KR910009866B1 - A method of preparing for the excellent impact retardant graft polymer - Google Patents

Abstract

The graft copolymer having excellent impact resistance is prepd. by graft-copolymerization of 20-60 wt. pts. of the rubber latex of 70-85% gel contents, 30-50 swelling index and 0.3-0.5 micron of ave. diameter; 30-60 wt. pts. of monovinylidene aromatic compound; 8- 25 wt. pts. of cyanoalkene based cpd.; the emulsifier; the chain transfering agent; and the initiator. Pref. in the process, the mixt. of the monomers, initiator and the chain transfering agent is continuously introduced.

Description

Method for preparing graft polymer having excellent impact resistance

The present invention relates to a method for producing a graft polymer having excellent impact resistance that can be used alone or in a mixture with a thermoplastic resin. Improved impact resistance by introducing a diene rubber component, such as polybutadiene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, or the like into thermoplastic resins such as polystyrene, styrene-acrylonitrile copolymer, and polymethyl methacrylate. It is already well known to make. It is also well known that the particle diameter of these rubber components has a great influence on the impact resistance and processability of the final composition, and it is already known that the larger the diameter of the rubber component is, the better the impact resistance is.

To prepare large-diameter rubber particles by general emulsion polymerization method, considerably longer polymerization time of 50 to 60 hours is required. Therefore, in order to solve this problem, a method of preparing small diameter rubber particles within a short time and agglomerating them has been used.Agglomeration methods include an acid method, a shear force method, a salt method, and a polymer. And a method using a flocculant, a freezing method and a solvent addition method. Some of these flocculation methods are not reproducible, and some of them cannot control rubber particle distribution well. If a large number of small-diameter rubber particles that are not aggregated remain, the impact resistance and workability of the final composition are lowered. In the present invention, a large diameter rubber latex, which is controlled to minimize a small diameter rubber latex that is not aggregated, is prepared using a well-known acid and shearing flocculation method (UK Patent No. 976,214), and used for graft polymerization. .

The gel content and swelling index of the rubber particles affect the impact resistance and flowability of the graft polymer, and it is advantageous to use rubber particles having a high swelling index in order to obtain a high graft rate of the graft polymer. The graft polymer having a high graft ratio is excellent in impact resistance and thermal stability, but when the graft ratio is too high, such physical properties may be degraded due to aggregation of rubber components in the matrix.

An object of the present invention is to provide a rubber latex having a relatively low gel content and a high swelling index to produce a large diameter rubber latex through agglomeration by acid and shear force, thereby using a new graft polymerization method which increases the graft rate within a short time. It is to provide a method for producing a thermoplastic resin.

If the present invention will be described in more detail

When a small-diameter rubber latex of 0.07 to 0.15 mu is prepared with a reaction conversion of 85% or more by a conventional emulsion polymerization method, the gel content of the rubber latex is 90 to 95%, and the swelling index is about 14 to 10. However, in the present invention, a small-diameter rubber latex having a gel content of 70 to 85% and a swelling index of 30 to 50 was used to obtain a graft copolymer having excellent impact resistance.

To 100 parts by weight of 1,3-butadiene, 3.3 parts by weight of potassium oleate as an emulsifier, 0.3 parts of potassium persulfate as an initiator, 0.2 parts of n-dodecyl mercaptan as a chain transfer agent, and 150 parts of water were added to a reactor, and the reaction internal temperature was increased to 55 ° C. The reaction was carried out. When the conversion rate reaches 30%, 0.1 part by weight of tertiary dodecyl mercaptan is added, and the reaction temperature is raised to 60 ° C. After the conversion reached 85%, the reaction was stopped by administration of diethylhydroxyamine, and the unreacted monomer was recovered to obtain a small diameter rubber latex having an average particle diameter of 0.085μ, a gel content of 83%, and a swelling index of 35. A-1 was obtained. The initial reaction temperature was the same, and 0.1 parts by weight of tertiary dodecyl mercaptan was added at a conversion rate of 30%, and the reaction temperature was raised to 60 ° C. Then, 0.1 parts by weight of tertiary dodecyl mercaptan was added again at a conversion rate of 60%. The reaction temperature was raised to 65 ° C. to stop the reaction at a conversion rate of 85% to obtain a small diameter rubber latex A-2. In addition, the initial reaction temperature was the same, 0.1 parts by weight of tertiary dodecyl mercaptan was administered at a conversion rate of 40%, and the reaction temperature was raised to 60 ° C to polymerize to obtain an average particle diameter of 0.085 μ, a gel content of 92%, and an swelling index of 18. Eggplant obtained small-diameter rubber latex A-3. The gel content and swelling index were measured by putting 1 g of polybutadiene rubber in 100 ml of toluene and leaving it at room temperature, then weighing the swelled rubber and the weight of the gel. The swelling index and the gel content defined in the present invention are as follows.

