JPH0352910A - Acrylic polymer with multilayered structure - Google Patents

Abstract

PURPOSE:To provide the title polymer having a specified granular size and capable of giving acrylic resin compositions excellent in transparency, impact resistance, temperature dependency for haze, etc., made up of each specific innermost rigid layer polymer, flexible layer polymer and outermost rigid layer polymer. CONSTITUTION:The objective polymer made up of (A) an innermost rigid layer polymer prepared by polymerization of a mixture of (1) 80-99 pts.wt. of methyl methacrylate. (2) 1-20 pts.wt. of a 1-8C alkyl acrylate and (3) a polyfunctional crosslinking agent and/or (4) a polyfunctional grafting agent, (B) a flexible layer polymer prepared by polymerization of a mixture of (5) 75-90 pts.wt. of a 4-8C alkyl acrylate, (6) 25-10 pts.wt. of an aromatic vinyl compound and 0-5 pts.wt. of the component (8) and/or 0.05-5 pts.wt. of the component (4) in the presence of the polymer A, and (C) an outermost rigid polymer prepared by polymerization of a mixture of 80-99 pts.wt. of the component (1) and 1-20 pts.wt. of the component (2) in the presence of the components A and B. The present polymer is 0.2-0.4mum in average granular size and 0.05-0.6 in the crosslinking index of the polymer A.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a multilayer structure acrylic polymer, and more specifically, it is blended with a thermoplastic acrylic resin to improve transparency, impact resistance and This article relates to a multi-structure acrylic polymer used to obtain a thermoplastic acrylic resin composition with excellent haze temperature dependence. [Prior Art] Generally, as a means of improving the impact resistance of thermoplastic resins,
A method of introducing a so-called elasmer component is being used. One such method is generally to introduce diene elastomers, but diene elastomers have very poor weather resistance and are therefore not suitable for outdoor applications.

