JPH0262375B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for manufacturing a laminated structure of vinylidene chloride resin, and more specifically, to a method for effectively preventing discoloration and decomposition of vinylidene chloride resin. However, the present invention relates to a method for manufacturing a laminated structure having excellent strength and thermoformability.

(Prior Art and Technical Problems of the Invention) Vinylidene chloride resins are widely used as sheet forming materials from the viewpoint of high barrier properties and the like.

However, this vinylidene chloride resin is
In order to suppress thermal deterioration and decomposition such as HCl and discoloration, there are strict restrictions regarding temperature and time during extrusion, and the normal residence time in the extruder (several minutes)
Based on this, extrusion must be carried out at a temperature of 190°C or lower.

For example, when extruding at a high temperature of 220℃ or higher, there is a problem that extrusion becomes impossible due to discoloration of the resin or charring due to decomposition.
When extruding at a temperature of 220°C, there is a time limit (1 to 2 minutes) to prevent discoloration and decomposition of the resin, which is undesirable in the manufacturing process. .

Therefore, extrusion of vinylidene chloride resin must be carried out at as low a temperature as possible within the temperature range from the melting point to 190°C.

Next, in addition to restrictions on extrusion temperature and time (residence time), it is also necessary to pay attention to restrictions on extruder tip pressure. In the case of vinylidene chloride resin, the extruder tip pressure should normally be 180 kg/cm ² or less. Tip pressure
This is because when the temperature exceeds 180 Kg/cm ² , the melting point of the vinylidene chloride resin becomes 180° C. or higher, and the difference between the melting point and 190° C. becomes too small, making extrusion practically difficult.

On the other hand, containers formed from multilayer sheets of olefin resins such as propylene resins, polycarbonate resins, or polyester resins, and vinylidene chloride resins can be retort sterilized and have excellent gas barrier properties, so they can be used for food products. It is attracting attention as a container for

For example, from the viewpoint of container strength and thermoformability, the propylene resin used in this case is
Grades with relatively large molecular weights, such as melt flow rate (ASTM D1238−82) of 2d
g/min or less should be used.

By the way, this melt flow rate is 2dg/
When considering productivity, it is extremely difficult to extrude propylene resin for less than 1 minute at a temperature of 220°C or less.

In other words, it is possible to perform extrusion at a temperature lower than 220℃ by lowering the screw rotation speed and lowering the extruder setting temperature, but in this case, the fluctuation in the extrusion amount will be large. The amount of extrusion becomes small, or insufficient kneading occurs.
Otherwise, the pressure loss within the T-die becomes large, resulting in fatal drawbacks such as an increase in pressure at the tip of the extruder for vinylidene chloride resin.

Multilayer sheets are generally produced by laminating the resin extruded from each extruder in a section called a feedblock and spreading it into a sheet with a T-die, or
Alternatively, it may be formed by stacking with a multi-manifold T-die or by any other means.

Therefore, when forming a multilayer sheet of the above-mentioned propylene resin and vinylidene chloride resin, the vinylidene chloride resin comes into contact with the high-temperature propylene resin, so it cannot escape thermal deterioration such as discoloration and decomposition. In such cases, decomposed substances may accumulate in the feedblock or T-die, causing problems such as impossibility of extrusion.

Further, even when an adhesive layer is provided between the vinylidene chloride resin layer and the propylene resin layer, such thermal deterioration cannot be prevented because the adhesive layer itself is very thin.

(Object of the Invention) Therefore, an object of the present invention is to provide a method for manufacturing a vinylidene chloride resin laminate structure in which thermal deterioration of the vinylidene chloride resin is effectively prevented.

Another object of the present invention is to provide a method for producing a vinylidene chloride resin laminate structure that has excellent strength, thermoformability, and gas barrier properties.

Still another object of the present invention is to provide a method for manufacturing a laminated structure of a vinylidene chloride resin and a thermoplastic resin such as a propylene resin having a high extrusion temperature.

