EP0223908A2 - Process for continuous production of nonwoven highly water-absorbent complex - Google Patents
Process for continuous production of nonwoven highly water-absorbent complex Download PDFInfo
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- EP0223908A2 EP0223908A2 EP86107597A EP86107597A EP0223908A2 EP 0223908 A2 EP0223908 A2 EP 0223908A2 EP 86107597 A EP86107597 A EP 86107597A EP 86107597 A EP86107597 A EP 86107597A EP 0223908 A2 EP0223908 A2 EP 0223908A2
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- nonwoven
- web
- activator
- peroxide
- fibrous web
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- D—TEXTILES; PAPER
- D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
- D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
- D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
- D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
- D04H1/58—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives
- D04H1/64—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives the bonding agent being applied in wet state, e.g. chemical agents in dispersions or solutions
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- D—TEXTILES; PAPER
- D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
- D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
- D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
- D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
- D04H1/58—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives
- D04H1/587—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by applying, incorporating or activating chemical or thermoplastic bonding agents, e.g. adhesives characterised by the bonding agents used
Definitions
- the present invention relates to a process for the continuous production of a nonwoven highly water-absorbent complex used as a humor absorbent, including paper diapers and sanitary articles.
- an absorbent complex produced by irradiation is disclosed in International Application No. PCT/US81/00601 (W081/03274). More specifically, after applying an aqueous acrylic acid or methacrylate solution to a fibrous substrate, an attempt is made to obtain an absorbent complex by applying electromagnetic radioactive rays or fine-particulate ionization radioactive rays to this material so as to convert the acrylic acid or methacrylate into a water-swelling polymer. Since a monomer can be used directly, this method is epoch-making in comparison with the conventional art in which powdered polymer is mixed with wood pulp and the like (see Japanese Patent Publication No. 53-46199).
- the aforementioned prior art has drawbacks in that (1) since a self-crosslinking reaction is carried out, the water-absorption properties of a complex obtained are inferior to those of a particulate water-absorbent polymer; (2) large- scale and highly expensive apparatuses including an electron beam accelerator are required, and the process thereof also becomes complicated, with the result that the amount of investment needed becomes large; and (3) the amount of residual monomers is large.
- the problem of the invention is, therefore, to overcome the drawbacks of the prior art by providing a process for producing a nonwoven complex having excellent water-absorption properties continuously at high speed.
- This problem is solved according to the present invention by adding in advance to an aqueous monomer solution a crosslinking agent and an oxidizing radical polymerization initiating agent having a latent activity, and after impregnating a continuous nonwoven fibrous web with this solution, causing a rapid polymerization reaction by adding an activator (i.e. an oxidizing agent or a reducing agent) to this web so as to form a water-swelling polymer in the web, thereby continuously forming a nonwoven highly water-absorbent complex.
- an activator i.e. an oxidizing agent or a reducing agent
- Fig.1 is a flow sheet briefly showing the process of the present invention.
- the nonwoven fibrous web In terms of properties, it is necessary for a nonwoven fibrous web to be bulky and porous as well as outstanding in compression recovery. Accordingly, the nonwoven fibrous web should desirably have an apparent density of 0.05 g/cm 3 or below (preferably 0.002 to 0.02 g/cm3 ) and a compression recovery rate * of 80% or above.
- polyester, polypropylene, or polyethylene hydrophobic fibers having a fineness of 3d or above (preferably 4 to 10d) and a hollow and irregular-shaped cross section are used.
- a 20 to 60 g/m 2 parallel web and a random web are formed from a fibrous mixture by the use of the card process, the air laid process, or other similar process. Subsequently, these webs are treated in a cylindrical drier or other heat treatment apparatus at a temperature of 150 to 250 C so as to couple the fibers.
- a monomer used in the present invention is an acrylic acid or one essentially constituted by the same, and 50% or more thereof is preferably neutralized by an alkali metallic salt, e.g. a sodium salt or a potassium salt.
