JP2013100436A - Highly branched rubber-modified styrenic resin composition for blow molding, and molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly branched rubber-modified styrenic resin composition for blow molding containing a branched ultrahigh molecular weight copolymer and excellent in a balance of melt tension and melt stretchability; and to provide a large-sized blow molded article using the same.SOLUTION: The highly branched rubber-modified styrenic resin composition for blow molding is formed by continuously feeding and polymerizing a raw material solution in which 100 to 3,000 ppm in terms of weight of a solvent-soluble polyfunctional vinyl compound copolymer having two or more vinyl groups in one molecule thereof and having a branched structure is continuously added to a monovinyl compound containing as an essential component styrene having a rubber component dissolved therein, in a polymerization reactor, and contains a highly branched ultrahigh molecular weight copolymer produced by polymerizing the solvent-soluble polyfunctional vinyl compound copolymer and the monovinyl compound, and a linear polymer produced by polymerizing the monovinyl compound, wherein Mw is 150,000 to 400,000; Mz/Mw is 2.2 to 5.0; and the branch ratio gM at the molecular weight of 1,000,000 to 1,500,000 is 0.85 to 0.40.

Description

  The present invention provides a continuous polymerization method in which a monovinyl compound essentially containing styrene in which a rubber component is dissolved and a solvent-soluble polyfunctional vinyl copolymer having a plurality of double bonds in one molecule are continuously supplied to a polymerization reactor. The present invention relates to a rubber-modified styrenic resin composition for high-branch blow molding containing a hyperbranched ultrahigh molecular weight copolymer and a linear polymer obtained by the following, and a molded product obtained therefrom. Excellent blow moldability of large molded products.

  Rubber-modified styrenic resins are used in a wide range of fields as industrial products, packaging materials, and daily necessities because of their excellent balance between rigidity and impact resistance and excellent dimensional stability and colorability. In the field of large molded products, large molded products such as housing equipment such as bathroom ceilings and vanities and automobile parts such as spoilers are manufactured by blow molding. Blow molding has a lower cost for molds and easier mold processing than injection molding, so that a large molded product can be obtained at low cost. However, when a large molded product is formed by blow molding, the parison cannot withstand its own weight and drawdown occurs, and the thickness of the molded product may become uneven or the molding itself may be impossible. If the thickness of the molded product is not uniform, the rigidity of the thin portion is lowered and the impact resistance is also lowered.

  To improve the draw-down resistance, a method of increasing the molecular weight of the rubber-modified styrenic resin and increasing the viscosity can be considered, but the flow becomes unstable during the extrusion of the parison, melt fracture occurs, and the thickness increases in the flow direction. Becomes non-uniform. In order to improve the drawdown resistance while stabilizing the extrusion of the parison, the balance between the fluidity (viscosity) of the molten resin and the melt tension representing elasticity is important, and the melt stretching represents elongation in the molten state. Balance with gender is important.

  As a means for controlling the melt tension, it is known that a method of containing an ultrahigh molecular weight component in a styrene resin is effective.

  As a method of obtaining a resin composition containing an ultrahigh molecular weight component, for example, there is a styrene polymer composition containing a component having a molecular weight of 2 million or more described in Patent Document 1 within a certain range. In order to obtain this composition, a method in which polymerization is allowed to proceed at a low temperature before polymerization or a method in which an ultrahigh molecular weight polymer separately polymerized by anionic polymerization or the like is blended have been proposed. There are problems such as inferior properties and high costs when blending separately polymerized components.

  In order to avoid the above problem, for example, there is a styrenic polymer containing a molecular weight component of 1 million or more containing a polyfunctional vinyl compound unit described in Patent Document 2 within a certain range. In order to contain a molecular weight component, it has been proposed to polymerize by adding a very small amount of an aromatic polyfunctional vinyl compound typified by an aromatic divinyl compound to a vinyl monomer. However, when this means is applied to continuous bulk polymerization, when a long-term reaction is continued, there is a problem that gelation proceeds in a region where the flow called a boundary film existing on the wall of the polymerization reactor is stopped, When trying to avoid the above, the amount of the polyfunctional aromatic vinyl compound was limited, and it was difficult to produce a desirable amount of ultrahigh molecular weight component.

  Furthermore, Patent Document 3 discloses a rubber-modified styrenic resin using a polyfunctional polymerization initiator. However, in this method, the entire styrenic polymer is likely to have a high molecular weight, and in order to avoid this, a large amount of chain transfer is performed. If the agent is used, the effect becomes insufficient. Patent Document 4 discloses that a styrene-based resin composition composed of linear polystyrene and multi-branched polystyrene obtained using a multi-branched macromonomer has excellent melt tension. Improvement is inadequate.

Japanese Examined Patent Publication No. 62-61231 JP-A-10-130443 JP 2002-145968 A JP 2003-292707 A

  The object of the present invention is to improve the draw-down resistance during blow molding, and is excellent in the balance between melt tension and melt stretchability, has no gel-like material, and contains a highly branched ultra-high molecular weight material. A rubber-modified styrenic resin composition and a molded product obtained therefrom are provided.

  That is, the present invention is a rubber-modified styrenic resin composition for hyperbranched injection blow as described below and a molded product obtained therefrom.

(1) A solvent-soluble polyfunctional vinyl copolymer having an average of two or more vinyl groups in one molecule and a branched structure in a monovinyl compound essentially containing styrene in which a rubber component is dissolved is 100 ppm by weight. The solvent-soluble polyfunctional vinyl copolymer and the monovinyl compound obtained by continuously supplying a raw material solution to a polymerization reactor in which ˜3000 ppm is added and one or more are continuously arranged to advance the polymerization reaction Is a rubber-modified styrenic resin composition comprising a hyperbranched ultrahigh molecular weight copolymer produced by polymerizing and a linear polymer produced by polymerizing the monovinyl compound, and having a weight average molecular weight (Mw) of 150,000 ˜400,000, the ratio (Mz / Mw) of the Z average molecular weight (Mz) to the weight average molecular weight (Mw) is 2.2 to 5.0, and the branching ratio gM at a molecular weight of 1 million to 1.5 million is 0.85 to 0. .4 Hyperbranched for blow molding a rubber-modified styrene resin composition characterized by it.

