KR20030068802A - Transparent impact-resistant styrene resin composition - Google Patents

Abstract

The present invention is an impact resistant styrene resin composition obtained by continuous bulk polymerization of a styrene monomer (a1), an alkyl (meth) acrylic acid alkyl ester (a2), and a styrene butadiene block copolymer (b), wherein the block copolymer (b) Forming particles, copolymer (A) of styrene monomer (a1) and (meth) acrylic acid alkyl ester (a2) forms a matrix, and Z average molecular weight Mz of the copolymer (A) is 22x10. ^It is 4-28 * 10 <^4> , the average particle diameter of the said rubbery particle is 0.3-2.0 micrometers, and the content rate of the polymer block of butadiene in the said composition is 2.0-7.5 mass%, The transparent impact resistant styrene resin composition characterized by the above-mentioned. To provide.

Description

Transparent impact-resistant styrene resin composition {TRANSPARENT IMPACT-RESISTANT STYRENE RESIN COMPOSITION}

The present invention relates to a transparent impact resistant styrene resin composition having not only excellent moldability and transparency but also excellent balance of impact resistance and rigidity and useful for film or sheet applications. That is, the transparent styrene-based resin composition of the present invention not only has good moldability but also has a very good balance of impact resistance and rigidity as a sheet molded product, such as food packaging trays, cover materials, cups, various storage trays, carrier tapes, and the like. Very useful for use.

Conventionally, a tray made of a polystyrene biaxially oriented sheet is often used for a tray such as a plastic container, but these are fragile due to poor impact resistance, and are easily cut off at the edge of the container. I) There was a problem.

So, for example, as a resin having both transparency and impact resistance, Patent No. 314881 discloses a rubbery elastomer as a dispersed particle, and a styrene monomer in which a styrene monomer and a (meth) acrylic acid ester monomer are graft-polymerized. The rubber modified styrene resin composition which makes the copolymer of and a (meth) acrylic acid ester monomer a continuous phase is disclosed.

However, the rubber-modified styrene-based resin composition disclosed in the above-mentioned Patent No. 314881 1 has good transparency and excellent practical strength represented by impact resistance, particularly fall impact strength, but for example, a container cover of a sheet molded article In applications requiring a strong elasticity such as a material, the rigidity is not sufficient, and there are practical drawbacks such as denaturation caused by the load from the upper part of the container. Moreover, also in transparency, it was not enough level as a sheet molding.

The problem to be solved by the present invention is to provide a transparent impact-resistant styrene resin composition and a method of manufacturing the same, which is excellent in balance of impact resistance and rigidity and has good transparency.

BRIEF DESCRIPTION OF THE DRAWINGS It is process drawing which shows an example of the continuous block polymerization line which combined the tubular reactor which has a static mixing element.

[Explanation of Significant Symbols in Drawings]

(1): plunger pump, (2): stirred reactor, (3): gear pump, (4), (5), (6): tubular reactor with static mixing element, (7): Gear pump, (8), (9), (10): tubular reactor with static mixing element, (I): circulating polymerization line, (II): acyclic polymerization line

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in order to solve the said subject, as a result, it is a transparent impact resistant styrene resin composition which consists of a matrix and rubber-like particle | grains dispersed in the matrix, The said matrix is a styrene-type monomer (a1) and (meth A resin composition comprising a copolymer (A) of an alkyl acrylate ester (a2), wherein the rubbery particles are composed of a styrene-butadiene block copolymer (b), and the molecular weight of the resin forming the matrix is high, and the particle size of the rubbery particles By adjusting the content of butadiene polymer structure in the range and the composition to a specific range, it has been found that excellent transparency can be expressed, and the balance between impact resistance and rigidity can be remarkably improved and the present invention has been completed.

That is, the present invention is a transparent impact resistant styrene resin composition comprising a matrix and rubber particles dispersed in the matrix, wherein the matrix is a copolymer of styrene monomer (a1) and (meth) acrylic acid alkyl ester (a2). ), The rubbery particles are made of styrene-butadiene block copolymer (b),

Z average molecular weight Mz of the said copolymer (A) is 22 * 10 <^4> -28 * 10 <^4> ,

The average particle diameter of the said rubbery particle is 0.3-2.0 micrometers, and

The content rate of the polymer block of butadiene in the said composition is 2.0-7.5 mass%, It is related with the transparent impact resistant styrene resin composition.

[Embodiment of the Invention]

As described above, the transparent styrene resin composition of the present invention has a matrix composed of a copolymer (A) of a styrene monomer (a1) and an alkyl ester of (meth) acrylic acid (a2), and the rubbery particles of styrene butadiene. It is comprised from a block copolymer (b).

