JP3508454B2 - Methyl methacrylate resin and molded product thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a methyl methacrylate resin and a molded product thereof.

[0002]

Blow molding is a method of preforming a parison by extrusion molding or injection molding of a thermoplastic resin, sandwiching it with a mold, blowing air into the parison, and expanding it to cool and solidify it. This is the method that has been deployed to. On the other hand, when blow molding is performed using a conventional acrylic resin, the thickness of the molded product becomes thin, and almost no acrylic resin is used for blow molding.

[0003]

In view of such circumstances, the present inventor has accomplished the present invention as a result of earnestly investigating a methyl methacrylate resin suitable for blow molding.

[0004]

That is, according to the present invention, the following equation [Equation 1],

From a linear polymer having a molecular weight distribution satisfying Mz × (Mz + 1) / Mw ² ≧ 3.5 (in the formula, Mz represents a Z average molecular weight and Mw represents a weight average molecular weight). The melt flow rate at 230 ° C. is 0.5 to 20 g / 10 minutes , and the die swell ratio is 1.
2 to 2.5, and a molded product obtained by blow molding using the methyl methacrylate resin. Hereinafter, the present invention will be described in detail.

[0005]

DETAILED DESCRIPTION OF THE INVENTION Melt Flow Rate (MFR)
Is the weight (g) flowing out of the orifice in 10 minutes using an orifice with a length of 8.0 mm and a diameter of 2.09 mm at a load of 3.8 kg at 230 ° C. The ratio is represented by a value obtained by dividing the maximum diameter of the strand that flows out by the diameter of the orifice. The melt flow rate at 230 ° C. is 0.5
.About.20, and the die swell ratio is 1.2 to 2.
When the methyl methacrylate resin composition of No. 5 is used, a good blow molded product can be obtained. The die swell ratio of the conventional methyl methacrylate resin is about 1 at a shear stress of about 3.4 × 10 ⁵ dyne / cm ² at the time of measuring the melt flow rate (Journal of Applied Polymer Science (J .Appl.Polym.Sci.) 29 (1984), 3479
-3490 described in Fig. 5).

As an example of the methyl methacrylate resin composition of the present invention, the weight average molecular weight is 80,000 to 400,000, and the molecular weight between branch points defined by the Z average molecular weight is 30,000 to 50.
If the branched methyl methacrylate polymer A is
100% by weight and the linear methacrylic resin B are 0 to 7
An example is a methyl methacrylate-based resin composition consisting of 0% by weight.

The branched methyl methacrylate polymer A is
It is a polymer of a monofunctional monomer containing methyl methacrylate as a main component and a polyfunctional monomer copolymerizable therewith. The monofunctional monomer having methyl methacrylate as a main component means a monofunctional unsaturated monomer which can be copolymerized with methyl methacrylate alone or with 50% by weight or more, and preferably 70% by weight or more of methyl methacrylate. It is a mixture of bodies. If the methyl methacrylate content is less than 50% by weight, the so-called polymethylmethacrylate characteristics, such as transparency and mechanical strength, are difficult to develop.

Examples of the copolymerizable monofunctional unsaturated monomer include methacrylic acid esters such as ethyl methacrylate, propyl methacrylate, butyl methacrylate, and benzyl methacrylate; methyl acrylate, ethyl acrylate, and acrylic. Acrylic esters such as propyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate;
Unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid and itaconic acid, acid anhydrides such as maleic anhydride and itaconic anhydride; 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, monoglycerol acrylate, Hydroxy group-containing esters such as 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate and monoglycerol methacrylate; amides such as acrylamide, methacrylamide, diacetone acrylamide; nitriles such as acrylonitrile and methacrylonitrile; diacetone Nitrogen-containing monomers such as acrylamide and dimethylaminoethyl methacrylate; epoxy group-containing monomers such as allyl glycidyl ether, glycidyl acrylate and glycidyl methacrylate; styrene, α-
Examples thereof include styrene-based monomers such as methylstyrene.

