CN111421790A

CN111421790A - Extrusion blow molding die and method for processing blow molding product by using same

Info

Publication number: CN111421790A
Application number: CN202010365098.6A
Authority: CN
Inventors: 陈华卿
Original assignee: Taizhou Xianglong Food Container Technology Co ltd
Current assignee: Taizhou Xianglong Food Container Technology Co ltd
Priority date: 2020-04-30
Filing date: 2020-04-30
Publication date: 2020-07-17

Abstract

The invention provides an extrusion blow molding die and a method for processing a blow molding product by using the same, belonging to the technical field of plastic dies. The method solves the problem that the flash weight is large when the existing extrusion blow molding is used for processing small-capacity containers. The extrusion blow molding mold comprises a mold body with a container mold cavity, wherein the mold body is provided with a raised head and a groove; when the two sets of extrusion blow molding dies are arranged along the axial lead direction of the container die cavity, one end face of one set of extrusion blow molding die can be abutted against the other end face of the other set of extrusion blow molding die, and the raised head of one set of extrusion blow molding die is embedded into the groove of the other set of extrusion blow molding die. The parison breaks between the first mold and the second mold during separation of the first mold from the second mold during the process of processing the blow-molded product using the extrusion blow mold. The weight ratio of the flash in the blow molding part is obviously reduced by utilizing the extrusion blow molding die to produce products, and the flash generation amount is reduced by more than 30%; and the bottom of the container does not need to be processed by flash cutting.

Description

Extrusion blow molding die and method for processing blow molding product by using same

Technical Field

The invention belongs to the technical field of plastic molds, and relates to a blow molding mold, in particular to an extrusion blow molding mold.

The invention belongs to the technical field of plastic processing, relates to a blow molding processing method, and particularly relates to a method for processing a blow molded product by using an extrusion blow molding die.

Background

Extrusion blow molding is a process for manufacturing hollow thermoplastic articles such as bottles, pails, cans, cases and containers for packaging food, beverages, cosmetics, pharmaceuticals and commodities.

The conventional extrusion blow molding process consists essentially of 5 steps: 1. extrusion of plastic parisons, i.e. hollow plastic tubes; 2. closing the split mold on the parison, clamping the mold and cutting off the parison; 3. blowing the parison against the cold wall of the mold cavity, adjusting the opening and maintaining a certain pressure during cooling; 4. opening the mold and discharging the blown part; 5. trimming the flash to obtain a finished product. When small capacity (less than 500 ml) containers are processed by conventional extrusion blow molding processes, the flash is significant in the blow molded parts, typically above 25% and even above 40%.

A method and apparatus for manufacturing containers having an interlayer of EVOH material, such as those used in the manufacture of containers (application No. 200780009337.7), an outer container of PP or PET-G, and an inner bag of three layers, wherein the EVOH, an adhesion promoter layer, Surlyn or L upolen, the market price of EVOH being much higher than that of the flying EVOH layer of PP, PET-G, Surlyn or L upolen, cannot be separated out efficiently, i.e. the EVOH material cannot be recycled separately, so that it is important to reduce the weight ratio of flash in blow-molded parts, such as reducing the consumption of EVOH and reducing the manufacturing cost of containers.

Disclosure of Invention

The invention provides an extrusion blow molding die, and aims to solve the technical problem of reducing the weight ratio of flash in blow molding parts.

The invention provides a method for processing a blow-molded product by using an extrusion blow-molding die, which aims to solve the technical problem of how to improve the processing efficiency of the extrusion blow-molded product.

The technical problem to be solved by the invention can be realized by the following technical scheme: an extrusion blow molding die comprises a die body with a container die cavity, and is characterized in that a raised head is arranged on one end surface of the die body, a groove is arranged on the other end surface of the die body, and the raised head and the groove are arranged along the axial lead of the container die cavity; when the two sets of extrusion blow molding dies are arranged along the axial lead direction of the container die cavity, one end face of one set of extrusion blow molding die can be abutted against the other end face of the other set of extrusion blow molding die, and the raised head of one set of extrusion blow molding die is embedded into the groove of the other set of extrusion blow molding die.

