JPH075820B2 - Blow molding resin composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a thermoplastic resin composition for blow molding, which is suitable for blow molding of large parts and has excellent paintability and heat resistance.

[Conventional technology]

Blow molding has been mainly used for molding hollow containers mainly for polyolefin resins, but it is a technology for molding large structural parts because large molded products can be obtained using relatively simple equipment. Is also attracting attention. However, since blow molded products have lower surface smoothness than injection molded products, sanding treatment or buffing process to finish the molded product surface with sandpaper is required for applications requiring good appearance. It was In particular, when it is used for automobile exterior parts, a coating quality equivalent to that of metal materials is required, so careful finishing is necessary, and the burden on this cannot be ignored. In the case of polyolefin, it is known that blow moldability is excellent and a relatively smooth molded body surface can be obtained, but the coatability is not always good and the adhesion strength of the coating film is often low, and it also has heat resistance. Not enough. A resin material containing polyphenylene oxide as one component has good blow moldability, coating adhesion, and heat resistance, but it is inferior in chemical resistance. There is a case where the "pour-in" phenomenon is lost, which is lost.

By the way, ABS resin which is acrylonitrile-butadiene-styrene copolymer is a resin material having excellent coatability, but the characteristics of this resin are strength and ease of injection molding and good appearance of injection molded products. It was never considered as a blow molding material. In addition, even if ABS resin designed on the premise of processing by injection molding is applied to blow molding as it is, parison strength is low and drawdown is easy, so it is difficult to obtain large molded products and heat resistance is not always sufficient. However, there was a problem such as deformation during baking of the paint.

To impart heat resistance to ABS resin, the method of using α-methylstyrene as an aromatic vinyl compound is well known, but if the molecular weight is increased to suppress drawdown during blow molding, it will thermally decompose during extrusion. It was difficult to use it industrially. That is, a material excellent in blow moldability and coatability, as well as blow moldability, coatability, and heat resistance has not yet been established.

[Problems to be Solved by the Invention]

In view of the present situation, the present invention provides a blow molding resin material that can obtain a large-sized molded article that is difficult to obtain by an injection molding method and that can obtain a good coating appearance and a coating film adhesion strength without performing a sanding treatment or the like. The task is to do so.

[Means for Solving the Problems] The thermoplastic composition for blow molding having excellent blow moldability and coatability according to the present invention means a rubbery polymer (B), a vinyl cyanide compound (A) and an aromatic vinyl. The graft copolymer (I) obtained by copolymerizing the compound (S) with the vinyl cyanide compound (A) and the aromatic vinyl compound (S) are copolymerized with the organic silane compound monomer, or vinyl cyanide. A resin composition comprising a copolymer (II) obtained by copolymerizing a compound (A), an aromatic vinyl compound (S) and a copolymerizable vinyl compound (E) with an organosilane compound monomer. (I) 10 to 30% by weight of (B) in the composition, (ii) 35 to 50% by weight of (A) in the resin component excluding (B) in the composition, iii) The organic silane compound unit in the composition is 0.005 to 0.
12% by weight (iii) Using a blow molding machine, pellets of the composition were extruded from a molten resin at a cylinder temperature of 220 ° C. with a diameter of 50 mm and a slit interval of 3.2 mm, and the swell ratio obtained from the molded parison was 1.5 or more. And a drawdown ratio of 0.8 or more, which is a thermoplastic resin composition for blow molding.

Further, when it is desired to improve heat resistance, a composition in which the component (S) is styrene and / or α-methylstyrene,
A composition obtained by copolymerizing an n-substituted maleimide as the component (E) is suitable.

Hereinafter, the present invention will be described in detail.

Generally, a resin having excellent blow moldability, that is, a resin which is difficult to draw down even when a large parison is molded is said to have a high melt viscosity.

As means for increasing melt viscosity in ABS resin, (a)
Examples thereof include a method for increasing the rubbery polymer content, (b) increasing the molecular weight of the acrylonitrile-styrene copolymer component, and (c) copolymerizing a component that raises the glass transition temperature of the copolymer.

However, although the ABS resin whose melt viscosity is simply increased by these methods is difficult to draw down, it is difficult to obtain a smooth molded product surface, and there is a practical problem.
However, when the present inventors use a copolymer of a vinyl cyanide compound and an aromatic vinyl compound obtained by copolymerizing an organic silane compound as one component of the ABS resin, the molecular weight of the vinyl cyanide-aromatic vinyl copolymer is It has been discovered that excellent drawdown resistance can be obtained without increasing the value and the surface of the molded body is sufficiently smooth. This fact cannot be explained simply by the fact that cross-linking occurs between co-polymeric molecular chains and the apparent increase in molecular weight.The copolymer also acquires elastic properties and makes the elongation during blow molding uniform. This is an unexpected effect that was presumed to have occurred. In particular, this method
It is effective to apply it to a resin composition in which a component having a high glass transition temperature such as methylstyrene and n-substituted maleimide is copolymerized and thus has a high melt viscosity, and therefore it is difficult to increase the molecular weight.

