JP2007138004A - Foamed molding composed of resin composition compounded with potassium ionomer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a foamed molding which has a homogeneous fine cell formation by water having no environmental load, is harmless, and has excellent cushioning property, antistatic property, and thermal welding characteristics using a high frequency wave. <P>SOLUTION: The foamed molding is produced from a composition obtained by blending 5-50 parts by weight of potassium ionomer of ethylene-unsaturated carboxylic acid copolymer with 100 parts by weight of a thermoplastic resin other than the ethylene-unsaturated carboxylic acid copolymer or an elastomer, and is obtained by subjecting a mixture containing the above composition and water or any material that may generate moisture at the time of foaming to the foaming by water. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a foamed molded article comprising a potassium ionomer-comprising resin composition, and more specifically, a predetermined amount of water in a composition in which a thermoplastic resin or elastomer is blended with a potassium ionomer of an ethylene / unsaturated carboxylic acid copolymer. The present invention relates to a foam molded article obtained by water foaming the contained product.

In order to avoid damage during transportation and storage, it is widely practiced to store products in foamed resin molded containers such as foamed polystyrene and foamed polyurethane having excellent buffering properties, or to package them with foamed resin films.
In particular, when the product is an electronic component or the like, such a foamed resin container or film is used because it is necessary to avoid even slight scratches on the packaging, but it is made of foamed polystyrene or foamed polyurethane. In the case of using a general-purpose product, problems such as dust adhering due to electrification and generation of electrostatic sparks have been problems.
For this reason, an attempt has been made to use a foamed resin containing an antistatic agent. However, the antistatic agent bleeds out over time, causing new inconveniences that contaminate electronic components and has not been widely adopted.

As measures for avoiding the above disadvantages, a foamed resin material that is excellent in buffering property and antistatic property and that does not contaminate an article to be packaged has been studied, and several materials have already been proposed. .
For example, Patent Document 1 discloses a resin composition of a potassium ionomer of an ethylene / unsaturated carboxylic acid copolymer and an olefin polymer, a chemical blowing agent such as azodicarbonamide, dinitrosopentamethylenetetramine, dicumyl peroxide, t -An invention of a non-chargeable crosslinked foam obtained by adding a crosslinking agent such as butylcumyl peroxide to foam is disclosed.
Patent Document 2 discloses an invention of a closed cell type foamed film obtained by foaming a potassium ionomer of an ethylene / unsaturated carboxylic acid copolymer with a chemical foaming agent.

JP-A-4-296338 Japanese Patent Laid-Open No. 8-113661

  The foamed product comprising the potassium ionomer or a composition of the olefin polymer and the potassium ionomer itself may have non-charging properties, and both are excellent in buffering properties and antistatic properties, and are suitable for the above-described uses. Can be used.

However, the foams of Patent Documents 1 and 2 use chemical foaming agents such as azodicarbonamide and dinitrosopentamethylenetetramine for their production, that is, foam molding.
These chemical foaming agents are flammable per se, generate harmful gases during combustion, and further have a drawback that they are difficult to handle, such as being immediately decomposed by contact with an acid or the like.
Further, the foaming gas contains a large amount of carbon monoxide, carbon dioxide gas and the like.

  In recent years, such chemical foaming agents, especially organic chemical foaming agents that are often harmful or dangerous substances, such as fluorocarbon gases, as foaming gases even if they are inorganic and relatively safe substances themselves, Those that emit gas such as light hydrogen carbonate gas, carbon dioxide gas, and carbon monoxide are avoided from the viewpoint of environmental load, and a foaming agent or a foaming method having no environmental load has been strongly demanded.

  The present inventors, from the above viewpoint, are harmless to the contents to be contained or packaged, have excellent buffering properties and antistatic properties, and do not use a harmful chemical foaming agent in foam molding, for example, As a result of earnest research to develop a foamed molded article that does not affect the environment even when the bubble gas in the foam is released to the outside air, a resin composition containing potassium ionomer in a specific amount ratio, the composition The present inventors have found that a foamed molded product obtained by water foaming a product containing a predetermined amount of water satisfies all the above requirements, and based on this finding, the present invention has been completed.

Accordingly, an object of the present invention is to provide a foamed molded article that is homogeneous and finely formed by foaming with water having no environmental impact, is harmless, and has excellent buffering and antistatic properties.
Another object of the present invention is to provide a foamed molded article having excellent heat-sealing characteristics by high frequency.

