JPH08295771A - Bimodal rubber reinforced styrene resin composition having good colorability and excellent balance between flowability and impact resistance - Google Patents

Abstract

PURPOSE: To obtain a bimodal rubber reinforced styrene resin composition having good colorability and an excellent balance between the flowability and the impact resistance by blending a bulk copolymer and an emulsion graft copolymer each having a specified constitution with a low-molecular-weight rigid copolymer. CONSTITUTION: This composition consists of 10-35 pts.wt. bulk copolymer of styrene monomer, an unsaturated nitrile monomer and a rubbery polymer (wherein the volume- mean particle diameter of the rubbery polymer is 0.5-2.5μm and the content thereof is 10-15wt.%); 30-55 pts.wt. emulsion graft copolymer of styrene monomer, an unsaturated nitrile monomer and a rubbery polymer (wherein the volume-mean particle diameter of the rubbery polymer is 0.06-0.4μm, the content thereof is 35-50wt.%, the weight- average molecular weight (Mw hereafter) of a free styrene/nitrile copolymer is 50,000 to 100,000, and the Mw of the graft copolymer is 60,000 to 120,000); and 10-60 pts.wt. low-molecular-weight rigid copolymer of styrene monomer and an unsaturated nitrile monomer [wherein the weight ratio of styrene monomer to nitrile monomer is (15:85) to (30:70), and the Mw of the copolymer is 40,000 to 120,000].

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bimodal rubber-reinforced styrene resin composition having good colorability and excellent flowability / impact resistance balance.

[0002]

2. Description of the Related Art ABS (acrylonitrile-butadiene-styrene) resin has appropriate moldability and impact resistance,
Since it is easy to color, it is used in a wide range of fields as a relatively inexpensive plastic material. Normal ABS
The resin has a monomodal distribution with a rubber particle diameter of about 0.2 to 0.3 μm, which is one factor for expressing a good physical property balance. However, if an ordinary monomodal ABS resin is to be used in a higher flow region than the molding conditions normally used, the impact strength, particularly the surface impact property, remarkably decreases, and it cannot be put to practical use.

On the other hand, HIPS (high-impact polystyrene) is difficult to have impact strength similar to that of high-impact ABS resin, but has extremely excellent fluidity / impact resistance balance in the high flow region and good coloring property. Is. This colorability is closely related to the pigment cost, and a material exhibiting good colorability can reduce the amount of pigment added, and is therefore effective in reducing the manufacturing cost.

On the other hand, research on bimodal resin compositions of rubber has been conducted for a long time for both ABS resin and HIPS, and many documents and patents have been published. It is known that a composition having rubber particles having a bimodal distribution has a synergistic effect on the impact strength due to the combination of the respective rubber particle diameters. , Are being examined according to the required characteristics of each. However, conventionally,
No studies have been made on improving the fluidity / impact resistance balance in the ultra-high flow region for ABS resins.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above conventional circumstances, and has excellent moldability equivalent to that of HIPS and impact strength (Izod impact, dirt impact). It is an object of the present invention to provide an ABS resin composition having good flowability / impact resistance balance (flow / impact balance) and colorability.

[0006]

The bimodal rubber-reinforced styrenic resin composition of the present invention, which has good colorability and excellent flowability / impact resistance balance, comprises a styrenic monomer and an unsaturated nitrile resin. A bulk copolymer of a monomer and a rubber-like polymer, wherein the volume average particle diameter of the rubber-like polymer is 0.5 to 2.5 μm, and the content of the rubber-like polymer is 10 to 15% by weight in bulk. Copolymer: 10 to 35 parts by weight An emulsion polymerization graft copolymer of a styrene-based monomer, an unsaturated nitrile-based monomer and a rubber-like polymer, wherein the rubber-like polymer has a volume average particle diameter of 0. 06-0.4 μm, content of rubber-like polymer 35 to 50% by weight, weight average molecular weight of free styrene-based monomer and unsaturated nitrile-based copolymer 50,000 to 100,000, graft Styrenic monomer and unsaturated Graft copolymer having a weight average molecular weight of 60,000 to 120,000 of a copolymer with a tolyl monomer: 30 to 55 parts by weight, and a styrene monomer and an unsaturated nitrile monomer are copolymerized. The resulting low molecular weight hard copolymer, wherein the weight ratio of unsaturated nitrile monomer to styrene monomer is unsaturated nitrile monomer / styrene monomer = 15 / 85-3
0/70, the weight average molecular weight of the hard copolymer is 40,000
~ 120,000 low molecular weight rigid copolymers: 10-6
It is characterized by containing 0 parts by weight.

