WO2009035888A2

WO2009035888A2 - Protection pad and method for manufacturing the same

Info

Publication number: WO2009035888A2
Application number: PCT/US2008/075110
Authority: WO
Inventors: Weilai Jiang
Original assignee: 3M Innovative Properties Company
Priority date: 2007-09-12
Filing date: 2008-09-03
Publication date: 2009-03-19
Also published as: CN101385576A; WO2009035888A3

Abstract

The present invention relates to a protection pad, which has good bending performance in all directions so that it can be well matched to the portion to be protected, and a method for manufacturing the same. The protection pad comprises: an outer layer made of flexible and stretchable elastic film material; an intermediate layer comprising a plurality of buffer units arranged separately and alternatively from one another; a base layer made of flexible and stretchable elastic film material, wherein, each of the plurality of buffer units is bonded to the outer layer and the base layer at two ends thereof respectively. The protection pad further comprises nondrying adhesive applied to the outer side of the base layer for fixing the protection pad at a portion to be protected.

Description

PROTECTION PAD AND METHOD FOR MANUFACTURING THE SAME

FIELD OF THE INVENTION

The present invention relates to a protection pad and the method for manufacturing the same. Specifically, the present invention relates to a protection pad, which has good bending performance in all directions so that it can be well matched with a portion intended to be protected ,and a method for manufacturing such a protection pad.

BACKGROUND OF THE INVENTION

Protection pads, especially those for human body protection is in great need of buffer material which has elastic resilience for absorbing external impact and friction. The buffer material can be constricted in volume upon receiving an external force so as to absorb external energy for achieving protection effect. When the external force is withdrawn, the buffer material can restore to its original volume so that long term and repetitive protection can be obtained.

However, material of good elastic resilience generally can not perfectly conform to the portions to be protected, such as the surface of the human body, because, the surface of the human body usually has irregular arc shapes, and particularly, in the articulated portions of the body, such as the shoulder, the elbow, the ankle and the like. The arc degree of the surface of body may vary continuously along with the motion of the body. If the protection pad uses material of high elastic resilience, the protection effect may be good, but the motion of the body will be impaired and the user may feel uncomfortable, and even more, it is difficult to maintain the good conformation between the protection pad and the body.

The US patent application No. US20060199456 discloses a composite structure for addressing the problem that the pure buffer material has poor flexibility. The process for making the composite structure comprises: firstly, thermally bonding the sheet of buffer material and a base material; then partitioning the sheet of buffer material by die cutting; then stretching the base material so as to partition the sheet of buffer material into separate buffer bodies. With the buffer pad made by such way, the space between the buffer bodies is very limited. Furthermore, it can be bent only in one direction and make little difference in effect compared to conventional protection pads having cutting lines. The international publication WO 2006036072 discloses an array type buffer material in which the buffer bodies arranged regularly, is made by die cutting the sheet of buffer material. In the array type buffer material, however, each of the buffer bodies is connected to one another and the whole buffer material is substantially continuous. Such form can improve the flexibility of the buffer material and the inward and outward bending performances are substantially the same. However, when the thickness of the buffer material is increased, the flexibility thereof is greatly degraded.

The French patent application No. FR 2797154 discloses a body protection pad in which grooves are formed on the surface of the buffer material by a die so that the buffer material is partitioned into a series of separate buffer units with the buffer units in the middle portion having lower height. With this configuration, when the protection pad is bent, it is capable of conforming to the articulated portions of the body better. The thickness at the portions of the grooves is small so that the bending performance of the buffer material is improved, while the height of the buffer units is large so that the protection effect can be ensured. However, such a solution raises high requirement on the die machining associated with the protection pad, and especially, for products with small buffer units of high distribution density, the die machining associated with the pad is very difficult. The French patent application No. FR 2879078 discloses a protection pad similar to that in the French patent application FR 2797154 except that the buffer units are disposed at two sides.

SUMMARY OF THE INVENTION

The present invention is made in view of at least one aspect of the problems existing in the prior art.

