JPS60188435A - Production of polyolefin resin foam particle - Google Patents

Abstract

PURPOSE:To form the titled foam particles of a uniform expansion ratio, by dispersing polyolefin resin particles containing a higher fatty acid salt in water contained in a sealed vessel, heating the dispersion to a predetermined temperature, and discharging it into air. CONSTITUTION:Use is made of particles of a polyolefin resin (e.g., propylene/ ethylene random copolymer) containing 0.4-10wt% 12-22C higher fatty acid metal salt (e.g., aluminum stearate). Namely, in a sealed vessel, 100pts.wt. above polyolefin resin particles are dispersed in about 200-1,000pts.wt. aqueous medium (preferably, a dispersion obtained by adding sodium dodecylbenzenesulfonate to a suspension of a difficulty water-soluble salt formed by mixing an aqueous calcium hydroxide solution with an aqueous phosphoric acid solution). The resulting dispersion is heated (this is accompanied with a pressure increase) to a temperature of the softening point of the resin - (its m.p.+25 deg.C). The resin particles together with the aqueous medium are discharged into air to obtain expanded particles.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing polyolefin resin foam particles. A foam product obtained by filling the foam particles produced by the method of the present invention into the cavity of a mold having steam holes and heating them with steam to fuse the foam particles together It is strong and has excellent mechanical strength, making it useful as a heat insulating material for hot spring piping, a heat insulating material for solar water heaters, and a packaging material for refrigerators and televisions.

Polystyrene foam is excellent as insulation material and packaging cushioning material.
It is used in areas such as floor desks. However, this polystyrene foam has a low compression strain recovery rate and a heat resistance of 70 to 80°C at most.

These drawbacks can be solved by using polypropylene foam or cross-linked polyethylene foam, but in order to produce the foam particles that are the raw materials for forming these polyolefin foams, polyolefin resins have a high rate of expansion agent dissipation. Therefore, it has the disadvantage that it is difficult to obtain, and even if it can be obtained, it has the disadvantage that only a low foaming product with a bulk density of 1 to 0.5 t/crl can be obtained.

As a method to solve this drawback, inorganic filler
Polyolefin resin particles containing ~70% by weight are dispersed in water as a dispersion medium in a sealed container, and the dispersion is heated to a pressure higher than the saturated vapor pressure of the dispersion and a temperature higher than the softening point of the polyolefin. A high pressure is maintained to allow water, which is a dispersion medium, to penetrate into the polyolefin resin particles, and then this dispersion is ejected from a high-pressure sealed container into atmospheric pressure to achieve a bulk density of 0.05 to 0.07/trI. A method for producing highly foamed polyolefin foam particles was proposed (
Special Publication No. 49-2183).

This method uses water as a dispersion medium as a blowing agent.
This method has the advantage that foam particles can be produced at a lower cost than a method of foaming using an organic expanding agent such as dichlorodifluoromethane, butane, or hexane. However, the presence of an inorganic filler is not preferable because it inhibits the fusion of the foam particles during molding.

When we retested the invention without a filler, we found that when using a polyolefin resin that does not contain an inorganic filler that absorbs water, resin foam particles with an expansion ratio of about 18 times can be obtained. Inside, the foaming ratio is 2.
It became clear that 2 to 8% of particles (with small particle size) that were ~3 times as large were contained. Irregular shapes of foam particles cause uneven filling rates during molding, and it is not possible to obtain molded products with consistent mechanical properties.

The present invention has been made to solve the problem of irregular shapes of foam particles, in other words, the foaming of resin particles is not uniformly performed. Polyolefin resin particles containing 0.4 to 10% by weight of metal salts of higher fatty acids are dispersed in water, heated to a temperature above the softening temperature of the resin particles and below a temperature 25°C higher than the melting point. Impregnated with water, then
A discharge port provided below the water surface in the sealed container is opened, and polyolefin resin particles containing an expanding agent and water as a dispersion medium are simultaneously discharged into an atmosphere at a lower pressure than the inside of the container, thereby producing polyolefin resin foam particles. The present invention provides a method for manufacturing.

A second invention provides a method for obtaining foamed resin particles with a uniform shape according to the first invention, in which (a) -5 = 0.4 to 5% of the higher fatty acid metal salt, and b) glycerin. , sorbitan, polyglycerin, and esters of higher fatty acids having 12 to 22 carbon atoms.
The present invention provides a method for producing foam particles having a higher expansion ratio using polyolefin particles containing s~2%.

