JP3124323B2 - Styrene resin molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a styrene resin molded article and a method for producing the same, and more particularly, to a styrene resin molded article having a high degree of crystallinity and excellent heat resistance, solvent resistance and transparency. And an efficient manufacturing method thereof.

[0002]

2. Description of the Related Art Syndiotactic styrene polymers are known to have high heat resistance and solvent resistance, and are expected to be used in various applications. In order to make full use of the characteristics of the styrene-based polymer, it is necessary to sufficiently increase the crystallinity of the molded article.
However, it is known that a molded product crystallized by a conventional method has low transparency. For example, as a molded article having a transparency made of a styrene-based polymer having a syndiotactic structure, a sheet having low crystallinity or a film having fine crystallization by stretching is known (JP-A-1-316).
246). However, this low crystallinity sheet
Insufficient heat resistance and solvent resistance. Although the above-mentioned stretched film has very excellent properties, the cost is high because the stretching apparatus is expensive. Further, when obtaining a thick stretched film, it is necessary to increase the thickness of the raw material having low crystallinity before stretching, and it has not been easy to produce a molded product having a thickness of 300 μm or more. Furthermore, a method of heat-treating a styrene-based polymer having a low crystallinity (Japanese Patent Application Laid-Open No. 1-272608) is known, but a transparent and crystallized molded product was not necessarily obtained by this method.

[0003]

Means for Solving the Problems Accordingly, the present inventors have:
Controlling the growth of positive birefringent crystal in primary crystallization and negative birefringent crystal in secondary crystallization and suppressing light scattering to produce transparent styrenic resin molded products with high crystallinity We examined the matter earnestly. As a result, the preform for heat treatment having a syndiotactic styrene polymer as a main component and a crystallinity of 20% or less is heat-treated in a certain temperature range, so that it has high crystallinity without stretching. And a highly transparent molded article can be obtained efficiently. The present invention has been completed based on such findings.

That is, the present invention comprises a styrenic polymer having a high syndiotactic structure (hereinafter sometimes referred to as SPS) or a composition thereof, and has a crystallinity of 25% or more and a spherulite radius of 10 μm. And a haze of 5% or less.

In the present invention, the styrenic polymer used as the material of the molded article has a high syndiotactic structure. Here, the advanced syndiotactic structure is a syndiotactic structure having a high stereochemical structure. An tactic structure, that is, a steric structure in which phenyl groups and substituted phenyl groups, which are side chains, are alternately located in opposite directions to a main chain formed from carbon-carbon bonds, and their tacticity is isotope Nuclear magnetic resonance method using carbon ( ¹³ C-N
(MR method). ^The tacticity measured by the ¹³ C-NMR method can be represented by the proportion of a plurality of continuous constituent units, for example, a dyad for two, a triad for three, and a pentad for five. However, the SPS referred to in the present invention is a polystyrene having a syndiotacticity of usually 75% or more, preferably 85% or more in a dyad, or 30% or more, preferably 50% or more in a pentad (racemic pentad). Poly (alkyl styrene), poly (halogenated styrene), poly (alkoxy styrene), poly (vinyl benzoate), a mixture thereof, or a copolymer containing these as a main component. The poly (alkyl styrene) includes poly (methyl styrene), poly (ethyl styrene), poly (isopropyl styrene), poly (tertiary butyl styrene) and the like, and poly (halogenated styrene) includes Examples include poly (chlorostyrene), poly (bromostyrene), and poly (fluorostyrene). Examples of poly (alkoxystyrene) include poly (methoxystyrene) and poly (ethoxystyrene). Of these, particularly preferred styrene polymers include polystyrene, poly (p-methylstyrene), poly (m-methylstyrene), poly (p-tert-butylstyrene), poly (p-chlorostyrene), and poly (p-chlorostyrene). m-chlorostyrene), poly (p-fluorostyrene), and a copolymer of styrene and p-methylstyrene.