The introduction of acrylic elastomers has been variously investigated in order to impart impact resistance without reducing weather resistance. In particular, many examples using acrylic polymers with multilayer structures have been proposed as acrylic elastomers. For example, by blending a 3N or 4N or higher multilayer structure polymer with a thermoplastic polymer, the impact resistance is improved without impairing transparency.
, which is based on a 3N structure and has an intermediate layer between each of these layers with a concentration gradient that changes at an almost constant rate (Japanese Patent Publication No. 58-1694, Japanese Patent Publication No. 59-36645), 3
Those based on the N structure and having an intermediate layer of one or more thickness between the central soft layer and the outermost layer (Special Publication No. 59-36646, Special Publication No. 63-8983), 4N structure of one soft, one hard, one soft and one hard. (Japanese Patent Publication No. 62-41241) has been proposed. [Problems to be Solved by the Invention] In this way, it is possible to improve other disadvantages while retaining the favorable properties of acrylic resins. For this purpose, many proposals have been made regarding acrylic polymers with a multilayer structure.However, although these methods are certainly effective in improving stress whitening resistance, they have problems with transparency and impact resistance. However, the temperature dependence of acrylic resin and haze have not yet been sufficiently improved. The object of the present invention is to provide an acrylic resin composition that not only has excellent transparency and flow processability, but also has excellent impact resistance and reduced temperature dependence of haze. [Means for solving the problems] This invention The inventors have discovered that the transparency of impact-resistant acrylic resin compositions,
As a result of intensive studies to improve impact resistance, it was discovered that the above object could be achieved by using a specific multi-structure acrylic polymer, and the present invention was completed. That is, the present invention provides: (a) 80 to 99 parts by weight of methyl methacrylate, 1 to 20 parts of alkyl acrylate whose alkyl group has 1 to 8 carbon atoms;
parts by weight, an innermost hard layer polymer obtained by polymerizing a monomer mixture consisting of a polyfunctional crosslinking agent and/or a polyfunctional grafting agent, (b) an alkyl group in the presence of the innermost hard N1 polymer; Alkyl acrylate having 4 to 8 carbon atoms 75 to
A soft material obtained by polymerizing a monomer mixture consisting of 90 parts by weight, 25 to 10 parts by weight of an aromatic vinyl compound, 0 to 5 parts by weight of a polyfunctional crosslinking agent, and 0.05 to 5 parts by weight of a polyfunctional grafting agent. methyl methacrylate 8 in the presence of a layer polymer, (c) a polymer consisting of the innermost hard layer and soft layer;
(d) average particle The diameter is 0.2 to 0.4 μm, and (e
) A multilayer structure acrylic polymer in which the innermost hard layer polymer has a crosslinking index of 0.05 to 0.6. The poly/t'll-formed acrylic polymer in the present invention is methyl methacrylate, an alkyl acrylate whose alkyl group has 1 to 8 carbon atoms, an aromatic vinyl monomer, a polyfunctional crosslinking agent and/or a polyfunctional grafting agent. It is a multilayer structure acrylic polymer consisting of. The multilayer structure acrylic polymer in the present invention is produced by sequential multistage polymerization, but it is preferable to use emulsion polymerization as the polymerization method. However, there is no particular limitation to this, and after emulsion polymerization, the emulsion M. It can also be produced by the turbidity polymerization method. Here, examples of the alkyl acrylate whose alkyl group has 1 to 8 carbon atoms include methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, etc., but n-butyl acrylate is preferably used. ．． As aromatic vinyl compounds,
Examples include styrene and substituted styrene derivatives, with styrene being preferred. As the polyfunctional crosslinking agent, commonly known crosslinking agents such as divinyl compounds, diallyl compounds, diacrylic compounds, and dimethacrylic compounds can be used.
) is preferably used. In addition, as the polyfunctional grafting agent, polyfunctional monomers having different functional groups, such as
Examples include allyl esters of acrylic acid, methacrylic acid, maleic acid, and fumaric acid, with allyl methacrylate being preferably used. The average particle diameter of the acrylic polymer of the present invention is 0.
2 to 0.4 pm, and 0. 25-0. 35 μm
is preferable. When the average particle diameter is less than 0.2 μm,
It has poor impact resistance, and if it exceeds 0.4 μm, only poor transparency can be obtained. In the multilayer structure acrylic polymer of the present invention, the innermost hard layer polymer has a crosslinking index of 0.05 to 0.6, preferably 0.1 to 0.4. If the crosslinking index is 0.05 or more, or if it exceeds 0.6, the impact resistance is poor. As described above, the properties of the innermost hard layer have a large effect on the impact resistance of thermoplastic acrylic resin repair products.
This is something that cannot be predicted using conventional technology. The crosslinking index is 80 to 99 parts by weight of methyl methacrylate,
Alkyl acrylate 1 whose alkyl group has 1 to 8 carbon atoms
When polymerizing a monomer mixture consisting of ~20 parts by weight to form the innermost hard layer polymer, the f! It can be controlled by choosing the type and amount. That is, increasing the amount of polyfunctional crosslinking agent and/or polyfunctional grafting agent increases the crosslinking index. Furthermore, the crosslinking index changes even if the type of polyfunctional crosslinking agent and/or polyfunctional grafting agent is changed. Here, as the polyfunctional crosslinking agent and polyfunctional grafting agent, those listed above are used. As mentioned above, it is advantageous to use the emulsion polymerization method to produce the multilayer structure acrylic polymer of the present invention, but the appropriate polymerization temperature for forming the polymer or copolymer of each layer is , 30 to 120°C for each layer, preferably 50 to 1