That is, the copolymer (A) forms a continuous phase in the composition, and the rubbery particles exist as a dispersed phase. In the rubbery particles, the styrene-butadiene block copolymer (b) forms particles, and specifically, the styrene-based monomer (a1) and the allyl group present in the styrene-butadiene block copolymer (b) on the particle surface thereof. It is preferable that (meth) acrylic-acid alkylester (a2) has the graft copolymerized part from the point of dispersibility and impact resistance. In this case, the graft copolymerization portion on the particle surface of the rubbery dispersed particles is a copolymer of styrene monomer (a1) and alkyl (meth) acrylic acid ester (a2) having a linear structure and intertwined with the matrix. .

In the present invention, the matrix is composed of a copolymer (A) of a styrene monomer (a1) and an alkyl ester of (meth) acrylic acid (a2), whereby the molded article can be provided with excellent transparency and rigidity. Moreover, in this invention, Z average molecular weight Mz of copolymer (A) is characterized by being 22x10 <^4> -28 * 10 <^4> . This molecular weight range is a high molecular weight which is not conventional in the technical field of the transparent impact-resistant styrene resin composition which uses what is called a styrene-acrylic-acid alkylester copolymer as a matrix. By making the molecular weight of such a copolymer (A) into a high molecular weight region, the rigidity of a molded article is remarkably improved.

In addition, the average particle diameter of the granular part of the styrene-butadiene block copolymer (b) dispersed in the said matrix is 0.3-2.0 micrometers. By setting the average particle diameter in such a range, excellent impact resistance can be expressed in the molded article thereof.

Moreover, the composition of this invention is the range whose content rate of the butadiene polymer structure in a composition is 2.0-7.5 mass%. Such a range is a low region as the transparent impact resistant styrene resin composition, and by providing such a numerical range, the rigidity of the molded article can be increased significantly. Moreover, although this invention combines rigidity and impact resistance, although the content rate of the butadiene polymer structure as a rubber component is comparatively small, it is especially worth mentioning that the outstanding impact resistance is expressed.

That is, the composition of the present invention can be provided with such a variety of conditions together with transparency, impact resistance and rigidity that have not been realized as a sheet molded article.

The compositions of the present invention in that the performance balance has to be particularly satisfactory is a Z average molecular weight Mz of the copolymer ^{(A) 22 × 10 4 ~28} × 10 4 , and the average particle size of the rubber-like particles 0.3~1.0㎛, Moreover, it is especially preferable that the content rate of the polymer block of butadiene in the said composition is 2.0-7.5 mass%.

In addition, the content rate of the polymer block of butadiene in a composition here is the content rate of the mass reference | standard calculated from the relative intensity of the peak resulting from polystyrene and the peak resulting from polybutadiene by IR measurement.

The composition of the present invention can significantly increase the rigidity of a molded article while having excellent impact resistance. As a result, the composition can have both rigidity and impact resistance. In view of this, the swelling index due to toluene at 25 ° C of the rubbery particles in the composition is 8 to 19, and the ratio of the content of toluene insoluble component at 25 ° C of the whole composition to the swelling index is shown. It is preferable that (toluene insoluble component content rate / swelling index) is 0.2-0.8.

In addition, the toluene insoluble component content rate and swelling index by toluene mentioned in this invention are measured as follows.

[Measurement method of content of toluene insoluble component and swelling index by toluene]

1 g of rubber-modified copolymer resin is precisely weighed, dissolved in 100 ml of toluene at 25 ° C. for 24 hours, and then the solution is transferred to a centrifuge tube and centrifuged at 8500 rpm for 10 minutes or less, followed by supernatant solution (上 澄 液). ) Is removed by decantation, and then the weight of the insoluble component swollen with toluene is measured. Next, the weight of the toluene insoluble component obtained by drying in a 60 degreeC vacuum dryer for 24 hours is measured, and a toluene insoluble component content rate (%) is computed by the following formula | equation.

Toluene insoluble component content rate (%) = (weight of toluene insoluble component) / (weight of resin) x100

In addition, a swelling index is computed by following Formula.

Swelling index = (weight of swelled toluene insoluble component) / (weight of toluene insoluble component after drying)

Next, as a styrene monomer (a1) which comprises the said graft copolymerization part in the particle surface of a copolymer (A) and rubbery particle | grains, for example, styrene, (alpha) -methylstyrene, o-methylstyrene, m Methyl styrene, p-methyl styrene, ethyl styrene, isobutyl styrene, t-butyl styrene, o-bromostyrene, m-bromostyrene, p-bromostyrene, o-chlorostyrene, m-chlorostyrene, p -Chloro styrene, etc. are mentioned. Among these, styrene is preferable for reasons such as good reactivity and easy polymerization.

Moreover, as (meth) acrylic-acid alkylester (a2) which comprises the said graft copolymerization part in the particle surface of a copolymer (A) and rubbery particle | grains, methyl methacrylate, ethyl methacrylate, meta, for example. And acrylic esters such as alkyl methacrylates such as propyl methacrylate and butyl methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate and 2-ethylhexyl acrylate. Among these, methyl methacrylate is preferable at the point which the effect of rigidity improvement of a molded article is large. Moreover, it is preferable to use together methyl methacrylate and butyl acrylate at the time of superposition | polymerization from the point of transparency and impact resistance of a molded article.

