KR100507792B1 - Lithium and potassium copolysilicate barrier coatings - Google Patents

Abstract

New coating solutions and methods for providing improved vapor, gas, or aromatic permeability to coated polymer substrates are provided. These methods and solutions use lithium-potassium copolysilicates having the formula (Li ₂ O) _x (K ₂ O) _1-x (SiO ₂ ) _y . For this method, if x is less than 1, y is between 1 and 10, and if x is 1, y is greater than 4.6. For a fresh coating solution, if x is less than 1, y is greater than 4.6 and if y is from 1 to 10, x is greater than 0.5.

Description

Lithium and Potassium Copolysilicate Barrier Coatings {LITHIUM AND POTASSIUM COPOLYSILICATE BARRIER COATINGS}

FIELD OF THE INVENTION The present invention relates generally to barrier coatings for polymeric articles, based on silicates.

Cross Reference to Other Applications

This application is partly filed in US Patent Application No. 08 / 652,287, filed May 22, 1996.

Alkali metal polysilicates have long been known as protective coatings that alter the permeability or surface properties of polymer films and other articles. Polysilicates of lithium (Li), sodium (Na), and potassium (K) are known to be effective as protective coatings for various surfaces. For example, Japanese Patent Publication No. H7-18202, published January 20, 1995, includes a mixture of an aqueous sodium or potassium silicate solution and an aqueous lithium silicate solution having a ratio of sodium or potassium silicate to lithium silicate of 1 to 3. Insoluble coatings and binders for use in metals, synthetic resins, glass, wood, cement and the like are mentioned.

As another example, Canadian Patent No. 993,738 to Hecht and Iler describes a gas and liquid impermeable coating for polymer substrates comprising lithium polysilicate having a molar ratio of SiO ₂ to Li ₂ O of about 1.6 to 4.6. It is. However, it is known that polymeric articles become opaque after certain polysilicate coatings have been bonded. The tendency of the sodium (Na) polysilicate coating to effloresce, ie, to be covered by powder crystalline material by exposure to the atmosphere has been documented [Weldes and Lange, Ind. Eng, Chem., 61 (4): 28-44 (1969). This property was similarly observed by the inventors for lithium polysilicate coatings. In contrast, pure potassium polysilicate coatings are not weathering, but at a relative humidity of 50% or higher, the barrier performance is significantly reduced. Pure lithium polysilicate coatings, on the other hand, show little or no barrier performance at the same relative humidity range.

In the field of barrier coatings, there is a need for coating compositions and methods that overcome the above disadvantages and can be widely used as vapor, gas and / or fragrance barriers for polymeric articles such as packaged products.

In one aspect, the present invention provides a method of providing improved vapor, gas, and odor barrier properties to a polymer substrate at high relative humidity. The method is formula (Li ₂ O) _x (K ₂ O) _1-x (SiO ₂ ) _y {x is the mole fraction of Li ₂ O in the bonded alkali metal oxide (M ₂ O), y is SiO ₂ : M Coating the substrate with a barrier coating solution comprising lithium-potassium copolysilicate of ₂ 0 molar beam}. In this method, x ranges from 0 to 1, including 0 and 1. In particular, y is 1 to 10 if x is less than 1, and if x is 1, y is greater than 4.6. (I.e. x is between 0 and 1 and y is 1 to 10, corresponding to claims 2, 17 and 22)

In another aspect, the present invention provides a novel vapor, gas and / or fragrance barrier coating solution for a polymeric article comprising a copolysilicate of the above formula, which overcomes the drawbacks in the art. The aforementioned coating solution is represented by the above formula except that y is greater than 4.6 if x is less than 1, and x is greater than 0.5 if y is 1 to 10. ( I.e. x is between 0 and 0.5, y is greater than 4.6 and up to 10, or x is 0.5 to less than 1, y is 1 to 10, corresponding to claims 1 and 16). The coating solution is colorless or transparent Preferably, it may comprise a suitable surfactant.

Another aspect of the invention provides a polymeric article coated with the barrier coating solution described above. The article may typically be a polymer film or membrane, such as used in rigid or semi-rigid containers such as packaging, sheets or bottles of foodstuffs.

Other aspects and advantages of the invention are described in the detailed description and claims below.

Detailed Description of the Drawings

Figure 1 shows the hazing rate (absolute percentage per day, ie a value of 1 indicates an increase in haze from 5% to 6% per day) versus copolysilicate {(Li ₂ O) _x (K ₂ O ) Is a graph of the mole fraction x of Li ₂ O in _1-x (SiO ₂ ) _y }. This figure shows the dependence of the clouding rate on the amount of lithium in the coating composition.

The present invention overcomes the disadvantages of prior art vapor barrier coatings. The present invention includes a method of providing improved vapor, gas, and / or aroma barrier properties to a polymer substrate using a coating solution containing lithium-potassium copolysilicate at high relative humidity. The present invention provides new coating solutions for substrates as well as improved coating articles. The coating solution used in the process provides superior vapor, gas and fragrance barrier properties at high relative humidity compared to pure potassium polysilicate and exhibits a significantly reduced wind rate compared to pure lithium polysilicate.

I. Justice

The term "vapor" means a liquid at partial pressure, such as water vapor. The term "gas" includes oxygen, nitrogen, carbon dioxide, and the like. "Aroma" includes fragrant substances such as menthol and the like. For simplicity, as used herein, the term "vapor barrier" may be interpreted to mean gas and aroma as well as vapor as originally defined.

