JPS589776B2 - Method for stretching polyvinyl butyral laminated glass interlayer film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a ribbon-shaped polyvinyl butyral interlayer film for laminated glass (hereinafter referred to as a laminated glass interlayer film).

) is continuously extended in a curved manner along the longitudinal force direction.

In order to improve the driver's visual condition, an automobile windshield having a colored portion formed on its upper edge as shown in FIG. 1 is widely used.

This colored portion is obtained by applying color to the laminated glass interlayer film itself, and the windshield glass is manufactured by laminating two glass plates together using the laminated glass interlayer film having the colored portion.

On the other hand, since the upper edge of an automobile windshield is curved according to the shape of the car body, it is desirable from an aesthetic or functional point of view to form the colored portion parallel to the curved upper edge of the glass. .

However, such a ribbon-shaped laminated glass interlayer film cut into predetermined dimensions, for example, a ribbon-shaped laminated glass interlayer film with a colored portion 1 formed on one side as shown in Fig. 2, can be used as is. When manufacturing laminated glass by inserting it between two curved glass plates, the width of the colored part differs in the horizontal direction of the windshield, and the width of the central part is smaller than that of both sides, as shown in Figure 3. The upper edge of the glass and the lower edge of the colored band of the laminated glass interlayer are not parallel.

Therefore, when manufacturing a windshield as shown in Figure 1 using this interlayer film, the interlayer film must be heated to stretch the colored portion so that it fits the upper edge of the windshield. .

Conventionally, as a method for stretching such an interlayer film, for example, USP2
After cutting the ribbon-shaped interlayer film to match the size of the windshield as shown in 817117, stretch the laminated glass interlayer film in the direction of the arrow as shown in Figure 4 to align the colored part with the curved upper edge of the windshield. There is a method of winding a ribbon-shaped laminated glass interlayer film around a roll as in USP 2,937,407, and then heating the roll to expand it into a cone shape (see Figure 5), or as described in USP 3,912,440. , the ribbon-shaped laminated glass interlayer film is heated to a temperature at which it can be stretched while being continuously transferred, and then the ribbon-shaped laminated glass interlayer film is continuously stretched between a pair of cone rolls, and then cut to form the desired shape. A method is known to stretch the shape into the shape of .

However, the first method described above had the drawbacks of poor productivity and a high level of skill, since the laminated glass interlayer film cut into predetermined dimensions was stretched one by one.

The second method described above has the disadvantage that the degree of stretching is not constant because the roll is once wound onto a roll and then expanded into a cone shape.

In addition, the third method described above allows continuous stretching of the laminated glass interlayer film and is excellent in productivity, but after stretching the laminated glass interlayer film, stress generated in the laminated glass interlayer film This had the disadvantage that the relaxation of

The first object of the present invention is to provide a method for stretching a laminated glass interlayer film into a curved shape without such drawbacks.

A second object of the present invention is to provide a method for stretching a laminated glass interlayer film, which allows continuous stretching of the laminated glass interlayer film and facilitates stress relaxation treatment after stretching the laminated glass interlayer film. The purpose of

Furthermore, a third object of the present invention is to provide a method for stretching a laminated glass interlayer film, which allows easy modification of the curvature of the elongation of the laminated glass interlayer film, and also allows easy adjustment of production volume.

That is, the present invention was invented as a result of various studies based on the above object, and its gist is that a ribbon-shaped laminated glass interlayer film is heated to a temperature at which it can be stretched while being continuously transferred, and then the laminated glass interlayer film is heated to a temperature at which it can be stretched. The film is wound onto a cone-shaped drum while giving different stretching distributions in the width direction, and the laminated glass interlayer film is stretched along the longitudinal direction.Then, it is placed in a heating chamber, and the stretching causes the formation of particles within the laminated glass interlayer film. The present invention relates to a method for stretching a laminated glass interlayer film, which is characterized by carrying out a relaxation treatment by holding the film for a sufficient period of time to relieve the strain caused by the laminated glass.