According to one aspect of the present invention, there is provided a protection pad, comprising an outer layer made of flexible and stretchable elastic film material, an intermediate layer comprising a plurality of buffer units arranged separately and alternatively from one another, a base layer made of flexible and stretchable elastic film material, wherein, each of the plurality of buffer units is bonded to the outer layer and the base layer at two ends thereof respectively.

When the protection pad is bent in use, two adjacent rows or lines of the plurality of buffer units will not interfere with each other. A portion of the outer layer between the buffer units is free to be bent and stretched.

The protection pad may further comprise nondrying adhesive applied to the outer side of the base layer for fixing the protection pad at a portion to be protected.

The outer layer and the buffer units may be bonded by pressure-sensitive adhesive, and the pressure-sensitive adhesive is only applied at the ends of the buffer units instead of being applied to the surface of the outer layer continuously. Similarly, the base layer and the buffer units may be bonded by hot-melt adhesive, and the hot-melt adhesive is simply applied at the ends of the buffer units instead of being applied to the surface of the base layer continuously.

In an embodiment, the buffer units are made of foam material and the foam material is preferably closed-pore foam material. The closed-pore foam material may be closed-pore polyolefin foam material, such as low density polythene, middle density polythene, high density polythene, ethylene vinyl acetate copolymer, ethylene methyl acrylate copolymer, and the like.

The buffer unit may be a rod body having a cross section of square, circular, or polygonal shape, and the buffer units may have different dimensions and shapes.

The arrangement of the buffer units may satisfy the condition:

S%^(PXA)/B

Wherein, S% represents percentage of coverage of the buffer units per unit area; P represents the load borne by the protection pad per unit area; A represents area of the pressure head; and B represents the compression stress under the allowable maximum compression rate determined under the working state of the foam material according to method of Chinese National Standard GB 10807.

In another embodiment, the minimum distance between the buffer units is greater than 1 mm. The horizontal distance between two adjacent buffer units in the horizontal direction is equal to or greater than the horizontal width of the adjacent buffer units; in the vertical direction, the vertical distance between the two adjacent buffer units is equal to or greater than the vertical width of the adjacent buffer units.

The working temperature of the hot-melt adhesive is not higher than the heat distortion temperature of the foam material, but higher than the upper limit of temperature in actual use.

The hot-melt adhesive is preferably ethylene vinyl acetate (EVA) type low melting point adhesive.

The base layer may be hydraulic needling non-woven fabrics or polyurethane film, and the outer layer may be polyurethane film, elastic fabrics, or non-woven fabrics.

If necessary, the outer layer and the base layer may be made of material of good air permeability.

According to another aspect of the present invention, there is provided a method for manufacturing protection pad, the method comprising the steps of: a) preparing buffer sheet material, applying pressure-sensitive adhesive on a side of the buffer sheet material and attaching a film of the pressure-sensitive adhesive to a releasing paper; b) joining a film of the hot-melt adhesive on a side of the buffer sheet material to which the pressure-sensitive adhesive is not applied by a hot mill, wherein the working temperature of the hot-melt adhesive is lower than the hot distortion temperature of the buffer sheet material; c) die cutting the semi-product obtained from the step b) with a cutting die prepared in advance, wherein the blade of the cutting die should cut off the film of hot-melt adhesive, the buffer sheet material and the pressure-sensitive adhesive but should not cut off the releasing paper; d) removing continuous waste material so as to form buffer units arranged separately from each other on the releasing paper according to the design positions; e) joining the base layer and the buffer units obtained from the above step d) by a hot mill, then cooling and removing the releasing paper; and f) joining the semi-product obtained from the step e) and outer layer and adhesively fixing them by the pressure-sensitive adhesive at one ends of the buffer units.

The cutting die is prepared according to the designed dimension and cross section shape of the buffer unit.

An advantage of at least one embodiment of the present invention lies in that it has improved conventional protection pads in structure and manufacturing process. As result, the protection pad according to the embodiment of the present invention has perfect bending performance in all directions and is improved in flexibility and air permeability, and therefore is comfortable for use. At the same time, the impact resistance of several embodiments can be well ensured.

