JPS59202213A - Production of impact-resistant acrylic polymer - Google Patents

Abstract

PURPOSE:To produce the titled polymer having excellent transparency, surface gloss, flow, moldability, and processability, by forming a methyl methacrylate copolymer and an alkyl acrylate copolymer by three-stage polymerization under specified conditions. CONSTITUTION:A first-stage rigid polymer of a Tg>=25 deg.C is obtained by emulsion-polymerizing a mixture of 80wt% or above methyl methacrylate, 20wt% or below another copolymerizable monomer (e.g., acrylic acid) and 5wt% or below still another copolymerizable polyfunctional grafting monomer (e.g., allyl acrylate). To this polymer is added a monomer mixture comprising 70-95wt% (1- 5C) alkyl acrylate and 5-30wt% copolymerizable monomer (e.g., styrene), and the polymerization for forming a second-stage flexible polymer of a Tg<=25 deg.C is started and, when the conversion reaches 60-90%, a monomer mixture containing 80wt% or above methyl methacrylate and 20wt% or below another copolymerizable monomer is added to form a third-stage rigid polymer of a Tg>=25 deg.C and a MW of 60,000-250,000.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides improved impact resistant acrylic polymers, more specifically, impact resistant acrylic polymers having excellent impact resistance, transparency and weather resistance; The present invention relates to a method for producing a polyacrylic polymer.

Methacrylic resin has both a transparent and beautiful appearance and weather resistance, and is used for a variety of purposes by taking advantage of these properties. However, Metac 17.7y resin generally does not have sufficient impact strength, and there has been a strong demand for improvement.

Conventionally, various proposals have been made as methods for improving the impact resistance of methacrylic resins. The most common and effective method has been to introduce an elastic material that is rubber-like at room temperature into methacrylic resin, such as unsaturated comb-like elastic material whose main component is butadiene, butyl acrylate, A method has been adopted in which a saturated rubber-like elastic material containing 2-ethylhexyl acrylate as a main component is dispersed in the form of particles.

However, unsaturated rubber-like elastic material impairs the weather resistance, which is a characteristic of methacrylic resin, so in recent years, saturated rubber-like elastic material has been considered from the viewpoint of weather resistance. It has low physical properties and low graft polymerizability with the hard resin phase, resulting in problems such as poor appearance such as impact resistance, transparency, and gloss, as well as poor flow molding processability due to the high rubber content. Efforts have been made. For example, Japanese Patent Publication No. 55-27576 discloses that impact resistance can be improved without impairing transparency by blending a three-layer or multilayer polymer with a hard thermoplastic polymer. JP-A-51-129449, JP-A-53-58554
A resin composition is also known from Japanese Patent Publication No. 2003-120002, which has a structure having three layers and an intermediate layer having a concentration gradient that changes at a substantially constant rate between these layers, and which has improved stress whitening resistance against impact. Although these methods are certainly effective in improving stress whitening resistance, they are not satisfactory in terms of resistance (i?4) and flow molding processability.Kasata, JP-A-56-167712 The publication proposes improvements in impact resistance, surface gloss, etc. by having four layers and crosslinking each layer, but such a method results in a decrease in stress whitening resistance and is unsatisfactory. As a result of intensive research into imparting impact resistance while maintaining the original properties of methacrylic resin, the present inventors found that the above objective could be achieved by producing a three-stage polymer under specific polymerization conditions. We have discovered that this can be achieved and have come up with the present invention.

That is, the present invention is made of a methyl methacrylate polymer or a copolymer mainly composed of methyl methacrylate and has a Tg of 2.
In the presence of the first stage hard polymer having a temperature of 5°C or higher, Tg of a copolymer mainly composed of an acrylic acid alkyl ester
When polymerizing the second stage soft polymer whose temperature is 25°C or less,
When the polymerization rate reaches 60 to 90% by weight, a third stage hard polymer having a Tg of 25° C. or higher, which is made of a methyl methacrylate-based polymer or a copolymer mainly composed of methyl methacrylate, is started. By starting, there is a method for producing impact resistant acrylic polymers.

The impact-resistant acrylic polymer obtained by such a method has excellent impact resistance, transparency, surface gloss, and flow moldability.