The copolymerizable polyfunctional monomer includes ethylene such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate and tetraethylene glycol di (meth) acrylate. Glycol or its oligomer esterified at both terminal hydroxyl groups with acrylic acid or methacrylic acid; divalent alcohols such as neopentyl glycol di (meth) acrylate, hexanediol di (meth) acrylate, butanediol di (meth) acrylate, etc. Esterified with hydroxyl or acrylic acid of acrylic acid or methacrylic acid; polyhydric alcohols such as trimethylolpropane and pentaerythritol or derivatives of these polyhydric alcohols with acrylic acid or methacrylic acid Mentioned aryl compounds having at least two alkenyl groups such as divinylbenzene; phased those

The weight average molecular weight (Mw) of the branched methyl methacrylate polymer A is 80,000 to 400,000. It is preferably 150,000 to 300,000. If the Mw is less than 80,000, the mechanical strength of the resin will be insufficient, and the strength of the molded article obtained by blow molding of the methyl methacrylate resin composition containing this will be poor. On the other hand, if it exceeds 400,000, it cannot be extruded under the temperature condition where the melt viscosity is high and the resin does not decompose.

The branched methyl methacrylate polymer A is
A molecular weight between branch points (Mzb) defined by using the Z-average molecular weight (Mz) is 30,000 to 500,000, preferably 5
It ranges from 10,000 to 200,000. When Mzb exceeds 500,000,
The resulting resin has poor tension during melt drawing, and the composition comprising the composition has poor extrusion performance. On the other hand, when Mzb is less than 30,000, the mechanical strength is poor and the appearance of the molded product is poor.

Here, Mw and Mz are values obtained by gel permeation chromatography (GPC) and a differential refractometer. For example, this method is 19
1994 edition "Polymer property analysis" (Kyoritsu Shuppan) pages 24-5
It is described on page 5.

The inter-branch molecular weight means the average value of the molecular weight from a branch point to the next branch point in a polymer having a branched structure, and is defined by using the Z average molecular weight (Mz). The molecular weight between branch points (Mzb) is calculated from the following [Equation 3] and [Equation 4] based on the description of "Characterization", Vol. 45, No. 2, pp. 105-118, Japan Rubber Association. It

[0014]

[Equation 3] {[η ₁ ] / [η ₂ ]} ^10/6 = {(1 + Bz /
6) ^0.5 + 4Bz / 3π} ^-0.5

[0015]

## EQU00004 ## Mzb = Mz / Bz

In the above [Formula 3], [η ₁ ] is obtained by using a universal calibration curve showing the relation between the product of the intrinsic viscosity and the absolute molecular weight with respect to the GPC elution time of the linear methyl methacrylate polymer standard sample. In the calibration curve showing the relationship of the intrinsic viscosity to the absolute molecular weight of the polymer to be measured, the molecular weight is the intrinsic viscosity corresponding to the Mz value. [η ₂ ] is
In a calibration curve showing the relationship between the absolute molecular weight and the intrinsic viscosity of a linear methyl methacrylate polymer standard sample, it is the intrinsic viscosity for the same molecular weight Mz value as the polymer to be measured. Bz is the number of branch points in the Z average molecular weight Mz.

The branched methyl methacrylate polymer A is
When the polymer has a molecular weight of 300,000 or more and the reduced viscosity of the polymer is 0.7 dl / g or less, {[14
X (reduced viscosity value) -6.8] to [14x (reduced viscosity value)
+11.2]} (wt%) and the reduced viscosity is 0.7 dl
When it exceeds / g, {[40 x (reduced viscosity value) -25] ~
[40 x (reduced viscosity value) -7]} (wt%) is preferable. The reduced viscosity represented by the present invention is the value at a solution concentration of 1 g / dl in chloroform of the polymer to be measured at 25 ° C.

When the ratio of the molecular weight of the branched methyl methacrylate polymer A of 300,000 or more is within the above range, the branched methyl methacrylate polymer is excellent in the balance between the fluidity and the tensile strength during melting. Along with that, a good molded product can be obtained due to the excellent balance between the fluidity of the resin composition obtained using this and the strength following melt drawing. The degree of cross-linking of the branched methyl methacrylate-based polymer is the gel fraction (% by weight of the portion not requiring acetone relative to the total weight of the polymer).
Is usually 3% or less, preferably 1% or less, more preferably about 0%.

