Patent Publication Number: US-2007094767-A1

Title: Powder free vinyl nitrile co-polymer gloves and process for preparing thereof

Description:
BACKGROUND OF THE PRESENT INVENTION  
      1. Field of Invention  
      This invention relates to disposable gloves, and more particularly, relates to disposable gloves used by the healthcare or similar personnel, wherein the disposable gloves are made of vinyl and nitrile copolymer so as to prevent the skin irritation and simultaneously achieve a solid cost saving.  
      2. Description of Related Arts  
      Commonly, a patient examination glove is a disposable device intended for medical purpose that is worn on the hand of healthcare and similar personnel to prevent contamination between healthcare personnel and the patient&#39;s body, fluids, waste or environment.  
      As a result, such gloves are supposed to provide excellent barrier protection and touching comfort. First of all, gloves should offer barrier protection both for the health care worker and the patient to guard against contact with blood, other body fluids, and micro-organisms. In short, people working in a high-risk environment containing blood borne pathogens or hazardous substances should wear good quality gloves.  
      Credited to its distinguished nature, natural rubber latex gloves have been widely used in the foodservice and medical industries for more than 100 years. Natural latex polymers have many advantages in these applications, being strong and highly elastic and having good overall tactile properties. Here, the good tactility refers to have a low deformation stress at ten to five hundred percent elongations and high elastic recovery. On the other hand, a natural latex glove is very comfortable, such that a user is able to slip his hand into the glove quickly and easily.  
      Unfortunately, the nature proteins of latex glove would cause skin irritations to some users. The gloves directed contact with the human skin would result to efflorescence and afflicted itching. There are substantial complaints around the world about the allergic reactions caused by the latex medical gloves. Even worse, not all latex gloves are created equal, there are significant differences between manufacturers and product lines in the amount of free latex protein that can be liberated from the glove and the number and types of chemicals used in glove production. A user would have been hassle to choose a glove from a variety of brands. Moreover, an ideal latex glove should be powder free, very low in extractable latex protein, and have the smallest concentration and the fewest number of residual chemicals from manufacture.  
      As a result, the vinyl gloves have been overwhelmed in the market to replace conventional latex gloves. However, the vinyl gloves have a poor performance in leakage rate with respect to the latex gloves. Latex gloves maintain their integrity longer under in-use conditions. In short, people who choose vinyl gloves would sacrifice on glove comfort, dexterity, and grip because the fit, feel, and elasticity of the synthetic materials differ from natural rubber latex.  
      Alternatively, people began to pay much attention onto other synthetic gloves, such as nitrile and polyurethane gloves that have physical properties similar to natural latex gloves. Compared with vinyl gloves, nitrile gloves are excellent in strength and durability, but vary in softness and flexibility. That is to say, some of the nitrile gloves are comfortable and fit well, whereas some are stiff and not flexible. Polyurethane gloves are soft, flexible and exert virtually no strain on the user hands. Conclusively, the nitrile and polyurethane gloves have much better overall performance compared with the vinyl gloves. They are either good or excellent in barrier protection, strength, durability, elasticity, puncture resistance, and chemical resistance.  
      Seemingly, the medical industry had already found the right materials to manufacture the disposable gloves to replace traditional natural latex gloves. However, disposable glove is a kind of heavily consuming products. Users not only should consider about the risk of allergic sensitization when selecting gloves, but also should take care about the cost issue. The reality is that both of the nitrile and polyurethane gloves are rather expensive, and the latex and vinyl gloves are generally affordable. Users would always be in a dilemma between the costs versus quality.  
