WO2012102439A1

WO2012102439A1 - Oligomer-type phosphite-based antioxidant exhibiting high heat resistance, and polymer resin composition including same

Info

Publication number: WO2012102439A1
Application number: PCT/KR2011/003222
Authority: WO
Inventors: Dong-Kyung Park; Jong-Cheul KIM; Seung-Nam Kim; Jung-Du Kim; Eun-Hwa Lee
Original assignee: Songwon Industrial Co., Ltd
Priority date: 2011-01-26
Filing date: 2011-04-29
Publication date: 2012-08-02
Also published as: KR20120086582A

Abstract

Provided are an oligomer-type phosphite-based antioxidant with high heat resistance and a polymer resin composition including the same, and the antioxidant is an oligomer-type phosphite-based antioxidant represented by the above Chemical Formula 1.

Description

OLIGOMER-TYPE PHOSPHITE-BASED ANTIOXIDANT EXHIBITING HIGH HEAT RESISTANCE, AND POLYMER RESIN COMPOSITION INCLUDING SAME

An oligomer-type phosphite-based antioxidant having excellent heat resistance and a polymer resin composition including the same are provided.

In general, a resin composition used to manufacture a plastic product needs a stabilizer against oxidation due to undesirable changes such as chain breaking, cross-linking, discoloring, and the like, as well as a mechanical or physical property change of the resin. The stabilizer may in general be an antioxidant, for example, a hindered phenol-based or phosphorus antioxidant.

This antioxidant may most effectively and conveniently protect the resin from modification. Examples of the phosphorus antioxidant may include a pentaerythritol diphosphite-based antioxidant, which can effectively maintain color stability and thus may be applied in various fields.

However, the phosphorus antioxidant has bad hydrolysis resistance because of phosphorus characteristics. Accordingly, the antioxidant with a powder or pellet shape absorbs moisture during storage and thereby entangles or conglomerates the stabilizer. As a result, the antioxidant becomes hard to supply or handle. In addition, when the antioxidant is exposed to moisture, it may be hydrolyzed and thus reduce stability, so that it deteriorates stabilityof the resin composition.

Therefore, for the antioxidant, an organic phosphite with an aryl group that is hindered to have hydrolysis resistance is used. For the organic phosphite with an aryl group that is hindered, tris-(2,4-di-tert-butylphenyl)phosphite having good hydrolysis stability is widely used. However, the organic phosphite has a low molecular weight and thus may be easily volatilized during the resin manufacturing process.

In addition, the organic phosphite has no satisfactory effect on coloring stability and fusion-flow stability, and also has low compatibility with a resin and stability in the resin due to the high melting point and thus may have a plate-out or blooming problem. In addition, a monomer-type antioxidant may be easily volatilized and thus may smell bad when used to prepare a resin composition requiring high temperatures for forming. The monomer-type antioxidant may bring about a problem of movement, evaporation, extraction, or the like in the resin composition.

One embodiment of the present invention provides an oligomer-type phosphite-based antioxidant having excellent heat resistance.

Another embodiment of the present invention provides a polymer resin composition including the antioxidant.

Yet another embodiment of the present invention provides a molded product manufactured using the polymer resin composition.

According to one embodiment of the present invention, an oligomer-type phosphite-based antioxidant represented by the following Chemical Formula 1 is provided.

[Chemical Formula 1]

In Chemical Formula 1,

R¹to R¹²are the same or different and are hydrogen or an alkyl group,and

n is an integer ranging from 1 to 10.

The oligomer-type phosphite-based antioxidant may have a weight average molecular weight (Mw) of 1000 to 5000.

According to another embodiment of the present invention, a polymer resin composition including the oligomer-type phosphite-based antioxidant represented by Chemical Formula 1 and a polymer resin is provided.

The polymer resin may be selected from the group consisting of polyolefin, polyethylene, polypropylene, polyester, polycarbonate, polyamide, polyurethane, polysulfone, polyimide, polyphenylene ether, a styrene polymer, an acrylic polymer, polyacetal, a halogenated polymer, and a combination thereof.

The phosphite-based antioxidant may be included in an amount ranging from 0.01 parts by weight to 0.5 parts by weight based on 100 parts by weight of the polymer resin.

According to another embodiment of the present invention, a product molded by using the polymer resin composition is provided.

The present invention provides an antioxidant with excellent heat resistance and particularly excellent long-term heat resistance and high hydrolysis stability, and thus provides no environmental contamination and easy handling, and accordingly may be usefully applied to various polymer resins.

