GB2331288A

GB2331288A - Sawtooth cutter

Info

Publication number: GB2331288A
Application number: GB9902930A
Authority: GB
Inventors: Atsuya Ozawa
Original assignee: Dai Nippon Printing Co Ltd
Current assignee: Dai Nippon Printing Co Ltd
Priority date: 1994-12-20
Filing date: 1995-12-20
Publication date: 1999-05-19
Anticipated expiration: 2015-12-20
Also published as: GB9812808D0; GB2323074A; GB2331288B; GB2323074B; GB9902930D0

Abstract

A sawtooth cutter 2A is made of vulcanised fibre coated with a resin such as an ethylene-acrylic acid copolymer (ionomer), an ethylene-propylene copolymer or a vinyl-acetate-polyolefin copolymer. Preferably, the coating is between 3 and 6 g/m . Allows at least the ends of the sawtooth cutter to be heat or ultrasonically welded to a carton.

Description

SAWTOOTH CUTTER 1 2331288 The present invention relates to a sawtooth

cutter suitable for Putting an aluminum. foil or a wrapping film.

This application is divided from GB 9617012.1.

A cuboidal carton containing a roll of an aluminum foil or a plastic wrapping film and provided with a metallic sawtooth cutter having a sawtooth cutting edge and attached to one edge of the carton has prevalently been used. The aluminum foil or the plastic wrapping film is pulled out of the carton and cut with the sawtooth cutter.

Since the metallic sawtooth cutter cannot be incinerated, problems arise in the disposal of the carton. The use of nonmetallic sawtooth cutters, such as paper sawtooth cutters and vulcanized fiber sawtooth cutters, instead of metallic sawtooth cutters have been proposed, for instance, in JP-A Nos. 6-48428 and 6-144425.

Staking, which is employed in fastening a metallic sawtooth cutter to a carton blank, cannot be applied to fastening a nonmetallic sawtooth cutter, such as a vulcanized fiber sawtooth cutter, to a carton blank.

Therefore it is usual to bond such a sawtooth cutter adhesively to a carton blank with a hot-melt or an emulsion type adhesive (glue). JP-A No. 6-48428 uses ultrasonic welding for bonding a sawtooth cutter to a carton blank, and JP-A No. 6-144425 bonds a sawtooth cutter temporarily to a carton blank with spots of an adhesive, and then bonds the entire length of the sawtooth cutter to the carton blank by ultrasonic welding or heat-sealing. when the entire length of a sawtooth cutter is bonded to a carton blank with an adhesive, it sometimes occurs 1 is that the opposite end portions of -he sawtkooth cutter come off from the carton during use to spoil the appearance of the carton cr the sawtooth cutter comes off completely JErom -the carton and becomes unusable. Those troubles were exam-Ined or;causes and the following causes were found.

When bonding a sawtooth cutter to a carton blank with an adhesive, the adhesive is spread in a wid-1h narrower than -hat of the saw.I-Jcth cutter and in a length shorter than that of the sawtooth cutter to mrevent the adhesive from oozing from under the sawtooth cutter. Therefore, cart a-,-the cut-ter is not coated with -the adhesive.

Particularly, cr)cos-.;-e end of the sawtCoth cutter are not coated with the adhesive. Port ions no t coated with the adhesive are liable -1) come of.E. in some cases, a hvgrosccn-4c sa-w-loc--h absorbs moisture, L-ends ta extend and, consequently, c--mes the carton. Since a rela--vel- - - -- I- L- y h4 gh c)rce is exe---ed on the end norzions of the sawtooth -,,;h e n. c u t t i n g a n a 1 u m. n u m IF a -4 1 a r a..7 r a p pz rl g ---1m with the cutter, wha'ch causes the end cortions of the sawt-coth cutter to be liable --a =me off.

Thus, the cz)oos-.:-ke end ccri-.;Lons a.'-- the sawtooth cutter c-.P--en come c..Of or the cuttke--- often falls off from the cart-on during use.

When the entire length of- a sawtacth cutter is bonded to a carton blank by ultrasor.-'.c welding likemethods disclosed in JP-A Nos. 6-48428 and do, a lateraliv elongate horn is necessar- L y. Such a laterally elongate horn lacks in du--ab-'.1,-y and needs large Gutput power 'or - L- J_ sealing the joint of a large area of surfaces. Although a d-4'-sk-shaped horn like that, employed in jP-A No. 6-144425 may be used, the d4..sk-shamed horn needs an aooa--a--.us o:E a commlicated construction. When '--cnding the entire length o:E a sawtooth cutter to a cart-.n blank by heat-sealing, 1 U anniv heat and arge power is necessary, it is 0 cressure, uniformly -c the elongate joint of sur.E-aces, adhesive strengt'.-% 'is liable to he distributed irregularly, heat-sealJng takes much time, and the nroduc---Jv-'Xv- is lOw.

