Dual draw tape bag and method of manufacture

#The invention relates to the manufacture of flexible bags and particularly to the manufacture of draw tape bags from thermoplastic films having a tight closure.

#Bags made of plastic film such as thin polyethylene film have been used in various sizes Small bags are used in the packaging of sandwiches and the like; larger bags are used for shopping bags and even larger bags are used for containing trash. The present invention is particularly related to draw band bags having a tight closure.

#A particularly advantageous closure for such bags includes a draw band or tape constructed from the same polyethylene material. Draw tape bags of this type have been know for several years and are described in various patents such as, for example, U.S. Pat. No. 3,029,853--Piazze. Bags of this type are formed by two pliable plastic sheets joined to one another on three sides and open at a fourth. A tubular hem is provided at the open end of each sheet and contains a pliable thermoplastic strip. A hole intermediate the ends of each hem exposes the strip in the hems allowing them to be pulled through the openings and used as a handle while simultaneously closing the open mouth of the bag. A similar type bag is disclosed in U.S. Pat. No. 4,624,654--Boyd et al. The draw tapes in the bags disclosed in these patents are at the same level in both hems of the bag. Draw tape bags using two tapes at different parallel levels in the bags are disclosed in U.S. Pat. Nos. 3,547,341--Kirkpatrick and 3,738,568--Ruda. In both of these patents the openings for pulling the draw tapes are at the opposite edges of the bag.

#FIG. 1 is an elevational view of a dual draw tape bag embodying the present invention.

#FIG. 2 is a sectional view taken along the lines 2--2 in FIG. 1.

#FIG. 3 is a sectional view taken along the lines 3--3 in FIG. 1.

#The plastic draw tape bags of the present invention may be made from either high density polyethylene or from linear low density polyethylene or equivalent plastic materials. In the preferred form of the invention the bags are formed from a tube of polyethylene which is oriented in the direction of extrusion. Such materials for plastic bags are disclosed in U.S. Pat. No. 4,558,463--Boyd. Apparatus suitable for manufacturing draw tape bags of the present invention is disclosed in U.S. Pat. No. 4,624,654--Boyd et al and the disclosure therein is incorporated herein by reference thereto.

#Referring to FIGS. 1-5 it will be seen that a draw tape bag 10 according to the present invention includes a front panel 11 and a rear panel 12. The two panels preferably are formed from a tube of polyethylene which is oriented in the direction of extrusion. The bottom 13 of the bag 10 may be formed by a fold or heat seal joining the front and back panels 11 and 12. The tube is slit along the top and the two longitudinal free edges are folded over respectively against the adjoining panels 11 and 12 to provide a pair of longitudinal hems 15 and 16 of double layer thickness opposite the longitudinal fold edge of bottom 13. As shown in FIGS. 1 and 5 the opposite ends of the hems 15 and 16 are provided with openings or holes 18 and 19. Each of the hems 15 or 16 is provided with a pair of crossed tapes 20 and 21. After the draw tapes 20 and 21 have been inserted in the respective hems 15 and 16, the double layer thickness of each hem is longitudinally joined together along seal lines 22 and 23 to form opposed tubular channels each containing a pair of the crossed draw tapes 20 and 21.

#It will be noted that the tape 20 crosses over the tape 21 within their respective hems 15 and 16. One end of the draw tape 20 in hem 15 is below the hole 19 at one side of the bag 10 and the other end of draw tape 20 is in line with the hole 18 at the other side of the bag 10. One end of the second draw tape 21 o the pair in hem 15 is below the hole 18 at one side of the bag 10 and in line with the hole 19 at the other side of the bag 10. One of the ends of the draw tapes 20 are secured to one side of the bag 10 when the side heat seal 25 is made and one of the ends of the draw tapes 21 are secured to the opposite side of the bag 10 when the side heat seal 26 is made. The opposite or free ends of the draw tapes 20 are secured together when the side heat seal 26 is made to form a loop or annular draw tape and the opposite or free ends of the draw tapes 21 are secured together when the side heat seal 25 is made to form a loop or annular draw tape. It will be noted in FIG. 5 that the annular draw tape formed by tapes 20 passes through the annular draw tape formed by the tapes 21. Thus the draw tapes are crossed within the bag and are locked together like two links in a chain.