JPS60137955A - Antistatic resin composition - Google Patents

Abstract

PURPOSE:To provide a composition having permanent antistatic property and excellent mechanical strength such as impact strength, flexural modulus, etc., by compounding a thermoplastic resin such as SAN resin, ABS resin, etc. with a specific graft copolymer of a diene/vinyl cyanide rubbery polymer. CONSTITUTION:(A) A obtained by the copolymerization of 50-97(wt)% aromatic vinyl monomer and/or (meth)acrylate monomer and 3-50% vinyl cyanide monomer (e.g. SAN resin) is compounded with (B) a graft copolymer (e.g. ABS resin) obtained by the polymerization of 20-95pts.(wt.) of a monomer mixture having the same composition as the component A in the presence of 5-80pts. of a rubbery polymer (e.g. SBR, EPDM, etc.) and (C) a graft copolymer produced by the polymerization of 3-90pts., preferably 10-75pts. of a monomer mixture containing >=35% vinyl monomer (as an essential component) having the polyalkylene oxide chain of formula in the presence of 10-97pts., especially 10- 75pts. of a diene/vinyl cyanide rubbery copolymer. The ratio of A and/or B to C is 40-99pts. to 1-60pts.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an antistatic resin composition that has permanent antistatic properties and is improved in mechanical strength represented by impact strength and flexural modulus.

Acrylonitrile-butadiene-styrene terpolymer (ABS) resin is used in a wide range of fields as a typical impact-resistant resin, but it has a high electrical resistivity and is easily charged, so it has various problems caused by static electricity. The disadvantage is that failures are likely to occur. Conventional methods for improving the antistatic properties of ABS resin include (1) incorporating cationic or amphoteric surfactants, and (2) replacing polybutadiene rubber with acrylonitrile, which has good conductivity, as a rubber component. −
A method using butadiene copolymer rubber (NBR) is generally practiced. (3) A method of partially copolymerizing hydrophilic monomers such as (meth)acrylamide derivatives, polyethylene glycol (meth)acrylate, and sulfonic acid derivatives during polymerization of ABS resin (JP-A-58-8
No. 317) has also been proposed. However, in method (1) above, the antistatic effect is still insufficient, and the surfactant mixed in tends to bleed out, so bleed substances may adhere to the mold surface during molding and reduce work efficiency. However, there is a problem that not only the performance as a material deteriorates, but also the antistatic property decreases due to washing or changes over time. Further, although method (2) above solves the problem caused by the surfactant bleed-out, the antistatic effect is still insufficient. Furthermore, in method (3) above, if the amount of hydrophilic monomer copolymerized is small, the antistatic effect will not be expressed, and it is necessary to copolymerize an extremely large amount of hydrophilic monomer in order to impart antistatic properties. In this case, the mechanical strength of the resulting resin, such as impact strength and flexural modulus, is significantly reduced and it cannot be used as a molding material. Therefore, the reality is that an antistatic resin that has both excellent permanent antistatic properties and mechanical strength has not yet been realized.

Therefore, the present inventors conducted intensive studies with the aim of obtaining an antistatic resin that has excellent permanent antistatic properties and excellent mechanical strength represented by impact strength and flexural modulus.
A graft copolymer obtained by polymerizing a monomer or a monomer mixture containing a vinyl monomer having a polyethylene glycol chain as an essential component in the presence of a diene/cyanated vinyl rubber-like polymer represented by BR. The inventors have discovered that the above object can be efficiently achieved by blending the polymer into a thermoplastic resin such as an acrylonitrile-styrene copolymer (SAN) resin or an ABS resin, and have thus arrived at the present invention.

That is, the present invention is directed to (1) monomers consisting of aromatic vinyl monomers, 50 to 97% by weight of (meth)acrylic acid ester monomers, and 3 to 50% by weight of vinyl cyanide monomers; Aromatic vinyl monomer and/or (meth)acrylic acid ester monomer 5 in the presence of 5 to 80 parts by weight of a rubber-like polymer
0-97% by weight and vinyl cyanide monomer 3-50%
The following formula ( A graft copolymer obtained by polymerizing 90 to 3 parts by weight of a monomer or monomer mixture containing a vinyl monomer having a polyalkylene oxide chain represented by 1) as an essential component, ) 40 to 99 parts by weight and 01
The present invention provides an antistatic resin composition in which the total amount of (6), CB) and 0 is 100 parts by weight.

