JP2016169135A - Clay slurry and clay film - Google Patents

Abstract

【Task】
It is an object of the present invention to provide a clay slurry capable of forming a clay film having excellent water resistance by heat treatment at a lower temperature.
[Solution]
A clay slurry containing (A) a layered silicate compound, (B) a carboxy group-containing resin, (C) a crosslinking agent having a functional group reactive with a carboxy group, and water (D).
[Selection figure] None

Description

  The present invention relates to a clay slurry and a clay film.

Clay is used in various fields such as thickeners, binders, rheology modifiers, inorganic binders, civil engineering muds, waterstops, and cosmetic raw materials.
Clay is a layered silicate compound and has a structure in which flat crystal structures are laminated. For example, a typical crystal structure of montmorillonite, which is a typical layered silicate compound, is a unit of a 2: 1 layer structure in which a silicic acid tetrahedral sheet in which a network of silicic acid is spread is sandwiched between alumina octahedral sheets. It consists of a crystal layer. In many cases, a part of aluminum, which is the central atom of the alumina octahedron sheet, is replaced with magnesium in this crystal layer, and this causes the crystal layer to be negatively charged, and the negative charge is neutralized between the layers. Cations are incorporated.

  In recent years, it has been reported that a laminar silicate compound is used to form a clay film having a barrier function by taking advantage of the plate-like crystal form of the layered silicate compound and its self-stacking property. For example, Patent Document 1 describes a water-soluble polymer composite self-supporting clay film characterized in that a water-soluble polymer is distributed in a laminated clay film. However, the material of this clay film is water-absorbing and does not show sufficient performance from the viewpoint of water resistance.

As a method for increasing the water resistance of a clay film, a method is known in which a clay film is formed using Li-type clay in which cations existing between crystal layers are replaced with lithium ions. In this Li-type clay, Li ions existing between crystal layers are immobilized on the crystal plane by high-temperature treatment, and loses water absorption. Therefore, a clay film having high water resistance or high water vapor barrier property can be formed by using Li-type clay (for example, Non-Patent Document 1, Patent Document 2, and Patent Document 3).
However, when a water-resistant clay film is formed using Li-type clay, heat treatment at a temperature as high as 200 ° C. or more is required to impart water resistance, and there are restrictions in terms of manufacturing equipment and cost.

Japanese Patent No. 3855004 JP 2009-107907 A JP2008-247719

“Clay Handbook”, third edition, edited by Japan Clay Society, May 2009, p. 125

  It is an object of the present invention to provide a clay slurry having good film formability and capable of forming a clay film exhibiting excellent water resistance in a lower temperature process, and a clay film formed using this clay slurry. To do.

  The present inventors have made extensive studies in view of the above problems. As a result, a clay film is formed in a clay slurry at a lower temperature process by blending a clay slurry with a resin having a carboxy group and a crosslinking agent having a functional group reactive to the carboxy group. It was found that a clay film exhibiting excellent water resistance can be obtained even in such a case. The present invention has been repeatedly studied and completed based on these findings.

The above-described problems of the present invention have been solved by the following means.
[1]
A clay slurry containing (A) a layered silicate compound, (B) a carboxy group-containing resin, (C) a cross-linking agent having a functional group reactive with a carboxy group, and water (D).
[2]
Clay slurry as described in [1] whose content of the said component (A) is 50-80 mass% in solid content of the said clay slurry.
[3]
In the ratio [1] or [2], the ratio of the content of the component (B) and the component (C) is, by mass ratio, component (B): component (C) = 1: 3 to 3: 1. The clay slurry described.
[4]
In any one of [1] to [3], the component (A) is a layered silicate compound selected from mica, vermiculite, kaolinite, montmorillonite, beidellite, saponite, hectorite, and stevensite. The clay slurry described.
[5]
The clay slurry according to any one of [1] to [4], wherein the component (C) is a crosslinking agent selected from a carbodiimide compound and an oxazoline compound.
[6]
A clay film formed using the clay slurry according to any one of [1] to [5].

