JPH01242638A - Expanded propylene resin particle and expanded molding - Google Patents

Abstract

PURPOSE:To improve the mechanical strength of a molding, by heating an aqueous dispersion of specified propylene/1-butene random copolymer particles and a volatile inflating agent in a sealed vessel and releasing the mixture into an atmosphere of a pressure lower than that in the vessel. CONSTITUTION:100 pts.wt. particles (A) (of the weight of 0.01-20mg) of a propylene/1-butene random copolymer of a latent heat of crystallization of 17-29cal/g and a 1-butene content of 3-12, desirably, 4-10wt.%, are dispersed in 150-1000 pts.wt. water (B) in the presence of a dispersant (e.g., calcium terti ary phosphate) in a sealed vessel and 10-50 pts.wt. volatile inflating agent (C) (e.g., butane) is added to the mixture. The resulting mixture is heated to a temperature ranging from the softening point of component A to a temperature at least 20 deg.C higher than its melting point and discharged into an atmosphere of a pressure lower than that in the vessel to obtain the title particles of a bulk density of 8-100kg/m<3>. These particles are packed in the cavity of a mold equipped with a steam inlet and heated with steam to obtain an expanded molding.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to expanded propylene copolymerized resin particles. The foamed molded article obtained by filling the foamed particles of the present invention into the cavity of a mold having steam holes and heating them with steam to fuse the foamed particles together has strong fusion between the foamed particles, It has excellent mechanical strength and is useful as a heat insulating material for filtered spring piping, a heat insulating material for solar water heaters, a heat insulating material for wall materials and flooring materials, and a packaging material for refrigerators and televisions.

[Conventional technology]

Polystyrene foam is used in a wide range of fields as insulation and packaging cushioning materials. However, this polystyrene foam has a low compression strain recovery rate and a heat resistance of only 70%.
~80°C, and oil resistance and impact resistance are poor.

Propylene-based resin foam particles have been proposed to improve this drawback (Japanese Patent Publication No. 49-2183, JP-A No. 57-90027, JP-A No. 57-195.131,
No. 58-1732, No. 5B-z3834, No. 58-
No. 25334, No. 58-33435, No. 58-552
No. 31, No. 58-76229, No. 58-76231, No. S8-7f3232, No. 58-76233, No. 58-76234, No. 58-87027, No. 462-
No. 151325).

Among propylene-based resin foam particles, foamed particles based on homogeneous polypropylene use high-pressure steam (high-temperature steam) to fuse the foamed particles together during in-mold molding, so the ethylene content is 1 to 1. Pre-expanded particles using 20% by weight ethylene-propylene random copolymer as the base resin have been proposed (Japanese Patent Publication No. 59-23731).
.

This product has the advantage that it can be molded using steam at a lower pressure than those using homopolypropylene or ethylene random block copolymer as the base resin.

[Problem to be solved by the invention]

These propylene resins are produced by dispersing propylene resin particles in water in a closed container, then supplying a volatile organic expanding agent into the closed container, and increasing the pressure inside the closed container to the vapor pressure of the expanding agent or higher. After heating above the softening temperature of the propylene resin particles while maintaining the pressure at Expanded propylene resin particles are produced by simultaneously releasing the propylene resin particles and water into an atmosphere at a lower pressure than the inside of the container (see the above-mentioned patent publications).

In this method for producing foamed propylene resin particles, in order to obtain foamed particles with the same expansion ratio, the filling rate of water, resin, etc. into the container (the volume ratio of the contents used for the reaction to the volume inside the closed container) When are the same, ethylene-propylene random copolymer, which has a lower resin melting point, requires lower heating temperature than homopolypropylene or block copolymer, so the internal pressure of the sealed container is also lower, and the pressure-resistant strength design of the sealed container is improved. The coefficient of can be made small.

Even among ethylene-propylene random copolymers of the same crystallinity, a copolymer with a higher ethylene content is preferable in terms of foamability and moldability because the copolymer has a lower melting point.

