JPH07316390A - Thermoplastic resin composition - Google Patents

Abstract

PURPOSE:To obtain the composition, comprising a mixture of a specific graft copolymer with a specified copolymer and capable of manifesting excellent formability in forming a sheet produced by an extrusion molding method into the objective shape according to a vacuum (pressure) forming method, CONSTITUTION:This thermoplastic resin composition comprises a mixture of (A) a graft copolymer obtained by copolymerizing a mixture of an aromatic vinyl monomer (e.g. styrene) with a vinyl cyanide monomer (e.g. acrylonitrile) and, as necessary, monomers copolymerizable therewith (e.g. methyl acrylate) with (B) a copolymer prepared by copolymerizing the aromatic vinyl monomer with the vinyl cyanide monomer and, as necessary, the monomers copolymerizable therewith. The copolymer (B) is a mixture of a copolymer having 50000-300000 weight-average molecular weight with a copolymer having 500000-5000000 weight-average molecular weight.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a thermoplastic resin composition. More specifically, the present invention relates to an ABS resin-based thermoplastic resin composition that exhibits excellent moldability when a sheet manufactured by an extrusion molding method is molded into a target shape by a vacuum (pressure) molding method.

[0002]

2. Description of the Related Art A graft copolymer obtained by graft-polymerizing a mixture of a styrene monomer and an acrylonitrile monomer on a rubber-like polymer, and a copolymer of a mixture of a styrene monomer and an acrylonitrile monomer. , A so-called graft blend type ABS resin and the like, are widely used for the inner box of the electric refrigerator. When manufacturing this inner box, first, a sheet is manufactured by an extrusion molding method, and then this sheet is molded into a target shape by a vacuum (compressed air) molding method.
In molding, a portion having a high draw ratio such as a corner portion of a box tends to have a non-uniform wall thickness. Therefore,
The thermoplastic resin used is required to have a high elongation viscosity when highly stretched in a high temperature region under molding conditions.

However, it is difficult to say that even the conventional ABS resin and the like can sufficiently satisfy these physical property values. In recent years, as a heat insulating foaming agent for electric refrigerators, so-called alternative CFCs that are difficult to destroy have been adopted in place of conventional CFCs that easily destroy the ozone layer, and a resin material with a high acrylonitrile component ratio has been developed as a suitable ABS resin. There is a high proportion of this acrylonitrile component A
The BS resin material has a problem in moldability particularly in the above-mentioned vacuum molding.

[0004]

SUMMARY OF THE INVENTION In view of the above situation, the present invention provides a thermoplastic resin having a good moldability such that a portion having a high draw ratio such as a corner of a box has a uniform thickness during vacuum forming. To provide.

[0005]

The above object of the present invention is to provide aromatic vinyl monomers, vinyl cyanide monomers, and, in the presence of a rubber-like polymer, a monomer which can be copolymerized therewith. A copolymer obtained by polymerizing a graft copolymer (A) obtained by polymerizing a polymer mixture, an aromatic vinyl monomer, a vinyl cyanide monomer, and optionally a monomer mixture copolymerizable therewith. Consisting of a mixture with the polymer (B),
In addition, this copolymer (B) has a weight average molecular weight of 50,000 to
With a mixture of 300,000 copolymer (b-1) and copolymer (b-2) having a weight average molecular weight of 500,000 to 5,000,000,
Can be resolved.

The present invention will be described in detail below. The resin composition according to the present invention is a so-called graft blend type A containing a graft copolymer (A) and a copolymer (B).
In the BS resin, it is essential that the copolymer (B) contains a component (b-1) having a usual weight average molecular weight and a component (b-2) having a high weight average molecular weight.

Aromatic vinyl monomers constituting the graft copolymer (A) and the copolymer (B) contained in the resin composition according to the present invention include styrene, α-methylstyrene, dimethylstyrene, Examples include vinyltoluene and the like, and styrene is typically representative. Examples of the vinyl cyanide monomer include acrylonitrile and methacrylonitrile, and acrylonitrile is typical. As the monomer copolymerizable with these, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, hydroxyethyl methacrylate,
Examples thereof include hydroxybutyl methacrylate, hydroxypropyl methacrylate, maleimide, N-phenylmaleimide and the like. These copolymerizable monomers may be one kind or a mixture of two or more kinds.