  The clay slurry of the present invention has good film formability when forming a clay film, and can form a clay film having excellent water resistance by a lower temperature process. The clay film of the present invention is a clay film having excellent water resistance that can be formed by a lower temperature process.

[Clay slurry]
The clay slurry of the present invention contains (A) a layered silicate compound, (B) a carboxy group-containing resin, (C) a crosslinking agent having a functional group reactive to a carboxy group, and (D) water. . Each component which comprises the clay slurry of this invention is demonstrated in order.

<(A) Layered silicate compound>
In the present invention, natural clay, synthetic clay, or a mixture thereof can be used as the layered silicate compound. More specifically, one or more layered silicate compounds selected from mica, vermiculite, kaolinite, montmorillonite, beidellite, saponite, hectorite, and stevensite can be used. As the layered silicate compound, a natural product or a synthetic product can be used. Among these, montmorillonite is preferable from the viewpoint of forming a clay film having a higher barrier property.

As the layered silicate compound used in the present invention, it is preferable to use one or more selected from Na-type clay, Li-type clay, K-type clay, and NH ₄ -type clay from the viewpoint of the film formability of the slurry. From the viewpoint of further improving the water resistance of the clay film formed using the slurry, one or more polyvalent cations selected from Mg type clay, Ca type clay, Al type clay, and Cu type clay are used. It is also preferable to use type clay.
Here, Na type, Li type, K type, NH ₄ type, Mg type, Ca type, Al type, and Cu type clays are respectively leached cation amount of clay (ie, total amount of leached cation, unit). : Meq / 100g) means a clay in which the amount of Na ⁺ , Li ⁺ , K ⁺ , NH ₄ ⁺ , Mg ²⁺ , Ca ²⁺ , Al ³⁺ , and Cu ²⁺ (unit: meq / 100 g) is 70% or more. To do.
In this specification, the leaching amount of cation clays, 1M ammonium acetate aqueous 100mL interlayer cations of the clay against the clay 0.5 g (Al clay 1M sulfuric acid for, 10 wt% for the NH ₄ form clay chloride The concentration of various cations in the obtained solution is measured by ICP emission analysis, atomic absorption analysis, ammonia electrode or the like and calculated.

  A commercial item can be used for a layered silicate compound. Examples of commercially available layered silicate compounds include Kunipia F, Kunipia M, Smecton SA, and Smecton ST (all trade names, manufactured by Kunimine Kogyo Co., Ltd.).

  In the solid content of the clay slurry of the present invention, the content of the layered silicate compound is preferably 45 to 85% by mass, more preferably 50 to 80% by mass, further preferably 55 to 80% by mass, and 60 to 75% by mass. Further preferred.

<(B) Carboxy group-containing resin>
The carboxy group-containing resin used in the present invention fills the voids in the clay film formed using the clay slurry of the present invention and forms a crosslinked network together with the component (C) described later. Thereby, the water resistance and intensity | strength of the clay film formed using the clay slurry of this invention can be improved.
The carboxy group-containing resin used in the present invention is preferably a water-soluble resin or an emulsified water-dispersible resin. For example, a resin obtained by water-solubilization or water-dispersion by neutralizing a carboxy group of a carboxy group-containing resin obtained by solution polymerization in an organic solvent with a basic compound, or obtained by solution polymerization in an organic solvent. Examples thereof include a resin obtained by emulsifying and dispersing a carboxy group-containing resin in an aqueous medium, or a resin obtained by emulsion polymerization or suspension polymerization in an aqueous medium as an emulsion or dispersion.

  The weight average molecular weight of the carboxy group-containing resin used in the present invention is not particularly limited, but is preferably 1,000 to 100,000, more preferably 5,000 to 50,000, and still more preferably 10,000 to 30,000. is there. By setting the weight average molecular weight within the above preferred range, the film forming property of the clay slurry can be further improved, and the water resistance of the clay film formed using the slurry can be further increased. In the present specification, the weight average molecular weight is measured by gel permeation chromatography (GPC).