However, molded articles (e.g. bumper core material; JP-A-58-2013
-221745)), the foaming ratio of the molded product should be lowered.
No. 660) or an ethylene/propylene random copolymer with a low ethylene content must be used as the base resin.

Now, taking the bumper core material as an example, reducing the foaming ratio (increasing the density) of the molded object (bumper core material) is not desirable in terms of vehicle design because it increases the weight of the bumper core material.

On the other hand, if an ethylene-propylene random copolymer with a low ethylene content is used as the base resin, the melting point will be high, so as mentioned above, it is necessary to increase the pressure resistance of the closed container in which expanded particles are manufactured and raise the operating temperature. There is. Furthermore, it is disadvantageous in terms of economic implementation, such as equipment and utility, as it increases the mold clamping force of the molding machine that heat-fuses the expanded particles.

(The cells of the resulting foamed particles become too fine, and the fusion of the foamed particles during molding becomes poor.

On the other hand, JP-A-60-110734 discloses propylene 1-butene with a content of 15 to 40 mol% (19 to 47% by weight), a latent heat of crystal of 5 to 15 cai), /t.
Pre-expanded particles of butene copolymers are described.

The purpose of this is to apply internal pressure to the pre-expanded particles using pressurized air, fill them into a mold, and heat them in the mold to cause secondary foaming to obtain a foamed molded product. There is no disclosure of knowledge for improving the mechanical strength of the molded body, except for reducing the temperature.

This propylene with a 1-butene content of 15 to 40 mol%
1-Butene random copolymer has a latent heat of crystallization of 5 to l5
As can be understood from the low can/f, since it has many amorphous parts, the molding temperature can be lowered, but the effect of improving the compressive strength of the resulting molded product is small.

The present invention is capable of producing expanded particles and heat-sealing the expanded particles using existing equipment and at a relatively low temperature or low pressure, and that the molded article obtained by heat-sealing the expanded particles can be produced using existing equipment. To provide expanded particles having excellent compressive strength.

[Specific means to solve the problem]

In the present invention, by setting the 1-butene content to 3 to 12% by weight, preferably 4 to 10% by weight, and using a highly crystalline ipropylene/1-butene random copolymer as the base resin, the foaming temperature and shape can be adjusted. The steam pressure (degrees) during molding can be lowered, and the compressive strength of the resulting molded product has also been improved.

That is, the present invention provides foamed propylene-based resin particles having a propylene/l-butene random copolymer as a base resin, wherein the 1-butene component in the copolymer is 3 to 12% by weight. The present invention provides foamed propylene resin particles with characteristics.

co(7)propylene-1-butene random copolymer 1
-Butene content is determined by heat pressing the copolymer particles to 190%.
A sheet with a thickness of 0.5 ms was obtained by applying a pressure of zw/dG for 1 minute at ℃, and the sheet was left at 20 ℃ for 1 day.The sample was obtained by infrared absorption spectrum analysis.

The latent heat of crystallization was determined by heating and melting Samples 3 to 8 at 240°C using a differential scanning calorimeter (DSC), and then cooling to 30°C at a cooling rate of 10°C/min. The exothermic energy generated during oxidation was determined from the peak area on the DSC chart.

The 1-butene content of the copolymer is from 3 to 12% by weight, preferably from 4 to 10% by weight. 1-butene content is 3 times 1
If the amount of copolymer is less than 9%, the cells of the foam become fine and the melting point becomes high, so that the heating temperature or heating pressure for producing expanded particles and heat fusing the expanded particles becomes too high.

If the 1-butene content exceeds 12% by weight, the compressive strength and heat resistance of the molded article will be poor.

As the α-olefin copolymerizable with propylene, l
-In addition to butene, ethylene, hexene-1, pentene-1
Although there are many variations, it seems that 1-phthene has a crystal structure similar to that of propylene in the copolymer, and therefore, the crystal stability is also presumed to be high.