The branched methyl methacrylate polymer A is
It can be obtained by adding a predetermined amount of a component to be a polyfunctional constitutional unit, if necessary, a chain transfer agent and / or a polymerization initiator to the monomer of the constitutional unit described above, and polymerizing.
Examples of the component serving as a polyfunctional constitutional unit include a polyfunctional monomer, a polyfunctional chain transfer agent, a polyfunctional initiator, and these 2
Mention may be made of mixtures of more than one species. The amount of the component serving as the polyfunctional constituent unit is usually 0.02 to 1% by weight based on methyl methacrylate (and the monofunctional monomer).

The chain transfer agent may be a known one used in the polymerization of methyl methacrylate. Among these, there are monofunctional chain transfer agents having one chain transfer functional group and polyfunctional chain transfer agents having two or more chain transfer functional groups. Examples of monofunctional chain transfer agents include alkyl mercaptans and thioglycolic acid esters, and examples of polyfunctional chain transfer agents include ethylene glycol, neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol, and tripenta. Examples include polyhydric alcohol hydroxyl groups such as erythritol and sorbitol esterified with thioglycolic acid or 3-mercaptopropionic acid.

The amount of the chain transfer agent used in obtaining the branched methyl methacrylate polymer A is usually 5 × 10 ^-5 mol to 5 × 10 ^-3 mol per mol of the monofunctional monomer. Yes, the amount of copolymerizable polyfunctional monomer is 1
The number of functional groups is usually in the range of 1 × 10 ⁻⁵ to {chain transfer agent (mol) −2.5 × 10 ⁻⁴ } equivalent per mole.

The weight average molecular weight of the branched methyl methacrylate polymer A is governed by the concentration of the polyfunctional monomer generally used, the concentration of the chain transfer agent and the concentration of the radical initiator. The weight average molecular weight is adjusted within the above concentration range of the polyfunctional monomer in consideration of the fact that the higher the concentration of the polyfunctional monomer is, the larger the weight average molecular weight is, and the higher the concentration of the chain transfer agent is, the smaller the weight average molecular weight is. And by appropriately changing within the range of the concentration of the chain transfer agent. The molecular weight between branch points can be adjusted mainly by the concentration of the polyfunctional monomer. The higher the polyfunctional monomer concentration, the smaller the molecular weight between branch points. Also,
In the chain transfer agent, the higher the concentration of the polyfunctional chain transfer agent, the smaller the molecular weight between branch points. The ratio of molecular weight of 300,000 or more is
The higher the concentration of the polyfunctional monomer, the greater the amount.

As the polymerization initiator, there are a monofunctional polymerization initiator which generates a pair of radicals and a polyfunctional polymerization initiator which generates two or more pairs of radicals in one molecule. Examples of the monofunctional polymerization initiator include azo compounds such as 2,2′-azobis (2,4-dimethylvaleronitrile), azobisisobutyronitrile, and dimethyl-2,2′-azobisisobutyrate. t-butyl peroxypivalate, t-butyl peroxy 2-ethylhexanoate,
Peroxyesters such as cumylperoxy 2-ethylhexanoate; organic peroxides such as diacyl peroxides such as di-3,5,5-trimethylhexanoyl peroxide and diacyl peroxide such as dilauroyl peroxide; Can be mentioned. Examples of polyfunctional polymerization initiators include bifunctional 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane and di-t.
As tributyl-peroxytrimethyl adipate, trifunctional tris- (t-butylperoxy) triazine, tetrafunctional 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane and the like can be mentioned. .

When the polymerization is completed at a polymerization rate of 45 to 60% by weight as in the bulk polymerization method, the use of a trifunctional or higher polyfunctional polymerization initiator will result in a higher polyfunctionality than branching by a polyfunctional monomer alone. The amount of unreacted vinyl groups due to the monomer can be reduced. When a polyfunctional polymerization initiator is used, it can be replaced with some or all of the above-mentioned polyfunctional constitutional units. The amount of the polymerization initiator used may be a well-known appropriate amount according to the polymerization method, and the monomer or the monomer mixture 10
About 0 to 1 part by weight, usually about 0.001 to 1 part by weight,
It is preferably 0.01 to 0.7 parts by weight. It should be noted that the larger the amount of the polymerization initiator, the smaller the weight average molecular weight, as in the case of a general methyl methacrylate polymer.

