JPH06345812A - Production of heat-resistant acrylic resin - Google Patents

Abstract

PURPOSE:To provide an efficient method for producing an acrylic resin remarkably improved in heat and solvent resistance, thermal stability, etc. CONSTITUTION:This method for producing a heat-resistant acrylic resin is to heat an acrylic polymer having carboxyl group and a compound, containing amide group and expressed by the general formula RCONH2 (R is 1-20C alkyl or aryl group) at >=100 deg.C and make the acrylic polymer react with the compound.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a heat-resistant acrylic resin, and more specifically, to an acrylic polymer having at least a carboxyl group, particularly various kinds of (meth) acrylic acid obtained as a monomer raw material. The present invention relates to a method for producing a heat-resistant acrylic resin having improved properties such as heat resistance, heat stability, solvent resistance, and water absorption resistance by chemically modifying an acrylic polymer.

The heat-resistant acrylic resin produced by the method of the present invention can be suitably used as a material for automobile members, electric / electronic device members, building materials, and the like.

[0003]

2. Description of the Related Art For (meth) acrylic resins, (meth)
Various things such as homopolymers or copolymers of acrylic acid [acrylic acid or methacrylic acid, or a mixture thereof] and its ester [for example, alkyl ester such as methyl (meth) acrylate] are known, Specifically, for example, polymethylmethacrylate (PMM
A), polyalkyl (meth) acrylates such as polymethyl acrylate, poly (meth) acrylic acid such as polymethacrylic acid and polyacrylic acid, and copolymers thereof. In addition, such (meth) acrylic resins are often produced as a copolymer with other vinyl-based comonomers [eg (meth) acrylonitrile, (meth) acrylamide, styrene, etc.], and various changes in their properties are caused. I'm giving.

These (meth) acrylic resins are used in various fields, for example, as adhesives, paints, coating materials, films, or plastic materials of various shapes, depending on their properties. Among them, there are many applications that make use of their excellent transparency, weather resistance, mechanical properties, etc., and they are widely used in various industrial fields such as automobile parts, electric / electronic device parts, and building materials.

However, since these conventional (meth) acrylic resins have a low heat distortion temperature of around 100 ° C.,
There is a problem that it is not suitable for use in an environment where higher heat resistance is required. Therefore, in such a case, it has been attempted to use a polycarbonate having transparency and relatively good heat resistance, but even in the case of this polycarbonate, the practical heat resistance temperature is unexpectedly low at less than 140 ° C., Depending on the application, it is still not sufficient, and there are many other disadvantages such as cost and workability.
From this point as well, there is a limitation in use.

Under these circumstances, it is an important subject to improve the heat resistance of the (meth) acrylic resin.

As a method for improving the heat resistance of a (meth) acrylic resin, conventionally, by heating a copolymer of (meth) acrylic acid and (meth) acrylonitrile, the side chains of the polymer, -COOH and -CN, are heated. By reacting with and cyclized to form a 6-membered ring imide structure (Japanese Patent Publication No. 44-8743), by reacting PMMA with a primary amine, the polymer side chain (-
COOCH ₃ ) is imidized and a part thereof is made into a six-membered ring imide structure (US Pat. No. 3,284,425), or a polyacrylic acid ester is reacted with an amide compound in the presence of an imidization catalyst. A method for improving heat resistance (Japanese Patent Laid-Open No. 1-289807) is known. Thus, it is noted that the heat resistance can be improved by imidizing the polymer side chain of the (meth) acrylic polymer.

However, in these conventional imidization methods, since the cyclization imidization reaction occurs only between adjacent side chains, there are many unreacted carboxylic acids (carboxyl groups) in the polymer chain. Remains, while
In the case of, since reacted at a relatively high temperature primary amines to -COOCH _3, or since the time generation of water by the thermal decomposition of methanol formed is not negligible, -COOC
Decomposition of H _{3 into} a carboxyl group is likely to occur simultaneously, and the carboxyl group remains in the polymer chain. As described above, the conventional imidization treatment as described above has a problem that a carboxyl group remains in the polymer chain, which adversely affects the thermal stability of the polymer. Furthermore, since amine compounds are used at high temperatures, corrosion is a major problem. In addition, in the method of 1, the polyacrylic acid ester has low reactivity with an amide compound, requires an imidization catalyst such as ammonium chloride, and requires removal of the catalyst, and the obtained polymer also has insufficient heat resistance. There was a problem that was.

[0009]

DISCLOSURE OF THE INVENTION According to the present invention, various acrylic polymers having a carboxyl group in the polymer chain are reacted with a suitable compound to convert the carboxyl group in the polymer chain into a group having good thermal stability. A method for effectively improving the heat resistance and heat stability of an acrylic polymer by changing it, that is, a method for efficiently producing a heat resistant acrylic resin in which heat resistance, heat stability, solvent resistance and the like are remarkably improved. The purpose is to provide.

