Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Wearing apparel – fabric – or cloth
Reexamination Certificate
2001-09-21
2003-07-01
Page, Thurman K. (Department: 1615)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Wearing apparel, fabric, or cloth
C424S618000, C424S617000, C424S630000, C424S645000, C424S684000, C514S717000, C514S718000, C514S724000, C514S731000, C514S734000, C514S735000
Reexamination Certificate
active
06585989
ABSTRACT:
The present invention relates to combinations of phenolic and inorganic compounds which exhibit excellent antimicrobial activity when incorporated into a substrate resin, which mixtures do not exhibit the negative effects associated with the use of either alone. Plastic articles manufactured via a variety of processes from such resins are provided long term antimicrobial activity and exhibit superior resistance to discoloration and maintenance of physical properties, especially upon exposure to ultraviolet radiation.
Triclosan, or Irgaguard®, Ciba Specialty Chemicals, 2,4,4′-trichloro-2′-hydroxydiphenyl ether, is a known antimicrobial for plastics applications. It is known to have high activity against numerous gram-positive and gram-negative bacterial. It can be incorporated as a neat material or via a masterbatch into a variety of polymer substrates, for example, polyethylenes such as LDPE, HDPE, MDPE, polypropylene (PP), acrylonitrile-butadiene-styrene terpolymer (ABS), styrene-acrylonitrile copolymer (SAN), polystyrene (PS), polyacrylates, polymethyl methacrylate (PMMA), polyamide, polyesters, polyvinyl chloride (PVC), polymer latex, polyurethane (PUR), thermoplastic polyurethane (TPU), unsaturated polyester (UP), urea formaldehyde resin (UF), etc. Irgaguard® exhibits high activity at the surface of plastic articles and the activity remains after repeated washing of plastic articles. Further, Irgaguard® has a good toxicological profile.
Disadvantages of Irgaguard® are that plastic articles formulated with it exhibit strong discloloration upon weathering. For example, polypropylene samples containing Irgaguard® exposed in a Xenon Arc Weather-Ometer at 035 W/m
2
, 63° C. discolor within hours. Further, processing at temperatures greater than 250° C. is poblematic due to the volatility of Irgaguard®.
Silver based materials, such as colloidal silver, silver nitrate, silver sulfate, silver chloride, silver complexes and silver ion containing zeolites are known antimicrobial agents for plastic articles. Silver compounds exhibit high activity against microorganisms and they have a good toxicological profile. High processing temperatures are possible with silver compounds (greater than 300° C.).
Disadvantages of silver based antimicrobials are that plastic articles containing them often exhibit discloloration upon weathering, and the activity on the surface of the articles is often lost after repeated washing.
It has been found, surprisingly, that a combination of certain phenolic compounds with certain inorganic compounds avoids the disadvantages of using either Irgaguard® or silver based antimicrobials alone in plastic articles while providing excellent long-term antimicrobial activity to the articles.
OBJECTS OF THE INVENTION
An object of the present invention is to provide a novel mixture of antimicrobial agents for plastics applications.
Another object of the invention is to provide plastic articles or films with antimicrobial activity which also exhibit superior resistance to discoloration, may be processed at high temperatures, and which maintain physical properties upon weathering, especially upon exposure to UV radiation.
DETAILED DESCRIPTION
The instant invention pertains to a novel mixture of antimicrobial agents for plastics applications which comprises
a) at least one phenolic antimicrobial compound, and
b) at least one inorganic antimicrobial compound,
wherein
the phenolic antimicrobial compound is of the formula (I)
wherein
n is 0 or 1,
R
1
and R
2
are hydrogen or chlorine,
R
3
is hydrogen or hydroxyl,
R
4
, R
5
and R
6
are hydrogen or chlorine,
R
7
is hydroxyl, and
X is —O— or —CH
2
—,
and wherein the inorganic antimicrobial compound is selected from the group consisting of zinc oxide, copper and copper compounds, colloidal silver, silver nitrate, silver sulphate, silver chloride, silver complexes, metal-containing zeolites and surface-modified metal-containing zeolites,
and wherein the ratio of components a):b) is from about 1:9 to about 9:1.
