JPS6367823B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention provides a rewetting adhesive mainly comprising a composition obtained by culturing pullulan-producing bacteria in a medium containing roasted dextrin as a carbon source;
The present invention relates to a sizing agent with excellent adhesive strength, caking strength, and film properties, which is suitably used as a binder, a sizing agent for fibers, etc., and a method for producing the same. Conventionally, roasted dextrin has a significantly low viscosity of the size liquid, the stability of the size liquid improves depending on the degree of decomposition, and those with a high degree of decomposition are completely soluble in cold water, and the adhesive strength and caking strength are Strong at high concentrations. Taking advantage of this feature, we are able to produce paper products, stamps, stamps, gummed tape, transfer paper, foundry sand molds, electric welding rods, whetstones,
It is used as an adhesive for plasterboard and paint, a diluent for medicines, dyes, enzymes, etc., and a sizing agent for finishing textiles and printing. In addition to the above-mentioned properties, roasted dextrin also has other sizing agents (e.g., polyvinyl alcohol,
Although it has the advantage of being cheaper than gelatin, glue, gum arabic, and pullulan), it has problems with mold resistance, moisture resistance and brittleness of the film, and curling of coated paper. On the other hand, pullulan has a low viscosity in the size liquid, dissolves very well in cold water, has good adhesion and cohesive strength, has a moisture-resistant film, and is not brittle. However, because it is more expensive than other adhesives, it is currently hardly used in the industrial field. Usually, pullulan is produced using sucrose, glucose, or a starch partial hydrolyzate (patent application 1973-
79413) for 5 to 8 days,
It is obtained by separating and purifying pullulan produced from the culture solution. However, it is difficult to obtain pullulan in high yield through short-term cultivation, and furthermore, after the cultivation is completed, the enzymes are inactivated by heating, the bacterial cells are removed, and more than an equal amount of an organic solvent such as methanol is added. Pullulan powder was obtained by precipitating pullulan, collecting the precipitate, dissolving it in water, repeating the same precipitation, and then drying to obtain pullulan powder, making it very expensive. The present inventors have found that good adhesive strength, caking strength, film properties,
As a result of extensive research in order to obtain a glue that is both moisture-resistant and inexpensive, we have developed a composition whose main ingredient is a composition obtained by culturing pullulan-producing bacteria in a medium containing roasted dextrin as a carbon source. The present inventors have discovered that a sizing agent based on the present invention is optimal and is superior to a simple mixture of pullulan and roasted dextrin, leading to the completion of the present invention. The roasted dextrin used as a carbon source for the culture medium is natural starch obtained from potatoes, sweet potatoes, corn, high amylose corn, wheat, rice, tapioca, sago, etc., amylose and amylopectin fractions, cross-linked starch, etherified starch, and esters. White and yellow dextrins obtained by heating modified starch, oxidized starch, acid-treated starch, etc. with a small amount of mineral acid, and British gum roasted in an acid-free or alkaline environment are used. Roasted dextrin is a wet acid hydrolyzate,
The major feature of enzyme-modified dextrin is that it is obtained not only through a simple hydrolysis reaction, but also through a transfer reaction and a recombination reaction of cut molecules. are different. The roasted dextrin used in the present invention may have a degree of hydrolysis (hereinafter abbreviated as DE, expressed as a reducing sugar value converted to dextrose) of 0.5 to 20. The concentration of this torrefied dextrin used in the culture medium ranges from 5 to 40%, preferably from 15 to 30%. Other nitrogen sources necessary for the medium include commonly used organic or inorganic nitrogen. Also, known inorganic salts may be used. That is, potassium phosphate, sodium chloride, magnesium sulfate, iron sulfate, etc. are used. Any strain capable of producing pullulan can be used as the pullulan-producing strain, but for example,
Pullularia Pulluans AHU9553, Pullularia
Pullulans IFO6353, Dematium Pullulans
IFO4464 Aureobasidium PullulansIFO6401,
Many strains such as 6402 and 6353 are used. During cultivation, the initial pH is adjusted to 5.0 to 7.5, the roasting temperature is adjusted to 22 to 30°C, and the mixture is aerated and stirred using a conventional method. The required culture time is usually 5 to 8 days, but in the present invention, the culture is carried out at a higher concentration than usual,
Since the remaining roasted dextrin can also be effectively utilized, the time required for culturing can be shortened to 3 to 5 days. After culturing, it is usually necessary to heat the culture solution to inactivate enzymes, remove bacterial cells, decolorize, concentrate, and separate and purify using an organic solvent. When used, the culture solution can be heated to inactivate the enzyme, sterilized, and left as is, or if necessary, filtered, concentrated, and powdered by means such as drum drying, spray drying, or precipitation with an organic solvent. The PH of the glue solution of the present invention is 3 to 8, and the viscosity is 10 ³ to 8.
10 ⁵ cps (15% aqueous solution, 30° C., B-type rotational viscometer), and the molecular weight of the pullulan produced is 10 ³ to 10 ⁶ . The ingredients in the glue of the present invention are the produced pullulan, the remaining roasted dextrin, and other things (dextrin that has been modified by bacterial cells and has a different structure from the roasted dextrin used in the culture medium, monosaccharides, and enzymes). It is thought that pullulan, which has a different structure from the pullulan produced when modified dextrin or acid-saccharified starch syrup is used as a carbon source, is produced as a by-product.) The ratio of the main component pullulan to roasted dextrin varies depending on the culture conditions. Depending on the situation, pullulan: roasted dextrin = 7:3 to 3:7 (weight ratio)
falls within the range of Moreover, it has been found that the sizing agent of the present invention has superior adhesive strength and caking strength, and has a lower manufacturing cost than a mixture of pullulan and roasted dextrin in these ratios. The adhesive of the present invention has good adhesive strength, caking strength, film properties, moisture resistance, etc., and is therefore used in paper making, stamps, labels, gummed tape, transfer paper, foundry sand molds, electric welding rods, grindstones, ceramics, gypsum boards, etc. It can be effectively used as an adhesive for paints, a sizing agent for finishing or sizing fibers, and a coating binder for paper manufacturing. Next, the present invention will be explained in more detail with reference to Examples. Example 1 In the production of the sizing agent of the present invention, Dematium
Using sucrose, glucose, acid-saccharified starch syrup (DE45), and roasted dextrin (DE0.7, 5, 10, and 17) as carbon sources for the Pullulans IFO4464 strain, the effects of the type of carbon source and culture time were investigated. The composition of the medium used is carbon source 20.0%, K ₂ HPO ₄ 0.2
%, Nac10.2%, Peptone 0.4%, _MgSO4 ,
7H ₂ O 0.04%, FeSO ₄ .7H ₂ O 0.001%, initial pH 7.5, roasting temperature 28°C, culture time 3, 4, 5 days, using rotary shaker. Table 1 shows the yield (g/) of pullulan produced. In addition, as a result of measuring the molecular weight of pullulan obtained by gel filtration method, sample number 1 in Table 1,
The amount obtained from samples No. 2 and 6 was approximately 10 ³ , the amount obtained from sample number 5 was approximately 10 ⁴ , the amount obtained from sample number 4 was approximately 10 ⁶ , and the amount obtained from sample number 3 was 10 ⁵ .

