JPS61103969A - Water-soluble glue - Google Patents

Abstract

PURPOSE:A water-soluble glue that contains an alkali metal salt of CMC with more than a specific value of substitution degree, thus being suitable for use as a paper-coating agent, a variety of adhesive and cloth starch. CONSTITUTION:The objective glue contains an alkali metal salt, preferably sodium salt, of CMC with an average degree of substitution (DS) of more than 1.2, preferably more than 1.4. The degree of polymerization in CMC is preferably about 20-200 (rather low degree), when a glue of high solid concentration is desired and advantageously about 200-2,000 (high degree), when a high viscosity is desired in a low concentration.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides a rot-resistant product characterized by containing an alkali metal salt of carboquine methyl cellulose having an average degree of substitution (hereinafter abbreviated as DS) of 12 or more. The present invention also relates to a water-soluble paste with excellent adhesive properties.

Water-soluble adhesives are widely used in the paper industry as coating agents, interior additives, wallpaper adhesives, plywood adhesives, corrugated pole corrugators, office or educational paper adhesives, and the like.

(Prior art) Wheat starch has long been used as this water-soluble thickener. Large amounts of unmodified starch such as Nstar Sen and modified starch such as modified starch etherified starch were used, but unmodified starch requires heat treatment during dissolution. A problem with this is that the COD of wastewater increases due to water-soluble components such as low molecular weight starch produced during denaturation.

Furthermore, these starch-based thickening agents have a major drawback in that they are susceptible to spoilage during storage after preparing the thickening agent. Various preservatives such as formaldehyde are added to prevent this spoilage, but their effectiveness is not sufficient, and many of the preservatives are harmful, creating a new problem. Therefore, synthetic polymer-based glues such as polyvinyl alcohol (PVA), polyethylene oxide, and sodium polyacrylate, which are easy to dissolve and have excellent spoilage resistance, have recently become mainstream in place of starch-based glues.

On the other hand, as a water-soluble glue made of cellulose derivatives,
Examples include carboxyl methylcellulose (CMC), hydroxyethylcellulose methylcellulose (MC), etc., but for the above uses, DS0. CMC of about 6 to LO is partially used. This CMC has the advantage of being soluble in cold water, slightly more rot resistant than starch-based glues, and has a greater thickening effect, but its adhesive properties are still inferior to starch-based glues. Because it has inferior rot resistance compared to synthetic polymer adhesives, it is only used in some cases. However, CMC has advantages such as a large thickening effect even when added in a small amount, and high tensile strength when formed into a film after adhesion.

These features are due to the fact that the molecular structure of CMC is linear and rigid, whereas synthetic polymer adhesives such as PVA have a flexible molecular structure. considered to be a thing. In addition, CMC is made of cellulose and has excellent compatibility with paper, which is the main adherend.
It also has features such as being harmless to the human body.

(Purpose of the Invention) The present invention was achieved as a result of intensive studies aimed at developing a water-soluble paste that takes advantage of these features of CMC and improves its disadvantages of adhesiveness and perishability.

(Structure and Effects of the Invention) The present invention relates to a water-soluble paste having excellent spoilage resistance and adhesion properties and made of CMC having an average degree of substitution (DS) of 12 or more, preferably L4 or more. In this way, CMC's D
It has been found that by setting S to 12 or more, preferably L4 or more, not only the rot resistance is significantly improved, but also the adhesiveness is significantly improved.

Conventional CMC has the disadvantage of being relatively easily putrefied and decomposed by cellulases produced by mold, etc., but by setting the DS to L2 or more, preferably L4 or more, CMC can be decomposed by cellulases in the molecular structure of CMC. It is thought that the rot resistance was improved by reducing the number of unsubstituted anhydroglucose units, which are considered to be easy points. ◇ Furthermore, the reason for the improved adhesion - although the reason is not clear, it is due to the water solubility and adhesion of CMC. This is thought to be due to the increased density of carboxine methyl groups in the molecule, which is thought to be closely related to sex.

Although the CMC of the present invention exhibits its effects with any of sodium, potassium, lithium, cesium, and rubidium, sodium salt is the most economical and advantageous. 1. There is no particular limit to the degree of polymerization of the CMC of the present invention, but if a glue with a high solid content concentration is required, it may be about 20-! A low polymerization degree of 200 is advantageous, while a polymerization degree of about 200 is advantageous when high viscosity is desired in a small amount.
High degrees of polymerization of ˜2000 are preferred.

In this way, the CMC of the present invention takes advantage of the features of conventional CMC, and also improves the rot resistance and adhesiveness, which were disadvantageous compared to conventional CMC. ,
The present invention provides a glue useful as a water-soluble glue such as a wallpaper adhesive, a plywood adhesive, a corrugator adhesive, a laundry paste, and an office or study paper adhesive.

Furthermore, the CMC of the present invention can be used in the above-mentioned applications in combination with starch-based sizing agents and synthetic polymer-based sizing agents that have been conventionally used as water-soluble sizing agents.

Furthermore, the CMC of the present invention is produced by reacting cellulosic raw materials such as ricotta or pulp with an etherifying agent such as caustic soda and monochloroacetic acid, but high DSCMC with a DS of 12 or more, particularly a DSL of 4 or more, is produced by a method developed by the present inventor. (JP-A-58-45201 and JP-A-58-1762
02) can be easily produced industrially.

(Examples) Next, examples of the present invention will be described, but the present invention is not limited to the following examples. In addition, parts and percentages in Examples and Comparative Examples are based on weight.

Example 1 Ratio 1
Pour 380 parts of water into a 500-volume cylindrical glass container, and while stirring with a stirrer, the degree of substitution (DS) is 123 and the degree of polymerization is 4.
60 CMC was added little by little and dissolved by stirring for 2 hours to obtain a paste with a viscosity of 2100 cps (25°C).

Take 50 parts of this glue and apply it to high-quality paper using a Percoater 58, paste the high-quality glue, press it with a rubber roller, and heat it at 100℃ for 50 minutes.
Adhesion after drying for minutes was measured and summarized in Table 1.

Further, the remaining glue was covered with loose film and left to stand in an air-conditioned room at 25°C, and after one month, the state of decay was examined and the viscosity was measured, and the results are summarized in Table 1.

Examples 2 to 5 and Comparative Examples 1 to 2 Instead of CMC used in Example 1, t'! Examples 2 to 5 and Comparative Examples 1 to 2 are summarized in Table 1, using CMCs with different DS and polymerization degrees, and with different amounts of water and CMC.

Comparative Example 3 Etherified corn starch (trade name Unique Gum C-3010, manufactured by Matsutani Chemical Industry) in place of CMC in Example 1
Those using are summarized in Table 1.

As is clear from Table 1, commercials with a DS of 12 or higher according to the present invention
C has superior spoilage resistance compared to conventional CMC and etherified starch.

Furthermore, in terms of adhesiveness, it is not only superior to conventional CMC, but also provides a thickening agent with a high viscosity at a lower concentration than etherified starch, and has excellent adhesiveness even at a low concentration.

j. Adhesiveness: Apply 50 parts of glue to high-quality paper using Bar Coater 8, laminate the high-quality paper, press with a rubber roller, dry at 100℃ for 5 minutes, and check the paper breakage when peeled 180°. It was evaluated as follows.

Paper tear rate 100% 0 Paper tear rate 99-90% ○ Paper tear rate 80-89% Δ Paper tear rate: 79% or less ×

Claims (1)

[Claims] A water-soluble paste containing an alkali metal salt of carboxymethyl cellulose having an average degree of substitution of 12 or more.