JP2011225760A - Method for production of imide resin improved in moldability - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoplastic resin excellent in transparency, heat resistance and further moldability.SOLUTION: There is provided an imide resin which is obtained by adding an imidizing agent to poly(meth)acrylic acid ester in an extruder to react and then reacting by adding an esterifying agent before removal of volatile portions, and which has ≤0.05 of the acid value expressed by the mm equivalent/g of imide resin for the amount of acids and acid anhydrides on the imide resin. There is also provided a molded body having reduced viscosity derived from the amount of the acid component, improved in peelability from a metallic roll and also improved in defect such as foaming being generated when molded.

Description

  The present invention relates to an imide resin having improved moldability, an optical resin composition containing the imide resin, and a molded body.

  In recent years, electronic devices have become more and more miniaturized, and have been used for various purposes by taking advantage of light weight and compactness, as represented by notebook personal computers, mobile phones, and portable information terminals. On the other hand, in the field of flat panel displays such as liquid crystal displays and plasma displays, it is also required to suppress an increase in weight due to an increase in screen size.

  In applications that require transparency, such as electronic devices as described above, there is an increasing trend to replace members that have conventionally used glass with resins having good transparency.

  Polymethyl methacrylate is widely used as a plastic material having excellent transparency, weather resistance and mechanical properties. However, since polymethyl methacrylate has a low heat distortion temperature, it cannot be used in a field requiring heat resistance, and there has been a strong demand for improvement in heat resistance. As a method for improving the heat resistance of polymethyl methacrylate, a method of imidizing polymethyl methacrylate is known. A method for producing an imide resin using an extruder is described in Patent Document 1, for example.

  However, imidized resins obtained by treating polymethyl methacrylate and the like with an imidizing agent often generate carboxyl groups and acid anhydride groups in the resin side chain during the imidation reaction. In some cases, the compatibility with the polymer deteriorates, or the viscosity increase is affected, leading to deterioration of molding processability. Thus, a technique for converting a carboxyl group or an acid anhydride group contained in an imide resin into an ester group or the like with a reagent such as dimethyl carbonate has been found (for example, see Patent Document 2). Moreover, the method of imidating acrylic resins, such as polymethylmethacrylate, using a tandem type extruder is known (for example, refer patent document 3).

U.S. Pat. No. 4,246,374 U.S. Pat. No. 4,727,117 JP2008-273140

  However, even if the acid component is reduced by esterification as in the above-mentioned patent document, it can be peeled off from the metal roll, which is considered to be derived from the acid component at the time of molding, specifically at the time of melt extrusion film formation. There was room for improvement.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a transparent imide resin having improved moldability and superior heat resistance compared to polymethyl methacrylate.

  In order to solve the above-mentioned problems, the present inventor, as a result of earnest research, removes volatile components after adding an imidizing agent to the extruder and reacting when producing an imide resin using an extruder. It has been found that the releasability at the time of film formation is greatly improved by adding only the esterifying agent and causing the reaction.

That is, the present invention provides a method for producing an imide resin using an extruder,
a) an imidization step in which an imidizing agent is reacted with a polymethacrylic acid ester unit;
b) a step of esterifying the imide resin obtained in the step a) without adding an esterification catalyst, and c) a volatile component removal step is not included between the steps a) and b). A method for producing an imide resin characterized in that (Claim 1)
The method for producing an imide resin according to claim 1, wherein the acid value expressed in milliequivalents per gram of the imide resin is 0.05 or less. ,
The method for producing an imide resin according to any one of claims 1 to 2, wherein the esterifying agent used in the step b) is orthoformate triester or orthoacetate triester (claim 3). )
The method for producing an imide resin according to any one of claims 1 to 3, wherein a co-direction meshing twin screw extruder is used (Claim 4).
Furthermore, the manufacturing method of the molded article of an imide resin characterized by including the process of heat-melting the imide resin obtained by the method of any one of Claim 1 to 4 (Claim 5).
It is about.

  The method for producing an imide resin of the present invention can remarkably reduce the acid value, and can improve the moldability of the produced resin.