  According to the present invention, a composition containing 5 to 50 parts by weight of potassium ionomer of an ethylene / unsaturated carboxylic acid copolymer and water with respect to 100 parts by weight of a thermoplastic resin or elastomer (excluding the following potassium ionomer). There is provided a foam-molded product obtained by water-foaming.

  The foam molded article of the present invention is structurally obtained by water-foaming a resin (or elastomer) composition containing a specific amount of ethylene / unsaturated carboxylic acid copolymer potassium ionomer. Is a remarkable feature.

The foamed molded article of the present invention has no environmental impact and is excellent in buffering properties and antistatic properties because it can form homogeneous and fine cells.
Furthermore, the heat-sealing property by high frequency is also excellent.

In the foamed molded article of the present invention, the unsaturated carboxylic acid content of the ethylene / unsaturated carboxylic acid copolymer constituting the potassium ionomer is preferably 1 to 35% by weight.
The neutralization degree of the potassium ionomer is preferably 50% or more.

Furthermore, it is preferable that the expansion ratio of the foamed molded product is 2 to 10 times.
Further, the ethylene / unsaturated carboxylic acid copolymer constituting the potassium ionomer is an ethylene / (meth) acrylic acid copolymer, and the other thermoplastic resin or elastomer is an olefin polymer resin or elastomer. In addition, it is preferable that the effective water content in foaming of the composition comprising the thermoplastic resin or elastomer and potassium ionomer is 1000 ppm to 5% by weight.
Furthermore, the shape of the foamed molded product may be a film or a sheet.

  According to the present invention, there is also provided a laminated sheet obtained by laminating at least one layer of the film-like or sheet-like foamed molded article.

The foamed molded article of the present invention has excellent buffering properties and moldability due to the formation of homogeneous and fine cells, and can produce various molded articles such as containers, packaging films, and sheets, and the containers and films. The sheet or the like does not damage the items to be contained or the items to be packaged.
In addition, the antistatic property is remarkably excellent, and even when rubbed in a dry atmosphere, it is difficult to cause electrostatic troubles such as dust adhesion and electrostatic sparks, and no bleed of contaminants occurs.
For this reason, it is particularly suitable as a container, film, or sheet for housing or packaging electronic components or the like.
Furthermore, the foamed molded product of the present invention, particularly the film-shaped or sheet-shaped foamed molded product, is excellent in heat-fusibility, and therefore, molding processing by thermal bonding is easy and rich in secondary workability.

In addition, since it is formed by water foaming, even when no chemical foaming agent is used or when it is used in combination, a very small amount is used, there is almost no environmental load, and safety is high.
Since the foaming gas is not carbon monoxide, carbon dioxide, chlorofluorocarbon, hydrocarbon gas or the like, there are many advantages such as that such a gas does not leak to the outside even if the molded body is broken.

Hereinafter, embodiments according to the present invention will be described in more detail and specifically.
The present invention relates to a composition in which a potassium ionomer of an ethylene / unsaturated carboxylic acid copolymer is blended with a thermoplastic resin (or elastomer), which contains water (or a substance capable of generating water during foaming). The invention comprises a foamed molded product, and a laminate formed by laminating at least one layer of the film or sheet-shaped foamed molded product of the present invention.

Examples of the unsaturated carboxylic acid in the ethylene / unsaturated carboxylic acid copolymer used as the resin component of potassium ionomer in the present invention include acrylic acid, methacrylic acid, fumaric acid, maleic acid, maleic anhydride, monomethyl maleate, A monoethyl maleate etc. can be illustrated.
Among these, acrylic acid or methacrylic acid is preferable.

In the present invention, the ethylene / unsaturated carboxylic acid copolymer may be one in which not only ethylene and unsaturated carboxylic acid but also other monomers are copolymerized.
Examples of such other monomers include unsaturated carboxylic acid esters, vinyl esters, and carbon monoxide.
Examples of unsaturated carboxylic acid esters include methyl acrylate, ethyl acrylate, isobutyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, and n-butyl methacrylate. In addition, dimethyl maleate, dimethyl fumarate and the like, and vinyl esters include vinyl acetate and vinyl propionate, respectively.

The ethylene / unsaturated carboxylic acid copolymer has an ethylene content of 65 to 99% by weight, preferably 70 to 98% by weight, and an unsaturated carboxylic acid content of 1 to 35% by weight, preferably 2 to 30% by weight. %, And other monomers are 0 to 40% by weight, preferably 0 to 30% by weight.
In the present invention, the ethylene / unsaturated carboxylic acid copolymer may not be only one kind of copolymer, but may be a mixture of two or more kinds of copolymers.
When composed of the above mixture, the average content of the mixture is 65 to 99% by weight, preferably 70 to 98% by weight, and the unsaturated carboxylic acid content is 1 to 35% by weight, preferably 2 to 30% by weight. It is preferable that the other monomer is in the range of 0 to 40% by weight, preferably 0 to 30% by weight.

