U.S. patent application number 16/711632 was filed with the patent office on 2020-04-16 for mechanically reinforced, transparent, anti-biofouling thermoplastic resin composition and manufacturing method thereof.
The applicant listed for this patent is Nano and Advanced Materials Institute Limited. Invention is credited to Yueying CHEN, Yiu Ting Richard LAU, Wenjun MENG.
Application Number | 20200115534 16/711632 |
Document ID | / |
Family ID | 62906057 |
Filed Date | 2020-04-16 |
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United States Patent
Application |
20200115534 |
Kind Code |
A1 |
MENG; Wenjun ; et
al. |
April 16, 2020 |
MECHANICALLY REINFORCED, TRANSPARENT, ANTI-BIOFOULING THERMOPLASTIC
RESIN COMPOSITION AND MANUFACTURING METHOD THEREOF
Abstract
This invention discloses a transparent standalone resin or
masterbatch concentrate composition and manufacturing method of
transforming commercial transparent grade base thermoplastics into
anti-biofouling resins through extrusion or any similar hot melt
mixing processes. The re-compound solids enable a number of product
reforming processes, including but not limited to thermoforming,
profile extrusion, injection molding, blow molding, blow filming,
film casting, and spinning into articles of different shapes and
geometries or overmolding on plastic substrates that can resist
surface adsorption of microbes, mammalian cells, proteins,
peptides, nucleic acids, steroids and other cellular constituents
after solidification. The articles formed thereof additionally
exhibit mechanical reinforcement and no leaching while retain the
optical clarity of the base thermoplastics in the same product form
as quantified in terms of the light transmittance and haze.
Inventors: |
MENG; Wenjun; (Hong Kong,
CN) ; CHEN; Yueying; (Hong Kong, CN) ; LAU;
Yiu Ting Richard; (Hong Kong, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Nano and Advanced Materials Institute Limited |
Hong Kong |
|
CN |
|
|
Family ID: |
62906057 |
Appl. No.: |
16/711632 |
Filed: |
December 12, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15415426 |
Jan 25, 2017 |
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16711632 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B29K 2995/0026 20130101;
B29C 48/919 20190201; B29C 48/022 20190201; C08L 23/12 20130101;
B29C 48/40 20190201; B29K 2105/0005 20130101; B29B 9/06 20130101;
C08L 2310/00 20130101; B29C 49/0005 20130101; B29B 7/005 20130101;
B29K 2101/12 20130101; C08L 2201/08 20130101; C08L 2205/05
20130101; B29B 9/12 20130101; B29B 7/88 20130101; C08L 2201/10
20130101; C08L 33/12 20130101; B29C 41/003 20130101; C08L 2205/06
20130101; C08L 23/14 20130101; C08L 23/14 20130101; C08K 2003/2227
20130101; C08L 23/0815 20130101; C08L 23/12 20130101; C08K
2003/2227 20130101; C08L 23/0815 20130101 |
International
Class: |
C08L 23/14 20060101
C08L023/14; B29C 48/40 20060101 B29C048/40; B29C 48/88 20060101
B29C048/88; B29B 9/12 20060101 B29B009/12; B29C 48/00 20060101
B29C048/00; B29C 41/00 20060101 B29C041/00; B29B 7/00 20060101
B29B007/00; B29B 7/88 20060101 B29B007/88; C08L 33/12 20060101
C08L033/12; C08L 23/12 20060101 C08L023/12 |
Claims
1. A composition for forming a functional polymer or a masterbatch
concentrate resin comprising a transparent grade base
thermoplastics at 70-99 wt %, impact modifiers at 0.1-30 wt %,
chemical modifiers at 0.5-10 wt %, and other additives at 0.1-6 wt
%, wherein said chemical modifiers comprise non-fouling modifiers
in 0.1-5 wt %; and wherein said other additives comprise one or
more of initiators, cross-linking agents, nucleators,
anti-oxidants, and/or auxiliary additives in 0.1-6 wt %.
2. The composition of claim 1, wherein said transparent grade base
thermoplastics comprise homopolymers, copolymers and blends of
polyolefins, cyclic polyolefins, acrylics, acetates, styrenics,
polyesters, polyimides, polyaryletherketones, polycarbonates,
polyurethanes and thermoplastic elastomers.
3. The composition of claim 1, wherein said transparent grade base
thermoplastics comprises poly(methyl methacrylate) (PMMA),
polystyrene (PS), polyethylene terephthalate (PET), polycarbonate
(PC), polymethylpentene (PMP), polysulfone, polyamide (PA),
polyvinyl chloride (PVC), styrene acrylonitrile (SAN),
styrene-methacrylate based copolymer, polypropylene based
copolymer, acrylonitrile butadiene styrene (ABS), polyimide (PI)
cellulosic resins, methyl methacrylate butadiene styrene (MBS), and
styrene ethylene butylene styrene block thermoplastic elastomer
(SEBS).
4. The composition of claim 3, wherein said polypropylene based
copolymer comprises polypropylene random copolymer (PPR),
impact-modified polypropylene compound (PPM) and polypropylene
homopolymer (PPH).
5. The composition of claim 1, wherein said non-fouling modifiers
comprise one or more of linear and/or multi-armed structures of
non-ionic surfactants and are in a concentration from 0.5 wt % to
10 wt %.
