JP2783476B2 - Method for producing coagulated polymer and composition thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a coagulated polymer and a coagulated polymer composition.

[0002]

2. Description of the Related Art As a method for improving the impact resistance of a synthetic resin such as an acrylic resin, a styrene resin, and a vinyl chloride resin,
Generally, a rubber phase having elasticity is discontinuously dispersed in a hard resin. The introduction of diene rubber is the most common, but acrylic rubber is also widely used from the viewpoint of weather resistance.

[0003] Modified resins using acrylic rubber include:
Various types of multi-layered polymers based on a core and shell structure and combining a soft layer and a hard layer have been studied.
54-18298, JP-B 55-27576, JP-B 62-41241
issue). An emulsion polymerization method is widely used as a production method thereof. In the method for producing a polymer using these emulsion polymerization methods, a step of taking out the polymer from the polymer latex is required.As a method for this, a method of adding an inorganic salt such as aluminum chloride and magnesium sulfate, sulfuric acid, etc. A method of adding an acid, a spray drying method, and the like are used. However, the above-mentioned method has a problem that the obtained polymer is in the form of a fine powder and is difficult to handle, which causes a decrease in productivity and a decrease in molding workability. On the other hand, those molded by using these polymers also have problems such as inferior optical properties due to heat coloring.

[0004] As a method of improving the handleability of a polymer, a method of suppressing a blocking phenomenon at the time of drying by mixing a slurry of an impact resistance modified polymer and a slurry of a hard inelastic polymer and then drying the mixture ( JP-A-58-1742) has been proposed. Although some improvement effect is recognized, it is not sufficiently satisfactory, and the coloring is not improved.

As a method for improving coloring, -OSO3
A method in which polymerization is carried out using an emulsifier having a group represented by M, -COOM, and -SO3M (where M is K or Na), and the obtained latex is brought into contact with an aqueous solution of magnesium sulfate to take out a polymer (Japanese Unexamined Patent Application Publication No. 61-108629), -PO3M2, -PO2M
(However, polymerization is carried out using an emulsifier having a group represented by M (alkali metal or alkaline earth metal), and the obtained latex is brought into contact with an aqueous solution of magnesium sulfate to remove the polymer (Japanese Patent Application Laid-Open No. 63-1988). No. 227606) has been proposed. Although some improvement effect is recognized, it is not sufficiently satisfactory, and furthermore, it has a disadvantage that the separated polymer is in a fine powder form and is difficult to handle.

[0006]

That is, an object of the present invention is to provide a method for producing a polymer coagulated product using emulsion polymerization, wherein the polymer coagulated product is excellent in impact resistance, optical properties, molding workability, and handleability. To provide a manufacturing method for obtaining

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies in view of such a situation, and as a result, the latex of the multilayer structure polymer obtained by the emulsion polymerization method is frozen, melted, and then dehydrated, whereby the latex is decomposed from the latex. The inventors have found that the above problems can be solved by removing the structural polymer, and have completed the present invention.

That is, according to the present invention, the outermost layer is (1) a hard layer having a glass transition temperature of 25 ° C. or more when polymerized alone, and at least one of the inner layers is (2) at least one diene-based monolayer. Over 60 % by weight and 100% by weight
% Or less , 40% by weight or less of other monomers copolymerizable therewith.
Obtained by polymerizing a monomer mixture consisting of fully, prepared by emulsion polymerization latex of the multilayer structure polymer is a soft layer having a glass transition temperature below 25 ° C. when polymerized alone, the latex Freeze at a speed of 4cm / hr or less
The present invention also relates to a method for producing a coagulated polymer, wherein a polymer having a multilayer structure is taken out of a latex by melting and then dewatering.

In the production method of the present invention, the multi-layered polymer is produced by an emulsion polymerization method, and the outermost layer comprises (1)
A hard layer having a glass transition temperature of 25 ° C. or more when polymerized alone, wherein at least one of the inner layers comprises (2) at least one type of diene-based monomer exceeding 60 % by weight
% By weight or less , 40 % by weight of another monomer copolymerizable therewith
% By polymerization of a monomer mixture having a glass transition temperature of less than 25 ° C. when polymerized alone.