The schematic of the film forming equipment used for the moldability evaluation of an Example is shown.

The present invention provides a method for producing an imide resin using an extruder,
a) an imidization step in which an imidizing agent is reacted with a polymethacrylic acid ester unit;
b) a step of esterifying the imide resin obtained in the step a) without adding an esterification catalyst;
The present invention relates to a method for producing an imide resin characterized in that c) does not include a volatile component removal step between the step a) and the step b).

  The imide resin of the present invention refers to a resin having an imide group obtained by modifying an acrylic resin. For example, there is a reaction in which a part of the functional group of the acrylic resin is imidized or esterified. The production method of the present invention is an acrylic resin containing a repeating unit represented by at least the following general formulas (1) and (2) (in the present specification, the raw material is not clarified particularly from the context). The term “imide resin” refers to a production method applicable to imidized acrylic resins such as imidized acrylic resins and esterified modified imidized acrylic resins.

  Preferred examples of the imide resin include imidized acrylic resins. An example of an imidized acrylic resin is shown below.

  Examples of the imidized acrylic resin include acrylic resins containing repeating units represented by the following general formulas (1) and (2).

(However, R ¹ and R ² each independently represent hydrogen or an alkyl group having 1 to 8 carbon atoms, and R ³ represents hydrogen, an alkyl group having 1 to 18 carbon atoms, or a cycloalkyl having 3 to 12 carbon atoms. Or a substituent containing an aromatic ring having 5 to 30 carbon atoms.) As preferred glutarimide units, R ¹ and R ² are hydrogen or a methyl group, and R ³ is hydrogen, a methyl group, or a cyclohexyl group. It is. The case where R ¹ is a methyl group, R ² is hydrogen, and R ³ is a methyl group is particularly preferred.
The glutarimide unit may be a single type or may include a plurality of types in which R ¹ , R ² , and R ³ are different.
As a 2nd structural unit which comprises the said acrylic resin, it is an acrylic ester or methacrylic ester unit represented by following General formula (2).

(However, R ⁴ and R ⁵ each independently represent hydrogen or an alkyl group having 1 to 8 carbon atoms, and R ⁶ represents hydrogen, an alkyl group having 1 to 18 carbon atoms, or a cycloalkyl having 3 to 12 carbon atoms. Or a substituent containing an aromatic ring having 5 to 30 carbon atoms.) The (meth) acrylic acid compound or the (meth) acrylic acid ester compound is not particularly limited. For example, methyl (meth) Examples include acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, and the like. In addition, acid anhydrides such as maleic anhydride or half esters of these and linear or branched alcohols having 1 to 20 carbon atoms; acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, Α, β-ethylenically unsaturated carboxylic acids such as crotonic acid, fumaric acid and citraconic acid can also be imidized and used in the present invention. Of these, methyl methacrylate is particularly preferred.
These second structural units may be of a single type, and may include a plurality of types in which R ⁴ , R ⁵ , and R ⁶ are different.
Furthermore, the acrylic resin to which the production method of the present invention can be applied may contain an aromatic vinyl unit represented by the following general formula (3).

(However, R ⁷ represents hydrogen or an alkyl group having 1 to 8 carbon atoms, and R ⁸ represents an aryl group having 6 to 10 carbon atoms.) Preferred aromatic vinyl structural units include styrene and α-methyl. Examples include styrene. Of these, styrene is particularly preferred.
These third structural units may be of a single type or may include a plurality of types in which R ⁷ and R ⁸ are different.

  The content of the glutarimide unit represented by the general formula (1) in the acrylic resin is preferably 1% by weight or more of the acrylic resin. The preferable content of the glutarimide unit is 1 to 95% by weight, more preferably 1.5 to 90% by weight, and still more preferably 2 to 80% by weight. When a glutarimide unit is smaller than this range, the heat resistance of the acrylic resin obtained may be insufficient, and transparency may be impaired. On the other hand, if it exceeds this range, the heat resistance is unnecessarily increased and it becomes difficult to mold, and the mechanical strength of the resulting molded body becomes extremely brittle, and the transparency may be impaired.