Compared with the prior art, the two sets of extrusion blow molding dies are butted when in use, and the extrusion blow molding die has the following beneficial effects: 1. the space between the two sets of extrusion blow molding dies is eliminated, and flash is prevented from being formed between the two sets of extrusion blow molding dies; 2. the groove is arranged to ensure that the distance between the bottom surface of the groove and the end surface of the container mold cavity is smaller than the distance between the end surface of the container mold cavity and the end surface of the mold body, so that the amount of flash generated between the end surface of the container mold cavity and the end surface of the mold body is reduced; 3. the raised head is embedded into the groove, so that the parison in the groove is fully utilized, the material utilization rate is improved, the amount of flash is reduced, and the butt joint consistency and stability of the two sets of extrusion blow molding dies are improved. The weight ratio of the flash in the blow molding part is obviously reduced by utilizing the extrusion blow molding die to produce products, and the flash generation amount is reduced by more than 30%.

In the extrusion blow molding die, part of the container die cavity is positioned in the raised head, so that the distance between the end surface of the container die cavity and the end surface of the raised head is ensured to be at the minimum, and the increase of the amount of flash generated between the end surface of the container die cavity and the end surface of the raised head is avoided.

In the extrusion blow molding die, the groove is provided with a first abutting surface which is obliquely arranged, and the raised head is provided with a second abutting surface which is obliquely arranged and can be matched with the first abutting surface; therefore, the convex heads can be embedded into the grooves, and the butt joint consistency of the two sets of extrusion blow molding dies is improved.

In the above extrusion blow molding mold, the mold body includes a left mold half and a right mold half, the recess and the projection are both split along a parting plane, one half of the recess and the projection are located on the left mold half, and the other half of the recess and the projection are located on the right mold half.

In the extrusion blow molding mold, the mold body is provided with an auxiliary pressing strip part positioned between the bottom surface of the groove and the end surface of the container mold cavity, the auxiliary pressing strip part is provided with an accommodating groove, and the accommodating groove penetrates through the container mold cavity and the groove; when one end face of one set of extrusion blow molding die abuts against the other end face of the other set of extrusion blow molding die, a clamping joint cavity is formed between the raised head and the wall of the groove. After the left half die and the right half die are closed, the auxiliary pressing strip part closes the tubular parison, the extrusion deformation of the parison can be controlled by controlling the depth of the accommodating groove, and the closing tightness is improved. Most of the material flows into the clamping joint accommodating cavity when the parison is extruded by the convex head and the auxiliary pressing strip part, so that the product forms a clamping joint, and the sealing property of the product is further improved. In the prior art, a clamping joint is formed in one set of extrusion blow molding die, and a clamping joint cavity in the technology needs two sets of extrusion blow molding dies to be formed in a butt joint mode.

The first scheme is as follows: a method for processing blow molding products by using extrusion blow molding dies is characterized in that the method for processing the blow molding products at least adopts two sets of extrusion blow molding dies arranged along the axial lead direction of a container die cavity, the two adjacent sets of extrusion blow molding dies are respectively called as a first die and a second die, and the second die is positioned between the first die and an extrusion device; extruding a hollow plastic parison by using an extruding device and arranging the parison along the axial lead direction of a container mold cavity;

the method for manufacturing the blow-molded product comprises the following sequential steps, wherein in the first step, the left half mould and the right half mould of a first mould are controlled to be closed, compressed air is injected into a parison positioned in the first mould, the parison is blown, and a certain pressure is maintained during cooling; controlling the second mold to be in an opening state, enabling the second mold to be in a leaning state with the first mold, and enabling part of the parison to be located between the left half mold and the right half mold of the second mold;

secondly, controlling the left half die and the right half die of the second die to be closed;

thirdly, injecting compressed air into the parison positioned in the second mold, blowing the parison, and keeping a certain pressure during cooling;

and fourthly, controlling the first mold or the second mold to move along the axial lead direction of the container mold cavity, so that the first mold is separated from the second mold, and the parison is broken between the first mold and the second mold.

