Polymer coating compositions and articles coated therewith
阅读说明：本技术 聚合物涂料组合物及由其涂覆的制品 (Polymer coating compositions and articles coated therewith ) 是由 L·M·范登博斯舍 J·J·塞皮尔 C·A·V·昆丁 于 2019-03-19 设计创作，主要内容包括：提供了聚合物涂料组合物和涂覆有所述聚合物涂料组合物的制品。所述聚合物涂料组合物可以包括基于乙烯的聚合物,其表现出令人期望的熔融性能和分子量分布。所述聚合物涂料组合物可以在制品上提供薄涂层,同时仍然提供有利的性能,例如密封强度。(Polymeric coating compositions and articles coated with the polymeric coating compositions are provided. The polymer coating composition can include an ethylene-based polymer that exhibits desirable melt properties and molecular weight distribution. The polymeric coating composition can provide a thin coating on an article while still providing advantageous properties, such as seal strength.)
1. A coated article comprising:
a fibrous substrate; and
at least one polymeric coating affixed to at least a portion of the first surface of the fibrous substrate, the at least one polymeric coating having a coating weight of about 13g/m2Or less, wherein the at least one polymeric coating comprises:
1) from about 20 wt% to about 80 wt% of an ethylene-based polymer having:
a) a melt index of about 5g/10min to about 30g/10 min;
b) a melt elastic modulus G' (G ═ 500Pa) at 170 ℃ of less than 15 Pa;
c) a relaxation time λ of less than 0.003s at 170 ℃;
d) there are at least two secondary melting temperature peaks between 110 ℃ and 120 ℃;
e) a weight average molecular weight (Mw) of about 10000g/mol to about 55000 g/mol;
f) a molecular weight distribution (Mw/Mn) of from about 2.0 to about 5.0; and
g) the Mz/Mw ratio is from about 1.5 to about 2.1; and
2) from about 20 wt% to about 80 wt%: (i) low density polyethylene; (ii) ethylene acrylic acid copolymers; (iii) ethyl-methyl acrylate copolymers; (iv) a polymer produced by polymerizing at a pressure of 50MPa-g or more; (v) ethylene-methacrylic acid copolymers; or (vi) a combination thereof.
2. The coated article according to claim 1, further comprising a sealed seam between the first end of the fibrous substrate and one of: (I) a second end of the fibrous substrate; (II) a portion of a separate fibrous substrate; or (III) a combination thereof, wherein the seal strength of the sealed seam measured by the seal strength test method is about 6.0N/15mm or greater.
3. The coated article according to any of claims 1 and 2, wherein the density of the ethylene-based polymer is about 0.910g/cm3Or larger.
4. The coated article according to any one of claims 1-3, wherein the melt index of the ethylene-based polymer is from about 10g/10min to about 25g/10 min.
5. A coated article according to any of claims 1 to 4, wherein the fibrous substrate comprises paper or paperboard.
6. The coated article according to any of claims 1-5, wherein the at least one polymer coating comprises from about 20 wt% to about 80 wt% of a low density polyethylene, a polymer produced by polymerization at a pressure of 50MPa-g or greater, or a combination thereof.
7. The coated article according to any of claims 1-6, wherein the at least one polymeric coating comprises from about 30 wt% to about 60 wt% of the ethylene-based polymer, and from about 40 wt% to about 70 wt% of: (i) low density polyethylene; (ii) ethylene acrylic acid copolymers; (iii) ethyl-methyl acrylate copolymers; (iv) a polymer produced by polymerization at a pressure of 50MPa-g or more; (v) ethylene-methacrylic acid copolymers; or (vi) a combination thereof.
8. The coated article according to any one of claims 1 to 7, wherein the at least one polymer coatingThe coat weight of the layer is about 10g/m2Or smaller.
9. The coated article according to any of claims 1 to 8, wherein the melt index of one or more of the following is from about 2g/10min to about 12g/10 min: (i) low density polyethylene; (ii) ethylene acrylic acid copolymers; (iii) ethyl-methyl acrylate copolymers; (iv) a polymer produced by polymerization at a pressure of 50MPa-g or more; (v) ethylene-methacrylic acid copolymers; or (vi) a combination thereof.
10. A coated article according to any of claims 1 to 9, wherein the coated article is for use in containing food, beverages or cosmetics.
11. A method of making a coated article for a container, the method comprising:
at least one polymer layer for receiving at about 15g/m2Or less, wherein the at least one polymer layer comprises:
1) from about 20 wt% to about 80 wt% of an ethylene-based polymer having:
a) a melt index of about 5g/10min to about 30g/10 min;
b) a melt elastic modulus G' (G ═ 500Pa) at 170 ℃ of less than 15 Pa;
c) a relaxation time λ of less than 0.003s at 170 ℃;
d) there are at least two secondary melting temperature peaks between 110 ℃ and 120 ℃;
e) a weight average molecular weight (Mw) of about 10000g/mol to about 55000 g/mol;
f) a molecular weight distribution (Mw/Mn) of from about 2.0 to about 5.0; and
g) the Mz/Mw ratio is from about 1.5 to about 2.1; and
2) from about 20 wt% to about 80 wt%: (i) low density polyethylene; (ii) ethylene acrylic acid copolymers; (iii) ethyl-methyl acrylate copolymers; (iv) a polymer produced by polymerization at a pressure of 50MPa-g or more; (v) ethylene-methacrylic acid copolymers; or (vi) a combination thereof; and
sealing a first end of the coated fibrous substrate to one of: (I) a second end of the coated fibrous substrate; (II) a portion of a separate fibrous substrate; or (III) a combination thereof, thereby forming a sealed seam of the coated article, wherein the sealed seam has a seal strength of about 6.0N/15mm or greater as measured by the seal strength test method.