The present invention has been made in view of the foregoing problems and it has been an object to allow a bonding method for a sawtooth cutter capable of satisfactorily bonding a nonmetallic sawtooth cutter to a carton blank without requiring any ultrasonic welding machine -or any heat-sealing machine of a complicated construction and a high output capacity.

An object of the present invention is to provide a sawtooth cutter suitable for the aforesaid sawtooth cutter bonding method.

According to the present invention, a sawtooth cutter has at least one sawtooth edge and is formed from a vulcanised fiber sheet having a surface coated with a synthetic resin.

- 4 i5 -F-he entire length of. a sawtooth cutter is bonded to a carton blank with an adhes.L'.ve, and then at least the ocoosi'.-.e end portions of tIhe sawtooth cutter are bonded by u-l---.-ason-ic welding or hea'--sealing to the carton blank. Therefore, the comcsi-xe end portions of the sawtooth cutter, which are liable to come off, are bonded securely to carton blank and hence Cne sawtooth cutt-er will not come off during use. Since only the occcsite end portions having a small area o--'-: the sawtooth cutter need to be bonded bv ul7--rascnic we-d..';_ng or hea tseal ing, the opposite end -ort-Lons can securely be bonded to the carton blank bv an ultrasor.-,f.c welding machine or a 1,nleatl--sea-',,;Lng machine of a simple construction. When necessarl;, cctional portions of a smail area of the saw-Loc-L-h cutter, in addition to the ccmcs-4t,-e end portions, may be bonded to the carton blank by ultrasonic welding or heat-sealing. Preferably, the width and length ofr portions to be bonded by ultrasonic welding or heat-sealing to the carton blank are in the range of 5 to 20 mm to bond those portions to the'carton blank securely by low energy.

Since the sv-,itheL.-c resin =tained in the resinimpregnated pacer sheet forming the sawt-coth cutter melts and exerts adhes-Lon, the sawtooth cutter need not be subjected to a secondary process, such as a polvethylene coat-ing process, and can be bonded to th.e carton blank by ultrasonic welding or heat-sealing. Since the resin4-nnregna-t-ed pacer sheet absorbs mc.;.s--ure scarcely, the sawtooth cutter will not be deteriorated and nor come off from the carton blank due -o mcisture absorptJon during use. The sawtjoth cutter need not necessarily be bonded by the foregoing method; the step of banding the sawtooth cutter to the carton blank with an adhesive may be omitted - and the entire length of the sawtooth cutter may be bonded to the carton blank by ultrasonic welding or heat-sealing. BRIEF DESCRIPTION OF THE. DRJ:kWINGS

Figs. 1(a), 1(b) and 1(c) are schematic perspective views illust-r at-ing steps c-' a blonding met-hod of a sawtooth cutter in a preferred embodiment according to the present invention; FIgs. 2(a) and 2(b) are schematic side views oil an apparatus for carrying out steps of the banding method of a sawtooth cutter illustrated in F_.Lgs. 1(a) to 1(c) far forming a sawtoath cutter by punching and bonding the saw--coth cutter to a carton blank in d-f.4:eren-L- phases of cce.-r-a-.-Jcn, respectively; Fig. 3 is a schematic u-Ltras.-n-'-c welding machine emoloved in car.---Ji.ng out the bonding me-k-hcd of a sawtooth cutter illustrated in Figs.!(a) --a l(C); Fig. 4 is a schematic side view c--;- the ultrasonic welding machine c-. Lc Fig. 3; Fig. 5 is a schematic Plan view of a c=bination af a ca---.on blank and a sawtooth cutter formed by banding a sawtoc"k-.h cutter to a carton blank; F-Lg. 6 is a schematic plan view cf a carton blank and a sawtooth cutter to be bonded to the cart= blank; Fig. 7 is a schematic Perspective view of a carton formed by assembling the parts shown in Fig. 6; Fig. 8 is a schematic plan view of another combination c.' a carton blank and a sawtooth cutter formed bv bonding a sawtooth cutter --a a cartan blank at another position on the carton blank; and Fig. 9 is a schematic plan view of a sawt-coth cutter in a modification.

