JP3338557B2 - Thermoplastic resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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 produced 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 onto a rubbery polymer, and a copolymer of a mixture of a styrene monomer and an acrylonitrile monomer are used. Thermoplastic resin such as a graft blend type ABS resin is widely used for an inner box of an electric refrigerator. When manufacturing the inner box, first, a sheet is manufactured by an extrusion molding method, and then, the sheet is formed into a target shape by a vacuum (pneumatic) molding method.
In molding, a portion having a high stretching ratio, such as a corner of a box, tends to have an uneven thickness. Therefore,
As the thermoplastic resin to be used, a resin having a high elongational viscosity when highly stretched in a high temperature range under molding conditions is required.

[0003] However, it is difficult to say that conventional ABS resins or the like can sufficiently satisfy these physical property values. In recent years, instead of the conventional fluorocarbon that easily destroys the ozone layer, a so-called alternative fluorocarbon that is difficult to destroy has been adopted as a thermal insulating foaming agent for electric refrigerators. However, this acrylonitrile component ratio A
The BS resin material has a problem particularly in the formability at the time of the vacuum forming described above.

[0004]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention is directed to a thermoplastic resin having good moldability such that a portion having a high stretch ratio such as a corner portion of a box becomes uniform in vacuum forming. Is to provide.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to provide an aromatic vinyl monomer, a vinyl cyanide monomer and optionally a monomer which can be copolymerized therewith in the presence of a rubbery polymer. Copolymer (A) obtained by polymerizing a polymer mixture, and a copolymer obtained by polymerizing an aromatic vinyl monomer, a vinyl cyanide monomer, and a monomer mixture copolymerizable therewith. Consisting of a mixture with the polymer (B),
The copolymer (B) has a weight average molecular weight of 50,000 to
By a mixture of a copolymer (b-1) of 300,000 and a copolymer (b-2) having a weight average molecular weight of 500,000 to 5,000,000,
Can be solved.

Hereinafter, the present invention will be described in detail. 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, the copolymer (B) must contain a component (b-1) having a normal weight average molecular weight and a component (b-2) having a high weight average molecular weight.

The 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 styrene is typically typical. Examples of the vinyl cyanide monomer include acrylonitrile and methacrylonitrile, and acrylonitrile is typical. Monomers copolymerizable with these include methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, hydroxyethyl methacrylate,
Examples thereof include hydroxybutyl methacrylate, hydroxypropyl methacrylate, maleimide, and N-phenylmaleimide. These copolymerizable monomers may be one kind or a mixture of two or more kinds.

[0008] Graft copolymer (A) and copolymer (B)
The weight ratio of the aromatic vinyl monomer, vinyl cyanide monomer and monomer copolymerizable therewith is 50 to 80:50 to 20: 0 to 15 (however, The total amount of the monomers is preferably 100% by weight.), But particularly preferably 50 to 65:50 to 35: 0.
-10.

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

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

The composition ratio of the rubbery polymer and the monomer mixture in the graft copolymer (A) is 5 to 3 for the rubbery polymer.
It is preferable to select the monomer mixture in the range of 95 to 70% by weight 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 case of emulsion polymerization, an emulsifier, a polymerization initiator and, if necessary, a chain transfer agent are used. Performed in a temperature range of 〜90 ° C. As the emulsifier that can be used, those that can be used when polymerizing a vinyl-based monomer by an emulsion polymerization method can be used without limitation.

Examples of the polymerization initiator include persulfuric acid, peracetic acid, perphthalic acid, potassium persulfate, hydrogen peroxide, benzoyl peroxide, chlorobenzoyl peroxide, acetyl peroxide,
Examples include peroxides such as lauroyl peroxide and t-butyl hydroperoxide, and azo compounds such as azobisisobutyronitrile. These may be used in combination of two or more. Further, a redox system in which a peroxide and a reducing agent are combined may be employed. The amount of these polymerization initiators 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, t-dodecyl mercaptan, terpinolene, α-methylstyrene dimer and the like. These amounts are usually based on 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 (b-
It is essential that 2) is a mixed mixture. The weight average molecular weight of the copolymer in the conventional graft-blended ABS resin includes those having a weight average molecular weight of about 50,000 to 300,000, but the present invention is characterized in that the copolymer further contains a high molecular weight one. The above range is essential for the weight average molecular weight of the component (b-2), and is preferably 3 to 20 times, and more preferably 5 to 15 times the molecular weight of the component (b-1). In the present invention, the weight average molecular weight means a molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC).

