JP5994078B2 - Water repellent composition, method for producing substrate with water repellent layer, water repellent layer forming coating solution and water repellent processed paper - Google Patents

Description

  The present invention relates to a water repellent composition, a method for producing a substrate with a water repellent layer, a water repellent layer forming coating solution, and a water repellent processed paper using them.

  In general, in order to increase the water repellency of the substrate surface, a water repellent such as silicone or fluorine-based chemicals is applied. However, by simply modifying the chemical components on the surface, the contact angle with water is 140 °. It is difficult to obtain a super water-repellent surface as described above. For this reason, the method of apply | coating hydrophobic microparticles | fine-particles on the surface and forming a fine concavo-convex structure is proposed (patent documents 1 and 2). Recently, as a method for treating a large area by a simpler method, a super-water-repellent film production method using a micro uneven structure of a self-assembling nanofiber has been reported (Non-patent Document) 1). Furthermore, a super water-repellent material composed of this low molecular gelling agent and a polymer material has been proposed (Patent Document 3). Contrary to this, a water repellent that can easily remove the water repellent film as required assuming paper recycling is proposed (Patent Document 4).

Japanese Patent Laid-Open No. 2003-172808 JP 2005-188016 A JP 2009-051921 A JP 2012-007099 A

Yamanaka etal., Chemical Communication, 2006, 2248-2250.

As seen in the above-mentioned Patent Documents 1 to 3 and Non-Patent Document 1, when a super water-repellent surface having a contact angle between water and a substrate of 140 ° or more is produced by coating, usually silicone, fluorine-containing compounds, those Fine particles and resins containing are used. Once these water repellents are applied to the surface of the substrate, it is difficult to remove only the water repellent, and in particular, it is extremely difficult to remove with a water-soluble cleaning agent, which hinders recycling of products. Among the base materials that require water repellent treatment, recycling is particularly important for paper materials. Patent Document 2 has a description of water repellents for paper materials. However, if conventional water repellents including these are coated, the paper material after coating loses its affinity for water, so that the recyclability becomes extremely poor. There were drawbacks. In addition, when coated with a polymer material, the air permeability of the paper is impaired, and writing with a pencil or pen becomes impossible. On the other hand, as disclosed in Patent Document 4, the water repellent agent based on 12-hydroxystearic acid can be easily removed by washing with an alkaline aqueous solution. However, when this water repellent is used, it is necessary to increase the solution concentration (0.5 wt% or more), and as a result, the water repellent film becomes thick and the appearance and feel of the substrate are impaired. It was. Accordingly, it has been desired to develop a water repellent composition and a method for producing a substrate with a water repellent layer that have improved these drawbacks.
The present invention has been made in view of the above-mentioned conventional problems, and imparts excellent water repellency with a small amount of application, and with a water repellent composition that can be easily removed when it becomes unnecessary, and with a water repellent layer It is an object of the present invention to provide a substrate and a water-repellent processed paper.

As a result of investigations to achieve the above-mentioned problems, the inventors have found that an aluminum salt of a carboxylic acid known as a low-molecular gelling agent, a monocarboxylic acid having 10 or more carbon atoms, and 10 or more carbon atoms. A water-repellent composition is obtained by mixing at least one dicarboxylic acid, and if a solution of this water-repellent composition is used, it can be applied to a substrate even at a low concentration (less than 0.5%). As a result, it was found that the surface can be made extremely water repellent (the contact angle between water and the substrate is 140 ° or more), and the present invention has been achieved.
That is, the water repellent composition of the present invention contains an aluminum salt of a carboxylic acid and at least one of a monocarboxylic acid having 10 or more carbon atoms and a dicarboxylic acid having 10 or more carbon atoms. Features.

  It is desirable that the aluminum salt of the carboxylic acid has 8 or more carbon atoms. Carboxylic acid aluminum salts having a carboxylic acid moiety having 8 or more carbon atoms have high hydrophobicity, and the surface coated with the water repellent composition of the present invention containing these compounds has a contact angle with water larger than 140 °. Because it becomes. The carbon number is more preferably 8 or more and 50 or less, further preferably 8 or more and 30 or less, and most preferably 8 or more and 20 or less.