BEST MWE FOR CARRYING OUT THE I_.WENTION Preferred embcd-Jmen-s of the present invenzion will be described hereinafter.

F g. 6 shows a carton blank 1 and a nonmetallic saw4,-coth cutter 2 to be bonded --a the carton blank 1 by a bonding me-,hcd of a sawtooth cutter in a creferred embodiment according to the present invention which will be described later. The sawtoo-cn cutter 2 is made by cutting the le ading end of a long material along a zigzag line and has opposite sawtooth edges 2a and 2b. The sawtooth cutter 2 is attached to a hatched region 3 on the outer surface of the carton blank 1, and then the carton blank 1 is cartoned to make a carton 1A. The sawtooth edge 2a of the sawtooth cutter 2 projects from one edge of the carton 1A. An aluminum foil, a wrapping film or the like is held in the carton 1A. When using the aluminum foil, the wrapping film or the like, a necessary length of the aluminum foil, the wrapping film or the like is pulled out from the carton 1A and cut off with the sawtooth edge 2a of the sawtooth cutter 2. The sawtooth cutter 2 need not is necessarily be attached to the carton blank 1 at the position shown in Fig. 6; f or example, the same may be attached to a region 3A (a region along a tear score line 4) on the inner surface of a flap section la of the carton blank 1 as shown in Fig. 8.

The material from which the sawtooth cutter 2 is made is a nonmetallic material having a proper hardness enough to form a sawtooth cutting edge, and a melt-welding property that enables ultrasonic welding or heatsealing. A resin-impregnated paper sheet formed by impregnating a paper sheet containing long-fiber wood pulp as a principal component, and not containing any size or containing a small amount of size with a resin is a suitable material for forming the sawtooth cutter 2. A suitable resin content of the resin- impregnated paper sheet is in the range of 50 to 80 parts by weight to a paper sheet content of 100 parts by weight. The strength of the sawtooth cutter is insufficient when the resin content is less than 50 parts by weight, and a resin content exceeding 80 parts by weight makes resin- impregnation difficult. Size content of the paper sheet to be impregnated with the resin is determined so that the paper sheet can be impregnated with the resin in a resin content in the aforesaid range. The resin content can be controlled by adjusting sizing degree through the adjustment of size content.

The thickness of the resin impregnated paper sheet suitable for securing sharpness and strength required of the sawtooth cutter is in the range of about 0.2 to about 0.4 mm. Suitable resins to be impregnated into the paper sheet are hard, water-soluble acrylic resins including methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate and butyl methacrylate.

The resin impregnated paper sheet is used as a material for forming the sawtooth cutter without subjecting the same to a secondary process, for instance, for forming a resin film on its surface.

A vulcanized fiber is another material suitable for forming the sawtooth cutter. Since a vulcanized fiber does not have any welding property, at least one surface thereof to be set in contact with the carton blank 1 must be coated with a resin to provide the vulcanized fiber with a welding property. Suitable coating resins for coating a vulcanized fiber are ethylene - acryl ic- acid copolymers (ionomers), ethylene - propylene copolymers, vinyl -acetate-polyolef ine copolymers and the like. The vulcanized fiber may be coated with such a resin by a gravure coater. A desirable amount of the coating resin per unit area of the vulcanized f iber is in the range of about 3 to about 6 g/m' (dry base).

A bonding method of a sawtooth cutter in a preferred embodiment according to the present invention for bonding the sawtooth cutter formed from the aforesaid material will be described hereinafter. Referring first to Fig. 1(a), an adhesive 6 is extruded through an adhesive applicator nozzle 5 to apply the adhesive 6 to a required portion of carton blank 1 of a predetermined shape punched out from material, in which the carton blank 1 is moved in the direction of the arrow relative to the adhesive applicator nozzle 5. The carton blank 1 may be held stationary and the adhesive applicator nozzle 5 may be moved in a direction opposite the direction of the arrow. The adhesive may be any suitable adhesive such as a hot-melt adhesive or an emulsion adhesive. Suitable hot-melt adhesives, a--e, for example, EVAs (ethyl ene-vinyl -acetate copolymers), APPs PEs (polyethylenes), SISs (styreneisoprene copolymers), SBSs (styrenebutadiene copolymers) and polyamides.

