JPH09169055A - Heat lamination method of crystalline thermoplastic resin sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of strain, deformation, breakage and sticking by heating only the vicinity of the surfaces of the adhesive layers on both sheets of a pressure laminated sheet to crystal fusion temp. or higher and further heating the same to a temp. range from crystal fusion temp. to below an m.p. to bond both sheets and subsequently cooling the laminated sheet to crystal fusion temp. or less and further cooling the same to room temp. SOLUTION: Resin sheets S1, S2 are controlled in temp. so that the temps. in the vicinity of the surfaces of the adhesive layers and non-adhesive surfaces thereof become a temp. range from crystal fusion temp. to below crystal fusion temp. and temporarily laminated by pressure bonding rollers 31, 32. The laminated sheet is allowed to fall from the pressure bonding rollers 31, 32 under its own wt. and heated to a temp. range from the crystal fusion temp. of the resin of the resin sheets to below the m.p. thereof in a non-contact state by preheating panels 43, 44 and pressed, laminated and bonded by a laminating roll 5 and a pressure cylinder 6 to be integrated. Thereafter, the laminated sheet is peeled from the laminating roll 5 by a peeling roll 83 and stepwise cooled by cooling rolls 71-73 and subsequently drawn out while nipped between a pair of discharge nip rolls 82.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat fusion laminating method for plastics, and more particularly to a heat laminating method suitable for a resin sheet of a crystalline polyolefin material.

[0002]

2. Description of the Related Art Conventionally, a method of thermally laminating a thermoplastic resin sheet such as a vinyl chloride resin sheet containing a plasticizer has been known. For example, "Public Office Official Notices and Common Techniques" (Japanese Patent Office, published June 15, 1984,
(P. 163), as a method for heat-sealing and adhering a thermoplastic resin film, there is a method in which two layers of resin films are continuously thermocompression bonded or thermocompression-bonded by a heat press for adhesion and integration. ing. Further, there is a so-called doubling embossing method in which the bonding and integration and the embossing treatment for shaping the surface of the resin film are simultaneously performed.
According to this method, the target resin film is a vinyl chloride resin, an acrylic resin, an acrylonitrile-butadiene-styrene copolymer film, or the like, but, in general, it is difficult to thermally bond the olefin resin film and the polyester. It is explained that a film or the like can be similarly heat-bonded by coating the film with a heat sealing agent in advance.

FIG. 3 is a conceptual diagram showing a device configuration of a conventional thermal laminating device (that is, a doubling embossing device) which also serves as an embossing device by such a method. Referring to the figure, the two-layer resin sheets S1 and S2 are supplied from the winding rolls 91a and 91b, respectively, and the preheating roll 92 is supplied.
a and 92b, respectively, and then heated by the heat drum 93 while being superposed on the heat drum 93 portion, and also heated by the preheat panel heater 94a and radiant heat by non-contact, and then by the preheat panel heaters 94b and 94c. While being radiantly heated, it is further heated by preheating rolls 95a to 95c whose surface is made of Teflon and made non-adhesive, and is guided between the embossing roll 96 and the impression cylinder 97,
The sheet is pressurized, embossed and integrated by laminating and adhering the two layers of sheets, and then cooled by the cooling roll 98 and wound by the winding roll 91c.

There are various other types of thermal laminating apparatus having such a structure. For example, in JP-A-57-157756, a vinyl chloride resin sheet containing a plasticizer is disclosed.
After heating only the upper base sheet after lamination with a heating drum, it is further heated to a temperature that softens the sheet by non-contact heating with a heater, while the lower base sheet after lamination is pre-embossed. There is disclosed a thermal laminating method for producing a laminated sheet having a structure in which two sheets are superposed with each other by pressurizing them so as not to return to each other and preheating them.

