JPS60110733A - Expandable polyolefin resin composition - Google Patents

Abstract

PURPOSE:The titled composition capable of providing an increased cross-sectional area of a product per unit weight of a discharge and being highly recoverable from shrinkage occurring after extrusion foaming, prepared by mixing a polyolefin resin with a PS resin, a volatile organic blowing agent, and a specified foaming improver. CONSTITUTION:The titled composition obtained by mixing (A) a polyolefin resin (e.g., high density PE) with (B) a PS resin, (C) a volatile organic blowing agent (e.g., hydrocarbon including dichlorotetrafluoroethylene), and (D) a foaming improver of the formula (wherein l and n are each 0 or an integer >=1, and m is an integer >=1). By using a combination of resin B and foaming improver D in continuously expansion-molding resin A together with blowing agent C by extrusion foaming or the like, it is possible to obtain the titled composition providing a markedly increased cross-sectional area of a product per unit weight of discharge and being highly recoverable from shrinkage occurring just after extrusion foaming.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a highly foamable polyolefin resin composition,
More specifically, it relates to a novel highly foamable polyolefin resin set ~ parabolic, which is a polyolefin resin blended with a polystyrene resin, a volatile organic blowing agent, and a foaming improver consisting of a compound having a specific hydroxyl group. The objective is to achieve product breakage per unit discharge of tta by using a polystyrene resin and a foaming modifier in combination when polyolefin is mixed with a volatile organic blowing agent and subjected to continuous foam molding by extrusion foaming or the like. It is an object of the present invention to provide a novel highly foamable polyolefin resin composition which has a significantly increased area and is highly resilient to shrinkage that occurs immediately after extrusion and foaming.

The present inventors have conducted various studies in order to obtain highly foamed non-crosslinked polyolefin, and have already developed a method by blending a specific volatile organic blowing agent and a specific foaming improver with polyolefin. We proposed a new composition for obtaining a highly foamed polyolefin product of high quality and a high product cross-sectional area (Japanese Patent Application No. 57-92372), but as a result of further intensive study, we found that polyolefin and a volatile organic blowing agent could be used together. By blending together a polystyrene resin and the above-mentioned foaming improver, they found a significant effect of increasing the cross-sectional area of the product per unit discharge amount and an effect of improving shrinkage recovery immediately after foaming, and completed the present invention. It's arrived.

That is, the present invention provides (a) polyolefin resin with (
b) polystyrene resin, (c) volatile organic blowing agent, and general formula (I) ii3 HC) + GH20H20 + r + CH (JllzO dirt → U
H2UH20iH--(1) (in the formula, t and n are 0 or an integer of 1 or more, m is an integer of 1 or more) and a foaming improver consisting of at least 1a+. A foamable polyolefin resin composition is provided.

In the composition of the present invention, as a foaming improver,
It is necessary to use a compound represented by the general formula (11) together with a polystyrene resin as a component foaming improver. A highly foamable composition suitable for molding can be obtained.

The mechanism of action of the above-mentioned combined effect is not yet clear, but it is believed that there are (b) a polystyrene resin that is easily soluble in organic solvents, and (a) a compound represented by general formula (1) that has a surfactant effect. However, even at the moment when it comes out of the die and reaches atmospheric pressure, the volatile organic blowing agent dissolves into the resin and the diameter of the foamable mixture containing polystyrene with strong elastic memory increases while foaming begins. However, it is thought that the cross-sectional area of the foam obtained by foaming after the die orifice is affected by the shibarasu effect is much larger than that obtained when the above-mentioned substances are not used together.

The polystyrene resin used as the (oral) component of the composition of the present invention is generally referred to as polystyrene resin, high inoculum polystyrene resin, etc., and includes styrene homopolymer, styrene-butadiene copolymer, styrene-butadiene copolymer, and styrene-based resin. Copolymers containing styrene as a main component such as acrylonitrile copolymers and styrene-methyl methacrylate copolymers are particularly suitable, and polystyrene resins are particularly preferred.

The mixing ratio of the polystyrene resin in the composition of the present invention is preferably in the range of 5 to 50 parts by weight, more preferably 10 to 30 parts by weight, based on 100 parts by weight of the resin (total of polyolefin resin and styrene resin). The range is
If it is less than 5 parts by weight, the effect of increasing the cross-sectional area and the recovery effect by adding styrene will be small, and if it exceeds 501 parts by weight, the resulting foam will have poor flexibility.

Further, examples of the compound represented by the general formula (1) include polyzolopylene glycol and polyoxyethylene-JP Rioki 7-propylene block polymer obtained by addition polymerizing ethylene oxide to both ends of polypropylene glycol. However, preferred is polyoxyethylene-polyoxypropylene block, 191J mer, and particularly preferred is the general formula (
1) is a polyoxyethylene-polyoxypropylene zolock polymer in which n is in the range of 1 to 90 and m is in the range of lθ axis 4o. These compounds may be used alone or in combination of two or more.

