CN111227398A

CN111227398A - Glove having uniform thickness and method of making same

Info

Publication number: CN111227398A
Application number: CN201911022520.1A
Authority: CN
Inventors: 黄忠万; 林秀娟; 诺拉妮莎·宾蒂·艾哈迈德·大卫; 刘铭来
Original assignee: Top Glove International Sdn Bhd
Current assignee: Top Glove International Sdn Bhd
Priority date: 2018-11-28
Filing date: 2019-10-25
Publication date: 2020-06-05
Also published as: MY191664A

Abstract

Gloves having a uniform thickness and methods of making the same. A multi-layer glove comprising two latex layers, wherein the two latex layers are a first latex layer and a second latex layer, wherein the first latex layer covers a fingertip to palm area, wherein the first latex layer has a total solids content of 4% to 25%, wherein the second latex layer covers a fingertip to wrist area, wherein the second latex layer has a total solids content of 15% to 40%, wherein the first latex layer is selected from the group consisting of nitrile butadiene rubber, neoprene rubber, polyisoprene rubber, natural rubber, and mixtures thereof, and wherein the second latex layer is selected from the group consisting of nitrile butadiene rubber, neoprene rubber, polyisoprene rubber, natural rubber, and mixtures thereof.

Description

Glove having uniform thickness and method of making same

Technical Field

The present invention relates to gloves and methods of making the same, and more particularly to multi-layer gloves and methods of making the same. The multilayer glove has a uniform thickness from the fingertips to the wrist and has unique characteristics in designated areas.

Background

Conventional glove manufacturing processes involve a dipping (nipping) process in which the fingertip area (fingertip) and palm area have a longer residence time in the latex tank than the wrist area. In brief, the fingertip region is immersed first and removed last, while the wrist region is immersed last and removed first.

In view of the above, conventional gloves occasionally have a high thickness gradient, with the latex film being thinnest in the wrist area and thickest in the fingertip area. Gloves with a high thickness gradient are undesirable for the following reasons:

i. a high film thickness in the fingertip region may give a poor tactile sensation to the user; and is

A low film thickness in the wrist region reduces strength and film integrity, resulting in a higher probability of glove tearing during donning.

In addition, conventional dipping processes produce gloves having similar physical properties in both the palm region and the wrist region. For example, neoprene surgical gloves have good flexibility in both the fingertip-to-palm region and the wrist region, while nitrile surgical gloves have good strength in both the fingertip-to-palm region and the wrist region. A disadvantage of conventional dipping methods is that it may not be possible to manufacture gloves that (1) have good flexibility in the fingertip to palm region and (2) have good strength in the wrist region. Low strength in the wrist region increases the risk of tearing of the glove during donning, while high strength (low softness) in the fingertip-to-palm region and wrist region increases the risk of hand fatigue.

Thus, it is apparent from the above disclosure that the existing glove manufacturing methods and gloves made therefrom have their own shortcomings. Accordingly, there is a need for a more advantageous and/or efficient glove manufacturing process that would eliminate the need to manufacture gloves having high thickness gradients and overcome the above-mentioned disadvantages (i.e., hand fatigue after prolonged use and the possibility of tearing during donning) as compared to conventional techniques.

Disclosure of Invention

The invention relates to a multi-layer glove, which comprises two emulsion layers, wherein the two emulsion layers are a first emulsion layer and a second emulsion layer, wherein the first latex layer covers fingertip to palm area, wherein the first latex layer has a total solids content of 4% to 25%, wherein the second latex layer covers fingertip to wrist area, wherein the second latex layer has a total solids content of 15% to 40%, wherein the first latex layer is selected from the group consisting of acrylonitrile butadiene rubber (acrylonitrite rubber), chloroprene rubber (polychloroprene rubber), polyisoprene rubber (polyisoprene rubber), natural rubber and mixtures thereof, and wherein the second latex layer is selected from the group consisting of nitrile rubber, neoprene rubber, polyisoprene rubber, natural rubber and mixtures of these.

