KR20070112112A - Polyhedral oligomeric silsesquioxanes and polyhedral oligomeric silicates barrier materials for packaging - Google Patents

Abstract

A method for barrier property enhancement using silicon containing agents and in situ formation of nanoscopic glass layers on polymer surfaces. Nanostructured chemicals such as polyhedral oligomeric silsesquioxane (POSS) are added to polymers, followed by in situ surface oxidation to form a glass layer.

Description

POLYHEDRAL OLIGOMERIC SILSESQUIOXANES AND POLYHEDRAL OLIGOMERIC SILICATES BARRIER MATERIALS FOR PACKAGING

This application claims the benefit of US Provisional Patent Application No. 60 / 634,495, filed December 8, 2004.

The present invention relates generally to methods of enhancing the barrier properties of natural polymers such as polyethylene, polypropylene, polyamides, polyester terephthalates, and cellulose and polylactic acid polymers. More specifically, the present invention provides polyhedral oligomeric silsesquioxanes (POSS) and for the gas and moisture barrier control in multilayered polymer laminate packaging or bottles for food, beverage, pharmaceutical and medicine. The incorporation of nanostructured chemicals, such as polyhedral oligomeric silicates (POS), is a concern.

Applications of such materials include replacing metalized polymer packages, replacing metal cans, and replacing packages containing discreet adhesive layers and discreet silica layers.

The present invention provides polyhedral oligomeric silsesquioxanes, silsesquioxanes, polyhedral oligomer silicates, as alloyable agents in polypropylene (PP), polyamide (PA), polyester ephthalate (PET), Silicates, silicones or metalized polyhedral oligomeric silsesquioxanes, silsesquioxanes, polyhedral oligomeric silicates, silicates, silicones. Polyhedral oligomeric silsesquioxanes, silsesquioxanes, polyhedral oligomeric silicates, silicates, silicones or metallized-polyhedral oligomeric silsesquioxanes, silsesquioxanes, polyhedral oligomeric silicates, silicates, silicones are then silicon-containing agents ( Note that it is referred to as Silicon Containing Agents.

Silicon-containing agents have been used to complex metal atom (s) as previously reported in US Pat. No. 6,441,210 (Abbenhuis et al.). As discussed in US Pat. No. 6,716,919 and WO 01/72885 PCT / US01 / 09668, these silicon-containing agents are used to uniformly disperse and alloy silicon and metal atoms at the nanoscopic level with polymer chains. Useful for Silicon containing agents can be converted to form a glass like silica layer in the presence of atomic oxygen. The use of such silicon containing agents to form oxide protective glass layers has been discussed in US Pat. No. 6,767,930. The use of such silicon containing agents to form fire protective surface char coatings has been described in US Pat. No. 6,362,279. Silicon-containing agents have also been described as useful for forming permeable porous membranes as discussed in US Pat. No. 6,425,936.

In view of the above, it has surprisingly been found that such silicon-containing agents are also useful for forming gas and liquid barriers in multilayered thin film packaging products. With this ability, silicon-containing agents are effective on their own when alloyed into polymers, but nanoscopically thin glass barriers when exposed to hot oxidizing gases such as oxygen plasma, ozone, oxidizing flame, or air. Is particularly effective at forming in situ.

Advantages of using silicon-containing agents include the ability of the silicon-containing agent to reduce permeability by reducing or plugging the free volume in the polymer, or when converted to nano-thin glass layers, Permeability is reduced due to the impermeability of the glass layer. Other advantages include: non-detection, toughness, and flexibility of the nanoscopic barrier to the human eye, resulting in storage suitability on the roll and thin film packaging, radiation absorption, moisture and gas Permeability, direct printability, stain resistance, environmental degradation resistance, chemical degradation resistance, scratch resistance, low cost and lighter than glass, careful composition discreet good adhesion between polymer and glass due to removal of compositional bondlines, and their replacement with compositionally graded material interfaces, improved mechanical properties (heat distortion, creep) , Compression set, shrinkage, modulus, hardness and abrasion resistance, etc., and improved physical properties (electrical conductivity, thermal conductivity and Fire resistance). As nanoscopic silicon agents are used in dental adhesives, better adhesive quality is also a viable advantage. Finally, silicon containing metals can provide stability to the polymer by absorbing photon and particle radiation that, if not absorbed, can damage the polymer and accelerate the degradation of the polymer. All of these factors contribute to packaging materials with better barrier and transparency properties than those obtained using prior art methods.

