JPH0375131A - Hot press-molded body of thermoplastic synthetic resin non-crosslinked open-cell foam - Google Patents

Abstract

PURPOSE:To easily mold even a shape having modified surface and large in the difference in level of unevenness by directly bonding a skin layer to a base material foam in a state being the substantially same size as the cell size of a foam layer receiving no hot pressing. CONSTITUTION:A heating mold 3 heated to the m.p. of the base material resin of a thermoplastic synthetic resin non-crosslinked open-cell foam 1 or higher is allowed to approach the foam 1 to be pressed thereto. When the foam is heated to its m.p. or higher, said foam is melted to become extremely well in flowabiltiy. Since air in the cells of the foam is heated to its m.p. or higher, said foam is melted to become extremely well in flowabiltiy. Since air in the cells of the foam escapes through the communicating gaps of open cells, molten and fluidized cell films easily form a skin layer to advance in the advance direction of the heating mold 3. When there is difference in level in a molded product, one different in level in a molded product, one different in the thickness of the skin layer every steps is formed. The surface of the obtained molded body has no rough feel due to cell films and is subjected to surface finish feeling smooth and pleasant. When an embossed pattern of every kind is applied to the surface of the heating mold, a fine embossed pattern can be applied to the surface of the molded product.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a heat-pressed molded article of non-crosslinked open-cell foam of thermoplastic synthetic resin with improved surface, and more specifically, to The present invention relates to a hot-pressed molded article of non-crosslinked open-cell thermoplastic synthetic resin foam that can be obtained in a short molding time without peeling or cutting waste during production.

[Conventional technology]

Conventionally, open-cell foams, especially soft urethane foams, are light and highly flexible, and have been used as cushioning materials, cushioning protection materials, storage cases,
It is used in a wide range of fields such as cucumber wood. However, the surface of soft urethane foam products is rough due to the bubble film, and it has been difficult to finish them in a finely textured pattern. In order to improve this problem, attempts have been made to form soft open-cell foamed urethane foam by cutting and then adhere a film or sheet to the surface to make the surface smooth.

[Problem to be solved by the invention]

However, forming by cutting requires a lot of time and effort, generates a large amount of cutting waste, increases manufacturing costs, and is not economical. In addition, the shape of the surface is complicated and has deep depressions. If the molded product is made of soft urethane foam, it is not possible to adhere the film or sheet along the shape of the surface, and it is impossible to obtain a molded product with a substantially smooth surface. Since adhesive is used, there are problems such as peeling at high temperatures and smells.

The present invention is an attempt to solve the above-mentioned problems, and its purpose is to provide a modified surface that can be easily molded even in shapes with large unevenness, and has sufficient surface smoothness. A non-crosslinked thermoplastic synthetic resin that does not require adhesion with a film or sheet to achieve such surface smoothness, does not produce odor, peeling, or cutting waste during manufacturing, and can be molded in a short molding time. An object of the present invention is to provide an open-cell foam press-molded product.

[Means to solve the problem]

The present invention is a heat-pressed molded article made of a thermoplastic synthetic resin non-crosslinked open-cell foam, and the foam is pressed from its surface by 31nI11 or more to form a recess, and the surface of the recess is heated. A skin layer is formed due to the pressing, and the skin layer has a thickness of 75 μm or more, and the foam layer immediately below the skin layer has a cell diameter that is substantially the same as the cell diameter of the foam layer that has not been subjected to heat pressing. The present invention provides a hot-pressed molded article of a non-crosslinked open-cell foam made of a thermoplastic synthetic resin, in which the skin layer is directly bonded to the base foam in a state of a certain size.

In the present invention, the non-crosslinked open-cell thermoplastic synthetic resin foam may be a foam that itself has an open-cell structure obtained by molding such as extrusion foaming, or a non-crosslinked open-cell thermoplastic synthetic resin foam that can be used by drilling, etc. It also includes open-cell foams whose cell structures are made open through post-processing. Examples of the thermoplastic synthetic resin non-crosslinked open-cell foam used in the hot-press molded article of the present invention include polybutene-1, ethylene ionomer, mixed resin of polybutene-1 and ethylene ionomer, polypropylene and 1.2 polybutadiene. Foams made of non-crosslinked resins such as mixed resins of low density polyethylene and ethylene ionomer, mixed resins of high density polyethylene and ethylene ionomers, mixed resins of ethylene-vinyl acetate copolymer and ethylene ionomers, etc. can be mentioned.

Among these, an open-cell foam made of a mixed resin of polybutene-1 and an ethylene ionomer gives particularly preferable results in achieving the object of the present invention.

