TWI466904B - Polymethacrylate composition - Google Patents

Description

Polymethacrylate composition

The present invention relates to a polymethacrylate composition, and more particularly to a polymethacrylate composition which is excellent in thermal stability and is not easily yellowed.

Polymethacrylate is a widely used polymer with good evaluation in formability, physical properties and mechanical properties, and its light transmittance is better than that of glass (up to 92%). The molded article looks good. One of the most excellent polymer transparent materials, known as "plexiglass", is often used as a variety of optical components or consumer goods, such as camera lenses, lenses, automotive taillights, billboards and so on.

Although polymethacrylate has the above-mentioned excellent optical properties and process formability, the thermal stability is slightly insufficient. Generally, the heat stability property is improved by increasing the molecular weight of the resin, but the molecular weight is too high, which leads to a decrease in fluidity. High molecular weight resins often require higher processing temperatures or even incapable processing, for example, at higher processing temperatures. When performing extrusion or injection molding, the chance of thermal deterioration increases greatly. In order to improve the thermal stability of polymethacrylate, it is usually transmitted by means of increasing the molecular weight, but if the molecular weight is too high, the fluidity is poor and the subsequent processing is not easy.

In addition, when polymethacrylate is used as an optical element, due to weather influence or long-time irradiation, yellowing often occurs after a period of use, which seriously affects transparency and even causes the light source to pass through the polymethacrylate. The color and brightness are completely changed. Generally by adding antioxidants, Such as octadecyl-(3,5-bis-tert-butyl-4-hydroxyphenyl)-propionate, triethylene glycol-bis[3-(3-tert-butyl-5-methyl) 4-hydroxyphenyl)-propionate], tetrakis[methylene-3-(3,5-bis-tert-butyl-4-hydroxyphenyl)-propionate]methane, 2-third Butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate, 2,2'-methylene-bis(4-methyl -6-tert-butylphenol), 2,2'-thiobis(4-methyl-6-tert-butylphenol), 2,2'-thio-diethylene-di [3-( 3,5-bis-tert-butyl-4-hydroxyphenyl)propionate], 2,2'-ethylenediamine-bis[ethyl-3-(3,5-bis-tert-butyl- 4-hydroxyphenyl)propionate], but the effect is limited, can not really solve the yellowing problem of polymethacrylate.

EP 0 322 166 and US Pat. No. 5,054, 581 disclose the use of compounds of the formula (I) and analogues thereof as antioxidants for polybutadiene rubber. In the process of polybutadiene rubber, the devolatilization temperature is higher than the solution polymerization temperature, and the yellowing may occur in the mixing under the anaerobic environment, and the compound represented by the formula (I) is used as the polybutadiene rubber. The antioxidant can improve the aforementioned problems, but the use of the compound represented by the formula (I) as an antioxidant does not solve the problem of yellowing of the polymethacrylate.

In view of the above, there is still a need to develop a polymethacrylate composition which is more thermally stable and less susceptible to yellowing, in order to meet the needs of the industry for subsequent processing processes and various applications.

A first object of the present invention is to provide a polymethacrylate composition which is excellent in thermal stability and is not easily yellowed.

Thus, the polymethacrylate composition of the present invention comprises: (A) a polymethacrylate having a weight average molecular weight ranging from 50,000 to 150,000, containing methacrylate monomer units of 92 to 99 wt%, and An acrylate monomer unit of 1 to 8 wt%; and (B) an antioxidant comprising a compound represented by the formula (I) and a compound represented by the formula (II):

Wherein the (B) antioxidant is used in an amount ranging from 0.005 parts by weight or more to less than 0.3 parts by weight based on 100 parts by weight of the total of the (A) polymethacrylate.

A second object of the present invention is to provide a polymethacrylate composition which is excellent in thermal stability and is not easily yellowed.

Thus, a polymethacrylate composition of the present invention comprises: a polymethacrylate copolymer having a weight average molecular weight ranging from 50,000 to 150,000, containing methacrylate monomer units of 92 to 99 wt%, and Acrylate monomer unit 1 to 8 wt%; a compound represented by the formula (I): As shown in formula (II): Wherein the compound represented by the formula (I) and the compound represented by the formula (II) are used in an amount ranging from 0.005 parts by weight or more to less than 0.3% by weight based on 100 parts by weight of the polymethacrylate copolymer. And in the polymethacrylate composition, the content of the compound represented by the formula (II) is in the range of 0.1 to 10 ppm.

