JPH0521128B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a new and useful method for producing a styrenic copolymer resin, and more specifically, to a method for producing a new and useful styrene-based copolymer resin, and more specifically, in the presence of a rubbery polymer, monomers containing styrene and methacrylic acid as essential components are polymerized in specific proportions. The present invention relates to a method for producing an impact-resistant styrene/methacrylic acid copolymer resin, which is particularly excellent in heat resistance and surface gloss, by grafting the resin. In general, polystyrene resin is widely used as a molding material due to its excellent transparency, dimensional stability, and moldability. However, among various thermoplastic resins, it lacks heat resistance.
In addition, poor chemical resistance has been pointed out as a drawback of this polystyrene resin. Therefore, in order to improve this drawback, styrene
Although maleic anhydride copolymer resin (hereinafter also referred to as SMA resin) and styrene-acrylonitrile copolymer resin (hereinafter also referred to as AS resin) have been proposed, the former is made by randomly adding a small amount of maleic anhydride. In order to copolymerize and make a resin suitable for molding materials, special equipment and techniques are required due to the high degree of alternating copolymerization of both monomers, and water quality problems such as suspension polymerization are required. There are also manufacturing technology limitations such as the inability to employ polymerization methods that use a medium, and on the other hand, the latter has drawbacks such as insufficient heat resistance and the resin being easily colored. By eliminating these drawbacks of conventional resins,
In addition, in order to provide a styrene-methacrylic acid copolymer resin (hereinafter also referred to as SMAA resin) as a transparent resin that has both heat resistance and oil resistance properties, the applicant has created a transparent resin based on such SMAA resin. We have previously filed a patent application for the resin composition (Japanese Patent Application Laid-Open No. 58-96641). In particular, the SMAA resin according to this patent application has a heat resistance of 20 to 30°C compared to the polystyrene resin.
It has high commercial value as a heat-resistant molding material due to its high heat resistance and excellent transparency, but on the other hand, its poor impact resistance is cited as a drawback, which limits its field of application. . In other words, if impact resistance could be added to this SMAA resin while retaining its original properties, it would be useful in fields where both heat resistance and impact resistance are required, namely instrument panels. , automotive parts such as heater ducts and tail lamp housings; home appliance parts such as air conditioner ducts, breaker covers, TV cabinets, hair dyes and iron handles; VTR tape cassettes, audio tape cassettes, and floppy discs. OA related parts such as cases and OA equipment housings;
For various fields such as optical related parts such as camera and projector housings and slide magazines; food container parts such as microwave tableware; and various insulation materials such as construction insulation materials, kotatsu insulation materials, and container insulation materials. It is clear that this will lead to further expansion of applications. However, the reality is that impact-resistant styrene/methacrylic acid copolymer resins having properties suitable for these various uses have not yet been developed. However, as a result of intensive studies to improve the various drawbacks of the various conventional resins described above, the present inventors have determined that styrene and methacrylic acid are essential in the presence of a rubbery polymer. They discovered that a copolymer resin obtained by graft polymerizing vinyl monomers in specific proportions can dramatically improve impact strength while retaining its inherent heat resistance. The present invention has now been completed. That is, the present invention comprises 3 to 70 parts by weight of a rubbery polymer, 97 to 70% by weight of styrene, and 3 to 30% by weight of a rubbery polymer.
The total amount of monomers consisting of methacrylic acid and, if necessary, other vinyl monomers copolymerizable with the styrene within the range of 1 to 20% by weight of the styrene. The present invention provides a method for producing a novel styrenic heat-resistant and impact-resistant resin, which is characterized by polymerizing and grafting 97 to 30 parts by weight of styrene-based heat-resistant and impact-resistant resin. What is particularly important for improving impact resistance is that the rubbery polymer is grafted with a vinyl monomer that essentially includes styrene and methacrylic acid. In order to clarify this fact, for example, "Reurex A-15" [Dainippon Ink & Chemicals Co., Ltd.]