That is, the inventors of the present invention have made a bimodal rubber reinforced styrene obtained by blending a bulk copolymer having a structure regulated under certain specific conditions, an emulsion polymerization graft copolymer and a low molecular weight rigid copolymer in a specific ratio. The present invention has been completed by finding that the resin composition satisfies the above-mentioned required characteristics.

In particular, the emulsion-polymerized graft copolymer and the low-molecular-weight hard copolymer according to the present invention have a structure different from that of the composition used in the ordinary ABS resin, and are effectively used in the present invention. in use.

The present invention will be described in detail below.

The rubber-reinforced styrenic resin composition of the present invention contains the bulk copolymer, the graft copolymer and the low molecular weight hard copolymer having the above-mentioned specific constitution.

In the present invention, the styrene-based monomer and unsaturated nitrile-based monomer used as raw materials for synthesizing the bulk copolymer, the graft copolymer and the low molecular weight rigid copolymer are as follows. Is mentioned.

Styrene-based monomers include styrene and α
-Methylstyrene, α-ethylstyrene, p-methylstyrene and the like can be mentioned, but it is most preferable to use styrene. When another styrene-based monomer such as α-methylstyrene is used together with styrene, the amount used is preferably twice or less that of styrene.

Examples of the unsaturated nitrile-based monomer include acrylonitrile, methacrylonitrile, ethacrylonitrile, fumaronitrile and the like, and acrylonitrile is preferably used.

In the present invention, the rubber-like polymer used as a raw material for synthesizing the bulk copolymer and the graft copolymer is polybutadiene rubber (PBD), styrene butadiene rubber (SBR), ethylene propylene diene rubber (EPDM). ), Ethylene-propylene rubber (E
PR), butadiene-acrylonitrile rubber (NB
R), isoprene rubber (IR), acrylic rubber (AR)
Etc. can be used.

The bulk copolymer according to the present invention is obtained by bulk-polymerizing a styrene-based monomer, an unsaturated nitrile-based monomer and a rubber-like polymer, and the volume average of the rubber-like polymer. The particle diameter (Dv) is 0.5 to 2.5 μm, and the content of the rubber-like polymer is 10 to 15% by weight.

If the Dv and content of the rubbery polymer of the bulk copolymer are out of the above range, a rubber-reinforced styrene resin composition having a good flow / impact balance cannot be obtained.

The weight ratio of the unsaturated nitrile monomer and the styrene monomer of this bulk copolymer (hereinafter referred to as "AN / S
Abbreviated as "T". ) Is preferably in the range of 20/80 to 40/60.

The rubbery polymer preferably has a number average particle diameter (Dn) of 0.3 to 1.2 and a volume average particle diameter (Dn).
The ratio of v) to the number average particle diameter (Dn) is preferably 1.5 to 2.5.

The graft copolymer according to the present invention is obtained by emulsion-polymerizing a styrene-based monomer, an unsaturated nitrile-based monomer and a rubber-like polymer, and the Dv of the rubber-like polymer is A copolymer of free styrene-based monomer and unsaturated nitrile-based monomer (hereinafter referred to as "free SA") having a rubbery polymer content of 0.06 to 0.4 μm and a rubbery polymer content of 30 to 50% by weight.
N ". ) Has a weight average molecular weight (Mw) of 50,000
˜100,000, a copolymer of a grafted styrene monomer and an unsaturated nitrile monomer (hereinafter referred to as “Graft S
It is called "AN". ) Has a weight average molecular weight (Mw) of 6000
0 to 120,000.

