Soft Elastic Disposable Gloves

Abstract

A single use disposable glove utilizing the cutting and sealing process. The top and bottom panels of the glove are produced from an extrusion process made from a variety of thermoplastic elastomers containing styrenic block copolymer (SBC). The glove made from this process is form fitting, has less than 20% deformation after 100% stretch for 10 second. The suitable SBC materials are selected from the group consisting of SIS, SBS, SEBS, SEPS, SEEPS, and combinations thereof.

Claims

1. A disposable glove comprising: one top panel in the form of a hand comprising at least one layer made from a first SBC-based thermoplastic elastomer (TPE), said top panel has less than 20% deformation after 100% stretch for 10 seconds; one bottom panel in the form of said hand comprising at least one layer made from a second SBC-based thermoplastic elastomer (TPE), said bottom panel has less than 20% deformation after 100% stretch for 10 seconds; wherein an opening is provided between said top panel and said bottom panel for the insertion of a human hand; the top panel has a first thickness between 0.02 mm and 0.1 mm; and the bottom panel has a second thickness between 0.02 mm and 0.1 mm.

2. A glove as described in claim 1, wherein each of said first and second thermoplastic elastomers comprises a member selected from the group consisting of SIS, SBS, SEBS, SEPS, SEEPS and combinations thereof.

3. A glove as described in claim 1, wherein the Melt Flow Indices of the thermoplastic elastomers are from 0.5 g/10 mins to 10 g/10 mins according to ASTM Test D1238 at 190 C and at a load of 2.16 kg.

4. A glove as described in claim 1, wherein at least one of said thermoplastic elastomers comprises one SIS and a member selected from the group consisting of SBS, SEBS, SEPS and SEEPS.

5. A glove as described in claim 1, wherein at least one of said thermoplastic elastomers comprises one SBS and a member selected from the group consisting of SIS, SEBS, SEPS and SEEPS.

6. A glove as described in claim 1, at least one of the panels is made by a biaxially oriented process.

7. A glove as described in claim 1, wherein the hardness of at least one of the panels is in the range of 35 Shore A to 90 Shore A.

8. A glove as described in claim 1, wherein the hardness of at least one of the panels is in the range of 50 Shore A to 80 Shore A.

9. A glove as described in claim 1, wherein said top panel has less than 10% deformation after 100% stretch for 10 seconds; said bottom panel has less than 10% deformation after 100% stretch for 10 seconds.

10. A disposable glove comprising: one top panel in the form of a hand with at least one layer made from a first thermoplastic elastomer comprising a first SBC, said first SBC having 12-25% styrene content by weight; one bottom panel in the form of said hand with at least one layer made from a second thermoplastic elastomer comprising a second SBC, said second SBC having 12-25% styrene content by weight; wherein a portion of the periphery of said bottom panel is welded to a portion of the periphery of said top panel; an opening is provided between said top panel and said bottom panel for the insertion of a human hand; the top panel has a first thickness between 0.02 mm and 0.1 mm; the bottom panel has a second thickness between 0.02 mm and 0.1 mm.

11. A glove as described in claim 10, where the Melt Flow Indices of the thermoplastic elastomers are from 0.5 g/10 mins to 10 g/10 mins according to ASTM Test D1238 at 190 C and at a load of 2.16 kg.

12. A glove as described in claim 10, wherein each of said first SBC and second SBC is selected from the group consisting of SIS, SBS, SEBS, SEPS, SEEPS and combinations thereof.

13. A glove as described in claim 10, wherein each of said first SBC and second SBC is selected from the group consisting of SIS, SBS, SEBS, SEPS, SEEPS and combinations thereof; and the Melt Flow Indices of the thermoplastic elastomers are from 0.5 g/10 mins to 10 g/10 mins according to ASTM Test D1238 at 190 C and at a load of 2.16 kg.

14. A glove as described in claim 10, wherein each of said thermoplastic elastomers comprises at least two SBC's selected from the group consisting of SIS, SBS, SEBS, SEPS and SEEPS.

15. A glove as described in claim 10, wherein each of said first and second panels has less than 20% deformation after 100% stretch for 10 seconds.

16. A glove as described in claim 10, wherein each of said first and second panel has less than 10% deformation after 100% stretch for 10 seconds.

17. A glove as described in claim 10, wherein at least one of said panels is made by a biaxially oriented process.

18. A glove as described in claim 10, wherein the hardness of one layer of the top or bottom panel is in the range of 50 shore A to 80 Shore A.

