JPS62177021A - Aromatic polyamide copolymer - Google Patents

Abstract

PURPOSE:To obtain the titled novel polymer capable of melt forming with both high thermal stability and fluidity, suitable for films, fibers, laminates, coatings, etc., by alternate copolymerization between specific two or more diamine components and acid component. CONSTITUTION:An aromatic dicarboxylic acid dichloride representing structural units of formula I (R1 is 1-4C alkyl, etc,; a is 0-4) is dissolved in, e.g. an organic polar solvent (e.g. N-methypyrrolidone); following that, (B) pref. 0.9-1.1mol per mol of the component A, of a mixed diamine made up of (i) 40-98mol% of an aromatic diamine representing structural unit of formula II and (ii) 60-2mol% of a second aromatic diamine representing structural unit of formula III (X is O, S, -CO-, etc,; b is 1-20) is added to the above sys tem to perform polymerization at -20-80 deg.C, thus obtaining the objective poly mer with a logarithmic viscosity >=0.25.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention relates to a novel heat-resistant thermoplastic polymer, and more particularly, it has good thermal stability and fluidity in the temperature range of 250 to 380°C. The present invention relates to a novel thermoplastic aromatic boria turf copolymer which has the following properties and is melt moldable.

<Prior Art> It has been well known that aromatic polyamides with excellent heat resistance can be obtained by generally combining isophthalic acid or terephthalic acid residues with aromatic diamine residues. For example, an aromatic polyamide represented by the general formula is synthesized by reacting isophthalic acid dichloride and m-phenylenediamine in an equimolar ratio (for example, Japanese Patent Publication No. 47-10865, Japanese Patent Publication No. 4B-17551).
(U.S. Pat. No. 3,049,511, U.S. Pat. No. 3,287,324, etc.).

Furthermore, by reacting terephthalic acid dichloride with four components: 3,4'-diaminodiphenyl ether, meta-phenylene diamine, and para-phenylene diamine, an aromatic polyamide with excellent heat resistance and rigidity can be obtained (for example, Publication No. 51-76386, Japanese Unexamined Patent Publication No. 1983-
134743, JP-A-55-115428, etc.).

Furthermore, aromatic polyamides with excellent melt flowability can be obtained by combining terephthalic acid dichloride and/or isophthalic acid dichloride with 2,2-bis(para-aminophenoxyphenyl)propane H3 (for example, as disclosed in JP-A-52-23198). , JP-A-54-77692, JP-A-54-77
693, etc.).

<Problems to be Solved by the Invention> However, aromatic polyamides that have been generally proposed so far, such as A, isophthalic acid dichloride/metaphenylene diamine polycondensate B, terephthalic acid dichloride/paraphenylene diamine Polycondensate C, terephthalic acid dichloride and/or isophthalic acid dichloride/4,4'-diaminodiphenyl ether polycondensate D, terephthalic acid dichloride/paraphenylenediamine/metaphenylenediamine/3°4'-diaminodiphenyl ether polycondensate, Although it has excellent properties in terms of both heat resistance and rigidity, it is practically impossible to melt and mold because the melt flow start temperature and thermal decomposition temperature are too close, so it is mainly dissolved in a solvent and molded. The reality is that a so-called wet molding method has no choice but to be adopted.

On the other hand, as described above, a method of combining terephthalic acid dichloride and/or isophthalic acid dichloride with 2,2-bis(para-aminophenoxyphenyl)propane Hs has been proposed as an effective method for imparting melt moldability to aromatic polyamides. This aromatic boria-based resin has a flow start temperature that is 50°C or more lower than the thermal decomposition temperature and has excellent thermal stability and fluidity during melt molding, so it exhibits good melt moldability. Due to the large number of ether bonds in the structure, the flexibility of the molecules becomes too high, resulting in a disadvantage that the physical properties of the molded product (particularly the bending strength and thermal properties) are too low.

Therefore, the present inventors have achieved good melt formability by combining good thermal stability and fluidity in the temperature range of 250 to 380°C, and improved physical properties (particularly bending strength and heat resistance) of the molded product. As a result of extensive research aimed at obtaining superior aromatic polyamides, we have developed a new thermoplastic aromatic material that has the desired properties by combining two different specific diamine components in a previously unknown composition. It was discovered that a polyamide copolymer can be obtained, and the present invention was achieved.

