JPH0717771B2 - Dipped rubber products - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to flexible rubber articles, particularly thin rubber gloves of the kind used by surgeons.

[0002]

BACKGROUND OF THE INVENTION Because surgeon's gloves are difficult to don, they are usually coated on their inner surfaces with a powdered lubricant, such as epichlorohydrin-treated cornstarch particles, to facilitate donning. If this powdered lubricant leaks from the inside of the gloves, there is a risk of contaminating the surgical site, and this leakage can occur when the gloves are being donned or, occasionally, when the gloves tear during surgery.

Polymeric lubricants have been proposed which are bonded to the inner surface of such gloves and which, because they are bonded to the inner surface, cannot leach out of the gloves.

Examples of such proposals include U.S. Pat. Nos. 4,070,713 and 4,143,109, which disclose gloves having an inner layer made of an elastic material and embedded therein a granular lubricant;
U.S. Pat. No. 38,136 also discloses surgeon's gloves with various slip coatings bonded to the inner surface.
Nos. 95, 3856561 and 4302852.

[0005] U.S. Pat. No. 3,813,695 ("Podell Patent") describes a surgeon's glove in which the glove material is formed from a laminate of an outer layer of flexible material, such as rubber, and a hydrophilic plastic material (such as a hydrogel polymer), with the inner and outer layers bonded to each other.

Many hydrogel polymers are known,
Examples include polyvinylpyrrolidone, polyhydroxyethyl acrylate or methacrylate, polyhydroxypropyl acrylate or methacrylate, and copolymers thereof with one another or with acrylic or methacrylic acid, acrylic or methacrylic esters or vinylipyridine.

A camera comprising such a hydrogel polymer formed by immersion in a solution of a hydrophilic, hydrogel-forming polymer and curing the resulting polymer layer is
There are many disclosures of this type of coating on rubber products such as taters and bath caps.

Among these numerous disclosures are U.S. Pat. No. 3,333,623.
No. 26742, No. 3585103, No. 3607473
No., No. 3745042, No. 3901755, No. 39
No. 25138, No. 3930076, No. 3940533
No., No. 3966530, No. 4024317, No. 41
10495 and 412547, and British Patent Nos. 1028446 and 859297.

[0009]

We have investigated a number of such hydrogel polymers and have surprisingly found that certain 2-hydroxyethyl methacrylate polymers exhibit excellent lubricity on dry skin and, with appropriate treatment, can also exhibit excellent lubricity on wet skin.

[0010]

Therefore, in accordance with the present invention, 2-hydroxyethyl methacrylate (HEMA)
and methacrylic acid (MAA) or 2-ethylhexyl acrylate (EHA), or HEMA,
A flexible rubber article is provided having a layer formed of a hydrogel polymer comprising a terpolymer of MAA and EHA and bonded to the article to form its skin-contacting surface.
In this case, the copolymer has a composition within the boundaries of the region ABCDEF in the ternary composition diagram of accompanying Figure 1. The region ABCDEF is considered to cover substantially the entire hydrogel-forming region of the composition diagram, and this region does not include homopolymers of HEMA or HEM.
A copolymer of A with up to 5% EHA and/or MAA is preferred.

Preferably, the composition is within the region ABXYZ, more preferably within the region PQRI. Most preferably, the composition is within the region IJKL.

In some embodiments, such copolymers comprise HEMA and MAA in a ratio of at least 1:1 (1 to 1).
or HEMA and EHA in a molar ratio of at least 2.5:1 (2.5 to 10:1).

The copolymer is preferably prepared by solution polymerization (bulk polymerization is less satisfactory).
The copolymer may be a copolymer of HEMA with MAA or EHA, or a terpolymer of these monomers with EHA. Such preferred terpolymers have a molar ratio of HEMA to (MAA+EHA) of 67:33 to 90:10 (i.e., 2 to 9:1) and a molar ratio of EHA to (HEMA+MAA) of 5:
97 to 20:80 (i.e., about 1:20-4).