The present invention also relates to a method of making a multi-layer glove, the method comprising the steps of: (i) dipping a former (former) in a coagulant solution to coat a coagulant layer on the former, (ii) drying the coagulant layer coated on the former obtained in step (i), (iii) dipping the former obtained in step (ii) in a first latex formulation to produce a first latex layer, (iv) drying the first latex layer coated on the former obtained in step (iii), (v) dipping the former obtained in step (iv) in a second latex formulation to produce a second latex layer, (vi) drying the second latex layer coated on the former obtained in step (v), (vii) treating the second latex layer coated on the former obtained in step (vi) with hot water to leach out chemical residues to form a pre-leached latex film, (viii) (viii) curling the pre-dissolved filtered latex film coated on the mold obtained in step (vii), to form a beaded latex film, (ix) drying the beaded latex film coated on the mold obtained in step (viii), (x) cooling the dried latex film coated on the mold obtained in step (ix), (xi) treating the latex film coated on the mold obtained in step (x) with chlorinated water, to obtain a treated latex film, (xii) treating the treated latex film obtained in step (xi) with hot water to leach out chemical residues, thereby obtaining a post-leaching latex film, (xiii) drying the latex film coated on the mold obtained in step (xii), to produce a multi-layer glove, and (xiv) stripping the multi-layer glove from the former.

Additional aspects, features and advantages of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments thereof, taken in conjunction with the accompanying drawings.

Drawings

The present invention will become more fully understood from the detailed description given herein below and the accompanying drawings given by way of illustration only, and thus not limiting of the present invention, wherein:

in the drawings:

FIG. 1(a) is a flow chart showing the steps involved in making a multi-layer glove using the first method (chlorination process).

FIG. 1(b) is a flow chart showing the steps involved in making a multi-layer glove using the second method (polymer coating method).

FIG. 1(c) is a flow chart showing the steps involved in making a multi-layer glove using a third method (powder coating method).

Fig. 2(a) illustrates a conventional double latex dipping method.

Fig. 2(b) illustrates the double latex impregnation method of the present invention.

Fig. 3(a) illustrates a schematic cross-sectional view of a glove layer prepared using a conventional process.

Fig. 3(b) illustrates another cross-sectional schematic view of a glove layer prepared via a conventional process.

FIG. 3(c) illustrates a schematic cross-sectional view of a glove layer made using the present invention.

Fig. 4(a) illustrates a schematic cross-sectional side view of the finished glove still on the mold.

Fig. 4(b) illustrates a schematic cross-sectional elevation view of the finished glove.

Detailed Description

Detailed descriptions of preferred embodiments of the invention are disclosed herein. However, it is to be understood that the described embodiments are merely exemplary of the invention, which can be embodied in various forms. Therefore, the details disclosed herein are not to be interpreted as limiting, but merely as the basis for the claims and as a teaching one skilled in the art to which this invention pertains. The numerical data or ranges used in the specification should not be construed as limiting.

The present invention relates to gloves and methods of making the same, and more particularly, to multi-layer gloves and methods of making the same, the multi-layer gloves including at least two latex layers, preferably two latex layers, namely, a first latex layer and a second latex layer. The first latex layer is selected from the group consisting of Nitrile Butadiene Rubber (NBR), neoprene rubber (CR), polyisoprene rubber (PI), Natural Rubber (NR), and mixtures of these rubbers. The second latex layer is selected from the group consisting of NBR, CR, PI, NR and mixtures of these rubbers.

Also, the first latex layer covers the fingertip to palm area of the glove. In addition, the second latex layer covers the fingertip to wrist region of the glove. Thus, the first latex layer will be completely covered by the second latex layer, as shown in fig. 3(c) and fig. 4(a) and 4 (b). The multi-layer glove may be an examination glove or a surgical glove. The multi-layered glove of the present invention has a uniform thickness from the fingertip to the wrist region. In addition to the above, the multilayer glove can be extended for use in the manufacture of household gloves and industrial gloves.

The thickness of the multilayer glove is 0.03mm to 0.30mm, preferably 0.09mm to 0.11 mm. The multi-layered glove of the present invention has unique properties in different designated areas, wherein the fingertip to palm area exhibits soft and elastic properties, and wherein the wrist area exhibits high strength properties. The fingertip to palm region is designed to have soft and elastic properties to provide comfort to the user, especially in the finger and palm regions. For the purposes of the present invention, the terms "finger" and "fingertip" include the thumb.

For the purposes of the present invention, two different latex combined formulations/conditions (i.e., a soft formulation and a strong/hard formulation) are used to prepare two latex layers (a first latex layer and a second latex layer). For example, in order to be able to obtain a good softness in the fingertip to palm area, the first latex layer has a tensile strength of 5MPa to 20MPa, an elongation at break of 600% to 1000% and a stress at 500% elongation (modulus) of 1MPa to 15MPa, prepared from a soft combination formulation.

Second, in order to be able to obtain good/high strength at the wrist, the second latex layer has a tensile strength of 20MPa to 35MPa, an elongation at break of 400% to 800% and a 500% tensile stress of 15MPa to 35MPa, which are prepared by a strong/hard combination formulation. The wrist region is designed to have high strength properties to prevent tearing when the glove is worn.

