JPS5915331B2 - Manufacturing method of impact-resistant and weather-resistant thermoplastic resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a thermoplastic resin that has excellent impact resistance and weather resistance and can be processed into good molded products.

Resin-rubber two-component system as one of the impact-resistant resins! 0 A typical composition is ABS resin;
The resin has many chemically unstable double bonds in the main chain of the rubber component used, that is, the diene polymer.
It is also known that it is easily degraded by light and has poor weather resistance.

In addition, as a material with improved weather resistance, rubber-like elastic materials with almost no double bonds in the main chain, a typical example of which is acrylic rubber, are known. Many proposals have been made regarding the manufacturing method. j0 However, from a practical standpoint, thermoplastic resins manufactured with conventional dimensions still have some problems.

One of them is the appearance of the injection molded product, that is, the dichroism of the weld part. Conventionally, acrylic rubber has been used to improve impact resistance and weather resistance.
When producing a polyurethane resin, the acrylic rubber component must have a crosslinked structure, and proposals have been made regarding the crosslinking method, such as the type of crosslinking agent and peroxide crosslinking.

However, in general, increasing the degree of crosslinking of acrylic rubber improves the appearance of the molded product, but the impact resistance decreases, making it impossible to obtain the desired impact resistant resin. As a result of various studies in this regard, the present inventors have discovered a method for producing a weather-resistant thermoplastic resin that has excellent impact resistance and improved dichroism in the weld area, thereby obtaining the present invention.

Here, weld part dichroism refers to the fact that in an injection molded product, the color tone exhibits dark and light dichroism at the weld part.

Since the color tone has directionality, it is thought that this dichroism occurs at the weld portion where two colors with different directionality butt against each other.

The present invention emulsion-polymerizes at least one monomer selected from aromatic vinyl monomers, vinyl cyanide monomers, and methacrylic acid esters in the presence of a crosslinked acrylic rubber latex, and then thermally polymerizes them. In the method for producing a plastic resin, (1) the crosslinked acrylic rubber has an orifice outflow velocity of 5 x 10 -3 d or less and a gel content of 90% or more, (j1) the latex has a turbidity of 20% or more, (111) A method for producing an impact-resistant and weather-resistant thermoplastic resin, characterized in that the latex and the monomer are mixed under stirring at a stirring speed of 2.57 n/Sec or more before emulsion polymerization.

Crosslinked acrylic rubber refers to acrylic esters having an alkyl group having 1 to 13 carbon atoms (n-butyl acrylate is particularly preferred; other examples include ethyl acrylate, propyl acrylate, hexyl acrylate, and 2-ethylhexyl acrylate). etc.

) is a polymer or copolymer obtained by using 50% or more by weight of 70% or more, especially a cross-linked polymer. In order to introduce this crosslinking, the above acrylic ester is polymerized in the presence of a crosslinking agent. That is, a method of copolymerizing a multifunctional monomer (crosslinking agent) having two or more functional groups copolymerizable with the above acrylic ester, and a method of polymerizing the above acrylic ester in the presence of a peroxide (crosslinking agent). There are ways to do this. In particular, the former method yields crosslinked acrylic rubber with better rubber elasticity. As the polyfunctional monomer, triallyl cyanurate,
Polyvalent vinyl compounds and polyvalent allyl compounds such as triallyl isocyanurate, divinylbenzene, triacryl formal, and ethylene glycol dimethacrylate are effective, and triallyl isocyanurate, triallyl cyanurate, and triacryl formal are particularly preferred. The amount of this polyfunctional monomer to be used is determined as appropriate;
Generally, about 0.5 to 5 70% by weight based on the crosslinked acrylic rubber raw material is preferred. For crosslinked acrylic rubber, if the orifice outflow rate is higher than 5x10-3C71L/Sec or if the gel content is lower than 9070, it indicates that the crosslinking of the rubber is insufficient. The rubber component is easily oriented and deformed by the shearing force, and the dichroism of the weld portion becomes large.

Therefore, the orifice outflow rate of crosslinked acrylic rubber is 5×
10-3~/Sec or less, gel content 90% or more, preferably orifice flow rate 3X1'3CTit/SeC
Below, a gel content of 95% or more is required. The turbidity of the latex is related to the size of the rubber particles in the latex.

