JPS6235416B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a thermoplastic resin composition having excellent weather resistance and heat resistance. More specifically, the present invention comprises a graft copolymer (A) of styrene and acrylonitrile to an ethylene-propylene copolymer rubber or an ethylene-propylene-diene copolymer rubber, and α-methylstyrene and acrylonitrile as main components. Thermoplastic with excellent weather resistance and heat resistance obtained by mixing copolymer (B) obtained by copolymerizing one or more vinyl monomers selected from styrene and methyl methacrylate. The present invention relates to a resin composition. Conventionally, in order to improve the impact resistance of styrene-based resins, rubber-modified thermoplastic resins obtained by graft polymerizing styrene or styrene and acrylonitrile to diene-based rubbery polymers, especially styrene and acrylonitrile, have been used.
ABS resin is widely used because of its toughness and good surface gloss. Recently, rubber-modified thermoplastic resins are being used in parts that were conventionally made of metal in the fields of automobiles, electrical equipment, and the like. In this case, the disadvantages or properties of the thermoplastic resin that are desired to be improved include (1) improved heat resistance to reduce deformation of the product in high-temperature atmospheres, and (2) improvement in the product's ability to be exposed outdoors. This prevents deterioration of physical properties when For the former, α-methylstyrene is used as the monomer to be graft copolymerized, and for the latter, ethylene-propylene copolymer rubber or ethylene-propylene-diene copolymer is used as the rubbery polymer. By using rubber, the properties of each are improved. Therefore, in order to satisfy these two properties, ethylene-propylene copolymer rubber or ethylene-propylene
A proposal has been made to graft copolymerize a vinyl monomer mainly composed of α-methylstyrene in the presence of a diene copolymer rubber. However, the content of unsaturated groups in ethylene-propylene copolymer rubber or ethylene-propylene-diene copolymer rubber is extremely low, making graft polymerization difficult even when styrene or acrylonitrile is used as a monomer. It is. If this graft polymerization reaction is not carried out sufficiently, the resulting resin will not have good impact resistance and resin surface, and a delamination phenomenon will be observed. As a method to improve these, there is a method of pre-treating ethylene-propylene copolymer rubber or ethylene-propylene-diene copolymer rubber with peroxide etc. to increase the number of graft points, as seen in Japanese Patent Publication No. 49-2026, etc.
Alternatively, various methods are available, such as those in Japanese Patent Publication No. 49-14549, which improve the selection of catalyst and the polymerization method. These measures to improve graft polymerization have some effect in the graft copolymerization of styrene and acrylonitrile, which have a high polymerization rate.
Graft copolymerization of vinyl monomers mainly composed of α-methylstyrene is even more difficult. It is difficult to improve. As a result of various studies in order to improve these drawbacks, the present inventors have found that ethylene-propylene copolymer rubber or ethylene-propylene-diene copolymer rubber has excellent weather resistance and improved heat resistance. Graft copolymer (A) that underwent a sufficient graft polymerization reaction using styrene and acrylonitrile
and a copolymer (B) obtained by copolymerizing α-methylstyrene and acrylonitrile as main components, and optionally one or more vinyl monomers selected from styrene and methyl methacrylate. The present invention was achieved by discovering a thermoplastic resin composition obtained by the following methods. That is, the present invention adds 60 to 70 parts by weight of styrene to 15 to 70 parts by weight of ethylene-propylene copolymer rubber or ethylene-propylene-diene copolymer rubber.
A graft copolymer (A) obtained by graft copolymerizing 85 to 30 parts by weight of a monomer mixture consisting of 80% by weight and 20 to 40% by weight of acrylonitrile, and 50% by weight of α-methylstyrene.
~80 wt%, acrylonitrile 10-30 wt%, styrene or/and methyl methacrylate 0-30
A copolymer (B) obtained by copolymerizing a monomer mixture consisting of To provide a thermoplastic resin composition having a content of 5 to 30% by weight and having excellent weather resistance and heat resistance. The present invention will be explained in detail below. The graft copolymer (A) used in the present invention may be one having normal rubber elasticity as an ethylene-propylene copolymer rubber or an ethylene-propylene-diene copolymer rubber, and is generally ethylene-propylene copolymer rubber.
