JPS6085919A - Manufacture of polyolefin series resin foam - Google Patents

Abstract

PURPOSE:To obtain polyolefin series resin foam in closed-cell structure having a uniform fine bubble diameter without being influenced by a variation of a quantity of a foaming agent and a foaming modifier and terms at the time of extrusion foaming, by making use of sodium bicarbonate and tarter acid as the foaming modifier. CONSTITUTION:As for a foaming modifier, sodium bicarbonate and tartar acid especially the tartar acid whose mean particle diameter is 5-100mum are used. As for loading, 0.1-5wts.pt. sodium bicarbonate and 0.1-0.5wts.pt tartar acid to 100wts.pt. polyolefin series resin are desirable. Polyolefin series resin foam is manufactured by a method wherein a mixture obtained by loading and mixing the foaming modifier to the polyolefin series resin is supplied to an extruder beforehand, molten and plasticized through heating the same at a temperature of more than the softening point of the polyolefin series resin, and then kneaded further by loading as a foaming agent liquidized dichloro-tetrafluoroethane obtained through pressing, which is extruded within the open air at discharge pressure of more than the critical pressure of the dichloro-tetrafluoroethane.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing polyolefin resin foam by extrusion foaming.

Conventionally, polyolefin resin foams have been widely used as cushioning materials in industrial materials and the like due to their closed cells and flexibility.

Generally, polyolefin resin foam is manufactured by mixing a volatile blowing agent or gas into polyolefin resin and extruding it (foaming foam C), but since polyolefin resin is a crystal, the cell diameter is small. It is easy to adjust, for example, to make the bubble diameter small and uniform, talc,
It has been produced by adding inorganic substances such as silica and sodium bicarbonate, and foam regulators such as organic acids such as stearic acid and salts thereof. Alternatively, in order to further reduce the cell diameter, the use of a thermally decomposable chemical blowing agent such as azodicarboxylic acid amide as a cell control agent is also being considered.

However, with such a foam control agent, the discharge rate is close to the critical pressure of the volatile foaming agent. Compared to a foam obtained by crosslinking with an electron beam or an organic peroxide using a C pyrolytic chemical blowing agent and avoiding foaming, the cell diameter is larger and the appearance and beauty are inferior.

In addition, the bubble diameter is affected by conditions such as the m of the foaming agent and the discharge pressure, and if these changes even minutely during extrusion foaming, the bubble diameter of the foam will change significantly, and the desired thickness and A appearance will be affected. The drawback was that it was difficult to obtain. Furthermore, in order to correct variations in the cell diameter of the foam, it is possible to increase or decrease the amount of cell control agent depending on individual factors, but this is complicated and requires highly accurate addition equipment. There was also a drawback.

The chain of defective products produced in the time it took to obtain a foam with the target cell diameter became enormous.

On the other hand, talc has a small change in the size of the bubbles due to changes in the amount of blowing agent added, but this is because when the discharge pressure is close to the critical pressure of the blowing agent, the bubble diameter is large at around 1 tm. Even under condition C, where the discharge pressure was 20 to 30 kg/cl higher than the critical pressure, the lower limit of the bubble diameter was 0.5 to 1 μm. If the amount of talc added is increased in order to make the cell diameter smaller than this, the closed cell structure is lost and the appearance also deteriorates.

The inventors of the present invention have carried out intensive research in order to eliminate these various drawbacks.1 As a result, a certain combination of foam regulators has been found to be effective in reducing the suspension and pressure horn of foaming agents and foam regulators. By making the bubble diameter very small and uniform regardless of fluctuations, and making the bubble diameter uniform and constant to the optimum size for producing low-density foam, the foam has extremely small fluctuations in the foam's height and an improved appearance. It has been found that a foam with good r(!1) can be obtained.

The present invention was made based on this knowledge.The object of the present invention is to create uniformly small cells with a uniform diameter without being affected by the amount of blowing agent or cell control agent or the size of the strips during extrusion foaming. The purpose of the present invention is to produce a polyolenoin resin foam having a closed cell structure.

1. The method for producing a polyolefin resin foam according to the present invention includes polyolenoin-based 4T1 resin, DIKU-U-RUTE as a blowing agent, and Uff as a foam regulator.
(i) Sodium carbonate and tartaric acid are supplied to an extruder, kneaded under conditions of a temperature higher than the softening point of the polyolenoin resin and a predetermined pressure, C-dissolved and plasticized, and then extruded into a low-pressure zone (r) to foam. do.

In the present invention, the polyolefin resins include low density polyethylene, high density polyethylene, polypropylene,
Dilene-pyrene copolymer, tyrene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, etc. are preferably used, and these can be used alone or as t iIN Combined C may be used.

In the present invention, 1 rutetrafluoroethane is used as the C foaming agent, and the amount added varies depending on the density of the desired foam, but is 3 to 35 Φ parts per 100 parts of the polyolefin resin. It is preferable that

In addition, as a foam regulator, sodium bicarbonate and tartaric acid, especially Sogri bicarbonate 4, with an average particle size of 5 to 100 ynμ, are used.
Uses tartaric acid. Addition amount is polyolefin resin 1
゛C soda bicarbonate is 0.1 to 5 fR for 00 weight part
It is preferable to use 0.01 to 0.5 parts by weight of tartarite 11Jf. Soda bicarbonate is less than 0.1 part by weight, tartaric acid is 0.1 part by weight.
If the amount is less than 0.011 parts by weight, the bubble diameter becomes coarse, and if the amount of sodium bicarbonate exceeds 5 parts by weight or the amount of tartaric acid exceeds 0.5 ffl, premature foaming occurs and -C9r is not obtained.

In particular, the ratio of bicarbonate of soda and tartaric acid is 9 to 11:1 (
Good results are obtained when using sodium bicarbonate (tartaric acid).

