JP3508357B2 - Impact resistant reinforced material and impact resistant reinforced polystyrene - 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-based resin impact-resistant reinforcing material and impact-resistant reinforced polystyrene reinforced with the impact-resistant reinforcing material.

[0002]

2. Description of the Related Art Polystyrene has excellent transparency and appearance, and has high tensile strength and rigidity, so that it can be used for food containers, stationery,
It is widely used in fields such as sundries, but has the drawback of low impact resistance.

Impact-resistant polystyrene obtained by reinforcing this polystyrene with a rubber component to improve impact resistance is used in household electric appliances, mechanical parts, and other broader fields.

As the impact-resistant polystyrene, a method of blending polystyrene with a rubber-like polymer such as polybutadiene or styrene-butadiene copolymer was proposed in the early stage of its development. There is a drawback that the interface with the resin phase has a poor affinity and sufficient impact resistance cannot be obtained. For this reason, impact-resistant polystyrene is currently a bulk polymerization method in which an uncrosslinked rubbery polymer is dissolved in a styrene monomer and polymerized as it is, or a bulk suspension weight method in which suspension polymerization is performed after preliminary polymerization is performed. Manufactured legally.

[0005]

The conventional impact-resistant polystyrene in which a rubber component is blended with polystyrene to improve its impact resistance has the following problems in its characteristics and manufacturing method.

Since the solubility of the rubber-like polymer in the styrene monomer is as low as about 10%, the rubber content cannot be increased any further. Therefore, it is not possible to manufacture a product having sufficiently high impact resistance.

Since the rubber component is dissolved in the styrene monomer and polymerized, the rubber phase containing a large amount of polystyrene is dispersed as particles in the produced polymer. The polystyrene contained in the rubber phase does not exhibit the properties of polystyrene, and the particle size of the rubber phase is 1.
Since it is as large as 0 to 3.0 μm, the rigidity is significantly reduced as compared with polystyrene, although the rubber content is small.

In order to change the brand, it is necessary to change the polymerization prescription, but it takes a long time to change the brand in this polymerization stage, and the amount of extraneous products is increased. Therefore, the types of brands are naturally limited, and it is difficult to manufacture brands with various physical property balances.

Conventionally, the rubber component for reinforcing polystyrene is polybutadiene or styrene.
Since a conjugated diene rubber such as a butadiene copolymer is used, it also has a drawback that weather resistance is poor.

The present invention solves the above-mentioned problems of the prior art, and is capable of producing an impact resistant styrene resin having excellent rigidity or high impact resistance which cannot be obtained by the prior art. And impact resistant reinforced polystyrene reinforced with the impact resistant reinforcing material.

[0011]

The impact resistant reinforcing material of the present invention has a gel content of 90% or less and an average particle size of 0.25 to 0.
An impact-resistant reinforcing material obtained by graft-polymerizing 30 to 80 parts by weight (in terms of solid content) of a rubber-like polymer latex of 55 μm and 70 to 20 parts by weight of a vinyl cyanide compound and an aromatic vinyl compound, The ratio of the vinyl cyanide compound to the total amount of the vinyl cyanide compound and the aromatic vinyl compound is 3 to 18% by weight, and prior to the graft polymerization, the vinyl cyanide compound and the aromatic vinyl compound are preliminarily added to the rubber-like polymer. It is characterized in that it is obtained by impregnating the particles and then performing graft polymerization using an oil-soluble polymerization initiator and a water-soluble polymerization initiator as a polymerization initiator.

Using a rubber-like polymer latex having a specific gel content and an average particle size limited by the present invention, a vinyl cyanide compound and an aromatic vinyl compound are preliminarily contained in the rubber-like polymer particles in a specific ratio. The impact-resistant reinforcement material obtained by graft-polymerizing with an oil-soluble polymerization initiator and a water-soluble polymerization initiator after being impregnated with is excellent in impact resistance and rigidity. A polystyrene resin can be manufactured.

That is, the amount of polystyrene contained in the rubber particles in the impact resistant reinforcing material according to the present invention is smaller than that of the impact resistant polystyrene produced by the prior art, and the particle diameters of the dispersed rubber phases are compared. Because of its small size, it is possible to obtain an impact-resistant polystyrene-based resin having a rigidity superior to that of the impact-resistant polystyrene produced by the conventional technique.