The effect of the invention is that the compound represented by formula (I) and formula (II) is present in the polymethacrylate composition, so that the polymethacrylate composition has better thermal stability and resistance. Yellow degeneration, suitable for high temperature injection molding and high temperature extrusion.

The polymethacrylate composition of the present invention comprises: (A) polymethacrylate having a weight average molecular weight ranging from 50,000 to 150,000, containing methacrylate monomer units of 92 to 99 wt%, and an acrylate a monomer unit of 1 to 8 wt%; and (B) an antioxidant comprising a compound of the formula (I) and a compound of the formula (II):

Wherein the (B) antioxidant is used in an amount ranging from 0.005 parts by weight to less than 0.3 parts by weight, based on 100 parts by weight of the total of the (A) polymethacrylate, preferably (B) The oxidizing agent is used in an amount ranging from 0.005 to 0.25 parts by weight, and more preferably, the (B) antioxidant is used in an amount ranging from 0.005 to 0.1 parts by weight.

Preferably, the (A) polymethacrylate is from 92 to 99 wt% of a methacrylate monomer, from 1 to 8 wt% of an acrylate monomer, and optionally added to 0 to 7 wt% of other copolymerizable monomers are polymerized.

Specific examples of the methacrylate monomer include, but are not limited to, n-octyl methacrylate, methyl methacrylate, n-butyl methacrylate, and the like.

Specific examples of the acrylate-based monomer include, but are not limited to, n-hexyl acrylate, methyl acrylate, ethyl acrylate, butyl acrylate, octadecyl acrylate, and the like. The methacrylate monomer and the acrylate monomer may be copolymerized separately or in combination of two or more kinds of monomers to form a copolymer.

Specific examples of the other copolymerizable monomer include, but are not limited to, acrylonitrile, styrene, maleic anhydride, α-methylstyrene, and a combination of the foregoing.

The polymethacrylate obtained by polymerization includes a methacrylate monomer unit and an acrylate monomer unit. Here, the "monomer unit" means a repeating structure formed by polymerization of the above methacrylate monomer or acrylate monomer.

The polymethacrylate has a weight average molecular weight ranging from 50,000 to 150,000; preferably, the polymethacrylate has a weight average molecular weight ranging from 60,000 to 120,000, and more preferably, the polymethacrylate The weight average molecular weight ranges from 65,000 to 75,000.

The (A) polymethacrylate can be prepared by a solution or a bulk polymerization method, preferably in the presence of a solvent to avoid a situation in which the polymerization reaction is difficult to control when the viscosity of the crude polymer rises above a certain value. . The viscosity of the polymethacrylate is usually expressed in terms of solid content, and the amount of the solvent is adjusted so that the solid content of the crude polymer is less than 50% by weight, preferably less than 40% by weight.

The boiling point of the solvent is preferably the same as the boiling point of the main monomer in which the polymerization is carried out. Recently, for example, a solvent similar to the boiling point of the methacrylate monomer is selected, so that the mixture of the solvent and the monomer has a narrow boiling point range, which can reduce the chance of mixing contaminants in the recycled mixture. The process of intermediate fractionation of the monomer and solvent mixture recycled back.

Therefore, preferably, the solvent has a boiling point of 40 to 225 ° C, more preferably a boiling point of 60 to 150 ° C. Specific examples of the solvent may be, for example but not limited to, hexane, heptane, octane, benzene, toluene, p-xylene, o-xylene, m-xylene, ethylbenzene, cyclohexane, cyclodecane, isooctane. And various low boiling hydrocarbon or aromatic hydrocarbon solvents