35 to 85 mol%, propylene 15 to 65 mol%, or a small amount of diene such as dicyclopentadiene, ethylidenenorbornene,
A copolymer of 1,4-hexadiene or the like is used. The graft copolymerization method is not particularly limited, but for example, ethylene-propylene copolymer rubber or ethylene-propylene-diene copolymer rubber and styrene or acrylonitrile are dissolved in a solvent such as an aromatic hydrocarbon, and a radical initiator is used. Ordinary solution polymerization method in which copolymerization is carried out in the presence of ethylene-propylene copolymer rubber or ethylene-propylene copolymer rubber
The diene copolymer rubber is dissolved in an organic solvent, an emulsifier and water are added thereto, the mixture is stirred with a homomixer to emulsify it, and the emulsion obtained by removing the solvent by steam distillation is used to infuse styrene into the rubber. ,
A method of carrying out emulsion polymerization by adding acrylonitrile can be mentioned. In the graft copolymerization, 60 to 80 parts by weight of styrene and 20 to 40 parts by weight of acrylonitrile are mixed in the presence of 15 to 70 parts by weight of ethylene-propylene copolymer rubber or ethylene-propylene-diene copolymer rubber.
85 to 30 parts by weight of the monomer mixture containing % by weight are graft copolymerized. The obtained graft copolymer has a graft ratio (weight of bonded styrene-acrylonitrile copolymer/weight of rubber component), which indicates the degree of bonding of the styrene-acrylonitrile copolymer to the rubber component, of 30% or more. preferable. If it is less than this, the surface gloss of the resulting mixed resin will decrease and delamination phenomenon will occur, which is not preferable. More preferably, the grafting rate is 50% or more. If the rubber component is less than 15% by weight, the mixing ratio of the resin component with the copolymer (B) will be small and sufficient heat resistance cannot be provided, while if it exceeds 70% by weight, graft copolymerization will occur. The reaction becomes insufficient and a resin with excellent surface gloss etc. cannot be obtained. In addition, if α-methylstyrene is used as a monomer component for graft copolymerization, the graft copolymerization reaction will be slow and the grafting rate will decrease. good. The composition ratio of styrene and acrylonitrile to be graft copolymerized is in the range of 20 to 40% by weight of acrylonitrile. Acrylonitrile content is 20
If it is less than 40% by weight, the impact strength of the mixed composition will decrease, and if it exceeds 40% by weight, the molding processability of the mixed composition will decrease or coloration will occur. The copolymer (B) to be mixed with the graft copolymer (A) is
It can be obtained by radical copolymerization of a monomer mixture having a composition range of 50 to 80% by weight of α-methylstyrene, 10 to 30% by weight of acrylonitrile, and 0 to 30% by weight of styrene or/and methyl methacrylate.
If the amount of α-methylstyrene is less than 50% by weight, a resin with sufficient heat resistance cannot be obtained, and if it exceeds 80% by weight, the polymerization conversion rate will be low and the resulting resin will become brittle. If the amount of acrylonitrile is less than 10% by weight, sufficient impact strength cannot be obtained when the resin is mixed with the graft copolymer (A). while 30
If the amount exceeds % by weight, the resulting resin will be significantly colored and fluidity will decrease. Styrene and/or methyl methacrylate can be obtained in a range of 30% by weight or less for the purpose of improving the copolymerization rate. From the viewpoint of polymerization conversion rate and heat resistance, the composition of the copolymer (B) is 50 to 80% by weight of α-methylstyrene,
It is preferable to use 10 to 30% by weight of acrylonitrile and 5 to 30% by weight of methyl methacrylate. More preferably, the composition is in a range surrounded by the following coordinate points A, B, C, D, and E in the triangular coordinate system consisting of α-methylstyrene, acrylonitrile, and methyl methacrylate.

[Table] The above copolymer can also be obtained by a one-stage polymerization method, but the polymerization is carried out in two stages.In the first stage, 60 to 85% by weight of α-methylstyrene is added. A monomer mixture consisting of 2 to 30% by weight of methyl methacrylate and 5 to 20% by weight of acrylonitrile is used, preferably 30 to 100% by weight of acrylonitrile is added continuously or intermittently for polymerization. And, in the first step, the polymer is polymerized until it becomes 40% by weight or more of the final polymer, and then, in the second step, the following coordinate point is
Adding the missing monomer so that it becomes a monomer mixture consisting of α-methylstyrene, methyl methacrylate and acrylonitrile within the range surrounded by FGHIJ and having a composition ratio different from that in the first step,
Finally, the above coordinate points A, B, C, D and E
A preferable method is to complete the polymerization reaction at a monomer composition ratio within the range enclosed by .

