KR20170122657A - Organic vulcanizing agents for medical rubbers compounding and methods of manufacturing the same - Google Patents

Abstract

Provided is an organic vulcanizing agent for mixing medical rubber, which is represented by chemical formula 1. The organic vulcanizing agent shows no cytotoxicity and can be usefully applied to a composition for mixing medical rubber. In the chemical formula 1, R is one or more selected from the group consisting of hydrogen and a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms respectively and independently. n is an integer of 3 to 10.

Description

Technical Field [0001] The present invention relates to an organic vulcanizing agent for medical rubber formulations, and a method for producing the same. BACKGROUND ART < RTI ID = 0.0 >

The present invention relates to an organic vulcanizing agent for medical rubber compounding and a process for producing the same. More particularly, the present invention relates to an organic vulcanizing agent for medical rubber compounding harmless to cells and a method for producing the same.

Generally, when a vulcanizing agent such as sulfur, metal oxide, or organic peroxide is applied to an unsaturated double bond in a chain polymer rubber, the rubber molecule becomes a kind of network polymer rubber and becomes an elastic body. Such vulcanization is called a vulcanization. Heat, time, pressure, and the like.

Natural rubber is not only stretched but also has waterproofing ability, but it has a disadvantage that when it is heated, it becomes sticky and when it gets cold, it breaks easily. The solution to this problem is the vulcanization method, which is characterized in that vulcanization of raw rubber or synthetic rubber by Charles Goodyear in 1839 not only increases the elasticity but also solves the problem of sticking at high temperature and breaking at low temperature Found.

The vulcanizing agent is appropriately selected and used depending on the composition of the polymer, the molecular distribution state, the structure, etc. Generally, it can be divided into an organic vulcanizing agent and an inorganic vulcanizing agent. The organic vulcanizing agent is a multifunctional organic vulcanizing agent containing an active sulfur-releasing organic vulcanizing agent, oxime, dinitroso compound, synthetic resin, and polyamine as a drug to form a crosslinked shape by bonding polymer chains of rubber, And peroxide vulcanizing agents.

Typical sulfur compounds as conventional inorganic vulcanizing agents include powdery sulfur obtained by sublimation or melt refining sulfur of a natural acid, insoluble sulfur containing a sulfuric acid carbon (CS ₂ ) insoluble matter in a particulate structure which is crystalline, and polysulfides such as calcium sulfite Colloidal sulfur made by grinding precipitated sulfur and sulfur in a colloid mill or precipitated from an insoluble colloid. However, such inorganic sulfur compounds have a problem in that when they are used as an additive in synthetic resin, their compatibility is deteriorated and adhesion is deteriorated depending on the amount of the additive.

On the other hand, an organic vulcanizing agent such as a polyfunctional organic vulcanizing agent and peroxide vulcanizing agent including an inorganic vulcanizing agent typified by a sulfur compound and an active sulfur releasing organic vulcanizing agent, oximes, dinitroso compounds, synthetic resins and polyamines Has a disadvantage of being biotoxic and has limitations in use for medical rubbers.

KR10-2007-0034153A

Embodiments of the present invention provide an organic vulcanizing agent for medical rubber formulation that is harmless to cells.

In another embodiment of the present invention, there is provided a process for preparing an organic vulcanizing agent for medical rubber formulations.

In one embodiment of the present invention, there is provided an organic vulcanizing agent for medical rubber compounding represented by the following formula (1).

[Chemical Formula 1]

(Wherein R is independently at least one member selected from the group consisting of hydrogen and substituted or unsubstituted alkyl groups having 1 to 30 carbon atoms, and n is an integer of 3 to 10.)

In an exemplary embodiment, the organic vulcanizing agent may be a reaction product of an alkylphenol compound and a disulfide disulfide.

In an exemplary embodiment, the organic vulcanizing agent may be a reaction product in which 25 to 66.7 parts by weight of the disulfide disulfide is reacted with 100 parts by weight of the alkylphenol compound.

In an exemplary embodiment, the alkylphenol compound may include at least one member selected from the group consisting of phenol, p-tert-butylphenol, p-tert-amylphenol and p-tert-octylphenol.

In an exemplary embodiment, the alkylphenol compound may be a copolymer of p-tert-butylphenol and p-tert-amylphenol.

