JPS63120632A - Porous biaxially stretched film manufacturing equipment - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for producing a porous biaxially stretched film. Specifically, the present invention relates to an apparatus for stably producing a porous biaxially stretched film made of a thermoplastic synthetic resin containing an inorganic filler by tubular biaxial stretching.

[Conventional technology and its problems]

As an apparatus for producing a biaxially stretched film, there are a tenter method biaxial stretching apparatus, a tubular method biaxial stretching apparatus, and the like.

The tenter method biaxial stretching equipment uses T-die, calender roll,
A device that biaxially stretches a film or sheet formed by inflation molding, etc. by holding it in the width direction with tenter clips and stretching it in the width direction while stretching it in the vertical direction.Tubular biaxial stretching equipment is used for inflation molding, etc. This device blows air into the obtained cylindrical film to expand it, stretch it in the transverse direction, and also stretch it in the lengthwise direction to form a biaxially stretched film.

Porous biaxially stretched films are often produced by stretching a film made by blending a large amount of inorganic filler with a synthetic resin as a raw material, thereby creating fine tears at the interface between the filler and the synthetic resin. It is being

When such a porous biaxially stretched film is manufactured using a tubular biaxially stretched device,
As the biaxial stretching progresses, the air permeability of the film increases, so the expansion air sealed inside the cylindrical film passes through the film and leaks, causing the diameter of the bubble to shrink over time, resulting in the desired stretching. There is a problem that magnification cannot be obtained.

For this reason, inflation air is replenished at a constant flow rate into the bubble formed by the cylindrical film, but it is difficult to adjust the balance between the amount of air leaking from the bubble and the amount of air being replenished. It was difficult to obtain a uniform film.

[Purpose of the invention]

The present invention produces a film with uniform porosity, orientation, etc. by controlling the balance between the air leaking from the porous film and the replenishing air during tubular stretching of the porous film as described above. The purpose is to provide a device that can

[Structure of the invention]

The object of the invention was achieved by regulating the amount of air supplied into the tube (bubble) in a special way.

That is, the gist of the present invention is to biaxially stretch a cylindrical body made of a thermoplastic synthetic resin containing an inorganic filler in the longitudinal and transverse directions using a tubular biaxial stretching device to obtain porous biaxial stretching. An apparatus for manufacturing film, which includes a means for measuring the tube diameter, a means for storing the set tube diameter and calculating the difference between the measured tube diameter and the set tube diameter, a means for measuring the pressure inside the tube, and a set tube inside pressure. means to calculate the difference between the pressure inside the measuring tube and the pressure inside the measuring tube.

Means for adjusting the flow rate of air supplied into the tube according to the calculation result of the pressure difference, and converting the calculation result of the tube diameter difference into a predetermined tube internal pressure value.

and a set tube pressure changing means for inputting the obtained tube pressure value as a set tube pressure value, for calculating the difference in tube diameter.

An apparatus for producing a porous biaxially stretched film, characterized in that the tube diameter is measured multiple times within a predetermined period of time, and the difference between the average value of the plurality of measured values and a set tube diameter is used as the difference in tube diameter. .

An example of the apparatus of the present invention will be explained using the drawings.

FIG. 1 is an explanatory diagram showing an example of the apparatus of the present invention.

In the figure, l is a cylindrical film, U is a feeding nip roll, 3 is a take-up nip roll, Hiro is a heating air ring, 5 is a cooling air ring, 6 is a preheating cylinder, 7 is a partition plate 1g is an air blowing pipe, 9 is a Biaxially oriented tubular film, IQ, IQ'
is a guide roll, ll is a slitting device, lyu, l2' is a biaxial W-stretched film, 13.13' is a winding section, lda is a blown air-conditioning pulp, 15 is a shielding plate, tts, i6' are tubes A diameter measuring device, and a pressure measuring device.

Ig is a calculation device, 19 is a tube pressure setting device,
indicate the pulp drive device, respectively.

The explanation will be made according to the apparatus shown in FIG.

The cylindrical film l to be biaxially stretched usually contains 2 to 100 parts by weight of an inorganic filler per ioo parts by weight of thermoplastic synthetic resin. -1I0
Approximately 0 parts by weight, preferably a cylindrical film l, is sent to an infeed nip roll roller and heated by heated air sent from a heating air ring. A preheating cylinder 6 and a partition plate provided in front of the heating air ring retain heated air from the heating air ring around the cylindrical film l in order to efficiently heat the cylindrical film l. play a role.

A cylindrical film l heated to a predetermined temperature by heated air from a heating air ring is expanded by air blown from an air blowing pipe g to form a biaxially stretched film. The stretching ratio in the longitudinal direction is determined by the difference in speed between the feed nip roll and the take-off nip roll 3, and the stretching ratio in the lateral direction is determined by the biaxially stretched tubular film 9 expanded by air from the air blowing pipe g. It is determined by the ratio of the diameter of the cylindrical film 1 and the diameter of the cylindrical film l which is the original film.

A cooling air ring 5 is provided to quickly cool the expanded film. Heating air ring
The purpose of the shielding plate 15 provided between the cooling air ring and the cooling air ring is to prevent heating air and cooling air from mixing.