  The acrylic resin may further contain an aromatic vinyl unit represented by the general formula (3). The content of the aromatic vinyl unit represented by the general formula (3) in the acrylic resin is preferably 80% by weight or less based on the total repeating units of the acrylic resin. The preferred content of the aromatic vinyl unit is 1 to 80% by weight, more preferably 1.5 to 70% by weight, and still more preferably 2 to 60% by weight. When the aromatic vinyl unit is larger than this range, the resulting imide resin may have insufficient heat resistance and a small photoelastic coefficient.

  Furthermore, the fourth structural unit may be copolymerized in the acrylic resin to which the production method of the present invention can be applied, if necessary. A constitution obtained by copolymerizing a nitrile monomer such as acrylonitrile and methacrylonitrile, and a maleimide monomer such as maleimide, N-methylmaleimide, N-phenylmaleimide, N-cyclohexylmaleimide as the fourth structural unit Units can be used. These may be directly copolymerized in an acrylic resin or may be graft copolymerized.

  The methyl methacrylate-styrene copolymer to which the production method can be applied is a (meth) acrylic acid compound or a (meth) acrylic acid ester compound that can be imidized, or a copolymer thereof or (meth). If an acrylic acid compound or (meth) acrylic acid ester compound and a styrene compound are included as essential components, even a linear (linear) polymer, a block polymer, a core-shell polymer, a branched polymer, a ladder polymer, It may be a crosslinked polymer. The block polymer may be an A-B type, A-B-C type, A-B-A type, or any other type of block polymer. There is no problem even if the core-shell polymer is composed of only one core and only one shell, or each layer is a multilayer.

  The imide resin that can be produced by the production method of the present invention preferably has a weight average molecular weight of 10,000 to 200,000. When the weight average molecular weight is not more than the above value, the mechanical strength of the molded product is insufficient. When the weight average molecular weight is not less than the above value, the viscosity at the time of melting may be high, and the productivity at the time of molding may be reduced. .

  The glass transition temperature of the imide resin that can be produced by the production method of the present invention is preferably 100 ° C. or higher, more preferably 110 ° C. or higher, and further preferably 120 ° C. or higher.

  If necessary, another acrylic resin can be added to the imide resin that can be produced by the production method of the present invention.

  Next, the manufacturing method of this invention is demonstrated.

The present invention provides a method for producing an imide resin using an extruder,
a) an imidization step in which an imidizing agent is reacted with a polymethacrylic acid ester unit;
b) a step of esterifying the imide resin obtained in the step a) without adding an esterification catalyst;
The imide resin production method is characterized in that c) does not include a volatile component removal step between the steps a) and b).

Below, each process is demonstrated.
a) Process The polymethacrylic acid ester unit used in this process is not particularly limited as long as it is a polymerized methacrylic acid ester unit. Examples of the methacrylic acid ester unit include methyl methacrylate, ethyl methacrylate, butyl methacrylate, and isobutyl. Examples include methacrylate, t-butyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate and the like.

The imidizing agent used in the present invention is not particularly limited as long as polymethyl methacrylate can be imidized. For example, methylamine, ethylamine, n-propylamine, i-propylamine, n-butylamine, i-butylamine , Aliphatic hydrocarbon group-containing amines such as tert-butylamine and n-hexylamine, aromatic hydrocarbon group-containing amines such as aniline, toluidine and trichloroaniline, and alicyclic hydrocarbon group-containing amines such as cyclohexylamine It is done. In addition, urea compounds that generate these amines by heating, such as urea, 1,3-dimethylurea, 1,3-diethylurea, and 1,3-dipropylurea can also be used. Of these imidizing agents, methylamine is preferable from the viewpoint of cost and physical properties.
The amount of the imidizing agent added is determined by the imidization rate for expressing necessary physical properties.

b) Step In this step, an esterification catalyst is added to the resin obtained in the step a), and the acid component in the resin produced in the step a) is esterified.

  Examples of the esterifying agent used in this step include trimethyl orthoformate, triethyl orthoformate, trimethyl orthoacetate, triethyl orthoacetate and the like, and among these, trimethyl orthoacetate is preferable from the viewpoint of price, stability, and ignition point.

