JPS63113037A - Improved expandable polyolefin based resin particle - Google Patents

Abstract

PURPOSE:To obtain the titled resin particles, containing a readily volatile foaming agent, capable of reducing evaporation of the readily volatile foaming agent and having excellent preservation stability, by sulfonating, chlorosulfonating or chlorophosphonating the surface layer part. CONSTITUTION:Particles obtained by sulfonating, chlorosulfonating or chlorophosphonating the surface layer part of expandable polyolefin based resin particles containing a readily voltatile foaming agent, e.g. propene, pentane, etc. The layer thickness of the surface layer part is desirably 1-200mu and the content of the readily volatile foaming agent is preferably 3-30wt% based on the resin content.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to expandable polyolefin resin particles whose surface layer has been modified. The present invention relates to expandable polyolefin resin particles that have excellent storage stability and whose dissipation is suppressed by a modified surface layer.

(Prior art and problems) Expandable polyolefin resin particles containing an easily volatile blowing agent and having a sulfonated, chlorosulfonated, or chlorophosphonated surface layer are a new substance that has not been described in any literature. .

Conventionally, highly elastic resin foams have been manufactured using polyethylene, polypropylene, and compositions in which polyethylene is blended with polystyrene as raw resins. However, when these raw material beads contain an easily volatile foaming agent, their retention of the foaming agent is extremely poor, and therefore they cannot be sold as raw material beads like expandable polystyrene; Currently, they are commercially available as pre-expanded particles or expanded molded bodies.

(Means for Solving the Problems) The present invention ultimately solves these problems and provides novel expandable polyolefin resin particles that have not existed in the past.

That is, the gist of the present invention is to provide expandable polyolefin resin particles containing an easily volatile blowing agent and having a surface layer portion that is sulfonated, chlorosulfonated, or chlorophosphonated.

The polyolefin resin particles referred to in the present invention include low-density polyethylene, high-density polyethylene, linear low-density polyethylene, polypropylene, ethylene-propylene random copolymer, ethylene-at-Ml
These include ethylene-styrene graft copolymer, ethylene-acetate pinyloose 4-v graft copolymer, chlorinated polyethylene, etc., and these may be used alone or in admixture with each other. Further, other resins may be mixed with these polyolefin resins. In this case, the polyolefin resin is at least 50% by weight. Further, these polyolefin resins may be crosslinked with peroxide or the like. Furthermore, there are no particular limitations on the granulation of the resin. A typical method for granulation is extrusion pelletizing. The conditions for extrusion pelletizing are appropriately selected depending on the resin used and are not particularly limited, but it is preferable that the resulting pellet has less residual strain. In addition, the diameter of the particles is not limited in any way, but those of about 11III are usually used.
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Therefore, the feature of the present invention is that by sulfonating, chlorosulfonating, or chlorophosphonating the surface layer of the pellet, the escape of the easily volatile blowing agent impregnated into the pellet is reduced, and the preservation of the pellet is reduced. The aim is to obtain expandable polyolefin resin particles with excellent stability, and a conventionally known reaction can be used for sulfonation, chlorosulfonation, or chlorophosphonation. That is, sulfonation is carried out using concentrated sulfuric acid, fuming sulfuric acid, chlorosulfuric acid, etc. as a sulfonating agent at room temperature to 100°C, chlorosulfonic acid is used as a chlorosulfonating agent, or chlorination is carried out after sulfonation. These methods include chlorosulfonation and chlorophosphonation in which phosphorus trichloride is reacted in the presence of oxygen.

The preferred thickness of the surface layer modified by these methods depends on the size of the polyolefin resin particles used, but in the case of particles with an average diameter of 0.5 aam or more, such as those commonly used in bead molding. It is preferable that the area between 1 and 200 μm from the surface of the particles is modified. This is because if only a thin layer of less than 1 μm is modified, the effect of suppressing the escape of the blowing agent is small, and if the thickness exceeds 200 μm, the original characteristics of the resin will be impaired.

Easily volatile blowing agents referred to in the present invention include aliphatic hydrocarbons such as propane, butane, pentane, hexane, and heptane, and aliphatic halogenated hydrocarbons such as Freon-11, Freon-12, and Freon-114. Boiling point organic compounds are preferably used, but are not particularly limited, and these can be used alone or in combination. The content of these blowing agents is preferably in the range of 3 to 3 M% based on the resin content. If the content is less than 3% by weight, the desired expansion ratio cannot be obtained, and if the content exceeds 30% by weight, it is not necessary to use it to obtain the desired expansion ratio.

In order to incorporate these easily volatile blowing agents into pellets, for example, a pellet whose surface layer has been modified in advance is immersed in a readily volatile blowing agent solution under high temperature conditions. It is possible.

The expandable polyolefin resin particles thus obtained are
It has good retention of the foaming agent it contains, and can maintain its foaming ability even after long-term storage.

(Example) Next, an example of the present invention will be shown, but the present invention is not limited only to the example.

Example 1 High-pressure polyethylene (density 0.
922, MI value 1.5) 100 parts by weight and 135 parts by weight of water were added, and while stirring, 0.45 parts by weight of dicumyl peroxide was added to 15 parts by weight of water containing 5 parts by weight of Neoverex (surfactant) O, 0. After adding the solubilized or finely dispersed system under heating and stirring, 50 parts by weight of water containing 0.3 parts by weight of calcium phosphate was added, and after degassing, the mixture was replaced with nitrogen and held at 100°C for 12 hours. , 4 at 140°C
After holding for a period of time, it was cooled to 40°C, the contents were taken out, washed with water, and dried to obtain crosslinked polyethylene particles with no fusion between particles. The gel fraction (insoluble matter in boiling xylene for 48 hours) of this crosslinked polyethylene was 51% by weight.