6. The composition of claim 5, wherein said non-ionic surfactants
comprise fatty alcohol polyoxyalkylene ethers, polyoxyalkylene
sorbitan/sorbitol fatty acid esters, polyoxyalkylene alkyl amines,
polyether glycols, fatty acid alkanolamides and their
derivatives.
7. The composition of claim 5, wherein said non-ionic surfactants
comprise polyethylene glycol (PEG) sorbitol hexaoleate, AEO-5 and
polyetheramine.
8. The composition of claim 7, wherein said PEG sorbitol hexaoleate
has an average molecular weight from 2000 to 20,000 Da.
9. The composition of claim 7 wherein said polyetheramine has a
molecular weight from 200 to 6,000 Da.
10. The composition of claim 1, wherein said impact modifiers
comprise polyolefin elastomers (POE) and thermoplastic polyurethane
(TPU).
11. The composition of claim 1, wherein said initiators comprise an
acid or base catalyst and exist in either standalone form or is
supported on filler particles with a weight percentage from 0.01 to
0.2 wt %.
12. The composition of claim 1, wherein said initiators comprise
tosylic acid, tetramethylammonium hydroxide, or an organic peroxide
and exist in either standalone form or is supported on filler
particles with a weight percentage from 0.01 to 0.2 wt %.
13. The composition of claim 12, wherein said organic peroxide
comprises dicumyl peroxide, bis(tert-butylperoxyisopropyl)benzene,
2,5-bis(tert-butylperoxy)-2,5-dimethylhexane, benzoyl peroxide.
14. The composition of claim 1, wherein said cross-linking agents
comprise triallyl isocyanurate, N,N'-m-phenylene dismaleimide or
sulfur and are in a concentration from 0.01 to 0.2 wt %.
15. The composition of claim 1, wherein said nucleators comprise
MILLAD.RTM. NX8000, MILLAD.RTM. 3988, ADK STAB NA-18 or ADK STAB
NA-25 in a concentration from 0.1 to 3 wt %.
16. The composition of claim 1, wherein said anti-oxidants comprise
butylated hydroxytoluene, IRGANOX.RTM. 1010, Irganox.RTM. 1076,
Irganox.RTM. 1098, Irgafos.RTM. 168 or Irganox.RTM. B 225, and are
in a concentration from 0.1 to 2 wt %.
17. The composition of claim 1, wherein said auxiliary additives
comprise alumina nanoparticles and are in a concentration from 0.1
to 4 wt %.
18. The composition of claim 7, wherein said polyetheramine
comprise JEFFAMINE.RTM. D-230 or T-5000.
19. The composition of claim 17, wherein said alumina nanoparticles
are AEROXIDE.RTM. Alu C.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This is a divisional patent application of U.S.
non-provisional patent application Ser. No. 15/415,426, filed on
Jan. 25, 2017, the disclosure of which is herein incorporated by
reference in its entirety.
TECHNICAL FIELD
[0002] The present invention relates to methods for modifying
transparent grade base thermoplastics to increase their surface
biofouling resistance with added mechanical reinforcement while
retain the light transmittance and haze of the base thermoplastics
after product forming processes. In particular, the present
invention relates to methods of introducing suitable chemical
modifiers to the base materials through extrusion or hot melt
mixing in order to increase surface biofouling resistance of the
base thermoplastics. It also relates to the product formed
therefrom.
BACKGROUND OF THE INVENTION
[0003] Transparent plastics ordinarily are rigid thermoplastics
such as poly(methyl methacrylate) (PMMA), polystyrene (PS),
polyethylene terephthalate (PET), polycarbonate (PC),
polymethylpentene (PMP), polysulfone, polyamide (PA), polyvinyl
chloride (PVC), styrene acrylonitrile (SAN), styrene-methacrylate
based copolymer, polypropylene based copolymer, acrylonitrile
butadiene styrene (ABS), polyimide (PI) and cellulosic resins.
Transparent plastics are regarded as plastics with light
transmission percentage of more than 80%. These plastics can be
used in aquariums, signboards, automobile taillights, bathtub
liners, sinks, cell phone display screens, backlight optical
waveguides for liquid crystal displays (LCD), lighting bulb shells
and aircraft window panels due to their low cost and ease of
processing as well as their lightweight, shatter resistant,
low-temperature impact resistant and chemical resistant properties.
They are therefore expected to replace the unbendable oxide glasses
in a wider range of applications in the near future apart from the
large application base in commodity products including food and
cosmetics packaging, construction, electrical appliances, toys,
stationery, spectacles and more.
[0004] There is a strong motivation for incorporation of surface
biofouling resistance into optically clear plastics that can be
found in daily life applications, for instance, the dust collection
chamber of the vacuum cleaner, the refillable liquid soap dispenser
and the paper roll holder which necessitates sanitary conditions
against microbes. Previous research showed that 50% of vacuum
cleaner brushes contained fecal bacteria and E. coli. Another data
supported that 25% of the refillable soap dispenser in the public
restrooms was contaminated with more than 1 million colony-forming
units (CFU) per milliliter of bacteria and 16% of the soap samples
contained coliform bacteria. On average, at least 10,000-fold
increase in the bacteria population is expected over 5 hours in a
non-sanitized and nutrient-enriched ambience.
[0005] Conventional non-fouling modification of polymers is usually
achieved by surface modification and coating with hydrophilic
layers on the polymeric surfaces after molding. This can be
demonstrated in a number of disclosures as follows.