It is preferable that a copolymer (A) contains a styrene structural unit in the ratio used as 30 to 60%. That is, in the range of 30% or more, the fluidity | liquidity at the time of melting of a composition becomes favorable, and it is excellent in moldability, and when it is 60% or less, the quantity of the acrylic component resulting from (a2) becomes relatively high, and the rigidity and chemical-resistance of a molded article It is excellent.

Further, the copolymer (A) is a Z average molecular weight Mz is 22 × 10 ⁴ ~28 × 10 ⁴ in components (hereinafter referred to as low as reducing "component (A1)") and, Z average molecular weight Mz is 23 × 10 ⁴ ~29 It is particularly preferable to contain a component having a size of 10 ⁴ (hereinafter, referred to as "component (A2)") in terms of the rigidity of the sheet molded article, and in particular, the component (A1) has a Z average molecular weight Mz in terms of balance with impact resistance. Is in the range of 20 × 10 ^{4 to} 21.8 × 10 ⁴ , and the component (A2) preferably has a Z average molecular weight Mz of 23.5 × 10 ^{4 to} 29 × 10 ⁴ .

Moreover, it is preferable that the abundance ratio of a component (A1) and a component (A2) is the ratio of (A1) / (A2) = 85 / 15-30 / 70 by mass basis from a point of a rigidity improvement effect.

Moreover, it is preferable that the content rate of the styrene structural unit content of a component (A1), and the content rate of the styrene structural unit of a component (A2) becomes 30 to 60% in the point of transparency of a sheet molded article from the point of rigidity and impact resistance of a molded article. Do. In terms of transparency, the styrene structural unit content of the component (A2) is preferably 0.8 to 1.2 times the styrene structural unit content of the component (A1).

Next, the styrene butadiene block copolymer (b) constituting the rubber particles is a copolymer of a styrene monomer and a diene monomer. Examples of the styrene monomer include various monomers exemplified as the styrene monomer (a1). . In particular, styrene is preferable. In addition, butadiene, chloroprene, isoprene, 1,3-pentadiene, etc. are mentioned as diene monomer, Butadiene is preferable at the point which is excellent in reactivity with a styrene monomer.

It is preferable that the content rate of the styrene structural unit in the styrene butadiene block copolymer (b) is 33 to 55% in view of the balance between impact strength and transparency. In the range of 55% or less, the butadiene block content becomes relatively high, and the molded article excellent in impact resistance is obtained. Moreover, in 33% or more of range, viscosity adjustment with a matrix becomes easy as melt flow property of a styrene-butadiene block copolymer (b) improves, and the balance of the fluidity | liquidity at the time of melting of a composition, and the heat resistance of a molded article becomes favorable.

The styrene-butadiene block copolymer (b) also has a styrene-based monomer (a1) and a (meth) acrylic acid alkyl ester on the particle surface of 14 to 35% of the 1,2-vinyl bond in the unsaturated bond based on butadiene. It is preferable because the balance between the graft ratio in a2) and the graft copolymerization portion and the degree of crosslinking of the rubbery particles become good and the impact resistance is improved. In this case, the rest of the 1,2-vinyl bonds form cis and trans bonds.

In terms of transparency, the styrene structural unit in the copolymer (A) is contained in a proportion of 30 to 60%, and the styrene structural unit content of the styrene butadiene block copolymer (b) is particularly preferably 33 to 55%. Do.

Next, the average particle diameter of the rubbery particles is 0.3 to 2.0 µm, preferably 0.4 to 1.0 µm, and the average particle diameter is measured as the median diameter by a laser diffraction scattering particle size analyzer LA-910. Value.

Moreover, although the form of rubber-like particle | grains is not specifically limited, It is preferable that it is any one of a core shell structure, an onion structure, and a salami structure from an impact resistant point. Especially, it is preferable to have onion structure from the point which is excellent in impact resistance.

Such a transparent impact resistant styrene resin composition has excellent impact resistance and rigidity as described above. Specifically, the impact resistance is more than 0.50 J as the DuPont impact strength in a sheet having a thickness of 0.4 mm, and the rigidity is in accordance with JIS K 7203. The modulus of elasticity is 2600 MPa or more.

The transparent impact resistant styrene resin composition described in detail above is not particularly specified in the production method, and can be produced by a batch polymerization method, a continuous polymerization method, or the like. It is preferable at the point which adjustment is easy.

That is, as a specific manufacturing method, the process (process 1) of superposing | polymerizing a styrene-type monomer (a1), the (meth) acrylic-acid alkylester (a2), and a styrene-butadiene block copolymer (b) to obtain a composition, and then Z average molecular weight Mz is A copolymer of a styrene monomer (a1) of 23 × 10 ^{4 to} 29 × 10 ⁴ and a (meth) acrylic acid alkyl ester (a2) (hereinafter, referred to as “copolymer (A2)”) is mixed. (Step 2) A method is mentioned.