（式中、Ｒ¹はジビニル化合物に由来する炭化水素基を示す。） (2) The solvent-soluble polyfunctional vinyl copolymer is obtained by polymerizing a monovinyl compound copolymerizable with a divinyl compound, and further contains a pendant vinyl group-containing unit derived from the divinyl compound represented by the following formula (a1). It is contained in the structural unit in the range of 0.10 to 0.50 as the molar fraction, and the ratio of the inertial radius (nm) in the weight average molecular weight to the molar fraction is in the range of 10 to 80. (1) A rubber-modified styrenic resin composition for highly branched blow molding.

(In the formula, R ¹ represents a hydrocarbon group derived from a divinyl compound.)

(3) A blow-molded product obtained by blow-molding the rubber-modified styrenic resin composition for highly branched blow-molding according to (1) or (2).

  The rubber-modified styrenic resin composition for highly branched blow molding of the present invention contains a highly branched ultra-high molecular weight copolymer and a linear polymer in a well-balanced manner, and has an excellent balance between melt tension and melt stretchability. It has excellent draw-down resistance, is suitable for blow molding of large molded products, and can obtain molded products with uniform wall thickness.

  Hereinafter, the present invention will be described in detail. The production method of the rubber-modified styrene-based resin composition for highly branched blow molding of the present invention (hereinafter also referred to as a rubber-modified styrene-based resin composition) includes a monovinyl compound containing styrene in which a rubber component is dissolved and a solvent-soluble polyfunctional compound. One or more reactions arranged in series and / or in parallel by adding a vinyl copolymer (hereinafter also referred to as a polyfunctional vinyl copolymer) and, if necessary, a solvent, a polymerization catalyst, a chain transfer agent and the like. A so-called continuous bulk polymerization method is preferably used in which monomers are continuously fed into a vessel and equipment equipped with a devolatilization step for removing unreacted monomers and the like, and the polymerization proceeds in stages. . Examples of the reactor type include a fully mixed tank reactor, a column reactor having plug flow properties, and a loop reactor in which a part of the polymerization liquid is withdrawn while the polymerization proceeds. There are no particular restrictions on the order of arrangement of these reactors, but in order to suppress the formation of gel-like materials in continuous production, the polyfunctional vinyl copolymer is unreacted and is not present in the reactor wall film. It is important not to develop a state of staying at a high concentration, and it is preferable to select a fully mixed tank reactor as the first reactor. The devolatilization process includes a vacuum devolatilization tank with a heater, a vented devolatilization extruder, and the like. The polymer in the molten state that has exited the devolatilization step is transferred to the granulation step. In the granulation step, the molten resin is extruded in a strand form from a porous die and processed into a pellet shape by a cold cut method, an air hot cut method, or an underwater hot cut method. One or more polymerization reactors are arranged in succession, but in the case of one, one may be used alone, and in the case of two or more, at least two are arranged in series (in series).

  The raw material solution contains a monovinyl compound containing styrene, a rubber component, and a polyfunctional vinyl copolymer. The polyfunctional vinyl copolymer, which is a constituent element of the rubber-modified styrene resin composition of the present invention, should be added from the middle of the reactor as necessary in a state dissolved in monovinyl compounds, a polymerization solvent and the like. You can also.

  The monovinyl compound (hereinafter also referred to as styrene monomer) used as a raw material for the rubber-modified styrene resin composition of the present invention may be 100% styrene, and styrene and other monovinyl compounds. It may be a mixture containing Other monovinyl compounds may be those having an olefinic double bond copolymerizable with styrene, such as aromatic vinyl monomers such as paramethylstyrene, acrylic acid monomers such as acrylic acid and methacrylic acid, and acrylonitrile. , Vinyl cyanide monomers such as methacrylonitrile, acrylic monomers such as butyl acrylate and methyl methacrylate, α, β-ethylenically unsaturated carboxylic acids such as maleic anhydride and fumaric acid, and imides such as phenylmaleimide and cyclohexylmaleimide Based monomers. These other monovinyl compounds may be used alone or in combination of two or more. And it is preferable that the ratio of styrene and another monovinyl compound is 50-100 mol% of styrene and 0-50 mol% of other monovinyl compounds in order to make use of the characteristics of the rubber-modified styrene resin composition.

  The rubber component that is a constituent element of the rubber-modified styrenic resin composition of the present invention is preferably a rubber-like polymer. The rubbery polymer is not particularly limited as long as it exhibits rubbery properties at room temperature. For example, polybutadiene, styrene-butadiene copolymers, styrene-butadiene block copolymers, hydrogenated (partially hydrogenated) polybutadiene, Hydrogenated (partially hydrogenated) styrene-butadiene copolymers, hydrogenated (partially hydrogenated) styrene-butadiene block copolymers, ethylene-propylene copolymers, ethylene-propylene-nonconjugated diene ternary copolymer Polymers, isoprene polymers, styrene-isoprene copolymers, and the like. These rubbery polymers can be used alone or in combination of two or more. The rubber component is used after being dissolved in a styrene-based monomer, but is dispersed in the composition into micro particles by the phase transition mechanism described later.

  The amount of the rubber component used is preferably 2 to 12 parts by weight, more preferably 3 to 8 parts by weight, based on 100 parts by weight of the styrene monomer.

  The polyfunctional vinyl copolymer used as a raw material for the rubber-modified styrene resin composition of the present invention provides a highly branched styrene resin that is highly branched by being copolymerized with a styrene monomer. It is.

  The polyfunctional vinyl copolymer can be obtained according to the methods disclosed in JP-A No. 2004-123873, JP-A No. 2005-213443, WO 2009/110453, and the like. Specifically, a divinyl compound and at least one monovinyl compound are used for copolymerization to obtain a copolymer having a reactive pendant vinyl group represented by the formula (a1). Furthermore, as described in the above-mentioned patent document, those having other terminal groups other than vinyl groups introduced at the terminals can also be used, particularly for compounds having an unsaturated bond in the molecule such as phenoxy methacrylates. In addition to (a1), it is possible to use a terminal-modified one because it can act as a crosslinking point. In this case, since the terminal unsaturated bond-containing structural unit (a2) also has a vinyl group, the total molar fraction (a3) with the structural unit of the formula (a1) indicates the total amount of vinyl groups present. It will be.