Exemplary embodiments of this disclosure will hereinafter be described in detail. However, these embodiments are only exemplary and do not limit this disclosure.

[Chemical Formula 1]

In Chemical Formula 1,

R¹to R¹²are the same or different and are hydrogen or an alkyl group,

n may be an integer ranging from 1 to 10.

In some embodiment, R¹to R¹²are the same or different and are hydrogen, a methyl group, a tertiary butyl group, or a tertiary pentyl group,

As used herein, when specific definition is not otherwise provided, the term "alkyl group" may refer to linear or branched C1 to C4 alkyl groups and the like.

The oligomer-type phosphite-based antioxidant may have a weight average molecular weight (Mw) of 1000 to 5000. When the oligomer-type phosphite-based antioxidant has a weight average molecular weight within the range, the oligomer-type phosphite-based antioxidant may have appropriate oligomer characteristics and a low melting point, and thus excellent compatibility with a polymer resin.

The phosphite-based antioxidant represented by the above Chemical Formula 1 is an oligomer type. Accordingly, when the phosphite-based antioxidant is used for a polymer resin composition, it may have better compatibility and durability with the polymer resin than a monomer-type antioxidant or a compound-type antioxidant. In general, when an antioxidant with a small molecular weight, that is, a monomer-type antioxidant or a compound-type antioxidant, is included in a resin composition, the antioxidant may be easily volatilized and smell bad and have a problem of migration in the resin composition (a phenomenon in which an antioxidant has low solubility to a polymer resin and moves up to the surface), evaporation, and extraction. According to one embodiment of the present invention, an oligomer-type antioxidant has a high molecular weight and is also an oligomer type that is closer to a resin than a monomolecular compound, and accordingly may not have these problems.

Furthermore, an oligomer-type phosphite-based antioxidant represented by the above Chemical Formula 1 includes a functional group induced from 4,4'-biphenol having a high melting point and a stable structure, and thus may have high heat resistance. Accordingly, an antioxidant according to one embodiment of the present invention may be usefully applied to engineering plastics requiring a high manufacturing temperature.

In addition, the oligomer-type phosphite-based antioxidant represented by the above Chemical Formula 1 includes a functional group induced from 4,4'-biphenol having a high melting point, but has a low melting point of 100 or less, i.e., the low melting point of ranging from 20 to 90℃.

Accordingly, the oligomer-type phosphite-based antioxidant has better compatibility with a resin and solubility in the resin than a conventional phosphite-based antioxidant with a high melting point, and thus decreases a problem such as deposition or blooming, and accordingly may be applied to various resins.

In addition, the oligomer-type phosphite-based antioxidant is combined with a functional group that is cubically hindered at both ends, and thus has excellent hydrolysis stability. The oligomer-type phosphite-based antioxidant represented by the above Chemical Formula 1 according to one embodiment of the present invention may be prepared in the following two methods. Hereinafter, each manufacturing method is illustrated in detail.

1) First method

4,4'-biphenyl and phosphorus trihalide are reacted under a catalyst to prepare tetrahalogen 4,4'-biphenol diphosphite.

The phosphorus trihalide may include PCl₃, PBr₃, PI₃, or a combination thereof.

The catalyst may include tri-n-alkylamine. In this tri-n-alkylamine, an n-alkyl group may have two or more carbons and less than ten carbons. Examples of the tri-n-alkylamine may include a combination of tertiary alkyl amines such as tri-n-ethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-pentylamine, di-n-butyl-n-pentylamine, and the like.

The 4,4'-biphenol and the phosphorus trihalide are mixed in a mole ratio ranging from 1:1 to 1:5. When the 4,4'-biphenol and phosphorus trihalide are mixed within the ratio, a side reaction may be minimized.

The reaction may be performed under an inert atmosphere such as with nitrogen, argon, and the like.

Furthermore, the reaction may be performed in a solvent. Herein, the solvent may be selected from the group consisting of xylene, toluene, hexane, heptane, methylene chloride, chloroform, chlorobenzene, ethylbenzene, benzene, and a combination thereof.

Then, the resulting reactant, tetrahalogen 4,4'-biphenyl diphosphite, is reacted with an alkyl-substituted phenol.

