JPH0256897B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to the production of carbohydrate derivative absorbent materials having high water absorption and liquid absorption properties, particularly high hemoglobin absorption properties, mainly from softwood or hardwood wood flour and high-yield low-grade pulp. BACKGROUND ART Conventionally, absorbent cotton, nonwoven fabrics, flat pulp, and the like have been used as liquid-absorbing materials for sanitary products, sanitary materials, medical materials, and the like. In addition, in recent years, water-soluble carboxymethyl cellulose (hereinafter abbreviated as CMC) made from high alpha pulp (ether grade) has been cross-linked with acid or formalin to make it water-insoluble, and alkali metal salts have been made into Crosslinked materials have been developed as materials with high liquid absorption properties. However, these methods use high-grade cellulose raw materials, require a cross-linking reaction using chemicals to make water-soluble derivatives water-insoluble, and require a cross-linking reaction to improve liquid absorption properties. The higher the degree of substitution (expressed as the degree of substitution per glucose unit) of the carboxymethyl group (hereinafter abbreviated as CM group), the better, but the degree of substitution of the CM group should be sufficiently high in order to crosslink under as mild conditions as possible. It has problems such as not being able to do it. In the case of carboxymethylated (hereinafter abbreviated as CM) cellulose, if the degree of substitution of the CM group is 0.4 or less, it is water-insoluble, but the resulting absorbent material does not exhibit sufficient absorption characteristics. The inventor has previously investigated the properties of cellulose, hemicellulose, and lignin, which are the main components of wood, and has investigated their properties under the same conditions.
During CM conversion, we found that the degree of substitution of the CM group in hemicellulose is the same as or higher than that of cellulose, and it becomes easily water-soluble, but the degree of substitution of lignin is low and, moreover, it is insoluble in water.
Along with this fact, we focused on the fine structure of wood cells. In other words, most of the hemicellulose and part of the cellulose in softwoods, and part of the cellulose and hemicellulose in hardwoods, are physically strongly entangled with the three-dimensional network structure of lignin.
By using lignin as a cross-linking agent, we can create water-insoluble absorbent materials that have a high degree of CM group substitution and are particularly good at absorbing blood, without performing any insolubilization treatment such as cross-linking reactions. The present invention was conceived based on the idea that it could be obtained. In other words, the inventor used wood flour and commercially available high-yield pulp as raw materials to convert them into CM using a solvent method, and created CM with a high carboxyl group content of 4.2 to 5.2 milliequivalents/gram.
Treated wood flour and pulp were obtained. This sample was extracted with water at room temperature and divided into a water-soluble part (hereinafter abbreviated as Fr.Si) and an insoluble part (hereinafter abbreviated as Fr.I ₁ ). The proportion of Fr.I ₁ is
When high-yield pulp was used as a raw material, it was 70 to 80% of that of CM pulp, about 50% of softwood flour, and about 25% of hardwood flour. The amount of CM groups in Fr.I ₁ is, for example, 4.52 milliequivalents/gram in the case of a sample obtained by converting Refiner mechanical pulp into CM by the solvent method at 55°C for 3 hours, and that of the sample before water extraction (4.55
A high value approximately equal to (milliequivalents/gram) was obtained, and considering only the degree of substitution, all should be water soluble. However, a considerable portion remains insoluble in water. Let's consider the reason. When Fr.I ₁ is treated with ozone or sodium chlorite, which selectively decomposes lignin, it becomes water-soluble as the reaction time progresses, and eventually becomes completely water-soluble. This means that lignin, which has a three-dimensional network structure in the wood composition, is replaced by CM cellulose (hereinafter referred to as CMC), which normally dissolves in water.
) and CM-modified hemicellulose (hereinafter referred to as
It is concluded that CMH is strongly intertwined with CMH, making it insolubilized. In other words, the lignin that originally exists in wood is actively used to insolubilize CM-formed carbohydrates. In addition, Fr.S ₁ and Fr.I ₁ from each raw material
When considering the composition of Fr.S ₁ in softwood flour and high-yield pulp, it was found that Fr.
The contamination of Fr.I ₁ is low, and most of the CMH
remains. CMH has a high swelling property, and leaving a large amount of it in the insoluble part Fr.I ₁ allows us to proactively use an organic raw material that has not been used in the past, and to take advantage of its excellent properties. This is a major feature of the present invention. In the above method, the water-soluble part (Fr.S ₁ )
occurs. Fr.S ₁ has a viscosity of 40 centipoise in a 1% aqueous solution, and it goes without saying that it can be used as is as CMC. However, each raw material
After CM formation and before water extraction, crosslinking with epichlorohydrin under mild conditions (add 3 g of epichlorohydrin to 100 g of CM compound and react at 55°C for ₁ hour) almost eliminates Fr. It becomes water insoluble (hereinafter abbreviated as Fr.CL-I) and can increase the yield of absorbent material. Also, Fr.I ₁ was incubated at 0℃ for various times (15 to 150 minutes).