Therefore, an open cell foam made of this mixed resin will be described below as a representative example.

The mixed resin of polybutene-1 and ethylene ionomer preferably has a component ratio of 10 to 100 parts by weight of ethylene ionomer to 100 parts by weight of polybutene-i.

As the blowing agent, a usual volatile blowing agent is used. Typical examples include lower hydrocarbons such as propane, butane, pentane, pentyne, hexane, and ethyl chloride, methylene chloride, methyl chloride, trichloromonofluoromethane, dichloromonofluoromethane, monochlorodifluoromethane, monochlorotrifluoromethane, and dichlorodifluoromethane. , 1.1-difluoroethane, 1
There are halogenated hydrocarbons such as -chloro-1,1-difluoroethane, 1,2-dichlorotetrafluoroethane, and monochloropentafluoroethane. Mixtures of these are also useful. The amount of the blowing agent is usually 5 to 50 parts by weight per 100 parts by weight of the mixed resin of polybutene-1 and ionomer.

As a method for obtaining the open-cell foam of the present invention, a method similar to the known extrusion foaming method can be used. Examples of this include a method in which a foaming agent is mixed with the resin composition or injected into the extruder midway, kneaded and melted under high temperature and high pressure, and then continuously extruded into a low pressure zone to foam. Further, a small amount of a metal soap such as zinc stearate, or an inorganic fine powder such as calcium silicate, talc, or calcium carbonate may be contained as a lubricant or a bubble control agent. Further, depending on the case, it is also possible to add an ultraviolet deterioration inhibitor, an oxidation stabilizer, a coloring agent, etc. Furthermore, for the purpose of improving the physical properties of the foam, a thermoplastic synthetic resin that does not interfere with the formation of open cells can be added.

The hot-pressed molded article of the present invention is produced by pressing a heating mold heated to a temperature higher than the melting point of the base resin of the foam onto the surface of the non-crosslinked open-cell thermoplastic synthetic resin foam. (hot press molding).

Next, a method for manufacturing a hot press molded article of the present invention will be explained with reference to the drawings.

First, as shown in FIG. 1(A), a non-crosslinked open-cell thermoplastic synthetic resin foam is heated to a temperature higher than the melting point of the base resin of the foam (in practice, the melting point of the base resin plus 20°C to 100°C). The heating mold 3 heated to a temperature within the temperature range of 200°C and preferably 200°C or less in terms of the fiber value is brought close, and the heating mold 3 is pressed against the foam l as shown in Figure 1 (B). do. Here, when the non-crosslinked open-cell thermoplastic resin foam is heated above its melting point, it melts and becomes extremely fluid. On the other hand, since the air in the cells of the foam escapes through the interconnected pores of the open cells, the melted and fluidized cell film easily forms a skin layer and advances in the direction of movement of the heating mold. As shown in Figure 1 (C), a thick skin layer 2a is formed in the part where the heating mold has penetrated deeply (the convex part of the heating mold), and a thick skin layer 2a is formed in the part where the heating mold has penetrated shallowly (the concave part of the heating mold). A thin skin layer 2b is formed. That is, if there are steps in the molded product, the thickness of the skin layer will differ from step to step. This skin layer can be obtained to a thickness of 75 μm or more by hot pressing a non-crosslinked open-cell thermoplastic resin foam from the surface at a temperature of 3 ma+ or higher and at a temperature higher than the melting point of the base resin of the foam.

In the process of heat pressing, the effect of heat is limited to the skin layer, with almost no effect on the interior of the open-cell foam, and the diameter of the bubbles directly below the skin layer is substantially smaller than that inside the skin layer. is the same as the bubble diameter. After the foam is melted in this way, the heating mold 3 is cooled [Fig. 1 (C)]
After the molten resin has sufficiently cooled and solidified, the heating mold 3 is released from the foam 1 as shown in FIG. 1(D).

The surface of the obtained molded product is finished with a smooth and pleasant surface without the roughness of the bubble film.

If various uneven patterns are provided on the surface of the heating mold described above, a fine uneven pattern can be applied to the surface of the molded product.

According to the present invention, the foam film melted and fluidized by the heating mold easily forms a skin layer while the molding progresses.
Molded products with complex shapes and grooves with large differences in unevenness, which could not be produced conventionally, can be obtained extremely easily.

Examples of shapes of molded bodies are shown in FIGS. 2(A) to 2(D).