Additionally, minor amounts of monomers which do not impair the properties of the copolymer may be added. The copolymers described above may also be used as mixtures with other copolymers of this type, or with minor amounts of other polymers which do not impair the properties of the hydrogel-forming polymer.

It should also be noted that EHA is hydrophobic, which aids in bonding of the hydrogel polymer to the (hydrophobic) rubber substrate. EHA also functions as a plasticizer,
It increases the flexibility of the hydrogel polymer (which is bonded to a flexible rubber substrate). Therefore, EHA can be replaced with alkyl acrylates or methacrylates that act similarly.

MAA provides crosslinking sites in the copolymer. The methyl groups in MAA affect the copolymer by (i) modifying the reactivity of the carboxylic groups, thereby influencing the degree and rate of crosslinking, and (ii) modifying the rate at which MAA is incorporated into the polymer backbone and, therefore, the distribution of crosslinking sites along the polymer chain.

The above-described copolymers provide better lubrication on dry skin than many of the other hydrogel-forming polymers we have examined. However, there is a significant difference between lubrication on dry skin and lubrication on moist skin. Surgeons' hands are particularly moist because they prefer to put on gloves after scrubbing their hands without completely drying them. We have found that hydrogel polymers used as inner layers bonded to surgeon's gloves, as suggested in the Podell patent, provide generally insufficient lubrication on moist hands.

The layer formed from the hydrogel polymer according to the present invention is preferably crosslinked. Such crosslinking generally reduces the water absorption of the polymer. After crosslinking, the layer may be surface-treated with a physiologically acceptable surfactant or a long-chain aliphatic amine, which increases the layer's lubricity on moist skin.

Such surfactants and fatty amines improve the lubricity to wet skin of a wide range of hydrogel polymers, as well as the special 2-hydroxyethyl methacrylate copolymers mentioned above.

Therefore, according to another aspect of the present invention,
A flexible rubber article is provided, comprising a layer formed of a hydrogel polymer and bonded to the article to form its skin-contacting surface, the layer preferably being surface-treated with a bactericidal or bacteriostatic surfactant or a long-chain aliphatic amine. The surfactant used is preferably ionic (although it may sometimes be preferred that the surfactant have a polarity opposite to that of the hydrogel-forming polymer). Cationic surfactants are particularly preferred. Such cationic surfactants may contain a free anion, such as a halide ion, or the anion may be part of the surfactant's molecular structure (i.e., the latter may have a betaine structure).

Preferred cationic surfactants are quaternary ammonium compounds having a hydrocarbon group (alkenyl or alkyl) containing 6 to 18 carbon atoms, the preferred hydrocarbon group being a hexadecyl group. More preferably, the hydrocarbon group is attached to a quaternary nitrogen atom which is part of a heterocyclic ring (such as that of pyridine, morpholine, or imidazoline).

The most preferred cationic surfactants are hexadecyltrimethylammonium chloride, N-laurylpyridinium chloride, N-cetylpyridinium chloride, their corresponding bromides, or hydroxyethylheptadecenylimidazoline salts, all of which significantly improve lubrication on wet skin, while
Does not adversely affect lubrication on dry skin.

Nonionic and anionic surfactants may be used in place of the cationic surfactants. Examples of suitable nonionic surfactants include ethylene oxide condensates (polyethylene oxide, ethylene oxide-
Such surfactants include polypropylene glycol condensates, and polyglycol-polyamine condensates. An example of a suitable anionic surfactant is sodium lauryl sulfate.

If a (neutral) aliphatic amine is used,
A preferred amine is one in which a hydrocarbon group having 6 to 18 carbon atoms (e.g., a hexadecyl group) is attached to the nitrogen atom. A preferred such amine is N,N-dimethylhexadecylamine (commercially available as Armeen 16 D).

The use of a cationic surfactant acts to inhibit bacterial growth when the layer formed from the hydrogel polymer is in contact with the skin. This is an advantage for surgeon's gloves because, as mentioned above, gloves can occasionally tear during a surgical procedure, releasing bacteria that have grown on the surgeon's skin since the start of the procedure into the surgical area.