The molecular weight of the SPS used in the present invention is not limited, but preferably has a weight average molecular weight of 10,000 or more, and most preferably has a weight average molecular weight of 50,000 or more. Further, the molecular weight distribution is not limited in its width, and various molecular weight distributions can be applied.
This SPS has a melting point of 200 to 310 ° C. and is much more excellent in heat resistance than a conventional styrene polymer having an atactic structure. Such SPS is prepared, for example, by using a titanium compound and a condensation product of water and a trialkylaluminum as a catalyst in an inert hydrocarbon solvent or in the absence of a solvent, using a styrene-based monomer (for the styrene-based polymer). (Corresponding monomer). The molded article of the present invention can be obtained by molding the above-mentioned styrene-based polymer (SPS). The styrene-based polymer includes thermoplastic resins and rubbers generally used within a range not to impair the object of the present invention. , An antioxidant, an inorganic filler, a cross-linking agent, a cross-linking aid, a nucleating agent, a plasticizer, a compatibilizer, a coloring agent, an antistatic agent, and the like, and used as a composition.

Examples of the thermoplastic resin include styrene-based polymers such as polystyrene having an atactic structure, polystyrene having an isotactic structure, AS resin and ABS resin, polyesters such as polyethylene terephthalate, polycarbonate, polyphenylene oxide, polysulfone, and the like. Polyether such as polyether sulfone, polyamide, polyphenylene sulfide (PP
S), condensation polymers such as polyoxymethylene, acrylic polymers such as polyacrylic acid, polyacrylate and polymethyl methacrylate, polyethylene, polypropylene, polybutene, poly 4-methylpentene
Examples thereof include polyolefins such as 1, ethylene-propylene copolymers, halogen-containing vinyl compound polymers such as polyvinyl chloride, polyvinylidene chloride, and polyvinylidene fluoride, and mixtures thereof.

Although various rubbers can be used, the most preferable one is a rubber-like copolymer containing a styrene compound as one component.
Rubber in which the butadiene part of the butadiene block copolymer is partially or completely hydrogenated (SEBS), styrene-
Butadiene copolymer rubber (SBR), methyl acrylate-butadiene-styrene copolymer rubber, acrylonitrile-butadiene-styrene copolymer rubber (ABS rubber), acrylonitrile-alkyl acrylate-butadiene-styrene copolymer rubber (ABS) , Methyl methacrylate-alkyl acrylate-styrene copolymer rubber (MAS), Methyl methacrylate-alkyl acrylate-butadiene-styrene copolymer rubber (MABS)
And mixtures thereof. Since the rubbery copolymer containing these styrene compounds as one component has styrene units, it has good dispersibility in styrene polymers having a high syndiotactic structure, resulting in improved physical properties. The effect is remarkable. Other examples of rubbers that can be used include natural rubber, polybutadiene, polyisoprene, polyisobutylene, neoprene, ethylene-propylene copolymer rubber,
Polysulfide rubber, thiocol rubber, acrylic rubber,
Examples include urethane rubber, silicone rubber, epichlorohydrin rubber, polyether / ester rubber, polyester / ester rubber, and the like, and mixtures thereof.

There are various antioxidants,
In particular, phosphorus-based antioxidants such as tris (2,4-di-t-butylphenyl) phosphite and tris (mono- and di-nonylphenyl) phosphite and diphosphites and phenolic antioxidants are preferred. . As the diphosphite, a general formula

[0010]