(A) The polymerization of polymethacrylate is initiated by a radical, and the radical initiator is not particularly limited, and specific examples thereof include an azo compound such as 2,2'-azobisisobutylene. Nitrile [2,2'-Azobis-(isobutyronitrile), hereinafter abbreviated as AIBN], 2,2'-azobis(2-methylbutyronitrile) [2,2'-Azobis-(2-methylbutyronitrile), Abbreviated as AMBN], 2,2'-azobis(2,4-dimethylvaleronitrile), hereinafter referred to as ADVN, etc.; Diacyl peroxides, such as Dilauroyl peroxide, Decanoyl peroxide, Dibenzoyl peroxide (BPO), etc.; Dioxane peroxide (Dialkyl peroxides) compounds, such as 2,5-dimethyl-2,5-t-butylperoxyhexane [2,5-Dimethyl-2,5-di-(t-butylperoxy)hexane], peroxidation Dicumyl peroxide, 1,3-bis(t-butyl peroxy isopropyl)benzene, etc.; Peroxyesters , such as t-butyl peroxypivalate (t- Butylperoxypivalate), 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane, etc.; Peroxycarbonates, such as tert-Amylperoxy 2-ethylhexyl carbonate, 2-ethylhexyl t-butyl peroxycarbonate (tert-Butylperoxy 2- Ethylhexyl carbonate), etc.; peroxydicarbonates, such as Dimyristyl peroxydicarbonate, Di(4-tert-butylcyclohexyl) [Di(4-tert-butylcyclohexyl) Etc.: Peroxyketal compounds such as 3,3,5-trimethylbis(1,1-tert-butylperoxyethane)[1,1-Di(tert-butylperoxy)-3 ,3,5-trimethylcyclohexane], 2,2-di(4,4-di(tert-butylperoxy)cyclohexyl)propane [2,2-Di(4,4-di(tert-butylperoxy)cyclohexyl)propane ], etc.: Hydroperoxides, such as t-Butyl hydroperoxide, Isopropylcumyl hydroperoxide, etc.; others 2,3- 2 Methyl-2,3-benzene 2,3-Dimethyl-2,3-diphenyl-butane, Potassium persulfate, Sodium persulfate, Ammonium persulfate, and the like. Preferably, the initiator is 2,2'-azobisisobutylnitrile. The starter may be used in an amount of from 0.01 to 1 part by weight, preferably from 0.03 to 0.5 part by weight, more preferably from 0.07 to 0.1 part by weight, based on 100 parts by total of the total of the monomer mixture fed. .

In the present invention, the polymerization reaction can be carried out at normal temperature, but in order to increase the polymerization rate, the reaction system can be heated, and the reaction temperature is generally about 5 to The reaction temperature is preferably from 20 to 130 ° C, more preferably from 30 to 100 ° C at 200 ° C.

The polymethacrylate composition of the present invention may be added with other additives as needed, for example, a plasticizer, a processing aid, an ultraviolet stabilizer, a UV absorber, a filler, a reinforcing agent, a colorant, a lubricant, and a charge prevention. Agent, flame retardant, flame retardant, thermal stabilizer, thermal discoloration inhibitor, coupling agent or other additives, etc., the above additives are not limited to being added during the polymerization reaction, after the polymerization reaction, before the coagulation or during the kneading process. .

The slip agent may be, for example but not limited to, metal stearate such as calcium stearate, magnesium stearate, lithium stearate, etidium distearylamine, dimethyl distearate, decyl palmitate, stearin a compound of butyl acrylate, palmitate stearate, polypropionic acid tristearate, n-docosic acid, stearic acid, etc., polyethylene wax, octadecanoic acid wax, carnauba wax ), petroleum wax, etc. The amount of the slip agent added is from 0.03 to 5.0 parts by weight based on 100 parts by weight of the total of the (A) polymethacrylate.

In order to improve extrusion moldability and thermoformability, an acrylate-based processing aid such as a core-shell processing aid having a weight average molecular weight of 500,000 or more may also be added. The ultraviolet absorber is, for example, but not limited to, a Benzotriazole-based compound, a benzophenone-based compound, a cyanoacrylic-based compound, or the like; and the ultraviolet-ray stability is, for example, but not limited to, a hindered amine-based compound. The amount of the above-mentioned substance added is 0.02 to 2.0 parts by weight based on 100 parts by weight of the total amount of the (A) polymethacrylate.

The charge preventing agent may be, for example but not limited to, a low molecular compound such as a tertiary amine compound or a quaternary ammonium salt compound, or a polyamine polyether such as 3- A polymer-based substance having a permanent charge prevention property of a chloro-1,2-propylene oxide polymer. Fillers can be, for example but not limited to, calcium carbonate, alumina, mica. The strengthening agent can be, for example but not limited to, glass fiber, carbon fiber, various whiskers, and the like. The colorant can be, for example but not limited to, titanium oxide, iron oxide, graphite, phthalocyanine dye. The thermal stabilizer may be, for example but not limited to, dibutyltin maleate, a basic magnesium aluminum hydroxycarbonate, and the like, and the thermal discoloration preventive may be, for example but not limited to, a low molecular weight styrene-anhydrous maleic acid copolymer. The amount of the above-mentioned substance added is 0.1 to 1.0 part by weight based on 100 parts by weight of the total amount of the (A) polymethacrylate.

