JPH09207196A - Poly(methyl methacrylate) extruded plate and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the nonuniformity of plate thickness after a secondary molding to form a complex shape or to increase area greatly. SOLUTION: Linear poly(methyl methacrylate) (A) having weight average molecular weight of 70,000-200,000 and poly(methyl methacrylate) (B) which has weight average molecular weight of 70,000-400,000 and branch structure indicated by molecular weight between branch points of 30,000-500,000 defined by z average molecular weight are constituents, and a weight ratio of (A)/(B) is 0/100-90/10.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a methyl methacrylate resin extruded plate and a method for producing the same.

[0002]

2. Description of the Related Art Methyl methacrylate resins are rigid, have excellent transparency and weather resistance, so they are used for signboards, light guides, lighting covers, carport roofs, vending machine front panels, Widely used for applications such as showcases and bathtubs. In many of these applications, an extruded plate obtained by melting a methacrylic resin, passing through a T-die and a roll unit, and stretched and cooled is used, and the extruded plate is further heated to perform secondary molding. It is processed into a desired shape.

As this secondary forming method, for example,
Free blow molding, free vacuum molding, push-up molding, ridge molding, straight molding, drape molding, reverse draw molding, air slip molding, plug assist molding, plug assist reverse draw molding, and the like. These molding methods involve stretching of a material, but recently, the shape of a molded article has been complicated due to high stretching molding such as a lighting cover or a bathtub, and improvement of molding technology itself.

[0004]

In the case of the conventional methyl methacrylate resin extruded plate material, when the secondary molding having a complicated shape or a high area expansion rate is performed, the phenomenon that the molded article becomes locally thin occurs. However, in addition to the post-processing process and the transportation process, a crack may be generated from that portion during actual use, which spoils the commercial value of the corner.

Therefore, according to the present invention, even if secondary molding with a complicated shape or a high area expansion rate is performed in the secondary processing, the thickness of the molded product is less thinned, that is, methacrylic resin with less uneven thickness after molding. A methyl acid resin extruded plate is provided.

[0006]

The present invention provides a linear methyl methacrylate polymer (A) having a weight average molecular weight of 70,000 to 200,000 and a weight average molecular weight of 80,000 to 400,000, and Z
The molecular weight between branch points defined using the average molecular weight is 30,000-
It is composed of a methyl methacrylate-based polymer (B) having a branched structure of 500,000, and the weight ratio (A) / (B) is 0 /
It is a methylmethacrylate resin extruded board which is 100-90 / 10, and its manufacturing method. Hereinafter, the present invention will be described in detail.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The methyl methacrylate polymer used in the present invention is one containing 50% by weight or more, preferably 70% by weight or more, of a methyl methacrylate unit as its constituent unit. As long as the content of the unit is 50% by weight or more, a part of the unit may be replaced with a monofunctional unsaturated monomer unit copolymerizable with methyl methacrylate. The copolymerizable monofunctional unsaturated monomer unit is preferably contained in the polymer in an amount of 1% by weight or more, more preferably 3% by weight or more, particularly 3 to 20% by weight. preferable.

Examples of the copolymerizable monofunctional unsaturated monomer include, for example, ethyl methacrylate, butyl methacrylate,
Cyclohexyl methacrylate, phenyl methacrylate,
Methacrylates such as benzyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate, methyl acrylate, ethyl acrylate,
Acrylates such as butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, etc., unsaturated acids such as methacrylic acid and acrylic acid, styrene, α -Methylstyrene, acrylonitrile, methacrylonitrile and the like.

The weight average molecular weight (Mw) of the linear methyl methacrylate polymer (A) of the present invention is 70,000 to 200,000, preferably 80,000 to 150,000. Weight average molecular weight (Mw)
Is less than 70,000, the mechanical strength of the extruded plate is insufficient. On the other hand, if it exceeds 200,000, the melt fluidity becomes low and it becomes difficult to form an extruded plate, and the secondary formability also deteriorates.

The weight average molecular weight (Mw) of the methyl methacrylate polymer (B) of the present invention is 80,000 to 400,000, preferably 150,000 to 300,000. Weight average molecular weight (Mw)
Is less than 80,000, the mechanical strength of the extruded plate is insufficient, and if it exceeds 400,000, the secondary formability is deteriorated.

The methyl methacrylate polymer (B) of the present invention has a molecular weight between branch points (Mzb) defined by its Z average molecular weight (Mz) of 30,000 to 500,000, preferably It is from 50,000 to 200,000. If the molecular weight between branch points (Mzb) is less than 30,000, the mechanical strength will be insufficient and the appearance of the product after secondary molding will be poor. If it exceeds 500,000, the effect of suppressing uneven thickness after secondary molding tends to be small.