[0010]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that various acrylic polymers having a carboxyl group in the polymer chain have
A specific compound (amide compound) at a specific temperature or higher (10
It was found that the heat resistance (glass transition temperature and the like) and thermal stability of the polymer can be easily improved by reacting at a temperature of 0 ° C. or higher), and the present invention has been completed.

That is, the present invention has a carboxyl group.
Acrylic polymer and general formula R CONH₂Represented by
An amide group-containing compound (provided that R in the formula Has 1 carbon
Represents an alkyl group or an aryl group of 20. ) And
Resistant to heating at 100 ℃ or more to react
The present invention provides a method for producing a thermosetting acrylic resin.

In the method for producing a heat-resistant acrylic resin of the present invention, an acrylic polymer (hereinafter sometimes referred to as a raw material polymer) which is reacted with an amide group-containing compound.
Is an acrylic polymer of any type and structure as long as it has a carboxyl group in the polymer chain as described above. This is because the carboxyl group easily reacts with the amide group-containing compound without a catalyst to efficiently transform into an imide group having good thermal stability, and in that case, the effect of improving heat resistance and solvent resistance is large.

The substitution position of the carboxyl group in the above-mentioned raw material polymer is not particularly limited, but normally, the following homopolymers or copolymers of acrylic acid or methacrylic acid derivatives are preferably used as the raw material polymer. It Further, it may be a polymer in which other monomers are copolymerized within a range that does not impair the reactivity of the raw material polymer.

That is, as the raw material polymer preferably used in the method of the present invention, for example, at least:
The following general formula [I]

[0015]

[Chemical 1]{However, R in the formula [I]¹ Is a hydrogen atom or a carbon number of 1 to
4 represents an alkyl group. } Repeating unit
Acrylic polymer [P-I] having [I] is given.
be able to.

In this repeating unit [I], R¹ Is
Represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms,
The polymer having the return unit [I] is R¹ Is a hydrogen atom
And only one selected from an alkyl group having 1 to 4 carbon atoms
Polymer, or R¹ Is the above 2
It may be a mixed type polymer composed of one or more species.

Repeating unit represented by the above general formula [I]
The acrylic polymer [P-I] having [I] is R¹
A wide variety depending on the type and combination (copolymer composition) of
And a single one consisting of the repeating unit [I]
It may be a polymer, or any combination of two or more
And a repeating unit [I].
A copolymer composed of other repeating units may be used.

Such an acrylic polymer [P-I]
Is, for example, the following general formula [II]

[0019]

[Chemical 2]{However, R in the formula [II]¹ Has the same meaning as above
It } Acrylic acid and acrylic acid derivatives [I
I], one or more of which are homopolymerized or copolymerized.
Acrylic polymers of various structures and compositions obtained by combining
-[P-Ia] and acrylic acid and acrylic acid derivatives
One or more of the body [II] and the acrylic acid
And / or other vinyl copolymerizable with acrylic acid derivative
Copolymerized with at least one compound [III]
Acrylic polymers of various structures and compositions obtained by
[P-Ib] and the like can be mentioned.

In the case of a copolymer, acrylic acid and /
Alternatively, the copolymerization ratio of the acrylic acid derivative [II] is preferably such that the copolymerization ratio of the monomer having a carboxyl group is 50 mol% or more.

Specific examples of [II] include acrylic acid,
Methacrylic acid, 2-ethylpropenoic acid, 2-propylpropenoic acid and 2-butylpropenoic acid can be mentioned.

On the other hand, other vinyl compounds [III] copolymerizable with these acrylic acids and / or acrylic acid derivatives
As, there are various olefins and various functional group-containing olefins, and of these, typical examples include, for example, acrylonitrile, methacrylonitrile,
Other (meth) acrylic compounds such as acrylamide, methacrylamide, acrolein, and methacrolein, styrene, α-methylstyrene, p-methylstyrene, 2,4
-Dimethyl styrene, p-tert-butyl styrene,
styrenes such as p-chlorostyrene, vinyl pyridine,
Examples thereof include N-2-vinylpyrrolidone and maleic anhydride.