The (B) antioxidant includes a compound represented by the formula (I) and a compound represented by the formula (II):

Wherein the (B) antioxidant is used in an amount ranging from 0.005 parts by weight or more based on 100 parts by weight of the total of the (A) polymethacrylate. It is less than 0.3 part by weight, preferably 0.005 to 0.03 part by weight, more preferably 0.07 to 0.1 part by weight.

Preferably, the compound represented by the formula (II) is contained in the polymethacrylate composition in an amount ranging from 0.1 to 10 ppm, preferably based on 100 parts by weight of the total of the (A) polymethacrylate. The ground is from 0.15 to 5 ppm, more preferably from 0.18 to 3 ppm.

More preferably, the weight ratio of the compound of formula (I) to the compound of formula (II) is 99.615: 0.385.

The use of the polymethacrylate composition of the present invention is not particularly limited, and it can be applied to various moldings of injection molding, compression molding, extrusion molding, blow molding, thermoforming, vacuum molding, and hollow molding. Finished products, such as: plate, film molded products, etc., can be formulated according to the formula to achieve high fluidity, high heat stability and other needs.

The polymethacrylate composition can be obtained by a general mixing and kneading mechanism such as a Brabender plastometer, a Banbury mixer, a kneader-mixer, a roller press, a uniaxial or biaxial extruder. Usually, after mixing and kneading by means of an extruder, the extruded extrudate is cooled and granulated. The polymethacrylate composition is usually kneaded at 160 to 280 ° C, preferably at a temperature of from 180 to 250 ° C, and the mixing and kneading of the components is not particularly limited in order.

The polymethacrylate composition of the present invention comprises: a polymethacrylate copolymer having a weight average molecular weight ranging from 50,000 to 150,000, containing methacrylate monomer units of 92 to 99 wt%, and an acrylate Monomer unit 1 to 8 wt%; compound as shown in formula (I): As shown in formula (II): Wherein the compound represented by the formula (I) and the compound represented by the formula (II) are used in an amount ranging from 0.005 parts by weight or more to less than 0.3, based on 100 parts by weight of the polymethacrylate copolymer. The compound of the formula (II) is contained in an amount ranging from 0.15 to 5 ppm by weight in the polymethacrylate composition.

The description and variations of the polymethacrylate copolymer, the compound of the formula (I) and the compound of the formula (II) are the same as those described above and will not be described herein.

Preferably, the methacrylate monomer unit is a methyl methacrylate monomer unit, and the acrylate monomer unit is a methyl acrylate monomer unit.

The invention will be further illustrated by the following examples, but it should be understood This embodiment is for illustrative purposes only and should not be construed as limiting the invention.

<Chemicals and Instruments>

1. A compound of the formula (I) and a compound of the formula (II): purchased from Yuyi Industrial Co., Ltd. under the trade name "HS-248P", the weight ratio of the compound of the formula (I) to the compound of the formula (II) is 99.615:0.385, Hereinafter referred to as (B-1) antioxidant.

2. Compound of the formula (I): purchased from Yuyi Industrial Co., Ltd. under the trade name "HW-248", containing 99.9 wt% of the compound of the formula (I), hereinafter referred to as (B-2) antioxidant, which cannot be measured a compound of formula (II).

3. Octadecyl-(3,5-bis-t-butyl-4-hydroxyphenyl)-propionate: purchased from Yuyi Industrial Co., Ltd., trade name "I1076", hereinafter referred to as (B-3) )Antioxidants.

4. 2-Terbutyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate [2-t-butyl-6-3 -t-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate]: purchased from Yuyi Industrial Co., Ltd. under the trade name "HW246", hereinafter referred to as (B-4) antioxidant.

<Preparation Examples 1 to 4> Preparation of (A) Polymethyl methacrylate [Preparation Example 1]

93.5 parts by weight of methyl methacrylate, 6.5 parts by weight of methyl acrylate, 0.43 parts by weight of n-dodecylmercaptan, 0.085 parts by weight of 2,2'-azobisisobutyronitrile, and 66 parts by weight of toluene were mixed. Continuously fed into a reaction tank for continuous solution polymerization. The reaction tank was an interlayer having a heat medium oil circulation, and the reaction temperature was maintained at 100 ° C and the pressure was 600 torr. Stir well in the reaction tank to uniformly mix the components and heat the polymer solution to 265 ° C After that, the polymer solution is devolatilized by a continuous devolatilizer under reduced pressure, and then formed into strips by extruding equipment, and after cooling and pelletizing treatment, (A-1) polymethyl methacrylate plastic particles are obtained. .