In the present invention, the rubber-like polymer is
One or more selected from the group consisting of polybutadiene, styrene / butadiene copolymer, ethylene / α-olefin copolymer and ethylene / α-olefin / non-conjugated diene copolymer can be preferably used.

With such an impact-resistant reinforcing material, polystyrene and / or impact-resistant polystyrene are melt-mixed at an arbitrary ratio to obtain various impact-resistant reinforcing materials having a balance of impact resistance and rigidity. Polystyrene can be easily manufactured.

That is, since it is mechanical melt mixing, the mixing ratio of polystyrene or impact-resistant polystyrene and impact-resistant reinforcing material can be easily changed, whereby impact-resistant styrenic resin having various physical property balances. Can be easily obtained. Further, since the amount of the rubber component can be easily increased, it is possible to easily obtain an impact strength higher than that possessed by the impact-resistant polystyrene produced by the conventional technique.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below.

In the present invention, the rubber-like polymer latex has a gel content of 90% or less, and the average particle diameter of the rubber-like polymer particles is 0.25 to 0.55 μm, preferably 0.3 to
The one with 0.4 μm is used. If the gel content of the rubber-like polymer latex exceeds 90%, a sufficient impact resistance reinforcing effect cannot be obtained. Further, when the average particle size of the rubber-like polymer particles is less than 0.25 μm, sufficient impact resistance reinforcing effect cannot be obtained, and when it exceeds 0.55 μm, stable latex cannot be obtained.

As the rubber-like polymer, polybutadiene,
A latex such as a styrene / butadiene copolymer, an acrylonitrile / butadiene copolymer, an ethylene / α-olefin copolymer, an ethylene / α-olefin / non-conjugated diene copolymer can be used. As a rubbery polymer, ethylene / α-olefin copolymer or ethylene /
When the α-olefin / non-conjugated diene copolymer is used, an impact-resistant styrene-based resin having excellent weather resistance can be obtained.

In the present invention, 30 to 80 parts by weight (as solid content) of such a rubber-like polymer latex is added to a total of 70 to 2 of a vinyl cyanide compound and an aromatic vinyl compound.
Graft-polymerize 0 parts by weight. If the proportion of the rubber-like polymer latex is less than the above range, the rubber content is too small to be used as an impact resistance reinforcing material, and if it exceeds the above range, a sufficient impact resistance reinforcing effect cannot be obtained. .
The preferred graft polymerization ratio is 60 to 30 parts by weight of vinyl cyanide compound and aromatic vinyl compound with respect to 40 to 70 parts by weight of rubber-like polymer latex (calculated as solid content).

In the present invention, a rubber-like polymer is graft-polymerized with an aromatic vinyl compound and a small amount of a vinyl cyanide compound. That is, the amount of the vinyl cyanide compound added is 3 to 18% by weight, preferably 5 to 15% by weight, based on the total amount of the aromatic vinyl compound and the vinyl cyanide compound. If the proportion of the vinyl cyanide compound is out of this range, a sufficient impact resistance reinforcing effect cannot be obtained.

As the aromatic vinyl compound, styrene, α-methylstyrene, o-methylstyrene, m-
Methylstyrene, p-methylstyrene, dimethylstyrene, t-butylstyrene, chlorostyrene, dichlorostyrene, bromostyrene, dibromostyrene and the like are exemplified, and one or more of these can be used,
Particularly preferred is styrene.

As the vinyl cyanide compound, acrylonitrile, methacrylonitrile and the like are exemplified, and one or more of these can be used, but acrylonitrile is particularly preferable.

In the present invention, an oil-soluble polymerization initiator and a water-soluble polymerization initiator are used in combination as a polymerization initiator for graft polymerization of a rubber-like polymer with an aromatic vinyl compound and a vinyl cyanide compound. Specifically, an oil-soluble polymerization initiator is used in the first half of the polymerization, and a water-soluble polymerization initiator is added in the second half to complete the polymerization. When only the oil-soluble polymerization initiator is used as the polymerization initiator, the rigidity is lowered, and when only the water-soluble polymerization initiator is used, the impact resistance reinforcing effect cannot be obtained.

