JPH07276464A - Manufacture of laminate - Google Patents

Abstract

PURPOSE:To provide a manufacturing method for a laminate which can form the laminate of superior surface smoothness by coextrusion molding any type of combination of resins or laminate consitutions. CONSTITUTION:A first thermoplastic resin is fed to a hopper 10 of an extruder 1 and a second thermoplastic resin is fed to a hopper 20 of an extruder 2 respectively, and the first thermoplastic resin is fed into a resin flow path 12 under an extrusion condition while the second thermoplastic resin is flowed in the laminate shape from the upper side and lower side of the first thermoplastic resin and joined together under an extrusion condition, and a laminate composed of three layers, namely a core layer formed by the first thermoplastic resin and both sides of the core layer formed by the second thermoplastic resin. At the same time, polyethylene glycol in a storage tank 5 is fed forcibly from a plunger pump 6 into lubricant injection holes 4, 4 on the upper and lower wall faces of a feed block die 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a laminate by coextrusion molding, which is capable of obtaining a laminate having good surface smoothness without being restricted by the resin composition and layer constitution. Regarding

[0002]

2. Description of the Related Art Conventionally, a lamination method and a coextrusion molding method have been known as a method for producing a laminate of a thermoplastic resin. The lamination method can stack films or sheets with a relatively simple device, but the manufacturing efficiency is low and the cost is disadvantageous because the step of forming the films or sheets and the step of stacking the films are separate. Is. In addition, if an adhesive is used to bond the films or sheets to each other, there are problems such as environmental failure due to the solvent and danger of ignition.

On the other hand, in the co-extrusion molding method, a laminate can be manufactured by only one step of extruding different kinds of raw materials melted by different extruders with an extrusion die, so that the manufacturing efficiency is high and the cost is advantageous. There is also a high degree of freedom in product design.
Furthermore, since no adhesive is used, there is no danger of environmental damage or ignition due to the solvent.

As a co-extrusion device, Japanese Examined Patent Publication No. 50-6860.
The publication describes what is usually called a feed block system in which molten resins are joined at the front of a shaping die. Since this device has one manifold, the die body does not become so large even when performing multi-layer molding of four or more layers, which is advantageous in terms of maintenance such as disassembly and cleaning.

[0005]

However, when the feed block method described in the above publication is used, the viscosity and elasticity of the resin to be multilayered are greatly different, or the thickness of each layer of the laminate to be manufactured is large. If they are different, even if proper extrusion conditions are selected, the inconvenient phenomenon that a parabolic or corrugated pattern is generated on the surface of the laminate and a low-viscosity resin wraps around the outside occurs.

The present invention solves the above-mentioned problems of the prior art and provides a method for producing a laminate which can obtain a laminate having excellent surface smoothness by coextrusion molding with any combination of resins and layer constitutions. The purpose is to

[0007]

According to the method for producing a laminate of the present invention, in producing a laminate by coextrusion molding of two or more thermoplastic resins, at least one of the above thermoplastic resins is When at least one of (1), (2), and (3) is satisfied, the extrusion molding is performed while supplying the lubricant to the inner surface of the extrusion die. (1) A layer thickness ratio of 10 or more (2) A viscosity ratio of 10 or more (3) A elasticity (first normal stress difference) ratio of 5 or more

The thermoplastic resin used in the present invention is not particularly limited as long as it softens when heated and exhibits plasticity and solidifies when cooled. Polyethylene, polypropylene, polybutene, chlorinated polyethylene, ethylene-propylene copolymer Polyolefin resins such as polymer, ethylene-propylene-diene copolymer, ethylene-ethyl acrylate copolymer, propylene copolymer, ethylene-vinyl acetate copolymer, polystyrene, polyvinyl chloride, polyvinyl fluoride, polycarbonate, polyacetal Polyphenylene sulfide, polyphenylene oxide, polyamide resin such as nylon 6, nylon 6-6, nylon 12, polyester such as polyethylene terephthalate and polybutylene terephthalate, acrylic resin, acrylon Lil - butadiene - styrene resin, such as cellulose plastics. These may be used alone or in combination of two or more.

In the present invention, when two or more kinds of the above-mentioned thermoplastic resins are formed into a laminate by coextrusion molding, at least one or more kinds of the resins correspond to at least one of the above (1) to (3). It is effective in some cases. When none of the above (1) to (3) applies, a laminate having good surface smoothness can be obtained by selecting appropriate extrusion conditions without supplying a lubricant to the inner surface of the extrusion die. To be

Here, the viscosity mentioned in (2) means JIS.
It is a value measured in accordance with K7199, and in the case of a crystalline resin, it is a viscosity at a melting point + 40 ° C and a shear rate = 10 [s ^-1 ]. Softening temperature +40 for amorphous resin
It is the viscosity at a shearing rate of 10 [s ^-1 ] at ° C.