[0006] CN102942708 discloses a wet chemical approach to obtain
surface hydrophilic polypropylene material in the form of film,
mesh, wire, particles or microspheres, by grafting a monomeric
maleic anhydride onto a polypropylene and then polyethylene glycol
onto the maleic anhydride. This is yet a surface modification
process on a preform of polypropylene material to impart the
antifouling properties.
[0007] One non-patent citation describes a combined
self-hydrogel-generating and self-polishing crosslinked polymer
coating, where hydrolysable polymer chains are kept leaching out
from the top to keep the surface antifouling (Xie et al. Polymer
2011, 52, 3738).
[0008] DE19643585 reveals an anti-adhesive agent, containing
sphingolipid, against microorganisms, viruses, parasites and
protozoa.
[0009] US20110177237 utilizes chromen-4-one derivatives as
non-toxic, environment friendly antifouling agent, a coating
material for objects submerged under the water and subject to
biofouling.
[0010] WO2016015005 discloses a three-component, protein-repellent
dental bonding system based on 2-methacryloyloxyethyl
phosphorylcholine as the active protein repellent agent.
[0011] US20090094954 discloses an antifouling composite material
through disposing an inorganic fine particle layer on a surface of
the substrate.
[0012] Some employ various classes and structures of functional
polymers as coatings to impart fouling resistance of relevantly
compatible substrates towards marine organisms as exemplified by
US20160002489, US20150197644, US20100130665 and U.S. Pat. No.
6,303,078.
[0013] Especially to living matters, one even adopts the time
release of antimicrobial compounds from the polymeric materials,
such as US20150218390, to avoid adherence of microorganisms to form
a biofilm and/or kill the microorganisms already adhered inhibiting
their growth, which is ecologically unfriendly and potentially
toxic to the mankind.
[0014] As inspired from the earlier fundamental researches, surface
energy of the substrate definitely plays an important role. Minimal
long-term adhesion of microbes is associated with surfaces having
initial surface tensions between 20 and 30 mN/m, i.e. low-energy
surfaces. Silicones and fluoropolymers are the two well-known
non-fouling organic compounds having been used as the essential
coating ingredients due to their low surface energies.
[0015] WO2016110271 discloses a built-in modification method to
enable antimicrobial property of polymers, through repelling the
microbes from the article surfaces based on an antifouling agent.
The antifouling agent is selected from a hydrophilic forming group
consisting of polyol, polyoxyether, polyamine, polycarboxylate,
polyacrylate, polyvinylpyrrolidone, polysaccharide, Zwitterionic
polyelectrolyte, a copolymerized system of polymer segments of
mixed charges and/or an interpenetrating blend mixture of cationic
and anionic polymers. The agent has to react with maleic anhydride
on a polymer carrier as a coupling linker and to be blended with
the base polymer.
[0016] US20100280174 discloses a melt blending process to
incorporate non-ionic surfactants having an HLB number of less than
or equal to 10 into hydrophobic polymers. The molded articles show
the protein resistance due to surface migration of the surfactants.
However, there are no relevant claims to indicate the bulk physical
change and more astoundingly, mechanical reinforcement, as well as
retention of the optical properties after the said
modification.
SUMMARY OF THE INVENTION
[0017] Accordingly, in a first aspect of the present invention, a
melt compounding strategy to non-covalently blend or covalently
graft the non-fouling moieties onto the backbones of various
optically clear copolymer resins is employed into a method for
modifying a transparent grade thermoplastic, wherein said method
comprises firstly using reactive melt extrusion on a screw extruder
to produce granular resins with non-fouling property from a
composition comprising said transparent grade thermoplastic and
then injection molding for product forming from pelletized granules
prepared early on. The transparent grade thermoplastic being
modified by the present method includes but not limited to
homopolymers, copolymers and blends of polyolefins, cyclic
polyolefins, acrylics, acetates, styrenics, polyesters, polyimides,
polyaryletherketones, polycarbonates, polyurethanes and
thermoplastic elastomers. In a preferred embodiment, the
transparent grade thermoplastics being modified by the present
method includes but not limited to poly(methyl methacrylate)
(PMMA), polystyrene (PS), polyethylene terephthalate (PET),
polycarbonate (PC), polymethylpentene (PMP), polysulfone, polyamide
(PA), polyvinyl chloride (PVC), styrene acrylonitrile (SAN),
styrene-methacrylate based copolymer, polypropylene based
copolymer, acrylonitrile butadiene styrene (ABS), polyimide (PI)
and cellulosic resins, methyl methacrylate butadiene styrene (MBS),
styrene ethylene butylene styrene block thermoplastic elastomer
(SEBS), etc. The method of the present invention also includes
blending one or more linear or multi-armed structures of non-ionic
surfactants as non-fouling modifiers, polyolefin elastomers and
polyurethane as impact modifiers, initiators, cross-linking agents,
nucleators, anti-oxidants and/or other auxiliary additives with the
transparent grade base thermoplastics prior to or during melt
processing of the base thermoplastics. When the afore-mentioned
transparent grade base thermoplastics, chemical modifiers and
auxiliary additives are added into the composition prior to said
melt processing by extrusion, they should be blended thoroughly and
then extruded to form a functional masterbatch. The formed
masterbatch is then further blended with the transparent grade base
thermoplastics for subsequent extrusion. Said melt processing can
be achieved on either a single-screw or twin-screw extruder
operated within a proper processing temperature range according to
different melting temperatures of the transparent grade base
thermoplastics and other main components for modifying the same,
e.g. from 150 to 250.degree. C. In a preferred embodiment, the
processing temperature of said melt processing ranges from 170 to
220.degree. C. After said melt processing, the melt processed
composition is then subjected to cooling, followed by pelletization
either separately from or continuously into the same extruder to
obtain either a solid standalone or a masterbatch concentrate
resin. The obtained solid or masterbatch concentrate resin is then
subjected to injection molding to reform into an article with
desired shape and dimension. Apart from injection molding, other
molding methods such as profile extrusion, blow molding, blow
filming, film casting, spinning and overmolding said standalone or
masterbatch concentrate resin on plastic substrates can also be
applied to reformation into an article.
