JPS58225111A - Preparation of ethylene/vinyl ester polymer - Google Patents

Abstract

PURPOSE:To prepare the titled copolymer having excellent oil resistance and transparency as well as cold resistance, and suitable as a base of a vinyl chloride graft copolymer, by the radical copolymerization of ethylene with a vinyl ester in the presence of a thermoplastic polyurethane. CONSTITUTION:The objective copolymer is prepared by copolymerizing ethylene with a vinyl ester (e.g. vinyl acetate) at a weight ratio of preferably 20/80-50/ 50, in the presence of preferably 10-60wt% of a thermoplastic polyurethane (preferably having a number-average molecular weight of >=500), and e.g. 0.05- 10wt% of a nonionic emulsifier such as polyoxyethylene alkyl ether, usually at 0-100 deg.C. EFFECT:Suppressed fish-eye formation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing ethylene/vinyl ester polymers which are particularly suitable for graft copolymerizing vinyl monomers such as vinyl chloride, and more particularly to a method for producing ethylene/vinyl ester polymers containing thermoplastic polyurethanes. , relates to a method for producing an ethylene/vinyl ester polymer having excellent low temperature properties and oil resistance.

Ethylene/vinyl ester copolymer (abbreviated as EV) is a useful resin in itself, and Ev/vinyl chloride graft copolymer (abbreviated as EV) obtained by graft copolymerizing EV with a vinyl monomer such as vinyl chloride 1! Abbreviated as VG)
It is also known as a useful resin. As described in Japanese Patent Publication No. 39-27876, EvG has excellent properties such as non-migration and low-temperature flexibility, and is therefore used in various applications including electric wire coating materials.

However, this I! Properties such as low temperature resistance and oil resistance of VG are I! v content and [! It is influenced by the ethylene content in v, and within the ethylene content range of 20 to 80% by weight where EV exhibits rubber elasticity, the higher the content of each of the above, the better the low temperature properties of EVG. On the other hand, conventional EVs have a so-called trade-off phenomenon in that the higher the ethylene content in EV, the lower the oil resistance and transparency.

In order to overcome this antinomy, the present inventors used polyurethane that is highly compatible with EV and polyvinyl chloride, and polymerized vinyl chloride in the presence of a mixture of polyurethane and EV, thereby improving low temperature resistance, oil resistance, and It was discovered that a vinyl chloride resin with excellent transparency can be obtained, but with this method, when it is desired to increase the content of polyurethane, its solubility is insufficient, and a portion of the polyurethane remains undissolved.
It has the disadvantage that it remains encapsulated in EvG and becomes coarse particles, causing fish eyes in molded products.

Therefore, the present inventors have developed a method suitable for producing a vinyl chloride-based graftomer that is not only low-temperature resistant, but also has excellent oil resistance and transparency, and does not cause fish eyes and is particularly economically advantageous. As a result of extensive research into rubber-like polymers as the core component, we have completed the present invention.

That is, the present invention provides a method for producing an edisin/vinyl ester copolymer by radical copolymerization of ethylene and vinyl ester in the presence of a thermoplastic polyurethane.

When producing a vinyl chloride graft copolymer using the polyurethane-containing ethylene/vinyl ester polymer obtained according to the present invention, if the polymer is an aqueous dispersion, a step of dissolving it in vinyl chloride is not particularly necessary. A vinyl chloride-based Graph 1 copolymer can be obtained which is easily and uniformly dissolved in vinyl chloride without any blemishes, has few fish eyes, and has excellent transparency. Further, the polyurethane-containing ethylene/vinyl ester polymer obtained by the method of the present invention is useful not only as a raw material for various grafts but also as a rubber product alone.

The polyurethane used as the backbone polymer in the present invention is a long chain glycol having a number average molecular weight of 300 or more, preferably 500 or more, having 011 groups at both ends, and V-Nc at both ends.

It is obtained by reaction with a polyisocyanate compound having a group. Among these, typical long-chain glycols include polyether glycols obtained by polymerizing alkylene oxides such as propylene oxide or tetrahydrofuran, and glycols such as adipic acid and ethylene glycol or propylene glycol. These include polyester glycols obtained by condensation with lactones, and polyester glycols obtained by open polymerization of lactones. Typical examples of the polyisocyanate compound include toluene diisocyanate, Schifte methane diisocyanate, hexamethylene diisocyanate, and naphthylene diisocyanate. Aliphatic diisocyanates such as hexamethylene diisocyanate are particularly preferred from the viewpoint of plasticizing effect on the vinyl chloride-based graft coelectrolyte and heat coloring resistance.

The amount of the polyurethane used is 10 to 60 96% by weight in the copolymer. If this amount is small, the effects of improving low temperature properties and oil resistance will not be sufficient, and in winter, the polyurethane will be difficult to dissolve uniformly in the vinyl web, and the copolymer will become large particles. Production of a vinyl chloride graft copolymer (1) is also not recommended as troubles tend to occur.