Thus, for the purposes of the present invention, the two latex layers refer to two regions, each having a unique composition and characteristics. More specifically, the two layers are not two distinct peelable layers, but rather are a single layer having two distinct regions having distinct compositions and characteristics, wherein the first latex layer is the first region, and wherein the second latex layer is the second region. The first region covers the fingertip to palm region and the second region covers the fingertip to wrist region.

The multi-layer glove of the present invention (as described above) is prepared by modifying the methods generally known in the glove manufacturing industry. The method comprises the following steps:

i. (ii) dipping a mould into a coagulant solution to coat a coagulant layer (100) on said mould, wherein washing is performed before using the mould in step (i);

drying (101) the coagulant layer coated on the mold obtained in step (i);

dipping the former obtained in step (ii) into a first latex formulation to make a first latex layer (102), wherein the first latex layer covers the fingertip to palm area;

drying (103) the first latex layer coated on the former obtained in step (iii);

v. dipping the former obtained in step (iv) into a second latex formulation to make a second latex layer (104), wherein the second latex layer covers the fingertip to wrist area;

drying (105) the second latex layer coated on the former obtained in step (v);

(vii) treating the second latex layer coated on the former obtained in step (vi) with hot water to leach out chemical residues, thereby forming a pre-leached latex film (106);

crimping the pre-filtered latex film coated on the mold obtained in step (vii) to form a crimped latex film (107);

drying (108) the beaded latex film coated on the mold obtained in step (viii);

cooling (109) the dried latex film coated on the mold obtained in step (ix);

treating the latex film coated on the mold obtained in the step (x) with chlorine water to obtain a treated latex film (110);

treating the treated latex film obtained in step (xi) with hot water to leach out chemical residues, thereby obtaining a post-leached latex film (111);

drying the latex film coated on the former obtained in step (xii) to produce a multi-layer glove (112); and

stripping the multilayer glove (113) from the mold.

Referring to the drawings, FIG. 1(a) is a flow chart showing the steps involved in making a multi-layer glove. The method comprises a first step of: immersing a mold in a coagulant solution at a temperature between 40 ℃ and 65 ℃ for a period of 4 seconds to 30 seconds to coat a coagulant layer (100) on the mold. The coagulant solution comprises: a release agent, an anti-sticking agent, calcium salt, a wetting agent and water.

The release or antiblocking agent is selected from the group consisting of calcium stearate, potassium stearate, zinc stearate or mixtures of these, preferably calcium stearate or potassium stearate or mixtures thereof. The coagulant solution contains 0.8 to 2% by weight of a mold release agent and an antiblocking agent. The calcium salt is selected from calcium nitrate or calcium chloride or a mixture thereof, preferably calcium nitrate.

The coagulant solution contains 3 to 20% by weight of calcium salt. The wetting agent is any alcohol ethoxylate. The ethanol ethoxylate is at least one or more of Polyoxyethylene (POE), polyoxyethylene glycol alkyl ether, Triton X-100, and polyoxyethylene glycol octylphenol ester. The coagulant solution contains 0.05% to 0.2% by weight of a wetting agent. The remainder of the coagulant solution is water. The molds are first subjected to washing prior to immersing the molds in the coagulant solution.

The washing step comprises treating the molds in an acidic solution and then rinsing the molds in purified water. The concentration of the acidic solution is 0.5% to 4.0%, and the treatment with the acidic solution is performed at a temperature of 50 ℃ to 70 ℃ for a period of 6 seconds to 30 seconds. The acidic solution is selected from the group consisting of any one or mixture of inorganic acids, any mixture of organic and inorganic acids, or any combination thereof with added surfactants and/or additives.

Then, the mold is treated with an alkaline solution to neutralize the acid, and then the mold is rinsed in clean water. The concentration of the alkaline solution is 0.5% to 8.0%, and the treatment with the alkaline solution is performed at a temperature of 50 ℃ to 70 ℃ for a period of 6 seconds to 30 seconds. The alkaline solution is selected from the group consisting of sodium hydroxide, potassium hydroxide or a mixture of these or any of said mixtures with added hypochlorite, surfactants, builders (builder) and/or additives.

Next, the mold is directed to brushing to remove dirt and/or greasy stains. The brushing step helps to remove any remaining coagulant residue on the mold surface (which is likely from a previous impregnation cycle). For the purposes of the present invention, the term "clean water" refers to, but is not limited to, municipal water supplies. Thereafter, the mold is immersed in a container containing a coagulant solution to coat the coagulant layer on the mold. The coagulant layer coated on the mold is then dried (101) in a heating chamber such as, but not limited to, an oven at a temperature between 80 ℃ and 300 ℃ for a period of time between 1 minute and 10 minutes.