The linear methacrylic resin B has a weight average molecular weight (Mw) of 70,000 to 300,000, preferably 80,000 to 200,000. If the Mw is less than 70,000, the mechanical strength of the molded product obtained from the resin composition obtained will be insufficient. Again 30
If it exceeds 10,000, the melt fluidity becomes low and the extrusion characteristics deteriorate.

The linear methacrylic resin B is a polymer of a monofunctional monomer whose main component is methyl methacrylate.
The monofunctional monomer whose main component is methyl methacrylate is
It is a mixture of monofunctional unsaturated monomers copolymerizable with methyl methacrylate alone or 50% by weight or more, preferably 70% by weight or more, of methyl methacrylate. Examples of the monofunctional unsaturated monomer copolymerizable with methyl methacrylate include those described above. The polymerization initiator used when polymerizing a monofunctional monomer containing methyl methacrylate as a main component, and optionally a chain transfer agent, include the monofunctional polymerization initiators and chain transfer agents described above.

As the polymerization method for obtaining the branched methyl methacrylate polymer A and the linear methacrylic resin B, a well-known polymerization method for producing a general methyl methacrylate resin, that is, a suspension polymerization method or a bulk polymerization method. A polymerization method or an emulsion polymerization method can be applied.

The methyl methacrylate resin composition used in the present invention comprises 30 to 100% by weight of a branched methyl methacrylate polymer A and a linear methacrylic resin B.
Those having a content of 0 to 70% by weight are preferably used.

As the methyl methacrylate resin composition used in the present invention, in addition to the resin composition comprising the branched methyl methacrylate polymer A and the linear methacrylic resin B described above, the following formula ],

[0030]

## EQU5 ## Mz × (Mz + 1) / Mw ² ≧ 3.5 (In the formula, Mz and Mw are the same as those described above, and represent Z average molecular weight and weight average molecular weight determined by GPC and a differential refractometer. A methyl methacrylate-based resin C having a molecular weight distribution satisfying (1) is also suitable. The methyl methacrylate resin C may be a linear polymer or a mixture thereof.

The resin composition of the present invention may be a resin composition comprising a methyl methacrylate-based polymer A and a methacrylic resin B, or a methyl methacrylate-based resin C mixed with a rubber-like polymer D. Is. By blending the rubbery polymer D, the impact resistance of the molded product is remarkably improved, and the toughness and toughness are improved, so that a blow molded product of good quality can be obtained.

As the rubbery polymer D, (1) an acrylic multi-layer structure elastic body or (2) 5 to 80 parts by weight of a rubbery polymer and 95 to 20 parts by weight of an ethylenically unsaturated monomer is graft-polymerized. The above graft copolymer is preferably used.

(1) The acrylic multi-layer structure elastic body is an acrylic polymer in which 20 to 60 parts by weight of a rubber elastic layer or an elastomer layer having at least a two-layer structure is incorporated, and a soft layer, Based on the outer hard layer,
The structure may further include the innermost hard layer. For example, those described in JP-B-55-27576, JP-A-6-80739 and JP-A-49-23292 can be used.

(2) A graft copolymer obtained by graft-polymerizing 95 to 20 parts by weight of an ethylenically unsaturated monomer on 5 to 80 parts by weight of a rubber-like polymer is used as a rubber-like polymer such as polybutadiene rubber or acrylonitrile / Diene rubber such as butadiene copolymer rubber and styrene / butadiene copolymer rubber, acrylic rubber such as polybutyl acrylate, polypropyl acrylate and poly-2-ethylhexyl acrylate, and ethylene / propylene / non-conjugated diene rubber Can be used. Examples of the ethylenic monomer and a mixture thereof used for graft-copolymerizing the rubber-like polymer include styrene, acrylonitrile, and alkyl (meth) acrylate. As these graft copolymers, JP-A-55 is
-147514 and Japanese Patent Publication No. 47-9740 can be used.

