JP2012029998A - Cushion to keep sitting posture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cushion capable of keeping a posture when sitting in a chair etc., to be specific, a cushion which not only has bedsore prevention performance and a sitting-posture keeping performance but also is very safety because the user is less likely to fall forward even when the user bends down forward during sitting in a wheelchair.SOLUTION: The cushion to keep a sitting posture is composed of: an anchor material which consists of plastic foam; and cushioning material which is integrally located on the anchor material and has stress relaxation property. In order that the posture during sitting becomes a retroverted posture, the anchor material is thinner at the position under the thighs than at the position under the ischial bone. In particular, it is desirable that an opening provided in the portion of the anchor material, the portion located under the ischial bone, eliminates stress reaction from the sheet surface of the wheelchair to the coccygeal bone and the ischial bone (so called a feeling of contacting with a bottom) when the user sits. It is also desirable to form one or two concave grooves in the anchor material, at the position under the thighs.

Description

  The present invention relates to a cushion capable of maintaining a posture when seated on a chair or the like.

  With the recent aging society, walking has become difficult and the number of people who need wheelchairs is increasing. If the wheelchair must be used in this way, it will be forced to sit on the wheelchair for a long time, and in some cases, pressure ulcers will develop in the buttocks (sciatic region). A pressure ulcer is the result of prolonged pressure on the same part of the body, resulting in impaired blood circulation in the skin tissue and necrosis of the skin and tissue. For this reason, cushions such as cushions used for wheelchairs are required not only to have simple cushioning performance but also to be made of a material that does not easily cause pressure ulcers from the viewpoint of QOL.

  As mentioned above, the external factor for pressure ulcers is mainly the body pressure (stressing stress) applied when sitting, but it is also compounding the shear stress in the lateral direction while sitting. It is said that the elucidation of such complicated factors is important. In addition, when a person with a disability in the lower body uses a wheelchair, if the sitting posture cannot be maintained, there is a possibility of falling forward from the wheelchair when the body is tilted forward while sitting. For wheelchair users, simply preventing pressure ulcers is not enough.

  Under such circumstances, as cushions used for wheelchairs, air cushions, cushions made of urethane foam, cushions made of gel-like materials, etc. are commercially available in addition to natural materials such as cotton. The air cushion has a high load dispersion performance (hereinafter sometimes referred to as “stress relaxation”), but has a problem that the body posture retention performance at the time of sitting is low. In addition, cushions made of urethane foam have a certain level of stress relaxation, but they have a low ability to absorb shearing force, which is attracting attention as one of the causes of pressure ulcers. Low power absorption performance. On the other hand, in recent years, from a low-resilience urethane foam having a gel structure, which is a kind of soft polyurethane foam, as a cushion having stress relaxation properties and dispersing performance of displacement force generated from lateral force A cushion has been developed. Gels generally have both liquid and solid physical properties, so they are easily deformed and are said to have a high ability to absorb shear forces generated by stresses in all directions including the lateral direction.

  However, the cushion made of the low-resilience urethane foam has a uniform cushion hardness, so that it is difficult to maintain a posture during sitting and is likely to be unstable. In particular, a person who is paralyzed with some of the functions of the body, such as inferiority of the lower body, easily loses the sitting posture and places a burden on the body. Therefore, in order to use the cushion for a long time, it is required that the seating posture is not easily broken and comfortable while maintaining the load dispersibility and the shift force dispersibility described above.

  On the other hand, as a wheelchair cushion, a wheelchair cushion excellent in the effect of stabilizing the pelvis has also been proposed (see Patent Document 1). In order to maintain the seated state, this cushion is formed of a flexible foam so that the seat surface with which the pelvis contacts is formed from a viscoelastic gel and the rear part is held by a support member.

  However, if it is made entirely of a flexible foam that is used for mattresses, cushions, etc., it does not have sufficient hardness, so there is an effect of stabilizing the pelvis when sitting, It seems that there is still a problem to be solved in terms of the function of preventing the vehicle from falling forward from the wheelchair.