The coagulant layer coated former is dipped into a container containing the first latex formulation at a temperature between 20 c and 40 c for a period of 4 seconds to 30 seconds to form a first latex layer (102), as shown in fig. 3 (c). The first latex layer covers the fingertip to palm area of the glove to be manufactured. The first latex formulation is selected from the group consisting of Nitrile Butadiene Rubber (NBR), neoprene rubber (CR), polyisoprene rubber (PI), Natural Rubber (NR), and mixtures of these.

The first latex layer coated on the former is dried (103) in a heated chamber such as, but not limited to, an oven at a temperature between 80 ℃ and 150 ℃ for a period of time between 20 seconds and 5 minutes. The first latex layer coated former is then dipped into a container containing the second latex formulation at a temperature between 20 ℃ and 40 ℃ for 4 seconds to 30 seconds to form a second latex layer (104). The second latex layer covers the fingertip to wrist region of the glove to be manufactured, as shown in fig. 3 (c). The second latex formulation is selected from the group consisting of NBR, CR, PI, NR, and mixtures of these. The second latex layer coated on the former is dried (105) in a heated chamber such as, but not limited to, an oven at a temperature between 80 ℃ and 300 ℃ for a period of time between 20 seconds and 5 minutes.

For the purposes of the present invention, the two latex layers are referred to as two regions, each having a unique composition and characteristics. More specifically, the two layers are not two distinct peelable layers, but rather are a single layer having two distinct regions having distinct compositions and characteristics, wherein the first latex layer is the first region, and wherein the second latex layer is the second region. The first region covers the fingertip to palm region and the second region covers the fingertip to wrist region.

Hereinafter, the duration of immersing the former in the container containing the coagulant solution, the first latex formulation, and the second latex formulation is referred to as "residence time". The residence time for all three phases is between 4 and 30 seconds, preferably between 4 and 20 seconds for the preparation of examination gloves and between 6 and 25 seconds for the preparation of surgical gloves. 6 to 25 seconds are ensured in order to prepare a multi-layered glove having a uniform thickness from the fingertip to the wrist area, i.e. having a thickness of 0.03 to 0.30mm, preferably 0.09 to 0.11 mm.

In addition, the concentration of calcium nitrate in the coagulant solution and the total solids content of both the first latex formulation and the second latex formulation were also optimized to obtain a multi-layered glove having a uniform thickness, see table 1. Table 1 summarizes the chemical parameters, concentration ranges, residence times, and impregnation levels for all three stages. For the purposes of the present invention, multilayer gloves having a uniform thickness from the fingertip to the wrist region were prepared under the following conditions:

i. the first latex layer is obtained by using a shorter residence time (but ensuring between 4 and 30 seconds) and a lower Total Solids Content (TSC) with respect to the latex formulation. This action reduces the calcium nitrate concentration on the mold from the fingertip to the palm area. Forming a film as a first latex layer;

the second latex layer was obtained by using a longer residence time (but ensuring between 4 and 30 seconds and longer than the residence time for the preparation of the first latex layer) and a higher TSC with respect to the latex formulation. This action produces a thinner membrane from the fingertips to the palm area and a thicker membrane in the wrist area, resulting in a second latex layer; and

as a result of combining the two layers together, a uniform thickness from the fingertip to the wrist region can be achieved.

Table 1: chemical parameters, concentration ranges, residence times and impregnation levels of the three impregnation stages

TSC% means the percentage of the total solids content in the respective formulation

Next, the second latex layer coated on the former is treated with hot water at a temperature between 40 ℃ and 80 ℃ (by dipping the second latex layer coated on the former into a container containing hot water) for a period of 20 seconds to 5 minutes to leach out chemical residues, thereby forming a pre-leached latex film (106). This step is referred to as the pre-leaching step, which is performed to remove chemical residues used prior to the pre-leaching step, such as additives, calcium-based compounds (i.e., calcium nitrate), and ionic surfactants (i.e., Sodium Dodecyl Benzene Sulfonate (SDBS)).

The next step is to crimp the pre-leached latex film coated on the mold by a rolling mechanism using conventional means such as, but not limited to, a crimping brush or a crimping blanket to form a crimped latex film (107). The beaded latex film coated on the former is dried in a heated chamber such as, but not limited to, an oven at a temperature between 80 c and 200 c to initiate the vulcanization process (108) for a period of time between 8 minutes and 60 minutes.