The other objects and advantages of the present invention will be obvious from the detailed description of the embodiments in the following, together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments of the present invention will be described with reference to the accompanying drawings.

Figure 1 is a side view showing the composite structure of the protection pad according to an embodiment of the present invention;

Figures 2-4 are top views showing the composite structure of the protection pad according to an embodiment of the present invention;

Figure 5 is a schematic view showing the protection pad under use;

Figure 6a, 6B and 6C show the cross section and arrangement of the buffer unit of the protection pad according to an embodiment of the present invention in detail; and

Figure 7-9 shows the steps according to the method for manufacturing the protection pad according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Figure 1 is a side view showing the composite structure of the protection pad according to an embodiment of the present invention. As shown in figure 1 , the protection pad 100 has a three-layer structure. The outer layer 1 is made of flexible and stretchable elastic fiber or film material. The intermediate layer 2 is a buffer layer comprising a series of separate buffer units 4 arranged alternately from one another. The base layer 3 is made of flexible fiber or film material. The material of the outer layer 1 is very flexible elastic material having good stretchability, such as polyurethane film, elastic fabrics or elastic non-woven fabrics. The outer layer 1 is bonded to one end of the intermediate buffer unit 4. The portions of the outer layer 1 between the buffer units 4 are free to be bent and stretched. Therefore, when the protection pad 100 is bent, the portions of the outer layer which are not bonded to the buffer unit 4 (that is, the portions between the buffer units 4) can be stretched and shrunk as the distance between the top ends of the buffer units 4 increases and decreases. This ensures that the movement (for example, the body movement of the user) of the portions where the protection pad 100 is used is not restricted.

The base layer 3 is usually made of flexible and flexible air permeable material, such as hydraulic needling non-woven fabrics, polyurethane film and the like. The base layer 3 serves to support the intermediate layer 2 so as to provide necessary strength for the buffer unit 4 while not affecting the bending performance of the protection pad 100 when it is bent. The external side of the base layer 3 can be applied with nondrying adhesive so that it can be conveniently attached to the portions to be protected, such as a portion of the body, as an attaching product.

The buffer unit 4 is made of foam material. Preferably, the buffer unit 4 is made of closed pore foam material. The closed pore foam material is preferably closed pore polyalkene foam material, but it can be other material having similar buffer property. The suitable polyalkene foam material comprises low density Low-Density Polyethylene (LDPE), middle density polyethylene (MDPE), High-density polyethylene (HDPE), ethylene vinyl acetate copolymer(EVA), ethylene methyl acrylate copolymer(EMA) and the like. The above polyalkene foam material is good for being not easy to absorb water and breed microorganism. Also, it is not irritant or allergic to the skin of the human body in normal condition. Therefore, it is suitable to be used as the material of buffer units 4 of the intermediate layer 2. In an embodiment of the present invention, the buffer unit is generally a rod shaped body.

Figures 2-4 are top views showing the composite structure of the protection pad according to the present invention. Figures 2-4 shows an exemplified arrangement of the buffer units 4 in the protection pad 100. The cross section of the buffer unit may be designed as square shape (figure 2), circular shape (figure 3), polygonal shape (figure 4) and the like. The composite structure is characterized in that the respective buffer units 4 are separate from one another, and arranged alternately. It should be noted that, although the buffer units 4 in the same structure are shown in the figures to have identical dimensions and shapes, the dimensions and shapes of the buffer units may vary as required. An example of this is shown in an embodiment as shown in figure 6C.

Figure 5 is a schematic view showing the protection pad under use. As shown in figure 5, the protection pad 100 according to the present invention may be externally or internally bent. Furthermore, it can be seen that when the protection pad 100 is bent, the two adjacent rows or lines of buffer units 4 do not interfere with each other.

The cross section and arrangement of the buffer units 4 of the protection pad 100 according to the present invention will be described in detail with reference to figure 6A, 6B and 6C.