Ozone treatment or at 70℃ for various times (15-150 minutes)
When treated in stages with sodium chlorite, the lignin, which had a three-dimensional network structure, is decomposed in stages, becoming partially water-soluble, and finally completely water-soluble. (Hereinafter abbreviated as Fr.S _2. ) The water-insoluble part (hereinafter abbreviated as Fr.I ₂ ) obtained in the intermediate stage is also a characteristic absorbent material with extremely high water-swellability. Next, the liquid absorption properties of Fr.I ₁ , Fr.CL-I and Fr.I ₂ obtained as described above will be described. Blood absorption characteristics were measured as follows. The blood used in the test was fresh bovine blood; 100 ml of bovine blood was mixed with 10 ml of a 3.8% sodium citrate aqueous solution.
was added. Blood was to be used within 3 hours after blood collection, and testing was performed at room temperature. The absorption rate of blood was determined based on the published patent publication (A) (Showa 56-28755). In other words, 0.3 grams of sample was spread out in a circle with a diameter of 25 mm on paper, a polyester non-woven fabric was placed on top of the sample, and blood was poured over the non-woven fabric.
0.5ml was added dropwise and the time required for it to be absorbed was measured. As a result, in all samples,
The blood was absorbed within one minute, there was little blood spreading, and no oozing occurred even when pressure was applied. At the same time, absorbent cotton and a commercially available sanitary napkin were used as a control, but both have a fast blood absorption rate, but in the case of absorbent cotton, blood oozes out when pressure is applied, and in the case of commercially available sanitary napkins, blood spreads considerably. Compared to these, all of the absorbent raw materials of the present invention were extremely superior. Next, blood retention characteristics were measured as follows and expressed as blood retention rate. In other words, 30 ml of blood was added to 0.3 g of a sample, left to stand for 30 minutes to completely wet the sample, and then the wet sample was transferred to a screen basket lined with a coarse cotton cloth, gently suctioned, and then heated at 270 to 300 G. The blood was drained for 1 minute, and the blood retention rate was determined from the change in weight of the sample before and after the test. As a control, absorbent cotton and commercially available sanitary napkins were used in the test. The results are shown in Table 1. Compared to the control sample, the absorbent material according to the present invention has a large amount of CM groups, and therefore has extremely excellent blood retention properties. In addition, when we measured the reflection spectrum of the sample after measuring the blood retention rate and examined the adsorbed components, we found that the absorbent material of the present invention has almost the same absorption of components that have absorption in the vicinity of 410 to 420 nm as compared to the control sample. but,
Hemoglobin, which has absorption in the vicinity of 550 to 580 nm, exhibited an excellent feature of extremely high absorption. Note that the water retention rate and the saline retention rate were measured under the same conditions as in the blood retention rate measurement described above using ion-exchanged water and physiological saline, respectively. Fr.I ₁ and Fr.CL-I made from high-yield pulp have extremely superior water retention and salt water retention rates compared to the control sample. Next, Fr.I ₂ (10) and Fr.I ₂ (30) obtained by treatment with Fr.I ₁ , Fr.CL-I and ozone for 10 or 30 minutes were treated with ion exchange water and physiological saline. The degree of swelling after 24-hour immersion in
The liquid retention rate obtained by centrifugation at 1700G for 20 minutes was measured. The results are shown in Table 2, and the degree of swelling of Fr.I ₂ was particularly high, and even when it was centrifuged, it remained gel-like and could not be dehydrated. As described above, the absorbent material according to the present invention has excellent liquid absorption properties, and since the raw material for the absorbent material is wood flour or low-grade high-yield pulp, the raw material cost is lower than that of conventional materials. Since it is inexpensive and does not undergo a characteristic crosslinking reaction, manufacturing costs can also be reduced. Furthermore, since it does not undergo a crosslinking reaction, it is safe as it does not use harmful reagents, and it is also excellent in terms of resource conservation, as it utilizes all the components of the wood to its advantage.

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Claims (1)

[Claims] 1. An absorbent material consisting of water-insoluble components remaining after carboxymethylating wood flour and high-yield pulp and extracting water-soluble components. 2. An absorbent material obtained by carboxymethylating wood flour and high-yield pulp and then crosslinking the remaining hydroxyl groups under mild conditions. 3. Absorption obtained by carboxymethylating wood flour and high-yield pulp, extracting water-soluble components, and partially decomposing the remaining water-insoluble components with ozone or sodium chlorite. sexual material.