Similar to the term used herein, the term "solution" is to be interpreted to include colloidal dispersions and suspensions. "Colloidal dispersion or suspension" means any dispersion or suspension of particles in a liquid, which particles are larger than the non-sinkable molecular scale. In general, the particle size of the suspension or dispersion of the present invention is about 10 to about 50,000 angstroms. As used herein, "coating solution" means a liquid that does not sink and contains a dissolved or suspended solid that is used to apply the solid to a substrate.

II. The present invention

The method of the present invention particularly includes coating the polymer substrate with a barrier coating solution containing lithium and potassium copolysilicate. The coating solution comprises a copolysilicate, ie a mixture of two different alkali metal polysilicates. More specifically, this coating solution is produced from a mixture of lithium polysilicate and potassium polysilicate. This coating solution has a general formula of (Li ₂ O) _x (K ₂ O) _1-x (SiO ₂ ) _y {the mole fraction of Li ₂ O is x and the molar ratio of SiO ₂ to M ₂ O is y} It is characterized by a polymer silicate. In coating solutions useful in the methods of the present invention, the co-polysilicate is one with x being less than 1, y being from 1 to 10, or if x being from 1, y is greater than 4.6. (I.e. x is between 0 and 1 and y is 1 to 10, corresponding to claims 2, 17 and 22)

The new specific coating solution for use in the process described above is provided by the above formula {where x is greater than 4.6 if x is less than 1 and x is greater than 0.5 if y is 1 to 10). (Ie x is between 0 and 0.5, y is greater than 4.6 and up to 10, or x is from 0.5 to less than 1 and y is from 1 to 10, corresponding to claims 1 and 16) More preferably, the present invention The new coating solution of is characterized in that the x value is 0.5 to 1, the y value is 4.6 to 10. (I.e. x is less than 0 to 1 and y is 4.6 to 10, corresponding to claims 3, 18 and 23)

In addition to the novel coating solutions of the present invention, coating solutions useful in the present method may also include suitable surfactants that reduce surface tension. Surfactants can be anionic, cationic and nonionic, and many surfactants of each type are commercially available. It is preferred that the surfactants useful in the process and the solutions of the invention are nonionic. Suitable surfactants included in the composition have a critical micelle concentration that is low enough so that the dried coating is not damaged by residual surfactant. Most preferably, the surfactant is commercially available from acetylenic glycol (e.g. as commercially provided by Air Products) and alkyl ethoxylate (Hoechest Celanese and many other companies). The same as that provided by " The amount of surfactant added to the coating solution or composition depends on the particular surfactant selected, but at the same time should be the minimum amount required to wet the polymer substrate without degrading the performance of the dry coating. For example, the amount of typical surfactant may be about 0.1% or less of acetylene glycol or alkyl ethoxylate.

Typical coating solutions according to the invention are preferably colorless and transparent. The coating solution of the present invention can be prepared from commercially available lithium polysilicate and potassium polysilicate solutions. For example, a colloidal suspension of commercially available lithium polysilicate may be mixed with a colloidal suspension of commercially available potassium polysilicate to make the coating of the present invention. It should be noted that the coating solution of the present invention can be prepared by using the "parent" article used to produce commercially available polysilicates. Such methods of preparation are well known, but are unnecessary in view of the commercial availability of lithium and potassium polysilicate solutions.

As illustrated in Example 1 below, one exemplary commercially available product having Inobond® Li 2043 (van Baerle & Cie AG) is up to 24.5 wt% silicon dioxide and up to 3.0 wt% lithium oxide It is an aqueous colloidal suspension of lithium polysilicate comprising a. Another useful product is an aqueous colloidal suspension having K-4009® (van Baerle & Cie AG) and containing up to 26.8 wt% silicon dioxide and up to 13 wt% potassium oxide. These components are admixed with water to produce the desired solids content.

The molar ratio y of SiO ₂ : M ₂ O in the dried coating may be determined by the molar ratio of SiO ₂ : Li ₂ O and SiO ₂ : K ₂ O in the starting alkali metal polysilicate. However, one may wish to change the molar ratio of SiO ₂ : M ₂ O throughout the copolysilicate coating. This can be done by adding an aqueous suspension of colloidal silicon dioxide to the coating solution. As described in Example 4 below, one exemplary commercially available product having Ludox® AS-30 (DuPont Specialty Chemicals) is an aqueous colloidal suspension of silicon dioxide comprising 30% by weight solids. Such colloidal dispersions are commercially available under various trademarks, including Ludox® (DuPont Specialty Chemicals) and Klebosol® (Societe Francaise Hoechst).

The content of solids typically useful in the coating solution of the present invention is about 25% by weight of solids, with the preferred solids content being entirely dependent on the coating method used, in order to obtain the desired coating thickness of the dry coating on the selected substrate. It can be easily adjusted through techniques well known in the art. For example, the coating on the thin film or sheet is preferably about 200 to about 500 nm, more preferably about 300 nm. The coating on the rigid or semi-rigid container is preferably a dry coating of about 100 to about 1000 nm, such adjustments are well known in the art [see, for example, Canadian Patent No. 993,738,

The vapor barrier coating mixture is then subjected to stirring and, optionally, filtration time. Optionally, a surfactant may be added at this stage to reduce the surface tension of the coating solution. For example, commercially available nonionic surfactants (Hoechst Celanese) or Genapol® UD050 [Hoechst] and Dynol® 604 are commercially available. Other surfactants may be added at this stage. As such, the vapor barrier coating solution can be readily applied to the polymer surface or substrate.

The lithium-potassium copolysilicate coatings of the present invention can be used on various polymer surfaces and articles to improve (ie, reduce) the permeability of the article to vapors such as oxygen, carbon dioxide, nitrogen, and the like. Typical organic fragrances and vapors include, but are not limited to, d-limonene, cinnamaldehyde, vanillin, menthol, gasoline, perfume scent, and the like. Such coatings are particularly advantageous where the polymer used to make the article or substrate does not provide sufficient impermeability of vapor, gas, or aroma to the desired application.