- an alkali metallic salt e.g. a sodium salt or a potassium salt.
- One of the characteristic features of the present invention is the use of a crosslinking agent, which proves extremely advantageous in controlling the properties of the polymer and makes it possible to widen the range of selection of reaction conditions in comparison with the self-crosslinking type employed in the prior art.
- the crosslinking agent is selected from compounds having properties of copolymerization with an acrylic monomer, compounds having reactivity with a functional group of an acrylic acid monomer, or compounds having the properties of both of these two types of compounds.
- Typical examples of this crosslinking agent are ethylene glycol bis-acryiate, N,N-methylene bis-acrylamide, ethylene glycol glycidyl ether and N-methylolacrylamide.
- the amount of the crosslinking agent to be added is preferably 0.1% to 3% by weight of the polymeric monomer. If the amount is too small, a problem arises in the stability of the gel: if too large, the water-absorbing capability decreases.
- the radical polymerization initiator employed in the present invention must be such as to be capable of forming a redox system with an amine and a reducing agent which have a certain degree of solubility with respect to a monomer or water and must exhibit oxidizing properties.
- radical polymerization initiators having such properties it is possible to use peroxides, e.g. hydrogen peroxide, persulfates such as ammonium persulfate and potassium persulfate, and hydroperoxides such as t-butyl hydroperoxide and cumene hydroperoxide.
- a water soluble radical polymerization intiator of azo type which has no oxidizing properties, cannot form a redox system with an amine or reducing agent; therefore, it cannot be used in the present invention.
- the amount of the radical polymerizaiton initiator used is preferably 0.1 to 2% by weight of the monomer.
- An activator capable of causing polymerizaiton reaction rapidly in a predetermined period of time should form a redox system with the aformentioned oxidizing radical polymerization initiator.
- amines e.g. aniline, monoethanol amine, diethanol amine, triethanol amine and dimethyl aniline
- water soluble reducing agents e.g. sodium sulfite, sodium hydrogensulfite, sodium thiosulfate, copper sulfate, ferrous sulfate, and L-ascorbic acid and salts thereof, erysorbic acid (isoascorbic acid) and salts thereof, polyphenols, such as gallic acid, and derivatives thereof.
- the amount of the activator added is preferably 0.01 to 4% by weight of the monomer.
- the nonwoven fibrous web containing, the mixed solution of the monomer, the crosslinking agent and the oxidizing radical polymerization initiator causes a rapid polymerrisation reactiion with the addition of the activator.
- the web containg the mixed solution should be stable for a long time before the activator is added.
- the rapid polymerization reaction should take place and be completed within a short time.
- a highly water-absorbent polymer having a sufficient water-absorbing capability should be formed stably in the nonwoven fibrous web. Described below are the desirable conditions for this polymerization reaction.
- the mixed monomer solution is adhered to the nonwoven web by means of impregnation, coating or spraying.
- the amount of the mixed monomer solution to be adhered and the conditions of adhesion vary according to the complex to be obtained, but the rate of pickup is normally 1 to 20 weight parts with respect to 1 weight part of the web.
- amine or the reducing agent When adding the amine or the reducing agent, it is advantageous to use the same as it is or in the form of an aqueous solution if it is a solution, or if it is a solid, it should be used in the form of an aqueous solution containing it. It is effective to spray a predetermined amount of it onto the monomer-containing web, and it is desirable to spray it onto both sides of the web as uniformly as possible.
- post-treatment including drying for controlling the residual moisture content, softining treatment, or lamination bonding with wooden pulp layers by making use of the residual moisture content, is carried out before effecting a final winding-up process so as to produce the nonwoven highly water-absorbent complex.
- the complex thus obtained is cut into a predetermined size, or folded, and can be used as the inner absorbent for disposable diapers for infants, the absorbent for diapers for adults, or the absorbent for sanitary napkins, or, in some cases, as the absorbent for construction material and the like.