Scheme II: a method for processing blow molding products by using extrusion blow molding dies is characterized in that the method for processing the blow molding products at least adopts two sets of extrusion blow molding dies arranged along the axial lead direction of a container die cavity, the two adjacent sets of extrusion blow molding dies are respectively called as a first die and a second die, and the second die is positioned between the first die and an extrusion device; extruding a hollow plastic parison by using an extruding device and arranging the parison along the axial lead direction of a container mold cavity;

the method for manufacturing the blow-molded product comprises the following sequential steps, wherein in the first step, the left half mould and the right half mould of a first mould are controlled to be closed, compressed air is injected into a parison positioned in the first mould, the parison is blown, and a certain pressure is maintained during cooling; controlling the second mold to be in an open state, wherein part of the parison is positioned between the left half mold and the right half mold of the second mold, and only a small gap is left between the second mold and the first mold;

secondly, controlling the left half mold and the right half mold of the second mold to be closed, and then controlling the first mold or the second mold to move along the axial lead direction of the container mold cavity so that the first mold and the second mold are in a mutual leaning state;

Compared with the prior art, after the first die and the second die are separated, the blown part in the first die and the blown part in the second die are thoroughly separated, and the position of the breaking line is matched with the top surface of the raised head of the first die, so that no flash is left in the groove of the second die, namely, the bottom of the container is not required to be trimmed by the flash, and the processing efficiency of extrusion blow molding products is further improved.

In the second scheme, a small gap is reserved between the second die and the first die, the gap is 0.5-2 mm, then the second die is closed, and the second die and the first die are depended on each other, so that the parison between the second die and the first die is extruded into the clamping joint cavity, the total amount of materials of the clamping joint cavity is increased, and the bottom sealing performance of the container is improved.

Drawings

Fig. 1 and 2 are schematic perspective views of extrusion blow molding dies from different viewing angles.

Fig. 3 is a schematic perspective view of a half-mold of an extrusion blow mold.

Fig. 4 is a front view of the extrusion blow mold.

Fig. 5 is a schematic sectional structure view of a-a in fig. 4.

Fig. 6 is a schematic perspective view of two sets of extrusion blow molding dies stacked together.

Fig. 7 is a schematic sectional structure view of two sets of extrusion blow molding dies stacked.

Fig. 8 is a schematic sectional structure view of B-B in fig. 7.

Fig. 9 is an enlarged view of the structure at C in fig. 8.

FIG. 10 is a schematic cross-sectional view of a second step in the process for manufacturing a blow molded product.

Fig. 11 is a schematic cross-sectional view of a third step in the process for manufacturing a blow-molded product, with only the mold in the closed state.

Fig. 12 is a schematic cross-sectional view of a third step in the process for manufacturing a blow-molded product with the parison in an inflated state.

Fig. 13 is a schematic sectional view showing a state in which the fourth step in the process for producing a blow-molded product is performed.

FIG. 14 is a cross-sectional structural view of a blow molded part.

FIG. 15 is a schematic view of a blow-molded part cut into finished products and flash.

In the figure, 1, left mold half; 2. a right half mold; 3. a container forming section; 4. a communicating neck; 5. a blow molding needle relief hole; 6. a raised head; 6a, a first inclined plane; 6b, a second abutting surface; 7. a groove; 7a, a first abutting surface; 8. auxiliary bar pressing parts; 8a, accommodating grooves; 9. clamping the seam cavity; 10. a parison; 11. a first mold; 12. a second mold; 13. an extrusion device; 14. a part; 14a, a plastic bottle; 14a1, bottle; 14a2, pinch seam; 14b, a communication neck.

Detailed Description

The following are specific embodiments of the present invention and are further described with reference to the drawings, but the present invention is not limited to these embodiments.

The first embodiment is as follows: as shown in fig. 1 to 5, an extrusion blow mold includes a mold body having a container cavity and a blow pin escape hole 5; the container cavity comprises a container forming portion 3 and a communicating neck portion 4 communicating the container forming portion 3 with the blow needle relief hole 5. One end face of the die body is provided with a raised head 6, the other end face of the die body is provided with a groove 7, the two end faces are oppositely arranged, and the raised head 6 and the groove 7 are arranged along the axial lead of the die cavity of the container.

The mold body comprises a left half mold 1 and a right half mold 2, and a container half mold cavity and a blow molding needle avoiding half hole are formed in the left half mold 1 and the right half mold 2; when the left half mold 1 and the right half mold 2 are closed, a container half mold cavity on the left half mold 1 and a container half mold cavity on the right half mold 2 form a container mold cavity, and a blow needle avoiding half hole on the left half mold 1 and a blow needle avoiding half hole on the right half mold 2 form a blow needle avoiding half hole. The recesses 7 and the projections 6 are split along the parting plane, half of the recesses 7 and the projections 6 being located on the left half-mould 1 and the other half of the recesses 7 and the projections 6 being located on the right half-mould 2.

