JPH11269322A - Thermoplastic resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a thermoplastic composition comprising a rubber-modified styrene-based resin and an ethylene-α-olefin copolymer, having excellent chemical resistance and improved mechanical characteristics such as balance between rigidity and impact strength, tensile strength, etc. SOLUTION: This thermoplastic resin composition comprises 5-95 wt.% of a rubber-modified styrene-based resin containing a rubber-like polymer dispersed in a granular state, 95-5 wt.% of an ethylene-α-olefin copolymer which is composed of ethylene and a 3-18C α-olefin, has <=90 deg.C peak temperature to show the maximum height in an elution curve of temperature rising elution fractionation(TFEF) and the ratio (H/W) of peak height (H) to width (W) of 1/3 height in the maximum peak of >=2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber-modified styrene resin and an ethylene-.alpha.-olefin copolymer, which are excellent in chemical resistance and have good balance between rigidity and impact resistance, mechanical properties such as tensile properties and the like. The present invention relates to a thermoplastic resin composition having excellent properties.

[0002]

2. Description of the Related Art Conventionally, rubber-modified styrenic resins containing a rubbery polymer dispersed in particles have excellent mechanical properties such as impact resistance, dimensional stability, etc., and can be inexpensive. Therefore, it is often used for parts of home electric appliances. However, this rubber-modified styrenic resin has a drawback that its use as a part that comes into direct contact with chemicals, organic solvents, and the like is limited due to poor chemical resistance and the like.

[0003] On the other hand, in order to improve the chemical resistance and the like of rubber-modified styrenic resins, it has long been considered to mix olefinic resins such as polyethylene and polypropylene. Various studies have also been made on the problem of poor mechanical properties such as impact resistance and tensile properties of the composition due to incompatibility with the resin, but there is still an essential solution to this problem. It has not yet arrived.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and comprises a rubber-modified styrene resin and an ethylene-α-olefin copolymer, and has excellent chemical resistance and rigidity. It is an object of the present invention to provide a thermoplastic resin composition excellent in mechanical properties such as balance between impact resistance and impact resistance and tensile properties.

[0005]

According to the present invention, there is provided a rubber-modified styrenic resin containing a rubbery polymer dispersed in the form of particles.
９５95% by weight, ethylene and an α-olefin having 3 to 18 carbon atoms, and the temperature of the peak having the maximum height in the elution curve of the temperature rise elution fractionation (TREF) is 90 ° C.
An ethylene-α-olefin copolymer having a ratio (H / W) of not more than 2 and a peak height (H) to a width (W) of １ ／ height at the maximum peak being 2 or more, and 95 to 5% by weight. % Of a thermoplastic resin composition.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The rubber-modified styrene resin as one of the constituents of the thermoplastic resin composition of the present invention is a known one containing a rubber-like polymer dispersed in a particle form. In the presence, one or more styrene-based monomers, or other copolymerizable monomers, bulk polymerization,
Alternatively, it is obtained by polymerization by a method such as bulk / suspension two-stage polymerization, and further includes a case where a rubber-unmodified styrene resin is mixed therein.

The styrene monomer includes, for example, styrene, α-alkyl-substituted styrene such as α-methylstyrene, and nucleated alkyl-substituted styrene such as p-methylstyrene. Examples of the polymerizable monomer include acrylonitrile, methacrylonitrile, methacrylic acid, methyl methacrylate, maleic anhydride, maleimide, and nucleus-substituted maleimide.
Examples of the rubbery polymer include, for example, polybutadiene rubber, styrene-butadiene copolymer rubber, ethylene-propylene copolymer rubber, ethylene-propylene-non-conjugated diene copolymer rubber, acrylic rubber, and the like. Among them, polybutadiene rubber and styrene-butadiene copolymer rubber are preferable.

In the present invention, the content of the rubbery polymer in the rubber-modified styrenic resin is preferably 1 to 30% by weight, more preferably 3 to 25% by weight, and more preferably 5 to 20% by weight. It is particularly preferred that the amount is by weight. If the content of the rubbery polymer is less than the above range, the impact resistance of the composition tends to be inferior, while if it exceeds the above range, the rigidity of the composition tends to be inferior. The average particle size of the rubbery polymer is preferably from 0.2 to 10 μm.
If the average particle diameter of the rubber-like polymer is less than the above range, the impact resistance of the composition tends to be inferior, while if it exceeds the above range, the surface gloss when the composition is formed into a molded article tends to decrease. .