The latent heat of crystallization of the base resin of the conopropylene/1-butene random copolymer is 17 to 29 can/y, preferably 17 to 25 caK/P, and the bulk density of the expanded particles is 0.0
15~0.090 t/cd, preferably 0.030~
It is 0.070 f/al.

If necessary, the propylene/1-butene random copolymer may be blended with other polyolefin resins in an amount not exceeding 50% by weight. For example, homopolypropylene, ethylene-propylene random copolymer, ethylene-propylene block copolymer, ethylene-propylene rubber, ethylene-propylene-1-butene random copolymer, high-pressure process low density polyethylene, linear process low density polyethylene. Polyethylene, medium/high density polyethylene, ethylene/vinyl acetate copolymer & vinyl acetate copolymer, ethylene/methyl acrylate copolymer, ethylene/ethyl acrylate copolymer, ethylene/acrylic acid copolymer, etc. may be added. .

Furthermore, the resin may contain inorganic fillers such as zeolite, silica, and talc, pigments, heat stabilizers, dyes, lubricants, and antistatic agents. These should be at most 5% by weight, preferably at most 2% by weight, in order to achieve good fusion when foamed particles are heated with steam to fuse them together to form a molded article.

The weight of one propylene/l-butene random copolymer particle is 0. O1 to 20111F. Granulation may be carried out by any method such as a strand cutting method, an underwater cutting method, a sheet cutting method, a freeze-pulverization method, a melt-spraying method, etc., and the method is determined in consideration of productivity, economic efficiency, formability, and quality. In addition, regranulation may be performed.

Expanded propylene/1-butene random copolymer particles are produced according to the methods described in the aforementioned patent publications.

Example: EVA, propylene/l-butene random copolymer particles are dispersed in water in a sealed container, and then a volatile swelling agent is supplied into the sealed container, which is higher than the softening point of the resin particles and 20°C higher than the melting point. After heating the dispersion to a temperature below the temperature, a discharge port provided below the water surface in the sealed container is opened, and the aqueous dispersion containing the resin particles impregnated with the swelling agent is heated to a temperature lower than the pressure in the sealed container. Produced by discharging into an atmosphere of pressure (into the atmosphere). During this production, it is preferable to pressurize with air or nitrogen gas to facilitate release.

Examples of volatile swelling agents include aliphatic hydrocarbons such as propane, butane, pentane, hexane, and heptane; trichlorofluoromethane, dichlorodifluoromethane, dichlorotetrafluoroethane, methyl chloride, ethyl chloride, methylene chloride, - Organic compounds having a boiling point of 80° C. or lower, such as logenated hydrocarbons, can be used alone or in combination of two or more.

The amount of the volatile swelling agent added varies depending on the type of 21IMl agent and the bulk density of the intended resin particles, but is usually 10 to 50 parts by weight per 100 parts by weight of the resin particles.

Examples of dispersants for dispersing resin particles in water include inorganic suspending agents such as aluminum oxide, titanium oxide, calcium carbonate, basic magnesium carbonate, and tribasic calcium phosphate; polyvinyl alcohol, methyl carboxyl cellulose, N
- Water-soluble polymeric protective colloid agents such as polyvinylpyrrolidone; ionic interfaces such as sodium dodecylhensensulfonate, sodium alkanesulfonate, sodium alkyl sulfate, sodium olefin sulfate, acylmethyltaurine, sodium dialkylsulfosuccinate, etc. Examples include activators and the like. Among these, it is preferable to use a combination of tricalcium phosphate having a particle size of 0.01 to 0.8 microns as an inorganic suspension agent and sodium dotecylbenzenesulfonate as a suspension aid. This fine tricalcium phosphate is obtained by reacting phosphoric acid in water at a ratio of 0.60 to 0.67 mol per mol of calcium hydroxide.

The amount of water used as a dispersion medium per part of 10011L of resin particles is 150 to 1,000 parts by weight, preferably 200 to SOO.
Parts by weight. If the amount is less than the iso weight part, the resin particles tend to block each other during heating and pressurization.

