JPS6040477B2 - Thermal adhesive film adhesive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a film adhesive suitable for thermal bonding between polyolefin materials and materials made of glass, metals, or polar polymers.

Film adhesives have the following advantages compared to wet adhesives that use solutions or dispersions in solvents.

■ Process is labor-saving.

Processing cost is low. ■ It is possible to cut out a mold according to the shape of the material to be adhered and to partially punch out the part loading section. There is no adhesive tangle-up, the quality of the bonding process is excellent, and the workability is good. Collecting the removed adhesive is an effective way to conserve resources. ■ Good work environment with no solvent discharge and no pollution. ■ Adhesive thickness is uniform and stable adhesion can be obtained. Hot melt extrusion is the most preferable method for making thermal adhesive into a film because it is easy to work with and has low production costs, but extrusion has problems with the ability to feed the resin from the hopper to the screw (liquids and adhesives cannot be used), The performance requirements for raw materials such as melt viscosity characteristics and thermal stability are severe, and the raw materials that can be extruded are severely limited. For this reason, although film-form thermal adhesives are expected to have many advantages as mentioned above, only adhesives can be produced by extrusion. Adhesive performance is extremely poor, and improvement is strongly desired. Polyamide or olefin copolymers are used as film adhesives by extrusion, but there are limits to the materials that can be individually bonded.

An example is shown in Table 1. It is difficult for film adhesives to bond different materials together, and there is no adhesive that can thermally bond polyolefin materials to glass, metals, and polar polymers. Even when resins are mixed to improve the adhesion properties of extrusion heat-adhesive resins, the compatibility between the resins is poor and the mechanical properties are drastically reduced, or the adhesion of each resin decreases due to mixing, making it impossible to obtain good results. do not have. Furthermore, when extruding polyamide with a low melting point, there are problems with sticking to the cooling drum and blocking after winding up. For this reason, the process is complicated and the manufacturing cost is high because it is extruded onto Shigeru paper. Combining resins by melt extrusion has already been carried out, and for example, there are many reports on composites of nylon and polyolefin, but all of them are related to packaging containers or packaging films, and some even mention thermal adhesive applications. I can't find anything.

Table 1 Adhesion of polyvinyl chloride and polyethylene using various adhesives K The composite forms of nylon that have already been proposed are nylon 6 (melting point 21yo) and nylon 66 (melting point 260°C)
, nylon 11 (melting point 186°C), nylon 610 (melting point 2170) and other high melting point homonylons.

In addition, although there are cases where copolymerized nylon is proposed, there are few that specifically explain the copolymerization composition, and nylon 6/6
6-san polymer, go-caprolactam, 3-aminomethyl-
The only thing that can be seen is a copolyamide of 3,5,5-trimethyl-cyclohexylamine and isophthalic acid. Even if such a composite material of nylon and polyolefin is used for thermal bonding, the melting point of nylon is as high as 175q0 or higher, and for polyolefin-based adherend materials with a melting point of 160°C or lower, the temperature will exceed the heat deformation temperature of the material and warp. Such deformation causes softening, etc., making it unusable for a wide range of applications.
In addition, such nylon has poor adhesion and cannot provide strong adhesive strength. The present invention combines the adhesive properties of a specific crystalline polyamide with a melting point of 170 qo or less and a specific olefin copolymer, as well as the effects of a composite of the two, which has not been achieved with conventional film-like thermal adhesives. It enables thermal bonding between polyolefin materials and glass, metals, and polar polymer materials.

There is no adverse thermal effect on the materials to be bonded during thermal bonding. Furthermore, the process of forming a film using polyamide with a low melting point is much easier than coextrusion, and a strong bond is formed between the polyamide and the olefin copolymer during the film forming process, resulting in stable adhesion when used for hollyhock. can be obtained. The present invention has a melting point of 17
This is a film adhesive made by laminating by coextrusion a crystalline polyamide of 000 or less and a copolymer obtained by graft polymerizing an unsaturated carboxylic acid with a polyolefin as a backbone.