The alkyl-substituted phenol may be selected from the group consisting of 2,4,6-tri-alkylphenol, di-alkylphenol, and a combination thereof, and in particular, 2,4,6-tri-tert-butylphenol, 2,4-di-tert-butylphenol, 2,4,6-tri-tert-pentylphenol, 2-tert-butyl-4-methylphenol, 2,6-di-tert-butylphenol, 2,4-di-tert-pentylphenol, 2-methyl-4,6-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, 2-methyl-6-tert-butylphenol, 2,6-dimethylphenol, or a combination thereof. The alkyl-substituted phenol may preferably include 2,6-di-tert-butylphenol, 2,4-di-tert-methylphenol, 2-methyl-6-tert-butylphenol, 2-methyl-4,6-di-tert-butylphenol, 2,6-dimethylphenol, or a combination thereof.

The alkyl-substituted phenol may be used in an amount of 1.9 to 2.2mol based on 1mol of the phosphorus trihalide. When the alkyl substituted phenol is included within the range, it is easy to remove excess phenol and to acquire a good quality product.

The reaction of the reaction product with the alkyl substituted phenol may be performed by heating them from room temperature to about 120 to about 150℃ and reacting them for about 20 to about 30 hours at the heated temperature.

In this process, the oligomer-type phosphite-based antioxidant represented by the above Chemical Formula 1 may be prepared.

2) Second Method

Phosphorus trihalide and an alkyl substituted phenol are reacted under a presence of a catalyst, preparing an alkyl halogen phosphite.

Next, the alkyl halogen phosphite is reacted with 4,4'-biphenol.

This manufacturing method includes the same phosphorus trihalide, alkylated phenol, mixing ratio, reaction condition, and the like as the first method, and will not be described in detail.

According to these methods, a phosphite-based oxide represented by the above Chemical Formula 1 according to one embodiment of the present invention may be prepared. In addition, these first and second methods may be step-wisely performed and may be appropriately selected depending on the kind of alkylphenol used. If all the materials are simultaneously mixed and reacted (one batch), a phosphite-based oxide represented by the above Chemical Formula 1 according to one embodiment of the present invention may not be prepared.

According to another embodiment of the present invention, a polymer resin composition including the phosphite-based antioxidant represented by the above Chemical Formula 1 may be provided.

The polymer resin composition may include the phosphite-based antioxidant and a polymer resin. Herein, the phosphite-based antioxidant may be included in an amount of 0.01 parts by weight to 0.5 parts by weight based on 100 parts by weight of a polymer resin.

The polymer resin may be selected from the group consisting of polyolefin, polyethylene, polypropylene, polyester, polycarbonate, polyamide, polyurethane, polysulfone, polyimide, polyphenylene ether, polystyrene, acrylic polymer, polyacetal, a halogenated polymer (polyvinyl chloride, polyvinyl bromide, polyethylene chloride, and the like), and a combination thereof. The desirable polymer may include a polyolefin. The polyolefin may include polypropylene, polyethylene, and the like.

Furthermore, the polymer resin composition may further include an additive, for example, a heat stabilizer, an antioxidant, and the like. The additive may be included in an amount of 0.01 to 1 parts by weight based on 100 parts by weight of the polymer resin.

Examples

Hereinafter, the present invention is illustrated in more detail with reference to examples.However, these are exemplary embodiments of present invention and are not limiting.

Preparation of an antioxidant

Example 1: Preparation of phosphorous acid 4'-[bis-(2-tert-butyl-6-methyl-phenoxy)-phosphanyloxy]-biphenyl-4-yl ester bis-(2-tert-butyl-6-methyl-phenyl) ester represented by the following Chemical Formula 1a

[Chemical Formula 1a]

(In the above Chemical Formula 1a, n denotes 2.3. Accordingly, the compound has a weight average molecular weight of 1411.)

A 1000ml four-necked reactor equipped with a reflux cooler, a thermometer, and a reactor was made to have a nitrogen atmosphere. Then, 167.5g (1.0mol) of 2-methyl-6-tert-butylphenol, 68.7g (0.5mol) of phosphorus trihalide, 3.4g (0.018mol) of tributylamine, and 167.5g of a xylene solvent were put in the reactor.

The reactor was heated to 140℃ and matured at the same temperature for 20 hours. The resulting reactant was cooled to 50℃, and 44.2g (0.24mol) of 4,4'-biphenol was added thereto. The mixture was heated to 140℃ and agitated at the same temperature for 20 hours.

After the reaction, the reactant was washed with water and concentrated under reduced pressure. The acquired reactant was cooled, acquiring a white solid product. The product had a yield of 85.6%, which is 182.8g. The product had a melting point (Mp) of 62.1℃.