After the vulcanization process, the latex film coated on the mold is allowed to cool (109) at a temperature between 40 ℃ and 80 ℃ for a period of 15 seconds to 3 minutes. Then, the latex film coated on the former is treated with chlorine water at room temperature by immersing the latex film coated on the former in a container containing chlorine water at a concentration of 400ppm to 1500ppm for a duration of 10 seconds to 60 seconds to obtain a treated latex film (110). This step is called a chlorination step, which is performed to harden the surface of the glove, thereby creating a fine texture and making the glove easy to wear. Thus, the treated latex film is subjected to a hot water treatment (by immersing the treated latex film in a container containing hot water) at a temperature of 40 ℃ to 90 ℃ for a period of 20 seconds to 5 minutes to leach out chemical residues, thereby obtaining a post-leached latex film (111).

The step of leaching out the chemical residue is referred to as a post-leaching step, which is performed to remove chemical residues such as chlorine water residue, additives, calcium-based compounds (i.e., calcium nitrate), ionic surfactants (i.e., sodium dodecylbenzene sulfonate (SDBS)), and latex proteins. Followed by drying the latex film coated on the former in a heated chamber such as, but not limited to, an oven at a temperature between 80 ℃ and 300 ℃ for a period of time between 20 seconds and 5 minutes to produce a multi-layered glove (112) as a final product. Finally, the multi-layer glove (113) is peeled from the mold.

Alternatively, the above-described steps for making the multi-layer glove of the present invention may be modified by introducing a polymer coating step after the pre-leaching step to obtain a polymer-coated latex film (106 a). The polymer coating step is performed by applying a thin coating of polymeric material onto a pre-dissolved filtered latex film coated on a former. The pre-filtered latex film coated on the former is dipped into a container containing the polymeric material at a temperature of 25 c to 45 c for a period of 6 seconds to 30 seconds.

The polymeric material is selected from acrylic or polyurethane polymer dispersions or mixtures thereof. This step is performed to reduce and/or eliminate stickiness. In addition, the polymer coating serves as a barrier to prevent direct contact with the latex layer. Further, this step eliminates the cooling step (109) and the chlorination step (110). Thus, after the polymer coating step (106a), the polymer-coated latex film follows the following steps: crimping (107), drying (108), post-leaching (111), drying (112) and peeling (113) to obtain a multilayer glove, as shown in fig. 1 (b).

Further alternatively, the above-described steps for producing the multi-layered glove of the present invention may be modified by introducing a powder material coating step after the post-leaching step to obtain a powder-coated latex film (111 a). The powdered material coating step is performed by applying a thin coating of powdered material, which is any one selected from the group consisting of corn starch, calcium carbonate and calcium stearate, on the post-leaching latex film coated on the mold. The post-leached latex film coated on the former is immersed in a container containing a solution of corn starch at a temperature of 30 ℃ to 60 ℃ for a period of 6 seconds to 30 seconds.

This step eliminates the cooling step (109) and the chlorination step (110). Thus, after the powdered material coating step (111a), the powder-coated latex film follows the following steps: drying (112) and peeling (113) to obtain a multilayer glove, as shown in fig. 1 (c). The multi-layer glove may be an examination glove or a surgical glove. In addition to the above, the multilayer glove can be extended for use in the manufacture of household gloves and industrial gloves.

The following examples are constructed to illustrate the invention in a non-limiting sense.

Multi-layer glove

The multi-layer glove comprises two latex layers,

wherein the two latex layers are a first latex layer and a second latex layer, wherein,

the first latex layer covering a fingertip-to-palm region, wherein the first latex layer has a total solids content of 4% to 25%,

wherein the second latex layer covers fingertip to wrist area, wherein the second latex layer has a total solids content of 15% to 40%,

wherein the first latex layer is selected from the group consisting of NBR, CR, PI, NR and mixtures of these and

wherein the second latex layer is selected from the group consisting of NBR, CR, PI, NR, and mixtures of these.

Fig. 3(a) shows different latexes used at different layers (outside and inside), fig. 3(b) shows different latexes blended and used as a single layer, and fig. 3(c) shows different latexes combined at designated areas to make a glove. Fig. 3(a) and 3(b) show a conventional glove, while fig. 3(c) shows a glove of the present invention. Fig. 4(a) shows a side view of the multilayer glove still on the mold, and fig. 4(b) shows a front view of the multilayer glove peeled off the mold. In fig. 4(a) and 4(b), the first latex layer (200) and the second latex layer (201) are labeled for ease of viewing. The multi-layer glove may be an examination glove or a surgical glove.