Suitable substrates to be coated with the coating solutions described above include polyesters such as poly (ethylene terephthalate) (PET) and polyolefins such as copolymers of ethylene and norbornene [US Pat. No. 5,087,677], in particular poly Substrates formed from a polymer comprising propylene, polystyrene, polyethylene and cycloolefins (COC) and polyamides such as nylon. Articles coated with such coatings include, but are not limited to, polymeric films and sheets, rigid and semi-rigid containers, and other surfaces. In particular, preferred coating articles according to the invention are films, beverage bottles, plastic containers, jars used to cover polypropylene films, PET films, nylon films, food products (eg, livestock meat, poultry meat, etc.) jars, blisterpacks and lidstocks made of the polymers described above.

The polymeric article to be coated with the composition of the present invention may not be pretreated. Optionally, the polymeric article, such as a film or bottle, may be subjected to a first plasma treatment to improve wetting and adhesion by the barrier coating as described in Example 1 below. Alternatively, the polymeric article may be corona treated via a corona discharge treatment method widely used in the industry. If the coating on the polymer is not adequately wetted through corona treatment of the polymer, a suitable primer may be applied first to the polymer article. For example, in the case of polypropylene, a primer solution of poly (vinyl alcohol) or poly (hydroxystyrene) can be used to improve the wetting of the barrier coating solution onto the polymer.

In addition, the polymer may be flame treated or chemically etched and oxidized prior to applying the coating solution of the present invention.

The substrate may be a film comprising a heat seal layer on at least one side. The heat tight layer may consist of an ethylene-propylene copolymer or an ethylene-propylene-butylene terpolymer. Thus, the coating solution is applied to the surface of the heat tight layer. Alternatively, where the film comprises one side coated with a heat tight layer, the coating solution of the present invention may be applied to the film surface opposite to the surface coated with the heat tight layer. The polymeric substrate or article may also include a protective topcoat layer. The coating of the present invention may be applied over the top coating layer.

The coatings of the present invention may be applied to selected polymer surfaces or articles by conventional coating techniques known to those skilled in the art. Such techniques include, but are not limited to, roll coating, spray coating, and dip coating techniques. Roll coating techniques include rod, reverse roll, forward roll, air knife, knife over roll, blade, gravure printing and slot die coating methods However, it is not limited thereto. Common techniques for this type of coating method include Modern Coating and Drying Techniques (New York, 1992) (E. Cohen and E. Gutoff, eds; VCH Publishers), It can be found in articles such as Web Processing and Converting Technology and Equipment (New York, 1984) (D. Satas, ed; Van Nostrand Reinhold). The three-dimensional article can be coated via spray coating or dip coating. The application method can be selected from these and other well known methods by one skilled in the art, but is not limited thereto.

After coating, the coated article must be dried at room temperature or a selection temperature higher than room temperature. The choice of drying temperature depends on the desired time to dry, ie the accelerated drying time can be made at a higher temperature which would not be necessary if longer times were allowed to dry. One skilled in the art can easily adjust the oven temperature and drying time as desired. The performance of the dried vapor barrier coating is not affected by the drying temperature of 25 to 200 ° C. An important advantage of the coatings and methods of the present invention is that the low drying temperatures (<100 ° C.) make this process consistent with the requirements of the biaxially oriented polypropylene (BOPP) film process.

The compositions and methods of the present invention are further described through the following examples, which are not intended to limit the scope of the present invention.

( Example)

Example 1: Changes in the lithium oxide mole fraction in the copolysilicate coating for this axially oriented PET film

A. Preparation of Coating Solution

A series of seven lithium-potassium copolysilicate barrier coating solutions for the present invention was prepared as shown in Table 1. The polysilicate coating composition of the present invention is represented by the mole fraction x of Li ₂ O in copolysilicate (Li ₂ O) _x (K ₂ O) _1-x (SiO ₂ ) _y , where x is 0 to 1. With continued stirring, Inobond® Li 2043 lithium polysilicate solution (van Baerle & Cie AG) with 3.0% w / w Li ₂ O and 24.5% w / w SiO ₂ was mixed with water. K-4009 potassium polysilicate solution (van Baerle & Cie AG) with 13.0% w / w K ₂ O and 26.85% w / w SiO ₂ was added to the lithium polysilicate solution. Genapol® 26-L-60N nonionic surfactant (Hoechst Celanese) was then added in a 1 wt% solution to improve the wetting of the poly (ethylene terephthalate) (PET) substrate. Each coating mixture of Table 1 was stirred and filtered through diatomaceous earth. The coating solution thus obtained contained 15% total solids and 0.01% surfactant. The SiO ₂ : M ₂ O molar ratio y ranged from 3.24 at x = 0 to 4.05 at x = 1.0.

B. Coated Film Preparation

A 10.16 cm (4 inch) circle was cut using a scalpel from a PET film (Hoechst Diafoil, Hostaphan® 2400, 0.5 mil thickness). All dust on the film was removed by blowing clean, filtered air. The sample was then plasma treated to improve the wetting with the copolysilicate coating solution and the adhesion of the dry copolysilicate coating. Plasma treatment was carried out using a Plasma Preen microwave reactor operated at 50% power at 2 Torr of oxygen. The treatment time was 5 seconds. About 10 g of the coating solution was dispersed in the PET film before rotating at 2000 rpm for 10 seconds. The coating film was dried for up to 30 seconds in an oven maintained at 50 ° C.

Several coated film samples were prepared using the respective coating solutions described in Table 1. Separate samples were chosen to measure oxygen permeability (OTR) as a function of accelerated aging / haze measurement and relative humidity.

