KR101711942B1 - Polyoxymethylene Resin Composition and Molding Including the Same - Google Patents

Abstract

More particularly, the present invention relates to a polyoxymethylene resin composition, a hindered phenol antioxidant, a mixed salt of a fatty acid calcium salt and a fatty acid zinc salt, and a porous organic / inorganic silica gel A polyoxymethylene resin composition having improved thermal stability, and a molded article comprising the same.

Description

TECHNICAL FIELD [0001] The present invention relates to a polyoxymethylene resin composition and a molded article containing the same,

The present invention relates to a polyoxymethylene resin composition and a molded article containing the same.

BACKGROUND ART Polyoxy methylene resin is known as a high-performance plastic having a balance of mechanical strength and impact resistance, and has been used in a wide range of fields as electronic equipment and automobile parts. However, the polyoxy methylene resin has a characteristic of being easily decomposed under an acidic or alkaline condition under a heating oxidizing atmosphere in the structure. Although it is known to stabilize the chemically active terminal by improving the lack of thermal stability, formaldehyde gas is generated at the time of molding, resulting in discoloration to yellowish brown .

In order to solve this problem, it has been proposed to improve the thermal stability of a polyoxy methylene resin by including a steric hindrance phenol, a fatty acid alkaline earth metal salt having 10 to 20 carbon atoms and / or a hydroxide of an alkaline earth metal, In JP-A-55-22508 discloses a polyoxymethylene resin composition which is stabilized with respect to oxidation and pyrolysis by incorporating a steric hindrance phenol and a fatty acid alkaline earth metal salt having 22 to 36 carbon atoms in a polyoxymethylene resin. A stabilized polyoxymethylene resin composition having suppressed discoloration is disclosed in Japanese Patent Publication No. 60-56784. JP-A-3-14857 discloses a combination of a hindered amine compound, a hindered phenol-based antioxidant having a molecular weight of 400 or more and a carboxylic acid metal salt having 12 or more carbon atoms, and JP 62-45662 A discloses a combination of a fatty acid, JP-A 11-29692 discloses a kneading of at least one column selected from the group consisting of a fatty acid, a phosphate, a carbon black and a quinoline compound, an amide compound and an amine compound The combination of stabilizers has been proposed. A-34-5440 discloses a polyoxy methylene resin composition in which a polyamide resin is blended. However, the composition is excellent in thermal stability at a high temperature and for a long time, but the composition of the polyoxy methylene resin composition with formaldehyde And a color change to yellowish brown color which is the action of oxygen.

Japanese Patent Publication (Kokoku) No. 62-4422 discloses a polyoxymethylene resin composition comprising a polyamide, a fatty acid having 12 to 35 carbon atoms, a fatty acid calcium salt having 12 to 35 carbon atoms, an aliphatic alcohol having 12 to 36 carbon atoms, A polyoxy methylene resin composition having extremely few precipitates in a mold at the time of molding and excellent in thermal stability by containing at least one of the groups consisting of a magnesium salt is disclosed in Japanese Patent Publication No. 62-58387, A polyoxy methylene resin having a high thermal stability can be obtained by incorporating an amine-substituted triazine compound in a polyoxy methylene resin, a steric hindrance phenol, a hydroxide of an alkali metal or an alkaline earth metal, an inorganic acid salt, a carboxylic acid salt or an alkoxide. The composition was developed.

However, the polyoxy methylene resin composition in which these stabilizers are appropriately combined and combined also undergoes action of heat or oxygen in the cylinder of the molding machine during molding to decompose the terminal or main chain of the polymer and generate formaldehyde gas It is difficult to prevent completely from doing. In the process of stabilizing the terminal groups, formaldehyde is oxidized to formic acid, which decomposes the main chain, and the stabilizer reacts with formaldehyde and tends to cause coloration in the molded article. That is, as the stabilizer composition, there is a problem that the polyoxymethylene resin composition increases the thermal stability and suppresses discoloration at the time of molding, and the product value is lost.

The present invention relates to a polyoxymethylene resin composition having improved thermal stability while maintaining physical properties such as excellent mechanical strength and impact resistance of a conventional polyoxymethylene resin, and a molded article containing the same.