-e-CH3CHO-R2... (I) (wherein, R1 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and R2 represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. (n represents an integer from 2 to 150.) Diene/cyanated vinyl rubber polymers represented by NBR (hereinafter referred to as NBR rubber polymers) themselves have relatively excellent conductivity. By polymerizing a vinyl monomer having a polyalkylenoxide chain or a monomer mixture containing the vinyl monomer as an essential component in the presence of this NBR rubber-like copolymer, conductivity can be achieved. A graft copolymer with extremely excellent properties (hereinafter referred to as "graft copolymer 0")
It is called. ) can be obtained. On the other hand, the NBR rubber-like copolymer itself has high miscibility with thermoplastic resins such as SAN resin and ABS resin, and therefore the graft copolymer (C) also has low miscibility with these thermoplastic resins. In good condition. Therefore, the graft copolymer (C) is SAN resin, A
By mixing with thermoplastic resin such as BS resin,
A resin composition that has both electrical conductivity and impact resistance can be obtained. In addition, in this resin composition, the polyalkylene oxide chains exist in a chemically bonded state in the graft copolymer (Q), so the polyalkylene oxide chains may bleed out during molding or use, or when washed. It exhibits excellent permanent antistatic properties, even though its conductivity has disappeared through wiping.

In the present invention, the copolymer ① is an aromatic vinyl monomer and/or a (meth)acrylic acid ester monomer.
~97Th,! 1%, particularly preferably 60-90% by weight
It is a copolymer obtained by polymerizing a monomer mixture consisting of 3 to 50% by weight, particularly preferably 10 to 40% by weight of a vinyl cyanide monomer. In the copolymer (8), specific examples of aromatic vinyl h-based monomers include styrene, α-methylstyrene, vinyltoluene, p-methylstyrene, and p-1-butylstyrene; (meth)acrylic acid Specific examples of ester monomers include methyl methacrylate, ethyl methacrylate, methyl acrylate, and ethyl acrylate, and specific examples of vinyl cyanide monomers include acrylonitrile and methacrylonitrile. . In the copolymer composition of copolymer ①, if vinyl cyanide monomer is less than 3% by weight (i.e., the total amount of aromatic vinyl monomer and/or (meth)acrylic acid ester monomer is If it exceeds 97% by weight), the impact strength and antistatic properties of the resin composition will be insufficient, which is not preferable. 50% by weight of vinyl cyanide monomer
(i.e. aromatic vinyl monomer and/or
Or the total number of (meth)acrylic acid ester monomers is 5
If the amount is less than 0% by weight, the resin composition will be colored and the melt fluidity will be significantly deteriorated, which is not preferable. There are no particular restrictions on the method for producing the copolymer, and the polymerization can be carried out by commonly known methods such as bulk polymerization, suspension polymerization, emulsion polymerization, solution polymerization, and bulk-M turbidity polymerization. In the polymerization of copolymer (1), there is no particular restriction on the method of feeding the monomer mixture, and any of initial batch feeding, divided feeding, and continuous feeding may be used. In the case of dividing or continuous charging, the composition may be changed during the polymerization. In addition to the above monomers, it is also possible to copolymerize other vinyl monomers within a range that does not impair the effects of the present invention.

The graft copolymer (c) in the present invention refers to an aromatic vinyl monomer and/or (meth) in the presence of 5 to 80 parts by weight, particularly preferably 10 to 70 parts by weight, of a rubbery polymer.
Single phosphor mixture 95 consisting of 50 to 97% by weight, particularly preferably 60 to 90% by weight, of acrylic acid ester monomers and 3 to 50% by weight, particularly preferably 10 to 40% by weight of vinyl cyanide monomers It is a graft copolymer obtained by polymerizing up to 20 parts by weight, particularly preferably 90 to 30 parts by weight. Examples of the rubbery polymer used in graft copolymer 0 include diene rubbers such as polybutadiene rubber, styrene-butadiene copolymer rubber (SBR), and acrylonitrile-butadiene copolymer rubber (NBR);
Acrylic combs such as polybutyl acrylate and ethylene-propylene-nonconjugated geno terpolymer rubber (
Polyolefin rubber such as EPDIV [) is used. Specific examples of the aromatic vinyl monomer, (meth)acrylic acid ester monomer, and vinyl cyanide monomer include those explained in the above copolymer ①.

