JPS6234069B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a thermoplastic resin composition that has excellent moldability, impact resistance, and local fracture resistance, and more specifically, the present invention relates to a thermoplastic resin composition that has improved moldability by reducing the amount of rubbery components and lowering the molecular weight of the resinous components. Acrylonitrile-butadiene-styrene resin (hereinafter referred to as
The present invention relates to a thermoplastic resin composition with good impact resistance, which is suitable for manufacturing thin-walled, large-sized molded products with complex shapes, by adding a very small amount of a certain compound to ABS resin (abbreviated as ABS resin). In recent years, the molding industry has been making molded products thinner, larger, and have a larger number of molded parts, with the goal of streamlining things such as saving resources and reducing production costs.Therefore, there is a strong demand for improved moldability of resins. ing. In general, reducing the amount of rubbery components and lowering the molecular weight of resinous components are particularly effective means of improving the moldability of ABS resin, but if the amount of rubbery components is too small or the molecular weight of the resinous components is too low
In order to impair impact resistance, which is one of the most important properties of ABS resin, ordinary ABS resin has a rubber component content of 15 to 25% by weight, and the resin component [η] (in methyl ethyl ketone, 30°C (measured by ) exceeds 0.47, especially resins with a value of 0.5 or more are used. When the [η] of the resin component reaches around 0.47, the effect of adding the rubber component decreases rapidly, resulting in an ABS resin that not only has poor impact resistance but also a decrease in mechanical strength, resulting in poor performance in both properties. Because it is extremely difficult to maintain a high level of [η], ABS resins with [η] of 0.47 or less have hardly been studied. If [η] of the resin component can be reduced to 0.47 or less without impairing the characteristics of ABS resin, the molding cycle can be shortened by lowering the molding temperature, the molding machine can be made smaller by lowering the injection pressure, It is extremely significant because it enables the molding of thin-walled products, large-sized products, and products with complex designs, as well as the production of multiple pieces. Generally, [η] of the resinous component is
If it is less than 0.47, if the thin-walled molded product has many parts with different wall thicknesses or has a large and complex shape, uneven flow will occur when the molten resin flows inside the mold. Also, since it is subject to complex influences even during cooling, residual strains such as large shear strains and volumetric strains are likely to occur locally. Furthermore, in large molded products, even when stress loads such as slight bending or twisting occur, the length over which the stress acts (distance between fulcrums) becomes longer, so the moment becomes larger, causing changes in wall thickness, thin walls, and narrow parts. Stress concentration occurs in places where residual strain is large, such as, and the molded product has the disadvantage that local fracture (hereinafter referred to as local fracture) easily occurs at a strength lower than that originally possessed by the resin. Specifically, the distortion when removing the molded product from the mold,
Small stresses and strains such as vibrations and impact distortions during transportation of molded products, and vibrations and impact distortions during assembly of molded products can cause localized fractures of molded products that are not seen in small molded products. Furthermore, if [η] of the resin component is set to 0.47 or less, even if the impact resistance can be improved by some means, similar local failure will occur in thin-walled and large molded products, making it unusable for practical use. is the current situation. Therefore, the present inventors investigated the composition, structure, and various types of ABS resin in order to improve moldability without causing the local fractures that occur in thin-walled, large-sized molded products, and without sacrificing impact resistance. As a result of intensive studies from the perspective of additives, we reduced the amount of rubber components and made the [η] of the resin components 0.47 or less in order to improve moldability, thereby reducing impact resistance and local fracture. By using a specific base latex, setting the graft ratio within a specific range, and adding special additives, we succeeded in creating a thermoplastic resin composition suitable for manufacturing thin-walled and large-sized molded products. The present invention was completed. That is, the present invention has a gel content of 80% or less and an average particle size of