Examples of the oil-soluble polymerization initiator include benzoyl peroxide, lauroyl peroxide, stearoyl peroxide, di-2-ethylhexyl peroxydicarbonate, di-isopropyl peroxy dicarbonate, t-butyl peroxy neodecaneate, One or more selected from organic peroxides represented by t-butylperoxypivalate and t-hexylperoxypivalate can be used.

As the water-soluble polymerization initiator, one or more selected from inorganic peroxides represented by ammonium persulfate, potassium persulfate and the like can be used.

As the oil-soluble polymerization initiator and the water-soluble polymerization initiator, the oil-soluble polymerization initiator is 0.5 to 1.5% by weight based on the total amount of the vinyl compound, and the water-soluble polymerization initiator is the vinyl compound. It is preferably used in a proportion of 0.3 to 0.9% by weight with respect to the total amount of.

In the present invention, the aromatic vinyl compound and the vinyl cyanide compound are impregnated (occluded) into the rubber-like polymer particles prior to the graft polymerization. Therefore, the rubber-like polymer particles are impregnated with the aromatic vinyl compound and the vinyl cyanide compound, and then the polymerization initiator is added to carry out the polymerization. The impregnation time is preferably 30 minutes to 90 minutes. If the impregnation time is less than 30 minutes, a sufficient impact resistance reinforcing effect cannot be obtained, and if it exceeds 90 minutes, a larger impact resistance reinforcing effect cannot be obtained, which is not economical.

The impregnation treatment is preferably carried out at 40 to 70 ° C.

The impact-resistant reinforcing material of the present invention comprises a specific rubber-like polymer latex and an aromatic vinyl compound and a vinyl cyanide compound in a specific ratio, and after the above-mentioned impregnation treatment, oil-soluble polymerization. It can be easily produced by an ordinary graft polymerization technique, except that an initiator is added and then a water-soluble polymerization initiator is added.

The impact-reinforced polystyrene of the present invention is obtained by using such impact-resistant reinforcement material of the present invention as polystyrene and / or
Alternatively, it can be easily produced simply by mechanically melt-mixing with impact-resistant polystyrene.

As described above, since the mechanical melt mixing is employed, the impact-resistant reinforcing material of the present invention can be mixed with polystyrene and / or impact-resistant polystyrene at an arbitrary ratio. Polystyrene or impact resistant polystyrene 9 to 10 to 40 parts by weight of impact resistant reinforcing material
It is preferable to mix at a ratio of 0 to 60 parts by weight.

[0033]

EXAMPLES The present invention will be described more specifically with reference to Examples and Comparative Examples below. In addition, below, each measuring method is as follows.

Gel content of rubbery polymer: After coagulation and drying of latex, polybutadiene and styrene / butadiene copolymer are added to toluene (normal temperature), ethylene / α-olefin copolymer and ethylene / α- Toluene (6 for olefin / non-conjugated diene copolymer)
Each of them was immersed in 0 ° C.) for 24 hours, and then filtered through a 200-mesh wire net to obtain the insoluble matter ratio (wt%), which was taken as the gel content.

Average particle size of rubber-like polymer latex : Measured by a creaming method using sodium alginate.

Izod condition strength : ASTM D256 notched, test piece thickness = 1/4 inch Bending elastic modulus : ASTM D790, test piece thickness = 1/8 inch Further, in Examples and Comparative Examples, blend with a graft polymer. The polystyrene used in was prepared by the general suspension polymerization method as follows.

39 kg of pure water, 130 g of tricalcium phosphate, 1.5 g of sodium dodecylbenzene sulfonate, 37 g of styrene were placed in a stainless steel reactor (internal volume 100 L) equipped with a stirrer, a thermometer and a reflux condenser.
g, t-dodecyl mercaptan 122 g, benzoyl peroxide 111 g, and t-butyl peroxybenzoate 13 g were charged, and the mixture was further heated at 85 ° C. for 7.5 hours and further 12 hours.
The temperature was raised to 0 ° C. and polymerization was performed for 2.5 hours. Then, the outlet valve of the reflux condenser was switched, and 5 kg of the condensate was discharged to the outside of the reactor for 2 hours at 120 ° C. to remove unreacted styrene. After cooling, the contents were extracted, acid decomposed, washed, dehydrated and dried to obtain polystyrene beads. The characteristics of the obtained polystyrene are the melt flow rate (JIS
K7210, 200 ° C / 5kg load) is 9.6kg /
After 10 minutes, the residual styrene monomer content was 1,700 ppm.