Graft copolymer (A) and copolymer (B)
The ratio of the aromatic vinyl monomer, the vinyl cyanide monomer and the monomer copolymerizable with these constituting the and is 50 to 80:50 to 20: 0 to 15 (note The total amount of the monomers is 100% by weight.), But particularly preferably 50 to 65:50 to 35: 0.
The range is from -10.

The rubber-like polymer constituting the graft copolymer (A) includes polybutadiene, butadiene-styrene copolymer, butadiene-acrylonitrile copolymer,
Carbon number 2 such as butadiene-based polymers such as polyisoprene and polychloroprene, propyl acrylate polymers, butyl acrylate polymers and amyl acrylate polymers
To 12 alkyl acrylate polymers, ethylene-propylene-conjugated diene rubbers and the like.
The rubbery polymer is not limited to those exemplified above. The rubber-like polymer may be one kind or a mixture of two or more kinds.

The method for producing the graft copolymer (A) includes emulsion polymerization method, suspension polymerization method, bulk polymerization method, emulsion-suspension polymerization method, bulk-suspension polymerization method, emulsion-bulk polymerization method and the like. The known polymerization method of (1) is used in combination with the batch type and / or the continuous type. The method for producing the graft copolymer (A) is preferably an emulsion polymerization method. A latex rubber-like polymer is used, and one of an aromatic vinyl monomer and a monomer copolymerizable therewith is used. Alternatively, it is preferable to polymerize a mixture of two or more kinds of monomers by an emulsion polymerization method.

The composition ratio of the rubber-like polymer to the monomer mixture in the graft copolymer (A) is 5 to 3 in the rubber-like polymer.
It is preferred to choose in the range of 95-70% by weight of the monomer mixture in the presence of 0% by weight. At this time, the particle size of the graft copolymer is usually preferably selected in the range of 0.1 to 0.65 μm. The case where the graft copolymer (A) is produced by an emulsion polymerization method will be described in detail below. In the emulsion polymerization, an emulsifier, a polymerization initiator and, if necessary, a chain transfer agent are used. It is performed in the temperature range of 90 ° C. As the emulsifier that can be used, any emulsifier that can be used when polymerizing a vinyl-based monomer by an emulsion polymerization method can be used without restriction.

Examples of the polymerization initiator include persulfuric acid, peracetic acid, perphthalic acid, potassium persulfate, hydrogen peroxide, benzoyl peroxide, chlorobenzoyl peroxide, acetyl peroxide,
Examples thereof include lauroyl peroxide, peroxides such as hydroperoxide-t-butyl, and azo compounds such as azobisisobutyronitrile. These may be used in combination of two or more. Also, a redox system in which a peroxide and a reducing agent are combined can be adopted. The amount of these polymerization initiators used is usually selected in the range of 0.1 to 5% by weight based on the monomer mixture.

Specific examples of the chain transfer agent include mercaptans such as n-octyl mercaptan, n-dodecyl mercaptan and t-dodecyl mercaptan, terpinolene and α-methylstyrene dimer. The amount used of these is usually relative to the monomer mixture,
It is selected in the range of 0.1 to 5% by weight. The copolymer (B) contained in the resin composition according to the present invention has a weight average molecular weight of 50,000 to 300,000 (b-1) and a weight average molecular weight of 1 to 20% by weight of 500,000. ~ 5 million things (b-
It is essential that 2) is a mixed mixture. The weight average molecular weight of the copolymer in the conventional graft blend type ABS resin includes about 50,000 to 300,000, but the present invention is characterized in that it further contains a high molecular weight. The above range is essential for the weight average molecular weight of the component (b-2), and a weight average molecular weight of 3 to 20 times, preferably 5 to 15 times the molecular weight of (b-1) is preferable. In the present invention, the weight average molecular weight means a polystyrene equivalent molecular weight measured by gel permeation chromatography (GPC).

Each component of the graft copolymer (A), the copolymer (b-1) and the copolymer (b-2) contained in the resin composition according to the present invention does not necessarily have to be one kind. Alternatively, two or more polymers may be used in combination. For example, as the graft copolymer (A), different rubber-like polymers may be used, and two kinds of graft copolymers obtained by graft polymerization may be used in combination. Further, a graft chain polymer of the graft copolymer (A), a copolymer (b-1)
Also, the components of the copolymer (b-2) do not have to be the same, but generally, it is desirable that the copolymer components are almost the same.