Means for Solving Problems> That is, the present invention uses (R4) a units and structural units as main essential structural units, and the ratio of each structural unit is such that (B+C) is substantially 1 with respect to 1 mole of A. mole, and C is 0.40 to 0.98 mole of B.
60 to 0.02 mol, and is characterized in that A and (B or C) are alternately connected (in the formula, R+ is an alkyl having a prime number of 1 to 4). group, alkoxy group or halogen group; .

The aromatic polyamide copolymer of the present invention mainly comprises the above A,
It is composed of structural units represented by B and C as essential structural units.

Specific examples of the above A unit include Hs and the like. These units may be one type or two or more types may be mixed.

A specific example of B unit is 0CHa 0CHa
0CHsOCHs QC)ia
Examples include C1. These B units are used for one or more types of money making.

Specific examples of the above C unit include CHa CHa CH3 ll- CH3 ■ 1 CHa CH3CH3. These units may be used alone or in combination of two or more.

-12= The ratio of each of the above units in the aromatic polyamide copolymer of the present invention is such that (B+C) is substantially 1 mol to At mol, and B O is 40 to 0.98 mol to G
O,60 to 0.02 mol, more preferably B O,5
It is C0150-0.1θ mole with respect to 0-0.90 mole. If the C unit of the (B+C) units exceeds 60 mol%, the strength and heat resistance of the molded article will decrease, which is not preferable. On the other hand, if the C unit is less than 2 mol % of the CB+C) units, the effect of improving fluidity during melting due to the introduction of the C unit will not be exhibited, which is not preferable.

In this way, the aromatic polyamide copolymer of the present invention has A, B
The three units of C and C are considered essential constituent units, but (
Up to 40 mol% of the B+C) units may be replaced with D units represented by (R+)H 2 . A, B and C
By further introducing a D unit into the unit, heat resistance, rigidity, etc. are improved, and favorable results can be obtained. As a specific example of this D unit, the unit is used alone or in combination of two or more types.

The aromatic polyamide copolymer of the present invention can be produced using any of the many general production methods that have been proposed to date, but among them, the following 4 are representative examples with high practicality. Laws can be mentioned.

(1) Acid chloride method: A method in which aromatic dicarboxylic acid dichloride and aromatic diamine are reacted (for example,
5-13247, Japanese Patent Publication No. 35-14399, Japanese Patent Publication No. 46-41387, Japanese Patent Publication No. 47-108
63, JP-A-54-77692, etc.).

(2) Iso, cyanate method: A method of reacting an aromatic dicarboxylic acid with an aromatic diisocyanate (Japanese Patent Publication No. 4
Publication No. 7-47596, French Patent No. 1578154
Publications, etc.).

(3) Ester amide exchange method: A method in which an aromatic dicarbonate ester is reacted with an aromatic diamine (for example, JP-A-52-82996, Belgian Patent No. 7314)
20, etc.).

(4) Direct polymerization method: A method in which aromatic dicarboxylic acids or their derivatives (excluding acid chlorides and ester derivatives) and aromatic diamines are directly reacted in the presence of a dehydration catalyst in a polar organic solvent (for example, JP-A-52 -58795, JP-A-52-58796, etc.) 0 Among the above four methods, the acid chloride method yields aromatic polyamide with a high degree of polymerization due to the relatively easy procurement of raw materials and low temperature polymerization. This is the most recommended manufacturing method. Here, a more specific example of the production of the aromatic polyamide copolymer of the present invention by the acid chloride method is as follows. That is, aromatic dicarboxylic acid dichloride (R1 is an alkyl group having 1 to 4 carbon atoms, an alkoxy group, or a halogen group, and a is 0 or an integer of 1 to 4.) 1
Mol and aromatic diamine (I) (R1 and a are the same as above) 40-98 (preferably 50-90) mol%
and aromatic diamine (I[), -(R+) a (R+) a (R+)
a (X is the same or different groups, direct bond, 0
Rx fluorine-substituted alkyl group or phenyl group, b represents an integer of 1 or more, R1 and a are the same as above) mixed diamine consisting of 60 to 2 (preferably 50 to 10) mol% 0.
9 to 1.1 mol is dissolved in an organic polar solvent, -20 to
Polymerization is carried out at a temperature of 80 DEG C. in the presence or absence of a hydrogen chloride scavenger for 0.1 to 10 hours. The organic polar solvent used in the polymerization is N,N-dialkylcarboxylic acid amide such as N,N-dimethylacetamide, N,N-diethylacetamide, N-methylpyrrolidone, tetrahydrothiophene-1,1-dioxide, 1 .3-
Heterocyclic compounds such as dimethyl-2-imidazolidinone, especially N-methylpyrrolidone and N,N
-dimethylacetamide is preferred. Further, the hydrogen chloride scavenger includes aliphatic tertiary amines such as trimethylamine, triethylamine, tripropylamine, and tributylamine, pyridine, lutidine, collidine,
These include concessionary organic bases such as quinoline, and organic oxide compounds such as ethylene oxide and propylene oxide.

