JPH0359086B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a graft modified product and a heat-sensitive adhesive using the same. More specifically, the present invention relates to a novel graft modified product exhibiting excellent adhesive properties under mild bonding conditions and a heat-sensitive adhesive using the same. Recently, polyethylene, polypropylene, polystyrene, rigid, semi-rigid or flexible polyvinyl chloride, ethylene-vinyl alcohol copolymer,
Synthetic resin base materials such as polyester and polyamide,
Laminates of smooth substrates such as metal substrates such as aluminum plates and steel plates, or laminates of these smooth substrates and porous substrates such as paper, wood, and synthetic resin foam are widely used. There is. Among these laminates, heat-sensitive adhesives are still used when bonding base materials that are relatively easy to adhere to, but polyolefin, soft polyvinyl chloride, ethylene-vinyl alcohol, etc. are also used as smooth base materials. When using polymers, polyesters, polyamides, etc., there are few heat-sensitive adhesives that exhibit sufficient adhesive strength to bond them.
Currently, it is unavoidable to surface-treat the base material and then use a solvent-based adhesive to adhere it. In addition, heat-sensitive adhesives themselves are required to be improved in areas other than adhesive properties, such as temperature, pressure, time, etc. Mild conditions are required. Furthermore, from the viewpoint of application to various industrial fields, high levels of adhesiveness such as weight resistance and durability are required. The heat-sensitive adhesives currently used industrially include polyolefins graft-modified with α,β-unsaturated carboxylic acids or their acid anhydrides.
Although this adhesive is effectively used for various purposes, it cannot be said to be an effective adhesive for soft polyvinyl chloride, polystyrene, polypropylene, etc., for example. Ethylene-
A method using vinyl acetate-carbon monoxide copolymer has also been proposed (Japanese Unexamined Patent Publication No. 165427/1982).
Even in the case of this adhesive, the level of adhesive strength required for various uses has not been reached. The present inventors have conducted various studies in search of a heat-sensitive adhesive that exhibits excellent adhesive properties under mild bonding conditions.
It has been found that a new substance, a graft modification of ethylene-vinyl acetate-carbon monoxide copolymer of α,β-ethylenically unsaturated carboxylic acid or its acid anhydride, is extremely effective. Therefore, the present invention
The present invention relates to such a graft modified product and a heat-sensitive adhesive using the same. The ethylene-vinyl acetate-carbon monoxide copolymer used for graft modification contains approximately 40 to 80% ethylene, preferably approximately 60 to 70%, and approximately 15 to 60% vinyl acetate, preferably by weight. about 20-30%,
Also, carbon monoxide is about 3 to 30%, preferably about 5 to 30%.
It is copolymerized at a ratio of 15%, and other comonomers may be copolymerized as necessary. If the ethylene content is less than this, the extrusion moldability during thermal bonding and the extrusion moldability of the film when used as a film type adhesive will be poor, while if the ethylene content is higher than this, the target adhesive strength level will not be obtained. . If the content of vinyl acetate and carbon monoxide is less than this, the target adhesive strength level cannot be obtained, and if it is more than this, heat resistance etc. will be inferior. Examples of the α,β-unsaturated carboxylic acid or its acid anhydride to be graft copolymerized to the ethylene vinyl monoacetate-carbon monoxide copolymer include acrylic acid, methacrylic acid, ethacrylic acid, maleic acid, fumaric acid, and itaconic acid. , hymic acid, crotonic acid, α
- Chloracrylic acid, maleic anhydride, itaconic anhydride, hymic anhydride and the like are exemplified, with acrylic acid, methacrylic acid, maleic anhydride and the like being particularly preferred. Graft modification is carried out by converting at least one α,β-unsaturated carboxylic acid or its acid anhydride into ethylene-
This is carried out by reacting with a vinyl acetate-carbon monoxide copolymer by a solution method, a melt method, or the like. The α,β-unsaturated carboxylic acid or its acid anhydride is graft copolymerized in such a proportion that it accounts for about 0.01 to 5% by weight in the resulting graft modified product.
