JPH0463114B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to adhesive compositions. More specifically, the present invention relates to an adhesive composition that exhibits excellent adhesion between smooth substrates and porous substrates of the same or different types. [Prior Art] Recently, polyethylene, ionomer resin, polypropylene, ethylene-vinyl alcohol copolymer, polyester,
Synthetic resin base materials such as polyamide, metal base materials such as aluminum plates and steel plates, laminates of smooth base materials such as natural and synthetic leather, or laminates of these smooth base materials and paper, cloth, wood, synthetic resin foam, etc. Laminates with porous substrates are widely used. In these laminates, heat-sensitive adhesives are still used when bonding base materials that are relatively easy to adhere to, but when the smooth base materials mentioned above are used, they are sufficiently bonded. Since there are not many heat-sensitive adhesives that exhibit strong adhesion, the current practice is to surface-treat the base material and then use a solvent-based adhesive for bonding. In addition to adhesive properties, heat-sensitive adhesives are required to have various other properties. For example, the molding process of applying the adhesive to the base fabric is easy, and the bonding conditions such as temperature, pressure, and time are gentle in order to prevent deterioration of the base material and the generation of odors during bonding. It has been demanded. Furthermore, the performance requirements for adhesives, such as heat resistance and durability, are diversifying as they are applied to various industrial fields. Heat-sensitive adhesives currently used industrially include polyolefins graft-modified with α,β-unsaturated carboxylic acids or their acid anhydrides; however, they are not suitable for smooth substrates, especially synthetic resin films. It cannot be said to be an effective adhesive. On the other hand, since the development of adhesives with excellent adhesion to such smooth substrates is industrially important, adhesive compositions are disclosed in published patents. For example, in JP-A-55-13718, in a composition consisting of a low-crystalline ethylene-α-olefin copolymer and an ethylene-vinyl acetate copolymer, at least one of them is graft-modified with an unsaturated carboxylic acid or its acid anhydride. A resin composition is shown. Also Tokukai Akira
No. 57-153064 discloses an ethylene copolymer (A) containing one or more functional groups selected from epoxy groups, carboxylic acid groups, and carboxylic acid anhydride groups and (meth)acrylic acid ester copolymers. An adhesive resin composition comprising a polymer (B) or an ethylene polymer (C) other than the above-mentioned ethylene copolymer (A) is described. However, as shown in the comparative examples below, when we evaluated these compositions with reference to their specifications, especially the detailed description of the invention and the examples, we found that these compositions do not necessarily have the adhesive strength currently required in the market. I couldn't be more satisfied. [Problems to be Solved by the Invention] In view of the current situation, the present inventors have developed a material that has excellent processability in coating work to the base material, good adhesion to the base material even under mild adhesive conditions, and a material that can be laminated. As a result of intensive research in search of an adhesive that improves the heat resistance of objects, the inventors have discovered that an adhesive composition consisting of the following components can solve this problem. [Means for solving the problems] and [Operation] The present invention provides (A) an ethylene content of 20 to 50 mol%, α-
25 to 75% by weight of a low-crystalline or non-crystalline ethylene-α-olefin copolymer with an olefin content of 50 to 80%, and (B) an ethylene-vinyl ester copolymer and/or an ethylene-unsaturated carboxylic acid ester copolymer. An adhesive composition comprising 75 to 25% by weight of a polymer, in which at least one of the polymer components is modified with an unsaturated carboxylic acid or a derivative thereof. The ethylene-α-olefin copolymer used in the present invention has an ethylene content of 20 to 50 mol% and a melt index of 0.1 to 1000, preferably 30 to 45 mol%.