In Japanese Patent Publication No. 42-551, a resin sheet A of a vinyl chloride laser is softened by an infrared radiation heating device and a heating drum, and a polyester film or the like is heat-resistant and has high toughness and flexibility and is peeled off. The thin film B, which is easy to be laminated, is passed between the embossing roll and the impression cylinder so that the thin film B is laminated with the embossing to perform thermal lamination, and then the film B is peeled from the sheet A. There is also proposed a method of forming a thin blurred pattern by applying a thermal laminating method, such as indirectly embossing the unevenness of No. 2 on the surface of the sheet A through the film B.

In Japanese Patent Publication No. 2-61378,
A thermal laminating method has been proposed in which a two-layer resin sheet to be laminated is passed through a pair of thermal laminating rolls while the resin sheet having a larger thickness is preheated by a preliminary heat treatment roll before being passed through. In addition, in the same publication, as a resin to which this method can be applied, a crystalline thermoplastic resin such as polyethylene or polypropylene is cited as well as a polystyrene resin.

[0007]

However, in the above-mentioned conventional thermal laminating method, a plasticizer-containing vinyl chloride resin sheet, an amorphous thermoplastic resin sheet or the like has a wide suitable temperature range for thermal laminating and is easy to manufacture. In particular, in the case of a crystalline thermoplastic resin sheet made of a polyolefin resin such as polyethylene or polypropylene, the proper temperature range is narrow and there is a problem in thermal lamination. That is, in the crystalline thermoplastic resin sheet, in the vicinity of the melting point of the resin of the sheet, it is difficult to control the temperature because of the thermo-mechanical characteristics that the sheet suddenly softens and the strength decreases, and in the case of excessive heating,
This is because the sheet melts and causes cutting or distortion or elongation. Then, there arises a problem that the surface of the sheet becomes tacky and is not separated from the heating roller. Also, if the heating is too low, the adhesive strength between the two layers of resin sheets will be insufficient and the laminating strength will not be obtained, and if embossing is also applied, the embossing will not be easy and the heat resistance of the embossing will be low and the laminating strength will be low. Relief of residual stress and strain was also insufficient.
In the case of a sheet of a polyolefin resin such as polyethylene or polypropylene, in order to improve the adhesiveness of the surface of the obtained laminated sheet, even if corona treatment or the like is performed before thermal lamination, it is still heated. There was also a problem that the effect diminished.

[0008]

In order to solve the above problems, in the thermal laminating method of the present invention, pressure lamination is performed while paying attention to the crystal melting temperature of the resin of the two-layer crystalline thermoplastic resin sheet. Mainly, a first pressure laminating step (step (b) in each claim) as a temporary laminate and a second pressure laminating step (step (d) in each claim) as a main laminate. In the first temporary laminating step, heating is performed above the crystal melting temperature in order to develop adhesiveness only in the vicinity of the bonding surface of both sheets, and the other parts are kept below the crystal melting temperature by this step. Temporary bonding is performed while ensuring the strength of the sheet at the part, and then in the present laminating process, both sheet surfaces are made to have a desired surface state (smooth or uneven) and residual stress in both sheets is removed. To increase the adhesive strength Bonding the over bets while heating a crystalline melting temperature above to a temperature below up to the melting point, then, the following crystalline melting temperature, in the manner further cooling to room temperature,
Even if the thermoplastic resin sheet is crystalline, thermal lamination can be performed. As a result, thermal deformation and distortion of both sheets,
Both sheets can be laminated while attempting to prevent breakage and adhesion to contact parts such as guide rollers.

Further, in the above method, when both sheets are preliminarily coated with an adhesive, the one whose adhesive strength expression temperature is lower than the crystal melting temperature of both sheets is used as the adhesive. In the temporary laminating step, the bonding is performed at a temperature which is equal to or higher than the adhesive strength developing temperature and lower than the crystal melting temperature. The thermoplastic resin sheet was bonded so that it could be thermally laminated even if it was crystalline. In this case as well, both sheets can be laminated while attempting to prevent thermal deformation, distortion, breakage, and adhesion to the contact portion such as the guide roller in the same manner as described above.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION A method for thermally laminating a crystalline thermoplastic resin sheet according to the present invention will be described below with reference to the drawings.

