JPH06306255A - Low-odor resin composition having excellent fluorocarbon resistance - Google Patents

Abstract

PURPOSE:To obtain the composition having excellent fluorocarbon resistance, odorlessness and strength-stability and useful, e.g. for the inner box of refrigerator and freezer by dispersing specific amounts of two specific kinds of graft copolymers in a copolymer of an aromatic vinyl compound and vinyl cyanide. CONSTITUTION:The objective composition is produced by dispersing (A) a graft copolymer having a graft ratio of 20-60% and obtained by polymerizing an aromatic vinyl compound and vinyl cyanide in the presence of a binary copolymer selected from ethylene-propylene copolymer and ethylene-butene copolymer and (B) a graft copolymer having a graft ratio of 25-70% and obtained by polymerizing an aromatic vinyl compound and vinyl cyanide in the presence of a diene-type rubbery polymer in (C) a copolymer consisting of 70-50wt.% of an aromatic vinyl compound and 30-50wt.% of vinyl cyanide. The amount of A+B in the composition is 15-30wt.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low odor resin composition having excellent chlorofluorocarbon resistance, more specifically,
1,1-dichloro-2,2,2-trifluoroethane (H
CFC-123) and 1,1-dichloro-1-fluoroethane (HCFC-141b) have excellent resistance to CFC substitutes and a low odor resin composition.

[0002]

2. Description of the Related Art In a heat insulating / cooling container such as a refrigerator or a freezer, a styrene resin (ABS resin, high impact polystyrene) sheet formed by a vacuum forming method is generally used as an inner box. The styrenic resin itself has a strong odor and is not preferable as a container for storing food. It has been proposed to change the alkyl mercaptan used as a molecular weight modifier during the polymerization to another compound such as terpinolene for the purpose of reducing the odor, but it is still not sufficient.

The styrene-based resin inner box is used as a heat insulator by providing a foam layer of hard urethane between the inner box and the metal outer box. "(Trichloromonofluoromethane CF
C-11 ″), in which case CFC-1
There was a problem that the inner box made of styrene resin was stressed due to the fact that 1 itself came into contact with the inner box made of styrene resin and the heat generated by foaming and the shrinkage of the foam layer caused the inner box to crack and whiten. For this reason, a protective layer must be provided in advance on the surface in contact with the foamed layer, which leaves a problem that the production process is complicated and the strength of the inner box itself is reduced.

Further, in recent years, production and use of ozone depleting substances such as CFC-11 have been regulated, and CF
Blowing agent replacing C-11, ie 1,1-dichloro-
2,2,2-trifluoroethane (HCFC-123),
1,1-dichloro-1-fluoroethane (HCFC-14
Investigations using alternative CFCs such as 1b) are underway. However, since the CFC substitute has a stronger polarity than CFC-11, the strength of the inner box using the conventional styrene-based resin is significantly reduced due to cracking or whitening, and a non-defective product cannot be obtained. Although it is possible to prevent the strength from decreasing by increasing the thickness of the inner box, there are problems such as an increase in the weight of the inner box and a longer preheating time during vacuum forming. Although it is possible to improve the resistance to CFC substitutes by increasing the content of acrylonitrile in the styrene resin, there remains a very serious problem that the processability, strength and thermal stability of the styrene resin are reduced. It had been.

On the other hand, AES resin obtained by improving the weather resistance of ABS resin (styrene-containing ethylene-propylene-non-conjugated diene terpolymer "EPDM" as a rubber component)
A blend of acrylonitrile resin) and ABS resin has recently been introduced as a material with excellent chlorofluorocarbon resistance, but the odor of the material itself is still strong, and it is not sufficient as a material for the inner box of refrigerators and freezers. It was
Therefore, without sacrificing the excellent mechanical strength, processability, appearance, thermal stability, etc., which are the characteristics of styrene resin,
It has been desired to develop a low-odor material having excellent chlorofluorocarbon resistance (particularly, resistance to alternative chlorofluorocarbons).

