JPS5836300A - Stable absorbing board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to methods and products utilizing fibrous absorbent materials for absorbing liquids. In particular, the present invention relates to products such as sanitary tampons, diapers, sanitary napkins, etc., and particularly those that can be easily handled in the manufacturing process and maintain integrity even when exposed to body fluids. This article relates to a fibrous absorbent material that can be used.

The majority of body fluid absorption products currently in use.

At least in the nine stages given its shape as a product,
Includes pads made of loosely assembled fibrous, generally cellulosic, absorbent materials such as finely divided wood pulp fluff (flt+, ff), sun staple, cotton, cotton linters, and the like. For generations, such materials have been absorbent and inexpensive.

Additionally, in the case of absorbent products that the user must wear for a period of time, these materials have been shown to be useful and effective as bandages, diapers, and sanitary protectors because they are flexible and comfortable. Rice nine.

Unfortunately, despite these excellent properties, pads made from loosely woven fibrous materials are relatively weak and have low tensile strength.

It must be handled with care during the entire manufacturing process.

Molded bodies of such fibrous materials must contain certain types of cellulosic materials (herein referred to as drocolloids) whose functionality is substantially enhanced through chemical modification. To some extent, the manufacturing problems associated with the loosely fitted fiber materials described above have been exacerbated to some degree. Examples of such materials include U.S.% fraud 3
, No. 889A78 (June 17, 1975, Pron.
Cellulose-based graft copolymer described in oy Chatt@rj・e published outside! -: U.S. Patent 5,751,68
No. 6 and No. 3,858,585 (May 8, 1973 and June 7, 1975).

Pr@mey Chat@rj*e) and U.S. Pat. No. 3,589,364 (June 29, 1971)
W.

There is a cross-linked carboxyalkyl cellulose material described in L, D. These hydrocolloidal materials are in the form of fibers with high swelling and high water retention. It would be desirable to combine these fibers with more conventional absorbent materials such as rayon, wood pulp, cotton or cotton linters to produce absorbent bodies with increased liquid retention, but unfortunately, such fiber materials It is not an easy task to uniformly distribute the particles when mixing them together, and the work involved adds to the burden on the production of the desired absorbent product.

Patent application filed by the applicant on October 6, 1980
No. 5-157859 describes a method that greatly avoids the difficulties of handling such materials, and specifically describes a method of forming the material into a board and then dry-pressing the board to make it flexible. did. Although this method made it possible to use textile systems in a more easily processed state and to create products that were more comfortable and convenient for the user,
However, there were some inconveniences. Specifically, when a fiber-based board containing chemically modified fibers as mentioned above gets wet with body fluids associated with urine or menstruation, the shape of the board deforms slightly, causing damage to tampons, diapers, etc. It has been found that it deforms under the influence of pressure, which is common in the use of products such as. Under the influence of pressure exerted by the wearer during normal use of such products, the board tends to collapse, move and deform, resulting in the trapping of liquid in the interstices between the fibres, and subsequent penetration of liquid. The person's ability to tolerate things is significantly reduced. Namely.

Deformation tends to inhibit the ability of liquids to penetrate and therefore to fully utilize the absorbent capacity of these absorbent board materials.

Therefore, it is easy to handle during manufacturing operations, comfortable when incorporated into absorbent products worn by the user, and
Moreover, there is a need to produce compressed board absorbent materials that resist deformation when exposed to pressure in a wet ball state.

According to the present invention, it has been found that an a-yielding material consisting of hydrocolloidal fibers can be provided as a board with substantial structural integrity both in the dry state and after being wetted by body fluids. Specifically, they exhibit substantial resistance to deformation when wet, and can therefore continue to absorb further body fluids at the risk of collapsing or impeding the passage of fluids into themselves. It has been found that it is possible to produce a hydrocolloidal fiber board similar to the one described above.

According to the present invention, the hydrocolloidal fibers are dried for about 3 to 30 minutes at a temperature in the range of about 50°C to about 200°C, preferably at 170 to 180°C for 10 to 10 minutes.
It is heated by being subjected to a heat treatment process for 5 minutes.

The board deposits the slurry onto the screen.

A wet web of hydrocolloidal fibers is formed from the slurry in such a way that the water is drawn off with the aid of a vacuum. It can be formed by conventional methods such as wet forming methods. The wet web is then dried to form a relatively stiff, inflexible board. As described in the previously mentioned patent application of the same applicant, the application of pressure can thereby compress the board and make it flexible. The resulting board is then subjected to a heat treatment as described herein.

This then gives the board resistance to deformation when wet.