The degree of neutralization (average) in the potassium ionomer of the ethylene / unsaturated carboxylic acid copolymer is 40 mol% or more, preferably 50 mol% or more, more preferably 70 mol% or more.
When a potassium ionomer having a degree of neutralization smaller than the above range is used, the antistatic property of the foamed molded article becomes insufficient.
The ionomer of the present invention has a melt flow rate (MFR) at 190 ° C. and a load of 2160 g from 0.1 to 20 g / 10 min, particularly 0 from the viewpoint of molding processability, mechanical strength of the obtained foamed molded article and the like. It is preferable to use one having a thickness of 5 to 5 g / 10 minutes.

  In the present invention, the other thermoplastic resin or elastomer blended in combination with the potassium ionomer is not particularly limited as long as it is a resin or elastomer that can form a composition with the potassium ionomer. , Polyolefin (PO) resins or elastomers, polystyrene (PS) resins or elastomers, polyester (PET) resins or polyether resins or elastomers, polyurethane resins or elastomers, polyamide resins or elastomers, other resins or elastomers, etc. Can be mentioned.

  Polyolefin (PO) -based resins or elastomers used in the present invention include olefin homopolymers and copolymers of two or more olefins, olefins and unsaturated carboxylic acids or their ionomers, unsaturated carboxylic acid esters, etc. It is a general term for resins or elastomers composed of copolymers with polar monomers, and may be highly crystalline, low crystalline, or amorphous.

  Examples of such polyolefin-based resins or elastomers include ethylene, propylene, 1-butene, 1 pentene, 1-hexene, 1-octene, 1-decene, 4-methyl-1-pentene, butadiene, dicyclopentadiene, Examples thereof include a resin or an elastomer composed of a homopolymer such as 5-ethylidene-2-norbornene and a copolymer of two or more olefins.

  More specifically, these olefin polymers include high-, medium-, or low-density polyethylene, low-crystalline or non-crystalline ethylene such as linear low-density polyethylene including metallocene-catalyzed polymerized polyethylene, and ethylene / propylene copolymer. -Ethylene / α-olefin / diene copolymer such as α-olefin copolymer or ethylene / propylene / diene copolymer, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, etc. .

Examples of unsaturated carboxylic acid ester components in copolymerization of olefin and unsaturated carboxylic acid ester include vinyl esters such as vinyl acetate and vinyl propionate, and esters such as acrylic acid, methacrylic acid and maleic acid. For example, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, isooctyl (meth) acrylate, (meth ) 2-ethylhexyl acrylate can be exemplified.
In addition, acrylic acid or methacrylic acid is preferable as the unsaturated carboxylic acid in the copolymerization of olefin and unsaturated carboxylic acid.

The proportion of the unsaturated carboxylic acid and / or unsaturated carboxylic acid ester component in the copolymer may be, for example, 1 to 60% by weight, preferably 5 to 50% by weight.
More specific examples of the copolymer include ethylene / vinyl acetate copolymer, ethylene / (meth) methyl acrylate copolymer, ethylene / (meth) ethyl acrylate copolymer, ethylene / (meth) acrylic. Acid n-butyl copolymer, ethylene / (meth) acrylic acid isobutyl copolymer, ethylene / (meth) acrylic acid copolymer or ethylene / (meth) acrylic acid copolymer and sodium, magnesium, zinc, etc. 1 Examples thereof include a resin or an elastomer composed of an ionomer (excluding potassium ionomer) neutralized with a valent or divalent metal ion.
Further, partially saponified products of ethylene / vinyl acetate copolymer and ethylene / vinyl alcohol copolymer can be used.

  Examples of the polystyrene (PS) resin or elastomer used in the present invention include polystyrene, styrene / butadiene copolymer, styrene / isoprene copolymer, styrene / acrylonitrile copolymer, and styrene / butadiene / acrylonitrile copolymer. Examples thereof include a resin or an elastomer composed of a polymer, an acrylate / styrene / acrylonitrile copolymer, an acrylonitrile / chlorinated polyethylene / styrene copolymer, and the like.

  Polyester (PET) or polyether resins or elastomers include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate (PEN), polyethylene terephthalate / isophthalate copolymer, polyester thermoplastic elastomer, polyoxymethylene ( Examples thereof include resins or elastomers comprising polyacetal).