12. The method according to claim 11, wherein said coated fibrous substrate is formed via extrusion coating of said at least one polymer layer onto said fibrous substrate.
13. The method according to any one of claims 11 and 12, wherein sealing a first end of the coated fibrous substrate comprises exposing the coated fibrous substrate to thermal energy sufficient to form a sealed seam.
14. The method according to any one of claims 11-13, wherein the density of the ethylene-based polymer is about 0.910g/cm3Or larger.
15. The process according to any one of claims 11-14, wherein the ethylene-based polymer exhibits a melt index of from about 10g/10min to about 25g/10 min.
16. A method according to any of claims 11-15, wherein the fibrous substrate comprises paper or paperboard.
17. The method according to any one of claims 11-16, wherein the container is a food container, a beverage container or a cosmetic container.
18. The method according to any one of claims 11-17, wherein the at least one polymer layer comprises from about 20 wt% to about 80 wt% of a low density polyethylene, a polymer produced by polymerization at a pressure of 50MPa-g or greater, or a combination thereof.
19. The method according to any one of claims 11-18, wherein the at least one polymer layer comprises from about 30 wt% to about 60 wt% of the ethylene-based polymer and from about 40 wt% to about 70 wt% of: (i) low density polyethylene; (ii) ethylene acrylic acid copolymers; (iii) ethyl-methyl acrylate copolymers; (iv) a polymer produced by polymerization at a pressure of 50MPa-g or more; (v) ethylene-methacrylic acid copolymers; or (vi) a combination thereof.
20. The method according to any one of claims 11-19, wherein the coating weight of the at least one polymer layer is about 10g/m2Or smaller.
21. The method according to any one of claims 11-20, wherein one or more of the following exhibits a melt index of from about 2g/10min to about 12g/10 min: (i) low density polyethylene; (ii) ethylene acrylic acid copolymers; (iii) ethyl-methyl acrylate copolymers; (iv) a polymer produced by polymerization at a pressure of 50MPa-g or more; (v) ethylene-methacrylic acid copolymers; or (vi) a combination thereof.
22. A thin layer composition comprising:
10g/m2or less, a composition comprising:
at least about 20 wt% of an ethylene-based polymer having:
a) a melt index of about 5g/10min to about 30g/10 min;
b) a melt elastic modulus G' (G ═ 500Pa) at 170 ℃ of less than 15 Pa;
c) a relaxation time λ of less than 0.003s at 170 ℃;
d) there are at least two secondary melting temperature peaks between 110 ℃ and 120 ℃;
e) a weight average molecular weight (Mw) of about 10000g/mol to about 55000 g/mol;
f) a molecular weight distribution (Mw/Mn) of from about 2.0 to about 5.0; and
g) the Mz/Mw ratio is from about 1.5 to about 2.1.
23. The thin layer composition of claim 22, wherein the composition further comprises from about 20 wt% to about 80 wt% of: (i) low density polyethylene; (ii) ethylene acrylic acid copolymers; (iii) ethyl-methyl acrylate copolymers; (iv) a polymer produced by polymerization at a pressure of 50MPa-g or more; (v) ethylene-methacrylic acid copolymers; or (vi) a combination thereof.
24. The thin layer composition of any of claims 22 and 23, wherein the melt index of one or more of the following is from about 2g/10min to about 12g/10 min: (i) low density polyethylene; (ii) ethylene acrylic acid copolymers; (iii) ethyl-methyl acrylate copolymers; (iv) a polymer produced by polymerization at a pressure of 50MPa-g or more; (v) ethylene-methacrylic acid copolymers; or (vi) a combination thereof.
25. The thin layer composition according to any one of claims 22-24, wherein the composition comprises from about 20 wt% to about 80 wt% of the ethylene-based polymer.
26. The thin layer composition of any of claims 22-25, wherein the ethylene-based polymer has a density of about 0.910g/cm3Or larger.
27. The thin layer composition of any of claims 22-26, wherein the ethylene-based polymer has a melt index of about 10g/10min to about 25g/10 min.
28. The thin layer composition according to any one of claims 22 to 27, wherein the composition comprises from about 30 wt% to about 60 wt% of the ethylene-based polymer, and from about 40 wt% to about 70 wt% of: (i) low density polyethylene; (ii) ethylene acrylic acid copolymers; (iii) ethyl-methyl acrylate copolymers; (iv) a polymer produced by polymerization at a pressure of 50MPa-g or more; (v) ethylene-methacrylic acid copolymers; or (vi) a combination thereof.
Technical Field
Polymeric coating compositions and articles coated therewith are provided.
Background
The polymeric coating composition can be used to coat a variety of substrates to impart certain properties to articles made therefrom, such as imparting moisture protection when containing food or beverages. In various applications, such as disposable cups, cutlery and industrial packaging, thick polymer coatings are not required. However, from a processing/manufacturing standpoint, conventional choices of polymer coating compositions do not provide a thin coating for a substrate in an efficient manner.