First, FIG. 1 is a conceptual diagram showing an apparatus configuration of a thermal laminating apparatus for realizing the method for thermally laminating a crystalline thermoplastic resin sheet of the present invention. As shown in FIG.
The pressure laminating portion of the thermal laminating apparatus that can realize the present invention has a temporary laminating portion for performing the first pressure laminating and a main laminating portion for performing the second pressure laminating. The temporary laminated portion is pressed by the pressure bonding rolls 31 and 32, and the main laminated portion is pressed by the laminating roll 5 and the impression cylinder 6. The resin sheets S1 and S2 are the winding roll 1 respectively.
The supply side nip rolls 81a and 81b, which are paired with 1 and 12, feed the nip rolls 81a and 81b while feeding the nip rolls 81a and 81b. Then, in the temporary laminating portion, both the sheets S1 and S2 are heated by the heating rolls 21 and 22, respectively, on the bonding surface side thereof, and further separated from the heating rolls and the surfaces are sandwiched by the pressure bonding rolls 31 and 32 having a low temperature. The resin sheets are preliminarily laminated by the pressure rolls 31 and 32 by being heated by infrared radiation from the preheating panel heaters 41 and 42 so as not to cool before being pressure-laminated. Then, in the thermal laminating method of the present invention, during this temporary lamination, the temperature near the surface on the adhesive surface side of both resin sheets and the temperature near the surface on the non-adhesive surface side are controlled to a predetermined temperature. Become.

As described above, the two-layer resin sheet is tentatively laminated to form a laminated sheet. Next, this laminated sheet is heated to the final temperature for main lamination. Therefore, the laminated sheet discharged from the pressure bonding roll is dropped vertically from the pressure bonding roll almost by its own weight,
Immediately before reaching the laminating roll 5 and the impression cylinder 6, the preheating panel heaters 43 and 44 heat the laminated sheet to a predetermined temperature defined by the present invention without contacting the laminated sheet, and the laminating roll 5 and the impression cylinder 6 are heated. By applying pressure, stacking, and adhering to integrate. Therefore, the laminate roll 5 and the impression cylinder 6 (nip surface thereof) of the main laminate have a structure located directly below (the nip surface of) the pressure rolls 31 and 32 of the temporary laminate. That is, the direction of the sheet's own weight (gravity) has only a component in the sheet conveying direction, and has no component orthogonal to the sheet and deforming it. Also, it does not receive any force from the rollers or the like. As a result, even if the laminated sheet is temporarily adhered in a unstable state due to a decrease in elastic modulus due to being heated to a temperature higher than or equal to the crystal melting temperature and lower than the melting point immediately before the main lamination, the main lamination can be stably performed from the temporary lamination part. It will be possible to transfer and transfer to the part. On the other hand, for example, in the conventional thermal laminating apparatus shown in FIG. 3, the crystalline thermoplastic resin sheet is meandered by the preheating rolls 95a to 95c by contact heating or stretched by the tension, and in this respect as well. The structure was impossible to process.

After that, the laminated sheet is peeled off from the laminating roll 5 by the peeling roll 83, and is gradually cooled by the cooling rolls 71 to 73, and is then drawn out and wound while being nipped by the pair of discharge side nip rolls 82. It is wound up on a roll 13.

The above is an example of a thermal laminating apparatus that can be used in the thermal laminating method of the present invention. In this apparatus, unlike the conventional thermal laminating apparatus, the adhesive surface side and the non-adhesive surface side of the resin sheet to be laminated are Both surfaces can be separately heated and controlled, and there is a large difference in that there is a two-stage pressure laminated portion. For example, in the conventional thermal laminating apparatus shown in FIG. 3, the heating surfaces of the various preheating rolls and preheating panel heaters for the sheets are not those for heating the bonding surface side in particular, and mainly because of the ease of the apparatus structure. It is the front surface of the laminated sheets (for example, the preheating roll 92a for the sheet S1, the preheating panel heaters 94a to 94c, and the preheating rolls 95a to 95c). The only one on the adhesive surface side is the preheating roll 92b for the sheet S2.

