JPS6141729B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an apparatus for manufacturing a film-like multilayer synthetic resin body consisting of, for example, three layers. Conventionally, in multilayer synthetic resin bodies, interfaces between layers are often flat. In that case, there will be little problem if resins with good adhesiveness are in contact with each other, but if resins with poor adhesiveness are in contact with each other, the adhesive layer composed of a material with adhesiveness is applied to both resins. Practically acceptable adhesive strength could not be achieved unless an adhesive component was inserted between the resins or mixed into both resins or one of the resins. Sandwiching an adhesive layer may result in expensive components of the adhesive layer, or the presence of the adhesive layer may deteriorate the properties of the entire multilayer body. Also, in some cases, there may be no suitable adhesive material for both resins. Therefore, it would be ideal if a multilayer synthetic resin body with sufficient adhesive strength could be produced without using such adhesive components. Based on this purpose, the inventor of the present invention
In order to obtain a multilayer synthetic resin body that increases the adhesive strength between layers without using any adhesive component, we invented a method of manufacturing a multilayer synthetic resin body having a cross-sectional structure as shown in FIG. Multilayer synthetic resin body 30 whose cross-sectional structure is shown in FIG.
In this case, the resin A in the center and the resin B on the inner and outer sides are integrated into one body. The interface between the resins A and B has irregularities of the same shape at regular pitches P in the extrusion direction MD during molding of the multilayer synthetic resin body 30. This multilayer synthetic resin body 30 includes, for example, second and third
Manufactured using the equipment shown in the figure. In the apparatus shown in FIGS. 2 and 3, several resin supply passages 2, 3, and 3a extending in the axial direction are provided inside a vertical central fixed shaft 1 without penetrating the resin supply passages 2, 3, and 3a. The upper ends of 3 and 3a are connected to resin passages 11, 12, and 12a, respectively, provided inside a rotary die 6 that is rotatably provided on the outer periphery of the central fixed shaft 1 by the operation of a chain wheel 5. Each resin passage 11, 1 inside the rotary die 6 is provided with
2, 12a are opened in the shape of several concentric rings at the rotating plane part of the upper end of the rotary die 6, and each ring-shaped opening 1 of each resin passage 11, 12, 12a is opened.
6, 17, 18, portions 1 having different widths in the radial direction
6a, 17a, 18a are provided periodically in the circumferential direction, and a ring-shaped die lip 13 is provided above these openings 16, 17, 18 and communicates with all the openings 16, 17, 18. 14,1
5 portions are provided in close contact with the upper surface of the rotary die 6. The resins A and B discharged from the openings 16, 17, and 18 enter a resin collection chamber 19 surrounded by fixed dies 14 and 15, pass through the rotating rotary die 6, and are discharged later. The resin is extruded and discharged from the upper die lip 13 as a multilayer synthetic resin body 30 such as an annular film, sheet, or pipe having a cross-sectional shape as shown in FIG. 1
4a is an air blowing hole. However, the peel strength at different interfaces of the multilayer synthetic resin body 30 produced by this apparatus was not sufficient for practical use. As a result of various studies, it was found that the peel strength of a multilayer synthetic resin body manufactured using such an apparatus is greatly influenced by the degree of penetration INT of resins A and B shown in FIG. The degree of biting INT is determined by, for example, the portions 16a having different widths in the radial direction provided periodically in the circumferential direction in the ring-shaped openings 16, 17, 18 at the upper end of the rotary die 6 shown in FIG. It is greatly influenced by the shapes of 17a and 18a and the speed difference (shear force difference) between the wall surface part of resin B and the center part of resin A. In other words, as the speed difference (shear force difference) increases, the degree of intrusion shown in FIG. It was found that INT becomes larger and peel strength improves. The present invention is a multilayer synthetic resin body that increases the adhesive strength between layers without using an adhesive component, for example, as shown in FIG. In manufacturing a multilayer synthetic resin body having a cross-sectional structure with periodic indentations in the right angle direction, it is possible to improve the peel strength between the different resin layers in contact with each other. To this end, in the present invention, in an apparatus for manufacturing a multilayer synthetic resin body using a rotary die and a fixed die, a part of the fixed die that constitutes the inclined inner wall of the resin collecting chamber in front of the die lip is provided with a structure that resists the flow of resin. A resistance generating part is provided that can add resistance. Next, the present invention will be explained with reference to embodiments shown in the drawings. Since the present invention relates to the structure of the resin collecting chamber before the die lip in the apparatus shown in FIGS. 2 and 3, for example, the explanation of the main body parts such as the rotary die 6 and fixed dies 14 and 15 will be limited. Omitted. However, the openings 16 to 18 provided concentrically on a plane, a spherical surface, an inclined surface, or the like intersecting the axis of the rotary die 6 do not necessarily have to be all ring-shaped. As shown in Figure 5, 1
It may also be a hole-like structure in which one or two openings are arranged at a predetermined pitch. However, in that case, the lower portions of the hole-shaped openings located on the same circle must be communicated with each other by ring-shaped resin passages 11, 12, and 12a located on the same circle. Fixed dies 14, 15 used in the present invention
In the 19 resin collecting chambers formed by,
An inner wall was provided with structural features that added resistance to resin flow. The walls of the resin gathering chamber 19, that is, the inclined outer circumferential surface of the inner fixed die 14 and/or the inclined inner circumferential surface of the outer fixed die 15, are coated with, for example, as shown in FIGS. 6 to 16. A groove 20 was provided to serve as a resistance wall. The one shown in FIG. 6 has several grooves 20 of triangular cross section formed on the inner surface of the fixed die 15 straight in the direction of the die lip 13 and gradually becoming shallower.
The one shown in FIG. 7 has several grooves 20 of triangular cross section formed on the outer surface of the fixed die 14 straight in the direction of the die lip 13 and gradually becoming shallower, and the one shown in FIG. Fig. 9 shows a groove 20 with the same depth as shown in Fig. 7, and Fig. 10 shows a groove 20 with a triangular cross section in the circumferential direction. Fig. 11 shows a groove 20 with several grooves 20 in different diagonal directions and crossing each other, Fig. 12 shows a groove 20 with several grooves 20 in the direction of the die lip 13 and a groove 20 with several grooves in the circumferential direction. grooves 20 intersecting each other,
13 shows a groove 20 shown in FIG. 7 with a shorter length, FIG. 14 shows a groove 20 shown in FIG. 7 in which several protrusions 21 having a triangular cross section are provided, 15 and 16 show grooves 20 having a semicircular cross section and a trapezoidal cross section, respectively, in place of the groove 20 having a triangular cross section shown in FIG. Of course, the 14th~
By using the protrusions 21 and grooves 20 as shown in FIG. 16, patterns as shown in FIGS. 8 to 13 can also be created. Further, the resistance generating portions made of the grooves 20, protrusions 21, etc. may be continuous or discontinuous. Grooves 20 provided in the inclined walls of the fixed dies 14-15
The appropriate spacing between the protrusions 21 is 1 to 20 pieces per 3 cm of circumference, preferably 1 to 10 pieces per 1 cm of circumference, and the width of the grooves, etc. is 0.5 to 7 mm, and the depth is 0.3 to 7 mm. . Next, an example of using the device according to the present invention and a comparative example using a conventional device will be shown. In the following usage example, Eval (Kuraray Eval F) was used as resin A and low density polyethylene (UBE polyethylene F022S) was used as resin B, and molding was performed by an inflation method. A cylindrical film was formed with the resin temperature at 220°C, the rotation speed of the rotary die 6 at 40 rpm, the blow ratio at 2.5, and the film winding speed at 5 m/min.
A multilayer film with a total thickness of 100 μm and an EVAL layer of 7 μm was obtained. In addition, the peel strength is 15 mm wider than the molded film.
A strip sample with a length of 10 cm was cut out and peeled to an appropriate length in advance, and the peel strength was measured using a T-peel method using an Instron tensile tester. Usage example 1 The resistance part has the shape shown in Fig. 7, and its groove 20
The interval between the lower ends is 3 pieces per 1 cm, and the dimensions and shape of the lower end of the groove 20 are 2 mm wide and 1.5 mm deep.
It has a triangular shape, and its width and depth become narrower and shallower toward the top, and it is provided only on the sloped surface part leading to the die lip 13 of the inner fixed die 14, and on the outer fixed die 15. A conventional flat surface was used as the inclined surface leading to the die lip portion 13. Usage Example 2 The resistance part has the shape shown in Figures 6 and 7, and the interval between the lower ends of the grooves 20 is 3 pieces per 1 cm, and the dimensions and shape of the lower ends of the grooves 20 are 2 mm in width and 2 mm in depth. Saha
A 1.5mm triangular shape that becomes narrower and shallower in both width and depth toward the top is inserted into the inner and outer fixed dies 1.
4 and 15, which were provided on both inclined surfaces leading to the die lip 13, were used. Comparative Example 1 Both of the inclined surfaces of the inner and outer fixed dies 14 and 15 up to the die lip 13 were conventional flat ones. Table 1 shows the peel strengths of Use Examples 1 and 2 and Comparative Example 1.