The method for producing the impact-resistant acrylic polymer of the present invention is not particularly limited, but it is preferably carried out by an emulsion method.

The impact-resistant acrylic polymer of the present invention is polymerized in three stages as described above. The first stage hard polymer is a monopolymer of methyl methacrylate or a co-7-do polymer consisting mainly of methyl methacrylate, and has a Tg of 25° C. or higher. This copolymer mainly composed of methyl methacrylate contains 80 or more methyl methacrylate and 20 or more copolymerizable monomers.
It is preferable that the copolymer has a copolymerization of 5 monomers or less, and a polyfunctional graftable monomer is preferably added. Monomers copolymerizable with methyl methacrylate are not particularly limited, but include methacrylic acid alkyl esters in which the alkyl group has 2 to 4 carbon atoms, acrylic acid alkyl esters in which the alkyl group has 1 to 8 carbon atoms, and methacrylic acid. , acrylic acid, and acrylonitrile.
Seconds are used.

The polyfunctional graftable monomers that can be combined are monomers having double bonds with different reactivities, such as allyl methacrylate, allyl acrylate, allyl maleate, and allyl methacrylate. Vinyl, vinyl acrylate, etc. are used, and if the amount added exceeds 5 monomers, the II;1 stress whitening property decreases, which is not preferable. The glass transition point (L'g) of this first stage hard polymer is 25°C or higher, preferably 50°C or higher, and if Tg is lower than 25°C, stress whitening resistance and... decreases and 1l-f-1,
No.

The second stage soft polymer is an acrylic acid alkyl ester or less. This copolymer mainly composed of an acrylic acid alkyl ester is an acrylic acid alkyl nitride whose alkyl group has 1 to 8 carbon atoms.
At least one of butyl, acrylic 2-ethylhexyl
A monomer that can be copolymerized with Species 70-95 D@%, and it is necessary to improve transparency by matching the refractive index with a hard polymer mainly composed of methyl methacrylate, so at least styrene is used. 5 to 30 M of a mixture containing styrene or a derivative thereof, 0.1 to 15 of a copolymerizable polyfunctional crosslinking monomer, and a polyfunctional grafting monomer capable of copolymerization 5 Heavy open: Consists of φ or less. Copolymerizable polyfunctional crosslinking monomers have 2′
It is a monomer with a heavy bond, and includes ethylene glycol dimethacrylate + -11,4 butylene glycol dimethacrylate, triethylene glycol diacrylate, 1,
Bifunctional monomers such as 6-hegysandiol diacrylate, trifunctional monomers such as trimethylolpro-ξndriaacrylate, triallyl isocyanurate, and tetrafunctional monomers such as pentaerythritol tetraacrylate. Each can be used alone or with silk combination-C.

The second-stage eyelid polymer has an 'rg of 25°C or less, preferably 0°C or less; if it exceeds 25°C, the primary impact strength decreases, which is undesirable.

The three-stage hard wheel assembly is made of a methyl methacrylate homopolymer or a copolymer J mainly composed of methyl methacrylate, and has an rg of 25° C. or higher. This copolymer mainly composed of 69 methyl methacrylate may be a copolymer with a weight Z of less than 20 methyl methacrylate and other copolymerizable monomers. preference] 2,
When the amount of copolymerizable monomer exceeds 20M, transparency deteriorates. In fact, it is necessary to adjust the molecular weight of the third stage hard polymer using a chain transfer agent from the viewpoint of flow molding processability, and the molecule t1 is preferably in the range of 60,000 to 250,000, preferably 80,000 to 200,000. As a chain transfer agent, an alkylcarbontane, thioglycolic acid and its ester are used. If the molecular weight is less than 60,000, mechanical strength will decrease, and if it exceeds 250,000, flow molding processability will decrease.

The Tg of this third-stage hardened combination is 25° C. or higher, preferably 50° C. or higher, and if l11g is 25° C. or lower, the heat resistance decreases and it becomes undesirable.

Although the Ser ratio of each stage is not particularly limited, there is a sense of security that at least the third stage hard polymer forms the outermost layer alone.

When polymerizing the above-mentioned polymers in each stage, the polymerization of the second stage soft polymer was started when the first stage hard polymer was substantially completed, and the polymerization rate reached 60 to 90 polymers. At the time,
It is necessary to initiate polymerization of the third stage hard polymer.