Many prior art methods are known for making packages having low barrier properties against gas and moisture. Such methods include depositing metal and thin glass coatings on polymers such as those described in US Pat. No. 6,720,097. While this approach is effective, extensive high speed molding and extrusion processing is not easy. In addition, this method is poor in interfacial bonding between glass or metal and polymer layers. Popular prior art approaches have also included the incorporation of two-dimensional platelet materials such as clay, mica, talc, glass flakes, carbon mesophase and tubes (US Pat. 6,376,591 and 6,387,996). This prior art lacks the ability to incorporate additives with sufficiently high uniformity to provide a high barrier while maintaining optical transparency. Thus, tradeoffs in barrier levels are allowed to accommodate transparency and decorative appearance. Another limitation of the latter approach was the use of naturally derived fatty surfactants such as tallow to make the two-dimensional platelet material compatible with the polymer layer. While this approach is cost effective, it introduces the potential into packaging materials for biologically active contaminants that may render the packaging material unsuitable for food and sterile medical products.

The silicon containing agents most useful for this operation are best exemplified by those based on inexpensive silicon compounds such as silsesquioxanes, polyhedral oligomeric silsesquioxanes, and polyhedral oligomeric silicates. 1 illustrates several representative examples of silicon compounds, including siloxane, silsesquioxane and silicate examples. The R groups in this structure can range from H to alkanes, alkenes, alkynes, aromatics, and substituted organic systems including ethers, acids, amines, thiols, phosphates, and halogenated R groups. In addition, the structure and composition is intended to include metallized derivatives in which metals from high to low Z can be incorporated into the structure.

Silicon-containing agents all share a common hybrid (ie, organic-inorganic) composition in which the internal backbone is mainly composed of inorganic silicon-oxygen bonds. Incorporation of such agents provides a barrier to moisture and oxygen through the blocking of amorphous regions, and free volume is contained within the solid state structure of the polymer. Barrier properties can be further improved by mild in situ oxidation of nanoscopic silicon entities in nano-thin silica glass. The vitrification treatment can be carried out during or after the peeling treatment. The exterior of the nanostructure is covered with both reactive and non-reactive organic functional groups (R), which ensures compatibility and tailorability with the organic polymer of the nanostructure. These and other properties of nanostructured chemicals are discussed in detail in US Pat. No. 5,412,053 and US Pat. No. 5,484,867, all of which are incorporated herein by reference in their entirety. These nanostructured chemicals are low density and may range in diameter from 0.5 nm to 5.0 nm.

The present invention describes a novel series of polymer additives and their utility in the formation of gas and moisture barriers within polymers and on polymer surfaces. The resulting nano-alloyed polymers, alone or in combination with other polymers, or in combination with macroscopic reinforcements such as fibers, clays, glass, metals, minerals, and other particulate fillers, inks and pigments, are entirely useful. Nano-alloyed polymers are particularly useful for making multilayered packages having improved oxygen and moisture barrier properties, printability, flame resistance, acid resistance, and base resistance. Preferred compositions presented herein include two main material combinations: (1) nanostructured chemicals, nanostructured oligomers, or silicones, polyhedral oligomer silsesquioxanes, polysilsesquioxanes, polyhedral oligomeric silicates, polysilicates, Silicon-containing agents including nanostructured polymers from the chemical class of polyoxometalates, carboranes, boranes; And (2) artificial thermoplastic polymers such as polypropylene, polyamides and polyesters.

A preferred method of incorporating nanostructured chemicals in thermoplastics is carried out by melt mixing the silicon containing agent in the polymer. All forms and techniques of blending, including melt blending, dry blending, solution blending, reactive and non-reactive blending, are also effective.

