JPS5915145B2 - Impact resistant thermoplastic resin composition - Google Patents

Description

Detailed Description of the Invention 10 The present invention relates to an impact-resistant thermoplastic resin composition, and more specifically to improvements in so-called ABS resins that have improved moldability, processability, product appearance, mechanical properties, etc. The present invention relates to an impact-resistant thermoplastic resin composition.

15 As is well known, ABS resin is an impact-resistant thermoplastic resin with excellent moldability in injection molding, extrusion molding, etc., and is therefore widely used as a molding material.

However, in recent years, consumers have been increasing the size of molded products and
The usage situation is becoming more complex, such as thinner walls, and there are strong demands for various qualities depending on the purpose of use. We need to be well prepared.

25 Conventional methods have limitations in meeting these requirements.

That is, conventional methods involve changing the rubber particle diameter of the rubber phase, the graft structure, the composition of the matrix resin phase, the molecular weight, the content of the rubbery component 30 as the ABS resin, etc. in order to improve the various properties of the ABS resin. or stabilizers,
The desired quality balance has been achieved by adding lubricants, plasticizers, etc., but these methods alone are not sufficient to maintain the level of various properties above a certain level and improve the desired properties. However, there were only 35. for example,
Increasing the rubber component as a means to improve impact resistance sacrifices moldability and rigidity, while adding large amounts of lubricants and plasticizers for the purpose of improving shapeability may result in decreased heat resistance, plate-out, etc. A satisfactory solution could not be reached because of the following problems.

In addition, when ABS resin is generally injection molded, when the resin is filled into a mold cavity through a narrow gate, a phenomenon called flow marks, which is a defective appearance, tends to occur near the gate, resulting in poor product quality. It may significantly reduce the product value. In other words, during molding, especially when using an injection molding machine, if the resin phase has a low molecular weight, it is easy to obtain large products and thin products due to the resin's good fluidity. It may not be strong enough to withstand practical use as a product.

On the other hand, when high molecular weight resin is used, it has poor moldability and is difficult to mold into the desired product, so the resin temperature and injection pressure are increased during injection molding, resulting in thermal discoloration of the resin. It has disadvantages in that it is prone to thermal deterioration, and is also prone to deformation of the product due to residual strain inside the product due to high-pressure molding, and stress cracks.

In order to improve these shortcomings, the Special Publication No. 53-4862
The publication proposes a method of blending a copolymer resin of a high molecular weight monovinyl aromatic monomer and an unsaturated nitrile monomer and a low molecular weight copolymer resin mentioned above into an ABS resin. This method aims at covering the drawbacks of both low molecular weight copolymers and high molecular weight copolymers by blending them together. Although moldability is improved to some extent by this method, the appearance and strength are not satisfactory. The inventors of the present invention have conducted intensive studies to develop an impact-resistant thermoplastic resin composition that has well-balanced moldability, mechanical properties, etc. and improved product appearance, and as a result, they have arrived at the present invention, which is highly effective. .

That is, the present invention provides a graft polymer obtained by graft polymerizing acrylonitrile and one or more of styrene, α-methylstyrene, and methyl methacrylate to a rubber component whose main component is polybutadiene, and the rubber component content is reduced. More than 50% by weight and less than 65% by weight (
4) and a copolymer (B) of acrylonitrile with one or more of styrene, α-methylstyrene 4, and methyl methacrylate, and the rubbery substance in the resin composition The content is 3-45% by weight, (
The grafting ratio of 4) is 25 to 70%, the weight ratio of CA)/(B) is 5/95 to 80/20, and (B) is a low molecular weight copolymer (B-1) and a high molecular weight copolymer. The intrinsic viscosity of the methyl ethyl ketone solutions of (B-1) and (B-2) at 30°C is (B-1) = 0.
．． 4 to 0.6, (B-2) = 0.6 to 1.1, and the weight ratio of (B-1)/(B-2) is 90/10 to
The present invention provides an impact-resistant thermoplastic resin composition characterized by having a hardness of 30/70. The graft polymer A of the resin targeted by the present invention is obtained by graft polymerizing one or more of styrene, d-methylstyrene, and methyl methacrylate and acrylonitrile to a rubbery polymer containing butadiene as a main component. Among the graft polymers, styrene alone, styrene/α-methylene, styrene/methyl methacrylate, and styrene/α-methylstyrene/methyl are preferred among one or more of styrene, α-methylstyrene, and methyl methacrylate. It is methacrylate.