Figure 2 (A) is an example of a molded body with a large recess on the inside;
Fig. 2 (B) is an example of a molded body with a concave peripheral edge and an inner convex portion and a concave portion, Fig. 2 (C) is an example of a molded body with a relatively fine wavy uneven shape, and Fig. 2 (D) shows an example of a molded article having a large concave portion on the inside of one side and relatively fine wavy irregularities on the other side.

In the four molded bodies of the present invention, the open-cell foam and the skin layer are integrally formed from the same resin, so the skin layer is less likely to peel off than when a film or sheet is wrapped or bonded. It has the advantage that there is no problem with adhesive odor.

〔Example〕

The present invention will be explained below with reference to Examples.

Example 1 Polybutene-1 resin (M I = 1.0 g
710 minutes, density = 0.91 g/cd, melting point = 112°C)
For 100 parts by weight of ionomer resin (MI=1.
0g/10min, density = 0.95g#+j, melting point = 80°
C) Using 60 parts by weight and adding 0.1 part by weight of talc as a nucleating agent, 20 parts by weight of dichlorodifluoromethane as a foaming agent was heated and kneaded with an extruder, and foamed with a heat exchanger. The mixture was cooled to temperature and extruded into a low pressure region through a die to foam. The resulting foam was open-celled and had a density of 27 kg/nf. On the surface of this open cell foam,
A mold heated to 150° C. was pressed 5 mm from the surface of the foam to obtain a hot-pressed molded product having a skin layer of 130 μm thick and smooth and pleasant to the touch.

Further, a molded body having the shape shown in FIG. 2(D) (the pressing distance of the concave portion was 30 nm+, and the pressing distance of the central convex portion was 15 mm) was obtained using a heating mold. The skin layer was smooth and did not have the rough feeling of air bubbles in the foam. The thickness of the skin layer is as thick as 800 μm in the part where the pressing distance is large and the depression is large, and 380 μm in the slightly convex part in the center where the pressing distance is small.
μm (!: It was ugly.The skin layer on the surface with the corrugated irregularities had a substantially uniform thickness.

Next, a hot-pressed molded product having a groove with a width of 2 cm, a length of 10 cm, and a depth of 8 Cl was created, and a molded product with a smooth surface and a good feel was obtained, with a skin layer of 2.1 cm in the recess. Ta.

When the hot-pressed molded article was cut and the state of the cross section was observed, it was found that the diameter of the bubbles immediately below the skin layer was substantially the same as the diameter of the bubbles inside the skin layer.

Example 2 Polybutene-1 resin (M I =1.0
g710 min, density = 0.91 g/cJ, melting point = 112°C
), 100 parts by weight of ethylene-vinyl acetate copolymer (M I = 1.4 g/10 min, density = 0.93 g/
A foam was obtained in the same manner as in Example 1, except that 40 parts by weight of csfl (melting point -93°C) was used. The resulting foam was an open cell foam with a density of 29 kg/rrr.

When hot-pressed molded bodies of various shapes were prepared from this open-cell foam in the same manner as in Example 1, almost the same results as those of the Example were obtained.

〔Effect of the invention〕

The present invention has a skin layer with good smoothness formed on the surface, has a soft feel, and has a modified surface, and can be used even when forming a complex shape or a shape with large unevenness that could not be achieved conventionally. , the bottom shape can be easily done in a short time. Also,
There is no need for adhesion with a film or sheet to obtain the above-mentioned surface smoothness, and there is no need for cutting when shaping the bottom, so there is no odor or cutting waste produced during manufacturing, and it can be used at high temperatures. There is no peeling.

Furthermore, a fine uneven pattern can be provided on the surface of the molded product.

[Brief explanation of drawings]

Figures 1 (A), (B), (C), and (D) are cross-sectional explanatory diagrams for explaining the process of creating a hot press molded product of the present invention, and Figures 2 (A), (B), (C)
, (D) is a sectional view showing an example of a hot press molded product of the present invention. 1...Thermoplastic synthetic resin non-crosslinked open cell foam 2.-
Skin layer 2a - Thick skin layer 2b - Thin skin layer 3 - Heating type 1 Figure (A)

Claims (1)

[Claims] 1 A heat-pressed molded body made of a thermoplastic synthetic resin non-crosslinked open-cell foam, the foam having a surface area of 3 m from its surface.
m or more to form a recess, a skin layer formed by hot pressing is formed on the surface of the recess, the skin layer has a thickness of 75 μm or more, and the foam directly under the skin layer is A thermoplastic synthetic resin non-crosslinked open-cell foam in which the skin layer is directly bonded to the base foam in a state where the layer has substantially the same cell diameter as the cell diameter of the foam layer that has not been subjected to heat pressing. Hot press molded product.