In the said manufacturing method, the composition obtained by the process 1 consists of a matrix and rubber-like particle | grains disperse | distributed in the matrix, The said matrix is a styrene-type monomer (a1) whose Z average molecular weight Mz is 20 * 10 <^4> -22.5 * 10 <^4> and It consists of a copolymer of (meth) acrylic-acid alkylester (a2) (Hereinafter, this copolymer is abbreviated as "copolymer (A1)."), And rubber-like particle | grains consist of styrene-butadiene block copolymer (b). .

In addition, copolymer (A1) and copolymer (A2) are mixed to obtain the copolymer (A). That is, copolymer (A1) corresponds to component (A1) in copolymer (A), and copolymer (A2) corresponds to component (A2) in copolymer (A).

Step 1 is a bulk-suspension polymerization, solution polymerization of styrene monomer (a1), alkyl (meth) acrylic acid alkyl ester (a2), styrene butadiene block copolymer (b) and other copolymerizable monomers as necessary. It is a process of graft copolymerization by block polymerization.

Here, the ratio of the styrene monomer (a1), the (meth) acrylic acid alkyl ester (a2), and the styrene butadiene block copolymer (b) to be used is based on the rigidity of the molded article, the transparency and the fluidity at the time of melting the composition of the present invention. It is preferable that the mass ratio of the styrene-based monomer (a1) and the (meth) acrylic acid alkyl ester (a2), ie, (a1) / (a2), ranges from 30/70 to 60-40 from an excellent point. Moreover, when the use ratio of the styrene-butadiene block copolymer (b) is too small, rubbery particle will become fine and it will not be able to express impact resistance. In order to express impact resistance, the rubbery particles should have an appropriate particle size, and the preferred rubbery particles are those having a particle diameter capable of forming a core shell structure, an onion structure, and a salami structure, and for this purpose, a styrene-butadiene block copolymer (b ) Is preferably a ratio of 7 to 18% by mass in the raw material components. In the finally obtained composition, it is preferable to increase the particle diameter of the dispersed particles as described above in terms of impact resistance, while in terms of rigidity, it is preferable to reduce the amount of rubbery particles and to increase the molecular weight of the matrix. It is preferable that the usage-amount of the styrene-butadiene block copolymer (b) of the process 1 is 10 to 14 mass% in a raw material component from the point which aims at these performance balances.

Moreover, when (meth) acrylic acid ester (a2) consists of methyl acrylate and butyl (meth) acrylate, it is a thing in which (meth) acrylic acid is a range which becomes 1-5 mass% in (meth) acrylic acid ester (a2). It is preferable at the point of transparency, the impact resistance improvement effect, and the heat resistance of a molded article.

As a specific method of graft copolymerization, continuous block polymerization method is preferable especially from the point of productivity, cost, and the uniformity of a composition.

The continuous bulk polymerization method is a method of continuous bulk polymerization using a continuous bulk polymerization line in which a plurality of tubular reactors in which a plurality of mixing elements having no movable parts are fixed inside are connected. It is preferable from the point that not only the dispersibility of the resin can be improved, but also the particle size can be increased uniformly and easily, and an appropriate graft ratio can be realized. Moreover, after melt | dissolving each raw material component, it is preferable to superpose | polymerize by one or more stirring reactors, and to introduce | transduce into the said continuous block polymerization line, and to perform continuous block polymerization.

Here, it is preferable to use it as a continuous polymerization line which connected the continuous bulk polymerization line which connected two or more stirring reactors and the tubular reactor in which the several mixing element which does not have a movable part fixed inside, and as such a continuous polymerization line, For example, a. Stirred reactor, b. An initial polymerization line consisting of one or more tubular reactors fixed therein with a plurality of mixing elements continuously free of moving parts from the stirred reactor, c. A main polymerization line consisting of at least one tubular reactor in which a plurality of mixing elements having no moving parts in series from the initial polymerization line are fixed therein, and d. It is especially preferable that it is a polymerization line comprised by the reflux line which splits between an initial polymerization line and a main polymerization line, and returns to an initial polymerization line.

In addition, as a mixing element used here, what mixes a polymerization liquid by changing the division | segmentation and flow direction of the flow of the polymerization liquid which flowed into the pipe | tube, and repeating division and joining is mentioned, for example. As such a tubular reactor, an SMX type, an SMR type lower type tubular mixer, a Kenny type static mixer, a Toray type tubular mixer, etc. are mentioned, for example.

Hereinafter, the polymerization method of step 1 using such a continuous bulk polymerization line will be described according to the process diagram of FIG. 1.

The raw material components are first sent to the stirred reactor 2 by the plunger pump 1 and then subjected to initial graft polymerization under stirring, and then to the tubular reactor 4 having a static mixing element by the gear pump 3. , 5, 6 and to the circulating polymerization line (I) with the gear pump (7).