If the amount of grafting is less than this, the desired adhesive strength cannot be obtained, whereas if it exceeds about 5% by weight, the tendency for the adhesive strength to increase will reach almost saturation, so generally, the amount of grafting less than this is sufficient. Also, it is approximately 0.1
It is preferable to have a melt flow rate of about 500 g/10 minutes. If the value of the melt flow rate is less than this, the fluidity is low and it becomes unsuitable for adhesion at low temperature and low pressure.On the other hand, if the melt flow rate is more than this, the cohesive force and adhesive force are reduced. The obtained graft modified product can be used alone or with other synthetic resins such as ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl acetate copolymer, ethylene-
Methacrylic acid copolymer, ethylene-vinyl acetate-
It can be used by blending with carbon monoxide copolymer, ethylene-α-olefin copolymer, etc. When blending an ethylene-vinyl acetate-carbon monoxide copolymer, it is also possible to blend a more highly grafted modified product and adjust the amount of grafting to about 0.01 to 5 weight as a blend. can. In addition to these, heat stabilizers, thickeners, lubricants, fillers, colorants, etc. may also be added as appropriate. Examples of base materials to which the heat-sensitive adhesive of the present invention is effectively applied include polyethylene, polypropylene, polystyrene, vinyl chloride resin, ethylene-vinyl alcohol copolymer, polyester,
Films such as polyamide, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, ethylene-methacrylic acid copolymer, ethylene-methacrylic acid ester copolymer, ionomer resin, Examples include sheets, other molded products, aluminum foil, copper foil, steel plates, paper, wood, synthetic resin foams, and nonwoven fabrics. The above-mentioned vinyl chloride resins include hard polyvinyl chloride, phthalate esters, adipate esters, phosphate esters, polyesters, and soft or Semi-rigid polyvinyl chloride, ethylene-vinyl acetate copolymer or vinyl chloride graft copolymer to polyacrylic ester, vinyl chloride-ethylene copolymer, vinyl chloride-propylene copolymer, vinyl chloride-acrylic ester Copolymers, vinyl chloride-methacrylic acid ester copolymers, or mixtures of these copolymers and polyvinyl chloride are used. The application of heat-sensitive adhesives to these substrates is
For example, the following method is used. (1) Heat fusion method A method in which a heat-sensitive adhesive film formed by an inflation method, a T-die method, etc. is sandwiched between base materials and bonded under heat, or a coextrusion method on at least one of the base materials. , a method in which a heat-sensitive adhesive is laminated in advance by an extrusion coating method, etc., and then bonded to the other base material (2) Sandwich lamination method A method of laminating a base material through a molten film of heat-sensitive adhesive by a T-die method, etc. (3) Co-extrusion method If the base material can be extruded, all the constituent layers, including the heat-sensitive adhesive, are co-extruded and laminated using an extrusion method (4) Hot-melt method When the base material can be extruded , A method of applying a hot melt adhesive compound containing a viscosity modifier such as wax, adhesive, etc. as necessary to a base material using a hot melt gun, etc., and bonding it by pressure.Adhesion conditions for heat-sensitive adhesives Temperature, pressure, time, etc. are considered to be the factors, but from the viewpoint of preventing deformation, deterioration, and odor generation of the base material or adhesive resin layer, forming a uniform adhesive resin layer, and productivity, mild It is desired that sufficient adhesive strength be obtained under suitable adhesive conditions. Conventionally used heat-sensitive adhesives, such as polyolefins graft-modified with α,β-ethylenically unsaturated carboxylic acids or their acid anhydrides, can reduce their adhesive strength when the adhesive conditions are mild. However, with the heat-sensitive adhesive according to the present invention, as shown in the examples below, there is almost no or only a slight decrease in adhesive strength even under mild adhesive conditions. Therefore, when the heat-sensitive adhesive according to the present invention is applied to various base materials, adhesive conditions such as temperature, pressure, and time can be selected from a wide range.