[Table] The resin composition of the present invention is a composition with excellent weather resistance and heat resistance obtained by mixing a graft copolymer (A) and a copolymer (B) with excellent heat resistance. be. However, graft copolymer (A) and copolymer (B)
Although the heat resistance and impact resistance of the mixed composition are influenced by the mixing ratio of (A)/(B) = 10/90 to 90/10, to achieve the object of the present invention, It is necessary to mix the rubber components so that the amount of the rubber component in the mixed composition is 5 to 30% by weight. In addition, especially in order to improve the heat resistance of the mixed composition, it is better to increase the rubber component ratio during the production of the graft copolymer, even if the rubber components in the mixed composition are the same. This is advantageous because the mixing ratio of the coalescence (B) becomes high. If (A)/(B) is outside the range of 10/90 to 90/10, the weather resistance and heat resistance that are the objectives of the present invention will not be fully satisfied. The graft copolymer (A) and copolymer (B) may be mixed after completion of polymerization, such as solution-solution or solution-latex, and then recovered, or they may be mixed as powder-powder, powder, etc. A mixture of body pellets and pellets and pellets may be used. It is preferable to add stabilizers, lubricants, pigments, fillers, etc. during mixing or pelletizing, if necessary. The grafting rate of the graft copolymer in the examples is
It was determined using the following method. Dissolve 1 g of the graft copolymer in 40 ml of methyl ethyl ketone (MEK) for 24 hours, and centrifuge twice (8000 rpm - 30 minutes).
Obtain MEK insoluble matter. The acrylonitrile (AN) content is determined from the N content of the MEK insoluble matter and calculated using the following formula. (All % in the following formula is weight %.) Z (Resin component content % in MEK insoluble matter) = AN content (%) in MEK insoluble matter × [100 - Rubber content in total resin (%) ]/AN content in total resin (%) Grafting rate=Z/100-Z×100 Rubber content is calculated from the polymerization rate and the amount charged. Next, the present invention will be specifically explained using examples. In the following Examples and Comparative Examples, parts mean parts by weight, and % means weight %. Example 1 (1) Production method of graft copolymer (A) A homogeneous solution of iodine was prepared in advance in a 10 stainless steel autoclave equipped with a three-stage paddle-type stirring blade, a thermometer, a pressure gauge, and an addition port on the top. 15, Mooney viscosity 50, propylene content 43%, contains 5-ethylidene-2-norbornene as a diene component
25 parts of EPDM, 42 parts of styrene, and 96 parts of toluene were charged and the temperature was raised to 50°C while stirring, followed by 18 parts of acrylonitrile and 0.1 part of tertiary-dodecyl mercaptan.
After adding 0.3 parts of dibenzoyl peroxide and purging with nitrogen, the stirring speed was set to 200 rpm, the temperature was further raised, and a graft copolymerization reaction was carried out while controlling the temperature to 80°C. A phase transition occurred in about 2 hours. At that time, the polymerization conversion rate was 38% and the viscosity was 18000cp.
(value at 50°C). Polymerization was continued under the same conditions, and the temperature was increased 6 hours after the start.
It took 1 hour to bring the temperature to 120°C. The polymerization conversion rate at that time was 83%. From that point on, the polymerization temperature is 120
While keeping the temperature at
It was added continuously over time. The polymerization conversion rate at the end of the additional addition was 95.5%. Furthermore, 1 at 120℃
After holding for a certain period of time, cooling was started. The final polymerization conversion rate was 96.5%, and the viscosity was 2.5 million cp (at 50°C). After cooling to about 90°C, 0.2 part of 2,2'-methylene-bis(4-methyl-6-t-butylphenol) was added as a stabilizer, and after thorough mixing, the reaction mixture was taken out from the autoclave. Volatile components such as residual monomers and solvents are substantially distilled off by steam distillation, and the graft copolymer (A
-1) was obtained. (2) Production method of copolymer (B) 184 parts of ion-exchanged water, 2.4 parts of potassium stearate
A mixture of 58 parts of α-methylstyrene, 12 parts of methyl methacrylate, 5 parts of acrylonitrile and 0.25 parts of tertiary dodecylcaptan was charged into a reactor equipped with a stirrer and purged with nitrogen, and emulsified. After raising the temperature to 40°C with stirring under a nitrogen stream, add 0.16 parts of sodium formaldehyde sulfoxylate, 0.08 parts of sodium ethylenediaminetetraacetate, and 0.003 parts of ferrous sulfate dissolved in 16 parts of ion-exchanged water, and add cumene. hydroperoxide
0.25 part was added to start the polymerization reaction. Control the jacket temperature of the reactor at 60℃ to control the polymerization.