As α-olefins, propylene, butene-
1, pentene-1, hexene-1, octene-1
Among them, propylene, butene-1, and especially propylene are preferable. The α-olefin content in the copolymer is 50 to 80 mol%
and preferably 55 to 70 mol%. α−
In adhesive compositions containing an ethylene-α-olefin copolymer with an olefin content of less than 50 mol% or more than 80 mol% as one of the polymer components, polyolefins, particularly smooth materials such as polypropylene and ionomer resins, are used. However, high adhesive strength cannot be obtained, making it unsuitable as a base polymer for adhesive compositions. In the present invention, as the base polymer, in addition to the above-mentioned ethylene-α-olefin copolymer, an ethylene vinyl ester copolymer and/or an ethylene-unsaturated carboxylic acid ester copolymer is used. Examples of the ethylene-vinyl ester copolymer used in the present invention include ethylene-vinyl acetate copolymer and ethylene-vinyl propionate copolymer. Among these, ethylene-
Vinyl acetate copolymers are preferred, particularly those with a vinyl acetate content of 2 to 15 mol% and a melt index of 1 to 15 mol%.
1000 ethylene-vinyl acetate copolymer is preferred. Furthermore, as the ethylene-unsaturated carboxylic acid ester copolymer used in the present invention, ethylene-
(meth)methyl acrylate copolymer, ethylene-
(meth)ethyl acrylate copolymer, ethylene-
(meth)butyl acrylate copolymer, ethylene-
Examples include 2-ethylhexyl (meth)acrylate copolymer. Among these, ethylene-(meth)acrylic acid methyl or ethyl copolymers are preferred, particularly ethylene-(meth)acrylic acids having a methyl (meth)acrylate or ethyl content of 2 to 15 mol% and a melt index of 1 to 1000. Methyl or ethyl copolymers are preferred. Next, in the present invention, the ratio of the ethylene-α-olefin copolymer to the ethylene-vinyl ester copolymer and/or the ethylene-unsaturated carboxylic acid ester copolymer is 25 A range of from 30 to 70% by weight, particularly from 30 to 70% by weight, is preferred. If the blending ratio of the ethylene-α-olefin copolymer is less than 25% by weight, the adhesion to the substrate will decrease, and if it is more than 75% by weight, the tackiness will increase, the cohesive force will decrease, and workability will deteriorate. Undesirable. Therefore, ethylene-α-
The blending ratio of olefin copolymer is 25 to 75% by weight.
It is necessary to keep it within the range of . In the present invention, at least one of the polymer components consisting of an ethylene-α-olefin copolymer, an ethylene-vinyl ester copolymer, and/or an ethylene-unsaturated carboxylic acid ester copolymer is substituted with a carboxylic acid or its acid anhydride. It is necessary to carry out graft modification by Examples of the graft monomer in this case include acrylic acid, methacrylic acid, fumaric acid, crotonic acid, itaconic acid, citraconic acid, maleic anhydride, itaconic anhydride, citraconic anhydride, and maleic acid monoethyl ester. can. Among these, it is most preferred to use maleic acid or maleic anhydride. Graft modification is carried out by converting at least one of the unsaturated carboxylic acids or derivatives thereof into (A) copolymer alone, (B) copolymer alone, or (A) copolymer in the presence of a radical generator such as an organic peroxide. This is carried out by reacting a mixture of the copolymer and the copolymer (B) by a known method such as a solution method or a melt method. What should be noted here is that (A) component ethylene-α
- Olefin copolymer, component (B) ethylene-vinyl ester copolymer and/or ethylene-unsaturated carboxylic ester copolymer, unsaturated carboxylic ester copolymer and unsaturated carboxylic acid or its derivative When simultaneously melt-kneaded and reacted in the presence of an oxide, an adhesive composition with extremely high adhesive performance can be obtained, although the mechanism of action is not clear. Therefore, in order to produce the adhesive composition of the present invention, a method is adopted in which component (A), component (B), and an unsaturated carboxylic acid or a derivative thereof are simultaneously melt-kneaded in the presence of an organic peroxide. It is preferable. The unsaturated carboxylic acid or its derivative is about 0.01 to 5% by weight in the resulting graft modified product (composition).
