HK1183225B - Wound-covering material - Google Patents

Description

Wound dressing

The present application is a divisional application of an invention patent application having an application date of 2007, 5/25, application No. 200780022594.4 and an invention name of "wound dressing".

Technical Field

The present invention relates to wound dressings suitable for use in the treatment of wounds such as burns, bedsores, sprains, cuts, abrasions and ulcers.

Background

In recent years, the fact that keeping the wound surface in a moist environment without drying it is effective for healing wounds has been confirmed. In particular, since components contained in exudate from a wound site are useful for promoting wound healing, a method of treating a wound under a moist environment generated by exudate from a wound site without sterilizing the wound (hereinafter may be referred to as "moist healing therapy") has been proved to be effective. Accordingly, various wound dressings have been developed that are suitable for use in such treatment methods.

In order to effectively perform the moist healing therapy, it is important to maintain a moderately moist environment on the wound surface by exudate from the wound site. Therefore, the wound dressing is required to have a function of retaining moderate exudate on the wound surface, rather than rapidly absorbing exudate. However, in order to maintain a moist environment, the wound dressing is firmly secured to the skin, and therefore, the moist healing therapy provides an enclosed area formed on the wound surface. As a result, when additional exudate is exuded to be excessively retained, the wound surface is pressed by the exudate, resulting in a "digging phenomenon" (a phenomenon in which the skin is depressed at the wound site due to the pressure of the exudate). Thus, the wound dressing is also required to have a function of appropriately discharging exudate from the wound surface.

Furthermore, if the material in contact with the wound site is not breathable and adheres tightly to the wound surface, there is a possibility that the wound that has healed or is healing may be damaged again when the wound dressing is removed. Therefore, it is also required that the wound dressing not adhere tightly to the wound surface.

As ｃA conventional wound dressing, for example, JP-A-7-80020 discloses ｃA dressing using ｃA porous film containing ｃA dispersed hydrophilic substance or covered with ｃA hydrophilic substance. However, in this wound dressing, the exudate discharge function is improved only by using the hydrophilic porous film, and the purpose of appropriately retaining exudate on the wound surface is not achieved.

Further, JP- ｃA-10-151184 discloses ｃA wound dressing suitable for use on an ulcer surface, which is formed of cotton, knitted or braided fabric, nonwoven fabric, or the like containing chitin-chitosan cellulose mixed fibers, to which ｃA hydrophilic colloid agent is applied as required. However, in this wound dressing, the function of absorbing exudate is focused, and the function of appropriately retaining exudate on the wound surface is insufficient. Further, it has been pointed out that prolonged direct contact of the skin with the hydrocolloid agent of a wound dressing can lead to skin redness or rash.

In order to solve the problems of the conventional wound dressings, the present inventors have developed a wound dressing having a sheet exhibiting an initial water pressure resistance as an osmotic layer in contact with a wound site, and have made an international patent application for the same (see WO 2005/000372). The wound dressing has significant functionality in a method for treating a wound while maintaining a moist environment created by exudate from the wound site.

Disclosure of Invention

It is an object of the present invention to provide a further improved wound dressing suitable for use in a method of treating a wound while maintaining a moist environment created by exudate from the wound site.

Namely, the present invention relates to:

(1) a wound dressing comprising at least three layers including, in order from a side for contact with a wound site, a first layer, a second layer and a third layer, the layers being laminated together,

the first layer includes a resin sheet having a plurality of holes penetrating therethrough in a thickness direction,

the second layer comprises a sheet material having a surface that is water-repellent and becomes water-permeable when pressurized,

the third layer comprises a sheet capable of absorbing and retaining water;

(2) the wound dressing according to the above (1), further comprising a fourth layer comprising a resin film, a woven fabric or a nonwoven fabric in addition to the first layer, the second layer and the third layer, the layers being integrally laminated;

(3) the wound dressing according to the above (1) or (2), wherein the sheet material of the first layer is a polyolefin resin;

(4) the wound dressing according to any one of the above (1) to (3), wherein,

the thickness of the sheet of the first layer is 100 to 2000 μm,

the equivalent diameter of the opening on the surface contacting with the wound part is 280-1400 μm,

the opening in the other surface is smaller than the opening in the surface for contact with the wound site, and

the density of the holes is 50-400/cm²。

(5) The wound dressing according to any one of the above (1) to (4), wherein,

the sheet material of the second layer is a polyolefin resin,

air permeability of 5 to 2000cm measured according to JIS-L-1096³/cm²S, and

water repellency measured according to JIS-L-1092 is grade 3 or more;

(6) the wound dressing according to any one of the above (1) to (5), wherein the sheet of the third layer is an air-laid nonwoven fabric;

(7) the wound dressing according to any one of the above (2) to (6), wherein,

the areas of the first to third layers are substantially the same,

the area of the fourth layer covering the first to third layers is larger than the areas of the first to third layers,

the fourth layer has an adhesive layer on at least a part of the non-laminated surface on which the first to third layers are laminated, and

at least a part of the vicinity of the outer periphery of the first to third layers does not have the adhesive layer or the fourth layer;

(8) the wound dressing according to any one of the above (2) to (6), wherein,

the areas of the first to third layers are substantially the same,

the area of the fourth layer covering the first to third layers is larger than the areas of the first to third layers,

the fourth layer has an adhesive layer on at least a part of the non-laminated surface on which the first to third layers are laminated, and

the fourth layer has slits or small holes along at least a part of the outer peripheries of the first to third layers; and

(9) a method for producing the wound dressing according to any one of the above (1) to (8), comprising a step of joining the two layers by laminating the sheet of the first layer to the coated surface after incompletely coating the sheet of the second layer with a hot-melt adhesive.

