MXPA00009054A - Modifier for methacrylic resin - Google Patents

Abstract

A modifier which comprises a blend of an impact modifier and a polymeric processability modifier in a weight ratio of 95/5 to 80/20 and in which a 0.4 wt.%toluene solution of the polymeric processability modifier has a specific viscosity as measured at 30°C of 2.5 to 5.0. It imparts impact resistance and high transparency to methacrylic resins processed under a wide range of conditions.

Description

MODIFIER FOR METHACRYLIC RESIN TECHNICAL FIELD This invention relates to a modifier for high transparency, which can stably provide high transparency under wide ranges of injection molding processing conditions, particularly when used mixed with methacrylic resins.

BACKGROUND OF THE ART However, it is well known that the transparency of thermoplastic resins which are characterized by their transparency, particularly methacrylic resins, changes within considerable ranges depending on their processing conditions. In addition, in view of insufficient strength, the addition of various modifiers for impact resistance has been attempted for the purpose of improving their strength. For example, techniques relating to the modification of their impact resistance are described in JP-B-55-27576 (the term "JP-B" as used herein means "Japanese Patent Examined Publication") and J PA-62-280841 (the term "JP-A" as used herein means a "Japanese Patent Application published without examination"). In this case, the transparency of methacrylic resins is an essential condition to be maintained, but it is not a sufficient condition from the practical point of view. It is therefore desirable to obtain slurries that can show high transparency and high quality in a stable manner over wide ranges of processing conditions. However, when such resins are processed using the techniques so far described, the requirement just described to obtain moldings that can show high transparency and high quality in a stable manner under wide ranges of processing conditions can not be completely satisfied. That is, the molds having high transparency can be obtained only within the range of narrow processing conditions, and the appearance of the moldings is impoverished in the processing time due to, for example, the addition of impact resistance modifiers. For example, when the molding temperature is increased in order to obtain high transparency, thermal deterioration may occur and burn marks are formed by only slight changes in the processing steps of the resin. On the other hand, when the injection molding temperature is set at a very low level, the transparency is greatly impaired. In other words, not only to simply ensure the qualities of high transparency and high strength, but also to obtain high transparency, high quality of stable moldings within wide molding ranges (processing conditions) required as important factors when carrying the molding by injection of methacrylic resins. Some attempts have been made, although not related to transparency, as the present invention seeks to ensure molds having stable high quality physical properties. For example, JP-B-1 -29218 describes a method in which the balance of strength and fluidity is improved by increasing fluidity using a methacrylic resin having a broad molecular weight distribution, and JP-B-2-2358 describes a technique that uses as a condition that a modifier of impact resistance and a dispersing agent are mixed in a latex form in order to avoid aggregation of the impact resistance modifier, as a means to reduce the so-called fish eye in the moment to mold by extrusion. However, these methods are different from the inventive idea of the present invention to narrow the range of transparency fluctuation in injection molding under wide ranges of processing conditions. In view of the foregoing, it is an object of the present invention to provide a modifier that can modify the impact resistance and provide high transparency products stably under broad conditions of injection molding processing, when used in methacrylic resins of the which transparency is a characteristic.

DESCRIPTION OF THE INVENTION With the objective of developing a modifier that can add an impact modifier effect for methacrylic resins without impairing its transparency and which can also maintain the transparency of the object resin at a high level under wide ranges of conditions of molding, the inventors of the present invention have conducted extensive studies and found that the aforementioned problems can be solved when an impact resistance modifier and a small amount of a polymer processability modifier are used in combination, thereby resulting in the embodiment of the present invention. Accordingly, the present invention relates to (1) a metracrylic resin modifier, comprising a mixture of an impact resistance modifier and a polymer processability modifier having a specific viscosity from 2.5 to 5.0 when measured at a concentration of 0.4% by weight and at a temperature of 30 ° C using toluene as the solvent, wherein the weight ratio of the impact resistance modifier and the polymer processability modifier is from 95/5 to 80/20, (2 ) the methacrylic resin modifier according to (1) above, wherein the impact resistance modifier is obtained by polymerizing monomeric components comprising from 70 to 100% by weight (referred to simply as "%" hereafter) of a (meta) acrylic ester, from 0 to 30% of an aromatic vinyl monomer and from 0 to 30% of another copolymerizable monomer (100% in total), in the presence of an acrylic rubber and / or a rubber of dienes with played, and (3) the methacrylic resin modifier according to (1) or (2) above, wherein the polymer processability modifier is a polymer comprising from 50 to 70% methyl methacrylate, from 1 to 50% of an alkyl ester of (meta) acrylic acid, wherein the number of carbon atoms of the alkyl group is from 2 to 8, and from 0 to 30% of another copolymerizable monomer (100% in total).