The ethylene-α-olefin copolymer as the other component of the thermoplastic resin composition of the present invention comprises ethylene and an α-olefin having 3 to 18 carbon atoms.
Here, as the α-olefin having 3 to 18 carbon atoms, for example, 1-butene, 3-methyl-1-butene, 1-pentene, 4-methyl-1-pentene, 4,4-dimethyl-
1-pentene, 1-hexene, 4-methyl-1-hexene, 1-heptene, 1-octene and the like.
It preferably has 4 to 12 carbon atoms, and more preferably 6 to 10 carbon atoms. The content of the α-olefin in the ethylene-α-olefin copolymer is preferably 2 to 50% by weight, more preferably 5 to 40% by weight.

In the present invention, the ethylene-α-olefin copolymer has a peak temperature having a maximum height of 90 ° C. in an elution curve of a temperature rise elution fractionation (TREF).
It is essential that the ratio (H / W) of the peak height (H) to the width (W) of the 1/3 height at the maximum peak be 2 or more. If any of the peak temperature and the ratio (H / W) of the peak height (H) to the width (W) of the 1/3 height does not satisfy the above range, ethylene-α-olefin copolymer The compatibility of the united product with the rubber-modified styrene resin is insufficient, and the composition cannot have excellent mechanical properties such as balance between rigidity and impact resistance and tensile properties.

In this case, the temperature rise elution fractionation (Temperat
ure Rising Elution Fractionation (TREF)
This is a known analytical method, in which, in principle, the polymer is completely dissolved in a solvent at a high temperature and then cooled to form a thin polymer layer on the surface of the inert carrier that has been present in the solution. At this time, from a highly crystalline component which is easy to crystallize (for example, a linear component having no branch in polyethylene) to a low crystalline or amorphous component which is hard to be crystallized (for example, a component having many short chain branches in polyethylene). A polymer layer is formed. Then, when the temperature is raised continuously or stepwise, contrary to the above, the low-crystalline or non-crystalline component elutes, and finally the high-crystalline component elutes. The composition distribution of the polymer is analyzed from the elution amount at each temperature and the elution curve drawn by the elution temperature.

In the present invention, the measurement of the elution curve
The test was performed under the following conditions. Temperature rise elution fractionation (TREF), in which the sample is fractionated using the difference in dissolution temperature as a measuring device
Mechanism and size exclusion chromatograph (Size Exclusion Chromatogra)
SEC) was connected online ("CFC T150A" manufactured by Mitsubishi Chemical Corporation).

Using o-dichlorobenzene as a solvent,
The polymer is dissolved at 140 ° C. to a concentration of 4 mg / ml and injected into the sample loop of the measuring device. The sample solution in the sample loop was filled with glass beads as an inert carrier and had an inner diameter of 4 mm and a length of 150 mm.
And cooled from 140 ° C. to 0 ° C. at a rate of 1 ° C./min to coat the surface of the inert carrier. The column at 0 ° C for 3
After holding for 0 minutes, 2 m of the component dissolved at a temperature of 0 ° C.
1 is injected from a TREF column to a SEC column ("AD80M / S" manufactured by Showa Denko KK, 3 tubes) at a flow rate of 1 ml / min. While the molecular size is being fractionated by SEC, T
The operation of raising the temperature of the REF column to the next elution temperature (5 ° C.), maintaining the temperature for 30 minutes, and then injecting the SEC column into the SEC column is repeated. The measurement of each elution class by SEC is 39
Performed at minute intervals. Elution temperatures are 0, 5, 10, 15, 2
0, 25, 30, 35, 40, 45, 49, 52, 5
5, 58, 61, 64, 67, 70, 73, 76, 7
9, 82, 85, 88, 91, 94, 97, 100, 1
The temperature was set to 02, 120, and 140 ° C., and the temperature was increased stepwise.

The solution separated into molecular sizes by the SEC column is measured for absorbance in proportion to the polymer concentration (detected by the stretching vibration of methylene having a wavelength of 3.42 μm) using an infrared spectrophotometer attached to the apparatus, and the elution temperature is determined. Obtain a chromatogram of the sections. Using the built-in data processing software, a base line of the obtained chromatogram of each elution temperature section is drawn and arithmetic processing is performed. Integrate the area of each chromatogram and calculate the integrated elution curve. Further, a derivative elution curve is calculated by differentiating the integral elution curve with respect to temperature. The plot of the calculation results is output to a printer, and the plot of the output differential elution curve is plotted on the horizontal axis, where the elution temperature is 89.3 mm per 100 ° C., and the vertical axis is the differential amount (the total integrated elution amount is standardized to 1.0, The amount of change at 1 ° C. was defined as a differential amount.) The measurement was performed at 76.5 mm per 0.1.