  Examples of the polyurethane resin or elastomer include resins or elastomers made of various thermoplastic polyurethanes such as polyurethane, polyether urethane, polyester urethane, and the polyamide resin or elastomer includes nylon 6, nylon 66, nylon 61, nylon. 11, a resin made of nylon 12, a polyamide-based thermoplastic elastomer, or the like.

The foamed molded product in the present invention can be manufactured in addition to a soft one, but a hard one can also be manufactured, but the degree of hardness and softness can be adjusted by selecting the type and blending amount of the thermoplastic resin or in the case of a soft foamed molded product. Although it is not necessary to mix | blend a crosslinking agent like the postscript, when making a hard foaming molding, for example, dicumyl peroxide, t-butyl cumyl peroxide, di-t-butyl peroxide, 1,3-di ( such as t-butylperoxyisopropyl) benzene, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3 An appropriate amount of a crosslinking agent (usually about 0.1 to 5 parts by weight with respect to 100 parts by weight of the resin composition) may be added and crosslinked and foamed.
Among these thermoplastic resins or elastomers, olefin polymer resins or elastomers are preferred, and in particular, when the foamed molded product is soft, polyethylenes such as low density polyethylene and linear low density polyethylene, ethylene / vinyl acetate, etc. A copolymer, an ethylene / (meth) acrylic acid alkyl ester copolymer, an ethylene / (meth) acrylic acid copolymer, or an ionomer thereof is preferable. Density, linear low density polyethylene, ethylene / vinyl acetate copolymer, ethylene / (meth) acrylic acid alkyl ester copolymer, ethylene (meth) acrylic acid copolymer or its ionomer and the cross-linking agent are preferably used used.

The resin composition used for the foamed molded article of the present invention is 5 to 50 parts by weight, preferably 10 to 30 parts by weight, of the ethylene / unsaturated carboxylic acid copolymer potassium ionomer with respect to 100 parts by weight of the thermoplastic resin or elastomer. , And in some cases, a cross-linking agent is blended to obtain a resin composition, which is absorbed in the atmosphere by moisture absorption of potassium ionomer to obtain a resin composition having a predetermined water content.
In some cases, water and water vapor are added to give the resin composition a predetermined water content, that is, 1000 ppm (0.1 wt%) to 5 wt%, preferably 5000 ppm (0.5 wt%) to 4 wt% when foamed. % Effective moisture content.
Here, the effective water content refers to the amount of water that can effectively contribute to water foaming under foaming conditions.

If the water content at the time of foaming of the resin composition exceeds the above upper limit, it will be difficult to sufficiently act as a foaming agent, and sufficient foaming will not occur, forming a homogeneous and fine foamed cell. It becomes impossible.
Moreover, sufficient foaming does not occur when the lower limit is not reached.
The composition before foaming of the foamed molded article of the present invention may be produced by adding water to a thermoplastic resin or elastomer and a potassium ionomer. However, since the potassium ionomer itself exhibits a considerably high hygroscopic property, Then, when the atmospheric humidity is high to some extent, the moisture content within the specified range of the present invention can be achieved by leaving the mixture of the thermoplastic resin or elastomer and the potassium ionomer or the potassium ionomer in the air without adding water. It is possible to adjust.

The foamed molded article of the present invention is produced by water-foaming a resin composition containing moisture in the above range.
For foam molding of the resin composition, the moisture-containing resin composition is heated to a predetermined temperature in a molding machine by a method such as T-die extrusion foam molding, cast extrusion foam molding, inflation foam molding, or profile extrusion foam molding. By heating, water evaporates and foaming is performed.
The foaming temperature varies depending on the composition of the resin composition, the foaming ratio, the water content, and other conditions, and is appropriately set, but is usually 160 to 280 ° C, more preferably 180 to 220 ° C.
The heating time for performing the foaming operation is also appropriately set in consideration of the resin composition, the foaming ratio, the water content, the heating temperature, etc., but is generally 30 seconds to 1 hour, preferably 1 to 10 minutes.

In the present invention, the foaming ratio of the foamed molded product varies depending on its use, desired properties, etc., and is appropriately determined, but is usually preferably about 2 to 10 times.
For foaming in the present invention, water as a foaming agent is usually sufficient. However, depending on applications and specifications, for example, hydroxyl group-containing fillers such as magnesium hydroxide and aluminum hydroxide, water-absorbing polymers, azo A chemical foaming agent such as dicarbonamide, dinitrosopentamethylenetetramine or sodium bicarbonate, or impregnation with foaming gas such as propane gas or carbon dioxide gas may be used in combination.