In the thermal laminating apparatus shown in FIG. 1, the heating rolls 21 and 22 are metal rolls having hollow interiors, such as iron and copper, and heat transfer media such as oil and water (steam) in the air core. Temperature is controlled by circulating or by dielectric heating. The roll surface may be chromium-plated in consideration of corrosion resistance or may be coated with a fluororesin in consideration of releasability. The heating rolls 21 and 22 contact the adhesive surfaces of the two-layer resin sheets to be laminated and heat the adhesive surface side to a higher temperature than the non-adhesive surface side. Note that a non-contact heating heater described below can be used instead of such conductive heating by contact. The preheating panel heaters 41 and 42, and further the preheating panel heaters 43 and 44 are heating wire heaters that radiate near infrared rays to far infrared rays, electrothermal infrared radiation heaters such as ceramic heaters, or dielectric heating using a high frequency AC electric field. Or blowing hot air, or YAG laser,
The heating and adjustment can be easily performed by heating without contact such as irradiation with an infrared laser beam such as a carbon dioxide gas laser. It is preferable that the heaters 41 and 42 immediately before the temporary lamination are heating wire radiant heaters, hot air blowing, or infrared laser pulse irradiation from the viewpoint of heating only the vicinity of the adhesive side surface of the sheet. Further, the heaters 43 and 44 immediately before the main lamination are preferably a ceramic electric heater that radiates far infrared rays and a dielectric heater from the viewpoint of uniformly heating the entire sheet thickness direction. Similarly to the heating rolls 21 and 22, the pressure bonding rolls 31 and 32 are metal rolls having a hollow interior, and oil inside the air core,
A heat transfer medium such as water (water vapor) is circulated, or the temperature is controlled by dielectric heating. However, it is preferable to coat the surface of one roll with a rubber-like elastic material such as silicone rubber.

The laminating roll 5 is a hollow metal roll, and its surface is mirror-finished by chrome plating or the like when it is not embossed. In the case of embossing, that is, in the case of an embossing roll, a surface having a desired uneven pattern is used by a method such as etching or engraving with or without copper plating. Alternatively, as the embossing roll, a roll surface layer made of resin or ceramics and subjected to laser engraving, or a plate made by plating a metal such as copper on a mold having a desired uneven pattern by electroforming can be used. . In addition, the uneven pattern is a wood grain conduit,
Examples include skin prints, grain, satin, hairline, and cloth. Impression cylinder 6
Is a hollow metal roll whose surface is covered with a rubber-like elastic material such as a silicone rubber layer and whose temperature is controlled by circulating hot water in the air core. And the cooling rolls 71 to 7
3 is a roll having a structure in which a low-temperature heat transfer medium such as cold water is circulated in a hollow roll made of a material having a high thermal conductivity such as metal. Alternatively, cooling may be performed by contact with a heat pipe. Further, cold air may be blown together.

If a coating device is provided between the cooling with the cooling roll in the thermal laminating device and the winding with the winding roll, the thermal laminating and the coating can be simultaneously performed online. . As the coating device, for example,
Various web coaters such as a gravure coater, a roll coater, and a comma coater may be used, and a drying zone may be provided if necessary. In addition, before the coating device, or even when the coating device is not provided, the surface of the laminated film after lamination may be modified by corona treatment in order to improve water wettability and adhesion performance. .

Next, the resin sheet suitable for the thermal laminating method of the present invention is made of a thermoplastic resin, and particularly a sheet made of a crystalline thermoplastic resin exhibits excellent suitability. Examples of these crystalline thermoplastic resins include polyethylene, polypropylene,
It is effective for polyolefin resins such as polybutene and polymethylpentene, linear polyamides such as nylon 6 and nylon 66, and polyester resins such as polyethylene terephthalate and polybutylene terephthalate.
In addition, polyvinyl chloride resin, acrylic resin, etc. are also effective. The thickness of the resin sheet is usually 10
It is about 500 μm.

