JPH0310660B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to blends of graft copolymers and resins. In particular, this relates to blends of α-methylstyrene/nitrile monomer/diene rubber graft copolymers with styrene/acrylonitrile or with styrene/acrylonitrile/α-methylstyrene resins. The number average particle size of the particles of the diene rubber (to which the alpha-methylstyrene and copolymerizable nitrile monomers are grafted) is from 400 to 1500 Angstroms in diameter. Monomers M ₁ and M ₂ are the spine
During the grafting reaction to graft onto S, a significant portion of M ₁ and M ₂ will copolymerize to yield the M ₁ -M ₂ resin, which is not itself part of the graft copolymer but is then No separation. Co-pending U.S. Patent Application No. 824,467 (Geelan) filed August 15, 1977, and U.S. Pat.
2908661; 3367995 and 3594453 are acrylonitrile and α grafted onto a diene rubber backbone.
- Graft copolymers with methylstyrene and/or styrene are disclosed. Co-pending applications and US Pat. No. 3,594,453 further disclose the use of small particle size (average particle diameter generally less than 2000 Angstroms) rubbers. There is no disclosure in this application and any of the three patents of the formulation of such a graft polymer with any resin; nevertheless, using the examples cited above, the graft copolymer products of this application and patent Analysis of will indicate the presence of the _M1 - _M2 resin. Obviously, each such resin would not be able to contain monomers not used in the original grafting mixture. US Patent Nos. 3,010,936 and 3,624,183 disclose that graft copolymers can be blended with separately prepared resins. The former patent ('936) is based on acrylonitrile, α
- discloses graft polymers of nitrile monomers, styrene or alpha-methylstyrene and polybutadiene blended with methylstyrene and optionally styrene resins, in which the graft/resin ratio is from 50/50 to 70/ Up to 30.
The patent does not mention the size of the rubber backbone particles. The latter patent ('183) describes a graft copolymer of styrene, acrylonitrile, and polybutadiene of large particle size (average particle size from 2000 to 5000 angstroms) blended with a resin of styrene and/or alpha-methylstyrene and acrylonitrile. Disclose. If a graft copolymer of (a) nitrile monomer, (b) alpha-methylstyrene (AMS), and (C) small particle size (sps) diene rubber is made separately, (S) styrene, (b) acrylonitrile, and
In some cases, when blended with a resin of (c) alpha-methylstyrene, the resulting blend unexpectedly shows that the separately produced resin is not the same as the resin originally present in the graft copolymer product (i.e., the previous resin). M ₁ − discussed in
_M2 resin) was found to have substantially better physical properties (particularly impact strength) than formulations that are identical to the M2 resin. The formulations described and claimed herein are generally less productive.
This is because sps rubber is cheaper to produce than large particle size (lps) rubber. In producing the graft polymer of the present invention,
Copolymerizable monomer is acrylonitrile (ACN)
is preferred; however, methacrylonitrile and ethacrylonitrile can also be used effectively. Mixtures of the above nitrile monomers may also be used. The ratio of alpha-methylstyrene to nitrile monomers used during the grafting reaction is from 50/50 to 90/10 (i.e. AMS is 50 to 90% of the monomer mixture), and most preferably 60/
It ranges from 40 to 80/20. In the graft copolymer, the ratio of total monomer (alpha-methylstyrene plus nitrile) to rubber backbone is 75/25 to 25/75.
up to, usually from 60/40 to 30/70, and preferably from 50/50 to 40/60. The rubber backbone may be any diene rubber, such as natural rubber, polybutadiene, polyisoprene, or polychloroprene, and may be made using techniques known in the art. Preferred diene rubbers are polybutadiene and copolymers of butadiene and up to 40% of one or more copolymerizable monomers, preferably styrene. Other copolymerizable monomers that may be used in the backbone include α-methylstyrene, acrylonitrile,
methacrylonitrile, ethacrylonitrile, acrylic acid, acrylic ester, vinylpyridine,
and similar things. The most preferred backbone is polybutadiene or poly(butadiene styrene) rubber containing up to 10% styrene. Rubber is used as a latex and usually contains less than 40% solids if all sps.
In the case of lps rubber, the latex will contain up to 60% solids. The rubber used for graft polymerization ranges from 400 to 1500 angstroms, typically from 400 to 1200 angstroms,
and preferably have a number average particle size of 400 to 1000 Angstroms. The graft polymerization reaction may be carried out using the methods taught in U.S. Pat.