As the ethylene and vinyl ester in the present invention, vinyl esters of ethylene and alkyl or aryl carboxylic acids are used. As this vinyl ester, representative CI
These include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl persadecate, and vinyl benzoate. It is also possible to use other monomers in combination. Typical examples of such other vinyl monomers include (meth)acrylonitrile, (meth)acrylic acid, or esterified products thereof.

The ratio when copolymerizing the ethylene and vinyl ester is 20/80 to 50,150 by weight. If the amount of ethylene is small, low temperature properties will be insufficient, and if the amount is too large, oil resistance will be poor.

In addition, when copolymerizing ethylene and vinyl ester, any of bulk, solution, suspension, and emulsion polymerization is possible, but emulsion polymerization, in which the polymer has a high molecular weight and is obtained in a state of fine particle dispersion, is preferable. .

The ethylene/vinyl ester polymer emulsion has a high polymer molecular weight and can be partially crosslinked, so it is also excellent as a coating agent for various materials. For example, since it is an emulsion, it can be used for materials such as benvelub, which is particularly poor in solvent resistance and for which solution-type coating agents cannot be used.

Dispersants used in emulsion polymerization include anionic emulsifiers, nonionic emulsifiers, and protective colloids, with nonionic emulsifiers and protective colloids being particularly preferred.

Nonionic emulsifiers include polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether,
Examples include polyethylene glycol and polyoxyethylene alkylamide. Also, 0ilW1. Colloids include polyvinyl alcohol and methyl cellulose. The above emulsifiers and 5-protective colloids can be used alone or in combination.

The amount of dispersant used is 0.05 to 1 % based on the copolymer.
0...% is preferable.

In the present invention, 1. As the radical initiator, oil-soluble, water-soluble, or redox radical initiators can be used. Preferably, a water-soluble radical initiator or a Redo-7 radical initiator is used.

In the present invention, the polymerization temperature is not particularly limited, but () to
Usually carried out at 100°C.

In addition, in the present invention, the polyurethane after combining ethylene and vinyl ester may be partially grafted with ethylene and/or vinyl ester, and if necessary, double bonds may be introduced into the polyurethane in advance, or It is also possible to increase the grafting rate by adding a radical prior to initiation of polymerization.

The polyurethane-containing ethylene/vinyl ester 7i polymer obtained by the method of the present invention is particularly suitable as a base material for vinyl chloride graph 1 copolymer, and the vinyl chloride-based graft copolymer obtained using such a polymer. The polymer has excellent low-temperature resistance and oil resistance, and particularly has fewer fish eyes and improved transparency. Furthermore, the polyurethane/ethylene/vinyl ester copolymer itself can be crosslinked as a rubber polymer with excellent oil resistance and low temperature properties, and can be suitably used as a rubber product or as a modifier for plastics.

In addition, the polyurethane-containing ethylene/vinyl ester composite obtained in the present invention is used to graft vinyl chloride monomer or other vinyl monomer copolymerizable with this monomer. Used when obtaining vinyl chloride graft copolymers.

Typical examples of Qtl 1 bodies for graft polymerization include vinyl chloride, and ethylene, vinyl acetate, vinylidene chloride, (meth)acrylic acid ester, or (meth)acrylonitrile that can be copolymerized with vinyl chloride.
The amount of the monomer capable of bending copolymerization is 50% by weight or less, preferably 1% by weight in the obtained vinyl chloride graft copolymer.
It is 5% by weight or less.

In this case, the polymerization method may be in bulk, solution, emulsion or suspension, but suspension polymerization is particularly advantageous.

Next, the present invention will be specifically explained with reference to Examples and Comparative Examples, in which all parts and percentages are based on weight.

Example 1 Materials 1 to 7 in Table 1 were charged into a stainless steel autoclave with an internal volume of 2P and equipped with a stirring device. Next, the temperature was raised to 50°C and stirred for 1 hour to sufficiently dissolve the polyurethane.
0t' Table 1 Notes *1) Polyurethane obtained by polymerizing 1,4-butanediol/adipic acid polyester polyol with a number average molecular weight of 91,200 and hexamethylene diisocyanate at an equivalent ratio of 1:1.

−/″− /′ (9) Add hydrogen and heat the inside of the autoclave for 3
While maintaining the temperature at 0°C, (10) 5% potassium persulfate aqueous solution was added.
It dripped over time. After maintaining it for an additional 30 minutes, unreacted ethylene was released to stop the polymerization. The resulting aqueous dispersion had a solid content of 49%, and compositional analysis of the polymer revealed that it contained 22% polyurethane and 33% ethylene. %, vinyl acetate 45%.

Next, in an autoclave with an internal volume of 2p equipped with a stirring device,]
408 parts of the above-mentioned polyurethane/ethylene/vinyl acetate copolymer water dispersion bay, 642 parts of distilled water, 200 parts of vinyl chloride, 1 part of α,α'-azodiisobutyronitrile, 2 parts of partially saponified polyvinyl acetate I gave it to you. then 60'
Polymerization was carried out at C for 8 hours.