[0018] The second aspect of the present invention relates to the
composition for forming a functional polymer or a masterbatch
concentrate resin. Said composition comprises said transparent
grade base thermoplastics (70-99 wt %) as described in the first
aspect and hereinafter, impact modifiers (0-30 wt %), chemical or
functional modifiers (0.5-10 wt %) including non-fouling modifiers
(0.1-5 wt %), and other additives (0.1-2 wt %) such as one or more
of initiators, cross-linking agents, nucleators, anti-oxidants,
and/or auxiliary additives (0.1-6 wt %). In the case that impact
modifiers are required, the weight percentage thereof ranges from
0.1-30 wt %. Said non-fouling modifiers include one or more of
linear and/or multi-armed structures of non-ionic surfactants. In a
preferred embodiment, said non-ionic surfactants include fatty
alcohol polyoxyalkylene ethers, polyoxyalkylene sorbitan/sorbitol
fatty acid esters, polyoxyalkylene alkyl amines, polyether glycols,
fatty acid alkanolamides and their derivatives. More specifically,
said non-ionic surfactants include polyethylene glycol (PEG)
sorbitol hexaoleate, AEO-5 and polyetheramine (e.g., JEFFAMINE.RTM.
D-230 or T-5000), wherein the PEG sorbitol hexaoleate has a
molecular weight ranging from 2,000 to 20,000 Da; the
polyetheramine has a molecular weight ranging from 200 to 6,000 Da.
Said impact modifiers include polyolefin elastomer, chlorinated
polyolefin, styrenic block copolymer, ethylene propylene rubber,
ethylene vinyl alcohol, acrylic resin, polyurethane, ethylene
copolymerized polar terpolymer, reactive modified elastomer. Said
initiators include an acid/base catalyst. More specifically, said
initiators include tosylic acid, tetramethylammonium hydroxide or
an organic peroxide, such as dicumyl peroxide,
bis(tert-butylperoxyisopropyl)benzene,
2,5-bis(tert-butylperoxy)-2,5-dimethylhexane and benzoyl peroxide,
which can exist in either standalone form or being supported on
filler particles. Said cross-linking agents are rubber
vulcanization agent. More specifically, said cross-linking agents
include triallyl isocyanurate, N,N'-m-phenylene dismaleimide and/or
sulfur. More specifically, said nucleators include MILLAD.RTM.
NX8000, MILLAD.RTM. 3988, ADK STAB NA-18 and/or ADK STAB NA-25.
More specifically, said anti-oxidants include butylated
hydroxytoluene, IRGANOX.RTM. 1010, IRGANOX.RTM. 1076, IRGANOX.RTM.
1098, IRGAFOS.RTM. 168 or IRGANOX.RTM. B 225. Said other auxiliary
additives include alumina nanoparticles, light stabilizers,
antiblocks, reinforcing fillers, optical brighteners, colorants,
flame retardants and deodorants. More specifically, said auxiliary
additives are alumina nanoparticles (AEROXIDE.RTM. Alu C). By the
present method and composition, deviation of optical transmittance
and haze of the transparent grade base thermoplastics is less than
20% at 1 mm thickness under the standard of ASTM D1003, meaning
that the transparency of the base thermoplastics is well maintained
while they also comply with various standards for different
applications including those plastics which are safe for food and
drinks because the modifiers and other main components added into
the composition for modifying the transparent grade base
thermoplastics according to the present invention enable biofouling
resistance and mechanical reinforcement of the end product or
molded article reformed therefrom against fluid biological matters,
such as microbes, mammalian cells, proteins, peptides, nucleic
acids, steroids and other cellular constituents.
[0019] These and other examples and features of the present
invention and methods will be set forth in part in the following
Detailed Description. This Summary is intended to provide an
overview of the present invention, and is not intended to provide
an exclusive or exhaustive explanation. The Detailed Description
below is included to provide further information about the present
disclosures and methods.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a schematic diagram showing an incubation protocol
for microbial adsorption tests on different molded circular plate
samples reformed by injection molding from the melt processed
composition comprising the modified transparent grade base
thermoplastics according to certain embodiments of the present
invention.
[0021] FIG. 2 is an illustration of the main components in the
composition for modifying the transparent grade base thermoplastics
according to certain embodiment of the present invention.
[0022] FIG. 3 is a schematic diagram showing a workflow of both
one-step and two-step methods for modifying the transparent grade
base thermoplastics according to certain embodiments of the present
invention.
[0023] FIG. 4 illustrates the test results of the molded plate
samples made of one of the modified transparent grade base
thermoplastics (MBS-M) against a control (MBS): (A) is an image of
molded MBS vs MBS-M plate samples placed on top of a piece of
paper; (B) shows microbial adsorption test of the molded MBS vs
MBS-M circular plate samples by an image taken from aerial view.