The surfactant or aliphatic amine is used in the form of a solution, such as an aqueous solution of the cationic surfactant (typical aqueous solutions are at least 0.2% by weight, eg 2% by weight).

The product according to the invention is preferably treated with a silicone fluid to reduce the tackiness of surfaces not coated with a layer formed from a hydrogel polymer. This treatment is preferably carried out simultaneously with the treatment with the surfactant described above. The treatment with silicone (such as pharmaceutical grade dimethylsiloxane) is carried out in a manner that is at least 0.
Preferably, the solution contains 0.5% by weight of silicone (e.g., 0.05-0.4% by weight).

The rubber used in the products of the present invention may be natural or synthetic rubber, with natural rubber being preferred. The products of the present invention are preferably formed by impregnation with rubber latex (prior to bonding the layer formed from the hydrogel polymer). The hydrogel layer is preferably applied to the rubber before vulcanization. This surprisingly results in a greater cooling sensation on the skin-contacting surface, likely due to greater vapor transmission through the final coated product.

Therefore, in accordance with another aspect of the present invention, there is provided a dipped rubber article having attached thereto a lubricating layer which forms the skin-contacting surface of the article, comprising applying a hydrophilic hydrogel-forming polymer solution to the impregnated rubber article prior to its complete vulcanization and hardening,
A dipped rubber article is provided which is formed by curing the polymer and vulcanizing the rubber.

The lubricating layer absorbs sweat and also makes it possible to dispense with the use of powdered lubricants.

The hydrogel-forming polymer solution (preferably including its curing agent) is preferably applied by dipping the rubber article into the solution.

The product according to the present invention is manufactured by a process comprising the following steps:

(a) forming a rubber article by immersing a master form in rubber latex, (b) exposing the rubber article in hot water;

(c) The rubber surface of the product bonded onto the master is pretreated, for example, with a dilute acid.

(d) Rinse the pretreated surface with water or aqueous alkali.

(e) While still bonded on the master, the article is immersed in a solution of a hydrophilic hydrogel-forming polymer and its curing agent.

(f) Heat drying is performed so that the resulting hydrogel polymer coating bonds to the rubber.

(g) The rubber is vulcanized and the polymer is cured by heating.

(h) The resulting product is peeled off from the mold.

(i) After optional rinsing, a solution of a silicone-containing surfactant material is applied to the article (eg, by tumbling back and forth in such solution).

(j) Heating the resulting surfactant coating to set in the slip properties of the coating.

Tests conducted by us after step (j) have shown the advantageous fact that the wet and dry skin slip properties of the coating formed from the hydrogel polymer are not impaired by subsequent washing (i.e., the surfactant material is not substantially leached out when the coated product is washed).

[0043] The application of a surfactant solution provides a non-stick surface on the exterior surface (not coated with hydrogel polymer) as well as the interior surface, which is of course advantageous.

The rubber surface to which the hydrogel polymer is to be bonded may be pretreated by, for example, immersion in a solution of an aluminum salt after pretreatment with a dilute acid.

It is a feature of the present invention that the preparation of the dipped rubber article, bleaching, pre-treating, application of the hydrogel polymer layer, vulcanization of the rubber and curing of the polymer are carried out in a continuous operation.

Although the present invention has been described primarily with reference to surgeon's gloves, it is also applicable to other flexible rubber articles which come into contact with skin or tissue, such as condoms, examination gloves used by medical and veterinary surgeons (such gloves are often worn on dry hands), catheters, urinary tubes, sheets and sheath-type incontinence devices.

When the present invention is used in a urinary tract or catheter, the layer formed from the hydrogel polymer is applied to the outer surface (this is the surface that comes into contact with the skin). In the case of a condom, the layer formed from the hydrogel polymer may be applied to the inner and/or outer surface.

[0048].

In order that the invention may be more fully understood, the following examples and comparative examples are given by way of illustration only.