U.S. patent No.6565934 discloses an insulated paper cup with improved sealability. The body member of the cup is coated on its outer surface with foamed low density polyethylene and on its inner surface with unfoamed modified low density polyethylene. The floor element of the cup is coated with foamed or unfoamed low density polyethylene, or foamed or unfoamed modified low density polyethylene. The body member and the sole member form a bond layer at the interface of the two members upon application of heat and pressure during fabrication.
U.S. publication No.2014/0367456 discloses a polyolefin and cellulose laminate for a food or beverage container. The container may be coated with 1-7 layers. The layer may comprise metallocene-catalyzed polyethylene alone or also conventional autoclave low density polyethylene. The container may be coated by a co-extrusion process.
Us publication 2015/0298438 discloses a polymer coated packaging material with three layers. The inner coating layer comprises a polymer blend having from 10 to 25 wt% of a low density polyethylene and from 75 to 90 wt% of another polyethylene having a higher melt viscosity than said low density polyethylene. The midcoat layer may include greater than 90 wt% high density polyethylene. The outer coating may comprise the same polymer blend as the inner coating.
U.S. publication No.2016/0168799 discloses a coated paper cup. The paper cup may include a first coating having a polyethylene copolymer on an inside of a bottom surface of the cup. The paper cups may also include a water-based coating on the inside surface of the sides of the cups. The water-based coating may include a water-based polymer that is water-soluble or water-dispersible.
WO2005/019333 discloses polymer blends comprising from 1 to 99% by weight of a copolymer of ethylene and an alpha olefin having from 3 to 10 carbon atoms, and from 1 to 99% by weight of a low density polyethylene. The copolymers may be prepared via metallocene catalysts. The polymer blend has a melt elastic modulus of 20 to 200Pa and can be used in extrusion coating applications.
WO2011/037590 discloses a polymer composition for use as a film or coating. The composition includes a first component (which is ethylene and one or more C's)3-C20α -copolymers of olefin comonomers) and a second component which is a low density polyethylene the density of the first component is 0.911 to 0.918g/cm3And the melt index of the second component is less than the melt index of the first component.
WO02/00436 discloses a polymer blend for use as a film or coating. The polymer blend comprises 1 to 99 weight percent of a polymer having a density of less than 0.916g/cm3And 1 to 99% by weight of a very low density polyethylene having a density of 0.916 to 0.928g/cm3The low density polyethylene of (1). The very low density polyethylene may have a melt index of 6 to 15 dg/min.
Summary of The Invention
In one aspect, a coated article is provided. The coated article may comprise a fibrous substrate, such as a paperboard substrate. The coated article can further include at least one polymeric coating affixed to at least a portion of the first surface of the fibrous substrate. The at least one polymer coating may have a coating weight of about 13g/m2Or smaller. The at least one polymer coating may include from about 20 wt% to about 80 wt% of the ethylene-based polymer. The ethylene-based polymer may have one or more of the following: a) a melt index of about 5g/10min to about 30g/10 min; b) a melt elastic modulus G' (G ═ 500Pa) at 170 ℃ lower than15 Pa; c) a relaxation time λ of less than 0.003s at 170 ℃; d) at least two secondary melting temperature peaks between 110 ℃ and 120 ℃; e) a weight average molecular weight (Mw) of about 10000g/mol to about 55000 g/mol; f) a molecular weight distribution (Mw/Mn) of from about 2.0 to about 5.0; and g) the Mz/Mw ratio is from about 1.5 to about 2.1. The at least one polymer layer may also include from about 20 wt% to about 80 wt% of: (i) low density polyethylene; (ii) ethylene acrylic acid copolymers; (iii) ethyl-methyl acrylate copolymers; (iv) a polymer produced by polymerization at a pressure of 50MPa-g or more; (v) ethylene-methacrylic acid copolymers; or (vi) a combination thereof.
In another aspect, a method of making a coated article for a container is provided. The method can include receiving a coated fibrous substrate coated with at least one polymer layer. The at least one polymer layer may be at about 15g/m2Or less, e.g. 10g/m2Or less coating weight, onto the substrate. The at least one polymer layer may include from about 20 wt% to about 80 wt% of the ethylene-based polymer. The ethylene-based polymer may have one or more of the following: a) a melt index of about 5g/10min to about 30g/10 min; b) a melt elastic modulus G' (G ═ 500Pa) at 170 ℃ of less than 15 Pa; c) a relaxation time λ of less than 0.003s at 170 ℃; d) at least two secondary melting temperature peaks between 110 ℃ and 120 ℃; e) a weight average molecular weight (Mw) of about 10000g/mol to about 55000 g/mol; f) a molecular weight distribution (Mw/Mn) of from about 2.0 to about 5.0; and g) the Mz/Mw ratio is from about 1.5 to about 2.1. The at least one polymeric coating may also include from about 20 wt% to about 80 wt% of: (i) low density polyethylene; (ii) ethylene acrylic acid copolymers; (iii) ethyl-methyl acrylate copolymers; (iv) a polymer produced by polymerization at a pressure of 50MPa-g or more; (v) ethylene-methacrylic acid copolymers; or (vi) a combination thereof. The method may further comprise sealing a first end of the coated fibrous substrate to one of: (I) a second end of the coated fibrous substrate; (II) a portion of a separate fibrous substrate; or (III) a combination thereof. This may allow for the formation of a sealed joint of the coated articleAnd (6) sewing. The seal strength of the sealed seam measured by the seal strength test method may be about 6.0N/15mm or more.