When attempts were made to melt-knead SMAA resin produced by the company and various diene-based rubbery polymers, no improvement in impact resistance was observed. i.e. polybutadiene (BR), styrene-butadiene rubber (SBR)
Even if we try adding other materials such as acrylonitrile-butadiene rubber (NBR), it only results in disadvantages such as a decrease in heat resistance, and the improvement in impact resistance is negligible. Izot impact strength (ASTM D-256, notched, 1/4 inch thick)
It is also known from the fact that it is only 3 kg cm/cm, which is poor in practical use. In addition, various impact-resistant resins such as high-impact polystyrene resin (HIPS resin), acrylonitrile-butadiene rubber-styrene copolymer resin (ABS resin) or methyl methacrylate-butadiene rubber-styrene copolymer resin (MBS resin) are used. ) and SMAA
Even when melt-kneaded with a resin, the phenomenon of delamination was observed in the molded products, and it is also known that no products with excellent mechanical strength could be obtained. Therefore, the method for producing a styrenic copolymer resin of the present invention includes 3 to 70 parts by weight of a rubbery polymer and a vinyl monomer that essentially includes styrene and methacrylic acid.
In this method, the vinyl monomers styrene and methacrylic acid are used in a ratio of 97 to 70 weight percent styrene and 3 to 30 weight percent methacrylic acid, respectively. If necessary, 1 to 20% by weight of the styrene may be substituted with other vinyl monomers copolymerizable with the styrene. In the above manufacturing method of the present invention, the grafting rate, that is, the percentage of monomer grafted to the rubbery polymer, is an important factor regarding the impact resistance of the styrenic copolymer resin, and the grafting rate is 3 to 3. 300%,
Among these, a range of 3 to 150% is preferable. Here, the graft rate is calculated by the following formula. Grafting rate (%) =
Solvent insoluble content (g) - Rubber polymer amount (g) / Rubber polymer amount (g)
)×100 However, as a solvent, toluene/methanol =
A mixture of 9/1 (volume ratio) was used. Representative examples of the above-mentioned rubbery polymers include BR, SBR, NBR, and ethylene.
Propylene polyene rubber (EPDM), etc., and the amount used is 3 to 70 parts by weight, when the total graft copolymerization component is 100 parts by weight.
A suitable range is preferably 3 to 50 parts by weight. If it is less than 3 parts by weight, the impact resistance will actually be improved.
On the other hand, if it exceeds 70 parts by weight, molding becomes extremely difficult, resulting in difficulties in molding processability. Further, the amount of methacrylic acid used in the vinyl monomer is suitably within the range of 3 to 30% by weight.
If it is less than 3% by weight, it is difficult to expect an improvement in heat resistance, and if it exceeds 30% by weight, the melt viscosity becomes high and molding becomes difficult, resulting in problems in moldability. Furthermore, the appropriate amount of styrene in the vinyl monomer is within the range of 97 to 70% by weight,
Of this, 1 to 20% by weight of this styrene may be replaced with other copolymerizable vinyl monomers. Representative examples of such copolymerizable vinyl monomers include 〓-methylstyrene, t-
These include butylstyrene, halogen-substituted styrene, vinyltoluene, (meth)acrylonitrile, -chloroacrylonitrile, (meth)acrylic acid ester, and the like. Next, in preparing the target resin by the method of the present invention, a method generally known as a graft polymerization method for obtaining an impact-resistant resin, that is, (1) converting a rubbery polymer to a vinyl monomer. (2) The so-called bulk polymerization method, in which the polymer is dissolved and polymerized at 60 to 150°C in the presence or absence of an initiator. The so-called solution polymerization method is carried out in a diluted state using a solvent for the purpose of facilitating polymerization. (4) Graft polymerization using latex-like rubber as the rubbery polymer and peroxide as an initiator in an emulsified state at 40 to 100°C. to do
Although methods such as the so-called emulsion polymerization method can be applied, it has high impact resistance.