  Examples of divinyl compounds used to obtain polyfunctional vinyl copolymers include divinyl aromatic compounds represented by divinylbenzene and aliphatic and alicyclic (meth) acrylates represented by ethylene glycol di (meth) acrylate. Examples are shown.

  Moreover, as a monovinyl compound used here, the monovinyl compounds containing monovinyl aromatic compounds, such as styrene as mentioned above, are mentioned.

  As a method for producing a polyfunctional vinyl copolymer, for example, two or more kinds of compounds selected from divinyl aromatic compounds, monovinyl aromatic compounds and other monovinyl compounds are used as promoters selected from Lewis acid catalysts and ester compounds. It can be obtained by cationic copolymerization in the presence. Further, when a (meth) acrylate divinyl or monovinyl compound is used, the reaction does not proceed in cationic polymerization, and therefore, it can be obtained by radical polymerization in the presence of a radical catalyst such as peroxide.

  The amount of divinyl compound and monovinyl compound used is determined so as to give the composition of the polyfunctional vinyl copolymer used in the present invention. The divinyl compound is preferably used in an amount of 10 to 90 mol% of the total monomers. Preferably 30 to 90 mol% is used. The monovinyl compound is preferably used in an amount of 90 to 10 mol%, more preferably 70 to 10 mol% of the total monomers. Here, in cationic polymerization like 2-phenoxyethyl methacrylate, what acts as a terminal modifier is not calculated as a monomer.

  The Lewis acid catalyst used in the production of the polyfunctional vinyl copolymer is not particularly limited as long as it is a compound composed of a metal ion (acid) and a ligand (base) and can receive an electron pair. Can be used. From the viewpoints of control of molecular weight and molecular weight distribution and polymerization activity, boron trifluoride ether (diethyl ether, dimethyl ether, etc.) complexes are most preferably used. The Lewis acid catalyst is used in the range of 0.001 to 10 mol, more preferably 0.001 to 0.01 mol, per 1 mol of the monomer compound. An excessive amount of the Lewis acid catalyst is not preferable because the polymerization rate becomes too high and it becomes difficult to control the molecular weight distribution.

  Examples of the cocatalyst include one or more selected from ester compounds. Among them, an ester compound having 4 to 30 carbon atoms is preferably used from the viewpoint of controlling the polymerization rate and the molecular weight distribution of the copolymer. From the viewpoint of availability, ethyl acetate, propyl acetate and butyl acetate are preferably used. The cocatalyst is used in the range of 0.001 to 10 mol, more preferably 0.01 to 1 mol, relative to 1 mol of the monomer compound. When the amount of the cocatalyst used is excessive, the polymerization rate decreases and the yield of the copolymer decreases. On the other hand, when the amount of the cocatalyst used is too small, the selectivity of the polymerization reaction is lowered, the molecular weight distribution is increased, the gel is generated, and the polymerization reaction is difficult to control.

  In addition, as a catalyst used for producing a polyfunctional vinyl copolymer by radical polymerization, simple compounds such as azo compounds represented by azobisisobutyronitrile, dibenzoyl peroxide, t-butylperoxybenzoate and the like can be used. Examples of functional peroxides and bifunctional or higher functional peroxides such as 1,1-bis (t-butylperoxy) cyclohexane are exemplified, and they are used alone or in combination of two or more. be able to.

  The polyfunctional vinyl copolymer used in the present invention can be obtained by the above production method, but it is necessary to leave a part of the vinyl group of the divinyl compound used as a monomer without polymerizing. . Then, on average, 2 or more, preferably 3 or more vinyl groups are present in one molecule. This vinyl group exists mainly as a structural unit represented by the above formula (a1). Then, by leaving a part of the vinyl group without being polymerized, the crosslinking reaction can be suppressed and solvent solubility can be imparted. Here, solvent-soluble means that it is soluble in toluene, xylene, THF (tetrahydrofuran), dichloroethane or chloroform. Specifically, in 100 g of these solvents, 5 g or more is dissolved at 25 ° C. It does not occur. On the other hand, a part of the divinyl compound needs to be crosslinked or branched by the reaction of two vinyl groups, whereby a copolymer having a branched structure can be obtained. Thus, in the present invention, one of the two vinyl groups is reacted for a part of the divinyl compound, one is left unpolymerized, and the other two are reacted together with the two vinyl groups. The polyfunctional vinyl copolymer to be used can be obtained. The polymerization method for obtaining such a polyfunctional vinyl copolymer is known as described above, and can be produced as described above.

  The weight average molecular weight (Mw) of the polyfunctional vinyl copolymer is preferably 1,000 to 100,000, more preferably 5,000 to 70,000. When it is smaller than 1,000, the effect of suppressing the progress of gelation in continuous polymerization is reduced as in the case of using an aromatic divinyl compound or a polyfunctional (meth) acrylate, and it is difficult to obtain a sufficient effect in continuous polymerization.

  The unit containing a vinyl group derived from a divinyl compound introduced into the polyfunctional vinyl copolymer has a structural unit represented by the above formula (a1), and the molar fraction of the structural unit (a1) is 0.10. It is good that it is -0.50. When the amount is less than 0.10 mol, it is difficult to obtain a high-branched ultrahigh molecular weight copolymer having a high molecular weight necessary for blow molding. On the other hand, when it exceeds 0.50 mol, the molecular weight of the hyperbranched ultra-high molecular weight copolymer is excessively increased and gelation is likely to occur, which tends to cause poor appearance of the blow molded product.