The product was evaluated regarding physical properties, and the results are provided as follows. In the following experiment results, ¹H-NMR was measured by using Varian Gemini-300 (CDCl₃, ppm unit), and IR was measured by using a BIORAD spectrometer.

¹H-NMR (CDCl₃,ppm): 7.27-7.23 (d,4H, aromatic protons), 7.19-7.16 (d, 4H, aromatic protons), 7.05-7.02 (d, 4H, aromatic protons), 7.00-6.97 (t, 4H, aromatic protons), 6.52-6.49 (d, 4H, aromatic protons), 2.45 (s, 12H, methyl group of 6-tert-butyl-o-cresol), 1.47 (s, 36H, tert-butyl group protons)

IR data cm^-1: 3077.0 (w, aromatic C-H stretch), 2958.2-2870.2 (s, aliphatic C-H stretch), 1601.8 (m,C=C), 1492.1 (s, aromatic C=C), 1415.6(s, CH₃bend), 1203.7 (s,C-O), 864.2 (s,P-O)

Example 2: Preparation of phosphorous acid 4'-[bis-(2,4-di-tert-butyl-6-methyl-phenoxy)-phosphanyloxy]-biphenyl-4-yl ester bis-(2,4-di-tert-butyl-6-methyl-phenyl) ester represented by the following Chemical Formula 1b

[Chemical Formula 1b]

(In the above Chemical Formula 1b, n is 1.5. Accordingly, the compound had a weight average molecular weight of 1349.)

A 3000ml four-necked reactor equipped with a reflux cooler, a thermometer, and a reactor was made to have a nitrogen atmosphere. Then, 404.6g (1.8mol) of 2-methyl-4,6-di-tert-butylphenol, 123.6g (0.9mol) of phosphorus trihalide, 8.1g (0.044mol) of tributylamine, and 404.6g of a xylene solvent were put in the reactor.

The reactor was heated to 140℃ and matured at the same temperature for 20 hours. The reactant was cooled to 50℃, and 79.6g (0.4mol) of 4,4'-biphenol was added thereto. The mixture was heated to 140℃ and agitated at the same temperature for 20 hours.

After the reaction, the reactant was washed with water and concentrated under reduced pressure. The acquired reactant was cooled, preparing a white solid product. The product had a yield of 86.3%, which is 345.6g. The product had a melting point (Mp) of 81.8℃.

The product was evaluated regarding physical properties according to the same method as Example 1, and the results are as follows.

¹H-NMR (CDCl₃, ppm):7.27 (s, 4H, aromatic protons), 7.15-7.12 (d, 4H, aromatic protons), 7.05 (s, 4H, aromatic protons), 6.46-6.43(d, 4H, aromatic protons), 2.44(s, 12H, methyl group of 4,6-di-tert-buthyl-2-methyl phenol), 1.46(s, 36H, tert-butyl group protons), 1.31(s, 36H, tert-butyl group protons)

IR data cm^-1: 3034.2 (w, aromatic C-H stretch), 2960.7-2868.6 (s, aliphatic C-H stretch), 1601.6 (m, C=C), 1492.5 (s, aromatic C=C), 1362.1(m, CH₃bend), 1198.4 (s, C-O), 850.4 (s, P-O)

Example 3:

Preparation of phosphorous acid 4'-[bis-(2,6-dimethyl-phenoxy)-phosphanyloxy]-biphenyl-4-yl ester bis-(2,6-dimethyl-phenyl) ester) represented by the following Chemical Formula 1c.

[Chemical Formula 1c]

(In the above Chemical Formula 1c, n is 7.2. Accordingly, the compound had a weight average molecular weight of 2831.)

A 3000ml four-necked reactor equipped with a reflux cooler, a thermometer, and a reactor was made to have a nitrogen atmosphere. Then, 139.7g (0.8mol) of 4,4'-biphenol, 206.0g (1.5mol) of phosphorus trihalide, and 2.8g (0.028mol) of triethylamine were put in the reactor.

The mixture was matured at room temperature for 5 hours, and 300g of a xylene solvent was added thereto. The resulting mixture was further matured for 15 hours.

This product was mixed with 359.3g (2.9mol) of 2,6-dimethylphenol (2,6-xylenol). The mixture was heated to 120℃ and matured at the same temperature for 20 hours.