In an exemplary embodiment, the copolymer of p-tert-butylphenol and p-tert-amylphenol may be prepared by copolymerizing the p-tert-butylphenol and p-tert-amylphenol in a weight ratio of 1: 3 to 3: Or may be formed by copolymerization.

In an exemplary embodiment, the organic vulcanizing agent may be non-toxic to cells.

In another embodiment of the present invention, there is provided a process for preparing an organic vulcanizing agent for medical rubber formulations comprising reacting an alkylphenol compound with a disulfide disulfide,

Wherein the organic vulcanizing agent is represented by the following formula (1).

[Chemical Formula 1]

(Wherein R is independently at least one member selected from the group consisting of hydrogen and substituted or unsubstituted alkyl groups having 1 to 30 carbon atoms, and n is an integer of 3 to 10.)

In an exemplary embodiment, the alkylphenol compound is phenol. The reaction between the alkylphenol compound and the disulfide disulfide can be represented by the following reaction formula (1).

[Reaction Scheme 1]

(In the above Reaction Scheme 1, m is an integer of 3 to 10.)

In an exemplary embodiment, the step of reacting the alkylphenol compound with a disulfide disulfide may be performed at 130 to 200 ° C.

In an exemplary embodiment, the organic vulcanizing agent may be non-toxic to cells.

In another embodiment of the present invention, a medical rubber compounding composition comprising an organic vulcanizing agent represented by the following general formula (1) is provided.

[Chemical Formula 1]

(Wherein R is independently at least one member selected from the group consisting of hydrogen and substituted or unsubstituted alkyl groups having 1 to 30 carbon atoms, and n is an integer of 3 to 10.)

According to the organic vulcanizing agent for medical rubber compounding of the present invention, the compatibility of the inorganic vulcanizing agent is complemented, and the rubber rubber compounding is excellent, and it is suitable for rubber processing technology and can be effectively applied to the vulcanization process of medical rubber. In addition, the organic vulcanizing agent may have a significantly lower toxicity in vivo than existing vulcanizing agents. Accordingly, it does not adversely affect the medical rubber, which is the final product, and thus can be effectively applied to the medical rubber vulcanization process.

FIG. 1 is a schematic diagram showing a method for measuring the number of cell cells in the MTT-assay and the Live & Dead Cell assay.
FIG. 2 is a graph showing the MTT-assay results of the test solutions individually containing the organic vulcanizing agent, the control group and the comparative example 1 according to Examples 1 to 7 having a molar concentration of 1%.
FIG. 3 is a graph showing the results of MTT-assay of the test solutions individually containing the organic vulcanizing agent, the control group and the comparative example 1 according to Examples 1 to 7 having a 5% molar concentration.
4 is a graph showing the MTT-assay results of the test solutions individually containing the organic vulcanizing agent, the control group and the comparative example 1 according to Examples 1 to 7 having a 10% molar concentration.
FIG. 5 is a photograph showing the cell survival analysis results of the test solutions individually containing the organic vulcanizing agent, the control group and the comparative example 1 according to Examples 1 to 7 through Live & Dead Cell assay.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Although the embodiments of the present invention have been described with reference to the accompanying drawings, it is to be understood that the same is by way of illustration and example only and is not to be construed as limiting the scope of the present invention.

Organic vulcanizing agents for medical rubber compounding

In one embodiment of the present invention, there is provided an organic vulcanizing agent for medical rubber compounding represented by the following formula (1).

[Formula 1]

(Wherein R is independently at least one member selected from the group consisting of hydrogen and substituted or unsubstituted alkyl groups having 1 to 30 carbon atoms, and n is an integer of 3 to 10.)

In an exemplary embodiment, the organic vulcanizing agent may be a reaction product of an alkylphenol compound and a disulfide disulfide.

In an exemplary embodiment, the organic vulcanizing agent may be a reaction product in which 25 to 66.7 parts by weight of the disulfide disulfide is reacted with 100 parts by weight of the alkylphenol compound. When the disulfide disulfide is reacted in an amount of less than 25 parts by weight, the unreacted alkylphenol compound remains, so that the organic vulcanizing agent can be prepared to exhibit cytotoxicity. When the reaction is performed in excess of 66.7 parts by weight, (S ₈ ), so that the organic vulcanization agent can be produced so as to be cytotoxic.

