JPS6228728B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an apparatus for manufacturing a multilayer synthetic resin body, and the product molded by the apparatus for manufacturing a multilayer synthetic resin body has a thin cylindrical shape as shown in FIG. FIG. 1 shows a partially enlarged longitudinal section of the thick portion of the thin portion. For example, when manufacturing a multilayer synthetic resin body having a cross-sectional structure in which the interfaces where different resins come into contact are periodically recessed in a direction perpendicular to the surface of the multilayer synthetic resin body, as shown in FIG. The present invention relates to an apparatus for producing a multilayer synthetic resin body that can increase the adhesive strength between layers without using adhesive components, and can improve the peel strength between layers in which different resin layers are in contact. 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 either the resins were sandwiched between the resins or an adhesive component was mixed into both resins or one of the resins. Sandwiching an adhesive layer may require expensive adhesive layer components, or the presence of the adhesive layer may deteriorate the properties of the entire multilayer. Sometimes there are no ingredients. Therefore, it would be ideal if a multilayer synthetic resin body with sufficient adhesive strength could be produced without using such adhesive components. The inventor of the present invention has already developed a multilayer synthetic resin body having a cross-sectional structure as shown in FIG. Invented manufacturing. These multilayer synthetic resin bodies were manufactured using, for example, an apparatus as shown in FIG. However, the conventional device does not have threaded portions 6″, 21″, and 22″. In the device shown in FIGS. The resin supply passages 2, 3, and 3a are provided without penetrating each other, and the upper end of each resin supply passage 2, 3, and 3a is rotatably provided on the outer periphery of the central fixed shaft 1 by the operation of the chain wheel 5. Inside the die 6, one resin passage 11, 12, 12a is provided which is linked to each resin supply passage 2, 3, 3a, and the rotary die 6
Each of the resin passages 11, 12, 12a inside the rotary die 6 is opened in the shape of several concentric rings at the rotating plane at the upper end of the rotary die 6.
In each ring-shaped opening 16, 17, 18 of 2a,
Portions 16a, 17a, 18 having different widths in the radial direction
a are provided periodically in the circumferential direction, and these openings 1
All openings 16, 1 above 6, 17, 18
Fixed dies 14 and 15 having one ring-shaped die lip 13 communicating with dies 7 and 18 are provided in close contact with the upper surface of the rotary die 6. opening 16,
Resins A and B discharged from 17 and 18 enter a resin collection chamber 19 surrounded by fixed dies 14 and 15,
It passes through the rotating rotary die 6 and is pushed out by the resin discharged later, and the upper die lip 13
From there, it is discharged as a multilayer synthetic resin body such as an annular film, sheet, or pipe having a cross-sectional shape as shown in FIG. Here, the reason why the die 6 is a rotary die is because the first
As shown in the figure, resin A in the thin section has a "swallow" shape and is continuously connected in the axial direction, connecting resins B and C on both sides. In the "wing" part that spreads on both sides of the shape and the thin body part, the bonding strength of the three types of resin is different and uneven in the axial direction, so in order to improve this weak point, " This is to make the height uniform by changing the height position of the "swallow" shape in a spiral manner in the circumferential direction as shown in FIG. In addition, this pipe-shaped molded body can be used as a parison,
Multilayer synthetic resin blow molded products can also be made. The cross-sectional structure in the thickness direction of a multilayer synthetic resin body such as a cylindrical film, sheet, pipe, or a blow-molded pipe-shaped product as a parison shown in FIG. Varies depending on shape and molding conditions. The pitch P shown in Fig. 1 becomes smaller as Pd in Fig. 3 becomes smaller, and it becomes smaller as the rotation speed of the rotary die becomes larger. It varies depending on the molding conditions. The thickness d of the molded body increases as the total discharge amount of resins A, B, and C increases, and decreases as the take-up of the molded body and the drawdown blow ratio increase. If the thickness of the narrow end of the resin A in the center is W ₁ and the thickness of the wide end is W ₂ , then the W ₁ /d ratio is
It depends on the ratio of the narrow width a ₁ of the openings 17 and the wide width b ₂ between the openings 17 and 18, and the ratio of the discharge amounts of resin A and resin C to the discharge amounts of resin B. Similarly, the W ₂ /d ratio is
6, the wide width b ₂ between the openings 17 and 18 _, and the ratio of the discharge amount of resin A and resin C to the discharge amount of resin B. W ₁ /W ₂ ratio is the narrow width a ₁ of the opening 16
and the wide width a ₂ of the opening 16. The degree of penetration of resin A INT is the opening 16,1
It depends on the ratio of the wide and narrow width portions of Nos. 7 and 18, and the ratio of the discharge amounts of resin A, resin B, and resin C. The uniqueness of the structure in the thickness direction of this multilayer synthetic resin body develops the adhesive strength between the layers. In the conventional method, the shapes of the openings 16, 17, and 18 are fixed, so resin A, resin B, and resin C
If the discharge rate ratio and molding conditions are the same, the cross-sectional structure of the multilayer synthetic resin body is defined as one. That is, only a certain value of interlayer adhesive strength could be developed. The invention provides a plurality of wall-like adjustable portions 6', 21', 22' forming openings 16, 17, 18.