A graft polymer obtained by graft polymerizing a mixture of an aromatic vinyl monomer and a vinyl cyan monomer to a conjugated diene rubbery polymer of 0.2 μ or more, or the graft polymer and an aromatic vinyl monomer and Consists of a blend of vinyl cyan monomer and copolymer
ABS resin, the graft ratio of the graft polymer is 20 to 50%, and the intrinsic viscosity [η] of the resinous component is
0.35 to 0.47 dl/g, based on 100 parts by weight of thermoplastic resin in which the amount of rubbery components in the final ABS resin is 10 to 20% by weight: (1) aliphatic alcohol having 8 to 22 carbon atoms; (2) A compound selected from alcohol esters of phthalic acid, (3) alcohol esters of linear saturated fatty acids having 16 to 18 carbon atoms, (4) epoxidized products of the above linear saturated fatty acid alkyl esters, and (5) polysiloxanes. (1) one or more of the following;
A thermoplastic resin composition having excellent moldability is obtained by adding 0.1 to 1.0 parts by weight of the compounds (4) and 0.001 to 0.05 parts by weight of the compound (5). Conventionally, it has been known to improve the impact resistance of ABS resin by adding lubricants such as metal salts of higher fatty acids or amides (Japanese Patent Publication No. 47-37495), or by adding silicone oil (Japanese Patent Publication No. 49-29947). However, the local fracture phenomenon that occurs in thin-walled and large molded products is essentially a characteristic that is completely unrelated to impact resistance, and local fracture is also observed in ABS resins that use resinous components with [η] of 0.47 or less. This phenomenon is a characteristic that does not pose a problem with ordinary ABS resin ([η] 0.5 or more). Furthermore, the above-mentioned fatty acids, fatty acid salts, fatty acid amides, hydrogenated cured products of castor oil, etc., which are normally used as lubricants for ABS resins, are completely ineffective in preventing this local destruction phenomenon. However, in the present invention, although the ABS resin uses a resinous component with [η] of 0.47 or less,
Quite surprisingly, without sacrificing impact resistance, the inevitable local fracture properties of ABS resins with low [η] resinous components are prevented by means of special additives. A thermoplastic resin composition was obtained, and as a matter of course, the molding processability of this composition was improved. The present invention will be explained in detail below. The aromatic vinyl monomers used in the present invention include styrene, α-methylstyrene, vinyltoluene, etc. alone or in mixtures, and the vinyl cyanide monomers include acrylonitrile, methacrylonitrile, etc. alone or in mixtures. However, in addition to the above-mentioned two monomers, unsaturated carboxylic acid esters such as methyl methacrylate and methyl acrylate may be added as monomers to be grafted onto the rubbery polymer. As the rubbery polymer, commonly used diene-based rubbery polymers such as polybutadiene and styrene-butadiene copolymer are used singly or in combination, but those with a gel content of more than 80% or an average particle size of less than 0.2μ are used. The graft polymer obtained in the above method has insufficient impact resistance and is not suitable. Polymerization methods for graft polymerization include emulsion polymerization, bulk polymerization, solution polymerization, and suspension polymerization, and any method may be used, but if the grafting ratio is less than 20%, the surface gloss of the molded product may deteriorate. Moreover, if it exceeds 50%, impact resistance decreases, which is not preferable. Excellent effects cannot be exhibited unless [η] of the resin component, which controls the effect on moldability, is 0.47 or less. On the other hand, if [η] is smaller than 0.35, the impact resistance will drop significantly, so preferably [η] is 0.37.
A range of ~0.43 is good. In the present invention, [η] of the resinous component refers to a copolymer of free aromatic vinyl monomer and vinyl cyan monomer produced during the production of the graft polymer, and a copolymer blended with the graft polymer. Refers to [η] of the copolymer of aromatic vinyl monomer and vinyl cyan monomer used. The ABS resin used in the present invention may be the graft polymer itself obtained by graft polymerizing a mixture of an aromatic vinyl monomer and a vinyl cyan monomer onto a rubbery polymer, or the graft polymer itself and an aromatic vinyl monomer. It may be a blend with a copolymer of vinyl cyanide monomer and vinyl cyan monomer, but the amount of rubbery component in the final ABS resin should be 20% to obtain excellent moldability.