In an exemplary embodiment, the alkylphenol compound may include at least one member selected from the group consisting of phenol, p-tert-butylphenol, p-tert-amylphenol and p-tert-octylphenol.

In an exemplary embodiment, the alkylphenol compound may be a copolymer of p-tert-butylphenol and p-tert-amylphenol, in which case the in vivo toxicity of the medical rubber to which the organic vulcanizing agent is applied may be significantly reduced .

In one embodiment, when the alkylphenol compound is a copolymer of p-tert-butylphenol and p-tert-amylphenol, the p-tert-butylphenol and p-tert- May be copolymerized within a weight ratio.

In an exemplary embodiment, the organic vulcanizing agent may be non-toxic to cells. Accordingly, the medical rubber, which is the final product to which the organic vulcanizing agent is applied, also has a problem in that the cytotoxicity is significantly lowered, so that it can exhibit the non-toxic nature of cells, and thus the organic vulcanizing agent can be effectively applied to the vulcanization process of medical rubber.

Manufacturing method of organic vulcanizing agent for medical rubber compounding

In another embodiment of the present invention, there is provided a process for preparing an organic vulcanizing agent for medical rubber compounding, which comprises reacting an alkylphenol compound with a disulfide disilicide,

[Chemical Formula 1]

(Wherein R is independently at least one member selected from the group consisting of hydrogen and substituted or unsubstituted alkyl groups having 1 to 30 carbon atoms, and n is an integer of 3 to 10.)

In the above formula (1), R may be, for example, a methyl group, a tert-butyl group, a tert-amyl group or a tert-octyl group.

In an exemplary embodiment, the preparation method can be expressed as shown in the following reaction formula 1 when the alkylphenol compound is phenol.

[Reaction Scheme 1]

(In the above Reaction Scheme 1, m is an integer of 3 to 10.)

In an exemplary embodiment, the disulfuric disulfide may be introduced into a container containing an alkylphenol compound in a batch or dropwise manner, but it is preferable to add dropwise thereto.

In one embodiment, when the dichloromethane disulfide is added dropwise, the dropping rate may be from 0.1 to 10.0 g / min, and preferably from 3.0 to 7.0 g / min. When the dropping rate is more than 10.0 g / min, the initial reaction proceeds excessively rapidly, so that the exothermic heat is not only increased, but also the disubstituted disulfide and the alkylphenol compound do not react sufficiently, have. Further, in this case, all of the added dichloromethane can not be synthesized but may remain as inorganic solid sulfur (S ₈ ), so that the above-mentioned cytotoxic organic vulcanizing agent may be produced. On the other hand, when the dropping rate is less than 0.1 g / min, the process efficiency is not easy and the production speed may be delayed.

In an exemplary embodiment, the reaction can be conducted at a temperature in the range of 130 to 200 占 폚, preferably at a temperature in the range of 150 to 180 占 폚.

The reaction temperature may generally be set differently depending on the functional group of the alkylphenol compound. However, when the reaction temperature is higher than 200 ° C, the disuccinimide and the alkylphenol compound may not react sufficiently, so that the organic vulcanization agent may not be produced properly. Also, in this case, all of the added dicarboxylic dianion can not be synthesized but can remain as inorganic solid sulfur, and accordingly, the above-mentioned cytotoxic organic vulcanizing agent may be produced. On the other hand, when the temperature is lower than 130 캜, the reaction proceeds excessively slowly, which may result in a delay in the production rate.

As described above, the organic vulcanizing agent prepared by the above method may be non-toxic to cells. Accordingly, when the organic vulcanizing agent is applied in the compounding reaction of the medical rubber, the medical rubber containing the organic vulcanizing agent can be manufactured so as to have no cytotoxicity. Accordingly, it can be usefully used in the medical industry.

Medical rubber compounding composition

 In one embodiment of the present invention, there is provided a medical rubber compounding composition comprising an organic vulcanizing agent represented by the following general formula (1).

[Chemical Formula 1]

(Wherein R is independently at least one member selected from the group consisting of hydrogen and substituted or unsubstituted alkyl groups having 1 to 30 carbon atoms, and n is an integer of 3 to 10.)

In an exemplary embodiment, the medical rubber compounding composition may comprise from 1 to 2 parts by weight of the organic vulcanizing agent, from 50 to 70 parts by weight of silica, and from 10 to 30 parts by weight of carbon black, based on 100 parts by weight of the raw rubber.