The guide roll IO1/0' is for properly feeding the biaxially stretched tubular film 9 into the take-up nip roll 3, and the slitting device ii cuts the obtained biaxially stretched tubular film 9 and slits it into two parts. Biaxially stretched film 12
)/2' to the winding sections iJ and i3'.

In the present invention, since the inorganic filler is usually blended in about 5 to 100 parts by weight in the supplied cylindrical film, when biaxial stretching is performed, the inorganic filler is mixed with the synthetic resin constituting the film. The interface of the inorganic filler ruptures, resulting in a porous film. For this reason, the air inside the tubular film expanded through the micropores of the produced film leaks, and if air is not constantly replenished into the tubular film 9, the diameter of the tubular film 9 will shrink and the desired diameter will not be achieved. An axially stretched film will not be obtained.

The apparatus of the present invention is capable of producing a uniform film by replenishing this air in a specific manner.

That is, a tube diameter measuring device/is, Its' is provided to measure variations in the tube diameter.

Tube diameter measuring device/6. For // and ', a phototube type device or the like, which is normally used in this type of device, is used. This tube diameter measurement is performed multiple times within a predetermined time,
The average value is calculated by the calculation device ig, and further compared with a desired tube diameter set in the calculation device to determine the difference.

The above-mentioned predetermined time is usually about S to 300 seconds, and the number of measurements is usually gJ 000 times.

That is, the tube diameter is measured within 5 to 5 seconds, with S to SOO seconds as one unit.

The measured value of the tube diameter is obtained, averaged, and the difference from the set tube diameter is determined.

Therefore, the fluctuation value of the tube diameter that is outputted to the outside from the arithmetic unit ttr is seven times in the above-mentioned 5 to 300 seconds.

In this way, by understanding the fluctuations in tube diameter as an average value over a certain period of time, it is possible to control the tube diameter relatively gently. , the phenomenon of repeated contractions) is prevented.

The film targeted by the present invention differs from ordinary films in that it contains a relatively large amount of inorganic filler and becomes breathable when stretched, so the air inside the expanded tube is always It leaks from the film surface, and variations in the diameter of the tube appear due to slight differences in the air permeability of the film or subtle fluctuations in the amount of extrusion. For this reason, 1. For example, if a control method is adopted in which the film diameter is constantly measured analogously, and when a fluctuation occurs, the blowing air regulating pulp l is immediately opened and closed to change the amount of air from the air blowing pipe g. On the contrary, the tubular film 9 causes a breathing phenomenon.

The present invention involves taking an average value of diameter changes over a certain period of time;
In other words, this breathing phenomenon can be prevented by grasping the tendency of diameter fluctuations.

The difference between the average value of the tube diameters determined as described above and the set tube diameter is input to the calculation device ig and converted into a predetermined tube internal pressure value.

The obtained tube internal pressure value is sent to the tube internal pressure setting device, and the pressure value set here is changed. On the other hand, the pressure inside the tube is measured by a pressure measuring device/? The measurement result is measured by the tube pressure setting device l? If there is a difference between the set value and the actual tube pressure value, the tube pressure setting device iq will issue an OK signal to the pulp drive device, and the pulp /4 will be opened and closed. becomes.

In this way, the tube internal pressure is controlled to be equal to the set value. By repeating this operation, the film is continuously produced.

The apparatus of the present invention operates in this manner, and a uniform biaxially stretched film is produced.

〔Effect of the invention〕

According to the apparatus of the present invention, it is possible to obtain a porous biaxially stretched film by the tubular stretching method with high efficiency and as a uniform film, which is very excellent in practical use.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of the apparatus of the present invention. In the figure, l is a cylindrical film, 2 is a feeding nip roll, 3 is a take-up nip roll, and g is an air blowing pipe. 9 is a biaxially stretched tubular film, /4' is blown air control pulp, /A, /A' are tube diameter measurement values, 1 is a pressure measuring device, ig is a calculation device, 19 is a tube internal pressure setting device , -〇 indicate the pulp drive device, respectively.

Claims (3)

[Claims] (1) A device for manufacturing a porous biaxially stretched film by biaxially stretching a cylindrical body made of a thermoplastic synthetic resin containing an inorganic filler in the vertical and horizontal directions using a tubular biaxial stretching device. means for measuring the tube diameter, means for storing the set tube diameter and calculating the difference between the measured tube diameter and the set tube diameter, and means for measuring the pressure inside the tube;
means for calculating the difference between the set tube internal pressure and the measured tube internal pressure; means for adjusting the flow rate of air supplied into the tube according to the pressure difference calculation result; and a set tube internal pressure changing means for converting the obtained tube internal pressure value into the set tube internal pressure value, and measuring the tube diameter multiple times within a predetermined time when calculating the difference in tube diameter. A porous biaxially stretched film manufacturing apparatus characterized in that the difference between the average value of the plurality of measured values and a set tube diameter is used as the difference in tube diameter. (2) The device according to claim 1, wherein the predetermined time is 5 to 300 seconds. (3) The device according to claim 1 or 2, characterized in that the tube diameter is measured 5 to 3000 times within a predetermined period of time.