JP2002030181A - Polyolefin resin composition for foaming - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyolefin resin composition suited in producing polyolefin resin foamed molded products having improved mechanical properties, particularly rigidity, and a foamed molded product having excellent rigidity and dimension precision to be obtained by foaming polyolefin foaming particles in a mold. SOLUTION: The polyolefin resin composition comprises a polyolefin resin containing a modified polyolefin having a functional group in the molecule and 1-15 wt.% inorganic substance having a scaly or lamellar structure having been subjected to the treatment of rendering the inorganic substance organic. The molded product to be obtained by subjecting foaming particles obtainable from the above polyolefin resin composition to foaming in a mold improves the compressive strength at 50% strain compared to the foamed product having the same expansion ratio to be obtained from the conventional foaming particles and, e.g. a molded product having an apparent density of 30 g/L improves the compressive strength by about 9% and a molded product having an apparent density of 24 g/L improves the compressive strength by about 24%. Foaming particles to be obtained from the above polyolefin based resin composition for foaming has a small variation in LR/DR and good stability of filling into a mold.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyolefin resin composition for foaming, and more particularly, to a polyolefin resin composition for foaming suitable for producing a polyolefin resin foam molded article having improved mechanical properties, particularly rigidity. About things. In particular, a polyolefin resin composition for foaming containing an inorganic substance subjected to an organic treatment, a foamed polyolefin resin particle obtained from the foamed polyolefin resin composition, a method for producing a foamed polyolefin resin particle, and a polyolefin resin mold. The present invention relates to a method for producing a foamed molded article, a foamed molded article in a polyolefin-based resin mold, and a method for producing a foamed polyolefin-based resin molded article.

[0002]

2. Description of the Related Art Conventionally, there has been a method of blending a relatively large amount of an inorganic powder such as talc or calcium carbonate as a filler for the purpose of improving mechanical properties such as rigidity and heat resistance of a polyolefin resin molded article. Are known. Specifically, 70
A sheet material called PP filler in which -30% of polypropylene and 30-70% of talc are blended has improved mechanical strength such as rigidity and heat resistance, and is preferably formed by thermoforming into a packaging container or the like. It is used.

In recent years, due to the review of plastics materials, polyolefin resins, especially polypropylene resins, have excellent balance of mechanical strength, heat resistance, workability, price, etc., Due to its excellent properties in terms of easy recyclability and the like, its application field is expanding.

[0004] In the field of polyolefin-based resin foam molded articles as well, non-crosslinked polyolefin-based resin foam molded articles have excellent properties such as buffering properties and heat insulating properties without losing the excellent properties of polyolefin resins. Therefore, it is used in many fields such as packaging materials, building materials, and heat insulating materials. In recent years, non-crosslinked polyolefin resin foam moldings, especially polypropylene resin foam moldings, have been renewed in the limelight because of their environmental compatibility, and foam moldings with improved mechanical properties, especially rigidity, have been developed. It has been desired.

[0005]

SUMMARY OF THE INVENTION In order to improve mechanical properties such as rigidity of a polyolefin resin foam molded article,
Mechanical properties of the foamed molded article, an inorganic filler used for improving heat resistance and the like, as a result of producing a foamed molded article using a polyolefin resin composition mixed with an inorganic powder such as talc, There is almost no improvement in the rigidity of the obtained foamed molded article, and in some cases, a polyolefin-based resin foamed molded article obtained by using a resin composition containing a large amount of such an inorganic powder as a base resin. In some cases, the rigidity may be lower than that of a polyolefin resin foam molded article having an apparent density equivalent to the apparent density of a foam obtained from a base resin not mixed with inorganic powder.

Further, when a foam is produced using a polyolefin resin composition containing a large amount of inorganic powder as a base resin, the formed foam tends to become open cells and a good foamed molded article cannot be obtained. Above, the surface is defective. In addition, even in the in-mold foam molding using foamed particles, when a large amount of inorganic powder is mixed, good foamed particles cannot be obtained, and the fusion strength between the particles during molding is poor and the mechanical strength is reduced. . In addition, the cells become open cells, and a good foamed molded product cannot be obtained, and the surface of the molded product becomes defective. Therefore, the inorganic material to be added is examined, and in order to improve the mechanical strength such as heat resistance and rigidity of the foam, the surface area of the inorganic material is affected while the concentration of the inorganic material in the base resin is large, and the surface area is large. It was found that the effect was more easily exerted and the effect was more effective, and it was found that a scaly or layered inorganic material was effective.

Conventionally, as a method for improving the mechanical properties such as impact resistance of a thermoplastic resin molded article and the physical properties such as heat resistance, a matrix resin has been used as a composite material in which an organically treated clay is mixed with a resin as a filler. It has been proposed to disperse clay therein (see, for example, JP-A-10-1828).
92, JP-A-10-181190, JP-A-11
JP-A-181309), which is used for modifying resins and improving mechanical properties such as impact resistance and heat resistance of molded articles such as polypropylene resin sheets. However, there is no example of applying an organically treated inorganic material to a special technique, which is different from the usual molding of a non-foamed molded article, such as foam molding.

[0008] In the foamed molded article, there are a large number of bubbles and a bubble film which are not present in a non-foamed molded article obtained by ordinary injection molding or extrusion molding. Significantly affects physical properties. In addition, since the melting point of the base resin used, the flow characteristics of the foamable molten resin, and the extrusion temperature conditions affect the formation of bubbles, these conditions should be sufficiently considered when molding the foam. This is very important. Therefore, when the above-described composite material applied to a non-foamed molded product obtained by ordinary injection molding or extrusion molding is applied as it is as a means for improving the physical properties of the foam, the physical properties inherent to the foam are affected. In some cases, the improvement of the rigidity and the like of the foamed molded article is not always sufficiently exhibited without the need. It is clear in the example of the PP filler.

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a polyolefin resin composition for foaming which is suitable for producing a polyolefin resin foam molded article having improved mechanical properties, particularly rigidity. Furthermore, expanded polyolefin resin particles having excellent mechanical properties, especially rigidity and dimensional accuracy, a method for producing the expanded particles, and in-mold foam molding excellent in mechanical properties obtained from the expanded particles, particularly, rigidity and dimensional accuracy And a foam molding method.

[0010]

Means for Solving the Problems The present inventors have improved the properties of a polyolefin-based resin foam molded article, particularly the improvement of rigidity, by using a polyolefin-based resin foamed resin composition obtained by mixing a polyolefin-based resin with an inorganic substance. Investigations were carried out from a variety of viewpoints regarding the molded product, and it was found that a scaly or layered inorganic substance was effective in place of the conventional inorganic powder, and further examination was conducted to make the scrubbed organically treated scaly. A foam obtained from a polyolefin resin composition obtained by adding and mixing a specific amount of an inorganic substance having a layered or layered structure (hereinafter sometimes simply referred to as an “organized inorganic substance”) is a polyolefin resin foam. It has been found that mechanical properties, especially rigidity, can be improved without impairing the inherent properties of the foam shown.

That is, the present invention relates to a polyolefin resin comprising a modified polyolefin resin having a functional group in a molecule, and an organic substance having a scaly or lamellar structure, which is treated with an organic substance. A polyolefin for foaming, comprising: a polyolefin-based resin composition containing 1% to 15% by weight of an inorganic substance having a scaly or lamellar structure which has been subjected to an organic treatment. The present invention relates to a resin composition.

According to the present invention, the modified polyolefin having the functional group is at least one selected from a hydroxyl group, a carboxyl group, a carbonyl group, an amide group, an imide group, a maleimide group, a urethane group, a thiol group and an epoxy group. The present invention relates to the above polyolefin resin composition for foaming having a functional group.