In the present invention, the resin of the polyolefin resin particles includes low density polyethylene, linear low density polyethylene, high density polyethylene, ethylene/vinyl acetate copolymer, polypropylene, ethylene-propylene block copolymer, and ethylene-propylene random copolymer. , ethylene-butene pot fluoropylene random terpolymer, silane cross-linked polypropylene, cross-linked polyethylene, etc. are used. These may be a mixture. In particular, propylene resins such as ethylene (4 to 10 weight i1%)/propylene random copolymer, ethylene/butene/propylene random turbo polymer, and silane crosslinked polypropylene provide foam particles with excellent heat resistance and are highly moldable. preferable.

6- Next, (a) as a metal salt of a higher fatty acid, the number of carbon atoms is 1.
Metal salts (Zn, A, K, Na, Ca) of 2 to 22 higher fatty acids (e.g. stearic acid, oleic acid, palmitic acid, myristic acid, lauric acid, etc.), particularly aluminum stearate and zinc stearate are preferred. . This higher fatty acid metal salt is present in the resin particles in an amount of 0.4 to 10% by weight.
It is preferably blended in a proportion of 0.5 to 2% by weight.

In addition, (b) esters of higher fatty acids having 12 to 22 carbon atoms and glycerin, polyglycerin, and sorbitan include glycerin monostearate, glycerin distearate, glycerin tristearate, sorbitan oleate, and fluvitan laurate. , glycerin monooleate, polyglycerin oleate, glyceryl trilysyllate, glyceryl acetyl lysyllate, glycerin monopalmitylate, and the like.

This ester is used in a proportion of 0.05 to 5%, preferably 0.5 to 2%, in the resin particles.

When the amount of these higher fatty acid metal salts (a) and esters (b) is large, the resulting polyolefin foam particles are filled into a mold cavity with steam holes, and the foam particles are fused together by steam heating. If a foam product is molded by adhesion, the degree of fusion between the foam particles is low and only a product with low strength can be obtained.

ERW of one polyolefin resin particle is 0.01 to 20
It is Tq. In addition to the above-mentioned metal salts and esters of higher fatty acids, these resin particles include inorganic fillers such as talc, clay, silica, calcium carbonate, titanium oxide, barium sulfate, and zeolite, stabilizers, ultraviolet absorbers, and volatile expansion agents. It may contain agents etc.

Volatile expansion agents are used to increase expansion ratio. Examples of such swelling agents include aliphatic hydrocarbons such as propane, butane, pentane, hexane, and heptane; halogens such as trichlorofluoromethane, dichlorodifluoromethane, dichlorotetrafluoroethane, methyl chloride, ethyl chloride, and methylene chloride; An organic compound having a boiling point of 80° C. or lower, such as carbonized hydrocarbon, can be used.

It is also possible to impregnate the polyolefin resin particles with this volatile swelling agent in advance and then disperse the resin particles in water, but from the viewpoint of the manufacturing process, the polyolefin resin particles are dispersed in water in a closed container, and then the container is sealed. After supplying an expanding agent into the container and heating it to a temperature equal to or higher than the softening temperature of the propylene copolymer resin particles while maintaining the pressure inside the sealed container at the vapor pressure of the expanding agent or higher, the temperature The pressure is maintained for a certain period of time, and then the discharge port provided below the water surface in the sealed container is opened, and the polyolefin resin particles containing the swelling agent and water are simultaneously discharged into an atmosphere at a lower pressure than the inside of the container. Method for producing resin foam particles (
JP-A No. 57-12035, No. 57-25336, No. 57-90027, No. 5'l-195131, No. 5
No. 8-1732, No. 58-23834, No. 58-25
No. 334, No. 58-33435, No. 58-55231
No. 58-76229, No. 58-76231, No. 58-76232, No. 58-76233, No. 58-
No. 76234 and No. 58-87027-〇-) are more preferable.

As a dispersant for dispersing the polyolefin resin particles in water, a water-releasable inorganic dispersant such as titanium oxide, aluminum monolayer, calcium carbonate, basic magnesium carbonate, zinc carbonate, or tribasic calcium phosphate is used. Dispersants play a role in preventing polyolefin resin particles dispersed in water from fusing together when heated above their softening point, and inorganic dispersants are stable at high temperatures.
polyvinyl alcohol, methyl carboxycellulose,
It is more commonly used than water-soluble polymeric protective colloid agents with poor thermal stability such as N-polyvinylpyrrolidone.