Here, the weight average molecular weight (Mw) and Z average molecular weight (Mz) are values obtained by gel permeation chromatography (GPC) and a differential refractometer. The method of obtaining this is described in, for example, “Polymer Characteristic Analysis”, edited by The Society of Polymer Science, Japan, 1984, pp. 24 to 55
Page.

The molecular weight between branch points means an average molecular weight from a branch point to the next branch point in a polymer having a branched structure, and is defined by using a Z average molecular weight (Mz). The molecular weight between branch points (Mzb) is calculated from the following [Equation 1] and [Equation 2] based on the description in "Characterization" of the Japan Rubber Association, Vol. 45, No. 2, pages 105-118. You.

[0014]

## EQU1 ## {[η ₁ ] / [η ₂ ]} ^10/6 = {(1 + Bz /
6) ^0.5 + 4Bz / 3π｝ ^-0.5

[0015]

## EQU2 ## Mzb = Mz / Bz

In the above [Equation ₁ ], [η ₁ ] is obtained by using a universal calibration curve showing the relationship 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 intrinsic viscosity and the absolute molecular weight of a linear methyl methacrylate polymer standard sample, the intrinsic viscosity corresponds to 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.

In the methyl methacrylate polymer (B) having a branched structure in the present invention, the ratio of the polymer having a molecular weight of 300,000 or more is such that the reduced viscosity of the polymer is 0.7 dl / g or less. , {[14 × the reduced viscosity value−
6.8] to [14 × the reduced viscosity value + 11.2]} (wt%), when the reduced viscosity of the polymer is 0.7 dl / g or more,
It is preferably in the range of [[40 × the reduced viscosity value−25] to [40 × the reduced viscosity value−7]} (wt%). In addition, the reduced viscosity represented by the present invention is a value at a solution concentration of the polymer to be measured at 1 g / dl. In this specification, unless otherwise specified, the molecular weight means a value converted to the molecular weight of the linear methyl methacrylate polymer. When the proportion of the molecular weight of 300,000 or more is in the above range, the balance between fluidity, solvent resistance and mechanical strength is excellent.

The degree of crosslinking of the methyl methacrylate-based polymer (B) having a branched structure in the present invention is usually 3% or less, preferably expressed as a gel fraction (weight% of acetone-insoluble portion relative to the total weight of the polymer). Is 1% or less, more preferably about 0%.

The methyl methacrylate-based polymer (B) having a branched structure is obtained by adding a predetermined amount of a component to be a polyfunctional constitutional unit to the monomer of the constitutional unit described above, if necessary, a chain transfer agent and / or polymerization. It is obtained by adding an initiator and polymerizing. The amount of the component serving as the polyfunctional constitutional unit is usually 0.02 to 1 part by weight based on methyl methacrylate (and the monofunctional monomer).

The copolymerizable polyfunctional monomer includes ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate and the like ethylene. 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 Phased what; divinyl benzene.

The chain transfer agent may be a known one used in the polymerization of methyl methacrylate. Among these, there are a monofunctional chain transfer agent having one chain transfer functional group and a polyfunctional chain transfer agent having two or more chain transfer functional groups. Examples of the monofunctional chain transfer agent include alkyl mercaptans and thioglycolic acid esters. Examples of the polyfunctional chain transfer agent include ethylene glycol, neopentyl glycol, trimethylolpropane, ditrimethylolpropane, pentaerythritol, and dipenta Polyhydric alcohol hydroxyl groups such as erythritol, tripetaerythritol, sorbitol, etc.
Those esterified with mercaptopropionic acid may be mentioned.

The amount of the chain transfer agent and the polyfunctional monomer is such that the amount of the chain transfer agent is 1 × 1 per mol of the monofunctional monomer.
0 ^-5 mol to 5 × 10 ^-3 mol, the amount of the polyfunctional monomer is 1 × 10 ^-5 to {the chain transfer agent (mol) -2.
The range is 5 × 10 ⁻⁴ mol.

The weight average molecular weight of the methyl methacrylate polymer (B) having a branched structure is generally controlled mainly by the concentration of the polyfunctional monomer, the concentration of the chain transfer agent and the concentration of the radical initiator which are mainly used. To adjust the weight average molecular weight,
Considering that the weight average molecular weight increases as the concentration of the cross-linking agent increases, and conversely decreases with the increase of the chain transfer agent, within the above concentration range of the polyfunctional monomer and within the concentration range of the chain transfer agent. Make appropriate changes in.