When the Dv and content of the rubber-like polymer of the graft copolymer and the Mw of free SAN and graft SAN are out of the above ranges, a rubber-reinforced styrene resin composition having a good flow / impact balance can be obtained. I can't.

The weight ratio AN / ST of the unsaturated nitrile monomer and the styrene monomer of this graft copolymer is 2
It is preferably in the range of 0/80 to 30/70.

The low molecular weight hard copolymer according to the present invention is obtained by copolymerizing a styrene monomer, an unsaturated nitrile monomer, and, if necessary, a third component copolymerizable therewith. The weight ratio AN / ST of the unsaturated nitrile-based monomer and the styrene-based monomer is 20/80 to 30 /.
70, having a molecular weight of 40,000 to 120,000.

If the AN / ST and the molecular weight of the low molecular weight hard copolymer are out of the above ranges, a rubber-reinforced styrene resin composition having a good flow / impact balance cannot be obtained.

The third component of the low molecular weight hard copolymer includes N-phenylmaleimide, maleimide, N-methylmaleimide, N-ethylmaleimide, (p-bromophenyl) maleimidemethacrylate, methylmethacrylate and the like. When these third components are copolymerized, the content ratio in the copolymer is preferably 20% by weight or less.

The rubber-reinforced styrenic resin composition of the present invention contains the bulk copolymer, the graft copolymer and the low molecular weight hard copolymer as described above, and the bulk copolymer: 10-35.
Parts by weight, graft copolymer: 30 to 55 parts by weight and low molecular weight hard copolymer: 10 to 60 parts by weight.

When the proportion of each copolymer is out of the above range, a rubber-reinforced styrene resin composition having a good flow / impact balance cannot be obtained.

The rubber-reinforced styrenic resin composition of the present invention is easily prepared by kneading a bulk copolymer, a graft copolymer and a low molecular weight hard copolymer produced by a conventional method in a predetermined composition. be able to. The kneaded product is pelletized by a conventional method and used as a forming raw material.

[0028]

The rubber-reinforced styrenic resin composition of the present invention comprises a bulk copolymer having a specific structure as a large particle size component, a graft copolymer having a specific structure as a small particle size component, and a low-polymerization composition having a specific structure. A bimodal rubber-reinforced styrenic resin composition containing a rigid polymer having a molecular weight in a predetermined ratio and having a composition within the scope of the present invention has a good flow / impact balance and excellent colorability. Can be realized.

[0029]

EXAMPLES The present invention will be described more specifically with reference to production examples, examples and comparative examples below.

Production Example 1: Synthesis of ABS Bulk Copolymer (Large Particle Diameter Component) Using the rubber species shown in Table 1, bulk polymerization was carried out with the raw material formulation shown in Table 1 to prepare an ABS bulk copolymer: Bulk. -1
~ 5 were prepared.

Polymerization was carried out by a bulk polymerization apparatus composed of three 4-liter fully homogeneous mixing type reactors, and after phase inversion of rubber in the first stage reactor, second stage and third stage. Monomer conversion rate of 85 in reactor
Polymerization was performed up to%, and the residual monomer was removed with a devolatilization device.

The polymerization temperature is as follows: 1st stage: 80 ° C., 2nd stage: 1
20 ° C., 3rd stage: 160 ° C. The rubber particle diameter in the polymer is appropriately controlled by adjusting the amount of chain transfer agent (t-dodecyl mercaptan) and the stirring speed of each reactor to obtain a predetermined rubber particle diameter. did.

[0033]

[Table 1]

Production Example 2: Synthesis of ABS Graft Copolymer (Small Particle Size Component) A stainless steel polymerization tank equipped with a stirrer was charged with the amounts of water and latex shown in Table 2 and heated to 60 ° C., and then Table 2 Fructose, sodium pyrophosphate and ferrous sulfate dissolved in water were added in the proportions shown in. At the same time, CHP shown in Table 2
And styrene, acrylonitrile, TDM mixed solution 2
It was added in series over 70 minutes, and finally emulsion polymerization was completed over 150 minutes. The setting of the polymerization temperature is as follows.