[Table] The inner part of Table 1 shows the peel strength between the inner polyethylene and the EVAL layer of the multilayer film, and the outer part shows the peel strength between the outer polyethylene and the EVAL layer. As can be easily understood from Table 1, a resistance generating part that can add resistance to the flow of resin is provided in the resin collecting chamber 19 that communicates from the openings 16 to 18 of the rotary die 6 to the die lip 13. When using this method, the peel strength of the produced film is much better than when using a conventional film that does not have the above-mentioned resistance generating portion. In this way, in the present invention, since the structure as described in the claims is adopted, it is possible to apply more flow resistance to the resin on the surface side than to the resin in the center. It is possible to further increase the degree of penetration into the interface between the two layers, and it is possible to manufacture a multilayer synthetic resin body with a strong peel strength and a reliable capacity.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an example of a multilayer synthetic resin body, FIG. 2 is a longitudinal sectional view showing an example of a conventional device,
FIG. 3 is a perspective view showing an example of the opening of the rotating die;
4 and 5 are plan views showing other examples of the opening of the rotary die, and FIGS. 6 to 16 are vertical sectional views or inclined views showing different embodiments of the fixed die portion of the present invention. 1...Central fixed shaft, 2, 3, 3a...Resin supply path, 6...Rotating die, 11, 12, 12a...Resin passage, 13...Die lip, 14, 15...Fixed die, 16~ 18...Opening, 19...Resin gathering chamber, 20...Groove, 21...Protrusion, 30...Multilayer synthetic resin body.

Claims (1)

[Claims] 1 Several openings, including an opening that can change the width of the discharged resin depending on the position in the circumferential direction, are provided concentrically on the plane that intersects the rotational axis of the rotary die, and all of the openings are placed above these openings. In an apparatus for producing a multilayer synthetic resin body, which is provided with a fixed die forming a ring-shaped die lip and a resin collecting chamber communicating with an opening, the resin collecting chamber communicates with the die lip from the opening to resist the flow of the resin. A manufacturing device for a multilayer synthetic resin body with a resistance generating part that can be added.