The proportion of the outermost layer in the multilayer polymer is not particularly limited, but is preferably from 10 to 80% by weight in order to obtain good dispersibility at the time of melt-kneading. Therefore, the temperature is preferably 50 ° C. or higher. Further, the molecular weight of the outermost layer is preferably adjusted. The reason is that when the coagulated product of the present invention is formed or processed, or when the coagulated product of the present invention is used as a modifier for a synthetic resin, heat-melt fluidity is necessary. This is important from the viewpoint of compatibility. This adjustment can be performed using a chain transfer agent such as mercaptan.
The ratio of the soft layer having a Tg of less than 25 ° C to the multilayer polymer is not particularly limited, but is preferably from 10 to 80% by weight for the development of impact resistance, and Tg is preferably 0 ° C or less from the same point. preferable. Further, the inner layer of the multilayer polymer may have any layer structure consisting of the above-mentioned soft layer alone or a hard layer having a Tg of 25 ° C. or more when polymerized alone. For example, in a polymer having a multilayer structure including the outermost layer, a two-layer structure of a soft layer-a hard layer, a three-layer structure of a hard layer-a soft layer-a hard layer, a soft layer-a hard layer-a soft layer-a hard layer from the innermost layer And a four-layer structure of hard layer-soft layer-soft layer-hard layer. Further, the hard layer used for the outermost layer and the inner layer preferably has at least one methacrylate ester of 50 to 100.
% By weight, obtained by polymerizing a monomer mixture comprising 0 to 50% by weight of other monomers copolymerizable therewith. is there. As a result, those having excellent optical characteristics and weather resistance can be obtained.

The monomers used for polymerizing the hard layer of the multilayer polymer include the following. Methacrylic esters such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, acrylic acid Acrylic esters such as benzyl; aromatic vinyl compounds such as styrene, vinyltoluene and α-methylstyrene; N-cyclohexylmaleimide;
-Chlorophenylmaleimide, N-substituted maleimide compounds such as N-tert-butylmaleimide, acrylonitrile, vinyl cyanide compounds such as methacrylonitrile, allyl methacrylate, allyl acrylate, triallyl cyanurate, allyl cinnamate, allyl sorbate, Diallyl maleate, diallyl phthalate, triallyl trimellitate, diallyl fumarate, ethylene glycol di (meth) ate
Examples thereof include polyfunctional monomers such as acrylate, polyethylene glycol di (meth) acrylate, divinylbenzene, and 1,3-butylene glycol di (meth) acrylate, which are used alone or in combination.

Further, as the monomers used for polymerizing the soft layer of the multilayer structure polymer, the following monomers may be mentioned. Examples of diene monomers include 1,3-butadiene,
2,3-dimethylbutadiene, isoprene and the like,
They are used alone or in combination. Preferably 1,
3-butadiene. Other copolymerizable monomers include acrylates such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, benzyl acrylate, methyl methacrylate, methacrylic acid Ethyl, butyl methacrylate, benzyl methacrylate, methacrylic acid esters such as cyclohexyl methacrylate, styrene, vinyl toluene, aromatic vinyl compounds such as α-methylstyrene, acrylonitrile, vinyl cyanide compounds such as methacrylonitrile, allyl methacrylate , Allyl acrylate, triallyl cyanurate, allyl cinnamate, allyl sorbate, diallyl maleate, diallyl phthalate, triallyl trimellitate, diallyl fumarate, ethylene glycol di (meth) acrylate, Triethylene glycol di (meth) acrylate, divinylbenzene, 1,3 polyfunctional monomers such as butylene glycol di (meth) acrylate. They may be used alone or in combination.

The particles of the multi-layered polymer obtained by the emulsion polymerization method are not particularly limited, but may vary within a particle size range of 0.01 to 0.5 μm. The thickness is preferably 0.05 to 0.3 µ for the purpose of exhibiting impact resistance.