In yet another aspect, a thin layer composition is provided. The thin layer composition comprises 10g/m2Or less, comprising at least about 20 wt% of an ethylene-based polymer. The ethylene-based polymer may have one or more of the following: a) a melt index of about 5g/10min to about 30g/10 min; b) a melt elastic modulus G' (G ═ 500Pa) at 170 ℃ of less than 15 Pa; c) a relaxation time λ of less than 0.003s at 170 ℃; d) at least two secondary melting temperature peaks between 110 ℃ and 120 ℃; e) a weight average molecular weight (Mw) of about 10000g/mol to about 55000 g/mol; f) a molecular weight distribution (Mw/Mn) of from about 2.0 to about 5.0; and g) the Mz/Mw ratio is from about 1.5 to about 2.1.
Brief description of the drawings
Fig. 1 shows the results of a seal strength test on paper substrates coated with various polymer coating compositions, which have seal portions formed at 100 ℃ and 110 ℃.
Fig. 2 shows the results of T-peel testing on samples formed by sealing paper substrates coated with various polymer compositions to uncoated, but printed plates, with a seal formed at 130 ℃.
Fig. 3 shows the results of seal strength tests on paper substrates extrusion coated with various polymer coating compositions, wherein the coating process was performed at a laminator line speed of 300 meters/min and a set temperature of 315 ℃.
Fig. 4 shows the results of seal strength tests on paper substrates extrusion coated with various polymer coating compositions, wherein the coating process was performed at a laminator line speed of 100m/min and a set temperature of 315 ℃.
Fig. 5 shows the results of seal strength tests on paper substrates coated with various polymer coating compositions, wherein the coating process was performed at laminator line speeds of 100m/min and 300 m/min.
FIG. 6 shows the neck-in values for various polymer coating compositions.
Fig. 7 shows the results of the seal strength test on paper substrates coated with various polymer coating compositions, which have seal portions formed at 100 ℃ and 110 ℃.
Fig. 8 shows the results of seal strength tests on paper substrates coated with various polymer coating compositions, wherein the coating process was performed at laminator line speeds of 100m/min and 300 m/min.
Detailed Description
Overview
In various aspects, polymeric coating compositions and articles coated with the polymeric coating compositions are provided. In one or more aspects, the polymeric coating composition can include an ethylene-based polymer that exhibits desirable melt properties, flow behavior, and molecular weight distribution. It has been surprisingly found that this combination of melt properties and molecular weight distribution allows for the formation of unexpectedly thin coatings, while still providing advantageous properties as a top coat, such as seal strength.
Traditionally, Low Density Polyethylene (LDPE) has been used to coat paper or paperboard, for example, to form coated food or beverage products. Such LDPE coatings can be used to impart various properties, such as protection from moisture or protection from physical handling. The LDPE coating may also be used as a medium for sealing a portion of an article. However, conventional LDPE coatings are limited in their processability, such as draw down (ability to form a film without breaking) at high line speeds and/or adhesion to paper-based substrates in conventional processing conditions. While converters may be used to help mitigate adhesion loss, this can adversely affect the hot tack (hot tack) performance of such coating compositions.
The polymeric coating compositions disclosed herein alleviate one or more of the problems described above. For example, in certain aspects, the polymer coating composition includes an ethylene-based polymer in an amount of at least about 20 wt%. In such aspects, the ethylene-based polymer exhibits:
a) a melt index of about 5g/10min to about 30g/10 min;
b) a melt elastic modulus G' (G ═ 500Pa) at 170 ℃ of less than 15 Pa;
c) a relaxation time λ of less than 0.003s at 170 ℃;
d) at least two secondary melting temperature peaks between 110 ℃ and 120 ℃;
e) a weight average molecular weight (Mw) of about 10000g/mol to about 55000 g/mol;
f) a molecular weight distribution (Mw/Mn) of from about 2.0 to about 5.0; and
g) the Mz/Mw ratio is from about 1.5 to about 2.1.
In certain aspects, the polymeric coating composition can include a blend of two or more polymers. In one aspect, the blend can include the ethylene-based polymer as a first polymer component in an amount from about 20 wt% to about 80 wt%, and a second polymer component in an amount from about 20 wt% to about 80 wt%. The second polymer component may include: low density polyethylene; ethylene acrylic acid copolymers; ethylene-methacrylic acid copolymers; ethyl-methyl acrylate copolymers; a polymer produced by polymerizing at a pressure of 50MPa-g or more; or mixtures thereof. In various aspects, the polymer coating composition may also be added with organic or inorganic additives, which are discussed further below.
Surprisingly, it has been found that the above-listed properties of ethylene-based polymers (alone or in a polymer blend) can be beneficial in the formation of thin polymer coating compositions. For example, the polymer coating composition may exhibit enhanced draw down and necking in processability, which may facilitate the application of thin coatings to substrates at high line processing speeds. Furthermore, it has been surprisingly found that these thin coatings of the polymeric coating compositions described herein can provide enhanced seal strength to the coated article at similar coating weights as compared to conventional polymeric coatings.
For convenience, in this description, specific reference is made to a polymeric coating composition for use as a coating on a paper substrate. It is to be understood that these references set forth a more general concept of thin coatings, including ethylene-based polymers that provide unexpected benefits independent of the particular substrate type.
