JPS6036939B2 - Method for manufacturing laminate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a laminate by bonding sheets of thermoplastic resin to various base materials. This invention relates to a method for manufacturing large, high-performance laminates at low cost.

In recent years, a wide variety of composite materials have been developed in which thermoplastic resin sheets, films, etc. are combined with base materials such as metal foil, paper, and cloth, and they are becoming popular as products with higher added value that take advantage of the characteristics of the individual components. It has been put into practical use.

Furthermore, the performance required for these composite materials varies depending on the purpose of use. Conventionally, most of the manufacturing methods for these composite materials involve a dry lamination method in which various adhesives are used in the process of bonding the thermoplastic resin and the base material, or
It uses an extrusion lamination method that uses an anchor coating agent, molten resin, etc.

However, these methods still have problems such as increased costs due to the use of adhesives, large-scale and complicated equipment, and, depending on the type of adhesive, pollution of the working environment. The method of the present invention involves manufacturing a laminate by bonding a sheet (film) of thermoplastic resin A to a base material such as paper, cloth, metal plate, metal foil, etc. The sheet contacts the base material. A layer of thermoplastic resin B having a melting point (or softening point) lower than that of thermoplastic resin A is provided on the surface, and the surface of thermoplastic resin B is subjected to surface treatment such as corona discharge treatment and flame treatment. The surface tension C is raised to 42 dynes/skin or more, and the sheet and the base material are laminated with a layer of thermoplastic resin B interposed therebetween, and the melting point (or softening point) of the thermoplastic resin A is lowered. This is a method of pressure bonding at a temperature higher than the melting point (or softening point) of thermoplastic resin B. Its purpose is to
By increasing the surface tension of the thermoplastic resin layer B in contact with the base layer, a resin layer with good adhesiveness is formed and strong adhesion with the base layer is obtained.As a result of various studies, the present inventors have found that It was found that sufficient adhesive strength could not be obtained unless the surface tension yc of the thermoplastic resin layer B was set to 42 dynes/dyne or higher.

In addition, by pressing the stacked sheets and the base material at a temperature lower than the melting point (or softening point) of thermoplastic resin A and higher than the melting point (or softening point) of thermoplastic resin B, the thermoplastic resin that is the material A laminate can be obtained without sacrificing the properties of A (eg, stretching effect, etc.).

The thermoplastic resin sheet provided with the adhesive resin layer, which is preferably used in the present invention, includes a two-layer (or multilayer) film or sheet produced by coextruding thermoplastic resin A and thermoplastic resin B. Alternatively, the two-layer (or multi-layer) film may be stretched, and the stretched film may be made into tapes, yarns, etc., and woven fabrics, non-woven fabrics, silk-like bodies, etc. produced by weaving, knitting, cross-layering, etc. is used.

The thermoplastic resin A constituting the sheet has crystallinity,
Resins that exhibit molecular orientation through stretching, etc. are used, and are used to produce high-density polyethylene (including an ethylene-Q-olefin copolymer whose main component is ethylene and whose density is in the same range as high-density polyethylene), isotactic polypropylene (including an ethylene-Q-olefin copolymer whose main component is ethylene, and whose density is in the same range as high-density polyethylene). (including crystalline copolymers as main components), homopolymers and copolymers of nylon, polyethylene terephthalate, etc., and filtered products of these or other resins mainly composed of these. On the other hand, the thermoplastic resin B, which is the adhesive resin layer, has a melting point (or softening point) lower than that of the thermoplastic resin A, and the properties of the material such as the sheet are It must be able to be easily bonded to the base material within a temperature range that does not cause loss.

Various resins having such properties can be selected in combination with thermoplastic resin A, but preferably low density polyethylene, amorphous ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, Polyvinyl chloride (European quality),
Modified and unmodified homopolymers and copolymers of polyolefins modified with polyvinylidene chloride, polymethyl methacrylate, polystyrene, maleic acid, acrylic acid, etc., and others based on these and others. Mixtures with other resins are used. Examples of common combinations of thermoplastic resin A and thermoplastic resin B include high density polyethylene and low density polyethylene, high density polyethylene and ethylene-vinyl acetate copolymer, isotactic polypropylene and amorphous ethylene. propylene copolymer,
Examples include a mixture of isotactic polypropylene and polypropylene whose main component is low-density polyethylene.

Furthermore, the thermoplastic resin sheet in the present invention is not limited to a two-layer film made of a combination of two types of resins each having a different melting point (or softening point).
It also includes a multilayer film of three or more layers made of the same or different resins that can be pressure-bonded within a temperature range without losing the properties of each material (eg, stretching effect, etc.).