The copolymer (b-1) may be a by-product when the graft copolymer (A) is produced, or may be an AS resin produced separately. In the latter case,
The manufacturing method thereof may be a known method. Specifically, an aromatic vinyl monomer, a vinyl cyanide monomer, and optionally another monomer copolymerizable therewith, in the presence of a polymerization initiator and, if necessary, a chain transfer agent, Examples thereof include a method of producing by emulsion polymerization method, suspension polymerization method or bulk polymerization method. As the polymerization initiator and the chain transfer agent used at this time, the same ones as those used for producing the above graft copolymer (A) can be mentioned.

The method for producing the copolymer (b-2) is basically the same as that for the copolymer (b-1), but (b-2) is required to be a particularly high molecular weight polymer. Therefore, usually, by the emulsion polymerization method, the amount of the polymerization initiator used is relatively small,
It is preferable to carry out the polymerization reaction in a low temperature range. To adjust the resin composition according to the present invention, (1) separately prepared powder, flakes, a method of measuring the predetermined amount of beaded polymer by melt mixing, (2) each separately A method in which a predetermined amount of the produced latex polymer is weighed, mixed and coagulated to form a powder, and (3) the graft copolymer (A) and the copolymer (b)
-2) is mixed and coagulated in the state of latex to form a powder, and the copolymer (b-1) is melt-mixed therewith,
(4) Copolymer (b-2) adjusted in advance to a graft polymerization system
And a method of producing the graft copolymer (A) in the presence of the latex.

The content ratio of each component constituting the resin composition according to the present invention is in the range of 20 to 65:80 to 35 by weight ratio of the graft copolymer (A) to the copolymer (B). And the copolymer (b-2) is in the range of 1 to 20% by weight (however, the total amount of each component is 100% by weight). When the ratio of the component (B) to the component (A) is out of the above range, the physical properties such as impact resistance and tensile strength are poor, and the moldability is poor. If the proportion of the component (b-2) in the resin composition is too low, the moldability during vacuum molding cannot be sufficiently improved, and conversely, if it is too high, the fluidity decreases, which is not preferable. Particularly preferable range is 2 to 15% by weight.

When the components constituting the resin composition according to the present invention are melt-mixed, the mixture of these components is
A single-screw extruder, an extruder such as a twin-screw extruder, or a processing device such as a Banbury mixer, a kneader / ruder, a pressure kneader, a kneader such as a heating roll, and the like can be further melt-mixed to obtain a resin composition. it can. Furthermore, the resin composition according to the present invention includes a lubricant of a type and an amount that does not impair the properties of the resin composition of the present invention, a release agent, a colorant, an antistatic agent, a flame retardant, an ultraviolet absorber, a heat stabilizer, Various resin additives such as a light resistance stabilizer can be added in an appropriate combination.

The resin composition according to the present invention is produced by an injection molding method,
It can be used as a raw material resin when producing a molded article by various molding methods such as an extrusion molding method and a thermoforming method. For example, office equipment housings, office equipment such as chassis, household products such as vanities, electric refrigerator inner boxes, and other electric appliances, and motorcycles such as cowlings and vending machine inner racks. It is suitable for manufacturing industrial parts such as ships and machines, and is particularly suitable for use as an inner box of an electric refrigerator in which a sheet is formed by an extrusion molding method and the sheet is manufactured by a vacuum forming method.

[0020]

As described above, the present invention has the following particularly remarkable effects, and its industrial utility value is extremely large. (1) The resin composition according to the present invention has a wide range of moldability when a sheet manufactured by an extrusion molding method is molded into a target shape by a vacuum molding method, and is suitable as a material for a vacuum molding method. (2) When a sheet made from the resin composition according to the present invention is formed into a desired shape by a vacuum forming method, a molded product having a good moldability and less uneven thickness can be obtained.

[0021]

EXAMPLES Next, the present invention will be specifically described based on examples, but the present invention is not limited to the examples described below as long as the gist thereof is not exceeded. In the following examples, "part" means "part by weight" and "%" means "% by weight".

