JPS5959910A - Super-absorbable synthetic fiber - 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 has the ability to retain a large amount of body fluid (diappr<1. :
Product (h n cl yfluid a19nrhen
l prr++ (ucls) relates to absorbent synthetic fibers that can be formed into dense fluff.

In recent years, diapers, 9 menstrual tampons, and sanitary napkins that absorb body fluids such as I'+, IIL! ! A great deal of effort has gone into producing absorbent materials for use in products. So far, these 1! (Naturally occurring cellulose fibers such as water pulp, cotton, etc. have been used in this product. Published on June 17, 1975.
U.S. Pat. No. 3,889,678 to Iterjee et al.
Products are disclosed that include a hydrophilic polymer moiety chemically grafted onto the backbone of cellulose fibers. As disclosed therein, the cellulose transverse 1a threads have significantly enhanced ability to absorb and retain body fluids, and these grafts The material has proven useful in a wide range of absorbent products. A similar disclosure is provided in U.S. Pat. No. 4,1 to Chatferjee et al., issued August 8, 1978.
It is in 05.033.

Notwithstanding the foregoing, the grafted I7 fibers retain the general appearance of the original cellulose yarn material, but with certain disadvantages. It has been discovered that it behaves. Specifically, the grafted cellulose is composed of Norolup fluff (p++Ip fl
It is known that cellulose fibers exhibit substantially greater bulk densities than old cellulose fibers when ground to a pulp (uff). This unfortunate property is manifested when the grafted fibers are manufactured in plate form and then milled in comparable equipment. For example.

1. Slightly more n than Ri pulp? - Fragile fibers are easy to crumble into powder (7). The first thing I did was
Pulp fluff produced is substantially lower? void
)'fr t'/l, giving a smoother (7) more abrasive feel, resulting in increased user comfort and protection. tV) low bulk 1■
qani+ary pr
The use of grafted cellulose fibers has been discouraged. Additionally, krafted cellulosic materials have been found to be difficult to work with, perhaps due to their crumbling and A-silver properties, despite attempts to process the materials into absorbent pads. Generally such operations ζ include one culm, such as carding the moss fibers.1.
The crumbling of the molluscs, A-1,) F & 1 of the molten fibers that use silk are easy to turn into powder, resulting in 6 u effort. Furthermore f,
Since these $F/If+ are manufactured from naturally occurring cellulose fibers, their length is not inherently regulated. Therefore, these fibers can be combined with other fibers 1+ +/
l: Blend with material (9, (blend)
It is not possible to adapt the I length. 611, cotton blending is more easily accomplished by mixing fibers of similar length, and this optimal method of cotton blending is limited when using grafted cellulose made from natural fibers.

In contrast to the above-mentioned reason, the grafted cellulose of ty + I'l + I r:j: has a high content of N Ml, exhibits a difficult crack retention property in terms of absorption, and is fluffy. ni saia, taki i a parf et (11 (1) (1
1: L) 1 ¥, dense + fJ, 3-1 dwarf soft 11 names 4") request exists.

This time, we have developed a 1-Year-II type ゛-rafty cellulose, which has all the characteristics of cellulose, but unlike such fibrous grafted cellulose, it has a low density 1[c, high void 1
It is possible to crush the fluff of the crowd. It has been discovered that a highly absorbent, highly retentive absorbent powder: PF may be provided.

Specifically, U.S. Patent No. 3,889 of
Although the teachings of the present invention were applied to the cellulose skeleton of the cellulose absorber described in , 678, one - (I+', IF qualitatively selected complete 1
By substituting the polymer in this synthesis, a product with a low bulk density can be obtained.
What is the selection of fees?

Yi) Aqueous Borifu i? This is done by choosing a thermoplastic polymer in a blend of polymers with a f~γ position (5iles) that is amenable to the graph 1- of li. Particularly good mixtures are those obtained by polymerizing polyolefins, preferably olefins containing 2 to 4 carbon atoms, R1], poly(lower olefins) combined with small amounts of polyvinyl alcohol. Particularly well rafted polymers are made of poly(carboxylic acid) type polymers, preferably those hydrolyzed to alkali.