The communicating neck 4 in the container cavity extends into a nose 6, the inner side of the nose 6 being inclined. The outer end surface and the parting surface of the raised head 6 on the left half die 1 are in transition by adopting a first inclined surface 6a, and the outer end surface and the parting surface of the raised head 6 on the right half die 2 are in transition by adopting a first inclined surface 6a, so that the distance between the outer side surface and the inner side surface of the raised head 6 is minimum at the parting surface, and the minimum distance is 4mm-7mm, so that the parison 10 is easier to tear at the raised head 6.

An auxiliary pressing strip part 8 is arranged in the die body between the bottom surface of the groove 7 and the end surface of the container die cavity, an accommodating groove 8a is arranged on the parting surface of the auxiliary pressing strip part 8, and the accommodating groove 8a penetrates through the container die cavity and the groove 7; the accommodation groove 8a is provided to make the parison 10 less likely to break at the auxiliary bead portion 8. The extrusion deformation of the parison 10 in the closed state of the left half die 1 and the right half die 2 can be controlled by controlling the depth of the accommodating groove 8a, and the thickness of the auxiliary bead pressing part 8 is controlled to improve the sealing property of the bottom of the container; the thickness of the auxiliary bar pressing part 8 is 4mm-7 mm.

The groove 7 has two obliquely arranged first abutment surfaces 7a, one first abutment surface 7a is located on the left mold half 1, the other first abutment surface 7a is located on the right mold half 2, and the two first abutment surfaces 7a are oppositely arranged. The raised head 6 is provided with a second abutting surface 6b which is obliquely arranged and can be matched with the first abutting surface 7 a; the number of the second abutting surfaces 6b is also two, two second abutting surfaces 6b are arranged oppositely, one second abutting surface 6b is positioned on the left half die 1, and the other second abutting surface 6b is positioned on the right half die 2.

As shown in fig. 6 to 9, when two sets of extrusion blow molding dies are arranged along the axial line direction of the container mold cavity, one end surface of one set of extrusion blow molding die abuts against the other end surface of the other set of extrusion blow molding die, and the convex head 6 of one set of extrusion blow molding die is embedded into the groove 7 of the other set of extrusion blow molding die; a clamping joint volume 9 is formed between the projection 6 and the wall of the recess 7.

The function and advantages of each structure are further illustrated by illustrating the method of processing the blow-molded product, which is a plastic bottle 14a, using an extrusion blow mold, as shown in fig. 10 to 13.

The method for processing the blow-molded product at least adopts two sets of extrusion blow-molding dies, the extrusion blow-molding dies are vertically arranged, namely, parting surfaces are vertically arranged, the raised head 6 is positioned above, and the groove 7 is positioned below. The extrusion blow molding die is arranged on the die carrier, the extrusion blow molding die can move up and down, and the left half die 1 and the right half die 2 of the extrusion blow molding die can be switched between an opening state and a closing state. All the extrusion blow molding dies are arranged along the axial lead direction of the container mold cavity, namely all the extrusion blow molding dies are arranged in series from top to bottom, and all the extrusion blow molding dies are sequentially called as a first die 11 and a second die 12 … … Nth die from bottom to top.

The extrusion head of the extrusion device 13 is located above the extrusion blow mold. A hollow plastic parison 10 is extruded by means of an extrusion device 13, the parison 10 hanging down naturally and the parison 10 being arranged in the direction of the axis of the container cavity. The raised head 6 and the groove 7 are both strip-shaped, the length of the raised head 6 and the length of the groove 7 are controlled to be matched with the diameter of the parison 10, and the bottom sealing performance of the plastic bottle is guaranteed.

The method for manufacturing a blow-molded product comprises the sequential steps of, as shown in fig. 10, controlling the left half 1 and the right half 2 of the first mold 11 to be closed, injecting compressed air into the parison 10 positioned in the first mold 11, inflating the parison 10, and maintaining a certain pressure during cooling; the second mold 12 is controlled to be in an open state, the second mold 12 is in a state of abutting against the first mold 11, and a part of the parison 10 is positioned between the left half mold 1 and the right half mold 2 of the second mold 12.