C. Haze formation measurement

Optical blur was measured using a spectrophotometer (MacBeth Color-Eye 7000) according to ASTM D 1003-61. The samples were placed in an environmental chamber (Tenney TH Jr.) maintained at 80 ° C. and 85% relative humidity immediately after spin-coating. Samples were periodically removed from the chamber to measure flow for two weeks.

The initial linear cloud formation rate due to wind damage was calculated using the least-squares fit on the% cloud versus time graph. Over time,% clouding represents a constant, which is proportional to the lithium content in the copolysilicate coating. 1 shows the dependence of the initial clouding progress on the coating composition. The clouding rate increases in proportion to the increased lithium content.

D. Oxygen Permeability Measurement

The barrier performance of the coated film sample was evaluated by measuring the OTR. OTR measurements were performed using a Mocon Oxtran 2000 instrument. Table 2 shows OTR values at 30 ° C. for a series of (Li ₂ O) _x (K ₂ O) _1-x (SiO ₂ ) _y copolysilicate barrier coatings on a 0.0013 cm (0.5 mil) PET film. (OTR unit: cm ³ / [m ² atm day]) versus relative humidity.

Small amount of lithium (x Copolysilicate coatings containing 0.34) suffer a significant loss of barrier performance at high humidity. Copolysilicate Coating (0.5) x 1) provides excellent barrier performance for PET films at high humidity, but significantly reduces wind-weakness as compared to lithium polysilicate coatings, as shown in FIG.

Example 2: Change in Lithium Oxide Mole Fraction in Copolysilicate Coatings on Biaxially Oriented PET Films

A. Preparation of Solution

Using the following method and the amounts listed in Table 3, a series of three lithium-potassium copolysilicate barrier coating solutions were prepared. As in Example 1, the x value represents the mole fraction x of Li ₂ O in the copolysilicate (Li ₂ O) _x (K ₂ O) _1-x (SiO ₂ ) _y . With continued stirring, Inobond® Li 2043 was mixed with distilled water. K-4009 potassium polysilicate solution was added to the lithium polysilicate solution during stirring. The coating solution thus obtained contained a total of 10% solids. The molar ratio y of SiO ₂ : M ₂ O had a range of 3.51 to x78 when x = 0.33 to 3.78 when x = 0.67. Similar solutions containing individual alkali metal polysilicate 10% solids were prepared as comparative samples.

B. Coated Film Preparation

A 10.16 cm (4 inch) circle was cut using a scalpel from a biaxially oriented PET film (Hoechst Diafoil, Hostaphan® 2400, 0.0013 cm (0.5 mil) thickness). All dust on the film was removed by spraying clean, filtered air. The sample was then plasma treated using a plasma-print microwave reactor operated at 50% power at 2 Torr of oxygen. The treatment time was 5 seconds. About 100 g of coating solution was dispersed over the polymer film. The spin cycle developed for 2 seconds at 350 rpm followed by the spin cycle for 10 seconds at 2000 rpm. The coated film was dried for 30 seconds in an oven maintained at 50 ° C. Several coated film samples were made with each coating solution described in Table 3.

C. Oxygen Permeability Measurement

Oxygen transmission was measured using a Mocon Oxtran 2000 instrument. Table 4 shows the oxygen transmission rate results for PET films coated with copolysilicate as a function of relative humidity. As a reference point, uncoated Hostaphan® 2400 grade PET film {0.0013 cm (0.5 mil)} had an oxygen transmission rate of about 170 cm ³ / [m ² day atm] when tested at 30 ° C. and 0% relative humidity. Has The OTR reduction for this example is much more pronounced than the data of Example 1.

Example 3: Change of Lithium Oxide Mole Fraction in Copolysilicate Coating on This Axial Polypropylene Film

A. Preparation of Solution

A series of three lithium-potassium copolysilicate barrier coating solutions was prepared as described in Example 2. Similar solutions containing 10% solids of the individual alkali metal polysilicates were prepared as comparative samples. In addition, a priming solution consisting of poly (p-hydroxystyrene) in an aqueous base is 4.19 g of lithium hydroxide monohydrate in a sufficient amount of distilled water to make a 100.0 ml solution. And 1.00 g of polymer grade poly (p-hydroxystyrene) were added by stirring in order. The solution thus obtained contained 1% by weight of poly (p-hydroxystyrene) in 0.1N aqueous lithium hydroxide.

B. Coated Film Preparation

A 10.16 cm (4 inch) circle was cut using a scalpel from a biaxially oriented polypropylene film (Trespaphan® FND 30, 0.003 cm (1.2 mil) thickness). All dust on the film was removed by blowing clean, filtered air. The sample was then plasma treated using a plasma-print microwave reactor operated at 50% power at 2 Torr of oxygen. The treatment time was 5 seconds. About 10 g of poly (p-hydroxystyrene) primer solution was dispersed over the polymer film. The spin cycle developed for 2 seconds at 350 rpm, followed by a spin cycle of 10 seconds at 2000 rpm. The primed film was dried for 30 seconds in an oven maintained at 50 ° C. Then, about 10 g of lithium-potassium copolysilicate blocking solution was dispersed over the primed polymer film. The spin cycle developed for 2 seconds at 350 rpm, followed by a spin cycle of 10 seconds at 2000 rpm. The coated film was dried for 30 seconds in an oven maintained at 50 ° C.

Several coated film samples were made with each coating solution described in Table 3. As comparative samples, films were also prepared in which the copolysilicate coating step was omitted.