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(Wherein, R ¹ and R ² each independently represent an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms). It is preferable to use a phosphorus compound. Specific examples of the phosphorus compound represented by the above general formula include distearyl pentaerythritol diphosphite; dioctyl pentaerythritol diphosphite;
Diphenylpentaerythritol diphosphite; bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite; bis (2,6-di-t-butyl-
4-methylphenyl) pentaerythritol diphosphite; dicyclohexylpentaerythritol diphosphite; Known phenolic antioxidants can be used, and specific examples thereof include 2,6-di-t-butyl-4-methylphenol; and 2,6-diphenyl-4-methoxyphenol. 2,2'-methylenebis (6-t-butyl-4-methylphenol); 2,2'-methylenebis- (6-t
-Butyl-4-methylphenol); 2,2'-methylenebis [4-methyl-6- (α-methylcyclohexyl) phenol]; 1,1-bis (5-t-butyl-4)
-Hydroxy-2-methylphenyl) butane; 2,2 ′
-Methylenebis (4-methyl-6-cyclohexylphenol); 2,2'-methylenebis- (4-methyl-6
-Nonylphenol); 1,1,3-tris- (5-t
-Butyl-4-hydroxy-2-methylphenyl) butane; 2,2-bis- (5-tert-butyl-4-hydroxy-2-methylphenyl) -4-n-dodecylmercaptobutane; ethylene glycol-bis [ 3,3-bis (3
-T-butyl-4-hydroxyphenyl) butyrate]; 1-1-bis (3,5-dimethyl-2-hydroxyphenyl) -3- (n-dodecylthio) -butane;
4,4'-thiobis (6-t-butyl-3-methylphenol); 1,3,5-tris (3,5-di-t-butyl-4-hydroxybenzyl) -2,4,6-trimethyl Benzene; 2,2-bis (3,5-di-t-butyl-
4-hydroxybenzyl) malonic acid dioctadecyl ester; n-octadecyl-3- (4-hydroxy-3,
5-di-t-butylphenyl) propionate; tetrakis [methylene (3,5-di-t-butyl-4-hydroxyhydrocinnamate)] methane and the like. Further, in addition to the phosphorus-based antioxidant and the phenol-based antioxidant, an amine-based antioxidant, a sulfur-based antioxidant, and the like can be used alone or in combination.

The above-mentioned antioxidant is used in the above-mentioned SPS100.
It is usually 0.0001 to 1 part by weight based on part by weight. Here, when the compounding ratio of the antioxidant is less than 0.0001 parts by weight, the molecular weight is remarkably reduced, and when it exceeds 1 part by weight, the mechanical strength is affected, and neither is preferable.

The inorganic filler is not limited to fibrous ones, granular or powdery ones. Examples of the fibrous inorganic filler include glass fiber, carbon fiber, and alumina fiber. On the other hand, granular and powdery inorganic fillers include talc, carbon black, graphite, titanium dioxide, silica, mica, calcium carbonate, calcium sulfate, barium carbonate, magnesium carbonate, magnesium sulfate, barium sulfate, oxysulfate, tin oxide,
Examples include alumina, kaolin, silicon carbide, and metal powder.

Examples of the crosslinking agent include t-butyl hydroperoxide; cumene hydroperoxide; diisopropylbenzene peroxide; 2,5-dimethyl-2,5-
Dihydroperoxyhexane; 2,5-dimethyl-2,5
Suitable amounts of hydroperoxides such as -dihydroperoxyhexane-3, dialkyl peroxides, ketone peroxides, diacyl peroxides, peroxyesters and the like can be used.

Examples of the crosslinking assistant include p-quinone dioxime; quinone dioximes such as p, p-dibenzoylquinone dioxime; methacrylates such as polyethylene glycol dimethacrylate; allyl compounds; and maleimide compounds. Can be used.

The styrenic resin molded article of the present invention can be prepared by using SPS as described above or a thermoplastic resin, rubber, antioxidant, inorganic filler, crosslinking agent, crosslinking assistant, nucleating agent, plasticizer, compatibilizing agent. A composition to which a coloring agent, a coloring agent, an antistatic agent and the like are added is used as a material, and the physical properties thereof are as follows. That is, the crystallinity of the styrenic resin molded article of the present invention is 25% or more, preferably 30% or more. Here, when the crystallinity is less than 25%, the heat resistance is insufficient.
The haze is at most 5%, preferably at most 4%.
If the haze exceeds 5%, the transparency becomes insufficient.
Further, the spherulite radius (measured by a light scattering method) is 10 μm or less, preferably 5 μm or less. Spherulite radius 10μm
If it exceeds, the transparency becomes insufficient. The non-orientation referred to in the present invention means that the absolute value of birefringence (| Δn |) is 20 × 10 ⁻³ or less, preferably 10 × 10 ⁻³ or less.

