JP4076457B2 - Method for producing styrene-based laminate - Google Patents

Description

【００１８】
【実施例１】
樹脂Ａを押出機Ａにて樹脂温度２３０℃、アダプター温度２３０℃で、樹脂Ｂを押出機Ｂにて樹脂温度２１５℃、アダプター温度２１５℃で押出し、２５０℃に設定したフィードブロック、コートハンガーダイを介して共押出した。このシートを連続的に縦延伸機にて１１５℃で流れ方向に２．２倍、ついで横延伸機にて１２５℃で幅方向に２．２倍に延伸し厚さ約２５０umの樹脂Ｂ／樹脂Ａ／樹脂Ｂの２種３層延伸シートを得た。この時の層比は約１／９／１である。
得られた延伸シートを上記４の方法でヘーズおよび全光線透過率を測定した。また目視で観察したところ、メルトフラクチャーのない良好な外観を呈するものであった。その結果を表２に示した。ヘーズが１．５％以下、全光線透過率９０％以上の良好な透明性を保有しているのがわかる。
【００１９】
【実施例２〜５】
及び
【比較例１〜４】
使用樹脂、アダプター温度、ダイス温度のうちの一部を変えた他は、実施例１と同様に実施した。以上の結果を表２にまとめて示した。なお表２における目視評価の○はメルトフラクチャーなし、×はメルトフラクチャーありである。各実施例および比較例でのＭＦＲの各値の差、及び各層に使用される樹脂におけるアダプター温度での動的粘弾性測定の貯蔵弾性率とダイス温度での貯蔵弾性率の差も表２に示した。
【００２０】
【表２】

