JPS5876228A - Polypropylene synthetic resin foamed and molded body - Google Patents

Abstract

PURPOSE:To improve the mechanical strength, by fillig a mold, which can be closed, but not be tightly closed, with polypropylene resin prefoamed particles, and heating the prefoamed particles to be molded into a body having a density of 0.06-0.3g/cm<3>, and a cell membrane thickness of 1-50mu. CONSTITUTION:The prefoamd particles are produced by incorporating 5- 30pts.wt. volatile foaming agent into 100pts.wt. polymer such as ethylene/propylene random copolymer, propylene monopolymer, etc. As said volatile foaming agent, aliphatic hydrocarbons such as propane, butane, etc. and cycloaliphatic hydrocarbons such as cyclobutane, etc. can be used. The prefoamed particles are matured at normal temperature under normal pressure, and then are matured under pressure to be provided with an internal pressure of 0.3-5kg/cm<2>G, and the mold, which can be closed, but not be tightly closed, is filled with the prefoamed particles, and the preforamed particles are heated and expanded using steam of 2-5kg/cm<2>G to obtain a molded body having a density of 0.06-0.3g/ cm<3>, and a cell membrane thickness of 1-50mu.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polypropylene synthetic resin foam molded article.

Molded products obtained by filling pre-expanded particles into a mold that can be closed but not sealed and heated to foam the particles are known. mm, packaging material.

It is used for insulation materials, construction materials, etc., and in the case of @high-density foam, it is used for packaging materials for heavy items, structural materials, building materials, vehicle components, etc. that require relatively high mechanical strength. expected to be suitable. Conventional.

Moldings made of foamed polystyrene have been used as foam moldings, but they have the fatal drawback of being brittle and have poor chemical resistance, and improvements to these problems have long been desired. A molded body made of crosslinked polyethylene foam was proposed as a solution to the drawback of sagging. However, this foamed polyethylene molded product has a drawback in that it has low mechanical strength such as compressive strength, which is required for structural and building materials.

The present invention provides a new polypropylene-based synthetic resin foam molded product that eliminates the drawbacks of the above-mentioned conventional technology.As a result of intensive research to obtain a foam molded product with high mechanical strength,
The present inventors have discovered that a polypropylene synthetic resin foam molded product having a certain density and cell thickness has good properties, and has completed the present invention.

That is, the present invention provides a molded article obtained by filling a mold that can be closed but not sealed with pre-expanded particles and foaming the particles by heating, the molded article being made of a polypropylene synthetic resin foam. r, s degree 0.06-0.3 g/d,
The gist is a polypropylene-based synthetic resin foam molded product characterized by a cell membrane thickness of 1 to 50 microns.

In obtaining the polypropylene synthetic resin foam molded product of the present invention, high-density pre-expanded particles are used, and the properties of the pre-expanded particles include ethylene-propylene random copolymer, ethylene-propylene block copolymer, etc. polymer,
Examples include propylene alone and monomer, and these may or may not be crosslinked, but non-crosslinked ones are particularly useful. Among the above-mentioned polymers, ethylene-propylene di-random copolymer is preferable, and * has an ethylene component of 0.5 to 10
Heavy weight copolymers are preferred.

The high-density polypropylene synthetic resin pre-expanded particles used in the present invention can be produced, for example, by the following pre-expanding method. Namely.

A step of incorporating a volatile blowing agent into the polymer particles.

A step of dispersing the polymer particles in a dispersion medium and heating them to a predetermined temperature in a closed container, and opening one end of the container.

It can be produced by a pre-foaming method comprising a step of releasing the particles and dispersion medium into the same FrfK container under a low pressure atmosphere.

Volatile blowing agents used in this method include aliphatic hydrocarbons such as propane, butane, pentane, hexane, heptane, etc., cycloaliphatic hydrocarbons such as cyclobutane, cyclopentane, etc., and trichloro Chloromethane, dichlorosifu-promethane, dichlorothidrafluoroethane.

Halogenated hydrocarbons such as methyl chloride, ethyl chloride, methylene chloride, etc. are used. The amount of the blowing agent added is usually 5 to 30 parts by weight per 100 parts by weight of the polymer particles.

In this method, the polymer particles and the volatile blowing agent are separated into KII1.
．． Alternatively, a volatile blowing agent is incorporated into the polymer particles and then dispersed in a dispersion medium. At this time, if necessary, a dispersant 2 such as finely divided aluminum oxide and titanium oxide, basic magnesium carbonate, basic zinc carbonate, Calcium carbonate can be used. The amount of this dispersant added is usually 0.01 to 10 parts by weight per 100 parts by weight of the polymer particles. The dispersion medium may be any solvent that does not dissolve the polymer particles.
Examples include water, ethylene glycol, glycerin, methanol, ethanol, etc., or a mixture of two or more thereof, but water is usually preferred.