      It is highly desirable to develop a new type of gloves having the advantages of the nitrile and polyurethane gloves, but cheaper in costs to replace the nature latex and vinyl gloves.  
     SUMMARY OF THE PRESENT INVENTION  
      A primary object of the present invention is to provide a vinyl nitrile co-polymer powder free exam glove, which is good in barrier protection, strength, durability, elasticity, puncture resistance, and chemical resistance, with a solid cost saving.  
      Another object of the present invention is to provide a vinyl nitrile co-polymer powder free exam glove, which is not irritating to the human skin.  
      Another object of the present invention is to provide a vinyl nitrile co-polymer powder free exam glove, which is inherited all advantageous characteristics of the nitrile gloves but affordable like a conventional vinyl glove.  
      Another object of the present invention is to provide a vinyl nitrile co-polymer powder free exam glove, which is comfortable like natural latex gloves.  
      Another object of the present invention is to provide a vinyl nitrile co-polymer powder free exam glove, wherein no donning powder would be required to solve the gloves sticking problem.  
      Another object of the present invention is to provide a vinyl nitrile co-polymer powder free exam glove, wherein the glove contains no more than 2 mg powder per glove.  
      Another object of the present invention is to provide a method for manufacturing the above mentioned vinyl nitrile co-polymer powder free exam glove.  
      Accordingly, to achieve above mentioned objects, the present invention provides a glove comprising a thin elastomeric film, the film comprises a co-polymer which is selected from a group consisting of polyvinyl chloride, oil-based liquid nitrile rubber (LNBR), pentanediol diisobutyrate (TXIB), di-isononyl phthalate and calcium zinc stabilizer.  
      Furthermore, the present invention provides a method for preparing a vinyl nitrile co-polymer powder free exam glove, comprising the following steps:  
      a. mixing polyvinyl chloride, oil-based liquid nitrile rubber, pentanediol diisobutyrate, di-isononyl phthalate and a calcium zinc stabilizer according to a predetermined formula to generate a polyvinyl mixture;  
      b. dipping the polyvinyl mixture into a former to form a glove;  
      c. heating the glove at a predetermined temperature for a time of period;  
      d. cooling the glove for a predetermined time of period at a temperature 75° C.; and  
      e. dipping the glove into a hot polyurethane mixture.  
      These and other objectives, features, and advantages of the present invention will become apparent from the following detailed description, the accompanying drawings, and the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a block chart showing the manufacturing process of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
      Referring to  FIG. 1 , a manufacturing method for preparing a co-polymer glove according to a preferred embodiment of the present invention is illustrated. The glove of the present invention is to provide a patient examination glove, which is disposable device intended for medical purpose that is worn on the hand of healthcare and similar personnel to prevent contamination between healthcare personnel and the patient&#39;s body, fluids, waste or environment.  
      Accordingly, the present invention provides a glove comprising a thin elastomeric film, the film comprises a co-polymer which is selected from a group consisting of polyvinyl chloride, oil-based liquid nitrile rubber (LNBR), pentanediol diisobutyrate (TXIB), di-isononyl phthalate and calcium zinc stabilizer.  
      In other words, the present invention provides a disposable glove which is prepared of polyvinyl co-polymer thus inheriting advantageous characteristics of nitrile gloves but in solid cost-saving like vinyl gloves. Therefore, a property test would be crucial for evaluating the gloves prepared by the present invention.  
      It is noted that the vinyl nitrile Co-Polymer Powder Free Exam Gloves meet all the current specifications listed under the American Society for Testing and Materials (ASTM) Specification D-6319-00al for Nitrile Examination Gloves, as showing in following tables.  
                                                  Section 7.5.1/7.5.2                                 Before Accelerated   After Accelerated           Aging   Aging                                             Tensile Strength   15.0 mPa   15.0 mPa           Ultimate Elongation   550%   550%                      
 