The board according to the invention here consists of fibers having a % image as hydrocolloidal. The substrate for these fibers can be commonly used cellulosic materials such as wood pulp, cotton, grasses (wheat, bamboo, etc.), or raw cellulose fibers, etc. These fibers have a length of approximately 100 ~ approx.
Wood pulp is particularly selected due to cost and availability considerations, with a range of 1.000 microns currently being generally preferred. The base fibers are made hydrocolloidal by chemical modification. That is, this renders the base fibers water-swellable and capable of absorbing at least about 10 times, and preferably from about 15 to about 30 times, their own dry weight of water. Chemical modification consists of attaching hydrophilic groups or polymers having hydrophilic groups to the polymeric backbone of the substrate.

Substrates that have been modified by carboxyalkylation, phosphonoalkylation, sulfoalkylation or phosphorylation to make them highly water warmer include: Materials of this type. Modified polymers such as are crosslinked to increase their hydrophilicity,
It may also be made water-insoluble.

These same substrates also serve as backbones to which other polymers are attached, for example by graft copolymerization methods, such grafted polysaccharides and methods of preparation are described in U.S. Pat.
No. 889,678 (published outside Chat@rjee), which has the general formula [where al and R2 are selected from the group consisting of hydrogen and alkyl having 1 to 4 carbon atoms, and X and Y are -OR
, -0 (alkali metal) and -NH2, where 9m is an integer having a value from 0 to about 5000, and n
is an integer having a value of 0 to about 5000, and the total number of m and n parts of a riveting is at least 500, p is an integer having a value of 0 or 1, and q is 1 to 4. is an integer having the value of ] It can be described as a polysaccharide molecular chain having a hydrophilic chain in a gracito bonded state. Preferably, the hydrophilic molecular chain is an acrylonitrile monomer, as described in U.S. Pat. No. 3,889,678.

It is a hydrolyzed copolymer of methyl methacrylate or ethyl acrylate monomer.

The above-mentioned grafted polysaccharides and especially grafted cellulose as well as hinicarboxymethylcellulose are the hydrocolloidal fibers of choice. The drocolloidal fibers may be combined with other cellulosic or non-cellulosic absorbent fibers in making the boards of the present invention.

The fibers are combined with water at a slurry forming station to form a slurry, and the slurry is conveyed to a web forming station. Generally, the slurry has a particle diameter of about 0.116 or less.
This slurry, which preferably has a solids content of about 0.05 or less, is known from the art industry. For example, after forming a slurry at a high solids concentration, e.g. about 15% by weight, it is advisable to dilute the slurry to the desired concentration by adding water. It is.

Regardless of how the slurry is formed.

The slurry is then conveyed to a web forming station.

So, for example, the slurry is deposited on a continuous belt.

The pressure differential between the front and back surfaces of the belt is maintained to remove excess water, leaving a wet web of compressed fibers on the belt and forming a wet web of compressed fibers. A solids content of less than or equal to 50 weights and greater than or equal to about 6 weights is preferred. The wet web is then transported to a drying station.

It is then dried to a water content of less than 10% by weight, preferably less than about 5% by weight.

According to the invention, then the essential VCW4 ambient conditions (
The dried web to ambL@nt conditions is heat treated by subjecting it to a heating step at a temperature of about 100 to about 200°C for about 5 to about 30 minutes. When the temperature i is high, the heating time approaches the lower limit.

It will be appreciated that heat treatment of the sheet can be accomplished by passing the sheet through an air circulation tunnel dryer operated at a suitable temperature and belt speed.

The resulting product is a board that exhibits high resistance to deformation due to pressure when wet. This property is determined by the relaxation/secent value (Percent ReaxationV), which will be described later.
alt+・) can be quantified using a measurement test. According to this test, a sample board of a given size is thoroughly wetted, and the candles are removed by blotting the water between bars/clothes.
The wet board was then placed in an Instron testing machine (Imslro).
n Te5ter) on the compressed cell.

Lower the head of the Instron tester until it almost touches the wet board and start the recorder. Then,
Instron heads can be used for any given weight (e.g.
25 Icg) is gradually lowered until a maximum compression load of 25 Icg) is indicated on the recorder chart. 25# maximum pressure I
When the Ifi4 load is reached, the Instron is turned off and the sample is allowed to equilibrate under that load. As the sample equilibrates, the compressive load decreases as the sample deforms due to the force applied by the head of the Instron tester. Deformation begins rapidly and then gradually decreases until a constant load prevails in the deformed state. Relaxation Nog Cent (Psrc@
ntRelaxation Value) is defined as the difference between the 25 phantom load and the load at equilibrium divided by the 25 kg load, multiplied by 100.