The polyamide used in the present invention has a melting point of 170 degrees or less and has the following polymer composition. A crystalline nylon copolymer having a melting point of 17 pi or less and having at least three or more types of structural units selected from the following group of polymer structural units.

[NH (C ratio) nCO]

n is a positive integer from 5 to 11 [NH (C ratio) 6NHC○ (C is) mCO] m is 4 to 1
Positive integer of 2'o} Nylon 12, 70-9 weight%
and nylon 6, 10-3% by weight English polymer.

The above polyamides can be made from lactams and/or nylon salts, such as:

Nylon 6/66/61G polymer, nylon 6/66
/11 copolymer, nylon 6/66/12 copolymer, nylon 6/66/610/11 copolymer, nylon 6/
66/610/IZ polymer, nylon 6/66/61
2 copolymer, nylon 6/69/12 copolymer, nylon 6/612/12 copolymer, and the like.

Examples of copolymer compositions preferably used in such copolymers include those shown in Table 2. Table 2 Each polyamide used in the present invention can be used as a blend within the same type or as a mixture between different types.

Furthermore, various additives and polymers can be used in combination within the range that does not significantly change the properties of the polyamide. The copolymer used in the present invention, in which a polyolefin is used as a backbone and an unsaturated carboxylic acid (including derivatives) is graft-polymerized, has the following polymer composition.

The main polyolefin is polyethylene, polypropylene, a polymer of ethylene and propylene, or a copolymer of ethylene or propylene and butene-1, to which, for example, the following monomers are grafted.

maleic acid, itaconic acid, acrylic acid, methacrylic acid,
Derivatives of these unsaturated carboxylic acids (acid anhydrides, erthers, amides, imides, metal salts, etc.).

The melting point of such an olefin copolymer is 17 points or less.

Various additives can be added to such olefin copolymers to improve thermal behavior, adhesive performance, and cold resistance.

Various waxes, tackifiers (rosin compounds, terbene resins, etc.), various polymers (polypropylene, polyethylene, copolymers of ethylene and propylene, polyptene,
copolymer of ethylene or propylene and butene-1,
polybutene, polyptadiene, chlorinated polyethylene, etc.). Note that when the shoulder of the film adhesive of the present invention is collected and used, both resins are slightly mixed with each other, but this does not adversely affect the adhesive performance.

In the present invention, coextrusion of polyIJ amide and olefin copolymer can be carried out by the following method.

A method that uses multiple extruders to compound the polymer inside the polymer tube from the extruder cylinder to the die. A method in which each resin is directly composited after being discharged from the dies of two extruders.

In the present invention, if a film is formed so that the polyolefin copolymer is in contact with the surface of the casting drum, the olefin polymer becomes a mold layer and can solve the problem of adhesion.

The temperature of the cooling drum is preferably 80° C. or lower in order to improve the cold resistance of the olefin copolymer. The crystalline copolyamide used in the present invention may be crystallized depending on the cooling and heating temperature during the manufacturing process, heat treatment after rolling up during manufacturing, or depending on the standing conditions after rolling up. can.

When crystalline polyamide is crystallized so that the latent heat of crystal fusion is 1.5 calories or more, the slipperiness of the polyamide surface improves, and the stiffness of the film increases.
Post-processability of film formation including unwinding and slitting and bonding workability are improved. As mentioned above, adhesive films can be handled as planar objects that have self-supporting properties compared to liquid adhesives, but a particularly great feature is that they can be punched or die-cut. The essential requirements for increasing the precision in such processing are good slipperiness on the polyamide surface and high stiffness of the film. When selecting a combination of polyamide and polyolefin polymer to be combined in the present invention, it is preferable to select materials so that the properties of both, such as melting temperature and melt flow characteristics, are aligned within preferable conditions.

For example, the melting temperature is preferably 70 qo or less because thermal bonding is often easier when the difference between the two is smaller. The film adhesive of the present invention is used for thermal bonding of polyolefin materials and materials made of glass, metals, and gutter polymers.

