KR19990001962A - Adhesive using soda silicate and manufacturing method thereof - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to an adhesive using sodium silicate and a method for producing the same.

2. The technical problem to be solved by the invention

SUMMARY OF THE INVENTION The present invention solves the problems associated with conventionally using sodium silicate alone as an adhesive. By using sodium silicate as a main material, it is possible to exhibit excellent water solubility by appropriately mixing a viscous organic compound exhibiting water insolubility. And it is an object of the present invention to provide an adhesive and a method for producing the same using sodium silicate which can not only have excellent flexibility but also prevent whitening from occurring after curing, and ultimately greatly improve adhesive strength.

3. Summary of Solution to Invention

The present invention for achieving the above object is a method for producing an adhesive using sodium silicate and stirring soda silicate prepared by mixing 80 to 100 of sodium silicate, 25 to 35 of polyvinylacetate and 6 to 9 parts by weight of vinyl acetate monomer Provide the used adhesive.

4. Important uses of the invention

It has a use as an adhesive agent, such as papers of this invention.

Description

Adhesive using soda silicate and manufacturing method thereof

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive using sodium silicate and a method for producing the same, and more particularly to an adhesive using sodium silicate obtained by adding polyvinylacetate and vinyl acetate monomer to sodium silicate and a method for producing the same.

Sodium silicate, also called water glass, is a type of silicate compound that exists in nature in various forms, ranging from Na ₂ O · 3.75SiO ₂ to 2Na ₂ O · SiO ₂ , and is generally a method of melting sodium carbonate and quartz powder. It is a white odorless substance obtained by the back.

Sodium silicate as described above has inherent adhesive strength and has been widely used as an adhesive for papers and castings in the past, and in particular, it is inexpensive to produce compared to other organic adhesives and does not cause pollution during manufacturing or after manufacturing. Has the advantage of.

However, when using sodium silicate alone as an adhesive, it has a disadvantage in that the water resistance is weak when exposed to moisture or moisture in the air. It is easy to bend when bent (면) has a characteristic that represents a big problem in terms of flexibility.

In addition, when sodium silicate is mixed with a paper material such as pulp to produce cardboard, Na ₂ O formed in the sodium silicate molecule reacts with carbon dioxide in the atmosphere and is converted into sodium carbonate, thereby changing the surface of the cardboard partially white. The whitening phenomenon appears, such a whitening phenomenon not only greatly impairs the appearance of the cardboard, but also weakens the adhesive force between the paper material particles constituting the cardboard there is a problem that shortens the life of the cardboard.

As described above, in order to solve the problem of using sodium silicate alone as an adhesive, a method of improving physical properties such as flexibility and water resistance by mixing adhesive and organic compounds with sodium silicate has been considered. Since it does not exhibit the hydrophilicity of the tacky organic compound of the mixed with water-soluble sodium silicate to prepare an adhesive there is a problem that the selection of a solvent for diluting it is very difficult.

That is, when an inorganic solvent such as water is used, the tacky organic compound is difficult to dissolve, and when an organic solvent such as benzene is used, dissolution of sodium silicate is difficult.

In this regard, Japanese Patent Laid-Open No. 61-252395 and Japanese Patent Laid-Open No. 5-32931 introduce a technique for preparing an intensifier or coating agent by mixing tacky organic compounds such as water-soluble polyvinyl alcohol with sodium silicate. Doing.

The polyvinyl alcohol used as a tacky organic compound in the above technique has a hydroxyl group as a hydrophilic group in the molecule and shows excellent water solubility, so that water can be used as a solvent even when mixed with sodium silicate. It is limited to use of tacky organic compounds such as polyvinyl alcohol having a hydrophilic group on its own, and there are no references to other tacky organic compounds that do not exhibit water solubility.

As described above, the present invention is to solve various problems that occur when using sodium silicate alone as an adhesive in the prior art, and by using sodium silicate as a main material, the adhesive organic compound exhibiting water insolubility is suitably mixed to provide excellent water solubility. It is an object of the present invention to provide an adhesive using sodium silicate and a method for producing the same, which can exhibit excellent water resistance and flexibility as well as prevent the occurrence of whitening after curing and ultimately greatly improve adhesion.