The molecular weight between branch points can be adjusted mainly by the concentration of the polyfunctional monomer. The higher the concentration of the polyfunctional monomer, the lower the molecular weight between branch points. As for the chain transfer agent, the higher the concentration of the polyfunctional chain transfer agent, the smaller the molecular weight between branch points. The proportion having a molecular weight of 300,000 or more increases as the concentration of the polyfunctional monomer increases.

The amount of the polymerization initiator used may be a well-known suitable amount depending on the polymerization method, and is about 0.001 to 1 part by weight, preferably 0.01, relative to 100 parts by weight of the monomer or monomer mixture. ~ 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 is, as is the case with well-known general methacrylic polymers, in both the methyl methacrylate polymers (A) and (B) of the present invention. .

As a method for obtaining the methyl methacrylate polymer (A) or (B) of the present invention, a well-known method for industrially producing an acrylic resin is used. That is, it is a suspension polymerization method, a continuous bulk polymerization method, or an emulsion polymerization method. The suspension polymerization method and the continuous bulk polymerization method are particularly suitable.

The weight ratio (A) / (B) of the methyl methacrylate polymer in the present invention is 0/100 to 90/10. When the ratio of (B) is 10 or less, the effect of suppressing uneven thickness after secondary molding becomes small.

In order to mix these methyl methacrylate resin compositions into an extruded plate, a known method of mixing a thermoplastic resin and forming an extruded plate can be used. For example,
There is a method of once melt-kneading each component, and the melt-kneading includes a method of using a generally used kneading device such as a single-screw or twin-screw extruder and various kneaders. Moreover,
It is also possible to form an extruded plate in one stage by using the molding method described below.

In order to form the methyl methacrylate resin composition into an extruded plate, after melt-kneading with a uniaxial or biaxial extruder, etc., a resin plate is basically manufactured through two or more rolls. There is a method, for example, "Handbook of Plastic Processing Technology"
(Published by Nikkan Kogyo Shimbun on October 20, 1979) 25
Pages 4-260: "Extruder""Die""Glossy roll unit (polishing roll machine)" Roller table "" Ear trimming device "as described in Japanese Patent Publication No. 61-46305
There is a so-called extrusion molding method using an apparatus having a configuration of "take-off roll" and "cutting and stacking apparatus".

The thickness of the methyl methacrylate resin extruded plate of the present invention is about 50 μm to 10 mm, but is not particularly limited.

The methyl methacrylate resin extruded plate of the present invention has an extrusion direction (MD) under the general manufacturing conditions for extruded plates.
Direction) The heat shrinkage tends to increase, but in the method of producing an extruded plate from a molten plate-like material through two or more rolls, immediately after peeling from the final roll and not contacting the rolls The surface temperature (Ts) of the resin plate on the side is the thermal deformation temperature (Th) of the methyl methacrylate resin + (5 ° C. to 5 ° C.).
0 ° C.), and for lowering the surface temperature of the resin plate after peeling from the final roll to Th, it takes 5 seconds or more of the value of the thickness of the resin plate expressed in mm as the number of seconds, The peripheral speed difference between the final roll and the take-up roll is 1 / 0.900 to 1 /
By setting the ratio to 0.995, it is possible to impart a low heat shrinkability equal to or higher than that of an ordinary extruded plate.

The Ts can be adjusted by adjusting the temperature of the extruded or rolled molten plate resin before being applied to the roll unit, adjusting the temperature of each roll, and adjusting the residence time on the roll. , The resin plate in contact with the roll is externally heated, or a combination thereof is used.
As described in Japanese Patent No. 6305, it can be extremely easily performed by those skilled in the art.

If Ts is less than Th + 5 ° C., the extruded plate tends to largely contract during secondary molding. Ts is T
When h + 50 ° C. is exceeded, the resin plate is not smoothly peeled off from the roll, so-called tack marks are generated, and the quality of the resin plate tends to be deteriorated.

Generally, the resin plate separated from the roll unit is naturally cooled. However, in the present invention, the heat shrinkage at the time of the secondary molding can be suppressed by adjusting the cooling rate. That is, in order to cool the surface temperature (Ts) of the resin plate after peeling from the final roll, it takes a time of 5 seconds or more of the value of the thickness of the resin board expressed in mm as the number of seconds, Lower to deformation temperature (Th). If the cooling time is shorter than this condition, heat shrinkage in the MD direction during secondary molding of the extruded plate tends to increase. Note that this time is up to about 100 times because the productivity decreases if it is too long.