Preparation of multilayer gloves：

The process for making a multi-layer glove (as described above) includes the steps of:

i. (ii) immersing a former in a coagulant solution at a temperature between 40 ℃ and 65 ℃ for a period of 4 seconds to 30 seconds to coat a coagulant layer (100) on the former, wherein washing is performed before using the former for step (i), and wherein the coagulant solution comprises: a release agent, an anti-sticking agent, calcium salt, a wetting agent and water;

drying (101) the coagulant layer coated on the mold obtained in step (i) at a temperature between 80 ℃ and 300 ℃ for a period of time comprised between 1 minute and 10 minutes;

(iii) immersing the former obtained in step (ii) in a first latex formulation at a temperature between 20 ℃ and 40 ℃ for a period of 4 seconds to 30 seconds to produce a first latex layer (102), wherein the first latex layer covers the fingertip to palm area, and wherein the first latex layer has a total solids content of 4% to 25%;

(iv) drying (103) the first latex layer coated on the former obtained in step (iii) at a temperature of 80 ℃ to 150 ℃ for a period of 20 seconds to 5 minutes;

(iv) dipping the former obtained in step (iv) into a second latex formulation at a temperature between 20 ℃ and 40 ℃ for a period of 4 seconds to 30 seconds to produce a second latex layer (104), wherein the second latex layer covers the fingertip to wrist region and wherein the second latex layer has a total solids content of 15% to 40%;

(vi) drying (105) the second latex layer coated on the former obtained in step (v) at a temperature between 80 ℃ and 300 ℃ for a period of time comprised between 20 seconds and 5 minutes;

(vii) treating the second latex layer obtained in step (vi) coated on the former with hot water at a temperature between 40 ℃ and 80 ℃ for a period of 20 seconds to 5 minutes to leach out chemical residues, thereby forming a pre-leached latex film (106);

(viii) crimping the pre-leached latex film coated on the mold obtained in step (vii) to form a crimped latex film (107);

(ix) drying (108) the beaded latex film coated on the mold obtained in step (viii) at a temperature between 80 ℃ and 200 ℃ for a period of time comprised between 8 minutes and 60 minutes;

cooling the dried latex film coated on the former obtained in step (ix) to a temperature (109) between 40 ℃ and 80 ℃ for a period of time between 15 seconds and 3 minutes;

treating the latex film coated on the mold obtained in step (x) with chlorine water at ambient temperature for a period of 10 seconds to 60 seconds to obtain a treated latex film (110);

treating the treated latex film obtained in step (xi) with hot water at a temperature of 40 ℃ to 90 ℃ for a time period of 20 seconds to 5 minutes to leach out chemical residues, thereby obtaining a post-leached latex film (111);

drying the latex film coated on the former obtained in step (xii) at a temperature of 80 ℃ to 300 ℃ for a period of 20 seconds to 5 minutes to produce a multi-layered glove (112); and

stripping the multilayer glove from the mold for donning (113);

wherein the first latex layer is selected from the group consisting of NBR, CR, PI, NR and mixtures thereof, wherein the second latex layer is selected from the group consisting of NBR, CR, PI, NR and mixtures thereof, and wherein the steps of immersing in the coagulant solution, immersing in the first latex formulation and immersing in the second latex formulation are preferably performed with a residence time of 4 to 20 seconds for the preparation of the examination glove and a residence time of 6 to 25 seconds for the preparation of the surgical glove.

For the purposes of the present invention, the two latex layers are referred to as two zones, each having a unique composition and characteristics. More specifically, the two layers are not two distinct peelable layers, but rather are a single layer having two distinct regions having distinct compositions and characteristics, wherein the first latex layer is the first region, and wherein the second latex layer is the second region. The first region covers the fingertip to palm region and the second region covers the fingertip to wrist region.

Fig. 2(a) shows a conventional double latex dipping method, and fig. 2(b) shows a double latex dipping method of the present invention. The thickness gradient of the multilayer gloves made using the method of the present invention was verified and compared to gloves made using a conventional double latex dipping method.

Table 2a and table 2b show the thickness gradient of both the prepared multilayer gloves (surgical gloves and examination gloves, respectively) and the conventional gloves.

Table 2 a: thickness gradient of the multilayer surgical glove of the present invention and thickness gradient of conventional surgical gloves

Table 2 b: thickness gradient of multilayer inspection glove of the present invention and thickness gradient of conventional inspection glove

The above table demonstrates that the thickness of the multi-layered glove made using the present invention is more uniform from the fingertip to the wrist area than conventional gloves. Based on this table, it is notable that the thickness gradient of the multilayer examination glove of the present invention is slightly thicker (about 0.03) than the thickness gradient of the multilayer surgical glove of the present invention. However, this difference is due to the examination glove having a textured surface in the finger region. Importantly, the thickness gradient of the multi-layered examination glove of the present invention is reduced by half as compared to conventional examination gloves.