Here, the structural unit (a1), the double bond (a2) derived from the terminal modifier, and the total molar fraction (a3) of both were measured using 13 J-NMR and JC-LA600 type nuclear magnetic resonance spectrometer. The structure was determined by 1H-NMR analysis. Chloroform-d1 was used as a solvent, and the tetramethylsilane resonance line was used as an internal standard.
As described above, those having a terminal modification with a compound having an unsaturated bond in the molecule, in addition to the structural unit represented by the formula (a1), the terminal unsaturated bond-containing structural unit (a2) also has a vinyl group. Therefore, it is preferable that the total molar fraction (a3) of both is 0.10 to 0.50.

  In addition, the polyfunctional vinyl copolymer requires a ratio of the radius of inertia (nm) in the weight average molecular weight to the molar fraction of the structural unit (a1) or the total molar fraction (a3) for this application. In order to adjust the hyperbranched ultrahigh molecular weight copolymer for imparting high melt tension and melt stretchability without gelation, it is preferably in the range of 10-80. When the above ratio exceeds 80, gelation does not proceed, but there is a tendency that a highly branched ultrahigh molecular weight copolymer is not sufficiently obtained. On the other hand, when it is smaller than 10, the hyperbranched ultra-high molecular weight copolymer tends to grow into a gel, and there is a tendency that defects such as poor appearance due to a minute gel tend to occur during blow molding.

Here, after adjusting the sample to a 0.5% THF solution, the radius of inertia was filtered with a membrane filter, and the filtrate was measured using a GPC multi-angle light scattering method. Further, the sample was adjusted to 0.2% THF solution and allowed to stand for 1 day. After that, it is diluted with THF to four kinds of concentration (0.02, 0.05, 0.10, 0.12 wt%) solutions, and dn / dc value (inherent refractive index increment) is used with these solutions. : A value representing how much the refractive index of the polymer solution changes with respect to the change in the concentration of the solute), and the inertia radius of the sample was calculated from the obtained dn / dc value.
The polyfunctional vinyl copolymer is a polymer having a distribution in molecular weight, and naturally, since the inertia radius also has a distribution, the inertia radius in the weight average molecular weight is adopted as the average value of the overall inertia radius. is there.

  The ratio of the molar fraction of the structural unit (a1) or the total molar fraction (a3), which is an index representing the radius of inertia and the double bond content defined here, is a highly branched ultrahigh molecular weight copolymer. It can be said that this is an index indicating how many reaction points are present in the spread of the polyfunctional vinyl copolymer as a nucleus in the polymerization reaction solution. If this ratio is too small, the reaction point is in the vicinity and gelation is likely to occur, and if this ratio is too large, it is difficult to increase the molecular weight of the branched component.

  As a compounding ratio of the polyfunctional vinyl copolymer with respect to a styrene-type monomer, it is 100 ppm-3000 ppm on a weight basis, and 100 ppm-1000 ppm are more preferable. When the blending ratio of the polyfunctional vinyl copolymer is less than 100 ppm, the production amount of the hyperbranched ultrahigh molecular weight copolymer is insufficient. On the other hand, when it exceeds 3000 ppm, a gel is formed, which is minute during blow molding. There is a possibility of causing problems such as poor appearance due to gel.

  By copolymerizing the polyfunctional vinyl copolymer and the styrenic monomer, a hyperbranched ultrahigh molecular weight copolymer that is a copolymer of the polyfunctional vinyl copolymer and the styrenic monomer, and a styrenic monomer Thus, the rubber-modified styrenic resin composition of the present invention, which is a mixture of a linear polymer produced only from the above and a rubber component dispersed in the form of particles, is obtained. When two or more kinds of styrenic monomers are used, the linear polymer becomes a copolymer.

  The weight average molecular weight (Mw) of the rubber-modified styrenic resin composition of the present invention is 150,000 to 400,000, preferably 200,000 to 350,000, and more preferably 230,000 to 330,000. When the Mw is less than 150,000, the strength of the rubber-modified styrene resin composition is insufficient. When the Mw exceeds 400,000, the fluidity is remarkably deteriorated and the moldability is lowered. The Mw of the rubber-modified styrene resin composition is the reaction temperature of the polymerization process, the residence time, the blending ratio of the polyfunctional vinyl copolymer, the type and addition amount of the polymerization initiator, the type and addition amount of the chain transfer agent, It can be controlled by the type and amount of the solvent used. The rubber-modified styrene resin composition of the present invention is a form in which rubber-like dispersed particles are dispersed in a matrix phase of a styrene resin composition comprising a hyperbranched ultrahigh molecular weight copolymer and a linear polymer, and has a molecular weight Means the molecular weight of the matrix phase. Therefore, the sample used for the molecular weight measurement was one from which rubber-like dispersed particles were removed. Specifically, a sample prepared by gel content measurement described later was used.

The weight average molecular weight (Mw), the Z average molecular weight (Mz), and the number average molecular weight (Mn) were measured using gel permeation chromatography (GPC) under the following conditions.
GPC model: Shodex GPC-101 manufactured by Showa Denko KK
Column: Polymer Laboratories PLgel 10 μm MIXED-B
Mobile phase: Tetrahydrofuran Sample concentration: 0.2% by mass
Temperature: 40 ° C oven, 35 ° C inlet, 35 ° C detector
Detector: differential refractometer The molecular weight is measured by calculating the molecular weight at each elution time from the elution curve of monodisperse polystyrene, and calculating the molecular weight in terms of polystyrene.

  Moreover, ratio (Mz / Mw) of Z average molecular weight (Mz) and weight average molecular weight (Mw) is 2.2-5.0, and 2.3-4.0 are preferable and 2.6-3. 5 is more preferable. When Mz / Mw is less than 2.2, the content of the hyperbranched ultrahigh molecular weight copolymer becomes insufficient. When Mz / Mw exceeds 5.0, the molecular weight of the hyperbranched ultrahigh molecular weight copolymer is insufficient. And the gel is likely to be formed in the manufacturing process.

  The branching ratio gM in the component having a molecular weight of 1,000,000 to 1,500,000 of the rubber-modified styrene resin composition of the present invention is 0.85 to 0.40, preferably 0.80 to 0.50. The branching ratio gM represents the degree of branching of the highly branched ultrahigh molecular weight copolymer contained in the rubber-modified styrenic resin composition. The lower the branching ratio gM, the more branches. If the branching ratio gM exceeds 0.85, the branching is insufficient, and even if the branching ratio gM is less than 0.40 and the number of branches is increased, no further improvement effect can be obtained.