  The addition amount of the esterifying agent is not particularly limited as long as the acid value of the imide resin can be less than 0.05 mmol / g, but is preferably 1 part by weight to 100 parts by weight, and more preferably 3 parts by weight to 50 parts by weight. . When the esterifying agent is larger than this range, a large amount of the esterifying agent remains in the resulting resin, and a side reaction may proceed.

  Usually, when esterifying and modifying an imidized acrylic resin, an esterification catalyst such as a base is used. However, in the production method of the present invention, no esterification catalyst is used. Use only the agent.

  The present invention is characterized in that c) step which is a volatile component removing step is not included between steps a) and b).

  That is, the step of removing volatile components such as vacuum devolatilization from the vent port is not included between the step a) and the step b). More preferably, the steps a) and b) are carried out continuously.

  As the extruder used in the present invention, various types can be used. In particular, it is preferable to apply a twin screw extruder in terms of high kneading ability, and since the kneading ability and productivity are high, the same direction meshing type twin screw extrusion. It is preferable to apply the machine. Moreover, an extruder may be used independently or may be connected in series. It is preferable to install one or more vents for removing volatile components from the extruder. Although the installation location is not particularly limited, for example, even if there is a vent between step a) and step b), that is, between the imidizing agent addition port and the esterification agent addition port, needless to say, devolatilization from this location is Not implemented.

  The extrusion temperature when the imidization reaction or esterification reaction of the acrylic resin is allowed to proceed is in the range of 200 to 350 ° C. 200-330 degreeC is more preferable, and 250-290 degreeC is further more preferable. Below 200 ° C., the melt viscosity of the polymer becomes high and a heavy load is imposed on the operation of the apparatus, and at 350 ° C. and above, resin degradation occurs.

  The internal pressure of the extruder during the imidization reaction or esterification reaction is usually in the range of 0.1 MPa to 30 MPa, and more preferably in the range of 0.5 MPa to 10 MPa. If the pressure is 0.5 MPa or less, the reaction efficiency of the imidizing agent or the esterifying agent becomes low, and the reaction hardly proceeds. If it is 10 MPa or more, an extreme screw configuration for resin sealing is required, the resin temperature becomes high, and the resin is decomposed and colored.

  The number of revolutions of the extruder is preferably 10 rpm to 2000 rpm, and more preferably 20 rpm to 1000 rpm. If it is 10 rpm or less, productivity and devolatilization efficiency are deteriorated, and if it is 2000 rpm or more, the electric energy of the extruder main motor becomes large, and further heat generation of the resin becomes intense, resulting in resin deterioration.

  In the present imide resin, generally used catalysts, antioxidants, heat stabilizers, plasticizers, lubricants, ultraviolet absorbers, antistatic agents, colorants, shrinkage preventing agents and the like are within the scope of the purpose of the present invention. May be added.

  The imide resin according to the present invention has properties such as high tensile strength and bending strength, solvent resistance, thermal stability, good optical properties, and weather resistance.

  The imide resin obtained in the present invention may be used by itself or may be blended with other thermoplastic polymers. Acrylic resins alone or blends with other thermoplastic resins can be processed into various molded products by various plastic processing methods such as injection molding, extrusion molding, blow molding, compression molding and the like. It can also be molded by a casting method using a polymer solution obtained by dissolving an acrylic resin obtained in the present invention such as methylene chloride in a solvent for dissolving the acrylic resin.

  When molding, generally used antioxidants, heat stabilizers, plasticizers, lubricants, UV absorbers, antistatic agents, colorants, shrinkage inhibitors, etc. are added within the range that does not impair the purpose of the present invention. May be.