Firstly, the horizontal distance between two adjacent buffer units in the horizontal direction is equal to or greater than the horizontal width of the adjacent buffer units; in the vertical direction, the vertical distance between the two adjacent buffer units is equal to or greater than the vertical width of the adjacent buffer units. Figures 6A, 6B and 6C show an example of ten buffer units 4 to illustrate the dimension relationship thereof. As shown in figure 6A, each square cross section has a side having a length of 4mm; in each row, the distance between the two adjacent squares is 4 mm; in each line, the distance between the two adjacent squares is 6 mm.

As shown in figure 6B, each circular cross section has a diameter of 4 mm; the circular cross sections are arranged alternately in respective rows and lines, and the two adjacent rows share a horizontal tangential line while the two adjacent lines share a vertical tangential line. In each row, the distance between the vertical tangential lines of the two adjacent circles is 4 mm; in each line, the distance between the horizontal lines of the two adjacent circles is 4 mm.

In figure 6C, the circular cross sections of 3 mm diameter and the circular cross sections of 5mm diameter are arranged alternately in respective rows and lines. The two adjacent rows share a horizontal tangential line while the two adjacent lines share a vertical tangential line. In each row, the distance between the vertical tangential lines of the two adjacent circles of 3 mm diameter is 5 mm while the distance between the vertical tangential lines of the two adjacent circles of 5 mm diameter is 3 mm; in each line, the distance between the horizontal lines of the two adjacent circles of 3 mm diameter is 5 mm while the distance between the horizontal lines of the two adjacent circles of 5 mm diameter is 3 mm.

At the same time, in a preferred embodiment, the minimum distance between two buffer units 4 may be larger than 1 mm so as to ensure that the waste material will not be broken when the waste material is discharged during the process of manufacture.

Further, the coverage percentage S% of the buffer units 4 in unit area can be calculated according to the load requirement of the protection pad and the material performance. If the protection pad is required to bear a load P per unit area, the allowable maximum compression rate under the working state of the foam material used is a%, the compression stress at the allowable maximum compression rate of a% determined according to Chinese National Standard GB10807 method is B, and the area of the pressure head for testing and determination is A, then the coverage percentage S% of the buffer units 4 in unit area meets the condition:

S%^(PXA)/B.

If S% calculated according to the above method is equal to or greater than 1 , it indicates that the selected material does not satisfy the requirement.

The dimensions and shapes of the buffer units 4 can be different. The feasibility and economical efficiency of the die cutting process should also be considered in design.

Figures 7-9 show the steps according to the method for manufacturing the protection pad according to an embodiment of the present invention.

As shown in figure 7, firstly, preparing buffer sheet material 5, applying pressure-sensitive adhesive 6 on a side of the buffer sheet material 5 and attaching it to a releasing paper 7. Then, joining a film of the hot-melt adhesive 9 on a side of the buffer sheet material 5 to which the pressure-sensitive adhesive is not applied by a hot mill 8, wherein it is important that the working temperature of the hot-melt adhesive 9 is lower than the hot distortion temperature of the buffer sheet material 5.

As shown in figure 8, the semi-product is die cut with a cutting die 10 prepared in advance, wherein the blade of the cutting die should cut off the film of hot-melt adhesive 9, the buffer sheet material 5 and the pressure-sensitive adhesive layer 6 but should not cut off the releasing paper 7. After the die cutting, the continuous waste material is removed so that the buffer units are left arranged separately from each other on the releasing paper 7 according to the design positions.

As shown in figure 9, the base layer 3 and the buffer units 4 are joined together by a hot mill 8, then cooling and removing the releasing paper 7. At this time, the buffer units 4 are fixed in position with respect to one another on the base layer 3. Finally, the semi-product and outer layer 1 are joined together and adhesively fixed by the pressure-sensitive adhesive at one end of the buffer units 4.

The product obtained can be cut into certain sizes as desired.