FIG. 1 is a graph representing the above-mentioned relationship, showing a compressive load time plot, where the force of the Instron head is gradually increased over a period of time to a value of P. pFi is arbitrarily selected, for example, 25#. After the board has been equilibrated, it will have a constant compressive load value R. At this time, the relaxation rate is defined as ((P-R)/P)X100. The lower the relaxation percentage value, the higher the stability of the board in wet conditions; conversely, the higher the relaxation percentage value, the lower the stability in wet conditions, and the board is more likely to deform under wet conditions. You'll understand.

Example 1 A series of sample boards were made from drocolloidal fiber material prepared according to Example 2 of the aforementioned US Pat. No. 3,889,678. This material is cellulose 2
A cellulose graft copolymer consisting of a hydrolyzed chemotactic polymer of polyacrylotrile and polyethyl acrylate grafted onto the main chain, starting from wood pulp, acrylonitrile and ethyl acetate in a 1:0 ratio. By combining K at a ratio (weight) of 8:1.40, a graft copolymer is obtained. The drocolloidal material is in a fibrous state and has an average fiber length of about 0.891111. According to the above-mentioned US FFI Patent No. 5,889,678, the graft material is subjected to a hydrolysis process. Thus, conditions are shown that result in hydrolysis products that are hydrophilic to various sl&.

Table 1 A 175 80 B 2.7580 C 57580 For forming into boards, the drocolloidal fiber material was dispersed in water to form a slurry having a consistency of 117 weight-solids. This slurry 1
19 x 19 scratches (7.5" x 7.5" I, manufactured by Williams Apparatus Company, Walter Town, New York)
(0 then TA poured into the hand she@tj mold
PPI standard method (Standard M@thod) T
-2050871, the slurry was diluted to a consistency of 0.01 weight solids.

After thorough mixing, the water is allowed to drain naturally by gravity,
A wet hydrocolloid fibrous web containing a solids content of about 5 s based on the dry web weight was obtained.The water in the wet web was then blotted with a blotting board and squeezed to remove excess water, followed by air. It was dried in a circulating oven to a water content of approximately 2% by weight of the dry material.

The resulting board had a basis weight of 156/cm2 (320 bonds/ft2).

Honjitsu 1*K Therefore, two different board samples were subjected to a heat treatment process in which they were heated at 175° C. for various times.

The sample boards were then tested in a round to determine percent relaxation by the compression test described above.

FIG. 2 tabulates the test results for samples A, B, and C in Table 1, which were subjected to heat treatment at 170° C. for 0 to 60 minutes. As can be seen from FIG. 2, the heat treatment was performed for 0 minutes, that is, without the heat treatment.

The relaxation, e-cent, is essentially a function of the degree of hydrolysis, ie, the hydrophilicity of the hydrocolloidal material.

Sample C with high water quality change has a relaxation percentage value of 81,
In other words, the wet stability is low. Sample A with low hydrophilicity shows relatively high wet stability! The t5Pa percentage value is 44. Sample B with a moderately variable hydrophilic device exhibits a relaxation nocent value of 71, or an intermediate wetting stability. It was observed that as these samples were subjected to heat treatment between 0 and 505), the value of percent relaxation decreased rapidly and tended to stabilize to a value in the range of 15 to 25 after 10 to 20 minutes of heat treatment. It will be done. Thereafter, the value of relaxation/(-cent appears to stabilize and no longer decreases with increasing heat treatment time. As a control, wood pulp samples were also subjected to the same board forming process followed by heat treatment. As shown in Figure 2, at 0 minutes of heat treatment (untreated)
Sample A has almost the same relaxation percentage value as the sample with low hydrophilicity. However, in marked contrast to the hydrocolloidal boards of the present invention, the wood, 6 lp, exhibits essentially no decrease in relaxed A-cent values with increasing heat treatment time.

Wet stability remains substantially lower compared to the hydrocolloidal boards of the present invention.

Example 1 To represent the time-temperature relationship for materials treated in accordance with the present invention, Sample C of Example I above was prepared at 150':17
It was subjected to temperatures of 5°C and 200°C. The results of relaxation and ξ-cent values for these materials are shown in Figure SVC.As can be seen from this figure, when heat treatment is performed at 150℃, it takes 60℃ for the relaxation percentage value to reach 20. It takes a minute. It takes 10-15 minutes for the 175°C heat treatment and only 5 minutes for the 117,200°C heat treatment to reach this percent relaxation value; as a control, pulp heated at 175°C for 0 minutes The sample is also shown in Figure 3,
The relaxation percentage does not essentially change to KW depending on the heat treatment time.