  In addition, a cushion for a chair that can hold a seating posture and prevent pressure ulcers by forming a frame with a support member made of a material having high resilience and inserting a low resilience cushioning material therein is proposed. (See Patent Document 2). This cushion is intended to prevent the sitting posture from being deformed by the deformation of the cushioning material by the support member, and is intended to prevent pressure ulcer by the low resilience foam and to maintain the sitting posture by the support member. As in the cushion disclosed in Patent Document 1, no examination has been made from the functional aspect of preventing the wheelchair user from falling over when the user leans forward.

JP 2006-136552 A JP 2006-000200 A

  Therefore, in the present invention, not only the pressure ulcer prevention performance and the sitting posture holding performance, but also a cushion with extremely high safety, it is difficult to fall forward even if it is tilted forward when it is used sitting on a wheelchair. The purpose is to provide.

  As a result of intensive studies to achieve the above object, the present inventors have found that it is not sufficient to simply examine the cushioning material and the cushion material, so that the sitting posture is maintained and the vehicle falls forward. In order to prevent this, it was found that a more safe cushion can be provided by combining an anchor material made of plastic foam with a cushioning material and making the shape of this anchor material a specific shape, and the present invention was completed. It came to do.

  That is, the present invention is a cushion for holding a seating posture comprising an anchor material made of a plastic foam and a buffer material having stress relaxation properties integrated and positioned on the anchor material. A cushion for holding a seating posture, characterized in that the thickness of the anchor material located below the sciatic bone is thinner than the thickness of the anchor material located below the thigh so as to be in a posture.

  In particular, by providing an opening in the anchor material located below the sciatic bone, the tailbone and sciatic can eliminate the repulsive stress from the wheelchair seating surface (so-called feeling of bottoming) when seated. Preferably, in order to further stabilize the sitting posture, it is preferable to form one or two concave grooves so that the thigh can be held in the anchor material located under the thigh. is there.

  The cushion for holding the seating posture of the present invention is not a cushion that merely uses a cushioning material as described above, but has a structure in which an anchor material of a specific shape made of a plastic foam is integrated. Can prevent pressure ulcers from being used, can maintain a sitting posture, and can provide an extremely safe cushion even if it is tilted forward during seating and does not fall forward. It is.

(A) is a top view of an example of the cushion of this invention, (b) is the side view. It is a perspective view (photograph) of the model shape which shows one example of the anchor material which comprises the cushion of this invention, and is the anchor material used in the Example. It is sectional drawing explaining the anchor material shown in FIG.

  The present invention will be described below with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding parts, but these drawings are examples of embodiments for explaining the contents of the present invention.

  FIG. 1 shows one embodiment of a cushion for holding a sitting posture according to the present invention. FIG. 1 (a) is a plan view and FIG. 1 (b) is a side view thereof. In FIG. 1, reference numeral 1 denotes an anchor material made of a plastic foam, and 2 denotes a cushioning material serving as a seating surface. As shown in FIG. 1, the cushion for holding a seating posture of the present invention is formed by integrating a cushioning material serving as a seating surface on the upper surface of an anchor material 1.

  The anchor material 1 in FIG. 1 is made of a plastic foam, and is an important component for exhibiting the effects of the present invention. That is, the seating posture can be maintained by integrating with the cushioning material, and the anchor material in the present invention is thinner than the anchor material located under the thigh, and the anchor material located under the sciatica is thinner. Even if it leans forward during use, it does not easily fall forward, and it can be used in a seat with extremely high safety.

  The anchor material in the present invention is made of a plastic foam, and since the plastic foam is used, the mechanical strength is sufficiently high, the shape of the entire cushion can be maintained, and the effect of being easy to carry when carrying Have In particular, the mechanical strength can be improved by using a hard plastic, and further, an anchor material having a good balance between flexibility and mechanical strength can be obtained by using a composite resin of a soft plastic and a hard plastic. Moreover, weight reduction of the whole cushion can be achieved by setting it as a foam. Therefore, it exhibits an excellent effect as compared with an anchor material made of soft plastic such as polyethylene or polypropylene, hard rubber or wood. Examples of such plastics include polystyrene, polyethylene / polystyrene composite resin, and polypropylene. In addition, the foamed form may be a continuous foamed form or an independent foamed form, but it is preferably a closed foamed form from the viewpoint of high mechanical strength and shape retention.