During the process of the manufacture, the method has at least the following advantages. (1 ) Although all the buffer units 4 are discrete from one another (this is different from the conventional layer type bonding), the method of the present invention can be employed to ensure the right position of the buffer units 4 with respect to one another so as to ensure that the array of buffer units 4 will not be damaged. At the same time, the manufacture efficiency is satisfactory. (2) According to the embodiments of the present invention, since the adhesive is applied only to the portions where the base layer 3 and the outer layer 1 are joined to the buffer units 4, the use of the adhesive does not affect the flexibility of the base layer 3 and the outer layer 1 greatly so that the comfortableness for use is increased. (3) The outer layer 1 and the base layer 3 are not adhered to each other; if the adhesive is simply applied on the base layer 3 and the outer layer 1 continuously, then during the process of manufacture and use, the portions of the base layer 3 and the outer layer 1 which are not joined to the buffer units 4 will adhere to each other and result in failure of the original structure.

Specifically, the pressure-sensitive adhesive serves to perform positioning function during the process of die cutting and joining. After die cutting, the continuous waste of buffer sheet material 5 is removed and the discrete buffer units is fixed on the releasing paper under the effect of the pressure-sensitive adhesive with the distance between the buffer units being maintained. Then, the base layer 3, which is not easy to be deformed by stretching, is bonded to the upper side of the buffer units 4 and the buffer units 4 is removed from the releasing paper. At this time, the relative positions of the respective buffer units 4 with respect to one another are fixed. The hot-melt adhesive film is covered on one side of the buffer sheet material 5 in advance, so that it is not necessary for the adhesive to be directly applied on the base layer 3 or the outer layer 1. In this way, adhesion will not occur. The hot-melt adhesive is characterized in that it exhibits adhesion only at a temperature beyond its working temperature. Utilizing this characteristics, die cutting can be performed at a temperature below the working temperature of the adhesive film. At this time, the adhesive film will not adhere to the blade of the cutting die. When the buffer units are joined to the base layer 3, the only thing to do is to press them together at a temperature beyond the working temperature, so that the hot-melt adhesive exhibits adhesion. It should be noted that, the working temperature of the hot-melt adhesive should not be higher than the heat distortion temperature of the selected foam material. At the same time, it must be higher than the upper limit of the temperature in actual use. The EVA type low-melt point adhesive film is preferable.

From the above description, it is obvious that the protection pad according to the present invention has apparent advantages in structure in comparison with the existing protection pad and therefore can bring forth better effect in use. The protection pad according to the invention has perfect bending performance and flexibility while guaranteeing certain impact resistance. Further, the air permeability of the protection pad of the present invention is improved. If special application such as application in athletic sports which requires much higher air permeability, then air permeability can be further improved by choosing material of perfect air permeability as the outer layer and the base layer.

Further, the structure disclosed in the present invention may also be applied to other applications listed as below in addition to applications in the protection products by modifying the properties of raw materials:

(1 ) Insulation

The present invention can be regarded as an insulation structure having a certain thickness which is formed by using a set of discrete foam units. Since the foam material itself has good insulation performance, such a composite structure can also exhibit good insulation. At the same time, such structure can be used for insulation protection of surface of special shape because it is very flexible and capable of conforming to surfaces of various shapes.

(2) Cold and heat proof

Since foam material and air both are poor conductors of heat, such a composite structure is capable of effectively blocking heat transfer so as to act for the purpose of cold or heat proof.

(3) Energy saving and sealing

The material for energy saving and sealing purpose is usually applied to the slits or gaps in the room door or window for reducing heat exchange between indoor space and outdoor space, so that the power consumption of the air conditioner can be reduced and the energy can be saved. The structure of the present invention has much better flexibility in comparison to the generally used foam cotton adhesive tape, and therefore is much suitable for sealing area which has a uneven surface

The present invention can be further modified and employed by those skilled in the art without departing from the scope of the claims.