In order to be suitable for use in a method of treating a wound in a moist environment created by exudate from the wound, the wound dressing of the present invention may maintain the moist environment by retaining the exudate so as to prevent its extensive diffusion without rapidly absorbing the exudate at the site where the exudate exudes from the wound. Thus, the treatment effect can be enhanced by holding the exudate in the area near the wound site, and the excessive diffusion of exudate which causes non-traumatic normal skin irritation can be prevented.

Therefore, the wound dressing of the present invention is suitable for the treatment of various wounds, and is most suitable for the prevention and treatment of bedsores in particular.

Drawings

FIG. 1 is an enlarged partial schematic view (in cross-section) illustrating a wound dressing of the present invention;

fig. 2 is an enlarged partial schematic view (cross-sectional view) illustrating a state in which exudate is trapped by a first layer in the wound dressing of the present invention;

fig. 3 is an enlarged partial schematic view (cross-sectional view) illustrating a state in which exudate is trapped by a first layer in the wound dressing of the present invention;

fig. 4 is an enlarged partial schematic view (cross-sectional view) illustrating a state in which exudate is trapped by the first layer in the wound dressing of the present invention;

FIG. 5 is a schematic top view of a wound dressing of the invention;

FIG. 6 is a schematic top view of a wound dressing of the invention;

FIG. 7 is a schematic top view of a wound dressing of the invention;

FIG. 8 is a schematic top view of a wound dressing of the invention;

FIG. 9 is a schematic top view of a wound dressing of the invention;

FIG. 10 is a schematic top view of a wound dressing of the invention;

fig. 11 is a schematic view (perspective view) illustrating a manufacturing process of a wound dressing of the present invention.

Description of the symbols

1 first layer

2 second layer

3 third layer

4 fourth layer

5 wound dressing

6 adhesive layer

7 non-adhesive area

8 slit

11 through hole

12 recess

13 exudate solution

21 second sheet material

22 Hot melt adhesive

23 adhesive discharge nozzle

Detailed Description

The wound dressing of the present invention is a dressing that is affixed to a wound site and may be suitable for use in a method of treating a wound in a moist environment resulting from exudate from the wound site. In the present invention, "wound" broadly refers to skin damage including burns, bedsores, sprains, cuts, abrasions, ulcers, surgical wounds, and the like.

Hereinafter, the structure of the wound dressing of the present invention will be described with reference to the drawings as necessary.

The wound dressing of the present invention is a wound dressing comprising at least three layers including a first layer, a second layer and a third layer in this order from a side for contacting a wound site, wherein the above layers are laminated integrally. The wound dressing of the present invention may be a wound dressing including a fourth layer other than the above-described first, second and third layers as necessary, wherein the above-described four layers are laminated integrally.

Fig. 1 is a schematic cross-sectional view showing a preferred example of the present invention including the fourth layer 4. In use, the first layer 1 is in contact with a wound site.

In the wound dressing of the present invention, the above-mentioned "layers are laminated integrally" means that the laminated state is produced by at least partially joining the layers to adjacent layers, and the layers are kept from separating in normal use unless forced to separate by application of any external force.

As examples of the joining method for lamination, in addition to bonding using an adhesive such as a hot melt adhesive, fusion by heat sealing and embossing are included, but not limited thereto.

Hereinafter, each layer will be specifically described.

(first layer)

The primary purpose of the first layer is to maintain a moist environment by not rapidly absorbing exudate at the site where exudate exudes from a wound, and to prevent its spread over a large area to hold the exudate. In order to heal the wound, it is sufficient to keep the exudate in the area near the wound site, and it is not preferable that the exudate spread beyond this area to the periphery of the wound site. This is due to the fact that in such areas where exudate is spread, the wound site may re-enlarge, slowing healing, due to, for example, inflammation of the intact normal skin. The present invention therefore comprises a first layer designed to prevent the extensive spreading of the area covered by exudate, thereby accelerating the healing of the wound.

The sheet constituting the first layer (hereinafter may be referred to as "first sheet") is a resin sheet.

In the present invention, "sheet" broadly refers to both porous and non-porous sheets, including, for example, resin films, woven fabrics, nonwoven fabrics, nets, etc., and the thickness thereof is not particularly limited.

The first sheet has many holes penetrating in the thickness direction (hereinafter may be simply referred to as "through-holes"). Preferably, the apertures are independent of each other and the first sheet preferably does not have any path inside to allow water to flow in the in-plane direction. Since the first sheet has many through-holes, it is prevented from being firmly stuck to the wound site.

The through-hole may have various shapes such as a cylindrical shape, a barrel shape, a hand-drum shape, etc., and is preferably a tapered through-hole having a diameter decreasing toward the second layer in the thickness direction of the first sheet (hereinafter, such a tapered through-hole having a diameter decreasing toward the second layer may be referred to as a "tapered hole"). Fig. 1 and 2 show an example in which the through-hole is a tapered hole.