% or less, and to maintain impact resistance, the content must be 10% or more. Compounds that are effective for local destruction of molded products that occur during molding of thin-walled and large-sized products include (1) octyl alcohol;
Aliphatic alcohols with 8 to 22 carbon atoms, such as lauryl alcohol and stearyl alcohol, (2)
Alcohol esters of phthalic acid represented by dibutyl phthalate, di-2-ethylhexyl phthalate, diisodecyl phthalate, etc. (3) Alcohol esters of linear saturated fatty acids having 16 to 18 carbon atoms represented by butyl stearate, etc. , (4) Epoxidized products of linear saturated fatty acid alkyl esters having 16 to 18 carbon atoms such as epoxybutyl stearate, epoxyoctyl stearate, etc., (5) polydimethylsiloxane, polydiethylsiloxane, polyphenylmethylsiloxane One or more types selected from polysiloxanes represented by can be used. When should these compounds be added?
Any stage may be used as long as it is a step before pelletizing the ABS resin. In this case, when using the compounds (1) to (4), the total of one or more compounds is 0.1 to 1.0 parts by weight per 100 parts by weight of the thermoplastic resin, (5)
For the compound, 0.001 to 0.05 part by weight is used. If the amount added is too small, the local fracture prevention effect will be insufficient, and if the amount is too large, the mechanical strength of the ABS resin will decrease, molding defects due to excessive lubricity, and secondary processing defects such as plating and painting will occur. This is not desirable, resulting in an ABS resin with overall inferior properties. The effects of the present invention will be explained in more detail with reference to Examples below, but the present invention does not exceed the gist thereof.
The present invention is not limited to these examples. All parts and percentages in the examples are by weight. Incidentally, the graft ratio and gel content in the present invention are determined as follows. Grafting rate (%) = Acetone insoluble content (g) - Rubber polymer component (g) / Rubber polymer component (g) x 100 Gel content of rubber polymer (%) = Rubber polymer (g) -Toluene soluble content (g)/rubber polymer (g) x 100 Reference Example 1 First, a rubber polymer latex (hereinafter referred to as latex A) was produced by the following method. That is, butadiene is emulsion polymerized using fatty acid soap as an emulsifier, a redox initiator consisting of cumene hydroperoxide, ferrous sulfate, and formaldehyde sulfoxylate as an initiator, and t-dodecylmercaptan as a chain transfer agent. A polybutadiene latex with enlarged latex particles was prepared by forced stirring during the process. The total polymerization time was 33 hours, and the conversion rate was
It was 58%. The average particle diameter of latex A measured by the sodium alginate method was 0.44μ,
Gel content was 62%. Then, a graft polymerization reaction was carried out by the method described below. The following reagents were charged into a reactor equipped with a stirring device, a heating jacket, a thermometer, a nitrogen gas inlet, and a device for continuously adding monomers and a polymerization initiator. Latex A 40 parts Disproportionated rosin acid potassium salt 0.3 Potassium hydroxide 0.01 Water (including water in the latex) 100 After replacing the atmosphere in the reactor with nitrogen gas,
Heated it with a jacket. When the internal temperature of the reactor reached 70°C, a solution of 0.25 parts of sodium pyrophosphate, 0.3 parts of glucose, and 0.003 parts of ferrous sulfate in 10 parts of water was added. While stirring the mixture, the temperature of the jacket was maintained at 70 to 80°C, and the following emulsified mixture was added continuously over a period of 2 hours. Styrene 42 parts Acrylonitrile 18 t-Dodecyl mercaptan 0.4 Cumene hydroperoxide 0.25 Disproportionated rosin acid potassium salt 1.5 Potassium hydroxide 0.05 Water 100 After the addition, the reaction was continued with stirring for an additional hour. The conversion rate after the reaction was 95%. After adding 1.0 part of 2,6-di-t-butyl para-cresol as an anti-aging agent to the obtained polymer latex, the latex was coagulated with sulfuric acid, washed with water, and dried to obtain a graft polymer powder. The grafting rate of this graft polymer is 45%, and [η] of the resinous component is 0.37.
