JPH0672165B2 - Low molecular weight ethylene random copolymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention is applied to a pigment dispersant for polyamide, polyester resin, etc. containing ethylene, (meth) acrylic acid, maleic anhydride as an essential constituent unit, and other uses. The present invention relates to a useful low molecular weight ethylene copolymer.

The (meth) acrylic acid ester means an acrylic acid ester, a methacrylic acid ester or a mixture thereof, and the (meth) acrylic acid means an acrylic acid, a methacrylic acid or a mixture thereof.

<Prior Art> Low molecular weight ethylene-based copolymers having ethylene and acrylic acid as constitutional units have been known (for example, Japanese Patent Publication No.
53-65389, JP-B 53-57295, JP-B 60-79007
No. 60-79008). This low molecular weight ethylene-based copolymer is used in the form of ammonium salt or amine salt as a dispersion for adhesives for paper, or as the copolymer itself is used as a pigment dispersant for resins. ，
It was found that the compatibility with polar resins such as polyamide and polyester resins was insufficient and the physical properties were deteriorated. Change the ratio of acrylic acid units in the copolymer,
Also, the molecular weight of the copolymer was changed, but the effect was not always sufficient.

<Problems to be Solved by the Invention> An object of the present invention is to solve the above problems and to provide a low molecular weight ethylene copolymer having excellent compatibility with polyamide, polyester resins and the like.

<Means for Solving Problems> As a result of various studies, the number average molecular weight obtained by thermally degrading an ethylene- (meth) acrylic acid ester-maleic anhydride copolymer having a number average molecular weight of 17,000 to 33,000 was found to be high. 1000
It has been found that a low molecular weight ethylene copolymer containing (meth) acrylic acid units and maleic anhydride units as essential components in the molecule at ~ 10000 solves this problem.

The reason why the compatibility with nylon and polyester resins is improved by the introduction of maleic anhydride units is not always clear, but it is considered that the maleic anhydride group is particularly familiar to polar groups in these resins. . The (meth) acrylic acid unit in the low molecular weight copolymer is 0.3 to 1
0%, maleic anhydride unit is preferably 0.2 to 5 mol%. If the content of the (meth) acrylic acid unit deviates from the above range, the compatibility with the resin decreases.

When the maleic anhydride content is 0.2 mol% or less, the compatibility improving effect is not observed, and when it is 5 mol% or more, the toughness decreases.
The number average molecular weight of the low molecular weight ethylene copolymer is 100 to 10
It is preferably 000. If it is 1000 or more, the compatibility with the resin is poor and it causes a poor surface condition due to bleeding out, and if it is 10,000 or more, the workability is poor due to the high viscosity.
The low molecular weight ethylene copolymer can also be produced by polymerizing the monomers of the respective constitutional units, but the molecular weight of 1000 to
A large amount of chain transfer agent is required to control to 10,000, which is not preferable. On the other hand, the number average molecular weight is 1700
The method of thermally degrading ethylene, (meth) acrylic acid ester and maleic anhydride copolymer of 0 to 33000 is to simultaneously reduce the molecular weight by breaking the main chain and the field of ester to acid. There is a feature that coalescing can be easily manufactured.

When the number average molecular weight of the copolymer used as a raw material is 33,000 or more, a large amount of energy is required for thermal degradation, which is not preferable, and when it is 17,000 or less, workability such as fusion of pellets of the copolymer is deteriorated and actually Not at all.

The number average molecular weight of the ethylene- (meth) acrylic acid ester-maleic anhydride copolymer used as a raw material is [[Polymer measurement method, structure and physical properties (above)], edited by The Society of Polymer Science, Baifukan, Showa Issued 48 years], pages 76 to 89, and is obtained by gel permeation chromatography (GPC). For example, using ortho-dichlorobenzene as a solvent, and using a calibration curve of the average molecular chain length and GPC count number prepared using monodisperse polystin, based on the values measured under the conditions of a column oven temperature of 145 ° C, the number average is used. Converted as molecular weight.

On the other hand, the number average molecular weight of the low molecular weight ethylene copolymer according to the present invention is described on pages 57 to 75 of [Polymer Measurement Method, Structure and Physical Properties (1), The Polymer Society of Japan, Baifukan, 1973]. Vapor pressure osmotic pressure method (VPO) with reference to the described method
Is required by. For example, it can be obtained by measuring at 60 ° C using a benzene solvent as a 1.0 wt% solution.