  As described above, the anchor material needs to have a different thickness between a portion located below the thigh and a thickness located below the sciatica. Specifically, the difference in the thickness of the anchor material located below the sciatic bone (a in FIG. 3) is preferably 2 to 5 cm rather than the thickness of the anchor material located below the thigh. If it is out of this range, the hardness of the cushion becomes anxious at the time of sitting use, or the cushion sinks too much, so that the holding stability of the sitting posture tends to be lowered. In addition, although the anchor material in this invention may form the recessed part with a level | step difference as shown in FIG.2 and FIG.3, it is preferable to form a taper-shaped recessed part from the point of stress dispersion | distribution.

  Moreover, it is preferable to provide an opening in the anchor material located under the sciatica. In general, when sitting on a cushion, the load applied under the sciatica is the largest, so that pressure ulcers are likely to occur around the sciatic region when sitting for a long time. The reason for this is that the tailbone and the scapula receive a repulsive stress (so-called feeling of bottoming) from the wheelchair seating surface or anchor material when seated. It is preferable to provide it. The size of the opening is not limited as long as it does not have a feeling of bottom against the coccyx or the sciatic bone, and is not limited because there are individual differences, but is about 8 to 20 cm in length and about 15 to 23 cm in width. The shape may be a circle, an ellipse, a triangular rice ball, a rhombus, or the like.

  Further, in the anchor material, it is possible to form one or two concave grooves that can hold the thigh at a position located below the thigh from the standpoint of holding posture. preferable. That is, the backward tilt posture retention by the anchor material can be improved, and the position of the thigh can be stably held by the concave groove when sitting, so that excellent posture retention can be achieved.

The cushioning material in the present invention needs to be a member that can sufficiently exhibit its original function as a cushion while being supported by the anchor material. Specifically, the hardness as a cushioning material having a function as a cushion for preventing pressure ulcer is 0.1 to 3.5 N / cm ² , preferably 0.15 to 2.0 N / cm as a compression modulus value described later. cm ² . If the hardness of the cushioning material is less than 0.1 N / cm ² , it is too soft and the buttock sinks too much when seated, so that the seatbone that sits in the buttock rests on the anchor material bottom and cushion It tends to come into contact with the surface, making it difficult to exert sufficient effects to prevent the occurrence of pressure ulcers. On the other hand, when the hardness exceeds 3.5 N / cm ² , it tends to be difficult to obtain compression stress relaxation property and shear stress relaxation property for preventing the occurrence of pressure sores because it becomes too hard.

  In addition, the hardness of the said buffer material in this invention is performed according to the measuring method as described in JISK6401 "soft polyurethane for load-bearing." Specifically, a universal testing machine (Autograph AGS-100, manufactured by Shimadzu Corporation) is used as a measuring device, and a buffer material having a size of about 38 cm in length, about 38 cm in width, and an arbitrary thickness at room temperature, or an anchor material. A value obtained by pressing a metal disk having a diameter of 200 mmφ from the upper surface of the cushioning material in the composite cushion to a depth of 25% of the entire thickness of the cushioning material or a depth of 20 mm at a compression speed of 10 mm / min, and allowing the stress to relax for 10 minutes. The compression modulus value was taken as the hardness of the buffer material.

  In this invention, the material which comprises a buffer material should just be a material which can generally be used for a cushion. Specific examples include fibers, sponges, soft plastics, foams of these plastics, and soft rubber. Of these, soft plastic foams, particularly polyurethane foams, are preferred as those that can relieve compressive stress and shear stress and prevent pressure ulcers from occurring, and are generally called low-resilience polyurethane foams. More preferably, the foam is used. In addition, as foaming form, either independent foaming or continuous foaming may be used, but in order to exert more stress relaxation as a cushioning material, the continuous foaming form (the cell wall of the independent foaming cell is torn into a continuous foaming state). (Including mixed systems such as).