(A-1) Polymethyl methacrylate plastic particles contain 95.5 wt% of methyl methacrylate monomer unit, 4.5 wt% of methyl acrylate monomer unit, weight average molecular weight of 75,000, and melt flow index (MI)= 9.0.

[Preparation Example 2]

93 parts by weight of methyl methacrylate, 7 parts by weight of methyl acrylate, 0.4 parts by weight of n-dodecyl mercaptan, 0.08 parts by weight of 2,2'-azobisisobutyronitrile, and 66 parts by weight of toluene were mixed. Continuously fed into a reaction tank for continuous solution polymerization. The reaction tank was an interlayer having a heat medium oil circulation, and the reaction temperature was maintained at 100 ° C and the pressure was 600 torr. The reaction vessel is thoroughly stirred to uniformly mix the components, and after heating the polymer solution to 265 ° C, the polymer solution is devolatilized by a continuous devolatilizer under reduced pressure, and then extruded into a strip by means of a press device. And (A-2) polymethyl methacrylate plastic particles are obtained after granulation treatment.

(A-2) Polymethyl methacrylate plastic particles contain 95 wt% of methyl methacrylate monomer unit, 5 wt% of methyl acrylate monomer unit, weight average molecular weight of 110,000, and melt flow index (MI)= 1.8.

[Preparation Example 3]

93.5 parts by weight of methyl methacrylate, 6.5 parts by weight of methyl acrylate, 0.4 parts by weight of n-dodecyl mercaptan, 0.08 parts by weight of 2,2'-azobisisobutyronitrile, and 66 parts by weight of toluene were mixed. Continuously fed into a reaction tank for continuous solution polymerization. The reaction tank is a clamp with a heat medium oil circulation The layer was maintained at a temperature of 100 ° C and a pressure of 600 torr. The reaction vessel is thoroughly stirred to uniformly mix the components, and after heating the polymer solution to 265 ° C, the polymer solution is devolatilized by a continuous devolatilizer under reduced pressure, and then extruded into a strip by means of a press device. And (3) polymethyl methacrylate plastic particles were obtained after the treatment.

(A-3) Polymethyl methacrylate plastic particles contain 95.5 wt% of methyl methacrylate monomer unit, 4.5 wt% of methyl acrylate monomer unit, weight average molecular weight of 72,000, and melt flow index (MI)= 9.5.

[Preparation Example 4]

93 parts by weight of methyl methacrylate, 7 parts by weight of methyl acrylate, 0.45 parts by weight of n-dodecyl mercaptan, and 0.09 parts by weight of 2,2'-azobisisobutyronitrile were continuously fed into a reaction tank. The continuous solution polymerization is carried out. The reaction tank was an interlayer having a heat medium oil circulation, and the reaction temperature was maintained at 100 ° C and the pressure was 600 torr. The reaction vessel is thoroughly stirred to uniformly mix the components, and after heating the polymer solution to 265 ° C, the polymer solution is devolatilized by a continuous devolatilizer under reduced pressure, and then extruded into a strip by means of a press device. And (A-4) polymethyl methacrylate plastic particles are obtained after the granulation treatment.

(A-4) Polymethyl methacrylate plastic particles contain 95 wt% of methyl methacrylate monomer unit, 5 wt% of methyl acrylate monomer unit, weight average molecular weight of 74,000, and melt flow index (MI)= 10.

<Examples 1 to 8 and Comparative Examples 1 to 10> Preparation of Polymethyl Methacrylate Composition [Example 1]

10 kg of the polymethyl methacrylate of Preparation Example 1, as shown in Table 1. The antioxidant (B-1) was added in the type and amount ratio, and then mixed with an extruder (supplier: Shizhou, model CM-PRA35) at 230 ° C and granulated to obtain a polymethyl methacrylate resin composition. Things. Next, the injection molding machine (supply company Seonohashi Corporation, model SM-90) was subjected to injection treatment at 200 ° C to obtain a polymethyl methacrylate resin of Example 1 having a length of 22 cm, a width of 2 cm, and a thickness of 3 mm. The composition and amount of the composition molded article of the first embodiment are described in detail in Table 1.