The initial graft polymerization in the stirred reactor (2) is such that the total polymerization conversion rate of the styrene monomer (a1) and the (meth) acrylic acid alkyl ester (a2) is 10 to 28% by weight at the outlet of the reactor (2), preferably It is preferable to carry out until it becomes 14 to 24 weight%. Moreover, as a stirring reactor 2, a stirring vessel-type reactor, a stirring tower reactor, etc. are mentioned, for example, As stirring blades, stirring blades, such as an anchor type, a turbine type, a screw type, a double spiral, etc., are mentioned, for example. Can be mentioned.

Next, the polymerization proceeds while the polymerization liquid is circulated in the circulation polymerization line (I), and a part of the polymerization liquid is transferred to the next acyclic polymerization line (II). Here, the ratio of the flow rate of the polymerization liquid circulating in the circulation polymerization line (I) and the flow rate of the polymerization liquid flowing out to the acyclic polymerization line (II), that is, the reflux ratio R, does not flow out to the acyclic polymerization line (II) but When the flow rate of the mixed solution refluxing in (I) is called F1 (liters / hour) and the flow rate of the mixed solution flowing out from the circulating polymerization line (I) to the acyclic polymerization line (II) is F2 (liters / hour). In general, R = F1 / F2 is preferably in the range of 3 to 15.

As for graft polymerization in the said cyclic polymerization line (I), the total polymerization conversion ratio of the styrene monomer (a1) and the (meth) acrylic-acid alkylester (a2) at the exit of the said cyclic polymerization line (I) is 35-55 mass% normally. Preferably, the polymerization is carried out to 40 to 50% by mass. As for polymerization temperature, 120-135 degreeC is suitable.

The polymerization temperature in the non-cyclic polymerization line (II) is 140-160 degreeC normally, and is continuously graft-polymerized until it becomes 60-85 mass% of polymerization conversion rates.

Next, the mixed solution is transferred to a preheater, followed by a devolatilization tank by a gear pump (II) to remove unreacted monomers and solvents under reduced pressure, and then pelletized to obtain the desired composition.

In the process 1, in order to reduce the viscosity of the said mixed solution in a reactor, you may use a solvent, and the usage-amount is 5-20 mass parts with respect to 100 mass parts of total raw material monomers. As a kind of solvent, toluene, ethylbenzene, xylene, etc. which are normally used by the bulk polymerization method are suitable.

In addition, since the particle size of the dispersoid in the composition obtained is adjusted to an appropriate range at the process 1, it is preferable to add a chain transfer agent for molecular weight control of a matrix. The addition amount of this chain transfer agent is the range of 0.005-0.5 weight part normally with respect to a total of 100 weight part of a raw material monomer.

Moreover, in the superposition | polymerization of process 1, an appropriate polymerization initiator can be used. Examples of the polymerization initiator include 1,1-bis (t-butylperoxy) cyclohexane, 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, 2,2-bis (t -Butyl peroxy) butane, n-butyl-4,4-bis (t-butylperoxy) valerate, t-butylperoxy acetate, t-butylperoxy-3,3,5-trimethylhexanoate, t-butylperoxylaurate, t-butylperoxybenzoate,

Bis (t-butylperoxy) isophthalate, 2,5-dimethyl-2,5-bis (benzoylperoxy) hexane, t-butylperoxymaleic acid, t-butylperoxyisopropylmonocarbonate, di-t -Butyl peroxide, dicumyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, etc. are mentioned.

In the composition thus obtained, the matrix is composed of the copolymer (A) of the component (A1), and the rubbery particles dispersed in the matrix are composed of the styrene-butadiene block copolymer (b).

In addition, the melt flow rate of the composition obtained in Step 1 is not particularly limited. However, if the melt flow rate is too low, the molding processability of the transparent impact resistant styrene resin composition for the final purpose is poor, and if the melt flow rate is too high, Since draw down is easy, it is preferable that melt flow rate (MFR) is 1-10 g / 10min with melt flow rate measured by the temperature of 200 degreeC and load 5Kgf based on JISK7210. More preferably, it is 1-2.5 g / 10min from a drawdown characteristic.

Next, step 2 is to mix the copolymer (A2) with the composition obtained in step 1.

In the present invention, by mixing a copolymer having a monomer composition equivalent to the matrix in the composition obtained in step 1 and having a high molecular weight, the rigidity when the sheet molded article is made, in particular, can be remarkably improved, and the molded article has excellent transparency. It becomes.

It is preferable that the copolymer (A2) used here is 0.8-1.2 times the styrene structural unit content rate with respect to the copolymer (A1). By setting it as such a range, transparency of a molded article will become very favorable.

In the case of polymerization of the copolymer (A2), when (meth) acrylic acid ester (b2) is used in combination of methyl methacrylate and butyl (meth) acrylate, (meth) acrylate is in (meth) acrylic acid ester (b2). It is preferable that it is the range which becomes 1-5 mass% from the point of the fluidity | liquidity at the time of melting of a composition, and the drawdown prevention property of a sheet molding.