When the turbidity is lower than 2070, not only is the impact resistance inferior, but the orifice outflow rate also tends to increase.
The turbidity is 20% or more, preferably 3070 or more. A turbidity of 20% or more corresponds to an average particle diameter of about 0.1 μm or more as measured by an electron microscope. In the present invention, there are no particular restrictions on the production of the crosslinked acrylic rubber latex, but in order to produce a latex with a turbidity of 2070 or higher, it is preferably produced by an emulsion polymerization method or a sheet polymerization method.

That is, the above raw materials are mixed in an aqueous medium with an emulsifier (for example, polyoxyethylene cetyl ether is particularly preferred).
) in the presence of a polymerization initiator such as potassium persulfate or ammonium persulfate, a crosslinked acrylic rubber latex with high turbidity is obtained. Also, a latex is obtained in the same manner as in such emulsion polymerization, and this is used as a seed latex, and the remaining raw materials (the crosslinking agent is added at the time of manufacturing the seed latex or during the subsequent emulsion polymerization).

) in an aqueous medium in the presence of an emulsifier (preferably an anionic or nonionic emulsifier), potassium persulfate,
A highly turbid crosslinked acrylic rubber latex can be obtained by emulsion polymerization using a polymerization initiator such as ammonium persulfate. In both of the above methods, the polymerization temperature is 20 to 100°C, preferably 40 to 70°C.
It is ℃. Examples of the aromatic vinyl monomer used in the present invention include styrene, α-substituted styrenes such as α-methylstyrene, and nuclear-substituted styrenes such as chlorostyrene, vinyltoluene, and t-butylstyrene.

Examples of vinyl cyanide monomers include acrylonitrile and methacrylonitrile.

Examples of methacrylic esters include methyl methacrylate,
Examples include ethyl methacrylate and butyl methacrylate.

The amount of these monomers to be used is determined as appropriate, but when vinyl cyanide monomer and methacrylic acid ester are used, 40% by weight or less and 70% by weight 70% or less in the monomers, respectively. Preferably, the aromatic vinyl monomer is used in an amount of 30% by weight or more of 70% of the total monomers.
Preferred for various properties. The latex and the monomers are stirred at a stirring speed of 2.0% before emulsion polymerization (preferably just before).
Mix while stirring at 5 ml or more.

Conventionally, it was considered virtually impossible to subject cross-linked acrylic rubber latex to high-speed agitation treatment due to the formation of large amounts of aggregates, but surprisingly, when high-speed agitation treatment is performed with the above monomers, (In this case, when using an emulsifier, an anionic or nonionic emulsifier is preferred.

), it was found that the formation of aggregates was extremely small and that it was highly effective in improving impact resistance. The effect is thought to be that the above-mentioned monomer uniformly impregnates and swells the crosslinked acrylic rubber. When the stirring speed is lower than 2.5 m/Sec, this effect is small, and the resulting resin has poor impact resistance. Here, the stirring speed is the circumferential speed of the stirring blade. In this stirring, it is preferable to use shearing, especially at a speed of 1 x 105 to 5 x 106 mu1
Preferably with a shear of −1. In the present invention, the latex and the monomer are combined into a latex (in terms of solid content) of 5
It is preferable to use 95 to 40 parts by weight of the monomer relative to 60 parts by weight.

Further, it is preferable to adjust the rubber content of the final product to 4 to 40% by weight. Furthermore, in the present invention,
Emulsion polymerization is preferably carried out at a temperature of 20 to 100°C, particularly 50 to 75 milk C, and during the polymerization, an emulsifier, a polymerization initiator, a chain transfer agent, etc. are added as appropriate. Examples of emulsifiers include anionic emulsifiers such as sodium and potassium salts of oleic acid, stearic acid, lauric acid, rosin acid, dodecyl sulfuric acid, dodecylbenzenesulfonic acid, alkylsulfosuccinic acid, and nonionic emulsifiers such as polyester. Oxyethylene cetyl ether (HLB of 14 to 16 is particularly preferred).

) etc. are preferable in order to improve gloss and eliminate dichroism in the weld area. Conventionally well-known emulsifiers such as partially saponified polyvinyl alcohol, polyoxylene oxide,
Water-soluble polymers such as sodium polyacrylate, polyacrylamide, and hydroxyethyl cellulose are not preferred in terms of the gloss of the resulting resin and the dichroism of the weld area. This is true of the emulsifier used at any stage of the invention. As a polymerization initiator,
A peroxide such as yumene hydroperoxide and a redox initiator such as Rongarit are used in an amount of about 0.1 to 2% by weight based on the monomers mentioned above.

