Semi-rigid heat-sealable laminates with permanent antistatic characteristics

• US 5,064,699 A
• Filed: 03/06/1990
• Issued: 11/12/1991
• Est. Priority Date: 05/19/1989
• Status: Expired due to Fees

• Current Assignee: Cryovac Incorporated (Sealed Air)
• Original Assignee: W R Grace & Company - CONN (WR Grace & Company)
• Inventors: Havens, Marvin R., Ebner, Cynthia L., Roberts, William P., Fowler, Stephen L.
• Primary Examiner(s): Seidleck, James J.
• Application Number:
  US07/489,411
• Time in Patent Office: 616 Days
• Field of Search: 428/35.7, 428/34.2, 428/500, 428/512, 428/522, 428/514, 428/80, 206/328, 206/464, 252/510
• US Class Current: 428/35.7
• CPC Class Codes: B32B 2307/21 Anti-static
• CPC Class Codes: B32B 2307/31 Heat sealable
• CPC Class Codes: B32B 2553/00 Packaging equipment or accessories not otherwise provided for
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/28 comprising synthetic resins not wholly covered by any one of the sub-groups B32B27/30 - B32B27/42
• CPC Class Codes: C08K 5/19 Quaternary ammonium compounds
• CPC Class Codes: C08L 23/08 Copolymers of ethene C08L23/16 takes precedence
• CPC Class Codes: C08L 2666/36 Nitrogen-containing compounds
• CPC Class Codes: C09J 123/08 Copolymers of ethene C09J123/16 takes precedence
• CPC Class Codes: Y10T 428/1303 Paper containing [e.g., paperboard, cardboard, fiberboard, etc.]
• CPC Class Codes: Y10T 428/1352 Polymer or resin containing [i.e., natural or synthetic]
• CPC Class Codes: Y10T 428/31855 Of addition polymer from unsaturated monomers
• CPC Class Codes: Y10T 428/31899 Addition polymer of hydrocarbon[s] only
• CPC Class Codes: Y10T 428/31906 Ester, halide or nitrile of addition polymer
• CPC Class Codes: Y10T 428/31935 Ester, halide or nitrile of addition polymer

Abstract

A semi-rigid, heat-sealable laminate with permanent antistatic characteristics comprising a semi-rigid packaging material having a coating of heat-sealable antistatic plastic. The antistatic plastic is a film of a modified acid copolymer. The modified acid copolymer is selected from (I) a mixture of (A) a polymer containing carboxylic acid moieties and (B) an antistatically effective amount of a quaternary amine, or (II) the acid/base reaction product of (A) a polymer containing carboxylic acid moieties and (C) an antistatically effective amount of an organic or inorganic base.

Claims

1. A semi-rigid heat-sealable, laminate with permanent antistatic characteristics comprising a semi-rigid deformable substrate having a surface with a surface portion for supporting an item to be packaged, and a heat-sealable, permanently antistatic layer extending over and bonded to said surface, said layer including a modified acid copolymer selected from:

(I) a mixture of (A) a polymer containing carboxyic acid moieties and (B) an antistatically effective amount of a quaternary amine;

or from

(II) an acid/base reaction product of (A) a polymer containing carboxylic acid moieties and (C) an antistatically effective amount of an organic base wherein (A), (B), and (C) are defined as follows;

(A) the polymer containing carboxylic acid moieties is a copolymer of (i) an alpha-olefin of the formula RCH═

CH₂ wherein R is H or C₁ to C₂₀ alkyl, C₁ to C₂₀ alkoxy, or C₆ aryl, and (ii) an alpha,beta-ethylenically unsaturated carboxylic acid, and

(B) the quaternary amine is of the formula

space="preserve" listing-type="equation">[(R.sup.1)(R.sup.2)(R.sup.3)(R.sup.4)N|.sup.+ [X|.sup.-

wherein

R¹ is selected from H, aryl, or C₁ to C₅₀ alkyl optionally having one or more non-contiguous C═

O or NHC═

O or --S-- or --O-- in the carbon chain, or the same as R² ;

each of R², R³, and R⁴ is the same or different and selected from H, C₁ to C₁₈ alkyl optionally substituted with one or more OH or from --(R⁵ --O)_a --H where a is an integer from 1 to 10 and R⁵ is ethylene or propylene; and

X is an anion selected from chloride, bromide, iodide, fluoride, nitrate, fluoborate, phosphate, C₁ to C₂₀ alkyl phosphate, sulfate, C₁ to C₂₀ alkyl sulfate, formate, C₁ to C₂₀ alkyl or C₆ to C₂₄ alkaryl or aryl sulfonate, acetate, trifluoroacetate, citrate, propionate, or tartrate, and

(C) the organic base is of the formula M ⁺ Y ^-, wherein M ⁺ is [R⁶ R⁷ R⁸ R⁹ N]⁺, where R⁶, R⁷, R⁸, and R⁹ are independently selected from a C₁ to C₄ alkyl, benzyl, 2-hydroxyethyl, or hydroxypropyl, and Y|^- is selected from hydroxide, C₁ to C₄ alkoxide, bicarbonate, or carbonate.