  The molded product comprising the step of heating and melting the imide resin of the present invention includes, for example, a camera, a VTR, a photographing lens for a projector, a finder, a filter, a prism, a Fresnel lens, and other image fields, a CD player, Lens field such as optical disk pickup lens such as DVD player and MD player, optical recording field for optical disk such as CD player, DVD player and MD player, liquid crystal display such as light guide plate for liquid crystal, polarizer protective film and retardation film Film, surface protection film and other information equipment fields, optical fibers, optical switches, optical connectors and other optical communication fields, automotive headlights, tail lamp lenses, inner lenses, instrument covers, sunroofs and other vehicle fields, glasses and contact lenses, Inside Environmental lenses, medical devices such as medical supplies that require sterilization, road translucent plates, lenses for paired glass, lighting windows and carports, lighting lenses and covers, and sizing for building materials, It can be used for microwave cooking containers (tableware), housings for home appliances, toys, sunglasses, stationery, and the like. The molded product does not necessarily need to be melted by heating and can be molded by dissolving in a solvent.

  The present invention will be described in more detail based on examples, but the present invention is not limited to these examples. In addition, each measuring method of the physical property measured in the following Examples and Comparative Examples is as follows.

(1) Measurement of imidation rate The pellet of the product was used as it was, and IR spectrum was measured at room temperature using TravelIR manufactured by SensIR Technologies. From the obtained spectrum, the absorption intensity (Abs Ester) attributed to the ester carbonyl group of 1720 cm ^-1, the imidization ratio from the ratio of the absorption intensity assignable to an imide carbonyl group of 1660cm ^-1 (Abs imide) (Im %). Here, the imidation rate refers to the proportion of the imide carbonyl group in all carbonyl groups.

(2) Measurement of ratio of acid component remaining in resin (acid value) 0.3 g of the product was dissolved in 37.5 ml of methylene chloride, and 37.5 ml of methanol was added. Two drops of 1 wt% phenolphthalein ethanol solution were added to this solution, 5 ml of 0.1N aqueous sodium hydroxide solution was added, and the mixture was stirred for 1 hour. 0.1N hydrochloric acid was added dropwise to this solution, and the amount of 0.1N hydrochloric acid added (Aml) until the reddish purple color of the solution disappeared was measured.

  Next, two drops of 1 wt% phenolphthalein ethanol solution were added to a mixed solution of 37.5 ml of methylene chloride and 37.5 ml of methanol. To this, 5 ml of 0.1N sodium hydroxide aqueous solution was added and stirred for 1 hour. 0.1N hydrochloric acid was added dropwise to this solution, and the amount of 0.1N hydrochloric acid added (Bml) until the reddish purple color of the solution disappeared was measured.

The acid value remaining in the resin was defined as Cmmol / g, and the following formula was used.
C = 0.1 × ((B−A) /0.3)

(Molding processability)
After the devolatilized imide resin obtained in Examples and Comparative Examples was dried at 100 ° C. for 5 hours, it was extruded at 260 ° C. using a 40 mmφ single-screw extruder and a 400 mm wide T-die, and obtained by extrusion sandwich molding. The obtained sheet-like molten resin was cooled with a cooling roll to obtain a film having a width of 300 mm and a thickness of 150 μm. Refer to FIG. 1 for the relationship between the touch roll, cast roll, and cooling roll in the film forming equipment.

Table 1 shows the acid value and molding processability of the resulting imide resin.
Judgment of molding processability evaluated the peelability to the cast roll of molten resin. In the evaluation, “◎” was very good, “◯” was good, “Δ” was bad, and “×” was very bad.

Example 1
An esterified imidized acrylic resin was produced using a polymethyl methacrylate resin (Mw = 105,000), monomethylamine as an imidizing agent, and trimethyl orthoacetate as an esterifying agent. The used extruder is a mesh type co-rotating twin screw extruder having a diameter of 70 mm and 19 divided barrels, and has a vent port in the 18th barrel from the upstream side of the extruder. The set temperature of each temperature control zone of the extruder was 230 to 250 ° C., and the screw rotation speed was 55 rpm. After supplying the resin from the hopper at 150 kg / hr and melting and filling the resin with a kneading block, 2.0 parts by weight of monomethylamine is injected into the resin from the seventh barrel from the upstream side using a nozzle. did. Further, 7.0 parts by weight of trimethyl orthoacetate was continuously injected from the 11th barrel from the upstream side using a nozzle. Thereafter, the by-product after reaction and excess methylamine were removed by reducing the pressure at the vent port to -0.092 MPa. The resin that came out as a strand from a die provided at the exit of the extruder was cooled in a water tank and then pelletized with a pelletizer. The imidization ratio and acid value of the obtained esterified imidized acrylic resin were measured. The measurement results are shown in Table 1.