00-''C.Furthermore, in order to form such a multilayer structure polymer, the polymer can be formed by sequentially adding and reacting each monomer or monomer mixture. It is advantageous to use the so-called seed polymerization method, which allows the polymerization to be carried out.In this case, it is necessary to select conditions that will prevent the generation of new particles when polymerizing from the 271st!!fl onwards. This can be achieved by adjusting the amount of emulsifier used to below the critical micelle concentration.
In addition, the presence or absence of new particle generation can be confirmed by observation using a Shizukuko V and mirror. There are no particular restrictions on the emulsifier used in emulsion polymerization, and any emulsifier can be selected from conventionally used emulsifiers. Examples include long silver alkyl carboxylates, sulfosuccinic acid alkyl ester salts, and alkylbenzene sulfonates. In addition, there are no particular restrictions on the polymerization initiator used at this time, and commonly used water-soluble inorganic initiators such as persulfates and perborates may be used alone, or sulfites and thiosulfates may be used. It can also be used in combination with other substances as a redox initiator system. Furthermore, oil-soluble organic peroxide/ferrous salt,
Redox initiator systems such as organic peroxide/sodium sulfoxylate can also be used. The multilayered acrylic polymer obtained by such a polymerization method is obtained as a particulate solid by subjecting the polymer latex state to salting out, washing, drying, etc. by known methods. A thermoplastic acrylic resin N composition can be produced by blending the multilayered acrylic polymer of the present invention with a thermoplastic acrylic resin.The thermoplastic acrylic resin used here can be prepared by a known polymerization method. For example, bulk polymerization,
It may be obtained by any method such as solution polymerization, suspension polymerization, or emulsion polymerization. The ratio of the multilayer acrylic polymer in the composition is 2
-80 m parts is preferable; if it is less than 2 parts by weight, the impact resistance will be insufficient, and if it exceeds 80 parts by weight, only poor color tone will be obtained. When kneading to produce an acrylic resin composition, stabilizers, lubricants, dyes, pigments, etc. can be added as necessary. By injection molding or extrusion molding the acrylic resin composition thus obtained, a molded article with excellent transparency and impact resistance and reduced temperature dependence of haze can be obtained. Furthermore, the multilayer structure acrylic polymer of the present invention may include alkyl methacrylates other than methyl methacrylate, styrene, styrene derivatives, acrylonitrile, methacrylic nitrile, vinyl chloride, . It can be used alone or as a copolymer of vinylidene chloride, or in a blend with polycarbonate, polyamide, polyester, etc. [Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited in any way by this. The measurements in Examples and Comparative Examples were performed using the following methods or measuring equipment. Izod impact strength; ASTM
D256 Haze: Using an integrating sphere haze meter, the haze of a 3 mm thick test piece was measured at 23°C and 70°C. The fruits are indicated by the following symbols. O Haze Less than 5% Q // 5% or more, 10% ungrooved Δ
〃 0% or more, 20% ungrooved × 〃 20% or more average particle diameter; sample the latex of the multi-eye structure acrylic polymer, dilute it with water to a solid content of 50 ppm, and measure it with a spectrophotometer. The absorbance at a wavelength of 550 nm was measured using a. From this value, the average particle diameter was determined using a detection line created by similarly measuring the absorbance of a sample whose latex particle diameter was measured from a transmission electron micrograph. Crosslinking index: When the polymerization of the innermost hard layer was completed, latex was sampled, salted out, washed, and dried to obtain a powdery innermost hard layer polymerized red. Add 30 parts of methyl ethyl ketone to about 2 g of this polymer, and after crushing at 25°C for 12 hours,
The mixture was shaken for 1 hour and centrifuged at 5°C and 2300 rpm for 1 hour. After removing the supernatant liquid by decantation, 30 d of methyl ethyl ketone was added and shaken at 25°C for 1 hour. Centrifugation was performed at 5°C and 2300 rpm for 1 hour. The supernatant liquid was removed and the weight was measured (W.). Thereafter, it was vacuum dried at 100°C for 6 hours, and the weight of the residue was weighed (W2).The crosslinking index was calculated using the following formula. In addition, the abbreviations used in Examples and Comparative Examples indicate the following compounds. MMA; methyl methacrylate BA; n-butyl acrylate St; styrene MA; methyl acrylate ALMA; allyl methacrylate PEGDA; polyethylene glycol diacrylate (
Molecular weight 200 or 600) n-OM; n-octylmerbutane HMB T; 2-(2'-hydroxy-59-methylphenyl)penzotriazole Example 1 Content fJI Cl was placed in a reactor with a reflux condenser and subjected to ion exchange. 6860 ml of water and 13.7 g of sodium dihexyl sulfosuccinate were added, and the temperature was raised to 75° C. under a nitrogen atmosphere while stirring at a rotational speed of 25 Orpm, so that there was virtually no influence of oxygen. Ammonium persulfate 0. 2
After adding 2 g, 746 g of MMA, BA 10
g, 30% of the mixture (n-1) consisting of 0.23 g of HMB T and 0.38 g of ALMA was added all at once,
Immediately after that, the remaining 70% was added continuously over a period of 20 minutes, and after the addition was completed, the mixture was held for an additional 60 minutes. The Latinx of the innermost hard N polymer thus obtained was 40
0g was collected, salted out, washed, and dried, and the crosslinking index of the polymer was measured and found to be 0.2. Next, after adding 0.96 g of ammonium per5R acid, BA990 g,
St 2 3 2 g, HMB T0.37g, A
A mixture (IF-2) consisting of 25.9 g of LMA was
Continuously add over 0 minutes, and then add 180 minutes after the addition is complete.
Hold for minutes.

