JPS60230827A - Preparation of low viscosity resin film - Google Patents

Abstract

PURPOSE:To prepare a resin film with MI of 10 or more in good yield, by performing multi-layer inflation film formation by using a resin with MI of 10 or more and a resin with MI of 8 or less before mutually separating the formed films. CONSTITUTION:Multi-layer inflation extrusion film formation is performed by using a resin with a melt index (MI) of 10 or more and a resin with MI of 8 or less and the formed films are mutually separated. For example, polyethylene with MI=3 is extruded from one extruder and polyethylene with MI=30 is extruded from the other one and both of them are supplied to an extrusion dual- layer circular die to form polyethylene films wherein the inside is polyethylene with MI=3 and the outside is one with MI=30 while the formed films are blown up to a dual-layer bulb. Thereafter, this bulb is folded by a nip roll and a knife is inserted into the bulb at the folded point to open the same to form two right and left films which are, in turn, peeled off by separate peel-off rolls and wound to obtain the polyethylene film with MI=30.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention has a melt index (hereinafter referred to as MI) of 10.
The present invention relates to a method for producing the above low-viscosity resin film.

[Conventional technology and its problems]

Low-viscosity resin films are used in a wide range of applications including hot melt films, and are exclusively produced by T-die extrusion film forming method. However, film formation by the T-die method has drawbacks such as poor product yield and the need to insert a joint to prevent adhesion, resulting in high production costs.

On the other hand, the inflation method has a better yield than the T-die method and is a cost-effective manufacturing method, but the MI is 1
Even if an attempt is made to form a film using inflation film using a resin of 0 or more, there is a problem in that the melt viscosity is too low and blow-up cannot be performed.

[Structure of the invention]

As a result of intensive study on a method for producing a resin film with an MI of 10 or more in good yield, the present inventors conducted multilayer inflation film formation using a resin that is normally used for inflation film formation as a support. They found that it was sufficient to perform post-separation, and after further study, they completed the present invention.

That is, the present invention is a method for producing a low-viscosity resin film with an MI of 10 or more, which is characterized by forming a multilayer inflation film using a resin with an MI of 10 or more and a resin with an MI of 8 or less, and then separating the films from each other. .

The resin having an MI of 10 or more (hereinafter referred to as A resin) used in the present invention is a thermoplastic resin that is a homo or copolymer of polyolefin, polystyrene, polyamide, polyester, polyvinyl, etc., and even a blend thereof. good.

Among these, those having an IVII of less than 10 can be subjected to known inflation film formation, and in the present invention, low-viscosity resins having an Ml of 10 or more, preferably 20 or more are used. Further, stabilizers, antioxidants, ultraviolet absorbers, colorants, lubricants, etc. can be added to the resin as required. In particular, when separating after film formation, it is preferable to add an anti-blocking agent such as an amide-based, ester-based, alcohol-based, or wax-based agent to suppress adhesion between resin films having different MIs.

On the other hand, resins with an MI of 8 or less (hereinafter referred to as B
The resin (referred to as "resin") is a resin that can be formed into a film by ordinary inflation, and can be selected from the above-mentioned equivalent polymer group, and may also be a blend or one containing the above-mentioned additives. When the MI exceeds 8, the viscosity is too low and blow-up cannot occur, making inflation film formation difficult. Preferably, it has an MI of 5 or less.

In the present invention, resin A and resin B are each melt-extruded, fed to a multilayer inflation die (circular die) and laminated to form a commonly known multilayer inflation film, and then separated from each other to form a resin A film. This is what you get.

For multi-layer circular dies, either the type in which each resin is extruded from a different lip and then laminated (outer block type) or the type in which molten resins are laminated together within the die (inner block type) can be used. In consideration of film formation stability and peelability after film formation, the outer block type is preferable. When resins A and B are molded into a bubble, which side (inner or outer) they are placed on can be appropriately selected depending on the type of resin used, viscosity, film thickness, etc. In particular, when manufacturing a low-viscosity resin film with an MI of 30 or more, placing the resin (A) on the inside and the resin film (B) with an MI of 8 or less on the outside means that the A resins adhere to each other under the pressure of the nip roll. A that has substantially twice the thickness
It is possible to form a three-layer film in which a resin film is laminated with B resin films on both sides, and it is preferable because it does not stick to rolls or the like in a later step.

