer of 75% or more for 2 minutes to 50% by weight
An aqueous polymer dispersion (A) having an average particle diameter of 1 nm to 200 μm, a solid content concentration of 2 to 60% by weight, and a pH of 7 or more, as measured by a light scattering method, The present invention relates to an aqueous dispersion containing (A) / (B) in a weight ratio of 1/99 to 99/1. (Here (meta)
Acrylic acid refers to acrylic acid or methacrylic acid. )

[0008]

DETAILED DESCRIPTION OF THE INVENTION The aqueous ionomer dispersion (A) used in the present invention has a (meth) acrylic acid content of 10 to 30.
It is an aqueous dispersion of a potassium salt in which the degree of neutralization of the ethylene / (meth) acrylic acid copolymer by weight with potassium ion is 75% or more, preferably 80 to 100% by weight, preferably 15 to 25% by weight. The copolymer may be a copolymer obtained by copolymerizing other monomers such as (meth) acrylic acid ester in addition to ethylene and (meth) acrylic acid. Such other monomers are copolymerized, for example, in amounts of up to 20% by weight.

If a copolymer having a (meth) acrylic acid content less than the above range is used, it is difficult to obtain a dispersion having good water dispersibility and it is difficult to obtain a coating film having good antistatic properties. . On the other hand, if a copolymer having a (meth) acrylic acid content higher than the above range is used, not only is it not possible to obtain a stable dispersion, but also the water resistance and mechanical strength of the coating film are undesirably reduced. If the degree of neutralization with potassium ions is smaller than the above range, it becomes difficult to obtain a coating film having good antistatic properties.

The ethylene / (meth) acrylic acid copolymer is considered to be 19 in consideration of water dispersibility, coating film strength and the like.
0 ° C, melt flow rate at 2160g load is 1
~ 1500g / 10min, especially 50 ~ 1000g / 10
It is preferable to use one for a minute.

The above-mentioned aqueous potassium ionomer dispersion can be easily obtained by stirring an ethylene / (meth) acrylic acid copolymer and potassium hydroxide in water at a temperature not lower than the melting point of the copolymer. . The solid content in the aqueous dispersion is 2 to 50% by weight, particularly 5 to 50% in consideration of easiness of production of the aqueous dispersion, stability, economy and the like.
It is desirable to adjust to about weight%.

The aqueous dispersion (B) used in the present invention comprises:
It has a pH of 7 or more and has an average particle size of 1 nm to 200 μm, preferably 5 to 20 μm, as measured by a light scattering method.
And a solid concentration of 2 to 60% by weight, preferably 5 to 60% by weight.
It is 50% by weight. PH of aqueous dispersion (B) is 7
If less than this is used, gelling occurs when blended with the aqueous dispersion (A), and a good aqueous dispersion cannot be obtained. In addition, an aqueous dispersion having a pH of less than 7 can be used as a stable aqueous dispersion by adjusting the pH to 7 or more with a basic aqueous solution such as aqueous ammonia. It is adjusted above.

When an aqueous dispersion having an average particle size of more than 200 μm is used, it cannot be uniformly blended with the aqueous dispersion (A), so that unevenness and cracks occur in the coating film, which is not preferable. If the solid concentration is too high, it is difficult to mix with the aqueous dispersion (A).

