MXPA00012630A - Methacrylic resin modifier composition less dependent on processing conditions - Google Patents

Abstract

A modifier composition for methacrylic resins which can stably give excellent strength under a wide range of injection molding conditions without impairing transparency, color tone, and appearance. The composition comprises an impact modifier, a polymeric processing aid, and a reducing compound. The proportion of the impact modifier to the polymeric processing aid is from 95/5 to 80/20 by weight, and the reducing compound is contained in an amount of 0.25 to 1.25 parts by weight per 100 parts by weight of the sum of the impact modifier and the polymeric processing aid.

Description

COMPOSITION TO MODIFY METACR1LATE RESINS WITH LITTLE DEPENDENCE ON PROCESSING CONDITIONS TECHNICAL FIELD The present invention relates to a composition for modifying a methacrylate resin, which is used for a thermoplastic resin particularly for a methacrylate resin and which can stably give a molding article with excellent strength (impact resistance) without deteriorating the transparency, color, tone and appearance of it, under a wide range of injection molding conditions BACKGROUND OF THE INVENTION A methacrylate resin has been used in lighting devices and outdoor items due to its high transparency and good resistance to the environment. On the other hand, its resistance is not necessarily sufficient, and therefore several classes of impact modifiers have been tried to be added to it. For example, Japanese Examined Patent Publication No. 55-27576 (19809 and 62-230841 (1987), describes a technique for modifying them.) It is necessary that the transparency, color tone and appearance of a resin of methacrylate under a wide range of processing conditions.

However, when the previously described techniques are used to process a methacrylate resin, it is difficult to achieve the requirement that a methacrylate resin be excellent in strength stably without deteriorating the transparency, tone of color and appearance thereof under a wide range of processing conditions. In fact, transparent molded articles can be obtained under limited processing conditions, and the appearance thereof deteriorates due to the agglomeration of the impact modifier during processing. Mainly, if it is raised to a molding temperature to obtain a molded article having high transparency, the article is thermally deteriorated, the color tone thereof is reduced, and a resin which becomes yellowish under slight fluctuation is obtained. the processing conditions. On the other hand, if the injection molding temperature is set at a low level, the appearance of the article becomes such that the transparency thereof deteriorates significantly. As a measure for these problems, some research has been carried out to stably obtain a molded article having high physical properties. For example, a method for using a methacrylate resin having a broad molecular weight distribution to improve the fluidity and the balance between strength and fluidity is disclosed (Japanese Examined Patent Publication No. 1-29210 (1989)), and a technique for mixing an impact modifier with a dispersing agent in the latex state to avoid agglomeration of the impact modifier as a means to reduce the so-called fish eye on the surface of an injection molding (Japanese Examined Patent Publication No. 2-2358 (1990)). However, these were not sufficient from the point of view that a molded article has excellent strength that is obtained without deteriorating the transparency, color tone and appearance thereof under a wide range of injection molding conditions in the present invention. . In the present invention, a composition is provided for modifying a methacrylate resin, which can stably give a molded article excellent in strength without deteriorating the transparency, color tone and appearance therein, under a wide range of molding conditions. by injection.

BRIEF DESCRIPTION OF THE INVENTION In view of these circumstances, the present inventors extensively studied a resin composition having a high strength without deteriorating the characteristics of a methacrylate resin, namely, transparency, color tone and appearance under a wide range of injection molding conditions. . As a result, it was discovered that the above problems in injection molding can be solved by mixing an impact modifier, a polymer processing aid and a reducing compound with a methacrylate resin to integrate the present invention. Primarily, the invention relates to (1) a composition for modifying for a methacrylate resin comprising an impact modifier 5, a polymer processing aid and a reducing compound, wherein the ratio of the impact modifier to the processing aid polymer is from 95/5 to 80/20, by weight, with an amount of the reducing compound from 0.25 to 1.25 parts by weight based on 100 parts by weight of the total amount of the impact modifier and the auxiliary of Processing, (2) the composition for modifying a methacrylate resin of (1) above, wherein the impact modifier is obtained by polymerizing a mixture of monomer comprising (meth) acrylate and an aromatic vinyl monomer in the presence of an acrylic rubber. and / or a conjugated diene rubber, (3) the composition for modifying a methacrylate resin of (1) or (2) above, wherein the polymer processing aid comprises 50 to 70% by weight of methylmethacrylate and 30 to 50% by weight of the other monomer copolymerizable therewith, (4) the composition for modifying a resin of methacrylate of the above (1), (2) or (3), wherein the specific viscosity of the polymer processing aid is from 2.5 to .0 relative to 0.4% by weight of a toluene solution at 30 ° C, (5) the composition for modifying a methacrylate resin of the above (1), (2), (3), or (4) in wherein the reducing compound is a sulfur and / or phosphorus containing compound, and (6) the composition for modifying a resin of l jjj j ^ methacrylate of the above (5), wherein the reducing compound is an organic reducing compound.