Polymer coating composition
As noted above, in certain aspects, the polymer coating composition can include an ethylene-based polymer having the following properties:
a) a melt index of about 5g/10min to about 30g/10min, or about 10g/10min to about 25g/10min (the technique for determining melt index as used herein is described in ASTM D-1238, 2.16kg, 190 ℃);
b) a melt elastic modulus G' (G ″ ═ 500Pa) at 170 ℃ of less than 15Pa (the technique for determining melt elastic modulus as used herein is described in WO 2005/019333);
c) a relaxation time λ of less than 0.003s at 170 ℃;
d) at least two minor melting temperature peaks between 110 ℃ and 120 ℃. The technique for determining the melting temperature peak as used herein is based on ASTM D-3417/D3418. In such a technique, a non-airtight Tzero pan from TA instruments and a target sample weight of 3.5mg (which has been adjusted in a controlled laboratory at 23 ℃ ± 2 ℃) may be used, enthalpy may be determined by linear integration, and a TA Q2000 DSC may be used. An exemplary DSC method for determining the melting temperature peak of polyethylene may comprise: equilibrating at 150 ℃, isothermally for 3 minutes, ramping to 0 ℃ at 10 ℃/min, isothermally for 3 minutes, and ramping to 150 ℃ at 10 ℃;
e) the weight average molecular weight (Mw) is from about 10000g/mol to about 55000g/mol (the technique for determining the number average molecular weight (Mn), weight average molecular weight (Mw) and Z average molecular weight (Mz) is described later);
f) a molecular weight distribution (Mw/Mn) of from about 2.0 to about 5.0; and
g) the Mz/Mw ratio is from about 1.5 to about 2.1.
In certain aspects, the ethylene-based polymer can exhibit a density of about 0.910g/cm3Or greater (techniques for measuring density are described in ASTM D4703/D1505).
It should be understood that the ethylene-based polymer is not limited to any particular method of preparation. In certain aspects, the ethylene-based polymer may be polymerized in the presence of a single site catalyst, such as a single site catalyst comprising a metallocene. Examples of metallocene catalysts, resins, and methods of manufacture are described in U.S. patent No. 6932592. It is noted that not all ethylene-based metallocene polymers may provide the combination of properties described herein.
In any embodiment, the ethylene-based polymers may be those described herein as PE1 type polyethylene, PE2 type polyethylene, or blends of the foregoing.
Polyethylene of PE1 type
The polyethylene, hereinafter referred to as polyethylene of the type PE1, comprises ≥ 50.0% by weight of polymer units derived from ethylene and ≤ 50.0% by weight, preferably from 1.0% by weight to 35.0% by weight, even more preferably from 1% by weight to 6% by weight of polymer units derived from C3-C20α -polymer units of an olefinic comonomer, preferably hexene or octene the polyethylene of PE1 preferably has a Composition Distribution Breadth Index (CDBI) of 60.0% or more, preferably from 60.0% to 80.0%, the polyethylene of PE1 may have a density of from 0.910 to 0.950g/cm3(preferably 0.915-0.940 g/cm)3Preferably 0.918-0.925g/cm3). Melt index (I) according to ASTM D1238(190 ℃/2.16kg) for polyethylene of PE1 type2.16) It may be 1 to 500g/10min, in particular 5 to 30g/10 min. Preferably these polymers are metallocene polyethylenes (mPE). Polyethylene of the PE1 type may be sold under the trade name ExcedTMmPEs are available from ExxonMobil Chemical Company. G 'typical of such linear polyethylene'vis0.95 or more, preferably 0.96 or more and can be prepared by a gas phase polymerization supported catalyst having a bridged bis (alkyl substituted dicyclopentadienyl) zirconium dichloride transition metal component and a methylaluminoxane cocatalyst.
Polyethylene of PE2 type
Suitable polyethylene polymers of the PE2 type may be ethylene and one or more polar comonomers or C3-C10α -copolymers of olefins typically, polyethylene polymers of the PE2 type useful herein comprise 99.0 to about 80.0 wt%,99.0 to 85.0 wt%, 99.0 to 87.5 wt%, 95.0 to 90.0 wt% of polymer units derived from ethylene and about 1.0 to about 20.0 wt%, 1.0 to 15.0 wt%, 1.0 to 12.5 wt%, or 5.0 to 10.0 wt% of polymer units derived from one or more polar comonomers, based on the total weight of the polymer suitable polar comonomers include, but are not limited to, vinyl ethers such as vinyl methyl ether, vinyl N-butyl ether, vinyl phenyl ether, vinyl β -hydroxy-ethyl ether, and vinyl dimethylamino-ethyl ether, olefins such as propylene, butene-1, cis-butene-2, trans-butene-2, isobutylene, 3,3, -dimethylbutene-1, 4-methylpentene-1, octene-1, and styrene, vinyl type esters such as vinyl acetate, vinyl butyrate, vinyl pivalate, and vinyl carbonate, halogenated olefins such as vinyl fluoride, vinylidene fluoride, tetrafluoroethylene, vinylidene chloride, ethylene dichloride, diethyl tetrachloroethylene and diethyl methacrylate, N-N-butyl methacrylate, N-ethyl methacrylate, N-butyl methacrylate, N-ethyl methacrylate, N-3-N-butyl methacrylate, N-2-ethyl methacrylate, N-2-ethyl methacrylate, N-methyl-ethyl methacrylate, N-2-ethyl methacrylate, N-methyl-ethyl methacrylate, N-methyl-ethyl methacrylate, N-methyl methacrylate, N-ethyl methacrylate, N-methyl-ethyl methacrylate, N-methyl methacrylate, N-ethyl methacrylate, N-Oxysilanes, N-vinylcarbazole, N-vinyl-N-methylacetamide, vinyldibutylphosphine oxide, vinyldiphenylphosphine oxide, bis- (2-chloroethyl) vinylphosphonate, and vinylmethylsulfide.