When tricalcium phosphate is used as a dispersant, a suspension aid may be used in combination. Such suspension aids include anionic surfactants such as sodium dodecylbenzenesulfonate, sodium alkanesulfonate, sodium alkylsulfate, sodium olefin sulfate, acylmethyltaurine, sodium dialkylsulfosuccinate; polyoxy Ethylene alkyl ether, polyoxyethylene fatty acid ester, polyoxyethylene alkylphenol ether, solhitan fatty acid ester,
Examples include nonionic surfactants such as polyoxyethylene sorbitan fatty acid ester; amphoteric surfactants such as alkyl betaine and alkyl diethylene triaminoacetic acid.

Particularly preferable ones include a solution prepared by mixing an aqueous solution of calcium hydroxide and an aqueous phosphoric acid solution to form a water-soluble salt as the suspending agent (4), and using sodium dodecylbenzenesulfonate as a suspending aid. It is something.

The suspension agent (A) above is obtained by reacting phosphoric acid in an aqueous solution at a ratio of 0.60 to 0.67 mol with respect to 1 mol of calcium hydroxide, and is an aqueous solution containing a poorly water-soluble salt thereof. The pH of is 8.5 to 11.5. The aqueous solution of the poorly water-soluble salt contains hydroxyapartite ((Caa(PO4)
It may also contain z'la・ca(OH)2).

An aqueous solution containing this poorly water-soluble salt can be used as a dispersion medium for polyolefin resin particles by adjusting the content of the poorly water-soluble salt to 0.1 to 0.3%.

If the weight is less than 0.01, blocking of the bulk polyolefin unknown fat particles is likely to occur. Furthermore, if the amount exceeds 0.3%, the [phase] adhesion of the resulting foam particles will be impaired. A water-soluble medium such as methanol, ethanol, glycerin, or ethylene glycol can also be blended with water as a dispersion medium.

The surfactant, which is a suspension aid, is 0.0% of water, which is a dispersion medium.
Used at a rate of 0.001 to 0.005%.

If it is less than 0.0001% by weight, there is a problem that blocking of the polyolefin resin particles is likely to occur under heating and pressure. On the other hand, even if it exceeds 0.005%, it is economically disadvantageous because the blocking prevention effect cannot be further improved.

The amount of water in the dispersion medium per 100 parts by weight of the polyolefin resin particles is 200 to 1.000 parts by weight, preferably 25 parts by weight.
0 to 500 weight is parts. If it is less than 200 parts, heat it.
Polyolefins tend to block each other at D0 pressure. If the number exceeds 1,000 electric resistance stitches, the productivity of the polyolefin resin foam particles decreases and is not economical.

An aqueous dispersion of polyolefin resin particles dispersed in water using a fine water-repelling salt of tricalcium phosphate with an average particle size of 0.01 to 0.8 microns as a clouding agent and a surfactant as a dispersion aid. If necessary, a gaseous expanding agent or a liquid expanding agent is supplied, and this dispersion is heated in a closed container to a temperature above the softening point of the polyolefin resin and below a temperature 25°C higher than the melting point. At the same time, the vapor pressure of water, which is a dispersion medium, increases, and then the polyolefin resin particles are transported together with water, which is a dispersion medium, through a slit or a discharge port of a nozzle provided at the bottom of the closed container, in a lower pressure region than the closed container, generally. By discharging into atmospheric pressure, polyolefin resin foam particles having a bulk density of 0.026 to 0.2 r/cJ can be produced.

As the dispersion is heated, the pressure increases, water (or water and a volatile swelling agent when an expanding agent is used) soaks into the polyolefin resin particles, and the resin particles become 13-expandable resin particles. Although the pressure inside the sealed container increases due to heating, nitrogen, It is preferable to pressurize by supplying an inorganic gas such as air, helium, or argon. The pressure of the inorganic gas is 1 to 50 Kyl a! G, preferably 5-25Kg/cJG, more preferably 5-IOK
ri/crl G. This pressurization with inorganic gas can prevent the polyolefin resin particles from remaining in the closed container after discharging the dispersion liquid, and is significant in obtaining polyolefin resin foam particles having fine and uniform cells.