PREFERRED MODE FOR CARRYING OUT THE INVENTION In the present invention there is no particular limitation for methacrylate resin, this includes a resin containing at least 50% by weight of methacrylate unit, preferably at least 50% by weight of a methyl methacrylate unit, and any commercially available methyl methacrylate resins can be used. There is no particular limitation for an impact modifier used in the present invention, so long as it can be used in a methacrylate resin. In particular, it is preferable that the modifier be prepared by polymerizing a monomer mixture comprising (meth) acrylate and an aromatic vinyl monomer, to which another copolymerizable monomer may be added depending on the object, in the presence of an acrylic rubber and / or a conjugated diene rubber The latter are very compatible with methacrylate resin to significantly improve the impact resistance of it. As these modifiers, those having several classes of multilayer structures are known and for example, those described in Japanese Examined Patent Publication No. 55-27576 (1980) can also be used. In addition, the polymerization method is not particularly limited, but the known emulsion polymerization method is practically convenient. However, if you add only When the impact modifier to a methacrylate resin is formed, the problem arises that the transparency, color tone and appearance inherent in the methacrylate resin deteriorate depending on the processing conditions. As a conjugated diene rubber, the examples are those rubber which comprise diene monomers such as butadiene, isoprene and chloroprene. As the acrylic rubber, the examples are alkyl acrylates having from 1 to 12 carbon atoms in the alkyl group, such as ethylacrylate, n-butylacrylate, n-octylacrylate, and 2-ethylhexylacrylate. Examples of aromatic vinyl monomers are styrene, o-methylstyrene, m-rnetylstyrene, p-10-methylstyrene, α-methylstyrene and chlorostyrene. Examples of (meth) acrylate are methylacrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (met ) acrylate, isobornyl (meth) acrylate, phenyl (meth) acrylate and benzyl (meth) acrylate, and the like. The polymer processing aid used in the present invention should have a relatively high molecular weight, and it is effective to use the modifier that is several tens of times the molecular weight higher than that which is generally used in the methacrylate resin ( Average molecular weight in weight is approximately 100,000). That is, apart from the technical idea that is generally conceived in the prior art, the addition of a small amount of the polymer processing aid reduces the dependence on transparency in the processing conditions, although the viscosity in the system rises «MÉMÉÜMitfk ^ ÉM ^ Éi slightly. The technical reason speculated for the latter is that the elasticity of fusion in the system becomes high to improve a lower appearance and stabilize the transparency. In addition, an amount of processing auxiliary polymer in the present invention is preferably 50 to 70% by weight of methyl methacrylate in view of compatibility with the matrix. If the amount is less than 50% by weight, the transfer decreases due to the deviation of the refractive index of the matrix. If the amount of methyl methacrylate is greater than 70% by weight, the compatibility of the matrix is reduced due to the increased stiffness of molecule in addition to the relatively high molecular weight, and therefore the transparency becomes adversely low. The aforementioned methylmethacrylate is preferably copolymerized with a softening component. For example, methyl methacrylate is preferably obtained by copolymerizing from 50 to 70% by weight of methylmethacrylate with 30 to 50% by weight of the other copolymerizable monomers. The other copolymerizable monomer is preferably (meth) acrylate of one to eight carbon atoms in the alkyl group other than methyl methacrylate. If necessary, 30% by weight of the (meth) acrylates can be replaced by the other copolymerizable monomers such as styrene and acrylonitrile. Mainly the (meth) acrylate monomers are preferably as the softening component without losing the environmental strength of the methacrylate resin. Examples of the softening component are butyl methacrylate, ethylacrylate, butylacrylate, octylacrylate and 2-ethylexylacrylate, which are preferably used in view of the costs and so forth. As a routine, the refractive index of the polymer processing aid must be adjusted to that of the methacrylate resin as necessary without losing the transparency of the molded article obtained. In addition, the molecular weight of the polymer processing aid should be relatively high as described above. That is, their molecular weight is preferably 2.5 to 5.0 in terms of specific viscosity (? Sp), more preferably 21.5 to 4.0. If the molecular weight of the methacrylate resin is less than 2.5 at specific viscosity, there is no modifying effect in the object of the