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 7 schematically shows the most common stretching device for carrying out the method of the present invention, in which the ribbon-shaped laminated glass interlayer film 2 to be stretched is placed on a film setting table 5 in the form of a film roll 6. The pinch rolls 1 0 , 1 0 are set, guided by the guide rolls 90 to the heating rolls 7 and 8 , and heated continuously to a temperature at which the pinch rolls can be stretched.
The cone has a predetermined taper on the film winding table 4 while being held at different elongations in the width direction! It is wound up on the drum 11.

The heating rolls 7 and 8 are heated to an appropriate temperature by circulating a heating medium, such as steam, supplied from the heating device 3, and transfer the laminated glass interlayer film 2 continuously sent from the film roll 6. Heat inside.

In this case, an arbitrary number of heating rolls can be installed along the transport path of the laminated glass interlayer film 2, but usually a plurality of heating rolls are installed in stages in order to heat the laminated glass interlayer film 2 to a temperature at which it can be quickly expanded. and use it.

The illustrated example is a case in which two heating rolls 7 and 8 are used in combination, and these heating rolls 7 and 8 are heated by, for example, meshing a worm gear of one drive shaft with a gear attached to the shaft of the heating roll. Rotates at a constant speed.

Further, in order to increase the heating efficiency by increasing the contact time of the laminated glass interlayer film 2 with the heating rolls 7, 8 as much as possible, it is desirable that the heating rolls 7, 8 have relatively large diameters.

In the present invention, the surfaces of these heating rolls 7 and 80 are surface-treated as necessary to prevent the laminated glass interlayer film 2 from sticking during heating and to properly maintain its surface properties.

In particular, strong surface treatment is essential when heating a clean interlayer film of laminated glass that does not have an anti-blocking agent on the surface, and when using multiple heating rolls, the rolls located in the high temperature range It becomes necessary.

In this example, only the heating roll 8 in the high temperature range is surface-treated as shown in FIG.

That is, the heating roll 8 has an uneven matte finish on the surface of the roll that comes into contact with the laminated glass interlayer film 2 to prevent adhesion, and the surface is further chrome plated to keep it clean at all times.

Incidentally, for this purpose, the roll surface can be coated with a heat-resistant resin such as a fluororesin.

On the other hand, the cone-shaped drum 11 is installed at the rear of the heating roll 8, and the heated laminated glass interlayer film 2 is transferred to the pinch roll 1.
0 and 10', different stretching distributions are given in the width direction, and the material is rolled up while being stretched.

That is, the cone-shaped drum 11 rotating in the direction of the arrow and the pinch rolls 10, 10 apply tension to the laminated glass interlayer film 2 between the pinch rolls 10, 10' and the cone-shaped drum.

In addition, the cone-shaped drum 11 has a winding diameter of the laminated glass interlayer film 2 that changes continuously along the direction of its rotation axis, and has a cone-shaped winding surface as a whole, so that it is not heated. When the ribbon-shaped laminated glass interlayer film 2 is wound up, the winding speed differs in proportion to the above tension and the winding diameter, so the laminated glass interlayer film that is wound up in the larger diameter part is rolled up in the smaller diameter part. The laminated glass interlayer film 2 is stretched by an amount equal to this winding speed difference than the laminated glass interlayer film 2 wound up, and the laminated glass interlayer film 2 has an elongation distribution proportional to the winding diameter of the cone-shaped drum 11 in its width direction. It is wound up while being received.

For example, when the colored portion 1 of the ribbon-shaped laminated glass interlayer film 20 is curved as shown in FIG.
The laminated glass interlayer film 20 is installed so that the colored part side of the laminated glass interlayer film 20 is wound up on the smaller diameter side, and the laminated glass interlayer film 20 is wound up on the cone-shaped drum 11 while the side without the colored part is expanded more.