According to the present invention, a vinylidene chloride resin (A) containing vinylidene chloride units as a main component and a resin having a melting point of 190°C or higher or a melt apparent viscosity (ηa) of 9000 poise or higher at a temperature of 190°C and a shear rate of 100 sec ^-1 . A method for manufacturing a laminated structure with a thermoplastic resin (B), wherein the melt apparent viscosity (ηa) at a temperature of 190°C and a shear rate of 100 sec ^-1 is formed between the resin (A) and the resin (B).
Less than 9000poise and melt flow rate 2d
Provided is a method for producing a vinylidene chloride-based resin laminate structure, which is characterized in that coextrusion molding is performed with a thermoplastic resin (C) interposed as a heat-blocking layer at a rate of 100 g/min or more.

(Action of the invention) That is, the present invention provides the vinylidene chloride resin (A) layer,
A thermoplastic resin (C) with a melt apparent viscosity of less than 9000 poise at a temperature of 190°C and a shear rate of 100 sec ^-1 can be melt-extruded as a heat shielding layer, or the temperature is 190°C and a shear rate of 190°C and a shear rate of 100sec ^-1
The temperature at which the thermoplastic resin (B) layer with an apparent melt viscosity of 9000 poise or higher is placed is the temperature at which the vinylidene chloride resin (A) and the thermoplastic resin (B) are coextruded. This is based on the regulatory knowledge that it is effectively suppressed.

(Embodiments of the Invention) In FIG. 1 showing a preferred layer structure of a laminated structure according to the method of the present invention, this laminated structure has a vinylidene chloride resin layer 1, a thermoplastic resin layer 2 having a high melt-extrudable temperature. , 2', and temperature 190℃, shear rate
It consists of thermoplastic resin layers 3 and 3' having a melt apparent viscosity (ηa) of less than 9000 poise at 100 sec ^-1 .

That is, the thermoplastic resin layers 3, 3 having low apparent melt viscosity are interposed as heat-blocking layers between the vinylidene chloride resin layer 1 and the thermoplastic resin layers 2, 2' having a high melt extrudable temperature. It is characterized by

Further, the thermoplastic resin layers 3, 3' are laminated on the vinylidene chloride resin layer 1 via adhesive layers 4, 4', if necessary.

When a thermoplastic resin such as a propylene resin having a melt extrusion temperature of 90°C or higher is laminated on the vinylidene chloride resin layer 1 directly or via an adhesive resin, such as in a conventionally known laminated structure, the thermoplastic Since the extrusion temperature of the resin is set at a high temperature of 220° C. or higher, thermal deterioration of the vinylidene chloride resin occurs due to heat conduction from the resin layer, resulting in discoloration, scorching, etc.

On the other hand, according to the present invention, as described above, a thermoplastic resin layer 3 having a low melt apparent viscosity, By interposing 3' as a heat blocking layer, heat conduction from the thermoplastic resin layers 2 and 2' with high resin temperature is blocked during coextrusion molding, effectively preventing thermal deterioration of the vinylidene chloride resin. It is something that will be done.

That is, the thermoplastic resin layer 3 interposed in the middle,
3' has a melt apparent viscosity (ηa) of less than 9000 poise at a temperature of 190°C and a shear rate of 100sec ^-1 ,
Since extrusion is possible in the low resin temperature range of 190°C to 220°C, the resin layers 3 and 3' act as a heat shielding layer, and the vinylidene chloride resin is not directly exposed to temperatures higher than 220°C during coextrusion. As a result, thermal deterioration of the vinylidene chloride resin is effectively prevented.

Vinylidene Chloride Resin Layer As the vinylidene chloride resin used in the present invention, not only a homopolymer of vinylidene chloride but also a copolymer having vinylidene chloride as a main constituent unit can be used.

Comonomers include acrylic or methacrylic monomers; vinyl aromatic monomers such as styrene and vinyltoluene; vinyl esters such as vinyl acetate and vinyl propionate; diolefins such as butadiene and isoprene; others. Methyl vinyl ether, glycidyl allyl ether, vinyl chloride, ethylene trichloride, ethylene tetrachloride, vinyl fluoride,
Vinylidene fluoride, ethylene trifluoride, ethylene tetrafluoride, maleic anhydride, fumaric acid, vinyl succinimide, vinyl pyrrolidone, etc. alone or in combination
Can be used in combination of more than one species.