Even if the conditions are mild, a high level of adhesiveness can be maintained for a long period of time regardless of the type of substrate. Next, the effects of the present invention will be explained with reference to Examples. Example 1 Ethylene-vinyl acetate-carbon monoxide copolymer (62.5% by weight of ethylene, 28.5% by weight of vinyl acetate,
Carbon monoxide 9.0% by weight; Melt flow rate as determined by the measurement method described below35) 100 parts (weight, same hereinafter), 1 part maleic anhydride and 80% mineral spirits of 1,1-bis(tert-butylperoxy)cyclohexane. After dry-blending 0.2 parts of the solution in advance and making it homogeneous, this was transferred to an extruder (screw diameter 30 mm,
L/D=32) at a supply rate of approximately 5 kg/hour,
Graft modification was carried out while maintaining the temperature in the middle part of the extruder at 200°C. The obtained maleic anhydride graft modified product has a grafting rate (by titration method)
0.3% by weight (maleic anhydride reaction rate approximately 30%), melt flow rate (according to JIS K-6760; 190°C,
2160g) had a value of approximately 30. In order to examine the adhesion of this maleic anhydride graft modified product with various resins, press sheets with a thickness of 1 mm were prepared for each of the graft modified product and various resin base materials, and then these two press sheets were overlapped. , press fusion was performed. Press fusion was carried out at a constant temperature of 200° C. in the following order: preheating for 3 minutes, degassing, and pressurization (9.8 MPa) for 3 minutes.
Similar press fusion was also performed on the aluminum base material. The interlayer adhesive strength of these laminates was measured as follows. Width of test piece: 15 mm Measuring device: Autograph P-100 manufactured by Shimadzu Corporation Measuring temperature: 23°C Measuring method: Peel off a predetermined distance using a solvent, or place a predetermined length of release paper between the layers before heat fusing. The adhesion force was measured by T-peel, which was inserted only slightly, grasped each layer with an autograph chuck, and pulled at a tensile speed of 200 mm.The obtained results are shown in Table 1 below. Example 2 Ethylene-vinyl acetate used in Example 1
100 parts of carbon monoxide copolymer, 2 parts of acrylic acid, and 0.1 part of tert-butyl peroctoate were dry blended in advance and homogenized, and then fed to the extruder of Example 1 at a feed rate of about 6 kg/hour. Graft modification was carried out while maintaining the temperature of the middle part of the extruder at 170°C. The obtained acrylic acid graft modified product had a grafting rate of 0.4% by weight (acrylic acid reaction rate of approx.
20%), and the melt flow rate had a value of approximately 20. The adhesion of this acrylic acid graft modified product to various substrates was measured in the same manner as in Example 1, and the results are shown in Table 1 below. Comparative Example 1 Ethylene-vinyl acetate used in Example 1
The adhesion of the carbon monoxide copolymer to various substrates was measured in the same manner as in Example 1, and the results are shown in Table 1 below. Comparative Example 2 The adhesion of maleic anhydride graft-modified polyolefin (Mitsui Petrochemicals Admer-NE050) to various resin base materials was measured in the same manner as in Example 1.
The results are shown in Table 1 below. However, the meanings of the symbols written together with the interlayer adhesive strength (g/15 mm width) are as follows. S: Interfacial peeling X: Cutting or breaking the base material O: Cutting or breaking the adhesive resin

[Table] Example 3 About 2.5 m
By supplying at a supply rate of kg/hour and extruding it from a T-die attached to the tip, the thickness of approximately 100μm,
A film approximately 10 cm wide was molded. This film was made of polyethylene (Mitsui Polychemical product Mirason M-16SP) with a thickness of 1 mm.
Sheet and flexible PVC (DOP50phr)
It was sandwiched between sheets, and press fusion was performed in the same manner as in Example 1. However, the fusion temperature is 130℃,
It was carried out at 150°C, 180°C or 200°C. Comparative Example 3 In Example 3, instead of the maleic anhydride graft modified film, a film of its unmodified copolymer was used. The interlayer adhesive strength of the press-fused laminates obtained in Example 3 and Comparative Example 3 was measured, and the results are shown in Table 2 below. In addition, in all of the measurement samples, peeling was observed at the interface on the polyethylene sheet side. Table 2 Fusion Temperature Example 3 Comparative Example 3 130°C 750g/15mm width 100g/15mm width 150 920 100 180 850 100 200 830 100 Example 4 In Example 3, the formed film was made of ethylene with a thickness of 1mm. - Sandwiched between saponified vinyl acetate copolymer sheet (Kuraray product Var EP-E) sheet and ionomer resin (Mitsui Polychemical product Himilan H-1652) sheet, fusion temperature
Press fusion was performed at 200°C. The press-fused laminate has an interlayer adhesion strength of 1150
g/15 mm width, peeling was observed in the measurement sample at the interface on the ionomer resin sheet side. Comparative Example 4 In Example 4, instead of the maleic anhydride graft modified film, a film of its unmodified copolymer was used. The press-fused laminate had an interlayer adhesive force of 530 g/15 mm width, and peeling was observed in the sample measured at the interface on the saponified ethylene-vinyl acetate copolymer sheet side. Example 5 The film formed in Example 3 was made into a film with a thickness of 30 μm.