Melt index (I) of said polyethylene polymer of PE2 type measured according to ASTM D1238, 2.16kg, 190 ℃2.16) It may be 1 to 30.0g/10min, in particular 5 to 20g/10 min.
Polymer blends
In various aspects, the polymeric coating composition can comprise a polymer blend. In such aspects, the polymer blend can include an ethylene-based polymer blended with a second polymer component. In certain aspects, the second polymer component can exhibit a melt index of from about 1g/10min to about 30g/10min, or from about 5g/10min to about 20g/10 min. In one or more aspects, the second polymer component can be a low density polyethylene; ethylene acrylic acid copolymers; ethyl-methyl acrylate copolymers; ethylene-methacrylic acid copolymers; or mixtures thereof. It will be appreciated that other blend partners (partner) may also be present in the polymer blend, as long as such polymer blend enables a thin coating, for example a coating weight of about 15g/m at high line speeds2Or less, or the coating weight is about 10g/m2Or smaller.
In various aspects, the ethylene-based polymer may be present in the polymer blend in an amount of about 20 wt% to about 80 wt%; from about 30 wt% to about 70 wt%, or from about 40 wt% to about 70 wt%. In the same or alternative aspects, the second polymer component of the polymer blend can be present in an amount of about 20 wt% to about 80 wt%; from about 30 wt% to about 70 wt%, or from about 40 wt% to about 70 wt%.
In certain aspects, the polymer coating composition includes the ethylene-based polymer in the absence of a second polymer component. In this aspect, the ethylene-based polymer may be present in an amount of at least about 70 wt%, at least about 90 wt%, at least about 95 wt%, or at least about 99 wt%.
In various aspects, the polymeric coating composition can optionally include one or more additives. The additives may include fillers such as inorganic fillers, antioxidants, anti-blocking additives, UV stabilizers, heat stabilizers, plasticizers, anti-blocking agents, mold release agents, antistatic agents, pigments, colorants, dyes, waxes, silicas, processing aids, and the like. The additive may be present in the polymer composition in an amount of less than about 15 wt%, less than about 10 wt%, or less than about 8 wt%.
In one aspect, the additive comprises an inorganic filler, such as talc, CaCO3Or mixtures thereof. In such aspects, the inorganic filler can facilitate processing (e.g., cutting) of a film or coating formed from the polymer coating composition.
As mentioned above, the polymer coating composition may be a film composition having a coat weight of about 15g/m2Or less, about 13g/m2Or less, about 12g/m2Or less, about 10g/m2Or less, about 8g/m2Or less, or about 5g/m2Or smaller.
In various aspects, the polymeric coating composition can be formed using any conventional equipment and preparation methods, including dry combining the individual components together and then melting in a mixer, or mixing the individual components directly into a mixer (e.g., a Banbury mixer or a dry mixer), or into a single or twin screw extruder (which can include a compounding extruder and/or a side arm extruder used downstream of the polymerization process or in-line blending in a converter operation).
Coated article
As noted above, in certain aspects, coated articles are described that include a substrate coated with at least one layer of the above-described polymeric coating compositions. In certain aspects, the substrate comprises a fibrous substrate, such as paper or paperboard. It is to be understood that substrates other than fibrous substrates are also contemplated, such as metal and/or plastic substrates.
The coated articles described herein may be used as containers for food, beverages, cosmetics, or other products. Exemplary coated articles include disposable beverage cups, cosmetic cream or lotion containers, ice cream containers, take-away food containers, and the like.
In various aspects, the coated article may comprise one, two, three, or more layers coated onto one or more surfaces of a substrate. As discussed further below, the composition and/or coating weight of each layer may be different depending on whether such layer is a single layer in a single layer coated article or one of multiple layers on a coated article. For ease of description, the foregoing relates to a coated article designed as a food or beverage container; however, the same or similar properties discussed in this section may also apply to coated articles designed for use with non-food or beverage containers.
In aspects in which the coated article is a monolayer coated article, the monolayer comprises the polymer blend described above in relation to the polymer coating composition. As mentioned above, the polymer coating compositions exhibit certain processing properties that are advantageous at high line speeds and low coating weights, e.g., about 15g/m2Or less, about 10g/m2Or less, about 8g/m2Or less, or about 5g/m2Or smaller to coat the substrate efficiently and effectively. In such aspects, the ethylene-based polymer component of the blend can provide desirable processing and sealing properties, while the second polymer component of the polymer blend provides a good balance between processability and end-use properties.
Surprisingly, the single layer polymeric coating, while present in thin layers at lower coating weights than conventional coated articles, exhibits enhanced seal strength. For example, when the coated article includes at least one sealed seam sealed via a single layer of polymeric coating, the seal strength of the sealed seam is at least about 6N/15mm, at least about 7N/15mm, or at least about 8N/15 mm. The seal strength may be measured as discussed further below in relation to the examples.