0.3% of (meth) acrylic acid unit and maleic anhydride unit
The low molecular weight ethylene copolymers containing 10 to 10% and 0.2 to 5 mol% are raw material copolymers containing 0.3 to 12 mol% and 0.2 to 5 mol% of (meth) acrylic acid ester unit and maleic anhydride unit, respectively. It is obtained by degradation using coalescence. Depending on the conditions, a part of the carboxylic acid may be decomposed, and therefore it may be preferable to use a raw material polymer having a higher content of the (meth) acrylic acid ester unit.

Examples of the alcohol component of the (meth) acrylic acid ester unit include straight chain / branched aliphatic alcohols having C ₂ or more, such as ethyl alcohol, isopropyl alcohol, and n-butyl alcohol. Although longer chain alcohols can be used, it is not practical to use long chain alcohols because the ester decomposes to an acid in the low molecular weight step due to thermal degradation. Further, the methyl ester is not easily converted into an acid by degrading, which is not preferable as a raw material of the present invention. The alcohol component does not have to be a single product, and may be a mixture thereof. This ethylene, (meth) acrylic acid ester, maleic anhydride copolymer can be produced, for example, by the method described in French Patent No. 1323379 (corresponding US Pat. No. 3201374). If used, polymers obtained by other methods can also be used.

The thermal degradation in the present invention means to appropriately reduce the molecular weight by heat treatment.

Thermal degradation is performed at 300 to 500 ° C, more preferably 350 to 450 ° C. The temperature and time of thermal degradation are not constant depending on the raw materials used and the physical properties of the desired low molecular weight copolymer. Since the presence of oxygen causes coloring and gelation during thermal degradation, it is preferably performed in an atmosphere of an inert gas. Undecomposed ester may remain depending on the condition of thermal degradation. As long as the low molecular weight ethylene copolymer satisfies the stated conditions in the claims, the residual ester content is not particularly limited, but usually the total amount of (meth) acrylic acid and (meth) acrylic acid ester is It is preferable that 50 mol% or more of the medium is (meth) acrylic acid.

The content of monomers in the copolymer is measured by infrared absorption spectrum.

The low molecular weight ethylene copolymer obtained is a pigment dispersant such as polyamide or polyester resin, a processability improving agent, and
It is useful as an adhesive for paper as an ammonium salt or amine salt and as an aqueous dispersion. The effects when used as a pigment dispersant for polyamide resin are shown below.

<Examples> The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example-1 An ethylene-acrylic acid ethyl ester-maleic anhydride copolymer (number average molecular weight of 31 was added to a 34-neck Kolben equipped with a nitrogen inlet pipe, a thermometer, an exhaust gas distillation pipe, and a stirring rod.
300 kg, ethyl acrylate unit content 1.0 mol%, maleic anhydride unit content 0.5 mol%) 1.5 kg is charged under nitrogen atmosphere. After that, nitrogen continues to be aerated in the Kolben until the heat reduction is completed. Next, the temperature was raised by heating with a malt heater and heat degradation was carried out at 360 ° C for 2 hours while stirring. Then, after cooling to 200 ° C, the thermal degradation product was taken out. The number average molecular weight of the obtained heat-degraded low molecular weight ethylene copolymer was 40.
00, the content of ethylene units is 98.5 mol%, the content of acrylic acid ethyl ester units is 0.5 mol% (45 mol% in the total amount of ethyl acrylate and acrylic acid), the content of acrylic acid units is 0.6 mol% % (55 mol% in the total amount of ethyl acrylate and acrylic acid), and the content of maleic anhydride unit was 0.4 mol%.

Example-2 Ethylene-acrylic acid ethyl ester-maleic anhydride copolymer (number average molecular weight 22800, content of acrylic acid ethyl ester unit 10 mol%, content of maleic anhydride unit
0.7 mol%) and in the same manner as in Example-1 at 395 ° C.
The number average molecular weight was 8000, the ethylene unit content was 89.3 mol%, and the acrylic acid ethyl ester unit content was 3.2 mol% (of the total amount of acrylic acid ethyl ester and acrylic acid 31%). Mol%), the content of acrylic acid units is 7.0 mol% (69 mol% in the total amount of acrylic acid ethyl ester and acrylic acid), and the content of maleic anhydride units is 0.5 mol% of a low molecular weight ethylene copolymer. Obtained.