Examples 1-5, Comparative Examples 1-5 50 parts by weight of polybutadiene latex having a gel content of 82.1% and an average particle diameter of 0.33 μm (as solid content), 44.0 parts by weight of styrene, and 6. acrylonitrile. 0 parts by weight,
0.1 parts by weight of t-dodecyl mercaptan, 1.0 parts by weight of sodium rosinate, 0.02 parts by weight of sodium hydroxide, and 150 parts by weight of pure water were charged in a reactor, heated to 60 ° C. and stirred for 60 minutes. Then, the temperature was raised to 75 ° C. Then
After 0.3 part by weight of t-hexyl peroxypivalate was added and polymerization was performed for 2 hours, 0.2 parts by weight of potassium persulfate was added and polymerization was further performed for 2 hours. After adding an antioxidant to the obtained graft polymer latex, it was poured into an aqueous calcium chloride solution to coagulate, washed, dehydrated and dried to obtain a graft polymer. The ratio of acrylonitrile to the total amount of styrene and acrylonitrile in this example was 12% by weight.

The obtained graft polymer was mixed with polystyrene or impact-resistant polystyrene in the proportions shown in Table 1, 0.5 part by weight of calcium stearate was added, and the mixture was kneaded with a Banbury mixer to be pelletized. The obtained pellets were injected into an injection molding machine ("J75E-P" manufactured by Japan Steel Works, Ltd.).
A test piece was molded using a mold and the physical properties were measured. Table 1 shows the measurement results of physical properties.

For comparison, the polystyrene prepared this time, the commercially available polystyrene, and the commercially available impact-resistant polystyrene according to the prior art were similarly injection-molded to prepare test pieces, and the physical properties were measured. The results are also shown in Table 1. .

As is clear from Table 1, the impact resistant reinforced polystyrene obtained by blending the impact resistant reinforcing material according to the present invention has an Izod impact strength equivalent to that of the impact resistant polystyrene obtained by the prior art. And has a flexural modulus (stiffness) superior to that of the impact-resistant polystyrene according to the prior art. Further, by increasing the mixing ratio of the impact resistant reinforcing material according to the present invention, it is possible to obtain impact resistant reinforced polystyrene having a high Izod impact strength which cannot be obtained by the conventional impact resistant polystyrene.

It can also be seen that higher impact Izod impact strength can be obtained by blending the impact resistant reinforcement of the present invention with the impact resistant polystyrene of the prior art.

[0043]

[Table 1]

Examples 6 to 10 and Comparative Example 6 Table 2 shows the proportion (% by weight) of acrylonitrile with respect to the total amount of styrene and acrylonitrile by setting the blending amount (parts by weight) of acrylonitrile to the value shown in Table 2. Test pieces were prepared and physical properties were measured in the same manner as in Example 1 except that the ratio was used, and the results are shown in Table 2.

From Table 2, it can be seen that if the addition amount of acrylonitrile is out of the range of the present invention, an impact resistant reinforcing material having a sufficient impact resistance reinforcing effect cannot be obtained.

[0046]

[Table 2]

Examples 11 to 14 and Comparative Examples 7 to 9 Test pieces were prepared in the same manner as in Example 1 except that the polybutadiene latices having the gel contents and average particle sizes shown in Table 3 were used. The physical properties were measured, and the results are shown in Table 3.
It was shown to.

From Table 3, when the gel content of polybutadiene exceeds 90%, or when the particle size of polybutadiene is out of the lower limit of the range of the present invention, the impact resistance reinforcing effect is not sufficient, and It can be seen that when the particle size exceeds the upper limit of the present invention, a stable graft polymer latex cannot be obtained.

[0049]

[Table 3]

Examples 15 and 16, Comparative Example 10 The blending amount (parts by weight) of polybutadiene is set to the value shown in Table 5, and the mixing ratio of the graft polymer and polystyrene is shown in Table 5.
The test pieces were prepared in the same manner as in Example 1 with the proportions shown in Table 1, and the measurement results of physical properties are shown in Table 5.