In addition, in the graft polymer, some of these monomers may be replaced with other monomers in order to improve heat resistance, chemical resistance, and the like. Further, in the graft polymer, a rubbery polymer containing butadiene as a main component, such as a butadiene-styrene copolymer, a butadiene-acrylonitrile copolymer, etc. other than polybutadiene, may be used as a rubbery component.

The content of these rubbery components in the graft polymer is more than 50% by weight and less than 65% by weight, and is obtained by coagulating and drying a latex polymerized in the form of an emulsion liquid. The grafting ratio of the graft polymer (4) is 25 to 70%.
If the grafting ratio is less than 25%, the impact resistance will be poor, and if it exceeds 70%, the impact resistance will not only be saturated but also the fluidity will deteriorate and the moldability will decrease. The copolymer resin Q3) in the present invention refers to one or more of styrene, d-methylstyrene, and methylstyrene, preferably 65 to
80% by weight and preferably 20-35% of acrylonitrile
% by weight.

The weight ratio of the graft polymer and the copolymer (8) is (A)/old)=5/95 to 80/20. (A
) If the A ratio is less than 5/95, the impact resistance will be poor, and if the ratio (B) exceeds 80/20, the appearance of the molded product will be poor and the fluidity will be poor. The copolymer (8) of the present invention is a mixture of a low molecular weight copolymer (B-1) and a high molecular weight copolymer (B-2). The intrinsic viscosity ω of the methyl ethyl ketone solution of these copolymers at 30°C is 0.4 to 0, respectively.
．． 6. The ω difference between copolymers (B1) and (B-2) used is in the range of 0.6 to 1.1, and a mixture of copolymers (B1) and (B-2) of 0.1 to 0.6 is better for improving the appearance. Effective. Here, the weight ratio of copolymers (B-1) and (B-2) is (B-1)
:(B-2)-90:10 to 30:70. The reason is as follows. (1) If only the high molecular weight copolymer or the mixing ratio of the high molecular weight copolymer exceeds the above range, the mechanical strength will be improved but the moldability will be significantly reduced. (2) Furthermore, when the high molecular weight polymer is below the above ratio, the characteristics of the present invention are not fully satisfied.

The method for producing these copolymers may be any currently known method such as suspension polymerization, bulk polymerization, or emulsion polymerization. -2
) can be mixed using generally known methods such as an extruder, heated roll, pen shell mixer, etc. The rubber component in the final impact-resistant thermoplastic resin is blended in a range of 3 to 45% by weight, but the quality balance as an ABS resin, such as rigidity - impact resistance, impact resistance. From the viewpoint of properties, heat resistance, etc., it is 6 to 30% by weight.
Preferably.

Further, it is also possible to add a stabilizer, a lubricant, an antistatic agent, etc. as necessary. The impact-resistant thermoplastic resin obtained by the present invention has excellent moldability and mechanical properties,
Furthermore, the resin composition has an improved appearance due to the flow mark improvement effect.

The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples.

Examples 1-4, Comparative Examples 1-4 (1) Graft polymer (4) A graft polymer was obtained by emulsion polymerization using the following formulation.

All amounts shown are parts by weight. [Preparation composition] Styrene, acrylonitrile, and T-DM were mixed in advance, and 10 parts of A were placed in a reactor containing polybutadiene latex, potassium persulfate, potassium oleate, and pure water.
The mixture was added at a rate of 1 hour and reacted with stirring.

The polymerization rate was 98%. The graft copolymer latex thus obtained was coagulated in a sulfuric acid hot water bath, washed with water and dried to obtain a graft polymer powder.

Moreover, the grafting rate of the graft polymer was 60%. In addition, the grafting rate was measured by the following method.

After drying the above powder under reduced pressure, 1.0gr was accurately weighed, 100cc of acetone was added, and the mixture was left to dissolve at room temperature for one week. After dissolution, insoluble matter is separated by centrifugation, dried under reduced pressure, and weighed.
Calculation> (2) Copolymer Resin B) The following charge composition was charged into a reactor and heated to 110°C over 2 hours with stirring, followed by stripping at 130°C for 0.5 hour.

The obtained beads were washed with water and dried before use. Here T-DM
The relationship between the amount of addition and the intrinsic viscosity ω of the obtained copolymer is shown in Table-
1? It was hot.

(3) Evaluation The graft polymer powder obtained in (1) above and the above ※※(
Using the copolymer beads obtained in 2), the rubbery component is
It was blended so that it was 0% by weight.