In order to obtain a resin of excellent quality, it is necessary to use a special method among the emulsion polymerization methods listed above (4). In other words, both the bulk polymerization method (1) and the solution polymerization method (2) are mass-produced methods that require large scale and equipment costs. In addition, as the rubber content increases, stirring or transportation becomes difficult, so it is easy to be subject to regulations.Also, even if the bulk-suspension polymerization method (3) is used, the rubber concentration (rubber content) becomes difficult. )
As the rubber content increases, the viscosity also increases, which tends to lead to troubles such as agglomeration of dispersed particles up to the suspension process.Usually, the rubber content is limited to 8 to 10% by weight, and therefore the physical properties and It is impossible to expect any improvement in appearance, and of course it becomes difficult to expect high impact resistance, and (4)
In this case, methacrylic acid enlarges or destroys the latex, making the system unstable during polymerization and often leading to clumping. ) is deactivated, and this phenomenon is often observed in emulsion systems in which such acid group-containing monomers are used. However, as a result of intensive research by the present inventors in order to overcome the difficulties in the conventional technology,
In the emulsion polymerization method, we discovered that the method of adding methacrylic acid significantly affects the stability of the emulsion system and the physical properties of the resulting copolymer resin, and arrived at the method of the present invention. By continuously adding a portion of the methacrylic acid used as the polymerization progresses, agglomeration of the latex during polymerization is suppressed, and in addition, the copolymer composition is made uniform in terms of physical properties. As a result, a product with superior impact strength can be obtained compared to the batch addition method. By following this specific emulsion polymerization method, it is possible to produce copolymer resins with rubber content as high as 70% by weight, so compared to other polymerization methods,
It is possible to obtain a resin with dramatically improved impact strength and excellent surface photo-selectivity. Furthermore, when the impact-resistant resin produced according to the specified emulsion polymerization method, such as the method of the present invention, is kneaded with ready-made SMAA resin, it is easy to adjust the impact resistance, heat resistance, fluidity, etc. Because of this, there is also the added benefit of being able to design and manufacture various products according to their intended use. As is already clear from the above explanation, the copolymer resin of the present invention can of course be produced according to the methods (1) to (4) listed above, but in particular, in order to obtain a resin of excellent quality, The specific emulsion polymerization method described above is suitable for this purpose, and by following the specified method such as the method of the present invention, a molded article with extremely excellent impact resistance, heat resistance, and surface gloss can be obtained. A copolymer resin is obtained, which can be used as a high-grade molding material comparable to conventional engineering plastics in the light electrical, precision equipment, and automobile industries. Next, the emulsion polymerization method, which can also be called the method of the present invention, will be explained in detail.In the following explanation, copolymer resin A is obtained by graft emulsion polymerization of styrene and methacrylic acid using a rubbery polymer latex. On the other hand, the styrene-methacrylic acid copolymer resin used to appropriately adjust the impact strength by melt-kneading resin A will be referred to as copolymer resin B. First, this copolymer resin A has a weight ratio of 3 to 70 parts by weight of rubbery polymer latex (solid content equivalent) and 97 to 70 parts by weight of styrene and methacrylic acid (the former).
Total amount of vinyl monomer mixture 3 to 30 (latter)
These raw materials were mixed and grafted in the presence of an emulsifier and an initiator at a temperature of 40 to 100°C with stirring for 3 to 12 hours. After emulsion polymerization, various inorganic salts such as calcium chloride, magnesium chloride, sodium chloride or sodium sulfate and/or
Alternatively, it can be obtained by adding various acidic substances such as hydrochloric acid, sulfuric acid, or acetic acid to coagulate and precipitate the product, followed by filtration, washing (washing with water), and drying. The initiator, chain transfer agent, antioxidant, etc. used here are not particularly limited, and it goes without saying that known and commonly used ones can be used as they are. However, the type of surfactant (emulsifier) is important for the stability of the emulsion system, and various sulfate-type and sulfonate-type anionic surfactants are suitable for use in this case; The use of metal salts of higher fatty acids, which are commonly used in polymerization, is not preferred because it causes demulsification during polymerization. Typical rubbery polymer latexes used here include polybutadiene latex, SBR latex, NBR latex, and
EPDM latex and the like are available, but especially from the viewpoint of the physical properties of the final product, it is preferable to use a rubber latex with a high gel content (gel content). The amount of methacrylic acid used in the vinyl monomer is an extremely important factor as it greatly affects the heat resistance of the final product, but if it is less than 3% by weight, the effect cannot be fully expressed, and vice versa. If the amount exceeds 30% by weight, the emulsion system becomes unstable and coarse particles are likely to be produced due to destruction of the latex. Furthermore, in order to obtain this copolymer resin (A), the method of adding methacrylic acid is to first charge 1 to 70% by weight, preferably 1 to 50% by weight of the total amount of methacrylic acid at the start of the reaction, The remaining amount, i.e. 99-30% by weight of the total amount of methacrylic acid, preferably
