JPH05222238A - Method for modifying wettability of resin foam - Google Patents

Abstract

PURPOSE:To uniformly carry out modify the wettability on the surface of a resin foam or in the interior of bubbles according to a simple and efficient method by exposing the resin foam to an atmosphere of a reactional gas. CONSTITUTION:A resin foam is exposed to an atmosphere of a reactional gas such as a halogen, carbon disulfide or ozone. For example, a hermetically sealed container 5 designed to feed a gas through a reactional gas feed control valve 9 and a feed control valve 8 for diluting nitrogen gas is used to always monitor the reactional gas concentration with a gas concentration sensing regulator 6. The pressure in the hermetically sealed container 5 is usually maintained at atmospheric pressure and the atmosphere in the hermetically sealed container 5 is kept uniform with circulating fans 7. A vent port is connected to a waste gas treating apparatus. In the case of an open-cell foam, a resin foam sheet 4 is introduced into the hermetically sealed container and compressed with pinch rolls 10. The treatment with the reactional gas is then carried out and the resin foam sheet is recompressed with pinch rolls 11 and subsequently taken out to the outside. In the case of a closed-cell foam, the compression is not always required.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for modifying the wettability of various resin foams. More specifically, the present invention relates to a method for improving the wettability of various resin foams. And a method of modifying the wettability of the same.

[0002]

2. Description of the Related Art Conventionally, resin foam has been mainly used as a cushioning material, but most of them do not use the foam alone, for example, (1) paper, foreign plastics, aluminum, etc. The outer skin of (1) is fused to a resin foam to form a composite material, or (2) a resin foam is coated with an adhesive or an adhesive and attached to another substrate for use.

Thus, in order to form a resin foam into a composite material or to attach it to another substrate, the resin foam is required to have a function of firmly fusing, sticking or adhering.

In the case of an open-cell foam, for example, by imparting wettability to the inside of the open-cell, for example, the amount of water retention is improved, or the inside of the open-cell is impregnated with an adhesive sealing material to obtain a sealant. We are trying to improve the function of the material.

Many resin foams, such as polyolefin resin foams, have low wettability and poor adhesion to other substances. Conventionally, as a method of modifying the surface of a resin foam to improve the wettability, there is a method of adding a polar group. As a method of imparting a polar group, a method of blending a polar resin with a raw material resin, a method of corona discharge treatment of a resin foam, a method of coating and impregnating a foam with a coupling agent, and the like are generally adopted.

Among these methods, the method of blending a polar resin is high in the cost of the polar resin, and further inhibits the generation of bubbles in the production process of the foam, and selects a friend material for each mating base material. There are drawbacks such as poor versatility because it is forced.

[0007] In the corona discharge treatment method, when a high degree of treatment is to be obtained, local discharge causes uneven treatment in the width direction of the resin foam sheet, and in extreme cases, pinholes are generated in the resin foam. Moreover, with the corona discharge treatment method, it is difficult to uniformly treat the inside of the open cells. The coating method using a coupling agent has the drawback of high equipment and running costs.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for modifying the wettability of the surface of a resin foam or the inside of cells by a simple and efficient method.

The inventors of the present invention have made extensive studies as to a method for imparting a polar group without the above-mentioned defects, and as a result, by exposing the resin foam to a reactive gas atmosphere, the resin foam is uniformly damaged without being damaged. It has been found that the surface can be modified and the uniform treatment can be performed even inside the open cells.
The present invention has been completed based on these findings.

[0010]

According to the present invention, there is provided a method for modifying the wettability of a resin foam, which comprises exposing the resin foam to a reaction gas atmosphere.

The present invention will be described in detail below. The method for modifying the wettability of a resin foam according to the present invention is a method in which a foam is directly passed through a highly reactive gas atmosphere to impart a polar group to the surface of the foam or the inside of open cells.

The method of the present invention allows continuous treatment in a dry state by simple steps. Also,
The degree of wettability modification (the degree of treatment) can also be arbitrarily adjusted by appropriately combining the type of reaction gas to be used, the concentration of the reaction gas, the passage speed of the resin foam in the reaction gas zone, and the like. Treatment unevenness in the width direction of the resin foam can be reduced as compared with the corona discharge treatment. Since the reaction gas is a gas, it is possible to uniformly process the inside of the open cells.

The wettability modification method of the present invention will be described with reference to FIG. The resin foam sheet (4) is introduced into the closed container (5). The closed container has a reaction gas supply control valve (9) and a nitrogen gas supply control valve (8) for dilution.
The gas is supplied via the. The reaction gas concentration is constantly monitored by the gas concentration detection controller (6),
The concentration is adjusted by the reaction gas and nitrogen gas control valve. The pressure in the closed container is usually maintained at about atmospheric pressure. Also,
The atmosphere in the closed container is agitated by the circulation fan (7) to be kept uniform. An exhaust port provided in the upper part of the closed container is connected to an exhaust treatment facility (12).

In the case of open-cell foam, the resin foam sheet (4), when introduced into a closed container, was first compressed by a pair of pinch rolls (10) and then treated with a reaction gas. After that, it is recompressed by the pair of pinch rolls (11) and then carried out of the closed container. In the examples, the distance between the doorway and each pinch roll was about 1 m. In the case of closed cell foam, it is not necessary to pass pinch rolls for compression.