The through-hole is formed in a surface of the first sheet to be in contact with a wound site (hereinafter, may be referred to as a "wound-side surface"), and preferably has an equivalent diameter of 280 to 1400 μm. The pore diameter of less than 280 μm tends to prevent passage of the exudate to the second layer, and is therefore not preferred. On the other hand, if the diameter exceeds 1400 μm, the second layer may come into contact with the skin of the wound site, resulting in difficulty in removing the wound dressing from the wound site or difficulty in ensuring a proper holding space for exudate, which is not preferable. The "equivalent diameter" refers to a diameter of the hole when the hole is circular, and refers to a diameter of a circle having an area equal to the area of the hole when the hole is not circular.

When the through-hole is a tapered hole, the diameter of the opening on the wound-side surface is larger than the diameter of the opening on the other surface, that is, preferably 1.1 to 1.8 times, more preferably 1.2 to 1.5 times larger than the opening on the second-layer-side surface, as described above.

When the first sheet has a rough surface, as shown in fig. 1 and 2, a plane in contact with the first sheet on the wound side is assumed, and the diameter of the hole at the position in contact with the plane is defined as the diameter of the opening on the wound-side surface. Likewise, consider a plane in contact with the first sheet on the side of the second layer, and the diameter of the hole at the location of contact with this plane is defined as the diameter of the opening on the side surface of the second layer.

The density of the through holes is preferably 50-400/cm²More preferably 60 to 325/cm². The opening ratio of the first sheet is preferably 15 to 60% relative to the entire wound-side surface.

The depth of the through-hole is preferably about 100 to 2000 μm, and more preferably about 250 to 500 μm.

From the viewpoint of maintaining a suitable amount of exudate on the wound surface by forming a suitable retention space between the wound surface and the second layer and preventing the exudate from spreading in the in-plane direction, it is advantageous to set the density, the open porosity, and the depth of the through-holes within the above-described preferred ranges.

The capacity of the retention space is preferably 0.015 to 0.55 μ L per through-hole, more preferably 0.030 to 0.45 μ L per through-hole, and particularly preferably 0.040 to 0.35 μ L per through-hole. The capacity of the retention space is less than 0.015 μ L per through-hole, and such a retention space tends not only to be difficult to hold exudate on the wound surface but also to prevent exudate from spreading in the in-plane direction, and is therefore not preferable. On the other hand, if the amount of the second layer exceeds 0.55 μ L per through-hole, the absorption rate of exudate by the second layer increases, and it tends to be difficult to maintain a suitably moist environment due to exudate from the wound site, which is not preferable.

The first sheet is preferably a resin film, and particularly, more preferably a porous film produced by perforating a resin film. The resin forming the first sheet is preferably a polyolefin resin, and particularly preferably a polyethylene resin. Therefore, the first sheet is preferably a porous polyolefin resin film, and particularly preferably a porous polyethylene resin film.

The first sheet may have hydrophilicity or hydrophobicity, but its surface preferably has hydrophobicity. When the material is a polyolefin resin, the surface may have hydrophobicity. Having hydrophobicity is advantageous in preventing close adhesion to the wound site.

The first sheet preferably has the property of becoming permeable to water when pressurized. In the present invention, "becoming permeable to water when pressurized" means that water is caused to permeate through a sheet when a water pressure exceeding a predetermined level is applied to the sheet. Hereinafter, the "property that becomes permeable to water when pressurized" may be referred to as "initial water pressure resistance".

The initial water pressure resistance of the first layer may be relatively low, and is preferably lower than that of the second layer described later. "low initial water pressure resistance" means that water is allowed to permeate under a relatively low water pressure.

The initial water pressure resistance of the first sheet can be easily achieved when the surface of the first sheet has water repellency, and the through-holes are tapered holes. Furthermore, the initial water pressure resistance of the first sheet can be set to 50-400 pieces/cm in the density of the through holes²The method is easy to realize, and the aperture ratio is easy to realize when 15-60%. As used herein, "initial water pressure resistance of the first sheet" refers to initial water pressure resistance against pressure from the side in contact with the wound site.

The first sheet having initial water pressure resistance penetrates through the through-holes when pressure is applied. Therefore, it is preferable that the first sheet does not substantially allow water to permeate through any portion other than the penetrating holes.

The fact that the first sheet has initial water pressure resistance can be confirmed, for example, by the following method. That is, when the first sheet is held at a constant height in the air by a metal frame or the like and water is slowly dropped onto the same portion of the sheet by a pipette, initial water does not drip through the sheet if the sheet has initial water resistance, but water drips through the sheet as the amount of water dropped increases.

The first sheet serves to prevent the exudate oozing from the wound from spreading in the in-plane direction. As shown in fig. 2, in the initial stage of exudation of exudate from the wound, that is, immediately after the wound dressing of the present invention is applied to the wound surface, exudate permeates into the middle of the through-hole. Therefore, the exudate is captured in the through-holes and prevented from moving in the in-plane direction, and is not diffused to exceed the wound site area and held between the wound surface and the first layer, thereby maintaining a moist environment. In order to effectively maintain a wet environment by preventing the diffusion of the exudate over a large area, it is advantageous that the first sheet has an initial water pressure resistance, that the through-holes are tapered, and that the capacity of the retention space is 0.015 to 0.55 μ L per through-hole.

