JP2002161112A - (metha)acrylate type resin of high thermal resistance and low moisture absorption - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a new (metha)acrylate type resin of high thermal resistance and low moisture absorption. SOLUTION: The (metha)acrylate type resin contains 3 wt.% or more of trimethylcyclohexyl (metha)acrylate monomer units based on total monomer units, and trans or cis form is more than 50 mol% of the above trimethylcyclohexyl (metha)acrylate monomer. The above trimethylcyclohexyl (metha)acrylate monomer contains 3,3,5-trimethylcyclohexyl (metha)acrylate or the like. The above trimethylcyclohexyl (metha)acrylate monomer may contain 75 mol% or more of trans form or 75 mol% or more of cis form.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel (meth) acrylic resin having a high heat resistance and a low moisture absorption and a molded article comprising the resin. The (meth) acrylic resin is useful as an information material for optical recording and an electronic material in addition to a general molding material.

[0002]

2. Description of the Related Art Polymethyl methacrylate (PMMA), which is known as a typical (meth) acrylic resin, has excellent transparency and low birefringence, so it can be used not only as a general molding material but also for optical recording. It is also used as an information material. However, PMMA has a problem that its application range is narrow because PMMA has a large water absorption rate and changes in dimensions and warpage due to water absorption occur. Therefore, development of a (meth) acrylic resin having improved hygroscopicity, which can be used as a material for optical devices in a wider range, is desired.

For the purpose of improving the hygroscopicity, methyl methacrylate has been copolymerized with a methacrylate having an alicyclic skeleton. For example, JP-A-58-
JP-A-5318 and JP-A-58-13652 disclose copolymers of methyl methacrylate and cyclohexyl methacrylate. However, such copolymers have improved hygroscopicity, but have reduced heat resistance, so that their use is also limited. Also, Japanese Patent Application Laid-Open No. Sho 60-1
Japanese Patent No. 04110 discloses an example in which methyl methacrylate is copolymerized with 3,3,5-trimethylcyclohexyl methacrylate or the like. However, although the copolymer thus obtained has a significantly improved low hygroscopicity, it is not always satisfactory in terms of heat resistance and moldability.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a novel (meth) acrylic resin having high heat resistance and excellent low moisture absorption, and a molded article comprising the (meth) acrylic resin. Is to provide.

Another object of the present invention is to provide a novel (meth) acrylic resin exhibiting excellent moldability and low moisture absorption, and a molded article made of the (meth) acrylic resin.

[0006]

Means for Solving the Problems The present inventors have proposed (meth)
A detailed study was conducted on a (meth) acrylic resin containing trimethylcyclohexyl acrylate as a monomer component. As a result, a polymer obtained by polymerizing trans-form trimethylcyclohexyl (meth) acrylate and a cis-form (meth) ) A polymer obtained by polymerizing trimethylcyclohexyl acrylate has a low water absorption rate due to a clear difference in glass transition point and the use of the above two stereoisomers (trans-form and cis-form). It was found that heat resistance and moldability could be controlled while maintaining the above. The present invention has been completed based on these findings.

That is, the present invention relates to a (meth) acrylic resin containing 3% by weight or more of trimethylcyclohexyl (meth) acrylate monomer units based on all monomer units, wherein the trimethylcyclohexyl (meth) acrylate is used. Provided is a (meth) acrylic resin in which the ratio of a trans form or a cis form in a monomer exceeds 50 mol%. The trimethylcyclohexyl (meth) acrylate monomer includes 3,3,5-trimethylcyclohexyl (meth) acrylate and the like. In the trimethylcyclohexyl (meth) acrylate monomer, the proportion of the trans form may be 75 mol% or more, and the proportion of the cis form may be 75 mol% or more.

[0008] As the (meth) acrylic resin, trimethylcyclohexyl (meth) acrylate monomer unit 3
To 80% by weight, methyl methacrylate monomer unit 20 to 9
(Meth) acrylic resin comprising 7% by weight and 0 to 30% by weight of other copolymerizable ethylenically unsaturated compound monomer units.