  A carboxy group-containing resin neutralized with ammonia (that is, an ammonium salt) can also be suitably used in the present invention as a carboxy group-containing resin. By using the carboxy group-containing resin neutralized with ammonia, the reactivity with the crosslinking agent can be suppressed until the drying after the film formation, so that the film formability of the slurry can be improved.

  The acid value of the carboxy group-containing resin used in the present invention is preferably 100 to 180 mgKOH / g, and more preferably 140 to 160 mgKOH / g. The acid value is measured according to the neutralization titration method of 3.1 of JIS K 0070: 1992 after preparing a dry resin sample.

Examples of preferable carboxy group-containing resins used in the present invention include homopolymers and copolymers of polymerizable monomers having a carboxy group such as (meth) acrylic acid, and copolymers of these polymerizable monomers and ethylene. Can be mentioned. Moreover, the ammonium salt of these polymers can also be used suitably.
In the present invention, a commercially available carboxy group-containing resin may be used. Examples of the commercially available products include: Syxen-A, Syxen-AC, Syxen-N, Syxen-L (all trade names, manufactured by Sumitomo Seika Co., Ltd.). Hitech S-3121 and Hitech S-3148K (both trade names, manufactured by Toho Chemical Industry Co., Ltd.).

  In the solid content of the clay slurry of the present invention, the content of the carboxy group-containing resin is preferably 5 to 30% by mass, more preferably 7 to 25% by mass, and still more preferably 8 to 22% by mass.

<(C) Crosslinking agent having functional group reactive to carboxy group>
The crosslinking agent of component (C) used in the present invention is a compound having a functional group that is reactive to a carboxy group. The cross-linking agent used in the present invention can form a strong cross-linked network structure on the clay film formed using the slurry of the present invention by reacting the reactive functional group with the carboxy group of the carboxy group-containing resin. . Thereby, the space | gap of a clay film can be sealed effectively and the water resistance of a clay film can be improved.
The molecular weight of the crosslinking agent used in the present invention is not particularly limited, and can be widely used from a low molecular crosslinking agent to a high molecular crosslinking agent. From the viewpoint of efficiently forming a crosslinked structure even when the crosslinking points are separated, it is also preferable to use a polymer having a certain degree of molecular weight, and the molecular weight is preferably 1,000 or more.
In the crosslinking agent used in the present invention, the molar amount of the functional group that is reactive with respect to the carboxy group is preferably 0.5 to 20 mmol / g-crosslinking agent, more preferably 1.0 to 10 mmol / g-crosslinking agent. .
Moreover, it is preferable that the crosslinking agent used for this invention is a carbodiimide compound and / or an oxazoline compound from a viewpoint of the reactivity to both the clay and the polymer which has a carboxy group, and the ease of handling by an aqueous system. Since the carbodiimide group and the oxazoline group can also react with the hydroxyl group on the end face of the clay, the use of the carbodiimide compound and / or the oxazoline compound forms a strong and complex cross-linking network, and can further improve the water resistance of the clay film. .

  The carbodiimide compound can use a commercial item, for example, carbodilite V-02, carbodilite V-02-L2, carbodilite E-01, carbodilite E-02 (all are brand names, the Nisshinbo make) etc. can be mentioned. . There is no restriction | limiting in particular in the molecular weight of the carbodiimide compound which can be used for this invention, Usually, molecular weight is 1,000-10,000, 1,000-5,000 are more preferable, 1,000-4,000 are further more preferable.

  Commercially available products can be used as the oxazoline compound, and examples thereof include Epocros WS-500, Epocros WS-700, Epocros K-2030E, and Epocros K-2020E (all trade names, manufactured by Nippon Shokubai Co., Ltd.). Although there is no restriction | limiting in particular in the molecular weight of the oxazoline compound which can be used for this invention, A polymer is preferable and the weight average molecular weight is preferably 10,000-100,000, and is 20,000-90,000. It is more preferable.