It was hot. Suspension polymerized AS beads ([η] =
0.37) to make ABS resin. This mixing ratio was adjusted so that the polybutadiene content in the final ABS resin was 15%. Next, add 1.5 parts of ethylene bis stearylamide to 100 parts of this mixed powder.
The mixture was mixed using a Henschel mixer (4), pelletized using an extruder, and further tested for impact resistance, local fracture resistance of thin-walled and large-sized molded products, and processability using the methods described below. Izotsu impact strength is 1oz
Specified test pieces were molded at 200°C using an injection molding machine, and measured at 23°C according to the method of ASTM D256. Local fracture resistance of thin-walled and large molded products is 140oz.
Using an injection molding machine (maximum injection force 1209Kg/cm ² ),
At a cylinder set temperature of 240°C or 260°C,
300mm, width 900mm, wall thickness 1-3mm, molded product weight
A 1.1Kg decorative window with a lattice pattern with many variations in wall thickness was molded, and the degree of breakage during removal from the mold was investigated. However, in consideration of distortion during subsequent processes, such as transportation and assembly, the molded product was slightly screwed by hand immediately after the mold was removed to examine its fracture properties, and the products that were destroyed at this time were also included in the evaluation. Ta. Molding processability was evaluated using the minimum filling pressure and molding temperature during this molding. These evaluation results are shown in Table 1. Reference Example 2, Comparative Examples 1 and 2 Latex A as a rubbery polymer latex
Latex B manufactured by the following method was used instead. Latex B was manufactured by continuing polymerization in the method for preparing latex A in Reference Example 1 without increasing the amount of t-dodecyl mercaptan and without performing forced stirring during the polymerization, and the total polymerization time was 33 hours.
At a conversion rate of 55%, the average particle size measured by the sodium alginate method was 0.27μ, and the gel content was 30%.
It was hot. Next, in the same graft polymerization method as in Reference Example 1, B-1 graft polymer (Reference Example 2, graft polymerization ratio 32%, resinous component [η] 0.41), B-2 graft polymer (Comparative Example 1,
Grafting rate 29%, resin component [η] = 0.32) and B-3 graft polymer (Comparative Example 2, grafting rate
Three types of graft polymers were obtained, each having a resin content of 33% and a resinous component [η] of 0.5). This B-1 powder contains styrene 70
suspension polymerization AS consisting of 30 parts of acrylonitrile and 30 parts of acrylonitrile
beads ([η] = 0.41), similar suspension polymerized AS beads for B-2 powder ([η] = 0.33), and similar suspension polymerized AS beads for B-3 powder ([η] = 0.51). ABS resin was made by mixing the two. This mixing ratio is the final
The polybutadiene content in the ABS resin was adjusted to 15%. The subsequent experiments were conducted according to Reference Example 1. These results are shown in Table 1. Comparative Example 3 In this example, a graft polymer was prepared using the following Latex C instead of Latex A, and the same experiment as in Reference Example 1 was conducted. Latex C was produced by continuing polymerization in the method for preparing Latex A in Reference Example 1 without adding t-dodecylmercaptan and without forced stirring, the polymerization time was 35 hours, and the conversion rate was 75%, average particle size is 0.25
μ, gel content was 78%. Next, in the same graft polymerization method as in Reference Example 1, t-
By adjusting the amount of dodecyl mercaptan, the amount of redox initiator, and the addition time of the emulsified mixture, a graft polymer with a graft ratio of 72% and a resinous component [η] of 0.39 was obtained. 70 parts of styrene to this powder,
Suspension polymerized AS beads ([η] = 0.41) consisting of 30 parts of acrylonitrile were mixed to reduce the polybutadiene content.