If it exceeds 1,000 electric arc parts, the productivity of foamed particles will decrease and it will be uneconomical.

A gaseous or liquid swelling agent is supplied to an aqueous dispersion of propylene/1-butene copolymer resin particles dispersed in water by a dispersion medium, and this aqueous dispersion softens the resin in a closed container. The copolymer particles are heated to a temperature above the melting point and below 20°C higher than the melting point, and the pressure inside the container increases due to this heating, and the swelling agent is impregnated into the copolymer particles. Propylene with a bulk density of 8 to 100Af/i is released by discharging the copolymer resin particles together with water from a closed container into a low pressure region (generally at atmospheric pressure) through a discharge port such as a slit or nozzle provided at the bottom. 1-Butene random copolymer expanded particles can be produced.

In the production of expanded particles, before or after the expansion agent is added into the closed container, an inorganic gas such as nitrogen, helium, air, etc. is supplied into the closed container to apply pressure.

This inorganic gas may be supplied before or after heating the dispersion.

Supplying an inorganic gas such as air, nitrogen gas, or argon into the closed container facilitates impregnation of the expanding agent into the resin particles, and is useful for obtaining propylene/1-butene copolymer foam particles having a low bulk density.

The heating temperature of the dispersion liquid is determined by determining the peak of crystal melting temperature (so-called melting point) using a differential scanning calorimeter for propylene/1-butene copolymer resin particles, and is approximately 20°C from this peak temperature.
A temperature between a low temperature as a lower limit and a temperature 20° C. higher than this peak temperature as an upper limit, preferably a temperature 3 to 15° C. lower than this peak temperature may be selected.

The time for which the dispersion is kept in a closed container depends on the pressure applied, the holding temperature, and the desired expansion ratio, but it is from 30 minutes to 12 minutes.
time, preferably 1 to 3 hours.

The foamed particles released into the atmosphere are dried (cured) in a room at 30 to 65°C to remove water attached to the surface.
Allotted for molding cushioning materials, containers, etc.

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

■ After filling the foamed particles of fluorolene/1-butene random copolymer into a mold, the foamed particles are compressed to reduce their volume by 15 to 50%, and then steam of 1 to 5 ky/dG is introduced to cause the foamed particles to combust. fused, then cooled the mold,
Compression molding method to obtain the product (DO821076g No. 3).

■1 Fill a mold with pre-expanded particles, which have been pre-impregnated with a volatile liquid expanding agent to give the expanded particles secondary foamability, and heat them with steam to cause secondary foaming and fuse the particles together. Get the product by wearing it.

■1 The foamed 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 foamed particles and give them secondary foamability. The applied pre-expanded particles are filled in a stirrer, heated with steam, and subjected to secondary foaming, and the particles are fused together to obtain a product (so-called pressure ripening method; Japanese Patent Publication No. 59-237
No. 31).

■1 In a method of molding a molded foam by filling a mold with foamed particles and fusing the foamed particles with each other by steam heating, the pressure inside the mold is increased to 1.0~e, ot4/-G with pressurized gas. Then, the foamed particles were heated to 5t4 from the pressure inside the mold.
While compressing using a pressurized gas with a pressure higher than 7- or more, the mold is filled sequentially by dividing it into multiple times, and during the filling, the pressure inside the mold is maintained at the above-mentioned inside pressure, and then after the filling is completed, the inside of the mold is filled. After returning the pressure to atmospheric pressure, the above-mentioned heating is performed to fuse the foamed particles to each other, and the foamed particles have the following formulas:

W...Weight of the molded product (f) ■...Capacity of the molded product<1) σ...Bulk density of expanded particles in the atmosphere (1/1))
In-mold molding method for foamed particles characterized by controlling the compression rate expressed by 40 to 70%
No. 25).