At the end of the hour, add 5 parts of acrylonitrile to 2
When the polymerization was continued for an additional hour, the polymerization conversion rate was 75%, and the remaining monomers were 17.6 parts of α-methylstyrene, 2.0 parts of methyl methacrylate, and 0.4 parts of acrylonitrile. It was hot. Next, 46 parts of ion-exchanged water, 0.6 parts of potassium stearate, 6.4 parts of α-methylstyrene, 6.0 parts of methyl methacrylate, 7.6 parts of acrylonitrile, and 0.15 parts of tertiary dodecylcaptan were emulsified in a separate container. Added. In addition, ion exchange water 4
A solution of 0.04 part of sodium formaldehyde sulfoxylate, 0.02 part of sodium ethylenediaminetetraacetate, and 0.002 part of ferrous sulfate was added to the mixture, and then 0.05 part of cumene hydroperoxide was added, and a polymerization reaction was carried out for 2 hours. The monomer conversion rate at this time was 9.7%. This polymer latex was added to 2,2'-methylenebis(4) as a stabilizer.
After emulsifying and adding 0.2 part of methyl-6-t-butylphenol), calcium chloride was added, solidified by heating, washed with water, dehydrated, and dried to form a copolymer powder (B-
1) was obtained. 60 parts of pulverized graft copolymer (A-1) and 40 parts of powdered copolymer (B-1) were mixed (rubber component
15 parts), pelletized using a 40m/m extruder (200℃, >700mmHg vacuum), made test pieces using a 5oz injection molding machine (cylinder temperature 230℃, mold 50℃), and measured physical properties. did. fluidity, impact resistance,
It has an excellent surface gloss, and when a peel test was performed by bending an ASTM No. 1 dumbbell, no peeling phenomenon was observed. As an index of heat resistance, the following heat shrinkage measurement was performed and the result was 1%.
The temperature at which shrinkage occurred was 122°C. 1% heat shrinkage rate temperature measurement method A 1/8″ x 1/2″ x 5″ test piece was made using an injection molding machine, and after measuring the length _L0 of its longest part, it was placed in a gear aging tester. After leaving it for 1 hour, it was taken out and left at room temperature for 1 hour, and then the length _L1 was measured again.The gear aging test temperature was carried out at several points in a 5°C range at an appropriate temperature.
The temperature at which the heat shrinkage rate (α) determined by the following equation was 1% was calculated. α=L ₀ −L ₁ /L ₀ ×100 (%) Example 2 As a method for producing the graft copolymer (A), the following emulsion polymerization was performed. Add 140 parts of a 15% aqueous solution of disproportionated potassium rosin acid to 1000 parts of a 10% n-hexane solution of the ethylene-propylene-diene copolymer rubber (EPDM) used in Example-1, and emulsify by stirring with a homomixer. let Next, steam distillation is performed to completely remove the solvent and reduce the particle size to 1,000 to 10,000.