The adhesive 6 is spread on the carton blank 1 in a region substantially corresponding to the entire length of the sawtooth cutter 2 as indicated in a hatched region in Fig. 5. The area coated with the adhesive 6 is f ar smaller than the total area of the sawtooth cutter 2 in order that the adhesive 6 may not ooze out from under the sawtooth cutter 2 when the sawtooth cutter 2 is pressed against the region coated with the adhesive 6. The opposite end portions 2c of a length in the range of, for example, about 2 to abut 5 mm of the sawtooth cutter 2 lie outside the region coated with the adhesive 6.

Then as shown in Fig. 1(b), the sawtooth cutter 2 of a predetermined shape is punched out from the leading end of a material 7 and the sawtooth cutter 2 is pressed against the region coated with the adhesive 6 of the carton blank 1 to bond the sawtooth cutter to the carton blank 1.

The sawtooth cutter 2 is formed by punching and bonded to the carton blank 1 by an apparatus shown in Fig. 2. Referring to Fig. 2, the apparatus comprises conveyor rollers 8 for conveying the carton blank 1, a table 9 for supporting the carton blank 1 at a portion including a region to which the sawtooth cutter 2 is bonded, a fixed die 10 provided at its free end with a sawtooth blade 10a, a movable die 11 provided at its free end with a sawtooth blade lla to be brought into engagement with the sawtooth blade 10a, a cylinder actuator for vertically moving the movable die 11, and sheet feed rollers 13 for feeding a length of the material 7 corresponding to the width of the sawtooth cutter 2 at a time. The apparatus functions as follows. Suppose that a length of the material 7 L L.1.

corresponding to the width of -he sawtooth cutter 2 is oroJected forward from the sawtooth blade 10a of the fixed die 10 as shown in Fig. 2(a) and held stationary. In this state the material 7 is held on the fixed die 10 by suction. The material 7 may be held on the &fixed die 10 by an appropriate mechanical clamping means instead of holding the same by suction.

In this state, a carton blank 1 having a region coated with the adhesive 6 is fed onto the table 9 and fixedly pcsitioned at a predetermined position. Then, as shown in Fig. 2(b), the movable die J.1 is lowered to cut off a sawtooth cutter 2 from the leading end portion of the material 7 in cooperation wi th the fixed die 10 and presses the saw", -ooth cutter 2 against the region =at-ed w-Lth the adhesive 6 of the carton blank 1. Then, the movable die 11 is::,a4-sed to its stlandby position, the cartlon blank 1 is delivered to the next process, and z-he s.,,.ee-- feed rollers 13 feeds the material 7 bv a length corresponding to the width of the sawt-coth cutter 2 for the next cycle of oceration. The same cycle of operation is repeated sawtooth cutters 2 a--a bonded to carton blanks 1 successivelv. Althcugh the subs tantially entire length of the sawtoc.'L..h cutter 2 is thus bonded to the carton blank 1 with the adhesive 6, the opposite end portions 2c of a small area of the saw-Looth cutter 2 lie outside the region coated with the adhesive 6 as shown.11n Fig. 5.

Then, as shown in Fig. 1(c), the opposite end portions of the sawtooth cutter 2 bonded to the cart-on blank 1 with the adhesive 6 is bonded to the car-ton blank 1 by ultrasonic horn units 20 included -in an ul-;_rasonL.c welding inachine shcwn in Figs. 3 and 4 by ultrasonic welding. Referring to Figs. 3 and 4, the ultrasonic welding machine c--mzrises cc)nve7or rollers 15 for conveying the ca---,c)n blank 1, a nair of anvils 16 discosed so that the opposite end portions oil the sawtoct.h cutter 2 '-,cnded to the carton blank 1 overlie the pair of anvils 116 when the ca--ton blank is 1 is stopped at a predetermined position, a main frame 17 disposed at a fixed position, support members 18 fixed to the main frame 17, horn holding members 19 vertically movably supported on the support members 18, L-he ul trasonic horn units.20;attached to the horn holding members 19, and pneumatic cvlinder actuators 22 for vertically moving the horn holding members 19. Each ultrasonic horn. unit 20 has, as principal components, a converter 20a, a booster 20b and a horn 20c.