The branching ratio gM is measured by a gel permeation chromatography multi-angle laser light scattering photometer (GPC-MALS method), and the molecular weight and the turning radius are measured. The turning radius <r ² > _{br of} the rubber-modified styrenic resin composition The branching ratio gM = <r ² > _br / <r ² > _lin was calculated from the rotation radius <r ² > _{lin of the} linear polystyrene, and was calculated as an average value between 1 million and 1.5 million molecular weight. In addition, since a polymer with a large branch has a small turning radius, the value of the branching ratio gM is small. A polymer with few branches has a value close to 1. GPC-MALS was measured under the following conditions.
GPC model: Shodex DS-4 manufactured by Showa Denko KK
Column: Polymer Laboratories PLgel 10 μm MIXED-B
Mobile phase: Tetrahydrofuran Sample concentration: 0.2% by mass
Temperature: Room temperature Detector: Differential refractometer MALS Model: DAWN DSP-F manufactured by Wyatt Technology
Wavelength: 633 nm (He-Ne)
The branching ratio gM is a value calculated when the branching ratio gM of standard linear polydisperse polystyrene (manufactured by Showa Denko: NBS706) is 1. In this measurement, as in the GPC measurement, a sample from which rubber-like dispersed particles were removed was used.

  The Mz / Mw of the rubber-modified styrene resin composition is related to the content of the hyperbranched ultrahigh molecular weight copolymer, and the branching ratio gM is related to the degree of branching. It can be controlled by adjusting the blending ratio of the polymer and the polymerization conditions. By using the polyfunctional vinyl copolymer of the present invention, a highly branched ultra-high molecular weight copolymer can be efficiently produced from the initial stage of polymerization, and the degree of freedom in polymer design depending on the polymerization conditions is great. In particular, in the polymerization of the rubber-modified styrene resin composition, it is necessary to control the size of the rubber-like dispersed particles in the first half of the polymerization, and there are limitations on the polymerization temperature and the type and addition amount of the polymerization initiator. By using this polyfunctional vinyl compound copolymer, it is possible to easily produce a hyperbranched ultrahigh molecular weight product.

  The total amount of residual styrene monomer and residual polymerization solvent in the rubber-modified styrene-based resin composition of the present invention is preferably 500 μg / g or less, and more preferably 350 μg / g or less. If the total amount of residual styrene monomer and residual polymerization solvent in the rubber-modified styrenic resin composition is large, these components volatilize at the exit of the extruder or at the time of thermoforming, and the mold is contaminated or adhered to the surface of the molded product. Therefore, it is preferable to reduce as much as possible because it causes problems such as poor appearance.

The amount of the residual styrene monomer and the residual polymerization solvent was measured by dissolving 500 mg of resin in 10 ml of DMF (dimethylformamide) containing cyclopentanol as an internal standard substance and using gas chromatography under the following conditions.
Gas chromatograph: HP-5890 (manufactured by Hewlett-Packard Company)
Column: HP-WAX, 0.25 mm × 30 m, film thickness 0.5 μm
Injection temperature: 220 ° C
Column temperature: 60 ° C to 150 ° C, 10 ° C / min
Detector temperature: 220 ° C
Split ratio: 30/1
The residual styrene monomer and the polymerization solvent can be reduced depending on the configuration of the devolatilization step and the operating conditions of the devolatilization step, and are adjusted to a preferable range by adopting a configuration such as two-stage devolatilization or two-stage water injection devolatilization be able to.

  The methanol soluble content of the rubber-modified styrene resin composition of the present invention is preferably 0.5 to 4.0% by mass, and more preferably 1.0 to 2.5% by mass. When the methanol-soluble content is less than 0.5% by mass, the tensile fracture strain decreases as mechanical characteristics. When the methanol soluble content exceeds 4.0% by mass, the drawdown resistance is deteriorated and the heat resistance of the molded product is also lowered. The methanol-soluble component refers to a component that is soluble in methanol in the resin composition. For example, in addition to the styrene oligomer (styrene dimer, styrene trimer) by-produced in the polymerization process or devolatilization process of the rubber-modified styrene resin, white Various additives such as oil and silicone oil, and low molecular weight components such as residual styrene monomer and residual polymerization solvent are included. Methanol-soluble matter can be adjusted by the amount of styrene oligomer (styrene dimer, styrene trimer) generated as a by-product in the polymerization process, the amount of various additives such as white oil, the amount of residual styrene monomer and residual polymerization solvent. it can.

The methanol-soluble component is precisely weighed (mass P) of 1 g of the resin composition, 40 mL of methyl ethyl ketone is added and dissolved, and 400 mL of methanol is rapidly added to precipitate and precipitate the methanol-insoluble component (resin component). After leaving still for about 10 minutes, it is gradually filtered through a glass filter to separate methanol-insoluble matter, dried in a vacuum dryer at 120 ° C. under reduced pressure for 2 hours, and then allowed to cool in a desiccator for about 25 minutes. By measuring the mass N of the dried methanol-insoluble matter, it was determined by the following formula.
Methanol-soluble content (mass%) = (P−N) / P × 100

  The gel content of the rubber-modified styrenic resin composition of the present invention is preferably 10 to 20% by mass, and more preferably 10 to 15% by mass. The gel content represents the content of rubber-like dispersed particles constituting the dispersed phase of the rubber-modified styrenic resin composition. When the gel content is less than 10% by mass, the impact resistance is lowered, and when it exceeds 20% by mass, the draw-down resistance is reduced. The properties deteriorate and the rigidity of the molded product also decreases. The gel content can be adjusted by the concentration of the rubber-like polymer used as a raw material and the graft ratio described later.