The composition ratio of the methyl methacrylate resin composition containing the rubber polymer D is 30 to 95% by weight of the branched methyl methacrylate polymer A and 0 to 70 of the linear methacrylic resin B. 5% by weight and rubbery polymer D
70% by weight, preferably 8 to 50% by weight, or 30 to 95% by weight of the methyl methacrylate resin C and 5 to 70% by weight of the rubbery polymer D, preferably 8 to 50% by weight.
Is. If the proportion of the rubber-like polymer D is less than 5% by weight, the effect of impact resistance is reduced, and if it exceeds 70% by weight, the heat resistance is lowered and the effect of the methyl methacrylate polymer A is lowered.

In the methyl methacrylate resin composition of the present invention, if necessary, a general release agent, an ultraviolet absorber, a colorant, an antioxidant, a heat stabilizer, a plasticizer, an antistatic agent, etc. Various agents that can be added to the acrylic resin can be added.

Examples of the method for blow molding the methyl methacrylate resin composition of the present invention include a direct blow molding method and an injection blow molding method, but the molding conditions are not particularly limited and conventionally known conditions. It is carried out according to.

By blow molding a parison obtained by compounding the methyl methacrylate resin composition of the present invention with a thermoplastic resin other than the above in a multi-layer structure, good weather resistance, gloss, which are characteristics of the methacrylic resin, It is possible to obtain a molded article of another thermoplastic resin having hardness. The thermoplastic resin used at this time is a so-called acrylic resin,
Examples thereof include carbonate resin, acrylonitrile / butadiene / styrene resin, polyvinyl chloride, polyethylene terephthalate and the like.

[0039]

EFFECTS OF THE INVENTION According to the present invention, the drawdown is low in the blow molding which has hitherto been difficult with the acrylic resin,
It becomes easy to obtain a molded product having a large wall thickness, and it is possible to easily provide a hollow molded product excellent in weather resistance and surface hardness, which are features of the acrylic resin.

[0040]

EXAMPLES The present invention will be described in detail below with reference to examples. Among the measuring methods, the items other than those described above were measured as follows. (1) MFR: Measured according to JIS K7210. The temperature is 23
The temperature was 0 ° C. and the load was 3.8 kgf. (2) Die swell ratio: A value obtained by dividing the maximum diameter of the strand measured by MFR by the diameter of the orifice (2.09 mm).

Abbreviations of various monomers and chain transfer agents used in the examples are as follows. -MMA: methyl methacrylate-MA: methyl acrylate-DDSH: n-dodecyl mercaptan-HDA: 1,6-hexanediol diacrylate

Reference Examples A1 to A4 "Methyl methacrylate-based polymer (A) having a branched structure"
Production of MMA, M in a 200-liter SUS autoclave
A, HDA and DDSH in the amounts shown in [Table 1], 0.3 part by weight of lauroyl peroxide, and 2 parts of deionized water.
00 parts by weight and 1 part by weight of sodium polymethacrylate were added and mixed, heated and heated to start polymerization at 80 ° C.,
After 90 minutes, the polymerization was further performed at 100 ° C. for 60 minutes. After the polymerization, washing, dehydration and drying were carried out to obtain a beaded polymer. The polymer obtained was evaluated. The evaluation results are shown in [Table 1].

Reference Examples B1 to B3 "Production of Linear Methyl Methacrylate Polymer (B)" MMA and M were added to a 200 liter SUS autoclave.
A, DDSH as shown in [Table 1], 0.3 parts by weight of lauroyl peroxide, 200 parts by weight of ion-exchanged water,
1 part by weight of sodium polymethacrylate was added and mixed, heated and heated to start polymerization at 80 ° C., and after 90 minutes, further polymerized at 100 ° C. for 60 minutes. After the polymerization, washing, dehydration and drying were carried out to obtain a beaded polymer. The polymer obtained was evaluated. The evaluation results are shown in [Table 1].

[0044]

[Table 1]

Test Example 1 As the branched methyl methacrylate polymer A, A1 of [Table 1] produced in Reference Example was used as an extruder (uniaxial, screw diameter
Direct blow molding machine NB3 manufactured by Japan Steel Works, pelletized with 40 mm, Tanabe Plastics Co., Ltd.
B (screw: 50 mmφ, no accumulator)
Was blow-molded at a cylinder and die temperature of 220 ° C. and a screw rotation speed of 20 rpm (discharging amount: about 150 g / min) to obtain a threaded container having an outer diameter of 70 mm and a height of 170 cm. The thickness distribution of this container was uniform and good. The results are shown in [Table 2].