In polymerizing the third stage hard polymer, it is preferable to feed the monomer mixture at a rate faster than the polymerization rate.

If the polymerization start point of the third-stage hard Jj polymer falls outside the above range of polymerization rate, significant impact resistance will not be observed. Therefore, in order to maintain impact resistance, a large amount of the soft 3+F polymer must be used. As a result, the flow molding processability and heat resistance inherent to methacrylic bamboo 4 resin deteriorate. Tg can be measured using a differential calorimeter or the like.

Since it is particularly clever to construct the aguacryl-based polymer of the present invention by emulsion Tl1f, the case by emulsion polymerization will be explained.

5jj Aigata # is 30-120℃, good location 50-10
It is 0°C.

It is necessary to select conditions such that no new particles are generated when weighting each stage, and for this purpose it is advantageous to use the so-called seed f method. Then, when carrying out the next stage of polymerization, it is necessary to add a new emulsifier to the emulsifier, or if it is necessary to add it, it is necessary to limit the addition to a range that does not generate new particles. The presence or absence of formation of particles can be easily determined using an electron microscope.

The emulsifier is not particularly limited as long as it is a commonly used emulsifier2), and examples of emulsifiers that can be used include long-chain alkyl carbon ry salts, sulfosuccinic acid alkyl ester salts, and alkylbenzene sulfonates.

The amount of the emulsifier to be used is such that the particle size when the second stage soft polymer of the impact-resistant acrylic polymer of the present invention is substantially completed is 500 to 4,000 particles, preferably 1,000 to 30 particles.
It is preferable to use the number so that there are 00 people.

It takes a lot of effort to specifically limit the type of initiator. It can also be used as a redox-initiated yarn resistant compound when mixed with salt. Dimension 3-1*'m;/CN ￥ide-ferrous, organic oxide 1-sodium formaldehyde sulfoxyl/
Redonx initiator yarns such as -g can also be used.

The polymer latex f, , j obtained by emulsion polymerization is coagulated, separated, and dried by known methods.

The uninvented multi-stage aggregate compacted product can be made into pellets and then injection molded or bone molded using clay to obtain the desired molded product for PJT.

1, or you can make friends with the commonly used acrylic resin molding materials and make 1 different product per month. Is this the master's self?
1) The case is selected as appropriate depending on the purpose of use.

Friendly acrylic Y body molding materials can be obtained by any method such as Kimiya [polymerization method f of 1], examples include bulk polymerization method, suspended S1 surface method, emulsion polymerization method, and solution FIF method. It may also be carried out by a commonly used method such as blending (d-melting 7I-7).

In addition to resins, conventional additives such as ultraviolet absorbers, antioxidants, fillers, dyes and pigments can be added as necessary.

Like this! -1 The resulting composition has good flow processability, and the molded product obtained by injection molding using an extrusion molding machine has transparency, il+-f impact strength, and surface 1. It has a weatherability of 1.v.

Next, the present invention will be explained in more detail using 11 examples. In fact, in one example, the surface impact resistance was measured by measuring the notched isot strength according to ASTM D256 using a specimen obtained by injection molding. Flow molding processability is A S 'I'
MI) 230℃ by 1238 3.8 K9 trace 1
(hereinafter abbreviated as MI). The molecular weight was determined from the intrinsic viscosity measured at 25° C. in chloroform solvent. The haze value is lll by A8T'MD 1003! II was determined.

-1. In the examples, the part or part indicates the heavy covering part or weight %.

Example 1 Ion exchange iK 6 in a reaction vessel with an Oe rapid flow condenser
ooog1y hexylsurnekohaku+Fsu)lJum1
The temperature was raised to 70°C under a nitrogen stream while stirring at a rotational speed of 2 sorpm, and 4 g of potassium persulfate was added, and after stirring, methyl methacrylate ( MMA) 760g1 methacrylic acid alinoy ALMA)
The monolithic mixture consisting of 1 g was added continuously over a period of 60 minutes and held for an additional 20 minutes after the addition was complete.

The polymerization rate +d at this time was 98.5%.