[Examples 2 to 7]

The preparation methods of Examples 2 to 4 were substantially the same as those of Example 1, except that the amount of the antioxidant (B-1) was changed.

The preparation methods of Examples 5 to 7 were substantially the same as those of Example 1, except that the polymethyl methacrylate of Preparation Example 2 was used. Among them, Examples 5 and 6 were used together with the (B-1) antioxidant and the (B-2) antioxidant.

The compositions and amounts of Examples 2 to 7 are described in detail in Table 1.

[Embodiment 8]

The preparation method of Example 8 was substantially the same as that of Example 1, except that the polymethyl methacrylate of Preparation Example 4 was used and 0.08 parts by weight of an antioxidant (B-1) was used, wherein the content of the compound of the formula (II) was used. It is 3.08 ppm. The temperature was raised from 100 ° C to 600 ° C at a heating rate of 20 ° C / min under a nitrogen atmosphere, and the temperature at 3% weight loss was measured at 338 ° C.

[Comparative Example 1]

Comparative Example 1 was (A-1) polymethyl methacrylate without adding any antioxidant. The composition and amount of Comparative Example 1 are described in detail in Table 1.

[Comparative Examples 2 to 9]

Comparative Examples 2 to 9 were carried out in substantially the same manner as in Example 1, except that 0.05% by weight of octadecyl alcohol was additionally added to the comparative examples, and Comparative Example 2 contained only 0.03 parts by weight of the compound of the formula (I). Example 3 used (B-3) antioxidant, Comparative Examples 4 to 8 used (B-4) antioxidant, and Comparative Example 9 used 0.3 parts by weight of (B-1) antioxidant. The compositions and amounts of Comparative Examples 2 to 9 are described in detail in Table 1.

[Comparative Example 10]

The procedure of Comparative Example 10 was substantially the same as that of Example 1, except that the polymethyl methacrylate of Preparation Example 4 was used and 0.033 parts by weight of the antioxidant (B-3) was used. The temperature was raised from 100 ° C to 600 ° C at a heating rate of 20 ° C / min under a nitrogen atmosphere, and the temperature at a loss of 3% was measured at 302 ° C.

<Physical test>

The following physical properties of the polymethyl methacrylate compositions of Examples 1 to 7 and Comparative Examples 1 to 9 were respectively analyzed, and the results are shown in Table 1.

1. Relative yellow index:

The molded product of the polymethyl methacrylate resin composition of Comparative Example 1 was measured according to ASTM D-1925, and the 22 cm long optical path of the molded article was measured by a spectrometer (supplier Nippon, model ASA-1) to measure the yellowness index (Yellowness). Index), counted as YI ₁ .

The polymethyl methacrylate resin composition molded articles of Examples 1 to 7 and Comparative Examples 2 to 9 were each measured in the same manner as a yellow index value, which was calculated as YI _x . The yellow index YI _x measured in each of the examples and the comparative examples was compared with the yellow index (YI ₁ ) of Comparative Example 1, and the relative yellow index was calculated by the following formula: YI (%) = YI _x / YI ₁ × 100 %

2. 5% thermogravimetric loss temperature:

0.5 mg of the polymethyl methacrylate resin compositions of Examples 1 to 7 and Comparative Examples 1 to 2 were taken as samples, and placed in a Thermo Gravimetric Analysis (TGA) for analysis and analysis. The conditions were as follows: the temperature was raised from 100 ° C to 600 ° C at a heating rate of 20 ° C / min under a nitrogen atmosphere, and the temperature at 5% weight loss was measured.

As can be seen from Table 1, Comparative Example 1 and Examples 1 to 4 were selected from (A-1) polymethyl methacrylate, and the polymethyl methacrylate composition of Comparative Example 1 was not added with any antioxidant, 5% thermogravimetric loss. The temperature is 323.28 °C. The polymethyl methacrylate compositions of Examples 1 to 4 employ different amounts of the antioxidant (B-1), and the antioxidant (B-1) contains the compound of the formula (I) and the compound of the formula (II), wherein the formula (II) The content of the compound is 0.385% of the antioxidant (B-1), the relative yellowness index of the polymethyl methacrylate compositions is significantly lowered and the 5% thermogravimetric loss temperature can be raised to 331.01 °C.