The heating temperature was determined by differential thermal analysis of polyolefin resin particles (
DSC) is performed, and the peak of the crystal melting temperature (so-called melting point, a) on the DSC chart shown in Figure 1 is found, and this peak descends from the hood (f fb), which is about 10 degrees Celsius lower than this peak, and the DSC The temperature that reached the bottom of the chart of (
A temperature approximately 10° C. higher than C) may be selected. Preferably, the temperature of (C) is 14 degrees. For example, in the case of a propylene homopolymer having a melting point of 164°C, the heating temperature is set to 154 to 193°C.

In addition, in the case of propylene ethylene/butene-1 copolymer with a melting point of 135°C, the melting point is 125 to 160°C, and the melting point is 11
When using an ethylene homopolymer at 0°C, the temperature is set at 100 to 135°C.

However, the heating temperature specifically shown here is based on the melting point measured with resin particles that do not contain expansion agents or organic solvents.
i is selected.

The foam particles thus obtained are dried in a room at 30 to 65°C to remove water adhering to the surface, and then used to mold cushioning materials, containers, and the like.

As the molding method, various conventionally known methods can be used. An example is shown below.

■ After filling the polyolefin resin foam particles into the mold, the foam particles are compressed to reduce their volume by 15-50%, and then steam of 1-5 Kg/c4 G is introduced to separate the foam particles. After fusing, the mold is cooled to obtain a product.

(2) The foam particles are pre-impregnated with a volatile expansion agent to impart secondary foamability to the foam particles, which are then filled into a mold and steam-molded.

■8 The foam particles are placed in a closed chamber, and then an inorganic gas such as air or nitrogen gas is forced into the chamber to increase the pressure inside the cells of the foam particles and give secondary foaming properties. The foam particles that have been given properties are filled into a mold and steam-molded.

(2) Combination of two or more of the above (2) to (4) 4゜The polyolefin resin foam product molded in this way has high mechanical strength as it is infused with the fusion sounds of the foam particles.

Hereinafter, the present invention will be further explained in detail with reference to Examples. Note that parts and percentages in the examples are based on weight.

Example 1 When an aqueous solution of 0.716 parts of calcium hydroxide Q dissolved in 100 parts of water and 0.372 parts of an aqueous solution of 17% phosphoric acid were mixed, a salt with a particle size of 0.05 to 0.3 microns was obtained. 0.1% was precipitated (pH 9,2). To this was added sodium dodenlebenzenesulfonate to prepare the following dispersion.

Water syneresis salt concentration 0.1% Dispersion pH 9.2 Dodecylbenzenesulfonic acid concentration 0.003% After transferring 100 parts by weight of this dispersion into an autoclave equipped with a discharge nozzle at the bottom, the weight of one particle was Approximately 1■,
Aluminum stearate: 5% by weight, stabilizer: 0.5%
Ethylene (4%) and propylene (96% by weight)
%) random copolymer particles (melting point: 137°C) were added into the autoclave, and nitrogen gas was supplied into the autoclave until the internal pressure within the autoclave reached 10 kg/dG.

Next, the dispersion was heated in the autoclave to 135° C. over about 60 minutes, and was further maintained at the same temperature for 20 minutes. The pressure inside the autoclave at this time was approximately 30 chest/alG.

After that, the dispersion was further heated to 150°C and held at the same temperature for 2 hours, and then the valve of the discharge nozzle at the bottom of the autoclave was opened and the dispersion was discharged into atmospheric pressure for 2 seconds to cause foaming. Ta. (Based on differential thermal analysis, the expanded polypropylene particles prior to release contained approximately 4% water within the particles). At the moment the dispersion liquid is discharged from the autoclave, in other words, the moment the gas phase begins to be discharged, the internal pressure of the autoclave is approximately 9 da/ctl.
It was G. Also, during dispersion discharge, the temperature of the autoclave was 150°C.

The bulk density of the polypropylene foam particles thus obtained was approximately 0.13 f/cJ. Further, the granularity of the foam particles was almost the same, and no blocking between the foam particles was observed.

After leaving the foam particles in a room at 40°C for 2 days to dry the moisture, they were placed in a sealed room and weighed 3Kg/al.
Air of G was introduced for 48 hours to impart secondary foamability to the particles (pressure aging).