(Example 2)
In Example 1, all was carried out in the same manner as Example 1 except that the esterifying agent to be injected was trimethyl orthoformate.

(Comparative Example 1)
An imidized acrylic resin was produced using polymethyl methacrylate resin (Mw = 105,000) and monomethylamine as an imidizing agent. The used extruder is a mesh type co-rotating twin screw extruder having a diameter of 70 mm and 19 divided barrels, and has a vent port in the 18th barrel from the upstream side of the extruder. The set temperature of each temperature control zone of the extruder was 230 to 250 ° C., and the screw rotation speed was 55 rpm. After supplying the resin from the hopper at 150 kg / hr and melting and filling the resin with a kneading block, 2.0 parts by weight of monomethylamine is injected into the resin from the seventh barrel from the upstream side using a nozzle. did. By-products and excess methylamine after the reaction were removed by reducing the pressure at the vent port to -0.092 MPa. The resin that came out as a strand from a die provided at the exit of the extruder was cooled in a water tank and then pelletized with a pelletizer. The imidization ratio and acid value of the obtained imidized acrylic resin were measured. The measurement results are shown in Table 1.

(Comparative Example 2)
An esterified imidized acrylic resin was produced using the imidized acrylic resin obtained in Comparative Example 1 and trimethyl orthoacetate as the esterifying agent. The used extruder is a mesh type co-rotating twin screw extruder having a diameter of 70 mm and 19 divided barrels, and has a vent port in the 18th barrel from the upstream side of the extruder. The set temperature of each temperature control zone of the extruder was 230 to 250 ° C., and the screw rotation speed was 55 rpm. After supplying the resin from the hopper at 150 kg / hr and melting and filling the resin with the kneading block, 7.0 parts by weight of trimethyl orthoacetate was added to the resin using the nozzle from the seventh barrel from the upstream side. Injected. By-products after the reaction and excess trimethyl orthoacetate were removed by reducing the pressure at the vent port to -0.092 MPa. The resin that came out as a strand from a die provided at the exit of the extruder was cooled in a water tank and then pelletized with a pelletizer. The imidization ratio and acid value of the obtained esterified imidized acrylic resin were measured. The measurement results are shown in Table 1.

(Comparative Example 3)
The same procedure as in Example 1 was conducted except that the esterifying agent to be injected was changed to dimethyl carbonate.

(Evaluation results)
After reacting by adding an imidizing agent, before removing the volatile matter, adding an orthoformic acid triester or orthoacetic acid triester as an esterifying agent causes the acid value to drop significantly. Molding processability was greatly improved. Moreover, when dimethyl carbonate was added as an esterifying agent, the internal pressure fluctuation of the extruder became severe, and extrusion became impossible.

1. Touch roll 2. Cast roll Cooling roll 1
4). Cooling roll 2
5). Cooling roll 3
6). T-die

Claims (5)

In the method for producing an imide resin using an extruder,
a) an imidization step in which an imidizing agent is reacted with a polymethacrylic acid ester unit;
b) a step of esterifying the imide resin obtained in the step a) without adding an esterification catalyst;
A method for producing an imide resin, characterized in that c) does not include a volatile component removing step between the steps a) and b). 2. The method for producing an imide resin according to claim 1, wherein an acid value in which the amount of acid on the imide resin is expressed in milliequivalents per gram of the imide resin is 0.05 or less.   The method for producing an imide resin according to any one of claims 1 to 2, wherein in the step b), the esterifying agent to be used is orthoformate triester or orthoacetate triester. The method for producing an imide resin according to any one of claims 1 to 3, wherein the same direction meshing type twin screw extruder is used. Furthermore, the manufacturing method of the molded article of an imide resin characterized by including the process of heat-melting the imide resin obtained by the method of any one of Claim 1 to 4.

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