(2) A method in which a mold is filled with propylene/l-butene random copolymer foamed particles and the foamed particles are fused together by steam heating to form a molded foam. The above-mentioned mold was given a gas internal pressure obtained by pressurizing it for more than 1 hour using a pressurized gas higher than the indoor pressure by 0.5 t4/- or more in advance in a mold pressurized to 0 kg/-G. The foamed particles are sequentially filled in multiple times using a pressurized gas with a pressure higher than the pressure inside the mold by 0.5 g/, -j or more, and during the filling, the pressure inside the mold is The pressure is continued to be maintained at the same pressure, and then after filling is completed, the pressure inside the mold is returned to atmospheric pressure, and then the above-mentioned heating is performed to fuse the foamed particles. Each represents the following.

W...Weight of the molded product (f) V...Volume of the molded product t (t) σ...Bulk density of expanded particles in the atmosphere (, f/l)
) An in-mold molding method for propylene/1-butene random copolymer foam particles, characterized in that the compression ratio is controlled to less than 40% (excluding 0%).

The propylene/l-butene copolymer foam product molded in this manner has excellent fusion of the foamed particles and has high mechanical strength.

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

Example 1 1-butene content is 6.0% by weight, MFR measured at 230°C is a, sr/lo min, and latent heat of crystal is 19.6 car.
Expanded particles were obtained using propylene/1-butene random copolymer particles of t/l (average weight of one particle was about 1111F).

That is, in a closed container, 250 parts of water, 100 parts of the above propylene/l-butene copolymer particles, and a particle size of 0.3-0.
1.0 part of 5 micron tricalcium phosphate and 0.007 part of sodium dodecylbenzenesulfonate were charged (filling rate 62%), and then nitrogen gas was pressurized under stirring until the internal pressure of the sealed container was 5 kg/clIG. The supply of nitrogen gas was stopped. Next, 18 parts of inobutane was supplied into a sealed container, heated to 132°C over 1 hour, and heated to 45°C at the same temperature.
After holding for a minute, the autoclave internal pressure was 24#/c.
jG was shown.

Then, open the discharge nozzle valve at the bottom of the sealed container,
The dispersion was discharged into atmospheric pressure for about 2 seconds to effect foaming. The internal pressure of the sealed container at the moment when the final portion after dispersion is released from the sealed container is approximately i.

It was n/cdG. Additionally, the temperature of the closed container was maintained at 132° C. during the fraction release.

The propylene/l-butene copolymer foam particles thus obtained have a bulk density of 30 #/n? , particle l 3.
3 m, and the foam cell diameter was 150 microns.

Further, no blocking between foamed particles was observed.

After leaving the foamed particles in a room at 40°C for 2 days to dry them, they were filled into a chamber with steam holes, the foamed particles were compressed by 50%, and then 30#/-G steam was introduced to expand the foaming. Particles were heated and fused together, then water-cooled for 10 seconds, 3
After cooling for 0 seconds, the molded product is cut out from the mold and the density is 60k.
A molded article with f/, l, 150 m in length, 300 m in width, and 12.5 m in thickness was obtained.

The compressive strength of this molded article was evaluated by the following measuring method and was found to be 6.3#/-.

Density is 60IS/-, sample size is 50 meters x 50 holes
A test piece of 50I111I was compressed by a method according to JIS-6767, and the compressive strength when the compressive strain was 50% (20
(measured in °C).

Examples 2 to 3, Comparative Examples 1 to 5 Using the resin shown in Table 1 as the resin particles, the temperature of the closed container was changed so that the bulk density of the expanded particles was 30 ky/nl, and the internal pressure inside the closed container was also changed. Example 1 except that the steam pressure was used to fuse the foamed particles together (different), and the steam pressure was used to fuse the foam particles together
In the same manner as above, a molded article having a density of 60'i/rrl was obtained.

The results shown in Table 1 were obtained.

In addition, in Table 1, the evaluation of the degree of foaming S is the heating holding temperature in a closed container to obtain expanded particles with a bulk density of 30 cape/- when operating under the charging conditions (filling rate) of Example 1. .

Also, the molding tolerance is the minimum steam pressure required to obtain a superior molded product.