The components of the graft copolymer (A), copolymer (b-1) and copolymer (b-2) contained in the resin composition according to the present invention need not necessarily be one kind. Alternatively, two or more polymers may be used in combination. For example, as the graft copolymer (A), two types of graft copolymers obtained by graft polymerization using different rubbery polymers can be used in combination. Further, a graft chain polymer of the graft copolymer (A), a copolymer (b-1)
The components of the copolymer (b-2) and the copolymer (b-2) do not need to be the same, but generally, it is desirable that they are substantially the same.

The copolymer (b-1) may be a by-product when producing the graft copolymer (A), or may be an AS resin produced separately. In the latter case,
The production method may follow a known method. Specifically, an aromatic vinyl monomer, a vinyl cyanide monomer, and optionally other monomers copolymerizable therewith, in the presence of a polymerization initiator and, if necessary, a chain transfer agent, Examples thereof include a method of producing by an emulsion polymerization method, a suspension polymerization method or a bulk polymerization method. As the polymerization initiator and the chain transfer agent used at this time, the same types as those used when 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). However, it is necessary that (b-2) is a polymer having a particularly high molecular weight. Therefore, usually, by the emulsion polymerization method, a relatively small amount of the polymerization initiator used,
It is preferable to carry out the polymerization reaction in a low temperature range. To prepare the resin composition according to the present invention, (1) a powdery, flake-like, bead-like polymer each separately produced, a method of weighing a predetermined amount of a polymer and 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, (3) a graft copolymer (A) and a copolymer (b)
-2) is mixed and coagulated in a latex state to form a powder, and the copolymer (b-1) is melt-mixed with the powder,
(4) Copolymer (b-2) prepared in advance in a graft polymerization system
In which the latex is present to produce the graft copolymer (A).

The content ratio of each component constituting the resin composition according to the present invention is in the range of 20 to 65 to 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). If the ratio of the component (B) to the component (A) is out of the above range, physical properties such as impact resistance and tensile strength are inferior, and moldability is inferior. If the proportion of the component (b-2) in the resin composition is too small, the moldability during vacuum molding cannot be sufficiently improved, and if it is too large, the fluidity decreases, which is not preferable. Particularly preferred in the above range is the range of 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
The resin composition can be further melt-mixed by an extruder such as a single-screw extruder or a twin-screw extruder, or a processing device such as a kneader such as a Banbury mixer, a kneader / ruder, a pressure kneader, or a heating roll. it can. Further, the resin composition according to the present invention, a kind and amount of a lubricant, a releasing agent, a coloring agent, an antistatic agent, a flame retardant, an ultraviolet absorber, a heat stabilizer, which do not inhibit the properties of the resin composition of the present invention, Various resin additives such as a light resistance stabilizer can be added in an appropriate combination.

The resin composition according to the present invention can be obtained 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, other electrical equipment and other electric products, and automobiles such as motorcycle cowling and vending machine inner racks. It is suitable for the manufacture of industrial parts such as ships, machines, etc., and is particularly suitable for use as an inner box of an electric refrigerator in which a sheet is formed by an extrusion 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 molding suitability and is suitable as a material for a vacuum forming method when a sheet manufactured by an extrusion method is formed into a target shape by a vacuum forming method. (2) When a sheet made of the resin composition according to the present invention is formed into a target shape by a vacuum forming method, a molded product having good clogging 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 unless departing from the gist thereof. In the following examples, “parts” means “parts by weight”, and “%” means “% by weight”.

Further, the copolymer (b-1) and the copolymer (b
The weight average molecular weight of -2) was measured using a gel permeation chromatography (GPC) apparatus under the following conditions. Apparatus: HLC-802A (manufactured by Tosoh Corporation) Column: two TSK gel GMHXLs in series Temperature: 40 ° C. Detection: differential refractive index solvent: tetrahydrofuran concentration: 1% by weight Calibration curve: 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 Kg / cm ² . * Impact strength means Izod impact strength (with notch) in accordance with JIS K7110. Based on 1/8 inch specimen. Unit Kg · cm / cm. * VICAT softening point Based on JIS K7206. Unit ℃. * Fluidity (MFR) Based on JIS K7210. Temperature 220 ° C, load 1
It represents the flow rate for 10 minutes under the condition of 0 kg. Unit g / 1
0 minutes.