19. A disposable glove comprising: one top panel in the form of a hand with at least one layer made from a first thermoplastic elastomer comprising a) a first SBC having 12%-25% styrene by weight, and b) a first polyethylene (PE); one bottom panel in the form of said hand with at least one layer made from a second thermoplastic elastomer comprising c) a second SBC having 12%-25% styrene by weight, and d) a second polyethylene (PE), wherein a portion of the periphery of said bottom panel is welded to a portion of the periphery of said top panel; an opening is provided between said top panel and said bottom panel for the insertion of a human hand; the top panel has a first thickness between 0.02 mm and 0.1 mm; the bottom panel has a second thickness between 0.02 mm and 0.1 mm; each of said first and second SBC's is selected from the group consisting of SIS, SBS, SEBS, SEPS, and SEEPS.

20. A glove as described in claim 19, wherein the Melt Flow Indices of the thermoplastic elastomers are from 0.5 g/10 mins to 10 g/10 mins according to ASTM Test D1238 at 190 C and at a load of 2.16 kg.

21. A glove as described in claim 19, wherein each of said first and second panels has less than 20% deformation after 100% stretch for 10 seconds.

22. A glove as described in claim 19, wherein each of said first and second panels has less than 10% deformation after 100% stretch for 10 seconds.

23. A glove as described in claim 19, wherein at least one of the panels is made by a biaxially oriented process.

24. A glove as described in claim 19, wherein the hardness of one layer of the top or bottom panel is in the range of 50 Shore A to 80 Shore A.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The above and additional objects, characteristics, and advantages of the present invention will become apparent in the following detailed description of preferred embodiments, with reference to the accompanying drawings.

[0014] FIG. 1 is a top view of two welded thin film layers of a thermoplastic elastomer material.

[0015] FIG. 2 is a side view of two welded thin film layers of a thermoplastic elastomer material.

[0016] FIG. 3 is a broad view of a thermoplastic elastomer glove.

[0017] Identical reference numerals throughout the figures identify common elements.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Definitions

[0018] As used herein, “PVC” means polyvinyl chloride; “NRL” means natural rubber latex; “PE” means polyethylene; “TPE” means thermoplastic elastomer.

[0019] As used herein, and consistent with ISO 1382, “thermoplastic elastomer” is a polymer or a mixture of polymers which doesn't need vulcanization or reticulation when processed, but demonstrates similar properties as vulcanized rubber at service temperature. These properties disappear at processing temperature to allow the ulterior process possible, but reappear as the material returns to working temperature.

[0020] As used herein, the term “elastomeric” and “elastic” refer to a material that, upon application of a stretching force, is stretchable in at least one direction, and which upon release of the stretching force, contracts/returns to approximately its original dimension. For example, a stretched material may have a stretched length that is at least 50% greater than its relaxed unstretched length, and which will recover to within at least 50% of its stretched length upon release of the stretching force. A hypothetical example would be a one (1) inch sample of a material that is stretchable to at least 1.50 inches and which, upon release of the stretching force, will recover to a length of not more than 1.25 inches. Desirably, the material contracts or recovers at least 50%, and even more desirably, at least 80% of the stretched length, and most desirably, at least 90% of the stretched length.

[0021] As used herein, “SBC” means Styrenic Block Copolymer. As the name implies, a SBC is made of blocks of distinct polymers that each contribute to the properties of the polymer. The polystyrene end-blocks are hard polymers that add strength to the SBC elastomer. The mid-blocks are composed of rubbery polymers such as polyisoprene, polybutadiene, ethylene-butylene copolymer and others.

[0022] As used herein, “SIS” means an SBC having the structure of styrene-Isoprene-styrene;

[0023] “SBS” means an SBC having the structure of styrene-butadiene-styrene;

[0024] “SEBS” means an SBC having the structure of styrene-ethylene butylene-styrene;

[0025] “SEPS” means an SBC having the structure of styrene-ethylene Propylene-styrene;

[0026] “SEEPS” means an SBC having the structure of styrene-ethylene ethylene propylene-styrene.

[0027] As used herein, the term “weld” refers to securing at least a portion of a first polymer film with a portion of at least a second polymer film by temporarily rendering at least a portion of one film or an intermediate material into a softened or plastic state and joining the films without the use of mechanical attachments such as, for instance, stitching or without the use of an adhesive material that causes the films to stick together. Two or more films can be welded together in various ways such as through thermal bonding, ultrasonic bonding, pressure bonding, solvent bonding, or mixtures thereof.