An EPDM latex of 1.5 nm was obtained. The rubber solids concentration of this latex was set to 20%, and emulsion graft copolymerization was carried out using the following formulation. EPDM latex (rubber solids concentration 20%)
250 parts Disproportionated potassium rosin acid 15% aqueous solution 3 Potassium hydroxide 0.04 Styrene 14 Acrylonitrile 6 Tertiary dodecyl mercaptan 0.05 After charging the above chemical solution into a reaction vessel and purging with nitrogen, the jacket was heated with stirring, and the inside was heated. temperature is 50
℃, add 0.008 parts of ferrous sulfate, 0.4 parts of sodium pyrophosphate, and 0.5 parts of dextrose dissolved in 20 parts of water, then add 0.06 parts of cumene hydroperoxide, and polymerize for 1 hour at a jacket temperature of 70℃. I do. Next, an emulsified solution containing 21 parts of styrene, 9 parts of acrylonitrile, 9 parts of tertiary dodecyl mercaptan, 0.02 15% aqueous solution of disproportionated potassium rosin acid, 6 parts of potassium hydroxide, 0.14 cumene hydroperoxide, and 20 parts of water was continuously added over 2 hours. After the addition was completed, the jacket temperature was raised to 80°C and polymerization was continued for an additional hour. The polymerization conversion rate of monomers was 94%. After emulsifying and adding 0.2 parts of 2,2'-methylenebis(4-methyl-6-t-butylphenol) as a stabilizer to the graft copolymer latex thus obtained, calcium chloride was added.
The mixture was solidified by heating, washed with water, dehydrated, and dried to obtain a graft copolymer powder (A-2). This graft copolymer (A-2) and Example-1
The copolymer (B-1) shown in Example 1 was mixed so that the rubber component contained in the mixture was 10%, 15%, 20%, and 25%, and the mixture was treated in the same manner as in Example 1. The physical properties, etc. were measured. As the amount of rubber increases, the impact strength increases, but the heat resistance slightly decreases. In either case, no delamination was observed, and good resins were obtained. Example 3 An α-methylstyrene/acrylonitrile copolymer was produced as copolymer (B) in the following manner.
184 parts of ion-exchanged water, 2.4 parts of potassium stearate
A mixture of 67.2 parts of α-methylstyrene, 6.4 parts of acrylonitrile, and 0.32 parts of tertiary dodecyl mercaptan was charged into a reactor equipped with a stirrer and purged with nitrogen, and emulsified. After raising the temperature to 40°C with stirring under a nitrogen stream, 0.16 parts of sodium formaldehyde sulfoxylate, 0.08 parts of sodium ethylenediaminetetraacetate, and 0.003 parts of ferrous sulfate dissolved in 16 parts of ion-exchanged water were added, and cumene was added. 0.25 parts of hydroperoxide was added to initiate the polymerization reaction. Reactor jacket temperature to 60
After polymerization was carried out for 1 hour while controlling the temperature at It was 1.6 parts. Next, 46 parts of ion-exchanged water, 0.6 parts of potassium stearate, 10.8 parts of α-methylstyrene, 9.2 parts of acrylonitrile,
A mixture containing 0.18 parts of tertiary dodecyl mercaptan was emulsified in a separate container and added. Furthermore, a solution of 0.04 parts of sodium formaldehyde sulfoxylate, 0.02 parts of sodium ethylenediaminetetraacetate, and 0.002 parts of ferrous sulfate in 4 parts of ion-exchanged water was added, and then 0.05 parts of cumene hydroperoxide was added, followed by polymerization for 2 hours. The reaction was carried out. The monomer conversion rate at this time was 96%. Calcium chloride was added to this polymer latex for salting out coagulation, washing with water, dehydration, and drying to obtain a copolymer powder (B-2). Graft copolymer powder of Example 2 (A-2)
and this copolymer (B-2) with a rubber component of 15%.
The mixture was mixed in the same manner as in Example 1, and the physical properties were measured. Impact strength and heat resistance were good, and no delamination was observed. Example 4 An α-methylstyrene, styrene, acrylonitrile copolymer was produced as the copolymer (B) in the following manner. A mixture of 120 parts of ion-exchanged water, 2 parts of potassium stearate, 31 parts of α-methylstyrene, 5 parts of styrene, 14 parts of acrylonitrile, and 0.3 parts of tertiary dodecyl mercaptan was charged into a reactor equipped with a nitrogen-substituted stirrer. Emulsified. After raising the temperature to 40°C with stirring under a nitrogen stream, 0.20 parts of sodium formaldehyde sulfoxylate, 0.10 parts of sodium ethylenediaminetetraacetate, and 0.005 parts of ferrous sulfate were dissolved in 16 parts of ion-exchanged water.
of cumene hydroperoxide
0.15 part was added to start the polymerization reaction. Control the jacket temperature of the reactor at 60℃ to control the polymerization.