C. Oxygen Permeability Measurement

Oxygen transmission was measured using a Morcon Oxtran 2000 instrument. Table 5 shows the oxygen permeability results for this axially oriented polypropylene film (1.2 mil thickness) of copolysilicate charcoal coated as a function of relative humidity. As a reference point, uncoated FND 30 grade polypropylene had an oxygen transmission of about 1700 cm ³ / [m ² day atm] when tested at 30 ° C. and 0% relative humidity, which is shown in FIG. 5. Basically the same as the value obtained for the primed but uncoated film.

Example 4: Change in molar ratio of silicon dioxide to metal oxide in copolysilicate coatings containing equal amounts of lithium oxide and potassium oxide

Example 1 demonstrates that the cloud formation rate due to wind damage in lithium polysilicate barrier coatings can be reduced by adding potassium silicate. However, adding potassium silicate impairs the good oxygen barrier performance of the lithium silicate coating at high humidity. The balance of low windage and satisfactory barrier performance at high humidity is achieved using about equivalent molar lithium-potassium copolysilicate mixtures.

The copolysilicate barrier coating, produced from K-4009 (SiO ₂ : K ₂ O = 3.24) and Li 2043 (SiO ₂ : Li ₂ O = 4.06), has a SiO ₂ : M ₂ O The molar ratio y is 3.64. In this experiment, y was increased by using (1) a potassium polysilicate solution having a high molar ratio of SiO ₂ : K ₂ O, or (2) adding colloidal silicon dioxide. The first approach increased the y of the copolysilicate coating of the present invention from 3.64 to 4.0. The upper limit of y was determined through the SiO ₂ : K ₂ O molar ratio of commercially available potassium polysilicate coating solution. The second method of adding colloidal SiO ₂ allows a solution with a much higher y value to be prepared.

A. Preparation of Coating Solution

In this example, the lithium polysilicate source was Inobond® Li 2043. Potassium polysilicate source was either K-4009 or KASIL® 1 potassium polysilicate solution (PQ Coporation) with 8.30% w / w K ₂ O and 20.8% w / w SiO ₂ . The colloidal silicon dioxide source was selected from the list of Ludox® colloidal silicon dioxide suspensions (DuPont Specialty Chemicals) described in Table 6. Dupont's Ludox® CL-X silicon dioxide was wrapped in Al ₂ O ₃ capsule. The same merchandise sold under the trade name Klebasol® is available from Societe Francaise Hoechst.

A series of lithium-potassium copolysilicate barrier coating solutions having a molar fraction x of Li ₂ O and a molar ratio y of SiO ₂ : M ₂ O differing from each other was prepared according to the amounts shown in Table 7. In one experiment, a potassium silicate solution KASIL® # 1 with a molar ratio of SiO ₂ : K ₂ O was used. With continued stirring, distilled water, potassium polysilicate solution, lithium polysilicate solution and Ludox® colloidal silicon dioxide were combined in sequence. The coating solution thus obtained had a total of 10% solids, and the molar ratio y of SiO ₂ : M ₂ O was 3.64 to 10.0. Similar solutions containing alkali metal polysilicate 10% solids and no additional colloidal silicon dioxide were prepared as comparative samples.

B. Coated Film Sample Preparation

A 10.16 cm (4 inch) circle was cut using a scalpel from a biaxially oriented PET film (Hoechst Diafoil, Hostaphan® 2400, 0.0013 cm (0.5 mil) thickness). All dust on the film was removed by blowing clean, filtered air. The film sample was then plasma treated to improve the soaking with the barrier coating solution and the adhesion of the dried barrier coating. Plasma treatment was performed using a plasma-print microwave reactor operated at 50% power at 2 Torr of oxygen. The treatment time was about 7 seconds.

About 10 g of coating solution was dispersed over the polymer film. The spin cycle developed for 2 seconds at 350 rpm, followed by a spin cycle of 10 seconds at 2000 rpm. The coated film was dried for 30 seconds in an oven maintained at 50 ° C.

C. Oxygen Blocking Performance

Oxygen transmission was measured using a Morcon Oxtran 2000 instrument. Samples were tested at 23 ° C. and 50% relative humidity. Table 8 shows the oxygen transmission rates for a series of lithium-potassium copolysilicate barrier coatings with a lithium molar fraction x of 0.5 in (Li ₂ O) _x (K ₂ O) _1-x (SiO ₂ ) _y , SiO _2. It is shown as a function of the molar ratio y of: M ₂ O. As a reference point, an uncoated 0.513 mil thick PET film has an oxygen transmission rate of up to 115 cm ³ / [m ² day atm] at 23 ° C. and 50% relative humidity. These results demonstrate that good barrier performance can be achieved in copolysilicate barrier coatings with molar ratios of SiO ₂ : M ₂ O up to 10. However, the molar ratio range of SiO ₂ : M ₂ O to achieve satisfactory blocking performance depends on what the colloidal silicon dioxide source is.

Example 5: Li in this axially oriented PET film ₂ O) _x (K ₂ O) _1-x (SiO ₂ ) _y SiO in copolysilicate coating ₂ : M ₂ O molar ratio y and Li ₂ Simultaneous change in mole fraction x of O

A. Preparation of Coating Solution

A series of lithium-potassium copolysilicate barrier coating solutions were prepared according to the amounts listed in Table 9. With continued stirring, Ludox® AS-30 colloidal dioxide containing distilled water, K-4009 potassium polysilicate solution, Inobond® Li 2043 lithium polysilicate solution, and 30% solids (Dupont Specialty Chemicals) The silicon suspensions are combined in the given order. The coating solution thus obtained had a total of 10% solids and had a molar ratio y value of SiO ₂ : M ₂ O of 3.51 to 13. Similar solutions containing individual alkali metal polysilicate 10% solids were prepared as comparative samples.