The graft reaction is carried out in such a proportion that it accounts for If the amount of grafting is less than this, the desired adhesive strength cannot be obtained,
On the other hand, if the amount exceeds about 5% by weight, the tendency for the adhesive strength to increase almost reaches saturation, so a grafting amount less than this is generally sufficient. Also, it is about 0.1~
It is preferable to have a melt flow rate of about 1000 g/10 minutes. If the value of the melt flow rate is less than this, the fluidity will be low and it will become unsuitable for bonding at low temperature and low pressure.On the other hand, if the value is more than this, the cohesive force will decrease and the adhesive force will also decrease. The adhesive composition of the present invention generally has good adhesive properties on its own, but it can further improve adhesive performance when bonding under milder bonding conditions or when bonding to difficult-to-adhesive substrates. adhesive composition for the purpose of
It is also possible to add less than 25 parts by weight of tackifying resin per 100 parts by weight. Examples of tackifier resins that can be used in this case include rosin and its derivatives, terpene resins, terpene-phenol resins, aromatic, aliphatic, alicyclic or copolymer petroleum resins, coumaron-indene resins, and styrene resins. Among these, terpene resins, terpene-phenol resins, aliphatic petroleum resins, and alicyclic petroleum resins and their copolymer petroleum resins are particularly preferred from the viewpoint of compatibility with polymer components, adhesiveness, and the like. In addition to the above-mentioned tackifying resin, the adhesive composition of the present invention may contain various modifiers and additives, as necessary, within the range that does not impair its performance. For example, petroleum waxes such as paraffin wax and microcrystalline wax, synthetic waxes such as polyethylene wax and polypropylene wax, liquid polybdenum, plasticizers such as cyoctylphthalate and dibutyl phthalate, and phenolic or bisphenol antioxidants. Examples thereof include UV absorbers, fillers such as calcium carbonate, talc, and glass fibers, known lubricants, roll release agents, and antiblocking agents. The adhesive composition of the present invention is prepared by dry blending the components simultaneously or sequentially. Dry blends can be mixed using various blenders such as Henschel mixers, tumbler mixers, and ribbon blenders, while melt blends can be mixed using single-screw extruders, twin-screw extruders, Banbury mixers, etc., and the mixing order There are no particular restrictions. Substrates to which the adhesive composition of the present invention can be effectively applied include, for example, polyethylene, polypropylene, polystyrene, vinyl chloride resin, ethylene-vinyl alcohol copolymer, polyester, polyamide, polyvinylidene chloride, polyacrylonitrile, and polycarbonate. , ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid ester copolymer, ethylene-(meth)acrylic acid copolymer, ionomer resin and other synthetic resin films, sheets and other molded products, aluminum foil, copper Examples include metals such as foils, natural and synthetic leathers, paper, woven and non-woven fabrics, wood, synthetic resin foams, etc., and are effective for laminating one or more base materials selected from these base materials. Lamination of these base materials with the adhesive composition is performed, for example, by the following method. (1) Heat fusion method A method in which an adhesive composition film formed by an inflation method, a T-die method, etc. is sandwiched between base materials and bonded under heat, or a method in which at least one base material is bonded by a coextrusion method, A method in which an adhesive composition is laminated in advance using an extrusion coating method or the like, and then bonded to the other base material by thermocompression bonding. (2) Sand-Germany lamination method A method of laminating base materials through a molten film of an adhesive composition using a T-die method or the like. (3) Coextrusion method A method in which all constituent layers, including the adhesive composition, are adhesively laminated by extrusion molding when the base material can be extruded. (4) Hot-melt method A method in which a hot-melt adhesive made by adding wax, tackifying resin, etc. to an adhesive composition, if necessary, is applied to a base material using a hot-melt gun, etc., and bonded by pressure. Although the configuration of the present invention has been described in detail above,
The first feature of the present invention is that it has been discovered that an ethylene-α-olefin copolymer having a specific comonomer content has excellent adhesive performance, and this is used as a component of an adhesive composition. The second feature is the ethylene-