In the exemplary embodiment, the raw rubber is not particularly limited as long as it is a rubber used for a medical person in general.

In an exemplary embodiment, the medical rubber compounding composition may be a mixture of conventional vulcanizing agents in addition to the above-mentioned organic vulcanizing agents according to the present invention.

As described above, the medical rubber compounding composition according to the present invention comprises an organic vulcanizing agent that is non-toxic to cells. Accordingly, the medical rubber which is finally produced can be produced so as to have the property of being non-toxic to cells.

Hereinafter, the present invention will be described in more detail with reference to Examples. It is to be understood by those skilled in the art that these embodiments are only for illustrating the present invention and that the scope of the present invention is not construed as being limited by these embodiments.

Example

[Control group]

Phosphate buffer saline (phosphate buffered saline) was used as a control.

[Comparative Example 1]

Phenol was used as Comparative Example 1.

[Example 1] Preparation of an organic vulcanizing agent

297.58 g of alkylphenol-1 (phenol) and 500 g of a solvent were placed in a 2-liter four-neck reaction vessel equipped with a double jacket reactor, a Teflon stirrer, a thermometer and a reflux condenser. 435 g of disulfide disulfide (300 g of a solvent) were added dropwise at the same time. The dropping rate was about 6.13 g / min. After the dropwise addition was completed, stirring was continued for 2 hours. Then, nitrogen purge was performed to remove HCl gas generated in the reaction tank. The HCl gas removed from the reactor was removed in salt form through a bath of aqueous base.

The organic vulcanizing agent thus obtained exhibited a sulfur content of 29.2% and a softening point of 97.5 ° C.

[Example 2] Preparation of an organic vulcanizing agent

An organic vulcanizing agent was prepared in the same manner as in Example 1, except that 652.39 g of alkylphenol-2 (p-tert-octylphenol) was used instead of the alkylphenol-1 (phenol)

[Example 3] Preparation of an organic vulcanizing agent

An organic vulcanizing agent was prepared in the same manner as in Example 1, except that 519.33 g of alkylphenol-3 (p-tert-amylphenol) was used instead of the alkylphenol-1 (phenol)

[Example 4] Preparation of an organic vulcanizing agent

An organic vulcanizing agent was prepared in the same manner as in Example 1, except that 475.00 g of alkylphenol-4 (p-tert-butylphenol) was used instead of the alkylphenol-1 (phenol)

[Example 5] Preparation of an organic vulcanizing agent

(P-tert-amylphenol) and 120.51 g of alkylphenol-4 (p-tert-butylphenol) were placed in a 2 liter four-necked reaction vessel equipped with a stirrer, a double jacket reactor, a Teflon stirrer, a thermometer and a reflux condenser (P-tert-butylphenol): alkylphenol-4 (p-tert-butylphenol) = 3: 1) and 500 g of a solvent were heated to 170 DEG C and melted. 435 g (300 g of a solvent) were added dropwise at the same time. The dropping rate was about 6.13 g / min. After the dropwise addition was completed, stirring was continued for 2 hours. Then, nitrogen purge was performed to remove HCl gas generated in the reaction tank. The HCl gas removed from the reactor was removed in salt form through a bath of aqueous base.

[Example 6] Preparation of an organic vulcanizing agent

The procedure of Example 5 was repeated except that the weight ratio of alkylphenol-3 (p-tert-amylphenol) to alkylphenol-4 (p-tert-butylphenol) was changed to 1: To prepare an organic vulcanizing agent.

[Example 7] Production of organic vulcanizing agent

The procedure of Example 5 was repeated except that the weight ratio of alkylphenol-3 (p-tert-amylphenol) to alkylphenol-4 (p-tert-butylphenol) was changed to 1: To prepare an organic vulcanizing agent.

[Comparative Example 1] Preparation of an organic vulcanizing agent cytotoxicity evaluation sample

For the evaluation of the cytotoxicity of the organic vulcanizing agents according to the present invention, samples of the respective vulcanizing agents were prepared with the compositions shown in Table 1 below.