Accordingly, the present invention provides, as a first preferred embodiment, a positive resist composition comprising 0.001 to 5 parts by weight of a hindered phenol antioxidant per 100 parts by weight of a polyoxymethylene resin; 0.001 to 5 parts by weight of a mixed salt of a fatty acid calcium salt and a fatty acid zinc salt; And 0.01 to 1 part by weight of a porous organic-inorganic hybrid silica gel represented by the general formula (2).

delete

delete

delete

(2)

Here, R has the structure represented by the general formula (3).

(3)

Al ₂ Si ₂ O ₅ (OH) _X .My

Here, M is a metal selected from P, Ca, Zn, Fe, K, Mn, Mo, Ag, Mg and Ti. X is an integer of 1 to 5 and y is an integer of 2 to 7.

The hindered phenol-based antioxidant according to this embodiment may have a molecular weight of 400 or less.

The mixed salt of the fatty acid calcium salt and the fatty acid zinc salt according to the embodiment may have a mixing ratio of 5-95 wt%: 95-5 wt%.

The porous organic-inorganic hybrid silica gel according to the embodiment may be a porous organic-inorganic hybrid silica gel for adsorbing volatile organic compounds (VOCs) having a pore size of 50 nm or less and a surface area of 200 to 2000 m ² / g .

The polyoxymethylene resin composition according to this embodiment may have a Delta E of 1.5 or less at a temperature of 180 to 240 ° C for 30 minutes.

The present invention also provides, as a second preferred embodiment, a molded article comprising the polyoxymethylene resin composition.

Hereinafter, the present invention will be described in more detail.

The present invention relates to a polyoxymethylene resin composition having improved thermal stability. More specifically, the present invention relates to a polyoxymethylene resin composition comprising 0.001 to 5 parts by weight of a hindered phenol-based antioxidant per 100 parts by weight of a polyoxymethylene resin; 0.001 to 5 parts by weight of a mixed salt of a fatty acid calcium salt and a fatty acid zinc salt; And 0.01 to 1 part by weight of a porous organic-inorganic hybrid silica gel represented by the general formula (2).

delete

delete

Here, the polyoxymethylene resin may have an average molecular weight of 500 to 5,000.

(2)

Here, R has the structure represented by the general formula (3).

(3)

Al ₂ Si ₂ O ₅ (OH) _X .My

Here, M is a metal selected from P, Ca, Zn, Fe, K, Mn, Mo, Ag, Mg and Ti. X is an integer of 1 to 5 and y is an integer of 2 to 7.

The hindered phenol-based antioxidant may have a molecular weight of 400 or more. When the molecular weight is 400 or less, there is a problem in that the thermal stability which damages the appearance of the polyoxymethylene resin homopolymer composition is deteriorated.

The hindered phenol-based antioxidant may be 0.001 to 5 parts by weight based on 1000 parts by weight of the polyoxymethylene resin. If the amount is less than 0.001 part by weight and exceeds 5 parts by weight, heat stability is not sufficient.

Specific examples of the hindered phenol-based antioxidant having a molecular weight of 400 or more as the hindered phenol-based antioxidant include triethylene glycol-bis [3- (3-t-butyl ) -5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5- butyl-4-hydroxyphenyl) propionate, pentaerythritol tetrakis [3- (3,5-di-tert-butyl) -4- Hydroxyphenyl) propionate, N, N'-hexamethylene bis (3,5-di-t-butyl-4-hydroxyphenyl) propionate 2-t-butyl-6- (3'-t-butyl-5'-methyl-2'- hydroxybenzyl) Methyl phenyl acrylate, 3,9-bis [2- {3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyl Propionyl oxy} - 1,8-dimethylethyl] -2,4,8,10-tetraoxaspiro (spiro) [5,5] undecane, and the like.

The mixed salt of the fatty acid calcium salt and the fatty acid zinc salt is prepared by preliminary melt mixing of a mixed salt of a fatty acid calcium salt and a fatty acid zinc salt. Specific examples of the fatty acid that forms the calcium salt and the zinc salt in the mixed salt include stearic acid, 12-hydroxy stearic acid , Sebacic acid, lauric acid, myristic acid, and parmitic acid.

The composition of the mixed salt (C) of a fatty acid calcium salt and a fatty acid zinc salt can be variously selected, but it is usually in the range of 5 to 95% by weight of a fatty acid calcium salt and 95 to 5% by weight of a fatty acid zinc salt.