As for the gel content, 1 g of a rubber-modified styrene resin composition was precisely weighed (mass W), and 35 ml of a 50% methyl ethyl ketone / 50% acetone mixed solution was added to dissolve the solution. -2000B (rotor: H)), centrifuged at 14,000 rpm for 30 minutes to settle the insoluble matter, and the supernatant was removed by decantation to obtain the insoluble matter, which was preliminarily kept at 90 ° C for 2 hours in a safety oven. After drying and further vacuum-drying at 120 ° C. for 1 hour in a vacuum dryer and cooling in a desiccator for 20 minutes, the mass G of the dried insoluble matter can be measured and determined as follows.
Gel content (mass%) = (G / W) × 100
The supernatant separated by decantation is placed in a 300 ml beaker, 250 ml of methanol is added rapidly, the polymer content is reprecipitated, the precipitated polymer content is suction filtered with a filter, and the polymer on the filter is placed in a vacuum dryer. The sample was then vacuum-dried for 1.5 hours or longer to obtain a sample for measurement of the aforementioned average molecular weight (Mz, Mw) and branching ratio gM.

  The graft ratio of the rubber-modified styrenic resin composition of the present invention is preferably 0.8 to 3.0, and more preferably 1.0 to 2.5. When the graft ratio is less than 0.8 or more than 3.0, the impact resistance is lowered. The graft ratio represents the ratio of polystyrene to rubber in the rubber-like dispersed particles, and represents the amount of polystyrene grafted by the rubber-like dispersed particles per unit rubber and encapsulated polystyrene. The graft ratio can be adjusted by the content of 1,2-vinyl bond in the rubbery polymer to be used, the kind and addition amount of the polymerization initiator, the type of reactor for forming rubber particles, and the like. The graft ratio was calculated from the gel content and the rubber content by the following formula: Graft rate = (gel content−rubber content) / rubber content.

  The rubber content in the rubber-modified styrenic resin composition is obtained by dissolving the rubber-modified styrenic resin composition in chloroform, adding a certain amount of iodine monochloride / carbon tetrachloride solution and leaving it in the dark for about 1 hour. Potassium iodide solution is added, excess iodine monochloride is titrated with 0.1N sodium thiosulfate / ethanol aqueous solution, and the amount of iodine monochloride added can be determined.

  The swelling ratio SR of the rubber component in the rubber-modified styrenic resin composition of the present invention is preferably 8 to 16, and more preferably 9 to 14. The swelling ratio represents the degree of crosslinking of the rubber-like dispersed particles. If the swelling ratio is less than 8, the impact resistance is lowered, which is not preferable. On the other hand, when the swelling ratio exceeds 16, the rubber-like dispersed particles are greatly deformed with respect to the flow direction during the molding process, and are easily broken along the flow direction. The swelling ratio can be adjusted by the temperature and residence time in the devolatilization step after leaving the polymerization step. Further, depending on the type of rubbery polymer used as a raw material, the high-cis polybutadiene rubber having a low 1,2-vinyl bond content tends to have a higher swelling ratio than the low-cis rubber.

The swelling ratio SR was precisely weighed 1 g of a rubber-modified styrenic resin composition, dissolved by adding 30 ml of toluene, and the solution was centrifuged at 14,000 rpm with a centrifuge (H-2000B (rotor: H) manufactured by Kokusan). Centrifuge for 30 minutes to settle the insoluble matter, remove the supernatant by decantation, measure the mass S of the insoluble matter swollen with toluene, and then measure the insoluble matter swollen with toluene in a safety oven at 90 ° C. 2 hours, followed by vacuum drying at 120 ° C. for 1 hour in a vacuum dryer, cooling in a desiccator for 20 minutes, and then measuring the dry mass D of the insoluble matter to obtain as follows: it can.
Swell ratio SR = S / D

  The particle diameter of the rubber-like dispersed particles of the rubber-modified styrene resin composition of the present invention is preferably 1.0 to 5.0 μm, and more preferably 1.5 to 3.5 μm. When the particle diameter is less than 1.0 μm, the impact resistance is lowered, and when it exceeds 5.0 μm, the gloss is lowered and the appearance is deteriorated. The particle size of the rubber-like dispersed particles is the 1,2-vinyl bond content and solution viscosity of the rubber-like polymer used, the stirring speed and the polymerization initiator in the region (phase transition) where the rubber-like dispersed particles are formed in the polymerization step. It can be controlled by the type and amount of addition, the type and amount of chain transfer agent, and the like. Moreover, the particle diameter can be reduced by using styrene-butadiene rubber bonded with styrene as the rubbery polymer.

  The particle size of the rubber-like dispersed particles was obtained by staining a rubber-modified styrene resin composition with osmium tetroxide, and using a transmission electron microscope (TEM), taking a TEM photograph of the rubber-like dispersed particles in an ultrathin section, The diameter of the rubber-like dispersed particles was measured, and the particle diameter was calculated as the volume-based median diameter.

  The melt mass flow rate (MFR) measured under the conditions of 200 ° C. and 49 N load of the styrene resin composition of the present invention is preferably 1.0 g / 10 min or more and less than 5.5 g / 10 min. More preferably, it is 5 g / 10 min or more and less than 4.0 g / 10 min. If it is less than 1.0 g / 10 minutes, the fluidity is insufficient, the flow becomes unstable during extrusion of the parison, and melt fracture tends to occur, which is not preferable. 5.5 g / 10 min or more is not preferable because drawdown tends to occur. MFR can be measured based on JIS K-7210.

  The melt tension value measured at 190 ° C. of the styrenic resin composition of the present invention is preferably 13 to 20 gf. The maximum melt draw ratio is preferably 30. If the melt tension value is less than 13 gf, the drawdown resistance is poor, and the thickness of the molded product tends to be non-uniform. When the melt tension value exceeds 20 gf, the fluidity tends to be unbalanced. On the other hand, when the maximum melt draw ratio is less than 30, the parison is insufficiently stretched, and the parison tends to break during molding or the mold reproducibility of the molded product tends to deteriorate. As long as the balance with the melt tension can be achieved, the upper limit value of the maximum melt draw ratio is not limited.