In order to achieve the above object, the present invention provides a method for producing an adhesive using sodium silicate in a method of mixing and stirring 80 to 100 of sodium silicate, 25 to 35 of polyvinylacetate and 6 to 9 parts by weight of vinyl acetate monomer.

As described above, the sodium silicate used as the main material in the present invention exists in various forms according to the molar ratio of Na ₂ O and SiO ₂ constituting the molecule, but among them, Na ₂ O: SiO ₂ is 1 Sodium silicate, consisting of a molar ratio of 3.2 to 3.4, is commonly used, which has a specific gravity at 20 ° C of 1,260 or higher, insoluble in water of 0.2% or less, and Na ₂ in the classification of sodium silicate specified in Korean Industrial Standard KS M 1415. It has a component composition corresponding to four kinds of sodium silicate including O 6-7% and SiO ₂ 23-25%.

The polyvinylacetate mixed with the above-mentioned sodium silicate is a colorless, odorless, water-insoluble compound, which is excellent in water resistance and weather resistance, and can be used as an adhesive of various materials such as paper, wood, glass, and metal, and is soft because it shows ductility during curing When used in combination with, it can show a remarkable improvement over many problems in terms of water resistance and flexibility when using sodium silicate alone.

As the amount of polyvinylacetate is increased, the above-described improvement effect can be further increased. However, when the mixing ratio of 80 to 100 parts by weight of sodium silicate exceeds 35 parts by weight, the price of polyvinylacetate is relatively high. Due to the phosphorus relationship, it acts as an increase factor of the overall manufacturing cost, so there is a problem in that it is not possible to fully consider the advantages in terms of economics by using relatively low-cost sodium silicate. Since it is difficult, it is preferable to mix in the range of 25-35 weight part.

In the present invention, the vinyl acetate monomer mixed with sodium silicate is converted into water-soluble sodium acetate and vinyl-silicate compounds by reacting with sodium silicate through the mechanism of Scheme 1, which is a vinyl silicate compound at the end of the vinyl group. It will have a silicate group having a hydrophilic property, and thus vinyl acetate, which is ultimately mixed with sodium silicate by the above-described reaction, may exhibit water solubility.

Scheme 1

In addition, the sodium atom constituted by sodium silicate by the above reaction may react with the acetate group constituted by the vinyl acetate monomer to form a sodium acetate compound, thereby exhibiting stability to carbon dioxide.

The effect of preventing whitening due to such a reaction is particularly remarkable when the adhesive of the present invention is applied to papers and the like. At this time, the acetate group composed of the vinyl acetate monomer and the polyvinylacetate mixed with it is capped from both sides with sodium composed of sodium silicate. After being capped, it is moved into the paper particles, thereby preventing the phenomenon of air-slaked lime due to contact with carbon dioxide in the atmosphere.

The reaction between sodium silicate and acetate groups as in Scheme 1 does not occur only in the reaction between sodium silicate and vinyl acetate monomer, and sodium atoms in sodium silicate react with some acetate groups in polyvinylacetate to give sodium acetate. And as the reaction proceeds to stabilize the vinyl-silicate compound, polyvinylacetate may also exhibit water solubility.

The vinyl acetate used in the present invention is a highly flammable and dangerous substance that emits toxic gases when burned. When it is added excessively during the manufacture of the adhesive, it remains as an unreacted substance that does not react with sodium silicate. In addition to the risk of causing a disaster, there is a problem that the adhesive force is deteriorated due to the unreacted vinyl acetate remaining in the adhesive.

That is, when the mixing ratio of vinyl acetate monomer is less than 6 parts by weight based on 80 to 100 parts by weight of sodium silicate, the whitening phenomenon cannot be effectively prevented, and when the mixing ratio exceeds 9 parts by weight, the vinyl acetate monomer remains as unreacted material. Since there is a problem in that the most suitable mixing ratio of vinyl acetate monomer is 6 to 9 parts by weight is preferred.