sandwiched between an aluminum foil and a 200 μm thick soft polyvinyl chloride (DOP 50 phr) film.
Heat sealing was performed at a predetermined temperature under conditions of a pressure of 0.29 MPa and a time of 5 seconds using a double-sided heating type heat sealer with a seal width of 15 mm. The interlayer adhesion of the heat-sealed laminates was measured and the results are shown in Table 3 below. In addition,
In the measurement sample, peeling was observed at the interface on the aluminum foil side. Comparative Example 5 Similar heat sealing was performed in Example 5 using an unmodified film instead of the maleic anhydride graft modified film.
The interlayer adhesion of the heat-sealed laminates was measured and the results are shown in Table 3 below. In addition, in the measurement sample, peeling was observed at the interface on the aluminum foil side. Comparative Example 6 In Example 5, similar heat sealing was performed using the maleic anhydride graft-modified polyolefin film used in Comparative Example 2. The interlayer adhesion of the heat-sealed laminates was measured and the results are shown in Table 3 below. In addition, in the measurement sample, peeling was observed at the interface on the soft polyvinyl chloride film side. Comparative Example 7 In Example 5, instead of the maleic anhydride graft modified film, a maleic anhydride graft modified product (grafting ratio 0.6% by weight) of an ethylene-α-olefin copolymer (Tafmer A manufactured by Mitsui Petrochemicals) was used. Similar heat sealing was performed using a film formed from a melt blend of 40 parts by weight of ethylene-vinyl acetate copolymer (Mitsui Polychemical product Evaflex 450). The interlayer adhesion for the heat-sealed laminates was measured and the results are shown in Table 3 below. In addition, in the measurement sample, peeling was observed at the interface on the aluminum foil side.

[Table] Example 6 In Example 5, the heat sealing temperature was set to 180℃.
Heat sealing was carried out at constant pressure and time while varying the pressure and time. The interlayer adhesion for the heat-sealed laminates was measured and the results are shown in Table 4 below. In addition, in the measurement sample, peeling was observed at the interface on the aluminum foil side.

[Table] From the results of Examples 5 and 6 above, when the maleic anhydride graft modified product of ethylene-vinyl acetate-carbon monoxide copolymer is used as an adhesive, the adhesion of temperature, pressure, time, etc. It can be seen that even under mild conditions, stable and good adhesive strength can be obtained. Example 7 Ethylene-vinyl acetate molded in Example 3
A film of a maleic anhydride graft modified product of a carbon monoxide copolymer is produced at a T-die exit temperature of 188
When extruded at ℃ and guided in its molten state between a chill roll and a nip roll, a soft polyvinyl chloride (DOP 50 phr) film and a foamed polyethylene sheet (Toray product PEF; expansion ratio 20, thickness 3mm, Sand lamination was performed by inserting a substrate (with an untreated surface), pressing the two substrates together via the adhesive layer of the graft modified product, and winding this up at a winding speed of about 5 m/min. For this sandwich laminate, the interlayer adhesive strength, that is, the interlayer adhesive strength between the adhesive layer and the soft polyvinyl chloride layer or the foamed polyethylene layer, was measured, and the results are shown in Table 5 below. In addition, if soft polyvinyl chloride plasticized with a liquid plasticizer is used as at least one of the base materials, the liquid plasticizer such as DOP contained therein will form on the surface of the soft polyvinyl chloride resin over time. A troublesome phenomenon is generally observed in which the initial adhesive strength decreases at the interface with the adhesive resin, but when using the pressure-sensitive adhesive of the present invention, the adhesive strength decreases over time. Even in a storage test in an atmosphere of 50°C, which was conducted as an accelerated test to investigate the decrease in adhesive strength, no decrease in the initial adhesive strength was observed even after approximately 3 months had elapsed. Example 8 100 parts of ethylene-vinyl acetate-carbon monoxide copolymer (66% by weight of ethylene, 24% by weight of vinyl acetate, 10% by weight of carbon monoxide; melt flow rate 35),
After dry-blending 0.5 part of maleic anhydride and 0.05 part of tert-butyl peroctoate in advance, this was mixed in an extruder (screw diameter 30 mm, L/D = 36).