No. 824,467 (Geelan) may be used.
This application is also incorporated herein by reference. According to the latter method, the graft polymerization reaction is carried out in an aqueous medium. The total amount of water in the reaction mixture is from 100 to 250 parts and preferably from 150 to 180 parts per 100 parts of the total amount of monomer plus rubber solids. (Other materials present in the grafting reaction mixture are also given on the same basis, i.e. parts per 100 parts by weight of the total monomer plus rubber solids.) Although it is possible to use more than 250 parts of water, In this case, the size of the device increases without any increase in productivity, which is economically questionable. Any anionic emulsifier commonly used in graft reactions may be used. Optionally, the emulsifier is used in conjunction with a dispersing agent, such as the sodium salt of polymerized alkylnaphthalene sulfonic acid. Examples of emulsifiers that can be used are the sodium and potassium salts of oleic and stearic acids, the sodium salts of sulfate half-esters (eg sodium lauryl sulfate), and saponified mixtures of fatty acids and/or rosin acids. Usually the emulsifier is potassium oleate or sodium lauryl sulfate, and preferably sodium lauryl sulfate is used in combination with the dispersing agents mentioned above. The amount of emulsifier used is from 1 part to 4 parts and preferably from 1.5 parts to 2.5 parts. The graft polymerization catalyst (or initiator) used is one-component and can be any water-soluble free radical polymerization initiator, such as hydrogen peroxide, potassium,
Use sodium or ammonium persulfates, peracetates, or percarbonates, alone or in combination. Potassium persulfate initiators are preferred.
The amount of initiator used is from 0.1 to 0.8 parts and
The amount is preferably from 0.3 to 0.6 parts. Molecular weight modifiers are optionally included in the reaction mixture. Such modifiers are added to inhibit subsequent polymerization by acting as chain terminators and to control the molecular weight of the polymer, which in turn affects the balance of impact strength to flow properties. . Mercaptans, like terpinolene, are particularly useful. Most preferably, the modifier is a mixture of tertiary C ₁₂ , C ₁₄ and C ₁₆ mercaptans in approximately a 60/20/20 ratio. This mixture is known in the art as "MTM". The amount of regulator used is from 0 to 0.8 parts and preferably from 0.4 to 0.7 parts. The reaction temperature depends to some extent on the initiator used, but is generally between 125° and 200° (52° and 93°).
°C), and most preferably from 150° to 170°C (66° to 77°C). The grafting reaction is carried out in one reaction step under an inert atmosphere, usually under a nitrogen atmosphere. The pressure in the reaction vessel is sufficient to maintain the reaction mixture in the liquid phase and is generally from 5 to 90 psig, and preferably from 15 to 40 psig.
That's it. Higher pressures can also be used, but are not economically justified. The reaction time depends on the catalyst concentration, reaction temperature, reactor type,
and the rate of addition of reactants. Generally the time required for the reaction will be from 1 to 12 hours, and usually from 4 to 8 hours. The reaction vessel is preferably a pressurizable, jetted tank reactor, which is equipped with stirring means. The shape of the reactor is not critical, as will be understood by those skilled in the art. For example, plug-flow (plug-flow) with multiple feed points
−flow) reactors could be used. Generally, the procedure for carrying out the grafting reaction is as follows. Place the rubber latex into the reactor. An aqueous solution of the soap ingredients (ie, emulsifiers, dispersants, and chelating agents) is made and a portion thereof is added to the latex in the reactor along with the initiator and any additional water required. Heat the mixture to reaction temperature. The monomer and remaining soap solution are then added continuously or in batches, usually over a period of about 3 hours. This conversion is usually followed by an additional 3 hours for complete reaction. At the end of this time, the reactor is cooled and the graft copolymer is recovered by standard coagulation and drying techniques. In this way, the graft copolymer can be blended with the resin at any time. Modifications to this procedure are possible to be understood by those skilled in the art. The resin used here is either styrene-acrylonitrile (SAN) or alpha-methylstyrene-styrene-acrylonitrile (ASAN). Styrene/acrylonitrile ratio in SAN resin ranges from 60/40 to 95/5, typically 65/35
to 85/15 and preferably 70/
It ranges from 30 to 80/20. ASAN resin starts from 15
up to 75% AMS, 5 to 50% ACN, and 15 to 75% styrene; usually 40 to 60
AMS up to %, ACN from 15 to 45%, and
15 to 25% styrene; and preferably
AMS from 50 to 60%, from 20 to 30%
Contains ACN, and 15 to 20% styrene. The resin is US Pat. No. 3010936; 3288731 and
No. 3,624,183, which patents are hereby incorporated by reference. In the formulations of the invention, the graft copolymer/resin ratio is from 20/80 to 45/55, preferably 25/75.