The compounding amount of the compound represented by the general formula (1) is 1
5. When the sum of the polyolefin resin of the component (a) and the polystyrene resin of the tray (b) is 100 parts by weight, 0.05 to 15 parts by weight, preferably 0.1 to 1 part by weight.
It is selected within the range of 0 parts by weight. If this value is less than 0.05%, the effect of increasing the cross-sectional area of the foam will not be sufficient;
If it exceeds 5 parts by weight, even if the amount is increased, the effect will not increase accordingly, making it uneconomical.

Examples of the polyolefin resin as component (a) used in the composition of the present invention include polyethylene, polypropylene, polybutene-1,1,2-polybutadiene,
, 3-polycitadiene, ethylene-zolopylene copolymer, copolymer of ethylene or propylene with other α-olefins, or ethylene-11 vinyl copolymer, ethylene-ethyl acrylate copolymer, ethylene-vinyl chloride copolymer Polymer, ethylene ionomer (ethylene-
Examples include copolymers whose main component is ethylene, such as acrylic acid copolymers (zinc or metal salts of ethylene and unsaturated calze/acid copolymers, such as IJum salt), Among them, high-density polyethylene with a density of 0.930 f 7 cm" or more is preferred.

In the composition of the present invention, these polyolefins may be used alone or in combination of two or more, and furthermore, these polyolefins may be used as a main component, and other resins may be used to improve foamability and recovery properties. It can also be used by appropriately blending it within a range that does not impair the properties.

Examples of the volatile organic blowing agent as component (iii) used in the composition of the present invention include hydrocarbons and halogenated hydrocarbons, and specific examples of these hydrocarbons include pro/zone, butane,
Pentane, pentene, hexane, etc., and specific examples of halogenated hydrocarbons include methyl chloride, methane dichloride,
Trichloromonofluoroethane, dichlorodifluoromethane, monochloromethane) IJ fluoromethane, dichloromonofluoromethane, monochlorodifluoromethane,
Examples include trichlorotrifluoroethane, dichlorotetrafluoroethane, and monochloropentafluoroethanat. Preferred among these are hydrocarbons and/or halogenated hydrocarbons containing at least 20 mol% or more of dichlorotetrafluoroethane and/or dichlorodifluoromethane, particularly hydrocarbons containing 30 mol% or more of dichlorodifluoromethane. and or halogenated hydrocarbons are preferred.

The mixing ratio of the volatile organic blowing agent in the composition of the present invention is preferably in the range of 5 to 150 parts by weight, more preferably in the range of 10 to 100 parts by weight, and less than 5 parts by weight per ioo parts by weight of resin. However, if the amount exceeds 150 parts by weight, the effect of increasing the cross-sectional area of the foam becomes small.

Particularly suitable compositions of the present invention have a temperature of 190°C.
, the melt index (H
MI) is 35f/10min or less and density is 0.93Of
/ High-density polyethylene of α3 or higher, and heated to a temperature of 200
Melt flow rate (MFI) measured at °C and a load of 5Kf
t) of 5 f/10 min or less and dichlorodifluoromethane as a volatile organic blowing agent from 30 to 80
% by mole, and a combination with at least one selected from other halogenated hydrocarbons, such as trichlorofluoromethane, dichloromonofluoromethane, trichlorotrifluoroethane, methyl chloride, and dichloride methane, and the general formula (It is a mixture of 11 compounds.

The composition of the present invention may contain a cell nucleating agent, which is usually used once, if necessary. Examples of the bubble nucleating agent include inorganic fine powders such as talc and silicon oxide, structuring fine powders such as zinc stearate and calcium stearate, and citric acid and sodium bicarbonate. A fine powder that can generate gas when heated is used, and in addition, an ultraviolet absorber, an antioxidant, an antistatic agent, a coloring agent, etc. can be included as desired.

To prepare the composition of the present invention, the components (a) to (a) and predetermined amounts of additional components added as necessary are mixed by any method commonly used for preparing a homogeneous mixture. do. Particularly suitable are the master batch method and the triblend method. Although there is no particular restriction on the order in which the components are added, the usual method is to mix the components other than the volatile organic blowing agent in advance and then mix this blowing agent in the extrusion foaming step.

A commonly used method for producing a foam from the composition of the present invention is, for example, a method in which the composition is prepared at high temperature and pressure, and then exposed to a low temperature and low pressure region to form a foam. In this case, examples of hK type force method include extrusion foaming method,
Although a press foaming method, an injection foaming method, an in-mold foaming method, etc. can be applied, the extrusion foaming method is advantageous.

In this way, extruded foam molded articles of various shapes, such as sheets, boards, rods, tubes, wires, nets, etc., can be manufactured.