The polyolefin material is made of polyolefins such as polyethylene, polypropylene, ethylene copolymer, and propylene copolymer. Various fillers may be used for reasons such as flame retardancy, ease of waste incineration, and high-frequency welder adhesion. Hildebr polar polymer
It has a solubility parameter index of 9 or more proposed by Ben et al., for example, the following. Polychlorophrene, acrylonitrile ptadiene rubber, polyvinyl acetate, alkyl (meth)acrylate polymer, polyvinyl chloride, polycarbonate, polyurethane, polyvinylidene chloride, urea resin, melamine resin, epoxy resin, phenol resin, polyester resin .

Polyolefin materials are being used as a component of structural materials for buildings, automobiles, railroad cars, electrical equipment, etc. because they are inexpensive, have good hygiene safety, and can be easily molded into curved surfaces. However, polar materials are often used by laminating and combining them, and the film adhesive of the present invention fully exhibits its functions in such uses.

4. Thermal bonding involves physical processes such as the resin layer softening and melting due to heating, dripping onto the surface of the object to be adhered to, or the adhering material diffusing and penetrating into the voids, melting and mixing of the adhesive and the adhering material, and mutual diffusion. Adhesion is also promoted with the aid of the protective effect. As a heating method, a heat transfer heating method using a hot plate, hot air, etc., a radiation heating method using an infrared heater, a high frequency welding method, an ultrasonic method, etc. can be adopted.

In the case of the high frequency welding method, the olefin copolymer layer of the composite film of the present invention does not generate heat directly, but the polyamide layer generates heat, and the olefin polymer layer is heated by the heat transfer. Utilizing this effect enables high-frequency welder bonding of structures containing olefin materials, which has been difficult in the past, but the heat generated by the polyamide layer requires a sufficient amount of heat to melt the olefin polymer layer. The high frequency welding method has the following features that cannot be achieved with other thermal bonding methods. The ability to perform high-frequency welding processing is an essential requirement for a general-purpose adhesive film. The high-frequency welder method can generate heat directly from within the adhesive film without requiring heat transfer from the adherend, resulting in high welding speed and high work efficiency.

Processing can be done by only heating the adhesive interface between the adhesive film and the adherend, so there is no need to overheat the adhesive material.
Heat damage to adherends can be prevented. If the adherend material is a thermally poor conductor, thick, or susceptible to thermal damage, using the heat transfer heating method will cause problems such as long processing time and material damage, but the high frequency welding method has these problems. can be solved all at once. In the case of heat-welding materials with low dielectric loss, processing using the high-frequency welding method results in significantly less damage, which is overwhelmingly superior to the heat conduction heating method. Example 1 Nylon 6/610/66/12 copolymer (30
/ Shigeru / 12/20 (wt%) crystalline copolymerized polyamide with a melting point of 115 qo and an olefin copolymer with a melting point of 160°C made by grafting 2 wt% of maleic anhydride onto polypropylene in a die using two extruders. Films were formed using the direct composite method described above at a film forming temperature of 230°C so that the copolyamide layer had a thickness of 40 μm and the olefin polymer layer had a thickness of 40 μm.

A casting method using a cooling drum in which 3,000 ml of water was circulated was adopted, and the olefin polymer was extruded so as to be on the cooling drum side.

During the film forming process, there was no adhesion of the extruded resin to the casting drum or peeling between the two resin layers, and the work could be carried out smoothly. Although the composite film was rolled up onto a paper tube, there was no blocking between the films. Using the composite film, a polyurethane foam was applied to the copolyamide side, and a polypropylene sheet with a filler added to the olefin copolymer side to improve the apparent heat softening temperature was applied, and they were thermally bonded at 165q0 using a thermocompression bonding method.

A single-layer film of the copolyamide of this example or a single-layer film of the olefin copolymer of this example were similarly bonded and compared.

The adhesive strength of each interface of the adhesive composite product was determined by the peel method at an angle of 900, and the results are shown in Table 3. The film adhesive according to the present invention was able to firmly adhere polyurethane foam and polypropylene sheet, but the adhesive using a single layer film of each resin was unable to bond both materials. In addition, a single-layer film of a copolyamide and an olefin copolymer was used in combination, but it had the following problems compared to a composite product made by single coextrusion, and could not be put to practical use. When cutting out adhesive to match the shape of the adherend, it was difficult to align both films during use, making the process virtually impossible.