[Problems to be Solved by the Invention]

The present invention is based on HCFC-123 and HCFC-
Another object of the present invention is to provide a low odor resin composition having excellent chlorofluorocarbon resistance, which is suitable as a material for an inner box of a refrigerator or a freezer, which uses the CFC substitute of 141b as a foaming agent.

[Means for solving problems]

The inventor of the present invention has found that a graft having a specific graft ratio based on a specific binary polymer and an A having a specific graft ratio.
The present inventors have found that a composition in which a BS resin is dispersed in a resin phase having a high acrylonitrile content is excellent in CFC resistance and has a low odor, and has reached the present invention.

That is, according to the present invention, the graft ratio obtained by polymerizing aromatic vinyl and vinyl cyanide in the presence of ethylene-propylene or ethylene-butene binary copolymer is 2
Graft polymer (B) having a graft ratio of 25 to 70% obtained by polymerizing aromatic vinyl and vinyl cyanide in the presence of 0 to 60% of the graft polymer (A) and a diene rubbery polymer.
Are dispersed in a copolymer (C) consisting of 70 to 50% by weight of aromatic vinyl and 30 to 50% by weight of vinyl cyanide, and an ethylene-propylene or ethylene-butene binary copolymer and a diene type The total amount of rubbery polymer is 15 to 3
A low odor resin composition having an excellent CFC resistance of 0% by weight is provided. The present invention will be described in detail below.

The graft polymer (A) used in the present invention is a graft ratio of 20 to 60 obtained by polymerizing aromatic vinyl and vinyl cyanide in the presence of an ethylene-propylene or ethylene-butene binary copolymer. % Graft polymer. There is no particular limitation on the ratio of ethylene and propylene in the ethylene-propylene binary copolymer, but the composition ratio is preferably 0.2 to 3 propylene in a molar ratio of 1 to ethylene.

Examples of aromatic vinyl include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, t-butylstyrene, α-methylvinyltoluene, dimethylstyrene, chlorostyrene and dichloro. Styrene, bromostyrene, dibromostyrene, vinylnaphthalene and the like can be mentioned, and one kind or two or more kinds can be used. Particularly preferred is styrene. Examples of vinyl cyanide include acrylonitrile, fumaronitrile, methacrylonitrile and the like, and one or more of them can be used. Acrylonitrile is particularly preferable. In addition, a part of the aromatic vinyl is unsaturated such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate without departing from the object of the present invention. Substitution with a maleimide compound such as carboxylic acid alkyl ester, maleimide, methylmaleimide, ethylmaleimide, N-phenylmaleimide, or O-chloro-N-phenylmaleimide is also possible. Although there is no particular limitation on the composition ratio of aromatic vinyl (or other compounds mentioned above) and vinyl cyanide to be used for polymerization, an aromatic vinyl-vinyl cyanide copolymer produced as a by-product during graft polymerization. Influences the composition ratio of the resin phase (copolymer C) specified in the present invention, so that aromatic vinyl is preferably 50 to 70% by weight and vinyl cyanide is 30 to 50% by weight.

The graft ratio of the graft polymer (A) is 2
It is 0 to 60% by weight. If it is less than 20% by weight, the strength is poor, and if it exceeds 60% by weight, the workability and the appearance are poor. It is particularly preferably 30 to 60% by weight. The graft ratio (%) can be obtained by extracting and separating the soluble portion (by-produced aromatic vinyl-cyanide vinyl copolymer) and the insoluble portion with acetone as a solvent, and calculating from the insoluble portion according to the following formula. . The graft ratio is a polymerization condition, for example, a ratio of an ethylene-propylene binary copolymer and a monomer (aromatic vinyl and vinyl cyanide), a method of adding a monomer, a kind and an amount of a catalyst and a molecular weight modifier. It can be adjusted by changing. There is no particular limitation on the intrinsic viscosity (30 ° C., dimethylformamide) of the by-produced aromatic vinyl-vinyl cyanide copolymer, but 0.3 to 0.7 is preferable in terms of physical property balance and flon resistance. preferable.