Claims

Claims:

1. A protection pad, comprising: an outer layer made of flexible and stretchable elastic film material; an intermediate layer comprising a plurality of buffer units arranged separately and alternatively from one another; a base layer made of flexible and stretchable elastic film material, wherein, each of the plurality of buffer units is bonded to the outer layer and the base layer at two ends thereof respectively.

2. The protection pad according to claim 1 , wherein when the protection pad is bent in use, and two adjacent rows or lines of the plurality of buffer units will not interfere with each other.

3. The protection pad according to claim 2, wherein a portion of the outer layer between the buffer units is free to be bent and stretched.

4. The protection pad according to claim 3, further comprising nondrying adhesive applied to the outer side of the base layer for fixing the protection pad at a portion to be protected.

5. The protection pad according to claim 3, wherein the outer layer and the buffer units are bonded by pressure-sensitive adhesive, and the pressure-sensitive adhesive is only applied at the ends of the buffer units.

6. The protection pad according to claim 3, wherein the base layer and the buffer units are bonded by hot-melt adhesive, and the hot-melt adhesive is only applied at the ends of the buffer units.

7. The protection pad according to claim 6, wherein the buffer units are made of foam material.

8. The protection pad according to claim 7, wherein the foam material is closed-pore foam material.

9. The protection pad according to claim 8, wherein the closed-pore foam material is closed-pore polyolefin foam material.

10. The protection pad according to claim 9, wherein the closed-pore polyolefin foam material comprising: low density polythene, middle density polythene, high density polythene, ethylene vinyl acetate copolymer, ethylene methyl acrylate copolymer.

11. The protection pad according to claim 7, wherein each of the buffer units is a rod body having a cross section of square, circular, or polygonal shape, and the buffer units may have different dimensions and shapes.

12. The protection pad according to claim 11 , wherein the arrangement of the buffer units satisfies the condition:

S%^(PXA)/B

13. The protection pad according to claim 12, wherein the minimum distance between the buffer units is greater than 1 mm.

14. The protection pad according to claim 13, wherein the horizontal distance between two adjacent buffer units in the horizontal direction is equal to or greater than the horizontal width of the adjacent buffer units; in the vertical direction, the vertical distance between the two adjacent buffer units is equal to or greater than the vertical width of the adjacent buffer units.

15. The protection pad according to claim 7, wherein the working temperature of the hot-melt adhesive is not higher than the heat distortion temperature of the foam material, but higher than the upper limit of temperature in actual use.

16. The protection pad according to claim 15, wherein the hot-melt adhesive is EVA type low melting point adhesive.

17. The protection pad according to claim 3, wherein the base layer is hydraulic needling non-woven fabrics or polyurethane film.

18. The protection pad according to claim 3, wherein the outer layer is polyurethane film, elastic fabrics, or non-woven fabrics.

19. The protection pad according to claim 3, wherein the outer layer and the base layer are made of material of good air permeability.

20. A method for manufacturing protection pad, comprising the steps of: a) preparing buffer sheet material, applying pressure-sensitive adhesive on a side of the buffer sheet material and attaching a film of the pressure-sensitive adhesive to a releasing paper; b) joining a film of the hot-melt adhesive on a side of the buffer sheet material to which the pressure-sensitive adhesive is not applied by a hot mill, wherein the working temperature of the hot-melt adhesive is lower than the hot distortion temperature of the buffer sheet material; c) die cutting the semi-product obtained from the step b) with a cutting die prepared in advance, wherein the blade of the cutting die should cut off the film of hot-melt adhesive, the buffer sheet material and the pressure-sensitive adhesive but should not cut off the releasing paper; d). removing continuous waste material so as to form buffer units arranged separately from each other on the releasing paper according to the design positions; e). joining the base layer and the buffer units obtained from the above step d) by hot pressing with a hot mill, then cooling and removing the releasing paper; and f). joining the semi-product obtained from the step e) and outer layer and adhesively fixing them by the pressure-sensitive adhesive at one end of the buffer units.

21. The method according to claim 20, wherein the cutting die is prepared according to the designed dimension and cross section shape of the buffer unit.