Test Example 2 50 parts by weight of A2 beads in Table 1 and B1 beads 50
By blending parts by weight and pelletizing in the same manner as in Test Example 1, blow molding was performed in the same manner as in Test Example 1. The thickness distribution of the container was uniform and good. The results are shown in [Table 2].

Example 1 80 parts by weight of B2 beads of Table 1 and B3 beads 20
Blow molding was carried out in the same manner as in Test Example 1 by blending parts by weight and pelletizing by repeating the granulation three times with a twin-screw extruder TEX30 manufactured by Japan Steel Works Ltd. The thickness distribution of the container was uniform and good. The results are shown in [Table 2].

Comparative Examples 1 to 3 The resins shown in Table 2 were pelletized by a uniaxial extruder and blow molded in the same manner as in Test Example 1, but good blow molded products were obtained. There wasn't. The results are shown in [Table 2].

Test Example 3 and Comparative Example 4 IS220FA3 manufactured by Toshiba Machine Co., Ltd. was used by pelletizing the resin shown in [Table 2] with a uniaxial extruder, and the maximum cylinder temperature was 250 ° C. and the manifold setting was 230 ° C, fixed mold temperature setting is 135 ° C, moving mold temperature setting is 145 ° C, height 12 cm, diameter 220 m
mΦ, 2 mm thick parison was injection molded, and subsequently the mold on the moving side was replaced with the resin melted, and the maximum diameter was 2
It was stretched to 75 mmΦ and blow molded. When the thickness of the maximum stretched portion was measured, the thickness of the thinnest portion of B1 was 0.66 mm, but the thickness of A1 was 0.91 mm.
The results are shown in [Table 2].

Test Example 4 50 parts by weight of A1 and Orogras DR as a rubber-like polymer
50 parts by weight of 101 (manufactured by Rohm & Haas) was blended and granulated using an extruder. The selected blend was blow molded as in Test Example 1. The thickness distribution of the container was uniform and good. The results are shown in [Table 2].

Test Example 5 Blow molding was carried out in the same manner as in Test Example 4 except that Sumipex HT018E (manufactured by Sumitomo Chemical Co., Ltd.) was used as the rubber-like polymer. The thickness distribution of the container was uniform and good. The results are shown in [Table 2].

Test Example 6 80 parts by weight of B2 and 20 parts by weight of B3 were blended and granulated in advance with a twin-screw extruder in the same manner as in Example 1 to give 5 parts.
0 parts by weight, and 50 parts by weight of Orograss DR101 were blended and granulated using an extruder. The selected blend was blow molded as in Test Example 1. The thickness distribution of the container was uniform and good. The results are shown in [Table 2].

Comparative Example 5 50 parts by weight of B1 and Orogras DR as a rubber-like polymer
Blow molding was carried out in the same manner as in Test Example 4 by blending 50 parts by weight of 101 by using an extruder, and then blow molding was performed, but a good blow molded product could not be obtained. The results are shown in [Table 2].

[0053]

[Table 2] MFR: Melt flow rate SR: Die swell ratio D: Direct blow method I: Injection blow method DD: Drawdown

Front page continued (58) Fields surveyed (Int.Cl. ⁷ , DB name) C08L 33/12 C08F 20/14 C08F 120/14 C08F 220/14 B29C 49/00 WPI (DIALOG)

Claims (2)

(57) [Claims] 1. The following equation [Equation 1] is satisfied: ## EQU1 ## Mz × (Mz + 1) / Mw ² ≧ 3.5 (wherein Mz represents a Z-average molecular weight and Mw represents a weight-average molecular weight). It is composed of a linear polymer having a molecular weight distribution, has a melt flow rate at 230 ° C. of 0.5 to 20 g / 10 minutes , and a die swell ratio of 1.
2 to 2.5, a methyl methacrylate resin. 2. A molded product obtained by blow molding the methyl methacrylate resin according to claim 1.