In this case, the rotational speed of the cone-shaped drum 11 is set such that the circumferential speed at which the laminated glass interlayer film 20 is wound is always constant.
The rotation speed can be controlled according to changes in the winding diameter.

Further, it is practically preferable that the diameter of the cone-shaped drum 11 is 300 mm or more so that the elongation can be easily performed.

The elongation of the laminated glass interlayer film 2 is automatically obtained with a predetermined distribution in the width direction by the winding operation of the cone-shaped drum 11.

The degree of curvature in the longitudinal direction of the colored portion 1 of the laminated glass interlayer film 2 obtained as a result of such stretching can be determined by adjusting the tension applied to the laminated glass interlayer film during stretching, for example, by adjusting the degree of curvature of the colored portion 1 of the cone-shaped drum 11. The winding diameter in the axial direction can be changed by changing the taper angle of the cone-shaped drum and by changing the arrangement angle of the drum.

That is, the greater the difference in the winding diameter in the axial direction of the cone drum 11, the greater the change in the elongation of the laminated glass interlayer film 2 in the width direction, and the colored portion 1 of the laminated glass interlayer film 2 increases the degree of curvature. Increase.

In the present invention, the arrangement relationship between the central axis of the pinch roll 10 and the central axis of the cone-shaped drum is appropriately selected depending on the curvature to be expanded.

In FIG. 7, 12 is a heating chamber, in which the laminated glass interlayer film wound around a cone-shaped drum and stretched is placed, and the laminated glass interlayer film is heat-treated and the laminated glass interlayer film is stretched. Alleviate the resulting distortion.

The laminated glass interlayer film to which the method of the present invention can be applied has the performance as an interlayer film for laminated glass, and is made of thermoplastic ribbon-shaped plastic.

For example, it can be optimally applied to commonly used polyvinyl butyral membranes.

In the present invention, prior to stretching, the laminated glass interlayer film is heated to a temperature at which it can be stretched, that is, to a temperature at which it exhibits thermoplasticity but does not soften and adhere, and then, after stretching the laminated glass interlayer film, the laminated glass It is characterized by two-step heating, in which the interlayer film is wound around a cone-shaped drum and heated in a heating chamber to relieve the stress generated in the laminated glass interlayer film. 3. Heating temperature for stretching in the first stage The optimum temperature range varies depending on the type of resin in the laminated glass interlayer film, the degree of stretching, etc., but it is a temperature at which the laminated glass interlayer film exhibits plasticity to the extent that it can be stretched, and is suitable for application to stretching rolls or cone-shaped drums. The temperature is preferably as low as possible so that the laminated glass interlayer film does not stick or become sticky.

For example, when the laminated glass interlayer film is a polyvinyl butyral film and the film thickness is about 10 mil to 40 mil, the temperature is preferably in the range of 40°C to 60°C.

Note that the heating method for the laminated glass interlayer film for stretching is not limited to the contact heating method using heating rolls as described above.
Heating methods using electric heaters, heating methods using hot air, radiation heating methods, and other heating methods that do not adversely affect the laminated glass interlayer film can be similarly applied.

In addition, the heating temperature in the heating chamber for strain relaxation in the latter stage is sufficient to relieve the strain generated in the laminated glass interlayer film, but it may cause the laminated glass interlayer film to adhere to the cone-shaped drum. Preferably, the temperature is as low as possible so that the laminated glass interlayer films do not adhere to each other.

For example, when the laminated glass interlayer film is a polyvinyl buteral film and the film thickness is about 10 mil to 40 mil, the optimum temperature range is 60°C to 90°C.

In addition, the strain relaxation treatment is performed by holding the laminated glass interlayer film in a heating chamber at a temperature of 60° C. to 90° C. for a sufficient period of time, for example, about 20 minutes to 3 hours, to relieve the strain generated in the laminated glass interlayer film due to stretching. is preferred.