is provided movably in the axial direction, and the opening 1
By arbitrarily changing the cross-sectional area of the resin channels 6, 17, and 18, it is possible to appropriately select the ratio of discharge amounts of resin A, resin B, and resin C, resulting in optimal multilayer synthesis. The cross-sectional structure of the resin body allows the adhesive strength between layers to be greatly increased. The adhesive strength between the layers of the multilayer synthetic resin body produced with this apparatus depends on the cross-sectional structure of the multilayer synthetic resin body shown in FIG. That is, if the molding conditions are the same, the unevenness of the cross section, the difference between W ₁ and W ₂ , and the degree of intrusion INT are the same as the cross-sectional area of the resin flow path of each ring-shaped opening at the upper end of the rotary die 6. A, B, C
depends on the ratio of discharge amount. For example, if the gap between the openings 16 is constant and the discharge ratios A/B and A/C are small, the portions 16 having different widths in the radial direction provided periodically in the circumferential direction in the openings
d is not filled with the resin A, and the difference in unevenness of the cross section in FIG. 1, the difference between W ₂ and W ₁ , and the degree of penetration INT are reduced, and it is considered that no improvement in the adhesion between the layers can be expected. The gaps between the openings 16, 17, and 18 are also determined in order to obtain optimal interlayer adhesion for a certain discharge ratio A/B/C. By freely adjusting the gap between the movable parts 6', 21', and 22' used in the present invention, it is possible to improve the adhesion between the layers.As a measure for this purpose, the movable parts 6',
The parts 21', 22' adjacent to the resin collection chamber 19 are inclined, and the movable parts 6', 21',
22' can be moved up and down, and the openings 16, 1
It has a structural feature that allows the gaps 7 and 18 to be freely adjusted. For example, to improve the adhesion between the inner layer and middle layer, and the middle layer and outer layer of a three-layer synthetic resin body,
Discharge amount ratio A/B/C and openings 16, 17, 18
The relationship between the flow path cross-sectional areas of openings 16, 17, 18 is
A cross-sectional area 16a in contact with the resin collection chamber 19,
Cross-sectional area ratio of 17b and 18c 16a/17b/1
8c and the ratio A/B/C of the discharge amount of resin are preferably made equal. Therefore, the portions 16 with different widths
d, 17d, 18d are constant and the openings 16, 17,
By changing the gap 18, the cross-sectional area 16
a, 17b, 18c to adjust the discharge amount ratio A/
Cross-sectional area ratio 16a/17 to be equal to B/C
Adjust b/18c. In addition, by weakening either the adhesiveness between the inner layer and the middle layer of the three-layer synthetic resin body or the adhesiveness between the middle layer and the outer layer, the molding of the three-layer synthetic resin body allows for easy peeling of just one layer. This can be easily achieved by adjusting the cross-sectional area ratio 17b/16a/18c according to the ratio A/B/C. Next, the present invention will be explained with reference to embodiments shown in the drawings. 4 and 5 show the opening 1 of the rotary die 6.
This shows different embodiments only around parts 6, 17, and 18, and the other parts are the same as those shown in FIGS. 1 and 2, so their explanation will be omitted. In addition, in FIGS. 4 and 5, the same parts as in FIGS. 2 and 3 are indicated by the same reference numerals, and the explanation thereof will be omitted. In FIG. 4, in order to adjust the shape of the openings 16, 17, 18 in the radial direction, the openings 16, 1
wall-like adjustable movable parts 6', 2 forming 7, 18;
1', 22' are provided so as to be movable in the axial direction, but in order to move the adjustable movable parts 6', 21', 22' in the axial direction, as shown in FIG.