Examples of the method for producing the graft polymer (A) include a bulk polymerization method, a suspension polymerization method, a solution polymerization method, an emulsion polymerization method and a combination method thereof. In the polymerization, known compounds such as an initiator, a molecular weight modifier, a solvent, a suspending agent and an emulsifier can be used.

The graft polymer (B) used in the present invention is a graft polymer obtained by polymerizing aromatic vinyl and vinyl cyanide in the presence of a diene rubbery polymer and having a graft ratio of 25 to 70%. It is a polymer. Examples of the diene polymer include polybutadiene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, polyisoprene and the like, and one kind or two or more kinds can be used.

Examples of the aromatic vinyl and vinyl cyanide constituting the graft polymer (B) include those mentioned in the section of the graft polymer (A). Particularly preferred are styrene and acrylonitrile. Further, like the graft polymer (A), a part of the aromatic vinyl can be sufficiently replaced with an unsaturated carboxylic acid alkyl ester or a maleimide compound. Although there is no particular limitation on the composition ratio of aromatic vinyl (or other compounds mentioned above) and vinyl cyanide to be used for polymerization, an aromatic vinyl-vinyl cyanide copolymer produced as a by-product during graft polymerization. Affects the composition ratio of the resin phase (copolymer C) specified in the present invention,
Aromatic vinyl 50-70% by weight, vinyl cyanide 30-
It is preferably 50% by weight.

The graft ratio of the graft polymer (B) is 2
5 to 70% by weight. If it is less than 25% by weight, the strength is poor, and if it exceeds 70% by weight, the workability and the appearance are poor. It is particularly preferably 30 to 60% by weight. The graft ratio (%) can be adjusted by changing the polymerization conditions as in the case of the graft polymer (A). Intrinsic viscosity of aromatic vinyl-vinyl cyanide copolymer (30
C., dimethylformamide) are not particularly limited, but 0.3 to 0.7 is preferable in terms of physical property balance and chlorofluorocarbon resistance.

Examples of the method for producing the graft polymer (A) include a bulk polymerization method, a suspension polymerization method, a solution polymerization method, an emulsion polymerization method and a combination method thereof. In the polymerization, known compounds such as an initiator, a molecular weight modifier, a solvent, a suspending agent and an emulsifier can be used.

In the resin composition of the present invention, the above-mentioned graft polymer (A) and graft polymer (B) are dispersed in a copolymer (C) consisting of aromatic vinyl and vinyl cyanide. Has become. The composition of the copolymer (C) is as follows: aromatic vinyl 50 to 70% by weight, vinyl cyanide 30 to 5
When it is less than 50% by weight, the workability and yellowing (coloring) are inferior, and when it exceeds 70% by weight, the CFC resistance is inferior. Preferably, aromatic vinyl 55-
65% by weight and 35 to 45% by weight of vinyl cyanide.
The copolymer (C) is a copolymer produced as a by-product during the graft polymerization of the graft polymer (A) and the graft polymer (B), or an aromatic vinyl-cyanide copolymer separately produced with them. It is a mixture. Furthermore, although the intrinsic viscosity of the copolymer (C) is not limited, it is preferably 0.5 to 0.9 in terms of physical property balance. Therefore, the above-mentioned copolymer (C) composition and intrinsic viscosity can be obtained in advance as their weighted average value, or can be confirmed by a method of analyzing the final composition.

