JPS6159733B2 - - Google Patents

Description

[Detailed description of the invention]

This invention relates to absorbent products, and more particularly to improved absorbent compositions for use in diapers, sanitary napkins, and the like. Many single-use products, such as diapers, sanitary napkins, and some tampons and absorbent surgical care products, contain a layer or core made of highly absorbent material.
It is made of a less absorbent material that covers it. In some cases, such as in diapers, the absorbent layer is surrounded on at least one side by an impermeable film material. For example, some diapers consist of a permeable top layer, a highly absorbent middle layer, and an impermeable bottom layer. Sanitary napkins usually consist of a highly absorbent layer surrounded by a permeable layer. Absorbent layers used in non-use products are usually
It consists of multiple layers of crepe paper tissue or, in some cases, chemical wood pulp fibers in a fluffy, loosely compressed form. It has been known for many years that peat moss (sphagnum) has good water absorption properties;
To date, there has been no success in incorporating it as a primary ingredient in compositions suitable for use in diapers, sanitary napkins, surgical dressings, etc. The reason for this was probably both the inherent extremely dark coloration of peat moss, the difficulty in shaping it into a suitable shape suitable for handling and packaging. The inventors have invented a new and improved absorbent composition or core material. This new material is somewhat darker in tone than fluffed chemical wood pulp, but the outer wrapper hides the visible tones, which are bright enough to make this new product suitable for use in diapers, napkins, and absorbent surgical materials. It can be processed and used as an absorbent core material. With the teachings of this invention, it has been unexpectedly discovered that this new product exhibits improved liquid absorption and is able to maintain its structural integrity. This novel material consists of bleached peat moss mixed with a finely dispersed Canadian Standard Freeness of greater than about 0.35 times the weight of said peat moss from about 30 to about Consisting of 600 pieces of mechanical wood pulp. The term "mechanical wood pulp" covers pulp that has been subdivided from the trunk and branches of wood, excluding bark and dust, and has not undergone any prior chemical treatment; Einar pulp, thermo mechanical pulp
pulp). Bleached peat moss Hunter Lumimus Reflective
When measured on a scale, it has a whiteness of at least about 70, yet retains the structure of the original peat moss. That is,
Bleached peat moss retains some humic acid and lignin-like components and still maintains its open, porous, leaf-like structure. This open structure
This peat moss is believed to be responsible for its highly absorbent properties. Unfortunately, peat sludge, in this open, porous state, is quite fragile and cannot by itself withstand the handling that diapers, napkins, tampons and other expropriated products are subjected to.
Furthermore, peat moss debris does not tangle with itself or stick together like the absorbent material of long ropes. In short, peat moss is
By themselves, they are difficult to handle and cannot be formed into self-supporting shapes with structural integrity. The disadvantage of the peat moss mentioned above is that it is mixed with peat moss at a Canadian standard water level (hereinafter referred to as CSF) of about 30 to about 600.
It has been found that this can be overcome by including a relatively fine mechanical wood pulp having a structure (abbreviated as ), resulting in an absorbent composition with surprisingly good absorbency as well as structural integrity. Such pulps are selected from groundwood pulps, refined wood pulps, and/or heated mechanical wood pulps, but generally chemical pulps, such as sulfite pulps, sulfate pulps, with which products such as diapers, sanitary napkins, and tampons are usually mixed. The length of the fiber is shorter than that of Fine mechanical wood pulp is characterized by its drainage and compressibility; it is called "aqueous";
That is, as measured by TAPPl test method T-227.
Represented by CSF. The structural integrity of pulp cotton made from crushed boards formed from an aqueous slurry of a mixture of peat moss and the comminuted mechanical wood pulp described herein is significantly affected by the weight ratio of wood pulp to peat moss. It turned out to be sensitive. Specifically, when the ratio is less than 0.35, the mixture loses its cohesive properties. Preferably this ratio should be kept above 0.38. The mixture of peat moss and mechanical wood pulp may also be reinforced with other absorbent materials such as the more commonly used long-wired wood pulps such as sulfite pulp, sulfate pulp or rayon fibers or mixtures thereof. good. To form a product from the absorbent composition of the invention, a core of a predetermined material as described above is wrapped on its entire surface with a permeable layer, such as a non-woven fabric, for example in sanitary napkins. Alternatively, in disposable diapers, the core is sandwiched between a permeable layer, such as a nonwoven fabric, and an impermeable layer, such as a thermoplastic film. Next, the present invention will be specifically described with reference to the drawings. 1 and 2 illustrate the new and improved material of the present invention, ie, core 10. FIG. This core 10 is