In addition to the above-mentioned components, commonly added components such as heat stabilizers, H1 agents, antistatic agents, and flame retardants are added in small amounts of 0.1 to 5 parts per 100 parts by weight of the polyolefin resin. be able to.

In the present invention, a mixture of a polyolenoin resin and a cell regulator added in advance by a triblend or a master hajj method is supplied to an extruder, and the mixture is heated to ``above the recovery point of the nitrogen resin'' to melt and plasticize it. Then pressurize and add the liquefied dichloroethane, -C, further knead, and extrude the polyolefin at a discharge pressure higher than the critical pressure of lafluoroethane. Producing a resin foam.

Note that the method of the present invention is particularly effective for obtaining a foam having a density of 300 to 25 kg/Tr13.

Next, embodiments of the present invention will be described.

Example 1 1000 parts of low-density polyethylene (DFD-0111 manufactured by Nippon Unicar Co., Ltd.) with MFR 2.4 was added with a cell regulator Do-C.
A mixture of 11 parts of sodium bicarbonate and 0.1 part of tartaric acid in 1 hour of dry plain and 25 parts of fTi as a light foaming agent.
1 part of the mixture was fed to a 65mm diameter extruder heated to 150°C, kneaded uniformly, and cooled to 102°C using a cold Nj machine following the extruder.
Discharge pressure 18 kg/c (
It is extruded into the atmosphere and foamed.

Regarding the obtained foam sheet, the state of foam molding such as C cell diameter was observed. The result was C as shown in Table 1.

Comparative Examples 1 to 6 Foams were produced in the same manner as in Example 1, except that 0.6 parts by weight of each component J shown in Table 1 as a cell regulator was used.

(The cell diameters and foam molding conditions of the foams were as shown in Table 1.

Table 1 (Margin below) As is clear from Table 1, the foam control agent C of Comparative Examples all had coarse bubbles and a poor appearance. C also showed large fluctuations in cell diameter, but in the cell control agent of Example 1, the cells were uniform and dense, and the appearance was good.

Example 2 The amount of dichlorna 1 to lafluoroethane was changed to 3.3.20.
A foam was produced in the same manner as in Example 1 except that the amount was changed to 32 parts by weight. Foam density 2 out of 1q foam
50kg/va3.40kg/w3.25k
The -C cell diameter and foam molding condition were observed for the one with g/ll3. The results were as shown in Table 2 and FIG. Comparative Example 7 A C foam was produced in the same manner as in Example 2, except that 0.61 part of °C talc was used as a cell regulator, and the cell diameter and foam molding state were observed in the same manner. The results are as shown in Table 2 and Figure 1.

(Left below) Table 2 As is clear from Table 2 and Figure 1, the density of the foam can be varied by changing the amount of dichlorotetrafluorochloride.
The cell control agent C of the example had a small and uniform cell diameter and had a good appearance, but the talc of the comparative example had coarse cells and a poor appearance even though the cell size was constant.

In FIG. 1, the solid line -C represents Example 2, and the dotted line represents Comparative Example 7.

Example 3 The discharge pressure of 1 no-kura die was set at 18 to 40 kg/
A foam was produced in the same manner as in Example 1 except that cJ was changed. The cell diameter and foam molding state of the obtained foam were 1.
The results were as shown in Table 3 and Figure 2.

Comparative Example 8 Talc was used as a bubble regulator at 0.0%. (A C foam was produced in the same manner as in Example 3, except that 3 Ogawa parts were used, and the cell diameter and foam molding state were observed in the same manner.The results were as shown in Table 3 and FIG. 2.

Table 3 (margins below) As is clear from Table 3 and Figure 2, in the example, if the discharge pressure is above the critical pressure of dichlorotetrafluoro-earthane, it will be dense and uniform regardless of the discharge pressure. Although a foam with a good appearance can be obtained due to the presence of air bubbles, it was found that in the comparative example, the air bubble diameter varied greatly depending on the discharge pressure.

In Fig. 2, the solid line represents the example, and the dotted line represents the comparative example. It is clear from more than 10 examples that the method of the present invention is effective against fluctuations in the amount of blowing agent and foam control agent and the discharge pressure. It is possible to produce a foam with an excellent appearance and having dense and uniform closed cells without any distortion.

[Brief explanation of the drawing]

Fig. 1 is a graph showing the relationship between foam density and average bubble i\ in Example 2 and Comparative Example 7, and Fig. 2 is a graph showing the relationship between discharge pressure and average bubble diameter in Example 3 and Comparative Example 8. There is a J graph showing this. Applicant: Building Blocks Chemical-II Juaj (Meeting 1 Representative: Futoshi Fujinuma)

Claims (4)

[Claims] (1) A polyolefin resin, dichlorotetrafluoroethane as a blowing agent, and sodium bicarbonate and tartaric acid as a foam control agent are supplied to an extruder, and the temperature is higher than the softening point of the polyolefin resin and a predetermined pressure is applied. A method for producing a polyolefin resin foam, which comprises kneading and melting and plasticizing under conditions, followed by extrusion into a low-pressure zone and foaming. (2) Claim 1 in which the sodium bicarbonate and tartaric acid chains are [0.1 to 5 parts by weight and 0.01 to 0.5 parts by weight, respectively, based on 100 parts by weight of the polyolefin resin]
A method for producing a polyolefin resin foam as described in 1. (3) The ratio of bicarbonate of soda and tartaric acid is 9 to 11:1e
A method for producing a polyolefin resin foam according to claim 1 or 2. (4) The polyolefin resin foam according to any one of claims 1 to 31H, wherein the tartaric acid has an average particle size of 5 to 100 mμ! J81 construction method.