EXAMPLE LAYER Samples of a hydrocolloidal material of the type described with respect to Example I were heat treated at a temperature of 175"O for various times. The samples were prepared in such a way that the starting materials used were 1 part cellulose and 2.75 parts ethyl acrylate. :Acrylonitrile t6 was prepared according to the method of Example 2, except that the weight ratio was 1. This sample was hydrolyzed at 80°C for 2 hours.
It is a graph showing changes in relaxation percentage value with changes in heat treatment time at 75°C. As can be seen from this figure, the sample board has a relaxation percentage of about 2 in about 10-15 minutes.
It stabilized at 0. The results of Example 1, which is approximately similar to this example in terms of percent relaxation, are superimposed in FIG.

Wood pulp is also shown as a control.

Example ■ The fibrous mixture was made of wood, carboxymethylated cellulose fibers (Vercules 9
An absorbent fiber board was made using the method described in Example I, except that it consisted of 1.5 kg of Agaalon (sold under the trademark Agaalon 3'') from Wilmington, Terrace. This board manufactured by the method of Example (2) was tested for percent relaxation after heating at 175 DEG C. for various times.The results are shown in FIG. 5, as can be seen from this figure.

Heat-treated carboxymethylcellulose-containing board.

That is, Sample E reaches a certain 11% sum value, ie, stability, after heat treatment at 175° C. for about 4 minutes.

This is substantially faster than the grafted cellulose copolymer of the previous example.

[Brief explanation of the drawing]

Figure 1: Graph showing the time-load relationship when a board is subjected to pressure in a wet state. Figure 2: Graph representing the relationship between percent relaxation value and heat treatment time according to the invention. FIG. 52 is a graph similar to FIG. 2, further illustrating the effects of various heat treatment temperatures. FIG. 4 = Graph similar to FIG. 2, but using a different drocolloidal material. Figure 5 = Graph similar to Figure 2 but using yet another hydrocolloidal material. Patent Applicant Personal Products Company Agent Patent Attorney Masahiro Matsui (2 others) Figure 2 Kaya 4 style (ordinance) Figure 3 Figure 4 Kaya 4 style (now) Article 5IA Procedural amendment (2) Toru “1 September 1980, Director General of the Japan Patent Office Kazuo Wakasugi 1. Indication of the case 1982 Patent Application No. 134774 2. Name of the invention Stable absorbent plate 3. Person making the amendment Relationship to the case Patent applicant 4, Agent 5, Date of amendment order Voluntary 6, Number of inventions increased by amendment None & ゛As per the attached appendix of the amendment contents 1. "of,
"Stable absorbent board" is corrected. 1. The scope of claims is amended as follows. A method of treating a board containing hydrocolloidal woven fibers to increase its resistance to deformation in wet conditions, the method comprising:
ions) and drying the board to approximately 5
A method comprising heating at a temperature in the range of 0<0>C to about 200<0>C for about 3 to about 30 minutes. 2. The method according to claim 1. The temperature of the board is about 70℃ to about 180℃.
The method is heated for about 15 minutes. 3. By the method described in claim 1. The hydrocolloidal fiber is selected from the group consisting of carboxyalkylated cellulose fiber, phosphonoalkylated cellulose at sulfoalkylated cellulose IIM, and X is grafted cellulose fiber. 4. The method according to claim 3. The method wherein the carboxyalkylated cellulose fiber is water-insoluble carboxymethyl cellulose. & There is a method 't' according to claim 5. The grafted Φ cellulose fiber has the formula [where at and R2 are selected from the group consisting of hydrogen and alkyl having 1 to 4 carbon atoms, X and Ya-OH
, -0 (alkali metal) and →■2, m is an integer having a value of 0 to about 5000, n is an integer having a value of 0 to about 5000, and one stud The number of nlls and n part OII of the stop is at least 500
, p is an integer with a value of 0 or 1, and q is 1 to
is an integer with a value of 4] A method consisting of cellulose to which a portion of O1K aqueous polymer is grafted. 4. The method according to claim 5. A method in which the polymer portion is a partially hydrolyzed copolymer of acrylonitrile and ethyl acrylate monomers. l A method according to claim 5. A method in which the polymer portion is a partially hydrolyzed copolymer of acrylonitrile and methyl methacrylate. & Absorbent board consisting of hydrocolloidal fibers, heat treated in the dry state and exhibiting a percent relaxation value of less than 2596 at compressive loads of up to 25 kg. 9. The board according to claim 8. Boards with relaxation percentage values less than 20- at maximum 25# compression loads. 10. The board according to claim 8. A board in which the hydrocolloidal fibers are selected from the group consisting of carboxyalkylated cellulose fibers, phosphonoalkylated cellulose fibers, sulfoalkylated cellulose fibers, and cellulose fibers manufactured by Company X. 11% The board of claim 10, wherein the carboxyalkylated cellulose fibers are made of water-insoluble carboxymethylcellulose. 12. The board of claim 1410, wherein the grafted cellulose fibers are and Y are selected from the group consisting of -OR, -0 (genus alkali) and -NH2, and m is 0 to about 5
000, n is an integer having a value from 0 to about 5000, and m part of one rivet and n
the number of trout in the segment is at least 500; p is an integer with a value of 0 or 1; q is an integer with a value of 1 to 4]; board. 15. The board according to claim 12,
A board in which a portion of the polymer is a partially hydrolyzed copolymer of acrylonitrile and ethyl acrylate monomers. 14. The board according to claim 12,
A board in which a portion of the polymer is a partially hydrolyzed copolymer of acrylonitrile and methyl methacrylate.''
Correct the line description as follows. (1) In the 4th to 3rd lines from the bottom of page 11, "sulfoalkylation or phosphorylation" is replaced with "or sulfoalkylation"
I am corrected. (2) “Comper” on page 22, line 10, is changed to “company”
I am corrected.