The present invention also provides a molded article comprising the above (meth) acrylic resin. In this specification, “acryl” and “methacryl” may be collectively referred to as “(meth) acryl”.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The (meth) acrylic resin of the present invention comprises (i) trimethylcyclohexyl (meth) acrylate monomer units in an amount of 3% by weight or more, preferably 10% by weight or more of all monomer units. , More preferably 30% by weight or more. When the amount of the trimethylcyclohexyl (meth) acrylate monomer unit is less than 3% by weight of the total monomer units, no improvement in heat resistance or low moisture absorption is obtained.

The trimethylcyclohexyl (meth) acrylate monomer is represented by the following formula (1)

Embedded image (Wherein, R ^a , R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R
⁸ , R ⁹ , R ¹⁰ and R ¹¹ each independently represent a hydrogen atom or a methyl group, and three groups selected from R ^{1 to} R ¹⁰ are methyl groups). Any of these may be used, but 3,3,5-trimethylcyclohexyl (meth) acrylate in which R ³ , R ⁴ and R ⁷ are methyl groups is particularly preferable.

When comparing a polymer containing trimethylcyclohexyl acrylate as a monomer component with a polymer containing trimethylcyclohexyl methacrylate as a monomer component, the latter is superior in terms of heat resistance. .
Therefore, particularly for applications requiring heat resistance, among the monomers represented by the formula (1), trimethylcyclohexyl methacrylate in which ^Ra is a methyl group is more preferable.

In the (meth) acrylic resin of the present invention,
(Ii) The ratio of the trans or cis isomer of the stereoisomer of trimethylcyclohexyl (meth) acrylate is 5
More than 0 mol%, that is, either one isomer is present in excess.

A typical example of the trans form of trimethylcyclohexyl (meth) acrylate is trans-3,3,5-trimethylcyclohexyl methacrylate represented by the following formula (2). As a typical example of cis-form trimethylcyclohexyl (meth) acrylate, cis-methacrylate represented by the following formula (3) is given.
3,3,5-trimethylcyclohexyl.

Embedded image

Embedded image

A polymer (copolymer) obtained by subjecting trimethylcyclohexyl (meth) acrylate containing a trans-form in an excess amount (preferably at least 75 mol%, more preferably at least 90 mol%, especially at least 95 mol%) to polymerization (copolymer) Polymer)), while exhibiting excellent low hygroscopicity, compared to a polymer obtained from an equal mixture of trans and cis isomers,
High heat resistance. Therefore, such a polymer can be suitably used particularly for a material requiring heat resistance. On the other hand, a polymer (copolymer) obtained by subjecting trimethylcyclohexyl (meth) acrylate containing a cis-form in excess (preferably at least 75 mol%, more preferably at least 90 mol%, particularly at least 95 mol%) to polymerization (copolymerization) Is excellent in the point of low hygroscopicity, and is excellent in moldability as compared with a polymer obtained from an equivalent mixture of a trans-isomer and a cis-isomer. Therefore, this polymer is useful for applications (materials) that require particularly high moldability.

Conventionally, as a method of changing the heat resistance, a method of adjusting the amount by using methyl methacrylate as a comonomer has been performed. In this case, however, the content of oxygen atoms in the resin increases. Therefore, the water absorption increases. On the other hand, in the present invention, the trans-form and the cis-form of trimethylcyclohexyl (meth) acrylate generally have the same water absorption rate but different heat resistance temperatures and melt viscosities. By appropriately selecting the ratio between the trans form and the cis form of trimethylcyclohexyl, it becomes possible to control the heat resistance temperature and moldability of the resin while maintaining low water absorption.