B. Preparation of Coating Film Samples

A 10.16 cm (4 inch) circle was cut using a scalpel from a PET film (Hoechst Diafoil, Hostaphan® 2400, 0.5 mil thickness). All dust on the film was removed by blowing clean, filtered air. The sample was then plasma treated using a plasma-print microwave reactor operated at 50% power at 2 Torr of oxygen. The treatment time was 5 seconds. About 10 g of coating solution was dispersed in the polymer film. The spin cycle developed for 2 seconds at 50 rpm followed by a spin cycle of 10 seconds at 2000 rpm. The coating film was dried for about 30 seconds in an oven maintained at 50 ° C. Several coated film samples were prepared using the respective coating solutions described in Table 9.

C. Measurement of Oxygen Permeability

Oxygen transmission was measured using a Mocon Oxtran 2000 instrument. Table _{10, (Li 2 O) x (} K 2 O) 1-x (SiO 2) in the _y different SiO _2: a M molar ratio y of ₂ O and co-polysilicate barrier having a mole fraction x of Li ₂ O layer Oxygen permeability results for coated axially oriented PET film {thickness of 0.0013 cm (0.5 mil)}. As a reference point, an uncoated Hostaphan® 2400 grade PET film {0.0013 cm (0.5 mil) thickness}, when tested at 23 ° C. and 0% relative humidity, approximately 115 cm ³ / [m ² day atm] It has an oxygen transmittance of

Example 6: roll coating of lithium-potassium copolysilicate barrier coating on this axially oriented PET film

A. Preparation of Coating Solution

With continued stirring, 4,513 g KASIL 占 (1 potassium polysilicate solution (PQ Coporation) with 8.30% w / w K ₂ O and 20.8% w / w SiO ₂ was mixed with 11,535 g of distilled water. To the stirring potassium polysilicate solution was added 3,951 g of Inobond® Li-2043 lithium polysilicate solution. The coating solution thus obtained had a solids level of 12% in total. The x and y values in (Li ₂ O) _x (K ₂ O) _1-x (SiO ₂ ) _y were 0.5 and 4.0, respectively.

B. Preparation of Coating Film

This axially oriented PET film (Hoechst Diafoil, Hostaphan® 2400, 0.0013 cm (0.5 mil)) was coated with a copolysilicate solution at a rate of 200 fpm (60.96 m / min) using the roll coating described above. Corona discharge treatment was used to increase the surface energy of the film surface just before applying the coating. Application of the coating was done using a gravure cylinder of inverse gravure configuration with a rigid rubber backing roll. The ceramic coated gravure cylinder had a cell pattern (sculpted with a laser) with 220 lines per inch (2.54 cm) arranged at an angle of 60 degrees to the roll axis and a theoretical cell volume of 10 billion cubic microns per square inch.

C. Oxygen Permeability Measurement

Oxygen transmission was measured using a Mocon Oxtran 2000 instrument. The average oxygen transmission rate, obtained for 12 representative samples selected from the coated film, was 0.77 ± 0.38 cm ³ / [m ² day atm] at 23 ° C. and 50% relative humidity. As a reference point, an uncoated Hostaphan® 2400 grade PET film {0.0013 cm (0.5 mil) thickness}, when tested at 23 ° C. and 50% relative humidity, approximately 115 cm ³ / [m ² day atm] It has an oxygen transmittance of

Example 7: Thick PET Film Coated with Copolysilicate

A. Preparation of Coating Solution

Lithium-potassium copolysilicate barrier coating solution with values of x and y of (Li ₂ O) _x (K ₂ O) _1-x (SiO ₂ ) _y of 0.5 and 3.64, respectively, was added to 694.2 g of distilled water with continued stirring. It was prepared by adding 176.8 g of Inobond® Li 2043 lithium polysilicate and 129.0 g of K-4009 potassium polysilicate.

B. Preparation of Coated Film Samples

A circle of 4 inches (10.16 cm) was cut from this axially oriented PET film (Hoechst Diafoil, Hostaphan® 4000, thickness of 0.017 cm (6.5 mil)) using a circular punch and scissors. All dust on the film was removed by blowing clean, filtered air. The sample was then corona treated to improve the soaking with the barrier coating solution and the adhesion of the dried barrier coating. Corona treatment was performed using Tantec Lab System II with hand held ceramic roller electrodes. The treatment time was about 20 seconds. Spin coating of the film was performed by dispersing about 10 g of coating solution in the polymer film. The spin cycle developed for 2 seconds at 350 rpm followed by a spin cycle of 10 seconds at 2000 rpm. The coating film was dried for about 30 seconds in an oven maintained at 50 ° C.

C. Oxygen Permeability Measurement

Oxygen transmission was measured using a Morcon Oxtran 2000 instrument. Samples were tested at 23 ° C. and relative humidity of 0 or 48%. Table 11 shows the oxygen transmission rate results for this axially oriented thick poly (ethylene terephthalate) film (thickness of 6.5 mils), coated with or without a copolysilicate barrier layer. Note that the OTR of the uncoated PET film is inversely proportional to the film thickness (see Example 5) {at 23 ° C, up to 8 cm ³ / [m ² day atm] vs. 0.0013 cm (for 0.017 cm (6.5 mil) film). 0.5 mil) film up to 115 cm ³ / [m ² day atm]. In contrast, the oxygen transmission rate of this axially oriented PET film coated with copolysilicate is independent of the thickness of the substrate. Thus, the improvement in relative blocking that can be achieved for thick substrates is less than for thin substrates.