{B' When continuous bonding is performed while unwinding thermal adhesive from a roll, two unwinding sections are required, and the device mechanism must be devised to combine both films, resulting in high equipment costs and poor workability. Moreover, wrinkles tend to form when the two films are combined, making it difficult to obtain stable adhesion.

Table 3 The film adhesive and adhered materials of this example are abbreviated as follows.

Copolymerized boryamide AMD, olefin copolymer-OL
F, polyurethane foam-UF, polypropylene sheet-PP〆 indicate a peeling interface. Example 2 In Example 1, the composite adhesive film was subjected to die cutting including partial punching for partial thermal bonding.

In the composite adhesive film, the crystalline state of the copolyamide was changed depending on the processing conditions after film formation.

The results are shown in Table 4, and it can be seen that the state of silk crystal collapse of the copolyamide had a great influence on workability.

When the latent heat of crystal fusion was less than 1.5 calories/night, it was virtually impossible to work. Table 4 Results of Example 2 When the tensile Young's modulus of each treated film was measured,
In Table 4, the film marked ■ was 5k9/metal, while the film marked ■ was 65k9/pine.

Example 3 Using the composite adhesive film of Example 1 and the composite film of the comparative example below, polyurethane foam (surface coated with polyester cloth) was added to the polyamide side and filler was added to the olefin copolymer layer side. A polypropylene sheet was applied and bonded using a welder mold using a high-frequency welder method, followed by blind processing and bonding.

The adhesive film of the comparative example was made of a base of polyamide resin 10 with a softening point of 135 qo obtained from hexamethylene diamine and oleic acid and azelaic acid, and a softening point of 86°C.
A composite film was formed by directly combining a mixture of 15 parts of the ethylene/acrylic acid copolymer and the olefin copolymer of Example 1 in a die to form a polyamide layer of 40 m and an olefin polymer layer of 40 r. did.

The polyamide mixture had a melt viscosity of 4 and was quite difficult to form into a film. Table 5 Peel test results of the adhesive of Example 3 Peel strength / Freight voltage: 0
．． 4A Current application time: 6 seconds Cooling time: 10 seconds ■ Melt viscosity of boryamide Boryamide of Example 1 1,100 boise (210°C)
When the adhesive film of Boryamide 45 Boise (210°C) Example 1 of the comparative example was used, the same adhesive strength as that of Example 1 was obtained, but the adhesive film of the comparative example had a small adhesive strength and was not suitable for practical use. I couldn't do that.

The polyamide layer of the comparative example had a small heat generation value and could not sufficiently melt the olefin copolymer layer, and the polyamide's melt viscosity caused the polyamide to penetrate into the polyurethane layer or flow around the welder mold, causing adhesion. The reason for this is thought to be that the layer could not be maintained. In addition, a composite film was produced in the same manner by replacing the olefin copolymer layer of the comparative example with a mixture of 10 parts of ethylene/acrylic acid copolymer and 9 parts of ethylene/vinyl acetate copolymer (vinyl acetate content 20%). However, although high frequency welding was performed under the same conditions, the adhesive performance could not be improved.

Claims (1)

[Scope of Claims] 1 (A) A crystalline polyamide with a melting point of 170°C or less selected from the following groups (1) and (2); and (1) a crystalline polyamide selected from the following group of polymer structural units: Nylon copolymer having at least three types of structural units [NH(CH_2)n
CO] n is a positive integer from 5 to 11 [NH(CH_2)_6NHCO(CH_2)mCO]
m is a positive integer from 4 to 12 (2) Nylon 12, 70 to
A copolymer (B) of 90 wt% and 10 to 30 wt% of nylon 6, a copolymer obtained by graft polymerizing an unsaturated carboxylic acid (including derivatives) with a polyolefin as a backbone, is laminated by coextrusion, and the polyamide is crystallized. The latent heat of fusion is 1.
A film adhesive for thermal bonding between a polyolefin material and a material made of glass, metal or polar polymer, characterized in that it is crystallized to have a concentration of 5 calories/g or more.