The resin composition of the present invention comprises a graft copolymer (I) having a vinyl cyanide compound and an aromatic vinyl compound copolymer chemically bonded to a rubber polymer, an organosilane compound and a vinyl cyanide compound. It is composed of an aromatic vinyl compound and a copolymer (II) of a monomer copolymerizable therewith. The copolymer (II) is produced without graft bonding when the graft copolymerization reaction is carried out (hereinafter referred to as II-1), and is prepared in a reaction separate from the graft copolymerization reaction and mixed with the composition. It was done. Separately prepared polymers were a component obtained by copolymerizing an organic silane compound (hereinafter referred to as II-2) and a component not containing an organic silane compound (hereinafter referred to as III
-3) may be independently produced and used as a mixture. The copolymer (II) can be separated as an acetone-soluble component of the resin composition.

Examples of the organic silane compound include γmethacryloxypropyltrimethoxysilane, γmethacryloxypropylmethyldimethoxysilane, and γmethacryloxypropyltriethoxysilane. The amount of the silane compound contained in the copolymer (II) is not particularly limited, but 0.005 to 0.005% based on the resin composition combined with the copolymer (I).
0.12% by weight is preferred. If it is less than 0.005% by weight, the effect of improving blow moldability is not remarkable, and if it exceeds 0.12% by weight, workability is deteriorated. The vinyl cyanide compound (A) constituting the copolymers (I) and (II) can be copolymerized with acrylonitrile and methacrylonitrile, and the aromatic vinyl compound (S) can be copolymerized with styrene and α-methylstyrene. As the vinyl compound monomer (E), (meth) such as methyl methacrylate and butyl acrylate
Acrylic ester compound, n-phenylmaleimide, n
Examples thereof include cyclohexylmaleimide and maleic anhydride. Among these, a preferable combination is acrylonitrile-styrene and / or α-methylstyrene and acrylonitrile-styrene-n-phenylmaleimide.

In the resin composition of the present invention, the content of vinyl cyanide compound units in the resin is also important. Molded products obtained by the blow molding method are usually painted because they are inferior in appearance to those molded by injection molding, but the paintability of blow molded products is relatively low in molding distortion, so the resin used The composition of the material is of primary concern. In the resin composition of the present invention, the content of the vinyl cyanide compound unit in the resin component excluding the rubbery polymer is important and is 35 to 50% by weight.
Is preferable, and 36 to 44% by weight is more preferable. If the content is less than 35% by weight, stress cracks will occur on the surface of the molded product due to painting or thinner, causing paint swelling.If it exceeds 50% by weight, the resin will be colored when reworking the burr portion, which is not preferable. .

Examples of the rubbery polymer in the resin composition include polybutadiene, butadiene-styrene copolymer, butadiene-
Diene rubbery polymer such as acrylonitrile copolymer, butyl acrylate-methyl methacrylate-
Examples include acrylic rubber such as (meth) acrylic acid ester copolymer, and saturated rubbery polymer such as ethylene-propylene copolymer rubber. Since the content of the rubbery polymer (B) does not significantly affect the paintability and blow moldability, it may be set according to the impact resistance required for the product, 10% by weight to
30% by weight is preferred.

Furthermore, the composition of the present invention satisfies the above requirements,
Using a blow molding machine for pellets of the composition, a molten resin was extruded from a die having a cylinder temperature of 220 ° C., a diameter of 50 mm, and a slit interval of 3.2 mm, and a swell ratio determined from the molded parison was 1.5 or more and a drawdown ratio was 0.8. Must be above.

The method for producing the copolymers (I) and (II) is not particularly limited, and known methods such as emulsion polymerization method, suspension polymerization method and solution polymerization method can be applied. A method is preferred in which a copolymer (I) having a high polymer content is prepared, a copolymer (II) containing an organosilane compound is prepared by a solution polymerization method, and both are extruded and blended.

As the copolymer (II), a copolymer (II-2) containing an organic silane compound and a copolymer (II-3) not containing an organic silane compound are separately prepared to obtain a graft copolymer (I). The most preferable method is to extrude and knead the added three components to obtain a resin composition.