As the acrylic polymer [P-I] or [P-Ia] or [P-Ib], there are various kinds depending on the kind and combination of monomers, copolymer composition, etc. Examples of such compounds include, for example, homopolymers and copolymers of (meth) acrylic acid, copolymers of (meth) acrylic acid and (meth) acrylonitrile, and other vinyl compounds such as (meth) acrylic acid and styrene. [II
I], various copolymers of (meth) acrylic acid, (meth) acrylonitrile and other vinyl compound [III], and various (meth) acrylic acid-based monomers containing at least (meth) acrylic acid as a monomer. Various things such as polymers can be mentioned. Among these, for example, those containing a carboxyl group such as poly (meth) acrylic acid are preferable because the effects of improving heat resistance and solvent resistance are particularly large as described above. By the way, the various acrylic polymers [P-I] ([P-Ia], [P-Ib], etc.) to be subjected to the reaction with the amide group-containing compound.
Can be suitably obtained by vinyl polymerization of the above-mentioned predetermined monomer according to a conventional method, for example, by radical polymerization at a suitable temperature using a suitable radical initiator in a suitable solvent. it can. As the radical initiator, those commonly used in this type of polymerization reaction can be suitably applied, and specific examples thereof include organic peroxides such as di-tert-butyl peroxide and dicumyl peroxide. And azo compounds such as azobisisobutyronitrile (AIBN) and azobiscyclohexylcarbonitrile.
This polymerization reaction can usually be suitably carried out in the temperature range of 40 to 150 ° C. Also, as the solvent in this polymerization reaction, various commonly used solvents can be used. In addition, by using a neutral polar solvent described later as this solvent, for example, from this polymerization reaction, the imidization treatment and the subsequent reaction with the amide group-containing compound are continuously carried out without particularly changing the solvent. It becomes easy to do. In this case, the amount of the solvent used is preferably selected, for example, in the range of 20 to 90% by weight of the reaction system at the start of the polymerization reaction. Moreover, these acrylic polymers can also be obtained by ionic polymerization, coordination polymerization, or the like.

In the method of the present invention, the above-mentioned various carboxyl group-containing acrylic polymers and amide group-containing compounds are heated to a temperature of 100 ° C. or higher to react with each other, whereby the heat resistance and thermal stability of the polymer, etc. Improve the characteristics of.

As the amide group-containing compound, various kinds of compounds can be used.
One kind or two or more kinds can be used. Where R of
As a specific example, the R¹ Each also illustrated as
And phenyl group, methylphenyl group, ethylphenyl
Group, dimethylphenyl group, etc.
it can. Of these preferred amide group-containing compounds,
Some examples include benzamide and 2-phenyl.
Phenylacetamide, 3-phenylpropionamide,
Examples include acetamide, propionamide, etc.
it can.

These amide group-containing compounds have 1
One kind may be used alone, or two or more kinds may be used together as a mixture or the like, if necessary.

As the reaction conditions for reacting the acrylic polymer with the amide group-containing compound, the following conditions are usually preferably adopted.

That is, the reaction temperature is 100 ° C. or higher, usually 100 to 280 ° C., preferably 150 to 2
It is suitable to select in the range of 50 ° C, and the reaction time is
Usually, it is preferable to select the range of 30 minutes to 10 hours.

If the reaction temperature is less than 100 ° C., the predetermined reaction rate becomes slow, which is not practical. On the other hand, 250
If the reaction is carried out at a high temperature exceeding ℃, the polymer is likely to be decomposed or side reaction may occur.

The proportion of the amide group-containing compound used is usually
Although it depends on the composition of the polymer [acrylic polymer] to be reacted, particularly the content ratio of the carboxyl group, it is preferable to react the carboxyl group with the amide group-containing compound as completely as possible to imidize.

The proportion of the amide group-containing compound used is preferably selected in the range of equimolar to 3 times the molar amount of the carboxyl groups in the polymer. Even under these conditions, sufficient heat resistance is usually obtained. Also, the effect of improving thermal stability can be obtained.

The reaction between the amide group-containing compound and the acrylic polymer is usually preferably carried out in a suitable solvent. As this solvent, various ones can be used, but normally, for example, N-methylpyrrolidone (NM
P), N-cyclohexylpyrrolidone, dimethylformamide (DMF), dimethylacetamide (DMA
c), dimethylimidazolinone (DMI), N-methylcaprolactam, dimethylsulfoxide (DMSO),
A neutral polar solvent such as sulfolane or dimethylpropyleneurea (DMPU) can be preferably used. Among these, NMP, DMF and sulfolane are particularly preferable. These solvents can be used as a single solvent or a mixed solvent.

The amount of the solvent used is usually preferably selected in the range of 20 to 90% by weight based on the whole reaction system. Regarding the reaction pressure, it can be carried out under normal pressure or under pressure, and particularly under pressure when the boiling point of the imide group-containing compound is low, it is effective to carry out under pressure.