When measured with Hunter Luminus Reflective Scale
It consists of a bleached peat sludge having a whiteness of 70, combined with finely ground mechanical wood pulp 14 having a CSF of about 30 to about 600, the weight of which is the weight of the wood pulp against the peat sludge. at least about
It is 0.35. Preferably this ratio is about 0.4 or greater, more preferably about 0.5 or greater. 10 more cores
Includes other absorbent materials such as long-thread chemical wood pulp 16 and long-thread rayon. The peat moss 12 has a leaf-like structure with open pores 18, as seen in detail in the photomicrograph sketch of FIG.
Above all, maintain this organization. Bleached peat moss 12
has a whiteness of at least about 70 as measured on the Hunter Color and Color Difference Scale as set forth in the Color Scale of ASTM D-2244. From peat moss (Sphagnum spp.) which holds at least 15 times its weight in water, preferably 20 times. The peat moss is sifted to a size between 10 and 100 mesh. 10 What is left over from the mesh sieve is mainly roots and branches, which are thrown away. 100
What passes through the mesh sieve, that is, fine powder, hardly contributes to absorbency and is difficult to bleach, so it is discarded.
Therefore, the peat moss which is the starting material of the present invention has a content of about 0.15
mm (100 meshes) or approximately 1.8mm (10 meshes)
The dimensions are Peat moss is bleached by chlorine and calcium in the form of limestone. Bleaching can be carried out batchwise. The peat moss is diluted with water to 2% by weight, treated with chlorine, then treated with calcium carbonate, and then pickled and washed with water to obtain the desired whiteness. Bleached peat moss can be handled and
It is dried to such an extent that it can be layered into plates or sheets if desired. When molded into a board, the finely crushed mechanical wood pulp 14 and optionally long wood pulp 16 are molded together, and then this mixture is thoroughly dried and finished into a board. To produce the absorbent wick, peat moss and mechanical wood pulp are produced by a standard grinding operation such as a hammer mill, and a carrier sheet (which can be a wrapper sheet or a sheet of tissue) may be placed on top in any desired amount as is well known in the art. Finely ground mechanical wood pulp is groundwood pulp,
selected from the group consisting of heated mechanical pulp and refined wood pulp. Groundwood pulp is essentially
Wood and branches that have had their bark removed, cleaned and ground into granules. Refiner wood pulp is a groundwood pulp that is ground by a refiner, that is, as is well known in the art, a disk-shaped device that generally has metal ribs around its periphery.
It remains in contact with the wood grains and has the effect of separating the wood grains without unduly damaging them. Heated mechanical wood fibers are similar to refiner wood pulps, except that in the refiner the wood grains are heated, usually by steam, and this heating further aids in the separation of the wood fibers. A common characteristic of these mechanical pulps is that they are not separated by chemical means. After being granulated, it may undergo chemical treatment, such as bleaching. These mechanical pulps are characterized by their "water content" as measured by the conventional CSF test (TAPPI test method T-227). This test essentially measures the rate of water drainage of the pulp, which in turn measures the degree of densification. Suitable CSF values for the mechanical wood pulp material incorporated into the absorbent barrel material of the present invention are from about 30 to about 600, preferably from about 60 to about 300. Long-thread wood pulp is approximately 5 to 50% of the total weight of the core.
Accounting for 20%, chemically processed wood pulps such as sulfite wood pulp and sulfate wood process are chosen. The wood pulp is preferably selected from softwood materials, although hardwood fibers can also be used. The term "long-walled wood pulp" refers to fibers at least 40% by weight consisting of fibers larger than 1/16 inch (0.158 cm), preferably 50% by weight consisting of fibers larger than 1/16 inch (0.158 cm). means. FIG. 4 shows a disposable diaper 20 using the improved absorbent core material of the present invention. The diaper has a backing layer 21 of thermoplastic fluid-impermeable film material.
including. The diaper also includes a surface layer 22, which is fluid permeable and may be made of any standard type of nonwoven fabric, such as a spunpond product, a spunlace product, or a standard carded nonwoven fabric; may be a transparent film material. Between the front and back layers is the new and improved absorbent core material 23 of the present invention, which is slightly smaller. FIG. 5 shows a sanitary napkin 24 that includes the absorbent core material of the present invention. In this configuration, the napkin includes a central barrier sheet 25. It may also be made of thermoplastic film. Absorbent core 2 made of the absorbent core material of the present invention is provided on both sides of this central sheet.