The two ultrasonic horn units 20 bond the opposite end pork-ions of the saw-L-oo."-h cutter 2 bended to the carton blank 1 fixedly held at the pradetarmined ccs-.;-i4on to the carton blank 1, respectively. Each ultrasonic horn unit 20 is dIsmased so that the lower surface of t_he horn 20c, e., a working surface o.0 the horn 20c, is ab'e to cover the end portion 2c of the sawtooth cutter 2 and a narrow region con-l---guous with the periphery of the end portion 2c. The size c.-;- the lower surface of each horn 20c is deter-nined so that the end portion 2c c--9 the saw--ccth cutter 2 af a length in the range of about, 5 to about 20 mm, prefferably, a length of about 10 = can be welded to the carton blank 1. The effect ci: ultrason--c welding is insufficient and the end por-l--.,-ons 2c of the sawt=oth cutter 2 is liable to come off if the length of a welded portion of the end pcr-l--4ons 2c is less than 5 mm. The length of the end portions 2-- greater than 20 mm is not prefe-rable because the size of the ul trasonic horn uni ts 20 mus t be relatively large and the effect. oJES ultrasenic welding does nct increase significantly accord--"- .g t-o increase in the length of the end portions 2c to be welded to the carton blank 1 beyond 20 mm. Therefore, it is preferable that the length a.' the end portions 2c to be welded to the carton blank 1 bv ultrasonic welding in in afforesaid range. Ultrasonic welding conditions for welding t.he end portions of, JEor example, 10 mm by i5 mm in area are, for example kHz in csc-4-l-la-k---.n frequency, 3 kg/c-.n2 in pressure and The ultrasonic welding machine functions as follows. Referring to Figs. 3 and 4, the carton blank 1 provided on its upper surface with the sawtooth cutter 2 is conveyed to and fixedly positioned at a predetermined position. Then, the pneumatic cylinder actuator 22 are actuated to press the ultrasonic horn units 20 against the opposite end portions 2c of the sawtooth cutter 2 for ultrasonic welding. After the predetermined welding time for ultrasonic welding has elapsed, the ultrasonic horn units 20 are raised, the carton blank 1 is delivered to the next process and the next carton blank 1 is fed to complete one cycle of operation, The cycle of operation is repeated to weld the opposite end portions 2c of the sawtooth cutter 2 to the carton blank 1. Thus, the end portions 2c of the sawtooth cutter 2 lying over regions not coated with the adhesive 6 are welded firmly to the carton blank 1. The sawtooth edge 2a of the sawtooth cutter 2 must not be bonded to the carton blank 1. A region lb underlying the sawtooth edge 2a is coated with a releasing OP varnish and hence the sawtooth edge 2a cannot be welded to the carton blank 1 by ultrasonic welding. If there is any possibility that the sawtooth edge 2a is welded to the carton blank 1, the anvils 16 may belocated so that portions of the carton blank 1 corresponding to the sawtooth edge 2a are not on the anvils 16.

The carton blank 1 thus processed is delivered to the next process, the carton blank 1 is cartoned to make a carton 1A, and a roll of an aluminum fail or a wrapping film is put in the carton 1A for use. Since the opposite end portions 2c of the sawtooth cutter 2, which are liable to come off, are welded to the carton blank 1 by ultrasonic welding after bonding the entire length of the sawtooth cutter 2 to the carton blank 1 with the adhesive 6, the opposite end portions 2c of the sawtooth cutter 2 are bonded firmly to the carton blank 1. Consequently, the opposite end portions 2c will not come off or will not be loosened during use, and functions properly for an extended - 12 period of use. Since the resin impregnated into the opposite end portions 2c of the sawtoot-h cutter 2 is melted by heat generated by ultrasonic welding and the density of the opposite end portions 2c is increased by pressure is applied to -thi opposite end portions 2c, the hardness of the opposite end pork-ions 2c is increased and.the cutting ability of the opposite end portions 2c is enhanced. The aluminum foil or the wrapping film can easily be cut because the opposite end portions 2c, on which a maximum -orce acts in the initial stage of operation J].for cutting the aluminum. foil cr- the wrapping film, are very sharp.