In the production method of the present invention, the multilayer polymer is produced by a known emulsion polymerization method. As a method for producing a multilayer polymer, first, a desired monomer mixture is emulsion-polymerized to form core particles, and then the other monomer mixture is emulsion-polymerized in the presence of the core particles to form a shell around the core particles. Create Then, another monomer mixture is emulsion-polymerized in the presence of the core and shell particles to form another shell. By repeating such a reaction, a desired multilayer polymer is obtained.

The type and amount of the emulsifier used in the emulsion polymerization are selected depending on the stability of the polymerization system, the intended particle size, and the like.
Known emulsifiers such as nonionic surfactants can be used alone or in combination. Particularly, an anionic surfactant is preferably used. Examples of the anionic surfactant include carboxylate salts such as sodium stearate, sodium myristate and sodium N-lauroyl sarcosinate, sulfonates such as sodium dioctylsulfosuccinate and sodium dodecylbenzenesulfonate, and sulfates such as sodium lauryl sulfate. Examples thereof include ester salts and phosphate salts such as sodium mono-n-butylphenylpentaoxyethylene phosphate.

The polymerization initiator used in the emulsion polymerization is not particularly limited, but inorganic peroxides such as potassium persulfate and ammonium persulfate, hydrogen peroxide-ferrous salt system, potassium persulfate-sodium acid sulfite system Water-soluble redox initiators such as ammonium persulfate-sodium acid sulfite, cumene hydroperoxide-sodium formaldehyde sulfoxylate, tert-butyl hydroperoxide-sodium formaldehyde sulfoxylate, etc. A water-soluble or oil-soluble redox initiator is used.

The chain transfer agent optionally used includes n-dodecyl mercaptan, n-lauryl mercaptan, tert-dodecyl mercaptan, sec-butyl mercaptan and the like.

In the emulsion polymerization, the monomer, emulsifier, initiator, chain transfer agent and the like may be added by any known method such as a batch addition method, a division addition method and a continuous addition method.

In the production of the coagulated polymer of the present invention, as a freezing method, a known air freezing method, contact freezing method, immersion freezing method, spray freezing method or the like is used.
It is necessary to freeze at a rate of / hr or less . here,
Start freezing when the polymer latex temperature reaches 0 ° C,
When the coalesced latex temperature reaches -5 ° C, the freeze is terminated.
And the time in between is defined as the freezing time, and
The thickness at which the polymer latex is frozen is defined as the freezing speed.
By adopting the above freezing conditions, handleability and extrusion stability in a subsequent step are further improved . Melting is 40 ℃ ~1 after sintering frozen
It is more preferable to carry out at 00 ° C., and to wash the obtained polymer with water at 0 ° C. to 100 ° C. or warm water.

The freezing and coagulation in the present invention is considered to proceed by the following mechanism. When the latex is cooled below the freezing point of water, ice crystals are generated in the aqueous phase, and the latex grows while excluding the spherical polymer particles and the water-soluble substance dissolved in the aqueous phase. The spherical polymer particles are trapped between the ice crystals, and the water-soluble substances are also concentrated there and precipitate when the concentration reaches a saturation value. As the ice crystals grow, the spherical polymer particles are gradually pressed. As the temperature further decreases, the concentrated aqueous solution of the water-soluble substance freezes. As the freezing proceeds, the bare spherical polymer particles are compressed and firmly pressed. When the latex that has undergone this step is melted, the compression of the spherical polymer particles is not broken and is separated from the aqueous phase as a coagulated product.

However, the properties of the coagulated product and the molded product obtained therefrom differ considerably depending on the type of the polymer and the freezing conditions, and those having excellent properties such as handleability, molding processability, impact resistance, and optical characteristics are very different. However, it is not always obtained by the freeze-coagulation method. By combining a specific multilayer structure polymer and a freeze-coagulation method, preferably a specific freezing condition, a suitable pressure-bonding property of the spherical polymer particles, a suitable particle size of the coagulated material, and an easy washing of impurities such as an emulsifier. And the object of the present invention is achieved for the first time.

The most characteristic feature of the method for producing a coagulated polymer of the present invention is that the polymer is frozen at a speed of 4 cm / hr or less . However, the spray-drying method and the acid or salt addition method cannot be used in the present invention because the obtained coagulated material has poor handleability and the stability during extrusion molding is poor.