2. The laminate of claim 1 wherein the polymer containing carboxylic acid moieties is ethylene-acrylic acid or ethylene-methacrylic acid and the quaternary amine is of the formula wherein:

R¹ is C₄ to C₃₀ alkyl, straight or branched optionally including one or more ether linkages and each of R², R³ and R⁴ is the same or different and selected from methyl or ethyl, and X is chloride, methyl sulfate, ethyl sulfate, methanesulfonate, or toluenesulfonate.

3. The laminate of claim 1 wherein the polymer containing carboxylic acid moieties is ethylene-acrylic acid or ethylene methacrylic acid and wherein R⁶, R⁷, R⁸ and R⁹ are selected from methyl, ethyl, or C₂ H₄ OH, and Y|^- is hydroxide, methoxide, or ethoxide.

4. The laminate of claim 1 wherein the antistatic layer will exhibit polycarbonate compatibility and be free of causing crazing of polycarbonate at a stress condition of at least about 2500 psi (176 kg/cm²) and 120°

F. (48.9°

C.).

5. The laminate of claim 1 wherein said laminate has the form of an X with a center including said surface portion, opposing first and second arms, each of said first and second arms foldable over said center or over the other arm of said first and second arms when said other arm is folded over said center, a third arm with a slotted opening, said third arm foldable over said center and said first and second arms when said first and second arms are folded, a fourth arm opposing said third arm and foldable over said third arm when said third arm is folded over said center and said first and second arms, and a tabl on said fourth arm for being received into said slotted opening to releasably close said package when said fourth arm is folded over said third arm.

6. A package constructed from the laminate of claim 1 wherein said surface includes a continuous border portion surrounding said surface portion, and when a static-sensitive item is placed on said surface portion to be packaged, said package further includes a sheet of flexible, heat-sealable, antistatic film vacuum formed over said surface portion and bonded to the portion of said anti-static layer extending over said border portion to form an enclosure over said surface portion, which contains the static sensitive item.

7. The laminate of claim 1 wherein the polymer containing carboxylic acid moieties is an ionomer containing carboxylic acid moieties partially neutralized by a metal salt.

8. The laminate of claim 1 wherein the antistatic layer will dissipate an applied charge of ±

5000 Vdc in a static decay time less than about 3000 milliseconds and will have a surface resistivity from about 10⁵ to about 10¹² ohms/square.

9. The laminate of claim 8 wherein the static decay time is less than about 3000 milliseconds and the surface resistivity is from about 10⁵ to about 10¹² ohms/square, after a 24 hour water shower.

10. The laminate of claim 8 wherein the static decay time of less than about 3000 milliseconds and the surface resistivity is from about 10⁵ to about 10¹² ohms/square, after 12 days in a hot oven of about 70°

C.

11. The laminate of claim 1 wherein a triboelectric enhancer is present in the antistatic layer.

12. The laminate of claim 11, wherein said triboelectric enhancer is comprised of ethoxylated sorbitan ester, ethoxylated glycerol ester, coco amphopropionate, oleoamphopropyl sulfonate, or ethylene oxide propylene oxide copolymer.

13. A semi-rigid heat-sealable laminate with permanent anti-static characteristics comprising a semi-rigid deformable substrate having a surface with a surface portion for supporting an item to be packaged, and a heat-sealable, permanently antistatic layer extending over and bonded to said surface, said layer being resultant from mixing with heat, optionally with solvent, (A) a polymer containing carboxylic acid moieties and an antistatically effective amount of a modifier selected from either (B) a quaternary amine or (C) an organic base wherein (A), (B), and (C) are defined as follows:

(A) the polymer containing carboxylic acid moieties is a copolymer of (i) an alpha-olefin of the formula RCH═

CH₂ wherein R is H or C₁ to C₂₀ alkyl, C₁ to C₂₀ alkoxy, or C₆ aryl and (ii) an alpha,beta-ethylenically unsaturated carboxylic acid, and

(B) the quaternary amine is of the formula

space="preserve" listing-type="equation"> (R.sup.1)(R.sup.2)(R.sup.3)(R.sup.4)N|.sup.+ X|.sup.-

wherein

R¹ is selected from H, aryl, or C₁ to C₅₀ alkyl optionally having one or more non-contiguous C═

O or NHC═

O or --S-- or --O-- in the carbon chain, or the same as R² ;

each of R², R³, and R⁴ is the same or different and selected from H, C₁ to C₁₈ alkyl optionally substituted with one or more OH or from --R⁵ --O)_a --H where a is an integer from 1 to 10 and R⁵ is ethylene or propylene; and

X is an anion selected from chloride, bromide, iodide, fluoride, nitrate, fluoborate, phosphate, C₁ to C₈ alkyl phosphate, sulfate, C₁ to C₈ alkyl sulfate, formate, C₁ to C₈ alkyl or C₆ to C₂₄ alkaryl or aryl sulfonate, acetate, citrate, trifluoroacetate, propionate, or tartrate, and

(C) the organic base is of the formula M ⁺ Y|^-, wherein M|⁺ is [R⁶ R⁷ R⁸ R⁹ N]⁺, where R⁶, R⁷, R⁸, and R⁹ are independently selected from a C₁ to C₄ alkyl, benzyl, 2-hydroxyethyl, or hydroxypropyl, and Y ^- is selected from hydroxide, C₁ to C₄ alkoxide, bicarbonate, or carbonate.