[0013] The present invention relates to the above foamable polyolefin resin composition, wherein the modified polyolefin having a functional group is an acid-modified polypropylene.

According to the present invention, the above-mentioned inorganic substance having a scaly or lamellar structure which has been treated with an organic substance is a clay mineral having a scaly or lamellar structure selected from smectite clay, vermiculite, halloysite or mica. And an organic onium compound.

According to the present invention, the polyolefin resin composition for foaming has a melting point of 125 ° C. to 170 ° C. and an MFR of 0.1 g.
/ 10 minutes to 100 g / 10 minutes.

In the present invention, the polyolefin resin composition for foaming is a pellet having a cylindrical shape, and the ratio of _{R R} / D _R (where L _R is the length of the pellet, D _R is the diameter of the pellet) ) Is 0.1 to 100, and L _m / L after heat-treating the pellets at the melting point of the polyolefin resin composition for foaming. D _m ratio (where, L _m is the length of the pellets after the heat treatment, D _m represents the diameter of the pellet after heat treatment) is, with respect to L _R / D _R ratio before heat treatment 0.5-1.0 The present invention relates to the above polyolefin resin composition for foaming, characterized in that the ratio is twice as high.

Further, according to the present invention, the foamed polyolefin resin composition preferably has a cell diameter of at least 100.
The present invention relates to expanded polyolefin resin particles having a diameter of μm.

According to the present invention, there is provided an autoclave containing a particulate material comprising the foaming polyolefin resin composition, which is dispersed under pressure and in an autoclave together with a dispersing medium containing a water-soluble borate and a foaming agent in an autoclave. To produce the expanded particles by foaming the granules by discharging the particles under low pressure.

The present invention also relates to a polyolefin-based in-mold foam molded article obtained by molding in a mold polyolefin-based resin foam particles obtained by foaming the polyolefin-based resin composition for foaming.

Further, the present invention relates to a method for producing a polyolefin resin in-mold expanded molded article by molding in a mold polyolefin resin expanded particles obtained by foaming the polyolefin resin composition for foaming. A polyolefin resin characterized by expanding the foamed particles so that the apparent density of the foamed molded article in the mold becomes 0.56 times or less (not including 0) of the apparent density of the foamed particles used for molding. The present invention relates to a method for producing an in-mold foam molded article.

The present invention relates to a method for producing a polyolefin resin in-mold foam by molding polyolefin resin foam particles obtained by foaming the polyolefin resin composition for foaming in a mold. Polyolefin resin mold internal foam molding characterized by expanding the foamed particles so that the apparent density of the inner foamed molded article becomes 0.55 times to 0.25 times the apparent density of the foamed particles used for molding. It relates to a method for producing a body.

Further, the present invention provides a method for melt-kneading the above polyolefin resin composition for foaming together with a foaming agent in an extruder,
Next, the present invention relates to a method for producing a polyolefin resin foam molded article, which is extruded under low pressure to form a foam molded article.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION The polyolefin resin composition for foaming of the present invention has a scaly or lamellar structure that has been subjected to an organic treatment in a polyolefin resin containing a modified polyolefin having a functional group in the molecule. A polyolefin resin composition comprising an inorganic substance, wherein the organic substance having a scaly or lamellar structure treated with an organic substance is contained in the polyolefin resin composition in an amount of 1% by weight to 15% by weight as an inorganic substance. It contains.

The polyolefin resin containing a modified polyolefin having a functional group in the molecule includes (1) a resinous modified polyolefin having a functional group in the molecule alone,
(2) a mixture of a resin-like modified polyolefin having a functional group in the molecule and a rubbery or / and oligomer-like modified polyolefin having a functional group in the molecule, (3) a resinous form having a functional group in the molecule A mixture of a modified polyolefin of the above and a rubbery or / and oligomeric polyolefin having no functional group in the molecule, or (4) a resinous polyolefin having no functional group in the molecule, and a functional group in the molecule. Examples thereof include a mixture with a modified polyolefin having a rubbery or / and / or a resinous / and / or oligomeric form. Among them, the mixture shown in (4) is most preferable in terms of cost.

The polyolefin having no functional group in the molecule corresponds to any of the following (a) to (d). (A) Homopolymers of α-olefins such as ethylene, propylene and butene. (B) A copolymer of two or more α-olefins. (C) a copolymer comprising an α-olefin component and another monomer component having no functional group in the molecule, and
The olefin unit component ratio is 50% by weight or more, preferably 60% by weight or more, more preferably 70% by weight or more, still more preferably 80% by weight or more, and most preferably 90% by weight.
The above copolymer. (D) A mixture of two or more selected from the group of (a), (b), and (c).

The above-mentioned polyolefin having a functional group in the molecule is obtained by introducing a functional group into a polyolefin having no functional group in the molecule. The introduction of the functional group is carried out by combining a monomer capable of forming a functional group when copolymerized with an α-olefin or a polyolefin.
It is usually carried out by block copolymerization and / or random copolymerization and / or graft copolymerization.

As the polyolefin having no functional group in the molecule, specifically, a homopolymer of ethylene,
Polyethylene such as an ethylene copolymer containing 50% by weight or more of an ethylene unit component composed of ethylene and an α-olefin having 3 to 12 carbon atoms, a propylene homopolymer, propylene, and ethylene or / and 4 to 12 carbon atoms. Α-
50% by weight of propylene unit component composed of olefin
Polypropylene such as a propylene-based copolymer contained above may be mentioned.

Examples of the polyethylene include low-density polyethylene resin, medium-density polyethylene resin, high-density polyethylene resin, ethylene-1-butene copolymer, and ethylene-1-octene copolymer.
A high-density polyethylene resin having a melting point of 125 ° C. or higher and a density of 0.945 g / cm ³ or higher is particularly effective in increasing the rigidity of the obtained foamed molded article.

Examples of the polypropylene include propylene homopolymer resin, propylene-ethylene random copolymer resin, propylene-1-butene random copolymer resin, and propylene-ethylene-1-butene random copolymer resin. And a propylene-ethylene block copolymer resin. Among them, the melting point is 13
Polypropylene having a temperature of 0 ° C. or higher, preferably 135 ° C. or higher is particularly effective in increasing the rigidity of the obtained foamed molded article.

The modified polyolefin having a functional group in the molecule includes a hydroxyl group, a carboxyl group, a carbonyl group, an amide group, an imide group, a maleimide group, a urethane group,
It has a functional group such as a thiol group or an epoxy group. As such a modified polyolefin, for example,
Ethylene-maleic anhydride copolymer, maleic anhydride-grafted polyethylene, ethylene-methacrylic acid copolymer, ethylene-vinyl acetate copolymer, propylene-maleic anhydride copolymer, maleic anhydride-grafted polypropylene, maleic anhydride An acid graft-modified propylene-ethylene random copolymer is exemplified. Among them, ethylene-maleic anhydride copolymer, acid-modified polyethylene such as maleic anhydride graft-modified polyethylene, propylene-maleic anhydride copolymer, maleic anhydride graft-modified propylene-ethylene random copolymer such as Acid-modified polypropylene is preferably used.

In the polyolefin resin composition of the present invention, the modified polyolefin having a functional group has an affinity for an organic portion of the organically modified inorganic substance, and the modified polyolefin is inserted between layers of the organically modified inorganic substance. A polyolefin-based resin composition in which inorganic substances are uniformly dispersed is obtained.

The modified polyolefin having a functional group in the present invention contributes to the homogeneous dispersing action of the inorganic substance in the polyolefin-based resin. The ratio (modification amount) of monomer unit components capable of forming a functional group is at least 0.1 mol%, preferably 1 mol% in the polyolefin resin.
As described above, the resin may be selected from the polyolefin resins exemplified in the above (1) to (4). The denaturation amount is 0.1 m
When the amount is less than ol%, the effect of increasing the rigidity of the foam is poor. Conversely, if the amount of modification exceeds 10 mol%, the cost will increase and the foaming efficiency may be reduced during the production of the foam.

