Unicharm issued US patent for manufacturing absorbent article such as pants-type disposable diaper

ALEXANDRIA, Virginia , April 9, 2014 () – From Alexandria, Virginia, VerticalNews journalists report that a patent by the inventor Yamamoto, Hiroki (Kanonji, JP), filed on March 2, 2010, was published online on April 1, 2014.

The patent's assignee for patent number 8685197 is Unicharm Corporation (Ehime, JP).

News editors obtained the following quote from the background information supplied by the inventors: "An absorbent article, such as a pants-type disposable diaper, generally includes a front waistline region to be fitted to the front waistline of a wearer, a back waistline region to be fitted to the back waistline of the wearer, a crotch region to be fitted to the crotch of the wearer, and leg-surrounding regions (for example, leg holes) respectively at sides of the crotch region.

"Such an absorbent article is formed mainly of: a liquid-permeable top sheet configured to come into contact with the skin of a wearer; a back sheet provided outside the top sheet; and an absorber provided between the top sheet and the back sheet and configured to absorb excretion of the wearer.

"The top sheet, the back sheet, and the absorber are bonded together with adhesive. When an elastic member is disposed in the waistline regions or the leg-surrounding regions in order to enhance the fitness, the elastic member is also bonded by adhesive (refer to PTL 1).

"PTL 1 describes a technique in which adhesive for bonding a top surface sheet, a bottom surface sheet, and an absorber is arranged in a spiral form continuous in a conveyance direction of a web during the manufacture.

"According to the technique described in PTL 1, after adhesive is applied on side edge portions of a first web, an elastic member is disposed on the adhesive. Thereafter, a second web is overlaid onto the first web with the elastic member in between.

"The inventors have discovered that, in the known technique, air may be trapped between any two of the first web, the adhesive, and the second web. In other words, an air pocket maybe formed. If the air permeability of the webs is high, the air in the air pocket is allowed to escape to the outside through the webs.

"The inventors have discovered that if the air permeability of the webs is low, it is difficult for the air in the air pocket to escape to the outside of the webs.

"Accordingly, when the webs are pressed by a roller in a subsequent step, the internal pressure of the air pocket increases. For this reason, it is conceivable that the risk of generation of creases in the webs and/or breakage of the webs is increased. It is desirable to avoid or to at least minimize such manufacturing defects that may lead to a decrease in the yield."

As a supplement to the background information on this patent, VerticalNews correspondents also obtained the inventor's summary information for this patent: "Therefore, the present invention has been made in consideration of the above problems. It is an object of the present invention to provide a method of manufacturing an absorbent article that is capable of preventing a decrease in the yield in manufacture when absorbent articles are manufactured by laminating webs each having a low air permeability.

"A first aspect of the present invention is summarized as a method of manufacturing an absorbent article, said method comprising: applying adhesive on a first continuous web being continuously conveyed along a conveyance direction; overlaying a second web on the first continuous web; and pressing the first and the second webs against each other in at least a pressing region extending in a direction crossing the conveyance direction, in a plan view of the first continuous web and the second web, wherein the first continuous web and the second web comprises a liquid-impermeable sheet that is impermeable to liquid; and

"the adhesive is applied in such a curved trajectory that an angle formed between (i) a tangent line drawn at any point on the trajectory of the adhesive, and (ii) an axis orthogonal to a trailing side of the pressing region in the conveyance direction falls within a range of .+-.90.degree. in the plan view.

"According to the characteristics of the present invention, it is possible to provide a method of manufacturing an absorbent article that is capable of preventing a decrease in the yield in manufacture when absorbent articles are manufactured by laminating webs each having a low air permeability."

For additional information on this patent, see: Yamamoto, Hiroki. Method of Manufacturing Absorbent Article. U.S. Patent Number 8685197, filed March 2, 2010, and published online on April 1, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=90&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=4497&f=G&l=50&co1=AND&d=PTXT&s1=20140401.PD.&OS=ISD/20140401&RS=ISD/20140401

Keywords for this news article include: Unicharm Corporation.

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