There are various methods for producing the styrenic resin molded article of the present invention. For example, the method of the present invention can be mentioned as a preferable method. That is, first,
The above-mentioned SPS or a composition to which the above-mentioned various components are added as necessary is preformed to obtain a preform for heat treatment (film, sheet or container). In this molding, what is necessary is just to extrude a heat-melted material of the above-mentioned molding material into a predetermined shape. In the case of a film or a sheet, it is to be molded by T-die molding, and other structures such as containers are molded by injection molding. Can be. The extruder used here may be either a single-screw extruder or a twin-screw extruder, and may be either with or without vent. Extrusion conditions are not particularly limited and may be appropriately selected according to various situations.Preferably, the temperature at the time of melting is selected in a range of from the melting point of the molding material to a temperature 50 ° C. higher than the decomposition temperature, and the shearing stress is adjusted. 5x
When it is set to 10 ⁶ dyne / cm ² or less, a preform for heat treatment with less surface roughness can be obtained. After the extrusion molding, it is preferable that the obtained preformed body for heat treatment is cooled and solidified. At this time, various refrigerants such as gas, liquid, and metal can be used. When a metal roll or the like is used for forming the preform for heat treatment by sheet forming, an air knife, an air chamber,
According to a method such as a touch roll or electrostatic application, it is effective in preventing thickness unevenness and waving. The temperature for cooling and solidification is usually from 0 ° C. to 30 ° C. below the glass transition temperature of the preform for heat treatment.
° C higher temperature range, preferably 7 ° C above the glass transition temperature.
The temperature range is from 0 ° C. lower to glass transition or lower. The cooling rate is not particularly limited, but is 200 to 3 ° C./sec.
Preferably, it is appropriately selected within the range of 200 to 10 ° C./sec.

The preform for heat treatment may be of various shapes, but usually has a thickness of 5 mm or less, preferably 3 m
m, such as sheets, films, containers (tubes, trays, etc.). If the thickness of the preform for heat treatment before heat treatment is more than 5 mm, the internal crystallization may progress during formation of the preform for heat treatment, resulting in cloudiness. The crystallinity of the heat-treated preform is 20%.
Or less, preferably 15% or less. Here, if the crystallinity of the heat-treated preform exceeds 20%, the transparency of the styrene-based resin molded article after the heat treatment is not sufficient.

The styrenic resin molded article of the present invention can be obtained, for example, by subjecting the above preformed article for heat treatment to a heat treatment in a temperature range of 140 to 180 ° C, preferably 150 to 170 ° C. Here, the heat treatment temperature is 14
If the temperature is lower than 0 ° C, the heat resistance may not be sufficient and the film may become cloudy. If the temperature is higher than 180 ° C, the transparency may be insufficient. The time for this heat treatment is usually 1 second to 30 minutes, preferably 1 second to 10 minutes. In addition, the temperature rising rate at this time is desirably set to a predetermined heat treatment temperature by rapidly raising the temperature of the preformed body for heat treatment. If the rate of temperature rise is lower than 30 ° C./min, heat treatment will be performed below a predetermined heat treatment temperature,
The transparency of the styrenic resin molded article may be impaired. The heating method of the heat treatment is not particularly limited,
For example, it may be brought into contact with a heat medium such as a gas, a liquid, and a metal at 120 to 200 ° C. Further, the styrene-based resin molded body heat-treated under the above conditions may be heat-treated again if necessary. As the heat treatment conditions at this time, it is appropriate that the heat treatment time is equal to or higher than the glass transition temperature and equal to or lower than the melting point, and the heat treatment time is equal to or longer than 1 second.
The styrene-based resin molded body that has been heat-treated again cannot improve the crystallinity, but can increase the heat distortion temperature without impairing the transparency.