0 to 30 minutes: constant at 60 ° C. 30 to 70 minutes: increase from 60 ° C. to 71 ° C. 70 to 150 minutes: constant at 71 ° C. After polymerization, an antioxidant is added, coagulation is performed with sulfuric acid, and washing is performed. ABS graft copolymer having the SAN molecular weight and the rubber content shown in Table 2 through the steps of dehydration and drying: HRG-1
~ HRG-11 was obtained.

[0036]

[Table 2]

Production Example 3: Synthesis of low-molecular-weight hard copolymer After the inside of an autoclave equipped with a stirrer was sufficiently replaced with nitrogen, the starting materials shown in Table 3 were used to prepare predetermined amounts of monomers, distilled water, and a surfactant. Then, the suspension stabilizer and the organic peroxide were charged, the internal temperature was raised to 80 ° C. with stirring at 350 rpm, and polymerization was carried out at this temperature for 9 hours. Then, the internal temperature was raised to 120 ° C. over 2.5 hours, and the reaction was carried out at this temperature for 2 hours. Monomer conversion is 98 for all samples
Reached over%. The obtained slurry is washed and dried to obtain a low molecular weight hard copolymer: PSAN-1 to PSAN-.
Got 6.

[0038]

[Table 3]

Examples and Comparative Examples ABS bulk copolymer obtained by the above method, ABS
The graft copolymer and the low molecular weight rigid copolymer are shown in Table 4 to
The mixture was mixed with 1.0 parts by weight of N, N'-ethylenebisstearylamide (EBS-wax) in a Banbury mixer in the formulation shown in 10 and then pelletized. The resulting sample was molded at 240 ° C on a 4 ounce injection molding machine.

SSP (kg / cm ² ): It is expressed as the minimum filling pressure when a tensile test piece is molded at 240 ° C. by a 4 ounce injection molding machine manufactured by Nippon Steel Co., Ltd. (It is known that the short shot point is a good representative of the flow characteristics in the actual molding of the material called. Izod impact value (kg-cm / cm): ASTM (D256)
1/8 inch notched Izod, measuring temperature is 23
℃ and -30 ℃ Drop weight impact value (kg-mm): Shimadzu Hydroshot HTM-1
Was used under the following conditions. Hammering speed: 5.0 m / sec Probe: 1/4 "R Sample holder: 1" Φ Measuring temperature: 23 ° C Coloring evaluation: The blend obtained by the Banbury compound is a colorant prepared in advance by a masterbatch. 0.1% of the red or blue pigment below was added to the pellet.
It was blended so as to be contained by weight, and colored pellets were obtained through an extruder. Injection molding it to a thickness of 1/10 ", 5
cm × 5 cm width test piece was prepared and L * was measured with a color difference meter (Nippon Denshoku Industries Co., Ltd. spectroscopic color difference meter (SZ-Σ90)).
And c * were obtained, and the color density was judged from the c * / L * value.
A higher c * / L * indicates a higher color density and better colorability.

Red pigment: Perinone oil-soluble dye Blue pigment: Copper phthalocyanine blue

[0042]

[Table 4]

From Table 4, the following is clear.

That is, comparing the blends Nos. 1 to 4, it is clear that the flow bulk / impact balance is poor in the system in which the rubber particle size of the ABS bulk copolymer is less than 0.5 μm or exceeds 2.5 μm.

The blend No. 5 containing Bulk-5 using SBR shows a good flow / impact balance and has an extremely good color developability.

[0046]

[Table 5]

From Table 5, the following is clear.

That is, comparing Blend Nos. 3 and Nos. 7-9, the flow / impact balance was poor in a system in which the rubber particle size of the ABS graft copolymer was less than 0.06 μm or more than 0.4 μm. it is obvious.