Subsequently, a monomer mixture consisting of 840 g of loobyl acrylate (BA), 22 parts g of styrene (sT), 8 g of t,a butylene glycol diacrylate, and 4 g of ALMA was continuously added over 90 minutes, and after the addition was completed, a further 70 g of styrene (sT) was added. MMA 320g, f(
A 2 g, low octyl mercaptan (n-OM)
0.8 g of #L polymer 711'' compound was added continuously over 20 minutes, the addition was maintained at 1. J' grade for 60 minutes, and the temperature was raised to 95° C. to complete the polymerization.

When the polymerization of the second beam H was held for 70 minutes, the '+1c percentage of the second stage +1 was 75%, and the polymerization rate of the polymerized latex A3 of the completed latex was 99 parts H or more.

The obtained latex was poured into an aqueous solution of 0.5% aluminum chloride to coagulate the polymer, followed by repeated dehydration, washing with water, and drying to obtain a three-stage polymer powder.

M was produced by ordinary suspension polymerization with 30 parts of the polymer powder.
A granular copolymer (molecular weight 1
(10000) 70 parts of the blended resin was IHJ mixed for 20 minutes using a Henschel mixer, and then extruded into a 40mm φ vented f4'1-i141 i-+ (M made by Nippon Kogo) "4O-30AB-y 4H. L/l)=:(0)
Pelletization was performed at 240°C using &. The helet was molded using an in-line screw injection molding machine (Toshiba Machine 15).
-758 type) at a molding temperature of 250°C and an injection pressure of 90°C.
A test piece was prepared under the conditions of 0 Kqr/J and a mold temperature of 50°C, and the physical properties were measured. Table 1 shows the results. It had good flow moldability, transparency, and gloss, and had excellent weather resistance.

Example 2 Copolymer composition: MMkg6%, methyl acrylate (
Table 1 shows the results of evaluation carried out in exactly the same manner as in Example 1 except that a blend resin consisting of MA) 4chi (molecular weight 120,000) was used.

Example 3 29,000 g of ion-exchanged water and 50 g of sodium dihexylsulfoconophosphate were placed in a stainless steel reaction vessel with contents F4501, and the temperature was raised to 70°C under a nitrogen stream while stirring at a rotation speed of 150 rpm to eliminate the influence of oxygen. After adding 2 OR of potassium persulfate, 3600 g of MMA
, 60 g of BA and 6 g of SALMA were added continuously over 60 minutes and held for an additional 60 minutes after the addition was complete. The polymerization rate at this time was 985%.

Add log potassium persulfate followed by BA 4060g1
ST 1060g, triallyl incyanurate 50g
A monomer mixture consisting of 20 g of ALMA and 20 g of ALMA was added continuously over 100 minutes, and after the addition was completed, the monomer mixture was kept for an additional 45 minutes to form a mixture of 4860 g of MMA, 540 g of BA, and n-0M.
16 g of a monomer mixture of F41 was continuously added over 90 minutes, and after the addition was completed, the mixture was maintained for 60 minutes and the temperature was raised to 95° C. to complete the polymerization.

2nd stage] I3: The polymerization rate in the second stage after holding the reaction for 45 minutes was 65 degrees, and the polymerization rate of the latex when the polymerization was completed was 99.5 parts or more.

40 parts of polymer powder obtained by the same treatment as in Example 1 and 6 parts of a blend resin (molecular weight 1oooooo) consisting of 98% MMA and 2% MA as a copolymer composition were evaluated in the same manner as in Example 1. The results are shown in Table 1.

The flow molding processability, transparency, gloss and 1fij weatherability were also excellent.

Comparative Example 1 Polymerization and test pieces were carried out in the same manner as in Example 3, except that the holding time in the second stage was changed to 10 minutes and the addition of the monomer mixture in the third stage was started. The results of the evaluation are shown in Table 1.

In the second stage polymerization, the polymerization rate in the second stage after holding for 10 minutes was 50%, and the polymerization rate of the polymerized and bonded latex was 99.5 parts or more.・Both transparency was poor.

Comparative Example 2 A test piece was produced and evaluated in the same manner as in Comparative Example 1, except that 80 parts of the multistage polymer of Comparative Example 1 and 40 parts of the blend resin were used, and the evaluation results are shown in Table 1. Although the impact resistance was satisfactory, the flow molding processability was significantly inferior.