Composition ratio of each sample Sample name Constituent Types of alkylphenol compounds used Solvent Control (control) PBS - DMSO Comparative Example 1
(phenol) Phenol - DMSO Example 1 Organic vulcanization-1 Alkylphenol-1 (phenol) DMSO Example 2 Organic Vulcanizing Agent-2 Alkylphenol-2 (p-tert-octylphenol) DMSO Example 3 Organic Vulcanizing Agent-3 Alkylphenol-3 (p-tert-butylphenol) DMSO Example 4 Organic vulcanizate-4 Alkylphenol-4 (p-tert-butylphenol) DMSO Example 5 Organic vulcanizate-5 A copolymer (3: 1) of alkylphenol-3 (p-tert-amylphenol) and alkylphenol-4 (p- DMSO Example 6 Organic Vulcanizing Agent-6 (1: 3) of alkylphenol-3 (p-tert-amylphenol) and alkylphenol-4 (p- DMSO Example 7 Organic Vulcanizing Agent-7 A copolymer (1: 1) of alkylphenol-3 (p-tert-amylphenol) and alkylphenol-4 (p- DMSO

[Experimental Example 1] Cytotoxicity of organic vulcanizing agent using fibroblast

The organic vulcanizing agent prepared according to the control, Comparative Example 1 and Examples 1 to 7 was frozen and dissolved in DMSO, diluted in PBS, and finally injected into mouse fibroblasts (NCTC Clone) in DMEM medium supplemented with 10% serum. L929) for 48 hours at 37 ° C / 5% CO ₂ .

The approximate method for the preparation of the test solution is as follows.

1) Sampling step

Sample is frozen and pulverized using freezer / mill 6770), dissolved in DMSO and diluted with PBS to prepare a sample solution.

2) Sterilization  step

Sterilize the test solution using autoclave.

3) Media manufacturing stage

Media was prepared by mixing DMEM, penicillin, FBS and test solution. "

On the other hand, the above test conditions were selected to maintain the physiological conditions most similar to the situation in which the liquid was applied to the human body.

 A cytotoxicity experiment (MTT ASSAY experiment and Live & Dead Cell assay experiment) based on "ISO 10993-5 (tests of in vivo cytotoxicity)" was performed on each sample (Comparative Examples 1 to 3) 2 and Examples 1 to 7). The evaluation criteria for toxicity according to cell viability are shown in Table 2 below. According to ISO 10993-5, it is evaluated that there is no cytotoxicity when cell viability corresponding to "Grade 0" or "Grade 1" appears.

Assessment of toxicity according to cell viability Grade Reactivity Condition 0 None Cell viability is also 100% One Slight Cell viability is 80% 2 Mild Cell viability was also 50% 3 Moderate Cell viability was also 30% 4 Severe Cell viability was also 0%

<MTT ASSAY Experiment>

The test solutions according to the control, Comparative Example 1 and Examples 1 to 7 were prepared to have a 1% molar concentration and MTT ASSAY experiments were conducted on the 1, 5 and 10 wt% dilutions thereof.

The experiment was roughly proceeded as follows.

"Stage 1: L929 cell thawing -> cell culture for 48 hours -> trypsin treatment -> centrifugation

Step 2: Cell counting is performed according to Equation (1)

(MTT ASSAY): Cells were cultured in 96 wells for 24 hours at cell counts. -> 24 hours later, the sample was added to the diluted solution. -> MTT treatment after 24 hours -> DMSO treatment after 4 hours - > Absorption Measurements

Hereinafter, experimental results of the above experiment are shown in Figs. 2 to 4. Fig.

2, a 1% molar concentration of the test solution was prepared and diluted with 1, 5, and 10 wt% of the amount of each of the test solutions in comparison with that of Comparative Example 1. As a result, in the case of 1 wt% and 5 wt% All showed cell survival rates of 80% or more and reached the level of "Grade 1" given in "ISO 10993-5". In addition, when the amount up to 10 wt% was increased, the cytotoxicity of phenol was reduced to about 50%, whereas the test solution of all samples showed cell viability consistent with "Grade 1".

Thereafter, the test solutions according to the control group, the comparative example 1 and the examples 1 to 7 were prepared to have a molar concentration of 5% and 10%, and the cell viability was analyzed in the same manner as the 1% molar concentration, and the results are shown in FIG. 3 and FIG. 3 and 4, overall cell viability was decreased, but cell viability was maintained at 80% in accordance with &quot; Grade 1 &quot;. On the other hand, when the concentration of phenol was increased to 5 wt%, the cell viability was drastically decreased.