14. A semi-rigid, heat-sealable laminate with permanently anti-static characteristics comprising a planar, semi-rigid deformable substrate having a surface with a surface portion for supporting an item to be packaged, and a heat-sealable, permanently antistatic layer extending over and bonded to said surface, said layer obtained from mixing with heat, optionally with solvent, ethylene-acrylic acid or ethylenemethacrylic acid and a quaternary amine of the formula [(R¹)(R²)(R³)(R⁴)N ⁺ [X ^- where R¹ is a C₄ to C₃₀ straight or branched alkyl optionally including one or more ether linkages, each of R² and R³ and R⁴ is the same or different and selected from methyl or ethyl, and X is chloride, methyl sulfate, ethyl sulfate, methane sulfonate, or toluene sulfonate.

15. A package according to claim 14, wherein the permanently antistatic layer will, after a 24 hour water shower, after 12 day oven aging at 70°

C., or after both, dissipate an applied charge of ±

5000 Vdc in less than about 3000 ms without having being subjected to irradiation from an electron beam.

16. A semi-rigid, heat-sealable laminate with permanently antistatic characteristics comprising a planar, semi-rigid deformable substrate having a surface with a surface portion for supporting an item to be packaged, and a heat-sealable, permanently antistatic layer extending over and bonded to said surface, said layer obtained from mixing with heat, optionally with solvent, ethylene-acrylic acid or ethylenemethacrylic acid and an organic base of the formula M|⁺ Y|^- where M ⁺ is R⁶ R⁷ R⁸ R⁹ N ⁺ wherein R⁶, R⁷, R⁸, and R⁹ are selected from methyl, ethyl, or C₂ H₄ OH, and Y ^- is hydroxide, methoxide, or ethoxide.

17. A package according to claim 16, wherein the permanently antistatic layer will, after a 24 hour water shower, after 12 day oven aging at 70°

C. or after both, dissipate an applied charge of ±

5000 Vdc in less than about 3000 ms.

18. A method for making a semi-rigid, antistatic, heat-sealable laminate with permanent antistatic characteristics comprising

(1) modifying an acid copolymer by mixing with heat, optionally with solvent, (A) a polymer containing carboxylic acid moieties and an antistatically effective amount of a modifier selected from either (B) a quaternary amine or (C) an organic base wherein (A), (B), and (C) are defined as follows:

(A) the polymer containing carboxylic acid moieties is a copolymer of (i) an alpha-olefin of the formula RCH═

CH₂ wherein R is H or C₁ to C₂₀ alkyl, C₁ to C₂₀ alkoxy, or C₆ aryl, and (ii) an alpha,beta-ethylenically unsaturated carboxylic acid, and

(B) the quaternary amine is of the formula

space="preserve" listing-type="equation">[(R.sup.1)(R.sup.2)(R.sup.3)(R.sup.4)N .sup.+ [X .sup.-

wherein

R¹ is selected from H, aryl, or C₁ to C₅₀ alkyl optionally having one or more non-contiguous C═

O or NHC═

O or --S-- or --O-- in the carbon chain, or the same as R² ;

each of R², R³ and R⁴ is the same or different and selected from H, C₁ to C₁₈ alkyl optionally substituted with one or more OH or from --(R⁵ --O)_a --H where a is an integer from 1 to 10 and R⁵ is ethylene or propylene; and

X is an anion selected from chloride, bromide, iodide, fluoride, nitrate, fluoborate, phosphate, C₁ to C₈ alkyl phosphate, sulfate, C₁ to C₈ alkyl sulfate, formate, C₁ to C₈ alkyl or C_y to C₂₄ alkaryl or aryl sulfonate, acetate, citrate, trifluoroacetate, propionate, or tartrate, and

(C) the organic base is of the formula M ⁺ Y ^-, wherein M ⁺ is [R⁶ R⁷ R⁸ R⁹ N]⁺, where R⁶, R⁷, R⁸, and R⁹ are independently selected from a C₁ to C₄ alkyl, benzyl, 2-hydroxyethyl, or hydroxypropyl, and Y ^- is selected from hydroxide, C₁ to C₄ alkoxide, bicarbonate, or carbonate, and

(2) applying a layer of said modified acid copolymer/quaternary amine mixture to a sheet of semi-rigid substrate.

19. The method of claim 18, wherein said layer is a permanently antistatic film which will, after a 24-hour water shower, after a 12 day oven at 70°

C., or after both, dissipate an applied charge of ±

5000 Vdc in less than about 3000 milliseconds.