There are 6. This three-layer laminate is wrapped on all sides with a suitable permeable material 27, such as a standard non-woven fabric. The wrapper extends beyond the ends of the absorbent core material and is formed with tabs 28 for attaching the napkin. FIG. 6 shows a tampon 29 containing the absorbent material 30 of the present invention in its center. The absorbent core material is wrapped on all sides by a wrapper 31 of a suitable permeable material, such as a standard non-woven fabric. The invention will be further explained in detail by the following examples. In these examples, the absorbent core material has been treated to contain a wetting agent in an amount of less than 0.5% based on its dry weight. The wetting agent used was Triton GR from Rohm and Haas Co.
It is a wetting agent containing sodium dioctyl sulfosuccinate sold under the trade name 5. Example 1 Approximately 28 pounds (12.7Kg) using SWeco classifier
The peat moss raw material is classified. Wet classification removes fine powder, that is, parts less than 100 mesh (150 microns in diameter). In addition, coarse parts, that is, parts larger than 10 pieces (roots, etc.) are also removed. Bleach sections of 10 to 100 mesh by treating them with 21 pounds (9.5 Kg) of calcium carbonate and 18.9 pounds (8.6 Kg) of chlorine. The bleached peat litter is dewatered from a 1% solids dispersion to a 5% solids dispersion. The peat moss is placed in a tank and brought to a 1% consistency with water and 10 pounds (4.54 kg) of 22 Baume hydrochloric acid. The resulting bleached peat moss is as described above.
It has a whiteness of approximately 72 on the Hunter scale. 1% bleached peat moss is kept in the tank.
Approximately 26.25 lbs (11.9 Kg) ground wood pulp and 2% approximately 5.25 lbs (2.4 Kg) bleached kraft wood pulp
Dispersed in water to a certain consistency. This wood pulp mixture and acidified bleached peat moss are mixed together to a solids concentration of 0.7.
% bleached peat moss 21 lbs (9.5Kg), ground wood pulp 26.25 lbs, (11.9Kg) long-threaded wood pulp
The mixture shall contain 5.25 lbs (2.4 Kg). The mixture is beaten with slight agitation and shearing to avoid abrasion of the peat moss leaves, then the mixture is poured onto a fourdrinier screen and a vacuum is applied to dewater and form plates. . The board is forced air-dried at approximately 350°C (177°C) and then rolled. The plate is conventionally ground in a hammer mill to obtain a fluffy absorbent core material. As mentioned above, the resulting improved absorbent core material has improved capillary action compared to chemical or ground wood pulp itself. Additionally, this new material exhibits improved liquid retention, ie, retains absorbed liquid under increased pressure better than either ground wood pulp or chemical wood pulp used alone. Example 2 A number of absorbent core materials are obtained by mixing and grinding various combinations of long-walled chemical wood pulp, ground wood pulp, unbleached peat sludge, and bleached peat sludge. These materials absorb liquid by the method described below.
Measures liquid retention after saturation, liquid retention under pressure. Liquid absorption test method. A 7.7 cm diameter piece of the absorbent core material to be tested is placed on a sintered glass filter and weighed at 2.5 g/cm ³
Press with confining pressure. The lower surface of the sintered glass filter contacts the liquid in the form of a liquid column extending 40 cm below the porous plate. The liquid column is in a graduated billet,
The absorbed volume is measured after 5 minutes and after 1 day (at which time equilibrium has been reached). The liquid column is raised to within 7.5 cm under the porous plate, allowed to reach equilibrium, and the absorbed volume is determined. The liquid column is allowed to rise to within 1 cm below the porous plate to reach equilibrium and the absorbed capacity is measured. Post-saturation liquid retention test The same absorbent core material used in the liquid absorption test is fully saturated, and the liquid column is reduced by 1 level from the level of the core material.
Measure the return capacity down to cm, starting from the core material level.
Return it to 40cm below and measure the capacity. This test determines the amount of liquid retained after saturation. Liquid Retention Test under Pressure A piece of absorbent core material is placed on a perforated mesh plate and thoroughly saturated with liquid. The saturated capacity is measured when no pressure is applied to the upper surface of the core material, when a pressure of 20 g/cm ² is applied, and when a pressure of 105 g/cm ² is applied. As mentioned above, a number of core materials of the compositions shown above in Table 1 below have been measured for various absorption properties and the results are shown below the table.