As the inorganic substance which has been treated with an organic substance, any known organic substance can be used. Examples thereof include JP-A-60-235712, JP-A-62-39205,
JP-A-60-83108, JP-A-64-33179
And a clay mineral having a flaky or layered structure selected from smectite clay, vermiculite, halloysite, or mica, and an organic onium compound, as described in JP-A-11-181309. Wherein the organic onium compound has a structure in which the organic onium compound is bonded to the surface of the clay mineral by an ionic bond.

Examples of the smectite clay include montmorillonite, saponite, hectorite, beidellite, stevensite, and nontronite. They may be natural or synthetic.

The organic onium compounds include hexyl ammonium, octyl ammonium, 2-ethylhexyl ammonium, dodecyl ammonium, lauryl ammonium, octadecyl ammonium, dioctyl dimethyl ammonium, trioctyl ammonium, stearyl ammonium, distearyl dimethyl ammonium, stearyl trimethyl ammonium, benzyl methyl Examples thereof include alkylammonium chloride, dimethyldialkylammonium chloride, benzyldimethylalkylammonium chloride, benzyltrialkylammonium chloride, and methyltrialkylammonium chloride.

In the present invention, the added amount of the organic substance treated in an organic manner is 1% to 15% by weight as an inorganic substance (as an inorganic substance not containing an organic substance) in the polyolefin resin composition. Is added to If the amount is less than 1% by weight, the effect of improving the rigidity of the obtained foamed molded article may not be sufficiently exhibited. Conversely, if the addition amount exceeds 15% by weight, the obtained foamed molded article may have an extremely low closed cell rate and may not sufficiently exhibit the effect of improving rigidity. In the present invention, the addition amount is preferably 2% by weight to 10% by weight.

The ratio of the organic onium compound in 100% by weight of the inorganic material subjected to the organic treatment is 10% by weight to 80% by weight.
% By weight, preferably from 30% by weight to 60% by weight.
Is more preferable. When the proportion is less than 10% by weight, it becomes difficult to obtain a polyolefin-based resin composition in which the inorganic substance is homogeneously dispersed. Conversely, when the proportion exceeds 80% by weight, the organic onium compound is added to the base resin. In some cases, it may act as a plasticizer, and in some cases, may significantly impair the effect of improving the rigidity of the foam molded article obtained therefrom.

In the present invention, when the mixture of the above (2) to (4) is used as the polyolefin resin, the modified polyolefin is added with an inorganic substance which has been subjected to an organic treatment in advance, so that the melting temperature of the modified polyolefin is higher than that of the modified polyolefin. It is preferable to melt-knead at a temperature of to form a master batch, and melt-knead this with a polyolefin having no functional group in the molecule to obtain a foamed polyolefin-based resin composition of the present invention in a desired shape. By doing so, it becomes possible to obtain a polyolefin resin composition for foaming in which the inorganic substance is homogeneously dispersed in a short time. When the masterbatch is used, when the masterbatch and the polyolefin having no functional group in the molecule are melt-kneaded, a foaming agent is further added thereto and melt-kneaded, and then extrusion foaming is performed under low pressure. Alternatively, a foam molded article can be obtained as it is by injection foam molding.

The melting point of the polyolefin resin composition of the present invention is preferably from 125 ° C. to 170 ° C. The melting point of the polyolefin resin composition is 125 ° C. or higher, preferably 130 ° C. or higher, more preferably 135 ° C.
This is particularly effective in increasing the rigidity of the obtained foam molded article. The melting point of the polyolefin resin composition is
If the temperature is too high, the processing temperature or the molding temperature may be too high, which may cause undesirable results.
70 ° C. or lower, preferably 165 ° C. or lower, more preferably 160 ° C. or lower, still more preferably 155 ° C. or lower. The magnitude of the melting point of the polyolefin-based resin composition largely depends on the type of the modified polyolefin having a functional group or the polyolefin having no functional group, the mixing ratio thereof, and the like. The melting point of the polyolefin-based resin composition generally shows almost the same value as the melting point of a modified polyolefin having a functional group as a main component or a polyolefin having no functional group.

M of the polyolefin resin composition of the present invention
FR (melt flow rate) is 0.1 g / 10 min or more,
100 g / 10 min or less is preferable, and 0.5 to 30 g / 1
0 minutes is more preferred. MFR is JIS K 721
This is a value measured under test condition 14 of 0. The MF
If the value of R is too small, the foaming efficiency tends to decrease when foaming is performed. Conversely, if the value of MFR is too large, the closed cell rate and heat resistance of the obtained foam tend to decrease, which is not preferable. . The magnitude of the MFR of the polyolefin-based resin composition largely depends on the MFR of the modified polyolefin having a functional group used, the MFR of the polyolefin having no functional group, the mixing ratio thereof, the amount of the inorganic substance subjected to the organic treatment, and the like. I do.

In the polyolefin-based resin composition of the present invention, a modified polyolefin having a functional group, a polyolefin having no functional group, and an organically treated inorganic substance are added to 100 parts by weight of a mixture of other substances, For example, other polymer components such as thermoplastic resins, synthetic rubbers, natural rubbers, and thermoplastic elastomers, and resin additives such as antioxidants, ultraviolet absorbers, lubricants, coloring agents, and flame retardants are used in a minimum necessary amount. 30 parts by weight or less, preferably 20 parts by weight or less, more preferably 10 parts by weight or less.
It may be contained in a proportion of not more than 5 parts by weight, more preferably not more than 5 parts by weight. When the content is a flame retardant, the content may be 160 parts by weight or less based on 100 parts by weight of the mixture.

The polyolefin resin composition for foaming according to the present invention can be formed by any of the known extrusion foaming molding, injection foaming molding, and in-mold foaming molding in which foamed particles are filled in a molding die and heated. It can be used, and a foam molded article having uniform cells, a smooth surface and excellent rigidity can be produced.

The polyolefin resin composition for foaming of the present invention can be formed into a columnar pellet.
Such pellets can be manufactured by extruding into a string form from an extruder and cutting to an appropriate length. Such pellets, L _R / D _R ratio (where, L _R
The pellet length, D _R represents the diameter of the pellet) is preferably 0.1 to 100. When L _R / D _R ratio is less than 0.1, then the foaming efficiency when trying to produce foamed particles tend to decrease. Also, L _R / D _R
If the ratio is larger than 100, it is difficult to supply the extruder with a stable supply during foam molding using the extruder. Also, L
_{When the R} / D _R ratio is greater than 100, the pellets are dispersed under pressure and heat in an autoclave together with a dispersing medium and a foaming agent, and the contents of the autoclave are discharged under low pressure to foam the pellets and expand the foamed particles. In the production method (dispersion medium release foaming method), the filling amount of pellets in the autoclave must be reduced in order to increase the dispersion efficiency of the pellets, and when the pellets are discharged from the autoclave under low pressure, they are easily clogged in the tube. Problem can occur. The dispersion medium release foaming method is described in, for example, JP-A-60-245650,
No. 29444, WO96 / 31558, WO
98/25996, WO98 / 06777, and the like.