Furthermore, the composition of the present invention is particularly suitable for producing thick boards.

The foam obtained from the composition of the present invention is a high foam with an expansion ratio of 5 to 150 times, and has excellent heat insulation and cushioning properties, such as insulation, cushioning, etc. It is useful as a packaging material, etc.

Next, the present invention will be explained in more detail with reference to Examples.

The foams in Examples and Comparative Examples were evaluated according to the following evaluation method and criteria.

Foam density is 30 after foaming based on JIS-6767.
It was calculated from the weighted volume of the aged foam, and the expansion ratio was determined according to the following formula.

Density (2) Section Index of Foam A measure for evaluating suitability for molding thick molded products with a large cross-sectional area, and the section index was calculated according to the following formula.

The larger this value is, the larger the foam cross-sectional area can be obtained with a smaller extrusion amount, and the more suitable it is for molding thick objects.

(3) Recovery time Immediately after extrusion foaming, the obtained foam shrinks when cooled to room temperature and recovers without further aging. The time required for recovery is defined as follows. did.

Recovery time: The volume of the foam measured within 15 seconds immediately after extrusion foaming is taken as 100, and the time required from immediately after foaming to recover to 90% or more of the volume.The shorter this time, the longer it will be stored in the warehouse. It is not necessary and is advantageous for industrial continuous production.

(4) Flexibility 30 days after extrusion foaming, diameter 15mm, length 100+n
A perfectly cylindrical foam of 50 mm was bent so that both ends of the foam were in contact with each other, and the flexibility was evaluated based on the change that occurred in the foam as follows.

A: There is no change in shape even when bent, and it is very flexible.

B: When the foam is bent, a crack will be generated on the surface of the foam, but the depth is less than 5 gourds.C: When the foam is bent,
The foam is inflexible and has a depth of more than 5m.

A foam with excellent flexibility, which is the object of the present invention, must have a flexibility of at least 0 or more.

Additionally, Table 1 shows the additives used in each Example and Comparative Example.

Table 1 Example 1 High density polyethylene (density 0.954 f/cm3.
IIMI5 F/10 minutes, 85 parts by weight of Santic B 880 (manufactured by Asahi Kasei Industries, Ltd.) and polystyrene V 7 (MFR
1.5f/10min.

15 parts by weight of Styron GP605 (manufactured by Asahi Kasei Industries, Ltd.), 0.5 parts by weight of a foaming improver (polyoxyethylene, polyoxyzolopyrene block copolymer, Pronon 201 (manufactured by NOF Corporation)), and a cell nucleating agent. 0.02 parts by weight of talc was added thereto, triblended using a Henschel mixer, and sufficiently uniformly kneaded using a mixed wire extruder to prepare a base material for foam molding.

The first extruder with a blowing agent inlet in the cylinder (caliber 3
A second extruder (diameter 4°, L/D=3'0) equipped with a cooling oil jacket on the cylinder
Using an extrusion foaming device 6' having a structure in which L/D=30) were connected in series, the base material was fed to the first extruder heated to a maximum of 220° C. at a feeding rate of 4 Ky/hour. , a prescribed blowing agent is injected into the zone where this is melted and kneaded,
A foaming composition was prepared. The blowing agent used was a mixture of dichlorodifluoromethane and dichlormethane in an equimolar ratio, and was continuously supplied using a high-pressure pump at a ratio of 50 parts by weight to 100 parts by weight of the resin. The composition obtained in this way is supplied to the second extruder through a connecting pipe, where it is gradually cooled to the optimum foaming temperature, and the composition is passed through a rond die attached to the tip of the second extruder. A foam was obtained by extrusion. Dies of 16 diameters can be exchanged in 0.2mm increments from 2.0+mφ to 5.0nonφ, and under the above extrusion conditions, the shear rate at the tip of the die is approximately 170 to 270.
Foaming behavior in the range of 0 sec' can be observed.

Generally, when the die diameter is increased under the conditions of a constant discharge rate, the product cross-sectional area increases, but the resin pressure at the die decreases, and when it reaches the critical pressure determined by the composition, foaming occurs within the die. The cross-sectional area of the product is drastically reduced, and the air bubbles become interconnected and the surface becomes rough, resulting in a significant loss of commercial value. All evaluations in the experiments shown below were conducted under conditions in which the cross-sectional area of the product was at its maximum immediately before foaming within the die occurred.

The evaluation results of the obtained foams are shown in Table 2.

As can be seen from this table, the foam obtained from the composition of Example 1 shows a high section index and has a fast recovery time (see Comparative Example 1 in Table 3). The material must be suitable for continuous molding of thick materials with large cross-sectional areas.
In addition, the foam was foamed to a high magnification, had good appearance, good closed cell properties, and had sufficient commercial value.