The characteristics of the three small-diameter rubber latex are shown in Table 1, and the particle size was measured by using Malvern's Autosizer IIc.

TABLE 1

The large-diameter rubber latex was prepared using the small-diameter rubber latex of Table 1 by the acid method (using acetic acid) and the shearing method (Homogenizer method). In general, the factors governing the aggregation is the amount of emulsifier, pH, temperature, the amount of solids, and the like, and when controlled well, large diameter rubber latex of desired size can be obtained. The large-diameter rubber latexes B-1, B-2, B-3 and B-4 used in the present invention aggregated the small-diameter rubber latex under the conditions shown in Table 2.

TABLE 2

1) Weight part of potassium rosinate as emulsifier per 100 parts by weight of latex (solid content)

2) The particle size distribution is μ

The graft polymerization in the present invention uses the aggregated large-diameter rubber latex (B-1, B-2, B-3) shown in Table 2, and the amounts and methods of the reaction compositions were adjusted to control the graft rate. The rubber content in the graft polymer was increased to perform the graft reaction within a short time, and the mixture was used in combination with the styrene-acrylonitrile copolymer resin. This can be said to be advantageous in terms of production.

That is, in the present invention, 20 to 60 parts by weight of a rubber latex having a gel content of 70 to 85%, an swelling index of 30 to 50, an average particle diameter of 0.3 to 0.5μ, a 30 to 60 parts by weight of a monovinylidene aromatic compound, and a cyanoalkene compound 8 It relates to a method for producing a graft copolymer having excellent impact resistance, characterized in that the polymerization by preparing the composition consisting of ~ 25 parts by weight, emulsifier, chain transfer agent, initiator.

The present invention is described in detail as follows.

The graft polymerization used a one-step polymerization method in which all components were added in a batch and a two-step polymerization method in which the components were separately added. In addition, in order to increase the graft rate, only a part of components or a continuous administration was used. 20 to 60 parts by weight of rubber latex (in solid content), 30 to 60 parts by weight of monovinylidene aromatic compound and 8 to 25 parts by weight of cyanoalkene compound are used alone or mixed with potassium rosin or potassium oleate as emulsifier. Potassium persulfate or cumene hydroperoxide was used as an initiator as n-dodecyl mercaptan or tertiary dodecyl mercaptan as a chain transfer agent. The one-step polymerization method used a batch dosing of all components and resulted in a high rubber content in the graft polymer. In addition, in order to increase the graft rate, a mixture of a monomer, an initiator and a chain transfer agent was continuously administered. The two-stage polymerization method is a method of dividing the reactant into two stages and polymerizing. The first stage components are collectively administered, followed by continuous administration in two stages, or the second stage of batch administration.

In the case of using the one-stage polymerization method in which all the physical properties were added, a resin having excellent impact resistance was obtained, and when the mixture of the monomer, the initiator, and the chain transfer agent was continuously administered, the graft ratio was increased and the flowability of the resin was improved. In the two-stage polymerization method, the graft ratio was controlled by using a method in which the one-stage components and the two-stage components were added in a batch and the one-stage components were added in a batch but the two-stage components were continuously added.

The graft ratio was measured as follows. First, 2 g of graft polymer powder and 300 ml of acetone were added to a solvent-cooled Ellenmeyer flask, and the temperature was raised and stirred for 24 hours. This solution is separated for 2 hours at 37,000 gauss using an ultracentrifuge. After condensation of the separated acetone solution, it was dropped in methanol to obtain an grafted styrene-acrylonitrile copolymer (SAN), which was dried and weighed. The graft ratio is defined as follows.

The amount of grafted SAN is the amount of ungrafted SAN subtracted from the total amount of monomer injected.

The graft polymer polymerized as described above had two SANs having different molecular weight distributions prepared by the bulk polymerization method in order to obtain resins having excellent impact resistance, and had a bipartite molecular weight distribution in the matrix. Was used to raise.

In the Examples, "parts" and "%" mean "parts by weight" and "% by weight", respectively.

EXAMPLES 1-8

The reaction product was added to the reactor and the initial reaction temperature was 40 ° C., the reaction temperature was raised to 70 ° C. over 1 hour, and the reaction was continued for about 3 hours. The conversion of the polymer obtained in this manner is 97% or more, and the amount of coagulated product is 0.2% or less when the latex is filtered through a mesh of 50 mesh. After adding an antioxidant to the resulting polymer latex, it was coagulated with 5% aqueous sulfuric acid solution, washed and dried to obtain a white powder. Styrene-acrylonitrile copolymers (SAN) having the properties shown in Table 3 were used in combinations as shown in Table 4 to change the molecular weight distribution and acrylonitrile (AN) content of SAN. SAN was mixed with the synthesized graft polymer to make the rubber content in the resin 25%, extrusion was carried out at 200 ° C., injection molding was performed, and a test piece was made to measure physical properties. The results are shown in Table 4.