In addition, selective incorporation and maximum loading levels of the silicon-containing agent into a particular polymer can be achieved using a silicon-containing agent having a chemical potential (miscibility) compatible with the chemical potential of the region in the polymer to be alloyed. Because of their chemistry, the silicon-containing agents can be tailored to show suitability or incompatibility with selected sequences and segments in polymer chains and coils. Due to their physical size in combination with their tailorable suitability, silicon-containing agents based on nanostructured chemicals are selectively incorporated into the polymer to control the dynamics of the coils, blocks, domains and segments and then It may work in favor of physical properties.

A particular advantage of incorporating nanoscopic silicon-containing agents as barrier materials is the use of low loading them to plug accessible free volumes in the polymer. Permeation (P) is controlled by the formula P = DS, where D is the diffusion coefficient and S is the solubility of the components in the material. In barrier applications, nanoscopic silicon agents may replace gas molecules in the polymer, thereby reducing the solubility of the gas in the polymer. In addition, nanoscopic silicon agents may occupy an accessible volume available for the diffusion of the gas, thus reducing overall permeability.

The formation of glass glazing in situ on the molded article from the polymer alloyed with the silicon-containing agent is performed by exposing the article to oxygen plasma, ozone, or other highly oxidizing media. These chemical oxidation methods are preferred because this is the current industrial treatment and does not heat the polymer surface. There is no topological constraint or decorative restriction on the molded article. After treatment, the portion includes a nanometer thick surface glass layer. The most effective and therefore preferred oxidation method is oxygen plasma. However, for alloys in which R on the silicon-containing agent is H, methyl or vinyl, the alloy can be converted to glass upon exposure to ozone, peroxide or even hot vapor. A reliable alternative to the method is to use an oxide flame. The method is selected according to the chemicals, the polymer alloy system, the loading level of the silicon containing chemicals, the surface segregation of the agent, the thickness of the desired silica surface, and the manufacturing considerations. Nanoscopic level dispersion of the silicon containing agent in the polymer is shown in FIG. 2.

Upon surface exposure to an oxidation source, depending on the oxidation state used, a nano-thin glass layer of 1-500 nm will be obtained, preferably a nano-thin glass layer of 1-100 nm. will be. The thickness of the formed layer may vary depending on the desired properties of the glass layer ( eg, impermeability, scratch resistance, transparency, radiation attenuation, etc.). If the silicon-containing agent included a metal, the metal would also be incorporated into the glass layer. Advantages resulting from the formation of nanocrystalline glass surface layers include barrier properties, improved chemical properties, improved oxidative properties, flammability, improved electrical properties, improved printability, improved flame resistance and improved scratch resistance to gases and liquids. This includes. In addition, the nano-thin silica layer can be seamlessly integrated with the bulk virgin polymer, malleable, stored on rolls and laminated in a multi-layer package.

Definition of Expression Display of Nanostructures

For the purpose of understanding the chemical composition of the present invention, the formula designation of silicon-containing agents and in particular polyhedral oligomeric silsesquioxane (POSS) and polyhedral oligomeric silicate (POS) nanostructures is defined as follows.

Polysilsesquioxane of the formula [RSiO _{1 .5]} The materials shown in _∞, ∞ is molar degree of polymerization (molar degree of polymerization) and, R is an organic substituent (Additionally, alcohols, esters, amines, ketones, olefins , H, siloxy, cyclic, or linear aliphatic, or aromatic groups, which may contain reactive functional groups such as ethers or may contain halogens. The polysilsesquioxanes can be homomoleptic or heteroleptic. Homoleptic systems include only one R group, whereas heteroreptic systems include one or more R groups.