(Left below) Example 4 Using the same method as in Example 1, a tetramer mixture consisting of 846 g of MMA and 94 g of MA was added continuously over a period of 60 minutes as the first stage monomer mixture, and the addition was completed. After that, it was held for an additional 60 minutes. The polymerization rate of this erection was 99.

Subsequently, 32 g of nA1o, 258 g of ST, 13 g of tetraethylene glycol diacrylate and ALMA
A monomer mixture consisting of 5 g was added continuously over 80 minutes, and after cooling was completed, the monomer mixture was kept for an additional 90 minutes.
A monomer mixture consisting of 6 g parts of 0g% BA and 8 parts of n-OMl was continuously added over 30 minutes, and after the addition was completed, the mixture was held for 60 minutes and the temperature was raised to 95° C. to complete the polymerization.

When the second stage polymerization was held for 90 minutes, the second stage polymerization ratio was 859 IS, and the polymerization ratio of the latex that was polymerized to completion was 99.5% or more.

The obtained latex was treated in the same manner as in Example 1 to obtain a polymer powder.

After blending 33 parts of the polymer powder with 67 parts of a copolymer (molecular weight 100,000) consisting of 90% MMA and 10% ethyl acrylate, the same evaluation as in Example 1 was performed, and the results are shown in Table 2.

It had good moldability, transparency, and gloss, and had excellent weather resistance.

Comparative Example 3 In the chassis of Example 4, the holding time of the second stage bundling was 10
Example 4 except that the third stage polymerization was started at 0 minutes.
Table 2 shows the results of manufacturing and evaluating test pieces in exactly the same manner as above.

The L collation rate of the second stage was 4% at the time of starting the first go of the third stage.

The impact resistance of the molded product was significantly reduced and was dull.

Comparative Example 4 A test piece was produced in the same manner as in Comparative Example 3, except that 70 parts of the multistage polymer of Comparative Example 3 and 30 parts of blended wood were used. Table 2 shows the results of the evaluation. Although it had 11it impact resistance, the flow moldability was significantly reduced.

Example 5 Using the same polymerization method as in Example 3, a first-stage monomer mixture consisting of 2560 g of MMA and 50 g of BA was continuously added over 110 minutes, and after the addition was completed, a monomer mixture was added for an additional 60 minutes. held. The vehicle ratio at this time was 99. Next, BA6700g, S'r1675g,
1.6 hexanediol diacrylate 65,,
, A monomer mixture consisting of 35 g of ALMA was added continuously over 90 minutes, and after the addition was completed, the monomer mixture was kept for an additional 140 minutes to give 4410 g of M M A, 35 g of BA, 35 g1n-0 M13
A monomer mixture consisting of g was added continuously over 60 minutes, and after the addition was completed, it was held for 60 minutes, and the temperature was raised to 95 ° C to complete one part.0 In the second stage polymerization, it was held for 1 tlLo. The polymerization rate of the second stage at that time was 80%, and the polymerization rate of the completed latex was 99.5% or more.

The obtained latex was treated in the same manner as in Example 1 to obtain a polymer powder.

28 parts of the polymer powder and 95 parts of MMA. After blending 72 parts of a copolymer (molecular weight 150,000) consisting of 5% MA and 5% MA, the same evaluation as in Example 1 was conducted.
Shown in 2.

However, it had good dynamic molding processability, transparency, and gloss, and was 14" superior in weather resistance.

(Margin below)

Claims (1)

[Claims] (Re) From a copolymer mainly composed of acrylic acid alkyl ester in the presence of a first stage hard polymer having a Tg of 25°C or higher, which is composed of a methyl methacrylate homopolymer or a copolymer mainly composed of methyl methacrylate. When polymerizing the second stage soft polymer whose Tg is 25°C or less, the polymerization rate is 6.
When the weight ratio reaches 0 to 90, start the polymerization of a third stage hard polymer having a Tg of 25 ° C. or higher, which is made of a methyl methacrylate homopolymer or a copolymer mainly composed of methyl methacrylate. Manufacturing method of featured impact-resistant acrylic polymer