[0028] As used herein, an “elastomer” refers to any polymer material that is elastomeric or elastic and includes plastomers.

[0029] As used herein, the tensile properties of a film including modulus and load at break are measured according to ASTM Test D412 using Die D or ASTM D-882.

[0030] As used herein, a panel that is formed from a “different composition of materials” in relation to another panel refers to any formulation variation between the two panels. Two panels having a different composition of materials may include panels made from different thermoplastic elastomers (for example one from SIS and the other from SEBS) or may include panels containing different additives or the same additives in different amounts (for example one panel is made from SIS with an oil, the other panel is made from SIS with a PE and without oil). Two panels being made from a different composition of materials can also occur when the panels contain different coloring compounds.

[0031] As used herein, a film or panel is said to be “based” on an SBC elastomer when the film or panel is made from said SBC elastomer in its pure form, or is made from a mixture of said SBC elastomer and at least one more other ingredients, including but not limited to an oil, a PE, a coloring compound or other polymers.

[0032] The present invention overcomes the poor plastic deformation after stress produced by the prior art cutting and sealing process employing polyethylene (PE) to produce the two panels of the glove. This is accomplished by utilizing a family of SBC selected from the group consisting of SIS, SBS, SEBS, SEPS, SEEPS and combinations thereof.

[0033] The use of these compositions for the top or bottom panel would produce a panel having a thickness in the range of 0.02 mm to 0.1 mm with excellent film integrity, but also good elasticity, thereby reducing hand fatigue. With improved elasticity not only would the glove be classified as truly form fitting, but it would also exhibit improved durability.

[0034] Compared to the dipping process, the cutting and sealing process employing the films produced by the above-listed compositions, would produce better film quality and reduced thickness and provide for a more versatile film structure, as well as wider glove material selection. For example, utilizing polyvinyl chloride to make a plastisol compound suitable for the manufacture of a glove using the dipping process, very limited choices of plasticizers are available. This is true, for example, since the dipping compound must be liquid at room temperature. More critically, the material that is utilized must have a viscosity at a certain range for thickness and film tensile strength optimization. Using the cutting and sealing approach, the film forming extrusion process could be produced but not limited to blowing, casting or calendaring.

[0035] Biaxial orientation is a process whereby a plastic film or sheet is stretched in such a way that the polymeric chains are oriented parallel to the plane of the film in two directions. Biaxially oriented films exhibit exceptional clarity, very high tensile properties, improved flexibility and toughness, improved barrier properties, and can be relatively easily made shrinkable.

[0036] It is our finding that the TPE films made for high elasticity and low deformation are very anisotropic and properties such as tensile strength and elongation in machine direction and transverse direction are much different. We found that through biaxial orientation, the properties, such as tensile and tear strength are improved overall.

DESCRIPTIONS OF FIGURES

[0037] FIG. 1 is a view of panels 10A and 10B welded together to form a weld seam 12. In preparation for the welding process, a die platen is preheated prior to cutting and sealing panel 10A and panel 10B together.

[0038] FIG. 2 is a side view of joined panels (10A and 10B) of FIG. 1 with weld seam (12). FIG. 2 shows eversion of film layers (10A) and (10B) at weld seam (12). Weld seam (12) has substantially complete continuity and integrity and is without pinholes, holidays or charred edges.

[0039] FIG. 3 is a TPE glove (20) comprised of TPE panels (top panel 24A and bottom panel 24B) joined at weld seam (22). Weld seam (22) is located at the finger contours of glove (20) where the two film layers are joined. The preheated die platen takes on the shape of the TPE product to be created, in this case, the shape of a hand. The top panel 24A is placed on top of the bottom panel 24B. A preheated die platen is lowered from above and brought into contact with these panels under pressure at the welding peripheries to create weld seam (22). The preheated die platen could take the shape of either a left hand or a right hand. Since the glove can be flipped over after the cutting and sealing process, it is necessary to define which panel is the top panel and which one is the bottom panel. For the purpose of the claim interpretation, “top panel” and “bottom panel” are defined according to their relative locations (top vs bottom) during the cutting and sealing process.

EXAMPLES

[0040] The following examples would illustrate the present invention as compared to a prior art glove using polyvinyl chloride (PVC) in the dipping process as well as the prior art glove produced by polyethylene (PE) using the cutting and sealing process.