When the reaction was complete, the reactant was concentrated under reduced pressure. The resulting reactant was cooled, acquiring a transparent white liquid product. The product had a yield of 87.0%, which is 476.8g.

The acquired product was evaluated regarding physical properties according to the same method as Example 1, and the results are as follows.

¹H-NMR (CDCl₃,ppm): 7.45-7.30 (m, 4H, aromatic protons), 7.17-7.13 (m, 4H, aromatic protons), 7.02-6.96 (m, 8H, aromatic protons), 6.94-6.87 (m, 4H, aromatic protons), 2.32 (s, 24H, methyl group of 2,6-xylenol)

IR data cm^-1: 3035.8 (w, aromatic C-H stretch), 2955.1-2855.3 (w, aliphatic C-H stretch), 1601.5 (w, C=C), 1491.1 (s, aromatic C=C), 1164.9 (s, C=O), 865.2 (s, P-O)

Example 4

Preparation of phosphorous acid 4'-[bis-(2,4-di-tert-butyl-phenoxy)-phosphanyloxy]-biphenyl4-yl ester bis-(2,4-di-tert-butyl-phenyl) ester) represented by the following Chemical Formula 1d

[Chemical Formula 1d]

(In the above Chemical Formula 1d, n is 3.7. Accordingly, the compound had a weight average molecular weight of 2221.)

The mixture was matured at room temperature for 5 hours, and 300g of a xylene solvent was added thereto and further matured for 15 hours.

The matured reactant was mixed with 618.9g (3.0mol) of 2,4-di-tert-butylphenol. The mixture was heated to 120°C and matured at the same temperature for 20 hours.

After the reaction, the reactant was concentrated under reduced pressure. The concentrated reactant was cooled, acquiring a white solid product. The product had a yield of 96.7%, which is 774.1g. The product had a melting point (Mp) of 67.2℃.

Then, the product was evaluated regarding physical properties according to the same method as Example 1, and the results are as follows.

1H-NMR (CDCl₃, ppm): 7.50-7.43 (m, 4H, aromatic protons), 7.40-7.32 (m, 4H, aromatic protons), 7.31-7.29 (m, 4H, aromatic protons), 7.27-7.18 (m, 4H, aromatic protons), 7.15-7.06 (m, 4H, aromatic protons), 1.38 (s, 36H, tert-butyl group protons), 1.30 (s, 36H, tert-butyl group protons)

IR data cm^-1: 3034.8 (w, aromatic C-H stretch), 2960.5-2867.8 (s, aliphatic C-H stretch), 1602.5 (m, C=C), 1491.1 (s, aromatic C=C), 1361.8 (m, CH₃bend), 1192.4 (s, C-O), 855.0 (s, P-O)

Comparative Example 1

Tris(2,4-di-tert-butylphenyl)phosphite represented by the following Chemical Formula 2 was used. This compound had a melting point (Mp) ranging from about 181 to 187℃.

[Chemical Formula 2]

Comparative Example 2

Tetrakis(2,4-di-tert-butylphenyl)-1,1-biphenyl-4,4'-diylbisphosphonite represented by the following Chemical Formula 3 was used. This compound had a melting point (Mp) ranging from about 93 to 99℃.

[Chemical Formula 3]

[Analysis Result]

Thermo-gravimetric analysis (TGA) Experiment

The products according to Examples 1 to 4 and the compounds according to Comparative Examples 1 to 3 were evaluated regarding TGA to evaluate thermal stability, and the results are provided in the following Table 1. The results provided in the following Table 1 indicated temperature at which weight loss ratios of 10wt% and 50wt% was reached, by heating a compound under a N₂atmosphere at a rate of 20°C/min and reaching. This experiment was performed by using a TGA device (TA 2100: TA Instruments).

Table 1

Weight loss (%)	Example 1	Example 2	Example 3	Example 4	Comparative Example 1	Comparative Example 2
10%	380.75℃	345.05℃	283.20℃	325.16℃	299.17℃	319.54℃
50%	420.03℃	410.88℃	411.40℃	440.28℃	339.15℃	409.15℃

As shown in Table 1, the products according to Examples 1 to 4 reached a weight loss of 50% at a very high temperature compared with the compounds according to Comparative Examples 1 to 2. As a result, the products according to Examples 1 to 4 had excellent heat resistance.