The crystal melting temperature, which is the term used in the method for thermally laminating the crystalline thermoplastic resin sheet of the present invention, will be described. Generally in the case of pure crystals, the crystal melting temperature at which the solid state changes to the liquid state is a physical quantity that can be uniquely defined as the melting point. However, in the case of an ordinary crystalline polymer substance composed of a flexible molecular chain,
The solid state consists of an amorphous region and a crystalline region (microcrystal), and these microcrystals are in various aggregate states with different stable states due to various sizes, various internal defects, etc. , A crystalline (thermoplastic) polymer does not have a clear melting point like pure crystals, but shows a melting point with a certain spread. Therefore, the peak temperature during thermal analysis such as differential thermal analysis (DTA) or differential scanning calorimetry (DSC) is the melting point. Further, although there may be a plurality of peaks, in this case, the main peak may be treated as the melting point in the method of the present invention. And, there is a skirt area in the peak, which shows that some of the microcrystals in the sample cause melting of the crystal at a temperature below the temperature of the main peak. The temperature at which the melting of the microcrystals starts, that is, the extrapolation melting start temperature is regarded as the crystal melting temperature in the present invention.

The above is a premise of thermal analysis.
The same can be said with respect to the relationship between temperature and mechanical properties (for example, elastic modulus E). This is illustrated in FIG. FIG. 2 is an explanatory diagram comparing the thermal lamination method of the present invention in which the temperature control of the resin sheet is focused on the crystal melting temperature and the like with the conventional thermal lamination method in terms of the elastic modulus of the resin and the temperature. In the figure, the horizontal axis is temperature T and the vertical axis is elastic modulus E. The curve designated by Ccrys is the curve of the crystalline thermoplastic resin, and the curve designated by Camor is the curve of the amorphous thermoplastic resin. It is shown conceptually. In the amorphous thermoplastic resin, the elastic modulus decreases as a temperature rises due to a step near the glass transition point Tg, and then gradually decreases, and the degree of decrease of the elastic modulus increases and the melting point T increases.
m or pour point (Tm) drops sharply. In order for the resin sheet to be heat-laminated, appropriate adhesiveness and mechanical strength are required. As a result, the elastic modulus is between the proper upper limit elastic modulus of processing Eu and the proper lower limit elastic modulus of processing El. There is a proper processing elastic modulus range ΔE. On the other hand, in the case of the crystalline thermoplastic resin Ccrys, the elastic modulus decreases with a rise in temperature with a slight step at the glass transition point Tg, and then gradually decreases, and the fine crystals progress to melt. At the same time, the elastic modulus drops sharply, and the elastic modulus drops most at the melting point, and then fluidizes. The degree of decrease in the elastic modulus in the proper processing elastic modulus range ΔE is steeper than that of the amorphous thermoplastic resin, so that the appropriate processing temperature range ΔTc of the crystalline thermoplastic resin is
rys is a proper processing temperature range ΔTa of the amorphous thermoplastic resin.
It is narrower than mor, and this is the reason why the crystalline thermoplastic resin sheet cannot be processed by the conventional thermal laminating apparatus.