Example A material with a thickness of 30 mil and a width of 30 mm, with a satin pattern formed on the surface and a colored band sprinkled heavily to prevent adhesion.
nch polyvinyl butyral laminated glass interlayer film (manufactured by Mitsubishi Monsanto Kasei ■, Suflex (product name), XA-
42) was extended using the following four methods.

Regarding this polyvinyl butyral laminated glass interlayer film, the results of measuring each item listed in Table 1 are also shown in Table 1.

(1) Extension method No. 1 (Method of the present invention) During stretching, the polyvinyl butyral laminated glass interlayer film was stretched by the stretching apparatus shown in FIGS. 7 and 8, and the polyvinyl butyral laminated glass interlayer film was passed between heating rolls and heated to 50°C, and It was passed between pinch rolls and rolled up onto a cone-shaped drum while being stretched.

After winding one roll of the polyvinyl butyral laminated glass interlayer film onto a cone-shaped drum, it is placed in a heating chamber at a temperature of 80°C to relieve stress on the interlayer film, and then cut to prepare samples for measurement. It was set to 1.

(2) Extension method No. 2 (Comparative Example) The polyvinyl butyral laminated glass interlayer film was stretched using a stretching device as shown in FIG.

For stretching, the polyvinyl butyral laminated glass interlayer film is placed in a heating furnace and heated to 82°C, then wound around an expanded cone-shaped mandrel, and then this mandrel is expanded.
Further, the intermediate film was placed in a heating chamber at 80° C. to relieve stress generated in the intermediate film, and then cut to obtain sample 2 for measurement.

(3) Extension method No. 3 (Comparative Example) The polyvinyl butyral laminated glass interlayer film was stretched using the stretching apparatus shown in FIGS. 7 and 8.

During stretching, the polyvinyl butyral laminated glass interlayer was passed between heating rolls and heated to 35°C, and then passed between pinch rolls and wound up onto a cone-shaped drum while being stretched.

After winding one roll of polyvinyl butyral laminated glass interlayer film onto a cone-shaped drum, it is placed in a heating chamber at a temperature of 80°C to relieve the stress generated in the interlayer film, and then cut to prepare samples for measurement. It was set as 3.

(4) Extension method No. 4 (Comparative Example) Using the stretching apparatus shown in FIGS. 7 and 8, the polyvinyl butyral laminated glass interlayer film was stretched.

During stretching, the polyvinyl butyral laminated glass interlayer film was passed between heating rolls and heated to 93°C, then stretched between pinch rolls and a cone-shaped drum, and cut without being wound around the cone-shaped drum. And so.

Thus, the present invention heats a laminated glass interlayer film, then stretches it through a cone-shaped drum, winds it up on the cone-shaped drum to maintain the stretching, and then puts it in a heating chamber to prevent the stretching from occurring during stretching. Since this is a two-step heating method that removes distortion, the heating temperature of the laminated glass interlayer film is set at 40°C to 60°C.
℃ compared to the conventional method, and the heating temperature for strain removal can also be lowered to 60 to 90 degrees Celsius.

Further, by setting the heating temperature of the laminated glass interlayer film to 40°C to 60°C, the temperature of the post-heating treatment can be set to 60°C to 90°C, and the post-heating temperature can be set to 60°C.
By heating at ~90℃, the heating temperature can be increased from 40 to 60℃.
It can be kept at a low temperature of ℃.

In addition, extension is performed at 40°C to 60°C, and strain removal is performed at 60°C to 90°C.
There are also the following advantages by performing the process at a low temperature compared to conventional methods.

(i) When stretching a polyvinyl butyral film, the interlayer film slips, but if it is kept at a low temperature, scratches caused by the rolls can be reduced even when it slips.

(11) An anti-adhesive agent, such as a heavy layer, is attached to the surface of the polyvinyl butyral film to prevent adhesion, but this heavy layer may cause scratches when the polyvinyl butyral film is stretched. However, if the stretching and strain relaxation temperatures are low, the occurrence of scratches can be reduced.