The graft modification was carried out while maintaining the temperature in the middle part of the extruder at 170°C. The obtained graft modified product had a graft ratio of 0.1% by weight (maleic anhydride reaction rate of about 20%) and a melt flow rate of about 30. Regarding this maleic anhydride graft modified product,
Film molding and sand lamination were carried out in the same manner as in Example 7. The interlayer adhesive strength of this sandwich laminate was measured, and the results are shown in Table 5 below. As can be seen, the adhesive strength decreased over time after 3 months in an atmosphere of 50°C. Even after that, it was not recognized. Comparative Example 8 In Example 7, film molding (T-die exit temperature 187 DEG C.) and sand lamination were carried out using the unmodified maleic anhydride graft modified product instead of the maleic anhydride graft modified product. The interlayer adhesive strength of this sandwich laminate was measured, and the results are shown in Table 5 below. Comparative Example 9 In Example 8, film molding (T-die exit temperature 187° C.) and sand lamination were performed using the unmodified maleic anhydride graft modified product instead of the maleic anhydride graft modified product. The interlayer adhesive strength of this sandwich laminate was measured, and the results are shown in Table 5 below.

【table】

[Table] Comparative Example 10 In Example 7, various synthetic resins were used instead of the maleic anhydride grafted modified ethylene-vinyl acetate-carbon monoxide copolymer, and the T-die outlet was adjusted according to the resin. Film forming and sand lamination using temperature were performed. The interlayer adhesive strength of these sandwich laminates was measured over time in an atmosphere of 50°C, and the results are shown in Table 6 below. (Synthetic resin used): Ethylene-vinyl acetate copolymer (Mitsui Polychemical product Evaflex 150): Maleic anhydride graft modified product of the above copolymer (grafting rate 0.5% by weight): Anhydride to the above copolymer Maleic acid-styrene co-graft modified product (maleic anhydride grafting rate 0.5% by weight, styrene grafting rate 15% by weight): Maleic anhydride to low-crystalline ethylene-α-olefin copolymer (Tafmer S manufactured by Mitsui Petrochemicals) Graft modified product (graft ratio 0.1% by weight): Thermoplastic polyurethane (Elastlan E 585 FNAT, manufactured by Nippon Elastran): Polyether polyester resin (Hytrel HTC 2551, manufactured by Toyo Products): Polyether polyester resin (Divax 5050, manufactured by DuPont) :Polyether polyester resin (DuPont product Daibax 722)

[Table] In these cases, not only is a bonding temperature of 200°C or higher required, but the interlayer adhesive strength decreases significantly over time between the softened polyvinyl chloride layer/adhesive layer, and the foamed polyethylene layer/adhesive layer Since the adhesive force of the agent layer is low, it cannot be said that sufficient adhesive performance is stably obtained.

Claims (1)

[Claims] 1. An ethylene-vinyl acetate-carbon monoxide random copolymer having a composition of 40 to 80% by weight of ethylene, 15 to 60% by weight of vinyl acetate, and 3 to 30% by weight of carbon monoxide, A melt flow rate of 0.1 to 500 g/
Graft modification for 10 min. 2 Into an ethylene-vinyl acetate-carbon monoxide random copolymer having a composition of 40-80% by weight of ethylene, 15-60% by weight of vinyl acetate and 3-30% by weight of carbon monoxide, at a rate of 0.01-5% by weight. Melt flow rate obtained by graft copolymerization of α, β-unsaturated carboxylic acid or its acid anhydride is 0.1 to 500 g/10
A heat-sensitive adhesive consisting of a graft modified product of 100%.