POSS and POS nanostructure compositions are represented by the following formulas:

Homo reptik compositions _{[(RSiO 1 .5) n]} Σ #

Heteroaryl reptik compositions _{[(RSiO 1 .5) n (} R'SiO 1 .5) m] Σ # ( However, R ≠ R ')

Heterofunctionalized Heteroreptic Compositions

_{[(RSiO 1 .5) n (} RSiO 1 .0) m (M) j] Σ #

Functionalized heteroaryl reptik compositions _{[(RSiO 1 .5) n (} RXSiO 1 .0) m] Σ # ( where, R groups may not be equal or equivalent)

All of R are as defined above and X is OH, Cl, Br, I, alkoxide (OR), acetate (OOCR), peroxide (OOR), amine (NR ₂ ) isocyanate (NCO), and R Including but not limited to. The symbol M represents metal elements in the composition comprising high and low Z metals, and in particular Al, B, Ce, Ni, Ag, Ti. The symbols m, n, and j represent the stoichiometry of the composition. The symbol Σ indicates that the composition forms a nanostructure, and the symbol # indicates the number of silicon atoms included in the nanostructure. The value of # is generally the sum of m + n, n is generally 1 to 24, and m is generally 1 to 12. It should be noted that ∑ # simply represents the overall nanostructure of the system (also known as cage size) and should not be confused with a multiplier to determine stoichiometry.

Detailed description of the invention

The present invention teaches the use of silicon-containing agents as alloying agents for the design and manufacture of polymers and polymer laminate packaging having barrier properties to oxygen and water. It is recognized that additional barriers can be obtained by in situ formation of the glass layer on the polymeric material through in situ oxidation of the nanoscopic silicon-containing agent.

Keys that can functionalize silicon-containing agents, such as nanostructured chemicals, in their capacity include: (1) the unique size of silicon-containing agents in terms of polymer chain dimensions, and (2) The ability of silicon-containing agents to be adapted to the polymer system and to be uniformly dispersed at the nanoscopic level, in order to overcome the repulsive forces that promote exclusion and non-compliance of the nano-reinforcement, (3) vitrified upon exposure to hybrid compositions and selective oxidants The ability of the silicon-containing agent, and (4) the ability to chemically incorporate metals into and from the corresponding glass made from the silicon-containing agent. Therefore, the requirements for selecting silicon-containing agents for permeability control and vitrification include nanosizes of nanostructured chemicals, distribution of nanosizes, and suitability and disparities between nanostructured chemicals and polymer systems, Loading level, desired silica layer thickness, and optical and physical properties of the polymer.

Silica agents such as the polyhedral oligomeric silsesquioxanes shown in FIG. 1 are available as solids and oils and with and without metals. Both forms can be dissolved in the molten polymer or solvent, reacted directly with the polymer or used as a binder material per se. For POSS, dispersion appears to be thermodynamically governed by the free energy of the mixing equation (ΔG = ΔH−TΔS). The nature of the R groups and the ability to react or interact with the polymers in the reactor on the POSS cage contribute significantly to the advantageous enthalpy (ΔH) term and entropy due to the monoscopic cage size and the distribution of 1.0. The term DELTA S is very advantageous.

In addition, the thermodynamic forces driving the dispersion contribute to the dynamic mixing forces such as occur during high shear mixing, solvent blending or alloying. In addition, the kinetic dispersion also helps the ability of some silicas to melt at or near the processing temperatures of most polymers.

Thus, by adjusting the chemical and processing parameters, the polymer can be nano-reinforced and alloyed to the 1.5 nm level for virtually any polymer system, as shown in FIG. 2. In addition, silica-containing agents can be used in combination with macroscopic fillers to resemble the desired benefits for enhancement of physical properties, barrier, flame retardant, acid resistance, base resistance, and radiation absorption. Thus, absorption of damaging radiation through metallized silica containing agents such as nickel, titanium, cerium, or boron is possible (FIG. 3). Such metalized systems are very useful for stabilizing polymers against environmental degradation and content degradation such as vitamins, flavors, colorants, and other nutrients.

The present invention demonstrates that barrier property enhancement can be achieved by directly blending silicon-containing agents, preferably nanostructured chemicals, directly into the polymer. This greatly simplifies the processing of the prior art.