After hours, 100 parts of ion-exchanged water, 1 part of potassium stearate, 31 parts of α-methylstyrene,
1 part, 5 parts of styrene, and 14 parts of acrylonitrile (same composition and monomer ratio as the initial addition) were added over 3 hours. After the addition was completed, stirring was continued for an additional hour to carry out polymerization. The monomer conversion rate was 97%. Calcium chloride was added to this polymer latex for salting out coagulation, washing with water, dehydration, and drying to obtain a copolymer powder (B-3). Graft copolymer powder of Example 2 (A-2)
and this copolymer (B-3) with a rubber component of 15%.
Mixed so that
Physical properties were measured. Although the heat resistance was slightly lower, a resin with good impact strength was obtained. No delamination was observed. Examples 5 to 7, Comparative Examples 1 to 2 Copolymers (B) were produced by changing the proportions of α-methylstyrene, styrene, and acrylonitrile in Example 4, and the physical properties of the mixed composition were evaluated in the same manner as in Example 4. The physical properties were measured. It can be seen that when a copolymer (B) containing less than 50% α-methylstyrene or more than 30% styrene is used, the heat resistance is significantly reduced. Comparative Example 3 Graft copolymer (A) and copolymer (B) were not produced separately, but a graft copolymer was produced using α-methylstyrene, styrene, and acrylonitrile as graft monomers by the following method. did. The rubber component and monomer component were kept in the same proportions as in Example 4. EPDM latex (rubber solids concentration 20%) 75 parts Disproportionated potassium rosin acid 15% aqueous solution 5 Potassium hydroxide 0.04 α-methylstyrene 17.36 Styrene 7 Acrylonitrile 9.64 Ion exchange water 100 Charge the above chemical solution into a reaction vessel and replace with nitrogen. After that, warm the jacket while stirring until the internal temperature reaches 50℃.
When the temperature reaches ℃, add 0.008 parts of ferrous sulfate, 0.4 parts of sodium pyrophosphate, and 0.5 parts of dextrose to ion-exchanged water.
Add 20 parts of the solution, add 0.1 part of cumene hydroperoxide, and adjust the jacket temperature.
Polymerization is carried out at 70°C for 1 hour. Next, an emulsified solution of 26.04 parts of α-methylstyrene, 10.5 parts of styrene, 14.46 parts of acrylonitrile, 15% aqueous solution of disproportionated potassium rosin acid, 10 parts of potassium hydroxide, 0.18 parts of cumene hydroperoxide, and 60 parts of ion-exchanged water was added continuously over 2 hours. After the addition was completed, the jacket was heated to 80°C and polymerization was continued for an additional hour. The polymerization conversion rate of monomers was 92%. Calcium chloride was added to the copolymer latex obtained in this way, and it was solidified by heating.
A graft copolymer powder was obtained by washing with water, dehydration, and drying. This powder was treated in the same manner as in Example 1 and its physical properties were measured. In terms of impact strength and heat resistance, it is inferior to the mixed composition obtained in the examples of the present invention,
A delamination phenomenon was observed in the dumbbell bending test.

[Table] Shows the results of accelerated weathering tests on resins using the compositions of Examples 1 and 2. 1/8″× as test piece
A 1/2" x 5" bar was prepared and the unnotched impact strength was measured at -30°C. Accelerated weathering tests are conducted using Sunshine Weather-Ometer (Suga Test Instruments WEL).
6XS-DC, black panel temperature 63±3℃, humidity
60±5%, rainfall cycle 18/120) was used.

【table】

Claims (1)

[Claims] 1 Ethylene-propylene copolymer rubber or ethylene-propylene-diene copolymer rubber 15-70
A monomer mixture consisting of 60-80% by weight of styrene and 20-40% by weight of acrylonitrile in the presence of parts by weight 85
Graft copolymer (A) obtained by graft copolymerizing ~30 parts by weight with α-methylstyrene 50-80% by weight, acrylonitrile 10-30% by weight, styrene or/
and a copolymer (B) obtained by copolymerizing a monomer mixture consisting of 0 to 30% by weight of methyl methacrylate,
(A)/(B) = 10/90 to 90/10 mixture, and the above rubber component in the mixture is 5 to 30% by weight, and has excellent weather resistance and heat resistance. Plastic resin composition.