BEST MODE FOR CARRYING OUT THE INVENTION The methacrylic resin modifier of the present invention is a modifier comprising a mixture of an impact resistance modifier and a particular polymer processability modifier and that can be used in most resins commercially available methacrylics without particular limitation. The aforementioned methacrylic resin is not particularly limited, but may preferably contain 50% or more, more preferably 70% or more, of a methacrylic ester. Also, like the methacrylic ester, methyl methacrylate is desirable, so that a resin preferably containing 50% or more, more preferably 70% or more, of methyl methacrylate is more desirable. The ratio of said impact resistance modifier and the polymer processability modifier in the aforementioned methacrylic resin modifier, namely (impact resistance modifier) / (polymer processability modifier), is from 95/5 to 80 / 20, preferably from 95/5 to 90/10, as a weight ratio. The ratio of the polymer processability modifier if it is very small will not have sufficient effect to improve the aforementioned problems, and if it is very large it will not produce a greater effect despite the high amount of polymer processability modifier, but rather it will reduce the effect of improvement in impact resistance and will cause a tendency to reduce the transparency of methacrylic resin. It is considered that the reduction in transparency occurs due to the relatively high molecular weight of the polymer processability modifier, which reduces its compatibility with the corresponding methacrylic resin. The aforementioned impact resistance modifier is used to improve the strength and impact strength of the methacrylic resin of base material, and any modifier conventionally used for methacrylic resins can be used without particular limitation. A preferred example of the modifier conventionally used for methacrylic resins is a modifier (I) of impact resistance which is obtained by polymerizing monomeric components (referred to as "monomer (M) s hereafter) comprising from 70 to 100%, preferably from 80 to 100%, of a (meta) acrylic ester, from 0 to 30%, preferably from 0 to 20%, of an aromatic vinyl monomer and from 0 to 30%, preferably from 0 to 15 %, of another copolymerizable monomer (100% by weight in total), in the presence of an acrylic rubber and / or a rubber of conjugated dienes (referred to as "rubber component (R)" hereinafter). The term "an (meth) acrylic ester" means an acrylic ester, a methacrylic ester, or a mixture thereof. The amount of monomer (M) is preferably from 20 to 65 parts by weight (referred to as "part (s)" hereafter), more preferably from 28 to 45 parts, based on 100 parts of the rubber component ( R). If the amount is greater than 65 parts it would cause a tendency to reduce the effect of resistance improvement and if it is smaller than 20 parts it would imply a difficulty to stably produce the modifier practically and it would also cause a tendency to reduce the effect of improvement of resistance. In this regard, when the (meta) acrylic ester in the monomer (M) constituting the impact modifier (I) is less than 70%, it causes a tendency to reduce the effect of resistance improvement due to reduced compatibility . Also, when the amount of the aromatic vinyl monomer exceeds 30%, it causes a tendency to reduce the weathering resistance. The polymerization method of the impact modifier (I) is practically not limited, but a known emulsion polymerization is convenient from a practical point of view. In this regard, the average particle size of the modifier (I) of impact resistance in the latex of the rubber component (R) is preferably from 1000 to 4000 A, more preferably from 1500 to 3000 [deg.], As a measured value by a light scattering method using a light source of 546 nm wavelength. In addition, an acrylic rubber is more desirable than a rubber of conjugated dienes from the point of view of weathering resistance. Examples of the aforementioned acrylic rubber include the compound produced in Example 1 which will be described later. They can be used alone or as a mixture of 2 or more. Examples of the aforementioned conjugated diene rubber include those having a refractive index adjusted by the copolymerization of a diene monomer with styrene. They can be used alone or as a mixture of two or more. Examples of the aforementioned (meta) acrylic ester as a component of the monomer (M) include methyl methacrylate, ethyl methacrylate, butyl methacrylate, methyl acrylate, ethyl acrylate, n-butyl acrylate and n-octyl acrylate. These compounds can be used alone or as a mixture of two or more. Examples of the aforementioned aromatic vinyl monomer as a component of the monomer (M) include styrene and α-methylstyrene. These compounds can be used alone or as a mixture of two or more. Examples of the other copolymerizable monomer mentioned above include acrylonitrile. Such compounds can be used alone or as a mixture of two or more. As the impact resistance modifier (I), several substances of multi-layer structure are known, such as the multilayer structure described in JP-B-55-27576 and the modifier described in the examples to be described later. The aforementioned polymer processability modifier is used to further expand