JII products are essentially synthetic polyester raw materials before crafting. -ffW #(t
(fluff density) is approximately 0.03 da/
The low bulk density absorbent 134J material of the present invention, having a fluff density less than cc, consists of a) a hydrophilic 1·'L carboxyl polymer portion grafted onto a 9 synthetic polymer material.

Graft l (as opposed to the synthetic polymer material that serves as the backbone).

Known in the industry as synthetic wood pulp.1. tree 44
SFl similar to Pulp Yokoki f#! Preferably, those having physical and formal properties. Examples of such things and 17
In polyolefins, such as Crown Zel Ie
It was sold by rhaCk and Nrvada under the product name SWP, but it is currently sold under the trade name (', rnwn Z
ellprback to FY old L synthesis ta, t
It is a synthetic irrigation valve fiber made from polyethylene and polypropylene as sold under the trade name of ``IT''.

Various methods of manufacturing synthetic water 4A valves are known;
(1) Stirring for 11 hours after solution polymerization, (21) melting the preformed polymer and exposing the solution to a non-solvent (7).
Alternatively, (3) localized agitation is applied while forming a polymer at the interface between the liquid layers, and the polymer Hf thus produced is fibrillated or shaped into a shape by tension. Synthetic irrigation pulp tP1. Method for manufacturing a cone (311, U.S. Pat. No. 3.561), 41 B; 3
．． [I R1, Ei 19 ;3, +103.912
: 3.048.527 and 3,290,209° South l'Frica Patent 69/7431, British Patent 1.111
If 2,342, Hinioranta IIfFF output [i Al
32. /48 7,'+13178 f is disclosed,
There are 11.

In terms of engraving, synthetic wood pulp fibers are generally sized and shaped to resemble naturally occurring wood ('/1 pulp) and are elongated, supple, or randomly shaped. -7 and has an irregular cross-section at any point along the length of the fiber, which also varies from point to point along the length of the fiber.
The main shape of a, f, flJ is usually ribbon-like.

Synthetic wood pulp fflta is primarily a hydrophobic polymer.

Specifically, it consists of lower polyolefins such as polyethylene and polypropylene. The degree of hydrophilicity in these fibers is that they contain a small proportion of hydrophilic polymers.

For example, it can be applied by physically mixing and adding a small amount of polyvinyl alcohol. for example.

swp fiber manufactured by JM by Crown Zellprback is commercially available in several varieties containing 0.8 to 4.0 2% polyvinyl alcohol by weight. When these hydrophilic 1't polymers are added, the absorbency of SWP reaches a level comparable to that of wood pulp. Despite this, swp fibers absorb and retain body fluids. It is much inferior in its capacity to wood pulp and, of course, substantially less effective than the grafted cellulose fibers mentioned above.

In accordance with the teachings of the present invention, it is advantageous to have a mixed Y water-based polymer present.

By utilizing the substrate as a site for the graft copolymerization of additional polymer moieties to produce products with desired levels of absorption and fluid retention, Found it again. Amazing things (Otsu 1
It was discovered that this could be accomplished while maintaining essentially the same low-density yield as the wood-based wood pulp yield.

Therefore, the starting material is a lower polyolefin/.

1! II Bill 21. It is a synthetic wood pulp consisting of a polymer of olefins of 4 to 4 carbon atoms and a small amount of hydrophilic polymer. Preferably, polyvinylene or polypropylene fibers are used in combination with a small amount of polyvinyl 11/alcohol. The polyvinyl alcohol is preferably present at about 0.5 to ti'NN degrees based on the heavy phase of cJ:, poly(olefin) and poly(vinyl alcohol). Preferably, the polyvinyl alcohol is present at least about 0.8 degrees by weight. The starting material is 9 then of the general formula (I), in which ul and B2 are selected from the group consisting of hydrogen and alkyl having 1 to 4 carbon atoms, and Y is an integer selected from the group consisting of L-(, ) (alkali metal), and -Nlt, and 1m is an integer having a valence of (] to about 5000;
n is an integer having a valence of 0 to about 5000;

the total number of m and n moieties on the chain is at least 500, p is an integer with a valence of O or 1, and q
is modified by grafting a chain of hydrophilic Vts, where fl is an integer with a valency of 1 to 4.