[0044] L _m / D _m ratio after heat treatment at the melting point of the pellet polyolefin resin composition (although, L _m and D _m represents the length and diameter of the pellet after the heat treatment, respectively), before heat treatment of L with respect to _R / D _R ratio, i.e., the pre / (heat treatment (L _m / D _m ratio after heat treatment) L _R / D _R
Ratio) is preferably 0.5 to 1.0 times,
More preferably, it is 6 to 1.0 times. When producing expanded particles from the pellets, the pellets containing the blowing agent are heated to a temperature near the melting point of the polyolefin-based resin composition, and the L _F / D _F ratio of the expanded particles (where L _F is the length, D _F represents the diameter of the foamed particles) tend to be smaller than L _R / D _R ratio of the pellet, expected underfilling, not when it was filled in extremely small change when the mold And may result in that a desired in-mold foam molded article cannot be obtained. The above (L _m after heat treatment ₎
/ D _m ratio) / (before heat treatment L _R / D _R ratio) ratio 0.5
The fact that it is 1.0 means that the pellet has a small shape change rate due to heat treatment near the melting point and, when producing foamed particles, obtains foamed particles that have little change in particle shape and contribute to reduction of poor filling. It shows that you can do it. The ratio of (L _m / D _m ratio after heat treatment) / (L _R / D _R ratio before heat treatment) usually does not exceed 1.

Pellets having a ratio of (L _m / D _m ratio after heat treatment) / (L _R / D _R ratio before heat treatment) of 0.5 to 1.0
It is obtained by the polyolefin resin composition according to claim 1. Further, L _F of such pellets, expanded particles even slightly varying the temperature at a temperature near the melting point obtained
The rate of change of the / D _F ratio is very small. Usually, when producing expanded particles having two or more types of expansion ratios from one type of pellets, and / or two or more types of expanded particles having a high-temperature endothermic peak calorific value (hereinafter, referred to as “high-temperature peak”) described below. or slightly elevated foaming temperature is adjusted to near the melting point in the case of producing each or slightly lowering, but that L _F / D _F ratio of the rate of change is small, the kind of the foamed particles obtained by Even if the ratio is changed, the L _F / D _F ratio does not change significantly, which means that expanded particles having stable filling properties can be obtained even if the expansion ratio or the amount of heat at the high temperature peak is changed.

In the heat treatment of the pellets, ten randomly selected pellets are simultaneously placed in a silicon oil bath in which 1 liter of silicone oil adjusted to the same temperature as the melting point of the pellets is circulated and heated for one minute. This is done by: After heating for 1 minute, the pellet is pulled up, the length / diameter ratio is measured for the ten pellets, and the arithmetic average is used to determine the L _m / D _m ratio.

The average weight per pellet obtained by using the polyolefin resin composition of the present invention is usually 0.1 mg or more and 100 mg or less, preferably 0.2 mg or more and 30 mg or less. It is. If the average weight is less than 0.1 mg, it is difficult to obtain foamed particles having an intended expansion ratio, which is not preferable. The average weight per pellet is 100mg
If the weight becomes heavier, the filling property of the obtained expanded particles into the mold tends to deteriorate. The average weight per pellet is calculated by dividing the weight of 100 randomly selected pellets by 100.

In the present invention, the expanded particles have a characteristic curve which is different from the intrinsic endothermic peak (hereinafter referred to as “intrinsic peak”) corresponding to the heat of fusion of the base resin of the expanded particles in the DSC curve obtained by the differential scanning calorimetry of the expanded particles. It is preferable that a high-temperature peak appears on the high-temperature side and the calorific value of the high-temperature peak is 2 J / g or more and less than 65 J / g. High peak heat of 2 J / g
If it is less than 3, the compressive strength, the energy absorption amount, etc. of the foamed molded article are reduced. In addition, the calorie at the high temperature peak is 65 J / g.
In the above case, there is a possibility that the saturated vapor pressure at the time of molding the expanded particles becomes high. In the present invention, the heat quantity of the high temperature peak is particularly 3 J / g to 60 J / g, and is 2 to 50 with respect to the sum of the heat quantity of the high temperature peak and the heat quantity of the specific peak.
%, More preferably 10 to 40%. In addition, it is preferable that the sum total of the heat quantity of the high temperature peak and the heat quantity of the specific peak is 40 J / g to 150 J / g.

The amount of heat at the high temperature peak refers to the expanded particles 2
DS obtained when ＤＳ4 mg was heated from room temperature (25 ° C.) to 220 ° C. at 10 ° C./min by a differential scanning calorimeter.
The calorific value of the high-temperature peak b that appears on the higher temperature side than the temperature at which the specific peak a specific to the base resin that appears in the C curve (shown in FIG. 1), and corresponds to the area of the high-temperature peak b, For example, it can be obtained as follows.
That is, first, the point α on the DSC curve corresponding to 80 ° C.
When, draw a straight line (α-β) linking the point on the DSC curve beta corresponding to the melting completion temperature T _E of the expanded beads. Next, a straight line parallel to the vertical axis of the graph is drawn from a point γ on the DSC curve corresponding to the valley between the unique peak a and the high-temperature peak b, and the intersection with the straight line (α-β) is defined as δ. . The area of the high-temperature peak b is a portion surrounded by the curve of the high-temperature peak b portion of the DSC curve, the line segment (δ-β), and the line segment (γ-δ) (the hatched portion in FIG. 1). Area. still,
The sum of the heat quantity of the high-temperature peak and the heat quantity of the specific peak is the area of the portion surrounded by the DSC curve and the straight line (α-β).

Although this high temperature peak b appears in the first DSC curve measured as described above, once the first DSC curve is obtained, the high temperature peak b temporarily changes from 220 ° C. to 10 ° C./min.
The temperature does not appear in the second DSC curve obtained when the temperature is lowered to around 0 ° C. and the temperature is raised again to 220 ° C. at 10 ° C./min, and the second DSC curve shows a unique peak unique to the base resin. Only a appears.

The above-mentioned expanded particles having an endothermic curve peak on the high-temperature side of the DSC curve are prepared by dispersing the above-mentioned pellets in a dispersion medium in a closed vessel in the above-mentioned dispersion medium discharge foaming method, and heating the pellets at the melting end temperature ( Any temperature (Ta) within the range of not less than the melting point (Tm) of the pellets −15 ° C. and less than the melting end temperature (Te) without increasing the temperature to above Te).
Stop at that temperature for a sufficient time, preferably 10-60
After holding for about a minute, the temperature is adjusted to an arbitrary temperature (Tb) in the range of melting point (Tm) -5 ° C. to melting end temperature (Te) + 5 ° C., and stopped at that temperature. Preferably, the pellets can be obtained by a method in which the pellets are held for 10 to 60 minutes and then foamed by releasing the pellets from the inside of the container to a low pressure region.

In the present invention, the magnitude of the calorific value of the high-temperature peak in the expanded particles mainly depends on the temperature Ta and the holding time at the temperature with respect to the pellets when the expanded particles are produced, and the temperature Tb and the temperature at the temperature Tb. It depends on the holding time and the temperature rise rate. The calorie at the high temperature peak of the expanded particles tends to increase as the temperature Ta or Tb falls within the above temperature range and as the holding time increases. Usually, the heating rate is 0.5 to 5 ° C./min. By repeating these preliminary experiments in consideration of these points,
It is possible to easily know the production conditions for the foamed particles exhibiting the desired high-temperature peak calorific value.

The temperature range described above is an appropriate temperature range when an inorganic physical foaming agent is used alone as a foaming agent. Therefore, when an organic volatile physical foaming agent is used in combination, the appropriate temperature range shifts to a lower temperature side than the above temperature range, depending on the type and amount used.

The above melting point (Tm) is defined as the above-mentioned pellet or 2 to 4 mg of the polyolefin resin composition for foaming as a sample, and the DSC curve of the foamed particles is obtained in the same manner as described above. Is the temperature at the top of the endothermic curve peak a peculiar to the base resin observed in the second DSC curve (an example of which is shown in FIG. 2). (T
e) refers to the temperature at which the tail of the specific endothermic curve peak a returns to the baseline (α-β) position on the high temperature side. The melting points of the modified polyolefin having a functional group and the polyolefin having no functional group are also measured by the same method as the melting point of the pellet or the polyolefin resin composition for foaming.