【table】

[Table] Example 2 Culture solution obtained in Example 1 (sample numbers 1 to 6)
was heated to deactivate the enzyme, sterilized, filtered, and concentrated to make a 25% paste solution, and for comparison with these, commercially available pullulan (molecular weight 300,000), roasted dextrin (DE3), and the above-mentioned pullulan. An adhesion test was conducted under the following conditions using a 25% glue solution made by mixing roasted dextrin at a ratio of 7:3. Each size solution was applied to a piece of high-quality kraft paper cut into 30 mm x 60 mm so that 30 g solid glue per m ² was applied to one end of 30 mm x 3 mm. After application, leave for 5, 30, and 120 seconds, overlap one end of 30mm x 60mm kraft paper on the glue part, and adhere.
The adhesive force was measured after being left for 10 or 20 seconds. Table 2 shows the results.
Shown below.

【table】

[Table] Example 3 Using the size liquid sample of Example 2, it was coated on high-quality kraft paper to a solid content of 40 g/m ² .
After drying at ℃ for 1 hour, and keeping it in an equilibrium state for one day and night in a constant temperature and humidity room at 20℃ and 65% RH, it was cut to 30 mm x 60 mm in the same way as in Example 2, and the glued side of one end was 30 mm x 30 mm.
After wetting the sheets with water, they were allowed to stand for 2, 5, and 10 seconds, and one end of the same-shaped kraft paper was stacked on 30 mm x 30 mm and pressed together with a load of 500 g, and left for 5 and 10 seconds to measure the adhesive strength. The results are shown in Table 3.

[Table] Example 4 1% of the sample used in Example 2 was added as a binder to charcoal powder, which is the raw material for briquettes, and molded into a cylindrical shape with a diameter of 30 mm and a height of 10 mm at a pressure of 1 ton at a moisture content of 17%. rear,
After drying at 100°C for 1 hour, the specimen was kept at equilibrium in a constant temperature and humidity room at 20°C and 65% RH for one day, and then the breaking strength was measured using a Tensilon tester. The results are shown in Table 4.

【table】

[Table] Example 5 The sample paste solution of Example 2 was adjusted to a 10% aqueous solution, and cotton canvas and cotton broadcloth were dipped in it, squeezed once with a mangle, and dried at 100°C for 5 minutes. The obtained starched cloth was subjected to a bending test (JIS-L
-1096, Method A). The results are shown in Table 5.

【table】

[Table] As is clear from the results of the above examples, it is shown that the sizing agent of the present invention has adhesive strength, caking strength, and fiber hardening effect that are superior to pullulan, roasted dextrin, and mixtures thereof. It was done.

Claims (1)

[Scope of Claims] 1. A sizing agent whose main component is a composition obtained by culturing a pullulan-producing strain in a medium containing roasted dextrin as a carbon source. 2. A method for producing a sizing agent, which comprises culturing a pullulan-producing strain in a medium containing roasted dextrin as a carbon source.