The cooling time of the resin plate may be adjusted by confirming the transition of the temperature of Ts by a known cooling method. For example, the roller table through which the resin plate passes after the final roll has a structure in which the temperature can be adjusted through electric heat or a heat medium, and the cooling rate of the resin plate is adjusted; There are methods such as adjusting the temperature of the atmosphere to adjust the cooling rate of the resin plate; heating the resin plate after the final roll peeling from the outside. Two or more of these methods may be combined.

The peripheral speed difference between the final roll and the take-up roll is 1 /
It is preferably 0.900 / 1 / 0.995. If the speed of the final roll is 1, and the speed of the take-up roll is less than 0.900, the extruded plate may meander depending on the material used. If it exceeds 0.995, heat shrinkage during secondary molding tends to increase. The speed of each roll can be adjusted by those skilled in the art very easily.

After passing through the above cooling conditions, an extruded plate is obtained through known steps thereafter.

The methyl methacrylate resin extruded plate of the present invention is added to a general acrylic resin such as a release agent, an ultraviolet absorber, a colorant, an antioxidant, a heat stabilizer, a plasticizer, etc., if necessary. There is no problem even if various possible additives are mixed.

[0039]

The methyl methacrylate resin extruded plate of the present invention is a normal methyl methacrylate resin extruded plate having a secondary heat which has a complicated shape and a high area expansion rate that remarkably thins the wall. Even if molding is performed, thinning can be reduced. Therefore, the methyl methacrylate resin extruded plate has a relatively complicated structure such as a lighting cover, a bath, and various glazings.
It can be suitably used for applications involving subsequent molding.

[0040]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. The evaluation method is as follows. (1) Reduced viscosity (ηSP / C): In accordance with JIS Z8803,
The reduced viscosity was a value at a concentration of 1 g / dl, and was determined by measuring at 25 ° C in a chloroform solution (dl / g). (2) Weight average molecular weight (Mw) and Z average molecular weight (M
z): Gel permeation chromatography with a differential refractometer and a viscometer (GPC15 manufactured by Waters Waters)
0-CV) was determined from a [molecular weight-elution time] calibration curve of a standard methyl methacrylate polymer. (3) Intermolecular molecular weight between branch points (Mzb): From the above calibration curve and the calibration curve showing the relationship between the intrinsic viscosity and the GPC elution time of the standard methyl methacrylate polymer, the calibration curve showing the relationship between the intrinsic viscosity and the absolute molecular weight was determined. Using this calibration curve, the intrinsic viscosity [η ₂ ] corresponding to the molecular weight Mz value was determined. Next, using a universal calibration curve showing the relationship between the product of the absolute molecular weight and the intrinsic viscosity with respect to the elution time of the standard methyl methacrylate polymer, a calibration curve showing the relationship between the absolute molecular weight and the intrinsic viscosity of the polymer to be measured was obtained. The intrinsic viscosity [η ₁ ] corresponding to the molecular weight Mz value was determined using this calibration curve. Using [η ₁ ] and [η ₂ ], Bz is obtained from the above [Equation 1], and then Mzb is obtained from the above [Equation 2].
Was calculated. (4) Gel fraction: After dissolving 3 parts by weight of a methacrylic polymer in 100 parts by weight of acetone, the weight of the polymer before dissolving the weight of the insoluble matter which was dried by filtration through a 400-mesh wire net was dissolved. It was divided by and the gel fraction was calculated. (5) Resin plate surface temperature: The resin surface temperature was measured with a contact thermometer (TD-150, manufactured by Shibaura Electronics). (6) Bending strength: measured according to ASTM-D790 (kgf /
cm ² ). (7) Surface gloss: Measured by a 60 degree reflection with a gloss meter (UGV-4D manufactured by Suga Test Instruments Co., Ltd.) according to JIS Z-8741 gloss measurement. (8) Heat distortion temperature (Th): Measured according to ASTM D-648. (9) Heat shrinkage ratio: The obtained sheet was 10 cm × 10 c
After cutting into m and heating in an oven at Th + 50 ° C. for 1 hour, the length in the MD direction was measured, and the ratio with that before heating was taken as the heat shrinkage ratio. (10) Push-up molding: A 30 cm × 20 cm extruded plate is heated to 150 ° C. in an oven, and a push-up molding machine (Osaka Itaki Seisakusho TF-300 type, push-up area 10 cm × 5 cm, push-up height 10 cm) is used. Using, a molded product as shown in FIG. 1 was obtained. (11) Plate thickness measurement: Point A shown in Fig. 1 of the push-up molded product
Ultrasonic thickness gauge (made by PANAMETRICS)
It was measured by ULTRASONIC GAGE MODEL 5222). Points A and B are 4.5 cm below the center of the long side and the short side at the top, respectively.