As a chain transfer agent, tert-dodecyl mercaptan or the like is used in an amount of about 0.1 to 1% by weight based on the monomer.

In addition, water (deionized water) is used as a medium for emulsion polymerization, and the solid content at the end of polymerization is about 20 to 40% by weight. It is preferable to use it so that

The emulsion polymerization is preferably carried out in an atmosphere of an inert gas such as nitrogen. After the polymerization, the polymer is separated by salting out or the like, and after drying, it is pelletized using, for example, an extruder. In addition, the thermoplastic polymer obtained by the present invention is a copolymer of a vinyl cyanide monomer and an aromatic vinyl monomer, and, as appropriate,
be blended.

In the present invention, the orifice outflow rate means that the dried polymer is heated using a Koka-type blow setter at a temperature of 200°C, a pressure of 30 kg/CTi, and an orifice diameter of 1 m77! φ×2m
Measured under conditions of m.

In addition, the gel content means that polymer 19 is mixed with 50rr of acetone.
Dissolved in Le, centrifuged to remove insoluble matter, and weighed its absolute dry weight (W
g) and calculated as w/1×100(to). Furthermore, turbidity is measured by dispersing a polymer in ion-exchanged water so that the solid content is 0.03% by weight and using a turbidity meter as a sample.

Note that the standard is ion-exchanged water. Example 1 1-1 Production of seed latex for sheet polymerization In a reaction vessel, 1600 parts of ion-exchanged water and 20 parts of Nonsal TN-1 (fatty acid soap manufactured by NOF Corporation) were dissolved, and 200 parts of separately prepared ion-exchanged water and 200 parts of supernatant were dissolved. An aqueous solution of 20 parts of potassium sulfate, 0.4 parts of sodium sulfite, and a monomer solution consisting of 600 parts of butyl acrylate, 270 parts of styrene, 90 parts of acrylonitrile, and 40 parts of triallyl cyanurate were mixed and replaced with nitrogen.

After that, the temperature was raised, and during polymerization, when the polymerization rate reached 4070, a solution of 110 parts of Nonsal TN-1 dissolved in 200 parts of ion-exchanged water was added, and the mixture was heated at 60 to 650C for 12 hours, for a further 85 to 90 minutes.
Polymerization was carried out at 0°C for 3 hours to obtain a seed latex (1).
1-2 Production of cross-linked acrylic rubber latex Dissolve 2000 parts of ion-exchanged water and 112 parts of Nonsal TN-1 in a reaction vessel, add 200 parts of separately prepared ion-exchanged water, 1.2 parts of potassium persulfate, and 0.24 parts of sodium sulfite. After mixing and stirring an aqueous solution consisting of 30 parts (solid content) of seed latex (1), 1152 parts of butyl acrylate,
A monomer solution consisting of 48 parts of triallyl cyanurate was added, the atmosphere was replaced with nitrogen, the temperature was raised, and the polymerization rate was 40? Non-salle T
200 parts of ion-exchanged water in which 14 parts of N-1 was dissolved was added.

Polymerization was carried out at 60-65℃ for 12 hours and at 185-90℃ for 3 hours.
A crosslinked acrylic rubber latex (1) was obtained.
The polymerization rate was 99701. The flow rate of the crosslinked acrylic rubber from the orifice was 4.5 x 10-3 d/Sec, and the turbidity of the latex was 35%. 1-3 Emulsion polymerization in the presence of crosslinked acrylic rubber latex 1200 parts of ion-exchanged water was placed in a container equipped with a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.).
Add 2.8 parts of Rongarit and 16.4 parts of Nonsal TN-dissolved, and add 600 parts of styrene, 200 parts of acrylonitrile, and 2.8 parts of Kyumene hydroperoxide.
After adding a monomer solution consisting of 1 part and 2.2 parts of tertiary dodecyl mercaptan and purging with nitrogen, homomixer treatment was carried out for 4 m/s.
Sec for 5 minutes, then 200 parts (solid content) of cross-linked acrylic rubber latex was added and homomixer treatment was carried out for 3 minutes.
It lasted 0 minutes.