The foam particles given this secondary foaming ratio are filled into a mold cavity with steam holes, and then 4.51C9/d is filled into the mold cavity.
G steam is introduced to perform secondary foaming, fuse the foam particles together, and then cool the foam to a bulk density of about 0.11 f/ctl, length 200 mm, width 3 oo, height. A 50 Wm polypropylene foam article was obtained.

When this product was broken in half by hand and the degree of fusion of the foam particles was examined, it was found to be 70%.

The degree of fusion is defined as 0% when all the foam particles have separated at the interface when the product is broken, and the degree of fusion is defined as 0% when the foam particles have 100% cohesive failure and peeled off. Wear degree 1
It was set as 00%.

Example 2 Ethylene (4% by weight)/propylene random copolymer particles containing 0.5% by weight of zinc stearate, 0.05% by weight of calcium stearate, and 0.5% by weight of a stabilizer as resin particles. Foam particles were obtained in the same manner as in Example 1 except that the following was used.

The bulk density of the resulting polypropylene foam particles is approximately 0.1
1 f/Cd, and the particle sizes were uniform. No blocking of the foam particles with each other was observed yet (the foam particles had absorbed about 3.8% of water before release).

These foam particles were aged under pressure in the same manner as in Example 1 to impart secondary foaming power, and then steam-molded to obtain a foam product having a bulk density of approximately 1 oy/aJ.

The degree of fusion of the foam particles of this product was approximately 65%.

Example 3 As resin particles, ethylene (4% by weight)/propylene random copolymer containing 1.0% by weight of aluminum stearate, 1.0% by weight of glycerin monostearate, and 0.5% by weight of stabilizer Foamed particles were obtained in the same manner as in Example 1 except that the combined particles were used.

The bulk density of the resulting polypropylene foam particles is approximately 06
1y/-, and the particle sizes were uniform. Further, no blocking of the foam particles with each other was observed (the foam particles had absorbed about 3.6% of water before release).

Using this foam particle, it was aged under pressure in the same manner as in Actual BFP Example 1 to impart secondary foaming power, and then steam-molded to obtain a foam product having a bulk density of approximately 0.06 f/cdl. .

The degree of compaction of the foam particles of this product was approximately 60%.

Comparative Example 1 A pond using ethylene (4% by weight)/propylene random copolymer particles containing 0.5% by weight of stabilizer as the resin particles and setting the discharge temperature of the dispersion liquid to 155°C is the same as that of Example. Foam particles were obtained in the same manner as in Example 1.

The average bulk density of the resulting polypropylene foam particles is approximately 0.
．． 05 f/d, and contained about 5% of foam particles with an expansion ratio of 2 to 3 times, and about 2% of particles with an expansion ratio of 20 to 25 times, and the particle sizes were irregular (before release). The expandable particles had absorbed approximately 4.4% water).

These foam particles were aged under pressure in the same manner as in Example 1 to impart secondary foaming power, and then steam-molded to form a 21-mm foam product with a bulk density of approximately 0.047 g/aA. It's a good deal.

The degree of fusion of the foam particles of this product was about 70%.

Example 4 Granular particles were prepared in the same manner as in Example 1, except that an ethylene (9% by weight)/propylene random copolymer was used as the ethylene/propylene random copolymer, and the dispersion temperature was set at 155°C. Uniform polypropylene foam particles were obtained.

The bulk density of the foam particles is approximately 0.045 f/crl
Met.

Example 5 Same as Example 1 except that an ethylene (quadruple is %)/propylene random copolymer containing 1.0% by weight of aluminum stearate and 1.0% by weight of glycerin monooleate was used as the resin particles. Polypropylene foam particles with uniform granularity were obtained in the same manner.

The bulk density of this foam particle is approximately 0.056 t/cT
It was l.

22- Example 6 Ethylene (quadruple breakage%)/propylene random copolymer containing 1.0% by weight of aluminum stearate, 0.5% by weight of sorbitan monooleate, and 0.2% by weight of stabilizer as resin particles. Polypropylene foam particles with uniform granularity were obtained in the same manner as in Example 1 except that polymerized particles were used.

The bulk density of the foam particles is approximately o, o52y/1-
It was tA.

Example 7 Polypropylene foam particles with uniform granularity were obtained in the same manner as in Example 6, except that polyglycerin monooleate was used instead of sorbitan monooleate.

The bulk density of the foam particles is approximately o, o s o t /c
It was tl.