Example 1 Thin surgeon's gloves made of natural rubber latex were exposed to sulfuric acid, washed, pretreated by dipping in an aluminum sulfate solution, thoroughly dried, and then immersed in a 4% aqueous solution of a copolymer of 2-hydroxyethyl methacrylate (HEMA) and methacrylic acid (MAA) in a 1:1 molar ratio.
% alcohol solution, which contained a 5/10 copolymer plus a partially methylated melamine-formaldehyde resin (as a crosslinker) and then dried.
0 and paratoluenesulfonic acid (as a catalyst) 0.5
/100 was included.

The rubber was then vulcanized and its lubricity to dry skin was evaluated on the following scale of 1 to 5:

1 means the coating is sticky, 2 means poor slip, 3 means fair slip, 4 means good slip, 5 means excellent slip (compared to a powdered lubricant surface). The lubricity index on dry skin was 5. The coating adhered well to the rubber and no visible peeling was observed.

Examples 2 to 11 The same procedures as in Example 1 were carried out except that the copolymers were replaced with those in Table 1 below.

[0053] Table 1 Example No. Polymer Monomer Molar Ratio Lubricity Index for Dry Skin 2 HEMA/MAA 2:1 5 3 HEMA/MAA 5:1 5 4 HEMA/MAA 10:1 5 5 HEMA/EHA 2.5:1 5 6 HEMA/EHA 4:1 5 7 HEMA/EHA 5:1 5 8 HEMA/EHA 10:1 5 9 HEMA/MAA/EHA 10:1:0.5 5 10 HEMA/MAA/EHA 5:1:1.2 5 11 HEMA/MAA/BA 10:1:0.5 5 Comparative Example No. Polymer Monomer Molar Ratio Lubricity Index for Dry Skin 1 HEMA/AA 2:1 4 2 HEMA/AA 1:1 4 3 HEMA/MMA 2:1 4 4 HEMA/MMA 1:1 4 5 HEMA/BA 5:1 4 6 HEMA/BA 2:1 3 7 HEMA/MA 2:1 4 8 HEMA/IA 2:1 4 9 HEMA/EHA 2:1 4 10 HEMA/EHA 1:1 4 11 HEMA/VPd 1:1 3 12 HEMA - 3-4 13 EHA - 3-4 14 VPb - 2 15 HPMA - 3-4 16 HEMA/HEA 1:1 4 17 HEMA/VPd 1:1 3-4 18 HEMA/HPMA 1:1 4 19 HEA/HPMA 1:1 4 20 HEMA/VPy 9:1 4-5 The abbreviations in the table above have the following meanings:

EHA 2-Ethylhexyl acrylate BA Butyl acrylate AA Acrylic acid MMA Methyl methacrylate MA Methyl acrylate IA Itaconic acid PVb N-Vinylpyrrolidone HEA Hydroxyethyl acrylate HPMA Hydroxypropyl methyl acrylate VPy Vinylpyridine (quaternized) It can be seen that each example according to the present invention has better lubricity on dry skin than any of the comparative examples (the only comparative sample whose lubricity is close to that of the sample according to the present invention is Comparative Example 20, which uses a quaternized copolymer).

In all of the examples according to the present invention, the coating was well adhered with very little peeling, including all the comparative examples except for Comparative Example 14, in which the coating was washed off when wiped wet.

The frictional force and coefficient of friction for the glove of Example 6, the glove of Example 10 and the powder coated conventional glove are shown in Table 2 below.

Table 2 Gloves Frictional force in dry state Friction coefficient Example 6 48.7 g 0.20 Example 10 53.1 g 0.218 Conventional product with powder coating 78.5 g 0.323 Examples 1 to 11 and Comparative Examples 2 to 10, 12, 13, 1
The lubricity index for wet skin was 2 for Nos. 5 to 20, and 1 for Comparative Examples 1, 11, and 14.

Examples 12-21 The samples prepared in Example 10 were post-treated by immersion in solutions of various substances as shown in Table 3 below.