In the present invention, the ethylene-α-
Olefin copolymers are available on size exclusion chromatographs (S
The Q value (weight average molecular weight / number average molecular weight) as the molecular weight distribution determined by EC) is preferably 4 or less, more preferably 3 or less, and particularly preferably 2.5 or less. When the Q value exceeds the above range, the surface appearance when the composition is formed into a molded article tends to decrease. The density of the ethylene-α-olefin copolymer is preferably 0.930 g / cm ³ or less, and the melt flow rate (190 ° C., 2.16 kg load) was 1
It is preferably 20 g / 10 min. In addition, 190
℃, the melt of 2.16kg load flow rate MFR _2.16
It is preferable that the ratio MFR ₁₀ / MFR _2.16 of the melt flow rate MFR ₁₀ at 190 ° C. and a load of 10 kg with respect to the MFR ₁₀ is not more than 7.

The ethylene-α-olefin copolymer in the present invention is described in, for example, JP-A-58-19309.
Nos. 59-95292, 60-35005, 60-35006, 60-35007, 60-
No. 35008, No. 60-35009, No. 61-130
No. 314, Japanese Patent Application Laid-Open No. H3-163088, European Patent Publication No. 420436, U.S. Pat.
No. 8, and a metallocene-based catalyst, particularly a metallocene-alumoxane-based catalyst, described in International Publication WO 91/04257 and the like, or described in, for example, International Publication WO 92/01723 and the like. Using a catalyst comprising a metallocene compound and a compound that reacts with the compound to form a stable anion, for example, a polymerization method such as a gas phase method, a slurry method, a solution method, and a high-pressure ionic polymerization method; It can be manufactured legally.

[0017] The thermoplastic resin composition of the present invention may contain 5 to 95% by weight, preferably 10 to 95% by weight of the rubber-modified styrenic resin.
90% by weight and 95 to 5% by weight of the ethylene-α-olefin copolymer, preferably 90 to 10% by weight. If the former styrene-based resin is less than the above range, the rigidity of the composition will be poor, while if it is more than the above range, the chemical resistance will be poor.

The thermoplastic resin composition of the present invention does not require a compatibilizer that is usually used in a composition of a styrene resin and an olefin resin, but may contain a compatibilizer. Other than the ethylene-α-olefin copolymer, other than the ethylene-α-olefin copolymer, for example, a branched polyethylene by a high pressure method, a linear low / low pressure method by a medium / low pressure method using a Ziegler catalyst may be used. Medium / high density polyethylene or the like may be blended. Further, if necessary, additives such as an antioxidant, an ultraviolet absorber, a lubricant, an antistatic agent, a release agent, a plasticizer, a flame retardant, a foaming agent, a dye and a pigment, and a filler may be added. .

The production of the thermoplastic resin composition of the present invention is carried out by a melt kneading machine usually used for producing a thermoplastic resin composition,
For example, the melt kneading is performed under ordinary conditions using a single screw extruder, a twin screw extruder, a roll, a Banbury mixer, a kneader, or the like.

The thermoplastic resin composition of the present invention described above can be formed into a molded product by a commonly used molding method, for example, an injection molding method, an extrusion molding method, a hollow molding method, a thermoforming method, or the like. It is formed into a foam by a molding method, a bead foam molding method, or the like, and is used for various purposes such as home electric parts, food containers, food packaging materials, and the like.

[0021]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention. The rubber-modified styrene resin, ethylene-α-olefin copolymer, and the like used in the following Examples and Comparative Examples are shown below.

Rubber-modified styrenic resin PS-1 whose rubbery polymer is polybutadiene rubber having a content of 8.5% by weight and an average dispersed particle size of 0.5 μm (Mitsubishi Chemical Corporation) "HT94
1 "). PS-2: The rubbery polymer is a polybutadiene rubber having a content of 7.5% by weight and an average dispersed particle size of 4.0 μm (“HT51” manufactured by Mitsubishi Chemical Corporation).
6 "). The content of the rubbery polymer is obtained by dissolving the rubber-modified styrenic resin in chloroform, adding iodine monochloride to react the double bonds in the rubber component, and adding potassium iodide to remain. It was determined by changing iodine monochloride to iodine and then back titrating with sodium thiosulfate.
The average particle diameter is determined by measuring the particle size of a rubber-modified styrene resin dispersed in dimethylformamide using a laser diffraction / scattering particle size distribution analyzer ("LA-70" manufactured by Horiba, Ltd.).
0 ") and obtained from the obtained volume-based particle size distribution.