When producing the foamed particles by employing the dispersion medium releasing method, it is preferable to add a water-soluble borate to the dispersion medium. This water-soluble borate can remove the organic onium compound (one component of the organically treated inorganic substance) present on the pellet surface,
The amount of the organic onium compound present on the surface of the obtained expanded particles can be reduced. In-mold molding using such foamed particles having a small amount of the organic onium compound present on the surface is preferable because an in-mold foamed molded article having high fusion strength between foamed particles can be obtained.

The water-soluble borate means a borate capable of dissolving at least 1 g in 1 liter of water at 80 ° C.
For example, one liter of water at 80 ° C. is selected from boric acid, borax, ammonium borate, or a salt formed from cations such as sodium, potassium, lithium, calcium, magnesium, zinc, aluminum, and iron and borate ions. Which can dissolve at least 1 g in the above. The water-soluble borate is preferably added to the dispersion medium at a ratio of 0.1 to 10 parts by weight per 100 parts by weight of the dispersion medium such as water.

The foamed polyolefin resin particles of the present invention thus obtained usually have an apparent density of 4 g / L.
６００600 g / L, but the apparent density is particularly 7 g / L〜
It is preferably 500 g / L, and the apparent density is 9 g.
/ L to 400 g / L is more preferable, and the apparent density is more preferably 10 g / L to 300 g / L. If the apparent density of the expanded particles is too high or too low, the in-mold moldability may be reduced.
The apparent density of the polyolefin resin foam particles is as follows:
Prior to measurement, the foamed particles having a known weight were measured at atmospheric pressure 23
° C., 50% relative humidity after leaving for 24 hours in a room, from the scale when the water 100 cm ³ of 23 ° C. in the same chamber being immersed in water in the contained graduated cylinder, of the expanded beads apparent volume Y ( cm ³ ) Read, foam particle weight (g)
Is divided by Y and converted to g / L.
In this measurement, the weight of the foamed particles was 0.5000 to 10.00.
A plurality of expanded particles having an amount of 00 g and Y of 50 to 90 cm ³ are used.

The expanded polyolefin resin particles of the present invention preferably have an average cell diameter of at least 100 μm. If the average cell diameter is too small, the degree of heating between the surface of the expanded particles and the inside of the expanded particles tends to greatly differ during in-mold molding, and if the apparent density of the expanded particles used for molding is relatively large, the melting of the surface of the expanded particles When the apparent density of the expanded particles used is relatively small,
There are drawbacks in that the resulting molded article tends to shrink more and the molding cycle becomes longer. Therefore, the average cell diameter of the expanded polyolefin resin particles is at least 15
0 μm, more preferably at least 200 μm
m is more preferable. However, if the average cell diameter is too large, the appearance of the in-mold foam molded article may deteriorate, and the average cell diameter is preferably 700 μm or less, more preferably 500 μm or less, and more preferably 400 μm or less. Is more preferable.
The average cell diameter of the foamed particles can be controlled mainly by the type and amount of the cell regulator and the foaming agent incorporated in the polyolefin resin composition, and the foaming temperature.

The average cell diameter of the foamed particles is determined by cutting a randomly selected foamed particle at a substantially central portion, and cutting the cut surface on a screen or a micrograph taken from an arbitrary cell wall. The number of cells (N) existing on a straight line having an arbitrary length (Q) up to an arbitrary cell wall is counted, and the average cell diameter (K ′) of each expanded particle is obtained by the following equation. However, the start point of the straight line is an arbitrary bubble wall, and the end point is another arbitrary bubble wall, so that at least 10 bubbles exist between the start point and the end point.

[0060]

K ′ = 1.62 × (Q１N)

The above operation is performed on a total of three expanded particles, and the cell diameter (K) of the expanded particles is calculated by arithmetically averaging the average cell diameter (K ') of the three expanded particles. .

The expanded polyolefin resin particles of the present invention are aged under atmospheric pressure, and if necessary, pressurized with pressurized air to increase the internal pressure, and then heated using steam or hot air. It is possible to obtain expanded particles having a higher expansion ratio.

The expanded polyolefin resin particles of the present invention are based on the procedure C of ASTM-D2856-70 (provided that the expanded particles have a diameter of 25 mm in a sample cup accommodated in a measuring instrument attached to an air-comparison hydrometer). The open cell ratio is preferably 40% or less, more preferably 30% or less, and is preferably 25% or less.
% Is most preferred. Expanded particles having a smaller open cell ratio are more excellent in moldability, and a molded article having higher mechanical strength can be obtained.

The foamed polyolefin resin particles of the present invention are filled in a mold that can be heated and cooled, and can be opened and closed, and has a saturated steam pressure of 0.10 to 0.59 MPa.
(G) The steam is supplied and heated to expand the foamed particles, to fuse the foamed particles in the mold, and then to cool and take out from the mold, adopting a normal batch-type molding method to foam in the mold. A molded article can be manufactured. In addition, the in-mold foam molded article increases the foamed particles, if necessary, to increase the internal pressure of the cells,
It is continuously supplied between the belts that move continuously along the top and bottom in the passage, expands and fuses the foamed particles when passing through the steam heating area, then cools by passing through the cooling area, and then obtains The obtained in-mold foam molded product is taken out from the passage and cut into appropriate lengths sequentially (for example, described in Japanese Patent Application Laid-Open Nos. 9-104026, 9-104027 and 10-180888). Molding method). In order to increase the internal pressure of the foamed particles, the foamed particles are placed in a closed container, and the compressed air is allowed to permeate the foamed particles by leaving the container with the pressurized air supplied for an appropriate time. I just need.

The foam molded article produced from the polyolefin resin composition of the present invention usually has an apparent density of 5 g / L.
６００600 g / L, but the apparent density is particularly 8 g / L.
To 500 g / L, and the apparent density is 1
The apparent density is more preferably from 0 g / L to 400 g / L, and even more preferably from 11 g / L to 300 g / L. In the present invention, as the apparent density decreases and / or as the degree of orientation of the cell membrane increases, the obtained molded article tends to increase the effect of improving rigidity. However, if the apparent density is too small, the open cell rate increases, which is not preferable. Incidentally, in order to increase the degree of orientation of the cell membrane, it is only necessary to apply more stretching to the strand during pelletization, or to expand the expanded particles more greatly during in-mold molding. In the case where the foamed particles are expanded to a greater extent during the in-mold molding, the apparent density of the obtained in-mold foam molded article is 0.56 times or less (excluding 0) the apparent density of the foamed particles used for molding. It is preferable to expand the expanded particles so that the apparent density of the obtained in-mold expanded molded article is 0.55 to 0.25 times the apparent density of the expanded particles used for molding. More preferably. The foam molded article obtained as described above is ASTM-D2856
The open cell ratio based on procedure C of -70 is preferably 40% or less, more preferably 30% or less, and most preferably 25% or less. A foam molded article having a smaller open cell ratio has better mechanical strength.

The apparent density of the foamed molded article was determined by measuring the foamed molded article having a known weight at a temperature of 23 ° C. under atmospheric pressure before measurement.
After being left in a room with a relative humidity of 50% for 48 hours, the apparent volume X (cm ³ ) of the foamed molded product was determined from the scale when the container was submerged in water in a container containing 23 ° C. water. It is determined by reading and dividing the weight (g) of the foamed molded product by X and converting it to g / L. For measuring the apparent density of this foamed molded article, the weight of the foamed molded article was 0.5000 to
A cut sample of 10.0000 g and an amount of X of 50 to 90 cm ³ is used.