Suitable examples of acrylic or methacrylic monomers include acrylic acid, acrylonitrile, acrylamide, methyl acrylate, ethyl acrylate, methyl α-chloroacrylate, propyl acrylate, butyl acrylate, hexyl acrylate, and acrylic. Octyl acrylate, cyclohexyl acrylate, glycidyl acrylate, 2-acrylic acid
Hydroxyethyl, acrylic acid monoglyceride,
Phenyl acrylate, methacrylic acid, methacrylonitrile, methacrylamide, methyl methacrylate, amyl methacrylate, glycidyl methacrylate, monoglyceride methacrylate, 2-hydroxypropyl methacrylate, β-methoxyethyl methacrylate, β-amino methacrylate ethyl,
Mention may be made of γ-N,N-diethylaminopropyl methacrylate.

In the present invention, vinylidene chloride/vinyl chloride copolymers and vinylidene chloride/methyl acrylate copolymers are particularly preferably used.

These vinylidene chloride resins have high barrier properties against various gases, but their contact point is generally in the range of 160°C to 175°C, and in order to prevent their thermal deterioration, the extrusion temperature is A temperature of around 175°C is appropriate.

The thickness of the vinylidene chloride-based resin layer 1 may vary depending on the use, etc., but is usually in the range of 5 to 200 μm.

Thermoplastic resin (B) layer The thermoplastic resin (B) used in the present invention with a melting point of 190°C or higher or a melt apparent viscosity of 9000 poise or higher at a temperature of 190°C and a shear rate of 100 sec ^-1 includes propylene resin, Olefinic resins such as 4-methylpentene-1 polymer and high-density polyethylene, polyester resins typified by polyethylene terephthalate, and polycarbonate resins are preferably used.

These thermoplastic resins (B) have gas barrier properties,
It has excellent mechanical properties such as impact resistance and moldability, and is widely used in various fields such as containers.

Examples of the propylene resin include crystalline polypropylene, a blend of crystalline polypropylene and polyethylene, crystalline propylene/ethylene copolymer, crystalline propylene/butene-1 copolymer, crystalline propylene/butene-1/ethylene Copolymers and the like are preferred, and among these, those having a melt flow rate (ASTM D1238-82) of less than 2 dg/min are particularly preferred.

That is, when the melt flow rate of this thermoplastic resin (B) is 2 dg/min or more, the formed laminated structure, for example, when used as a container,
The container strength, such as drop impact strength and low-temperature strength, is unsatisfactory, and furthermore, it is unsuitable for use as a retort container. In other words, in order to suppress thermal shrinkage during retorting, retort containers must be thermoformed at a temperature higher than the melting point of the thermoplastic resin forming the outer layer, but the melt flow rate is 2 dg/min. If it is more than that, the molecular weight is low;
This is because, since the melt tension is low, heating the laminated sheet to a temperature above the melting point causes a disadvantage that the drawdown of the sheet becomes large.

Thermoplastic resin (C) layer (thermal barrier layer) In the present invention, as described above, a thermoplastic resin (C) layer with a temperature of 190° C. is provided between the vinylidene chloride resin layer 1 and the thermoplastic resin layers 2 and 2' as a heat barrier layer. , shear rate
Thermoplastic resin (C) layers 3 and 3' having a melt apparent viscosity (ηa) of less than 9000 poise at 100 sec ^-1 are provided.

If this melt apparent viscosity (ηa) exceeds 9000 poise, the extrusion temperature of the resin must be set at a high temperature of 220°C or higher, so the resin layers 3 and 3' no longer function as a heat-blocking layer. Therefore, the object of the present invention, which is to suppress thermal deterioration of vinylidene chloride resin, cannot be achieved.