Made 15% ABS resin. The subsequent experiments were conducted according to Reference Example 1. These results are shown in Table 1. Comparative Example 4 In this example, a graft polymer was prepared using the following latex D instead of latex A, and the same experiment as in Reference Example 1 was conducted. Latex D was manufactured by continuing the polymerization in the method for preparing Latex A in Reference Example 1 without increasing the amount of t-dodecylmercaptan and without performing forced stirring during the polymerization, the total polymerization time was 25 hours, and the conversion rate was The average particle size was 0.15μ, and the gel content was 37%. Next, in the same graft polymerization method as in Reference Example 1, by adjusting the amount of t-dodecyl mercaptan, the amount of redox initiator, and the addition time of the emulsified mixture by a conventional method, the grafting rate was 3% and the [η ] A graft polymer of 0.42 was obtained. Suspension-polymerized AS beads ([η] is 0.41) consisting of 70 parts of styrene and 30 parts of acrylonitrile were mixed with this powder to produce an ABS resin with a polybutadiene content of 15%. The subsequent experiments were conducted according to Reference Example 1. These results are shown in Table 1. Examples 1-2 Graft polymer based on latex A prepared in Reference Examples 1 and 2 or B-1 graft polymer based on latex B and suspension polymerization AS
Polybutadiene content 15% made from beads
To 100 parts of ABS resin powder, 1.5 parts of ethylene bis stearylamide and various compounds shown in Table 2 were added to the combinations shown in Table 2, mixed in a Henschel mixer, and pelletized using an extruder. After that, impact resistance, moldability, and local fracture property were evaluated using the same test methods as in Reference Example 1.
The results are shown in Table 2, but since there was almost no change in impact resistance and moldability due to the addition of the compounds shown in Table 2, the results were omitted. Explanation of Table 1 Samples A and B-1 (Reference Examples 1 and 2) Show good impact resistance and moldability (low injection pressure, low cylinder temperature), but poor local fracture resistance. Sample B-2 (Comparative Example 1) Shows very excellent impact resistance and local fracture resistance, but has poor moldability. Sample B-3 (Comparative Example 2) Shows very good impact resistance and local fracture resistance, but has poor moldability, and to obtain the same moldability as other samples requires a cylinder temperature of approximately 20°C or an increase of 150 kg/cm ² in injection pressure. Samples C and D (Comparative Examples 3 and 4) Good moldability, but poor impact resistance and local fracture resistance.

【table】

【table】

[Table] (1) to (7) are within the scope of the present invention
(8) to (13) are outside the scope of the present invention Table 2 Explanation By adding butyl stearate, octyl epoxy stearate, diisodecyl phthalate, stearyl alcohol, lauryl alcohol, and dimethyl siloxane compounds, the local destructibility of ABS resin is significantly reduced. improves. Lauryl alcohol added by 0.05 part, ethylene bisstearylamide added by 1 part, hydrogenated castor oil, calcium stearate, stearic acid, tri-2-ethylhexyl trimellitate, and tricresyl phosphate have improved local destructive properties. The effect is insufficient.

Claims (1)

[Scope of Claims] 1. A product obtained by graft polymerizing a mixture of an aromatic vinyl monomer and a vinyl cyan monomer onto a conjugated diene rubbery polymer having a gel content of 80% by weight or less and an average particle size of 0.2μ or more. an acrylonitrile-butadiene-styrene resin comprising a graft polymer or a blend of the graft polymer and a copolymer of an aromatic vinyl monomer and a vinyl cyan monomer,
The grafting ratio of the graft polymer is 20 to 50%, the intrinsic viscosity [η] of the resinous component is 0.35 to 0.47 dl/g, and the amount of rubbery component in the final acrylonitrile-butadiene-styrene resin is 10 to 20% by weight. For 100 parts by weight of a certain thermoplastic resin, (1) aliphatic alcohol having 8 to 22 carbon atoms, (2) alcohol ester of phthalic acid, and (3) alcohol ester of linear saturated fatty acid having 16 to 18 carbon atoms. , (4) the epoxidized product of the linear saturated fatty acid alkyl ester, and (5) one or more compounds selected from polysiloxane, (1)
A thermoplastic resin composition containing 0.1 to 1.0 parts by weight of the compound (4) and 0.001 to 0.05 part by weight of the compound (5).