In the polymerization of the graft copolymer (f3), the rubbery polymer needs to be in an amount of 5 to 80 parts by weight, preferably 10 to 70 parts by weight, and if it is less than 5 parts by weight or more than 80 parts by weight, The performance of the graft copolymer () as an impact modifier is not sufficiently exhibited, so it is not preferable. The composition of the monomer mixture as a graft component is such that the total amount of aromatic vinyl monomer and/or (meth)acrylic acid ester single star is 50 to 97% by weight, preferably 60 to 90% by weight, and vinyl cyanide. It is necessary that the monomer content is 3 to 50% by weight, preferably 10 to 40% by weight; if it deviates from this range, the performance of the graft copolymer as an impact modifier will not be fully exhibited. This is not preferable because the resulting resin composition may be colored or have poor melt fluidity. There are no particular restrictions on the method for producing the graft copolymer (1), and conventional methods such as emulsion polymerization, suspension polymerization, bulk polymerization, solution polymerization, and bulk-suspension polymerization can be used. There are no particular restrictions on the method of charging the rubbery polymer and monomer mixture, and initial batch charging, divided charging, or continuous charging can be used. In addition to the aromatic vinyl monomer, (meth)acrylic acid ester monomer, and vinyl cyanide monomer, the graft copolymer CB) may contain other substances as long as they do not impair the effects of the present invention. It is also possible to use vinyl monomers such as

In the present invention, the graft copolymer (Q refers to a vinyl monomer having a polyalkylene oxide group in the presence of an NBR rubber-like polymer (hereinafter referred to as PEG-based vinyl monomer) is an essential component. It is a graft copolymer obtained by polymerizing monomers or monomer mixtures.

The NBR rubber-like polymer in graft copolymer 0 is 40 to 95% by weight, preferably 55 to 95% by weight of conjugated diene monomers such as butadiene, isoprene, and chlorobrene.
90% by weight and 5 to 60% by weight of vinyl cyanide monomers such as acrylonitrile and methacrylate trile,
Preferably, it is a rubbery polymer formed by polymerizing a monomer mixture consisting of 10 to 45% by weight, and usually acrylonitrile-butadiene copolymer rubber (NBR) is preferably used.

PEG-based vinyl monomer in graft copolymer 0 is a vinyl-based monomer having a polyalkylene oxide group represented by the following formula (1).

R.

+CH2CHO+R2... (+) In the formula (1), R1 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, preferably a hydrogen atom or a methyl group, particularly preferably a hydrogen atom. R2 is a hydrogen atom or has 1-1 carbon atoms
It represents eight alkyl groups, preferably hydrogen atoms or methyl groups.

n is 2 to 150, preferably 4 to 50, particularly preferably 5
Represents an integer from ~30. Here, it is not preferable that the number of carbon atoms in R1 exceeds 4 and the number of carbon atoms in R2 exceeds 18 because the antistatic property is insufficient. Further, when n is less than 2, the antistatic property is insufficient, and when n exceeds 150, the polymerizability of the monomer itself is poor, which is not preferable. PEG-based vinyl monomer There is no particular restriction as long as it is a vinyl monomer having a polyalkylene oxide group represented by formula (1), but specific examples include polyethylene glycol acrylate, polyethylene glycol methacrylate, and methoxypolyethylene glycol acrylate. , methoxypolyethylene glycol methacrylate, polyethylene glycol malate (single ester type and/or double ester type), methoxypolyethylene glycol malate (
single ester type and/or double ester type), polyethylene glycol acrylamide, and methoxypolyethylene glycol acrylamide.

There are no particular restrictions on the vinyl monomer that can be polymerized with the PEG-based bivinyl monomer in the graft copolymer 0, but for example, the above-mentioned aromatic vinyl monomers, (meth)acrylic acid ester monomers, and A vinyl cyanide monomer can be used. Also, N-vinylpyrrolidone, 2
- Hydrophilic monomers such as hydroxyethyl methacrylate, acrylamide and sodium styrene sulfonate can also be used in combination.