[0020]

Next, the present invention will be described in more detail with reference to Reference Examples, Production Examples, Examples and Comparative Examples. Reference Example 1 17 g of copper sulfate pentahydrate (CuSO ₄ 5H ₂ O) was placed in a glass container having an inner volume of 500 ml and purged with argon.
(71 mmol), 200 ml of toluene and 24 ml (250 mmol) of trimethylaluminum were added and reacted at 40 ° C. for 8 hours. Thereafter, the solid portion was removed to obtain 6.7 g of a contact product. The molecular weight of the obtained contact product measured by freezing point depression method was 610.
Met.

Production Example 1 1 liter of purified styrene, 5 mmol of the contact product obtained in Reference Example 1 as aluminum atom, 5 mmol of triisobutylaluminum, 5 mmol of pentamethylcyclopentadienyl titanium in a 2 liter reaction vessel A polymerization reaction was carried out at 90 ° C. for 5 hours using 0.025 mmol of trimethoxide. After completion of the reaction, the product was decomposed with a methanol solution of sodium hydroxide to decompose the product, washed repeatedly with methanol, and dried to obtain 308 g of a polymer. The weight average molecular weight of this polymer was measured by gel permeation chromatography at 130 ° C. using 1,2,4-trichlorobenzene as a solvent.
And the weight average molecular weight / number average molecular weight is 2.64.
Met. Further, by measuring the melting point and ¹³ C-NMR, it was confirmed that this polymer was an SPS having a syndiotacticity of 97%.

Production Example 2 Production Example 1 was the same as Production Example 1, except that 950 ml of purified styrene and 50 ml of p-methylstyrene were used as starting monomers.
The same operation as described above was performed. As a result, the obtained copolymer had a co-syndiotactic structure (syndiotacticity of 97%), and it could be confirmed by ¹³ C-NMR measurement that it contained 9.5 mol% of p-methylstyrene units. Was.
The weight average molecular weight was 438,000, and the ratio of weight average molecular weight / number average molecular weight was 2.51.

Example 1 The styrenic polymer powder obtained in Production Example 1 was mixed with 150
Vacuum dried while stirring at 2 ° C. for 2 hours. This powder
Includes multiple capillaries at the tip of a vented single screw extruder
After extruding with a device equipped with a die, cool and cut.
Thus, an extrusion molding material (pellet) was prepared. At this time,
Conditions include a melting temperature of 300 ° C, an extrusion rate of 30 kg / hour,
Pressure was 10 mmHg. The pellet is then heated
Crystallization and drying were performed while stirring in the air. The obtained pe
500 ppm of styrene monomer remaining in let, crystallinity
Was 35%. Using these pellets, single screw extruder
Extruded with a device equipped with a T-die at the tip of
Obtained. The extrusion temperature at this time is 320 ° C, and the shear stress is 3 ×
10^Fivedyne / cm^TwoMet. Quiet the obtained sheet
By applying electricity, it is brought into close contact with the metal cooling roll and cooled,
A preform (sheet) for use was prepared. At this time,
The cooling roll is adjusted to 70 ° C and the cooling rate is 70 ° C / sec.
Was. The thickness of the heat treatment preform was 15
At 0 μm, the crystallinity was 13%. This heat treatment reserve
The preform is heat-treated in an oven at 155 ° C for 10 minutes.
Was. The heating rate of the heat treatment temperature was 200 ° C./min. Profit
The crystallinity of the obtained styrenic resin molded product was 43%,
Is 0.8%, spherulite radius is 1.4 μm, | Δn | is 5.1 × 1
0 ^-3(Low orientation). In addition, thermal mechanical
The length of the styrenic resin molded product was determined by analysis (TMA).
When the temperature at which the material deformed by 2% was measured, it was 175 ° C.
Was.

