JP3134066B2 - Dialdehyde dextrin for leather tanning and its production method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a dialdehyde dextrin which can be used as a non-chromium tanning agent and a method for producing the same.

[0002]

2. Description of the Related Art The development of non-chromium tanning agents, which are conventionally widely used, has become a global issue due to environmental pollution and occupational health problems. It is known that dialdehyde den powder obtained by oxidizing starch with periodate has a tanning effect, but this substance is poorly soluble in water and has poor permeability to skin tissue. It has been reported (Haruka Toyoda, Toshimitsu Komuro: Journal of the Japan Leather Technology Association 6,61,1960) and is hardly practical at present.

[0003]

SUMMARY OF THE INVENTION The present invention provides a dialdehyde dextrin which is easily soluble in water and is suitable as a tanning agent.

[0004]

The dextrin used as a raw material in the present invention is a group of intermediate products formed by hydrolyzing starch, and three glucosines are formed from a high molecular weight compound to which a large number of glucoses are bonded. Since various compounds having different degrees of polymerization are contained up to maltotriose to which malttriose is bonded, the molecular weight is extremely wide. Therefore, quality (degree of hydrolysis)
Indicates the DE value as follows. DE value = [direct reducing sugar (as glucose)] / solid content × 100 The cyclic structure and glycosidic bond of a sugar by an acetal bond are stable against oxidation by sodium periodate, and hexopyranoside of dextrin is stable. It changes as follows.

[0005]

[Formula 1]

That is, the carbon-carbon bond at the glucose 2-3 position in dextrin is broken, and an aldehyde group is introduced into both OH groups. The present invention provides a dialdehyde dextrin in which the aldehyde group is 70% or more.

[0007]

Example 1. Preparation of dialdehyde dextrin Using dextrin obtained from potato starch, the molar ratio of sodium periodate as periodate to hexopyranoside of dextrin was 1: 0.125.
Dialdehyde dextrins with different degrees of oxidation are prepared by changing to 1: 1. The amount of the oxidizing agent added to dextrin is 3.28 g of dextrin and 4.28 g of sodium periodate in a molar ratio of 1: 1. Both were dissolved in 100 ml of distilled water and treated at a reaction temperature of 15 ° C. for 24 hours. To terminate the reaction, 25 ml of 0.6 mol of ethylene glycol was added, followed by 5 days of running water dialysis and 1 day of distilled water dialysis, followed by concentration and freeze-drying. This preparation was performed three times, and the following test was performed using the obtained dialdehyde dextrin as a sample. Oxidation degree of dialdehyde dextrin (aldehyde group content)
Was measured by Inano's alkali consumption method (Mitsumasa Inano: Industrial Chemistry Magazine 71, 1687, 1968). Regarding the tanning properties, the thermal denaturation temperature (Td) was measured by suggestive thermal analysis and used as a measure of the tanning properties. That is, using a sample skin piece (Hiroka Okamura et al .: Leather Chemicals 13,81,1967), the operation of immersing in a pH8.6,5% sodium sulfate solution for 2 hours was repeated three times to adjust the pH. The sample was placed in a 300 ml wide-mouthed reagent bottle, and 200 ml of a 2% dialdehyde dextrin solution adjusted to pH 8.6 was added to make the (weight) ratio of the solution: leather about 20: 1. Next, immersion was performed while shaking for 5 hours and 10 hours in a constant temperature water bath at 25 ° C. The pH was adjusted hourly with 0.1N sulfuric acid and 0.1N sodium carbonate solution. After the dialdehyde treatment, the sample skin was dehydrated with cold acetone and pulverized with a wire mill to measure (Td). The measurement results were as shown in Table 1.

[0008]

【table 1】

Oxidation degree: ratio of introduction of aldehyde group of C ₂ and C ₃ (3
Yield: The amount of dialdehyde dextrin produced based on the amount of dextrin used (average of three measurements) Td value: pH 8.6, value when using 2% dialdehyde dextrin (3
Average), the Td of the sample skin is 58.6 ° C.