The thermoplastic resin (C) forming this heat shielding layer must have an apparent melt viscosity within the above-mentioned range, and must not have an adverse effect on the properties such as gas barrier properties, impact resistance, and moldability of the laminated structure. Any thermoplastic resin can be used as long as it is not specified, but in general, resins of the same type as the thermoplastic resin (C) forming the outer layer or blends thereof are suitable. This is because in such cases, a high interlayer bond is generally formed between the two without providing a special adhesive layer.

Of course, other resins such as polyethylene and ethylene/vinyl alcohol copolymers can also be used.

Further, since the thermoplastic resin (C) is extruded at a temperature lower than 220°C, it is more preferable that the melt flow rate is in the range of 2 dg/min or more.

The thickness of the thermoplastic resin (C) layers 3, 3' is preferably at least 0.1 mm in order to obtain a sufficient heat shielding effect.

Furthermore, the thickness of the above-mentioned thermoplastic resin (B) layers 2, 2' and the thickness of the above-mentioned thermoplastic resin (C) layers 3, 3' are as follows.
Respectively, C/B+C=0.1 to 0.6...(1) Particularly, it is preferable to set it in the range of 0.2 to 0.4.

If the value of C/B+C is larger than the above range, even if it is desirable from the viewpoint of preventing thermal deterioration of the vinyl chloride resin, it tends to be undesirable from the viewpoint of drawdown property, and also within the above range. If it is smaller than , even if it is suitable from the viewpoint of drawdown properties, it tends to be inappropriate from the viewpoint of preventing thermal deterioration of the vinyl chloride resin.

Specifically, both the thermoplastic resin (B) layers 2 and 2' and the thermoplastic resin (C) layers 3 and 3'
It is provided to have a thickness that satisfies the above formula (1) within a range of 1000 μm.

In the embodiment shown in FIG. 1, the thickness of these thermoplastic resin layers 2 and 3 and the vinylidene chloride resin layer 1 are
a thermoplastic resin layer 2' located on the opposite side of the
The thickness of 3' does not necessarily have to be the same,
It may be asymmetrical with respect to the vinylidene chloride resin layer 1.

Further, in the embodiment shown in FIG. 1, the thermoplastic resin layers 2, 2' and 3, 3' are laminated directly, but they may also be laminated via a suitable adhesive layer. A layer made of scraps such as burrs generated when a container or the like is formed from a laminated structure may be interposed between the layers.

The thickness of such a scrap layer is usually 100 to 100 mm.
A range of 2000 μm is preferable.

Adhesive Layer In the present invention, the thermoplastic resin layers 3 and 3' having a low melting apparent viscosity described above may be directly laminated on the vinylidene chloride resin layer 1, but it is possible to obtain strong adhesive strength. Therefore, they may be laminated with an adhesive layer 4 interposed therebetween.

As such an adhesive, one that is conventionally used and known per se can be used for adhesion with vinylidene chloride resin.

For example, when the thermoplastic resin layers 2, 2' and 3, 3' are both made of propylene resin,
Ethylene/vinyl acetate copolymer, a blend of the copolymer and an olefin resin such as polypropylene, a blend of the copolymer and a rubber such as SBR, a blend of the copolymer and a rubber such as SBR, an olefin resin such as polypropylene and a rubber such as SBR Blends with and the like are preferably used.

The thickness of these adhesive layers 4 may vary depending on the type, etc., but is generally in the range of 10 to 200 μm, particularly in the range of 10 to 100 μm.

Manufacture of Laminated Structure According to the present invention, a film or sheet-like laminated structure is obtained by subjecting each resin corresponding to each of the resin layers described above to coextrusion molding which is known per se.

The extrusion temperature of the vinylidene chloride resin is set at a temperature above the melting point of the resin and below 190°C, usually around 175°C.

The extrusion temperature of the resin (B) forming the thermoplastic resin layers 2, 2' is set in the range of 220 to 350°C, particularly 220 to 290°C, and the extrusion temperature of the resin (B) forming the thermoplastic resin layers 3, 3' is set in the range of 220 to 290°C. The extrusion temperature of the multi-viscosity resin (C) is set in the range of 190 to 220°C, particularly 190 to 200°C.