The sodium silicate, polyvinylacetate and vinyl acetate monomer compounds as described above are mixed in the appropriate mixing ratio ranges as described above, and then, by adding an appropriate amount of water as a solvent, at a normal temperature (preferably 20 to 30 ° C.) of the conventional method. By stirring and mixing at an appropriate speed, the adhesive of the present invention can be prepared.

Hereinafter, the present invention will be described in more detail with reference to Examples, Comparative Examples, and Experimental Examples.

Example 1

9 kg of four kinds of sodium silicate, 3 kg of polyvinylacetate, 750 g of vinyl acetate, and an appropriate amount of water were put into a mixer and stirred at 25 ± 5 ° C. for 35 minutes to prepare an adhesive according to Korean Industrial Standard KS M 1415. .

Example 2

In the same manner as in Example 1, the mixing amount of sodium silicate was 8g, the mixing amount of polyvinylacetate was 2.5 kg, and the mixing amount of vinyl acetate was 600g.

Example 3

In the same manner as in Example 1, the mixing amount of sodium silicate was 10 kg, the mixing amount of polyvinyl acetate was 3.5 kg, and the mixing amount of vinyl acetate was 900 g.

[Comparative Example]

The same procedure as in Example 1 was carried out except that polyvinyl acetate and vinyl acetate were not added.

Experimental Example

Water resistance test

Each of the adhesives prepared in Examples 1 to 3 and Comparative Examples was mixed with a pulp material to prepare a paper particle board having a size of butterfly × length × thickness of 50 × 200 × 10 mm. The ash particleboard was impregnated with water at 30 ° C. for 3 hours, and then dried at 20 ° C. for 10 minutes to prepare a test piece.

Each of the prepared specimens were loaded using a UTM (model UEH-200A) tester manufactured by Japan S with a three-point loading method (span length: 150 mm) with an average strain rate of about 10 mm / min. After measuring the maximum load indicated by the following equation 1 to measure the bending strength is shown in Table 1 below.

[Equation 1]

Bending strength (N / ㎠) =

In Equation 1,

P: Maximum load (N)

L: Span (cm)

b: Butterfly (cm) of test piece

t: thickness of test piece (cm)

TABLE 1

As can be seen from the results shown in Table 1, in Examples 1 to 3 according to the present invention, there is a slight difference in bending strength as the mixing ratio of polyvinylacetate and vinyl acetate monomer mixed with sodium silicate is changed. However, the overall bending strength of 109 to 116 N / ㎠ is shown, which shows a difference of up to 21 N / ㎠ than 95 N / ㎠ shown in the comparative example, the adhesive according to the present invention is only conventional silicon silica It is to demonstrate that it shows a significant improvement in water resistance than the adhesive.

Whitening phenomenon test

As in the water resistance test example, each of the adhesives prepared in Examples 1 to 3 and Comparative Example were mixed with a pulp material to prepare a test piece, but the size of butterfly × length × thickness was 100 × 100 × 1 cm. After one month of standing in a well-ventilated place, the external surface of the test piece was visually observed. As a result, in the case of the test piece made of the adhesive of Examples 1 to 3 according to the present invention, the original state was maintained for one month. However, in the case of the comparative example, white staining was observed at about 35 to 40% of the total area of the test piece.

As described above, according to the present invention, polyvinylacetate and vinylacetate monomers are mixed at an appropriate ratio by using sodium silicate as a main material, so that the whitening phenomenon occurs after water-resistant and flexible curing that are conventionally used when sodium silicate alone is used. It is a useful invention that not only solves the problems but also enables the acceptance of the tacky organic compound mixed with sodium silicate and ultimately improves the utilization efficiency of sodium silicate as an adhesive.

Claims (2)

Sodium silicate 80 to 100, polyvinylacetate 25 to 35 and vinyl acetate monomer 6 to 9 parts by weight of a mixture of stirring, characterized in that the manufacturing method of the adhesive using sodium silicate. Adhesive using sodium silicate produced by the method according to claim 1.