The elasticity referred to in (3) is a value measured by a rheometer, and in the case of a crystalline resin, the melting point +
This is the first normal stress difference at 40 ° C. and shear rate = 10 [s ⁻¹ ], and in the case of an amorphous resin, the softening temperature is +40.
It is the first normal stress difference when the shear rate is 10 [s ^-1 ] at ° C.

The first normal stress difference is as shown in FIG.
Normal stress (τx in the shear direction of shear surface B with respect to fixed surface A)
x), the normal stress in the shear gradient direction (τz z), and the normal stress in the vertical direction (τ y y), which are considered as the normal stress in the shear direction (τ xx) and the normal stress in the shear gradient direction. It is the difference from the linear stress (τz z).

The lubricant used in the present invention is a fluid whose viscosity at the time of molding is preferably 0.1 to 1000 poise, more preferably 1 to 100 poise, and it is difficult for decomposition and boiling to occur during molding and the resin. A chemically stable substance that does not dissolve in water and does not accelerate the deterioration of the resin is preferable.

Lubricants satisfying such conditions are, for example, various silicone oils such as liquid paraffin, polymethylsiloxane and polydimethylsiloxane, various fatty acids such as stearic acid and stearic acid metal salts and metal salts thereof, and various interfaces. Examples include activators, polyhydric alcohols such as glycerin and polyethylene glycol and their alkyl esters, alkyl ethers, polyoxyalkylenes and their alkyl esters and alkyl ethers, and low molecular weight polyethylene. These may be used alone,
You may use 2 or more types together.

The amount of lubricant supplied to the inner surface of the extrusion die is preferably such that the film thickness on the inner surface of the extrusion die is 10 to 500 μm, more preferably 50 to 200 μm. Film thickness is 1
If it is less than 0 μm, film breakage easily occurs, and if it exceeds 500 μm, no further effect can be expected.

The extrusion die used in the present invention is one in which a plurality of thermoplastic resins melted by different extruders are simultaneously extruded without the resin layers being mixed with each other to form a laminate having a layer structure of two or more layers. Say. The extrusion die is classified into a multi-manifold type and a feed block type depending on the order of the laminating process and the film forming process. The former is for stacking after film formation, and the latter is for stacking after stacking. The method of the present invention is more effective in the field block type in which the time for flowing in a multilayer state in the extrusion die is longer.

Next, an example of the method for producing a laminate of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing the outline of a manufacturing apparatus used in the present invention, 1 is an extruder, a hopper 10 and a screw (diameter 50 mm, L / D = 2
6) 11 is provided. 2 is also an extruder and is equipped with a hopper 20 and a screw (diameter 50 mm, L / D = 26) 21. The molten resins sent from the extruders 1 and 2 are merged and laminated by the feed block die 3, and a film is formed by the shaping unit 7 to obtain a laminate 9 from the discharge port 71. 8 is a polishing roll, 80 is a roll table, and 81 is a take-up roll.

Immediately after the junction between the resin flow passage 12 of the extruder 1 and the manifolds 23 and 24 of the extruder 2 in the feed block die 3, the lubricant injection ports 4 and 4 are opened above and below the laminated resin flow passage 31. It will be done. A lubricant is supplied from the reservoir 5 to the lubricant inlets 4 and 4 by a plunger pump 6 through a conduit 61.

FIG. 4 is a perspective view showing the internal structure of the shaped portion 7 without the lubricant injection port. The molding portion 72 has a gradually widened front and a thinner thickness following the laminated resin flow path 31. The discharge port 71 has a constant width and a constant thickness.

As a method of supplying the lubricant to the inner surface of the extrusion die, since the inside of the extrusion die is under pressure, the lubricant is supplied from a lubricant supply port provided on the inner wall surface of the extrusion die by using a plunger pump or the like. A method such as press-fitting can be mentioned. or,
The position where the lubricant supply port is provided is preferably provided immediately after the plurality of molten resin layers merge in the extrusion die. Furthermore, it is preferable that the lubricant supply section has a structure in which the lubricant is uniformly supplied over the entire circumference of the resin flow surface.

As an example of such a structure, the lubricant supply unit is shown in FIG.
As shown in FIG. 3, a lubricant reservoir 41 is provided between the lubricant introducing portion 41a and the lubricant supply port, so that the lubricant is temporarily stored in the lubricant reservoir 41 and then supplied to the inner surface of the extrusion die 3. You may

Further, as shown in FIG.
A lubricant reservoir 42 is provided subsequent to b, and if foamed bodies 43, 43 of open cells such as polyurethane are provided at the lubricant supply port at the tip of the lubricant reservoir 42, the inner surface of the extrusion die 3 will be exposed. This is preferable because the outflow amount of the is easily uniform.