The foamed molded article using the polyolefin resin composition for foaming of the present invention as a base resin has the physical properties inherent in the foamed article, has rigidity, is excellent in other mechanical properties, and has excellent surface properties. A molded article having good appearance can be provided. For example, a foam molded article obtained by in-mold molding using foamed particles using a polyolefin resin composition for foaming as a base resin is excellent in rigidity, and has an apparent density as shown in Examples and Comparative Examples. In a molded product having a thickness of 30 g / L and a thickness of 50 mm, the compressive strength at the time of 50% strain is improved by about 9% as compared with a molded product not using the resin composition according to the present invention, and has an apparent density of 24 g / L. About 24%.

[0068]

The present invention will be described below with reference to examples and comparative examples.

[Production of Polyorganic Resin Composition Containing Organized Inorganic Substance] Example 1 Maleic anhydride-modified polypropylene resin "MPP-1" shown in Table 1 and organized clay (Southern Clay Products Inc., USA) Product name "Cloisite"
15A ") at a ratio (weight ratio) of 2: 1 and melt-kneaded in a twin-screw extruder. Next, the melt-kneaded material is passed through a die having a number of circular outlets having a land length of 10 mm and a diameter of 3 mm. After being extruded into a strand at 170 ° C. and rapidly cooled, it was cut with a pelletizer and dried in an oven at 60 ° C. to obtain cylindrical pellets. 15 parts by weight of the pellets and the polypropylene resin "PP-1" shown in Table 1
85 parts by weight and zinc borate (cell regulator) 500 pp
m was kneaded in a twin-screw extruder, and then extruded into a strand at a temperature of 220 ° C. from a die having a number of circular outlets having a land length of 10 mm and a diameter of 2 mm at a temperature of 220 ° C., followed by quenching. Cut at 60
It dried in the oven of ° C, and obtained the cylindrical minipellet (the average weight per minipellet is 2 mg) which consisted of the organized clay-containing polypropylene resin composition. The L _R / D _R ratio of this minipellet was 1.2.

The melting point, MFR and tensile modulus of the resin composition (mini-pellet) were measured. The tensile modulus is J
It was measured under the following conditions according to IS K 7113-1981. Test piece: No. 2 type test piece Test piece thickness: 1 ± 0.1 mm Test speed: 50 mm / min Distance between chucks: 80 mm Further, the mini-pellet was subjected to the above-mentioned (L _m after heat treatment _).
/ D _m ratio) / (L _R / D _R ratio before heat treatment) ratio, i.e. (L _{m
/ D m) :( L R /} D R) was measured. Table 2 shows the above measurement results.

Example 2 The same procedure as in Example 1 was carried out except that 30 parts by weight of pellets composed of MPP-1 and organically modified clay and 70 parts by weight of a polypropylene resin "PP-1" shown in Table 1 were used. In the same manner as in Example 1, columnar mini-pellets made of the organized clay-containing polypropylene resin composition were obtained. The L _R / D _R ratio of this minipellet was 1.1. The melting point, MFR, tensile modulus and (L _m /
D _m ): (L _R / D _R ) was measured. These are shown in Table 2.

Example 3 The same operation as in Example 1 was repeated, and “MPP-1” and “C
loisite 15A "and melt-knead it into a cylindrical
Lett was manufactured. Then, 15 parts by weight of the pellets and
85 weight of the polypropylene resin "PP-1" shown in 1
Parts and zinc borate (bubble regulator) 500ppm
The resulting mixture is melt-kneaded in a twin-screw extruder, and then
Of 50 mm (10 mm in Example 1) and 1 mm in diameter
From a die having a large number of circular outlets,
Extruded into a strand at a temperature of about 2 ° C.
Quenched while taking off the strand at the take-up speed
After that, cut with a pelletizer and dry in a 60 ° C oven
, From organically modified clay-containing polypropylene resin composition
Cylindrical mini-pellets (per mini-pellet)
The average weight was 1.1 mg). L of this mini pellet
_R/ D_RThe ratio was 1.2. Also this mini pellet
Extends the land length, lowers the extrusion temperature,
As a result of the increased speed, the
The degree of orientation in the length direction of the land is increased.
ing. Melting point of the above resin composition (mini-pellet), M
FR, tensile modulus, and (L _m/ D_m ): (L_R/
D_R) Was measured. These are shown in Table 2.

Comparative Example 1 (Example in which the organic clay was changed to talc) 80 parts by weight of the polypropylene resin "PP-1" shown in Table 1 and talc (trade name "HIFILLER" manufactured by Matsumura Sangyo KK) 20 Parts by weight and 500 ppm of zinc borate were premixed and melt-kneaded by a twin-screw extruder. The melt was extruded into strands, rapidly cooled, and cut with a pelletizer to obtain mini-pellets. The mini-pellet was dried as in Example 1. The melting point of the mini-pellet, MF
R, tensile modulus, and (L _m / D _m ): (L _R / D _R )
Was measured. These are shown in Table 2.

Comparative Example 2 (Example in which a cell regulator was simply added to PP-1) Polypropylene resin "PP-1" 100 shown in Table 1
Parts by weight and zinc borate (500 ppm) were preliminarily mixed and melt-kneaded with a twin-screw extruder. The melt was extruded into strands, rapidly cooled, and cut with a pelletizer to obtain mini-pellets. The mini-pellet was dried as in Example 1. Also, as in Example 1, the melting point, MFR, tensile modulus of mini-pellet,
And (L _m / D _m ): (L _R / D _R ) was measured. These are shown in Table 2.

[0075]

[Table 1]

[0076]

[Table 2]

[Production of Expanded Particles and Expanded Molded Articles] Foaming Examples 1 to 3 Into an autoclave, 100 parts by weight of the mini-pellet obtained in Example 1 or 2 above, and water 3 as a dispersion medium.
00 parts by weight, 0.3 parts by weight of kaolin as a dispersant, 0.002 parts by weight of sodium dodecylbenzenesulfonate as a surfactant, 2 parts by weight of borax as a water-soluble borate, and carbon dioxide (dry ice) as a blowing agent Was filled in the amount shown in Table 3 and sealed, and then heated to a temperature 5 ° C. lower than the foaming temperature shown in Table 3 at a heating rate of 2 ° C./min while stirring the contents of the autoclave. At 15
After holding for 1 minute, the mixture was heated at a heating rate of 1 ° C./min to the foaming temperature shown in Table 3. Immediately thereafter, high-pressure carbon dioxide gas was supplied into the autoclave, and the pressure in the autoclave was shown in Table 3. After maintaining at the same temperature for 15 minutes while maintaining the pressure (the pressure is maintained until the end of foaming), the contents of the autoclave were discharged under atmospheric pressure to obtain foamed particles. The resulting foamed particles are 2 at atmospheric pressure.
Left for 4 hours. Next, an air pressure of 98.1 KPa (G) is applied to the foamed particles using air at 23 ° C., and after 5 hours from taking out the room at 23 ° C., the average cell diameter, apparent density, and high-temperature peak of the foamed particles are obtained. Heat of fusion (J /
g) was measured. Further, the L _F / D _F of the expanded particles is measured,
The ratio of L _F / D _F to L _R / D _R , that is, (L _F /
D _F ): (L _R / D _R ) was measured. Table 3 shows these results.
Are shown together.