* Vacuum moldability A sheet having a thickness of 2 mm is manufactured from the resin composition by an extrusion molding method, and the sheet is separated from the sheet by using a vacuum molding machine (FC-4APA manufactured by Asano Laboratories, plug assist type). Change the heating time of the sheet (50, 60, 70, 80
Sec), opening diameter 300mm, bottom diameter 150mm, depth 2
A molded product having a 50 mm bucket shape, a width reaching 6 mm from the opening to the bottom, and two ribs protruding outward was provided so as to oppose the wall surface. For the obtained molded product,
(1) The portion farthest from the rib was cut vertically from the opening to the bottom, and the measured value of the minimum thickness at the cut surface was shown. The larger the measured value, the more preferable. (2) Observe the sink mark of the rib portion (mold clogging-whether or not it is formed in accordance with the shape of the vacuum forming mold) with the naked eye, and check a good sink mark (good clogging) with " Sink "○," Sink "
Bad thing (bad shape) is "rib sink mark"
×, respectively.

The molding suitable region is a heating time allowed for obtaining a molded product having sufficient "sinking of ribs" when vacuum forming is performed and not causing uneven thickness. The wider this is, the better the vacuum formability is. Production example of graft polymer (A)

A-1 (1) Production of Rubbery Polymer A 150-L stainless steel autoclave equipped with a stirrer, a heating / cooling device, a thermometer, each raw material, and an auxiliary agent charging device is charged with 150 parts of deionized water. Part, higher fatty acid soap (sodium salt of fatty acid having 18 carbon atoms as a main component) 4.0
Parts, 0.075 parts of sodium hydroxide were charged and stirred.
After the replacement with nitrogen, the internal temperature was raised to 68 ° C. When the internal temperature reached 68 ° C., 1,3-butadiene 90 separately adjusted was used.
Parts, 10 parts of styrene and 0.1 part of t-dodecyl mercaptan.
After charging 20% of the monomer mixture consisting of 3 parts,
0.135 parts of potassium persulfate was added. An exotherm occurred a few minutes later, confirming the start of polymerization.

One hour after the addition of potassium persulfate, continuous addition of 80% of the monomer mixture was started, 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 continued for another hour. The obtained rubbery polymer latex has a solid content of 3%.
The average particle diameter of the rubber was 9.5%, and the average particle diameter was 0.08 μm.

(2) Production of Graft Polymer The rubbery mass obtained in the above (1) was placed in a 5 L reactor equipped with a stirrer, a heating / cooling device, a thermometer, and each raw material and auxiliary agent charging device. 100 parts of a combined latex having an average particle diameter of 0.27 μm enlarged with acetic anhydride as a solid content, and 347 parts of deionized water (including the water content in the latex) were charged, and the mixture was stirred at an internal temperature. At 70 ° C
The temperature rose. At the time when the internal temperature reached 60 ° C. on the way, sodium pyrophosphate 1.0 dissolved in 20 parts of deionized water was used.
Part, dextrose 0.25 part and ferrous sulfate 0.0
One part aqueous solution was added.

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

After the completion of the continuous addition, the reaction was continued at a temperature of 70 ° C. for another 30 minutes, and then the internal temperature was cooled to terminate the reaction. The graft polymer latex having a solid content of 39.5% was obtained. Was. This graft polymer latex is
-1.

A-2 (1) Production of Rubbery Polymer A 151-liter stainless steel autoclave equipped with a stirrer, a heating / cooling device, a thermometer, each raw material and an auxiliary agent charging device was charged with 151 deionized water. Part, higher fatty acid soap (sodium salt of fatty acid having 18 carbon atoms as main component) 2.0
And 1 part of sodium bicarbonate, and the mixture was purged with nitrogen under stirring, and then the internal temperature was raised to 75 ° C. Potassium persulfate 0.
After 5 minutes, 100 parts of butyl acrylate and 0.05 part of allyl methacrylate were added.
Parts of a monomer mixture consisting of 1.2 parts of t-dodecyl mercaptan and 4 parts of t-dodecyl mercaptan. A few minutes later a fever occurs,
The initiation of polymerization was confirmed.

At 20 minutes after the charging of the monomer mixture, continuous addition of the remaining monomer mixture was started.
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 continued for another hour. The obtained rubbery polymer latex had a solid content of 39.5%, an average particle diameter of 0.10 μm, and a gel content of 0%.

(2) Production of Graft Polymer The rubber-like weight obtained in the above (1) was placed in a 5 L reactor equipped with a stirrer, a heating / cooling device, a thermometer, and each raw material and auxiliary agent charging device. The combined latex is 100
Parts, 402 parts of deionized water (including water in latex) 2.2 parts of sodium pyrophosphate, glucose 0.55
And 0.022 part of ferrous sulfate, and the inner 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-dodecylmercaptan and 1.1 parts of cumene hydroperoxide was started. It ended in 30 minutes. A solution consisting of 3.96 parts of disproportionated potassium rosinate soap was continuously added to 88.2 parts of deionized water over the same time as the continuous addition of the monomer mixture.