  In addition, upon foaming, various additives such as foam stabilizers, antioxidants, light stabilizers, ultraviolet absorbers, lubricants, antiblocking agents, organic or inorganic pigments, dyes, and the like are added to the resin composition of the present invention. Furthermore, for the purpose of imparting dimensional stability, imparting heat resistance and increasing the amount of the foamed molded article obtained, inorganic fillers such as calcium carbonate (charcoal) and talc, Si fillers such as silica, and glass Polysaccharide organic fillers such as cellulose and chitosan may be added.

The foamed molded product of the present invention can take various shapes, and typical molded product shapes include foamed sheets and foamed films.
When making it into a foam film, the thickness is usually preferably 20 μm to 2 mm.

The foamed sheet or film of the present invention can of course be used in a single layer, but when a material having higher mechanical strength properties such as tear strength is required, a thermoplastic comprising at least one layer is required to improve this. It is good to use it laminated with a film layer.
Such a thermoplastic polymer film is preferably an ordinary non-foamable film, for example, high-pressure polyethylene, linear low-density polyethylene, polypropylene, ethylene / vinyl acetate copolymer, ethylene / (meth) acrylic acid ester copolymer. Polymer, ethylene / (meth) acrylic acid copolymer or ionomer thereof, olefin polymer or copolymer such as ethylene / (meth) acrylic acid / (meth) acrylic acid ester copolymer or ionomer thereof, polyester, Examples of the film include one or more layers such as polyamide, ethylene / vinyl alcohol copolymer, polyvinyl chloride, and polyvinylidene chloride.
In particular, it is preferable to laminate a non-foamed resin film layer as a skin layer on both surfaces of the foamed sheet of the present invention.
The thickness of the laminated film is preferably about 30 μm to 3 mm.

  The foamed molded product of the present invention is used for the packaging containers, films, sheets and the like already described, and hard materials are furniture, boards, panels, partitions, top plates, desk edges, skirting boards, waist walls, benches It is suitable for deformed extruded building materials such as miscellaneous materials, miscellaneous goods sheets, etc., and soft materials are suitable for various leathers, desk edges, skirting boards, waist walls and the like.

  The present invention will be specifically described by the following examples, but the present invention is not limited to these examples.

"Example 1"
30 parts by weight of potassium ionomer resin (MFR 0.5 g / 10 min) in which 80% of methacrylic acid in an ethylene / methacrylic acid copolymer (methacrylic acid content 18% by weight) is neutralized with potassium ions, and ethylene / methacrylic acid 70 parts by weight of an acid copolymer zinc ionomer (trade name: HiMilan 1650 manufactured by Mitsui DuPont Polychemical Co., Ltd.) was blended with a kneader to form a sheet, which was formed at a temperature of 23 ° C. and a relative humidity of 50%. The sheet was left in a humid atmosphere for 6 days to adjust the water content in the sheet to 1.2% by weight.

  The grain sheet composition was finely cut, put into a T-die extruder and extruded, and foamed and extruded into a foamed film having a thickness of 1 mm and a width of 150 mm (foaming condition: extrusion resin temperature 200 ° C.).

Claims (9)

  A composition containing 5-50 parts by weight of potassium ionomer of ethylene / unsaturated carboxylic acid copolymer and water is foamed with 100 parts by weight of thermoplastic resin or elastomer (excluding the following potassium ionomer). Foam molded body.   The foamed molded article according to claim 1, wherein the unsaturated carboxylic acid content of the ethylene / unsaturated carboxylic acid copolymer constituting the potassium ionomer is 1 to 35 wt%.   The foamed molded article according to claim 1 or 2, wherein the degree of neutralization of the potassium ionomer is 50% or more.   The foaming molding according to any one of claims 1 to 3, wherein the foaming ratio is 2 to 10 times.   The foamed molded article according to any one of claims 1 to 4, wherein the ethylene / unsaturated carboxylic acid copolymer constituting the potassium ionomer is an ethylene / (meth) acrylic acid copolymer.   The foamed molded article according to any one of claims 1 to 5, wherein the thermoplastic resin or elastomer is an olefin polymer resin or elastomer.   The foamed molded article according to any one of claims 1 to 6, wherein an effective moisture content in foaming of the composition in which the potassium ionomer is blended with the thermoplastic resin or elastomer is 1000 ppm to 5 wt%.   The foamed molded product according to any one of claims 1 to 7, wherein the foamed molded product is a film or a sheet.   A laminated sheet obtained by laminating at least one layer of the film or sheet-like foamed molded product according to claim 8.