EXAMPLE 3 A series of fluffy materials are prepared by grinding plates formed from a slurry of a mixture of peat sludge, mechanical pulp (groundwood pulp) and chemical pulp to a fluffy state. The composition of each sample is shown in Table 2. Each sample was tested using RoTap Testing with a 10-mesh Tyler sieve.
Measure its structural integrity by entering the Sieve Shaker pan. The device is manufactured by WFTyler Inc., a subsidiary of Combustion Engineering Inc. in Ohio, USA.
The RoTap Shaker pan, which is 8 inches (20.3 cm) in diameter, fills to a depth of 2 inches (5.08 cm).
The RoTap Sieve Shaker was operated for 25 cycles and the weight of the material passing through the Tyler sieve during the run was determined and is shown in Table 2 as a loss in weight percent relative to the initial 5 g sample. Figure 7 illustrates the data shown in Table 2, showing the weight ratio of pulverized wood pulp to peat moss and the structural integrity as expressed in Table 2, weight percentage loss through the sieve. ing.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the new and improved absorbent material of the present invention. FIG. 2 is a 160x magnification micrograph sketch of the new and improved absorbent material of the present invention. Figure 3 is a sketch of a 160x magnification micrograph of a bleached peat sludge used in the absorbent material of the present invention. FIG. 4 is a partially cut-away perspective view of a disposable diaper using the absorbent material of the present invention. FIG. 5 is a partially cut-away perspective view of a sanitary napkin using the absorbent core material of the present invention. FIG. 6 is a perspective view of a tampon using the absorbent core material of the present invention. FIG. 7 is a graph showing the relationship between the weight ratio of mechanical wood pulp to peat moss and the structural integrity of the resulting machine.

【table】

Claims (1)

[Claims] 1. Peat moss and 0.35 based on the weight of the peat moss.
Absorbent material consisting of a greater proportion of mechanical wood pulp having a Canadian Standard Freeness of about 30 to about 600. 2. The absorbent material according to claim 1, which has a whiteness (color intensity) of at least 70 on the Hunter Color Scale System "C".
Those with 3. Absorbent material according to claim 1, in which the mechanical wood pulp is present in a proportion greater than 0.38 to the weight of the peat slough. 4. The absorbent material according to claim 1, wherein the mechanical wood pulp is a refiner wood pulp. 5. The absorbent material according to claim 1, wherein the mechanical wood pulp is a heated mechanical wood pulp. 6. An absorbent material according to claim 1, which further contains a long fiber absorbent material. 7. The absorbent material according to claim 1, wherein the long fiber absorbent material is chemical wood pulp. 8. The absorbent material according to claim 1, wherein the long fiber absorbent material is rayon. 9. The absorbent material according to claim 1, wherein the peat moss has a particle size distribution of 10 to 100 mesh. 10. An absorbent material according to claim 1, wherein the wood pulp has a Canadian Standard Freeness of about 60 to about 300.
Those with