The present invention also relates to a method for producing a polymer coagulation composition.

The process for producing the polymer coagulation composition of the present invention comprises:
Producing a latex of a hard polymer having a glass transition temperature of 25 ° C. or more by an emulsion polymerization method, and the latex,
By mixing the latex of the multilayer structure polymer obtained by the emulsion polymerization method, the mixed latex is frozen, melted, and then dehydrated, to thereby obtain a polymer composition comprising a hard polymer and a multilayer structure polymer from the mixed latex. It is a method of taking out.

In the method for producing the solidified composition, as the monomer used for polymerizing the hard polymer, the same monomers as those used for the hard layer of the multilayer polymer can be used. The preferred hard polymer is a polymer obtained by polymerizing a monomer mixture of 50 to 100% by weight of at least one methacrylate ester and 0 to 50% by weight of another monomer copolymerizable therewith. is there. The molecular weight of the hard polymer is preferably adjusted in order to improve moldability, and this adjustment can be performed using a chain transfer agent such as mercaptan. Further, the emulsion polymerization of the hard polymer and the freezing, thawing and dehydration of the latex mixture can be carried out in the same manner as in the method for producing the coagulated polymer, and preferable freezing conditions are also the same.

According to this production method, the multilayer polymer obtained by the emulsion polymerization method and the hard polymer obtained by the emulsion polymerization method are mixed in a latex state. There is an advantage that the mixed state can be made more uniform as compared with the mixed one. As a result, the obtained molded product has improved impact resistance in addition to improved dispersibility.

In the production method of the present invention, if necessary, a lubricant, an ultraviolet absorber, a light stabilizer, a heat stabilizer, an antioxidant, a plasticizer, a dye / pigment, an antistatic agent, a flame retardant, etc. may be added in optional steps. Can be added.

Further, the obtained polymer coagulated product and polymer coagulated composition can be used as it is by molding or blending with another polymer.

[0029]

The present invention will be described in more detail with reference to the following examples. The measurement of various characteristics shown in the examples was performed according to the following methods. (1) Fusing and blocking when the polymer coagulated product or the polymer coagulated composition is dried; the coagulated product is dried at 80 ° C. for 10 hours in a tray-type hot-air dryer to cause fusing and blocking. The following table shows the results. X: Fusing and blocking occurred. O: No fusion or blocking occurred. (2) Extrusion stability: Extrusion stability when the dried acrylic polymer coagulated material was melt-kneaded and pelletized using a 40φ extruder was examined and shown as follows. Stable: Stable extrusion with little surging. Unstable: Surging easily occurred and extrusion could not be performed stably. (3) Izod impact strength; ASTM-D256 (4) Yellow index; ASTM-D1925 (3 mm plate thickness) The abbreviations used in the examples are shown below. Methyl methacrylate (MMA), butyl acrylate (BA) styrene (ST), N-cyclohexylmaleimide (CHM
I), n-octyl mercaptan (n-OM), 2,6
-T-butyl paracresol (BHT).

Parts represent parts by weight and% represents% by weight. (Example 1) 140 parts of ion-exchanged water were placed in a pressure-resistant reaction vessel.
BA 24.5 parts, sodium stearate 0.7 parts, N
0.35 parts of sodium lauroyl sarcosinate, 0.35 parts of sodium pyrophosphate, 0.0035 ferrous sulfate
Parts, dextrose 0.21 part, and diisopropylbenzene hydroperoxide 0.14 part. After purging with nitrogen, 45.5 parts of 1,3-butadiene was added, and 6
It was kept at 0 ° C. for 7 hours.

Then, the obtained latex was transferred to a reaction vessel equipped with a reflux condenser, and further 60 parts of ion-exchanged water, 0.06 part of potassium persulfate and 0.15 part of sodium N-lauroyl sarcosinate were added, and 55 The temperature was raised to ° C. Then, 25.5 parts of MMA, 3 parts of CHMI, 1.5 parts of ST, n-
A monomer mixture consisting of 0.02 parts of OM was continuously added over 90 minutes, and the mixture was kept for 90 minutes after completion of the addition to obtain a two-layer polymer latex.