In the next stage, the exudate further oozes out and its pressure increases, penetrating through the first layer to the surface of the second layer, and then further penetrating toward the third layer. Preferably, the exudate is not allowed to return through the first layer. In particular, the exudate that has permeated through the second layer may propagate various germs after a long time has elapsed since the exudate has exuded, and for example, if the wound dressing is pressurized by an external force and the exudate returns to the wound site, infection may be caused. In preventing such a return of the percolate, it is advantageous for the through-going hole to be a conical hole.

The first and second layers are preferably in intimate contact with each other. In particular, as shown in fig. 3, they are preferably in close contact to such an extent that the exudate cannot spread in the in-plane direction on the interface between the first layer and the second layer even if the above-mentioned retention space is filled with the exudate. Such intimate contact may be achieved by incompletely applying a hot melt adhesive to the surface of the second layer and joining the two layers as described below.

Regardless of the quality of the above-described close contact, when the first sheet having the tapered holes and the rough surface as shown in fig. 1 and 2 is used, as shown in fig. 4, since the exudate reaching the surface of the second layer can be trapped at the concave portions, it is more advantageous to prevent the exudate from spreading in the in-plane direction.

(second layer)

The second layer has initial water pressure resistance which is a property that water becomes permeable when pressurized. Since the second layer has initial water pressure resistance, the wound dressing of the present invention, when in actual use, has a function of withstanding pressure against the pressure generated by exudate from a wound to prevent the exudate from permeating at the initial stage of exudate exudation, and allowing the exudate to permeate when the pressure generated by the exudate exceeds a predetermined level.

The sheet constituting the second layer (hereinafter may be referred to as "second sheet") is a sheet having initial water pressure resistance. Since the initial water pressure resistance can be easily achieved when the surface has water repellency, it is preferable that the second layer is composed of a sheet having a water repellent surface and an initial water pressure resistance.

In the present invention, as the index of the initial water pressure resistance, air permeability (according to JIS-L-1096) and water repellency (according to JIS-L-1092) can be used. The second sheet preferably has a thickness of 5 to 2000 (cm)³/cm²S) permeability and water repellency grade 3 or more. When the air permeability and the water repellency are within the above ranges, the initial water pressure resistance suitable for the purpose of the present invention can be achieved, and therefore, a moderately moist environment which enhances the healing effect can be achieved by preventing the infiltration and absorption of exudate at the initial stage where the exudate is small, and by infiltrating and absorbing the excess exudate at the stage where the exudate is excessively exuded. The air permeability is more preferably 15 to 500 (cm)³/cm²S), in which case it is estimated that an appropriate humid environment can be maintained for a long time.

The above air permeability is not preferably less than 5 (cm)³/cm²S) is because in this case, the water pressure resistance of the second sheet is too high, and even if the pressure is increased by the increase in the amount of exudate in the closed region on the wound surface, the exudate cannot penetrate into the third layer, and therefore, there is a possibility that the exudate returns to the wound surface side or spreads in the in-plane direction. On the other hand, it is not preferable that the air permeability exceeds 2000 (cm)³/cm²S) is because, in this case, the water pressure resistance of the second sheet is so low that the exudate is rapidly absorbed, and therefore, there is a possibility that a moderate humid environment cannot be maintained.

Further, it is not preferable that the water repellency is lower than grade 3 (grade 2 or less), because in this case, the water pressure resistance is too low to allow the exudate to be rapidly absorbed, and therefore, there is a possibility that a moderately humid environment cannot be maintained.

The air permeability was measured according to method A (Ferraet method) described in 8.27.1 of JIS L-1096. In this measurement method, a textile fisher type air permeability tester was used. In particular, it is transparentGas properties were determined as follows: the test piece was mounted on a Frazier-type tester, the induced draft fan was adjusted by a rheostat so that the differential barometer would read 125Pa, and from this, the pressure indicated by the vertical barometer and the type of hole used were measured, and the amount of air (cm) passing through the test piece was calculated using a table attached to the tester³/cm²S). The air permeability was obtained by calculating the arithmetic mean of five measurements.

The water repellency was measured according to the water repellency test (spray test) described in 6.2 of JIS-L-1092. In this measurement method, a water repellency test apparatus including a nozzle having a predetermined capability (capability of spraying 250mL of water for 25 to 30 seconds) is used. Specifically, the water repellency was measured as follows: (1) a test piece (about 20cm × 20 cm) was attached to a test piece holding frame of the water repellency testing apparatus, 250mL of water was sprayed onto the test piece from a nozzle within 25 to 30 seconds, (2) the holding frame was removed from the stage of the water repellency testing apparatus, a predetermined operation was performed to drop excessive water droplets from the test piece, and (3) the wet state of the test piece attached to the holding frame was compared with a comparison sample in a predetermined wet state to rate the test piece. The predetermined operation in the above (2) means that the same operation is performed by holding one side of the holding frame in a horizontal position, making the surface of the test piece face down, making the other side collide with some hard object, and then rotating the test piece by 180 degrees.

In the water repellency test, the temperature was set to 20. + -. 2 ℃ and distilled water was used as the water for measurement.

The comparative samples in the wet state are as follows.