The reaction gas is not particularly limited as long as it can modify the wettability of the resin foam, and specific examples thereof include halogen such as fluorine gas, carbon disulfide and ozone. it can. The reaction gas is usually diluted with an inert gas such as nitrogen gas before use. Further, when a small amount of oxygen gas is present in the atmosphere or on the surface of the resin foam, polar groups are easily generated and the wettability is improved. The higher the temperature of the resin foam and the atmosphere, the more reactive it is.

[0016]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples.

[Examples and Comparative Examples] Using the following three kinds of foams, the reaction gas treatment and the corona discharge treatment were performed by the treatment means and the treatment conditions shown below.

<Foams for Performance Evaluation> The following three kinds of foams were used for the performance evaluation of the wettability modification test. (1) Foam A Low-density polyethylene closed-cell foam [Sekisui Chemical Co., Ltd.
Made, product name Softlon S, firing rate 30 times, thickness 2m
m] (2) Foam B Polypropylene closed-cell foam [manufactured by Sekisui Chemical Co., Ltd., trade name Softlon PP, expansion ratio 25 times, thickness 3 mm] (3) Foam C low-density polyethylene open-cell foam [Sekisui Chemical Co., Ltd.
Made, brand name Soft Ron Renpo, foaming ratio 20 times, thickness 15 mm]

<Treatment Means and Treatment Conditions> (1) Reaction Gas Treatment Reactive gas type: Fluorine gas Fluorine gas concentration: 1.36% (residual gas: nitrogen) Foam and ambient temperature: 25 ° C. (2) Corona discharge Treatment equipment: Kasuga Electric Co., Ltd. corona discharge treatment machine, model HF
SS-203 Voltage: 205V Current: 44A Electrode bar diameter: 8mm Gap between electrode bar and foam: 10mm <Wetting reagent for treating degree evaluation> Ethylene glycol monoethyl ether

Results and Evaluation [1] Foam B (Softron PP) was subjected to fluorine gas treatment and corona discharge treatment under the above conditions. The treatment speed was 10 m / min for the fluorine gas treatment, and 10 m / min and 30 m / min for the corona discharge treatment.

FIG. 1 shows the time-dependent change in the wettability of the foam B after each treatment. In FIG. 1, 1 is fluorine gas treatment (treatment speed 10 m / min), 2 is corona discharge treatment (treatment speed 1
0 m / min), 3 indicates corona discharge treatment (30 m / min). In FIG. 1, the vertical axis represents wettability (unit: dyne / cm), and the horizontal axis represents elapsed days.

As is apparent from FIG. 1, in the case of the fluorine gas treatment (1), 50 dy was obtained even after 30 days from the treatment.
It has a high wettability of ne / cm. The foam B
The wettability of the untreated product was 31 dyne / cm. On the other hand, in the case of the corona discharge treatment (2, 3), the wettability is low both in the initial stage and over time. [2]
Using the foam A (Softlon S), fluorine gas treatment and corona discharge treatment were performed under the above conditions. The results are shown in Table 1.
Shown in.

[0023]

[Table 1]

As is clear from Table 1, in the case of the fluorine gas treatment, the wettability of the foam sheet in the width direction was uniform, and even if the treatment degree was increased, no inconvenience such as pinholes occurred. . On the other hand, in the case of the corona discharge treatment, the wettability varied and pinholes were generated as the treatment degree was increased. The wettability of the untreated product was 33 dyne / cm.

[3] Foam C (Softlon Lempow)
Was used to perform the fluorine gas treatment and the corona discharge treatment under the above conditions. The results are shown in Table 2.

[0026]

[Table 2]

As is clear from Table 2, in the case of the fluorine gas treatment, the wettability of the surface layer of the foam sheet and the wettability of the center layer in the thickness direction are the same, showing an excellent modifying effect. ing. On the other hand, in the case of corona discharge treatment, the wettability of the center layer in the thickness direction is 50 dyne of the untreated product.
It was equivalent to / cm.

[0028]

According to the present invention, the wettability of the surface of a resin foam or the inside of cells can be uniformly modified by a simple and economical method. The closed-cell foam with improved wettability is useful as an adhesive / adhesive processed material, composite material, etc., and in the case of the open-cell foam, it is also useful as a heat insulating / condensation water retaining material for a folded sheet roofing material. is there.

[Brief description of drawings]

FIG. 1 is a graph showing changes over time in wettability of resin foams due to differences in treatment methods.

FIG. 2 is an explanatory view showing a method for modifying the wettability of a resin foam according to the present invention.

[Explanation of symbols]

 1 Fluorine gas treated product (treatment speed 10 m / min) 2 Corona discharge treated product (treatment speed 10 m / min) 3 Corona discharge treated product (treatment speed 30 m / min) 4 Foam sheet 5 Closed container 6 Gas concentration detection controller 7 Circulation fan 8 Dilution gas supply control valve 9 Reactive gas supply control valve 10 Inlet pinch roll 11 Outlet pinch roll 12 Exhaust treatment facility

Claims (2)

[Claims] 1. A method for modifying the wettability of a resin foam, which comprises exposing the resin foam to a reaction gas atmosphere. 2. The method for modifying the wettability of a resin foam according to claim 1, wherein the reaction gas is halogen, carbon disulfide or ozone.