Example 8 When an aqueous solution of 0.0716 parts of calcium hydroxide dissolved in 100 parts of water and 0.372 parts of an aqueous solution of 17% phosphoric acid were mixed, a salt with a particle size of 0.05 to 0.3 microns was obtained. 0.1% was precipitated (pH 9,2'). This sodium dodecylbenzenesulfonate was added to prepare the following dispersion.

Difficult water-soluble salt intensity 0.1% PH of the dispersion 9.2 Dodecylbenzenesulfonic acid concentration 0.003% After transferring 100 parts by weight of this dispersion into an autoclave equipped with a discharge nozzle at the bottom, particles 1 (1?a Ethylene (4%) with a weight of approximately 1 cm and containing 0.5% by weight of aluminum stearate and 0.2% by weight of stabilizer.
Propylene (96%) random copolymer particles (melting point 13
7℃) into the autoclave, and nitrogen gas was added into the autoclave until the internal pressure inside the autoclave was 10 kg.
/1rlG.

Next, 18 parts of butane gas was added into the autoclave with stirring, and then the dispersion was heated to 130° C. over about 60 minutes, and further maintained at the same α degree for 20 minutes. The pressure inside the autoclave at this time was about 30V4/crIG.

Thereafter, the valve of the discharge nozzle at the bottom of the autoclave was opened, and the dispersion was discharged into atmospheric pressure for 2 seconds to effect foaming. The internal pressure of the autoclave was approximately 9 Kf/cIIG at the moment when the dispersion liquid was discharged from the autoclave, in other words, at the moment when the gas phase began to be discharged. Also, during dispersion release, the temperature of the autoclave was 130°C.
Met.

The bulk density of the polypropylene foam thus obtained was approximately 0.027 f/cd. Further, no blocking between foam particles was observed.

In addition, according to differential thermal analysis, the expandable particles before release have a value of about 0.
It had absorbed 18 weights of water.

The foam particles were left in a room at 40° C. for 2 days to dry the moisture, and then placed in a sealed chamber, and air of 3~/crIG was injected for 48 hours to impart secondary foamability to the particles. .

The foam particles imparted with secondary foamability are filled into a mold cavity having steam holes, and then steam of 25-4.5 Kq/crl G is introduced into the mold cavity to perform secondary foaming, and Fusing foam particles together,
The product was then cooled to obtain a polypropylene foam product having a bulk density of about 0.025 t/cd, length 200 ym, width 300 ++l #I, and height 50 yen.

When this product was broken in half by hand and the degree of fusion of the foam particles was examined, it was found to be 70%.

Example 9 Water containing 0.3% by weight of fine aluminum oxide 10
After transferring 0 parts by weight into an autoclave equipped with a dispensing nozzle at the bottom, each particle weighs approximately 1, 160% by weight of aluminum stearate, 1.0% by weight of glycerin monostearate and stable. 33 parts of ethylene (4%)/propylene (96%) random copolymer particles (melting point 137° C.) containing 0.2% by weight of agent were added into the autoclave.

Then dichlorodifluoromethane 19 was added to the autoclave.
After adding 50% of the dispersion with stirring, the dispersion was heated to 122° C. over about 60 minutes and kept at the same temperature for an additional 26-20 minutes. At this time, the pressure inside the autoclave was approximately 331 ce/cIIG.

After that, the dispersion was heated to 130°C and kept at the same temperature for 2 hours, and then nitrogen gas was supplied into the autoclave to apply back pressure and the valve of the discharge nozzle at the bottom of the autoclave was opened to bring the dispersion to atmospheric pressure. It was released in 2 seconds to complete foaming. The internal pressure of the autoclave was approximately 21 kg/cfAG at the moment the dispersion liquid was discharged from the autoclave, in other words, the moment the gas phase began to be discharged.

The bulk density of the polypropylene foam thus obtained was approximately 0.068 f/erl. Further, no blocking between foam particles was observed.

After leaving the foam particles in a room at 40°C for 2 days to dry the moisture, they were placed in a sealed room and were heated to 3Kp/cr.
1 G of air was injected for 48 hours to impart secondary foamability to the particles.

The foam particles imparted with secondary foamability are filled into a mold cavity having steam holes, and then placed in the mold cavity at 4.5 to 9/rJ.
Guide the tG steam to perform secondary foaming,
The foam particles are fused together, then cooled, and the bulk density is approximately 0.067 t/crA, 200mm long and 300+ wide.
A polypropylene foam product with a height of 50 m and a height of 50 cm was obtained.