Preferred phenolic antimicrobial compounds of component a) are o-benzyl-phenol, 2-benzyl-4-chloro-phenol, 2,4,4′-trichloro-2′-hydroxydiphenyl ether, 4,4′-dichloro-2-hydroxydiphenyl ether, 5-chloro-2-hydroxy-diphenyl-methane, mono-chloro-o-benzyl-phenol, 2,2′-methylenbis-(4-chloro-phenol) and 2,4,6-trichlorophenol.
Most preferred phenolic antimicrobial compounds of component a) are 2,4,4′-trichloro-2′-hydroxydiphenyl ether and 4,4′-dichloro-2-hydroxydiphenyl ether.
The metal-containing zeolites of component b) are those such as described in U.S. Pat. Nos. 4,775,585, 4,911,898, 4,911,899 and 6,071,542, the disclosures of which are hereby incorporated by reference. A zeolite is generally aluminosilicate having a three dimensionally grown skeleton structure and is generally represented by xM
2
O.Al
2
O
3
.ySiO
2
.zH
2
O, written with Al
2
O
3
as a basis, wherein M represents an ion-exchangeable metal ion, which is usually the ion of a monovalent or divalent metal; n corresponds to the valence of the metal; x is a coefficient of the metal oxide; y is a coefficient of silica; and z is the number of water of crystallization. The zeolites of the present invention have a specific surface area of at least 150 m
2
/g.
Antibacterial metals for use in metal-containing zeolites include silver, copper, zinc, mercury, tin, lead, bismuth, cadmium, chromium, cobalt, nickel, zirconium, or a combination of two or more of these metals. Preference is given to silver, copper, zinc and zirconium, or a combination of these. Especially preferred metals are silver alone or a combination of silver with copper, zinc or zirconium.
Particularly preferred inorganic antimicrobial compounds of component b) are surface-modified metal-containing zeolites according to U.S. Pat. No. 6,071,542.
Especially preferred is the antimicrobial mixture wherein component a) is 2,4,4′-trichloro-2′-hydroxydiphenyl ether and wherein the inorganic antimicrobial compound of component b) is a surface-modified silver-containing zeolite. The term “silver-containing” includes the combination of silver with other metals such as zinc, copper and zirconium. BACTEKILLER BM-102GA (Kanebo) is an example of a surface-modified silver-containing zeolite according to U.S. Pat. No. 6,071,542.
In addition to zeolites, it is also contemplated that antibacterial metals such as silver, silver compounds and silver complexes may be supported on other inert materials, for example SiO
2
, TiO
2
and glass.
The instant invention also pertains to plastic films, fibers or articles that comprise the novel mixture of components a) and b).
The novel antimicrobial mixture of components a) and b) may be incorporated into the plastic resin prior to its being subjected to such manufacturing processes as blown film, rotational molding, fiber spinning, etc. The mixture of components a) and b) is able to withstand demanding processing conditions such as high temperature, e.g. temperatures greater than 200° C.
The plastic films, fibers and articles comprising the present antimicrobial mixture of components a) and b) is suitable for outdoor exposure; they are resistant to weathering and UV light degradation.
The antimicrobial mixture of components a) and b) exhibit good long-term activity and a good toxicological profile.
Triclosan containing plastic samples lead to a strong discoloration within a very short time when exposed to weathering. Plastic samples containing the present combination of components a) and b) exhibit only minimal color changes.
Triclosan containing plastic samples exhibit a reduced light stability. Plastic samples containing the present combination of components a) and b) exhibit physical properties that are comparable to a control formulation without antimicrobial agents.
The plastic films, fibers and articles of the present invention are advantageously employed for applications that require long-term hygienic activity on the surface, e.g., medical devices, hand rails, door handles, etc. The antimicrobial plastic film
Herbst Heinz
Stadler Urs
Ciba Specialty Chemicals Corporation
Fubara Blessing
Page Thurman K.
Stevenson Tyler A.
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