  In the clay slurry of the present invention, the ratio of the content of the component (B) carboxy group-containing aqueous resin and the component (C) the crosslinking agent is a mass ratio of [carboxy group-containing aqueous resin] / [crosslinking agent] = 1. / 3 to 3/1 is preferable, and [carboxy group-containing aqueous resin] / [crosslinking agent] = 1/2 to 2/1 is more preferable. By making the ratio of the content of the carboxy group-containing resin and the crosslinking agent within the above preferred range, the water resistance of the resulting clay film can be further improved.

  In the solid content of the clay slurry of the present invention, the content of the crosslinking agent of the component (C) is preferably 5 to 30% by mass, more preferably 7 to 25% by mass, and further preferably 8 to 22% by mass.

<(D) Water>
The slurry of the present invention contains water as a dispersion medium. There is no restriction | limiting in particular in the water used for this invention, A tap water, distilled water, ion-exchange water, a pure water etc. can be used.
In the slurry of the present invention, the content of water is preferably 70 to 99% by mass, more preferably 80 to 98% by mass, and still more preferably 90 to 97% by mass.

<Other ingredients>
The clay slurry of the present invention further contains a silane coupling agent, an organic polymer, silica, a surfactant, inorganic nanoparticles, a polar organic solvent, ammonia and the like as long as the effects of the present invention are not substantially impaired. Also good.

<Production of slurry of the present invention>
Preparation of the clay slurry of this invention is demonstrated.
In the preparation of the clay slurry of the present invention, there is no particular limitation on the order of mixing the respective components, but a dispersion in which the layered silicate compound is dispersed in water or an aqueous medium is prepared, and this dispersion, the carboxy group-containing resin, It is preferable to prepare by mixing with a crosslinking agent. When a polyvalent cation type clay is used as the layered silicate compound, it is generally difficult to disperse in water, but an aqueous medium containing water and a compound having an unshared electron pair (for example, acetonitrile or ammonia). Can be used to increase the aqueous dispersion of polyvalent cation clay.

As a mixing method, a general impeller with a blade, a homomixer, a universal mixer, a rotating / revolving mixer, an Eirich mixer, or the like can be used. Among these, a homomixer is preferable in that the stirring shear force is strong and a finely dispersed slurry can be produced in a short time. Moreover, it is also preferable to use a universal mixer from the viewpoint of suppressing the generation of bubbles in the slurry. Moreover, when manufacturing a high concentration slurry whose montmorillonite concentration exceeds 20% by mass, a rotation and revolution mixer capable of efficiently mixing can be suitably used.
Although there is no restriction | limiting in particular in the temperature at the time of preparing each slurry by mixing each raw material, Usually, it carries out under the temperature of 4-30 degreeC.

  The clay slurry of the present invention is preferably adjusted to a solid content concentration of 2 to 20% by mass, more preferably 5 to 10% by mass. By setting the preferable solid content concentration, a slurry in which the layered silicate compound is more uniformly dispersed can be easily obtained, the drying time when the clay film is formed can be shortened, and the dispersion has an appropriate viscosity. As shown, film formability can be improved.

[Clay film of the present invention]
By applying the clay slurry of the present invention on a substrate and drying it to a desired level, a crosslinked network is formed and the clay film of the present invention having excellent water resistance can be obtained. In order to further reduce the voids in the clay film, it is preferable to form the clay film using a clay slurry that has been subjected to a defoaming process by evacuation or centrifugation. For the application of the clay slurry, a method such as a bar coater, a casting knife, or spray coating can be employed.
There is no restriction | limiting in particular in the said board | substrate, Resin board | substrates, such as a polyethylene terephthalate (PET), a polypropylene (PP), polyethylene (PE), a glass substrate, a stainless steel board | substrate etc. can be mentioned.

  The method for drying the clay slurry coated on the substrate is not particularly limited, and is performed under a temperature condition of 60 to 130 ° C., preferably 70 to 100 ° C. in a forced air oven or a continuous dryer. The clay film of the present invention in which a crosslinked network is formed can be obtained by drying for about 15 minutes to 3 hours, preferably about 30 minutes to 2 hours. By setting it as the said preferable drying temperature, a clay film can be formed in a comparatively short time, suppressing generation | occurrence | production of a bubble. Further, after the drying treatment, it may be further subjected to a heat treatment. For example, by performing additional heat treatment for about 30 minutes to 3 hours under a temperature condition of 105 to 150 ° C., preferably 110 to 130 ° C., volatile components remaining in the film can be completely removed, and The crosslinking reaction can be sufficiently advanced.