Level 1: wetting the entire surface

And 2, stage: semi-wet and small individual water drops on the surface penetrate the fabric

And 3, level: the surface is wetted by small individual water droplets on the surface

4, level: the surface is not wet, but there are small water drops on the surface

And 5, stage: no wetting and no water drop on the surface

Therefore, in the above-mentioned water repellency test, "the water repellency is of grade 3 or more" includes "the surface is wetted with small individual water droplets on the surface", "the surface is not wetted but there are small water droplets on the surface" and "the surface is not wetted and there are no water droplets", and does not include "the entire surface is wetted" and "half of the surface is wetted and small individual water droplets penetrate the fabric".

The test method of the water repellency test according to JIS-L-1092 is similar to ISO 4920.

The second sheet may be a nonwoven fabric or a porous film or fabric formed of a hydrophobic material such as a polyolefin resin (e.g., polypropylene, polyethylene, etc.), a polyester resin (e.g., polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, etc.), a polyamide resin (e.g., nylon 6, nylon 66, etc.), or a polyurethane resin. The second sheet is preferably a nonwoven fabric, more preferably a nonwoven fabric containing polyolefin fibers, and particularly preferably a nonwoven fabric containing polypropylene fibers.

The type of nonwoven fabric is not particularly limited, and various wet-process or dry-process nonwoven fabrics can be used, for example, a thermal bond nonwoven fabric, a needle-punched nonwoven fabric, a spunlace nonwoven fabric, a spunbond nonwoven fabric, a meltblown nonwoven fabric, a flash-spun nonwoven fabric, or a composite of these nonwoven fabrics (SMS, SMMS, etc.).

Furthermore, a nonwoven fabric subjected to water repellent treatment and formed of hydrophilic fibers such as cotton and rayon may be used.

As the nonwoven fabric used for the second sheet, a meltblown nonwoven fabric and a flash-spun nonwoven fabric obtained by meltblowing and flash spinning, respectively, are particularly preferable.

The meltblown nonwoven fabric and the flash-spun nonwoven fabric are formed of, for example, ultrafine fibers having a fiber diameter of about 20 μm or less. Therefore, when the basis weights (basis weight) of both the meltblown nonwoven fabric and the flash-spun nonwoven fabric are equal to each other as compared with those of the nonwoven fabric obtained by other production methods such as the spunbond method, the voids between the fibers can be made smaller, and therefore a fabric having a desired initial water pressure resistance can be easily obtained.

Briefly, a meltblown nonwoven fabric is a fabric formed of continuous ultrafine fibers, and is obtained by drawing and fibrillating the fibers while blowing high-temperature and high-pressure gas toward the outlet of a spinning nozzle. The meltblown nonwoven fabric may be used as a so-called SMS nonwoven fabric, SMMS nonwoven fabric, or the like, and is formed by laminating a spunbond and meltblown nonwoven fabric in a layer.

The flash spun nonwoven fabric is a mesh nonwoven fabric formed of continuous ultrafine fibers, and is obtained by uniformly dissolving a fiber-forming polymer in a low-boiling solvent at high temperature and high pressure, then rapidly vaporizing and expanding only the solvent while discharging the solution from a nozzle, and stretching and solidifying the fiber-forming polymer.

The nonwoven fabric as the second sheet may be subjected to a calendering process. The calendering as used herein means that the nonwoven fabric is subjected to a pressure treatment using a calender roll or an emboss roll adjusted to a temperature of not higher than the melting point. This calendering process thermally melts a part of the fibers forming the nonwoven fabric and breaks the voids between the fibers, so that the nonwoven fabric can easily obtain desired initial water pressure resistance.

(third layer)

The third layer is a layer for absorbing exudate which has exuded from the wound site, has permeated through the first layer, and then has permeated through the second layer. Thus, the third layer is composed of a sheet capable of absorbing and retaining water. This is because the sheet material capable of absorbing and holding water is capable of absorbing and holding exudate.

By "capable of absorbing and retaining water" is meant that, when in contact with liquid water, the sheet naturally absorbs the water and retains at least a portion of the water within its interstices against gravity. Therefore, when the sheet holding the absorbed water is lifted, if a part of the absorbed water is held without falling down, it can be said that the sheet can absorb and hold the water. Preferably the sheet material can absorb water by capillary action.

The sheet capable of absorbing and retaining water used as the sheet constituting the third layer (hereinafter may be referred to as "third sheet") may be a sponge-like sheet, and is preferably a sheet formed of hydrophilic fibers such as cotton or hydrophilized fibers. The third sheet is preferably a hydrophilized nonwoven fabric, fluff pulp, air-laid nonwoven fabric, or the like.

When the third sheet is formed of fibers, it is preferable to bond the fibers by an adhesive (binder) or an interfiber adhesion force generated by compression to such an extent that neither lint nor other auxiliary materials are released from the incision at the time of cutting the wound dressing. Therefore, it is also preferable to use heat-bondable fibers at least in part.

The third sheet is particularly preferably an air-laid nonwoven fabric. The air-laid nonwoven fabric is obtained by uniformly cutting and dispersing raw pulp fibers or short fibers in the air, depositing them on a rotating porous cylinder or a movable belt screen, and spraying a water-soluble binder thereon for bonding the fibers to each other. In particular, a nonwoven fabric containing pulp fibers as a main component is preferably used in order to easily absorb the exudate. As a method for producing these nonwoven fabrics, the DAN-WEB method, the Honshumethod (Honshumethod), and the like can be used.

