JP2007262354A - Adhesive having principal component of japanese lacquer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide such an adhesive having the principal component of Japanese lacquer as is easy-to-prepare and easy-to-handle and also is excellent in the storage stability and high adhesion effect, by removing a compound and a molecular structure not concerned in the hardening reaction and adhesive strength and by selecting a compound which is made from a raw material of a natural product and is so prepared as to have a proper molecular weight, on the basis of the reaction mechanism between urushiol and an amino group. <P>SOLUTION: The adhesive is characterized in that a casein or collagen peptide aqueous solution having a concentration of 5-50 wt.% is mixed with a Japanese lacquer liquid having a weight from one to two times the weight of the above aqueous solution. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to an adhesive mainly composed of lacquer obtained by preparing and mixing lacquer and a lacquer-like compound that is solidified by a similar mechanism, and caseins or collagen peptides.

Lacquer liquid is made from sap collected from urushi tree, and its main component is urushiol and urushiol analogues that are partly different in structure. Other ingredients are rubber, nitrogen-containing compounds, enzymes, water. There are different types depending on the place of production.

Lacquer liquor has been used for various things including paint since ancient times. For this reason, linseed oil, coconut oil, tung oil, egg white, glue, etc. are used as traditional additives. It is common.

For example, one of the methods for restoring works of art such as ceramics and cultural assets is “gold joint” using lacquer. Conventionally used in this method are wheat flour lacquer, rice grain paste lacquer, and the like. Additives to be mixed with lacquer liquor have been selected from long experience, and due to the low degree of processing from natural raw materials and the degree of refining, if the shelf life is poor and it is not used immediately after preparation, it will result in spoilage, etc. There was a problem that the strength was lowered, and it was difficult to mix and dissolve in the lacquer liquid and it was difficult to handle.

The present invention improves the above problems, eliminates compounds and molecular structures that are not related to curing reaction and adhesive strength based on the reaction mechanism of urushiol and amino groups, and uses natural products prepared with appropriate molecular weight as raw materials. The present invention provides an adhesive mainly composed of lacquer, which is easy to prepare, easy to handle, excellent in storage stability and has a high adhesive effect.

The adhesive mainly composed of lacquer according to claim 1 of the present invention is characterized in that 5 to 50% by weight of casein or collagen peptide aqueous solution is mixed with lacquer solution of 1 to 2 times the same weight. It is.

According to the adhesive mainly comprising lacquer according to claim 1 of the present invention, a compound derived from a natural product of casein or collagen peptide is selected as an additive to the lacquer solution, and prepared so as to work effectively. Therefore, it is less harmful to the human body and has less environmental impact due to disposal, etc., increases the solubility in the lacquer liquid, does not require large-scale manufacturing equipment, is easy to prepare and handle, has excellent storage stability, and after curing It is possible to obtain an adhesive mainly composed of lacquer, which has a high adhesion effect without elution of slag or springing to the surface.

Hereinafter, an embodiment of the present invention will be described in detail. The casein used in the present invention has been refined as a protein, has an extra particle component removed, has a molecular weight of tens of thousands or less, and has an easy-to-handle particle structure. Furthermore, in the present invention, a collagen peptide prepared by reducing the molecular weight to several thousand can also be used.

In order to allow the curing reaction of lacquer to proceed without hindering, the amino group active against urushiol is achieved at the molecular end without steric hindrance in the vicinity of the molecular structure. This is due to the need for the amino group to react well with urushiol. Basically, proteins have this structure scattered in the molecule.

Moreover, in order to solve the trouble when using a compound derived from a natural product, it is achieved by limiting the use to those having a molecular structure effective for reaction. Problems in the use of wheat flour and glue are due to the presence of components other than the contained protein, the contained protein itself having too many functional groups not involved in the reaction, the molecular weight being too large, and the like. In the present invention, the compounds satisfying such conditions are limited to casein and collagen peptides.

In using this casein, since casein is insoluble in water and organic solvents, it must be dissolved. It is best to dissolve with ammonia water. Ammonia does not have a residual component in which the excess is volatilized, and can cause a chemical reaction most effectively.

In addition, the method of dissolving using alkali salts such as ammonium hydroxide, borax, sodium phosphate, sodium sulfite, sodium carbonate, and the method using a combination of slaked lime and sodium salt inhibits the curing reaction of lacquer. It is necessary to be careful as it may be. When sodium hydroxide is used for neutralization, care must be taken because casein itself may be strongly hydrolyzed.

In addition, casein that has been subjected to easy dissolution treatment, such as ready-made sodium casein, may be used, but the same precautions are necessary since there is a history of neutralization in the production stage. In addition, when an amide compound such as urea, thiourea, or soda ash is used, care must be taken because the amide compound itself may inhibit the curing reaction of lacquer.

Moreover, about a lacquer liquid, it is necessary to homogenize a contained component by making raw lacquer into chrome, coconut, etc.

A viscous brown liquid is obtained by adding 5 to 50% by weight of the casein or collagen peptide aqueous solution thus obtained to a lacquer solution of 1 to 2 times the same weight and mixing it uniformly at room temperature. Is obtained. The reaction mechanism between urushiol, which is the main component of lacquer liquid, and casein is as shown in Chemical Formula 1.

General casein has a molecular weight of about 23,000, and has about 200 amino groups in one molecule. If urushiol, which is the main component of lacquer, reacts with this in an equivalent amount, theoretically 200 moles are required, but in reality, it is prepared in a smaller amount.