It is also possible to block the ends of the aromatic polyamide copolymer of the present invention before, during, or by adding an end-blocking agent to the reaction vessel. Terminal capping greatly improves the thermal stability of the aromatic polyamide copolymer, which is preferable.

Examples of the terminal blocking agent include acid anhydrides such as acetic anhydride, propionic anhydride, butyric anhydride, caproic anhydride, isobutyric anhydride, phthalic anhydride, benzoic anhydride, naphthalene-1,8-dicarboxylic anhydride, and chloride. Acetyl, propionyl chloride, butyryl chloride, benzoyl chloride, a- or β
- Acid chlorides such as naphthoic acid chloride and caproyl chloride, propylamine, butylamine, amylamine,
Primary and secondary monoamines such as aniline, p-aminoacetanilide, benzylamine, cyclohexylamine, dicyclohexylamine, morpholine, toluidine, diphenylamine, phenol, cresol, xylenol, t-butylphenol, methoxyphenol, β-naphthol, cumyl Examples include monohydroxy compounds such as phenol and phenylphenol.

After stirring and mixing the aromatic polyamide copolymer solution thus obtained with a liquid that is miscible with the solvent but does not dissolve the aromatic polyamide copolymer, for example, a precipitant such as water or methanol. The aromatic polyamide copolymer can be isolated by passing through the mouth.

In addition, as an alternative method to the acid chloride polymerization method, a solution in which 0.9 to 1.1 mol of a mixed diamine consisting of the above diamine (I) and diamine (n) is dissolved in an organic solvent that is sparingly soluble in water and a solution that is sparingly soluble in water. A solution of 1 mol of the above dicarboxylic acid chloride dissolved in an organic solvent of
A method in which polymerization is carried out at ~80°C for 1 to 10 hours is also possible. Examples of the poorly water-soluble organic solvent used in this method include chlorobenzene, dichloroethane, trichloroethane, tetrachloroethane, chloroform, dichloromethane, methyl, ethyl ketone, cyclohexanone, acetophenone, and methylacetophenone.

Water-soluble hydrogen chloride scavengers include, for example, inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium subacid, potassium subacid, sodium hydrogen acetate, and potassium hydrogen acetate, and aliphatic alkalis such as the above hydrogen chloride scavengers. Examples include water-soluble tertiary amines and concessionary organic bases.

Specific examples of the above-mentioned aromatic dicarboxylic acid dichloride are shown in the form in which -cl is attached to the carbonyl groups on both sides of the divalent aromatic group shown above as a specific example of the A unit of the present invention, and aromatic diamine Specific examples of (I) and aromatic diamine (II) are indicated by adding -H to the amine groups on both sides of the divalent aromatic group shown as specific examples of the B unit, C unit, and D unit of the present invention. be done.

By the production method detailed above, the aromatic polyamide copolymer targeted by the present invention can be obtained, and further A units,
Melt processability and physical properties of an aromatic polyamide copolymer producing aromatic and aliphatic units constituting the polyamide in addition to the C unit and optionally included D unit at position 814 It is possible to copolymerize and use them together in a quantitative range (for example, 30 mol % or less) that does not significantly reduce the properties, and this is included within the scope of the present invention. Furthermore, a quantitative range that does not significantly reduce the melt processability and physical properties of the copolymer that produces structural units other than amide (for example, imide group units, etc.) in the aromatic polyamide copolymer of the present invention. (For example, 30 mol% or less)
It is also possible to use them together and introduce copolymerization, which is included within the scope of the present invention.