In various aspects, the monolayer polymeric coating may be present on both (opposing) surfaces of the substrate. In an alternative aspect, the single layer polymeric coating may be present on the food and/or beverage contacting side of the coated article and the opposing surface of the substrate is uncoated.
As discussed above, in an alternative aspect, the coated article can include at least two polymeric coatings on the substrate. For example, a first polymeric coating may be secured to one surface of the substrate, and a second polymeric coating may be secured to the first polymeric layer such that the first polymeric layer is located between the substrate surface and the second polymeric coating. In such aspects, the first polymeric coating layer secured to the substrate functions as a "tie" layer and may provide adhesion to the substrate, while the second polymeric coating layer secured to the first polymeric coating layer functions as a "seal" layer to provide a barrier between the beverage or food product and the substrate, and/or to form a sealed seam in the coated article.
In certain aspects, the first polymer layer may comprise one or more functionalized copolymers or terpolymers, or homopolymers or copolymers. A non-limiting list of examples of functionalized copolymers or terpolymers includes ethylene acrylic acid copolymers (EAA), such as ExxonMobil EscorTMEthyl-methyl acrylate copolymers (EMA), e.g. ExxonMobil OptemaTMResins, ethylene n-butyl acrylate copolymers (EnBA), e.g. ExxonMobil EnBATMResins, or maleic anhydride-functionalized polyolefins (homopolymers or copolymers), e.g. ExxonMobil ExxelorTMIn various aspects, the homopolymer or copolymer in the first polymer layer may comprise an ethylene homopolymer and/or an ethylene copolymer, including an ethylene-hexene copolymer, or other α -olefin copolymers.
In such aspects, the first polymer layer is selected to provide sufficient adhesion to the substrate. In such a wayThe adhesive bonding layer is applied at a relatively low coating weight, for example about 7g/m2Or less, or about 5g/m2Or smaller.
In such aspects, the second polymeric layer comprises the polymeric coating composition described above. For example, in such aspects, the second polymer layer can include the ethylene-based polymer described above, alone or in a polymer blend as described above.
The second polymer layer may be about 15g/m at a coating weight2Or less, about 13g/m2Or less, about 12g/m2Or less, about 10g/m2Or less, about 8g/m2Or less, or about 5g/m2Or smaller, which is a reduced coating weight for the sealant layer (and food contact layer) compared to conventional sealant layers. It has been surprisingly found that a second polymer layer at such a reduced coating weight can exhibit sufficient or enhanced seal strength when at least a portion of the coated substrate forms a sealed seam. For example, a coated article described herein comprising first and second polymer layers can have a sealed seam with a seal strength of at least about 6N/15mm, at least about 7N/15mm, or at least about 8N/15 mm.
In one or more aspects, the coated article may include a third polymeric layer on one or both sides of the article. In certain aspects, the third polymer layer can be secured to the second polymer layer and opposite the first polymer layer. In such aspects, the third polymer layer can have the same parameters as the other polymer layers described above. In various aspects in which the coated article includes three polymer layers, each of the three polymer layers can have the same or similar polymer composition.
Method of forming a coated article
The coated article may be manufactured according to any conventional method. For example, the coated article may be manufactured via extrusion coating, coextrusion coating, and lamination processes known to those skilled in the art. In aspects in which the coated article includes a polymeric coating on opposing sides of the substrate, the substrate can be coated on the first side via extrusion coating or coextrusion coating prior to coating the second side.
In various aspects, as discussed above, the coated article can include a sealed seam, which can be sealed via a polymeric coating composition. In such aspects, one end of the coated article can be sealed to the other end of the coated article, to a portion of a respective substrate (coated or uncoated), or a combination thereof. In such aspects, the coated article may be exposed to thermal energy to promote formation of a sealed seam. It should be understood that any number of sealed seams may be present in the coated article, depending on the desired article. Any conventional apparatus or method may be used to form the article into the final coated article.
Molecular weight testing method
The distribution and moment (moment) of molecular weight (Mw, Mn, Mw/Mn, etc.) was determined by high temperature gel permeation chromatography (Polymer CharGPC-IR) equipped with an infrared detector IR5 based on a multichannel bandpass filter, an 18-angle light scattering detector and a viscometer. Three
The concentration (c) at each point of the chromatogram was calculated from the baseline-subtracted IR5 broadband signal intensity (I) using the following equation:
c＝βI，
where β is the mass constant determined using the PE standard. Mass recovery is calculated from the ratio of the integrated area of the concentration chromatography within the elution volume and the injection mass (which is equal to the predetermined concentration multiplied by the injection loop volume).
Conventional molecular weights (IR MW) were determined by combining the universal calibration relationship with a column calibration using a series of monodisperse Polystyrene (PS) standards of 700-10M. The MW at each elution volume is calculated using the following equation:
where the variables with subscript "PS" represent polystyrene and those without subscript represent test samples in this method, αPS0.67 and KPS0.000175, and α and K are a series of empirical formulas established by ExxonMobil and disclosed in the literature (t.sun, p.branch, r.r.chance, and w.w.graessley, Macromolecules, volume 34, stage 19, page 6812 and 6820, (2001)).
Nominal MHK 0.000534, nominal MHa 0.695; dn/dc is 0.1048 mL/mg; a2 ═ 0.00150.
All concentrations are in g/cm3Molecular weights are expressed in g/mol and intrinsic viscosities are expressed in dL/g, unless otherwise indicated.