It increases the cohesive force, which is a drawback of α-olefin copolymers, prevents sticking and blocking of adhesive compositions and their coated products, and improves processability, such as maximum take-off speed, during extrusion coating work on substrates. Ethylene-vinyl ester copolymers and/or ethylene-unsaturated carboxylic acid ester copolymers are effective as polymers that increase the heat resistance of laminates and do not impair the adhesive properties of ethylene-α-olefin copolymers. It has been found that this is the case and has been used as the second component of an adhesive composition. As a result, the third characteristic is that (A) component ethylene-α-olefin copolymer is an organic peroxide decomposition type, and component (B) component ethylene-vinyl ester copolymer or ethylene-unsaturated carboxylic acid ester copolymer. Since the copolymer mainly composed of ethylene is an organic peroxide crosslinked type, both components (A) and (B) and an unsaturated carboxylic acid or its derivative can be simultaneously melt-kneaded in the presence of an organic peroxide. However, when reacted, the melt index, which is an important property of adhesives, decreases little during the reaction, and although the mechanism is not clear, it has become possible to obtain adhesive compositions that have extremely high adhesive performance. It is. The fourth characteristic
Because the ethylene-vinyl ester copolymer and/or ethylene-unsaturated carboxylic acid ester copolymer as component (B) has excellent compatibility with the tackifying resin, the tackifying resin is not added to the adhesive composition. It is easy to add, and it has become possible to further improve the adhesive performance of the component (A) ethylene-α-olefin copolymer. [Example] Next, the effects of the present invention will be explained with reference to Examples. The compositions prepared in each Example and Comparative Example were evaluated as follows. (1) Method for evaluating adhesive strength of adhesive composition: (a) Heat sealing method The adhesive composition was heated and melted at 160°C, and a sheet with a thickness of 200 μm was created using a hot press. This adhesive sheet was sandwiched between base materials, and a heat sealer was used to seal width 25 mm, seal temperature 150°C (temperature of the top and bottom surfaces of the seal bar), seal pressure 3 Kg/cm ² G, and seal time 5.
After heat-sealing for 2 seconds, the sample was cut to a width of 25 mm, and the T-peel strength of the sample was measured using an Instron tester at a tensile speed of 300 mm/min and a temperature of 23°C. (b) Extrusion coating method Adhesive composition is extruded at 65m/m using a coating machine (L/D=24, roll surface length 710m/m)
using a resin temperature of 170℃ and a line speed of
Under the condition of 20m/min, the adhesive phase thickness is 100μ
It was coated so that it became m. This laminate was bonded to the aluminum plate or synthetic leather using a heat sealer under the following conditions: sealing width 25mm, sealing temperature 150℃ (temperature of the top and bottom surfaces of the seal bar), sealing pressure 3Kg/cm ² , and sealing time 5 seconds. After heat sealing, the sample was cut to a width of 25 mm, and the T-peel strength of the sample was measured using an Instron tester at a tensile speed of 300 mm/min and a temperature of 23°C. The base materials for these adhesive strength measurements were polypropylene film (PP: Inflation film made from polypropylene manufactured by Mitsui Oil & Chemicals Co., Ltd., thickness 200 μm), soft aluminum plate (Al: thickness 200 μm), cotton cloth ( Achilles' cotton-9A) and synthetic leather (Teijin Cordray S2941-1110-K05) were used, respectively. (2) Heat resistance (shear adhesive failure temperature): Method for measuring adhesive strength (a) In the heat sealing method, a 200 μm sheet of the adhesive composition was sandwiched between kraft paper and heat sealed under the same conditions, and then
A sample with a width of 25 mm was prepared, a load of 1 kg was applied to it, and the temperature was raised at a heating rate of 0.3°C/min. The temperature at which the load fell was measured, and this was used as a measure of heat resistance. (3) Non-adhesion: The adhesion (tack) of the surface of a 200 μm sheet of the adhesive composition was evaluated by finger tack at 23°C as follows. ○ No tack △ Slight tack The maximum drawing speed (m/min) at which no cutting occurred during melting was used as a measure of processability during melting. Example 1, Comparative Examples 1a to 1b Propylene-ethylene copolymer (propylene content 60 mol%, melt flow rate 1.5, hereinafter PER
-1), 100 parts (weight, same below), 1.5 parts of maleic anhydride and 2,5-dimethyl-2,5
-bis(t-butylperoxy)hexyne-3
0.2 parts were blended using a Henschel mixer, and this mixture was heated to a resin temperature of 260°C using an extrusion unit with a diameter of 30 mm (L/D = 32, using a Dalmage screw).