In the polymerization of graft copolymer 0, in the presence of 10 to 97 parts by weight, preferably 25 to 90 parts by weight, of NBR rubber-like polymer, 100% by weight, preferably 25 to 100% by weight of PEG-based bivinyl monomer. Particularly preferably 35 to 10
0% by weight and 0 to 99% by weight of other polymerizable vinyl monomers, preferably 0 to 75% by weight
% by weight, particularly preferably from 0 to 65% by weight of a monomer or monomer mixture, preferably from 75 to 3 parts by weight
It is necessary to polymerize 10 parts by weight. NBR here
If the amount of the rubber-like polymer is less than 10 parts by weight, the miscibility of the graft copolymer (Q with copolymer (a) and/or graft copolymer (i) will deteriorate, resulting in a mechanical failure of the resulting resin composition). If the amount exceeds 97 parts by weight, the antistatic properties will be poor, which is not preferable.If the amount of the PEG-based bivinyl monomer in the monomer mixture is less than 1% by weight, the antistatic properties will not be exhibited, which is not preferable.

There are no particular limitations on the method for producing graft copolymer 0 (it can be polymerized using conventional methods such as emulsion polymerization, bulk polymerization, solution polymerization, suspension polymerization, and bulk-suspension polymerization). There are no particular restrictions on the method of charging the rubbery polymer and monomer, and either initial batch charging or continuous charging may be used.Furthermore, only the rubbery polymer may be charged in bulk at the beginning, and the monomers may be divided. Alternatively, continuous charging can be used.In this case, a method may also be used in which the composition of the monomer mixture is changed in the first and second stages of polymerization.

The resin composition of the present invention comprises a total amount of 40 to 99 parts by weight, preferably 50 to 95 parts by weight, of copolymer (1) and/or graft copolymer (2) and 01 to 60 parts by weight, preferably 5 parts by weight of graft copolymer (2). ~50 parts by weight ■, 03) and 0
This is a resin composition in which the total amount is 100 parts by weight. If the amount of graft copolymer 0 is less than 1 part by weight, excellent antistatic properties will not be exhibited, and if it exceeds 60 parts by weight, the mechanical properties of the resin composition will be deteriorated, which is not preferable.

There are no particular limitations on the method for producing the resin composition of the present invention, and any known method can be used. For example, depending on the form of the raw materials, there may be a method in which the raw materials are premixed using a latex blend, parater blend, or Hennel mixer, and then supplied to an extruder without premixing, followed by melt-kneading and pelletizing.

The resin composition of the present invention may further contain other thermoplastic resins such as polyamide, polybutylene terephthalate, polyethylene terephthalate, etc., within a range that does not impair the effects of the present invention.
Polycarbonate, polyphenylene oxide, polystyrene, polyvinylchloride polyethylene, polypropylene, and the like can also be mixed to achieve desired performance. Furthermore, it is also possible to further improve the antistatic property by adding an antistatic agent such as a cationic, anionic, or nonionic surfactant. Furthermore, various stabilizers such as antioxidants and ultraviolet absorbers, flame retardants, pigments, dyes, lubricants, and plasticizers can be added as necessary.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

In the example, the volume resistivity is injection molded with a thickness of 3M.
Measurements were made using a square plate of 23°C at a room temperature of 23°C and a humidity of 50% RH. For the measurement, a super insulation resistance meter 5IVI-10 manufactured by Toa Denpa Kogyo Co., Ltd. was used. Flexural modulus is ASTM
D790, Izod impact strength is ASTM D256
Measured according to method A. In addition, parts and percentages represent parts by weight and percentages by weight.

Reference Example 1 (Production of Copolymer ①) A monomer mixture having the composition shown in Table 1 was polymerized to produce copolymers <p, -1) to (A-4).

Table 1 Reference Example 2 (Preparation of Graft Copolymer (C)) Graft copolymer (C) was prepared by polymerizing a monomer mixture in the presence of a rubbery polymer according to the composition shown in Table 2.

Table 2 P13D: Polybutadiene rubber EPDM: Ethylene/propylene/non-conjugated diene terpolymer rubber Reference example 3 (manufacture of graft copolymer 0) Polymerization was carried out in the following manner and used as examples and comparative examples. Graft copolymer 0 having the composition shown in Table 3 was produced.