  The aluminum salt of the carboxylic acid is preferably at least one of aluminum stearate, aluminum 2-ethylhexanoate, aluminum laurate, aluminum behenate, aluminum oleate, and aluminum dodecanedioate. Since these carboxylic acid aluminum salts have a high gelling ability, if a solution of a water-repellent composition containing these compounds is used, the solution can be applied to a substrate even at a low concentration (less than 0.5%). The surface can be made water repellent easily.

  The monocarboxylic acid and dicarboxylic acid are required to have 10 or more carbon atoms. Monocarboxylic acids and dicarboxylic acids having 10 or more carbon atoms have high hydrophobicity, and the surface on which the water repellent composition of the present invention containing these compounds is applied has a contact angle with water larger than 140 °. It is. The carbon number is more preferably 8 or more and 50 or less, further preferably 8 or more and 30 or less, and most preferably 10 or more and 22 or less.

  The monocarboxylic acid is at least one of stearic acid (melting point 70 ° C.), behenic acid (melting point 82 ° C.) and palmitic acid (melting point 63 ° C.), and the dicarboxylic acid is dodecanedioic acid (melting point 129 ° C.) and sebacic acid. It is preferably at least one of (melting point 134 ° C.). In this case, a water repellent film having a contact angle between the surface on which the water repellent composition of the present invention is applied and water is greater than 140 ° and the heat resistance is 60 ° C. or more can be formed.

  In the water repellent composition of the present invention, the value of (total weight of the monocarboxylic acid and dicarboxylic acid) / (total weight of the aluminum salt of the carboxylic acid) is preferably 0.8 or more and 200 or less. This is because the super-water-repellent composition for paper can be applied uniformly, and the contact angle between the surface on which the water-repellent composition is applied and water is greater than 140 °. More preferably, the value of (total weight of the monocarboxylic acid and dicarboxylic acid) / (total weight of the aluminum salt of the carboxylic acid) is 1.0 or more and 100 or less, and more preferably 1.5 or more and 50 or less. Yes, most preferably 2 or more and 30 or less.

Moreover, the base material with a water repellent layer can be manufactured using the water repellent composition of the present invention.
That is, the method for producing a substrate with a water repellent layer of the present invention comprises a coating liquid preparation step in which the water repellent composition of the present invention is dissolved or dispersed in a liquid to form a coating liquid, and the coating liquid is applied to the surface of the substrate. And a film forming step of forming a water-repellent film by drying a liquid contained in the coating solution attached to the surface of the base material.
Moreover, the water-repellent layer forming coating solution used in the method for producing a substrate with a water-repellent layer of the present invention is obtained by dissolving or dispersing the water-repellent composition of the present invention in a liquid.

  The water repellent composition is particularly effective for producing water-repellent processed paper. When recycling the paper material, there is a step of adding the paper material to an alkaline solution. In this step, the monocarboxylic acid and dicarboxylic acid coated on the paper material are easily converted into an alkali metal salt and dissolved in water, or Can be dispersed. For this reason, the water repellent processed paper obtained from the water repellent composition is easy to recycle.

  The water repellent composition of the present invention can coat a substrate very easily by applying and spraying and then drying. The water-repellent film thus formed can be a super water-repellent surface having a contact angle with water of more than 140 °. Further, even when the solution concentration of the water repellent layer forming coating solution is low (0.5% or less), the surface of the substrate can be made super water repellent. Moreover, the coating film can be easily peeled off by washing the surface coated with the water repellent composition of the present invention with an alkaline solution. For this reason, the water-repellent processed paper obtained by coating the water-repellent composition is easy to recycle and has little environmental burden. Further, since the formed water repellent film is composed only of a low molecular weight compound, there is an advantage that writing with a pencil or pen is possible without impairing the air permeability of the paper.