Preferred hydrophilic chains are poly(acrylic acid), poly(acrylic acid) alkali, such as poly(acrylic acid) sodium or potassium, and copolymers thereof, such as 7 hydration of poly(acrylonitrile) chains. Obtained by decomposition! It is like choosing from a group of 9 things. 4) yf (then the intermediate product poly(acrylamide)
It should be noted that some amount of chloride will be produced and will also be present in the final product.

----,) or 'fM number ■(, the aqueous chain is the polymer backbone' - ICIC graph 1 The detailed mechanism of Grafting takes place 1. Free radicals are located on the polymer backbone (7), which acts as a raining agent and the hydrophilic 1'lE chain is bonded to the bo117-reducing agent through carbon bonds to form a raft copolymer. It is one thing to do
It is considered to be 1 t, (! 7).

The hydrophilic open chain is a polymer of an olefinic unsaturated carboxylic acid or derivative thereof or at least one other monomer capable of copolymerizing therewith. The resulting polycarboxylic acid-type polymer.

For example, acrylic acid, acrylic anhydride, methacrylic acid,
Croton moromi, maleic acid, itaconic acid, citraconic acid,
α-dimetyl-7leic acid fumaric acid, α-butylene-7leic acid fumaric acid '7 Konitz 1-m1'5. Similarly, polymers containing one monomer unit of these moieties, intermediates, and esters can be included. Both the dianhydrides and the dianhydrides of the aforementioned acids are used.

7) Copolymers of anhydride and other monomers.

By reaction with water, carboxyl-Ω-ecopolymer is produced.
And compounds such as sodium hydroxide, potassium hydroxide, etc. are converted to carbonic acid 'M';
Can be converted into parts.

The copolymers are produced in a known manner by reacting a mixture of the desired monomers in a suitable core medium in the presence of an initiator.

It is convenient to classify the resulting copolymers based on their monomer constituents. However, the names given to copolymers are related to the molecular structure of the polymer; 4, but are they due to the copolymerization of specific monomers? ! It is not limited to J-treated polymers. In many cases, the same copolymer can be prepared from other monomers and subsequently converted to the desired copolymer by means of chemical reactions.

Suitable hydrophilic polymer chains can be prepared by various methods known to those skilled in the art. Examples of these methods are as follows.

(11 Acrylonitrile is mixed together and hydrolyzed with an alkaline solution to produce alkali IIIJ of polyacrylic acid.

(n) Acrylic acid a) C< is an alkali salt of acrylic acid.

(31Me-tacrylonitrile is combined and hydrolyzed with acid to produce polymethacrylic acid, or hydrolyzed with an alkaline solution to produce alkali 11m of polymethacrylic acid.

(4) Polymerize methacrylic acid or an alkali salt of methacrylic acid.

(51 acrylic compound is combined, optionally followed by hydrolysis.

(61 methacrylamide is combined, optionally followed by hydrolysis.

Methods of grafting copolymerization of olefinic non-divisible chains onto cellulose to produce copolymers of any of the monomers mentioned above are known to those skilled in the art and can also be used in connection with the present invention. Thus, 1' hair, water ( The crafting of the 2t:i material into synthetic wood pulp L can be achieved simultaneously with the production of a hydrophilic polymer material in an aqueous medium, since the ff1i monomers are copolymerized. Suitable initiators for this purpose are ceric ions, ferrous ions, ferrous ions, Nikoharu j-io7,
(Nf(4)7s2(Jg, f.