Furthermore, the flexibility of the obtained foam was not inferior to the original flexibility of polyethylene foam, and the properties of polyethylene resin were utilized as they were.

Comparative Example 1 A foam was produced in the same manner as in Example 1, except that one or both of the polystyrene resin and the foaming improver were not used.

The evaluation results of the obtained foams are shown in Table 2.

As can be seen from this table, although all compositions are foamed at high magnification, the cross-section index is smaller than that of Example 1, and the example in which polystyrene is not blended (Experiment A2.4)
The foam remained shrunk without reaching 90% or more of its volume immediately after foaming.

Furthermore, when comparing the cross-sectional area increasing effect of the polystyrene resin and the foaming improver with Example 1, it is found that the single system of the polystyrene resin and the foaming improver has a certain degree of cross-sectional area increasing effect, but when both are combined. As a result, it can be seen that an effect of increasing the cross-sectional area that cannot be estimated from a single system is produced.

Margin Example 2 Below, as shown in Experiment Nos. 5 to 10 in Table 3, the same procedure as Example 1 was carried out except that the type or amount of the foaming improver was changed.
A foam was produced.

The evaluation results of the obtained foams are shown in Table 3.

As can be seen from this table, all foams obtained from compositions within the scope of the present invention exhibit high cross-sectional indexes,
It had good recovery properties, excellent moldability for thick materials, was foamed at a high magnification, had good appearance and closed cell properties, and had sufficient commercial value.

Comparative Example 2 As shown in Experiment No. 11.12 in Table 3, a foam was produced in the same manner as in Example 1 except that the amount of foaming improver used was changed.

The evaluation results of the obtained foams are shown in Table 3.

As can be seen from this table, when the amount of the foaming improver is less than 0.05 parts by weight, the cross-sectional area increasing effect is small, and when it exceeds 15 parts by weight, the effect is small relative to the amount added.

Example 3 A foam was produced in the same manner as in Example 1 except that the amount of polystyrene resin used was changed as shown in Table 4, Experiment No. 13.14.

The evaluation results of the obtained foams are shown in Table 4.

As can be seen from this table, all foams obtained from compositions within the scope of the present invention exhibit high cross-sectional indexes,
It had good recovery properties, excellent moldability for thick materials, foamed to a high magnification, good appearance and independent temperature properties, and had sufficient black market value.

Comparative Example 3 A foam was produced in the same manner as in Example 1, except that the content of polystyrene was changed from 1t1c as shown in Experiment Nos. 15 to 16 in Table 4.

The evaluation results of the obtained foams are shown in Table 4.

As can be seen from this table, when the content of polystyrene resin is less than 5%, the effect of increasing the cross-sectional area is small, and it takes time to recover, resulting in poor moldability of thick materials. %, the resulting foam no longer exhibits the flexibility that is a feature of polyolefin resin foams.

Table 4, Example 4 As shown in Table 5, Experiment Nos. 17 to 19, foams were produced in the same manner as in Example 1, except that the type and amount of blowing agent used were changed.

The evaluation results of the obtained foams are shown in Table 5.

As can be seen from this table, all foams obtained from compositions within the scope of the present invention exhibit high cross-sectional indexes,
It had good recovery properties, excellent moldability for thick materials, was foamed at a high magnification, had good appearance and closed cell properties, and had sufficient commercial value.

Comparative Example 4 As shown in Table 5, Experiment No. 20.21, a foam was produced in the same manner as in Example 1, except that the type of blowing agent and the amount of blowing agent used were changed.

The evaluation results of the obtained foams are shown in Table 5.

As can be seen from this table, when dichlorodifluoromethane or dichlorotetrafluoroethane is foamed with an unmatched foaming agent, the foam remains shrunk and does not recover to the volume immediately after foaming, the foaming ratio is low, and the foam is full of wrinkles. became.

Margin below

Claims (1)

[Claims] L (a) polyolefin resin, (b) polystyrene resin, and (c) volatile organic blowing agent) general formula % formula %
() (In the formula, t and n are O or an integer of 1 or more, and m is a polyolefin resin composition for extrusion foaming obtained by mixing with a foam improver. General formula The combined amount of the composition and foaming improver according to claim 1, which is an integer above, is 0.05 to 15 parts by weight per 100 parts by weight of resin (sum of polyolefin resin and polystyrene resin). Claim 1 which is part
Composition table according to item 1 or 2 Claim 1, @2, wherein the polyolefin resin is high-density polyethylene
Composition 6 according to Item 4, wherein the volatile organic blowing agent is dichlorodifluoromethane; Composition 6, wherein the volatile organic blowing agent is a hydrocarbon and/or halogenated hydrocarbon containing dichlorotetrafluoroethane The composition 7 according to claim 1, 2, 3 or 4, wherein the polystyrene resin is polystyrene. Composition according to item 4, item 5 or item 6