Thereafter, the emulsion polymerization latex (
1) was obtained. This emulsion polymerization latex (1) was added dropwise to an aqueous solution prepared by dissolving 10 parts of potassium uran in 500 parts of ion-exchanged water and heated to 95° C. with stirring, followed by salting out, followed by dehydration and drying to obtain a powder. This powder was pelletized using an extruder and used as a sample for evaluating physical properties, which will be described later. I-4 Evaluation method 1) Measurement of orifice flow rate of cross-linked acrylic rubber The cross-linked acrylic rubber latex is dropped into a mixture of 3 parts isopropyl alcohol and 1 part water with stirring to coagulate, and then washed and dried to form a solid. I got my share.

This solid content was tested at a temperature of 200% using a Koka type flow tester.
℃, pressure 30kg/d, orifice diameter 1φ x 2m7! L
Tested under the following conditions. 11) Gel content of crosslinked acrylic rubber The above crosslinked acrylic rubber solid content 19 was mixed with 50cc of acetone.
The insoluble matter was centrifuged at 16,000 RPM,
The absolute dry weight was determined and used as the gel content.

1 [1) Turbidity of cross-linked acrylic rubber latex A sample of cross-linked acrylic rubber latex diluted with ion-exchanged water and adjusted to a solid content of 0.0370 was measured using a turbidity meter (Nippon Denshoku Kogyo ND-H5 model). It was measured.

1) Weld part dichroic cyanine pull colorant 1.5PHR. Ti020.2P
A pellet colored with HR was used as a sample and molded using a weld forming mold at a cylinder temperature of 240°C.

The evaluation was carried out visually, with ◎ indicating almost no weld dichroism, × indicating clearly observed weld dichroism, and △ indicating intermediate between these. V) Physical Properties Tests were conducted in accordance with the applicable test methods of JIS or ASTM.

Vl) Weather resistance Evaluated by accelerated test using sunshine weather meter.

Reference Example 1 The monomer composition during the production of cross-linked acrylic rubber latex was changed to butyl acrylate 118 without using a seed latex.
8 parts triallyl cyanurate, 12 parts triallyl cyanurate, and 20 parts nonsal TN-1 initially charged, and instead of homomixing, a propeller-type stirring blade was used at a stirring speed of 1 m/Se.
The procedure of Example 1 was followed except that the treatment was carried out in step c.

Reference Example 2 The monomer composition during the production of crosslinked acrylic rubber latex was 1188 parts of butyl acrylate and 12 parts of triallyl cyanurate, and instead of homomixing, a propeller-type stirring blade was used at a stirring speed of 1 m/Sec. The same procedures as in Example 1 were performed except for the treatment.

The evaluation results of Example 1 and Reference Examples 1 and 2 are shown in Table 1.

Table 2 shows the accelerated weathering test results for the resin obtained in Example 1 and the commercially available ABS resin.

Claims (1)

[Scope of Claims] 1. At least one monomer selected from the group consisting of an aromatic vinyl monomer, a vinyl cyanide monomer, and a methacrylic acid ester in the presence of a crosslinked acrylic rubber latex. In the method for producing a thermoplastic resin by emulsion polymerization, (i) the crosslinked acrylic rubber has an orifice flow rate of 5 x 10^-^3 cm^2/sec or less and a gel content of 90% or more, and (ii) ) The latex has a turbidity of 20% or more, and (iii) the latex and the monomer are mixed at a stirring speed of 2.5 m/sec or more before emulsion polymerization. (The orifice outflow rate is determined by measuring the dry polymer using a Koka type flow tester at a temperature of 200°C.
Measurements were made under the conditions of a pressure of 30 kg/cm^2, an orifice diameter of 1 mmφ, and a length of 2 mm.The turbidity was measured using a sample in which the polymer was dispersed in ion-exchanged water to a solid content of 0.03% by weight. ). 2. The method for producing an impact-resistant and weather-resistant thermoplastic resin according to claim 1, wherein an anionic emulsifier or a nonionic emulsifier is used as the emulsifier. 3. The crosslinked acrylic rubber latex is obtained by emulsion polymerization of acrylic acid ester in the presence of a crosslinking agent using polyoxyethylene cetyl ether as an emulsifier. Process for producing impact-resistant, weather-resistant thermoplastic resins. 4. Claim 1 or 2, in which the latex of the crosslinked acrylic rubber is obtained by a seed polymerization method.
A method for producing the impact-resistant and weather-resistant thermoplastic resin described in .