  The melt tension value uses “Capillograph 1B type” manufactured by Toyo Seiki, barrel temperature 190 ° C., barrel diameter 9.55 mm, capillary length: L = 10 mm, capillary diameter: D = 1 mm (L / D = 10), The resin is extruded at an extrusion speed of 10 mm / min in the barrel, the load measuring part is set 60 cm below the die, the strand-shaped resin flowing out from the capillary is set in the winder, and the winding line speed is 4 m / min. Gradually increase the speed from the minute and measure the load until the strand breaks. Since the load is stabilized at a constant value as the winding linear speed is increased, the range in which the load is stable is averaged to obtain a melt tension value. Further, the ratio of the winding linear velocity (m / min) when the strand broke and the flow velocity (m / min) in the capillary was defined as the maximum melt draw ratio (times).

  When producing the rubber-modified styrenic resin composition of the present invention, from the viewpoint of controlling the polymerization reaction, a polymerization initiator such as a polymerization solvent or an organic peroxide, or a chain transfer agent such as an aliphatic mercaptan, is necessary. Can be used.

  The polymerization solvent is used for reducing the viscosity of the reaction product in continuous polymerization. Examples of the organic solvent include alkylbenzenes such as benzene, toluene, ethylbenzene and xylene, ketones such as acetone and methyl ethyl ketone, hexane and cyclohexane. Aliphatic hydrocarbons such as can be used.

  In particular, when it is desired to increase the amount of the polyfunctional vinyl copolymer added, it is preferable to use a polymerization solvent from the viewpoint of suppressing gelation. Thereby, the addition amount of the polyfunctional vinyl copolymer shown previously can be increased dramatically, and a gel is hardly generated.

  Although the usage-amount of a polymerization solvent is not specifically limited, From a viewpoint of controlling gelatinization, it is usually preferable that it is 1-50 mass% as a composition in a polymerization reactor, and 3-25 mass % Is more preferable. When it exceeds 50% by mass, productivity tends to be remarkably reduced, and the molecular weight of the rubber-modified styrene resin tends to be excessively reduced.

  As the polymerization initiator, a radical polymerization initiator is preferable. For example, 1,1-di (t-butylperoxy) cyclohexane, 2,2-di (t-butylperoxy) butane, 2,2- Peroxyketals such as di (4,4-di-t-butylperoxycyclohexyl) propane, 1,1-di (t-amylperoxy) cyclohexane, cumene hydroperoxide, t-butyl hydroperoxide, etc. Alkyl peroxides such as hydroperoxides, t-butylperoxyacetate, t-amylperoxyisononanoate, t-butylcumyl peroxide, di-t-butyl peroxide, dicumyl peroxide, di-t -Dialkyl peroxides such as hexyl peroxide, t-butylperoxyacetate Peroxyesters such as t-butyl peroxybenzoate and t-butylperoxyisopropyl monocarbonate, peroxycarbonates such as t-butyl peroxyisopropyl carbonate and polyether tetrakis (t-butyl peroxycarbonate) N, N′-azobis (cyclohexane-1-carbonitrile), N, N′-azobis (2-methylbutyronitrile), N, N′-azobis (2,4-dimethylvaleronitrile), N, N '-Azobis [2- (hydroxymethyl) propionitrile] and the like can be mentioned, and these can be used alone or in combination.

  Furthermore, a chain transfer agent can be used to adjust the molecular weight of the rubber-modified styrene resin composition of the present invention, and examples thereof include aliphatic mercaptans, aromatic mercaptans, pentaphenylethane, α-methylstyrene dimer, and terpinolene.

  As described above, the rubber-modified styrene resin composition of the present invention is obtained by continuously polymerizing a polyfunctional vinyl copolymer added to a styrene monomer in which a rubber component is dissolved. For the purpose of imparting or improving the strength, it is also possible to use a prepolymerized styrenic resin, an additive other than the liquid paraffin described above, or the like by melt blending with an extruder or dry blending in a pellet state.

  Examples of the above styrene resins and additives include GP-PS resins for improving fluidity, rubber-reinforced aromatic vinyl resins such as MBS resin containing rubber for improving strength, and aromatics such as SBS. A vinyl-type thermoplastic elastomer is mentioned. Examples of the additive include higher fatty acids such as stearic acid, zinc stearate, calcium stearate, magnesium stearate and salts thereof, lubricants such as ethylene bisstearyl amide, plasticizers such as liquid paraffin, and antioxidants.

  The rubber-modified styrenic resin composition of the present invention is for blow molding, but is particularly suitable for large-scale extrusion blow molding, and is suitable for an intermittent extrusion method (accumulator method). By using the rubber-modified styrenic resin composition of the present invention, even a large molded product having a parison weight exceeding 10 kg has good drawdown resistance, and a molded product having a uniform thickness can be obtained. The large blow molding of the present invention means molding performed using a molding machine having an accumulator capacity of 10L or more and less than 50L. Typical molded products include exterior parts and units such as automobile bumpers and air spoilers. Examples are buses and ceilings of unit baths.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to these Examples.

Synthesis example (polyfunctional vinyl copolymer A)
3.1 mol (399.4 g) of divinylbenzene, 0.7 mol (95.1 g) of ethylvinylbenzene, 0.3 mol (31.6 g) of styrene, 2.3 mol (463.5 g) of 2-phenoxyethyl methacrylate Then, 974.3 g of toluene was put into a 3.0 L reactor, 42.6 g of boron trifluoride diethyl ether complex was added at 50 ° C., and reacted for 6.5 hours. After stopping the polymerization reaction with a sodium hydrogen carbonate solution, the oil layer was washed three times with pure water, and the reaction mixture was poured into a large amount of methanol at room temperature to precipitate a polymer. The obtained polymer was washed with methanol, filtered, dried and weighed to obtain 372.5 g of a polyfunctional vinyl copolymer A. This polyfunctional vinyl copolymer A has a weight average molecular weight Mw of 8,000, a molar fraction of the structural unit (a1) containing a vinyl group derived from a divinyl compound is 0.44, and a terminal component derived from 2-phenoxyethyl methacrylate at the end. The double bond (a2) was 0.03, and the combined molar fraction (a3) of both was 0.47. Further, the radius of inertia of the copolymer at a weight average molecular weight of 8,000 was 6.4 nm. The ratio of the mole fraction of the double bond of this copolymer to the radius of inertia is 13.6, and the polyfunctional vinyl in this synthesis example is compared with the fact that the inertia radius at a linear molecular weight of 8000 is 15 nm. It can be seen that the copolymer has a branched structure.