Further, the copolymer (b-1) and the copolymer (b
The weight average molecular weight of -2) is measured under the following conditions using a gel permeation chromatography (GPC) device. Device: HLC-802A (manufactured by Tosoh Corporation) Column: Two TSK gel GMHXL in series Temperature: 40 ° C Detection: Differential refractive index Solvent: Tetrahydrofuran Concentration: 1% by weight Calibration curve: Conforms to standard PS (manufactured by Tosoh Corporation) (The molecular weight is PS
Converted Value) In the following examples, various physical property values of the resin composition were evaluated by the methods described below.

* Tensile strength According to JIS K7113. Unit is Kg / cm ² . * Impact strength In accordance with JIS K7110, it means Izod impact strength (with notch). 1/8 inch test piece. Unit is Kg / cm / cm. * VICAT softening point Based on JIS K7206. Unit ° C. * Flowability (MFR) Based on JIS K7210. Temperature 220 ℃, load 1
It represents the flow rate for 10 minutes under the condition of 0 kg. Unit g / 1
0 minutes.

* Vacuum Formability A sheet having a thickness of 2 mm was produced from the resin composition by an extrusion molding method, and this sheet was removed from the sheet using a vacuum forming machine (FC-4APA manufactured by Asano Laboratory, plug assist type). Change the heating time of the sheet (50, 60, 70, 80
Seconds), opening diameter 300 mm, bottom diameter 150 mm, depth 2
A molded product having a bucket shape of 50 mm and having a width of 6 mm extending from the opening to the bottom and protruding outward was provided to oppose the wall surface. About the obtained molded product,
(1) The portion farthest from the rib was vertically cut from the opening to the bottom, and the minimum wall thickness measured on the cut surface was shown. The larger the measured value, the more preferable. (2) Visually inspect the sink marks in the ribs (molding-whether or not they are molded according to the shape of the vacuum mold) with the naked eye, and select the ones with good sinking (the ones with good molding) as "rib "Sink" ○, "Sink"
The bad ones (the ones with bad shape) are "rib sinks"
Displayed as x, respectively.

The moldability region is a heating time that is sufficient to obtain a molded product that has sufficient "rib sink marks" and no uneven thickness when vacuum molding is performed. The wider this is, the better the vacuum formability is. Production Example of Graft Polymer (A)

A-1 (1) Manufacture of rubbery polymer A deionized water was added to a stainless steel autoclave with a capacity of 5 L equipped with a stirrer, a heating / cooling device, a thermometer, each raw material and an auxiliary charging device. Parts, higher fatty acid soap (sodium salt of fatty acid containing 18 carbon as a main component) 4.0
Parts, 0.075 parts of sodium hydroxide, and with stirring
After purging with nitrogen, the internal temperature was raised to 68 ° C. When the internal temperature reached 68 ° C, separately adjusted 1,3-butadiene 90
Part, styrene 10 parts and t-dodecyl mercaptan 0.
After charging 20% of the monomer mixture consisting of 3 parts,
0.135 parts of potassium persulfate was added. An exotherm occurred after a few minutes, confirming the initiation of polymerization.

80% of the monomer mixture was continuously added from the point 1 hour after the addition of potassium persulfate, and the addition was completed in 6 hours. After the addition of the monomer mixture was completed, the internal temperature was raised to 80 ° C., and the polymerization was further continued for 1 hour. The obtained rubber-like polymer latex has a solid content concentration of 3
The average particle size of the rubber was 9.5% and 0.08 μm.

(2) Production of Graft Polymer A rubber-like polymer obtained in the above (1) was placed in a reactor having a capacity of 5 L equipped with a stirrer, a heating / cooling device, a thermometer, each raw material and an auxiliary charging device. Combined latex was charged with 100 parts of solid particles of acetic anhydride having an average particle size of 0.27 μm and solidified, and 347 parts of deionized water (including water in latex), and the mixture was stirred and the internal temperature was increased. 70 ℃
The temperature was raised to. When the internal temperature reached 60 ° C on the way, sodium pyrophosphate 1.0 dissolved in 20 parts of deionized water
Parts, 0.25 parts dextrose and 0.0 ferrous sulfate
An aqueous solution consisting of 1 part was added.