Example 2 Thickness 400 μm prepared by adjusting the extrusion amount and lip opening
A styrenic resin molded article was prepared and the physical properties were measured in the same manner as in Example 1, except that the heat-treated preform was used and the rate of temperature increase was changed. Table 1 shows the obtained results.

Example 3 The styrenic resin molded product obtained in Example 2 was heat-treated again (240 ° C., 10 seconds) to form a styrenic resin molded product, and its physical properties were measured. Table 1 shows the obtained results.

Example 4 Using the styrenic polymer obtained in Production Example 2, the
Styrene-based resin in the same manner as in Example 1 except that a preformed body (sheet) for heat treatment having a thickness of 1000 μm prepared by adjusting the lip opening was used and the rate of temperature increase was changed. A molded article was prepared and its physical properties were measured.
Table 1 shows the obtained results.

Example 5 Using the styrene polymer obtained in Production Example 2, the
Styrene-based resin in the same manner as in Example 1 except that a heat treatment preform (sheet) having a thickness of 2500 μm prepared by adjusting the lip opening was used, and the rate of temperature increase was changed. A molded article was prepared and its physical properties were measured.
Table 1 shows the obtained results.

Example 6 A styrenic resin molded product (film) was prepared in the same manner as in Example 1 except that the heat treatment temperature was 165 ° C.
Physical properties were measured. Table 1 shows the obtained results.

Comparative Example 1 The physical properties were measured in the same manner as in Example 1 except that no heat treatment was performed. Table 1 shows the obtained results.

Comparative Example 2 The procedure of Example 1 was repeated, except that the heat treatment temperature was set to 250 ° C. and the rate of temperature increase was changed.
Physical properties were measured. Table 1 shows the obtained results.

Comparative Example 3 The physical properties were measured in the same manner as in Example 1 except that the heat treatment temperature was changed to 130 ° C. Table 1 shows the obtained results.

Comparative Example 4 The physical properties were measured in the same manner as in Example 1 except that an air gap was opened at the time of forming the styrenic resin molded article, and the rate of increasing the heat treatment temperature was changed. Table 1 shows the obtained results.

[0033]

[Table 1]

[0034]

[Table 2]

The test methods and conditions used in the above physical property tests are shown below. Haze: Based on JIS K7105. Crystallinity: Endothermic enthalpy at melting point (ΔΔ) measured at a constant heating rate using a differential scanning calorimeter (DSC).
H _m ), the exothermic enthalpy at the cold crystallization temperature (ΔH
_cc ) and the enthalpy of fusion of 100% crystal (ΔH
_f : 53 J / g) and the crystallinity (X _c ) was determined as (X
_{c = (ΔH m -ΔH cc)} / ΔH f). Spherulite radius: The spherulite radius (R) was determined from the maximum scattering angle (θ _m ) of the scattering image measured with Cross Nicol F using a light scattering measurement device. | Δn |: The retardation (Γ) was measured using a polarizing microscope and a Berek compensator to determine the birefringence | Δn |. Heat resistance: The temperature at which the length of the molded body was deformed by 2% was measured by thermal mechanical analysis (TMA).

[0036]

As described above, the styrenic resin molded article of the present invention is a styrenic resin molded article having a high degree of crystallinity and excellent heat resistance and transparency. Therefore, the styrene resin molded article of the present invention can be effectively used as a heat-resistant transparent sheet such as a wrap, a heat-resistant transparent container such as a microwave oven container, a food packaging container, and a heat-resistant bottle.

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Claims (2)

(57) [Claims] 1. A styrene polymer having a high degree of syndiotactic structure or a composition thereof, and having a crystallinity of 25% or more, a spherulite radius of 10 μm or less, and a haze of 5% or less. Oriented styrene resin molded article. 2. The molded article is a film having a thickness of 5 mm or less,
The styrenic resin molded product according to claim 1, which is a sheet or a container.