A special method is recommended in which 99 to 50% by weight is added continuously as the polymerization progresses, that is, depending on the degree of progress of the polymerization until the polymerization rate reaches 90%. At this time, if the amount of methacrylic acid initially charged is less than 1% by weight, styrene homopolymer is likely to be formed in the initial stage of polymerization, resulting in a decrease in physical properties; Exceeding this is not preferable because the emulsion system becomes unstable. In addition, in such a specific method, it is preferable that the timing of adding methacrylic acid is set at a time up to a polymerization rate of 90%; if the polymerization rate exceeds 90%, methacrylic acid is no longer substantially present in the copolymerized resin. It will no longer be possible to be taken into account. Graft copolymer resin A obtained in this way
is supplied in powder or pellet form,
It becomes a molding material. On the other hand, the above-mentioned copolymer resin B can be obtained by heat-polymerizing styrene and methacrylic acid in the presence or absence of a polymerization initiator, as described in, for example, the above-mentioned Japanese Patent Application Laid-open No. 58-96641. This can be obtained by Next, Resin A and Resin B thus obtained are kneaded to obtain heat-resistant and impact-resistant resins of various qualities (grades), but at this time, both resins (A) and (B) to be melt-mixed are They can be mixed in any ratio, but preferably within the range of (A)/(B) = 20-70/80-30 (weight ratio). In this case, the rubber content (rubber content) in the final product is suitably in the range of 3 to 70% by weight, particularly preferably in the range of 20 to 40% by weight. If the rubber content is less than 3% by weight, the impact resistance will be low and there will be no practical value; if it exceeds 70% by weight, fluidity and processability will deteriorate, which is not preferable. For kneading both resins (A) and (B), any known method using known and commonly used equipment such as two rolls, a Banbury mixer, and an extruder can be applied. Furthermore, when necessary, when kneading both resins (A) and (B), various known and commonly used additives such as plasticizers, lubricants, stabilizers, ultraviolet absorbers, flame retardants, or blowing agents may be used. Of course, you can do so. The styrenic heat-resistant and impact-resistant resin of the present invention obtained as described above can be easily subjected to injection molding, extrusion molding, press molding, etc. using an ordinary molding machine. Next, the present invention will be specifically explained using Reference Examples, Examples, and Comparative Examples. In the following, all parts and percentages are based on weight unless otherwise specified. Reference Example 1 (Preparation example of SMAA resin) 200 parts of distilled water was placed in a 5L autoclave equipped with a stirring device, and 1 part of partially saponified polyvinyl alcohol as a suspension stabilizer and 0.005 part of sodium dodecylbenzenesulfonate were added and dissolved. Next, 85 parts of styrene, 15 parts of methacrylic acid, 0.2 parts of ditertiary butyl peroxyhexahydroterephthalate, and 0.1 part of tertiary butyl perbenzoate were charged in sequence, and the mixture was stirred at a rotational speed of 400 rpm. The temperature was raised to 90°C and suspension polymerization was carried out for 10 hours, and the reaction was further continued at 120°C for 3 hours. The thus obtained granular SMAA resin was washed,
Dehydrated and dried. Example 1 The following substances were charged into a reactor similar to Reference Example 1. Polybutadiene latex (solid rubber content = 57.4
%) 52 parts Styrene 60〃 Methacrylic acid 3〃 Potassium persulfate 0.3〃 Tertiary dodecyl mercaptan 0.1〃 Sodium dodecylbenzenesulfonate 2〃 Distilled water 200〃 Nitrogen gas was introduced into this reactor and 70% was added under stirring.
The temperature was raised to .degree. C., and after reaching the same temperature, 7 parts of methacrylic acid was continuously added over 3 hours, and emulsion polymerization was further carried out at the same temperature for 2 hours to complete the reaction. 10 of calcium chloride adjusted to 5% based on the solid content of the latex thus obtained.
% aqueous solution was added thereto and coagulated at a temperature of 90 to 110° C. under stirring, followed by filtration, washing with water, dehydration, and drying to obtain a powdery graft copolymer resin. Next, this copolymer resin is coated with ``Irganox''.
1076" (an antioxidant manufactured by Ciba Geigy, West Germany) was added and pelletized using an extruder at a cylinder temperature of 230°C. Thereafter, injection molding was performed using this pellet, and the physical properties of the molded product were measured. The results are summarized in Table 1. Example 2 A target graft polymer resin was produced in the same manner as in Example 1, except that the raw materials to be charged were changed as follows. Thereafter, the same operations as in Example 1 were repeated to measure the physical properties of the resin, and the results are summarized in Table 1. Polybutadiene latex (as above) 52 parts Styrene 50〃 Methacrylic acid* 10〃 Methyl methacrylate 10〃 Potassium persulfate 0.3〃 Tertiary dodecyl mercaptan 0.1〃 Sodium dodecylbenzenesulfonate 2〃 Distilled water 200 parts *However, methacrylic acid Of the 10 parts, 3 parts were added and the remaining 7 parts were added continuously. Example 3 Into a reactor similar to Reference Example 1, the following substances were charged: 82 parts of styrene, 10 parts of methacrylic acid, 8 parts of polybutadiene rubber, 0.08 parts of tertiary dodecyl mercaptan, and 0.08 parts of tertiary dodecyl mercaptan.After sufficiently dissolving at 60°C, they were heated with nitrogen gas. After replacing the inside of the reactor, the temperature inside the reactor was maintained at 110℃ and bulk polymerization was carried out for 4 hours with stirring, and then the reaction solution was
The mixture was cooled to 70°C, and 0.2 part of ditertiary butyl peroxyhexahydroterephthalate and 0.05 part of tertiary butyl perbenzoate were added and dissolved. Next, 0.5 parts of partially saponified polyvinyl alcohol and sodium dodecylbenzenesulfonate were added to this polymerization system.