Example-thin film Polymer component
In the following examples, various thin layer polymer coatings and combinations of such thin layer polymer coatings are described. A thin layer of a polymer coating corresponds to a coating comprising one or more of the following types of polymers.
Low density polyethylene a (ldpe a) represents a commercially available low density polyethylene resin. The melt index of LDPE A was 8.2g/10min and the peak melt temperature was 106 ℃. LDPE A does not have a secondary melting temperature peak between 110 ℃ and 120 ℃. In other applications, LDPE a is traditionally used as a coating for applications where good sensory properties of water vapor are desired.
Low density polyethylene b (ldpe b) represents another commercially available low density polyethylene coating. The melt index of LDPE B is 5.0g/10min and the peak melt temperature is 105 ℃. In other applications, LDPE B is traditionally used for low speed extrusion coating and its low neck-in properties. LDPE B also has good organoleptic properties.
Copolymer C is a commercially available ethylene-acrylic acid copolymer resin. The melt index of copolymer C was 8.2G/10min, the peak melting temperature was 102 ℃, and the melt elastic modulus G' (G ═ 500Pa) at 170 ℃ was greater than 15 Pa. The copolymer C also has a weight average molecular weight (Mn) outside the range of the weight average molecular weight (Mn) of the ethylene-based polymer described above. In other applications, copolymer C is traditionally used for extrusion coating and coextrusion coating, and has good adhesion properties to various surfaces.
Ethylene-based polymer 1(EB polymer 1) is a commercially available metallocene ethylene-hexene copolymer. In other applications,
Ethylene-based polymer D (EB polymer D) is another commercially available metallocene ethylene-hexene copolymer with good tensile properties and impact and puncture toughness. The melt index of EB polymer D was-3.5 g/10 min.
As used herein, "lambda relaxation time" is calculated by dynamic frequency scanning using an ARES rotational rheometer at 170 ℃ in a nitrogen atmosphere using a 25mm diameter plate-plate geometry. The strain is maintained at less than or equal to 10% and the frequency is varied from 100rad/s to 0.2rad/s and 5 points are measured per decade. The dynamic modulus (i.e., storage modulus G' and loss modulus G ") was recorded and the norm complex viscosity was calculated according to
η ω ═ G'2+ G "2
The norm of the complex viscosity is then fitted with a Cross model according to
η ω ═ η 01+ λ ω 1-
where η 0 is the zero shear viscosity, λ is the average relaxation time, and n is the shear-thinning index.
In the following table, the term "coating weight" refers to the thickness of the polymer coating, expressed in grams (g/m) of the weight of the polymer coating composition per square meter2)。
In the following table, "speed (meters per minute)" refers to the speed of the laminator or extrusion coating line in which the polymer coating composition is applied to a substrate, and is expressed in meters per minute (m/min).
The coated paper samples described and analyzed in the table below were made according to the following procedure. Single and co-extrusion coating was performed using 2.5 inch and 3.5 inch extruders, 28: 1L/D. The 750mm diameter roll used was matte finished and kept as cold as possible during operation. The paper substrate was 70 grams per square meter (g/m)2) Kraft paper, which was corona discharge treated on the production line prior to coating. The air gap was kept at 170 mm.
In the following table, "seal strength test" refers to the measurement of the strength of the sample seal and the seal portion. The sample sealing procedure is based on ASTM F2029. First, a paper substrate is coated with the coating composition specified in the table at a specific speed and coating weight. Heat seals were prepared under standard laboratory conditions. The sealing conditions included a 5mm sealing bar with a smooth surface, a time of 0.5 seconds and a pressure of 500N. Heat sealing is carried out at several temperatures, for example 90-100 ℃, 110 ℃ or 120 ℃. The sealed sample was conditioned in a thermostated laboratory at 23 ℃ +/-2 ℃ and 50% +/-relative humidity for at least 40 hours. The heat sealing force was tested based on ASTM F88. Each tail of the sealed specimen was secured in opposing clamps spaced 20mm apart and the sealed portion remained unsupported while the test was conducted. The test speed for measuring the heat-sealing force was 100 m/min. The 100N chamber of the Zwick machine gives the average heat seal force in "N/15 mm".
In the following table, "T-peel test" refers to a paper cup to be in one portion and 70g/m2The force required to peel apart the seal formed between the paper substrates that have been coated with the coating compositions specified in the tables. The samples were prepared by cutting the paper cup to flatten the sidewall of the cup. The flattened outer sidewall and paper base of the cup were sealed together using a Kopp heat sealer using a 20mm smooth surfaced sealing bar at a pressure of 1600N for 1 second. The seal portions were formed at the temperatures specified in the table. The sealed sample was conditioned in a thermostated laboratory at 23 ℃ +/-2 ℃ and 50% +/-relative humidity for at least 40 hours. The sealed samples were then cut into at least five 15mm strips with a sample cutter. The 15mm strip was then partially torn and the torn end was held in a fixed position by a clamp placed 20mm apart in a Zwick machine with a 100N chamber and a flat insert. The Zwick machine then measures the force required to tear the remaining seal. The Zwick machine gives the average heat seal force expressed as "N/15 mm".
In the following table, "necking" refers to the reduction in width of the polymer coating when extruded onto paper at line speeds of 25, 50, 100 and 200 meters/minute at 35rpm output.
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