(Left below) Procedural amendment (spontaneous) January L6, 1999 1, Indication of case 1988 Patent Application No. 70186 2
Name of the invention Relationship to the propylene-based resin foam particles and foamed molded product lambda correction case (Patent applicant) Address 1000 Yojiri-cho, Yokkaichi City, Mie Prefecture Name Mitsubishi Yuka Verdice Co., Ltd. Representative Masaru Isono Iomote Agent address: Mitsubishi Yuka Co., Ltd., 2-5-2 Marunouchi, Chiyoda-ku, Tokyo Telephone: (θ3) 283-5597 5. Number of claims increased by amendment: 06, Subject of amendment 1), No. 20 of the specification In the 8th line of the page, the statement "...compressed, compression distortion..." is corrected to "...compression speed: 1011 m+/min), compression distortion...".

2) After the end of page 22 of the specification, the following examples 4-
7. Insert the sentences of Comparative Examples 6 to 9.

“Example 4 M with a 1-butene content of 5.2% by weight, measured at 230°C
FR is c+, 7r/lo min, latent heat of crystal is 22.6can
Expanded particles were obtained using propylene/1-phytene random copolymer particles of /P (the average weight of each particle was about 1 pc).

That is, in a closed container, 250 parts of 1 water, loo part of the above propylene/1-butene copolymer particles, 1.0 part of calcium pyrophosphate, and 0.0 parts of sodium dodecylbenzenesulfonate are placed in a closed container.
007 parts were charged (filling rate: 62%), and nitrogen gas was then pressurized under stirring until the internal pressure of the closed container became 5 Ay/clIG, and the supply of nitrogen gas was stopped. Next, 18 parts of inobutane was supplied into a sealed container and heated to 140°C for 1 hour.
When the autoclave was heated to a temperature of 45 minutes and maintained at the same temperature for 45 minutes, the internal pressure of the autoclave was 26#/iG.

Then, open the discharge nozzle valve at the bottom of the sealed container,
The dispersion was discharged into atmospheric pressure for about 2 seconds to effect foaming. The internal pressure of the sealed container at the moment the final portion after dispersion is released from the sealed container is approximately 10#/1M! It was G. Additionally, the temperature of the closed container was maintained at 140° C. during dispersion release.

The thus obtained foamed globylene/l-phytene copolymer particles have a bulk density of 30A? /? P/, particle size 3.
3. The foam cell diameter was 150 microns.

Further, no blocking between foamed particles was observed.

The foamed particles were left to dry for 2 days at 40°C, then filled into a mold with steam holes, the foamed particles were compressed by 50%, and then steam of s, oi57iG was introduced to form the foamed particles. After heating and fusing the comrades, cooling with water for 10 seconds and cooling for 30 seconds, the molded product is removed from the mold and the density is 0.
．． A bumper core material of 062 t/ed, 1500 m long, 200 m wide, and 150 m thick was obtained.

From this bumper core material, the length is 80 m, the width is 801 m, and the height is 50 m.
Cut out a test piece of 20°C and calculate the stress/strain curves at 20°C and 80°C.
The energy absorption ratio at 0°C was determined.

Examples 5 to 7, Comparative Examples 6 to Polypropylene resins shown in Table 2, namely: - Propylene/butene-1 random copolymer (BPF) - Propylene/ethylene random copolymer (EPF) - Propylene/ethylene block A bumper core material having the physical properties shown in Table 2 was obtained according to Example 4 using the copolymer (EPB).

Claims (1)

[Scope of Claims] 1) Propylene-based resin foam particles having a propylene/1-butene random copolymer as a base resin, wherein the 1-butene component in the copolymer is 3 to 12% by weight. Propylene-based resin foam particles characterized by the following. 2) The propylene resin foam particles according to claim 1, wherein the propylene/1-butene random copolymer as the base resin has a latent heat of crystal of 17 to 29 cal/g. 3), density is 0.015-0.09g/cm
A molded article made of a propylene/1-butene random copolymer of ^2.