Therefore, in the method for thermally laminating a crystalline thermoplastic resin sheet according to the present invention, an appropriate processing temperature range ΔTcr of a crystalline thermoplastic resin that realizes an appropriate processing temperature range ΔE is obtained.
Even if it deviates from ys, in order to perform thermal lamination without problems,
In order to heat the resin sheet of at least two layers until it develops tackiness and can be temporarily fixed (it is not necessary to have the final laminating adhesive strength), the temperature at which the microcrystals start melting is equal to or higher than the crystal melting temperature. Then, only the surface near the bonding surface is heated to perform temporary lamination. The temperature on the non-bonding surface side, which is not related to bonding, is kept below the crystal melting temperature without raising the temperature so that the strength of the resin sheet can be maintained. Therefore, even if the temperature in the vicinity of the surface of the adhesive surface rises above the melting point and fluidity appears, the non-adhesive surface (rear surface) is below the crystal melting temperature and has sufficient strength.
Because it is a two-layer composite, the sheet does not deform significantly. On the other hand, even if the vicinity of the surface of the adhesive surface is lowered below the crystal melting temperature, for example, the insufficient adhesive force is eliminated in the subsequent main laminating step. As a result, the proper processing temperature range of the laminate is substantially expanded. In addition, heating the vicinity of the surface of the non-adhesive surface, which is lower than the crystal melting temperature, assists heating on the adhesive surface side, and also serves as preheating for the next main laminate.

Then, after the temporary lamination is completed as described above, after that, in order to remove the thermal strain and the like of the entire laminated sheets and to obtain the final lamination strength,
(For embossing in the case of embossing), the entire laminated sheet is heated to the crystal melting temperature or higher. Also at this time, the temperature is lower than the melting point to prevent the entire laminated sheet from breaking, deforming, and sticking to the guide roller. After that, it is cooled to room temperature as in the conventionally known thermal lamination.

As described above, performing pressure lamination in two stages has the advantage that it can be manufactured more stably than performing it in one stage. If one step is to be performed, for example, in FIG. 1, when the preheated two-layer resin sheet is supplied between the laminating roll 5 and the impression cylinder 6, the other sheet is transferred from the right side to the other side. Sheets must be fed from the left and diagonally. However, the mechanical strength of the preheated crystalline thermoplastic resin sheet is weak and unstable, so if the sheet is fed obliquely, it will sag due to its own weight unless it is fed with tension, and if it is fed with tension, it stretches. Breaks. After all, it is necessary to supply a two-layer sheet from directly above, and if two-layer sheets are adjacently supplied, the sheet preheated due to the flapping of the sheet may be abruptly adhered due to adhesion, which is not stable. . Therefore, it is necessary to consciously and stably adhere the two layers of sheets (temporarily) and then supply the sheets between the laminating roll and the impression cylinder.

Further, according to the method for thermally laminating a crystalline thermoplastic resin sheet of the present invention, thermal lamination is possible even if a heat-fusible adhesive layer is not formed on the adhesive surfaces of the two layers of resin sheets to be laminated. However, the method of the present invention described above can be extended even when the heat-fusible adhesive layer is formed. That is, paying attention to the adhesive force expression temperature of the heat-fusible adhesive layer and the crystal melting temperature of the resin of the resin sheet portion other than the heat-fusible adhesive layer, the vicinity of the surface on the adhesive side is the adhesive force of the former. At the temperature above the expression temperature, the vicinity of the surface on the non-adhesive surface side is set below the crystal melting temperature of the latter so that the first temporary lamination is performed. The subsequent main lamination may be carried out by heating both layers of both sheets laminated at a temperature not lower than the crystal melting temperature of the resin of the resin sheet and not higher than the melting point, as in the above. In this case, the heat-fusible adhesive may be any conventionally known adhesive such as an adhesive for dry lamination as long as it is an adhesive that exhibits heat-fusible properties and is not particularly limited. Further, there is no problem if the adhesive force expression temperature is higher than or lower than the crystal melting temperature of both sheets. Thus, the crystalline thermoplastic resin sheet on which the heat-fusible adhesive layer is formed can be regarded as a crystalline thermoplastic resin sheet having a two-layer structure from the beginning, instead of a single layer. It suffices to perform thermal lamination by paying attention to thermal characteristics such as melting temperature and melting point.

[0025]

EXAMPLES The thermal laminating method for the crystalline thermoplastic resin sheet of the present invention will be described below with reference to examples.

