CN1035258A

CN1035258A - Polybag and manufacture method thereof and equipment

Info

Publication number: CN1035258A
Application number: CN 88101521
Authority: CN
Inventors: 爱德华·盖尔博特
Original assignee: Wilverley Mansion Ibv
Current assignee: Wilverley Mansion Ibv
Priority date: 1988-02-27
Filing date: 1988-02-27
Publication date: 1989-09-06

Abstract

This paper has introduced a kind of sack, and it comprises an antetheca and a rear wall, and an opening is arranged, and wherein front and back walls links together by pleat or folding.At least one folding of sack has vertical hot weld seam, and the hot weld seam is to be positioned on the inner side edge rather than centre fold of folding.The handle of sack is that the overall extension by front and back walls and folding forms.Can eliminate or reduce the damage of hot weld seam according to the produced sack of principle of the present invention.A kind of method and equipment thereof of making this sack is disclosed in addition.

Description

Polybag and manufacture method thereof and equipment

What the present invention relates to is thermoplastic bag, the manufacture method of thermoplastic bag particularly, and this polybag has one to run through the long hot weld seam of whole bag, therefore, has avoided concentrating along the stress of weld seam.

Past, the sack that clients are used, for example, shopping bag is made of paper.Recently, owing to these sacks of multiple reason by polybag, particularly the sack of polyethylene system replaces.These Polythene Bags have the not available strength characteristics of paper bag (particularly when making moist).In addition, usually near the opening of sack, it is made of independent handle parts the handle of paper bag, with sack be not an integral body, the handle of polybag then is that the overall extension by bag limit or bag wall forms.The polybag of this structure is called as " T-shirt " bag sometimes.

Polybag can comprise a plurality of complete joints, and these joints install on the main body of sack by die-cut position.Usually each sack is with the fixing bookbinding of its joint, forms the folded or bag group of bag.Each sack also can be torn at die-cut position and be separated.

United States Patent (USP) 4,165,832 have introduced a kind of sack that is used for bag stack structure.This polybag is shaped on the handle of broad at the top, to reduce bag handle is rolled into small cross sections in user's hand trend.In addition, this sack also comprises the stress off-load recess of handle and sack junction, to reduce the possibility that stress concentrates caused handle place to tear.

The polybag of the sort of pattern of studying generally is to be made by continuous thermoplastic light wall pipe (for example polyethylene), its method comprises cuts the basic configuration that pipe is made sack, folding back forms limit " folding " or pleat, and hot weld is to form the bag end of handle and involution.

Recently, making the diameter polyethylene pipe (also be called bobbin) bigger than used in the past caliber becomes a reality.Three times (or more) that are used for the pipe girth of bag before for example, the girth of these pipes can reach.These pipes promptly are cut into bar longitudinally, can make a plurality of less pipes simultaneously thus.For example, big pipe can be cut into three longitudinally bar to form three independently pipes, the operation of ensuing bag then can become operation simultaneously from operation successively, and sack of former like this manufacturing just can be made the sack of nearly triple amount in required time.

In addition, the expense that is used to make the extruder of pipe or bobbin is compared relative higher with the expense of other project of polyethylene bag production line.Therefore, use one of an extruder production to manage again longitudinal heat seal and become a plurality of small bobbins, rather than use many extruders directly to produce a plurality of small bobbins and will save cost significantly.Like this, the cost that uses large diameter pipe to make polybag obviously reduces.

When using a major diameter bobbin to make three minor diameter periosteums, two outside bobbins have a weld seam, and middle bobbin has two weld seams.These weld seams are positioned on the inside or centre fold at bag edge break pleat place.In use, when sack is packed thing into, these weld seams will bear bigger stress, just look like " tear line ", and along it, sack trends towards being torn by stress.In fact, the weld seam at crease center is the sack place of easy damage in use.Existing, inefficient processing method adopts weldless pipe to make sack, does not therefore have these weld seams.Improved method is made a plurality of pipes simultaneously with a large diameter pipe and is gone to make the making that sack can make sack and more effectively reach cheaply, but the ability that this sack in use meets with stresses is very limited.For fear of breaking of weld seam broken line place, adopt thick tear-proof material to make sack sometimes.Certainly these materials are more expensive than the plastics that are used to make solderless bagging, so the material cost that adopts the saving volume of a plurality of bobbin gained of longitudinal heat seal to be increased has again been offset.

The objective of the invention is to limit or reduce the trend that sack with one or more longitudinal seam occurs breaking along weld seam.