4 is a drawing-substituting photograph of water droplets on a water-repellent film when measuring a contact angle in Example 1. FIG. 2 is a drawing-substituting electron micrograph of the surface of the water-repellent film in Example 1. FIG. 14 is a drawing-substituting photograph of water droplets on the coating film at the time of contact angle measurement in Comparative Example 7. FIG. 10 is a drawing-substituting electron micrograph of a coated surface in Comparative Example 7. FIG.

Hereinafter, the present invention will be described in detail.
The water repellent composition of the present invention contains an aluminum salt of a carboxylic acid and at least one of a monocarboxylic acid having 10 or more carbon atoms and a dicarboxylic acid having 10 or more carbon atoms. To do. After both are uniformly dissolved or dispersed in an appropriate organic solvent, the super-water-repellent surface can be obtained by adhering to the surface of the substrate by a technique such as coating or spraying and removing the solvent.

  The carboxylic acid portion of the aluminum salt of the carboxylic acid is, for example, octanoic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, 2-ethylhexanoic acid, isostearic acid, Although compounds such as palmitoleic acid, oleic acid, linoleic acid, linolenic acid, erucic acid, sebacic acid, dodecanedioic acid, and eicosanedioic acid are exemplified, it is not necessarily limited thereto.

  Among aluminum salts of carboxylic acids, aluminum stearate, aluminum 2-ethylhexanoate, aluminum laurate, aluminum behenate, aluminum oleate and aluminum dodecanedioate have high gelling ability, and water repellents containing these compounds The composition can easily make the surface of the substrate water repellent. These compounds may be used alone or in combination.

Examples of the monocarboxylic acid and dicarboxylic acid contained in the water repellent composition of the present invention include capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, sebacic acid, dodecane. Although compounds, such as a diacid and eicosane diacid, are mentioned, It is not necessarily limited to these. These compounds may be used alone or in combination.
Among these monocarboxylic acids and dicarboxylic acids, stearic acid, behenic acid, palmitic acid, dodecanedioic acid, and sebacic acid are relatively easy to obtain, have a melting point of 60 ° C. or higher, and have excellent heat resistance. Is obtained.

In addition, the liquid used for the water-repellent layer-forming coating liquid of the present invention is not particularly limited as long as it can uniformly dissolve or disperse the water-repellent composition of the present invention. For example, alcohols, ketones, esters, alcohol esters, ketone esters, ethers, ketone alcohols, ether alcohols, ketone ethers, ester ethers, nitriles, hydrocarbons, halogenated hydrocarbons , Halides and the like.

  The value of (total weight of monocarboxylic acid and dicarboxylic acid) / (total weight of aluminum salt of carboxylic acid) is preferably 0.8 or more and 200 or less. If the ratio is within this range, the contact angle of the resulting water-repellent coating with water is particularly large.

  There is no particular limitation on the method of dissolution or dispersion in the coating liquid preparation step in the method for producing a substrate with a water repellent layer of the present invention. For example, dissolution or dispersion by heating or dissolution or dispersion using a stirrer is possible. Can be. A dispersing agent may be used for dispersion.

  In the coating process in the method for producing a substrate with a water repellent layer of the present invention, there is no particular limitation as a method for attaching the coating liquid to the surface of the substrate, and a method of applying or spraying a water repellent composition included. For example, conventionally known coating methods such as spin coating method, flow coating method, spray coating method, dip coating method, roll coating method, screen printing method, bar coater method, brush coating, and sponge coating can be used.

  There is no particular limitation on the film forming process for forming the water-repellent film by drying the liquid contained in the coating solution, and the film can be formed by a conventionally known solvent drying method such as heating, air blowing, or decompression.

  In the water repellent composition of the present invention, known additives can be blended as necessary. Examples of such additives include coloring materials, ultraviolet absorbers, light stabilizers, leveling agents, thickeners, antifoaming agents, and antifungal agents.

  There are no particular restrictions on the coated object in which the water repellent composition of the present invention can be used, and it can be used for coating various materials, such as paper, metal (for example, iron, aluminum, alloys containing these, etc.) ), Wood, glass, plastic, concrete, ceramics, and a base material provided with an organic or inorganic coating film.