Next, the physical properties of the multi-layer glove of the present invention were tested. The test requires placing a dumbbell specimen between the palm and wrist areas of the glove. Table 3 shows the physical properties of the multi-layer glove made using the method of the present invention compared to the physical properties of the glove made using the conventional double latex dipping method.

Table 3: comparison of physical Properties of the Multi-layer glove of the present invention with those of conventional gloves

Generally, the strength of a glove is proportional to its film thickness, e.g., the higher the film thickness, the higher the strength of the glove. Higher glove strength can be observed from a comparison of group 2 to group 3. Further, by making the thickness of the wrist region larger, the strength of the glove can be improved. These two factors are taken into account in making the multi-layer glove of the present invention, thereby producing a lightweight and strong glove (see comparison between group 1 and group 3). Table 4 shows different latex combinations for making the multi-layer glove of the present invention.

Table 4: latex compositions for making the multi-layer gloves of the present invention

Sample(s)

1

2

3

4

5

6

Latex 1 (first latex layer)

NBR

CR

PI

NR

CR-NBR

Latex 2 (second latex layer)

NBR

NR

CR-NBR

As can be seen from Table 4, the same or different latexes can be used to make the multi-layer glove using the methods discussed herein. For example, latex with soft and elastic properties may be used in the palm area to provide good comfort for the user. While latex with higher strength characteristics may be used in the wrist area to prevent tearing during wear. By preparing different combination formulations (i.e., soft and strong/hard formulations), the same latex can be used to provide both soft and elastic properties as well as higher strength properties. The different combination formulas will ensure that the user experiences (1) comfort in the palm area and (2) good strength in the wrist area to prevent tearing during wear.

For example, in order to be able to obtain a good softness in the fingertip to palm area, the first latex layer has a tensile strength of 5MPa to 20MPa, an elongation at break of 600% to 1000% and a stress at 500% of 1MPa to 15MPa, prepared from a soft combination formulation. Secondly, in order to be able to obtain good/high strength at the wrist, the second latex layer has a tensile strength of 20MPa to 35MPa, an elongation at break of 400% to 800% and a 500% tensile stress of 15MPa to 35MPa prepared from a strong/hard combination formulation. The latex formulations used to prepare the multi-layer gloves of the present invention using the soft and strong/hard formulations (according to the combinations described in table 4) are described in detail below:

NBR-NBR latex

NR-NR latex

NR-NBR latex

CR-NBR latex

CR & NBR blend-CR & NBR blend latex

The mechanical properties of the multi-layer glove of the present invention (i.e., tensile strength, elongation (%), stress at elongation at 500%, and force to break (N)) were tested according to standard ASTM and EN test methods. Table 5 shows the mechanical properties of the multi-layer glove made using the method of the present invention compared to the mechanical properties of the glove made using the conventional double latex dipping method.

Table 5: comparison of the mechanical Properties of the Multi-layer glove of the present invention with those of conventional gloves

The multi-layer glove of the present invention is prepared using a first latex layer having properties of high elasticity and good flexibility (i.e., fingertip to palm region) and a second latex layer having properties of high strength (i.e., fingertip to wrist region). Thus, the multi-layer glove of the present invention has good comfort in the palm region and good strength in the wrist region, as is apparent from the groups 1 to 6 in Table 5 (i.e., six kinds of surgical gloves of NBR-NBR, CR-NBR, PI-NBR, NR-NR, and CR & NBR-CR & NBR).

In general, multilayer gloves made with the present invention have negligible/much smaller thickness gradient measures and seek to overcome the disadvantages of the conventional techniques by ensuring that the multilayer gloves have low hand fatigue after prolonged use and low likelihood of tearing during donning.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, a description in the singular may be intended to include the plural unless the context clearly indicates otherwise. The terms "comprises," "comprising," and "having" are intended to be inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

The method steps, processes, and operations described herein do not have to be performed in the particular order discussed or illustrated herein, unless an order of performance is specifically indicated. It will also be appreciated that additional or alternative steps may be employed. The use of the expression "at least" or "at least one" implies the use of one or more elements, as such use may achieve one or more of the desired objectives or results in one of these embodiments.