to extrude the maleic anhydride-modified propylene-ethylene copolymer (hereinafter abbreviated as MAH-PER-1).
A pellet was obtained. This melt flow rate is
25, the maleic anhydride grafting rate was 1.1% by weight (Comparative Example 1a). obtained in this way
Pellets were obtained by melt-blending 20 parts of an alicyclic petroleum resin (Alcon P100, manufactured by Arakawa Chemical) with 100 parts of MAH-PER-1 (Comparative Example 1b). Also,
100 parts of MAH-PER-1 and 100 parts of unmodified ethylene-ethyl acrylate copolymer (Evaflex A-704 manufactured by Mitsui Dupont Polychemicals, EA content 27% by weight, melt flow rate 210, hereinafter abbreviated as EEA-1) Using the same extruder as above, the resin temperature is 170
Melt blending was carried out at °C to obtain pellets with a melt flow rate of 65 (Example 1). The adhesive strength by heat sealing method, shear adhesive failure temperature, and processability of each adhesive composition thus prepared were measured, and the results are shown in the table. Example 2 In Example 1, unmodified EEA-2 (manufactured by Mitsui DuPont Polychemicals, Evaflex A-703, EA content 25% by weight, melt flow rate 6) was used in place of unmodified EEA-1. The melt flow rate of the pellets obtained was 10. Example 3 In Example 1, instead of PER-1,
Using EEA-1, maleic anhydride-modified ethylene ethyl acrylate copolymer (hereinafter MAH-
(abbreviated as EEA-1) was obtained. This melt flow rate is 90, and the maleic anhydride grafting rate is
It was 1.1% by weight. obtained in this way
100 parts of MAH-EEA-1 and 100 parts of unmodified PER-1
The mixture was melt-blended in the same manner as in Example 1 to obtain pellets with a melt flow rate of 7. Example 4 100 parts of MAH-PER-1 obtained in Comparative Example 1a and 100 parts of MAH-EEA-1 obtained in Example 3 were melt-blended in the same manner as in Example 1 to form pellets with a melt flow rate of 55. Obtained. Example 5 In Example 1, ethylene-vinyl acetate copolymer (manufactured by Mitsui DuPont Polychemicals, Evaflex #210, VA 28% by weight, melt flow rate) was used instead of unmodified ethylene-ethyl acrylate.
