JPH0784546B2 - Resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a resin composition suitable for molding, which comprises a saponified ethylene-vinyl acetate copolymer, a specific polyamide resin, and a fatty acid ester.

[Conventional technology]

In recent years, a film that shrinks with hot water or hot air has been used for food packaging.
It is stated that the material has mechanical strength capable of retaining the shape of the contents, a barrier property for preventing rancidity and drying, as well as good dimensional stability at room temperature and high shrinkability at high temperature.

As a composition for such use, a composition comprising a saponified ethylene-vinyl acetate copolymer, a polyamide resin and an α-olefin ionomer resin is known (JP-A-60-133050). The composition has a drawback that the heat stability against melting is not sufficient, a gel is often formed, and as a result, there are many fish eyes in the film and the like, and the transparency is deteriorated.

[Object of the Invention]

The present inventors have conducted extensive studies to solve such problems, and as a result, (I) saponified ethylene-vinyl acetate copolymer,
(II) Terminal carboxyl group content (Xμeq / g / polymer)
A composition comprising a polyamide resin and (III) a fatty acid ester, which have a relationship of satisfying the formula Y ≧ X + 5, and a terminal amino group content (Yμeq / g · polymer), have excellent melt heat stability and long life. The present invention has been completed by finding that there is no inconvenience such as formation of a gel-like substance over a period of time, a product with less fish eyes can be stably produced, and transparency is not impaired.

[Structure of Invention]

The saponified product of (I) ethylene-vinyl acetate copolymer used in the present invention has an ethylene content of 20 to 80 mol%, preferably
Those having a degree of saponification of 25 to 60 mol% and a vinyl acetate component of 90 mol% or more, preferably 95 mol% or more are usually used.
When the ethylene content is 20 mol% or less, the oxygen barrier property at high humidity is deteriorated, while when the ethylene content is 80 mol% or more, physical properties such as oxygen barrier property and printability are deteriorated. Further, if the silicidation degree is 90 mol% or less, the oxygen barrier property and the moisture resistance decrease. Among these saponified products, those having an intrinsic viscosity (measured as a 15% hydrous phenol solution at 30 ° C.) of 0.7 to 1.5 dl / g, preferably 0.8 to 1.3 dl / g are preferably used in terms of mechanical strength of the molded product. To be done.

Further, the saponified copolymer is a small amount of propylene, isobutene, α-octene, α-dodecene, α-olefin such as α-octadecene, unsaturated carboxylic acid or its salt / partial alkyl ester, complete alkyl ester / nitrile / It does not matter if it contains a comonomer such as amide, anhydride, unsaturated sulfonic acid or a salt thereof.

The polyamide resin used in the present invention must have terminal carboxyl groups and amino groups satisfying the above formula.

That is, in a polyamide obtained by polymerizing or copolymerizing a lactam having 3 or more membered rings, ε-amino acid or dibasic acid with diamine, the content of terminal amino group in the molecule is adjusted to be larger than the content of terminal carboxyl group. It is what is done.

To produce the polyamide-based resin of the present invention, polycondensation is carried out in the coexistence of a diamine when a lactam having three or more membered rings or ω-amino acid is used, and a diamine is prepared when polycondensation is carried out with a dibasic acid and a diamine. By using an excess amount of

Specific examples of the raw material for the above polyamide include ε-caprolactam, enantolactam, capryllactam, lauryllactam, α-pyrrolidone, lactams such as α-piveridone, 6-aminocaproic acid, 7-aminoheptanoic acid, 9 -Ω-amino acids such as aminononanoic acid and 11-aminoundecanoic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azeaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecadione Acid, tetradecadioic acid, hexadecadioic acid, hexadecenedioic acid, octadecadioic acid, octadecenedioic acid, eicosandioic acid,
Aliphatic dicarboxylic acids such as eicosendioic acid, docosandionic acid, 2,2,4-trimethyladipic acid, 1,4-
Alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, dibasic acids such as terephthalic acid, isophthalic acid, phthalic acid, and aromatic dicarboxylic acids such as xylylenedicarboxylic acid may be mentioned. The diamines include ethylenediamine and trimethylene. Diamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, tridecamethylenediamine, hexadecamethylenediamine, octa Decamethylenediamine, 2,2,4 (or 2,4,
4) -aliphatic diamines such as trimethylhexamethylenediamine, cyclohexanediamine, methylcyclohexanediamine, alicyclic diamines such as bis- (4,4'-aminocyclohexyl) methane, aromatic diamines such as xylylenediamine And so on.