Next, after adding 0.29 g of persulfurized ammonium, MM
A7 1 1 g - A mixture (II-3) consisting of 9 g of BA, 0.22 g of HMBT and 1.44 g of n-OM was added continuously over 40 minutes, and after the addition was completed, an additional 60 g of
It was held for a minute. Next, the temperature was raised to 95°C and held for 60 minutes. ．． A small amount of the latex thus obtained was sampled, and the average particle diameter was determined by absorbance method and was found to be 0.25 μm.

The remaining latex was poured into a 3% by weight hot aqueous sodium sulfate solution for salting out and coagulation, followed by repeated dehydration and washing, followed by drying to form a multilayered acrylic polymer (n).
I got it. 30 parts by weight of this multilayer structure acrylic polymer (II) and MMA/MA copolymer (I) [MMA/MA=97.5
/2.5 weight ratio, η,i,/C=0.54d/g (0.
30g/a chloroform solution, 25°C)]70i
After mixing for 20 minutes with a Henschel mixer, the
The pellets were pelletized at 240°C using a mold. The obtained pellets are processed using an in-line screw injection molding machine (Toshiba Machine ■).
Predetermined test pieces were prepared using a molding degree of 250° C., an injection pressure of 900 kgf/cm”, and a mold temperature of 50° C., and their physical properties were measured.

The resulting resin composition had excellent transparency and temperature dependence of haze, and also had good impact resistance. The results are shown in Table 1. Example 2 Example 1 except that the amount of ALMA in the mixture constituting (If-1) was 0.76 g. is Example 1
The experiment was carried out in exactly the same manner as in 1. The results are shown in Table 1. Example 3 Same as Example 1 except that the amount of ALMA in the mixture constituting (II-1) was 1.89 g.
It was carried out in exactly the same way. The results are shown in Table 1. Example 4 Example 1 was carried out in exactly the same manner as in Example 1, except that the mixture constituting (II-1) was changed to 1243 g of MMA, 17 g of BA, 0.38 g of HMBT, and 1.25 g of ALMA. The results are shown in Table 1. Example 5 In Example 1, 5830d ion-exchanged water, 11.7g of sodium dihexyl sulfosuccinate, (
The mixture constituting n-1) was mixed with 2244 g of MMA and BA2
2g of HMBT, 0.52g of HMBT, and 86g of ALMAO, and the continuous addition time of 80% was 40 minutes (II-
2) The mixture constituting BA841g, St197
g, HMB T0.3! g and ALMA22.0g
and the mixture constituting (II-3) was mixed with 604 g of MMA.
BA8g, HMBT (L19g and n-O M 1.
It was carried out in exactly the same manner as in Example 1 except that the weight was 84 g.

The results are shown in Table 1. Comparative Example 1 Example 1 was carried out in exactly the same manner as Example 1 except that ALMA was not used in the mixture constituting (II-1). The results are shown in Table-1.

Comparative Example 2 Comparative example 2 was carried out in exactly the same manner as in Example 1 except that the amount of ALMA in the mixture constituting (If-1) was changed to 15.1 g. The results are shown in Table I. Comparative Example 3 In Example 1, part of (II-1) was not added all at once, but was added continuously over 60 minutes, and the mixture constituting (If-2) was added to 990 g of BA, 232 g of St, and HMBT.
0.37g%ALMA13.0g and PEODA1.5
The experiment was carried out in exactly the same manner as in Example 1, except that the amount was changed to 9g. The results are shown in Table 1. As described above, if the scope of the present invention is exceeded, a composition with excellent impact resistance, transparency, and temperature dependence of haze cannot be obtained. [Effects of the Invention] According to the present invention, the drawbacks of conventional multilayer acrylic polymers are improved, and in addition to having the excellent transparency and moldability inherent to acrylic resins, they also have excellent impact resistance and haze. An acrylic resin composition with excellent temperature dependence can be provided. Procedural amendment (voluntary) January 23, 1990

Claims (1)

Scope of Claims: (a) 80 to 99 parts by weight of methyl methacrylate, 1 to 20 parts of alkyl acrylate whose alkyl group has 1 to 8 carbon atoms;
parts by weight, an innermost hard layer polymer obtained by polymerizing a monomer mixture consisting of a polyfunctional crosslinking agent and/or a polyfunctional grafting agent; (b) in the presence of the innermost hard layer polymer, an alkyl 75 to 90 parts by weight of an alkyl acrylate whose group has 4 to 8 carbon atoms, 25 to 10 parts by weight of an aromatic vinyl compound, 0 to 5 parts by weight of a polyfunctional crosslinking agent, and 0.05 to 5 parts by weight of a polyfunctional grafting agent.
(c) 80 to 99 parts by weight of methyl methacrylate, a soft layer polymer obtained by polymerizing a monomer mixture consisting of parts by weight, and (c) a polymer consisting of the innermost hard layer and soft layer. The outermost hard layer consists of a polymer obtained by polymerizing a monomer mixture consisting of 1 to 20 parts by weight of alkyl acrylate having 1 to 8 carbon atoms, and (d) has an average particle diameter of 0.2 to 0.4 μm. and (e
) A multilayer structure acrylic polymer in which the innermost hard layer polymer has a crosslinking index of 0.05 to 0.6.