(Effects of the Invention) Thus, according to the manufacturing method of the present invention, when the resin flows merge in the feedblock or multi-manifold T-die, the gap between the high-temperature thermoplastic resin (B) and the vinylidene chloride resin (A) Since the relatively low-temperature thermoplastic resin (C) is present, thermal deterioration of the vinylidene chloride resin is effectively suppressed, and the coextrusion molding operation can be performed smoothly.

The obtained laminated structure has excellent strength, thermoformability, and gas barrier properties. For example, gas barrier properties can be improved by subjecting the sheet to plug-assist molding, drawing, pressure forming, drawing and ironing, etc. A seamless cup-shaped container with excellent mechanical properties such as drop impact strength and drop impact strength can be obtained.

The excellent effects of the present invention will be explained with the following examples.

Example 1 The resin (A) was vinylidene chloride/vinyl chloride copolymer resin (Saran resin manufactured by The Dow Chemical Company, USA) with a melting point of 154°C and a density (20°C) of 1.7 g/cm ³ and a melting point of 158°C. The (B) resin is an ethylene-propylene copolymer with an apparent melt viscosity of 10,500 poise at a temperature of 190°C and a shear rate of 100 sec ^-1 and a melt flow rate (210°C) of 0.6 dg/min, and the melting point is 162°C. temperature 190
The apparent melt viscosity at °C and shear rate of 100 sec ^-1 is
8500poise, melt flow rate (210℃) is 3.5d
g/min polypropylene as the (C) resin, and an ethylene/vinyl acetate copolymer resin (Evaflex P-2850 manufactured by Mitsui-Dupont Chemical Co., Ltd.) with a melt flow rate of 6 dg/min as the adhesive resin. A symmetrical four-type, seven-layer sheet with a total thickness of 0.8 mm having the configuration shown in FIG. 1 was molded using four extruders, a feedblock, a T-die, and a sheet take-up device. The composition ratio of (B) resin, (C) resin, adhesive resin, and vinylidene chloride resin (A) is B/C/adhesive/A = 58/
The screw rotation speed of each extruder was adjusted so that the thickness ratio was 30/5/7 (thickness ratio). Also, the extrusion temperature of each resin (resin temperature at the tip of the extruder) is 242℃ for (B) resin, (C)
The temperature was 194°C for the resin, 185°C for the adhesive resin, and 175°C for the vinylidene chloride resin.

Sheet molding took about 10 hours, but the operation was successful without thermal deterioration of the vinylidene chloride resin in the T-die and feedblock.

Comparative Example 1 In Example 1, the melt flow rate was 3.5d.
g/min without using polypropylene resin (C),
(B) Resin/adhesive/vinylidene chloride resin (A)/adhesive/(B) Resin composition sheet with a total thickness of 0.8 mm (B/adhesive/A = 88/5/7 thickness composition ratio) Molding was carried out in the same manner as in Example 1, using the set temperature (215° C.) of the eed block and T-die. (B) Resin, adhesive resin,
(A) The heating temperature of the resin is 244, (B) the resin is 244, the adhesive resin is
The temperature was 184°C, and the temperature of (A) resin was 174°C, which was almost the same as in Example 1. Approximately 10 to 12 minutes after sheet forming began, smoking occurred from the T-die outlet, and the extrusion rate began to decrease, so the operation was stopped. It was found that the vinylidene chloride resin was affected by the temperature of the (B) resin, causing HCl removal deterioration in the T-die and feedblock.

Comparative Example 2 In Example 1, the composition ratio of B/C/adhesive/A is set to 68/20/5/7 (in Fig. 1, the thicknesses of layers 3 and 3' each correspond to 80 mm). Sheet molding was attempted in the same manner as in Example 1 except for this. 18 to 19 minutes after the start of operation, a pungent odor that was thought to be HCl gas was generated, and the sheet produced had a noticeable browning due to thermal deterioration of the vinylidene chloride resin.