The trimethylcyclohexyl (meth) acrylate having a high content of the trans-form or the cis-form is the corresponding trimethylcyclohexanol having a high content of the trans-form or the cis-form, and (meth) acrylic acid or a reactive derivative thereof ( For example, acid halides, acid anhydrides, esters, etc.) can be obtained by subjecting them to a conventional esterification reaction (or transesterification reaction) using an appropriate catalyst if necessary. Trimethylcyclohexyl (meth) acrylate having a high content of the trans or cis form can also be obtained from a mixture of the trans and cis forms by separation and purification means such as crystallization, distillation, and column chromatography.

More specifically, cis-3 methacrylate,
3,5-Trimethylcyclohexyl is, for example, methacrylic acid selected from methacrylic acid chloride, methacrylic acid and methyl methacrylate or a derivative thereof, and cis-
It can be obtained by reacting with 3,3,5-trimethylcyclohexanol. The amount of methacrylic acid or a derivative thereof to be used is 0.9 to 5 moles, preferably 1 to 2 moles relative to cis-3,3,5-trimethylcyclohexanol. A catalyst can be used as appropriate. For example, when methacrylic acid is used as a reaction component, it is preferable to use an acid catalyst. As the acid catalyst, for example, protonic acids such as sulfuric acid and p-toluenesulfonic acid are preferable. When methacrylic acid chloride is used as a reaction component, it is preferable to use a base as a dehydrochlorinating agent. As the base, for example, trialkylamines such as triethylamine, pyridines and the like can be used. When using methyl methacrylate as a reaction component, it is preferable to use a transesterification catalyst. Examples of the transesterification catalyst include metal alkoxides such as titanium butoxide and titanium isopropoxide; metal oxides such as dibutyltin oxide; metal acetates such as zinc acetate and iron acetate; zinc acetylacetonate and titanium oxyacetylacetonate. Metal acetylacetonate and the like can be mentioned. Also,
Each of the above reactions can also be performed by adding a polymerization inhibitor to the system. Trans-3,3,5-trimethylcyclohexyl methacrylate is also used as the above cis-3,3, methacrylate.
It can be produced in the same manner as 5-trimethylcyclohexyl.

The (meth) acrylic resin of the present invention may be a homopolymer of trimethylcyclohexyl (meth) acrylate. However, in order to further improve mechanical strength and heat resistance, other polymerizable unsaturated resins are used. It may be a copolymer obtained by copolymerizing a compound having a bond (such as an ethylenically unsaturated compound).

Examples of monomers copolymerizable with trimethylcyclohexyl (meth) acrylate include, for example, methyl methacrylate, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, Methacrylates such as norbornyl methacrylate, bornyl methacrylate, adamantyl methacrylate, and dimethyl adamantyl methacrylate (alkyl methacrylate,
Esters of methacrylic acid and cycloaliphatic alcohols);
Methyl acrylate, ethyl acrylate, butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, norbornyl acrylate, bornyl acrylate, adamantyl acrylate,
Examples include acrylic acid esters such as dimethyl adamantyl acrylate (alkyl acrylates, esters of acrylic acid and alicyclic alcohols); aromatic vinyl compounds such as styrene, α-methylstyrene, and vinyltoluene. One or two or more of these monomers can be used.

Of these monomers, it is preferable to use methyl methacrylate for improving the mechanical strength. As such a resin, trimethylcyclohexyl (meth) acrylate monomer unit 3 to 80% by weight (preferably about 10 to 78% by weight, more preferably about 30 to 75% by weight) and methyl methacrylate monomer unit 20 ~ 97
% By weight (preferably about 22 to 90% by weight, more preferably about 25 to 70% by weight), and 0 to 30% by weight of other copolymerizable ethylenically unsaturated compound monomer units (preferably 0 to 25% by weight). (More preferably about 0 to 20% by weight). Such a resin is characterized by having excellent heat resistance, low water absorption, and excellent mechanical strength.