As the addition amount of polybutadiene was changed, the addition amounts of styrene and acrylonitrile differed from those of Example 1 as shown in Table 4, and the polymerization was initiated with the addition amounts of styrene and acrylonitrile. Agent,
The addition amount of t-dodecyl mercaptan was different from that in Example 1 as shown in Table 4. Other polymerization conditions are in Example 1
Is the same as. However, the gel content of the polybutadiene latex is slightly different.

From Table 5, it can be seen that the impact resistance reinforcing effect is not sufficient when the amount of polybutadiene added deviates from the upper limit of the range of the present invention.

[0053]

[Table 4]

[0054]

[Table 5]

Comparative Examples 11 and 12 Implementations were repeated except that an oil-soluble initiator or a water-soluble polymerization initiator was used alone as a polymerization initiator in the compounding amounts shown in Table 6 and the polymerization temperature and the polymerization time were adjusted accordingly. Test pieces were prepared in the same manner as in Example 1, and the measurement results of physical properties are shown in Table 6.

From Table 6, it can be seen that the oil-soluble polymerization initiator alone has a low rigidity, and the water-soluble polymerization initiator alone cannot obtain the impact resistance reinforcing effect.

[0057]

[Table 6]

Examples 17 and 18, Comparative Example 13 Example 1 was repeated except that the impregnation time was changed to that shown in Table 7.
Test pieces were prepared in the same manner as in, and the measurement results of physical properties are shown in Table 7.

From Table 7, it can be seen that the impact resistance reinforcing effect can be obtained by the immersion treatment for 30 minutes, but the higher impact resistance reinforcing effect cannot be obtained even after 90 minutes.

[0060]

[Table 7]

Examples 19-21 As shown in Table 8, tests were conducted in the same manner as in Example 1 except that a rubbery polymer other than polybutadiene having a gel content and an average particle diameter within the scope of the present invention was used. Make a piece,
The measurement results of physical properties are shown in Table 8.

From Table 8, it can be seen that the use of the rubber-like polymer within the scope of the present invention makes it possible to obtain an impact resistant reinforcing material having an excellent impact resistance reinforcing effect.

[0063]

[Table 8]

[0064]

As described in detail above, according to the impact resistant reinforcing material of the present invention, an impact resistant styrenic resin having significantly higher rigidity than the impact resistant polystyrene produced by the prior art can be produced. can do. In addition, according to the impact-resistant reinforced polystyrene of the present invention, it is possible to easily change the mixing ratio of the impact-resistant reinforcing material and the styrene resin by mechanical melt mixing to achieve various balances of impact resistance and rigidity. It is possible to easily produce the impact-resistant styrene-based resin.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI C08L 55/02 C08L 55/02 (56) References JP-A-9-136926 (JP, A) JP-A-5-295051 (JP , A) JP-A-4-80221 (JP, A) JP-A-3-177405 (JP, A) JP-A-2-261813 (JP, A) JP-A-60-15415 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08F 279/04 C08F 255/02-255/06 C08L 25/00-25/18 C08L 51/04-51/06 C08L 55/02

Claims (3)

(57) [Claims] 1. A gel content of 90% or less and an average particle size of 0.
25-0.55 μm rubber-like polymer latex 30-8
An impact resistance reinforcing material obtained by graft-polymerizing 0 to 20 parts by weight (in terms of solid content) of a vinyl cyanide compound and 70 to 20 parts by weight of an aromatic vinyl compound, which is a vinyl cyanide compound and an aromatic vinyl compound. The ratio of the vinyl cyanide compound to the total amount of
That is, prior to the graft polymerization, after the vinyl cyanide compound and the aromatic vinyl compound are impregnated in the rubber-like polymer particles, an oil-soluble polymerization initiator and a water-soluble polymerization initiator are used as a polymerization initiator. An impact resistant reinforcing material obtained by graft polymerization. 2. The rubbery polymer according to claim 1, which is selected from the group consisting of polybutadiene, styrene / butadiene copolymer, ethylene / α-olefin copolymer and ethylene / α-olefin / non-conjugated diene copolymer. 1 chosen
Impact-resistant reinforcing material of one kind or two or more kinds. 3. Impact-resistant reinforced polystyrene obtained by melt-mixing the impact-resistant reinforcement material according to claim 1 and polystyrene and / or impact-resistant polystyrene.