When the left half die 1 and the right half die 2 of the first die 11 are switched from the open state to the closed state, the parison 10 is extruded and deformed by the raised head 6, and the material flowing through extrusion deformation is located in a space between the two first inclined surfaces 6a, namely the space between the two first inclined surfaces 6a is used for limiting the flowing range of the material during extrusion deformation, so that adverse effects of disordered flowing products of the material are avoided, and the overlapping goodness of fit of the upper and lower extrusion blow molding dies is reduced if the material flows to the overlapping of the two extrusion blow molding dies.

In the second step, as shown in fig. 11, the left mold half 1 and the right mold half 2 of the second mold 12 are controlled to be closed. The parison 10 is extruded by the nose 6 when the left half-mold 1 and the right half-mold 2 of the second mold 12 are switched from the open state to the closed state, the material flowing in the extrusion being located in the space between the two first bevels 6 a. Meanwhile, the auxiliary bead pressing part 8 extrudes and deforms the parison 10, part of the material flows into the clamping seam containing cavity 9, and the clamping seam containing cavity 9 is fully filled with the material by controlling the size of the clamping seam containing cavity 9.

In a third step, as shown in fig. 12, compressed air is injected into the parison 10 located in the second mold 12 to inflate the parison 10, maintaining a certain pressure during cooling.

Fourth, as shown in fig. 13, the first mold 11 or the second mold 12 is controlled to move along the axial line of the container cavity, so that the first mold 11 is separated from the second mold 12, the parison 10 is broken between the first mold 11 and the second mold 12, specifically, at the bottom edge of the pinch-off seam 14a2, and the pinch-off seam 14a2 formed in the pinch-off seam cavity 9 is a part of the part 14 blow-molded by the second mold 12.

In the fifth step, the first mold 11 is opened and the blown part 14 is discharged. As shown in fig. 14, the unit 14 includes a bottle body 14a1 formed in the container forming portion 3, a communication neck 14b formed in the communication neck 4, and a pinch seam 14a2 formed in the pinch seam receiving chamber 9, the communication neck 14b is connected to the mouth of the bottle body 14a1, the pinch seam 14a2 is integrally connected to the bottom of the bottle body 14a1, and the pinch seam 14a2 improves the sealability and strength of the bottom of the plastic bottle 14 a.

And sixthly, as shown in fig. 15, cutting off the communication neck 14b in the part 14 to obtain a finished plastic bottle 14 a. Compared with the prior art, the bottom of the plastic bottle 14a does not need to be subjected to flash cutting processing, and the weight of the part cut above the opening of the plastic bottle 14a is reduced.

Example two: the structure and principle of the present embodiment are substantially the same as those of the first embodiment, and the substantially same parts are not described redundantly, but only different parts are described, and the different parts are: in the first step, the second mold 12 and the first mold 11 are not in a leaning state, but only a small gap of 0.5mm-2mm is left between the second mold 12 and the first mold 11. In the second step, the left half mold 1 and the right half mold 2 of the second mold 12 are controlled to be closed, and then the first mold 11 or the second mold 12 is controlled to move along the axial line direction of the container mold cavity, so that the first mold 11 and the second mold 12 are in a mutually leaning state.

Claims

1. An extrusion blow molding die comprises a die body with a container die cavity, and is characterized in that a raised head (6) is arranged on one end surface of the die body, a groove (7) is arranged on the other end surface of the die body, and the raised head (6) and the groove (7) are arranged along the axial lead of the container die cavity; when the two sets of extrusion blow molding dies are arranged along the axial lead direction of the container die cavity, one end face of one set of extrusion blow molding die can be abutted against the other end face of the other set of extrusion blow molding die, and a raised head (6) of one set of extrusion blow molding die is embedded into a groove (7) of the other set of extrusion blow molding die.

2. Extrusion blow mould according to claim 1, characterised in that the projection (6) and the recess (7) are both strip-shaped.

3. Extrusion blow mould according to claim 1, characterised in that the container mould cavity extends into the nose (6).

4. Extrusion blow moulding tool according to claim 1, characterised in that the recess (7) has a first abutment surface (7 a) arranged obliquely and in that the nose (6) has a second abutment surface (6 b) arranged obliquely and able to coincide with the first abutment surface (7 a).