Next, the foamed particles, to which the air pressure of 88.3 KPa (G) was applied in the foamed particles by using air at 23 ° C., were completely compressed to 300 mm × 300 mm ×
The mold is filled into a molding die having an inner dimension of 50 mm (at the time of filling, the mold is slightly opened so that the inner dimension in the thickness direction of the mold becomes 52 mm, and after filling, the mold is completely clamped and the mold in the thickness direction of the mold is removed. After the inner dimension becomes 50 mm, perform steam heating in the next step), then completely clamp the mold, exhaust the mold through steam into the chamber, and preheat the foamed particles in the mold with steam. After that, main heating was performed using saturated steam having a pressure shown in Table 3 (forming steam pressure), and then cooling was performed to obtain a foamed molded product. The obtained molded body was dried by being left in a room at 60 ° C. for 24 hours under atmospheric pressure, and then left to cure in a room at 23 ° C. under atmospheric pressure for 7 days, and then subjected to 50% strain compression in the same room. The strength (rigidity) was measured. These are shown in Table 3.

Foamed Comparative Examples 1 to 3 As foamed comparative examples, foamed particles were obtained in the same manner as in Examples 1 to 3 using the mini-pellets obtained in Comparative Example 1 or Comparative Example 2 above. In the same manner as in Examples 1 to 3 to obtain a foam molded article. Table 3 shows the physical properties of the obtained expanded particles and the expanded molded article after curing.

[0080]

[Table 3]

Foaming Examples 4 and 5 and Foaming Comparative Examples 4 and 5 Into an autoclave, 100 parts by weight of the mini-pellet obtained in the above Example 3 or Comparative Example 2 and water 3 as a dispersion medium were used.
00 parts by weight, 0.3 parts by weight of kaolin as a dispersant, 0.002 parts by weight of sodium dodecylbenzenesulfonate as a surfactant, and 2 parts by weight of borax as a water-soluble borate, and after sealing, the contents of the autoclave were filled. While stirring the product, it was heated at a heating rate of 2 ° C./min to a temperature 5 ° C. lower than the foaming temperature shown in Table 4, and immediately thereafter, high-pressure nitrogen gas was supplied as a foaming agent into the autoclave. While maintaining the internal pressure at the pressure shown in Table 4 (this pressure is maintained until the end of foaming), the temperature was maintained at the same temperature for 15 minutes, and then the temperature was increased at a rate of 1 ° C./min. After heating to the foaming temperature shown in (1) and maintaining at the same temperature for 15 minutes, the contents of the autoclave were discharged under atmospheric pressure to obtain foamed particles. The resulting foamed particles are at atmospheric pressure for 24 hours.
Left for hours. An air pressure of 98.1 KPa (G) is then applied to the foamed particles using air at 23 ° C.
Five hours after being taken out of the room at 3 ° C., the average cell diameter, apparent density, and heat of fusion of the high-temperature peak (J /
g) was measured. Further, the L _F / D _F of the expanded particles is measured,
The ratio of L _F / D _F to L _R / D _R , that is, (L _F /
D _F ): (L _R / D _R ) was measured. Table 4 shows these results.
Are shown together.

Next, in the foaming example 5 and the foaming comparative example 5, 88.3 KP was added into the foamed particles using air at 23 ° C.
Using the foamed particles to which the air pressure of a (G) was applied, the same operation as in the foaming examples 1 to 3 was performed to obtain a foam molded article.

In the foaming example 4 and the foaming comparative example 4,
343.2 KPa in foamed particles using air at 23 ° C.
The expanded particles to which the air pressure of (G) is applied are 210 mm ×
A mold having an inner dimension of 210 mm × 0 to 100 mm (a mold whose inner dimension in the thickness direction can be changed to 0 to 100 mm) is filled with the inner dimension in the thickness direction adjusted to 40 mm, and then completely filled. After tightening, the inside of the mold is evacuated through steam into the chamber, the foamed particles in the mold are preheated with steam, and then the main heating is performed using saturated steam having a pressure shown in Table 4 (forming steam pressure). When the introduction of steam is completed, the inner dimension of the mold in the thickness direction is
m, and then cooled to obtain a foam molded article.
The 50% strain compressive strength (rigidity) of the foam molded body after curing was measured in the same manner as in the foaming examples 1 to 3. These are shown in Table 4.

Foamed Example 6 and Foamed Comparative Example 6
100 parts by weight of the obtained mini-pellet, 300
Parts by weight, 0.3 parts by weight of kaolin as a dispersant, surfactant
Sodium dodecylbenzenesulfonate 0.0
02 parts by weight, carbon dioxide (dry ice) as blowing agent
7.5 parts by weight and 2 parts by weight of borax as a water-soluble borate
After filling and sealing, stir the contents of the autoclave.
And at a heating rate of 2 ° C./min from the foaming temperature shown in Table 4.
Heat to 5 ° C lower temperature and hold at same temperature for 15 minutes
Then, at a heating rate of 1 ° C./min, the foaming temperature shown in Table 3
Until high-pressure, and immediately
Feed into the autoclave and the pressure in the autoclave will be as shown in Table 4.
While maintaining the indicated pressure (this pressure is maintained
After performing the same temperature for 15 minutes,
The contents of the autoclave are released under atmospheric pressure to form expanded particles.
Obtained. The resulting expanded particles are left under atmospheric pressure for 24 hours.
Was. Then use air at 23 ° C. in the expanded beads.
An air pressure of 1 KPa (G) is applied, and then a chamber at 23 ° C.
5 hours after being taken out, the average bubble of expanded particles
Measure diameter, apparent density, heat of fusion (J / g) at high temperature peak
Specified. In addition, the L_F/ D_FIs measured, and L_R/ D_R
L for_F/ D_F, Ie, (L _F/ D_F): (L_R
/ D_R) Was measured. The results are shown in Table 4.
You.

Next, the foamed particles, to which the air pressure of 343.2 KPa (G) was applied by using air at 23 ° C., were placed in a molding die (thickness: 210 mm × 210 mm × 0 to 100 mm). Inner dimension in direction is 0-100
inner mold in thickness direction to 40 mm
The mold was evacuated from the mold through steam into the chamber, and the foamed particles in the mold were preheated with steam, and then saturated with the pressure shown in Table 4. Main heating was performed using steam (molding steam pressure) to complete the introduction of steam, so that the inner dimension of the mold in the thickness direction became 50 mm, and then cooled to obtain a foam molded article. The 50% strain compressive strength (rigidity) of the foam molded body after curing was measured in the same manner as in the foaming examples 1 to 3. These are shown in Table 4.

[0086]

[Table 4]

The 50% strain compressive strength was 5 mm from the foamed molded product.
Using a test piece obtained by cutting so as to be 0 mm, 50 mm in width and 25 mm in thickness, according to JIS Z 0234-1
Specimen temperature 23 ° C, loading speed 10 according to method 976 A
A compression test was performed under the conditions of mm / min until the strain reached 55%, the stress at 50% strain was read from the obtained stress-strain diagram, and this was taken as 50% strain compressive strength.

The apparent densities of the foamed moldings are the same (3
0 g / L) The following can be seen from the comparison between the foaming example 1 and the foaming comparative example 2. That is, the in-mold foam molded product according to the foaming example 1 has a compressive strength at a time of 50% strain which is about 50% lower than that of the foam molded product according to the foam comparative example 2 obtained from the conventional foam particles to which the organic inorganic substance is not added. 9% improvement.

Further, the following can be seen from a comparison between the foaming example 2 and the foaming comparative example 3 in which the apparent density of the foamed molded article is the same (24 g / L). That is, the in-mold foam molded product according to the foaming example 2 has a compressive strength at a time of 50% strain which is about 50% lower than that of the foam molded product according to the foam comparative example 3 obtained from the conventional foam particles to which the organic inorganic substance is not added. 24% improvement.