- the following advantages can be obtained: (1) since the polymerization speed is high, continuous production can be effected easily, and it is possible to use compact apparatuses for produciton; (2) since the reaction is carried out uniformly, it is possible to effect the production under smooth and stable operating conditions, and (3) the degree of crosslinking and the degree of polymerization can be controlled.
- a 50 g/m 2 web was formed from 70% of 6d x 51 mm hollow polyester fibers (made by Teijin Co., Ltd.) and 30% of 3d x 51 mm heat-fusible polypropylene conjugated fibers (made by Chisso Co., Ltd.) using a card.
- the web was subsequently led into a heat treatment apparatus (made by Honeycomb Co., Ltd.) heated to 220 °C and a nonwoven fabric having the following properties was produced.
- a 40 % aqueous sodium hydroxide solution and pure acrylic acid (made by Sumitomo Chemical Co., Ltd. and conforming to JIS) were mixed in a water- cooled tank having a capacity of 40 litres, and sodium acrylate solution having a neutralization rate of 80 % and a monomer concentration of 42 wt.% was prepared.
- N, N-methylene bis-acrylamide was then dissolved in this solution in a proportion of 0.2 % by weight of the monomer.
- potassium peroxide was dissolved in said solution in a proporiton of 0.3 % by weight of the monomer.
- This mixed monomer solution was adjusted at 60 C through a heat exchanger and was then introduced into a roll coater.
- the aforementioned nonwoven fabric was impregnated with the mixed monomer solution on both sides thereof by a double roll coater such that a pickup rate of 1000 wt.% was achieved.
- the above-described impregnated nonwoven fabric was let onto a stainless conveyor, and as the reducing ahgent a 7 % aqueous sodium hydrogensulfite solution heated to 50 C was adhered uniformly to a sheet from above using a spray. This resulted in polymerization reaction accrmpanying sudden generation of heat.
- the impregnated nonwoven fabric was then passed in a falling state through the reaction tank in such a manner as to oppose the flow of air heated to 120 C and the polymerization reaction was completed in approximately 10 seconds, and it was possible to obtain a complex containing a hihgly water-absorbent polymer solidified in the nonwoven fabric. This complex was then passed through a drier and dried to a moisture content of 10 %.
- the physiological saline absorbing capacity of this complex was 55 and the residual monomer was approximately 100 ppm.
- the weight of the complex was 200 g/ m 2 .
- a carded web was made of 80% of 8d x 51 mm hollow conjugated polyester fibers (made by Mitsubishi Rayon Co., Ltd.) and 20% of 3d x 51 mm polyester heat-fusible fibers (marketed by Uni-Chika Co., Ltd. under the reference Melty). This web was led continuously into an oven wherein 250°C heated-air was circulated, and it was possible to obtain a nonwoven fabric in which heat-fusible fibers were melted and the web- constituting components bonded together.
- the porperties of the nonwoven fabric were as follows:
- a 70 wt.% aqueous potassium acrylate solution was prepared with the same apparatus as the one used in Example 1 under cooling condition, employing sodium hydroxide. The neutralization rate was 75%. N-methylene bis-acrylamide was then added to this aqueous monomer solution so that its concentration would become 0.3% by weight of the monomer. Then, as the oxidizing radical polymerization initiator hydrogen peroxide was added to the mixed solution and was mixed so that its concentration would become 0.2% by weight of the pure monomer.
- a mixed monomer solution was adhered to one side of the aforementioned nonwoven fabric by the roll coater such that the pickup rate of about 500 wt.% was achieved.
- the above-described monomer-adhered nonwoven fabric was passed in a falling state through the reaction tank heated to 100 t. Subsequently, a 7% aqueous monoethanolamine solution was sprayed perpendicularly on the monomer-coated surface of the nonwoven fabric in the upper layer of the reaction tank, and the polymerization reaction was completed in approximately 15 minutes. Consequently, it was possible to obtain a highly water-absorbent complex having a structure in which polymers having a larger particle size were distributed on one side of the nonwoven fabric.