[0023]

When at least one of the thermoplastic resins to be coextruded corresponds to at least one of the above (1) to (3), the lubricant is supplied to the inner surface of the extrusion die while the lubricant is being supplied. By extrusion molding, the friction at the interface between the inner surface of the extrusion die and the thermoplastic resin in contact therewith is reduced, so that the laminated state of the molten resin layer does not collapse and is stable. As a result, no uneven pattern is formed on the surface of the laminate, and excellent surface smoothness is obtained.

[0024]

【Example】

(Examples 1 to 3) Next, examples of the method for producing a laminate of the present invention will be described with reference to the drawings. The first thermoplastic resin shown in Table 1 is put in the hopper 10 of the extruder 1 of the manufacturing apparatus shown in FIG. 1, and the second thermoplastic resin shown in Table 2 is put in the extruder 2.
And the second thermoplastic resin from the resin flow channel 22 under the extrusion conditions shown in Table 1 and the manifold shown in Table 1. 23 and 24, the second thermoplastic resin is merged as a layer from the upper side and the lower side of the first thermoplastic resin, the core layer is made of the first thermoplastic resin, and both surfaces thereof are made of the second thermoplastic resin. There were three layers. At the same time, polyethylene glycol (trade name: Nissan Unilube 75DE3800, manufactured by NOF CORPORATION) in the storage tank 5 was pressed by the plunger pump 6 through the conduit 61 from the lubricant injection ports 4 and 4 on the upper and lower inner wall surfaces of the feed block die 3. .

[0025]

[Table 1]

[0026]

[Table 2]

The laminated resin is sent to the shaping section 7 while its upper and lower surfaces are lubricated at the interface with the inner surface of the feed block die 3.
The shaped portion 7 was doubled in the width direction while reducing the thickness, and then extruded from the ejection port 71. The extruded laminate having a three-layer structure is passed through a polishing roll 8 and a roll table 80 to be cooled and solidified, and then taken up by a take-up roll 81,
A laminate 9 having a width of 400 mm and a thickness of 6 mm was obtained and wound.

Comparative Examples 1 to 3 Table 3
In the same manner as in Examples 1 to 3, except that the first thermoplastic resin shown in Table 2 and the second thermoplastic resin shown in Table 4 were extruded under the conditions shown in Table 3 and Table 4, respectively. 400 m
A 3-layer laminated body having m and a thickness of 6 mm was coextrusion-molded.

[0029]

[Table 3]

[0030]

[Table 4]

Evaluation of surface properties of products Based on JIS B0601, a surface roughness meter (trade name: Surfcom, manufactured by Tokyo Seimitsu Co., Ltd.) was used to measure the surface roughness of the products to the maximum height (Rmax) of the sectional curve and 10 points. Average roughness (R
z). The measurement length is 30 mm. Example 1
The results of Nos. 3 to 3 are shown in Table 5, and the results of Comparative Examples 1 to 3 are shown in Table 6 (however, the average value after three measurements is shown).

[0032]

[Table 5]

[0033]

[Table 6]

Table 7 shows the manufacturer names and trade names of the first and second thermoplastic resins.

[0035]

[Table 7]

As is clear from Tables 5 and 6, it was found that Examples 1 to 3 had much smaller surface roughness and excellent surface smoothness than Comparative Examples 1 to 3. .

[0037]

EFFECTS OF THE INVENTION The method for producing a laminated body of the present invention has the above constitution, and if it is a thermoplastic resin, a laminated body excellent in surface smoothness can be obtained by coextrusion molding regardless of the type of resin or the layer constitution. You can

[0038]

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an outline of an apparatus used in the present invention.

FIG. 2 is a sectional view showing another example of the extrusion die used in the present invention.

FIG. 3 is a sectional view showing still another example of the extrusion die used in the present invention.

FIG. 4 is a perspective view showing the internal structure of the shaping unit.

FIG. 5 is an explanatory diagram for explaining a first normal stress difference.

[Explanation of symbols]

 1, 2: Extruder 3: Extrusion die 4: Lubricant supply section 5: Lubricant storage tank 6: Plunger pump 7: Shaping section 9: Laminated body 10, 20: Hopper 11,21: Screw 12,22: Resin flow path 23, 24: Manifold 31: Laminated resin flow path 41, 42: Lubricant reservoir 43: Foam 71: Discharge port

Claims (1)

[Claims] 1. When a laminate is produced by coextrusion molding two or more thermoplastic resins, at least one of the above thermoplastic resins is compared with other resins in the following (1) and (2). ) Or (3), the method for producing a laminate is characterized in that extrusion molding is performed while supplying a lubricant to the inner surface of the extrusion die. (1) A layer thickness ratio of 10 or more (2) A viscosity ratio of 10 or more (3) A elasticity (first normal stress difference) ratio of 5 or more