Example 2 The vinylidene chloride resin used in Example 1 was (A)
Made of resin, melting point 154℃, temperature 190℃, shear rate
The (C) resin is an ethylene-propylene random copolymer with an apparent melt viscosity of 7000 poise at 100 sec ^-1 and a melt flow rate (210°C) of 6 dg/min.
The weight ratio of phenol/tetrachloroethane is 50/
Intrinsic viscosity at 30℃ in 50% mixed solvent is 0.1
B/C/A/C/B (B/
An attempt was made to form a sheet with a total thickness of 1 mm having a configuration (C/A = 71/22/7 thickness ratio) using a multi-manifold T-die.

(A) Set the temperature of the extruder and the adapter pipe from the tip of the extruder to the T-die so that the resin extrusion temperature is 175℃, (C) Set the extruder temperature so that the resin extrusion temperature is 192℃. The temperature of the extruder and adapter pipe was set so that the extrusion temperature of (B) resin was 275°C.
Also, the temperature of the multi-manifold T-die was set at 270°C. Sheet molding could be carried out stably without generating any irritating odor due to HCl removal or any noticeable browning of the vinylidene chloride resin.

On the other hand, (C) B/A/B without using resin
(B/A = 93/7 thickness ratio) was attempted to be formed into a sheet, but a smoke phenomenon occurred from the T-die outlet several minutes after the start of extrusion, so sheet forming could not be performed.

Note that there are various methods for measuring the viscosity of a polymeric catalyst.
For example, rheology measurement method (edited by Rheology Committee of the Society of Polymer Science, Kyoritsu Publishing Co., Ltd. (February 20, 1965)
It can be determined using a cone-plate rheometer, rotating cylinder rheometer, rheogoniometer, flow tester, parallel plate plastometer, etc. as described in the Japanese publication).

The apparent melt viscosity (ηa) defined herein is determined by various methods. It means the value of the ratio τ/γ〓 of shear stress (τ) and shear rate (γ〓) when γ〓=100sec ^-1 . When the solution is a Newtonian fluid, the apparent melt viscosity corresponds to the true melt viscosity; in other cases, the apparent melt viscosity takes on different values depending on the shear stress or shear rate. Shear speed speed 100sec ^-1
corresponds to the extrusion shear rate under normal extrusion conditions.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the layer structure of a laminated structure manufactured by the method of the present invention. 1 is a vinylidene chloride resin layer, 2 is a thermoplastic resin layer with a high melt-extrudable temperature, 3 is a thermoplastic resin layer with a low melt apparent viscosity, and 4 is an adhesive layer.

Claims (1)

[Scope of Claims] 1. A vinylidene chloride resin (A) mainly composed of vinylidene chloride units, and a melting point of 190°C or higher, or a melt apparent viscosity (ηa) of 9000 poise or higher at a temperature of 190°C and a shear rate of 100sec ^-1 . A method for producing a laminated structure with a thermoplastic resin (B), wherein the resin (A) and the resin
(B), the melt apparent viscosity (ηa) at a temperature of 190°C and a shear rate of 100sec ^-1 is less than 9000 poise,
A method for producing a vinylidene chloride-based resin laminate structure, characterized in that co-extrusion molding is performed with a thermoplastic resin (C) having a melt flow rate of 2 dg/min or more interposed as a heat-blocking layer. 2. The manufacturing method according to claim 1, wherein the olefin resins (B) and (C) are both propylene resins. 3. The manufacturing method according to claim 1, wherein the thermoplastic resin (B) is a polycarbonate resin. 4. The manufacturing method according to claim 1, wherein the thermoplastic resin (B) is a polyester resin. 5. The method according to claim 1, wherein the vinylidene chloride resin (A) is a vinylidene chloride/vinyl chloride copolymer. 6. The manufacturing method according to claim 1, wherein the vinylidene chloride resin (A) is a vinylidene chloride/methyl acrylate copolymer. 7. The method for manufacturing a laminate structure according to claim 1, wherein the heat-blocking layer made of the thermoplastic resin (C) has a thickness of at least 0.1 mm.