The composition ratio of vinyl cyanide and aromatic vinyl at the time of polymerization is not particularly limited, but the composition of the copolymer (C) is limited (aromatic vinyl 50 to 70% by weight, vinyl cyanide 30 to 50% by weight). %), Aromatic vinyl 50 to 65
It is preferable that the content of vinyl cyanide is 35 to 50% by weight. As a method of separately producing an aromatic vinyl-vinyl cyanide copolymer, a bulk polymerization method, a suspension polymerization method,
A solution polymerization method, an emulsion polymerization method and a combination method thereof can be mentioned. In the polymerization, known compounds such as an initiator, a molecular weight modifier, a solvent, a suspending agent and an emulsifier can be used.

The total amount of the ethylene / propylene or ethylene-butene binary copolymer and the diene rubbery polymer in the composition of the present invention is 15 to 30% by weight. 15% by weight
If it is less than 30%, impact resistance and CFC resistance are poor, and if it exceeds 30% by weight, workability is poor. The total amount can be prepared by varying the composition of the graft polymers (A) and (B) and the composition of each graft polymer.

The blending ratio (weight basis) of the graft polymers (A) and (B) is not particularly limited, but the graft polymer (B) is preferably 0.5 to 2 per 1 graft polymer (A). .

The form and mixing method of the graft polymers (A), (B) and the copolymer (C) are not particularly limited, and they may be in any form such as pellets, powders, aqueous dispersions and slurries. Also, the mixing is carried out by a known device, for example,
It can be performed using an extruder, a tumbler, a Banbury mixer, or the like. Incidentally, the resin composition of the present invention,
If necessary, additives such as an antioxidant, an ultraviolet absorber, a lubricant, a release agent and an antistatic agent can be optionally added, and the addition timing is also arbitrary.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples. All parts and% used in the examples are based on weight.

Reference Example 1: Preparation of Graft Polymer (A-1) Ethylene-propylene binary cut into 3 mm square with stirring in 300 parts of pure water in which 0.3 part of suspension stabilizer (hydroxyethyl cellulose) was dissolved. Copolymer (43% propylene)
50 parts were charged and suspended. Then 37 parts of styrene,
20 parts of acrylonitrile, polymerization initiator (t-butylper
5 parts of oxypivalate) and 0.1 part of a molecular weight regulator (t-dodecyl mercaptan) were added, and the mixture was polymerized at 100 ° C. for 10 hours in a nitrogen atmosphere. After the polymerization, water was separated and the polymer was recovered. The polymer obtained was a by-produced copolymer 25 having a graft ratio of 51% and a graft product of 75% and an intrinsic viscosity of 0.68.
% Resin.

Reference Example 2: Preparation of graft polymer (A-2) 20 parts of an ethylene-butene binary copolymer (83% ethylene, 17% butene) obtained by cutting into 3 mm square was dissolved in 300 parts of ethylbenzene. , Styrene 70 parts, acrylonitrile 25 parts, and benzoyl peroxide 2 parts 67
Polymerization was carried out at ℃ for 10 hours in a nitrogen atmosphere. After the polymerization, the polymerization solution was brought into contact with a large excess of methanol to recover the polymer.
The polymer obtained is a graft body 30 with a graft ratio of 35%.
% And 70% by-product copolymer having an intrinsic viscosity of 0.68.

Reference Example 3: Production of Graft Polymer (X-1) The ethylene-propylene binary copolymer was changed to an ethylene-propylene-ethylidene norbornene ternary copolymer (propylene 43%, iodine value 25). Other than reference example 1
Polymerization was carried out under the same conditions as above, and the polymer was recovered. The obtained polymer is a resin composed of 83% of a graft product having a graft ratio of 50% and 17% of a by-product copolymer having an intrinsic viscosity of 0.68.

Reference Example 4: Preparation of Graft Polymer (X-2) Ethylene-propylene binary cut into 3 mm square while stirring in 300 parts of pure water in which 0.3 part of suspension stabilizer (hydroxyethyl cellulose) was dissolved. Copolymer (43% propylene)
50 parts were charged and suspended. Then 37 parts of styrene,
20 parts of acrylonitrile, 5 parts of t-butylperoxypivalate were polymerized at 100 ° C. for 10 hours in a nitrogen atmosphere. After the polymerization, water was separated and the polymer was recovered. The obtained polymer is a resin composed of 88% of a graft having a graft ratio of 66% and 12% of a by-product copolymer having an intrinsic viscosity of 0.72.