- Copper ions, etc. The desired ions are provided in the form of ceric-11 ammonium nitrate, ferrous ammonium sulfate, and the like. Graft copolymerization of unsaturated chains with olefins is carried out by irradiation (ultraviolet rays - 9, sub-beam,
This can be carried out in an aqueous medium in the presence of an emulsifier, by gamma or X-rays) or by heating.

Synthetic wood pulp forges are added to the graft copolymerization initiator system and the slurry.

Usually W or more depending on the initiator used.
5itu (at that location) It is possible to slurry the polymerized 7-mer in water.

The crafting rate of hydrophilic chains onto the mature wood valve can vary from about 1D weight percent to about 90 weight percent of the crafted synthetic wood pulp product, preferably about 40@ijX.

A preferred polymer portion is an at least partially hydrolyzed polymer based on acrylic polymers. Acrylonide 11
Hydrolysis of a copolymer of 1,000 acrylic acid; (7
This is the polymer preferred by samurai.

The coupling and grafting reactions are preferably carried out at an acidic pH.
.

Example 11 is started with ceric ion for about 0.8 h to about 2.6 h and at room temperature. Since the reaction is inhibited by the presence of oxygen, it is possible to buff the reaction system with a non-oxidizing gas such as helium or argon to remove essentially all the oxygen from the system. desirable.

The grafted portions are hydrolyzed by reacting the fibers with an excess of a 9-strong solution (for example, hydroxylated). The concentration of this solution is from about 1% to about 50% by weight.

The product is washed until free of reactants and dried.

Drying may be accomplished using hot air, but preferably physical properties and absorbency are best preserved by using methods such as freeze drying or let solvent extraction as known to those skilled in the art; do. Freeze-drying can be accomplished by methods known to those skilled in the art, drying the moist Hf below the freezing point of the liquid.
111 and then removing the frozen liquid by sublimation, which is accomplished by suctioning the vapor sublimating the frozen material under reduced pressure.

Solvent extraction is also known to those skilled in the art, in which the water retained in the solvent dissolves to a moderate extent. The method consists of dispersing a moist substance in a volatile solution. The volatile solvent is then removed by evaporation into hot air.

The dried weft fibers are fluffed by mechanical agitation to produce low density fluff. Such fluff has a density comparable to that of both unmodified wood pulp fluff and unmodified synthetic wood pulp, i.e., from about 0.01 to about 0.0.
5 f/cc 'f% IQ'. At the same time, the synthetic wood pulp was grafted with the lowest body fluid F4F
(minim+on fl++irl capaci
ty ) (defined by the perforated plate test described below)
is also 15 times lower for wood pulp fluff and more than 5 times lower for unmodified synthetic wood pulp. Similarly, regarding body fluid retention (described later), the low-density 1F graft size is more than 6 times that of wood pulp, and 1
Shows twice the holding power.

111 A funnel with a stirrer, a bubble tube and a stopper was made into foil.
1-1 Into the flask, I D (1 (1 m# water and 20 f SW
Obtained from Zellerhack.

It was named 18-F33 fJ by the 11th and 19th century. Such fibers have a thickness of about 1.3 to 1.8 mm and are composed of Bo 11 ethylene and polyvinyl alcohol, with polyvinyl alcohol Ii about 4.0 mm.
It is included as a 4*x counterfeit. The suspension is degassed by bubbling the dried mixture through the system for 15 minutes with continuous stirring.The stirring suspension is then degassed by bubbling the dried mixture through the system for 15 minutes. Add ceric ammonium nitrate initiator solution.

The ceric ammonium nitrate initiator Mu is prepared by dissolving 10 mmol of cerium salt in 1N nitric acid at 100 w/M area.

After completely dispersing the initiator, add a mixture of 31.8F acrylonitrile and 1,000 liters of 55.4F acrylic acid;
The system is then allowed to react for 2 hours at room temperature.

The resulting grafted fibers are now isolated by straining into a Buchner funnel and thoroughly washed with water. The washed fibers are then hydrolyzed with excess 6% sodium hydroxide solution for 30 minutes at reflux temperature. The obtained hydrolysis product is then washed with water until the washing water has a p117 to p8.