The following can be seen from a comparison between the foaming example 2 and the foaming comparative example 1 in which the apparent density of the foamed molded article is the same (24 g / L). That is, the in-mold foam molded product according to Foaming Example 2 has about 24% improvement in compressive strength at 50% strain as compared with the foam molded product according to Foam Comparative Example 1 obtained from foamed particles containing talc as an inorganic substance. ing. still,
The compressive strength at the time of 50% strain of the foamed molded article according to the foamed comparative example 1 obtained from the foamed particles containing talc as the inorganic substance has the same apparent density (24 g / L) as the above,
It can also be seen that there is no difference from the same compressive strength of the foam molded article according to the foaming comparative example 3 obtained from the conventional foamed particles to which no inorganic substance is added.

From the comparison between the foaming example 5 having the same apparent density (60 g / L) and the foaming comparative example 5, the following can be understood.
That is, when the mini-pellet is manufactured, the foam molded article according to the foaming example 5 obtained by using the mini-pellet having a higher degree of orientation in the length direction of the strand is used when manufacturing the mini-pellet. Compressive strength at the time of 50% strain is improved by about 10% as compared with the foamed molded article obtained by foaming comparative example 5 obtained from the conventional foamed particles having a small degree of orientation in the transverse direction and no added organically-organized inorganic substance. . Considering the relatively high apparent density of the foam molded article,
This degree of improvement in compressive strength is more than expected.

The following can be seen from a comparison between the foaming example 4 having the same apparent density (140 g / L) and the foaming comparative example 4. That is, the foamed molded article according to the foaming example 4 in which the mini-pellet is produced by using the mini-pellet having a high degree of orientation in the length direction of the strand and further giving a large orientation to the cell membrane during the in-mold molding is used. Foaming comparative example in which conventional foamed particles having a small degree of orientation in the length direction of the strand when the pellets are produced, and no organically-organized inorganic substance is used, and further having a large orientation in the foam film during in-mold molding. The compression strength at the time of 50% strain is improved by about 20% as compared with the foamed molded article of No. 4. Considering that the apparent density of the foam molded article is considerably high, the degree of improvement in the compressive strength is much larger than expected.

The following can be seen from the comparison between the foaming example 6 having the same apparent density (16 g / L) and the foaming comparative example 6. That is, the foam molded article according to the foaming example 6 in which mini-pellets are manufactured using mini-pellets having an increased degree of orientation in the length direction of the strand and further giving a large orientation to the cell membrane during in-mold molding is a mini-pellet. Foaming comparative example in which conventional foamed particles having a small degree of orientation in the length direction of the strand when the pellets are produced, and no organically-organized inorganic substance is used, and further having a large orientation in the foam film during in-mold molding. 6, the compression strength at the time of 50% strain is improved by about 20%. Although the apparent density of the foamed molded article is quite small, the degree of the improvement in the compressive strength is more than expected even in consideration of the apparent density.

[0094]

As described above, the polyolefin resin composition for foaming according to the present invention is suitable for producing a polyolefin resin foam molded article having improved mechanical properties, especially rigidity. It is a composition and can provide a foam molded article excellent in mechanical properties, particularly rigidity and dimensional accuracy. For example, an in-mold foam molded article of foamed particles obtained from the polyolefin resin composition for foaming of the present invention has a 50% strain compared to a molded article of the same expansion ratio obtained from conventional foamed particles to which no inorganic substance is added. Compressive strength is improved, for example, about 9% for a molded body having an apparent density of 30 g / L.
It is improved by about 24% in a molded article having an apparent density of 24 g / L. Further, foamed particles obtained from foamed polyolefin-based resin composition of the present invention has the rate of change of the relative L _R / D _R ratio of the pellet is small,
Excellent filling stability.

[Brief description of the drawings]

FIG. 1 shows an example of a chart of a first DSC curve of expanded polypropylene resin particles as one of the expanded particles according to the present invention.

FIG. 2 shows an example of a chart of a second DSC curve of a polypropylene-based resin.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Kazuya Ogiyama 5 Satsuki-cho, Kanuma-shi, Tochigi JSP Kanuma 2nd Factory (72) Inventor Toshio 282-1 Togami-cho, Utsunomiya-shi, Tochigi Blanche Room No.103 F-term (reference) 4F207 AA03 AA11 AE02 AG20 AH46 KA01 KA12 4F212 AA03 AA11 AE02 AG20 AH46 UA01 UB01 UC06 4J002 BB031 BB051 BB091 BB121 BB141 BB151 BB171 BB201 FB2100

Claims (13)

[Claims] 1. A polyolefin resin composition comprising a polyolefin resin containing a modified polyolefin having a functional group in a molecule, and an inorganic substance having a scaly or lamellar structure that has been subjected to an organic treatment. In the polyolefin-based resin composition, 1% by weight of the organic substance having a scaly or layered structure is used as an inorganic substance.
A polyolefin-based resin composition for foaming, characterized in that the composition comprises from 15 to 15% by weight. 2. The modified polyolefin having a functional group has at least one functional group selected from a hydroxyl group, carboxyl group, carbonyl group, amide group, imide group, maleimide group, urethane group, thiol group and epoxy group in the molecule. The polyolefin resin composition for foaming according to claim 1, which has: 3. The polyolefin resin composition for foaming according to claim 1, wherein the modified polyolefin having a functional group is an acid-modified polypropylene. 4. An organic substance having a scaly or lamellar structure and having a scaly or lamellar structure selected from smectite clay, vermiculite, halloysite or mica, and an organic onium compound The polyolefin resin composition for foaming according to claim 1, which is obtained from: 5. A polyolefin resin composition having a melting point of 1
25 ° C to 170 ° C, MFR 0.1 g / 10 min to 10
The polyolefin resin composition for foaming according to claim 1, wherein the amount is 0 g / 10 minutes. 6. The polyolefin resin composition for foaming is a pellet having a cylindrical shape, and its L _R / D _R ratio (where L _R represents the length of the pellet and D _R represents the diameter of the pellet) is 0. .1 to 100.
The polyolefin resin composition for foaming according to the above. 7. The pellets exhibits a cylindrical shape, L _m / D _m ratio after heat treatment at the melting point of the polyolefin resin composition (although, L _m is the pellet length, D _m represents the diameter of the pellet) but 0.5 for L _R / D _R ratio before heat treatment
The polyolefin resin composition for foaming according to claim 6, wherein the ratio is from 1.0 to 1.0. 8. The foamed polyolefin resin composition according to claim 7, which has an average cell diameter of at least 100 μm.
m. Expanded polyolefin-based resin particles, wherein 9. An autoclave obtained by dispersing a particulate material comprising the polyolefin resin composition for foaming according to claim 1 together with a dispersion medium containing a water-soluble borate and a foaming agent in an autoclave under pressure and heat in an autoclave. A method for producing expanded particles by expanding the above-mentioned granular material by discharging the content under low pressure. 10. A polyolefin resin in-mold foam molded article obtained by molding in a mold polyolefin resin foam particles obtained by foaming the polyolefin resin composition for foaming according to claim 1. 11. A foamed polyolefin-based resin composition obtained by foaming the polyolefin-based resin composition for foaming according to claim 1 in a mold to produce a polyolefin-based in-mold foam molded article. A polyolefin resin characterized by expanding the foamed particles so that the apparent density of the foamed molded article in the mold becomes 0.56 times or less (not including 0) of the apparent density of the foamed particles used for molding. A method for producing an in-mold foam molded article. 12. A foamed polyolefin-based resin composition obtained by foaming the polyolefin-based resin composition for foaming according to claim 1 in a mold to produce a polyolefin-based resin molded foam in a mold. Wherein the foamed particles are expanded so that the apparent density of the in-mold foam molded article is 0.55 to 0.25 times the apparent density of the foamed particles used for molding. A method for producing a foam molded article. 13. A foamed polyolefin resin molded article characterized in that the foamed polyolefin resin composition according to claim 1 is melt-kneaded together with a foaming agent in an extruder and then extruded under low pressure to form a foamed article. Production method.