In addition, silicon-containing agents, such as nanostructured chemicals, have a spherical form, such as molecular spheres (via single crystal X-ray diffraction studies), and, because of their dissolution, are also effective in reducing the viscosity of the polymer system. This is beneficial for the processing, molding, or coating of articles using such nano-alloyed polymers, with the added benefit of strengthening the individual polymer chains due to the nano nature of the chemicals. Subsequent exposure of the nano-alloyed polymer to an oxidant results in the formation of nano-glass in situ on the exposed surface. 4 shows the oxidation of silicon, such as silsesquioxane, into the glass. Exposure of the nano-alloyed polymer to the source of oxidation breaks the silicon-R bonds and the R groups are lost as volatile reaction byproducts, while the valences to silicon are maintained by the bridging of oxygen atoms together through the fusion of the cage and An equivalent is made. Thus, such glass surface layers are readily formed in situ by using nanostructured silicon-containing agents. The prior art requires the use of a secondary coating or deposition method that forms a micron thick glass layer on the surface.

The nano-dispersed nature of the silica-containing agent in and throughout the polymer is combined with the ability to form the glass layer directly on the polymer surface of the molded article, thereby reducing processing costs due to reduced time and materials and simplified packaging. It offers a great advantage (Fig. 5). There is a wide range of multilaminate polymer packaging architectures. Thus, Figures 4 and 5A-5F are intended to illustrate the incorporation into the current packaging design of the present invention in a non-limiting manner. The loading level of the silicon-containing agent can be 0.1% to 99% by weight, with a preferred range of 1% to 30% by weight.

1 shows a representative structural example of a non-metalized silicon containing agent.

2 shows the ability to uniformly disperse the nanostructured silicon agent to 1-3 nm levels at the surface and thickness of the polymer.

3 shows the ability of metallized silicon to selectively absorb damaging radiation.

4 shows a chemical treatment in which the silicon-containing agent is oxidatively converted to a fused, nano-thin glass layer.

5A-5F illustrate a preferred method of incorporating nanostructured silicon-containing agents into a plastic multilaminate package.

General Processing Variables Applicable to All Processing

As is common in chemical treatments, there are a number of variables that can be used to adjust the purity, selectivity, rate and mechanism of any treatment. Variables that affect the treatment for incorporation of silicon-containing agents into plastics include the size and polydispersity and composition of the nanoagents. Similarly, between the silicon-containing agent and the polymer, the molecular weight, polydispersity and composition of the polymer system must also be harmonized. Finally, tools of the trade that can affect the loading level and degree of enhancement due to the incorporation of kinetics, thermodynamics, processing aids, and fillers used during compounding or blending processing do. Blending treatments such as melt blending, dry blending and solution mixing blending are all effective for mixing and alloying nanoscopic silicas into plastics.

Alternative method: solvent assisted formulation. The silicon-containing agent is added to a container containing the desired polymer, prepolymer or monomer and an amount of organic solvent (e.g. hexane, toluene, dichloromethane, etc.) or fluorine is sufficient to form one homogeneous phase. Can be dissolved in the solvent. The mixture is then stirred at a sufficient temperature under high shear to ensure proper mixing for 30 minutes, after which the volatile solvent is removed and recovered through a similar form of treatment including vacuum or distillation. Note that supercritical fluids such as CO ₂ may be used as substitutes for flammable hydrocarbon solvents. The resulting composition can then be used for direct or subsequent treatment.

Example 1 Permeability Barriers

The examples provided below are not intended to limit specific material combinations or conditions.

A typical oxygen plasma treatment is one to five minutes at 100% power. A typical ozonolysis treatment is performed for 1 second to 5 minutes with ozone administered at 0.03 equivalents of O ₃ per vinyl group via CH ₂ Cl ₂ solution. Typical steaming treatment is from 1 second to 5 minutes. Typical flame oxidation treatments are from 1 second to 5 minutes.

Example  2. Improved packaged food

The following describes the advantages observed through incorporation into the food packaging of the present invention.

Example  3. Packaging performance based on design

A series of silicon-containing additives include silicone and epoxy thermosets, polyolefins, It was incorporated into polycarbonate thermoplastics and their absorption characteristics were measured for the incident dosages of UV-Vis, neutrons, gamma and low energy photons. The main advantage of low Z-alloyed polymers was observed for low energy photons (<1000 ev). Improvements occur due to the increased electron density in the material that provides shielding against the damaging effects of incident radiation. The main advantage of the high Z alloyed polymer was to prevent high energy UV radiation from damaging and decolorizing silicon and polycarbonate. Improvements occur because the UV absorbing properties of the glass layer extend to the 90-390 nm range.