Such a copolymer (A2) may be made by graft copolymerization of styrene monomer (a1) and (meth) acrylic acid alkyl ester (a2) by block-suspension polymerization, solution polymerization or block polymerization. In the case of such polymerization, an organic solvent can be added to a polymerization raw material as needed. Examples of the organic solvent include ethylbenzene, toluene, xylene, acetone, isopropylbenzene, methyl ethyl ketone, hexane, and the like, and in particular, use of ethyl benzene and toluene is preferable.

Although it does not specifically limit as a method of mixing the composition and copolymer (A2) obtained at the process 1 in process 2, It is preferable to perform by melt blending from the point of uniformity of a composition. Specifically, a method of mixing the two by heating and melting may be mentioned. For example, pellets or pearls of the composition and copolymer (A2) obtained in Step 1 may be melt-blended at 200 to 240 ° C. with an extruder and left as is. It may be made into a sheet, and may be melted into an extruder after pelletizing once.

What is necessary is just to graft copolymerize the styrene-type monomer (a1) and the (meth) acrylic-acid alkylester (a2) by block-suspension polymerization, solution polymerization, or block polymerization for the copolymer (A2) used at the process 2. At the time of this superposition | polymerization, an organic solvent can be added to a superposition | polymerization raw material as needed. Examples of the organic solvent include ethylbenzene, toluene, xylene, acetone, isopropylbenzene, methyl ethyl ketone, hexane, and the like, and in particular, use of ethyl benzene and toluene is preferable.

Next, it is preferable to mix the ratio obtained by mixing the composition obtained in Step 1 with the copolymer (A2) in a ratio of composition / copolymer (A2) = 50/50 to 90/10 on a mass basis, for example. However, it is necessary to mix so that the content rate of the polybutadiene structure site | part of the composition of this invention finally obtained may be 2.0-7.5 mass% in conversion of raw material mass ratio.

In the present invention, a general styrene-based resin such as a release agent, an ultraviolet absorber, a colorant, an antioxidant, a heat stabilizer, a plasticizer, a dye, and the like during the polymerization of the step 1 and the preparation of the copolymer (A2) or the melt kneading of the step 2, as necessary. You may mix various additives which can be added to. Without any problem, it can be added when kneading it or during polymerisation.

Specific examples include plasticizers such as mineral oils, ester plasticizers, polyester plasticizers, antioxidants, chain transfer agents, higher fatty acids, higher fatty acid esters, metal salts of higher fatty acids, silicone oils, and the like. More than one species are used in combination.

Thus, the transparent impact resistant styrene resin composition of this invention obtained as described above exhibits the effect that it is excellent in transparency, impact resistance, and rigidity as before with a sheet molding. For example, as transparency, the plate blur value using the 2 mm injection test piece based on ASTMD1003 will be 10 or less.

The transparent impact resistant styrene resin composition of the present invention has a good sheet extrusion moldability and an excellent balance between impact resistance and rigidity, and thus sheet molded articles such as food packaging trays, cover materials, cups, various storage trays, and carrier tapes. Very useful for such purposes.

Moreover, the transparent impact resistant styrene resin composition of the present invention has rigidity, impact resistance and transparency in addition to the use of sheet molded articles, and furthermore, injection molding, uniaxial extrusion molding, biaxial molding It can be applied to various molding applications such as stretch extrusion, inflation extrusion, calender molding, release extrusion, vacuum molding, and compressed air molding, and can be used for housings and parts of home appliances, various parts of OA machines, blister packages, and stationery. It can also be used for miscellaneous goods.

EXAMPLE

Physical properties in Examples were measured as follows.

(1) plate blur

According to ASTM D1003, it measured using the injection test piece of 2 mm thickness.

(2) DuPont impact strength

50% fracture energy of the 0.4 mm thick test piece was calculated | required using the DuPont impact tester. (Weight 200 g, impact radius tip radius 6.3 mm, receiving radius 6.3 mm)

(3) flexural modulus

Based on JISK7203, the test speed was made into 2 mm per minute, and the value was calculated | required.

(4) MFR (melt flow rate)

In accordance with JIS K7210, the temperature was measured at 200 ° C and a load of 5 Kgf.

(5) Drawdown Characteristic Evaluation

Using a sheet extruder (screw diameter 30 mm), the resin pellets were extruded at a melt resin temperature of 210 ° C. to 230 ° C. and an extrusion rate of 0.8 to 1 m / min to make a sheet sample having a thickness of 0.4 mm. Next, this sheet sample was measured using a vacuum molding machine to measure the length of the sheet extending down the center of the sheet on the basis of the sheet surface before sheet heating immediately after heating at a heating temperature of 290 ° C to 300 ° C and a heating time of 10 to 30 seconds. The drawdown properties were evaluated from the sagging length of the sheet against the heating time.

When heating time is 20 second, less than 40 mm of stretched amount is (circle) and 40 mm or more are x.

When heating time is 30 second, less than 60 mm of stretched amount is (circle), 60 mm or more is x.