As described above, by reacting various acrylic polymers with the amide group-containing compound, the heat resistance, heat stability and solvent resistance thereof can be sufficiently and easily improved, and the desired heat resistance can be obtained. Of a water-soluble polymer can be efficiently obtained. The polymer thus obtained has heat resistance (glass transition temperature, etc.) because the carboxyl group remaining in the polymer chain is changed into another stable group (imide group) by the reaction with the amide group-containing compound. And the thermal stability (for example, thermal decomposition resistance such as the effect of improving the thermal decomposition starting temperature) is sufficiently improved.

The polymer obtained by reacting the amide group-containing compound as described above is separated from the reaction mixture by a conventional method and, if necessary, subjected to an appropriate purification treatment to obtain a desired product. At that time, the recovered solvent (and the unreacted amide group-containing compound, if any) can be reused if necessary.

[0036]

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

In the following examples, the reduced viscosity [η _sp / c] of the polymer was measured by solvent NMP, polymer concentration of 0.
The measurement was performed under the conditions of 2 g / dl and a measurement temperature of 30 ° C.

The glass transition temperature was measured by DSC at a temperature rising rate of 20 ° C./minute, and the decomposition initiation temperature was measured by TGA in air at a temperature rising rate of 10 ° C./minute. The temperature at 5% weight loss was determined.

Example 1 10 g of polyacrylic acid (η _sp /c=3.04 dl / g, glass transition temperature 106 ° C., thermal decomposition starting temperature 250 ° C.),
2-Phenylacetamide (18.8 g, equivalent to the carboxyl group of polyacrylic acid) and sulfolane (50 ml) were mixed, and this was heated at 230 ° C. for 3 hours. After completion of the reaction, the polymer was precipitated in methanol, washed with methanol and dried.

The reduced viscosity of the polymer thus obtained [η
_sp / c] was 1.36 dl / g, and its glass transition temperature was 241 ° C and thermal decomposition initiation temperature was 328 ° C. Also, when a solubility test was performed on the polymer before and after the reaction, polyacrylic acid dissolves in water / methanol,
The reaction product polymer was soluble in NMP and sulfolane, but was insoluble in water, methanol and acetone.
The IR chart of this polymer is shown in FIG.

Example 2 Instead of 2-phenylacetamide, benzamide 1
A polymer was obtained in the same manner as in Example 1 except that 6.8 g (equivalent to the carboxyl group of polyacrylic acid) was used.

Reduced viscosity [η _sp / c] of the obtained polymer
Is 1.35 dl / g and its glass transition temperature is 24
The temperature was 3 ° C and the thermal decomposition starting temperature was 296 ° C. The solubility of the polymer was the same as that of the polymer obtained in Example 1. The IR chart of this polymer is shown in FIG.

Example 3 Instead of polyacrylic acid, polymethacrylic acid (η _sp / c =
A polymer was obtained in the same manner as in Example 1 except that 1.20 dl / g, glass transition temperature 166 ° C., thermal decomposition start temperature 212 ° C.) were used.

Reduced viscosity [η _sp / c] of the obtained polymer
Is 1.8 dl / g and its glass transition temperature is 178
C., and the thermal decomposition starting temperature was 362.degree. The solubility was the same as that of the polymer obtained in Example 1.

Example 4 In place of 2-phenylacetamide, acetamide 8.
A polymer was obtained in the same manner as in Example 1 except that 19 g (equivalent to the carboxyl group of polyacrylic acid) was used.

Reduced viscosity of obtained polymer [η _sp / c]
Is 1.95 dl / g and its glass transition temperature is 22.
The temperature was 6 ° C and the thermal decomposition starting temperature was 291 ° C. The solubility of the polymer was the same as that of the polymer obtained in Example 1.

As described above, regarding the poly (meth) acrylic polymer containing a carboxyl group, both the glass transition temperature (one measure of heat resistance) and the thermal decomposition initiation temperature (one measure of thermal stability) are large. Improved.

[0048]

According to the present invention, an acrylic polymer can be reacted with an amide group-containing compound to convert the carboxyl group of the polymer chain into an imide group having good thermal stability without adding a catalyst. Therefore, a heat-resistant acrylic resin having excellent heat resistance, heat stability, and solvent resistance can be easily obtained. Further, polyacrylic acid, which was conventionally water-soluble, can be changed to a completely different acrylic resin.

[Brief description of drawings]

FIG. 1 is an IR chart of the polymer obtained in Example 1.

FIG. 2 is an IR chart of the polymer obtained in Example 2.

Claims (1)

[Claims] 1. An acrylic poly having a carboxyl group
Mar and general formula R CONH₂Amide group containing
Compound (however, R in the formula Is an alkyl group having 1 to 20 carbon atoms
Alternatively, it represents an aryl group. ) And heating above 100 ℃
Heat-resistant acrylic resin characterized by reacting by
Manufacturing method.