C-1: 150 parts of pure water, 0.5 part of glucose, 0.5 part of sodium birophosphate, and 0.5 parts of ferrous sulfate were placed in a polymerization tank purged with nitrogen.
005 parts and Butageno 75% and acrylonitrile 2
5% copolymer rubber (hereinafter referred to as rubbery polymer (a-
80 parts (solid content weight) of latex (referred to as 1)) were added and thoroughly stirred. Next, while controlling the temperature inside the tank to 60°C, methoxypolyethylene glycol methacrylate (9% for the average polymerization of ethylene oxide units) was added from one charging port.
, hereinafter referred to as vinyl monomer (b-1). )20 copies 4
It took about an hour or so to charge at a constant speed. At the same time, from another charging port, 30 parts of pure water and 2.5 parts of potassium oleinoate (emulsifier) were added.
and 0.2 parts of cumene hydroperoxide were charged uniformly over 6 hours. After the addition was completed, the temperature was raised to 75°C and polymerization was continued for an additional hour. After the polymerization was completed, magnesium sulfate was added to solidify, followed by washing, dehydration, and drying to produce a graft copolymer (C-1').

C-2 = Copolymer rubber consisting of 67% butadieno and 3396 acrylonitrile (hereinafter referred to as rubbery polymer (a-2)) as a rubbery polymer. Using 50 parts (solid weight) of latex, methoxy Polyethylene glycol methacrylate (average degree of polymerization of ethylene oxide units: 2
3, hereinafter referred to as vinyl monomer (b-2). ) 30 copies,
Graft copolymer (C-2) was prepared in exactly the same manner as graft copolymer (C-1), except that a monomer mixture consisting of 14 parts of styrene and 6 parts of acrylonitrile was charged at a constant rate over 4 hours. Manufactured.

C-3: After purging the autoclave with a stirrer with nitrogen, a copolymer rubber consisting of 90% butadiene and 10% acrylonitrile (hereinafter referred to as rubbery polymer (a-3)) 2
0 parts, dimethoxypolyethylene glycol malate (average molecular weight of ethylene oxide units: 9, hereinafter referred to as vinyl monomer (b-3)) 20 parts, styrene 51 parts,
After charging 9 parts of acrylonitrile, 0.5 parts of benzoyl peroxide and 100 parts of methyl ethyl ketone and thoroughly dissolving them, the mixture was heated at 80°C with stirring for 7 hours and 11 υ, then at 90°C.
Polymerization was carried out at ℃ for 2 hours. After the polymerization was completed, the solvent was removed to produce a graft copolymer (C-3).

Using 60 parts of C-4 rubber-like polymer (a-), Metquin polyethylene glycol acrylate (average degree of polymerization of ethylene oxide units 30, hereinafter referred to as vinyl monomer (
b-4). The graft copolymer (C-4 ,) was manufactured.

C-5=A monomer mixture consisting of 50 parts of rubbery polymer (a-1), 20 parts of vinyl monomer (b-2), 5 parts of styrene, 23 parts of methyl methacrylate, and 2 parts of acrylonitrile. The graft copolymer (C-1) was prepared in exactly the same manner as the graft copolymer (C-1) except that it was charged at a constant speed over 4 hours.
C-5) was produced.

C-6: Graft copolymer (C-6) except that 50 parts of rubbery polymer (a-1) was used, and a monomer mixture consisting of 35 parts of styrene and 15 parts of acrylonitrile was charged at constant speed over 4 hours. Graft copolymer (C
-6) was produced.

C-7: Graft copolymer (C-1) was prepared in exactly the same manner as graft copolymer (C-1) except that 80 parts of polybutadiene rubber (hereinafter referred to as PBD) was used as the rubbery polymer.
7) was manufactured.