  The polyurethane foam, which is a preferable material constituting the buffer material, belongs to a class of thermoplastic elastomers obtained by polyaddition reaction of polyisocyanate and polyol, and is a polyester polyurethane or polyether polyurethane. It is possible to use a foam made of the above. Specifically, a polyisocyanate prepolymer obtained by reacting a polyisocyanate such as diphenylmethane diisocyanate or tolylene diisocyanate and a polyol such as ethylene oxide or propylene oxide in an equimolar amount in terms of the number of functional groups is reacted by adding the polyol. Thus, a polyurethane composition having a three-dimensional structure (gel structure) is once produced. Next, by adding water, the unreacted isocyanate group remaining in the polyisocyanate prepolymer reacts with water to generate carbon dioxide and foam, and the isocyanate group changes to an amino group or the like by reaction with water. As a result, this reacts with other isocyanate residues to form urea bonds and the like, and the cross-linked structure proceeds to obtain a polyurethane foam having the target gel structure. At this time, by adding an excess amount of polyol to the polyisocyanate, the unreacted polyol acts as a plasticizer in the polyurethane foam. In addition, you may mix | blend a low-reactive plasticizer and softener separately.

  In the polyurethane foam having the gel structure described above, the low-reactivity polyol added for the purpose of plasticizer and the unreacted product of the polyol added for forming the urethane structure are incorporated into the polyurethane system as a liquid component. It has a gel structure in the state. As a result, in addition to stress relaxation for compressive stress, which is the original property of gels, it has the ability to absorb shearing force combined with shearing stress caused by lateral force, etc., and an excellent load as a cushion made of polyurethane foam Demonstrate dispersion performance. Moreover, since it is a foam, the weight of the entire cushion can be reduced.

  As described above, the cushion according to the present invention can maintain the sitting posture by the anchor material when seated, relaxes the compressive stress by the cushioning material, and the shear force in the lateral direction and the combined displacement force. Has an effect. The displacement force in this case is adjusted to 10 to 65 N, preferably 25 to 55 N on the cushion upper surface. That is, if the displacement force is less than 10N, the seated person may be given a fluffy feeling when sitting, and it may be difficult to maintain a stable posture. If the displacement force exceeds 65N, When the body moves in a state, a large force acts on the sitting heel part and tends to develop inflammation such as pressure ulcer. Note that the displacement force can be measured by the method described in JP-A-2006-51067.

  The cushion for holding a seating posture in the present invention can be used as a cushion for wheelchairs by being enclosed in a bag or the like when used.

The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples, and various applications are possible without departing from the technical idea of the present invention.
Examples 1-2 and Comparative Examples 1-2
As the buffer material, the following composition was prepared.

  50 parts by weight of diphenylmethane diisocyanate and 50 parts by weight of polyether polyol (polyoxyethylpolyoxypropylated glycol, ethylene oxide / propylene oxide: 75/25% by weight, hydroxyl value: 56, molecular weight: 3000) Isocyanate prepolymer A (isocyanate group content: 15 mol%) was prepared.

  Further, 5 parts by weight of tolylene diisocyanate and 95 parts by weight of a polyol (polyoxyethyl polyoxypropylated glycol, ethylene oxide / propylene oxide: 70/30% by weight, hydroxyl value: 7.5, molecular weight: 15000) are reacted. To produce a polyisocyanate prepolymer B (isocyanate group content: 2 mol%).

Next, 65 weights of polyether polyol (polyoxyethyl polyoxypropylated glycol, ethylene oxide / propylene oxide: 50/50) was added to 21 parts by weight of polyisocyanate prepolymer A and 14 parts by weight of polyisocyanate prepolymer B prepared above. Part is reacted to prepare a polyurethane gel composition, then 3 parts by weight of water as a foaming agent is added at room temperature, stirred and mixed, poured into a mold, foamed and aged to form a gel structure A buffer material (displacement force 30 N, buffer member portion hardness 0.4 N / cm ² ) made of a low-resilience polyurethane foam having a length of 38 cm (length: 38 cm, width: 38 cm, thickness: 4.5 cm) was prepared.