<Live & Dead Cell Assay>

On the other hand, for the analysis through visual data, the test solutions according to the control group, the comparative example 1 and the examples 1 to 7 were prepared to have a 1% molar concentration and a Live & Dead cell assay was performed on the 10 wt% The dead cells were identified.

The experiment was roughly proceeded as follows.

"Stage 1: L929 cell thawing -> cell culture for 48 hours -> trypsin treatment -> centrifugation

Step 2: Cell counting is performed according to Equation (1)

Step 3: Cells were incubated for 24 hours at 96 wells in the number of cells counted. -> Added to the diluted solution after 24 hours. -> After 24 hours, reacted with Live & dead cell kit for 15 minutes -> Fluorescence fluorescent reading "

The experimental results of the above experiment are shown in Fig.

5, the results of the Live & Dead Cell assay showed the same tendency as those obtained by the MTT assay, and it was confirmed that a large amount of cells survived in each sample group. These results indicate that not only all the samples prepared through the synthesis of the phenol series (Comparative Examples 1 to 2 and Examples 1 to 7 are excellent in cell survival rate in comparison with phenol but also the cell survival rate is also ISO 10993 -5 in accordance with the criteria of non-toxicity of cells on the evaluation criteria.

The embodiments of the present invention described above should not be construed as limiting the technical idea of the present invention. The scope of protection of the present invention is limited only by the matters described in the claims, and those skilled in the art will be able to modify the technical idea of the present invention in various forms. Accordingly, such improvements and modifications will fall within the scope of protection of the present invention as long as it is obvious to those skilled in the art.

Claims (12)

An organic vulcanizing agent for medical rubber compounding represented by the following formula (1).
[Chemical Formula 1]

(Wherein R is independently at least one member selected from the group consisting of hydrogen and substituted or unsubstituted alkyl groups having 1 to 30 carbon atoms, and n is an integer of 3 to 10.) The method according to claim 1,
Wherein the organic vulcanizing agent is a reaction product of an alkylphenol compound and a disulfide disilicide. 3. The method of claim 2,
Wherein the organic vulcanizing agent is a reaction product in which 25 to 66.7 parts by weight of the disulfide disulfide is reacted with 100 parts by weight of the alkylphenol compound. 3. The method of claim 2,
Wherein the alkylphenol compound comprises at least one member selected from the group consisting of phenol, p-tert-butylphenol, p-tert-amylphenol and p-tert-octylphenol. 5. The method of claim 4,
Wherein the alkylphenol compound is a copolymer of p-tert-butylphenol and p-tert-amylphenol. 6. The method of claim 5,
Wherein the copolymer of p-tert-butylphenol and p-tert-amylphenol is formed by copolymerizing the p-tert-butylphenol and p-tert-amylphenol in a weight ratio of 1: 3 to 3: Organic vulcanizing agents for rubber compounding. The method according to claim 1,
Wherein the organic vulcanizing agent is non-toxic to cells. A process for producing an organic vulcanizing agent for medical rubber compounding,
Comprising reacting an alkylphenol compound with a disulfide disulfide,
Wherein the organic vulcanizing agent is represented by the following formula (1).
[Chemical Formula 1]

(Wherein R is independently at least one member selected from the group consisting of hydrogen and substituted or unsubstituted alkyl groups having 1 to 30 carbon atoms, and n is an integer of 3 to 10.) 9. The method of claim 8,
Wherein the alkylphenol compound is phenol,
Wherein the reaction between the alkylphenol compound and the disulfide disulfide is represented by the following reaction formula (1).
[Reaction Scheme 1]

(In the above Reaction Scheme 1, m is an integer of 3 to 10.) 9. The method of claim 8,
Wherein the step of reacting the alkylphenol compound and the disulfide disulfide is carried out at a temperature of 130 to 200 ° C. 9. The method of claim 8,
Wherein the organic vulcanizing agent is non-toxic to cells. A medical rubber compounding composition comprising an organic vulcanizing agent for compounding a medical rubber represented by the following formula (1).
[Chemical Formula 1]

(Wherein R is independently at least one member selected from the group consisting of hydrogen and substituted or unsubstituted alkyl groups having 1 to 30 carbon atoms, and n is an integer of 3 to 10.)

Images