As the conditions for extrusion forming the A and B resins, known inflation melt extrusion conditions can be adopted, in which the melting point of each resin is higher than the softening melting point and lower than the decomposition temperature. In addition, after film formation A
To separate the resin films from B and B, immediately after passing through nip rolls to form a flat, multilayer film, both ends are cut, and then tensile stress (tension) is applied in different directions to separate them from each other. . It is desirable to incorporate this step into the inflation film forming process, but
It can also be done in a separate process. In order to facilitate the separation (peeling) operation at this time, in order to weld or adhere resin B to resin A and each other (select from among the available materials), or add an anti-blocking agent to resin A and/or B. It is preferable to take a method such as keeping it in place.

According to the method of the present invention, the flat laminated film that has passed through the nip roll has a uniform thickness in the width direction, and if the bubble is stable, it can be cut at the bending point at the extreme end.
There is no substantial loss and a yield of almost 100% can be achieved. In addition, the obtained low viscosity resin film (usually 10 to 5
00 μm thickness) is suitably used as a hot melt film, for example.

In addition, the MI referred to in the present invention is ASTM D-123F! −
52T (load: 2.161cg).

〔Example〕

The present invention will be explained below with reference to Examples.

Example 1 One extruder (65 mmψ) produced MIRASON 12) made of polyethylene (three-layer polychemical @) with MI=3, and the other extruder produced polyethylene (PETROCENE 2 (made by Chubu Polyethylene Co., Ltd.) with MI-30). )02) respectively, and the inner die lip (270wnψ) and the outer die lip (30
A two-layer circular die (150°C) with two die lips of 0 to After blowing up on a certain two-layer valve, fold it with nip rolls, insert a knife at the bending point, open it into two pieces on the left and right, pass through a pair of pinch rolls, and then peel it off with peeling rolls on the sides to make two pieces on each side. It was wound up using a winding machine to produce a polyethylene film (20 μm thick, 1 m width) with MI=30.

The yield at this time is practically 100% excluding the loss at the start.
%Met.

Example 2 Using the inflation molding apparatus used in Example 1, ethylene-vinyl acetate copolymer resin No. 4 (Evaflex manufactured by Mitsui Polychemical Co., Ltd.) was applied to M from the inner die lip, and ethylene bisamide was applied from the outer die lip. 40 low melting point nylon resin (Diamide made by Daicel Chemical @) was extruded into M containing 0.05% by weight at a die temperature of 135°C.
), a low viscosity nylon film (30 μm thick, 1 m width) was produced in the same manner.

The yield at this time was practically 100%, and the obtained nylon resin film could be used satisfactorily as a hot melt film.

Example 3 Using the apparatus of Example 1, MI=5 from the outer die lip
polyethylene (Mirason manufactured by Mitsui Polychemical Co., Ltd.)
and MI=4 ethylene-vinegar and copolymer resin were blended at a ratio of 7=3 (weight ratio), and further ethylene bisamide was added at 0.0.
A resin composition containing 5% by weight was supplied, and a low melting point polyester resin with an MI of 60 (PES manufactured by Toagosei Co., Ltd.) was supplied from the inner die lip, and after extrusion at a die temperature of 130°C, blow-up was performed. When the polyester resin films on the inside bonded together and were pulled out while being pressed together, the film was formed into an integrated film. After cutting at the bending point, the polyethylene resin on both sides was pulled by three peeling rolls and then rolled up by three machines. It was wound up using a machine to obtain a low melting point polyester film (60 μm thick, 1 m width).

The yield at this time was practically 100%, and the obtained polyester film was good as a hot melt film.

Comparative Example 1 Using the apparatus of Example 1, an attempt was made to form a single-layer inflation film at a die temperature of 150°C by supplying M with 30% polyethylene (Petrocene made of middle polyethylene) only to the outer die lip, but the blow-up However, it was not possible to form a film.

Comparative Example 2 Low melting point nylon resin with MI=40, lip width 1500m
Extrude using an extruder with a T-die (150°C) and cool and solidify while inserting a mount (made of low-density polyethylene). Each piece was cut to produce a 1 m wide nylon film (30 μm thick).

The yield at this time was 77% excluding loss at the start.
It was inferior to the production of blown film of the same width.

〔Effect of the invention〕

In the method of the present invention, it is possible to use a low-viscosity resin, which has been difficult with the conventional inflation method, by simply inflating the resin in multiple layers and then peeling it off, and it has great utility value.

patent applicant Mitsui Toatsu Chemical Co., Ltd.

Claims (1)

[Claims] 1) A multilayer inflation extrusion film using a resin with a melt index (MI) of 10 or more and a resin with an MI of 8 or less, and then separated from each other. Method for producing viscous resin film.