This can be done by making the portions 1'' and 22'' thread-like and turning the adjustable movable portions 6', 21' and 22'. Also, as shown in Figure 4, 6'', 21'', 2
It is also possible to fit the 2" portions together, move them to the optimal position, and then fasten them with pins or screws. Furthermore, as shown in Figure 5, leave a large amount of space for the pins and screws in advance. It is also possible to set it in a suitable position. Next, we will show examples of how to use the device and comparative examples. In the usage examples described below, resin A is EVAL (Kuraray Eval F), resin B is resin B, and resin C is Using low density polyethylene (UBE polyethylene F022S),
The resin temperature was 220° C. and the rotation speed of the rotary die 6 was 40 rpm to form a pipe-shaped molded product, which was used as a parison to mold a blow bottle. The total thickness at the side of the molded product is 0.6 mm. Note that the adhesion strength between layers is determined from the side of the molded product to the width.
A strip-shaped sample piece of 15 mm and 10 cm in length was cut out, peeled in advance to an appropriate length, and measured as peel strength using a T-peel method using an Instron type tensile tester. Usage example 1 Adjustable movable parts 6', 21', 22' shown in Fig. 3
The discharge ratio A/B/C of resin A, resin B, and resin C is 1/1/1, and the cross-sectional area is 16.
Cross-sectional area ratio of a, 17b, 18c 16a/17
Molding was performed using b/18c as 1/1/1. Usage example 2 Adjustable movable parts 6', 21', 22' shown in Fig. 3
The discharge ratio A/B/C of resin A, resin B, and resin C is 20/1/20, and the cross-sectional area is 16a,
Cross-sectional area ratio of 17b and 18c 16a/17b/1
Molding was carried out using 8c as 20/1/20. Usage example 3 Adjustable movable parts 6', 21', 22' shown in Figure 3
The discharge ratio A/B/C of resin A, resin B, and resin C is 10:10:1, and the cross-sectional area is 16a,
Molding was performed with the cross-sectional area ratio of 17b and 18c being 1/1/1. Comparative example Discharge ratio A/B/C of resin A, resin B, and resin C
20/1/20, cross-sectional area 16a, 17b, 18
The cross-sectional area ratio 16a/17b/18c of c is 1/
Molding was performed as 1/1. Table 1 shows the peel strengths of Usage Examples 1, 2, and 3 and Comparative Examples.

[Table] From this table, resin discharge ratio and opening 16,1
It can be seen that the peel strength is greater when the cross-sectional area ratios of Nos. 7 and 18 are the same, and if possible, it is better to set the discharge ratio of each resin and each cross-sectional area ratio to 1:1:1. In this way, the present invention has a structure in which the cross-sectional area of the resin flow path at the opening of the rotary die part can be arbitrarily adjusted, so that the cross-sectional area ratio of these openings can be adjusted to an optimum value according to the resin discharge ratio. A multilayer synthetic resin body having good adhesive strength can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a partially enlarged vertical cross-sectional view showing an example of a multilayer synthetic resin body manufactured by the apparatus of the present invention, FIG. 2 is a vertical cross-sectional view showing an example of the present invention, and FIGS. 3 and 4 are A perspective view (including a sectional view) and a longitudinal sectional view showing the opening in Fig. 2, respectively, Fig. 5 a longitudinal sectional view showing another example of the portion corresponding to Fig. 4, and Fig. 6 a multilayer composite. It is a perspective view of a resin body. 1... Central fixed shaft, 2, 3, 3a... Resin supply path, 6... Rotating die, 6', 21', 22'... Adjustable movable part, 11, 12, 12a... Resin passage,
13...die lip, 14,15...fixed die,
16, 17, 18...opening, 19...resin collection chamber.

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 link-like die lip and a resin collection chamber communicating with an opening, a plurality of wall-shaped adjustable portions forming the opening are axially moved. 1. An apparatus for manufacturing a multilayer synthetic resin body, characterized in that the apparatus is movably provided and has a structure in which the cross-sectional area of the resin flow path of the opening can be arbitrarily adjusted.