Table 3 Example No. Material Solution Concentration Lubricity Index on Wet Skin 12 N-Cetylpyridinium Chloride (N-CPC) 5% 3-4 13 Same as above 1% 3-4 14 Sodium lauryl sulfate 5% 3 15 Same as above 1.0% 3 16 Same as above 0.5% 3 17 Same as above 0.1% 2-3 18 N,N-Dimethylhexane 1% 3-4 Decylamine 19 Ethylene oxide-polypropylene 1% 3 Pyrene glycol condensate 20 Distearyldimethylammonium chloride 1% 3 21 Hexadecyltrimethylammonium chloride 1% 3-4 In each case, the lubricity on dry skin was not substantially impaired.

Examples 22-26 The same procedures as in Example 12 were carried out using solutions containing N-CPC in various proportions as shown in Table 4 below and containing 0.3% pharmaceutical grade polydimethylsiloxane.

Table 4 Example No. Percentage of N-CPC Lubricity Index on Wet Skin 22 0.1 3 23 0.25 3-4 24 0.50 4 25 1.0 4 26 2.0 4 Percentage of polydimethylsiloxane was increased to 0.05%.
Even when the above condition was met, the same effect as in Example 22 was obtained.

Example 27: A series of hand-shaped formers were dipped in natural rubber latex to form a thin rubber layer on each former. The rubber layer was then treated by exposure to hot water, followed by immersion in dilute sulfuric acid, rinsed, and immersed in a caustic soda bath at pH 10.5 containing sufficient hydrogen peroxide to react with the hydrogen sulfide formed in the pretreatment step. The rubber, while still covered on the former, was then applied to a 5:1:1.2 monomer molar ratio.
The samples were immersed in a 4% ethanolic solution of a HEMA/MAA/EHA terpolymer containing 5/100 to 5/100 (based on polymer weight) of a partially methylated melamine-formaldehyde resin (as a crosslinker) commercially available as Cymel 373, and paratoluene sulfonic acid (as a catalyst) (based on the same basis).
It was included between 0.5/100 and 1.5/100.

The rubber was then vulcanized and the polymer cured at the same time (during vulcanization the temperature was raised to 80°C for 25 minutes).
The resulting gloves were stripped from the formers. The stripped gloves were rinsed with water and then inverted into an aqueous solution containing 0.75 wt. % N-cetylpyridinium chloride, which also contained 0.05 wt. % silicone emulsion. The gloves were finally inverted and dried at 65°C for 75 minutes.

The resulting glove had a dry skin lubricity index of 5 and a wet skin lubricity index of 4 for its polymer coated surface (used on the inside of the glove).

No allergic or irritant reactions have been reported with these gloves, even when worn by surgeons with sensitive skin.

Example 28: Copolymer was prepared from 80% HEMA, 10% MAA, 10% EH
The same procedure as in Example 1 was carried out except that the copolymer having the molar ratio of A was used instead. A lubricity index of 5 for dry skin was obtained.

Example 29: A rubber-coated porcelain mandrel was immersed in water above 70°C for several minutes, rinsed with running water, and immersed in 2% sulfuric acid at 40°C. The coated mandrel was then immersed in dilute caustic soda (pH 9-10) (for neutralization) and then in a water wash tank at 40°C. The coated mandrel was then coated with a 10% ethanol solution of the ternary polymer used in Example 1, containing 10% by weight of Cy.
It contains mel370 (crosslinker) and 1% by weight of p-toluenesulfonic acid.

The coated mandrel was heated in an oven at a temperature of 105° C. for 30 minutes.

The gloves were stripped from the mandrels and immersed for 15 minutes in a 15% aqueous dispersion of 35% silicone medical grade emulsion DC365 (trademark of Dow Corning Co.) containing 0.5% cetylpyridinium chloride. After draining, the gloves were dried in a 70°C oven for 30 minutes.

The outer surface of the gloves was not sticky, and the inner coated surface was hydrophilic and had high slipperiness, making them easy to put on even on dry hands (the lubricity index for dry skin was 5).

The moisture transport properties of the final gloves at 25°C (100% relative humidity) are shown below in Table 5, along with those of a similar uncoated glove (control). TABLE 5 Sample Moisture Transport Rate (gm/m²/mm/24 hr) Inventive 7.86 Control 4.22 Examples 30-37 Example 1 was repeated except that the copolymer was replaced with the polymer shown in Table 6 below.