- Example 1 150g/m 2 wooden pulp mat (NBKP made by Rayonier Co., Ltd.) was bonded to both sides of the complex obtained in Example 1 by applying water to the surface of the complex, and pressing was effected for this structure.
- This structure was cut into dimensions of 25 cm (hight) x 33 cm (length). After removing the absorbent of a commercially available paper diaper, the structure was inserted into said paper diaper and a consumer test was carried out. It was found that the articles according to the present invention have doubled its rate of water absorption in comprison with commercially available ones. Thus, it was possible to obtain the absorbent in which the rate of occurrence of leakage was extremely low even without replacement at night.
Abstract
Description
- The present invention relates to a process for the continuous production of a nonwoven highly water-absorbent complex used as a humor absorbent, including paper diapers and sanitary articles.
- As a prior art of the present invention, an absorbent complex produced by irradiation is disclosed in International Application No. PCT/US81/00601 (W081/03274). More specifically, after applying an aqueous acrylic acid or methacrylate solution to a fibrous substrate, an attempt is made to obtain an absorbent complex by applying electromagnetic radioactive rays or fine-particulate ionization radioactive rays to this material so as to convert the acrylic acid or methacrylate into a water-swelling polymer. Since a monomer can be used directly, this method is epoch-making in comparison with the conventional art in which powdered polymer is mixed with wood pulp and the like (see Japanese Patent Publication No. 53-46199).
- However, the aforementioned prior art has drawbacks in that (1) since a self-crosslinking reaction is carried out, the water-absorption properties of a complex obtained are inferior to those of a particulate water-absorbent polymer; (2) large- scale and highly expensive apparatuses including an electron beam accelerator are required, and the process thereof also becomes complicated, with the result that the amount of investment needed becomes large; and (3) the amount of residual monomers is large.
- The problem of the invention is, therefore, to overcome the drawbacks of the prior art by providing a process for producing a nonwoven complex having excellent water-absorption properties continuously at high speed.
- This problem is solved according to the present invention by adding in advance to an aqueous monomer solution a crosslinking agent and an oxidizing radical polymerization initiating agent having a latent activity, and after impregnating a continuous nonwoven fibrous web with this solution, causing a rapid polymerization reaction by adding an activator (i.e. an oxidizing agent or a reducing agent) to this web so as to form a water-swelling polymer in the web, thereby continuously forming a nonwoven highly water-absorbent complex.
- Fig.1 is a flow sheet briefly showing the process of the present invention.
- More detailed description will be made hereinafter with reference to a flow sheet shown in the attached drawing.
- In terms of properties, it is necessary for a nonwoven fibrous web to be bulky and porous as well as outstanding in compression recovery. Accordingly, the nonwoven fibrous web should desirably have an apparent density of 0.05 g/cm3 or below (preferably 0.002 to 0.02 g/cm3 ) and a compression recovery rate* of 80% or above. To obtain the web having such properties, polyester, polypropylene, or polyethylene hydrophobic fibers having a fineness of 3d or above (preferably 4 to 10d) and a hollow and irregular-shaped cross section are used. To prepare a nonwoven web from these fibers, a 20 to 60 g/m2 parallel web and a random web are formed from a fibrous mixture by the use of the card process, the air laid process, or other similar process. Subsequently, these webs are treated in a cylindrical drier or other heat treatment apparatus at a temperature of 150 to 250 C so as to couple the fibers.
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- 1VO.5 = the bulk (mm) of a sample web when it is treated for 10 minutes under a light load of 0.5 g/cm2.
- V1 = the bulk (mm) of a sample web when it is treated for 5 hours under a heavy load of 50 g/cm2 .
- 2V0.5 = the bulk(mm) of a sample web when a light load of 0.5 g/cm2 is applied to it for 10 minutes after being left for 30 minutes as it is on measurement of V1.
- A monomer used in the present invention is an acrylic acid or one essentially constituted by the same, and 50% or more thereof is preferably neutralized by an alkali metallic salt, e.g. a sodium salt or a potassium salt. In view of the subsequent dehydrating process, the higher the concentration of the monomer, the greater the economic efficiency, with the result that it is advantageous to set the concentration of the monomer to the vicinity of saturation solubility in a working temperature.
- One of the characteristic features of the present invention is the use of a crosslinking agent, which proves extremely advantageous in controlling the properties of the polymer and makes it possible to widen the range of selection of reaction conditions in comparison with the self-crosslinking type employed in the prior art.
- The crosslinking agent is selected from compounds having properties of copolymerization with an acrylic monomer, compounds having reactivity with a functional group of an acrylic acid monomer, or compounds having the properties of both of these two types of compounds. Typical examples of this crosslinking agent are ethylene glycol bis-acryiate, N,N-methylene bis-acrylamide, ethylene glycol glycidyl ether and N-methylolacrylamide. The amount of the crosslinking agent to be added is preferably 0.1% to 3% by weight of the polymeric monomer. If the amount is too small, a problem arises in the stability of the gel: if too large, the water-absorbing capability decreases.
- The radical polymerization initiator employed in the present invention must be such as to be capable of forming a redox system with an amine and a reducing agent which have a certain degree of solubility with respect to a monomer or water and must exhibit oxidizing properties. As radical polymerization initiators having such properties, it is possible to use peroxides, e.g. hydrogen peroxide, persulfates such as ammonium persulfate and potassium persulfate, and hydroperoxides such as t-butyl hydroperoxide and cumene hydroperoxide.
- For instance, a water soluble radical polymerization intiator of azo type, which has no oxidizing properties, cannot form a redox system with an amine or reducing agent; therefore, it cannot be used in the present invention.
- Incidentally, the amount of the radical polymerizaiton initiator used is preferably 0.1 to 2% by weight of the monomer.
- An activator capable of causing polymerizaiton reaction rapidly in a predetermined period of time should form a redox system with the aformentioned oxidizing radical polymerization initiator. For instance, one or more of the following may be used: amines, e.g. aniline, monoethanol amine, diethanol amine, triethanol amine and dimethyl aniline; and water soluble reducing agents, e.g. sodium sulfite, sodium hydrogensulfite, sodium thiosulfate, copper sulfate, ferrous sulfate, and L-ascorbic acid and salts thereof, erysorbic acid (isoascorbic acid) and salts thereof, polyphenols, such as gallic acid, and derivatives thereof. The amount of the activator added is preferably 0.01 to 4% by weight of the monomer.
- As descriged above, the nonwoven fibrous web containing, the mixed solution of the monomer, the crosslinking agent and the oxidizing radical polymerization initiator causes a rapid polymerrisation reactiion with the addition of the activator. In view of te fact that this is a continous process, the web containg the mixed solution should be stable for a long time before the activator is added. After the addition of the activating agent, the rapid polymerization reaction should take place and be completed within a short time. In addition, a highly water-absorbent polymer having a sufficient water-absorbing capability should be formed stably in the nonwoven fibrous web. Described below are the desirable conditions for this polymerization reaction.
- The Amount of Mixed Monomer Solution to be Adhered to the Nonwoven Web.
- The mixed monomer solution is adhered to the nonwoven web by means of impregnation, coating or spraying. The amount of the mixed monomer solution to be adhered and the conditions of adhesion vary according to the complex to be obtained, but the rate of pickup is normally 1 to 20 weight parts with respect to 1 weight part of the web.
- Conditions of Addition of Activator.
- When adding the amine or the reducing agent, it is advantageous to use the same as it is or in the form of an aqueous solution if it is a solution, or if it is a solid, it should be used in the form of an aqueous solution containing it. It is effective to spray a predetermined amount of it onto the monomer-containing web, and it is desirable to spray it onto both sides of the web as uniformly as possible.
- Adjustment of Polymerization Reaction Time.
- The adjustment of polymerization reaction time is depending on the following factors:
- a. The concentration and temperature of the monomer to be mixed in the web.
- b. The amount of polymerization heat generated.
- c. The concentration and temperature of the activating agent.
- d. The ambient temperature of a reaction tank at the time of polymerization reaction.
- However, it is a general practice to adjust the polymerization time by controlling the temperature of the reaction tank described in d above.
- It is possible to control the polymerization reaction time between 5 sec. to 1 hour by selecting the conditions a,b,c and d above. However, it is desirable to complete the polymerization reaction within 20 sec., preferably 10 sec., by maintaining the temperature of the reaction tank at 50 to 120 C.
- With respect to the web for which polymerization is completed, post-treatment, including drying for controlling the residual moisture content, softining treatment, or lamination bonding with wooden pulp layers by making use of the residual moisture content, is carried out before effecting a final winding-up process so as to produce the nonwoven highly water-absorbent complex. The complex thus obtained is cut into a predetermined size, or folded, and can be used as the inner absorbent for disposable diapers for infants, the absorbent for diapers for adults, or the absorbent for sanitary napkins, or, in some cases, as the absorbent for construction material and the like.
- As described above, according to the present invention, the following advantages can be obtained: (1) since the polymerization speed is high, continuous production can be effected easily, and it is possible to use compact apparatuses for produciton; (2) since the reaction is carried out uniformly, it is possible to effect the production under smooth and stable operating conditions, and (3) the degree of crosslinking and the degree of polymerization can be controlled.
- The following examples describe the present inveniton, although these should not be considered as a limitaiton to the object of the present invention.
- A 50 g/m2 web was formed from 70% of 6d x 51 mm hollow polyester fibers (made by Teijin Co., Ltd.) and 30% of 3d x 51 mm heat-fusible polypropylene conjugated fibers (made by Chisso Co., Ltd.) using a card. The web was subsequently led into a heat treatment apparatus (made by Honeycomb Co., Ltd.) heated to 220 °C and a nonwoven fabric having the following properties was produced.
- A 40 % aqueous sodium hydroxide solution and pure acrylic acid (made by Sumitomo Chemical Co., Ltd. and conforming to JIS) were mixed in a water- cooled tank having a capacity of 40 litres, and sodium acrylate solution having a neutralization rate of 80 % and a monomer concentration of 42 wt.% was prepared. N, N-methylene bis-acrylamide was then dissolved in this solution in a proportion of 0.2 % by weight of the monomer. Then, as the oxidizing radical polymerization initiator, potassium peroxide was dissolved in said solution in a proporiton of 0.3 % by weight of the monomer. This mixed monomer solution was adjusted at 60 C through a heat exchanger and was then introduced into a roll coater.
- The aforementioned nonwoven fabric was impregnated with the mixed monomer solution on both sides thereof by a double roll coater such that a pickup rate of 1000 wt.% was achieved.
- The above-described impregnated nonwoven fabric was let onto a stainless conveyor, and as the reducing ahgent a 7 % aqueous sodium hydrogensulfite solution heated to 50 C was adhered uniformly to a sheet from above using a spray. This resulted in polymerization reaction accrmpanying sudden generation of heat. The impregnated nonwoven fabric was then passed in a falling state through the reaction tank in such a manner as to oppose the flow of air heated to 120 C and the polymerization reaction was completed in approximately 10 seconds, and it was possible to obtain a complex containing a hihgly water-absorbent polymer solidified in the nonwoven fabric. This complex was then passed through a drier and dried to a moisture content of 10 %.
- The physiological saline absorbing capacity of this complex was 55 and the residual monomer was approximately 100 ppm. The weight of the complex was 200 g/m 2.
- ** Physiological saline Absorbin Capacity; 1 g of the complex is placed in a 500 ml beaker, 300 g of 0.9 wt.% physiological saline solution is added, and the mixture is left as it is for 2 hours. After that the mixture is filtered by a 100-mesh filter, and the physiological saline absorbing capacity is caluculated by the following formula;
- A carded web was made of 80% of 8d x 51 mm hollow conjugated polyester fibers (made by Mitsubishi Rayon Co., Ltd.) and 20% of 3d x 51 mm polyester heat-fusible fibers (marketed by Uni-Chika Co., Ltd. under the reference Melty). This web was led continuously into an oven wherein 250°C heated-air was circulated, and it was possible to obtain a nonwoven fabric in which heat-fusible fibers were melted and the web- constituting components bonded together. The porperties of the nonwoven fabric were as follows:
-
- A 70 wt.% aqueous potassium acrylate solution was prepared with the same apparatus as the one used in Example 1 under cooling condition, employing sodium hydroxide. The neutralization rate was 75%. N-methylene bis-acrylamide was then added to this aqueous monomer solution so that its concentration would become 0.3% by weight of the monomer. Then, as the oxidizing radical polymerization initiator hydrogen peroxide was added to the mixed solution and was mixed so that its concentration would become 0.2% by weight of the pure monomer.
- A mixed monomer solution was adhered to one side of the aforementioned nonwoven fabric by the roll coater such that the pickup rate of about 500 wt.% was achieved.
- The above-described monomer-adhered nonwoven fabric was passed in a falling state through the reaction tank heated to 100 t. Subsequently, a 7% aqueous monoethanolamine solution was sprayed perpendicularly on the monomer-coated surface of the nonwoven fabric in the upper layer of the reaction tank, and the polymerization reaction was completed in approximately 15 minutes.
Consequently, it was possible to obtain a highly water-absorbent complex having a structure in which polymers having a larger particle size were distributed on one side of the nonwoven fabric. - Physiological saline absorbing capacity: 48 residual monomers; trace
- 150g/m2 wooden pulp mat (NBKP made by Rayonier Co., Ltd.) was bonded to both sides of the complex obtained in Example 1 by applying water to the surface of the complex, and pressing was effected for this structure. This structure was cut into dimensions of 25 cm (hight) x 33 cm (length). After removing the absorbent of a commercially available paper diaper, the structure was inserted into said paper diaper and a consumer test was carried out. It was found that the articles according to the present invention have doubled its rate of water absorption in comprison with commercially available ones. Thus, it was possible to obtain the absorbent in which the rate of occurrence of leakage was extremely low even without replacement at night.
Claims (5)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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JP256594/85 | 1985-11-18 | ||
JP25659485 | 1985-11-18 |
Publications (3)
Publication Number | Publication Date |
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EP0223908A2 true EP0223908A2 (en) | 1987-06-03 |
EP0223908A3 EP0223908A3 (en) | 1989-07-12 |
EP0223908B1 EP0223908B1 (en) | 1993-02-24 |
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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EP86107597A Expired - Lifetime EP0223908B1 (en) | 1985-11-18 | 1986-06-04 | Process for continuous production of nonwoven highly water-absorbent complex |
Country Status (3)
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EP (1) | EP0223908B1 (en) |
DE (1) | DE3687823T2 (en) |
ES (1) | ES2001289A6 (en) |
Cited By (5)
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US5268229A (en) * | 1992-07-23 | 1993-12-07 | Eastman Kodak Company | Spinneret orifices and filament cross-sections with stabilizing legs therefrom |