The mixed salt of the fatty acid calcium salt and the fatty acid zinc salt may be 0.001 to 5 parts by weight of the mixed salt of the fatty acid calcium salt and the fatty acid zinc salt per 100 parts by weight of the polyoxymethylene resin. If the amount is less than 0.001 part by weight, There is a problem that it becomes a source of formaldehyde gas in the subsequent injection. If it exceeds 5 parts by weight, the polymer decomposes to deteriorate physical properties or cause discoloration of the polymer.

The porous organic-inorganic hybrid silica gel can be used for improving the thermal stability and improving the discoloration of the yellowish brown color upon molding. The porous organic-inorganic hybrid silica gel can be prepared by 1) alkoxysilylalkylene having 4 or more alkoxy groups or 2) tetraalkylososilicate, 4 60 to 98% by weight of a silica precursor selected from the group consisting of alkoxysilylalkanes and alkoxysilylalkenes having one or more alkoxy groups and alkoxysilanes, alkoxyalkenylsilanes, alkoxyarylsilanes and alkoxyaralkylsilanes having 1 to 3 alkoxy groups Volatile organic compounds (VOCs) having a pore size of 50 nm or less and a surface area of 200 to 2000 m ² / g, which are prepared by hydrolysis, dehydration and washing in the presence of a surfactant in an amount of 2 to 40 wt% May be a porous silica gel for adsorption.

The content of the porous organic-inorganic hybrid silica gel may be 0.001 to 1 part by weight of a mixed salt of a fatty acid calcium salt and a fatty acid zinc salt based on 100 parts by weight of the polyoxymethylene resin. If the amount is less than 0.001 part by weight, volatile organic compounds (VOCs) However, if the content of the polyoxyethylene resin exceeds 1 part by weight, the bonding strength between the terminal groups and the resin of the polyoxymethylene resin becomes weak and decomposition occurs, And at the same time, the foaming is severely caused, and there is a problem in the synthesis process.

According to the present invention, it is possible to obtain a polyoxymethylene (polyoxy methylene) resin composition having excellent thermal stability in a high-temperature molten state of polyoxymethylene resin as described above and having excellent mechanical strength and color tone upon molding.

Hereinafter, the present invention will be described in detail with reference to preferred embodiments. However, the present invention is not limited to the following examples.

Example  1 to 10

A polyoxymethylene resin composition was prepared by blending a hindered phenol-based antioxidant, a mixed salt of a fatty acid calcium salt and a fatty acid zinc salt, and a porous organic-inorganic hybrid silica gel at a ratio shown in Table 1 per 100 parts by weight of a polyoxymethylene resin.

Comparative Example  1 to 6

A polyoxymethylene resin composition was prepared by blending a hindered phenol-based antioxidant, a mixed salt of a fatty acid calcium salt and a fatty acid zinc salt, and a porous organic-inorganic hybrid silica gel in the proportions shown in Table 3 with respect to 100 parts by weight of a polyoxymethylene resin.

Property evaluation

The properties of the polyoxymethylene resin compositions prepared in Examples and Comparative Examples were measured by the following methods, and the results are shown in Tables 2 and 4.

1. Delta E ( ΔE * _ab , color difference of two samples)

(1) The polyoxymethylene resin composition is allowed to stand in an extruder at 220 占 폚 for 5 minutes and 30 minutes, respectively.

(2) After measuring the L, a, and b values of each specimen using a color meter, calculate the value according to the following formula.

? L * = L * _t - L *

? A * = a * _t - a *

? B * = b * _t - b *

L * _t , a * _t , b * _t : the L * a * b * value of the reference sample

L *, a *, b *: the L * a * b * value of the sample

(3) For L * a * b * space, the two data color differences ΔE * _ab can be obtained from the following equation.

? E * _ab = [(? L *) ² + (? A *) ² + (? B *) ² ] ^1/2

2. YI (Yellow Index, yellow degree)

 Calculate the number of digits to the second decimal place

 YI = 100 (1.28 X -1.06 Z) / Y

Where X, Y, and Z are the three qualification values (stimulus values) of the test sample and the test piece in the standard light C, respectively.

3. MI (Melt Index)

According to ASTM D-1238, measurement is made at a temperature of 190 DEG C and a load of 2160 grams.