Sack of the present invention comprises an antetheca and a rear wall, and an opening is arranged, and by pleat or folding antetheca is linked to each other with rear wall herein.Made sack has vertical hot weld seam at least on a folding, and the hot weld seam is to be positioned at certain of inboard of folding a bit rather than on the centre fold.Sack preferably has a handle that is made of the overall extension of front and back walls and folding.Can eliminate or reduce the damage that hot weld is stitched according to the sack that principle of the present invention produces.

The present invention also comprises the method made from pleated sack.This sack is made by the thermoplastic of tubulose, and at least one hot weld seam is arranged.Make pipe extend into substantially cylindrical.Be applied to the pleat active force on the position that is sewed with certain distance on the pipe apart from hot weld, like this, the hot weld seam will have certain distance with the interior broken line at pleated position.

The present invention also comprises a device of making polybag, and this device comprises and is used to carry the input roller of plastic foil pipe and is used for to the pipe inflation so that the aerating device of formation garden tube.The garden tube has changed shape by behind the pleated device, and one of formation is pleated on the tube of garden.Pleatedly longitudinal seam is not overlapped on pleated interior position of broken line in the direction of being got on the tube of garden.

The garden tube of distortion becomes the pipe of band folding then by outlet roller, enter hot weld and cutter sweep again, carries out hot weld and cutting successively, forms single sack at last.

Shown in Figure 1 is the front view of manufacture process of the present invention.

Figure 2 shows that the side view of process shown in Figure 1.

Shown in Figure 3 is the part section end-view of process shown in Figure 1.

The front view of Fig. 4 manufacturing " T-shirt " bag according to the present invention.

Fig. 5 is the vertical view of sack shown in Figure 4 5-5 along the line.

Referring to each figure, particularly Fig. 1, it has shown the front view of manufacture process of the present invention.Continuous, flat thermoplastic film manages 2 by a cover input roller 4 tractions.

Used thermoplastic material is polyethylene normally, especially with LLDPE (LLDPE), low density polyethylene (LDPE) (LDPE), high density polyethylene (HDPE) (HDPE) and HMW(high molecular weight)-high density polyethylene (HMW-HDPE) for well, but also can use other thermoplastic material, comprise copolymer.

Before flat pipe 2 enters input roller 4, longitudinally cut by two independent hot cuttves 6, and be welded into three independent equal diameter pipes.Each hot cutter 6 cuts two walls of pipe 2, and burn-on in two sides of immediately each hot cutter 6 being caused then, forms two independent weld seams.

After passing through input roller 4, three independent pipes 10 are used gas inflated respectively and formation garden tube 12.Gas can be nitrogen, argon gas or other inert gas, also can be air or other gas.Each is pulled into three by the pipe 10 garden tubes 12 that form and overlaps independently outlet roller 16.The closed area that is formed by input roller 4 and outlet roller 16 is enclosed in gas in each

garden tube

12,12 need of each garden tube fill once gas when production process begins like this, in case substitute the bad for the good, then garden tube 12 can retain gas, and need not inflate (defective of removing the unprovoked plastics causes the gas effusion) again.

Each garden tube 12 all makes its distortion by flap 18 entering it separately before the outlet roller 16.Each garden tube is furnished with a pair of flap 18.The setting of every pair of flap should make external pressure be applied on the opposite side position of each garden tube circumference.Every pair of flap forms the wedge shape of an opening, like this, is drawn to two garden tubes 12 between the flap 18 and is out of shape gradually up to obtaining desirable maximum distortion.Being right after is input roller 16 after flap 18, and it flattens the garden tube 14 of distortion, draws from every pair of outlet roller 16 with pleated pipe 20, and each is with the centre fold 22 of the pleated pipe 20 maximum distortion position 19 corresponding to flap 18.

Every pair of flap 18 residing planes parallel with the axle of outlet roller 16.Shown in Fig. 3 (being the end-view of device shown in Figure 1), every cover outlet roller 16 axially tilting with respect to input roller 4.Angle between input and outlet roller is designated as " angle α " in Fig. 3.Figure 3 shows that the figure after strained garden tube 14 parts are excised.By adjusting the axial angle α of flap 18 and outlet roller 16 and input roller 4, the centre fold 22 of crease 21 is not overlapped with weld seam 8.

Weld seam 8 can change by changing angle α with respect to the accurate position of centre fold 22.For example: when angle α is 0 when spending, weld seam 8 overlaps with centre fold 22, and the setting of prior art is exactly like this.When angle α increased, the position of weld seam 8 will be away from centre fold 22.Angle α can continue to increase up to maximum angle, surpass this angle then weld seam 8 will drop on pleated 21 outside fully.