In particular, when an ester of (meth) acrylic acid such as dimethyl adamantyl methacrylate and an alicyclic alcohol is used as the other copolymerizable ethylenically unsaturated compound, low water absorption and mechanical strength can be obtained. Can be remarkably enhanced while maintaining a practically sufficient level. The content of the ester of the (meth) acrylic acid and the alicyclic alcohol is, for example, about 1 to 30% by weight, preferably about 3 to 25% by weight, more preferably 5 to 5% by weight, based on all monomer units. It is about 20% by weight.

The (meth) acrylic resin of the present invention can be obtained by known polymerization methods such as radical polymerization, ionic polymerization and coordination polymerization. The radical polymerization can be performed by a method such as bulk polymerization, solution polymerization, or suspension polymerization in the presence of an initiator, but bulk polymerization or suspension polymerization is preferable in consideration of productivity.

The initiator is not particularly restricted but includes, for example, benzoyl peroxide, lauroyl peroxide, cyclohexanone peroxide, 3,3,5-
Trimethylcyclohexanone peroxide, methylcyclohexanone peroxide, di-t-butylperoxy-3,3,5-trimethylcyclohexane, 1,1
-Bis (t-butylperoxy) cyclohexane, n-
Butyl-4,4-bis (t-butylperoxy), cumene hydroperoxide, diisopropylbenzene peroxide, 2,5-dimethylhexane-2,5-dihydroperoxide, di-t-butylperoxydiisopropylbenzene , T-butylcumyl peroxide, α, α'-bis (t-butylperoxy-m-isopropylbenzene, 2,5-dimethyl-2,5-di (t
Organic peroxides such as -butylperoxy) hexyne-3;
Azo compounds such as azobisisobutyronitrile and azobiscyclohexanone-1-carbonitrile; water-soluble initiators such as potassium persulfate; redox initiators using a combination of a peroxide or a persulfate and a reducing agent are used. be able to.

The amount of the initiator to be added is not particularly limited as long as the properties and quality of the resin are not impaired, but it is preferable to add the initiator in the range of about 0.001 to 1% by weight based on the total amount of the monomers. preferable.

In the polymerization, for the purpose of controlling the molecular weight, a commonly used molecular weight regulator, for example, a mercaptan-based compound such as butanethiol, octanethiol or dodecanethiol may be added as required. .

[0027] The polymerization temperature is generally in the range of 30 to 200 ° C, and particularly preferably in the range of 50 to 150 ° C. When a polymerization solvent is used, a commonly used solvent such as benzene, toluene, and methyl ethyl ketone can be used.

When the (meth) acrylic resin of the present invention is produced by suspension polymerization, a suspending agent and a suspending aid are used. As a suspending agent, for example, polyvinyl alcohol,
Examples include water-soluble polymers such as methylcellulose, and inorganic substances such as calcium phosphate. When the inorganic substance is used as a suspending agent, it is preferable to add a surfactant such as sodium dodecylbenzenesulfonate or sodium thiosulfate to the system.

The molecular weight of the (meth) acrylic resin of the present invention is not particularly limited, but is preferably in the range of 10,000 to 1,000,000 in terms of weight average molecular weight [GPC (gel permeation chromatography) method; standard polystyrene conversion]. If the weight average molecular weight is less than 10,000, mechanical strength and heat resistance are liable to decrease, and
If it is larger than 0, the moldability tends to decrease.

The (meth) acrylic resin of the present invention may be used alone or in combination with another resin. Also, for example, when used as an optical resin,
If necessary, antioxidants such as phenols, phosphites, thioethers, aliphatic alcohols, fatty acid esters, phthalic acid esters, and fluorine-based compounds to prevent deterioration, improve thermal stability, and improve moldability. Surfactants, release agents such as higher fatty acid metal salts, lubricants, plasticizers, antistatic agents,
You may add additives, such as an ultraviolet absorber, a flame retardant, and a coloring agent.

The (meth) acrylic resin of the present invention can be used in various useful ways by utilizing the properties of the resin of the present invention by using a conventional molding method such as extrusion molding, casting, injection molding, compression molding and the like. A molded article can be obtained. Examples of such a molded product include a light-transmitting extruded plate, an optical molded product (an optical element substrate such as an optical recording information material), and the like.