The air-laid nonwoven fabric preferably contains synthetic fibers having a small decrease in strength under wet conditions, and specific synthetic fibers are, for example, polyamides including nylon 6 and nylon 66, polyesters including polyethylene terephthalate, polyethylene and polypropylene.

The air-laid nonwoven fabric may contain binder fibers. The binder fiber is a fiber that exhibits a binding property by changing its state through melting and solidification of all or a part thereof according to a temperature condition. Specific examples of the binder fiber include: fully fusible fibers containing a low melting point resin such as a polyester resin and a polyamide resin alone or a polyolefin resin; core-sheath composite fibers and side-by-side composite fibers containing two types of resins having different melting points, such as polyethylene resin/polypropylene resin or low-melting polyester resin/polypropylene resin.

The third sheet may contain an absorbent material such as superabsorbent resin powder to enhance the ability to absorb and retain exudates. Since the components of the air-laid nonwoven fabric such as fibers are bonded to each other by pressure with the binder, the highly absorbent resin powder, fluff pulp, and the like are less likely to fall off even if the wound dressing is cut before use. The absorbent material is a material that absorbs liquid and swells to form a gel in a short time when it comes into contact with the liquid. As the absorbent material, a so-called Super Absorbent Polymer (SAP) of polyacrylic acids, starches, carboxymethyl celluloses, polyvinyl alcohols, or polyethyleneoxides; for example, highly absorptive natural polysaccharides such as alginic acid and dextran. The absorbent material may be not only in the form of powder and granules, but also in the form of fibers. Furthermore, by treating the absorbent material with a calcium salt, a hemostatic effect of the wound surface can be provided.

The fibers forming the third sheet may be superabsorbent fibers having a water absorption capacity equal to that of the superabsorbent polymer (SAP), and the third sheet may be substantially formed of only superabsorbent fibers. With the third sheet formed substantially only of the super absorbent fibers, fibers can be prevented from falling off even if the wound dressing is cut before use, as compared with the case of using a powdery super absorbent resin. In the case of using a powdered resin, since the powdered resin absorbs exudate and swells at the time of use, the third sheet becomes uneven, and thus the layers of the wound dressing may be easily separated. However, the third sheet formed substantially only of the super absorbent fibers is less likely to become uneven, and therefore separation of the layers can be prevented. Specific examples of the high water-absorbent fibers include, for example, "ランシール (registered trademark) F" manufactured by toyobo textile co.

When the air-laid nonwoven fabric as the third layer absorbs the exudate, hydrogen bonds between pulp fibers in the air-laid nonwoven fabric are broken and the water-soluble binder is dissolved, resulting in a decrease in inter-fiber bonding under wet conditions. In particular, when the air-laid nonwoven fabric contains a high water-absorbent resin, the strength of the resin is reduced by gelation, and the gelation increases the volume of the resin, with the result that entanglement and bonding between fibers are physically broken. Therefore, the wet strength of the air-laid nonwoven fabric may be significantly reduced. However, the air-laid nonwoven fabric can contain water-insoluble long fibers and binder fibers to keep the inter-fiber bonding at a minimum, whereby the reduction in wet strength of the air-laid nonwoven fabric can be controlled. Thus, the detachment or disintegration of the third layer of the wound dressing, which often occurs after absorption of exudate and which is caused by a decrease in the strength of the airlaid nonwoven fabric, can be controlled, whereby the wound dressing can be easily and aesthetically removed from the wound surface.

The air-laid nonwoven as the third layer may be softened by perforation. As used herein, "perforation" refers to the process of forming a plurality of holes in a nonwoven fabric. Since the fibers in the air-laid nonwoven fabric are bonded to each other by the binder, the rigidity of the fabric is high, and thus the flexibility thereof may be impaired. However, since the perforations described above may soften the air-laid nonwoven, the wound dressing may be flexible to conform to the skin. Moreover, the perforations also allow the nonwoven to absorb exudates through the perforations, so that the absorption rate gradually increases once the nonwoven starts to absorb exudates.

The cross-sectional shape of the hole produced by perforation is not particularly limited. The apertures may or may not extend completely through the airlaid nonwoven.

The third sheet may be a composite sheet. The composite sheet can be obtained by impregnating a nonwoven fabric with an acrylic monomer, and then performing polymerization and crosslinking reaction. Another example of the composite sheet can be obtained by a casting method in which a dispersion liquid containing a fibrous material having high hydration reactivity (for example, microfibers and the like) and a water-swellable solid substance (for example, various polysaccharides, flocculants, super absorbent Substances (SAP) and the like) dispersed in a mixed solvent of an organic catalyst and water is poured into a support sheet such as a nonwoven fabric, and then the dispersion liquid is dried.

For the third sheet, the stretchability may be provided by making cuts in an irregular manner, such as holes created by perforations or the like.

The thickness of the third sheet is not particularly limited, but is preferably about 0.4 to 0.8mm in view of the capacity to absorb exudates. The third sheet preferably has a weight per unit area of 60 to 170g/m²。

(fourth layer)

The wound dressing of the present invention includes first to third layers and, if desired, further includes a fourth layer 4 such as shown in fig. 1. The fourth layer is provided to prevent the exudate absorbed by the third layer from being transferred to the outside. The wound dressing of the present invention does not necessarily have to have a fourth layer. However, when the fourth layer is not provided, it is preferable to use another sheet together with the third layer in order to prevent the exudate absorbed by the third layer from transferring to the outside and staining, for example, clothes or bedding.