*Rubber-like polymer a-1: butadiene/acrylonitrile = 75/2.5
(%) Copolymer rubber (latex) a-2 = butadiene/acrylonitrile = 67/33 (
%) Copolymer rubber (latex) a-3: Butadiene/acrylonitrile = 90/IO
C96) Copolymer rubber (solid) PBD: Polybutane rubber ※※ Vinyl monomer (b) b-1: Methoxypolyethylene glycol acrylate (average degree of polymerization of ethylene oxide units: 9) b-2: Methoxypolyethylene glycol Acrylate b-3'' Nidimethoxypolyethylene glycol malate b-4: Methoxypolyethylene glycol acrylate Examples Copolymers ■, graft copolymers ■, and graft copolymers (q shown in Table 4) produced in Reference Examples 1 to 3 Pellets were produced by mixing at the indicated compounding ratio, melt mixing and extrusion using a 40 silk φ extruder at a resin temperature of 220°C.Next, using an injection molding machine, the cylinder temperature was 220°C and the mold temperature was 50°C. A test piece was molded using the following method, and each physical property was measured.

The volume resistivity was measured under the following two conditions using an injection molded square plate with a thickness of 3 mm.

(1) Immediately after molding, wash with an aqueous solution of the detergent Mama Royal (manufactured by Lion Yushi Co., Ltd.), then thoroughly wash with distilled water to remove surface moisture, and then store at 23°C and 50% RH for 24 hours.
The humidity was adjusted for a period of time and measured.

(2) After molding, leave it for 100 days at 23°C and 50% RH, wash it with Mama Royal detergent aqueous solution, then thoroughly wash it with distilled water to remove surface moisture, and then
The humidity was controlled at 3° C. and 50% RH for 24 hours.

The measurement results are shown in Table 4.

Copolymer (6) produced in Reference Examples 1 to 3, graft copolymer (Q), graft copolymer (Q) and rubbery polymer (
a-1) Rubber-like polymers (a-1) obtained by coagulating latex with magnesium sulfate and dehydrating and drying were blended in the proportions shown in Table 4, and each physical property was measured in the same manner as in Examples.

The results are also shown in Table 4.

The following is clear from the results of Examples and Comparative Examples. All of the resin compositions (At-415) of the present invention have excellent mechanical properties represented by impact strength and flexural modulus, and low specific volume resistivity. Moreover, it maintains low resistivity even after surface cleaning and long periods of time after molding.
Demonstrates permanent antistatic properties. That is, the resin composition of the present invention is a resin composition that has both excellent mechanical properties and permanent antistatic properties.

On the other hand, the resin compositions of the present invention that do not contain the graft copolymer 0 (16 to 19) have a high specific volume resistivity and do not have antistatic properties. When graft copolymer 0 does not have a polyalkylene oxide chain-containing monomer component in the graft component (C-6), the resulting resin composition (420) has a high resistance value. Resin composition (4) using a graft copolymer (C-7) using polybutadiene rubber as a pace rubber
21, 22) are inferior in both impact strength and antistatic properties. The resin composition (A2'3) containing the butadiene/acrylonitrile copolymer rubber (a-1) as it is has slightly insufficient antistatic properties. In addition, graft copolymers (C-1 to (C-7)
) As is (423-30), the flexural modulus is low and the mechanical properties are poor.

As explained above, the resin composition of the present invention is an antistatic resin composition that has permanent antistatic properties and excellent mechanical properties, and is expected to find application in various fields in the future.

Patent applicant Higashi Shikikai Co., Ltd.

Claims (1)

[Scope of Claims] ■ Monomer content consisting of 50 to 97% by weight of aromatic vinyl monomer and/or (meth)acrylic acid ester monomer and 3 to 50% by weight of vinyl cyanide monomer (1) 50 to 97% by weight of an aromatic vinyl monomer and/or (meth)acrylic acid ester monomer in the presence of 5 to 80 parts by weight of a rubbery polymer; and a graft copolymer obtained by polymerizing 95 to 20 parts by weight of a monomer mixture consisting of 3 to 50% by weight of a vinyl cyanide monomer, and a diene/shea/vinyl rubber-like polymer lo
In the presence of ~97 parts by weight, 90 to 3 parts by weight of a monomer or monomer mixture containing a vinyl monomer having a polyalkylene oxide represented by the following formula (1) as an essential component are polymerized. and/or @40 to 99 parts by weight and 01 to 60 parts by weight of the graft copolymer;
(1) An antistatic resin composition in which the total of (Q) is 100 parts by weight. R. → CH2CHO+-R2 (1) (in the formula,
R1 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms;
2 represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms. n represents an integer from 2 to 150. )