In addition, the products according to Examples 1 to 4 all had a melting point of 90℃ or less, and thus excellent compatibility with a resin compared with the compounds with a melting point ranging from about 93 to 190℃ according to Comparative Examples 1 and 2. Furthermore, the products according to Examples 1 to 4 had a low melting point and an oligomer-type molecule structure, and thus excellent compatibility with a resin compared with the compounds with a singular molecule and a high melting point according to Comparative Examples 1 and 2.

[Preparation of a resin composition]

Example 5

0.15 parts by weight of the product according to Example 1 and 0.05 parts by weight of Songstab SC-100 (a heat stabilizer) were mixed with 1 part by weight of a polypropylene homopolymer, and 99 parts by weight of a polypropylene homopolymer was added thereto. The resulting mixture was mixed with a tubular blender for 30 minutes, preparing a resin composition.

Example 6

A resin composition was prepared according to the same method as Example 5, except for using the product of Example 2 instead of the product of Example 1.

Example 7

A resin composition was prepared according to the same method as Example 5, except for using the product of Example 3 instead of the product of Example 1.

Example 8

A resin composition was prepared according to the same method as Example 5, except for using the product of Example 4 instead of the product of Example 1.

Comparative Example 3

A resin composition was prepared according to the same method as Example 5, except for using the product of Comparative Example 1 instead of the product of Example 1.

Comparative Example 4

A resin composition was prepared according to the same method as Example 5, except for using the product of Comparative Example 2 instead of the product of Example 1.

* Melt Flow Index (MFI) measurement

The resin compositions according to Examples 5 to 8 and Comparative Examples 3 to 4 were respectively put in a twin-screw extruder having a die diameter of 37mm and L/D 40 at a rate of 10kg per hour

The extrusion was performed at a top to bottom extruder temperature of 190℃/195℃/200℃/205℃/210℃/215℃ under 10,000ccm of nitrogen and an axis rotation speed of 150rpm, fabricating a compounding pellet.

The compounding pellet was extruded one to five times by using a single-screw extruder with L/D 25 in a twin-screw extruder. The extrusion was performed at a top to bottom extruder temperature of 230℃/250℃/255℃ under air at an axis rotation speed of 25rpm.

The once-extruded pellet, three-time-extruded pellet, and compounding pellet were evaluated regarding melt index at 230℃ under a load of 2.16kg by using a melt index measurement device. The results are provided in the following Table 2. In the following Table 2, pass 1 is a once-extruded pellet, and pass 3 is a three-time-extruded pellet.

Table 2

(unit: g/10min)

	Example 5	Example 6	Example 7	Example 8	Comparative Example 3	Comparative Example 4
Compounding pellet	3.46	3.73	3.27	3.60	3.94	3.40
Pass 1	5.54	6.19	5.11	5.40	8.13	5.17
Pass 3	22.10	35.15	14.01	26.84	X	40.65

Referring to the results in Table 2, as for a compounding pellet, the compositions according to Examples 5 to 8 and Comparative Examples 3 and 4 all had similar MFI values. However, as for a once-extruded pellet, the composition according to Comparative Example 4 had a similar value to the pellets according to Examples 5 to 8. The composition according to Comparative Example 3 had a somewhat higher value than the compositions according to Examples 5 to 8.

In addition, as for a three-time-extruded pellet, the composition according to Comparative Example 3 had so high an MFI value that the three-time extrusion was not performed at all. The composition according to Comparative Example 4 had an extremely high MFI valuecompared with the compositions according to Examples 5 to 8. If multi-extrusions do not change an MFI value a great deal, an antioxidant works appropriately in a resin composition. Accordingly, since the compositions according to Examples 5 to 8 did not have extremely increased MFI despite several extrusions, the products of Examples 1 to 4 used therein turned out to appropriately work therein as an antioxidant. As a result, the compounds according to Comparative Examples 3 and 4 had better anti-oxidation effects than the ones according to Comparative Examples 1 and 2.

Example 9

0.10 parts by weight of the product according to Example 1, 0.05 parts by weight of Songstab SC-100 (a heat stabilizer), and 0.05 parts by weight of Songnox 1010 (an antioxidant) were mixed with one part by weight of a polypropylene homopolymer, and 99 parts by weight of polypropylene homopolymers were added thereto. The final mixture was mixed with a tubular blender for 30 minutes, preparing a resin composition.

Example 10

A resin composition was prepared according to the same method as Example 9, except for using the product according to Example 2 instead of the product according to Example 1.

Example 11

A resin composition was prepared according to the same method as Example 9, except for using the product according to Example 3 instead of the product according to Example 1.