When this product was broken in half by hand and the degree of fusion of the foam particles was examined, it was found to be 50%.

Example 10 When an aqueous solution of 0.0716 parts of calcium hydroxide dissolved in 100 parts of water and 0.372 parts of an aqueous solution of 17% phosphoric acid were mixed, a salt with a particle size of 0.05 to 0.3 microns was obtained. 0.1% was precipitated (pH 9,2). Sodium dodecylbenzenesulfonate was added to prepare the following dispersion.

Water syneresis salt concentration 0.1% Dispersion pH 9.2 Dotecylbenzenesulfonic acid concentration 0.003% After transferring 100 parts of this dispersion into an autoclave equipped with a discharge nozzle at the bottom, the weight of one particle was The aluminum stearate content is about 1%, the glycerin monostearate content is 1.0% by weight, and the stabilizer content is 0%.
．． 33 parts of cross-linked low-density polyethylene particles (melting point 110°C) containing 1% by weight were added into the autoclave, and nitrogen gas was introduced into the autoclave until the internal pressure inside the autoclave was 10%.
It was supplied until it reached Ky/dG.

Next, the dispersion was heated to 103°C over about 45 minutes, kept at the same temperature for 20 minutes, and then heated to 120°C.
It was maintained at the same temperature for 60 minutes. The pressure inside the autoclave at this time was about zslQ/cJG.

Thereafter, the valve of the discharge nozzle at the bottom of the autoclave was opened, and the dispersion was discharged into atmospheric pressure for 2 seconds to effect foaming. The moment the dispersion liquid was discharged from the autoclave, the internal pressure of the autoclave was approximately 7 to 7/all G at the moment when the gas phase began to be discharged.

The crosslinked polyethylene foam thus obtained had a bulk density of approximately 0.046 ff/ctIl. Also,
Issue 29- No blocking between foam particles was observed.

The foam particles were left in a room at 40°C for 2 days to dry the moisture, then placed in a sealed room and heated to 2.
Air of G was injected for 48 hours to impart secondary foamability to the particles.

The foam particles imparted with secondary foamability are filled into a mold cavity having steam holes, and then 2 parts w/! G steam is introduced to perform secondary foaming, fuse the foam particles together, and then cool it until the bulk density is approximately 0.04.
ay/I:11! A crosslinked polyethylene foam product measuring 200 meters long, 300 meters wide, and 50 meters high was obtained.

When this product was broken in half by hand and the degree of fusion of the foam particles was examined, it was found to be 90%.

[Brief explanation of drawings]

FIG. 1 is a chart of differential thermal analysis of the resin. Patent Applicant Yuka Bardatesier Co., Ltd. Agent Patent Attorney Hidetoshi Furukawa Agent Patent Attorney Masahisa Hase 30-

Claims (1)

[Claims] 1) In a closed container, polyolefin resin particles containing 0.4 to 10% by weight of metal salts of higher fatty acids having 12 to 22 carbon atoms are dispersed in water. The particles are heated to a temperature higher than the softening temperature and lower than 25°C higher than the melting point to absorb water, and then the discharge port provided below the water surface in the sealed container is opened, and the polyolefin resin particles and the dispersion medium are heated. A method for producing polyolefin resin foam particles by simultaneously releasing certain water into an atmosphere at a lower pressure than the inside of the container. 2) In a sealed container, a) 4 to 10% by weight of a metal salt of a higher fatty acid having 12 to 22 carbon atoms and b) an alcohol selected from glycerin, sorbitan, and polyglycerin and a higher fatty acid having 12 to 22 carbon atoms. Sail esters with higher fatty acids05
Polyolefin resin particles containing ~5% by weight are dispersed in water, heated to a temperature above the softening temperature of the resin particles and below a temperature 25°C higher than the melting point to allow the particles to absorb water, and then placed in a closed container. A method of manufacturing polyolefin resin foam particles by opening a discharge port provided below the water surface of the container and simultaneously releasing polyolefin resin particles and water as a dispersion medium into an atmosphere at a lower pressure than the inside of the container. 3) The method for producing polyolefin resin foam particles according to claim 1 or 2, wherein the metal salt of higher fatty acid is aluminum stearate or zinc stearate. 4) The method for producing polyolefin-based one-fat foam particles according to claim 2, wherein the ester is glycerin monostearate.