Comparative Example 2 and Examples 5 to 7 selected (A-2) polymethyl methacrylate, since (A-2) polymethyl methacrylate has a higher molecular weight than (A-1), so 5% thermogravimetric loss The temperature will be higher than (A-1). Comparative Example 2 added 0.03 parts by weight of the antioxidant (B-2), and the antioxidant (B-2) contained only the compound of the formula (I). The relative yellow index of Comparative Example 2 was 115% and the 5% weight loss temperature was 336.1 °C. The polymethyl methacrylate composition has poor yellowing resistance. The polymethyl methacrylate composition of Examples 5 to 7 is used in an amount of 0.03 part by weight of the antioxidant. When the content of the compound of the formula (II) is increased, the polymethyl methacrylate composition is synergistic due to the presence of the antioxidant. The compound of the formula (I) and the compound of the formula (II) are both improved in both yellowing resistance and thermal stability.

In Comparative Example 10 and Example 8, (A-4) polymethyl methacrylate was selected, and it was found from the 3% thermogravimetric loss test result that the polymethyl methacrylate composition of Example 8 had a synergistic effect due to the antioxidant. The compound of the formula (I) and the compound of the formula (II) give a significant improvement in thermal stability.

Comparative Example 3 used (B-3) an antioxidant, which did not significantly improve the yellowing resistance. The antioxidant (B-4) selected in Comparative Examples 4 to 8 was 2-t-butyl-6-(3- Third butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate, although the structure of the antioxidant (B-4) is similar to the compound of the formula (I), the polymethacrylic acid The relative yellowness index of the methyl ester composition also slightly improved, but as the amount of the antioxidant (B-4) increased, the yellowing occurred more severely. Comparative Example 9 used 0.3 parts by weight of the (B-1) antioxidant, and the compound of the formula (II) was found to have a yellowing resistance of 11.55 ppm.

In summary, the polymethacrylate composition of the present invention has a better yellowing resistance and heat resistance by blending an antioxidant containing a compound of the formula (I) and a compound of the formula (II). Stability, it is indeed possible to achieve the object of the present invention.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent.

Claims (8)

A polymethacrylate composition comprising: (A) polymethacrylate having a weight average molecular weight ranging from 50,000 to 150,000, containing methacrylate monomer units of 92 to 99% by weight, and an acrylate series 1 to 8 wt% of the bulk unit; and (B) an antioxidant comprising a compound of the formula (I) and a compound of the formula (II): Wherein the (B) antioxidant is used in an amount ranging from 0.005 parts by weight or more to less than 0.3 parts by weight based on 100 parts by weight of the total of the (A) polymethacrylate. The polymethacrylate composition according to claim 1, wherein the compound represented by the formula (II) is in the polymerization based on the total amount of the (A) polymethacrylate being 100 parts by weight. Methacrylate composition The content ranges from 0.1 to 10 ppm. The polymethacrylate composition according to claim 1, wherein the compound represented by the formula (II) is in the polymerization based on the total amount of the (A) polymethacrylate being 100 parts by weight. The content of the methacrylate composition ranges from 0.15 to 5 ppm. The polymethacrylate composition according to claim 1, wherein the methacrylate monomer unit is selected from the group consisting of n-octyl methacrylate monomer units and methyl methacrylate monomer units. , n-butyl methacrylate monomer unit, or a combination of these. The polymethacrylate composition according to claim 1, wherein the acrylate monomer unit is selected from the group consisting of n-hexyl acrylate monomer units, methyl acrylate monomer units, and ethyl acrylate monomer units. , butyl acrylate monomer unit, octadecyl acrylate monomer unit, or a combination of these. The polymethacrylate composition according to claim 1, wherein the (A) polymethacrylate has a weight average molecular weight ranging from 65,000 to 75,000. A polymethacrylate composition comprising: a polymethacrylate copolymer having a weight average molecular weight ranging from 50,000 to 150,000, containing methacrylate monomer units of 92 to 99% by weight, and an acrylate monomer Unit 1 to 8 wt%; a compound as shown in formula (I): And a compound of formula (II): Among them, in the polymethacrylate composition, the content of the compound represented by the formula (II) is in the range of 0.1 to 10 ppm. The polymethacrylate composition according to claim 7, wherein the methacrylate monomer unit is a methyl methacrylate monomer unit, and the acrylate monomer unit is a methyl acrylate monomer. Body unit.