Production Examples (Examples and Comparative Examples)
(Production of styrene resin compositions PS-1 to PS-10)
The first reactor, which is a complete mixing tank, the second reactor and the third reactor, which are tower-type plug flow reactors with stirring blades, and the fourth reactor, which is a static mixer type plug flow reactor, are connected in series. To form a polymerization step. The capacity of each reactor was 25 L for the first reactor, 40 L for the second reactor, 50 L for the third reactor, and 50 L for the fourth reactor. A raw material solution was prepared with the raw material composition described in Table 1, and the raw material solution was continuously supplied to the first reactor at a flow rate described in Table 1. As polybutadiene, Diene 55AE manufactured by Asahi Kasei Chemicals Corporation was used. The polymerization initiator and the chain transfer agent were added to the raw material solution at the entrance of the third reactor so as to have the addition concentration shown in Table 1 (concentration based on mass relative to the raw styrene), and mixed uniformly. In Table 1, polymerization initiator-1 is 2,2-di (4,4-t-butylperoxycyclohexyl) propane (Pertetra A manufactured by NOF Corporation), and polymerization initiator-2 is t-butylkumi. Ruperoxide (Nippon Oil Co., Ltd., Perbutyl C), and t-dodecyl mercaptan is a chain transfer agent. As the crosslinking agent, the polyfunctional vinyl copolymer A or divinylbenzene (DVB) obtained in the above synthesis example is used, and the addition concentration (concentration based on the raw material styrene mass) shown in Table 1 at the inlet of the first reactor. It added to the raw material solution so that it might become.
Subsequently, to the solution containing the polymer continuously taken out from the fourth reactor, white oil was added / mixed so as to have the concentration shown in Table 1 with respect to the polymer, and a preheater constituted by two stages in series. After introducing unreacted styrene and ethylbenzene by adjusting the temperature of the preheater to the resin temperature shown in Table 1 and adjusting to the pressure shown in Table 1, The strand was extruded from the die into a strand shape, and the strand was cooled and cut into a pellet by a cold cut method. PS-1 to PS-3 are examples, and PS-4 to 10 are comparative examples.

In addition, when the presence or absence of a gel-like substance in continuous operation was confirmed under each condition, a lot of gel-like substances were included in the strand from the porous die at the time of 24 hours under the conditions of PS-6 and PS-10, It was difficult to continue driving.
Moreover, it can be seen from the molecular weights Mw and Mz of the outlets of the reactors and the pellets that by using the polyfunctional vinyl copolymer, a highly branched ultrahigh molecular weight copolymer is efficiently produced from the initial stage of polymerization.

Example 1
The styrene resin composition PS-1 was plasticized with a 90 mmφ single screw extruder at a cylinder temperature of 190 ° C., the resin was accumulated in an accumulator, and a parison was extruded from a 300 mmφ die. The weight of the parison was 12 kg, and the size of the molded product was 2000 × 500 × 50 mm. The flow stability was evaluated based on the state of melt fracture during the parison extrusion (○: No melt fracture occurred, △: Partial melt fracture occurred, ×: Large fluctuation in thickness in the flow direction due to melt fracture occurrence) . Also, the drawdown resistance was evaluated from the parison state (○: No drawdown, stable continuous molding possible, Δ: Molding state unstable due to drawdown, x: Drawdown markedly, continuous molding impossible). Furthermore, the molded product was cut, and the wall thickness at the top and bottom of the parison was measured and evaluated as the uniformity of the wall thickness (◯: the wall thickness was uniform, x: the wall thickness was not uniform).
The Charpy impact strength was determined by Method 1eA (edgewise impact) based on JIS K7111. The Vicat softening temperature was determined based on JIS K 7206 under conditions of a heating rate of 50 ° C./h and a load of 50N.

Examples 2-3 and Comparative Examples 1-5
Evaluation was performed in the same manner as in Example 1 except that the styrenic resin composition having the name shown in Table 2 was used. Table 2 shows the evaluation results of the characteristics and molding characteristics of the styrenic resin compositions obtained in the production examples.

Claims (3)

  100 ppm to 3000 ppm of solvent-soluble polyfunctional vinyl copolymer having two or more vinyl groups in one molecule and having a branched structure on average, to a monovinyl compound essentially containing styrene in which a rubber component is dissolved The solvent-soluble polyfunctional vinyl copolymer and the monovinyl compound are polymerized by continuously supplying one or more raw material solutions to a polymerization reactor that is continuously arranged and advancing the polymerization reaction. A rubber-modified styrenic resin composition comprising a hyperbranched ultra-high molecular weight copolymer produced by polymerization and a linear polymer produced by polymerizing the monovinyl compound, and having a weight average molecular weight (Mw) of 150,000 to 40 The ratio (Mz / Mw) of the Z average molecular weight (Mz) to the weight average molecular weight (Mw) is 2.2 to 5.0, and the branching ratio gM at a molecular weight of 1,000,000 to 1,500,000 is 0.85 to 0.40. In The rubber modification for highly branched blow molding is characterized in that the melt mass flow rate (MFR) measured at 200 ° C. under a load of 49 N is 1.0 g / 10 min or more and less than 5.5 g / 10 min. Styrenic resin composition. A solvent-soluble polyfunctional vinyl copolymer is obtained by polymerizing a monovinyl compound copolymerizable with a divinyl compound, and a pendant vinyl group-containing unit derived from the divinyl compound represented by the following formula (a1) is contained in the structural unit. The mole fraction is contained in the range of 0.10 to 0.50, and the ratio of the inertial radius (nm) in the weight average molecular weight to the mole fraction is in the range of 10 to 80. 2. A rubber-modified styrenic resin composition for high-branching blow molding according to 1.

(In the formula, R ¹ represents a hydrocarbon group derived from a divinyl compound.)   A blow molded product obtained by molding the rubber-modified styrenic resin composition for highly branched blow molding according to any one of claims 1 to 2.