  Among the objects to be coated, the water repellent composition of the present invention is particularly effective for paper materials that are required to be recycled by removing the water repellent, and examples of paper materials include newspaper winding paper, printing / information paper, and packaging paper. Sanitary paper, corrugated paper, hybrid paper and the like.

  Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

(Synthesis of aluminum salt of carboxylic acid)
Commercial products were used for aluminum stearate and ethylhexanoic acid. Other aluminum salts of carboxylic acid were obtained by the following method.
1332 mg of sodium laurate (molecular weight of about 222) and 630 mg of aluminum sulfate 16 hydrate (molecular weight of about 630) were dissolved in about 30 mL of distilled water. The two solutions were mixed and stirred at room temperature for 24 hours. The white solid precipitated in the solution was filtered, washed well with distilled water, and dried to obtain an aluminum laurate salt. In the same manner, aluminum behenate, aluminum oleate, and aluminum dodecanedioate were obtained.

<Examples 1 to 22>
(Preparation of substrate with water repellent layer)
A solution of aluminum salt of carboxylic acid shown in Table 1 and monocarboxylic acid having 10 or more carbon atoms or dicarboxylic acid having 10 or more carbon atoms dissolved or dispersed in 1 mL of various organic solvents. Was cast on various substrates (38 mm × 26 mm) and allowed to stand at room temperature. The blend ratio was such that the value of (total weight of monocarboxylic acid and dicarboxylic acid) / (total weight of aluminum salt of carboxylic acid) was 0.8 to 200. The amount of the solution to be cast was 0.5 mL glass plate, 0.2 mL fine paper, 0.4 mL cardboard, and 0.5 mL corrugated paper. Three days after casting, the contact angle of water on the coated surface was measured with an optical contact angle meter (KSV Instruments CAM200), and the results shown in Table 1 were obtained. All the coated surfaces thus obtained had a static contact angle with water of 140 ° or more. Table 1, no. A photograph of water droplets on the water-repellent film when the contact angle of 1 is measured is shown in FIG. FIG. 2 shows an electron micrograph of the coated surface.

* 1: A: Aluminum stearate (made by Kawamura Kasei Kogyo, # 50), B: Aluminum stearate (made by Kawamura Kasei Kogyo, # 33), C: Aluminum stearate (made by Kawamura Kasei Kogyo, # 30) D: Aluminum 2-ethylhexanoate (STREM CHEMICALS, 93-1326), E: Aluminum laurate, F: Aluminum behenate, G: Aluminum oleate, H: Aluminum dodecanedioate * 2: Check visually, ○ if the coating is uniform, × if it is not uniform
* 3: Made by Matsunami Glass Industry (S7213)
* 4: Made by Tokyo Chemical Industry (S0163)
* 5: Made by Tokyo Chemical Industry (B1248)
* 6: Kanto Chemical (32016-30)
* 7: Made by Kanto Chemical (25384-01)
* 8: Made by Tokyo Chemical Industry (S0022)
* 9: Made by Tokyo Chemical Industry (D0013)
* 10: KOKUYO, coat 100
* 11: KOKUYO, Se-830
* 12: Oji Paper, No. 4-10

<Examples 23 and 24>
(Preparation of substrate with water repellent layer)
The compounding ratio of the aluminum salt of carboxylic acid and the monocarboxylic acid or dicarboxylic acid shown in Table 2 is the value of (total weight of monocarboxylic acid and dicarboxylic acid) / (total weight of aluminum salt of carboxylic acid). Was less than 0.8 or greater than 200, a sample was prepared under the same conditions as above, and the results shown in Table 2 were obtained. All the obtained coated surfaces had a static contact angle with water of 130 ° or more and less than 140 °.