TABLE 3

Comparative Example 1

Polymerized with the same prescription as in Example 1, the rubber latex used was agglomerated rubber latex B-4. SAN was added to the resultant graft polymer in the same combination as in Example 4 so that the AN content in the matrix was 30%. The results are shown in Table 4.

Example 9

Among the components of Example 1, except for the monomers styrene and acrylonitrile, cumene hydroperoxide as initiator, and tertiary dodecyl mercaptan as a chain transfer agent, were added to the reaction tank, the reaction temperature was set to 70 ° C, and then the monomer, initiator The mixture of chain transfer agent is added over 4 hours. Physical properties were measured by adding SAN in the same manner as in Example 4. The results are shown in Table 4.

Example 10

[Stage 1]

After the batch administration of the components of the first stage to the reactor, the reaction temperature is started at 40 ° C and raised to 70 ° C over 1 hour, and then the emulsion of the second stage components is added over 3 hours. When the addition of the emulsion is completed, the reaction temperature is raised to 80 ° C. and further aged for 1 hour to terminate the reaction. The rubber latex used at this time is agglomerated rubber latex B-3, and the conversion rate of the obtained polymer is 97% or more. 100 parts by weight of the graft polymer thus produced was added 8.6 parts by weight of SAN-1 and 51.4 parts by weight of SAN-4 to 30% of the AN content in the matrix, the rubber content of the resin to 25% Was measured. The results are shown in Table 4.

Example 11

After batch administration of the components of the first stage to the reactor, the reaction temperature starts at 40 ° C. and is raised to 70 ° C. over 1 hour. At this time, after the batch administration of the components of the second stage, the reaction for 3 hours. The cohesive rubber latex used was B-3, and the amount of dilution SAN added was the same as in Example 10. The results are shown in Table 4.

Example 12

Using agglomerated rubber latex B-2, the polymerization formulation and polymerization method were the same as in Example 10, and the addition amount of the dilution SAN was also the same. The results are shown in Table 4.

TABLE 4

1) Based on Graft Polymer 100

2) Notch Izod impact strength: 1/4 ″ specimen, 23 ℃

3) 220 ℃, 10kg

4) Incident angle 60 °

5) R-scale

As shown in Table 4, a thermoplastic resin having excellent impact resistance and fluidity by incorporating a styrene-acrylonitrile copolymer having a molecular weight distribution in a double polydisperse form into the graft copolymer and increasing the acrylonitrile content in the matrix. Got. In addition, as shown in Table 4, large diameter rubbers with low gel content and high swelling index had higher gel content and showed better impact strength and flow index when manufacturing ABS or ABS type resins than low swelling index. . It is thought that the lower the swelling index, the lower the graft ratio, and thus these characteristics were reduced. In addition, the use of SAN having a high molecular weight distribution and having a high molecular weight distribution as a matrix is advantageous for increasing the impact strength of the thermoplastic resin.

Claims (7)

20 to 60 parts by weight of rubber latex having a gel content of 70 to 85%, swelling index of 30 to 50, average particle diameter of 0.3 to 0.5μ, 30 to 60 parts by weight of monovinylidene aromatic compound, 8 to 25 parts by weight of cyanoalkene compound, Method for producing a graft copolymer excellent in impact resistance, characterized in that the graft polymerization by adding an emulsifier, a chain transfer agent, an initiator. The method of producing a graft copolymer having excellent impact resistance according to claim 1, wherein a monomer mixture, an initiator, and a chain transfer agent are continuously added. The method of producing a graft copolymer having excellent impact resistance according to claim 1, wherein the components of one step are collectively administered by a two-step polymerization method, and the two steps of components are continuously administered. The method of claim 1, wherein after the batch administration of the components of the first stage by a two-stage polymerization method, the reaction proceeds, and then the two-stage components are collectively administered. . The rubber content is 50 to 78% by weight and the weight percentage of the monovinylidene aromatic compound to the cyanoalkene compound is 80:20 to 65:35 as one step in the two-stage polymerization. Method for producing a graft copolymer having excellent impact resistance. The graft copolymer having excellent impact resistance according to claim 1, wherein the weight ratio of the monovinylidene aromatic compound to the cyanoalkene-based compound is 75:25 to 65:34 as two steps in the two-step polymerization. Manufacturing method. When the styrene-acrylonitrile copolymer is added to the synthesized graft polymer, the difference in weight average molecular weight is 30,000 to 80,000 by mixing a styrene-acrylonitrile copolymer having a relatively low molecular weight distribution and a relatively high molecular weight distribution. A method for producing a graft copolymer having a bimodal molecular weight distribution and excellent acrylonitrile content of the copolymer in an amount of 27 to 30% by weight.