Table 6 Example No. Mole % HEMA Mole % MAA Mole % EHA 30 70 20 10 31 60 10 30 32 60 20 20 33 60 30 10 34 50 30 20 35 40 30 30 36 40 40 20 37 30 60 10 In all cases, a lubricity index of 5 on dry skin was obtained.

Examples 38 to 53 were carried out in the same manner as in Example 12, except that various surfactant solutions were used in place of N-CPC. The results are summarized in Table 7.

Example 54: Example 1 was repeated except that the copolymer was replaced with a copolymer having the following molar ratio: 70% HEM
A, 10% EHA, 10% EHA. A lubricity index of 5 was obtained for dry skin.

[0075] Table 7 Examples Surface Active Agent Solution Concentration No. Lubricity Index on Wet Skin 38 Octadecyltrimethylammonium Bromide 1.0% 3 39 Cetylpyridinium Bromide 1.0% 3-4 40 2-Oleyl-1-(ethylbetaine)imidazoline 1.0% 3 Oxypropionic Acid 1.0% 3 41 Laurylpyridinium Chloride 1.0% 3-4 42 Oxyethylalkylammonium 1.0% 3 Phosphate 43 Alkyldimethylbenzylammonium Chloride (10-18C) 1.0% 3 44 Polypropoxyquaternary ammonium 1.0% 3 Acetate 45 Alkylbetaine (12-14C) 1.0% 3 46 Coconut Imidazoline Betaine 1.0% 3 47 Amine Oxide Ethoxylate 1.0% 3 (Empigen DY) 48 N-Cetyl-N-Ethylmorpholinium Ethosulfate 1.0% 3 49 Distearyldimethylammonium Chloride 1.0% 3 50 Pluronic F38 (Ethylene Oxide Polypropylene Glycol, Molecular Weight 5020) 0.15% 3 51 Polyethylene Oxide (Molecular Weight 400,000) 1.0% 3 52 Dodecylbenzyl Hydroxymethyl Dimethyl Chloride 1.0% 3 53 Cetyl Stearyl Ethylene Oxide Condensate (20 Ethylene Oxide Units) 5% 3

[Brief explanation of the drawings]

FIG. 1 shows a ternary composition diagram of HEMA, MAA, and EHA.

──────────────────────────────────────────────────── Continued from the front page (72) Inventor: Duck, Roger 29 Woodstock Road, Upper E17, London, England (72) Inventor: Podell, Howard Irwin 28 Beachfront Lane, New Rochelle, New York, 10805, United States (72) Inventor: Goldstein, Albert 87 Glenwood Drive, Tenton Falls, New Jersey, 07724, United States (72) Inventor: Blackley, David Charles 100 Berkeley Avenue, Buckinghamshire H.P.S., 2RS, Chesham, United Kingdom (56) References: Patent Publication Showa 50-150793 (JP, A) Special Public Official Showa 56-36066 (JP, B2)

Claims (4)

[Claims] [Claim 1] A flexible rubber article comprising a layer bonded to the article to provide its skin-contacting surface, said layer being formed from a hydrogel polymer consisting of a copolymer of 2-hydroxyethyl methacrylate with methacrylic acid and/or 2-ethylhexyl acrylate, said copolymer having a composition within the boundaries of region ABCDEF in the ternary composition diagram of accompanying Figure 1, thereby substantially improving the lubricity of the skin-contacting surface against dry skin. Claim 2. The copolymer has a composition within the boundaries of region PQRI in the ternary composition diagram of accompanying Figure 1.
1. The product described in [Claim 3] A dipped rubber product as described in claim 1, having a lubricious layer bonded to the product to provide its skin-contacting surface, said lubricious layer being formed by applying a solution of a hydrophilic hydrogel-forming polymer to the product prior to full vulcanization of the dipped rubber product, followed by curing the polymer and vulcanizing the rubber. 4. The method of claim 1, wherein the solution is applied by immersion.
Item 3. The product according to item 3 .