the range of molding process conditions under which excellent transparency can be obtained. It is necessary that the polymer processability modifier have a relatively large molecular weight, and a polymer having a molecular weight from several times to several tens of times (preferably 10 times to 50 times) larger than that of the methacrylic resin corresponding (about 1,000,000 in average molecular weight) is generally effective. If the molecular weight is similar to or less than that of the corresponding methacrylic resin, it would not provide the modifying effects of this invention. As well, if the molecular weight is very large it would cause a great reduction of the transparency due to the reduced compatibility with the matrix. Thus, the molecular weight is that which shows a specific viscosity (? Sp) from 2.5 to 5.0, preferably from 2.5 to 4.0. In this case, the value of? Sp is calculated by the formula? 8p = (? -? O) ?? or using a viscosity? obtained by dissolving the aforementioned polymer processability modifier in toluene at a concentration of 0.4% and measuring the solution at a temperature of 30 ° C. The value of? 0 is the viscosity of the solvent (toluene). When the polymer processability modifier having the aforesaid viscosity is added in a small amount, the viscosity of the system that melts at the time of molding slightly increases, but exerts an effect to reduce the dependence on transparency under conditions of prosecution. Although its technical reason is not clear, transparency is considered to be stabilized by increasing the fusion elasticity of the system. The aforementioned polymer processability modifier is preferably a polymer comprising from 50 to 70%, preferably from 60 to 70%, of methyl methacrylate from the point of view of compatibility with the matrix, from 1 to 50%, preferably from 30 to 40%, of an alkyl ester of (meta) acrylic acid, wherein the number of carbon atoms of the alkyl group is from 2 to 8, which is preferably used as a soft component for the purpose of not harming the weathering resistance of the methacrylic resin, and of 0 to 30% of other copolymerizable monomers (100% in total). When the amount of methyl methacrylate is very high, its compatibility with the matrix is reduced and the transparency of the methacrylic resin tends to decrease, due to the increased stiffness of the molecule in addition to its relatively large molecular weight. That is, it is desirable to copolymerize a mild component in addition to methyl methacrylate from a practical point of view. However when the ratio of methyl methacrylate is very small, it causes a tendency to reduce the effect to further expand the range of molding process conditions under which excellent transparency can be obtained. Also, when the amount of the alkyl ester of (meta) acrylic acid, wherein the number of carbon atoms of the alkyl group is from 2 to 8, exceeds 50% or is less than 1%, it causes a tendency to reduce the effect to further expand the range of molding process conditions under which excellent transparency can be obtained. Examples of the alkyl ester of (meth) acrylic acid, wherein the number of carbon atoms of the alkyl group is from 2 to 8, include butyl methacrylate, ethyl acrylate, butyl acrylate, octyl acrylate and 2-ethylhexyl acrylate, which are practical from the point of view of cost, for example. These compounds can be used alone or as a mixture of two or more. Among these compounds, butyl methacrylate and butyl acrylate are particularly preferable. Examples of the other copolymerizable monomer mentioned above include styrene, α-methylstyrene and acrylonitrile. These compounds can be used alone or as a mixture of two or more. The aforementioned polymer processability modifier can be produced by various polymerization methods known in the prior art, but an emulsion polymerization method is practical, because it is desirable to have a relatively high molecular weight. In fact, of course, the spare index of this modifier can be adjusted so that it is in the methacrylic resin to be used as narrow as possible so that the transparency of the obtained moldings is not impaired. The above-mentioned polymer processability modifier can be used, commercially available products which can satisfy the various conditions mentioned above (e.g., the polymer processability modifiers of the KAN E ACE PA series produced by Kaneka Corporation). In this regard, the method for mixing the aforementioned impact resistance modifier and the polymer processability modifier is not particularly limited, and can be effected by mixing powders of both modifiers and then mixing the mixture with the methacrylic resin to be used or by mixing the impact resistance modifier and the polymer processability modifier, both obtained by polymerization, in the latex form, making the powder mixture in the usual manner and then mixing the powder with a methacrylic resin. With respect to the ratio of a methacrylic resin and the methacrylic resin modifier of the present invention, it is desirable that the ratio of the methacrylic resin and the polymer processability modifier, namely methacrylic resin / polymer processability modifier, be from 90/10 to 40/60, preferably from 85/15 to 50/50, as weight ratio.