The blend No. 10 containing HRG-5 using SBR shows a good flow / impact balance, and the coloring property is also very good.

[0050]

[Table 6]

Blends No. 3 and Nos. 11 to 1 in Table 6
Comparing 3 shows that the molecular weight of the grafted SAN of the ABS graft copolymer is below the flow /
It is clear that the impact balance deteriorates.

[0052]

[Table 7]

Blends No. 3 and Nos. 14 to 1 in Table 7
By comparing 6 with each other, it is clear that the flow content / impact balance is deteriorated when the rubber content of the ABS graft copolymer is out of the range of the present invention.

[0054]

[Table 8]

The following is clear from Table 8.

That is, the blend Nos. 3, 17, and 18 are
Since the AN / ST ratio is within the range of the present invention, both are excellent in flow / impact balance.

By comparing the blends No. 3 and Nos. 19 and 20, it can be seen that the flow / impact balance becomes poor when the molecular weight of the low molecular weight hard copolymer is less than 40,000 or more than 120,000.

From Blend No. 21, N-PMI, α
-It is clear that a good flow / impact balance is exhibited even when a low molecular weight high heat rigid such as MST is used. In this system, good heat resistance is expected at the same time.

[0059]

[Table 9]

From Table 9, it is clear that the blends having the composition ratio within the range of the present invention show a good flow / impact balance, while the blends outside the range of the present invention are inferior in the flow / impact balance. .

[0061]

[Table 10]

The following is clear from Table 10.

That is, it can be seen that the blends No. 8 and No. 3 are superior to the flow / impact balance of the monomodal ABS-1 and ABS-2, and are extremely good in colorability. Further, it can be seen that both blends have physical properties that cannot be conventionally designed with monomodal ABS, and are excellent in flow / impact balance and colorability even when compared with high flow HIPS.

[0064]

As described in detail above, according to the rubber-reinforced styrene resin composition of the present invention, the rubber-reinforced rubber composition is excellent in flow / impact balance, has good moldability and impact strength, and is also excellent in colorability. A styrene resin composition is provided.

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[Procedure amendment]

[Submission date] July 6, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0030

[Correction method] Change

[Correction content]

Production Example 1: Synthesis of ABS Bulk Copolymer (Large Particle Size Component) Using the rubber species shown in Table 1, bulk polymerization was performed and the results are shown in Table 1.
ABS bulk copolymer having composition and particle size : Bulk-
1-5 were prepared.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0033

[Correction method] Change

[Correction content]

[0033]

[Table 1]

Claims (1)

[Claims] 1. A bulk copolymer of a styrene-based monomer, an unsaturated nitrile-based monomer and a rubber-like polymer, wherein the rubber-like polymer has a volume average particle size of 0.5 to 2.5 μm. Bulk copolymer having a rubber polymer content of 10 to 15% by weight: 10 to 35 parts by weight An emulsion polymerization graft copolymer of a styrene monomer, an unsaturated nitrile monomer and a rubber polymer. Then, the volume average particle diameter of the rubber-like polymer is 0.06 to 0.4 μm, the content of the rubber-like polymer is 35 to 50% by weight, and the styrene-based monomer and the unsaturated nitrile-based monomer are free. A graft copolymer having a weight average molecular weight of 50,000 to 100,000 and a weight average molecular weight of the grafted styrene-based monomer and unsaturated nitrile-based monomer of 60,000 to 120,000. 30-55 parts by weight and styrene type A low molecular weight hard copolymer obtained by copolymerizing a monomer and an unsaturated nitrile monomer, wherein the weight ratio of the unsaturated nitrile monomer and the styrene monomer is unsaturated nitrile. System monomer / styrene system monomer = 15 / 85-3
0/70, the weight average molecular weight of the hard copolymer is 40,000
~ 120,000 low molecular weight rigid copolymers: 10-6
A bimodal rubber-reinforced styrene-based resin composition having a good colorability and an excellent flowability / impact resistance balance, which is characterized by containing 0 part by weight.