to 35/65. Compounding may be accomplished by standard methods such as mixing the graft and resin latex together and coagulating or dry compounding the resin and graft. The following examples are provided to further illustrate the invention. However, it will be appreciated that the examples are for illustrative purposes only and are therefore not intended to limit the scope of the claims. EXAMPLES Various blends of graft copolymers and resins are made and tested to determine their physical properties. The graft copolymers for Experiment A shown in the following table are made as follows (all parts are by weight and rubber base plus monomer):
(based on 100 copies). A two-stand reactor equipped with a 60 rpm stirrer, reflux condenser, two dropping funnels, and a thermometer and heated with a 66° C. oil bath is used. 55 parts sps styrene-butadiene rubber (dry basis, 37% solids latex, number average particle size of approximately 540 angstroms,
7/93 styrene/butadiene weight ratio) into the reactor. Stir 1.6 parts of sodium lauryl sulfate into 10.7 parts of distilled water in a second container. Potassium persulfate catalyst (0.375 parts) is dissolved in 20 parts of warm (below 50°C) distilled water in a third vessel. Sodium sulfate (0.7 parts), ethylenediaminetetraacetic acid trisodium salt (0.01 parts) and naphthalene sulfonate (1.6 parts) are dissolved in 80.7 parts of warm (below 50°C) distilled water in a fourth vessel. Part of sodium lauryl sulfate solution (2.68 parts)
in a fourth vessel, stir and add the resulting solution to the reaction vessel. Place the remaining 9.62 parts of the sodium lauryl sulfate solution into one of the dropping funnels. 31.1 parts AMS, 13.9 parts ACN and 0.6 parts
Mix the MTM together in a fifth container. A portion of this mixture (9.12 parts) is charged to the reactor when the reactor temperature reaches 61°C. Residual AMS−ACN−
Add 36.48 parts of MTM mixture into another dropping funnel. When the temperature of the reaction vessel reaches 62° C., begin continuous feeding of monomer and soap solution in the two dropping funnels. Addition is complete in 2 hours. This is followed by heating for 3 hours followed by cooling. In a separate compounding vessel, 84.2 g of the graft copolymer latex (31.9% solids) was then placed into 200.9 g of a separately prepared SAN resin emulsion (75% styrene, intrinsic viscosity 0.43, 36.4% solids). and stir to form a graft-resin blend. 4.5g
25% solid antioxidant emulsion [0.90 part tri(mixed mono-dinonyl)phenyl phosphite, 0.45 part 2,2'-methylenebis-(4-methyl-6-nonylphenol), and 0.90 part alkylated diphenylamine ] in a mixing container and stir. This mixture was then mixed with 7g of water in 700g of distilled water.
Pour into a coagulation vessel containing MgSO ₄ solution at 210 °C (99 °C) and stir. Adjust the rate of addition of the mixture to maintain the temperature within ±2°C. After the addition is complete, the contents of the vessel are stirred for an additional 10 minutes and the coagulated material is recovered from the mixture by vacuum filtration, which is then added to 700 g of freshly distilled water. This washing mixture is then heated to 100 °C (38 °C)
Heat to and stir for 10 minutes. A refiltration and a second water wash are then carried out at room temperature. The recovered graft-resin mixture is dried in an air oven at 60°C for 24 hours. To prepare the formulation for physical property testing, add 2 parts of ethylene bis(stearamide) lubricant to the dry formulation and mix vigorously. The test substance was kneaded in a machine at 320°C (180°C) for 10 minutes, then cut into samples.