The aromatic polyamide copolymer of the present invention has a logarithmic viscosity (η1nh) measured in N-methylpyrrolidone solvent at a polymer concentration of 0.5% by weight at 30°C of 0.25 or more, preferably 0.30 or more. It is a highly polymerized polymer and can be used for various purposes such as those listed below.

Compression molding is carried out after tri-blending the aromatic polyamide copolymer powder of the present invention with different polymers, additives, fillers, reinforcing agents, etc., as required, at a temperature of usually 250 to 380°C, preferably 280 to 350°C, and pressure. 50-500 kg/m20
carried out under conditions. Also, extrusion molding and injection molding
A tri-blend of the aromatic polyamide copolymer of the present invention with different polymers, additives, fillers, reinforcing agents, etc. as required, or pellets made by extruding this into pellets using an extrusion molding machine or injection molding. feed the machine, 25
It is carried out at a temperature of 0 to 380°C, preferably 280 to 350°C. In particular, the aromatic polyamide copolymer of the present invention has an excellent balance of thermal stability and flow characteristics in the 250 to 380°C range, and is useful for extrusion molding and injection molding.

For film and fiber manufacturing applications, the polymerization termination liquid can be applied in a dry or wet-dry casting process, or the isolated polymer can be melt-molded with appropriate additives added if necessary. .

The laminate is made by impregnating a cloth or mat made of glass fiber, carbon fiber, asbestos fiber, etc. with a copolymer solution, and then precuring it by drying/heating to obtain a prepreg. ℃, 50-300k
Manufactured by pressing under conditions of g/m.

For paint applications, different types of solvents may be added and mixed to the polymerization-completed solution as needed, and then the concentration may be adjusted and used for practical use as is.

The composition of the present invention may contain the following fillers in an amount of 70% by weight or less, if necessary. (a
l Abrasion resistance improvers: graphite, carborundum, silica powder, molybdenum disulfide, fluororesin, etc., fb) Reinforcers: glass fiber, carbon fiber, boron fiber, silicon ash fiber, carbon whisker, asbestos fiber, asbestos, metal Fibers, etc., fc) Flame retardant improvers: antimony trioxide, magnesium carbonate, calcium carbonate, etc., (dl electrical property improvers: clay, mica, etc.) (e) Tracking resistance improvers: diasbestos, silica, graphite, etc. (f
) Acid resistance improvers: barium sulfate, silica, calcium metasilicate, etc. ((a) Heat conductivity improvers: metal powders such as iron, zinc, aluminum, copper, etc.) (h) Other glass beads, glass balls, Calcium carbonate, alumina, talc, diatomaceous earth, irrigation alumina, mica, shirasu balloons, asbestos, various metal oxides, inorganic pigments, etc. 250℃
The above-mentioned stable synthetic and natural compounds are included.

<Example> Hereinafter, the present invention will be explained in further detail with reference to Examples.

It should be noted that the values of %, parts, and ratios used in this example indicate the values of weight %, parts by weight, and weight ratio, respectively, unless otherwise specified. Further, the value of the logarithmic viscosity (η1nh), which is a measure of the molecular weight of the polymer, was measured in N-methyl-2-pyrrolidone solvent at a polymer concentration of 0.596 and a temperature of 30°C.

Note that measurements of various physical properties were performed according to the following methods.

Bending stress: ASTM 0790 Bending modulus: Heat distortion temperature: ASTM D648-56 (18,
56 kg/a+2) Example 1 168.2 g (0.84 mol) of 3,4'-diaminodiphenyl ether, 2
．． 2-bis(4-(4-aminophenoxy)phenyl)
147.8 g (0.36 mol) of propane and anhydrous N,
N-dimethyl 7cetamide (hereinafter abbreviated as DMAC)
2,000 g was charged and stirred to obtain a homogeneous solution.

Next, after adding 141.7 g (14 mol) of triethylamine, the reaction system was cooled to -1θ°C in a dry ice-methanol bath, and 243.6 g (1,2 mol) of isophthalic acid dichloride was added.
mol) was added in small portions at such a rate as to maintain the temperature of the polymerization system below 0°C. After the addition was completed, stirring was continued for 1 hour at 20°C, and 8.4% of benzoyl chloride was added as a terminal treatment agent.
3 g (0.06 mol) was added and stirring was continued at 20° C. for 1 hour.