EXAMPLES The examples of the present invention will be later by way of illustration and not by way of limitation. Unless otherwise indicated, all parts, relationships, percentages, etc. They are in weight.

EXAMPLE 1 (Production of impact resistance modifier) (a) Production of entangled methacrylic polymer (innermost layer) A mixture of the following composition was placed in a glass reactor and heated to 80 ° C while stirring in a nitrogen stream, and then 25% of a solution of the components of the innermost layer of 25 parts of methyl methacrylate and 0. 1 parts of allyl methacrylate were added in one go to carry out 45 minutes of polymerization.

(Composition) (Parts) Deionised water 220 Boric acid 0.3 Sodium carbonate 0.03 Sodium sodium lauroyl sarcarbonate 0.09 Sodium formaldehyde sulfoxylate 0.09 Sodium ethylene diamine tetraacetate 0.006 Ferrous sulphate heptahydrate 0.002 Next, the remaining 75% of the mixed solution was added continuously taking 1 hour. After finishing the addition, the mixture was maintained at the same temperature for 2 hours to complete the polymerization. During this period, 0.2 parts of sodium N-Lauroyl sarcocinate were added. The average particle size of the polymer particles in the interlaced meta-acrylic polymer latex of the innermost layer thus obtained was 1600 A (calculated using light scattering of 546 nm wavelength), and the polymerization conversion ratio ((amount of polymer formed / amount of charged monomer) x 100 (%)) was 98%. (b) Production of acrylic rubber While maintaining the interlaced methacrylic polymer latex obtained in step (a) above at 80 ° C in a stream of nitrogen, 0.1 part of potassium persulfate was added and then a solution of mixed monomers of 41 parts of n-butyl acrylate, 9 parts of styrene and 1 part of allyl methacrylate taking 5 hours. During this period, 0.1 part of potassium oleate was added in three portions. After finishing the addition of the mixed monomer solution, 0.05 parts of potassium persulfate was added, and the mixture was maintained for hours to complete the polymerization. The average particle size of the acrylic rubber particles in the polymer latex thus obtained was 2300 A (calculated by the light scattering method), and the polymerization conversion ratio was 90%. (c) Polymerization of the outermost layer (production of impact resistance modifier) While maintaining the rubber-like polymer latex obtained in step (b) above at 80 ° C, 0.02 parts of potassium persulfate was added. Then, a mixed solution of 24 parts of methylmethacrylate, 1 part of n-butyl acrylate and 0.1 part of t-dodecyl mercaptan was added continuously taking one hour. After finishing the addition of the mixed monomer solution, the resulting mixture was maintained for one hour to obtain a multilayer structure graft copolymerization latex. The average particle size of the acrylic rubber particles in the multi-layer structure grafted copolymer latex was 2530 A (calculated by the light scattering method), and the polymerization conversion ratio was 99%. By holding the grafted copolymerization latex of multilayer structure thus obtained to salt aggregation, heat treatment and drying in the usual way, a graft copolymer of multiple layer structure, namely a resistance modifier, was obtained as a white powder. to the impact (Production of polymer processability modifier) A reactor equipped with an agitator was charged with 200 parts of water, 1 part of sodium dioctylsulfosuccinate and 0.03 parts of potassium persulfate, oxygen in space and in the water was removed by blowing nitrogen and then the contents were heated to 65 ° C while stirring. Then a mixture of monomers (mixture A) of 60 parts of methyl methacrylate was added, 15 parts of butyl methacrylate and 15 parts of butyl acrylate taking four hours, and then stirring was continued for one hour at 65 ° C to substantially complete the polymerization. Then, a mixture of monomers (mixture B) of 5 parts of butyl acrylate and 5 parts of methylmethacrylate was added taking one hour, and the contents were kept at 65 ° C for 1.5 hours and then cooled spontaneously to obtain a polymerization latex in emulsion. The polymerization conversion ratio was 99.2%. Also, the average particle size of the polymer particles of the emulsion polymerization latex was 650? when it was calculated by a turbidity method. By subjecting the emulsion polymerization latex thus obtained to salt aggregation, heat treatment and drying in the usual way, a powder sample was obtained. The specific viscosity of the sample thus obtained was 3.1.