There are no particular restrictions on the base material, and for example, metal plates, metal foils, cloth, paper, etc. can be used. In particular, cellulose base materials have good adhesion to the sheet, and paper is the most preferred.

The laminate produced by bonding and press-bonding a sheet and a base material is not only simply composed of two layers, a sheet and a base material, but also a three-layer laminate with a sheet as the center layer and base material layers on both sides. , a 3-layer laminate with sheet layers provided on both sides of the laminate, and a multi-layer laminate in which a 2-layer and/or 3-layer laminate is further layered are also manufactured.

As mentioned above, the surface of the thermoplastic resin B forming the adhesive resin layer of the sheet is subjected to corona discharge treatment etc. to reduce its surface tension yc.
This can be achieved, for example, by passing the thermoplastic resin B side of the sheet between the electrodes of a corona discharge device before overlapping the sheet and the substrate.

The following describes the production of laminates, ie, heavy packaging materials, reinforced paper, etc., for which the method of the present invention is particularly effective.
The embodiment will be explained according to the attached drawings.

Fig. 1 shows a sheet (film) of a silk-like body, a cloth body, or a non-woven fabric made of stretched tape, yarn, etc., with the layer of thermoplastic resin B facing the base material.
It is.

2 is a base material such as paper material, 3 is a corona discharge device, 4 is a guide roll, 5 is a heating device, 6 is a pressure roll on the side in contact with the sheet, 7 is a pressure roll on the side in contact with Motomura, 8 is a product It is a laminate.

After the sheet is subjected to surface treatment by the corona discharge device 3, it is overlapped with the base material 2 and heated and pressed to a predetermined temperature by the heating device 5 and/or rolls 6 and 7. By the way, an adhesion phenomenon occurs between the sheet and the roll 6, and after the sheet is crimped, the sheet is taken by the roll 6, and the sheet and the base material may partially peel off.

In order to solve this problem, it is important to press the sheet while keeping the temperature of the roll 6 in contact with it as low as possible. That is, in the method of the present invention, in FIG. 1, only the surface temperature of the roll 7 in contact with the base material is set to a temperature higher than the melting point (or softening point) of the thermoplastic resin B, and the surface temperature of the roll 6 in contact with the sheet is set to a temperature higher than the melting point (or softening point) of the thermoplastic resin B. The temperature of the sheet is maintained at a temperature lower than the melting point (or softening point) of plastic resin B, and the temperature of the sheet is lower than the melting point (or softening point) of thermoplastic resin A and higher than the melting point (or softening point) of thermoplastic resin B. By press-bonding the laminate as a laminate, the above-mentioned adhesion phenomenon can be prevented and a laminate can be easily manufactured.

The roll 6 may be cooled if necessary to prevent sticking phenomena. In addition, it is preferable to use a roll 6 made of a material such as rubber or synthetic resin with an elastic surface in order to press the sheet and the base material together with as wide an adhesive surface as possible. Optimally, the surface material of the roll 6 should have a cohesive energy density (CED ) is 40
(cal/cc) or less, it is desirable to use rubber or synthetic resin.

Typical examples of such materials include silicone rubber and polytetrafluoroethylene resin. The pressure of the rolls during crimping is not particularly limited as a means of helping the base material and sheet adhere, but the number of crimping rolls is not limited to one pair as shown in Figure 1, but may be 6 or 7 rolls as necessary. After that, one or more pairs of rolls may be further provided.

Further, the surface treatment (corona discharge treatment) of the sheet may be performed either before preheating or after child heating. Incidentally, the child heat (child heat device 5) is not necessarily required when sufficient heat quantity for thermocompression bonding can be obtained by the roll 7 alone.

Although the embodiments of the present invention have been described in detail above, the manufacturing method of the present invention is not limited to the above-mentioned embodiments, and the pressurizing method is not limited to rolls, but any arbitrary method such as a press plate can also be used. .

In the conventional manufacturing method of laminates by thermocompression bonding, silk-like bodies, cloth bodies, or non-woven fabrics made of stretched tapes, yarns, etc. undergo significant thermal shrinkage at the softening temperature during pressure bonding, and do not adhere well to the base material. Pressure bonding is difficult, the stretching effect is almost completely lost, and the strength is significantly reduced.

Furthermore, when adhesives are used, many problems remain, such as high costs, complicated equipment, and pollution of the working environment. In addition, it has been known to bond split fiber nonwoven fabric produced from stretched multilayer film to kraft paper to form a laminate, but this type of laminate does not have sufficient adhesive strength after being crimped, resulting in peeling. There is a possibility.