[0032]

The (meth) acrylic resin and the molded article of the present invention have high heat resistance and / or moldability and exhibit excellent low moisture absorption.

[0033]

EXAMPLES The present invention will be described below in more detail with reference to Examples, but the present invention is not limited to these Examples.

Production Example In a nitrogen-substituted 10-L four-neck separable glass flask with stirring blades, 1420 g (10 mol) of cis-3,3,5-trimethylcyclohexanol as a raw material, 1033 g (12 mol) of methacrylic acid, and a solvent As toluene 4500
g, 50 g of p-toluenesulfonic acid monohydrate as a catalyst
And a dehydration reaction was carried out under reflux for 8 hours. After completion of the reaction, the reaction mixture was washed successively with a 10% by weight aqueous solution of sodium hydroxide and water. The organic layer was separated and concentrated to obtain 1790 g of the target cis-3,3,5-trimethylcyclohexyl methacrylate. Cis-3,3, methacrylate
The ¹ H-NMR spectrum of 5-trimethylcyclohexyl is shown in FIG. Similarly, transformer-3,3,5-
Trans-3,3,5-trimethylcyclohexyl methacrylate was produced from trimethylcyclohexanol and methacrylic acid. The resulting methacrylic acid trans-
¹ H-NMR of 3,3,5-trimethylcyclohexyl
The spectrum is shown in FIG. The signal of the proton corresponding to R ¹¹ in the formula (1) is cis-methacrylic acid.
4.95p for 3,3,5-trimethylcyclohexyl
pm and 5.17 ppm for trans-3,3,5-trimethylcyclohexyl methacrylate. Only one signal was observed in each spectrum, confirming that the high-purity target product was obtained.

Example 1 In a stainless steel autoclave having a capacity of 10 L, 2.0 kg of trans-3,3,5-trimethylcyclohexyl methacrylate (t-TMCHMA) and 500 ppm of azobisisobutyronitrile with respect to the monomer were used. 2000 ppm of dodecanethiol to the monomer, 4.0 kg of distilled water, 1.0% by weight of tribasic calcium phosphate to the total amount of distilled water and the monomer, and sodium dodecylbenzenesulfonate to the total amount of distilled water and the monomer. Then, 50 ppm was charged and mixed, the atmosphere in the flask was replaced with nitrogen for 1 hour, and then polymerization was performed at 70 ° C. for 6 hours. In addition, 1
The temperature was raised to 20 ° C., and polymerization was continued for 5 hours. The obtained polymer was washed with water, dehydrated, and dried at 60 ° C. under reduced pressure for 10 hours.
Bead-shaped polymer particles were obtained.

Example 2 As a monomer, cis-3,3,5-trimethylcyclohexyl methacrylate (c-methacrylate) was used in place of t-TMCHMA.
Except for using TMCHMA), the same operation as in Example 1 was performed to obtain a beaded polymer.

Example 3 Except that 1.2 kg of t-TMCHMA and 0.8 kg of methyl methacrylate (MMA) were used as monomers,
The same operation as in Example 1 was performed to obtain a beaded polymer.

Example 4 0.8 kg of t-TMCHMA and MM as monomers
A beaded polymer was obtained by performing the same operation as in Example 1 except that A1.2 kg was used.

Example 5 0.8 kg of cis-3,3,5-trimethylcyclohexyl methacrylate (c-TMCHMA) as a monomer
The same operation as in Example 1 was performed except that 1.2 kg of MMA was used, and a bead-like polymer was obtained.

Example 6 1.0 kg of t-TMCHMA and 0.2 k of dimethyladamantyl methacrylate (DMAdMA) as monomers
g and MMA in an amount of 0.8 kg were carried out in the same manner as in Example 1 to obtain a bead-like polymer.