When the product was dried, 375 parts of a white powdery vinyl chloride graft coelectrolyte was obtained. The vinyl chloride content of the polymer was 50%.

Table 2 shows the analytical values of the polyurethane-containing ethylene/vinyl acetate copolymer and the evaluation results of its vinyl chloride graft copolymer.

The obtained vinyl chloride graft copolymer has fewer coarse particles, fewer fish eyes when molded, and has improved transparency compared to conventional copolymers.

Comparative Example 1 Except for (1) polyurethane in Table 1 in Example 1, 9
- (2) Polymerization was carried out in the same manner except that the amount of distilled water was changed from 400 parts to 300 parts, and the obtained aqueous dispersion of ethylene/vinyl acetate copolymer was salted out and dried to form a solid rubber. A polymer was obtained. Analysis of the polymer composition revealed that it was 41% ethylene and 59% vinyl acetate.

Next, 156 parts of the solid ethylene/vinyl acetate copolymer described above, 44 parts of the pellet-shaped polyurethane used in Example I, and 85 parts of distilled water were placed in an autoclave with an internal volume of 21 and equipped with a stirring device.
0 parts, 200 parts of vinyl chloride, 1 part of α,α'-azodiisobutyronitrile, and 2 parts of partially saponified polyvinyl acetate were charged and stirred vigorously at room temperature for 3 hours to dissolve the polymer mixture in vinyl chloride. .

Next, electric coupling was performed at 60° C. for 8 hours. When the product was dried, 377 parts of a white powdery vinyl chloride graft copolymer was obtained. The vinyl chloride content of the polymer was 49%.

The obtained vinyl chloride gelast copolymer was subjected to the same test as in Example 1. The results are shown in Table 2.

LL+- Note to Table 2 *1 Vinyl chloride graft polymer of dry # layer is J
It was separated using ISlllfpHll 32 mesh and the amount of unfiltered material was measured, and its weight % is not shown.

*2 100 parts of vinyl chloride graft polymer, 1 part of ocdyltin mercapto, 0.2 parts of stearin #zinc, and stearic acid calcium chloride. 2 parts were added and kneaded with a roll for 5 minutes at 160°C to obtain a roll sheet of 0.5 yen. From this, 10CIIXIO■ was cut out and left in a hot air dryer at 170°C for 30 minutes, and the number of red and black spots was determined as the number of fisheyes. A value of 2 or less per 10xlO- was considered to be a pass.

*3 The rolled sheet obtained in Step 2 was press-molded at 170° C. for 5 minutes to obtain a 1-long sheet, and its total light transmittance and sound were measured.

Example 2 The same reaction as in Example 1 was carried out except that the amount of polyurethane was changed to 140 parts in Table 1 of Example 1, and 75 parts of methanol was added. An aqueous polyurethane/ethylene/vinyl acetate copolymer dispersion having a polymer composition of 29% polyurethane, 30% ethylene, and 41% vinyl acetate was obtained. When a vinyl chloride graft copolymer was synthesized in the same manner as in Example 1, 373 parts of a polymer having a vinyl chloride content of 51% was obtained. The amount of this vinyl chloride graft copolymer that did not pass through 32 meshes was 1%, and when the molded product was evaluated, it was found that
Example 3 In Table 1 of Example I, vinyl acetate was replaced with vinyl propionate, and ethylene was used at 52 ktr/cJ (3
The reaction was carried out in the same manner as in Example 1, except that 0"t:) was changed to 44 kg/cja (30°C).Polyurethane-containing ethylene/vinyl acetate whose polymer composition was 25% polyurethane, 25% ethylene, and 50% vinyl acetate. An aqueous copolymer dispersion was obtained. Using this aqueous copolymer dispersion, a vinyl chloride graft copolymer was prepared in the same manner as in Example I. 4. sea urchin, 5. i °'', and the transparency was excellent.

12-Example 4 Same as Example 1 except that in Table 1 of Example 1, polyoxyethylene nonylphenyl ether (degree of polymerization 10.5 >) was used in the same amount instead of (5) polyoxyethylene polyoxypropylene ether. Similarly, the polymer composition is polyurethane 239A, ethylene 31%, vinyl acetate 46%.
An aqueous dispersion of polyurethane-containing ethylene/vinyl acetate copolymer was obtained. A vinyl chloride graft copolymer was synthesized using this aqueous dispersion in the same manner as in Example 1, and the resulting molded product was evaluated and found to have few fish eyes and excellent transparency.

Patent expert: Dainippon Ink & Co., Ltd. 13-

Claims (1)

[Claims] A method for producing an ethylene/vinyl ester polymer, which comprises radical copolymerization of ethylene and vinyl ester in the presence of a thermoplastic polyurethane.