The obtained latex was placed in a stainless steel container so as to have a height of 6 cm, and was frozen at −20 ° C. in a freezer. Temperature was measured by placing a thermocouple in latex
Result, we either reached 0 ° C. - to pass through the 5 ° C., it took 4 hours and 30 minutes. That is, the freezing speed was 1.3 cm / hr. After the slowest part of the temperature drop passes -5 ° C,
After further cooling for 2 hours, the frozen latex was taken out.

After the frozen latex was thawed at 70 ° C., the polymer was separated by filtration. Further, washing and dehydration were repeated three times with hot water at 70 ° C., followed by drying at 80 ° C. for 10 hours. Fusing and blocking did not occur, and a smooth coagulated product was obtained.

3 parts of the dried coagulated material thus obtained and MMA85
-CHMI10-ST5 (wt%) was mixed at a ratio of 7 parts of acrylic resin beads, and melt-kneaded at a cylinder temperature of 250 ° C using a 40φ extruder to obtain pellets. At this time, surging hardly occurred, and the extrusion was stable. The pellets were subjected to injection molding at a cylinder temperature of 250 ° C. and a mold temperature of 60 ° C. to obtain an Izod impact strength test piece based on ASTM standards and a 50 × 50 × 3 mm flat plate. Table 1 shows the results of evaluating various characteristics using this test piece. (Example 2) Table 1 shows the results of evaluation performed in the same manner as in Example 1 except that the freezing conditions were changed as shown in Table 1. (Comparative Example 1) 100 parts of the final latex obtained in Example 1,
After mixing 2 parts of BHT and 1.5 parts of calcium stearate, salting out and coagulation were carried out at 70 ° C. using twice the amount of a 1% aqueous solution of aluminum chloride. Then, washing and dehydration were repeated three times with hot water at 70 ° C., and then dried at 80 ° C. for 10 hours. Since the coagulated material was fused and blocked, the condition was set at 60
The temperature was changed to -15 hours and dried.

Table 1 shows the results of the evaluation performed in the same manner as in Example 1 except that the obtained coagulated product after drying was used. (Comparative Example 2) Except for using 1% aqueous sulfuric acid solution,
Table 1 shows the results of the evaluation performed in the same manner as in Comparative Example 1. (Example 3) (Production of polymer having two-layer structure) In a pressure-resistant reaction vessel, 140 parts of ion-exchanged water, 0.7 part of sodium stearate, 0.35 part of sodium N-lauroylsarcosinate, and 0.1 part of sodium pyrophosphate were used. 35 parts, ferrous sulfate 0.0035 parts,
0.21 part of dextrose and 0.14 part of diisopropylbenzene hydroperoxide were charged. After purging with nitrogen, 70 parts of 1,3-butadiene was added, and the mixture was kept at 60 ° C. for 7 hours to obtain a latex.

Then, the obtained latex was transferred to a reaction vessel equipped with a reflux condenser, and further 60 parts of ion-exchanged water, 0.06 parts of potassium persulfate and 0.15 parts of sodium N-lauroyl sarcosinate were added thereto, and 55 The temperature was raised to ° C. Subsequently, a monomer mixture consisting of 24 parts of MMA, 6 parts of ST and 0.02 part of n-OM was continuously added over 90 minutes, and after the addition was completed, the mixture was maintained for 90 minutes to obtain a two-layer polymer latex.

(Production of hard polymer) In a reaction vessel equipped with a reflux condenser, 250 parts of ion-exchanged water, 2.5 parts of sodium stearate, 0.2 parts of sodium N-sarcosinate, MM
A40 parts, ST10 parts and n-OM 0.15 parts were charged. Then, 0.1 part of an aqueous potassium persulfate solution was added, and 8
The temperature was raised to 0 ° C. and maintained for 90 minutes.

Then, a 10% aqueous potassium persulfate solution (1.0%) was added.
Parts, MMA 47 parts, MA 3 parts, n-OM
A monomer mixture consisting of 0.15 parts was continuously added over 30 minutes, and after the completion of the addition, the mixture was maintained for 60 minutes to obtain a polymer latex.