The left three sets of image represents the microbial adsorption of
MBS towards Escherichia coli, and the right three sets of image
represents the microbial adsorption of MBS towards Staphylococcus
Aureus.
[0024] FIG. 5 illustrates the test results of the molded plate
samples made of one of the modified transparent grade base
thermoplastics (PPM-M) against a control (PPM): (A) is an image of
molded PPM vs PPM-M plate samples placed on top of a piece of
paper; (B) is an image of molded PPM vs PPM-M plate samples after
being tested in a protein repellent assay according to the protocol
as described hereinafter; (C) shows microbial adsorption test of
the molded PPM vs PPM-M circular plate samples by an image taken
from aerial view. The left three sets of image represents the
microbial adsorption of PPM towards Escherichia Coli, and the right
three sets of image represents the microbial adsorption of PPM
towards Staphylococcus Aureus.
DETAILED DESCRIPTION OF THE INVENTION
[0025] References in the specification to "one embodiment", "an
embodiment", "an example embodiment", etc., indicate that the
embodiment described can include a particular feature, structure,
or characteristic, but every embodiment may not necessarily include
the particular feature, structure, or characteristic. Moreover,
such phrases are not necessarily referring to the same embodiment.
Further, when a particular feature, structure, or characteristic is
described in connection with an embodiment, it is submitted that it
is within the knowledge of one skilled in the art to affect such
feature, structure, or characteristic in connection with other
embodiments whether or not explicitly described.
[0026] Values expressed in a range format should be interpreted in
a flexible manner to include not only the numerical values
explicitly recited as the limits of the range, but also to include
all the individual numerical values or sub-ranges encompassed
within that range as if each numerical value and sub-range is
explicitly recited. For example, a concentration range of "about
0.1% to about 5%" should be interpreted to include not only the
explicitly recited concentration of about 0.1 wt. % to about 5 wt.
%, but also the individual concentrations (e.g., 1%, 2%, 3%, and
4%) and the sub-ranges (e.g., 0.1% to 0.5%, 1.1% to 2.2%, and 3.3%
to 4.4%) within the indicated range.
[0027] As described herein, the terms "a" or "an" are used to
include one or more than one and the term "or" is used to refer to
a nonexclusive "or" unless otherwise indicated. In addition, it is
to be understood that the phraseology or terminology employed
herein, and not otherwise defined, is for the purpose of
description only and not of limitation. Furthermore, all
publications, patents, and patent documents referred to in this
document are incorporated by reference herein in their entirety, as
though individually incorporated by reference. In the event of
inconsistent usages between this document and those documents so
incorporated by reference, the usage in the incorporated reference
should be considered supplementary to that of this document; for
irreconcilable inconsistencies, the usage in this document
controls.
[0028] In the methods of manufacturing described herein, the steps
can be carried out in any order without departing from the
principles of the invention, except when a temporal or operational
sequence is explicitly recited. Recitation in a claim to the effect
that first a step is performed, and then several other steps are
subsequently performed, shall be taken to mean that the first step
is performed before any of the other steps, but the other steps can
be performed in any suitable sequence, unless a sequence is further
recited within the other steps. For example, claim elements that
recite "Step A, Step B, Step C, Step D, and Step E" shall be
construed to mean step A is carried out first, step E is carried
out last, and steps B, C, and D can be carried out in any sequence
between steps A and E, and that the sequence still falls within the
literal scope of the claimed process. A given step or sub-set of
steps can also be repeated.
[0029] Furthermore, specified steps can be carried out concurrently
unless explicit claim language recites that they be carried out
separately. For example, a claimed step of doing X and a claimed
step of doing Y can be conducted simultaneously within a single
operation, and the resulting process will fall within the literal
scope of the claimed process.
Definitions
[0030] The singular forms "a," "an" and "the" can include plural
referents unless the context clearly dictates otherwise.
[0031] The term "about" can allow for a degree of variability in a
value or range, for example, within 10%, or within 5% of a stated
value or of a stated limit of a range.
[0032] The term "independently selected from" refers to referenced
groups being the same, different, or a mixture thereof, unless the
context clearly indicates otherwise. Thus, under this definition,
the phrase "X1, X2, and X3 are independently selected from noble
gases" would include the scenario where, for example, X1, X2, and
X3 are all the same, where X1, X2, and X3 are all different, where
X1 and X2 are the same but X3 is different, and other analogous
permutations.
DETAILED DESCRIPTIONS OF PREFERRED EMBODIMENTS
[0033] The present invention is not to be limited in scope by any
of the following descriptions. The following examples or
embodiments are presented for exemplification only.
[0034] The modification of the transparent grade base
thermoplastics according to the present invention can be processed
in either one-step or two-step method (FIG. 3). The transparent
grade base polymer is blended or reacted with chemical modifiers
and/or auxiliary additives either before or during extrusion to
create functional polymer (one-step) or masterbatch (two-step).
Representative examples of transparent grade base thermoplastics
include (-impact modified) polypropylene random (PPR) copolymers
and homopolymer (PPH) and several thermoplastic elastomers, such as
methyl methacrylate butadiene styrene (MBS), styrene ethylene
butylene styrene block thermoplastic elastomer (SEB S) and
polyurethane. Melt processing can be achieved on either
single-screw or twin-screw extruder operated with a proper
processing temperature window. The extruder can be equipped with a
cooling water bath and a pelletizer to obtain solid standalone or a
masterbatch concentrate resin prior to article reforming by
injection molding, for example. The processing temperature ranges
from 170 to 220.degree. C. for said transparent grade base
thermoplastics and other main components for modifying the
same.