(Mixed with methacrylic resin and production of moldings) A 0.1% portion of a phosphorus-based stabilizer (TN PP: trisnonylphenyl phosphites) was added to a mixture of 37% of the multilayer graft copolymer, 3% of the polymer processability modifier, both obtained in the steps mentioned above, and 60% of a methacrylic resin (methacrylic resin MG-102 manufactured by ICI, specific viscosity 0.122), 100% in total, and the resulting mixture was converted to pellet carrying out extrusion kneading at a cylinder temperature at C3: 210 ° C using a single screw extruder of the vent type (HW-40-28 manufactured by Tabata Kikai, 0 40 mm, L / D = 28). The pellet thus obtained was dried at 90 ° C for four hours or more and then subjected to injection molding using a type 16-OMSP-10 manufacturing machine manufactured by Mitsubishi Heavy Industries under cylinder temperature conditions in zone C3: 230 ° C, nozzle temperature (N): 235 ° C and injector screw speed: 20 mm / second, 50 mm / second or 90 mm / second, obtaining with this a molded plate sample of 100 mm x 150 mm x 3 mm used for evaluation of physical properties. Also, another sample was molded for evaluation under C3 cylinder temperature conditions: 250 ° C, nozzle temperature (N): 225 ° C and injector screw speed: 90 mm / second, in order to examine the transparency change It depends on the molding temperature. Using the samples thus obtained, the opacity was measured at a constant temperature of 23 ° C according to the procedure of J I S K 6714. The results are shown in Table 1.

Example 2 A polymer processability modifier was obtained in the same way as described in Example 1, except that that composition of mixture A in the step of "polymer processability modifier production" of Example 1 was changed to 60 parts of methyl methacrylate, 24 parts of butyl acrylate and 6 parts of styrene. Then, moldings were obtained for evaluation in the same way as described in Example 1 and the same measurement was carried out to be used as Example 2. The results are shown in Table 1.

Comparative Examples 1 to 3 Molds were obtained for evaluation in the same manner as described in Example 1, except that the amount of polymer processability modifier was charged for 0.1 or 1% and the amount of MG-102 was charged for 63, 62 or 52% in the step of "mixed with methacrylic resin and molding production" of Example 1, and the same measurement was carried out to be used as Comparative Examples 1, 2 and 3, respectively. The results are shown in Table 1 .