【００２１】
【発明の効果】
本発明は共押出法において樹脂同士の界面に流れの乱れが生じず外観や透明性の優れたスチレン系積層体を容易に得るための製造方法および積層体を提供するものであり、得られた成形品は食品、薬剤、文具、日用品の包装用容器及びフィルムや産業用の各種容器及びフィルムなどの用途に好適に用いられるものである。[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a method for producing a styrene-based laminate and a laminate, and more specifically, a method for producing a styrene-based laminate useful as a packaging container and film for foods, drugs, stationery, daily necessities, and various industrial containers and films. And a laminate thereof.
[0002]
[Prior art]
Sheets and stretched films of styrenic polymers or polymer compositions containing this polymer are widely used for various containers and packaging because of their transparency and relatively low cost. Multi-layering is generally performed as a method for imparting functions such as heat resistance and chemical resistance. Multi-layered laminates are used for containers for foods, drugs, stationery, daily necessities and films, and for industrial use. Are widely used as various containers and films.
[0003]
As a technique for multilayering by coextrusion, a method using a multi-layer flat die such as a multi-manifold die or a feed block die (hereinafter abbreviated as FB die), a multi-layer circular die such as a distribution channel built-in die or a modular die is used. There is a method to use (see, for example, Non-Patent Document 1).
In particular, the method using the FB die is easy to cope with the increase in the number of layers as compared with other methods, the formation of an ultrathin layer is relatively easy, a wide sheet is easy to take, and the resin is not easily deteriorated by heat. It is often used for reasons such as easy maintenance such as disassembly and cleaning, and overall low production costs (for example, see Non-Patent Document 2).
[0004]
[Non-Patent Document 1]
Plastic Swage, Vol.46, No.8, p.78-87, 2000 [Non-Patent Document 2]
Molding, Vol. 12, No. 2, p95, 2000 [0005]
However, when coextrusion is performed for multilayering, flow disturbance may occur at the interface between the resins depending on the viscosity and molding conditions of each resin, not only the appearance and transparency are impaired, but also stretching in the subsequent process. In some cases, a failure such as breakage may occur.
This phenomenon in which flow disturbance occurs at the interface between the resins is particularly noticeable in the method using the FB die.
This is because when molten resin flows in the order of multiple extruders-multiple adapters-FB die, different resins are flowing from the extruder to the adapter, and the temperature can be set for each resin in each layer. This is because, when joining and widening, since the temperature cannot be set for each resin in each layer already after joining, the flow between the layers is disturbed.
[0006]
[Problems to be solved by the invention]
The present invention has been made in view of such circumstances, and even in a coextrusion method using an FB die, turbulence of the flow does not occur at the interface between the resins, and the styrenic laminate excellent in appearance and transparency. An object of the present invention is to provide a production method and a laminate for easily obtaining the above.
[0007]
[Means for Solving the Problems]
That is, the present invention provides a multilayer coextrusion method in which a styrene-based polymer or a polymer composition containing this polymer is melted and extruded from a plurality of extruders through a die via an adapter to obtain a laminate. In each of the values of the melt flow rate (hereinafter abbreviated as MFR) measured at a resin temperature of 200 ° C. and a load of 5 kg of a styrenic polymer used for adjacent layers or a polymer composition containing this polymer. The adapter temperature is such that the difference is 4 g / 10 min or less and the difference between the storage elastic modulus of the dynamic viscoelasticity measurement at the adapter temperature and the storage elastic modulus at the die temperature in the resin used for each layer is 1500 Pa or less. And a method of manufacturing a styrene-based laminate, and a laminate thereof, wherein a laminate is obtained by setting a die temperature.
[0008]
The present invention is described in detail below.
First, in the present invention, the difference in each value of MFR measured at a resin temperature of 200 ° C. and a load of 5 kg of the styrene polymer used for the adjacent layers or the polymer composition containing this polymer is 4 g / 10. Must be less than or equal to minutes, more preferably less than or equal to 3 g / 10 minutes. The MFR here is a value measured in advance by the method described in JIS K-7210-1999. When the difference in MFR exceeds 4 g / 10 min, when the resin is merged and widened by the FB die, the viscosity difference of the resin in each layer is greatly different, so the flow rate is not constant between the layers and the flow is disturbed. As a result, the appearance and transparency are impaired. In particular, when the transparency such as the total light transmittance described in JIS K-7361-1997 is regarded as important, the difference in MFR is preferably 3 g / 10 min or less.
[0009]
Further, in the present invention, the adapter temperature and the die temperature are set so that the difference between the storage elastic modulus at the dynamic viscoelasticity measurement at the adapter temperature and the storage elastic modulus at the die temperature in the resin used for each layer is 1500 Pa or less. is required.
The storage elastic modulus of the dynamic viscoelasticity measurement here is measured in advance by sandwiching a plasticized resin between parallel plates and dynamically applying a shearing force to the resin by its rotation. The frequency and stress are set and controlled by this apparatus.
Measuring apparatus: Rheometric Scientific dynamic viscoelasticity measuring machine DSR-200
Frequency: 1Hz Stress: 1000Pa
[0010]
If the difference between the storage elastic modulus at dynamic viscoelasticity measurement at the adapter temperature and the storage elastic modulus at the die temperature is greater than 1500 Pa, the flow will be disturbed because the viscoelastic properties change rapidly when the resin flows from the adapter to the die. As a result, the appearance and transparency of the molded product are impaired. This is because even if the MFR difference is 4 g / 10 min or less, the appearance and transparency of the molded product are impaired in the same manner as this difference in storage elastic modulus is greater than 1500 Pa.
[0011]
A well-known thing can be used for the extruder, adapter, and FB die | dye used for manufacture of the styrene-type laminated body of this invention. The die shape may be a coat hanger die having a manifold shape inclined in the width direction, but a straight manifold having a small inclination in the width direction is more preferable because the flow in the width direction becomes uniform.
A commercially available electric band heater or the like can be used for heating the adapter and the die. It is desirable to use a system in which the resin temperature is monitored by a temperature sensor such as a thermocouple and the result is fed back to adjust the temperature electrically.
[0012]
The styrenic polymer used in the present invention or the polymer composition containing this polymer is preferably an amorphous resin. When a crystalline resin is used in the outer layer of the laminated body, it is difficult to control the surface state because the viscosity and viscoelasticity change abruptly by cooling by metal contact such as an adapter or die. Therefore, crystalline resin is not preferred when the transparency required for the molded product to be obtained is high.
In the case of an amorphous resin, since the change in viscosity and viscoelastic characteristics with respect to temperature is gradual compared to a crystalline resin, the condition range can be relatively wide. In addition, many amorphous resins alone are highly transparent, which is advantageous when a laminated body is used. In particular, when at least one is a styrene-methyl methacrylate copolymer, the affinity with polystyrene is good and more preferable.
[0013]
The styrenic polymer used in the present invention or a polymer composition containing this polymer has a known additive, such as a plasticizer, a lubricant, an antioxidant, and a heat stable, within a range not to impair the purpose of the present invention. An agent, an ultraviolet absorber, an antistatic agent, a colorant, an antibacterial agent, a light diffusing agent and the like can be added.
The method for adding these additives is not particularly limited, and there are a dry blending method using a mixer such as Henschel, tumbler, and Banbury, and a melt kneading method using a single screw extruder, a twin screw extruder, or the like.
[0014]
After melt coextrusion, the film is cooled and stretched to increase transparency, and the orientation of molecular differences can be advanced to increase the strength of the molded product. As a method of co-stretching, for example, uniaxial stretching, simultaneous biaxial stretching, sequential biaxial stretching, and a multistage stretching method combining these can be used.
Of these, simultaneous or sequential biaxial stretching is preferably used in the present invention. Moreover, 3-20 times are preferable and, as for the area stretch ratio in that case, 4-10 times are more preferable. The stretching temperature at this time is preferably 80 to 180 ° C, more preferably 80 to 150 ° C.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the embodiment of the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited thereto. The evaluation and test equipment used are shown below.
[0016]
1. The MFR of each resin used was measured in advance at a temperature of 200 ° C. and a load of 5 kg using MELT INDEXER C-5059D manufactured by Toyo Seiki Seisakusho in accordance with JIS K-7210-1999.
2. The storage elastic modulus at each temperature of each resin to be used was measured by using a parallel plate with a DSR-200 manufactured by Rheometric Scientific, under the following settings.
Frequency: 1Hz
Initial Temp: 280 ° C
Final Temp: 100 ° C
Ramp Rate: 4 ℃ / min
Zone Time: 1 hour
Time Per Measure: 15 seconds
Stress: 1000Pa
The measurement sample was used after plasticizing a pellet. The pellets were previously dried at 75 ° C. for 2 hours with DN-43H manufactured by Yamato Scientific Co., Ltd. After holding the parallel plate at the above Initial Temp. For 1 minute, place the pellet on the lower plate, hold for another 2 minutes, narrow the parallel plate gap, adjust to 0.5 mm, and leave the edge The sample was scraped off.
3. The equipment used for extrusion and stretching is as follows.
Extruder for core (Extruder A): PLASTIC EXTRUDER NVC65 made by Nakatani Machinery
Surface layer extruder (Extruder B): PLASTIC EXTRUDER VSK40 manufactured by Nakatani Machinery Co., Ltd.
Longitudinal stretching machine: Tanabe Plastics Machinery 400 type longitudinal stretching roll unit Lateral stretching machine: Kobayashi Machinery Co., Ltd. SK-WE A88-027
4). The appearance of the obtained stretched sheet was visually evaluated, and a test piece was cut out to 50 mm × 50 mm from the center in the width direction, and HAZE METER NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd. was used, and the haze was JIS K-7136-2000. The total light transmittance was measured according to JIS K-7361-1997. The measured values of haze and total light transmittance were each average values measured five times.
[0017]
The resins used in the examples and comparative examples are shown below.
Resin A: HRM-6 manufactured by Toyo Styrene Co., Ltd.
Resin B: 77.5 parts by mass of styrene and 22.5 parts by mass of methyl methacrylate (MMA) in an autoclave equipped with a stirrer, 0.2 parts by mass of benzoyl peroxide, 0.1 parts by mass of t-dodecyl mercaptan, a suspension as a polymerization initiator As a turbid stabilizer, 0.001 part by mass of sodium dodecylbenzenesulfonate, 0.5 part by mass of tricalcium phosphate, and 200 parts by mass of pure water were charged and polymerized at a temperature of 95 ° C. for 6 hours and further at a temperature of 130 ° C. for 2 hours. . After completion of the reaction, washing, dehydration and drying were performed to obtain a styrene resin having a mass composition of styrene / MMA = 77.4 / 22.6.
Resin C: TF-2 made by Toyo Styrene Co., Ltd.
Resin D: SBS (styrene-butadiene-styrene block copolymer) 730L manufactured by Denki Kagaku Kogyo Co., Ltd.
Resin E: Melted and kneaded at a mass ratio of Resin A: Resin D = 4: 6.
Table 1 shows the measurement results of MFR and storage elastic modulus of each resin used.
[Table 1]

[0018]
[Example 1]
Feed block and coat hanger die in which resin A was extruded at extruder resin A at resin temperature 230 ° C and adapter temperature 230 ° C, and resin B was extruded at extruder resin B at resin temperature 215 ° C and adapter temperature 215 ° C. Through coextrusion. This sheet is continuously stretched 2.2 times in the flow direction at 115 ° C. in a longitudinal stretching machine, and then 2.2 times in the width direction at 125 ° C. in a transverse stretching machine, and a resin B / resin having a thickness of about 250 μm. A two-layer three-layer stretched sheet of A / resin B was obtained. The layer ratio at this time is about 1/9/1.
The stretched sheet thus obtained was measured for haze and total light transmittance by the method 4 described above. Moreover, when visually observed, it had a good appearance without melt fracture. The results are shown in Table 2. It can be seen that it has good transparency with a haze of 1.5% or less and a total light transmittance of 90% or more.
[0019]
[Examples 2 to 5]
And [Comparative Examples 1 to 4]
The same procedure as in Example 1 was performed except that a part of the resin used, the adapter temperature, and the die temperature was changed. The above results are summarized in Table 2. In Table 2, ◯ in the visual evaluation is no melt fracture, and x is melt fracture. Table 2 also shows the difference in each value of MFR in each Example and Comparative Example, and the difference in storage elastic modulus at dynamic viscoelasticity measurement at adapter temperature and storage temperature at die temperature in the resin used in each layer. Indicated.
[0020]
[Table 2]

[0021]
【The invention's effect】
The present invention provides a production method and a laminate for easily obtaining a styrene-based laminate having excellent appearance and transparency without causing flow disturbance at the interface between resins in a coextrusion method. The molded article is suitably used for food, medicine, stationery, packaging containers and films for daily necessities, and various industrial containers and films.

Claims (3)

In the multi-layer coextrusion method in which a styrenic polymer or a polymer composition containing this polymer is melt-extruded from a plurality of extruders and joined by a die via an adapter, a laminated body is obtained. The difference of each value of the melt flow rate measured by the resin temperature of 200 degreeC and the load of 5 kg of the styrene-type polymer used for a layer or the polymer composition containing this polymer is 4 g / 10min or less, and each layer To obtain a laminate by setting the adapter temperature and the die temperature so that the difference between the storage elastic modulus of the dynamic viscoelasticity measurement at the adapter temperature and the storage elastic modulus at the die temperature is 1500 Pa or less The manufacturing method of the styrene-type laminated body characterized by these. 2. The method for producing a styrene-based laminate according to claim 1, wherein at least one of the styrene-based polymer or the polymer composition containing the polymer is a styrene-methyl methacrylate copolymer. The method for producing a styrene-based laminate according to claim 1, wherein biaxial stretching is performed after coextrusion.