Next, the polymerization finished liquid is gradually poured into water under high-speed stirring to precipitate the polymer into powder.Then, the precipitated polymer is crushed into a fine powder using an impact crusher, and then thoroughly washed with water. After dehydration, the mixture was dried in a hot air dryer at 150° C. for 5 hours and then at 200° C. for 3 hours, yielding about 444 g of a polymer powder with a logarithmic viscosity of 0.76.

The theoretical Gozo unit formula and the corresponding molecular formula of the copolymer obtained here are as follows, and the A unit and B
Alternatively, the copolymer has a structure in which C units are alternately connected, and the elemental analysis results of the copolymer showed good agreement with the theoretical values as shown below.

Hs Be C27N24 N202 liters A/B/C = 1.210.8410.36 (mole ratio) = 100/70/30 (mole ratio) Elemental analysis results Next, the obtained copolymer powder was subjected to Brabender Plastograph Ext. A uniform pellet was obtained by supplying the mixture to a Ruder (processing temperature: 300 to 330°C) and extruding it while melt-kneading. Next, the obtained pellets are molded into a small injection molding machine (processing temperature 300-330℃, pressure 1700-2100kg).
/cIN'') to prepare test pieces and measure their physical properties, and the results shown in Table 1 below were obtained.

Table 1 Comparative Example 1 Using 492.6 g (12 mol) of 2,2-bis(4-(4-aminophenoxy)phenyl)propane alone as the diamine component and l) MAC3, as the solvent.
The same operations as in the first half of Example I were carried out except that 0.000 g was used to obtain 610 g of a polymer powder having a logarithmic viscosity of 0.78.

Next, the obtained polymer was used in the same manner as in Example 1 using a Brabender Plastograph extruder (processing temperature 280°C).
-320°C) and extrusion was performed while melt-kneading to obtain uniform pellets. Next, the obtained pellets were molded into a small injection molding machine (processing temperature 280-320℃, pressure 170℃).
0 to 2100 kg/α2) to prepare test pieces and measure their physical properties, and the results shown in Table 2 below were obtained.

Table 2 As shown, melt molding can be performed without any problems by using only the second component of the diamine used in Example 1 as the diamine component, but both the strength and heat resistance of the molded product obtained are the same as in Example 1. It is inferior compared to

Comparative Example 2 The same operations as in the first half of Example 1 were carried out except that 240.3 g (1.2 mol) of 3,4'-diaminodiphenyl ether was used alone as the diamine component, and the logarithmic viscosity was 0.
376 g of polymer powder of No. 81 was obtained.

Next, the obtained polymer was supplied to a Brabender extruder (processing temperature 310 to 330°C) in the same manner as in Example 1 and extruded while melt-kneading.
Although uniform pellets were obtained, they were significantly colored. Next, the obtained pellets are used in a small injection molding machine (
Processing temperature 310-330℃, pressure 1700-2100k
g/cTM2) When a test piece was prepared and the physical properties were measured, the results shown in Table 3 below were obtained.

Table 3 Although melt molding is possible if only the first diamine component used in Example 1 is used as the diamine component, the melt viscosity during melt kneading is extremely high and the thermal stability is poor. The strength of the obtained molded product was also inferior to that of the molded product of Example 1.

Example 2 192.2 g (0.96 mol) of 3,4'-diaminodiphenyl ether and bis(4-(
4-aminophenoxy)phenyl]sulfone l O3,
8 g (0.24 mol) and 170.5 g (0.84 mol) of isophthalic acid dichloride as acid component.
mol) and 7.3.1 g of terephthalic acid dichloride
The same operations as in the first half of Example 1 were carried out except that 1 O, 36 mol) was used to obtain 429 g of a copolymer powder having a logarithmic viscosity of 0.71.

The theoretical structural unit formula and the corresponding molecular formula of this copolymer are as follows, and the elemental analysis results also showed good agreement with this theoretical value.

BeCI2 HION20 'f - (C24HI8 N2048← A I/AI[/B/C=0.8410.3610.9
610.24 (mole ratio) 70/30/80/20 (mole ratio) Next, using the obtained copolymer, melt mixing operation was performed in the same manner as in Example 1 to obtain pellets, and then small-sized injection molding was performed. machine (processing temperature 300-330℃, pressure 1700-2100k)
When test pieces were prepared and their physical properties were measured, the results shown in Table 4 below were obtained.