present invention. On the other hand, if it is more than 5.0, it deteriorates compatibility with the matrix resin at a significantly lower transparency. In this case, the conditions to measure the specific viscosity? sp are the following: That is, the sample is dissolved at a concentration of 0.4% by weight in toluene and the viscosity is obtained using a viscometer at 30 ° C according to the equation? sp = (? -? o) /? o- 15 In this equation,? is the viscosity of the solution and? 0 is the viscosity of the solvent (toluene). The ratio of the impact modifier to the polymer processing aid by weight is 95/5 to 80/20. If the ratio of the polymer processing aid to the impact modifier is greater than 95/5, the effect improving the aforementioned object is less. On the other hand, if the ratio is less than 80/20, the effect to improve the impact resistance is reduced due to the amount of impact modifier and also the transparency is reduced. That is, it is estimated that ¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡Gggjg * ^^ Compatibility of the polymer processing aid including the methacrylate resin as object is reduced due to the relatively high molecular weight of the polymer processing aid, by therefore, it decreases the transparency adversely. As a polymer processing aid, any commercially available products can be used as long as they satisfy the conditions described above. However, if only the impact modifier and the polymer processing aid are added to a methacrylate resin, a resin having high transparency and high impact resistance is obtained, and the transparency thereof is obtained, but the color tone is not improved at all. Finally, the reducing compound in the present invention is a substance that exhibits so-called reducing actions such as the decomposition of peroxide, deoxygenation and hydrogenation in the substance subject to oxidation by oxidative actions such as oxidation and dehydrogenation for the substance. Particularly, it is preferred to use compounds with a structure containing sulfur and / or phosphorus. Examples thereof are a phosphorus-containing reducing organic compound such as lipoforosphor or its derivatives, phosphoric acid or its derivatives and a reducing organic compound containing sulfur such as Tiol, Thioether and sulfoxide. Among these compounds having a structure containing sulfur and / or phosphorus, the reducing compound has a phosphorus-containing chemical structure that includes antioxidants such as the trade names of PEP-4C, PEP-8, PEP-8F, PEP-8W , PEP-11C, PEP-24G, PEP-36, HP-10, 2112.260, 522A, -U-ÍÉAü? üiBi-i ^^^ 329K, 1178, 1500, C, 1354A, 3010, and TPP, which are commercially available from Asahi Denka Kogyo K.K :. The reducing compound has a sulfur-containing chemical structure that includes antioxidants such as the trade names of IRGanox PS800 and Irganox PS802 FL, which are available from Ciba Geigy. The thermal degradation in the molding can be drastically improved by using the reducing compound in combination with the impact modifier and the polymer processing aid. And in that way a molding article having superior impact strength without deteriorating the transparency, color tone and appearance thereof can be obtained under a wide range of injection molding conditions. The amount of the reducing compound is from 0.25 to 1.25 parts by weight based on 100 parts by weight of the total amount of the impact modifier and the polymer processing aid. If the amount is less than 0.25 parts by weight, the improving effect of the stabilizer is less. On the other hand, if the amount is greater than 1.25 by weight, the color tone deteriorates contrarily. There is no particular limitation for a mixing method of the impact modifier, the polymer processing aid and the reducing compound. A method can be used to mutually mix a mixture thereof in the powder state with a methacrylate resin, or the impact modifier, and a method for mixing the impact modifier, the polymer processing aid and the "A reducing compound, which are obtained by polymerization, in a latex state and then mixed in a conventional manner (agglomeration, washing with water, filtration, drying) with the methacrylate resin to be modified. The reducing compound can also be added during the polymerization process of the impact modifier. The composition for modification of the present invention is suitably applied to a thermoplastic resin, particularly a methacrylate resin. An amount thereof is from 5 to 50 parts by weight based on 100 parts by weight of the methacrylate resin. If the amount is less than 5 parts by weight, there is no effect of improving the impact resistance. On the other hand, if the amount is greater than 50 parts by weight, transparency decreases. In the following, the present invention is described in greater detail using examples. However, they are shown for illustrative purposes but the intention is not to limit the scope of the present invention.