Then r! Il! 1111 ivy materials (+ray)
Spread on top and freeze at a temperature of -25° C. in a medium. Next, freeze the ingredients again, New 11
Manufactured by Runqwick 5Ccientific Inc.
ing apparatus (model no. 64) and freeze-dried under an FC atmosphere at equilibrium temperature and between 0 and 5 microns of mercury. The dried product was then fluffed by stirring in a Waring blender (model number 12RL3) at 7 on the mixing scale for 45 seconds.
Obtain a low density absorbent fluff.

EXAMPLE 1 The method for producing grafted SWP described in Example I was demonstrated by adding various degrees of grafted polymers (a
Repeat, except varying the ratio of pulp to total monomer while keeping the ratio of each monomer phase, constant, to obtain dd-nn). Grafting and polymer addition can also compensate for the difference between the bone-dry finished material and the raw pulp.
Defined as the value divided by the material that has been sunk and multiplied by 1[)0.

In addition, samples prepared by the method described in U.S. Pat. Manufacture. Here, 11 samples +', rex+ile roe! l, J, 37
The perforated plate test (Pnrr+us PI; ueTesti
ng) The device is used to test for absorbency, I='ll or maximum capacity (maxin+v+mc+pacHy) and fluid retention (flold+lretention). Briefly, this test consists of placing a sample of fluff in what is essentially a so-called planar funnel with a perforated bottom plate, and applying a standard weight onto it to maintain a standardized confining pressure. This means that the sample is held in place. A perforated plate is placed in contact with the body fluid reservoir and the body fluid is absorbed through the perforated plate until the sample is saturated. By maintaining the sample essentially at the level of the reservoir, the absorbed body fluid is kept at essentially zero hydraulic head with respect to the reservoir. The absorbed body fluid divided by the weight of the sample is called the maximum capacity. To measure fluid retention, a hydraulic head is applied to the absorbed fluid by lifting the saturated sample against the fluid reservoir. This head is arbitrarily selected such as 35.5 CLn of body fluid. This device provides a method for measuring the volume of a body held by a hydraulic head F. Retention force values are reported as the volume retained per unit weight of sample. Test results for various samples of Grafted Synthetic Water Pulp (GSWP) and US Patent 8B9.678 material, Grafted Wood Pulp ((IWP)) are summarized in Section 1 below.
Shown in the table. The test body fluid used was 1 nail needle% N a CjI
It is an aqueous solution.

31 13.2 9.1 -52
17.4 11.7 55 14. , o 6
．． 564 17.5 12.8 -6
9 24.6 16.0 80 17.0 12
．． []9 As can be seen from the table above, at essentially the same polymer loading percentage, the grafting, l'V' synthetic wood <')
Lev exhibits significantly greater absorbency than that of grafted wood pulp.

Example 1 The monomers acrylonitrile and acrylic acid are 1=1
The procedure of Example I is used, except that SWP fibers containing 4 parts of polyvinyl alcohol are introduced at a molar ratio of 1 part of polyvinyl alcohol. 1 liter as well as the wall conversion rate (% polymerization)
l11 is determined. These results are shown in Table 1.

1 0.8 5.0 22.52
2.0 5.0 59.03 3
．． 0 6.9 59.54 4.0
11.9 58.0" As can be seen from the two tables, the maximum capacity increases as the monomer conversion rate increases as well as the amount of polyvinyl alcohol added.

The procedure of Example I was followed to prepare the example samples, but with
1 keeping the vinyl alcohol content constant at 4%, and the monomer acrylonitrile λ1 1,000 mols of acrylic acid)
change the meaning. Again, both the maximum body fluid force and monomer conversion are measured as described in the previous Example 1. The TML Table shows the results obtained.

5 [30,20 60,54,059 71,011,95:/ 8 2.0 90 459
3.0 B, 9 44 As can be seen from the table above, the maximum capacity and monomer conversion rate are also 1.0.
The monomer ratio is the highest.