Using a thermal laminator having a structure as shown in FIG. 1, two layers of polypropylene resin sheet (crystal melting temperature 130 ° C., melting point 176 ° C.) made of polypropylene are prepared and supplied as a strip-shaped continuous sheet from winding. Then, thermal lamination was performed. The surface temperature of the heating rolls 21 and 22 is 1
40 ° C. is set higher than the crystal melting temperature, the surface temperature of the pressure bonding rolls 31 and 32 is set to 95 ° C. lower than the crystal melting temperature, and the preheating panel heater 4 is used.
1 and 42 radiate an appropriate amount of infrared rays to prevent cooling from leaving the contact of the heating roll until the two-layer sheet is pressure-bonded by the pressure roll. The surface temperature of the adhesive surface of both sheets immediately before pressure bonding by the pressure rollers 31 and 32 is set to 1
The surface temperature of the non-contact surface is kept at 40 ° C and 95 ° C. The laminated sheet having undergone the temporary laminating step as described above is dropped vertically between the pressure bonding rolls 31 and 32 and guided between the impression cylinder 5 and the laminating roll 6 for the next main lamination. At that time, the laminated sheets that have been temporarily adhered are heated from both sides by infrared radiation by different preheating panel heaters 43 and 44, and this time the surface temperature of both sides is set to 170 ° C. which is higher than the crystal melting temperature and lower than the melting point. After the adjustment, the laminated sheet is inserted between the laminating roll 5 and the impression cylinder 6 immediately after heating, and the main lamination is performed. The surface temperature of the laminating roll and the impression cylinder is set to 60 ° C., and then cooled to room temperature by the cooling rolls 71, 72 and 73. The surface temperature of the cooling roll is 40 ° C., 30 ° C., and 25 ° C. from the upstream side closer to the laminating roll. The sheet feeding speed was 25 m / min.

The components of the thermal laminator used above are as follows. Heating rolls 21 and 2
2 is a hollow iron roll whose surface is chrome-plated, and heats the inside of the air core through high-pressure steam. Crimping rolls 31 and 32
One has a structure in which a hollow iron roll with a surface chrome plating heats the air core through hot water, and the other one coats the surface of the hollow iron roll with a silicone rubber layer and heats the inside of the air core through hot water. Next, the preheating panel heaters 41 and 42
Is a Nichrome wire electric heater, and is also a preheat panel heater 4
Reference numerals 3 and 44 respectively use electric heating type ceramic surface radiant heaters, which are heated by radiant heat.
Further, the laminating roll 5 is an iron core roll having an air core, and the surface thereof is plated with chrome and finished to have a mirror surface. Heat by circulating hot water in the air core. Further, the impression cylinder 6 covers the surface of an air-core iron roll with a silicone rubber layer having a hardness of 50 °,
The air core has a structure in which hot water is circulated for heating. The cooling rolls 71 to 73 are air-core iron rolls whose surfaces are mirror-finished by chrome plating, and have a structure for cooling the inside of the air-core by passing cold water.

[0028]

EFFECTS OF THE INVENTION According to the present invention, a thermoplastic resin sheet having crystallinity such as a polyolefin material can be efficiently provided with sufficient adhesive force without applying a heat-fusible adhesive to the resin sheet. It is possible to carry out lamination (and embossing if necessary) at high speed while preventing distortion, deformation, breakage of the sheet and adhesion with the guide roller. Also,
Less affected by variations in processing conditions, especially sheet heating conditions. Further, even when a resin sheet having a heat-fusible adhesive applied to the resin sheet is used, the temperature in the vicinity of the non-adhesive surface of the resin sheet is below the crystal melting temperature regardless of the adhesive force expression temperature of the adhesive. Since the temporary laminating step is performed, the effect of preventing distortion, deformation, breakage of the sheet, and adhesion to the guide roller and the like is particularly high. Further, in the present laminating step, since heating is performed at a temperature higher than the crystal melting temperature and pressure is applied, the adhesive force between both resin sheets is not reduced and residual stress (strain) does not occur.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing an example of a device configuration of a thermal laminating device capable of realizing a thermal laminating method for a crystalline thermoplastic resin sheet of the present invention.