Claims

1. A multi-layered glove comprising two latex layers, wherein the two latex layers are a first latex layer and a second latex layer, wherein the first latex layer covers a fingertip to palm area, wherein the first latex layer has a total solids content of 4% to 25%, wherein the second latex layer covers a fingertip to wrist area, wherein the second latex layer has a total solids content of 15% to 40%, wherein the first latex layer is selected from the group consisting of nitrile rubber, neoprene rubber, polyisoprene rubber, natural rubber, and mixtures of these rubbers, and wherein the second latex layer is selected from the group consisting of nitrile rubber, neoprene rubber, polyisoprene rubber, natural rubber, and mixtures of these rubbers.

2. The multi-layered glove of claim 1, wherein the first latex layer has a tensile strength of 5MPa to 20MPa, an elongation at break of 600% to 1000%, and a 500% tensile stress of 1MPa to 15 MPa.

3. The multi-layered glove of claim 1, wherein the second latex layer has a tensile strength of 20 to 35MPa, an elongation at break of 400 to 800%, and a 500% tensile stress of 15 to 35 MPa.

4. The multi-layered glove of claim 1, wherein the multi-layered glove has a thickness range of 0.03mm to 0.30 mm.

5. A method of making a multi-layer glove, the method comprising the steps of:

i. immersing a mold in a coagulant solution at a temperature between 40 ℃ and 65 ℃ for a period of time between 4 seconds and 30 seconds to coat a coagulant layer (100) on the mold;

drying the coagulant layer coated on the mold obtained in step (i) at a temperature between 80 ℃ and 300 ℃ for a period of time between 1 minute and 10 minutes (101);

(iii) immersing the former obtained in step (ii) in a first latex formulation at a temperature between 20 ℃ and 40 ℃ for a period of 4 seconds to 30 seconds to produce a first latex layer (102);

(iv) drying the first latex layer coated on the former obtained in step (iii) at a temperature of 80 ℃ to 150 ℃ for a period of 20 seconds to 5 minutes (103);

v. immersing the former obtained in step (iv) in a second latex formulation at a temperature between 20 ℃ and 40 ℃ for a period of 4 seconds to 30 seconds to produce a second latex layer (104);

(vi) drying the second latex layer coated on the former obtained in step (v) at a temperature between 80 ℃ and 300 ℃ for a period of time between 20 seconds and 5 minutes (105);

(vii) treating the second latex layer coated on the former obtained in step (vi) with hot water at a temperature between 40 ℃ and 80 ℃ for a period of 20 seconds to 5 minutes to leach out chemical residues, thereby forming a pre-leached latex film (106);

(ix) drying the beaded latex film coated on the mold obtained in step (viii) at a temperature between 80 ℃ and 200 ℃ for a period of time between 8 minutes and 60 minutes (108);

cooling the dried latex film coated on the former obtained in step (ix) to a temperature between 40 ℃ and 80 ℃ for a period of 15 seconds to 3 minutes (109);

treating the treated latex film obtained in step (xi) with hot water at a temperature of 40 ℃ to 90 ℃ for a period of 20 seconds to 5 minutes to leach out chemical residues, thereby obtaining a post-leached latex film (111);

stripping the multilayer glove (113) from the mold.

6. The method of making a multi-layered glove according to claim 5, wherein the coagulant solution comprises: a release agent, an anti-sticking agent, calcium salt, a wetting agent and water.

7. The method of making a multi-layered glove of claim 5, wherein the first latex layer covers fingertip to palm area, and wherein the first latex layer has a total solids content of 4% to 25%.

8. The method of making a multi-layered glove of claim 5, wherein the second latex layer covers fingertip to wrist regions, and wherein the second latex layer has a total solids content of 15% to 40%.

9. The method of making a multi-layer glove of claim 5, wherein the first latex layer is selected from the group consisting of nitrile rubber, neoprene rubber, polyisoprene rubber, natural rubber, and mixtures of these rubbers.

10. The method of making a multi-layer glove of claim 5, wherein the second latex layer is selected from the group consisting of nitrile rubber, neoprene rubber, polyisoprene rubber, natural rubber, and mixtures of these rubbers.

11. The method of making a multi-layered glove of claim 5 or 9, wherein the first latex layer is made from a latex combination process resulting in a latex layer having a tensile strength of 5MPa to 20MPa, an elongation at break of 600% to 1000%, and a 500% tensile stress of 1MPa to 15 MPa.

12. The method of making a multi-layered glove of claim 5 or 10, wherein the second latex layer is made from a latex combination process resulting in a latex layer having a tensile strength of 20MPa to 35MPa, an elongation at break of 400% to 800%, and a 500% tensile stress of 15MPa to 35 MPa.

13. The method of making a multi-layer glove of claim 5, wherein the multi-layer glove has a thickness range of 0.03mm to 0.30 mm.