The thickness of the clay film of this invention is suitably adjusted according to a use by adjusting content of the layered silicate compound in a slurry. The thickness of the clay film of the present invention is usually 1 to 100 μm, preferably 2 to 80 μm, more preferably 4 to 60 μm, further preferably 5 to 40 μm, and further preferably 6 to 20 μm.
The clay film of the present invention hardly absorbs water even when it comes into contact with moisture and has excellent water resistance. Therefore, for example, it can be suitably used as a packaging film, an electronic substrate, a flame retardant film, a water vapor barrier film, an insulating film, a coat film and the like.

  The clay film of the present invention exhibits excellent water resistance even when a layered silicate compound having high water absorption is used.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to these.

[Example 1]
A dispersion (paste) containing 10 wt% of clay was obtained by sufficiently mixing Kunipia F (trade name, manufactured by Kunimine Kogyo Co., Ltd., natural Na-type montmorillonite) and distilled water using a universal mixer.
The obtained dispersion and Saixen A (trade name, manufactured by Sumitomo Seika Co., Ltd., carboxy group-containing resin) were mixed with 70 parts by weight of the solid content of the dispersion (solid content of Kunipia F). Was mixed to 20 parts by mass. Distilled water was added to the mixture and mixed using a self-revolving mixer (2000 rpm, 10 minutes). Carbodilite V-02 (trade name, manufactured by Nisshinbo Co., Ltd., carbodiimide compound) was added to the obtained mixed solution so that the amount was 10 parts by mass with respect to 70 parts by mass of the solid content of Kunipia F, distilled water was added, and the above It mixed using the self-revolving mixer similarly to. In addition, addition of the distilled water before mixing with a self-revolving mixer was added so that the total solid content concentration might be 5.5 wt%. Moreover, the temperature of the slurry at the time of mixing by a self-revolving mixer was set to less than 30 ° C. by cooling the slurry and mixing.
The slurry thus obtained was defoamed (2200 rpm, 10 minutes) and then dried on a corona-treated surface of a PET film (single-sided corona-treated product, length 210 mm × width 297 mm × thickness 50 μm) using a casting knife. The entire coating was applied so that the subsequent coat thickness was about 10 μm. This was sufficiently dried in a dryer at 70 ° C., dried at 105 ° C. for 2 hours, and further subjected to heat treatment at 130 ° C. for 2 hours to obtain a clay film.

[Example 2]
Except that the blending amount was changed so that the solid content of Zyxen A was 15 parts by mass and the solid content of Carbodilite V-02 was 15 parts by mass with respect to 70 parts by mass of the solid content of Kunipia F. A clay film was obtained.

[Example 3]
The same as Example 1 except that the compounding amount was changed so that the solid content of Zyxen A was 10 parts by mass and the solid content of Carbodilite V-02 was 20 parts by mass with respect to 70 mass parts of the solid content of Kunipia F. A clay film was obtained.

[Example 4]
A clay film was obtained in the same manner as in Example 3 except that carbodilite V-02-L2 was used instead of carbodilite V-02.

[Example 5]
A clay film was obtained in the same manner as in Example 2 except that Epocros WS-700 was used instead of Carbodilite V-02, and the total solid concentration in the slurry was 7.0 wt%.

[Example 6]
A clay film was obtained in the same manner as in Example 2 except that Hitech S-3121 was used instead of Zaixen A.

[Example 7]
A clay film was obtained in the same manner as in Example 6 except that Epocros WS-700 was used instead of Carbodilite V-02, and the total solid concentration in the slurry was 7.0 wt%.

[Comparative Example 1]
Xyxen A is added so that the solid content of Saixen A is 30 parts by mass with respect to 70 parts by mass of the solid content of Kunipia F. Carbodilite V-02 is not added, and the total solid content concentration in the slurry is 7%. A clay film was obtained in the same manner as in Example 1 except that the content was 0.0 wt%.

