JPS6243849B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a T-die for molding synthetic resin films or sheets.

As shown in FIG. 1, the conventional T-die has a plurality of die bolts 3a, 3b, 3c provided at approximately equal intervals in the width direction of the die slit gap 2 relative to the fixed lip 1.
... was pushed and pulled to move the movable lip 4 to adjust the thickness of the die slit gap 2.

However, in the conventional device as described above, when a specific one of the plurality of die bolts is operated to adjust the thickness of the die slit gap, due to the so-called mutual interference effect, it is difficult to control the position of the bolt other than the operated bolt, especially the adjacent one. This will affect the bolt position. For example, as shown in the graph of Figure 2, when observing eight bolts inward from the widthwise end of the die, the vertical axis represents the deformation amount δ of the lip, and the second bolt is pushed in. The lip deformation amount δ due to the second bolt is a curved line, and the lip deformation amount δ due to the first and third bolts on both sides thereof is a curved line and a curved line, respectively.

Such a T-die does not cause much problem in the molding of general non-stretched sheets or films and allows the flow rate distribution to be adjusted, but it is difficult to meet the following special requirements.

(1) Adjustment control of edge profile of raw material for biaxially stretched film, etc.

(2) Measurement of the corresponding die bolt position (operate only the die bolt in a specific part to change the flow rate, therefore the thickness, and measure the corresponding position on the sheet or film with a thickness gauge).

In order to eliminate the drawbacks of the conventional example as described above, a U-shaped or similar groove 6 is provided in the movable lip 5 as shown in FIG. 3, and a thin wall portion is provided between the bolts to reduce mutual interference. There is a weakened T die. When this is done, the deformation characteristics of the lip will be as shown in Figure 4, where the part far from the operated bolt,
(portions 5, 6, 7, and 8 in the figure) are not affected, and the mutual interference effect is considerably weakened.

However, this method is also unfavorable because the lip deformation profile becomes a discontinuous pattern as shown by the dotted line a, as shown in FIG.

It is an object of the present invention to provide a T-die which eliminates the above-mentioned drawbacks of the conventional device and which provides an edge profile adjustment function and a corresponding bolt position measurement function without impairing the continuity of the lip shape. To explain the T-die of the present invention in more detail, a plurality of die bolts provided at approximately equal intervals in the width direction of the die slit gap are pushed and pulled, and a part of the lip at the contact point of the die bolt is formed into a U-shape or this. The above-mentioned U-shaped groove or groove similar to this is used in a T-die for synthetic resin, which is made thinner by providing a groove similar in shape to the die bolt, and deforms the lip and adjusts the die slit gap while reducing the rigidity between the contact points of the die bolt. This is a T-die for synthetic resin, which has two or more grooves and the depth of the groove gradually decreases inward from both ends in the width direction of the die slit gap, and has properties intermediate between the two conventional devices described above. It is something.

Next, one embodiment of the present invention will be described with reference to FIG. 6. Reference numeral 11 denotes a fixed lip, 12 a movable lip, and both lips 11 and 12 form a die slit gap 13. 14 is the die slit gap 13
A plurality of die bolts 14a, 14b, 14c... are provided at approximately equal intervals in the width direction of the die bolt 14.
Push and pull the movable lip 12 to fix the fixed lip 1.
1 to adjust the thickness of the die slit gap 13. Reference numeral 15 denotes a U-shaped or similar groove provided in the movable lip 12, which is designed to weaken the mutual interference effect when pushing and pulling the die bolt 14. The depth L gradually decreases toward the inside, and the deformation characteristics of the lip are as shown in Figure 7, which is between the two conventional devices shown in Figures 2 and 4. The lip deformation profile also becomes like the graph shown by the dotted line b in FIG. 8, and is discontinuous only at both ends in the width direction. However, this discontinuous portion is the portion that is picked up by tenter clips during stretching of the film, etc., and is ultimately trimmed, so it does not cause any problems as a product.

In addition, in the conventional device, when only one die bolt (the second bolt in the embodiment) is pushed in, the position of the corresponding bolt is unclear as shown in FIG. As can be seen, since the location of a particular bolt is clear, the thickness of the sheet or film can be measured and the corresponding bolt can then be manipulated to change the flow of the resin and thus the thickness of the film.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a conventional T-die. Figure 2 is the first
A lip deformation characteristic diagram of the T-die shown in the figure. FIG. 3 is a diagram of another conventional device. FIG. 4 is a lip deformation characteristic diagram of the T-die shown in FIG. 3. FIG. 5 is a diagram showing the edge profile of the T-die shown in FIG. 3. FIG. 6 is a diagram showing one embodiment according to the present invention. FIG. 7 is a diagram showing the lip deformation characteristics of the T-die according to the present invention. FIG. 8 is an edge profile diagram of a T-die according to the present invention.
FIG. 9 is an explanatory diagram of the conventional T-die shown in FIG. 1, showing a lip deformation pattern when a specific die bolt is pressed. FIG. 10 shows a T according to the present invention.
A diagram showing a lip deformation pattern when a specific die bolt of a die is pressed. 11... Fixed lip, 12... Movable lip, 1
3...Die slit gap, 14...Die bolt,
15...U-shaped groove.

Claims (1)

[Claims] 1 Push and pull a plurality of die bolts provided at approximately special intervals in the width direction of the die slit gap, and form a U-shaped or similar groove in a part of the lip at the die bolt contact point to form a thin wall part. However, in a T-die for synthetic resin in which the die slit gap is adjusted by deforming the lip while reducing the rigidity between the contact points, the U-shaped or similar groove is formed by two grooves.
A T-die for synthetic resin, characterized in that the depth of the groove is gradually decreased inward from both ends in the width direction of the die slit gap.