Comparative Example-1 Ethylene-acrylic acid ethyl ester copolymer (number average molecular weight 32100, acrylic acid ethyl ester unit content 4.7
Mol%) copolymer and the same operation as in Example-1.
After thermal degradation at 360 ℃ for 2 hours, a low molecular weight ethylene copolymer with a number average molecular weight of 5000 and an acrylic acid unit content of 3.0 mol% was obtained.

Comparative Example-2 Ethylene-acrylic acid ethyl ester copolymer (number average molecular weight 32700, acrylic acid ethyl ester unit content 8.6
Mol%) copolymer and the same operation as in Example-1.
After thermal degradation at 390 ℃ for 30 minutes, a low molecular weight ethylene copolymer with a number average molecular weight of 8500 and an acrylic acid unit content of 6.5 mol% was obtained.

Comparative Example-3 Using polyethylene having a number average molecular weight of 30800 and a density of 0.919,
Thermal degradation was performed at 354 ° C. for 2 hours in the same manner as in Example-1,
A low molecular weight ethylene copolymer having a number average molecular weight of 5000 was obtained.

Various low molecular weight ethylene copolymers (50 parts by weight) obtained by the thermal degradation method described in the above Examples and Comparative Examples and a copper phthalocyanine blue pigment (50 parts by weight) were used at the surface temperature.
The mixture was kneaded for 10 minutes using three rolls adjusted to 120 ° C, cooled and pulverized to obtain a master powder of 10 to 20 mesh.

Polyamide 6 (Toray Industries, Ltd., Amilan CM1001) 100
1 part by weight of the master powder was mixed with 1 part by weight, and various test pieces for measuring physical properties were prepared using a 10 ounce injection molding machine at a resin temperature of 245 ° C. and a mold temperature of 70 ° C. The injection moldability, the surface condition of the molded product, the retention of Izod impact strength and elongation at break (value in comparison with the molded product of the base polyamide) were evaluated, and the results shown in Table 1 were obtained.

<Effects of the Invention> As described above, according to the present invention, it is possible to provide a low-molecular-weight ethylene-based copolymer having excellent compatibility especially with polyamide, polyester resins and the like.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kentaro Mashita 5-1 Anezaki Kaigan, Ichihara City, Chiba Prefecture Sumitomo Chemical Co., Ltd. (72) Inventor Tetsuo Morino 67, Kita-ku, Kitano-ku, Kyoto Prefecture (72) ) Inventor Hiroshi Nishimoto 36, 12-12, Seifu-cho, Otsu City, Shiga Prefecture (56) Reference JP-A-53-57295 (JP, A) JP-A-60-79007 (JP, A) JP-A-60-79008 (JP) , A) Japanese Patent Laid-Open No. 53-65389 (JP, A) Japanese Patent Publication No. 50-33839 (JP, B2) US Patent 3201374 (US, A)

Claims (2)

[Claims] 1. Ethylene having a number average molecular weight of 17,000 to 33,000
(Meth) acrylic acid ester-maleic anhydride random copolymer obtained by thermal degradation and having a number average molecular weight of 10,000 to 10,000 ethylene unit- (meth) acrylic acid ester unit- (meth) acrylic acid unit-anhydrous A low molecular weight ethylene random copolymer comprising maleic acid units, wherein the content of (meth) acrylic acid ester units is less than 50 mol% in the total amount of (meth) acrylic acid ester units and (meth) acrylic acid units, A low molecular weight ethylene random copolymer having a content of (meth) acrylic acid units of 0.3 to 10 mol% and a content of maleic anhydride units of 0.2 to 5 mol%. 2. Ethylene- (meth) acrylic acid ester-
The content of the (meth) acrylic acid ester unit in the maleic anhydride random copolymer is 0.3 to 12 mol%, and the content of the maleic anhydride unit is 0.2 to 5 mol%. Low molecular weight ethylene random copolymer.