Specific examples of the aqueous dispersion (B) include polyvinyl acetate, ethylene / vinyl acetate copolymer, acrylic resin, styrene / acrylic copolymer, and a copolymer of three or more of these, SBR, BR, MBR, NBR, C
R, urethane resin, urethane / acrylic copolymer, urethane / vinyl copolymer, silicone resin, silicone
"Emulsion market analysis and manufacturer strategy", including acrylic copolymers, epoxy resins, epoxy-acrylic copolymers, fluororesins, polyvinyl chloride, polyvinylidene chloride, and aqueous dispersions of vinylidene chloride-acrylic copolymers (Mc Planet Business Division, 1994). Furthermore, polyacrylamide resins (Polystron: Arakawa Chemical Industries), polyamide resins (Alafix: Arakawa Chemical Industries), vinylidene chloride resins (Crehalon: Kureha Chemical Industry), polyester resins (Peselezine: Takamatsu Yushi), chlorine Polypropylene (HARDDEN: Toyo Kasei Kogyo), polyethylene (Chemipearl: Mitsui Petrochemical), ethylene-propylene copolymer (Chemipearl: Mitsui Petrochemical), and other styrene resins, polyethylene oxide resins, and chlorinated polyethylene resins Water dispersions such as resins, EPDM resins, phenolic resins, maleic anhydride-grafted polypropylene, maleic anhydride-grafted polyethylene, and maleic anhydride-grafted polypropylene-ethylene copolymers can also be used. These can be used in combination of two or more.

The mixing ratio of the aqueous dispersions (A) and (B) is
1/99 to 99/1, preferably 5/9 by solid content weight ratio
Although it is 5 to 95/5, when it is desired to make the best use of the performance of the potassium ionomer coating film, the ratio of (A) to (B) should be 50/50 to 99/1, particularly 60/4.
The ratio is preferably from 0 to 95/5, and if it is desired to make the best use of the properties of the coating film of the aqueous polymer dispersion, the ratio should be 1/99 to 50/50, especially 5/95 to 30.
The ratio is preferably / 70.

The mixed aqueous dispersion of the present invention can be prepared by mixing the aqueous dispersions (A) and (B) with stirring. In this case, there is no particular need for heating. Alternatively, the base resins (A) and (B) may be melt-blended or dry-blended in advance and then dispersed in water. In any case, the present invention is not limited by such a manufacturing method.

In the aqueous dispersion (A) and the aqueous dispersion (B), an optional additive can be blended with one or both or after mixing both. As such additives, glycerin, polyethylene glycol,
Polyhydric alcohols such as polypropylene glycol,
Water-soluble epoxy compounds, methanol, ethanol, monoalcohols such as isopropyl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether,
Ethers such as diethylene glycol monoethyl ether and dipropylene glycol monomethyl ether, esters such as propylene glycol monoacetate and ethylene glycol monoacetate, pigments, dyes, antioxidants, ultraviolet absorbers, light stabilizers, lubricants, and antiblocking Agents, plasticizers, preservatives, defoamers, thickeners, antibacterial agents and the like.

The aqueous dispersion composition obtained in the present invention has excellent storage stability and is useful as a coating material for various substrates. As a substrate to which such an aqueous dispersion can be applied, for example, high, medium, low density polyethylene,
Ethylene / α-olefin copolymer, ethylene / vinyl acetate copolymer, ethylene / (meth) acrylate copolymer, ethylene / (meth) acrylic acid copolymer or its ionomer, ethylene / (meth) acrylic acid・
(Meth) acrylate copolymer or its ionomer, polypropylene, poly-1-butene, poly-4
Olefin polymer or copolymer such as -methyl-1-pentene, styrene resin such as polystyrene, ABS resin, styrene / butadiene block copolymer, polyester such as polyethylene terephthalate, polybutylene terephthalate, nylon 6 , Various polymers such as polyamides such as nylon 66, polyvinyl chloride and blends thereof in any proportion; metals such as iron, steel, aluminum, and stainless steel; natural materials such as wood, board, and paper; natural and synthetic. Leather, nylon, polyester,
Fibers such as acrylic, urethane and rayon, woven fabrics and non-woven fabrics can be exemplified.

【The invention's effect】

The coating film obtained by applying the aqueous dispersion of the present invention on such a substrate exhibits antistatic properties and has a higher water resistance than the coating film obtained from the potassium ionomer aqueous dispersion. Properties such as properties are improved, and by appropriately selecting the composition and mixing ratio of each component, excellent adhesion to the substrate, water resistance, flexibility, gloss, oil resistance, heat adhesion, film forming properties It has excellent antifogging properties, blocking resistance, transparency, flexibility, coating properties, resolubility, filler dispersibility, chipping resistance, ink absorption, printability, and the like. Therefore, it can be used as an ink, paint, adhesive or the like.