Example 8: Copolysilicate Barrier Coating of PET Bottles

This example illustrates the oxygen barrier performance obtained by spray coating a PET bottle with a lithium-potassium copolysilicate barrier coating. The main difference between coating a PET film and coating a bottle is that (1) the thickness of the bottle wall is thicker, typically 0.036 cm (14 mil) vs. 0.0013 cm (0.5 mil) used in the previous example. ) Or 0.017 cm (6.5 mil) film, (2) spray coating process. One skilled in the art of spray coating can achieve the conditions of creating a uniform barrier coating layer of suitable thickness to achieve acceptable barrier performance.

A. Coating Solution Preparation

Two li-potassium copolysilicate barrier coating solutions with x and y values of 0.5 and 3.64 for (Li ₂ O) _x (K ₂ O) _1-x (SiO ₂ ) _y were sprayed. Prepared by coating. For example, the first coating solution called Barrier 1 keeps stirring

It was prepared by adding 70.7 g of Inobond® Li 2043 lithium polysilicate and 51.56 g of K-4009 potassium polysilicate to 1,877 g of distilled water. For example, a second coating solution called Barrier 2 contains 0.195 g of Genapol® 26-L-60-N (Hoechst Celanese) and an alkyl ethoxylate surfactant in a 1003.35 g aliquot of Barrier 1. It was prepared by adding. Each solution contained a total of 2.0 weight percent solids. The solution was mixed thoroughly just before spray coating.

B. Preparation of Coated Bottles

PET bottles (Hoechst Celanese T-80 PET resin) blow-molded at 20 ounce injection pressure were washed using a towel damped with acetone. The dried bottle was plasma treated to improve the wetting of the barrier coating solution and the adhesion of the dried copolysilicate layer. Copolysilicate blocking solution was applied with a Badger air sprayer. The bottle was dried for several minutes in an oven kept at 80 ° C.

C. Measurement of Oxygen Permeability

Oxygen transmission was measured using a Mocon Oxtran 2000 instrument with a package test module maintained at 30 ° C. and 0% relative humidity. Table 12 provides oxygen permeability for the oxygen partial pressure difference of 0.21 atm, such as air on the outside and pure nitrogen on the inside, for the walls of PET bottles. These data indicate that the oxygen permeation rate generated by the lithium-potassium copolysilicate barrier layer is approximately doubled.

Example 9: CO2 Blocking Performance of Biaxially Oriented PET Film Coated with Copolysilicate

The permeability of carbon dioxide of the biaxially oriented poly (ethylene terephthalate) film sample coated with the lithium: potassium copolysilicate described in Example 6 was tested. The average carbon dioxide transmission for four representative samples selected from the coated film was 16 ± 11 cm ³ / [m ² day atm] at 23 ° C. and 0% relative humidity. As a reference point, an uncoated 0.0013 cm (0.5 mil) Hostaphan® 2400 grade poly (ethylene terephthalate) film, at 23 ° C. and 0% relative humidity, was approximately 440 cm ³ / [m ² day atm] Has a carbon dioxide transmission rate.

Example 10: Aroma Barrier Performance of Coaxially Coated and Coaxially Oriented Polypropylene Films

A. Preparation of Coating Solution

Lithium-potassium copolysilicate barrier coating solutions with x and y values of 0.5 and 3.64 for (Li ₂ O) _x (K ₂ O) _1-x (SiO ₂ ) _y , respectively, were prepared using the method used in Example 1. It was prepared using Inobond® Li 2043 lithium polysilicate, K-4009 potassium polysilicate and water. The solution thus obtained had a solids level of 12% in total.

B. Preparation of Coated Film Samples

This axially oriented polypropylene film {Trespaphan® FND 20, 0.002 cm (0.8 mil thick)} was corona treated and then primed into a poly (vinyl alcohol) solution by reverse gravure coating. The priming film was coated with the copolysilicate solution described in the above example using a roll coating at a speed of 200 fpm (60.96 m / min). Application of the coating was achieved by the use of a gravure cylinder of reverse gravure configuration with a rigid rubber backing roll. The ceramic coated gravure cylinder had a cell pattern (sculpted with a laser) with 220 lines per inch (2.54 cm) arranged at an angle of 60 degrees to the roll axis and a theoretical cell volume of 10 billion cubic microns per square inch.

C. Measurement of Directional Blocking

Aroma barrier performance was tested using cinnamaldehyde as permeant. The cinnamic aldehyde transmittance (measured with liquid cinnamic aldehyde in contact with the uncoated side of the film) of the uncoated and copolysilicate coated film was 0.095 g / (m ² day) and 0.022 g / (m, respectively, at 23 ° C. ² day).

Example 11: cycloolefin copolymer coated cycloolefinic film

A. Solution Preparation

Lithium-potassium copolysilicate barrier coating solutions with x and y values of 0.5 and 3.64 for (Li ₂ O) _x (K ₂ O) _1-x (SiO ₂ ) _y , respectively, were prepared using the method used in Example 1. It was prepared using Inobond® Li 2043 lithium polysilicate, K-4009 potassium polysilicate and water. The solution thus obtained had a solids level of 10% in total.

B. Preparation of Coated Film

A 4 inch (10.16 cm) circle was cut from the corona treated and axially oriented film of the cycloolefin copolymer, a copolymer of ethylene and norbornene having a thickness of 0.002 cm (0.8 mil). All dust on the film was removed by blowing clean, filtered air. About 10 g of coating solution was sprayed onto the polymer film and spin cycled at 2000 rpm for 10 seconds. The coated film was dried for about 30 seconds in an oven kept at 50 ° C.

C. Oxygen Permeability Measurement

Oxygen transmission was measured using a Mocon Oxtran 2000 instrument at 30 ° C. and 0% relative humidity. The polysilicate coated film showed an OTR of 28 cm ³ / [m ² day atm], while the uncoated film showed an OTR of 2819 cm ³ / [m ² day atm] under the same conditions.