      Section 7.4: Physical Dimension Test:  
                               Small, Medium, Large and X-Large: Width,       Length and Thickness (all in mm.)                                                Length                                                 S 220   M 230   L 230   XL 230                       Actual Results   242   245   245   245                                     Width                                     S 80 +/− 10   L 95 +/− 10   L 110 +/− 10   XL 120 +/− 10               Actual   82   97   112   121       Results                 Thickness: Finger: 0.10 Palm: 0.10             
 
      The above results illustrated that the glove prepared by the present invention is inherited excellent physical properties of the nitrile gloves for overcoming the drawbacks of the vinyl gloves.  
      Moreover, the vinyl nitrile Co-Polymer Powder Free Exam Gloves conforms to all ASTM D-6319-00al procedures and FDA 100 ml Water Test. It is noted that the MIL STD 105E-sampling plan is being employed in the above test and the result is shown in following table.  
                                           Items   Related Defects   Inspection Level   AQL                  Water Tightness   Holes   G-1   2.5       Dimensions   Width, Length &amp;   S-2   4.0           Thickness       Physical Properties   Unaged, Aged   S-2   4.0                  
 
      Furthermore, the present invention provides a manufacturing method for preparing the above motioned gloves, comprising the following steps:  
      a. mixing polyvinyl chloride, oil-based liquid nitrile rubber, pentanediol diisobutyrate, di-isononyl phthalate and a calcium zinc stabilizer according to a predetermined formula to generate a polyvinyl mixture;  
      b. dipping the polyvinyl mixture into a former to form a glove;  
      c. heating the glove at a predetermined temperature for a time period;  
      d. cooling the glove for a predetermined time period at a temperature 75° C.; and  
      e. dipping the glove into a hot polyurethane mixture.  
      In the step a, the formers are washed, dried and then dipped in a mixture of polyvinyl chloride (43.2%), oil-based liquid nitrile rubber (LNBR) (13%), pentanediol diisobutyrate (TXIB) (13%), di-isononyl phthalate (30.2%) and calcium zinc stabilizer (0.6%).  
      In the step (b), the formers (molds) are dipped in the polyvinyl mixture. In the step (c), the gloves are run through an oven that will heat the gloves at 205° C. for approximately 5.2 minutes duration. And in the step (d), the gloves are then cooled on-line for 5.6 minutes bringing them to a temperature of 75° C.  
      According to the preferred embodiment of the present invention, the manufacturing method further comprises a step (e) for dipping the gloves into a hot polyurethane mixture so as to coat the glove and replace the need for any donning powder and eliminates the problem of gloves sticking together.  
      Finally, the manufacturing method of the present invention comprises a step (f) for stripping the gloves from the forms. In the step (f), the gloves are further heated in a completed oven; the gloves are stripped from their forms and are tested to meet ASTM D5250-00 ε4  for vinyl examination gloves.  
      In other words, gloves are created by dipping forms (which look like human hands) into liquid mixture which is selected from a group consisting of primarily polyvinyl chloride and oil based liquid nitrile rubber. Afterwards, the gloves are hardened through an oven that will heat the gloves at 205° C. for approximately 5.2 minutes duration. The gloves are then cooled on-line for 5.6 minutes bringing them to a temperature of 75° C.  
      On the other hand, the biocompatibility of the gloves prepared by the present invention is desirable. The following skin irritation and dermal sensitization studies were carried out to determine the biocompatibility status of the gloves. The result of primary skin irritation test showed that the glove according to the present invention is not irritation to the skin.  
      In the example I, six New Zealand white rabbits each received a single dermal application of approximately one square inch of the test article on two test sites, one abraded and one non-abraded. The test sites were occluded for 24 hours and were observed individually for erythema, edema, and other effects 24 and 72 hours after application. Mean scores from the 24 and 72 hour readings were averaged to determine the primary irritation index. Each dosage was moistened with saline and applied so that the inside surface of the glove contacted the skin of the test site.  
      Results: Primary Irritation Index: 0.15  
      Conclusion: According to Federal Hazardous Substances Act Regulations (16 CFR 1500.41), and under the conditions of this test, this test article is not a primary dermal irritant.  
      In the example II, twelve (6M:6F) Hartley albino, outbred, viral antibody free, guinea pigs (SPF Hartley guinea pig Aai: (HA) Outbed), 341-398 grams, each received three (3) topical, occluded applications of the test article during the induction period of three weeks. An additional group of then (5M:5F) Hartley-Strain guinea pigs, 351-395 grams, served as a control group. These animals did not receive induction applications. Two weeks following the last induction application, the animals in the test group received a topical application of the test article to a dorsal, virgin site. At the same time, the control group animals received an identical dosage of the test article. Observations of irritation and other effects were recorded 7 and 24 hours after each induction application and 7, 24 and 48 hours following the challenge application. Each dosage (one (1) square inch) was moistened with saline and applied so that the inside surface of the glove contacted the skin of the test site. Once more, the gloves prepared by the present invention is showing negative on irritation.  
      Results:  
                              Results:                             Index:                                 Incidence   Severity       Group   Test/Control   Test/Control                         Scoring Interval:                          7 Hours   0.00/0.00   0.00/0.00       24 Hours   0.00/0.00   0.00/0.00       48 Hours   0.00/0.00   0.00/0.00                  
 
      One skilled in the art will understand that the embodiment of the present invention as shown in the drawings and described above is exemplary only and not intended to be limiting.  
      It will thus be seen that the objects of the present invention have been fully and effectively accomplished. Its embodiments have been shown and described for the purposes of illustrating the functional and structural principles of the present invention and is subject to change without departure form such principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims.