JPH03114727A - Manufacture of stretched article - Google Patents

Abstract

PURPOSE:To manufacture efficiently and cheaply a strip material having heat resistance, chemical resistance, and mechanical strength by cooling the strip material and thereafter uniaxially stretching it in the range of 1-40% in a width reduction rate. CONSTITUTION:A strip material is cooled which can be obtained by extruding or press-molding thermoplastic resin having a crystal structure. In the next place, the strip material is subjected to uniaxial stretching in the range of 1-40% in its width reduction rate in order to obtain a desired extended article. This thermoplastic resin is particularly made a stylene polymer having a syndiotactic structure.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing a drawn product, and in particular to a process for improving the efficiency of a drawn product of a thermoplastic resin having a crystalline structure, especially a styrenic polymer having a syndiotactic structure. Concerning good manufacturing methods.

[Prior art and problems to be solved by the invention] Generally, styrenic polymers, especially polystyrene, produced by radical polymerization are used, and are widely used in the fields of food packaging, miscellaneous goods packaging, industrial materials, etc. as films and sheets. It's being used. However, products obtained from polystyrene having an active stereoregular structure have drawbacks such as poor heat resistance, poor chemical resistance, and poor mechanical strength, so their field of use has been limited.

On the other hand, the group of the present inventors conducted research on materials that solved the above-mentioned drawbacks, and recently succeeded in developing a styrenic polymer with a syndiotactic structure (
(Japanese Unexamined Patent Publication No. 62-104818).

However, this styrenic polymer with a syndiotactic structure has a characteristic of having a crystalline structure, so it has to be extruded to a higher degree than the styrenic polymer used for boat fishing, and there is a risk of decomposition and deterioration. There is. Therefore, when extruding a styrenic polymer having such a syndiotactic structure (hereinafter sometimes abbreviated as SPS), the cooling conditions, the equipment used, and the conditions of the subsequent secondary processing equipment must be adjusted. There were various problems, including the need for special consideration.

Furthermore, polystyrene with an acute structure cannot be expected to improve its physical properties even if stretched [Kobunshi Kagaku 21,
206 (1964), it is possible to improve the physical properties of a thermoplastic resin having a crystalline structure such as SPS by stretching it under appropriate conditions. However, up to now S
Specific methods, conditions, etc. for rolling PS etc. have not been established.

Furthermore, Japanese Patent Application Laid-Open No. 63-77.905 discloses that stretching in the axial and biaxial directions three times or more is possible.
Although the specification of No. 05837 describes stretching uniaxially by a factor of 1.1 times or more, there is no description regarding the width reduction rate, and there is also no description of specific equipment or conditions.

Therefore, in order to solve the above-mentioned problems, the present inventor examined various practical conditions using specific manufacturing equipment, and conducted extensive research to develop an efficient stretching method.

As a result, it has been found that by stretching a belt-shaped member made of a thermoplastic resin having a crystalline structure at a specific width reduction rate, the physical properties can be significantly improved. The present invention was completed based on this knowledge.

[Means for Solving the Problems] That is, the present invention provides a belt-shaped member obtained by extrusion molding or press molding of a thermoplastic resin having a crystalline structure, and after cooling it, uniaxially bending the belt-shaped member to a width reduction rate in the range of 1 to 40%. The present invention provides a method for producing a stretched product, which is characterized by stretching.

Although the method of the present invention can be applied to thermoplastic resins having various crystal structures, styrenic polymers having a syndiotactic structure are particularly suitable. The syndiotactic structure in a styrenic polymer having this syndiotactic structure is a stereochemical structure or syndiotactic structure, that is, a phenyl group or a substituted side chain with respect to the main chain formed from carbon-carbon bonds. It has a three-dimensional structure in which phenyl groups are alternately located in opposite directions,
Its toughness is determined by nuclear magnetic resonance method (C-NMR method) using carbon isotope.13C-NMR
Toughness measured by the method can be expressed by the proportion of consecutive constituent units, for example, diats if there are two, triats if there are three, and pentads if there are five. The styrenic polymer having a syndiotactic structure according to the present invention is usually 75% or more, preferably 85% or more of racemic diad, or 30% or more, preferably 50% or more of racemic pentad. polystyrene, poly(alkyl styrene), poly(halogenated styrene), poly(alkoxystyrene), poly(vinyl benzoate), hydrogenated polymers thereof, mixtures thereof, or those containing these as the main component. refers to a copolymer with

Note that poly(alkylstyrene) here includes poly(methylstyrene) and poly(ethylstyrene).

Poly(isopropylstyrene), poly(tert-butylstyrene), poly(phenylstyrene) poly(vinylnaphthalene) 1 poly(vinylstyrene), etc. Poly(halogenated styrene) includes poly(chlorostyrene), poly(chlorostyrene), etc. (bromostyrene) poly(fluorostyrene), etc. In addition, poly(halogenated alkylstyrene) such as poly(chloromethylstyrene),
As poly(alkoxystyrene), poly(methoxystyrene) is used.

Examples include poly(ethoxystyrene). Furthermore, as comonomer components of copolymers containing these structural units,
In addition to the above styrene polymer monomers, ethylene, propylene, butene, and hexene.

Examples include olefin monomers such as octene, diene monomers such as butadiene isoprene, cyclic olefin monomers, cyclic diene monomers, and polar vinyl monomers such as methyl methacrylate, maleic anhydride, and acrylonitrile.

Among these, particularly preferred styrenic polymers include polystyrene, poly(alkylstyrene), poly(halogenated styrene), hydrogenated polystyrene, and copolymers containing structural units thereof.

A styrenic polymer having such a syndiotactic structure can be produced by using a titanium compound and a condensation product of water and trialkylaluminum as a catalyst, for example, in an inert hydrocarbon solvent or in the absence of a solvent. (monomer corresponding to the above-mentioned styrenic polymer) (Japanese Patent Laid-Open No. 61-18770
Publication No. 8). Further, poly(halogenated alkyl styrene) can be obtained by the method described in JP-A-1-46912, and hydrogenated polymers thereof can be obtained by the method described in JP-A-1-178,505.

The molecular weight of this styrenic polymer is not particularly limited, but the weight average molecular weight is 100,000 or more, preferably 300,000 or more. Further, there is no restriction on the width or narrowness of the molecular weight distribution, and various types can be used.

In the method of the present invention, a thermoplastic resin having a crystal structure such as SPS is further added to a generally used non-grade thermoplastic resin, rubber, an inorganic filler, an antioxidant, a plasticizer,
A compatibilizer 1, a coloring agent, etc. can be added.

The method of the present invention involves forming a thermoplastic resin having a crystalline structure, such as SPS, into a belt shape by extrusion molding or press molding, cooling it (especially rapid cooling), and then forming the thermoplastic resin with a width reduction rate of 1 to 40%. It is uniaxially stretched within a range. As for the extruder, T-die, press molding device, etc. used at this time, commonly used ones can be used as they are. In this molding, it is preferable to cool the material to below the glass transition temperature immediately after molding. In SPS, it is desirable that the crystallinity of the band member obtained by rapid cooling after molding is 30% or less, preferably 20% or less, and more preferably 10% or less. Further, it is desirable that the thickness unevenness of the band member be 10% or less, preferably 5% or less.

The temperature during stretching is the glass transition temperature (T
g) It is preferable that the temperature is 10°C lower than the melting point (Tm) of the resin, that is, (Tg - (Tm - 10°C)). If the stretching temperature is less than Tg, the molded product may be destroyed, and if it exceeds (Tm -10°C), the stretching effect may not be sufficiently obtained.

In the method of the present invention, the width reduction rate of the strip member is reduced to 1 as described above.
The sheet is uniaxially stretched to a range of 40% to 40%, preferably 5 to 30%.By stretching within this range, sheet rigidity can be improved and a stretched sheet with less edge heat can be obtained. In addition, there is little drawdown when thermoforming the obtained sheet, and the moldability is also good. In this case, if the width reduction rate is less than 1%, there will be almost no effect of stretching, and drawdown during thermoforming will increase, causing bridging and the like, making it impossible to obtain a good molded product.

Note that as the stretching device, it is possible to use various kinds of devices that have been commonly used in the past.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Reference example (manufacture of styrene polymer) 2p of toluene as a solvent in a reaction vessel! Then, 5 mmol of tetraethoxytitanium and 500 mmol of methylaluminoxane as aluminum atoms were added as catalyst components, and 15ffi of styrene was added to the dirt at 50° C., and a polymerization reaction was carried out for 4 hours.

After the reaction was completed, the product was washed with a hydrochloric acid-methanol mixture to decompose and remove the catalyst component. The mixture was then dried to obtain 2.5 kg of a styrene polymer (polystyrene). Next, this polymer was subjected to Soxhlet extraction using methyl ethyl getone as a solvent to obtain an extracted residue of 95 layers. The weight average molecular weight of this product was 800.000. Furthermore, analysis by 130-NMR measurement using 1,2-dichlorobenzene as a solvent revealed that 143 was caused by a syndiotactic structure.
．． Absorption was observed at 35 ppm, and the syndiotacticity for racemic pentads calculated from the peak area was 96%. To the thus obtained tafolystyrene, 0.1 weight of each of bis(24-sheepdelphenyl)pentaerythritol diphosphite and tetrakis[styrene(35-di-butyl-hydroxyhydrocinnamate)]methane were added as antioxidants. The mixture was mixed in parts and extruded into pellets using a twin-screw extruder with a diameter of 40 mm.

The melting temperature of the obtained styrenic polymer (SPS) (
Tm) is 270℃, glass transition temperature (Tg) is 100℃
Met.

Example 1 The SPS obtained in the above reference example was heated at 120 to 150°C for 2
After drying for ~5 hours, use an extruder with a diameter of 30 mm17)
Using uniaxial extrusion 1a (L/D=26), the extrusion amount was 6.9
kg/hour, the temperature distribution of the extruder is 290℃ near the input port.
2 Middle part 300℃ 9 Tip part 310'C, T die part 310
A belt-like member (sheet) having a width of 170 mm and a wall thickness of 0.5 °C was extruded and cooled using a cooling roll at a temperature of 60 °C. The crystallinity of this product was 20%, and the thickness unevenness was ±3%.

Next, this strip member was stretched using three stretching rolls at a temperature of 120°C, with the ratio of the take-up roll speed to the 10th roll speed being 1.3:1, and the 10th and 20th rolls.
The number of rotations of the rolls was gradually increased in the order of 1st roll, 30th roll, and take-up roll, so that the width reduction rate was 30%.

Table 1 shows the elastic modulus and thickness unevenness of the obtained stretched product.

Examples 2, 3 and Comparative Example 1.2 Adjusting the ratio of take-up roll speed and 10th roll speed to reduce width by 10% (Example 2), 5% (Example 3), and 50%
(Comparative Example 1) and 0% (Comparative Example 2, no stretching), the strip member was stretched in the same manner as in Example 1. Table 1 shows the elastic modulus and thickness unevenness of the obtained stretched product.

Comparative Examples 3 and 4 Using general polystyrene with an active structure instead of SPS as the resin material, the width reduction rate was 0% (Comparative Example 3).
(No stretching) and 30% (Comparative Example 4). Table 1 shows the elastic modulus and thickness unevenness of the obtained stretched product.

Furthermore, when the SPS sheets obtained in Examples 1 to 3 were thermoformed, good molded products with little drawdown were obtained.

Further, the SPS sheet that was not stretched in Comparative Example 2 had a large drawdown and bridging occurred during thermoforming at the same temperature, and a good molded product could not be obtained.

(The following is a blank space) [Effects of the Invention] As described above, according to the present invention, a belt-shaped member having excellent heat resistance, chemical resistance, and mechanical strength can be manufactured efficiently and at low cost. Furthermore, the band member obtained by the present invention has less drawdown during thermoforming and has good moldability.

Stretched products such as films and sheets produced in this way can be effectively used as packaging materials for various products including foods, or as various industrial materials.

Claims (3)

[Claims] (1) Manufacture of a stretched product characterized by cooling a belt-shaped member obtained by extrusion molding or press molding a thermoplastic resin having a crystal structure, and then uniaxially stretching it to a width reduction rate in the range of 1 to 40%. Method. (2) The manufacturing method according to claim 1, wherein the thermoplastic resin having a crystal structure is a styrenic polymer having a syndiotactic structure. (3) The manufacturing method according to claim 1, wherein the uniaxial stretching temperature is 10° C. lower than the glass transition temperature to melting point of the thermoplastic resin.