By using the method of the present invention and using the improved coating composition of the present invention, there is no significant loss of barrier performance at higher humidity than pure potassium polysilicate, but about half of pure lithium polysilicate (x is up to 0.5) ) To create a blur ratio. More specifically, the lithium-potassium copolysilicate coating of the present invention reduces the windage rate of pure lithium polysilicate without losing the barrier properties of such lithium-polysilicate coatings. The lithium potassium polysilicate coating of the present invention provides excellent barrier properties with reduced adverse side effects caused by wind damage.

As described above, the present invention has the effect of providing a barrier coating that provides excellent gas and / or aroma barrier properties while improving the wind and cloud characteristics of the coating.

Claims (33)

A polymer film or sheet having a lithium-potassium copolysilicate coating layer comprising a copolysilicate of formula (M ₂ O) (SiO ₂ ) _y , M ₂ O is (Li ₂ O) _x (K ₂ O) _1-x , (i) x is between 0 and 0.5, y is greater than 4.6 and up to 10, or (ii) x is from 0.5 to less than 1 and y is from 1 to 10, A polymer film or sheet having a lithium-potassium copolysilicate coating layer comprised of copolysilicates of the formula (M ₂ O) (SiO ₂ ) _y , M ₂ O is (Li ₂ O) _x (K ₂ O) _1-x , x is between 0 and 1, y is 1 to 10, Polymer film or sheet. The polymer film or sheet according to claim 1 or 2, wherein x is from 0.5 to less than 1 and y is from 4.6 to 10. The polymer film or sheet according to claim 1 or 2, wherein the polymer is selected from the group consisting of polyesters, polyolefins, polystyrenes, and polyamides. The polymer film or sheet of claim 4, wherein the polyolefin is selected from polyethylene, polypropylene, cycloolefin copolymers, and copolymers thereof. The polymer film or sheet of claim 4, wherein the polyester is poly (ethylene terephthalate). The polymer film or sheet of claim 5, wherein the cycloolefin copolymer is a copolymer of ethylene and norbornene. The polymer film or sheet of claim 4, wherein the polyamide is nylon. The polymer film or sheet of claim 1, wherein the substrate is selected from the group consisting of a polymer film, a polymer sheet, and a rigid or semi-rigid polymer container. The polymer film or sheet of claim 9, wherein the substrate is a film comprising a heat seal layer on at least one side. The polymer film or sheet according to claim 10, wherein the heat-adhesive layer is made of ethylene-propylene copolymer or ethylene-propylene-butylene terpolymer. The polymer film or sheet according to claim 1 or 2, wherein the substrate is plasma treated, corona treated, flame treated or chemically etched / oxidized. The polymer film or sheet of claim 1, further comprising a protective topcoat layer. The polymer film or sheet of claim 9, wherein the substrate is a polymer film. The polymer film or sheet of claim 9, wherein the substrate is a rigid or semi-rigid polymer container. A barrier coating solution for use in a polymer substrate comprising lithium-potassium copolysilicate having the formula (M ₂ O) (SiO ₂ ) _y , M ₂ O is (Li ₂ O) _x (K ₂ O) _1-x , (i) x is between 0 and 0.5, y is greater than 4.6 and up to 10, or (ii) x is from 0.5 to less than 1 and y is from 1 to 10, Barrier coating solution. A barrier coating solution for use in polymer substrates consisting essentially of lithium-potassium copolysilicates of the formula (M ₂ O) (SiO ₂ ) _y , M ₂ O is (Li ₂ O) _x (K ₂ O) _1-x , x is between 0 and 1, y is 1 to 10, Barrier coating solution. 18. The barrier coating solution of claim 16 or 17 wherein x is between 0.5 and less than 1 and y is between 4.6 and 10. The barrier coating solution of claim 16 further comprising a surfactant. 20. The barrier coating solution of claim 19 wherein the surfactant is nonionic. The barrier coating solution of claim 20 wherein the surfactant is selected from the group consisting of acetylene glycol and alkyl ethoxylates. A method of providing barrier properties to a polymer substrate, comprising coating the substrate with a barrier coating solution comprising lithium-potassium copolysilicate having the formula (M ₂ O) (SiO ₂ ) _y , M ₂ O is (Li ₂ O) _x (K ₂ O) _1-x , x is between 0 and 1, y is 1 to 10, A method of providing barrier properties to a polymer substrate. 23. The method of claim 22, wherein x is from 0.5 to less than 1 and y is between 4.6 and 10. 23. The method of claim 22, wherein said polymer is selected from the group consisting of polyesters, polyolefins, polystyrenes, and polyamides. 25. The method of claim 24, wherein the polyolefin is selected from polyethylene, polypropylene, cycloolefin copolymers, and copolymers thereof. 25. The method of claim 24, wherein the polyester is poly (ethylene terephthalate). 27. The method of claim 25, wherein the cycloolefin copolymer is a copolymer of ethylene and norbornene. 25. The method of claim 24, wherein the polyamide is nylon. The method of claim 22, wherein the substrate is selected from the group consisting of a polymer film, a polymer sheet, and a rigid or semi-rigid polymer container. 30. The method of claim 29, wherein the substrate is a film comprising a heat tight layer on at least one side. 31. The method of claim 30, wherein the heat tight layer is made of ethylene-propylene copolymer or ethylene-propylene-butylene terpolymer. The method of claim 22, wherein the substrate is plasma treated, corona treated, flame treated or chemically etched / oxidized prior to application of the coating. 23. The method of claim 22, wherein the substrate further comprises a protective top coating layer.