In this method, one end of the container is opened and the polymer particles and dispersion medium are simultaneously discharged into the container into a low-pressure atmosphere.
The pressure inside the container at this time may be either higher than or lower than the volatile blowing agent Os atmospheric pressure.

The atmosphere to be released is usually an atmosphere of normal pressure.

The high v obtained by doing K like this! i degree pre-expanded particles are 1
At the time of foaming, it has an apparent expansion ratio of 0Il1 degree, pressure 1, amount of blowing agent, etc., but usually 3 to 20 times.

Next, the pre-expanded particles are aged at room temperature and pressure, and then aged under pressure. Pressure aging is usually carried out using an inorganic gas or a mixed gas of an inorganic gas and a volatile blowing agent at a rate of 0.3 to 8 ky/m (G
) for 3 to 72 hours, thereby adding 0.3 to 5 kg/cd (G), preferably 3
An internal pressure of ky/d (G) or less is applied. As the inorganic gas, air, nitrogen, argon, -\lium, etc. are used.

The pre-expanded particles are subjected to internal pressure as described above.

A mold that can close the particles but cannot be sealed, for example, a mold having small holes in the mold surface through which a heating medium of steam can pass, is filled with steam of 1 to 5 ky/cj (G), for example. By heating and expanding the polypropylene-based synthetic resin foam molded product of the present invention, a polypropylene-based synthetic resin foam molded product of the present invention is obtained.

The polypropylene synthetic resin foam molded product of the present invention obtained by K as described above has a density of 0.06 to 0.3 I/-2
The bubble film thickness is 1 to 50μ. Density is 0.06117d
If it is less than 1, the mechanical strength of the foamed molded product is too low to be used for, for example, structural materials, building materials, etc.

If K exceeds o, sl/d, the weight of the foamed molded product increases, 1. It is difficult to reduce the amount of abrasion, which is an advantage of foamed products, and 2. the surface protection property is not sufficient. The preferred range of direction and density is 0.
07-0.1. p/cIl. Also, the bubble film thickness is 1μ
If it is less than 50 μm, the molded product will not have sufficient flexibility (it is weak and will easily break due to bending), and if it exceeds 50 μm, the surface protection will be significantly impaired.

For example, when used as a packaging material, there is a risk of damaging the product.

The polypropylene synthetic resin foam molded product of the present invention can be used, for example, in packaging materials, cushioning materials, structural materials, MS, vehicle parts, etc. In particular, packaging materials for heavy items that require mechanical strength, and core materials for bags. Structural materials such as

It can be effectively used for building materials such as heat insulating materials, and vehicle components such as core materials for automobile doors, ceilings, and seats.

As explained above, the polypropylene synthetic resin foam molded product of the present invention having a specific density and cell thickness has a compression hardness and flexibility (resilience) of 4! The mechanical strength of
It also has good surface protection properties and is particularly useful when used, for example, in packaging materials for heavy objects, structural materials, building materials, vehicle parts, etc., which require relatively high mechanical strength.

Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Examples 1 to 3 and Comparative Examples 1 to 5 Ethylene-propylene random ux combined particles <:r-straw tyrene component weight%) iooxi part, dichlorodifluoromethane 5 to 50 parts by weight, fine particulate aluminum oxide 0.3x
parts and 300 parts by weight of water were placed in a closed container and heated to 135-150° (7°C) while stirring to incorporate dichloroschif-p-methane into the particles.

Then, the pressure inside the container k 20 ms o, ky/cj (
G) While retaining K, polymer particles and water were simultaneously released into the atmosphere and dried to obtain pre-expanded particles. Similarly, dichlorodifluoromethane was tested using the above-mentioned method with various changes. The obtained pre-expanded particles are placed in a pressurized container,
Fill a mold with the ridge and pre-expanded particles that have been pressurized and aged in air at 2 kg/m (G) for 100 hours to give internal pressure; 3.
The foam was expanded by heating with water vapor at 5 to 5 kg/c#1 (G) to obtain a foam molded product having the density and cell thickness as shown in Table 1. Compression wave 62 surface integrity and flexibility tests were conducted on each of the foamed shields obtained. The results are shown in Table 1.

Table 1 *1 - Measurement of compression hardness was performed according to JIS K6767. -: Evaluation is ◎ if it is 9 yu/cIi or more, and × if it is 2 y/cIi or more and 9 y/cIi or less and less than 0.2 y/cIi.

*2-Surface retention test is conducted by friction with hard decorative board.i*3-Flexibility test is 9 in accordance with NDS z0503.
0" bend.

Claims (1)

[Scope of Claims] A molded article obtained by filling a mold that can be closed but not sealed with pre-expanded particles and foaming the particles by heating, the molded article being made of polypropylene synthetic resin foam. The density is 0.06 to 0.3 N/all. ft11 [A polypropylene-based synthetic resin foam molded product characterized by having a thickness of 1 to 50 μm.