[0035] One or more of linear and/or multi-armed structures of
non-ionic surfactants is/are selected as the non-fouling modifiers.
The non-ionic surfactants are chosen from fatty alcohol
polyoxyalkylene ethers, polyoxyalkylene sorbitan/sorbitol fatty
acid esters, polyoxyalkylene alkyl amines, polyether glycols, fatty
acid alkanolamides and their derivatives. Polyethylene glycol (PEG)
sorbitol hexaoleate, AEO-5 and polyetheramine (JEFFAMINE.RTM. D-230
or T-5000) are preferred non-fouling modifiers. Proper ratio and
combination of functional modifiers is key to the anti-biofouling
performance and retention of transparency of the transparent grade
base thermoplastic materials. Typical ratio is adjusted from 0.5 to
10% on a weight basis with respect to the total weight of the
composition. In a specific embodiment, thePEG sorbitol hexaoleate
has a molecular weight ranging from 2,000 to 20,000 Da (or 2 to 20
kDa). In another specific embodiment, said polyetheramine has a
molecular weight ranging from 200 to 6,000 Da.
[0036] Elastomers, such as polyolefin elastomer (POE) and
thermoplastic polyurethane (TPU), are chosen as impact modifiers
for modifying different transparent grade base thermoplastics.
VISTAMAXX.TM. and ENGAGE.TM. series POE and ELASTOLLAN.RTM. series
TPU are preferably suggested in this case. The suggested ratio
ranges from 0.1 to 30% by weight with respect to the total weight
of the composition in order to augment the impact strength.
Initiators and additives including tosylic acid,
tetramethylammonium hydroxide, and/or an organic peroxide, such as
dicumyl peroxide, bis(tert-butylperoxyisopropyl)benzene,
2,5-bis(tert-butylperoxy)-2,5-dimethylhexane and benzoyl peroxide,
in a weight percentage from 0.01% to 0.2% with respect to the total
weight of the composition are added to initiate covalent grafting
of the non-fouling modifiers onto the base polymers and/or impact
modifiers.
[0037] Other additives, such as anti-oxidant, cross-linking agent,
optical brightener, color masterbatch, odor absorbent, etc. are
chosen to control the appearance and the scent of the articles. The
anti-oxidant is preferred to be selected from butylated
hydroxytoluene, IRGANOX.RTM. 1010, IRGANOX.RTM. 1076, IRGANOX.RTM.
1098, IRGAFOS.RTM. 168 or IRGANOX.RTM. B 225 with a weight
percentage to the total weight of the composition from 0.1 to 2 wt
%. The cross-linking agent is preferred to be selected from
triallyl isocyanurate, N,N'-m-phenylene dismaleimide or sulfur with
a weight percentage to the total weight of the composition from 0
to 1 wt %. The initiator is preferred to be selected from dicumyl
peroxide, bis(tert-butylperoxyisopropyl)benzene or benzoyl peroxide
with a weight percentage to the total weight of the composition
from 0.01 to 0.2 wt %. The nucleator is preferred to be selected
from MILLAD.RTM. NX8000, MILLAD.RTM. 3988, ADK STAB NA-18 or ADK
STAB NA-25 with a weight percentage to the total weight of the
composition from 0 to 3 wt %. An auxiliary additive is preferred to
be alumina nanoparticles (AEROXIDE.RTM. Alu C) for enhancement of
the heat deflection temperature of base polymers with suggested
weight percentage to the total weight of the composition from 0.1
to 4 wt %.
[0038] During injection molding, the cycle time typically ranges
from a few seconds to 5 minutes for extremely thick-wall parts per
shot. On average, the injection falls in the range between 20 and
60 seconds for a well-designed mold and with a proper barrel and
mold temperature control. For instance, samples of dogbone tensile
test bars (Type I, ASTM D638), Izod impact test bars (ASTM D256),
flat circular plates with thickness of 1.5 mm and diameter of 60 mm
for optical haze/transmittance (ASTM D1003) and yellowness index
(ASTM E313) measurement and rectangular strips for heat deflection
temperature measurement (ISO 75) were produced on a 150-ton
injection molding machine in one single shot from the mold cavity.
Extrusive compounding was performed on a co-rotating twin-screw
extruder. The extruder had a screw diameter of 26 mm, a screw
length-to-diameter (L/D) ratio of 42:1 and an adjustable speed of
50-500 rpm. Its barrel was divided into 7 temperature zones, one of
which was located at the die orifice. The extruder was equipped
with a volumetric feeder composed of two separate compartments that
can feed two different types of raw materials at an equivalent
ratio.
[0039] Protein repellent assay procedures are herein described as
follows:
(a) 0.5 ml bovine serum albumin (BSA)/0.01 M phosphate-buffered
saline (0.1 g/ml, pH 7.4) protein solution is wetted on a flat
surface of a molded circular plate sample; (b) The protein solution
is placed at room temperature for half an hour for adsorption; (c)
The protein solution is withdrawn by aspiration; (d) Bradford
reagent (Cat. no. B6916, Sigma) of the same volume is deposited on
the affected area to stain the potentially protein-fouled sample
surface; (e) Color change of the Bradford reagent (from brown to
blue) qualitatively indicates the presence of adsorbed
proteins.