For the resin composition, a known heat stabilizer, ultraviolet absorber,
It is optional to add a release agent, a lubricant, an antistatic agent, a flame retardant and a coloring agent.

〔Example〕

 The present invention will be described below based on Examples.

The number of parts used below is parts by weight.

<Graft copolymerization reaction> G-1: 60 parts of polybutadiene rubber latex (as solid content) and 100 parts of deionized water were put in a polymerization tank equipped with a reflux condenser, and the temperature was raised to 70 ° C while replacing the gas phase with nitrogen. did.

Then add 24 parts of styrene and 16 parts of acrylonitrile.
Part, 0.3 part of t-dodecyl mercaptan, 0.2 part of cumene hydroperoxide and deionized water 50
Part, sodium formaldehyde sulfoxylate 0.2
Parts, 0.004 parts of ferrous sulfate, and 0.008 parts of ethylenediaminetetraacetic acid disodium salt were added continuously for 5 hours to react. During this period, the polymerization temperature was adjusted to 70 ° C., and after the additional addition was completed, the state was maintained for another 30 minutes to complete the polymerization.

The polymerization rate of the monomer was 93.3%, and the content rate of acrylonitrile unit in the resin component excluding the rubbery polymer was 36.1%.

G-2: Polybutadiene rubber latex rubber solid content 40 parts, deionized water 100 parts, potassium rosinate 0.3 parts, t-dodecyl mercaptan 0.2 parts were put in a polymerization tank equipped with a reflux condenser, and the gas phase was replaced with nitrogen. The temperature was raised to 70 ° C. 24 parts acrylonitrile, 36 parts styrene, cumene hydroperoxide
A mixed solution of 0.15 parts, t-dodecyl mercaptan 0.4 parts, and an aqueous solution prepared by adding 50 parts of deionized water, 0.3 parts of sodium formaldehyde sulfoxylate, 0.004 parts of ferrous sulfate, and 0.04 parts of ethylenediaminetetraacetic acid sodium salt, It was made to react by adding continuously over time. During this period, the temperature of the polymerization system was controlled at 70 ° C, and 0.02 parts of cumene hydroperoxide was further added after the addition was completed,
The state was maintained for 1 hour to complete the reaction.

The monomer polymerization rate was 97.5%, and the content rate of acrylonitrile units in the resin component excluding the rubbery polymer was 39.3%.

<Organosilane compound copolymerization reaction> To a flask equipped with a reflux condenser, 5000 g of ethylbenzene, 1750 g of styrene, 3250 g of acrylonitrile, 10.0 g of γ-methacryloxypropyltrimethoxysilane and 15.0 g of benzoyl peroxide were added, and the mixture was reacted at 60 ° C for 3 hours. It was
The copolymer was precipitated and recovered using methanol, and the acrylonitrile content was determined from the atomic analysis, and the γ-methacryloxypropyltrimethoxysilane content was calculated from the silicon content determined by the atomic absorption method.
It was 0.35%.

<Vinyl cyanide compound-aromatic vinyl compound copolymerization reaction> M-1: 170 parts of deionized water, potassium alkenyl succinate [Latemul ASK manufactured by Kao Soap Co., Ltd.] 1.0 part, disproportionated potassium rosinate 1.0 part 0.4 parts of sodium formaldehyde sulfoxylate, 0.004 parts of ferrous sulfate and 0.008 parts of ethylenediaminetetraacetic acid disodium salt were placed in a polymerization tank equipped with a reflux condenser and heated to 65 ° C. while substituting the gas phase with nitrogen.
Then, a mixture of 40 parts of acrylonitrile, 60 parts of α-methylstyrene, 0.1 part of t-dodecyl mercaptan and 0.5 part of cumene hydroperoxide, and 80 parts of deionized water, sodium formaldehyde sulfoxylate.
An aqueous solution containing 0.1 part, 0.001 part of ferrous sulfate, and 0.002 part of ethylenediaminetetraacetic acid disodium salt was continuously added for 8 hours and reacted. During this time, the polymerization temperature was 65 ° C.
After completion of the additional addition, the state was maintained for 1 hour to complete the polymerization.

M-2: The same reaction as M-1 was carried out with 27 parts of acrylonitrile and 73 parts of α-methylstyrene to obtain M-2.

M-3: The same reaction as M-1 was carried out without t-dodecyl mercaptan to give M-3.