EXAMPLES In the examples, the term "parts by weight" as the quantity of each of the starting materials indicates a value that is based on the amount of total monomers used. The evaluation of physical properties in the example was carried out in the following way: (1) Turbidity was measured (%) at 23 ° C according to JIS K 7105, The yellow color of a molded article was evaluated by observation with the eyes uncovered in the sample molded on a white board. The degree of yellow was classified into three levels: low, medium and high in the order of increase in the degree of yellow. (3) The surface appearance of a molded article was evaluated according to the following: OR ... There is no deficiency in appearance X ... The appearance is poor EXAMPLE 1 Preparation of the impact modifier (a) Polymerization of a cross-linked methacrylate polymer (innermost layer). A glass reactor was charged with a mixture with the composition shown below. The temperature thereof was then raised to 80 ° C with stirring under a stream of nitrogen, 1/4 of the portion of a mixture of components of the innermost layer consisting of 25 parts by weight of methylmethacrylate and 0.1 parts by weight of allylmethacrylate. that were added to it to polymerize them for 45 minutes. (component) (parts by weight) Deionized water 220 Boric acid 0.3 Sodium carbonate 0.003 N-lauroyl sarcosinate sodium 0.09 Sodium formaldehyde sulfoxylate 0.09 Sodium ethylenediaminetetraacetic acid 0.006 Ferrous sulphate heptahydrate 0.002 5 The remaining 3/4 portion of the above mixture was continuously added thereto for 1 hour. After the addition, it remained Mix at the same temperature for 2 hours to complete the polymerization. Meanwhile, 0.2 parts by weight of N-lauroyl sarcosinate sodium. A promised diameter of polymer particles in the innermost layer of the interlaced methacrylate polymer latex was 1600 A (as determined by light screening at a wavelength of 546 nm), and the polymerization conversion (amount of polymer formed / quantity of charged monomers (x 100 (%)) was 98%. (b) Polymerization of a rubber polymer The latex of the cross-linked methacrylate polymer obtained in (a) above was maintained at 80 ° C under a stream of nitrogen. After 20 were added thereto, 0.1 parts by weight of potassium persulfate, a monomer mixture consisting of 41 parts by weight of n-butylacrylate, 9 parts by weight of styrene and 1 part by weight of allyl methacrylate were added continuously to the same for 5 hours. Meanwhile, 0.1 was added ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ After addition of the monomer mixture, further 0.05 parts by weight of potassium persulfate was added thereto and the reaction solution was maintained for 2 hours to complete the polymerization. The average particle diameter of the polymer obtained was 2300 A, and the polymerization conversion was 99%. (c) Polymerization of the outermost layer The rubber polymer latex obtained in (b) above is maintained at 80 ° C. After 0.02 parts by weight of sodium persulfate was added thereto, a mixture comprising 24 parts by weight of methylmethacrylate, 1 part by weight of n-butylacrylate and 0.1 parts by weight of t-dodecyl mercaptan was continuously added thereto during 1 hour. After the addition of the monomer mixture, the mixture is maintained for 1 hour to give a grafted copolymer latex with a multi-layered structure. An average particle diameter of the graft copolymer with multiple layer structure was 2530 A, with a polymerization conversion of 99%. The grafted copolymer latex obtained had a multilayer structure and was subjected in a usual manner to coagulation by desalting, heat treatment and drying to obtain a white pulverulent grafted copolymer with multiple layer structure (impact modifier). ^^^^^^^^ e ^ &^^^^^^^ p Preparation of the polymer processing aid A reactor equipped with a stirrer was charged with 200 parts by weight of deionized water, one part by weight of dioctyl sulfoccinate of sodium and 0.03 parts by weight of sodium persulphate. After the oxygen was removed from the atmosphere and the solution in the reaction passed nitrogen, a content thereof was heated to 65 ° C with stirring. A mixture of monomers (mixture A) comprising 60 parts by weight of methyl methacrylate, 15 parts by weight of butyl methacrylate and 15 parts by weight of butylacrylate was added thereto over a period of 4 hours and then heated for 1 hour with agitation to substantially complete the polymerization. Subsequently, a mixture of monomers (mixture B) comprising 5 parts by weight of butylacrylate and 5 parts by weight of methylmethacrylate was added thereto for 1 hour, and the content was maintained at 65 ° C for 1.5 hours and allowed to stand at room temperature throughout the night. The conversion of polymerization was 99.2%. In addition, the average particle diameter in polymerized emulsion latex was 650 A which was determined by the turbidity method. From this product, a powdery sample was obtained according to the method to obtain the product having the multiple layer structure as described above. The viscosity specific of it was 3.1.