An aqueous solution prepared from 0.005〃 distilled water and 100〃 was added under stirring to suspend the bulk polymer, and then the temperature was raised to 90℃ and the mixture was heated to 80℃.
Suspension polymerization was carried out for a period of time, and the reaction was further carried out at 120°C for 3 hours. Thereafter, the thus obtained copolymer resin beads were washed and dehydrated in the same manner as in Example 1.
After drying, pelletizing and injection molding, physical properties were evaluated. Example 4 This example shows a blend of graft copolymer resin and SMAA resin, but the same procedure as in Example 1 was carried out except that the amounts of polybutadiene latex and styrene were changed to 87 parts and 40 parts, respectively. A graft copolymer resin was obtained. Next, 20 parts of this graft copolymer resin, 80 parts of the SMAA resin obtained in Reference Example 1, and 0.2 parts of "Irganox 1076" were mixed and pelletized using an extruder with a cylinder temperature of 230°C. . The pellets were then injection molded, and the physical properties of the molded products were measured and are summarized in Table 2. Application Example 1 Pelletization was performed in the same manner as in Example 4, except that the graft copolymer resin obtained in Example 4 was changed to 40 parts, and the SMAA resin was changed to 60 parts.The pellets were then injection molded and the physical properties were evaluated. . The results are summarized in Table 2. Application example 2 Except that the amounts of graft copolymer resin and SMAA resin used were changed to 60 parts and 40 parts, respectively.
The pellets were pelletized and injection molded in the same manner as in Example 4, and the physical properties were measured, as shown in Table 2. Comparative Example 1 Except for using the SMAA resin obtained in Reference Example 1 instead of the graft copolymer resin,
The pellets were pelletized and injection molded in the same manner as in Example 1, and the physical properties were evaluated. The results are summarized in Table 1. Comparative Example 2 70 parts of the SMAA resin obtained in Reference Example 1, 30 parts of "Asaflex 810" [SBR manufactured by Asahi Kasei Corporation],
and 0.2 parts of "Irganotux 1706",
It was pelletized using an extruder with a cylinder temperature of 230°C. Next, injection molding was performed using this pellet, and the physical properties of the molded product were measured. The results are summarized in Table 2, and in particular, the Izot impact strength of this product was 3.0 Kg·cm/cm. The physical properties of each resin obtained in the above Examples, Comparative Examples, and Applied Examples are shown separately in Tables 1 and 2.

[Table] * All polymer compositions in the table are shown in parts.

[Table] *All blend ratios and blend compositions in the table are as follows in parts.
is shown.

Claims (1)

[Scope of Claims] 1. Total amount of monomers consisting of 3 to 70 parts by weight of a rubbery polymer, 97 to 70% by weight of styrene and 3 to 30% by weight of methacrylic acid, and if necessary, the styrene. A total amount of 97 to 30 parts by weight of monomers including other vinyl monomers that can be copolymerized with the styrene within a range of 1 to 20% by weight is polymerized to form a graft. A method for producing a new styrenic copolymer resin. 2. The manufacturing method according to claim 1, wherein the rubbery polymer and the monomer are grafted by emulsion polymerization. 3. A rubbery polymer and a monomer are emulsion-polymerized to form a graft, then a coagulant is added to separate the resin component, and the resin component is washed, dehydrated, and then dried. The manufacturing method according to item 1. 4 Emulsion polymerization is carried out using 1 to 70% by weight of methacrylic acid at the beginning of the polymerization reaction, and then the remaining 99 to 30% by weight until the polymerization rate reaches 90%.
Claim 2 is carried out by adding as the polymerization progresses, and then the polymerization reaction is completed.
Or the manufacturing method described in item 3.