M-4 to M-6: Using a completely mixed continuous reactor, a monomer solution consisting of acrylonitrile, styrene, and ethylbenzene was continuously added at a constant rate while the product was being dispensed to keep the reaction rate in the polymerization system constant. It kept, and the acrylonitrile-styrene copolymer was obtained. At this time, by changing the composition of the monomer added continuously, M-
4-M-6 were obtained.

The analytical values of M-1 to M-6 are collectively shown in Table 1.

Example 1 Graft copolymer G-1 and copolymer M-1 containing no organic silane compound unit were latex-blended at a ratio of 35:65 in solid content, and 1.3 parts of magnesium sulfate based on 100 parts of total solid content. Was added to obtain an aggregate. 0.2 parts by weight of a phenolic heat stabilizer [Sumitomo Chemical Co., Ltd., BHT] was added to 10 parts by weight of a copolymer containing an organic silane compound to 90 parts by weight of a resin powder obtained by washing the aggregate with water, dehydration and drying. After adding 0.5 parts by weight of ethylenebisstearylamide, the mixture was pelletized using an extruder. Using a blow molding machine for pellets, the molten resin was extruded from a die with a die diameter of 50 mm and a slit interval of 3.2 mm at a cylinder temperature of 220 ° C., and from the molded parison, the swell ratio and drawdown ratio were calculated according to the following formulas, respectively. It was 1.85 and 0.95.

Cooled parison into a coating solution at 23 ℃ (Lecrac 55 (Fujikura Kasei): Non-brushing: 169 thinner = 50:15:35)
When immersed for 20 seconds and dried at 80 ° C. for 30 minutes and observing the surface condition, no cracks were found. The pellets were injection-molded into test pieces, and the Izod impact value and heat distortion temperature were measured according to the standard.
It was kg cm / cm and 100 ° C.

In Examples 2 to 4 and Comparative Examples 1 to 4, the same test was conducted by changing the ratio of each copolymer. The results are collectively shown in Table 2. In Comparative Example 2, parison molding itself was impossible. The blow moldability was judged to be good when the swell ratio was 1.5 or more and the drawdown ratio was 0.8 or more.

Example 5 A copolymer M-4 containing no organosilane compound and an organosilane compound copolymer which were separately polymerized into a powder by the same method as that used in Example 1 using the graft copolymer latex G-2, were added, Heat stabilizer and lubricant were added and pelletized using an extruder. The same evaluations as in Example 1 were performed and the results are shown in Table 2.

Examples 6 and 7, Comparative Examples 5 and 6 The same operation as in Example 5 was carried out by changing the ratio of each component, and the results are summarized in Table 2.

From Table 2, good blow moldability and impact strength were obtained at 10 to 30% by weight of the rubbery polymer in the composition and the content of the organic silane compound unit was 0.005 to 0.12, and acrylonitrile in the resin component excluding the rubbery polymer. It is clear that good coatability is obtained when the unit content is 0.35% by weight or more. This person
It is clear that it is also effective when the α-methylstyrene copolymers (Examples 1 to 4) and the n-phenylmaleimide copolymers (Examples 6 and 7) are used.

Claims (5)

[Claims] 1. A graft copolymer (I) obtained by copolymerizing a rubbery polymer (B) with a vinyl cyanide compound (A) and an aromatic vinyl compound (S), and a vinyl cyanide compound (A).
And an aromatic vinyl compound (S) are copolymerized with an organic silane compound monomer, or a vinyl cyanide compound (A) and an aromatic vinyl compound (S) and a copolymerizable vinyl compound (E) are an organic silane. A resin composition comprising a copolymer (II) copolymerized with a compound monomer, wherein (i) (B) in the composition is 10 to 30% by weight, and (ii) the composition. (A) occupy 35 to 50% by weight of the resin component excluding (B) in the product, and (iii) the organic silane compound unit in the composition is 0.005 to 0.
12% by weight, and (iv) using a blow molding machine, extruding a molten resin from a die having a cylinder temperature of 220 ° C., a diameter of 50 mm and a slit interval of 3.2 mm, and a swell ratio obtained from a molded parison. Of 1.5 or more and a drawdown ratio of 0.8 or more, a thermoplastic resin composition for blow molding. 2. A thermoplastic resin composition for blow molding with improved heat resistance according to claim 1, wherein (A) which constitutes the composition is acrylonitrile and (S) is styrene and / or α-methylstyrene. . 3. The thermoplastic resin for blow molding with improved heat resistance according to claim 1, wherein (A) constituting the composition is acrylonitrile, (S) is styrene, and (E) is an n-substituted maleimide. Resin composition. 4. A blow-molded article obtained by using the blow-molding resin composition according to claim 1. 5. A product obtained by applying a coating to the molded product according to claim 4.