5. Extrusion blow mould according to claim 1 or 2 or 3 or 4, characterised in that the mould body comprises a left mould half (1) and a right mould half (2), the recesses (7) and the projections (6) each being arranged facing along a parting plane, one half of the recesses (7) and the projections (6) being located on the left mould half (1) and the other half of the recesses (7) and the projections (6) being located on the right mould half (2).

6. The extrusion blow mold according to claim 5, characterized in that the outer end surface of the nose (6) on the left half mold (1) transitions to the parting plane by a first bevel (6 a), and the outer end surface of the nose (6) on the right half mold (2) transitions to the parting plane by a first bevel (6 a).

7. The extrusion blow mold according to claim 1 or 2 or 3 or 4, wherein the mold body has therein an auxiliary bead portion (8) between a bottom surface of the groove (7) and an end surface of the container cavity, the auxiliary bead portion (8) having thereon an accommodation groove (8 a), the accommodation groove (8 a) penetrating through the container cavity and the groove (7); when one end face of one set of extrusion blow molding die is abutted against the other end face of the other set of extrusion blow molding die, a clamping joint containing cavity (9) is formed between the raised head (6) and the wall of the groove (7).

8. A method for processing blow-molded products by using the extrusion blow-molding die of claims 1 to 6, characterized in that the method for processing blow-molded products adopts at least two sets of extrusion blow-molding dies arranged along the axial lead direction of a container cavity, and a hollow plastic parison (10) is extruded by an extruding device (13) and arranged along the axial lead direction of the container cavity; two adjacent sets of extrusion blow molding dies are respectively called a first die (11) and a second die (12), and the second die (12) is positioned between the first die (11) and the extrusion device (13);

the method for manufacturing a blow-molded product comprises the following sequential steps, a first step of controlling the closing of the left half (1) and the right half (2) of a first mold (11), injecting compressed air into a parison (10) located in the first mold (11), inflating the parison (10), and maintaining a certain pressure during cooling; controlling the second mould (12) to be in an opening state, controlling the second mould (12) and the first mould (11) to be in a leaning state, and controlling a part of the parison (10) to be positioned between the left half mould (1) and the right half mould (2) of the second mould (12);

secondly, controlling the left half mould (1) and the right half mould (2) of the second mould (12) to be closed;

a third step of injecting compressed air into the parison (10) located inside the second mold (12), blowing up the parison (10), maintaining a certain pressure during cooling;

fourthly, controlling the first mold (11) or the second mold (12) to move along the axial lead direction of the container mold cavity, so that the first mold (11) is separated from the second mold (12), and the parison (10) is broken between the first mold (11) and the second mold (12);

or the method for manufacturing the blow-molded product comprises the following sequential steps, wherein in the first step, the left half mould (1) and the right half mould (2) of the first mould (11) are controlled to be closed, compressed air is injected into the parison (10) positioned in the first mould (11), the parison (10) is blown, and a certain pressure is kept during cooling; controlling the second mould (12) to be in an open state, wherein a part of the parison (10) is positioned between the left half mould (1) and the right half mould (2) of the second mould (12), and only a small gap is left between the second mould (12) and the first mould (11);

secondly, controlling the left half mold (1) and the right half mold (2) of the second mold (12) to be closed, and then controlling the first mold (11) or the second mold (12) to move along the axial lead direction of the container mold cavity, so that the first mold (11) and the second mold (12) are in a mutual leaning state;

and fourthly, controlling the first mold (11) or the second mold (12) to move along the axial lead direction of the container mold cavity, separating the first mold (11) from the second mold (12), and breaking the parison (10) between the first mold (11) and the second mold (12).

9. The method of claim 8, wherein the mold body has a supplemental bead portion (8) between the bottom surface of the groove (7) and the end surface of the container cavity, and the supplemental bead portion (8) has a receiving groove (8 a) therein, the receiving groove (8 a) extending through the container cavity and the groove (7); when one end face of one set of extrusion blow molding die abuts against the other end face of the other set of extrusion blow molding die, a clamping joint containing cavity (9) is formed between the raised head (6) and the wall of the groove (7); after the parison (10) has been broken between the first mould (11) and the second mould (12), the pinch-seam (14 a 2) formed in the pinch-seam receptacle (9) is part of the blow-moulded part (14) of the second mould (12).

10. A method of processing a blow moulded product using an extrusion blow moulding tool according to claim 8 or 9 characterised in that the gap is 0.5mm-2 mm.