Example 1

[0041] The top and bottom panels are made from the same single layer film. In this example, the film is made from a TPE comprising an SIS and a PE. The SIS has a styrene content of 18% by weight.

[0042] It is clear from Table 3 that the performance of this TPE as a glove material is excellent. It has equal or better elasticity than the industrial standard Nitrile glove material. The glove made from this TPE is very soft with a Shore A hardness of 59 and is very comfortable to wear. As it is a thermoplastic material, it can be recycled and re-used. In fact, the dropoff material from cutting the hand shaped panels is reused in making the film. The process in making the film and glove does not generate any toxic material, thus making it a truly environment-friendly process. The PE in this example may be a low density polyethylene (LDPE), a linear low density polyethylene (LLDPE), a Medium density polyethylene (MDPE), or a High density polyethylene (HDPE).

Example 2

[0043] The top and bottom panels are made from the same single layer film based on SEBS. The SEBS has 12% to 25% (inclusive) styrene content by weight in the SBC molecular structure of the elastomer. Note again the deformation after 100% stretch is less than 10%.

Example 3

[0044] The top and bottom panels are made from the same single layer film based on SIS and SEBS. It is found that mixing SIS and SEBS gives good balance of softness, recovery and tensile strength resulting a comfortable and strong form fitting glove.

[0045] To produce gloves with highly desired properties, the Melt Flow Indices of the top and bottom panels are preferably from 0.5 g/10 mins to 10 g/10 mins according to ASTM Test D1238 at 190 C and at a load of 2.16 kg, and the hardness of the panels is preferably in the range of 35 Shore A to 90 Shore A, and most preferably in the range of 50 Shore A to 80 Shore A.

Example 4

[0046] The top and bottom panels are made from the same single layer film based on SBS and SEBS. In particular, the film is made from a mixture containing at least one SBS and at least one SEBS. The SBS is the lowest cost SBC and we found its use together with SEBS is synergistic and advantageous in cost control and performance.

[0047] The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the invention. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the invention. In other instances, well known devices are shown in block diagram form in order to avoid unnecessary distraction from the underlying invention. Thus, the foregoing descriptions of specific embodiments of the present invention are presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously many modifications and variations are possible in view of the above teachings. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, the thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.

Tables

[0048]

TABLE-US-00001 TABLE 1 Typical Properties of PVC, NRL, Nitrile and PE Gloves Material PVC NRL Nitrile PE Manufacturing Method Dipping Dipping Dipping Welding Tensile Strength 11-15 18-25 20-40 11-15 (MPA) Elongation (%) 300-400 ~800 ~600 ~600 Deformation after  8-16 ~5  5-10 >30 100% stretch (%) Thickness range (mm) 0.06-0.1  0.08-0.12 0.06-0.12 0.01-0.02 Weight (gram) >5 >5 >4 <2

TABLE-US-00002 TABLE 2 Properties of TPE of Example 1 Properties Unit Value Test Method Hardness Shore A 59 10 Sec; ASTM 2240 Tensile Strength MPa 18.3 ASTM D882 Elongation % 852 ASTM D882 Deformation after % 2.5 Per U.S. Pat. No. 100% stretch 8,572,765 Thickness mm 0.05

TABLE-US-00003 TABLE 3 Properties of TPE of Example 2 Properties Unit Value Test Method Hardness Shore A 78 10 Sec; ASTM 2240 Tensile Strength MPa 26.5 ASTM D882 Elongation % 556 ASTM D882 Deformation after % 8.8 Per U.S. Pat. No. 100% stretch 8,572,765 Thickness mm 0.06

TABLE-US-00004 TABLE 4 Properties of TPE of Example 3 Properties Unit Value Test Method Hardness Shore A 76 10 Sec; ASTM 2240 Tensile Strength MPa 22.4 ASTM D882 Elongation % 778 ASTM D882 Deformation after % 6.3 Per U.S. Pat. No. 100% stretch 8,572,765 Thickness mm 0.06

TABLE-US-00005 TABLE 5 Properties of TPE of Example 4 Properties Unit Value Test Method Hardness Shore A 56 10 Sec; ASTM 2240 Tensile Strength MPa 15.0 ASTM D882 Tensile Elongation % 920 ASTM D882 Deformation after % 9.0 Per U.S. Pat. No. 100% stretch 8,572,765 Thickness mm 0.08