Comparative Example 1 The same operation as in Example 1 was carried out except that 2.0 kg of MMA was used as a monomer to obtain a beaded polymer.

Comparative Example 2 As a monomer, cyclohexyl methacrylate (CHM
A) The same operation as in Example 1 was carried out except that 1.2 kg and 0.8 kg of MMA were used to obtain a beaded polymer.

Comparative Example 3 1.0 kg of t-TMCHMA and c-
Except that 1.0 kg of TMCHMA was used, the same operation as in Example 1 was performed to obtain a beaded polymer.

Evaluation Test The following physical properties were measured using the polymers obtained in Examples and Comparative Examples. Table 1 shows the results. The glass transition temperature (Tg: ° C) was measured by differential scanning calorimetry (DSC).

(Saturated water absorption) The saturated water absorption (%)
It was measured at 23 ° C. based on SK 7209. (Bending strength) The bending strength (MPa) is ASTM-D79.
The measurement was based on 0. (Melt viscosity) The melt viscosity (Pa · sec) is 240 ° C.
The measurement was performed under the condition of 100 sec ^-1 .

[0046]

[Table 1]

As is clear from Table 1, trans-3,3,5-trimethylcyclohexyl methacrylate (t-
The homopolymer of TMCHMA) (Example 1) has a higher glass transition temperature and a very low water absorption as compared with the polymer of the comparative example. On the other hand, methacrylic acid cis-3,3,5
The homopolymer of -trimethylcyclohexyl (c-TMCHMA) (Example 2) has the same water absorption as the polymer of Example 1, but has a low melt viscosity and is excellent in moldability.

Further, trans-3,3,5 methacrylate
-Trimethylcyclohexyl (t-TMCHMA) or cis-3,3,5-trimethylcyclohexyl methacrylate (c-TMCHMA) is converted to methyl methacrylate (MM
By copolymerizing with A) (Examples 3 to 5), the strength can be improved while maintaining practically sufficient heat resistance and low water absorption. Further, methacrylic acid trans-
3,3,5-trimethylcyclohexyl (t-TMCH
MA), methyl methacrylate (MMA) and dimethyl adamantyl methacrylate (DMAdMA) (Example 6) to obtain a polymer exhibiting excellent low water absorption and strength without significantly lowering the glass transition temperature. Obtainable.

[Brief description of the drawings]

FIG. 1 shows cis-3,3, methacrylate produced in Production Example.
^{1 is} a ¹ H-NMR spectrum of 5-trimethylcyclohexyl.

FIG. 2 shows trans-3 methacrylate produced in the production example.
^{1 is} a ¹ H-NMR spectrum of 3,5-trimethylcyclohexyl.

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Claims (6)

[Claims] 1. A (meth) acrylic resin containing trimethylcyclohexyl (meth) acrylate monomer units in an amount of 3% by weight or more of all monomer units, wherein the (meth) acrylic resin is contained in the trimethylcyclohexyl (meth) acrylate monomer. (Meth) acrylic resin having a trans- or cis-form proportion of more than 50 mol%. 2. The (meth) acrylic resin according to claim 1, wherein the trimethylcyclohexyl (meth) acrylate monomer is 3,3,5-trimethylcyclohexyl (meth) acrylate. 3. The (meth) acrylic resin according to claim 1, wherein the proportion of the trans form in the trimethylcyclohexyl (meth) acrylate monomer is 75 mol% or more. 4. The (meth) acrylic resin according to claim 1, wherein the proportion of the cis-form in the trimethylcyclohexyl (meth) acrylate monomer is 75 mol% or more. 5. Trimethylcyclohexyl (meth) acrylate monomer unit in an amount of 3 to 80% by weight, methyl methacrylate monomer unit in an amount of 20 to 97% by weight, and other copolymerizable ethylenically unsaturated compound monomer units. The (meth) acrylic resin according to any one of claims 1 to 4, comprising 0 to 30% by weight. 6. A molded article comprising the (meth) acrylic resin according to any one of claims 1 to 5.