Example V A series of samples were fluffed according to the method of Example (2), and the fluff material was fluffed with high-density lIV. Sample 6 is a Gwp sample of Example 1 Series 1 with 80% polymer loading. Samples 4 and 5 are samples of SW Crafted SW
P, /l\ This is the sample shown in the regular sample after 4 samples of the number of times it was carried out. The difference between Sample 4 and Sample 5 is that the former was lyophilized and the latter was dried by solvent extraction. Freeze-drying is carried out in accordance with the procedure in Example ①. Solvent extraction.

This is accomplished by first rinsing the wet hydrolyzed material with water to p117-8. 1 of the cleaned old materials
Then, in acetone, 100 f of the reduced material to 1!
After dispersing in acetone at a ratio of , it is filtered. The filtered cake was then dried in a hot air circulation oven at 80°C.
4-ru. All samples are fluffed as described in Example 1. The results of the density measurements and absorbency tests are shown in Table 1V below.

Absorbency (cc/f) 1 Wood pulp 0.030 12 2
2 SWP 01124 2
13 ()WT'0.1<S
o i8 134 (ISWP (freeze-drying) old) 15 1'9 1ro5 ()SWP
, (Solvent Extraction) 0.020 22 As can be seen from the table in Table 1, the ungrafted raw material wood valve and SWP both have essentially the same low density and low retention properties. More hydrophilic wood pulps exhibit substantially higher maximum capacities. When grafted onto an irrigation valve, the iWP sample showed a significant increase in both maximum capacity and retention, and unfortunately a concomitant increase in bulk density. Similarly, Hv
Grafting to p7. When the GSWP samples were prepared using the GSWP sample, both samples 4 and 5 J- also showed a significant increase in the suction 1 reaction over that of the grafted wood valve sample. However, the grafted pulp or synthetic water pulp of the present invention exhibited a bulk density as low as that of the raw material.

Claims (1)

[Claims] 1. capable of producing low-density fluff and consisting of a polyolefin and polyvinyl alcohol, the polyvinyl alcohol having a portion of a hydrophilic polymer grafted thereto; Synthetic wood pulp fibers with hydrophilic, water-retaining properties. 2. The fiber according to claim 1, comprising: [)1
1.7 The hydrophilic poly(117) moiety is of the general formula: wherein It' and R2 are selected from the group consisting of hydrogen and alkyl having 1 to 4 carbon atoms, and X and Y
-UI1. -0 (alkali metal), and -N ■
, 1m is 0 to about 5. DOO
is an integer that represents the value of , where n is OB or approximately 5.0 []
It is an integer that makes the value of O 41. in and 11 il on the chain (the total number of minutes is at least 5
110, p is an integer having a valence of O or 1, and q is an integer having a filli of 1 to 4. 3. The fiber according to claim 2. The chain is poly(acrylic acid), poly(acrylic acid)
Alkali and their copolymers are also θ). 4. The fiber according to item 1, wherein the polyvinyl alcohol is present in an amount of at least about 0.5% by weight based on the weight of the polyolefin and the polyvinyl alcohol. 6. The fiber of claim 4, wherein the polyvinyl alcohol is present in an amount of at least about 0.8% by weight based on the weight of the poly(olefin) and the poly(vinyl alcohol). , the fiber according to claim 1, wherein the poly(,3refine) is made of polyethylene.
To 2, please apply for a patent in this range No.1jη'i3L
And. The polyC olefin) is made of polyzolopyrene. 8. The fiber according to claim 1. The hydrophilic polymer) 111% contains the grafted synthetic water pulp fibers from about 10% to about 90%. 9. The fiber according to claim 8. The hydrophilic polymer portion has a weight of about 40 to about 130
ffi...X said grafted synthetic wood pulp fiber if
Something that separates 1. 1 [) Special features] [The fibers according to claim 1jI'i. nil low density i1:t: fluff having a density of about o, o1 to about 0.059 Ac.