Example 12

A resin composition was prepared according to the same method as Example 9, except for using the product according to Example 4 instead of the product according to Example 1.

Comparative Example 5

A resin composition was prepared according to the same method as Example 9, except for using the product according to Comparative Example 1 instead of the product according to Example 1.

Comparative Example 6

A resin composition was prepared according to the same method as Example 9, except for using the product according to Comparative Example 2 instead of the product according to Example 1.

* Melt Flow Index (MFI) Measurement

The resin compositions according to Examples 9 to 12 and Comparative Examples 5 to 6 were respectively put in a twin-screw extruder with a die diameter of 37mm and L/D 40 at a rate of 10kg per hour.

The extrusion was performed at a top to bottom extruder temperature of 190℃/195℃/200℃/205℃/210℃/215℃ under 10,000ccm of nitrogen at an axis rotation speed of 150rpm, preparing a compounding pellet.

The compounding pellet prepared in a twin-screw extruder was extruded one to five times by using a single-screw extruder with L/D 25. The extrusion was performed at a top to bottom extruder temperature of 230℃/250℃/255℃ under air at an axis rotation speed of 25rpm.

In addition, a polypropylene homopolymer compounding pellet was prepared according to the aforementioned compounding pellet process by using only a polypropylene homopolymer resin.

The once-extruded pellet, three-time-extruded pellet, and five-time-extruded pellet among the multi-extruded pellets and the polypropylene homopolymer compounding pellet prepared according to the aforementioned process were evaluated regarding melt index at 230℃ with a load of 2.16kg by using a melt index measuring device. The results are provided in the following Table 3. In the following Table 3, pass 1 is the once-extruded pellet, pass 3 is the three-time-extruded pellet, and pass 5 is the five-time-extruded pellet.

Table 3

(unit: g/10 min)

	Example 9	Example 10	Example 11	Example 12	Comparative Example 7	Comparative Example 8
Pass 1	4.220	4.870	3.600	4.410	5.540	5.070
Pass 3	6.270	7.800	4.720	7.020	9.560	9.780
Pass 5	8.890	11.860	5.930	12.680	15.660	19.240

As shown in Table 3, as for the once-extruded pellet, the pellets of Comparative Examples 7 and 8 had a somewhat higher MFI value than the pellets of Example 9 to 12. In addition, comparing the MFI of the once-extruded pellet with the MFI of the three-time-extruded pellet, the difference between MFI of the three time-extruded pellet and that of once extruded pellet was much higher in Comparative Examples 7 and 8, than that in Examples 9 to 12. Especially, the difference between MFI of the five-time extruded pellet and that of once extruded pellet was greater in the Comparative Examples 7 ad 8, than that in Examples 9 to 12.

Based on the above results, since the resin compositions according to Examples 9 to 12 did not have extremely increased MFI despite multiple extrusions, the products according to Examples 1 to 4 turned out to appropriately work as an antioxidant in the resin compositions, and resultantly had better anti-oxidation effects than the compounds according to Examples 1 and 2 included in the compositions according to Comparative Examples 7 and 8.

* Yellow Index Measurement

The once-extruded pellet, three-time-extruded pellet, and five-time-extruded pellet among the multi-extruded pellets prepared according to Example 5 to 8 and Comparative Examples 3 to 4 were evaluated regarding yellow index by using a spectrophotometer (Hunterlab Ultrascan PRO). The results are provided in the following Table 4. In the following Table 4, pass 1 indicates the once-extruded pellet, and pass 3 indicates the three-time-extruded pellet. In addition, Table 4 provides a yellow index difference (△YI) between the three-time-extruded pellet and the compounding pellet.

Table 4

(no unit)

	Example 5	Example6	Example 7	Example 8	Comparative Example 3	Comparative Example 4
Compounding pellet	-1.520	-1.820	-3.640	-2.100	-2.430	-2.120
Pass 1	1.02	0.83	-1.10	0.39	-0.43	0.65
Pass 3	1.94	1.42	0.31	1.33	X	2.01
△YI	3.46	3.24	3.95	3.43	X	4.13

As shown in Table 4, the pellets according to Examples 5 to 8 had a smaller yellow index difference (△YI) than the pellet according to Comparative Example 4, and thus had excellent antioxidant effects. In addition, when the pellet of Comparative Example 3 was extruded once, it had a small yellow index change. However, the pellet could not be extruded three times so that it could not be practically used.