[0020]

The present invention will be described below in detail with reference to examples. In addition, the kind of the polymer which comprises the aqueous dispersion used in the Example, the physical property measuring method, etc. are as follows.

1. Aqueous dispersion (A) Potassium salt dispersion of ethylene / acrylic acid copolymer (EAA-K 90%) Ethylene / acrylic acid copolymer (acrylic acid content: 20
90% of the carboxyl group of
Aqueous dispersion liquid with 25% solid content, neutralized with 1% potassium

(B) Aqueous Polymer Dispersion Various aqueous polymer dispersions (B-1) to (B-15) used
Table 1 shows the type, product name, pH, average particle size, and solid content concentration.
It was shown to.

The physical properties of the aqueous polymer dispersion are measured by the following methods. (1) pH Based on JIS K6833. (2) Particle size Laser light scattering type particle size distribution analyzer NICOMP 3
Measured using 70 HPL.

[0024]

[Table 1]

2. Substrate Biaxially oriented polyethylene terephthalate (OPET) Thickness: 50 μm

3. Method for Measuring Non-Chargeability (Surface Resistivity) of Physical Properties of Coating Film A sample obtained by applying an aqueous dispersion onto a substrate and drying by heating is sufficiently washed once with water to remove the influence of additives such as an emulsifier. After that, drying is performed again, and the temperature 2
After aging at 3 ° C. and a relative humidity of 40% for 24 hours, the surface resistivity of the coating film surface was measured by a high resistivity meter (HIRES manufactured by Mitsubishi Yuka).
TA-IP).

Example 1 Acrylic emulsion Newcoat KT-002 (B) shown in Table 1 was used as a polymer aqueous dispersion in an aqueous dispersion (A) of a potassium salt of an ethylene / acrylic acid copolymer prepared by a conventional method. -1) was blended so that A / B = 7/3 in terms of solid content weight ratio. The resulting mixed aqueous dispersion was coated on an OPET substrate,
The coating was dried at 5 ° C. for 5 minutes to form a coating film having a thickness of 3 μm. PET with the aqueous dispersion thin film thus obtained formed on the surface
3. Regarding the sheet. The surface resistivity was measured by the method described above. Table 2 shows the results.

[Examples 2 to 33] In Example 1, instead of (B-1), various polymers of (B-2) to (B-15) shown in Table 1 were used as the aqueous polymer dispersion. Using an aqueous dispersion, an aqueous dispersion of a potassium salt of an ethylene / acrylic acid copolymer (A) and an aqueous dispersion of a polymer (B) were prepared. Example 1
A coating film was formed on an OPET substrate in the same manner as described above, and the surface resistivity was measured. The results are shown in Tables 2 and 3.

Comparative Examples 1 to 15 In Examples 1 to 33, potassium disversion of ethylene-acrylic acid copolymer was not added, and (B-1) to (B-1) shown in Table 3 were added.
Only various polymer aqueous dispersions of 5) were applied on a substrate, coated films were formed in the same manner as in Examples 1 to 33, and the surface resistivity was measured. Table 4 shows the results.

[0030]

[Table 2]

[0031]

[Table 3]

[0032]

[Table 4]

Claims (1)

[Claims] 1. A neutralization degree of an ethylene / (meth) acrylic acid copolymer having a (meth) acrylic acid content of 10 to 30% by weight and a melt flow rate (190 ° C., 2160 g load) of 1 to 1500 g / 10 min. An aqueous dispersion (A) having a solid content concentration of potassium salt of 75% or more of 2 to 50% by weight, an average particle diameter measured by a light scattering method of 1 nm to 200 μm,
The aqueous polymer dispersion (B) having a solid content concentration of 2 to 60% by weight and a pH of 7 or more has a solid content weight ratio of (A) / (B) of 1
Aqueous dispersion prepared by mixing at a ratio of / 99 to 99/1.