When the internal temperature reached 70 ° C., styrene 6
The continuous addition of a monomer mixture consisting of 0 part, 40 parts of acrylonitrile and 0.2 part of t-dodecyl mercaptan was started and completed in 2 hours and 30 minutes. Over the same time as the continuous addition of this monomer mixture, it consists of deionized water 35 parts, disproportionated potassium rosinate soap 1.8 parts, cumene hydroperoxide 0.5 parts, potassium hydroxide 0.37 parts. The solution was added continuously.

After these continuous additions were completed, the reaction was continued at 70 ° C. for a further 30 minutes, then the internal temperature was cooled to complete the reaction, and the graft polymer latex had a solid content concentration of 39.5%. It was This graft polymer latex is
-1.

A-2 (1) Manufacture of rubber-like polymer 151 deionized water was placed in a stainless steel autoclave having a capacity of 5 L equipped with a stirrer, a heating / cooling device, a thermometer, each raw material and an auxiliary material charging device. Parts, higher fatty acid soap (sodium salt of fatty acid containing 18 carbon as the main component) 2.0
And 1 part of sodium hydrogencarbonate were charged, the mixture was replaced with nitrogen under stirring, and the internal temperature was raised to 75 ° C. Potassium persulfate 0.
135 parts were added, and after 5 minutes, 100 parts butyl acrylate and 0.05 allyl methacrylate were added.
Parts, 4 parts of a monomer mixture consisting of 1.2 parts of t-dodecyl mercaptan. After a few minutes a fever occurred,
The initiation of polymerization was confirmed.

20 minutes after the charging of the monomer mixture, continuous addition of the remaining monomer mixture was started for 3 hours and 20 hours.
The addition was completed in minutes. At 2 hours on the way, 1 part of fatty acid soap was added, and at 2 hours and 30 minutes, 0.015 part of potassium persulfate was added. After the addition of the monomer mixture was completed, the internal temperature was raised to 80 ° C., and the polymerization was further continued for 1 hour. The obtained rubber-like polymer latex had a solid content concentration of 39.5%, an average particle diameter of 0.10 μm, and a gel content of 0%.

(2) Production of Graft Polymer A rubber-like polymer obtained in the above (1) was placed in a reactor having a capacity of 5 L equipped with a stirrer, a heating / cooling device, a thermometer, each raw material and an auxiliary charging device. Combined latex as solid content 100
Parts, deionized water 402 parts (including water in latex) sodium pyrophosphate 2.2 parts, glucose 0.55
And 0.022 part of ferrous sulfate were charged, and the internal temperature was raised to 70 ° C. with stirring. When the internal temperature reached 70 ° C, continuous addition of a monomer mixture consisting of 154 parts of styrene, 66 parts of acrylonitrile, 0.44 parts of t-dodecyl mercaptan and 1.1 parts of cumene hydroperoxide was started, and 3 It ended in 30 minutes. A solution of 3.96 parts of disproportionated potassium rosinate soap was continuously added to 88.2 parts of deionized water over the same time period as the continuous addition of this monomer mixture.

After these continuous additions were completed, the reaction was continued at 70 ° C. for another 30 minutes, then the internal temperature was cooled to complete the reaction, and the graft polymer latex had a solid content concentration of 35.4%. It was This graft polymer latex is
-2. Production example of copolymer (B)

B-1 Acrylonitrile 4 under stirring in a stainless steel autoclave with a capacity of 5 L equipped with a heating / cooling device, a curved turbine type stirring device, a thermometer, each raw material and an auxiliary material charging device.
5 parts, styrene 10 parts, di-tertiary butyl-p-
Cresol 0.02 parts, acrylic acid / acrylic acid-2-
0.03 parts of ethylhexyl copolymer, 0.4 parts of sodium bromide and 70 parts of deionized water were charged, and the inside of the autoclave was replaced with nitrogen. Under stirring, the internal temperature was raised to 106 ° C,
0.15 parts of 1-azo-1-cyanocyclohexane dissolved in a small amount of styrene was added to start the polymerization reaction. Immediately after the polymerization was started, 36 parts of styrene was continuously added at a constant rate for 4 hours and 30 minutes, and the internal temperature was adjusted to 1
The temperature was raised to 28 ° C. After the continuous addition of styrene was completed, the internal temperature was raised to 145 ° C over 45 minutes, and stripping was performed for 1 hour while maintaining the internal temperature at 145 ° C. After completion of stripping, the mixture was cooled, filtered, washed with water, and dried to obtain a bead-shaped copolymer (b-1). The weight average molecular weight of this copolymer was 120,000.