As mentioned above, the effects of the present invention are particularly remarkable in the production of heavy-duty packaging materials, reinforced paper, etc. In comparison, 1
Since no adhesive is required, costs for equipment, materials, etc. are reduced.

2 The breathability of the paper is not impaired.

3. After winding up the product, the adhesive will not run around through the mesh and cause blocking.

4. Food packaging does not use adhesives, so there are no hygiene problems.

5. There are no environmental pollution problems caused by solvent vapor during the adhesive coating process.

6. Although no adhesive (auxiliary) agent is used, it does not require high temperatures like extrusion lamination, so the stretching effect is not impaired even in the case of stretched tapes.

Many such advantages can be mentioned, and these advantages exhibit great advantages in industrial implementation.

Examples of the present invention will be described below.

Example 1 and Comparative Example 1 Commercially available high-density polyethylene (hereinafter referred to as HDPE).

M. 1.1.0, density 0.960, melting point 127°C) and commercially available ethylene-vinyl acetate copolymer (hereinafter referred to as EV
(referred to as A). M. 1.2.0, density 0.930, VA content 5%, softening point 90CC), it was made into a coextruded two-layer film using a T-die, and this was stretched once (length ratio 6 times), and the following By carrying out corona discharge treatment under the following conditions and changing the speed at which the treated body passed through the electrode surface, various single-stretch films with different surface tensions were obtained. Corona discharge: Equipment used
Taisei Sangyo ■ HF-3000 oscillation frequency 2
00KHZ Adjustment Voltage: 40V Grid Current: 42A Plate Current: 280A I-axis oriented film thickness: HDPE 40mm, EVA 3mm Surface tension: (based on ASTM-D2578) Wet state with standard liquid formamide ethyl cellosolve mixture After measurement, the uniaxially stretched film obtained above and a film with a thickness of 20
The EVA side of the uniaxially stretched film is used as the bonding surface of the French aluminum foil, and after being heated using the heating device 5 (infrared heater), the aluminum foil is pressed with a roll under the following conditions to form the stretched film and aluminum foil. A laminate was manufactured.

Roll 6: Diameter 200m/Skin x Medium 500/Skin silicone rubber coated Roll 7: Diameter 200m/Skin 0 x Medium 500/Skin surface hard chrome plating Double tube heating medium circulation method Crimping conditions:
Roll 7 was not heated, roll 6 was not heated, and the material was maintained at a predetermined temperature solely by child heat and heat transfer from roll 7.

Child heat temperature 71-7400 Roll surface temperature; Roll 680-86000-R7 160-1
63〃 Material temperature; Stretched film 102-112〃Aluminum foil
118-120'' Crimp speed: 7 m/mjn Roll pressure: 5k9K Peel strength test was conducted on the obtained laminate, and the results are shown in Table 1.

Table 1 *Peel strength test: 18? Peeling Test piece: medium 20 kite x length 100 enemy Tensile speed 200/min Chuck distance 50 skin The tensile direction was made to match the stretching direction.

The strength was expressed as the load at the start of peeling.

(However, the average value of measurements using 10 test pieces) Example 2 and Comparative Example 2 Commercially available HDPE (M.1.1
．． 0, density 0.960, melting point 127°C) as the central layer,
Commercially available low density polyethylene (hereinafter referred to as LDPE) is placed on both sides.
That's what it means.

M. 12.0, density 0.921, melting point 109o○) was stretched 6 times by 1 mm to make a 3-layer stretched tape, and each of the tapes (inside 6.0 side) was stretched by 32 layers. The parallel bodies arranged in parallel at intervals were stacked perpendicularly to each other and pressed lightly in about 12,000 layers of hot air to obtain a cross-laminated network (FIGS. 2 and 3) consisting of a three-layer stretched tape. Next, the surface of the net-like body was subjected to a corona discharge treatment in the same manner as in Example 1, and various net-like bodies having different surface tensions were obtained by changing the speed at which the treated body passed through the electrode surface. 3-layer stretched tape thickness: LDPE2 mu HDPE20 Yamaichi LDPE2
Furthermore, bleached kraft paper (basis weight: 72 mm/ground) was superimposed on the silk-like body obtained above, and after heating with a preheating device 5 (infrared heater), the silk-like body was pressed with a roll under the following conditions. - A laminate made of kraft paper was obtained.