[0040] The incubation protocol for microbial adsorption tests on
the molded circular plate samples is herein described by the
schematic diagram in FIG. 1. The starting inoculum concentration of
E. coli (ATCC.RTM. 8739.TM.) and S. aureus (ATCC.RTM. 6538P.TM.)
was about 0.9.times.10.sup.6 and 8.times.10.sup.8 cells/ml in 1/500
NB solution (1/500 NB refers to the 500.times. diluted Nutrient
Broth with pH adjusted to 6.8-7.2) for challenging the sample
surface. Result of the adsorption tests are illustrated in the
following examples, and also in FIG. 4B and FIG. 5C.
EXAMPLES
[0041] The embodiments of the present invention can be better
understood by reference to the following examples which are offered
by way of illustration. The present invention is not limited to the
examples given herein.
Example 1
[0042] The modification of MBS, a highly transparent methyl
methacrylate butadiene styrene plastic compound, was rendered by
extrusive compounding of 94% MBS resin with 1% IRGANOX.RTM. B 225
and 5% AEO-5, a fatty alcohol ethoxylate, on a weight basis with a
processing temperature ranging from 180.degree. C. to 210.degree.
C. to obtain functional resin directly. The modified formulation
was re-pelletized as standalone resin (herein annotated as MBS-M)
that could be fed into an injection molding machine (with
processing temperature of 210.degree. C.) to obtain plastic samples
dictated by the mold tooling design. FIG. 4A shows that the molded
plate samples made of MBS-M according to the present method remain
essentially transparent. The characterization results are
summarized in Table 1. The impact strength of MB S-M was almost
double that of the base MBS plastic apart from the added microbial
repellent performance towards E. coli, a Gram-negative and S.
aureus, a Gram-positive bacteria. MBS-M passed ISO 22196's
antibacterial requirement by showing a nearly log-4 reduction of
bacterial counts after intimate contact with corresponding molded
plate samples with accredited report certificate. The plate samples
also indicated zero-growth ratings consistently over 21 days under
ASTM G21 and ASTM G22 standards with accredited report
certificates. Besides, the total aerobic microbial count and the
total combined molds and yeasts of the MBS-M pellets were less than
10 CFU/g according to USP <61> enumeration tests with
accredited report certificate.
TABLE-US-00001 TABLE 1 Izod % reduction % reduction Impact
Elongation Mechanical of E. coli of S. aureus Transparency Haze
Strength HDT at break Strength adsorption adsorption Sample (%) (%)
(KJ/m.sup.2) (.degree. C.) (%) (N/mm.sup.2) (%) (%) MBS 88.4 7.3
24.42 83.5 89.2 28.04 -- -- (Control) MBS-M 89.6 6.5 47.11 79.8
82.6 24.37 99% 96%
Example 2
[0043] The modification of PPR, a transparent polypropylene random
copolymer, was rendered by extrusive compounding of PPR resin with
30% polyolefin elastomer (VISTAMAXX.TM. 6202, ExxonMobil), 2%
JEFFAMINE.RTM. D-230, 2% poly(ethylene glycol) sorbitol hexaoleate,
3.75% alumina nanoparticles, 0.1% dicumyl peroxide, 0.05% triallyl
isocyanurate and 0.01% CBS-127, an optical brightener, on a weight
basis with processing temperature ranging from 170.degree. C. to
190.degree. C. to obtain a functional masterbatch concentrate
(herein, annotated as PPR-M) after pelletization. The masterbatch
was dry blended at a ratio of 1:1.5 w:w PPR with 0.1% overall by
weight of NX8000 and subsequently fed into an injection molding
machine (with processing temperature of 190.degree. C.) to obtain
plastic samples. The characterization results are summarized in
Table 2. Alumina nanoparticles helped to minimize the reduction of
heat deflection temperature (HDT) by counteracting the influence of
addition of polyolefin elastomer.
TABLE-US-00002 TABLE 2 Izod % reduction of % reduction Impact E.
coli of S. aureus Transparency Haze Strength HDT Yellowness Protein
adsorption adsorption Sample (%) (%) (KJ/m.sup.2) (.degree. C.)
Index repellency (%) (%) PPR 84.1 26.4 7.21 78.1 10.6 No -- --
(Control) PPR-M 82.5 28.2 15.42 77.6 11.9 Yes >99% >99%
Example 3
[0044] The modification of PPM, an impact-modified polypropylene
compound, was rendered by extrusive compounding of PPM resin with
2% JEFFAMINE.RTM. D-230, 2% AEO-5, 1% MILLAD.RTM. NX8000, 0.1%
dicumyl peroxide and 0.05% triallyl isocyanurate with processing
temperature ranging from 170.degree. C. to 190.degree. C. to obtain
a functional masterbatch concentrate (herein, annotated as PPM-M)
after pelletization. The masterbatch was dry blended at a ratio of
1:1.5 w:w PPM with 0.1% overall by weight of IRGANOX.RTM. 1010 and
0.1% overall by weight of IRGAFOS.RTM. 168 for injection molding
with processing temperature of 190.degree. C. FIG. 5A shows that
the molded plate sample of PPM-M is essentially transparent; The
characterization results are summarized in Table 3, and also in
FIG. 5B and FIG. 5C. FIG. 5B shows that when BSA protein solution
added on the molded plate sample made of PPM-M effectively repelled
protein adsorption onto the surface. Solution of bovine serum
albumin (BSA), a protein molecule, was dropped on the sample
surface for five minutes prior to aspiration. The Bradford Reagent
(Coomassie Blue), which could react with the nitrogen of the BSA,
was then dropped on the sample surface. The sample surface where
BSA was adsorbed on would change Bradford Reagent from brown into
blue color, indicating the adsorption of protein on the surface.