FIG. 2 is an explanatory diagram comparing the thermal laminating method of the present invention in which the temperature of a resin sheet is controlled by paying attention to the crystal melting temperature and the like and the conventional thermal laminating method in terms of the relationship between the elastic modulus of the resin and the temperature.

FIG. 3 is a conceptual diagram showing an example of a device configuration of a thermal laminating device for performing a conventional method for thermally laminating a thermoplastic resin sheet.

[Explanation of symbols]

 11-13 Winding roll 21, 22 Heating roll 31, 32 Pressure bonding roll 41-44 Preheating panel heater (non-contact heating) 5 Laminating roll (or embossing roll) 6 Impression drum 71-73 Cooling roll 81a, 81b Paper feeding side Nip roll (pair) 82 Paper discharge side nip roll (pair) 83 Peeling roll 91a to 91c Winding roll 92a, 92b Preheating roll 93 Heat drum 94a to 94c Preheating panel heater (non-contact heating) 95a to 95c Preheating roll 96 Embossing roll 97 Impression cylinder 98 Cooling roll Ccrys Crystalline thermoplastic resin Camor Amorphous thermoplastic resin E Elastic modulus Eu Machining appropriate upper limit elastic modulus El Machining proper lower limit elastic modulus ΔE Suitable machining elastic modulus range Tc Crystal melting temperature Tg Glass transition temperature Tm Melting point or Flow temperature ΔTcrys Crystalline thermoplastic Proper processing temperature range of proper processing temperature range ΔTamor amorphous thermoplastic resin of the resin S1 sheet 1 S2 sheet 2

Claims (2)

[Claims] 1. A thermal laminating method for laminating and adhering two layers of crystalline thermoplastic resin sheets by thermal fusion bonding, comprising: (a) forming a thermally fusible adhesive layer on each adhesive surface of the resin sheet. Without forming the two-layer resin sheet, the vicinity of the surface of each adhesive surface is above the crystal melting temperature of the resin of the resin sheet, and the vicinity of the surface of each non-adhesive surface is the crystal melting of the resin of the resin sheet. (B) Next, the two-layer resin sheet is pressure-laminated from both sides in such a direction that the adhesive surfaces face each other, and (c) then the two-layer resin sheet is heated. Both layers of the sheet are heated together to above the crystal melting temperature of the resin of the resin sheet and below the melting point, (d) then the two-layer resin sheet is pressed from both sides, and the two-layer resin sheet Is cooled to below the crystal melting temperature, and (e) then the two-layer resin sheet is brought to room temperature. In cooling, characterized by comprising the steps, the crystalline thermoplastic resin sheets thermally laminated methods. 2. A thermal laminating method for laminating and adhering two layers of crystalline thermoplastic resin sheets by heat fusion, which comprises: (a) the resin sheet having an adhesive force developing temperature on each adhesive surface of the resin sheet. A resin having a heat-fusible adhesive layer having a temperature lower than the crystal melting temperature of the resin is prepared, and the resin sheet of the two layers is formed such that the adhesive surface temperature of each adhesive surface is equal to or higher than the adhesive force expression temperature of the adhesive. Also, heating is performed so that the vicinity of the surface of each non-adhesive surface becomes lower than the crystal melting temperature of the resin of the resin sheet, and (b) then, the two-layer resin sheet is oriented so that the adhesive surfaces face each other. (C) Next, both layers of the two-layer resin sheet are heated to above the crystal melting temperature of the resin of the resin sheet and below the melting point, and (d) The two-layer resin sheet is pressed from both sides, and the two-layer resin sheet is crystallized. Cooled to below the temperature, (e) Next, the resin sheet of the second layer is cooled to room temperature, characterized by comprising the steps, the crystalline thermoplastic resin sheets thermally laminated methods.