[Comparative Example 2]
A clay film was obtained in the same manner as in Comparative Example 1 except that Hitech S-3121 was used instead of Zaixen A.

[Comparative Example 3]
Without adding Saixen A. Further, a clay film was obtained in the same manner as in Example 1 except that carbodilite V-02 was added so that the solid content of carbodilite V-02 was 30 parts by mass with respect to 70 mass parts of the solid content of Kunipia F. .

[Comparative Example 4]
A clay film was obtained in the same manner as in Comparative Example 3 except that carbodilite V-02-L2 was used instead of carbodilite V-02.

[Comparative Example 5]
A clay film was obtained in the same manner as in Comparative Example 3 except that Epochros WS-700 was used instead of Carbodilite V-02.

The acid value of the saixen A was 151 mgKOH / g, and the acid value of Hitech S-3121 was 154 mgKOH / g.
The content of the carbodiimide group in the carbodilite V-02 is 1.67 mmol / g-solid, the content of the carbodiimide group in the carbodilite V-02-L2 is 2.6 mmol / g-solid, and Epocross WS-700. The content of the oxazoline group is 4.5 mmol / g-solid content.

[Test Example 1] Evaluation of film formability The clay films obtained in the above Examples and Comparative Examples were visually observed and evaluated according to the following evaluation criteria. The results are shown in Table 1 below.
<Filmability evaluation criteria>
A: The clay film is not cracked.
B: The clay film is cracked.

[Test Example 2] Evaluation of film thickness For the clay films obtained in the above Examples and Comparative Examples, the film thickness of 5 points was randomly measured using a micrometer, and the average value of the obtained values was used. The value obtained by subtracting the thickness of the PET film was taken as the thickness of the clay film. The results are shown in Table 1 below.

[Test Example 3] Evaluation of water resistance The clay film obtained in each of the above Examples and Comparative Examples was immersed in distilled water together with the PET film, taken out after 24 hours, visually observed, and evaluated according to the following evaluation criteria.
<Water resistance evaluation criteria>
A: No change is observed in the state of the clay film before and after immersion.
B: The clay film is disintegrated or swollen in water, and the clay film is peeled off from the PET film.

As shown in Table 1 above, the clay film formed using the slurry not containing any one of the carboxy group-containing resin and the crosslinking agent has high water absorption and collapses in water, resulting in poor water resistance. (Comparative Examples 1 to 5).
On the other hand, when the clay slurry of the present invention was used, the film formability was good, and the resulting clay film exhibited excellent water resistance despite using water-swellable clay.

[Test Example 4] Evaluation of oxygen gas barrier property The oxygen gas permeability of the clay films obtained in the above Examples and Comparative Examples was measured using an OX-TRAN 2/21 (manufactured by Mocon) at 23 ° C under Dry conditions. (According to JIS K7126-2 appendix A). Further, the oxygen gas permeability of only the PET substrate was also measured as a reference. The results are shown in Table 2 below.

  As shown in Table 2, it was found that the clay film produced in the above example also has excellent oxygen gas barrier properties in addition to water resistance.

Claims (6)

  A clay slurry containing (A) a layered silicate compound, (B) a carboxy group-containing resin, (C) a cross-linking agent having a functional group reactive with a carboxy group, and water (D).   The clay slurry of Claim 1 whose content of the said component (A) is 50-80 mass% in solid content of the said clay slurry.   The ratio of content of the said component (B) and the said component (C) is mass ratio, and is component (B): component (C) = 1: 3-3: 1. Clay slurry.   4. The component (A) according to claim 1, wherein the component (A) is a layered silicate compound selected from mica, vermiculite, kaolinite, montmorillonite, beidellite, saponite, hectorite, and stevensite. Clay slurry.   The clay slurry according to any one of claims 1 to 4, wherein the component (C) is a crosslinking agent selected from a carbodiimide compound and an oxazoline compound.   The clay film | membrane formed using the clay slurry of any one of Claims 1-5.