The fourth layer is preferably a resin film, a woven fabric, a nonwoven fabric, or a combination thereof. Among them, a resin film is particularly preferable as the fourth layer.

As the resin film, a resin film that prevents liquid permeation is preferable. Examples of the resin film include resin films formed of olefin-based resins (polyethylene, polypropylene, etc.), polyester-based resins, nylon-based resins, and the like. It is also preferable to use a stretchable resin film made of a polyurethane resin or the like. The use of a stretchable resin film improves the adaptability of the wound dressing to the skin. The thickness of the resin film is not particularly limited, and may be appropriately set in consideration of strength, flexibility, and the like.

The use of the liquid permeation preventing resin film as the fourth layer is effective not only for preventing the transudation of exudate to the outside of the wound dressing, but also for preventing the entry of water and dirt from the outside. The use of the resin film as the fourth layer also prevents evaporation of the exudate and more effectively maintains the moist environment.

As described below, a slit or the like may be provided to a part of the resin film that prevents liquid penetration, as necessary. In this case, the slit may provide a passage for the liquid. However, even in this case, the liquid penetration can be prevented at any portion other than the slit. Therefore, even in this embodiment, the film is still a "liquid permeation preventing resin film" unless otherwise specified.

The outer surface of the fourth layer may be colored or patterned as desired. For example, the surface is rendered unnoticeable by coloring it like a skin color. Conversely, for fashion and to satisfy the core, conspicuous patterns, illustrations, photographic prints, and the like may be intentionally provided.

The fourth layer may be transparent. In this case, the state of the exudate in the inner layer is visible, and therefore, it is easy to know the appropriate time to change the dressing.

The wound dressing of the invention is in the form of a laminated sheet which may be supplied, for example, in the form of a long roll of sheet material which may be cut to the required length prior to use. In this case, if the wound dressing has the fourth layer, the areas of the first to fourth layers laminated are the same, and therefore, a medical tape or the like can be used to fix the wound dressing to the wound surface.

The wound dressing of the present invention may be cut to the appropriate size prior to delivery. In the wound dressing of this aspect, the first to third layers preferably have substantially the same area, and the fourth layer covering the first to third layers preferably has a larger area than the first to third layers. More specifically, as shown in fig. 5, for example, it is preferable that the first to third layers are laminated in the same shape, and the fourth layer is diffused over all or a part of the outer peripheries of the first to third layers. Fig. 5 is a schematic plan view seen from the first layer side. In this example, the second and third layers are hidden behind the first layer, and the fourth layer protrudes over part or all of the periphery.

In the preferred embodiment in which the area of the fourth layer is large, the fourth layer preferably has an adhesive layer on at least a part of an unlaminated surface (hereinafter may be referred to as an "exposed surface") of a side on which the first to third layers are laminated (hereinafter may be referred to as an "inner side", and the other side may be referred to as an "outer side"). The adhesive layer is provided to secure the wound dressing to the skin. Thus, the adhesive layer is preferably one that can secure the wound dressing and be easily removed. Specifically, an adhesive layer containing a hypoallergenic adhesive such as an acrylic adhesive or a silicone adhesive which does not cause skin irritation when it comes into contact with the skin is preferable, and an adhesive layer used in a known adhesive plaster (for example, "バンドエイド" (registered trademark)) or the like can be used.

With respect to the above-described embodiment in which the fourth layer has an adhesive layer on at least a part of the inner exposed surface, an embodiment in which the adhesive layer is not provided on at least a part of the vicinity of the outer peripheries of the first to third layers as shown in fig. 6 and 7, and an embodiment in which the fourth layer is not provided on at least a part of the vicinity of the outer peripheries of the first to third layers as shown in fig. 8 and 9 are further preferable. The exposed surface of the fourth layer in fig. 8 and 9 may have an adhesive layer. In these preferred embodiments, the portion not having the adhesive layer or the portion not having the fourth layer is not adhered to the skin, and forms an open area. As a result, the open area supplies air to the periphery of the wound site, which effectively inhibits the proliferation of anaerobic bacteria, thereby preventing infection.

In the embodiment having no adhesive layer on at least a part of the vicinity of the outer peripheries of the first to third layers as shown in fig. 6 and 7, the embodiment having a portion having no adhesive layer (hereinafter may be referred to as "non-adhesive region") extending to the outer periphery of the fourth layer as shown in fig. 6 is preferable when the sheet of the fourth layer is a sheet lacking air permeability (for example, a non-porous resin film) and has an adhesive layer. The purpose of this is to ensure air permeability through the outer peripheral portion. On the other hand, as shown in fig. 7, the embodiment in which the non-adhesive region does not extend to the outer periphery of the fourth layer and the entire outer periphery has the adhesive layer is preferable when the sheet of the fourth layer is an air-permeable sheet (e.g., nonwoven fabric) and has the adhesive layer. This is because the air permeability of the air-permeable sheet including a nonwoven fabric or the like is maintained in the non-adhesive region although the air permeability is inhibited by the adhesive layer.