The amount of the diamine used is 0.6 to 20 meq / mol, preferably 0.8 to 18 me, based on the polyamide raw material as the amount of amino groups.
q / mol. When a dibasic acid is used, it is preferable that the excess amount of diamine with respect to the acid be the above-mentioned amount.

The reaction for producing the polyamide resin of the present invention is carried out by using the above-mentioned polyamide raw material under reduced pressure according to a conventional method for 0.5 hours or more and usually 1-2 hours.

The polyamide resin used in the present invention has a carboxyl group and an amino group as terminal groups, but in the present invention, the content of the carboxyl group (X μeq / g · polymer) and the content of the amino group (Yμed / g / polymer)
It is necessary that the relation Y ≧ X + 5, and preferably Y ≧ X + 10, be satisfied. And preferably, the absolute value of the carboxyl group content (X) is 50 μeq / g.
It is suitable that the polymer content is not more than 30 μeq / g · polymer, more preferably not more than 20 μeq / g · polymer.

If a polyamide resin having many terminal carboxyl groups is used, the melt viscosity increases during melt molding, which is not preferable for molding. On the other hand, having a small number of carboxyl groups is preferable from the viewpoint of application, but it is difficult to produce a resin, so it is a good idea to limit the amount to at least 1 μeq / g · polymer.

The carboxyl group is measured by dissolving a polyamide resin in benzyl alcohol and titrating with 0.1N caustic soda.

Amino group dissolves polyamide resin in phenol,
Measure with 0.5N hydrochloric acid.

The relative viscosity (ηrel) of the polyamide resin of the present invention is JIS
According to K6810, the value measured in a 98% sulfuric acid concentration of 1% and a concentration of 25 ° C. is 2 to 6, preferably 2 to 5. If the relative viscosity is too low, it becomes difficult to form strands and form chips, which is inconvenient in manufacturing. On the other hand, if it is too high, the moldability will deteriorate.

The mixing ratio of the saponified ethylene-vinyl acetate copolymer (I) and the polyamide resin (II) is not particularly limited, but usually (I) / (II) = 98/2 to 2/98 on a weight basis. Preferably
95 / 5-10 / 90 is suitable. When it is 98/2 or more, the effect of improving the physical properties such as impact strength improvement of the saponified ethylene-vinyl acetate copolymer is not recognized, while when it is 2/98 or less, the effect of improving the oxygen barrier property of the polyamide resin is not obtained.

Fatty acid ester is an ester composed of higher fatty acid having 10 or more carbon atoms and alcohol. Examples of such higher fatty acids include saturated or unsaturated carboxylic acids such as lauric acid, myristic acid, palmitic acid, stearic acid, montanic acid, oleic acid, linoleic acid and ricinoleic acid. A substituent such as a hydroxyl group may be present in the carbon skeleton of the carboxylic acid, and the carbon number is preferably 10 to 35. On the other hand, examples of the alcohol which forms an ester include monohydric or polyhydric alcohols, and examples thereof include methanol, ethanol, propanol, butanol, hexanol, 2-ethylhexanol, octanol, decyl alcohol, dodecyl alcohol, cetyl alcohol and octadecyl. Alcohol, ethylene glycol, polyethylene glycol, propylene glycol, butylene glycol, glycerin,
Examples include trimethylolpropane and pentaerythritol. These alcohols preferably have 1 to 20 carbon atoms.

Specific examples of the higher fatty acid ester include propyl laurate, butyl laurate, glycerin monolaurate,
Trimethylolpropane trilaurate, polyethylene glycol ester of lauric acid, propyl palmitate, butyl palmitate, cetyl palmitate, myricyl palmitate, glycerin monopalmitate, propyl stearate, butyl stearate, glycerin monostearate, glycerin Distearate, glycerin tristearate, trimethylolpropane mostearate, trimethylolpropane distearate, pentaerythritol monostearate, triglyceride of 12-hydroxystearic acid, glycerin monooleate,
Examples thereof include glycerin diolate, polyethylene glycol ester of montanic acid, and a mixture thereof.