Reference Example 5: Preparation of Graft Polymer (B) 50 parts (solid content) of butadiene-styrene polymer (styrene content 7%) latex having a weight average particle diameter of 0.4 μ were charged, and then pure water 110 was added. 0.1 part dextrin, 0.1 part anhydrous sodium pyrophosphate and 0.0 parts ferrous sulfate
Add an aqueous solution in which 05 parts was dissolved. Then, the gas phase part was replaced with nitrogen, and the temperature was raised to 70 ° C. When the temperature in the reaction tank reaches 70 ° C, 15 parts of acrylonitrile, 35 parts of styrene, t-
A mixed solution of 0.3 part of dodecyl mercaptan and 0.3 part of cumene hydroperoxide and an emulsifier solution in which 0.7 part of potassium oleate was dissolved in 20 parts of pure water were continuously added over 4 hours. Keep the temperature in the bath at 70 ℃ during continuous addition,
After the continuous addition was completed, the mixture was aged at 70 ° C. for 2 hours for polymerization. After the polymerization, the polymer was recovered using a salting-out agent. The obtained polymer is a resin composed of 76% of a graft product having a graft ratio of 52% and 24% of a by-product copolymer having an intrinsic viscosity of 0.61.

Reference Example 6: Preparation of Graft Polymer (Y) After charging 40 parts (solid content) of butadiene-styrene polymer (styrene content 7%) latex having a weight average particle diameter of 0.4 μ, pure water 110 To 0.5 parts dextrin, 0.1 parts anhydrous sodium pyrophosphate and 0.1 parts ferrous sulfate.
Add an aqueous solution in which 05 parts was dissolved. Then, the gas phase part was replaced with nitrogen, and the temperature was raised to 70 ° C. When the temperature in the reaction tank reaches 70 ° C, 18 parts of acrylonitrile, 42 parts of styrene, t-
A mixed solution of 0.2 part of dodecyl mercaptan and 0.3 part of cumene hydroperoxide and an emulsifier solution in which 0.7 part of potassium oleate was dissolved in 20 parts of pure water were continuously added over 4 hours. Keep the temperature in the bath at 70 ℃ during continuous addition,
After the continuous addition was completed, the mixture was aged at 70 ° C. for 2 hours for polymerization. After the polymerization, the polymer was recovered using a salting-out agent. The obtained polymer is a resin comprising 72% of a graft product having a graft ratio of 80% and 28% of a by-product copolymer having an intrinsic viscosity of 0.65.

Reference Example 7: Production of copolymer (C) After charging 120 parts of pure water and 0.3 part of potassium persulfate,
Replace the gas phase with nitrogen and heat with stirring. When the temperature in the tank reaches 68 ° C, 38 parts of acrylonitrile, 62 parts of styrene,
A mixed solution of 0.3 part of t-dodecyl mercaptan and 0.3 part of cumene hydroperoxide, and an emulsifier solution in which 0.7 part of potassium oleate was dissolved in 20 parts of pure water were continuously added over 7 hours. After that, at 70 ℃ 3
Polymerization was continued for an hour. After the polymerization, the polymer was recovered using a salting-out agent. The obtained copolymer had a composition of 63% styrene and 37% acrylonitrile and had an intrinsic viscosity of 0.55.