Those surfaces repelled protein adsorption would keep Bradford
reagent brown, indicating the protein repellency of sample surface.
FIG. 5C shows that E. coli and S. aureus are substantially repelled
(>99%) by the molded plate sample made of PPM-M. PPM-M passed
ISO 22196 by showing a nearly log-4 reduction of bacterial counts
after intimate contact with corresponding molded plate samples with
accredited report certificate. PPM-M also passed ASTM G21 and ASTM
G22 by indicating zero-growth ratings consistently over 21 days
with accredited report certificate. Besides, PPM-M showed zero
rating meaning a complete resistance against the pink staining by
Streptoverticillium reticulum with accredited report certificate.
Under ASTM E2149, a dynamic shake flask antibacterial test, PPM-M
molded plates showed 100% and 90.7% reduction of E. coli and S.
aureus respectively upon 24 hours of incubation with accredited
report certificate. Under ISO 20645, an agar diffusion plate test,
nil growth of E. coli, S. aureus, Salmonella typhimurium,
Campylobacter jejuni under samples were observed while zero zone of
inhibition were obtained with accredited test certificate, thus
implicative of no free biocide leaching. The samples were
antibacterial towards Klebsiella pneumoniae by showing 72%
reduction of counts after 24 hours of contact even with agar
slurries under ASTM E2180 with accredited report certificate.
Furthermore, the total aerobic microbial count and the total
combined molds and yeasts of the PPM-M pellets were less than 10
CFU/g according to USP <61> enumeration tests with accredited
report certificate. The samples also complied with the overall
migration limits for the three types of stimulants used (3% w/v
acetic acid, 10% v/v ethanolic solution and rectified olive oil) at
70.degree. C. for 2 hours as well as the two types of stimulants
(3% w/v acetic acid, 10% v/v ethanolic solution) at 100.degree. C.
for 4 hours, as set out by EU No. 10/2011 as well as conformed to
US FDA 21 CFR 177.1520(d), Items 3.1a and 3.2a as a polypropylene
copolymer for intended uses in food contact articles. Relevant
certificates issued from accredited agency were available.
Furthermore, the total aerobic microbial count and the total
combined molds and yeasts of the PPM-M pellets were less than 10
CFU/g according to USP <61> enumeration tests with accredited
report certificate. The samples were also proven to be
biocompatible under ISO 10993-4 (both direct contact and extract
method) hemolysis tests and ISO 10993-5 (MEM elution method)
cytotoxicity tests with accredited report certificates. Last but
not least, an even slight increase of the impact strength of the
base PPM plastic after modification was resulted.
TABLE-US-00003 TABLE 3 Izod % reduction of Impact Repellency E.
coli % reduction of Transparency Haze Strength HDT towards
adsorption S. aureus adsorption Sample (%) (%) (KJ/m.sup.2)
(.degree. C.) Protein (%) (%) PPM 81.9 23.7 44.55 71.8 No NA NA
(Control) PPM-M 82.6 20.3 47.46 73.1 Yes >99% >99%
Example 4
[0045] The modification of PPH, a transparent polypropylene
homopolymer, was rendered by extrusive compounding of PPH resins
with 30% VISTAMAXX' 3980FL, 2% JEFFAMINE.RTM. D-230, 2%
poly(ethylene glycol) sorbitol hexaoleate, 0.1% dicumyl peroxide,
0.05% triallyl isocyanurate and 3.75% alumina nanoparticles with
processing temperature ranging from 180.degree. C. to 200.degree.
C. The reformulated pellets were then directly subjected to
injection molding (with processing temperature of 200.degree. C.)
to get molded samples. The characterization results are summarized
in the table below. The impact strength increased significantly by
more than 120% with respect to the base PPH plastic. Alumina
nanoparticles were added to keep the heat deflection temperature
(HDT) of PPH as high as about 80.degree. C. for warm water
contacting applications. Characterization results are summarized in
Table 4.
TABLE-US-00004 TABLE 4 % Izod % reduction reduction Impact
Repellency of E. coli of S. aureus Yellowness Transparency Haze
Strength HDT towards adsorption adsorption Sample Index (%) (%)
(KJ/m.sup.2) (.degree. C.) Protein (%) (%) PPH 10.06 83.9 17.0 4.49
98.9 No NA NA (Control) PPH-M 15.83 81.6 29.5 9.94 79.2 Yes >99%
>99%
Example 5
[0046] The modification of SEBS, a styrene ethylene butylene
styrene block thermoplastic elastomer, was rendered by extrusive
compounding of SEBS resins with 0.1% tosylic acid, 2.5%
polyethylene glycol (average molecular weight of 10,000) and 2.5%
AEO-5 on a weight basis with processing temperature ranging from
170.degree. C. to 220.degree. C. The reformulated pellets were
directly subjected to injection molding (with a processing
temperature of 210.degree. C.) to obtain molded samples.
Characterization results are summarized in Table 5
TABLE-US-00005 TABLE 5 % reduction % reduction Repellency of E.
coli of S. aureus Yellowness Transparency Elongation at towards
adsorption adsorption Sample Index (%) Haze (%) break (%) Protein
(%) (%) SEBS 8.12 82.5 20.2 420% No NA NA (Control) SEBS-M 10.03
79.2 26.4 400% Yes >99% >98%
* * * * *