Mixing with a methacrylate resin and preparing a molded article. To 100 parts by weight of a mixture comprising 37% by weight of the graft copolymer with a multilayer structure, with 3% by weight of the polymer processing aid and 60% by weight of a methacrylate resin (MG-102: specific viscosity = 0.122 available from ICI), 0.3 parts by weight of a phosphorus-type antioxidant, 1178 (trinonylphenyl phosphite available from Asahi Denka Kogyo K K.) was added. The pelletized mixture was formed by extruding and kneading in a single screw extruder with ventilation (HW-40-28: 40 m / m, L / D = 28, manufactured by Tabata Kikai Co., Ltd.) at a temperature of C3 = 210 ° C. The pellets obtained were dried at 90 ° C for at least 4 hours and samples were obtained from the plate with a measurement of 100 x 150 x 3 (mm) for evaluation, by injection molding at a cylinder temperature of C3 = 230 ° C, at a nozzle temperature of N = 235 ° C, and at a screw speed of 20 mm / sec, 50 mm / sec and 90 mm / sec on a 160MSP-10 molding machine (manufactured by Mitsubishi Plastics Industries Ltd.). The plates obtained were evaluated to show the results of the same in table 1.

EXAMPLE 2 Molded articles were prepared in the same manner as that of example 1 except that Irganox PS800 FL (dilauryl thiodipropionate available from Ciba Geigy) of a sulfur-type antioxidant was used in place of the antioxidant 1178. The results are shown in table 1.

COMPARATIVE EXAMPLE 1 Molded articles were obtained for evaluation in the same manner as in Example 1, except that neither the polymer processing aid nor the reducing compound were used. The results are shown in table 1.

COMPARATIVE EXAMPLE 2 Molded articles were obtained for evaluation in the same manner as in Example 1, except that the reducing compound was not used. The results are shown in table 1.

COMPARATIVE EXAMPLE 3 Molded articles were obtained for evaluation in the same manner as in Example 1, except that the polymer processing aid was not used. The results are shown in table 1.

COMPARATIVE EXAMPLE 4 Molded articles were obtained for evaluation in the same manner as in Example 1, except that the amount of stabilizer 5 (1178 supra) was 0.1 parts by weight. The results are shown in table 1.

COMPARATIVE EXAMPLE 5 Molded articles were obtained for evaluation in the same manner as in Example 1, except that the amount of the stabilizer (1178 above) was 1.5 parts by weight. The results are shown in table 1.

TABLE 1 twenty INDUSTRIAL APPLICATION By mixing the composition to modify a methacrylate resin of the present invention, a molded article with superior strength can be stably prepared without deterioration of the transparency, color tone and appearance thereof under a wide range of molding conditions. by injection.

Claims (6)

NOVELTY OF THE INVENTION CLAIMS

1. A composition for modifying a methacrylate resin comprising an impact modifier, a polymer processing aid and a reducing compound, wherein the amount of the impact modifier to the polymer processing aid is 95/5 to 80/20 by weight, and the amount of the reducing compound is from 0.25 to 1.25 parts by weight with 10 basis to 100 parts by weight of the total amount of the impact modifier and the polymer processing aid.

2. The composition for modifying a methacrylate resin according to claim 1, further characterized in that the impact modifier is prepared by polymerizing a mixture of 15 monomers comprising (meth) acrylate and an aromatic vinyl monomer in the presence of an acrylic rubber and / or a conjugated diene rubber.

3. The composition for modifying a methacrylate resin according to claim 1, further characterized in that the polymer processing aid comprises from 50 to 70% by weight of 20 methylmethacrylate and 30 to 50% by weight of the other copolymerizable monomers.

4. The composition for modifying a methacrylate resin according to claim 1, further characterized in that the ^^ ti & The specific viscosity of the polymer processing aid is from 2.5 to 5.0 relative to 0.4% by weight of a toluene solution at 30 ° C.

5. The composition for modifying a methacrylate resin according to claim 1, further characterized in that the reducing compound is a compound containing sulfur and / or phosphorus.

6. The composition for modifying a methacrylate resin according to claim 5, further characterized in that the reducing compound is a reducing organic compound. i ^ ÉüMíÉiíiauMi? fei