Table 4 Example 3 120.1 g (0.6 mol) of 3.31-diaminodiphenyl ether, 2.2-bis(
4-(4-aminophenoxy)phenyl]propane 12
402 g of copolymer powder with a logarithmic viscosity of 0.68 was prepared by carrying out the same operations as in the first half of Example 1 except for using 3.2 g (0.3 mol) and 32.4 g (0.3 mol) of m-phenylenediamine. Obtained.

The theoretical structural unit formula and the corresponding molecular formula of this copolymer are as follows, and the elemental analysis results also showed good agreement with this theoretical value.

Hs (C2y)i24N202 Length A / B / C / D = 1.2 / 0.6
/ 0.3 / 0.3 (mole ratio) = 100150/25/25 (mole ratio) Next, using the obtained copolymer, melt-kneading operation was performed in the same manner as in Example 1 to obtain pellets. , small injection molding machine (processing temperature 300-330'C1 pressure 1700-2100k
When a test piece was prepared and the physical properties were measured, the results shown in Table 5 were obtained.

Table 5 Example 4 144.2 g (0.72 mol) of 3,4'-diaminodiphenyl ether and bis(4
-(4-7minophenoxy)phenyl diketone l 90
．． 3 g (0,48 mol) and DMAC2,000
g was charged and stirred to obtain a homogeneous solution.

Next, the reaction system was cooled in a water bath, and the isophthalic acid dichloride 2
43.6 g (12 mol) was added in small portions at such a rate that the temperature of the polymerization system was maintained at 20° C. or lower. After the addition was completed, stirring was continued at 30° C. for 1.5 hours, and the resulting polymerized liquid was subjected to the same post-treatment operation as in Example 1, yielding 461 g of copolymer powder with a logarithmic viscosity of 0.65.

The theoretical structural unit formula and the corresponding molecular formula of the copolymer obtained here are as follows, and it has a structure in which A units and B or C units are alternately connected. The elemental analysis results showed good agreement with this theoretical value.

A/B/C = L210.7210.48 (mole ratio) = 100/60/40 (mole ratio) Next, using the obtained copolymer, a melt-kneading operation was performed in the same manner as in Example 1 to form pellets. Obtained. Next, the pellets are compression molded (processing temperature 310-340℃, pressure 50-100k).
g/ax') to prepare test pieces and measure their physical properties, and the results shown in Table 6 below were obtained.

Table 6 Examples 5 to 7 Copolymers were obtained by performing the same operations as in Example 1 except for using the acid component and diamine component shown in Table 7.

These copolymers each had the theoretical structural unit formula shown in Table 7, and the elemental analysis results also agreed well with the theoretical values. Next, the obtained polymer was melt-extruded into pellets in the same manner as in the second half of Example 1. The pellets were compression molded (processing temperature 280-350°C, pressure 50-100 kg/α2
), a test piece was prepared and the physical properties were measured, and the results shown in Table 7 were obtained.

Effect of the invention> The aromatic polyamide copolymer of the present invention can be heated at 250 to 380°C.
It has good melt moldability due to the combination of good thermal stability and fluidity in the temperature range of High performance materials and molded articles can be created. Taking advantage of their excellent heat resistance and mechanical properties, these materials and molded articles are widely used in fields such as electrical and electronic parts, aerospace equipment parts, automobile parts, and office equipment parts.

Claims (1)

[Scope of Claims] A, Structural unit of formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ B, Structural units of formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ and C, Formula ▲ Numerical formulas, chemical formulas, tables, etc. The structural unit ▼ is the main essential structural unit, and the ratio of each structural unit is that (B + C) is substantially 1 mol to 1 mol of A, and C is 0.40 to 0.98 mol of B. 0.60
~0.02 mol, and a thermoplastic aromatic polyamide copolymer characterized in that A and (B or C) are alternately connected. (However, in the formula, R_1 is an alkyl group having 1 to 4 carbon atoms, an alkoxy group, or a halogen group, and X is the same or different group, including a direct bond, -O-, -S-, -SO_2-,
▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲Mathematical formulas, chemical formulas,
There are tables, etc.▼, or▲There are mathematical formulas, chemical formulas, tables, etc.▼, R_2 is an alkyl group with 1 to 4 carbon atoms, a fluorine-substituted alkyl group, or a phenyl group, a is 0 or an integer from 1 to 4, and b is 1 ~ indicates an integer of 20)