B-2 In a glass autoclave having a volume of 5 L, 1 part of deionized water was added.
23 parts, 1.2 parts of disproportionated potassium rosinate soap, and 4.0 parts of acrylonitrile were charged, nitrogen substitution was carried out with stirring, and the internal temperature was raised to 50 ° C. After adding 0.075 parts of potassium persulfate, a monomer mixture consisting of 60 parts of styrene and 40 parts of acrylonitrile was continuously added at a constant rate for 6 hours and 30 minutes. After 30 minutes from the start of continuous addition, a solution of deionized water (26 parts), disproportionated potassium rosinate soap (1.8 parts) and potassium persulfate (0.175 parts) was added at a constant rate for 6 hours and 30 minutes. Added continuously. After completion of continuous addition of this solution, the reaction is continued for another 1 hour,
The reaction was terminated by cooling, and a copolymer (b-2) latex having a solid content of 40.5 and a weight average molecular weight of 1.2 million was obtained.

Examples 1 to 4 and Comparative Examples 1 and 2 The latexes of the above graft polymer (A) and the copolymer (b-2) were mixed in the proportions shown in Table 1 (in terms of solid content), 2.5 parts of anti-aging agent was added to the obtained mixed latex, and then the mixture was added to a stirring magnesium sulfate aqueous solution heated to 95 ° C. for coagulation, and the coagulated product was washed with water and dried to give a white powdery resin. A composition was obtained. The copolymer (b-1) was mixed with the obtained resin composition in the proportions shown in Table-1, kneaded with a twin-screw extruder, and pelletized.

Using this pellet, a test piece for measuring physical properties was molded by an injection molding machine, and the physical properties were evaluated by the evaluation method described above. The results are shown in Table-1. Also, a sheet was formed by an extruder using this pellet, and the vacuum formability of this sheet was evaluated by the evaluation method described above. The results are shown in Table-1.

[0039]

[Table 1]

The following is clear from Table-1. 1. The resin composition according to the present invention is not only excellent in impact resistance, heat resistance, and fluidity and well-balanced in physical properties, but also has a wide range of moldability when vacuum-molded, has a good moldability, and has a good balance. Molded articles with less meat are obtained (Examples 1 to 3). 2. On the other hand, the resin composition of the comparative example that does not satisfy the essential requirements of the present invention is inferior in fluidity (Comparative Example 2), has a narrow moldability range, and only a molded product having a large uneven thickness is obtained ( Comparative Examples 1-2).

Claims (3)

[Claims] 1. A graft copolymer obtained by polymerizing an aromatic vinyl monomer, a vinyl cyanide monomer, and optionally a monomer mixture copolymerizable therewith in the presence of a rubbery polymer. A mixture of the polymer (A) and a copolymer (B) obtained by polymerizing an aromatic vinyl monomer, a vinyl cyanide monomer and optionally a monomer mixture copolymerizable therewith, In addition, this copolymer (B) comprises a copolymer (b-1) having a weight average molecular weight of 50,000 to 300,000 and a copolymer (b-2) having a weight average molecular weight of 500,000 to 5,000,000. A thermoplastic resin composition, which is a mixture. 2. The weight ratio of the graft copolymer (A) and the copolymer (B) constituting the thermoplastic resin composition is 20 to 65:80 to 35, and the copolymer ( b-
2. The thermoplastic resin composition according to claim 1, which contains 2) in the range of 1 to 20% by weight (however, the total amount of each component is 100% by weight). 3. The ratio of the aromatic vinyl monomer, the vinyl cyanide monomer, and the monomer copolymerizable with them, in the graft copolymer (A) and the copolymer (B), The weight ratio is in the range of 50 to 65:50 to 35: 0 to 15 (however, the total amount of the monomers is 100% by weight).
The thermoplastic resin composition according to claim 1 or 2, wherein