Heat activated adhesives for bag closures
View Patent ↗A polymeric woven bag has a first panel and a second panel and an open end of the bag to be pinched closed. A first layer of heat activated adhesive material is on a portion of the bag to form an adhesive-to-adhesive seal by contact with a second layer of heat activated adhesive material on a portion of the bag. second panel, wherein the first adhesive layer and the second adhesive layer have respective heat activation temperatures below the softening point temperature of the polymeric bag material, and wherein sealing the bag end after the bag has been filled with contents by heat activating the first layer of adhesive material and the second layer of adhesive material at a temperature below the softening point temperature of the polymeric bag material.
1. A polymeric woven bag, comprising:
a polymeric outer layer;
an inner polymeric woven bag layer laminated to or adhesively adhered to the outer layer;
a first panel and a second panel and an open end of the bag to be pinched closed between the first panel and the second panel after filling the bag with contents, and wherein the bag is foldable along a fold line;
an adhesive layer on a portion of the first panel below the fold line to form an adhesive-to-adhesive seal by contact with a further adhesive layer on a portion of the second panel above the fold line, wherein the first adhesive layer and the further adhesive layer are dry and impervious to water, and are separate from each other while the bag end is open for filling the bag with contents, and wherein the adhesive layer and the further adhesive layer are heat activatable to adhesive states at a temperature below the softening point temperature of the polymeric material, while in contact with each other and while the bag is folded, to form the adhesive-to-adhesive seal; and
the adhesive layer and the further adhesive layer respectively comprise:
(a) ionomer dispersions in water, based upon poly (ethylene-co-methacrylic acid) (EMAA); or
(b) aqueous based dispersions or emulsions including water, acrylic polymer, polyester polyurethane resin, formaldehyde, ammonium hydroxide, alumina and further including ammonia as a combustion product.
2. The polymeric woven bag of claim 1 wherein the heat activated adhesive layers extend across an area of width ranging from ½ inch to 6 inches.
3. The polymeric woven bag of claim 1 wherein, the adhesive layer and the further adhesive layer comprise adhesive materials being dry after their application to the portion of the first panel and the portion of the second panel, respectively.
4. The polymeric woven bag of claim 1 wherein, each of the adhesive layer and the further adhesive layer comprises an adhesive material soluble in an air dryable solvent.
5. The polymeric woven bag of claim 1 wherein, each of the adhesive layer and the further adhesive layer comprises an adhesive material soluble in water and air dried.
6. The polymeric woven bag of claim 1 wherein, the adhesive layer and the further adhesive layer are the same material.
7. The polymeric woven bag of claim 1 wherein the portion on the second panel comprises a sealing flap portion and the further adhesive layer is on the sealing flap portion.
8. The polymeric woven bag of claim 1 wherein the bag is foldable to fold the portion of the first panel on itself, and wherein the sealing flap portion is foldable toward the first panel to hold the bag folded by contact between the adhesive layer and the further adhesive layer.
9. The polymeric woven bag of claim 8 wherein, the adhesive layer and the further adhesive layer are on opposite panels of the bag.
10. The polymeric woven bag of claim 8 wherein, each of the adhesive layer and the further adhesive layer comprises polymeric adhesive dispersed in water having a melt temperature below about 300° F. and below the softening point temperature of the polymeric material of the bag.
11. A method of making the polymeric woven bag of claim 1 , comprising:
a polymeric outer layer;
an inner polymeric woven bag layer laminated to or adhesively adhered to the outer layer;
a first panel and a second panel and an open end of the bag to be pinched closed between the first panel and the second panel after filling the bag with contents;
applying a heat activated adhesive layer on a portion of the first panel of the bag to be pinched closed between the first panel and the second panel after filling the bag with contents;
applying a heat activated further adhesive layer on a portion of the second panel, wherein the adhesive layer and the adhesive layer have respective heat activation temperatures below the softening point temperature of the polymeric material;
drying the adhesive layer and the further adhesive layer separately from each other;
applying heat at a temperature below the softening point temperature of the polymeric material to activate the adhesive layer and the further adhesive layer to adhesive states after the bag has been filled with contents; and
folding the bag to form an adhesive-to adhesive seal by contact between the heat activated adhesive layer and the heat activated further adhesive layer on a folded bag.
12. The method of claim 11 , comprising:
folding the bag to fold the first panel on itself to urge the further adhesive layer into contact with the adhesive layer on the first panel of the bag and form the adhesive-to-adhesive seal.
13. The method of claim 11 , comprising:
folding a flap portion of the second panel over the first panel to urge the further adhesive layer into contact with the adhesive layer on the first panel of the bag and form the adhesive-to-adhesive seal.
14. The method of claim 11 , comprising:
applying the heat activated further adhesive layer on the portion of the second panel, wherein the portion of the second panel comprises a sealing flap portion of the bag; and
folding the sealing flap portion of the bag to form the adhesive-to adhesive seal.
15. The method of claim 11 , comprising:
applying the heat while the adhesive layer and the further adhesive layer are not in contact with each other.
16. The method of claim 11 , comprising:
applying the heat while the adhesive layer and the further adhesive layer are in contact with each other.
17. The method of claim 11 , comprising:
applying the heat by passing the bag through a pinch sealing unit that blows hot air onto the adhesive layer and the further adhesive layer at a temperature below the softening point temperature of the polymeric material to activate the adhesive layer and the further adhesive layer to adhesive states.
18. The method of claim 11 , comprising:
applying the adhesive layer and the further adhesive layer simultaneously, wherein the adhesive layer and the further adhesive layer are the same material.
19. The method of claim 11 , comprising: extending the adhesive layers across an area of width ranging from ½ inch to 6 inches.
20. A method of making the polymeric woven bag of claim 1 , comprising:
forming a pinch closed bag end between a first panel and a second panel;
applying the adhesive layer on a portion of the first panel;
applying the further adhesive layer on a portion of the second panel,
activating the adhesive layer and the further adhesive layer to adhesive states after filling the bag with contents by applying heat at a temperature below the softening point temperature of the polymeric material; and
pinch closing the end of the bag to urge the adhesive layers into contact and to form an adhesive-to-adhesive seal.