[Production Example of Composition (Step 1)]

Preparation of Composition (1)

A mixed solution consisting of 50 parts of styrene, 45 parts of methyl methacrylate (MMA), 5 parts of butyl acrylate (BuA), 10 parts of ethylbenzene, and 14 parts of styrene-butadiene block copolymer (styrene monomer unit content of 40%) was prepared and polymerized. 0.02 parts of t-butylperoxybenzoate as an initiator and 0.1 part of n-dodecyl mercaptan are added with respect to 100 parts of monomer mixtures as a chain transfer agent, and it uses the polymerization line shown in the process diagram of FIG. Mass polymerization was performed continuously under the conditions.

Reaction temperature in the stirred reactor 2: 120 ° C.

Reaction temperature in circulating polymerization line (I): 140 ° C.

Reaction temperature in acyclic polymerization line (II): 150 ° C.

The mixed solution obtained by superposing | polymerizing was heated to 225 degreeC by the heat exchanger, after removing a volatile component under reduced pressure, it was made into pellets and the composition (1) was obtained. The physical properties of the obtained composition are shown in Table 1.

Preparation of Composition (2)

A monomer as a polymerization initiator in a mixed solution consisting of 50 parts of styrene, 45 parts of methyl methacrylate (MMA), 5 parts of butyl acrylate (BuA), 9 parts of ethylbenzene, and 11 parts of styrene-butadiene block copolymer (styrene monomer unit content of 40%) Composition (2) was prepared in the same manner as in Preparation Example of composition (1), except that 0.02 parts of t-butylperoxybenzoate and 100 parts of the monomer mixture as a chain transfer agent were added to 0.1 part of n-dodecylmercaptan. Got. The physical properties of the obtained composition are shown in Table 1.

[Production of Copolymer (A2)]

Preparation of Copolymer (A2-1)

A mixed solution consisting of 50 parts of styrene, 47.5 parts of methyl methacrylate (MMA), 2.5 parts of butyl acrylate (BuA), and 8 parts of ethylbenzene was prepared, and 0.02 parts of t-butylperoxybenzo with respect to 100 parts of the monomer mixture as a polymerization initiator. 0.1 part n-dodecyl mercaptan was added with respect to 100 parts of monomer mixtures as an acetate and a chain transfer agent, and mass polymerization was performed continuously on condition of the following.

Reaction temperature in the stirred reactor 2: 120 ° C.

Reaction temperature in circulating polymerization line (I): 140 ° C.

Reaction temperature in acyclic polymerization line (II): 150 ° C.

The mixed solution obtained by superposing | polymerizing was heated to 225 degreeC by the heat exchanger, after removing a volatile component under reduced pressure, it was made into pellets and obtained copolymer resin (A2-1). The physical properties of the obtained copolymer are shown in Table 2.

Preparation of Copolymer (A2-2)

A mixed solution consisting of 50 parts of styrene, 47.5 parts of methyl methacrylate (MMA), 2.5 parts of butyl acrylate (BuA), and 8 parts of ethylbenzene was prepared, and 0.02 parts of t-butylperoxybenzo with respect to 100 parts of the monomer mixture as a polymerization initiator. A copolymer (A2-2) was obtained in the same manner as the preparation example of the copolymer (A2-1) except that 0.09 parts of n-dodecyl mercaptan was added to 100 parts of the monomer mixture as the acetate and the chain transfer agent. The physical properties of the obtained copolymer are shown in Table 2.

Preparation of Copolymer (A2-3)

A mixed solution consisting of 50 parts of styrene, 47.5 parts of methyl methacrylate (MMA), 2.5 parts of butyl acrylate (BuA), and 8 parts of ethylbenzene was prepared, and 0.02 parts of t-butylperoxybenzo with respect to 100 parts of the monomer mixture as a polymerization initiator. A copolymer (A2-3) was obtained in the same manner as the preparation example of the copolymer (A2-1) except that 0.12 parts of n-dodecyl mercaptan was added to 100 parts of the monomer mixture as the acetate and the chain transfer agent. The physical properties of the obtained copolymer are shown in Table 2.

Example 1

The copolymer (A2-1) was added to the composition (1) at a compounding ratio of 70/30, extrusion molded to form a sheet having a thickness of 0.4 mm, and a JIS test piece and a plate molded article having a thickness of 2 mm were formed by injection molding. Various physical properties were measured using these. The measured values are shown in Table 3. In addition, sheet molding conditions and injection molding conditions are as follows.

Sheet Molding Machine: UEV Type 30mm Extruder

Cylinder temperature: 220 ℃, T die set temperature: 220 ℃

Injection Molding Machine: SAV-30-30-P Injection Molding Machine made by Sansei Seiki Co., Ltd.

Cylinder temperature: 230 ° C, mold temperature: 50 ° C

Example 2

The copolymer (A2-2) was added to the composition (1) at the compounding ratio of 60/40, the sheet | seat of thickness 0.4mm and the injection test piece were made on the same conditions as Example 1, and the various physical properties were measured. The measured values are shown in Table 3.