Comparative Example 4 A polymer processability modifier was obtained in the same manner as described in Example 1, except that the amount of potassium persulfate in the "polymer processability modifier production" step of Example 1 was changed to 0.08 parts. The specific viscosity of the product was 1.5. Then, moldings were obtained for evaluation in the same manner as described in Example 1 and the same measurement was carried out to be used as Comparative Example 4. The results are shown in Table 1.

Comparative Example 5 In the step of "polymer processability modifier production" of Example 1, 0.005 part of potassium persulfate was used and taking 2 hours the polymerization was carried out by loading the total volume of mixture A at one time, and mixture B was continuously charged in the same manner as described in Example 1, thereby obtaining a polymer processability modifier. The specific viscosity of the product was 5.8. Then, moldings were obtained for evaluation in the same manner as described in Example 1 and the same measurement was carried out to be used as Comparative Example 5. The results are shown in Table 1.

Table 1 Thus, as is evident from the results shown in Table 1, when the modifier of the present invention is mixed with methacrylic resin, moldings having high transparency can be obtained with less influence by the molding conditions.

Claims (5)

1. REVINDICATIONS 1. A methacrylic resin modifier, comprising a mixture of an impact resistance modifier and a polymer processability modifier having a specific viscosity from 2.5 to 5.0 when measured at a concentration of 0.4% by weight and at a temperature of 30 ° C using toluene as the solvent, wherein the weight ratio of the impact resistance modifier and polymer processability modifier is from 95/5 to 80/20. The methacrylic resin modifier according to claim 1, wherein the impact resistance modifier is obtained by polymerizing monomeric components comprising from 70 to 100% by weight of a (meta) acrylic ester, from 0 to 30% in weight of an aromatic vinyl monomer and from 0 to 30% by weight of other copolymerizable monomers (100% by weight in total), in the presence of an acrylic rubber, a rubber of conjugated dienes or a mixture thereof. The methacrylic resin modifier according to claim 1 or 2, wherein the polymer processability modifier is a polymer comprising from 50 to 70% by weight of methyl methacrylate, from 1 to 50% by weight of an ester of alkyl of the (meta) acrylic acid, wherein the number of carbon atoms of the alkyl group is from 2 to 8, and from 0 to 30% by weight of another copolymerizable monomer (100% by weight in total). The methacrylic resin modifier according to claim 1, wherein the weight ratio of the impact resistance modifier and the polymer processability modifier is from 95/5 to 90/10. The methacrylic resin modifier according to claim 2, wherein the impact resistance modifier is obtained from 20 to 65 parts by weight of the monomer components comprising a (meta) acrylic ester, a vinyl monomer aromatic and another copolymerizable monomer and 100 parts by weight of rubber components comprising an acrylic rubber, a rubber of conjugated dienes or a mixture thereof. The methacrylic resin modifier according to claim 2, wherein the average particle size of the impact resistance modifier in the latex of the rubber component is from 1,000 to 4,000 Á as a value measured by a method of light scattering using a light source of 546 nm wavelength. The methacrylic resin modifier according to claim 2, wherein said (meta) acrylic ester is at least one compound selected from the group consisting of methyl methacrylate, ethyl methacrylate, butyl methacrylate, methyl acrylate, methyl acrylate, n-butyl acrylate, and octyl acrylate. The methacrylic resin modifier according to claim 2, wherein said aromatic vinyl monomer is at least one compound selected from the group consisting of styrene and α-methylstyrene. 9. The methacrylic resin modifier according to claim 2, wherein said other copolymerizable monomer is acrylonitrile. The methacrylic resin modifier according to claim 2, wherein the specific viscosity of the polymer processability modifier when measured at a concentration of 0.4% by weight and at a temperature of 30 ° C using toluene as the solvent is from 2.5 to 4.0. The methacrylic resin modifier according to claim 3, wherein said alkyl ester of (meth) acrylic acid is at least one compound selected from the group consisting of butyl methacrylate, ethyl acrylate, butyl acrylate. , octyl acrylate, and 2-ethylhexyl acrylate. The methacrylic resin modifier according to claim 3, wherein said other copolymerizable monomer is at least one compound selected from the group consisting of styrene, α-methylstyrene and acrylonitrile.