Claims (1)

Claims: t. Increases resistance to deformation in wet conditions. A method of treating a board containing hydrocolloid fibers, the method comprising:
The board is placed under ambient conditions (ambi@nt'@axis diti
ons) and drying the board at approximately 5 t.
A method consisting of heating a loaf for about 3 to about 50 minutes at a temperature in the range of 0°C to about 200°C. 2. The method according to claim 1. The temperature of the board is about 70℃ to about 180℃.
The method is heated for about 15 minutes. (v) The method as set forth in claim 1. A method selected from the group consisting of the aforementioned drocolloidal fibers, carboxyalkylated cellulose fibers, phosphonoalkylated cellulose fibers, sulfoalkylated cellulose fibers, phosphorylated cellulose fibers, or grafted cellulose fibers. 4. The method according to claim 5. The method wherein the carboxyalkylated cellulose fiber is water-insoluble carboxymethyl cellulose. 5. The method according to claim 3. The grafted cellulose fiber has the formula [herein ζ, R and R are selected from the group consisting of hydrogen and alkyl having 1 to 4 carbon atoms, and X and Y are -OH, -
0 (alkali metal) and -Nl2, 0m is an integer having a value of 0 to about 5000, and n is 0.
an integer having a value of ~5000, and the total number of m and n moieties on one chain is at least 500;
p is an integer having a value of 0 or 1, and q is an integer having a value of 1 to 4]. & A method according to claim 5. A method in which a portion of the polymer is a partially hydrolyzed copolymer of acrylonitrile monomer and ethyl acrylate monomer. l, - the method according to claim 5. A method in which the polymer portion is a partially hydrolyzed copolymer of acrylonitrile and methyl methacrylate. a Absorbent board made of human mycolloidal fibers, heat-treated in a dry state, and with a compressive load of up to 25 toges.
Absorbent board exhibiting a percent relaxation value of less than 511. 9. A board according to claim 8. A board with a relaxation percentage value of 20 at a maximum compression load of 25. 1α A board according to claim 8. A board in which the drocolloidal fibers are selected from the group consisting of carboxyalkylated cellulose fibers, phosphonoalkylated cellulose fibers, sulfoalkylated cellulose fibers, phosphonylated cellulose fibers, or grafted cellulose fibers. 11. The board according to claim 10,
A board wherein the carboxyalkylated cellulose fibers are water-insoluble carboxymethylcellulose. 12. The board according to claim 10,
The grafted cellulose fibers have one formula [where at and R2 are selected from the group consisting of hydrogen and alkyl having 1 to 4 carbon atoms, and X and Y are -OR, -0 (alkali metal and →■ Selected from the group consisting of 2, 2m is 0 to about 5
is an integer with a value of 000, and ! 1 is 0 to about 5000
and the total number of m and n moieties on a chain is at least 500, and p is 0 or Fi
is an integer having a value of 1, and q is an integer having a value of 1 to 4.] A board made of cellulose to which a portion of a hydrophilic polymer is grafted. 13. The board of claim 12, wherein the polymer portion is a partially hydrolyzed copolymer of acrylonitrile monomer and ethyl acrylate monomer. 14,4I A board according to claim 12, wherein a portion of the polymer is a partially hydrolyzed copolymer of acrylonitrile and methyl methacrylate.