As another embodiment of forming the open region having the above-described effects, for example, as shown in fig. 10, the fourth layer may have slits or small holes along at least a part of the outer peripheries of the first to third layers. In fig. 10, the exposed surface of the fourth layer may have an adhesive layer. The size and number of the slits or holes may be appropriately determined in consideration of the advantages of the supplied air and the disadvantages of the transudation of the exudate to the outside.

Providing another sheet that covers and hides the slits or holes without blocking them is effective for preventing exudates from soiling clothing and bedding.

(production method)

The method for producing the wound dressing of the present invention is not particularly limited as long as the first to third layers or the first to fourth layers can be integrally laminated and do not hinder the object of the present invention, and a known method can be appropriately employed. The layers may be laminated together at the same time, or after lamination of some layers, the other layers may be laminated together.

In order to join the first layer and the second layer when manufacturing the wound dressing of the present invention, it is preferable to laminate the first layer sheet to the surface of the second layer sheet after incompletely coating the surface with the hot melt adhesive to join the two layers. In this preferred procedure, the hot melt adhesive is not completely applied to the surface because application to the entire surface may impede migration of exudate at the interface of the first layer and the second layer.

The above-mentioned "incompletely coating" means that coating is performed so as to produce a coated portion and an uncoated portion. The coating pattern is not particularly limited, and various incomplete coating patterns can be used. A coating pattern in which coated portions and uncoated portions alternately appear, for example, a dot pattern, a stripe pattern, a lattice pattern, or the like, is preferable. A particularly preferred coating pattern is a spiral coating pattern as shown in fig. 11, for example. Since this pattern can be easily achieved by discharging the hot melt adhesive from the upper nozzle to form a spiral pattern while supplying the second sheet, excellent productivity and a good joined state can be provided.

The wound dressing of the present invention manufactured as described above can maintain the moist environment by preventing the exudate from spreading over a large area by retaining the exudate at the site where the exudate exudes from the wound without rapidly absorbing the exudate. Thus, by retaining exudate in the area around the wound site, the therapeutic effect can be enhanced, and the excessive spread of exudate which causes irritation of the non-wounded normal skin can be prevented.

Claims (5)

1. A wound dressing comprising, in order from a side for contact with a wound site, at least a first layer, a second layer, a third layer and a fourth layer, the layers being laminated together,

the first layer includes a resin and hydrophilic sheet having a plurality of holes penetrating in a thickness direction and substantially not allowing water to permeate at any portion except the penetrating holes,

the second layer comprises a sheet material having a surface that is water-repellent and becomes water-permeable when pressurized,

the third layer comprises a sheet material capable of absorbing and retaining water,

the fourth layer comprises a resin film, a woven fabric or a nonwoven fabric,

the areas of the first to third layers are substantially the same, the area of the fourth layer covering the first to third layers is larger than the areas of the first to third layers, the fourth layer has an adhesive layer on at least a part of the non-laminated surface on the side where the first to third layers are laminated, and the adhesive layer or the fourth layer is not present on at least a part of the vicinity of the outer periphery of the first to third layers,

the sheet of the first layer has a thickness of 100 to 2000 [ mu ] m, the equivalent diameter of the open pores on the surface of the through-hole for contact with the wound site is 280 to 1400 [ mu ] m, the open pores on the other surface are smaller than the open pores on the surface for contact with the wound site, and the density is 50 to 400/cm²The through hole has an aperture ratio of 15 to 60%, and the through hole is a tapered through hole having a diameter that decreases toward the second layer.

2. A wound dressing comprising, in order from a side for contact with a wound site, at least a first layer, a second layer, a third layer and a fourth layer, the layers being laminated together,

the first layer includes a resin and hydrophilic sheet having a plurality of holes penetrating in a thickness direction and substantially not allowing water to permeate at any portion except the penetrating holes,

the second layer comprises a sheet material having a surface that is water-repellent and becomes water-permeable when pressurized,

the third layer comprises a sheet material capable of absorbing and retaining water,

the fourth layer comprises a resin film, a woven fabric or a nonwoven fabric,

the first to third layers have substantially the same area, the fourth layer covering the first to third layers has an area larger than the areas of the first to third layers, the fourth layer has an adhesive layer on at least a part of the non-laminated surface on the side where the first to third layers are laminated, and the fourth layer has a slit or a pinhole along at least a part of the outer periphery of the first to third layers,

the sheet of the first layer has a thickness of 100 to 2000 [ mu ] m, the equivalent diameter of the open pores on the surface of the through-hole for contact with the wound site is 280 to 1400 [ mu ] m, the open pores on the other surface are smaller than the open pores on the surface for contact with the wound site, and the density is 50 to 400/cm²The through hole has an aperture ratio of 15 to 60%, and the through hole is a tapered through hole having a diameter that decreases toward the second layer.

3. The wound dressing of claim 1 or 2,

the sheet material of the second layer is a polyolefin resin,

air permeability of 5 to 2000cm measured according to JIS-L-1096³/cm²S, and

the water repellency measured according to JIS-L-1092 was 3 or more.

4. The wound dressing of claim 1 or 2, wherein the sheet of the third layer is an air-laid nonwoven.

5. The wound dressing of claim 3, wherein the sheet of the third layer is an airlaid nonwoven.