At this time, the mixing ratio of AS・1 and AS・2 is 90:10~3
Blended at 0:70. Furthermore, 1 part by weight of ethylene bisstearamide was added and mixed uniformly with a pen shell mixer, and then pelletized with an extruder to prepare a sample for evaluation. The pellets were used to evaluate the following items.

The results are shown in Table-2. From Table 2, the following can be said.

The product of the present invention has an excellent balance between mechanical strength and fluidity, and has significantly improved flow marks.

Example 5, Comparative Examples 5 to 9 (1) Graft copolymer (A) Same as used in Examples 1-4.

(2) Copolymer resin (B) The following formulation was charged into a reactor and 11
The temperature was raised to 0°C, and then stripping was performed at 130°C for 0.5 hour.

The obtained beads were washed with water and dried before use. [Preparation recipe (parts by weight)] Table 3 shows the relationship between the added T-DM and [η] of the obtained copolymer resin.

(3) In the same manner as Evaluation Examples 1 to 4, the graft copolymer and copolymer resin were mixed so that the rubbery component was 20% by weight, and 1 part by weight of ethylene bisstearamide was added to form a pen shell. After mixing with a mixer, the mixture was pelletized with an extruder.

The measurement results for the pellets are shown in Table 4. From the results in Table 4, the product of the present invention has a well-balanced mechanical strength and fluidity, but when blended with a material that has a lower molecular weight than general AS, such as AS-3, the chemical properties deteriorate. Therefore, especially when painting a molded product, it has defects such as crazing and cracks.

Examples 6-9, Comparative Examples 10-12 (1) Graft copolymer A A graft polymer was obtained by emulsion polymerization using the following formulation.

Styrene, acrylonitrile, and T-DM were mixed in advance and added to a reactor containing PBD latex, potassium persulfate, sodium laurate, and pure water at a rate of 10 parts/hour, and reacted with stirring. .

After the reaction was completed, the polymerization rate was measured and found to be 97%.

To the graft polymer latex obtained here, 5 parts by weight of an aqueous slurry (slurry concentration 42% by weight) of fine powder of ethylene bisstearamide (average particle diameter of approximately 10μ) was added to the graft polymer, stirred, and mixed with sulfuric acid. The mixture was coagulated in a hot water bath, washed with water, and dried to obtain a graft polymer powder. The grafting rate of the graft polymer was 41%. ). ) Copolymer resin (B) A copolymer was obtained in the same manner as in Examples 1 to 4 using the following formulation.

[Preparation recipe (weight parts)]

In the copolymer (AS-6) obtained here, [a is 0.
It was 66.

S) Evaluation AS-6 obtained above and AS- obtained in Examples 1 to 4
1. AS-2 and a graft polymer with a rubbery content of 60% by weight were blended so that the rubbery content was 10% by weight and pelletized.

The blend ratio of AS-1, AS-2 and AS-6 during blending and the measurement results of pellets are shown in Table 5.
Table 5 is based on a general AS [A level product (AS・1...(G)-0.52), and a higher ω AS-6 (0.66). AS-2(
This is the result of using a blend of 0.81).
The 1-flow mark improvement effect is remarkable compared to when each AS is used alone.

It can be said that the resin composition has an excellent balance of two physical properties, especially the balance of impact strength and fluidity.

Examples 10 to 12, Comparative Examples 13 to 15 Graft polymers were obtained in the same manner as Examples 1 to 4 except that the charging ratios of polybutadiene, styrene, and acrylonitrile were changed.

Claims (1)

[Claims] 1 A graft polymer obtained by graft polymerizing acrylonitrile and one or more of styrene, α-methylstyrene, and methyl methacrylate to a rubbery component whose main component is polybutadiene, and whose rubbery content exceeds 50% by weight. 65% by weight or less (A), styrene,
A resin composition comprising a copolymer (B) of one or more of α-methylstyrene and methyl methacrylate and acrylonitrile, the resin composition having a rubber content of 3 to 45% by weight. %, the grafting rate of (A) is 25
~70% by weight, weight ratio of (A)/(B) ~5/95
80/20, and (B) is a low molecular weight copolymer (B-1
) and a high molecular weight copolymer (B-2), (B-1
) and (B-2), the intrinsic viscosities at 30°C of methyl ethyl ketone solutions are (B-1) = 0.4 to 0.6 and (B
-2)=0.6 to 1.1, and (B-1)/(
An impact-resistant thermoplastic resin composition characterized in that the weight ratio of B-2) is from 90/10 to 30/70.