The crosslinked polyethylene particles were immersed in concentrated sulfuric acid at 50° C. for 120 minutes, taken out, washed with water, and dried to obtain surface-sulfonated crosslinked polyethylene particles.

When the state of sulfonation of the obtained particles was examined using an X-ray microanalyzer as the amount of sulfur element in the cross section of the particles, it was found that sulfur was distributed from the surface of the particles to the inside of 50 μm, and that the peak The largest part is the outermost part,
Its concentration was 8% by weight.

Next, the surface sulfonated crosslinked polyethylene particles 100
Part by weight, 0.5% by weight polyvinyl alcohol aqueous solution 12
0 parts by weight and 25 parts by weight of butane were placed in an autoclave, and the temperature was raised to 100°C and maintained for 6 hours while stirring, then cooled, taken out, and dried to obtain expandable particles. The aging properties of the foaming agent retention properties of the foamable particles were examined at 23°C. The results are shown in Table 1.

Comparative Example 1 Expandable particles were obtained in the same manner as in Example 1, except that the surface layer of the crosslinked polyethylene particles was not sulfonated. The chronology was investigated. The results are shown in Table 1.

Example 2 Cross-linked polyethylene particles were treated with concentrated sulfuric acid at 70°C.
Expandable particles were obtained in the same manner as in Example 1, except that the heating time was 180 minutes. The results are shown in Table 1.

Example 5 Cross-linked polyethylene particles were treated with concentrated sulfuric acid at 30°C.
Expandable particles were obtained in the same manner as in Example 1 except that the heating time was 160 minutes. The results are shown in Table 1.

Rice 1 The amount of blowing agent impregnated was determined as the weight loss during leaving the pellet immediately after impregnating the blowing agent in an atmosphere at 100° C. for 1 hour.

Rice 2 It is expressed as the residual rate (% by weight) at each time point relative to the amount of foaming agent that was initially impregnated. Stored in an open state at 123℃.

Examples 4 to 8 In Example 1, instead of butane as the blowing agent, propane, pentane, Freon-11, Freon-12, and
Table 2 shows the results using Freon-114.

Comparative Examples 2 to 6 In Comparative Example 1, instead of butane as the blowing agent, propane, pentane, Freon-11, Freon-12, and
Table 2 shows the results using Freon-114.

Table 2 Impregnated blowing agent aging c%) Blowing agent type Foaming agent amount (wt%) 1 hour 1 day 7 days 20 days Example 4 Propane 23.5 90.2 84. A 66
57.1 5 Pentane 22.1 9
1.1 82,1 61.5 53.4〃 6 Freon-1224,894゜8 90.6 82
73.1 7 Freon-1121,891,2
82,360,652,3 8 Freon-114
24,593,888,781,270,5 Comparative Example 2
Propane 26.1 16.2 0 0
0〃 3 Pentane 24.3 12.1 0
0 0〃 4 Freon-1226,52
6,0000〃 5 Freon-1123,323,2
000〃6 Freon-11427,524,40
00 Example 9 5 g of the crosslinked polyethylene particles of Example 1 were gradually added to a 20% trichlene solution of chlorsulfonic acid while cooling with ice, and then stirred at room temperature for 60 minutes. After washing and drying the obtained chlorosulfonated polyethylene particles, we examined the distribution of sulfur elements using an X-ray microanalyzer.We found that sulfur was distributed from the surface of the particles to the inside of 50 μm, and the maximum peak was at the maximum. The outer shell portion had a concentration of 5% by weight.

In order to examine the foaming agent retention of the obtained particles, they were impregnated with butane using the method of Example 1, and the results are shown in Table 3.

Example 10 Ethylene-propylene random copolymer (density 0.90
f/cm, MI value 9, ethylene content approximately 4.5%) 1
00 parts by weight and 0.05 parts of powdered talc,
The mixture was extruded into pellets approximately 1.5 m in size.

The obtained pellets were immersed in a phosphorous trichloride solution at 55° C. for 60 minutes while bubbling oxygen, then washed with water and dried to obtain ethylene-propylene random copolymer particles with surface chlorophosphonation.

When the state of chlorophosphonation of the obtained particles was examined using an X-ray microanalyzer as the amount of phosphorus element in the cross section of the particles, it was found that phosphorus was distributed from the surface of the particles to the inside of 80 parts m. The maximum peak was in the outermost shell portion, and its concentration was 4% by weight.

In order to examine the foaming agent retention of the obtained particles, they were impregnated with butane using the method of Example 1, and the results are shown in Table 3.

Table 3 (Effects of the Invention) As is clear from the results of Examples and Comparative Examples, the foamable polyolefin resin particles of the present invention, which have been subjected to surface strength, sulfonation, chlorosulfonation, or chlorophosphonation, are easily volatile and foamable. It can be seen that when the foaming agent is contained, the retention of the foaming agent over time is dramatically improved.

Claims (3)

[Claims] (1) Contains an easily volatile blowing agent, the surface layer is sulfonated,
Expandable polyolefin resin particles that are chlorosulfonated or chlorophosphonated. (2) The expandable polyolefin resin particles according to claim 1, wherein the layer thickness of the surface layer portion is in the range of 1 to 200 μm. (3) Claims 1 or 2 in which the easily volatile blowing agent comprises one or more of propane, butane, pentane, Freon-11, Freon-12, and Freon-114. expandable polyolefin resin particles.