The scope of angle α depends on the distance of 28 in the centre fold 22 of the girth of garden tube 12 and crease 21 and outer broken line.Yet the girth of garden tube 12 (C) itself is again by the decision of the degree of depth (D) of bag 23 desired width (W) and each folding.Girth is defined as two times width (W) and adds four times the degree of depth (D) like this, or C=2W+4D, and angle α is defined as then:

α＝ (360（D）)/(2（W）+4（D）)

For example: desired bag width is 10 inch, and desired folding width is 2 inch, and then used angle α is according to the present invention:

α＝ (360°（2）)/(2（10）+4（2）) ＝ 728/28 ＝25.7°

Angle α can be set in the scope of 0 °＜α＜25.7 °, so that weld seam 8 is dropped between centre fold 22 and the outer broken line 28 like this.

The pipe 20 of the band folding of drawing from outlet roller 16 is hot weld and lateral dissection then, and to form single sack, sack 23 has the hot weld seam on its a bag top 24 and a bag end 25.Referring to Fig. 4, handle 26 can a die-cut part form on bag 23.

Shown in Figure 5 is the cross-sectional view of bag 23, has marked along the position of two weld seams 8 on crease wall limit.Weld seam 8 preferably be positioned at along crease 21 walls except centre fold 22 or on any point outside the broken line 28.Place the folding wall can guarantee that weld seam 8 can extend to back welding seam 25 from the overhead welding seam 24 of sack 23 weld seam, this structure can make the stress minimum on the weld seam 8, thereby obtains solid polybag.

Claims

1, a kind of method of continuous manufacturing band folding bag, this band folding bag is to be made by the pipe of thermoplastic material, the surface of this pipe has at least a vertical hot weld that runs through whole pipe range to stitch, and comprises following step:

Make tube expansion one-tenth garden tubular substantially;

Apply discounting power on the said expansion tube being in apart from said vertical hot weld seam preset distance, the interior broken line that makes hot weld seam and said folding is at a distance of predetermined distance.

2, the method for claim 1 also comprises: flatten the pipe of band folding, and laterally hot weld and cut said band folding pipe successively, to form single sack.

3, make the method for polybag, comprising:

The continuous thermoplastic plastic membrane's pipe of vertically cutting weld seam that has at least is provided;

Said pipe is sent into a cover input roller;

After said pipe is sent into input roller, give pipe inflation formation garden tube;

Change said garden barrel shape, form a pair of relative folding on the tube of said garden, each folding all has a centre fold, and the direction that each folding is got on the tube of said garden should make vertically cuts weld seam and do not drop on the centre fold of each folding;

The garden tube of distortion is sent into a cover outlet roller to form the pipe of band folding, and the direction that said outlet roller is got then can keep folding that forms on the tube of said distortion garden and the relative position of vertically cutting weld seam;

Successively laterally hot weld and each position of cutting said band folding pipe to form single sack.

4, the method for claim 3, wherein said deforming step comprises: draw said garden tube by a cover flap, said flap forms an opening wedge shape, and said garden tube is out of shape gradually up to forming said relative folding.

5, the method for claim 4, the axis of wherein said flap and said outlet roller at grade, said outlet roller is parallel with the axis of said input roller, but not in same plane.

6, the method for claim 4, wherein said continuous pipe are longitudinally cut before entering said input roller and are welded into three continuous pipes than minor diameter, and each narrow tube all is furnished with a cover flap and an outlet roller.

7, the method for claim 3, wherein said thermoplastic plastic membrane is a polyethylene.

8, the method for claim 7, wherein said polyethylene is selected from: LLDPE, low density polyethylene (LDPE), high density polyethylene (HDPE) and HMW(high molecular weight)-high density polyethylene.

9, produce the device of polybag, comprising:

Be used to carry and have at least one input roller device of vertically cutting the continuous thermoplastic plastic foil pipe of weld seam;

After said pipe is sent into said input roller device, give the aerating device of said pipe inflation with formation garden tube;

Offer said garden tube forms a pair of relative folding with the shape of change garden tube and on the tube of said garden discounting device, each folding has a centre fold, and each folding should make in the direction of being got on the tube of said garden and vertically cut on the center line that weld seam do not drop on each folding;

Be equipped with in order to form adjacent with said discounting device is with the outlet roller device of rolling over pipe, the direction that said outlet roller device is got can keep folding and the said relative position of vertically cutting weld seam that forms on the tube of said distortion garden;

Be used for hot weld successively and cut hot weld and the cutter sweep of said discounting pipe to form single sack.

10, a kind of polybag comprises:

Thermoplastic plastic membrane's pipe, it has at least one vertically to cut weld seam, and said Guan Yiduan has otch, and it has determined opening and two relative bag handles of bag;

A pair of relative folding is arranged on said pipe, and each folding has a centre fold, the direction that said folding is got on said pipe should make said vertically cut weld seam do not drop on each folding centre fold or outside on the broken line;

Horizontal hot weld seam is arranged at top and bottom at sack.