400; hereinafter abbreviated as EVA-1) to obtain adhesive composition pellets. This melt flow rate is 85
It was hot. Comparative Example 2 In Example 2, only MAH-EEA-1 was used. Comparative Example 3 100 parts of unmodified PER-1 and unmodified EEA-1
100 parts were melt blended under the same conditions as in Example 1 to obtain pellets. The melt flow rate of this pellet was 20. Comparative Example 4 In Comparative Example 3, melt blending was performed using unmodified EVA-1 instead of unmodified EEA-1. The melt flow rate of this pellet is
It was 50. Comparative Example 5 In Example 1, instead of PER-1, TER-1 with a high ethylene content (80 mol% ethylene,
Using melt flow rate 4), maleic anhydride modified ethylene-propylene copolymer (hereinafter referred to as
A pellet (abbreviated as MAH-EPR-1) was obtained. The maleic anhydride grafting rate of this pellet was 1.0% by weight, and the melt flow rate was 2.7. 100 parts of MAH-EPR-1 thus obtained was melt blended under the same conditions as in Example 1 to obtain pellets with a melt flow rate of 50. Comparative Example 6 Ethylene-methacrylic acid copolymer (manufactured by Mitsui-Dupont Polychemicals, Nuclell 410, acid content 9% by weight, melt flow rate 10 or less)
50 parts of EMMA-1) were melt blended using 15 parts of EEA-2 and 35 parts of EVA-1 under the same conditions as in Example 1, and the melt flow rate was
Obtained 35 pellets. Example 6 50 parts of PER-1, 50 parts of EEA-1, 1.5 parts of maleic anhydride, and 0.2 parts of 2,5-bis(t-butylperoxy)hexyne-3 were blended in a Henschel mixer, and this mixture was prepared. Under the conditions of Example 1, pellets of a maleic anhydride modified adhesive composition (abbreviated as MAH-(PER/EEA)-1) were obtained. The melt fluorate of this composition is 8
The maleic anhydride grafting ratio was 1.2. Example 7 The same procedure as Example 6 was carried out except for 100 parts of PER-1 and 40 parts of EEA-1, and a maleic anhydride-modified polyolefin polymer composition (MAH-(PER/EEA)-2
) pellets were obtained. The melt flow rate of this composition was 10, and the maleic anhydride grafting ratio was 1.2. Example 8 In Example 7, EVA-1 was used instead of EEA-1.
A maleic anhydride-modified polyolefin polymer composition (MAH-1) was prepared in the same manner except that MAH-1 was used.
(PER/EVA)-1) pellets were obtained.
The melt flow rate of this composition was 20, and the maleic anhydride grafting ratio was 1.2. The adhesive strength, shear bond failure temperature, and processability of the adhesive compositions prepared in Examples 2 to 8 and Comparative Examples 1 to 6 were measured by heat sealing, respectively. The results are shown in the table. Example 9 MAH-PR-1 obtained in Example 2
100 parts of melt blend pellets of 50 parts and 50 parts of EEA-2, alicyclic petroleum resin (Arakawa Chemical Alcon)
P100), 0.1 part of erucic acid amide (Nutron S manufactured by Nippon Fine Chemical Co., Ltd.), and 0.1 part of polyethylene glycol (PEG-4000 manufactured by Wako Pure Chemical Industries, Ltd.) were melt blended using an extruder to obtain pellets with a melt flow rate of 20. Ta. Example 10 MAH-(PER/
EEA)-1 100 parts, alicyclic petroleum resin (Etsuo Chemical Escorets 5300) 20 parts, erucic acid amide 0.1
1 part and 0.1 part of polyethylene glycol were melt blended using an extruder to determine the melt flow rate.
Got 10 pellets. Comparative Example 7 In Example 9, melt blending was performed using unmodified PER-1 instead of MAH-PER-1 to obtain pellets with a melt flow rate of 3.5. As described above, the adhesive strength and processability of the adhesive compositions prepared in Examples 9 and 10 and Comparative Example 7 were measured by the extrusion coating method. The results are shown in the table.

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Claims (1)

[Scope of Claims] 1 (A) A low-crystalline or non-crystalline ethylene-α-olefin copolymer with an ethylene content of 20 to 50 mol% and an α-olefin content of 50 to 80 mol%, and ( B) In an adhesive composition comprising 75 to 25% by weight of an ethylene-vinyl ester copolymer and/or an ethylene-unsaturated carboxylic acid ester copolymer, at least one of the polymer components is an unsaturated carboxylic acid or a derivative thereof. An adhesive composition characterized by being modified by. 2. The adhesive composition according to claim 1, wherein the low-crystalline or non-crystalline ethylene-α-olefin copolymer is an ethylene-propylene copolymer. 3. The adhesive composition according to claim 1, wherein the unsaturated carboxylic acid ester of the ethylene-unsaturated carboxylic acid ester copolymer is an aliphatic alkyl ester of acrylic acid or methacrylic acid. 4. The adhesive composition according to claim 1, which is produced by simultaneous melt mixing of component (A), component (B), unsaturated carboxylic acid or its derivative, and organic peroxide.