Example 3

The copolymer (A2-3) was added to the composition (1) at the compounding ratio of 60/40, the sheet | seat of thickness 0.4mm and the injection test piece were made on the same conditions as Example 1, and the various physical properties were measured. The measured values are shown in Table 3.

Comparative Example 1

Composition (1) The monolith was prepared under the same conditions as in Example 1 to form a sheet and an injection test piece of 0.4 mm in thickness, and measured various physical properties. The measured values are shown in Table 4.

Comparative Example 2

Composition (2) The monolith was prepared under the same conditions as in Example 1 to form a sheet and an injection test piece of 0.4 mm in thickness, and measured various physical properties. The measured values are shown in Table 4.

Comparative Example 3

The copolymer (II-2) was added to the composition (1) at the compounding ratio of 20/80, the sheet | seat of thickness 0.4mm and the injection test piece were made on the same conditions as Example 1, and the various physical properties were measured. The measured values are shown in Table 4.

TABLE 1

Composition One 2 (A) Styrene (part) 50 50 (B) MMA (part) 45 45 BuA 5 5 (C) rubber (part) 14 11 Dispersion Rubber Grain Size (㎛) 0.5 0.22 Mz x 10 ⁴ 21.4 21.6 Plate blur 3.5 3.0 MFR (g / 10min) 2.5 2.1

TABLE 2

Copolymer A2-1 A2-2 A2-3 (A ') Styrene (part) 50 50 50 (B ') MMA (part) 47.5 47.5 50 BuA 2.5 2.5 0 Mz x 10 ⁴ 24.2 26.0 24.5 Plate blur 0.4 0.4 0.4 MFR (g / 10min) 2.1 1.9 1.2

TABLE 3

Example One 2 3 Composition (1) 60 60 60 Composition (2) Copolymer A2-1 40 Copolymer A2-2 40 Copolymer A2-3 40 Plate blur 2.0 2.0 2.5 DuPont Impact Strength (J) 0.51 0.55 0.62 Flexural Modulus (MPa) 2750 2770 2800 Drawdown O O O Toluene Insoluble Component Content 6.7 6.7 6.7 Swelling index 14 14 14 Insoluble component / swelling index Butadiene content Mz x 10 ⁴ 0.5622.5 0.5622.8 0.5622.5

TABLE 4

Example One 2 3 Composition (1) 100 20 Composition (2) 100 Copolymer A2-1 Copolymer A2-2 80 Plate blur 3.5 3.0 0.9 DuPont Impact Strength (J) 1.00 0.40 0.08 Flexural Modulus (MPa) 2430 2500 2870 Drawdown O O O Toluene Insoluble Component Content 11.1 9.0 2.3 Swelling index 14 14 9 Insoluble component / swelling index Butadiene content Mz x 10 ⁴ 0.8821.4 0.7721.6 0.31.524.8

According to this invention, the transparent styrene resin composition excellent in transparency, impact resistance, and rigidity can be provided, and its manufacturing method.

In the sheet molded article, cracking and deformation caused by applying a load from the upper part of the molded article can be prevented, and since transparency is excellent, visual recognition of the contents is also good. Therefore, it is very useful for uses, such as a food packaging tray, a cover material, a cup, various storage trays, and a carrier tape.

Claims (6)

A transparent impact resistant styrene resin composition comprising a matrix and rubber particles dispersed in the matrix, the matrix comprising a copolymer (A) of a styrene monomer (a1) and an alkyl ester of (meth) acrylate (a2), The rubbery particles are made of a styrene butadiene block copolymer (b), Z average molecular weight Mz of the said copolymer (A) is 22 * 10 <^4> -28 * 10 <^4> , The average particle diameter of the said rubbery particle is 0.3-2.0 micrometers, and The content rate of the polymer block of butadiene in the said composition is 2.0-7.5 mass%, The transparent impact resistant styrene resin composition characterized by the above-mentioned. The method of claim 1, The swelling index by toluene at 25 degrees C in rubber-like particle | grains is 8-19 in the said composition, and the ratio of the toluene insoluble component content rate and the said swelling index at 25 degrees C of all compositions is toluene (toluene Insoluble component content / swelling index) is 0.2-0.8. The method of claim 2, A composition in which the styrene structural unit content of the copolymer (A) is 30 to 60%, and the styrene structural unit content of the styrene butadiene block copolymer (b) is 33 to 55%. The method according to claim 1 or 3, The said (meth) acrylic-acid alkylester (a2) consists of methyl (meth) acrylate and butyl (meth) acrylate. The method of claim 1, The said copolymer (A) consists of a component whose Z mean molecular weight Mz is 20x10 <^4> -22.5x10 <^4> , and a component whose Z average molecular weight Mz is 23 * 10 <^4> -29 * 10 <^4> . The method of claim 5, The ratio of the former / the latter = 85/15 to 30/70 based on the mass of the component having a Z average molecular weight Mz of 20 × 10 ^{4 to} 22.5 × 10 ^{4 and} a component having a Z average molecular weight Mz of 23 × 10 ^{4 to} 29 × 10 ⁴ Composition containing.