The sharnness alE the sawtooth cutter 2 was tested on a tensile tester. in the test, the carton blank crovided with the sawtooth cutter 1 was set on the tens.;'_le taster at =clinations of 45, 45' and 30 to a X, a Y and a Z axis, a -film was pulled at a f-..xed pulling- speed of 500 mm/min, and tble maximum load at the breakage o-E the fil:n (the maximun, load at which the starts b--e-%k-4ng) was measured. Whereas the film engaged with a portion c-10- the sawtooth cutter bonded to the ca--t%on blank on117 with the adhesive broke at a load of 308 g, the film engaged wit-h a 1Dortion of the sawtooth cutter welded by ultrasonic welding (10 mm x 15 mm in area, 20 kHz in ascilla-..cn frequency, 3 kg/cmz in pressure and 0.1 sec in oscillation time) broke at a load of 225 g. The test results proved the high sharpness of the port..;.cns of the sawtcoth cutter bonded by ultrasonic welding. Although thlis enbcd- 4mentL. bonds only the oDccs---e end portions 2c cf, the sawtooth cutter 2 to the cart-on blank 1 by ultrasonic welding after bcnd-4ng the saw-l-- c--h cutter 2 to the ca---L-on blank 1 with the adhesive 6, appropriate small _regions of the saw.och cutter 2 be-,-4een the ceces,;-te end pert.- .cns 2c mavLze bonded to the ca=ton blank 1 by ultrasonic welding when necessaryA-thouch this embodiment employs t.-.,e straight sawtooth cutter 2, -,.-e present invention -4s applicable to a case where an obtusely V- shamed sawt-coth cutter 2A is bonded to the inner surface of a flap section la of a carton blank 1 as shown in Fig. 9. When the sawtooth cutter 2A of such a shape is employed, the opposite end portions 25 enclosed by alternate long and two short dashes lines of the sawtooth cutter 2A may; be bonded to the carton blank 1 by ultrasonic welding after attaching the substantially entire length of the sawtooth cutter 2A to the carton blank 1 with an adhesive.

When the sawtooth cutter 2A is employed, the opposite end portions 25 enclosed by alternate long and two short dashes lines and the V-shaped middle portion 26 enclosed by alternate long and two short dashes lines of the sawtooth cutter 2A may be bonded to the carton blank 1 by ultrasonic welding after attaching the substantially entire length of is the sawtooth cutter 2A to the carton blank 1 with an adhesive. When the sawtooth cutter 2A is thus bonded to the carton blank 1, the opposite end portions 25 and the V-shaped middle portion 26, which are liable to come off, can securely be bonded to the carton blank 1 and are able to function properly for an extended period of use.

Although foregoing embodiment uses ultrasonic welding for bonding the opposite ends 2c of the sawtooth cutter 2, or the opposite ends 25 and the V-shaped middle portion 26 of the sawtooth cutter 2A to the carton blank 1, those portions may be bonded to the carton blank 1 by heat- sealing.

As is apparent from the foregoing description, accordinq to the present invention. at least the opposite end portions of the sawtooth cutter are bonded to the carton blank by ultrasonic welding or heat-sealing after bonding the substantially entire length of the sawtooth cutter to the carton blank with the adhesive. TherelEore, the opposite end portions of the sawtooth cutter which are liable to come off can surely and firmly be bonded to the carton blank and the opposite end portions will not come off during use. Since the area of the opposite end portions to be bonded to the carton blank by ultrasonic - 14 welding or heat-sealing is small, the ultrasonic welding machine or the heat-sealing machine for bonding the opposite end portions to the carton blank may be of a relatively small output capacity and of a simple construction.; and the opposite end portions can securely be bonded to the carton blank. Furthermore, since the opposite end portions of the sawtooth cutter are bonded to the carton blank by ultrasonic welding or heat-sealing, the resin density of the opposite end portions increases because the opposite end portions are heated and pressed. Consequently, the cutting ability of the opposite end portions, on which a maximum force acts when cutting a wrapping film or the like, is enhanced, whereby the wrapping film or the like can easily be cut.

Since the sawtooth cutter is formed from the resinimpregnated paper sheet, the welding property of the resin contained in the sawtooth cutter is available; that is, ultrasonic welding and heat-sealing are effective even if the res in- impregnated paper sheet is not coated with a polyethylene by a secondary process. Accordingly, the sawtooth cutter capable of being bonded to the carton blank by ultrasonic welding or heat- sealing can be manufactured at relatively low manufacturing costs. Since the resinimpregnated paper sheet absorbs moisture scarcely, the sawtooth cutter will not be deteriorated and not come off due to moisture absorption during use.

Claims

1. A sawtooth cutter having at least one sawtooth edge formed fr-oma material produced by coating the surface of a vulcanised fiber with a resin.

2. A sawtooth cutter as claimed in claim 1 wherein the coating resin is selected from ethylene-acrylic-acid copolymers (ionomers), ethylene-propylene copolymers; and vinyl-acetate- polyolefin copolymers.

3. A sawtooth cutter as claimed in Claim 1 or Claim 2 wherein the resin is coated in an amount per unit area of the vulcanised f iber in the range of about 3 to about 6 g/m'.

4. A sawtooth cutter as claimed in any one of Claims 1 to 3 substantially as herein described with reference to the accompanying drawings