Reference Example 8: Production of Copolymer (Z) After charging 120 parts of pure water and 0.3 part of potassium persulfate,
Replace the gas phase with nitrogen and heat with stirring. When the temperature in the tank reaches 68 ° C, 25 parts of acrylonitrile, 75 parts of styrene,
A mixed solution of 0.3 part of t-dodecyl mercaptan and 0.3 part of cumene hydroperoxide, and an emulsifier solution in which 0.7 part of potassium oleate was dissolved in 20 parts of pure water were continuously added over 7 hours. After that, at 70 ℃ 3
Polymerization was continued for an hour. After the polymerization, the polymer was recovered using a salting-out agent. The obtained copolymer had a composition of styrene 76% and acrylonitrile 24%, and an intrinsic viscosity of 0.56.

Examples and Comparative Examples After mixing the above-mentioned graft polymer and copolymer, 230
The mixture was melt-kneaded at ℃ and pelletized. The compositions and characteristics of various compositions are shown in Table-1 and Table-2. The physical properties were measured by the following methods. "STY: styrene" and "ACN: acrylonitrile" of the copolymers in Tables 1 and 2 are copolymers produced separately from the copolymer by-produced during the graft polymerization forming a continuous phase in the resin composition. The calculated composition is shown below.

(1) Freon resistance and odor evaluation Freon resistance evaluation Using an 8 ounce injection molding machine, a cylinder set temperature of 240
A 15 mm × 2 mm × 0.2 mm thick test piece was prepared from a 30 mm × 10 mm × 0.2 mm thick plate molded at 0 ° C. and subjected to a deflection of 4.5 cm using a cantilever jig, and then the HCFC- 141b Leave in steam for 24 hours. The amount of strain at which cracks occur (maximum 1.35%) was determined. The larger the value, the better the CFC resistance (HCFC-141b). Odor evaluation 1-ounce injection molding machine was used, and the cylinder temperature was set to 240.
A 9 cm × 5.5 cm × 0.3 cm thick plate molded at 0 ° C. was placed in a polyester odor bag (3 liters of internal capacity) and purged with nitrogen gas. After standing in an oven at 40 ° C. for 1 hour, the state was adjusted at room temperature for 1 hour, and a sensory test was carried out by four panelists. Using Comparative Example 1 as a control (x), relative comparison was carried out, and a sample in which a reduction in odor was recognized was marked with ◯.

(2) Evaluation of Impact Strength, Workability and Thermal Stability The obtained pellets were molded into a test piece for each physical property at a cylinder set temperature of 230 ° C. using a 3.5 ounce injection molding machine. Notched Izod Impact Strength (NI) Complies with ASTM D-256. 1/4 inch thickness, 23 ° C, unit: Kg · cm / cm Workability (MFR) Melt indexer, 220 ° C, 10Kg Unit: g /
10 min Thermal stability It was allowed to stay in a Koka type flow tester at 260 ° C for 30 minutes, after which the appearance change of the strand (rough skin condition)
Visually judge. ○: No change to small △: Medium ×: Large

[0034]

[Table-1]

[0035]

[Table-2]

[0036]

INDUSTRIAL APPLICABILITY The present invention relates to a resin composition having excellent chlorofluorocarbon resistance and having little odor, which is an important item as an inner box of a refrigerator, and uses HCFC-123, HCFC141b or the like as a foaming substitute. Even by the method, it is possible to provide an excellent inner box for a refrigerator / freezer without increasing the thickness of the inner box and reducing the strength due to cracks and whitening and having no odor.

Claims (1)

[Claims] 1. Ethylene-propylene or ethylene-
In the presence of a butene binary copolymer, a graft polymer (A) obtained by polymerizing aromatic vinyl and vinyl cyanide and having a graft ratio of 20 to 60%, and a diene rubbery polymer, aromatic vinyl and Grafting ratio 2 obtained by polymerizing vinyl cyanide
5 to 70% of the graft polymer (B) is dispersed in a copolymer (C) of 70 to 50% by weight of aromatic vinyl and 30 to 50% by weight of vinyl cyanide, and ethylene-propylene or A low odor resin composition having excellent chlorofluorocarbon resistance, wherein the total amount of the ethylene-butene binary copolymer and the diene rubbery polymer is 15 to 30% by weight.