* LTTS (Long Term Thermal Stability) Measurement

1) 135℃ Measurement

The resin compositions according to Examples 5 to 8 and Comparative Examples 3 to 4 were respective put in a twin-screw extruder with a die diameter of 37mm and L/D 40 at a rate of 10kg per hour.

The compounding pellet was put in an injection molding machine having a top to bottom temperature of 220℃/230℃/240℃/245℃, preparing a specimen with length X width X thickness of 127 X 12.7 X 1.6mm. The specimen was thermally deteriorated in a 135°C-heated gear type oven, and a point where the specimen started to show embrittlement was recorded. The results are provided in the following Table 5.

Table 5

	Comparative Example 3	Comparative Example 4	Example 5	Example 6	Example 7	Example 8
Hours	16.5	16.5	56.5	26.5	56.5	32.5

As shown in Table 5, the compounding pellets prepared by respectively using the resin compositions according to Examples 5 to 8 took a longer time to start to show embrittlement than the pellets according to Comparative Examples 3 and 4, and thus had excellent heat resistance.

2) 150℃ Measurement

The compounding pellets were put in an injection molding machine having a top to bottom temperature of 220℃/230℃/240℃/245℃, preparing a specimen having a length X width X thickness size of 127 X 12.7 X 1.6mm. The specimen was thermally deteriorated in a 150℃-heated gear type oven, and a point where the specimen started to show embrittlement was recorded. The results are provided in the following Table 6.

Table 6

	Comparative Example 4	Comparative Example 3	Example 5	Example 6	Example 7	Example 8
Hour	3.5	1.5	5.5	3.5	9.3	5.5

As shown in Table 6, compounding pellets respectively including the resin composition according to Examples 5 to 8 took a longer time than the compounding pellets according to Comparative Examples 3 and 4, and thus had excellent heat resistance.

3) 150℃ Measurement

The resin compositions prepared according to Examples 9 to 12 and Comparative Examples 5 and 6 were respectively put in a twin-screw extruder with die diameter of 37mm and L/D 40 at a rate of 10kg per hour.

The compounding pellet was put in an injection molding machine having a top to bottom temperature of 220℃/230℃/240℃/245℃, preparing a specimen with a length X width X thickness size of 127 X 12.7 X 1.6mm. The specimen was thermally degraded in a 150℃-heated gear type oven, and a point where the specimen started to show embrittlement was recorded. The results are provided in the following Table 7.

Table 7

	Comparative Example 6	Comparative Example 5	Example9	Example10	Example11	Example12
Unit (days)	16	16	24	21	28	23

As shown in Table 7, the compounding pellets including the resin compositions according to Examples 9 to 12 took a longer time to show the embrittlement than the pellets according to Comparative Examples 5 and 6, and thus had excellent heat resistance.

While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Therefore, the aforementioned embodiments are exemplary in every aspect but not limiting.

Claims

An oligomer-type phosphite-based antioxidant represented by the following Chemical Formula 1:

[Chemical Formula 1]

wherein,

R¹to R¹²are the same or different and are hydrogen or an alkyl group, and

n is an integer ranging from 1 to 10.
The oligomer-type phosphite-based antioxidant of claim 1, wherein the alkyl group is a C1 to C4 alkyl group.
The oligomer-type phosphite-based antioxidant of claim 1, wherein R¹to R¹²are the same or different and are hydrogen, a methyl group, a tertiary butyl group, or a tertiary pentyl group.
The oligomer-type phosphite-based antioxidant of claim 1, wherein the oligomer-type phosphite-based antioxidant has a weight average molecular weight of 1000 to 5000.
A polymer resin composition comprising:

the oligomer-type phosphite-based antioxidant represented by the following Chemical Formula 1; and

a polymer resin.

[Chemical Formula 1]

wherein,

R¹to R¹²are the same or different and are hydrogen or an alkyl group, and

n is an integer ranging from 1 to 10.
The polymer resin composition of claim 5, wherein the polymer resin comprises one selected from polyolefin, polyethylene, polypropylene, polyester, polycarbonate, polyamide, polyurethane, polysulfone, polyimide, polyphenylene ether, a styrene polymer, acrylic polymer, polyacetal, a halogenated polymer, and a combination thereof.
The polymer resin composition of claim 5, wherein the phosphite-based antioxidant is included in an amount of 0.01 to 0.5 parts by weight based on 100 parts by weight of the polymer resin.
A molded product fabricated by using the polymer resin composition according to claim 5.