Compression mold at 350㎓ (177℃) under 3000psi for 10 minutes. The physical properties of the samples are measured according to the following ASTM methods: Notched Izod Impact Strength, D-256 (Method A); Rockwell Hardness, D-
785; Tensile strength, D-638; Heat deflection temperature, D-
678. The other formulations in the table are similarly prepared and tested using the ingredients and amounts indicated therein. In the table, formulations A, F, G and I are within the scope of the invention and the other formulations are outside the scope. Formulation A includes AMS-ACN-spsSBR graft copolymer and SAN resin. This formulation has good impact strength and low viscosity and is suitable for injection molding. Formulation B is such that the resin of B is AMS/ACN;
It is the same as A except that it is the same resin that is produced during the grafting reaction when the graft used for is made. (The resin emulsion used is 69%
styrene, containing 44.4% solids and having an intrinsic viscosity of 0.56). Formulation B has a lower impact strength and a substantially higher viscosity than Formulation A;
This makes B less desirable for injection molding. This demonstrates that novel and unexpected results are obtained by practicing the present invention. Formulation C differs essentially from A only in the substitution of styrene for AMS in the graft copolymer. The impact strength of C is extremely poor, making it unsuitable for applications requiring good impact strength. Formulation D is sps in the backbone of the graft copolymer.
It differs from A only in that the rubber is replaced by lps rubber (number average particle size of approximately 2100 angstroms). Formulation D has significantly lower impact strength than A. Moreover, the production cost of Formulation D is higher due to the higher price of LPS rubber compared to SPS rubber. Formulation E differs essentially from A in that it uses lps rubber and styrene instead of sps rubber and AMS, respectively. E also exhibits low impact strength. Formulation F uses a low-rubber graft (monomer/rubber ratio 65/35 versus 45/55 in A) and a high graft/resin ratio (41.1/58.9 versus 26.8/73.2 in A). It differs from A in the use of . Although impact strength is low, other properties are excellent. Formulation G has very low monomer/
Differs from A in the use of a rubber ratio (25/75 vs. 45/55 in A) and a lower graft/resin ratio (20.1/79.9 vs. 26.8/73.2 in A). The properties are not the best except for the properties towards flow. Formulation H is the same as G except that AMS/ACN resin is used instead of SAN. Formulation I is within the scope of the invention, but
ASAN resin (53% AMS, 18% styrene, 29%
Same as A except for the use of ACN). Formulation I exhibits significant impact strength combined with good tensile strength. This formulation once again illustrates the surprising advantages of the present invention. Formulation J is essentially the same as I except that 1/4 of the AMS in the graft is replaced by styrene. This substitution substantially reduces impact strength but has little effect on other physical properties.

Although specific embodiments of the invention have been shown and described herein, it will be obvious to those skilled in the art that various changes and modifications may be made thereto without departing from the essence of the invention. It is therefore intended that the appended claims cover all changes and modifications falling within the true spirit and scope of the invention.

Claims (1)

[Scope of Claims] 1 (A) a graft copolymer containing α-methylstyrene and a copolymerizable nitrile monomer grafted onto a diene rubber backbone; (B) styrene and acrylonitrile or consisting of styrene, acrylonitrile and α-methylstyrene; and a resin, the weight ratio of graft copolymer to resin is from 20/80 to 45/55, and the rubber content of the graft copolymer is from 25 to 75% by weight,
A formulation characterized in that the diene rubber is polybutadiene or poly(butadiene/styrene) and the number average particle size of the rubber backbone particles is from 400 to 1500 angstroms in diameter. 2. The formulation according to claim 1, wherein the copolymerizable nitrile monomer is acrylonitrile. 3. A formulation according to claim 1, wherein the number average particle size is from 400 to 1000 angstroms in diameter. 4. A formulation according to claim 1, wherein the rubber content of the graft copolymer is between 40 and 70% by weight. 5 Graft copolymer to resin weight ratio is 25/75
4. A formulation according to claim 4, which has a molecular weight of 35/65 to 35/65. 6. A formulation according to claim 4, wherein the copolymerizable nitrile monomer is acrylonitrile. 7 The number average particle size of the rubber main particles is 400 in diameter.
5. A formulation as claimed in claim 4, wherein the particle diameter is from 1000 angstroms to 1000 angstroms. 8 Graft copolymer approximately 31% α-methylstyrene, approximately 55% poly(butadiene/styrene),
and about 14% acrylonitrile; the resin includes about 75% styrene and about 25% acrylonitrile; and the graft copolymer/resin weight ratio is about 27/73. compound. 9 Graft copolymer approximately 31% α-methylstyrene, approximately 55% poly(butadiene/styrene)
and about 14% acrylonitrile; the resin contains about 53% alpha-methylstyrene, about 29% acrylonitrile, and about 18% styrene; and the graft copolymer/resin weight ratio is about 27/73.
A formulation according to claim 1.