After completion of the continuous addition, the reaction was continued at a temperature of 70 ° C. for another 30 minutes, and then the internal temperature was cooled to terminate the reaction, and the graft polymer latex having a solids concentration of 35.4% was obtained. Was. This graft polymer latex is
-2. Production example of copolymer (B)

B-1 A 5 L stainless steel autoclave equipped with a heating / cooling device, a curved turbine type stirring device, a thermometer, and a device for charging each raw material and an auxiliary agent was stirred with acrylonitrile 4 under stirring.
5 parts, styrene 10 parts, di-tert-butyl-p-
Cresol 0.02 parts, acrylic acid / acrylic acid-2-
0.03 part of an ethylhexyl copolymer, 0.4 part of sodium bromide, and 70 parts of deionized water were charged, and the inside of the autoclave was purged 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 initiate a polymerization reaction. Immediately after the start of the polymerization, 36 parts of styrene were continuously added at a constant rate over a period of 4 hours and 30 minutes.
The temperature was raised to 28 ° C. After the continuous addition of styrene, 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 the completion of the stripping, the mixture was cooled, filtered, washed with water and dried to obtain a bead-like copolymer (b-1). The weight average molecular weight of this copolymer was 120,000.

B-2 Deionized water 1 was placed in a 5 L glass autoclave.
23 parts, 1.2 parts of disproportionated potassium rosinate soap and 4.0 parts of acrylonitrile were charged, and the mixture was purged with nitrogen while 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 over 6 hours and 30 minutes. 30 minutes after the start of continuous addition, a solution consisting of 1.8 parts of disproportionated potassium rosinate soap and 0.175 parts of potassium persulfate was added to 26 parts of deionized water at a constant rate over 6 hours and 30 minutes. It was added continuously. After the continuous addition of this solution, the reaction was continued for another hour,
After cooling, the reaction was completed to obtain a copolymer (b-2) latex having a solid content of 40.5 and a weight average molecular weight of 1.2 million.

Examples 1-4, Comparative Examples 1-2 Latexes of the above graft polymer (A) and copolymer (b-2) were mixed at the ratio (in terms of solid content) shown in Table 1, 2.5 parts of an antioxidant was added to the obtained mixed latex, and then added to a stirred aqueous solution of magnesium sulfate heated to 95 ° C. to coagulate, and the coagulated product was washed with water and dried to obtain a white powdery resin. A composition was obtained. The copolymer (b-1) was mixed with the obtained resin composition at a ratio 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 methods described above. The results are shown in Table 1. Further, a sheet was formed by an extruder using this pellet, and the vacuum formability of the sheet was evaluated by the above-described evaluation method. The results are shown in Table 1.

[0039]

[Table 1]

From Table 1, the following becomes clear. 1. The resin composition according to the present invention is not only excellent in impact resistance, heat resistance, and fluidity, and is balanced in physical properties, but also has a wide range of molding suitability in vacuum forming, good clogging, and unevenness. A molded product with less meat is 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), and has only a molded article with a narrow moldability range and large uneven thickness (Comparative Example 2). Comparative Examples 1 and 2).

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-180949 (JP, A) JP-A-4-332742 (JP, A) JP-A-2-252512 (JP, A) JP-A-54- 28355 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 55/02 C08L 25/12

Claims (3)

(57) [Claims] 1. A graft copolymer obtained by polymerizing an aromatic vinyl monomer, a vinyl cyanide monomer and a monomer mixture copolymerizable therewith in the presence of a rubbery polymer. A mixture of a copolymer (A), an aromatic vinyl monomer, a vinyl cyanide monomer and a copolymer (B) obtained by polymerizing a monomer mixture copolymerizable therewith, In addition, the copolymer (B) is composed of 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 ratio of the graft copolymer (A) and the copolymer (B) constituting the thermoplastic resin composition is from 20 to 65:80 to 35 by weight, and the copolymer ( b-
2. The thermoplastic resin composition according to claim 1, wherein 2) is contained in an amount of 1 to 20% by weight (however, the total amount of each component is 100% by weight). 3. The graft copolymer (A) and the copolymer (B) have a proportion of an aromatic vinyl monomer, a vinyl cyanide monomer, and a monomer copolymerizable therewith. The weight ratio ranges from 50 to 65:50 to 35: 0 to 15 (provided that the total amount of the monomers is 100% by weight).
The thermoplastic resin composition according to claim 1 or 2, wherein