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

The extrusion equipment used in the examples is as follows. -Extruder: screw diameter 40 mm, uniaxial, manufactured by Tanabe Plastic Co., Ltd.-T die: width 220 mm, lip interval 4 mm-roll unit: diameter 200 mm, width 300 mm, consisting of 3 polishing rolls. -Roller table: diameter 50 mm, width 350 mm, heating medium heating type 3 rolls 30 cm, 50 cm, 80
Installed at intervals of cm.

Reference Examples 1 to 4 "Preparation of Methyl Methacrylate Polymer (B)" 4 parts by weight of methyl acrylate and 0.3 parts of lauroyl peroxide were added to 96 parts by weight of methyl methacrylate in a 200-liter SUS autoclave. Parts by weight, n-dodecyl mercaptan and 1,6-hexanediol diacrylate as shown in [Table 1], 200 parts by weight of deionized water and 1 part by weight of sodium polymethacrylate were added and mixed, and heated under a nitrogen atmosphere. The temperature was raised, polymerization was started at 80 ° C., and after 90 minutes, polymerization was further performed at 100 ° C. for 60 minutes.
After polymerization, washing, dehydration and drying were performed to obtain a beaded polymer. The obtained polymer was evaluated. The evaluation results are shown in [Table 1].
Shown in

[0044]

[Table 1]

Examples 1 to 6 and Comparative Examples 1 to 6 As a methacrylic polymer (A), a suspension of a monomer mixture of methyl methacrylate (94% by weight) and methyl acrylate (6% by weight) was suspension polymerized. The copolymer beads thus obtained (weight average molecular weight 120,000: straight chain) and the amount of the methacrylic polymer (B) produced in Reference Example shown in [Table 2] were mixed in a Henschel mixer, and then the extruder was used. After melt kneading at a resin temperature of 265 ° C., an extruded plate was obtained under the conditions shown in [Table 2] and [Table 3]. The evaluation results of the obtained sheet are shown in [Table 2] and [Table 3].

[0046]

[Table 2]

[0047]

[Table 3]

[Brief description of drawings]

FIG. 1 is a diagram showing a shape of a push-up molded product in an example.

[Explanation of symbols]

 A Measurement point of thickness of molded product B Measurement point of thickness of molded product

Claims (3)

[Claims] 1. A linear methyl methacrylate-based polymer (A) having a weight average molecular weight of 70,000 to 200,000 and a weight average molecular weight of 80,000 to 400,000, which are defined using the Z average molecular weight. Methacrylic acid comprising a methyl methacrylate-based polymer (B) having a branched structure having a molecular weight between branch points of 30,000 to 500,000 and a weight ratio (A) / (B) of 0/100 to 90/10. Methyl resin extruded plate. 2. A methyl methacrylate polymer (B) having a branched structure, wherein the ratio of the polymer having a molecular weight of 300,000 or more, and the reduced viscosity of the polymer is 0.7 dl / g or less, {[14 × the reduced viscosity value−6.8] to [14 ×
(Reduced viscosity value + 11.2]} (wt%), when the reduced viscosity is 0.7 dl / g or more, {[40 × the reduced viscosity value−2
5] to [40 x the reduced viscosity value-7]} (% by weight). The methyl methacrylate resin extruded plate according to claim 1. 3. A linear methyl methacrylate-based polymer (A) having a weight average molecular weight of 70,000 to 200,000 and a weight average molecular weight of 80,000 to 400,000, which is defined using the Z average molecular weight. Methacrylic acid comprising a methyl methacrylate-based polymer (B) having a branched structure having a molecular weight between branch points of 30,000 to 500,000 and a weight ratio (A) / (B) of 0/100 to 90/10. A method for producing an extruded plate from a molten plate-like material through a methyl-based resin composition through two or more rolls, the surface of the resin plate on the side not in contact with the roll immediately after being peeled from the final roll. The temperature (Ts) is the heat distortion temperature (Th) of the methyl methacrylate resin + (5 ° C to 50 ° C)
And the surface temperature of the resin plate after peeling from the final roll is T
In order to lower the thickness to h, it takes 5 seconds or more the value of the thickness of the resin plate expressed in mm as the number of seconds, and the peripheral speed difference between the final roll and the take-up roll is 1 / 0.900 to 1 /0.9
95 is set to 95, The manufacturing method of the methylmethacrylate type resin extrusion board characterized by the above-mentioned.