Among these fatty acid esters, those having at least one free hydroxyl group such as glycerin monostearate are preferable.

The mixing ratio of the fatty acid ester (III) and the total amount of the saponified ethylene-vinyl acetate copolymer (I) and the polyamide resin (II) is usually (III) / (I) + (I on a weight basis.
I) 0.05 / 100 to 5/100, preferably 0.08 / 100 to 3/100. If the amount of fatty acid ester is too small, the gelation preventing effect will decrease. On the contrary, if the amount is too large, the barrier property and the biteability into the molding machine are impaired.

The composition of the present invention is a melt-formed pellet, film,
It is molded into various molded products such as sheets, containers, and bars. As the melt molding method, known molding means such as extrusion molding, blow molding, and injection molding are adopted.

Melt molding temperature in the range of 150 to 270 ° C, more specifically in the extruder discharge temperature 200 to 240 ° C, screw compression temperature 180 to 230
You can choose from ℃.

Various additives such as stabilizers, fillers, pigments, dyes, lubricants, antiblocking agents, and various thermoplastic resins may be added to the resin composition of the present invention.

〔Example〕

Next, the composition of the present invention will be described more specifically with reference to examples.

<Production Example of Polyamide Resin> Seven kinds of polyamide resins were produced by the following method.

Autoclave to 200, 60 kg of ε-caprolactam,
Charge 1.2 kg of water and diamine in the amount shown in Table 1 below, or diamine and dicarboxylic acid, and seal under a nitrogen atmosphere.
After the temperature was raised to 0 ° C. and the reaction was performed under pressure for 2 hours with stirring,
The pressure was gradually released, and the pressure was reduced to the pressure shown in Table 1 below, and the reaction was performed under reduced pressure for 2 hours.

After introducing nitrogen and restoring the pressure to normal pressure, stirring was stopped and the strands were extracted to form chips, and unreacted monomers were extracted and removed using boiling water and dried.

Table 1 shows the relative viscosity, the amount of terminal carboxyl groups, and the amount of terminal amino groups of the obtained polyamide resin.

Examples 1 to 7 and Comparative Examples 1 to 6 Polyamide-based resins produced in the above production examples, saponified ethylene-vinyl acetate polymers having an ethylene content of 38 mol% and a vinyl acetate component saponification degree of 99 mol%. (Nippon Rigid Chemical Co., Ltd., trade name: Soarnol ET), and the gelation preventing additives shown in Table 2 were dry blended at the ratio shown in Table 2 below, and a 40 mmφ extruder with a T die (Ikegu) Iron Works Co., Ltd.
Manufactured by eS-40 type) to produce a film having a thickness of 50 μ at an extrusion temperature of 240 ° C. and a screw rotation speed of 50 rpm.

The film was sampled 8 hours after the start of drug production, and the melt heat stability was evaluated by counting the fish eyes of 80 μ or more using a laser eye (manufactured by Yasukawa Electric Co., Ltd.).

In addition, haze indicating transparency was measured according to JIS K-6714. The results are shown in Table 2 below.

[Effects of the Invention] The composition of the present invention has good melt heat stability, excellent transparency, and is capable of producing a film free from disadvantages such as fish eyes.

Continuation of the front page (56) Reference JP 62-106944 (JP, A) JP 63-175051 (JP, A) JP 61-157554 (JP, A) JP 62-22840 (JP , A)

Claims (3)

[Claims] 1. A saponified product of (I) an ethylene-vinyl acetate copolymer, (II) a content of a terminal carboxyl group (X) and a terminal amino group (Y) (μeq / g · polymer) is represented by the formula Y ≧ X + 5. A resin composition comprising a polyamide resin satisfying the requirements and (III) a fatty acid ester. 2. The polymerization compounding ratio of (I) and (II) is (I) /
The resin composition according to claim 1, wherein (II) = 98/2 to 2/98. 3. The weight ratio of (III) to (I) + (II) is (III) / (I) + (II) = 0.05 / 100 to 5/100. Alternatively, the resin composition according to item 2.