This is due to the fact that casein has a particulate molecular structure and for the time being, the number of amino groups that can participate in reactions facing outwards is limited, and reaction inhibition of components not involved in the reactions contained in lacquer and casein. In consideration of chemical reaction factors such as the necessity of sufficient ammonia water to sufficiently dissolve casein, and operational factors such as a viscosity range suitable for handling as an adhesive, It was specified in the blending ratio.

In the present invention, when the concentration of casein or collagen peptide aqueous solution is less than 5% by weight, the ratio of lacquer is relatively increased, and the adhesive strength is low as in the case of lacquer alone, and when it exceeds 50% by weight, it becomes a paste. This is because the permeability becomes poor and it is difficult to penetrate into the gaps on the bonding surface. Moreover, when the lacquer liquid added to the casein or collagen peptide aqueous solution is less than 1 times the weight of the casein or collagen peptide aqueous solution, the ratio of the lacquer is relatively reduced, and the adhesiveness is lowered. This is because the ratio of lacquer is relatively increased and the adhesive strength is the same as in the case of lacquer alone.

Moreover, in a usage method, after apply | coating a lacquer adhesive to an adhesive surface, you may leave as it is, and also high intensity | strength adhesion | attachment is possible by heating to 150-200 degreeC.

(Example 1) Milk casein (for industrial use) having general properties and average molecular weight was used. To 10 g of this milk casein, add 50 ml of lukewarm water and stir. This is boiled in water, and 0.4 ml of ammonia water (25%) is gradually added while stirring to dissolve. The casein aqueous solution is allowed to cool while degassing (removing ammonia odor). The lacquer used was a refined lacquer made in China. No additives are used in the manufacturing process. Next, 3 g of a casein aqueous solution (about 20% by weight) was added to 4 g of the lacquer solution and kneaded so as to be uniform, whereby the adhesive of Example 1 was obtained.

(Example 2) Casein (refined product) has less impurities than general products and has an average molecular weight slightly smaller due to the operation history. The same ammonia water and lacquer solution as in Example 1 are used. The adhesive of Example 2 was obtained by adding 3 g of a casein aqueous solution (about 20% by weight) prepared by the method to 4 g of the lacquer solution and kneading it uniformly.

(Example 3) Ammonia water was dissolved in a collagen peptide by adding a very small amount of 1-2 drops. 3 g of this collagen peptide aqueous solution (about 20% by weight) was added to 4 g of the lacquer solution by the same method as in Example 1 and kneaded uniformly to obtain the adhesive of Example 3.

Next, the infrared absorption spectrum was measured on behalf of the adhesive of Example 1. For comparison, the infrared absorption spectra of the cured lacquer and casein alone were measured, and the results are shown in FIG.

From the infrared absorption spectrum of FIG. 1, the absorption of the casein lacquer adhesive of Example 1 showed an absorption that was not found in the spectrum of grated lacquer or casein. It, 3545Cm ^-1 vicinity of the shoulder, large absorption in the vicinity of 1454cm ^-1, which is a fine absorption around 970~804cm ^-1. In addition, absorption near 1685, 1440, and 1070 cm ^{−1 in} Shirome Urushi is shifted to the low wave number side, and the strength is decreased.

The spectrum of this lacquer adhesive is different from the spectrum obtained by simply mixing lacquer and casein, which indicates the presence of amines, primary amine salts, ammonium ions, etc., conjugated quinone produced from urushiol, The effects of catechol and aryl-related ether increase / decrease and the influence of peripheral functional groups appear, and it can be confirmed that the lacquer solution and casein react well and have a complex network structure and are cured.

Adhesive strength test] compressive shear adhesion strength was conducted by the test method by bonding two ceramic test pieces using an adhesive based on JIS K ^{6852 -1994.}

Apply a thin layer of fresh lacquer on the adhesive surface of the test piece and dry it. At this time, it was heated at 130 ° C. for about 30 minutes to accelerate drying. Next, the adhesive of the present invention was applied to the same surface, adhered and dried for 2 days, and then heated at 180 ° C. for 2 hours to eliminate variation due to poor curing, baked and completely cured, and allowed to cool. A test piece was obtained. The test results are shown in Table 1.

Comparative example

As a control sample, conventionally used as a lacquer for bonding, wheat flour lacquer (Comparative Example 1), rice grain paste lacquer (Comparative Example 2), water glass lacquer (water glass 1: lacquer 3) (Comparative Example 3) In the same manner, a ceramic test piece was bonded to each other, and the compression shear bond strength was measured. The test results are also shown in Table 1.

From the results of Table 1, the casein lacquer adhesive of the present invention has a compression shear adhesive strength of 6.87 [MPa] or more, and a peptide lacquer adhesive also has a 6.30 [MPa] comparison, which has been conventionally used. It was confirmed that the strength was considerably higher than that of the example adhesive lacquer. From Examples 1 and 2, it is considered that the casein lacquer adhesive has higher adhesive strength as the molecular weight is larger.

In addition, by using lacquer as the main component, it has characteristics of being thin, tough, and robust, which are not found in ordinary polymer adhesives. Can also be used.

It is an infrared absorption spectrum of the lacquer adhesive of Example 1 and lacquer alone and casein alone.

Claims (1)

An adhesive comprising lacquer as a main component, wherein 5 to 50% by weight of casein or collagen peptide aqueous solution is mixed with 1 to 2 times the lacquer liquid of the same weight.