[0010] As the amount of sodium periodate added to hexopyranoside of dextrin increases, the degree of oxidation increases, but the yield of dialdehyde dextrin decreases. Sample 3
(0.5 mol) or more, the yield sharply decreases.
0% or less. However, the tanning properties of the samples after immersion for 10 hours were all higher than 64 ° C., which was higher than the Td (58.6 ° C.) of the sample skin pieces. In particular, in Samples 4 and 5, the tanning property is remarkably increased at 75 ° C. or higher, so that it is considered that the preparation of dialdehyde dextrin preferably has an oxidation degree of 70% or more. That is,
It is necessary to oxidize the periodate to hexopyranoside at a molar ratio of 1: 0.75 or more.

2. Effect of difference in DE of dextrin on yield of dialdehyde dextrin It is thought that molecular weight distribution is different by using dextrin prepared from potato den powder and utilizing solubility difference in alcohol. The resulting four fractionated dextrins were prepared.
In addition, dialdehyde dextrins were prepared in accordance with 1 above using four types of commercially available dextrins having different DEs as samples, and the degree of oxidation and the yield were measured. The results shown in Table 2 were obtained. The amount of periodate added was 1: 1 with respect to hexopyranoside.
Mol and 1: 0.75 mol.

[0012]

[Table 2]

[0013] In Table 2, sample numbers 1, 3, 5, and 7 are commercially available dextrins,
The percentage (%) is the number of dialdex
Hydrodextrin production 5 times average value percentage, oxidation degree is C
_TwoAnd C_ThreeAldehyde group introduction ratio (average of three measurements)
You. -Is effluent by dialysis and cannot be recovered.

[0014] In DE3.6 (sample 1) and 5.6 (sample 2), when the amount of periodate added to hexopyranoside is 1: 1 mol, the yields are 70.2% and 65.4%, respectively, and the oxidation degree is also high. Over 80%. At 1: 0.75 mol, the yields were 78.4% and 71.2%, and the degree of oxidation was about 70%. In the case of 1: 1 mole, the yield of dextrin of DE8.2 is remarkably reduced to 29.4%, which indicates that it is not suitable as an economic preparation condition. 1: 0.75
Even in moles, the yield is 41.7%, which is about 1/2. An increase in DE means that hydrolysis has progressed, which indicates that starch has a low molecular weight. It is presumed that the reduced molecular weight dextrin is further reduced in molecular weight by cleavage of the main chain at the same time as oxidation by periodate, and is discharged during dialysis. Therefore, it is considered that it is desirable to use a dextrin having a DE of 5.6 or less, preferably 5 or less as a raw material of the dialdehyde dextrin of the present invention.

[0015]

[Effect] A dextrin of about DE5 is oxidized by periodate to hexopyranoside at a molar ratio of 1: 0.75 or more to hexopyranoside, and OH groups bonded to C ₂ and C ₃ are changed into aldehyde groups, and the degree of oxidation (aldehyde group introduction) By preparing a dialdehyde dextrin having a ratio of 70% or more, it was clearly confirmed by Td measurement that the dialdehyde dextrin can be used as a non-chrome tanning agent.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hiroshi Okamura 1-7 Taishido, Setagaya-ku, Tokyo Showa Women's University Graduate School (58) Field surveyed (Int. Cl. ⁷ , DB name) C14C 3/08

Claims (2)

(57) [Claims] A dextrin having a DE value of about 5 or less is used as a raw material, and OH groups of C ₂ and C _{3 in} hexopyranoside are reduced to 70%.
A dialdehyde dextrin for leather tanning, wherein the aldehyde group is used. A dextrin hexopyranoside having a DE value of about 5 or less is added with a periodate in a molar ratio of 1: 0.75 or more to reduce the C ₂ , C ₃ OH groups of the hexopyranoside to 70%. A process for producing dialdehyde dextrin for leather tanning, wherein the aldehyde group is used.