(Removal of Polymer Composition and Evaluation) After mixing 30 parts of the obtained two-layer polymer latex and 70 parts of the hard polymer latex, the mixture was frozen under the conditions shown in Table 1. After thawing this frozen latex at 70 ° C,
The polymer was separated by filtration. Further, washing and dehydration were repeated three times with hot water at 70 ° C., followed by drying at 80 ° C. for 10 hours. Fusing and blocking did not occur, and a smooth coagulated product was obtained.

The obtained dried coagulated material was melt-kneaded at a cylinder temperature of 250 ° C. using a 40φ extruder to obtain pellets. At this time, surging hardly occurred, and the extrusion was stable. Using these pellets, cylinder temperature 250
Injection molding was performed at 50 ° C. and a mold temperature of 50 ° C. to obtain an Izod impact strength test piece based on ASTM standards and a 50 × 50 × 3 mm flat plate. Table 1 shows the results of evaluating various characteristics using this test piece. Comparative Example 3 Table 1 shows the results of the evaluation performed in the same manner as in Example 3 except that the latex mixture obtained in Example 3 was salted out and coagulated using a 2% aqueous magnesium sulfate solution. (Comparative Example 4) The latex mixture obtained in Example 3 was sprayed into a spray dryer having an inflow hot air temperature of 170 ° C to dry and separate the polymer. Table 1 shows the results of evaluation in the same manner as in Example 3 except for the above.

[0041]

[Table 1]

[0042]

According to the method for producing the coagulated polymer of the present invention and the composition thereof, the handleability in the drying step is remarkably improved, and the extrusion stability is also improved. Demonstrate superior effect. In addition, a molded product excellent in optical properties such as low thermal coloring and excellent in impact resistance can be obtained, so that the range of use is expanded.

Continuation of the front page (51) Int.Cl. ⁶ Identification symbol FI C08L 101/00 C08L 101/00 // (C08F 279/02 220: 10) (56) References JP-A-2-225510 (JP, A) JP-A-5-17514 (JP, A) JP-A-5-194680 (JP, A) JP-A-4-356502 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C08F 251/00-292/00 C08F 2/22 C08F 6/22

Claims (4)

(57) [Claims] The outermost layer comprises: (1) a hard layer having a glass transition temperature of 25 ° C. or more when polymerized alone; and at least one of the inner layers comprises: (2) at least one diene monomer 60 100 wt% greater than the weight percent, obtained by polymerizing a monomer mixture consisting of these with other copolymerizable monomers than 40 wt%, 25 ° C. when polymerized alone
A latex of a multilayer structure polymer, which is a soft layer having a glass transition temperature of less than, is produced by an emulsion polymerization method, and the latex is frozen at a rate of 4 cm / hr or less , melted, and dehydrated to obtain a multilayer structure weight from the latex. A method for producing a coagulated polymer, comprising removing the coalesced product. 2. The outermost layer is obtained by polymerizing a monomer mixture comprising 50 to 100% by weight of at least one methacrylate unit and 0 to 50% by weight of another monomer copolymerizable therewith. The method for producing a coagulated polymer according to claim 1, wherein the hard layer has a glass transition temperature of 25 ° C or more when polymerized alone. 3. A latex of a hard polymer having a glass transition temperature of 25 ° C. or more is produced by an emulsion polymerization method, and the latex is mixed with the latex of a multilayer structure polymer according to claim 1 or 2, and the mixture is mixed. Latex less than 4cm / hr
A method for producing a polymer coagulation composition, wherein a polymer composition comprising a hard polymer and a multilayer polymer is taken out of a mixed latex by freezing at a lower rate , melting and then dehydrating. 4. A hard polymer having a glass transition temperature of 25 ° C. or higher comprises 50 to 100% by weight of at least one methacrylate unit and 0 to 50% by weight of another monomer copolymerizable therewith. The method for producing a polymer coagulation composition according to claim 3, which is obtained by polymerizing a monomer mixture.