DE4420088A1 (en) * | 1994-06-09 | 1995-12-14 | Stockhausen Chem Fab Gmbh | Method of making a water absorbent sheet and use |
US5723159A (en) * | 1989-04-04 | 1998-03-03 | Eastman Chemical Company | Spinnerets for making fibers capable of spontaneously transporting fluids |
US7338625B2 (en) | 2002-09-18 | 2008-03-04 | Kimberly-Clark Worldwide, Inc. | Methods of restoring elasticity after stiffening treatments |
US10161080B2 (en) * | 2013-03-06 | 2018-12-25 | Carl Freudenberg Kg | Ventilation insert |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6872275B2 (en) | 2001-12-14 | 2005-03-29 | Kimberly-Clark Worldwide, Inc. | Process for adding superabsorbent to a pre-formed fibrous web via in situ polymerization |
US7018497B2 (en) | 2001-12-14 | 2006-03-28 | Kimberly-Clark Worldwide, Inc. | Method of making an absorbent structure having high integrity |
US6918981B2 (en) | 2001-12-14 | 2005-07-19 | Kimberly-Clark Worldwide, Inc. | Process for adding superabsorbent to a pre-formed fibrous web using two polymer precursor streams |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
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GB962458A (en) * | 1959-07-27 | 1964-07-01 | Rohm & Haas | Bonded non-woven fibrous products and methods of making them |
WO1980001031A2 (en) * | 1979-02-28 | 1980-05-15 | Du Pont | Polyester fiberfill blends |
EP0019169B1 (en) * | 1979-05-19 | 1983-01-26 | BASF Aktiengesellschaft | Use of an aqueous dispersion of an emulsion copolymer that contains amide groups for bonding nonwovens |
-
1986
- 1986-06-04 DE DE86107597T patent/DE3687823T2/en not_active Expired - Fee Related
- 1986-06-04 EP EP86107597A patent/EP0223908B1/en not_active Expired - Lifetime
- 1986-09-03 ES ES8601600A patent/ES2001289A6/en not_active Expired
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB962458A (en) * | 1959-07-27 | 1964-07-01 | Rohm & Haas | Bonded non-woven fibrous products and methods of making them |
WO1980001031A2 (en) * | 1979-02-28 | 1980-05-15 | Du Pont | Polyester fiberfill blends |
EP0019169B1 (en) * | 1979-05-19 | 1983-01-26 | BASF Aktiengesellschaft | Use of an aqueous dispersion of an emulsion copolymer that contains amide groups for bonding nonwovens |
Non-Patent Citations (1)
Title |
---|
CHEMICAL ABSTRACTS, vol. 107, no. 16, 19th October 1987, page 84, abstract no. 135863g, Columbus, Ohio, US; & JP-A-62 97 979 (MITSUBISHI PETROCHEMICAL CO., LTD) 07-05-1987 * |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5723159A (en) * | 1989-04-04 | 1998-03-03 | Eastman Chemical Company | Spinnerets for making fibers capable of spontaneously transporting fluids |
US5733490A (en) * | 1989-04-04 | 1998-03-31 | Eastman Chemical Company | Process for helically crimping a fiber |
US5855798A (en) * | 1989-04-04 | 1999-01-05 | Eastman Chemical Company | Process for spontaneouly transporting a fluid |
US5972505A (en) * | 1989-04-04 | 1999-10-26 | Eastman Chemical Company | Fibers capable of spontaneously transporting fluids |
US5268229A (en) * | 1992-07-23 | 1993-12-07 | Eastman Kodak Company | Spinneret orifices and filament cross-sections with stabilizing legs therefrom |
DE4420088A1 (en) * | 1994-06-09 | 1995-12-14 | Stockhausen Chem Fab Gmbh | Method of making a water absorbent sheet and use |
DE4420088C3 (en) * | 1994-06-09 | 2001-02-15 | Stockhausen Chem Fab Gmbh | Process for producing a water-absorbing fabric and its use |
US7338625B2 (en) | 2002-09-18 | 2008-03-04 | Kimberly-Clark Worldwide, Inc. | Methods of restoring elasticity after stiffening treatments |
US10161080B2 (en) * | 2013-03-06 | 2018-12-25 | Carl Freudenberg Kg | Ventilation insert |
Also Published As
Publication number | Publication date |
---|---|
DE3687823D1 (en) | 1993-04-01 |
EP0223908A3 (en) | 1989-07-12 |
ES2001289A6 (en) | 1988-05-01 |
DE3687823T2 (en) | 1993-09-30 |
EP0223908B1 (en) | 1993-02-24 |
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