 (Unit: parts by weight) division Suzy Composition 1 Composition 2 Composition 3 Polyoxymethylene Example 1 100 0.5 0.01 0.5 Example 2 100 0.5 0.10 0.5 Example 3 100 0.5 0.20 0.5 Example 4 100 0.1 0.01 One Example 5 100 One 0.01 One Example 6 100 3 0.10 One Example 7 100 0.5 0.10 0.1 Example 8 100 0.5 0.10 1.5 Example 9 100 0.5 0.10 2 Example 10 100 One 0.20 1.5 - - The contents of the compositions 1, 2 and 3 were the weight parts of each composition relative to 100 parts by weight of the polyoxymethylene resin
- Composition 1: Hindered phenolic antioxidant (SONGNOX245, Songwon Industry)
- Composition 2: Mixed salt of a fatty acid calcium salt and a fatty acid zinc salt (calcium 12-hydroxystearate, zinc 12-hydroxystearate, Daeil Chemical)
- Composition 3: Porous organic-inorganic hybrid silica gel (TS-1, Taesung Environmental Research Institute)

 (Unit: displayed in parentheses separately) division Delta E YI MI Example 1 1.45 -7 One Example 2 0.62 -6.4 1.5 Example 3 1.05 -10.3 0.7 Example 4 1.4 -2 2.5 Example 5 1.0 -4.1 3 Example 6 1.2 -5.7 2.1 Example 7 0.5 -5.5 0.7 Example 8 0.8 -4 1.3 Example 9 1.2 -3 1.8 Example 10 1.4 -1.5 2.7

 (Unit: parts by weight) division Suzy Composition 1 Composition 2 Composition 3 Polyoxymethylene Comparative Example 1 100 0.5 0 0 Comparative Example 2 100 0.5 5 0 Comparative Example 3 100 0.5 6 0 Comparative Example 4 100 0.5 0 4 Comparative Example 5 100 0.5 5.5 4 Comparative Example 6 100 0.5 6 4 Comparative Example 7 100 0 0.2 0.2 Comparative Example 8 100 6 0.2 0.1 - - The contents of the compositions 1, 2 and 3 were the weight parts of each composition relative to 100 parts by weight of the polyoxymethylene resin
- Composition 1: Hindered phenolic antioxidant
- Composition 2: Mixed salt of fatty acid calcium salt and fatty acid zinc salt
- Composition 3: Porous organic-inorganic hybrid silica gel

 (Unit: displayed in parentheses separately) division Delta E YI MI Comparative Example 1 3.5 4 7 Comparative Example 2 4 3.5 8.3 Comparative Example 3 3.9 7 7.5 Comparative Example 4 6.8 5.7 12.2 Comparative Example 5 5.1 9.3 6.5 Comparative Example 6 7 14 13.4 Comparative Example 7 6 9 13.1 Comparative Example 8 4 5 11.5

As a result of evaluation of physical properties, as shown in Table 2, it was found that the polyoxymethylene resin composition of the examples had a small value of Delta E, YI and MI and a low probability of discoloration and a high thermal stability.

On the other hand, as shown in Table 4, the values of Delta E, YI and MI of the polyoxymethylene resin compositions of the comparative examples were large, indicating that the thermal stability was lower than that of the examples.

Claims (6)

With respect to 100 parts by weight of the polyoxymethylene resin,
0.001 to 5 parts by weight of a hindered phenolic antioxidant;
0.001 to 5 parts by weight of a mixed salt wherein the mixing ratio of the fatty acid calcium salt and the fatty acid zinc salt is 5 to 95% by weight: 95 to 5% by weight; And
0.01 to 2 parts by weight of a porous organic-inorganic hybrid silica gel represented by the general formula (2).
(2)

Here, R has the structure represented by the general formula (3).
(3)
Al ₂ Si ₂ O ₅ (OH) _X .My
Here, M is a metal selected from P, Ca, Zn, Fe, K, Mn, Mo, Ag, Mg and Ti. X is an integer of 1 to 5 and y is an integer of 2 to 7.
The method according to claim 1,
Wherein the hindered phenol-based antioxidant has a molecular weight of 400 or less.
delete The method according to claim 1,
Wherein the porous organic-inorganic hybrid silica gel is a porous organic-inorganic hybrid silica gel for adsorbing volatile organic compounds (VOCs) having a pore size of 50 nm or less and a surface area of 200 to 2000 m ² / g.
The method according to claim 1,
And having a Delta E of 1.5 or less at a temperature of 180 to 240 DEG C for 30 minutes.
A molded article comprising the polyoxymethylene resin composition according to any one of claims 1 to 4,