<Comparative Examples 1-14>
(Preparation of substrate with water repellent layer)
When coated with only monocarboxylic acid having 10 or more carbon atoms shown in Table 3 or dicarboxylic acid having 10 or more carbon atoms (Comparative Example), and coated with only aluminum salt of carboxylic acid (Comparative Example) The sample was prepared under the same conditions as in Example 1 to try to form a film, and the results shown in Table 3 were obtained. When coating is attempted only with the monocarboxylic acid or dicarboxylic acid, a large crystal that can be visually confirmed is deposited, so that a uniform surface cannot be obtained or even if it can be uniformly coated, the contact angle of the coated surface Was 120 ° or less. Moreover, when coat | covered only with the carboxylic acid aluminum salt, although uniform application | coating was possible, the contact angle was 120 degrees or less on all implemented conditions. Table 3, No. The photograph of the water droplet on the coating film at the time of measuring the contact angle of 7 is shown in FIG. FIG. 4 shows an electron micrograph of the coated surface.

<Comparative Examples 15-17>
(Comparative Example 2 for producing a substrate with a water repellent layer)
The compounding ratio of the carboxylic acid aluminum salt shown in Table 4 and the monocarboxylic acid or dicarboxylic acid having less than 10 carbon atoms is (weight of the monocarboxylic acid or dicarboxylic acid) / (weight of the aluminum carboxylic acid salt). ) Was 0.8 or more and 200 or less, samples were prepared under the same conditions as in Example 1, and the results shown in Table 4 were obtained. All obtained coated surfaces had a static contact angle with water of less than 120 °.

From the results of Examples 1 to 24 and Comparative Examples 1 to 17, the following was found.
That is, when a mixture of an aluminum salt of a carboxylic acid and a monocarboxylic acid and at least one dicarboxylic acid having 10 or more carbon atoms is applied to a substrate, nanoscale to microscale irregularities are formed on the surface. Therefore, super water repellency is exhibited.
On the other hand, when an attempt is made to form a film consisting only of an aluminum salt of carboxylic acid, irregularities from nanoscale to microscale are not formed, and only a water-repellent film having a contact angle of 120 ° or less can be obtained.
In addition, when attempting to form a film consisting of at least one of a monocarboxylic acid and a dicarboxylic acid having 10 or more carbon atoms, macroscopic crystals are deposited and a uniform film itself cannot be obtained, or a relatively uniform film Is obtained, the contact angle is 120 ° or less.
Moreover, even if it is a mixture of a carboxylic acid aluminum salt and a monocarboxylic acid and at least one dicarboxylic acid having 10 or more carbon atoms, the monocarboxylic acid or dicarboxylic acid has less than 10 carbon atoms. A super water-repellent film cannot be obtained.

Claims (7)

For forming a water-repellent layer , wherein an aluminum salt of a carboxylic acid and at least one of a monocarboxylic acid having 10 or more carbon atoms and a dicarboxylic acid having 10 or more carbon atoms are dissolved in an organic solvent Solution . The solution for forming a water repellent layer according to claim 1, wherein the aluminum salt of the carboxylic acid has 8 or more carbon atoms. The water repellent according to claim 1 or 2, wherein the aluminum salt of carboxylic acid is at least one of aluminum stearate, aluminum 2-ethylhexanoate, aluminum laurate, aluminum behenate, aluminum oleate and aluminum dodecanedioate. Layer forming solution . The repellent according to any one of claims 1 to 3, wherein the monocarboxylic acid is at least one of stearic acid, behenic acid, and palmitic acid, and the dicarboxylic acid is at least one of dodecanedioic acid and sebacic acid. Aqueous layer forming solution . / Repellent according to any one of claims 1 to 4 the value of (the aluminum total weight of salts of carboxylic acids) is 0.8 to 200 (total weight of the monocarboxylic acid and the dicarboxylic acid) Aqueous layer forming solution . A coating step for attaching the water repellent layer forming solution according to claim 1 to the surface of the substrate;
A film forming step of drying a liquid contained in the coating solution attached to the surface of the substrate to form a water repellent film;
A method for producing a substrate with a water repellent layer. A component other than the organic solvent of the water repellent layer forming solution according to any one of claims 1 to 5 is attached to the surface of the paper , and a contact angle with water is 140 ° or more. Water repellent processed paper.