Ethylene-α-olefin copolymer PE-1: an ethylene-1-hexene copolymer produced with a metallocene catalyst, having a density of 0.898 g /
cm ³ , melt flow rate 17 g / 10 min, TREF
With a maximum peak temperature of 58 ° C and an H / W of 3.8 (“EXACT4044” manufactured by EXXON). PE-2: an ethylene-1-hexene copolymer produced with a metallocene-based catalyst, having a density of 0.910 g /
cm ³ , melt flow rate 2.2 g / 10 min, TRE
One having a maximum peak temperature of 70 ° C. and an H / W of 3.9 in an elution curve of F (“EXACT3030” manufactured by EXXON).

PE-3: a linear low-density polyethylene produced with a Ziegler catalyst, having a density of 0.92
1 g / cm ³ , melt flow rate 16 g / 10 min, T
REF elution curve maximum peak temperature 89 ° C, H / W 0.
9 (“UJ370” manufactured by Nippon Polychem). PE-4: a high-density polyethylene produced by a Ziegler-based catalyst, having a density of 0.964 g / cm ³ , a melt flow rate of 7.0 g / 10 min, a maximum peak temperature of 98 ° C. in an elution curve of TREF, and H / W8. 0.7 (“HJ560” manufactured by Nippon Polychem Co., Ltd.).

Examples 1 to 5 and Comparative Examples 1 to 8 As rubber-modified styrenic resins and ethylene-α-olefin copolymers, those shown in Table 1 were used at the composition ratios shown in Table 1, respectively. 200 with a twin screw extruder with a diameter of 40 mm
The mixture was melted and kneaded at a temperature of 0 ° C. and pelletized. Each of the obtained pellets is injected with an injection molding machine (“IS-90B”) manufactured by Toshiba Machine Co., Ltd.
A test piece was formed by injection molding at a resin temperature of 200 ° C. and a mold temperature of 40 ° C. For each of the obtained test specimens, the tensile yield point strength, tensile elongation at break, flexural modulus, and Izod impact strength were measured by the methods described below.
It was shown to. The test pieces separately press-molded were evaluated for chemical resistance by the following method, and the results are shown in Table 1.

Tensile yield point strength and tensile elongation at break were measured at a measurement temperature of 23 ° C. and a tensile speed of 20 mm / min in accordance with JIS K7113. The flexural modulus was measured at a measurement temperature of 23 ° C. in accordance with JIS K7203. Izod impact strength A 1 / 8-inch thick V-notched test piece was measured at a measurement temperature of 23 ° C. in accordance with JIS K7110.

The ellipse represented by chemical resistance ^{x 2/12 2 + y 2} /4.5 2 = 1 1
A 1 mm thick test piece separately press-molded was fixed to a / 4 elliptical jig, and salad oil was applied to the surface of the test piece.
After being left for 4 hours, the test piece was visually observed to determine the minimum strain (critical strain) at which cracks occurred, and the chemical resistance was evaluated according to the following criteria. ；: Critical strain of 0.3% or more, or no defective appearance. Δ: Critical strain of 0.25% or more and less than 0.3%. ×: Critical strain of less than 0.25% or poor appearance such as whitening, swelling, and dissolution.

Example 6 and Comparative Example 9 The pellets obtained in the same manner as in Example 1 were extruded at a resin temperature of 220 ° C. using a 65 mm diameter extruder manufactured by Nippon Steel Works. A sheet was formed. The obtained sheet was measured and evaluated for tensile yield point strength and tensile elongation at break, flexural modulus, Izod impact strength, and chemical resistance in the same manner as in Example 1, and the results are shown in Table 1. Was.

[0029]

[Table 1]

[0030]

According to the present invention, a rubber-modified styrenic resin and an ethylene-α-olefin copolymer are used, which have excellent chemical resistance, balance between rigidity and impact resistance, and mechanical properties such as tensile properties. A thermoplastic resin composition having excellent properties can be provided.

Claims (2)

[Claims] 1. A rubber-modified styrenic resin containing a rubbery polymer dispersed in the form of particles, comprising 5 to 95% by weight, ethylene and an α-olefin having 3 to 18 carbon atoms. )), The temperature of the peak having the maximum height in the elution curve is 90 ° C. or less, and the ratio (H / W) of the peak height (H) to the width (W) of the 1/3 height of the maximum peak. Is from 95 to 5% by weight of an ethylene-α-olefin copolymer having 2 or more. 2. The rubber-modified styrenic resin according to claim 1, wherein the content of the rubbery polymer is 1 to 30% by weight, and the dispersed particles have an average particle size of 0.2 to 10 μm. Thermoplastic resin composition.