  On the other hand, the anchor material was made of a polyethylene / polystyrene composite resin foam, and an anchor material having a shape shown in FIG. 2 was produced. Specifically, four anchor materials (Example 1) having a length of 38 cm, a width of 38 cm, a maximum thickness (under the thigh) of 6.5 cm, and a thickness of the thinnest part (a recess under the sciasis) changed as shown in Table 2 -2, Comparative Examples 1-2) were produced.

  Next, on the anchor material obtained above, the cushioning material made of the produced low resilience polyurethane foam is placed, and the seating posture holding cushion model of the present invention is manufactured to maintain the sitting posture. , The hardness of the seating surface when seated, and the pressure dispersibility were evaluated. In addition, as a reference example, measurement was also performed on a cushion made of only a cushioning material without an anchor material.

  The seating posture retention, the seating surface hardness, and the pressure dispersibility were evaluated according to the following criteria. The seating posture retention and the hardness of the seating surface were evaluated using four test subjects shown in Table 1 below, and the average values are shown in Table 2.

<Sitting posture retention>
The “stability” and “security” while seated were confirmed by listening to the impressions of each subject. The evaluation score was made into 5 grades from 1 to 5 points, and 1 point was given when instability and anxiety were strong, and 5 points were given when stability and security were strong.
<Hardness of the seating surface>
It was confirmed by listening to the impression of each subject about the sinking and the hardness of the seating surface when sitting on the cushion. The evaluation score was made into 5 stages from 1 to 5 points, and it was scored as 1 point when it was too subdued or the seat surface was too hard, and 5 points when there was moderate subsidence and moderate hardness. .
<Pressure dispersibility>
About the cushion obtained in each Example and the comparative example, the pressure dispersibility at the time of sitting was measured. The pressure dispersibility is measured by laying a sensor sheet (manufactured by Verg Inc., model name: FSA, number of sensors 32 × 32, sensor pitch 14 mm) on which a pressure sensor is incorporated on a cushion, Table 2 shows the number of sensors showing a contact pressure of 150 mmHg or more. The smaller the number, the better the stress dispersibility and the more effective the prevention of pressure ulcers.

  As is apparent from the results in Table 2, the products of the examples have excellent sitting posture retention and a good balance between the hardness of the seating surface and the pressure dispersibility.

  That is, the sitting posture holding cushion of the present invention is superior in holding the sitting posture as compared to the cushion made of the cushioning material alone, and the anchor material is in a specific shape, so that it is in a backward tilted posture while sitting, It was confirmed that the cushion was extremely stable and safe without any tipping forward while sitting.

  Moreover, since the cushion of this invention combines the anchor material compared with the case where it uses only with a shock absorbing material, the thickness of a cushion can be reduced and weight reduction can be implement | achieved. Further, even if such lightening is performed, the characteristics of the cushioning material such as load dispersibility are not impaired. Therefore, if the cushion of this invention is used for a wheelchair, it can be used as a safe and comfortable cushion, and can be effectively used in the field of nursing care.

1 Anchor material 2 Buffer material 3 Sciatic bone

Claims (5)

A cushion for holding a seating posture comprising an anchor material made of a plastic foam and a cushioning material having stress relaxation properties integrated and positioned on the anchor material so that the posture at the time of sitting is a backward tilted posture. A cushion for holding a sitting posture, characterized in that the thickness of the anchor material located under the sciatic bone is thinner than the thickness of the anchor material located under the thigh. The cushion according to claim 1, wherein the thickness of the anchor material located below the sciatica is 2 to 5 cm thinner than the thickness of the anchor material located below the thigh. The cushion according to claim 1 or 2, wherein the anchor material located below the sciatica has an opening. The cushion according to claim 1, wherein one or two concave grooves are formed so that the thigh can be held in an anchor material located under the thigh. The cushion according to claim 1, wherein the cushioning material is made of a low resilience polyurethane foam.