(iii) When producing laminated glass, a satin pattern is formed on the surface of the polyvinyl butyral film to facilitate pressure bonding between the glass and the polyvinyl butyral film, but depending on the stretching temperature or strain relaxation, If the temperature is high, the satin pattern will fade, but if the temperature is low, this will not occur.

(IX/) At high temperatures, adhesion occurs between polyvinyl butyral films when wound onto a roll or when a polyvinyl butyral film wound on a roll is subjected to relaxation treatment, but this may occur at low temperatures. do not have.

(■) A low temperature can prevent the polyvinyl butyral film from adhering to the roll during stretching.

Ring) Less heat loss.

Note that, as a specific example of the present invention, the extension of a laminated interlayer film having a colored portion has been described, but the present invention is not limited thereto, and can similarly be applied to a normal laminated glass interlayer film having no colored portion.

According to the present invention, the ribbon-shaped laminated glass interlayer film is heated while being transferred, and the laminated glass interlayer film, which has reached a temperature at which it can be stretched, is stretched while being wound around a cone-shaped drum while applying tension of different distributions. can be performed continuously and uniformly.

Furthermore, since the stretched laminated glass interlayer film is wound around a cone-shaped drum, it can be held for a predetermined period of time, and the stress generated in the laminated glass interlayer film can be sufficiently alleviated.

Furthermore, since the method of the present invention can be carried out in a batch operation by winding it around a cone-shaped drum, it is suitable for small-scale production, and the production amount can be easily adjusted.

Further, even when changing the curvature of stretching, it is only necessary to replace the cone-shaped drum, so it is easy to produce various kinds of stretched laminated glass interlayer films.

Also, since the laminated glass interlayer is stretched according to the curved shape,
The yield of laminated glass interlayer films can be improved.

[Brief explanation of the drawing]

Figure 1 is a front view of a windshield with a colored part on the top;
Figure 2 is an explanatory diagram of the laminated glass interlayer before stretching, Figure 3
The figure is a front view of an example of laminated glass manufactured using a laminated glass interlayer that does not stretch, Figures 4 and 5 are explanatory diagrams showing the conventional stretching method, and Figure 6 is a ribbon-shaped laminated glass intermediate after stretching. FIG. 7 is an explanatory diagram of the heating stretching device according to the present invention, and FIG. 8 is an enlarged perspective view of the main parts thereof. In the figure, 2 is a laminated glass interlayer film, 1 is a colored part, and 7
, 8 are heating rolls, 10, 10' are pinch rolls, 1
1 is a cone-shaped drum, 12 is a heating chamber.

Claims (1)

[Claims] 1. While continuously transporting the ribbon-shaped polyvinyl butyral laminated glass interlayer film, the interlayer film is heated at 40°C to 60°C.
The heated polyvinyl butyral laminated glass interlayer film is wound around a cone-shaped drum with a predetermined taper while imparting different elongation distributions in the width direction. The cone-shaped drum having the polyvinyl petitral laminated glass interlayer film wound thereon is placed in a heating chamber and heated to 60°C to 90°C,
A method for stretching a polyvinyl butyral laminated glass interlayer film, which comprises holding the polyvinyl butyral laminated glass interlayer film at such temperature for a sufficient time to relieve stress generated in the polyvinyl butyral laminated glass interlayer film. 2. The polyvinyl butyral laminated glass according to claim 1, wherein the ribbon-shaped polyvinyl butyral laminated interlayer film has at least one band-shaped colored portion with a predetermined width in the longitudinal direction thereof. How to stretch the interlayer. 3. The ribbon-shaped polyvinyl butyral laminated glass interlayer film is passed through a heating roll at an extension temperature of 40
A method for stretching a polyvinyl butyral laminated glass interlayer film according to claim 1, characterized in that the polyvinyl butyral laminated glass interlayer film is heated to 60°C to 60°C.