While specific representative embodiments and detailed descriptions have been presented for the purpose of illustrating the invention, it will be apparent to those skilled in the art that various changes may be made to the methods and apparatus disclosed herein without departing from the scope of the invention as defined in the claims. will be.

Claims (27)

A method of forming an in situ of a glass layer on a polymer surface, (a) incorporating the nano-dispersed silicon-containing agent into the polymer; And (b) oxidizing the surface of the polymer to form a glass layer. The method of claim 1, Incorporating a mix of different silicon containing agents into the polymer. The method of claim 1, And wherein said polymer is selected from the group consisting of polyethylene, polypropylene, polyamide, and an adhesive. The method of claim 1, Wherein said polymer is a polymer coil, a polymer domain, a polymer chain, a polymer segment, or a mixture thereof. The method of claim 1, And the silicon-containing agent strengthens the polymer at the molecular level. The method of claim 1, Wherein said incorporation is non-reactive. The method of claim 1, Wherein said incorporation is reactive. The method of claim 1, Wherein the physical properties of the polymer are improved as a result of the incorporation of the silicon-containing agent into the polymer. The method of claim 1, Wherein the physical properties of the polymer are improved as a result of in situ formation of the glass layer. The method of claim 8, The physical properties include adhesion, water repellency, density, glass transition, viscosity, melt transition, storage modulus, relaxation, stress transfer, wear resistance, gas permeability, moisture permeability, adsorption, biocompatibility , Chemical resistance, porosity, radiation absorption, and optical quality. The method of claim 9, The physical properties include adhesion, water repellency, density, glass transition, viscosity, melt transition, storage modulus, relaxation, stress transfer, abrasion resistance, gas permeability, moisture permeability, adsorption, biocompatibility, chemical resistance, porosity, radiation absorption, and optical quality In situ forming a glass layer on the polymer surface. The method of claim 8, Wherein said incorporation step is performed in combination with one or more other fillers or additives. The method of claim 9, Wherein said incorporation step is performed in combination with one or more other fillers or additives. In the method of improving the barrier properties of multi-layer packaging, (a) incorporating the nanodispersed silicon-containing agent into a polymer selected from the group consisting of polyethylene, polypropylene, and polyamide; And (b) oxidizing the surface of the polymer to form a glass layer. The method of claim 1, Incorporating a mix of different silicon-containing agents into the polymer. The method of claim 14, Wherein said polymer is a polymer coil, a polymer domain, a polymer chain, a polymer segment, or a mixture thereof. The method of claim 14, And wherein said silicon-containing agent strengthens said polymer at the molecular level. The method of claim 14, And wherein said incorporation is non-reactive. The method of claim 14, And wherein said incorporation is reactive. The method of claim 14, Wherein the physical properties of the polymer are improved as a result of the incorporation of the silicon-containing agent into the polymer. The method of claim 14, Wherein the physical properties of the polymer are improved as a result of in situ formation of the glass layer. The method of claim 20, The physical properties include adhesion, water repellency, density, glass transition, viscosity, melt transition, storage modulus, relaxation, stress transfer, wear resistance, gas permeability, moisture permeability, adsorption, biocompatibility, chemical resistance, porosity, radiation absorption and optical quality. Method for improving the barrier properties of a multi-layer package, characterized in that it is selected from the group consisting of. The method of claim 21, The physical properties include adhesion, water repellency, density, glass transition, viscosity, melt transition, storage modulus, relaxation, stress transfer, abrasion resistance, gas permeability, moisture permeability, adsorption, biocompatibility, chemical resistance, porosity, radiation absorption, and optical quality Method for improving barrier properties of multi-layer packaging, characterized in that it is selected from the group consisting of. The method of claim 20, Wherein said incorporation step is performed in combination with one or more other fillers or additives. The method of claim 21, Wherein said incorporation step is performed in combination with one or more other fillers or additives. The method of claim 14, And the silicon-containing agent comprises a metal. The method of claim 28, And said metal slows degradation of said polymer or contents of said package.

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