Rolls: Same as in Example 1 Pressing conditions: Roll 6 is not heated and only roll 7 is heated Preheating temperature: 73-78qC Roll surface temperature: Roll 685-90〃 Roll 7 145-147'' Material temperature: Reticulated material 110 ~122〃Kraft paper
124-126 Crimp speed: 15 m/mjn Roll pressure: 5k9/skin The results of a peel strength test performed on the obtained laminate are shown in Table 2.

Table 2 *The peel strength test was conducted in the same manner as in Example 1.

Example 3 and Comparative Example 3 The high density polyethylene in Example 2 was replaced with commercially available isotactic polypropylene (
MFI. 1.5 density 0.910, melting point 167o0),
Furthermore, the low density polyethylene in Example 2 was
Propylene copolymer rubber ("Espren 806", M
Laminated layer consisting of silk material and kraft paper in the same manner as in Example 2 except that the pressure bonding conditions using the roll after the corona discharge treatment were changed. I got a body.

3-layer stretched tape thickness: ethylene/propylene copolymer
3-moist isotactic polypropylene 40 ethylene-propylene copolymer 3-roll: Same as in Example 1 Pressing conditions: Roll 6 is not heated, only roll 7 is heated Preheating temperature: 120-12900 Roll surface temperature; Rolls 6140-144 Roll 7 180-1840.

Material temperature during crimping: Reticulated material 153-160〃 Kraft paper 162-166〃 Bonding speed, roll constriction pressure: Same as in Example 2 A peel strength test was conducted on the obtained laminate, and the results are shown in Table 3. there were.

3 *The peel strength test was conducted using the same method as in Example 1.

[Brief Description of the Drawings] Figure 1 is a schematic diagram showing the manufacturing method of the present invention, Figure 2 is a stretched tape cross-laminated network of Example 2, and Figure 3 is A of Figure 2.
-A is an enlarged cross-sectional view. DESCRIPTION OF SYMBOLS 1... Sheet, 2... Base material, 3... Corona discharge device, 4.
... Guide roll, 5... Child heating device, 6... Roll on the side in contact with the sheet, 7... Roll on the side in contact with the base material, 8...
・Laminated body, 1-1, 1-1...low density polyethylene,
1-2, 1-2... High density polyethylene. Figure 1 Figure 2 Figure 3

Claims (1)

[Scope of Claims] 1. In a method of manufacturing a laminate by bonding a sheet of thermoplastic resin A to a base material, the sheet has a melting point lower than that of thermoplastic resin A (or softening made of thermoplastic resin B having a surface of 42 dynes/c
An adhesive resin layer having a surface tension γc of m or more is provided, the base material and the sheet are overlapped via the adhesive resin layer, and the thermoplastic resin is lower than the melting point (or softening point) of the thermoplastic resin A. A method for producing a laminate by press-bonding B at a temperature higher than the melting point (or softening point). 2. The method for producing a laminate according to claim 1, wherein the base material is a paper material. 3. The method for producing a laminate according to claim 1, wherein the base material is a metal foil. 4. The method for producing a laminate according to any one of claims 1 to 3, wherein at least A of the thermoplastic resins A and B constituting the sheet is a stretched sheet. 5. The method for producing a laminate according to any one of claims 1 to 4, wherein the sheet is a net-like body made of either a woven fabric or a nonwoven fabric made of a stretched thermoplastic resin. 6. The method for manufacturing a laminate according to any one of claims 1 to 5, wherein the thermoplastic resin A constituting the sheet is high-density polyethylene, and the thermoplastic resin B is low-density polyethylene. 7. The laminate according to any one of claims 1 to 5, wherein the thermoplastic resin A constituting the sheet is high-density polyethylene, and the thermoplastic resin B is an ethylene-vinyl acetate copolymer. Production method. 8. Claim 1, wherein the thermoplastic resin A constituting the sheet is isotactic polypropylene, and the thermoplastic resin B is an amorphous ethylene-propylene copolymer.
5. A method for producing a laminate according to any one of Items 5 to 5. , 9 In order to press the laminate, at least one pair of rolls is used, and the surface temperature of the roll on the side in contact with the base material is set to a temperature equal to or higher than the melting point (or softening point) of the thermoplastic resin B, so that the sheet is The laminate according to any one of claims 1 to 8, wherein the surface temperature of the contacting roll is maintained at a temperature lower than the melting point (or softening point) of the thermoplastic resin B, and the laminate is pressed. manufacturing method. 10 Out of a pair of rolls, at least the surface of the roll on the side in contact with the sheet has a cohesive energy density (CED) of 40
10. The method for producing a laminate according to claim 9, wherein the roll is made of a rubber or synthetic resin material having (cal/cc) or less.