JP2007051235A - Hot melt adhesive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hot melt adhesive hardly causing stringing and excellent in thermal stability. <P>SOLUTION: The hot melt adhesive comprises at least a base resin, a resin incompatible with the base resin, an adhesiveness-imparting resin, a wax and an antioxidant, wherein the base resin is at least one olefinic copolymer obtained by copolymerization of ethylene with a 3-20C α-olefine, the resin incompatible with the base resin is a ethylene-vinyl acetate copolymer satisfying 28-45 wt.% vinyl acetate content and 10-200 g/10 min melt flow rate, the adhesiveness-imparting resin is at least one selected from a group consisting of a hydrogenated terpene resin, a hydrogenated 5C-based resin, a hydrogenated 9C-based resin and a hydrogenated rodin-based resin. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hot melt adhesive.

  Hot melt adhesives are solvent-free and have the advantages of bonding process and economics that instant bonding and high-speed bonding are possible, so they are used in large quantities mainly in fields such as packaging, bookbinding and woodworking. ing. The base resin (main component) of the hot melt adhesive is excellent in the balance of adhesiveness, flexibility, heat stability, price, etc., so that ethylene-vinyl acetate copolymer or ethylene-ethyl acrylate copolymer is used. Ethylene copolymers such as are widely used. In general, hot-melt adhesives are added to these base resins with a tackifying resin as an adhesive improver and a wax as a function modifier.

  Among the above components, the base resin expresses cohesive force for imparting bulk properties to the hot melt adhesive, and is tough and strong against tensile stress and compressive stress. The tackifying resin has a function of improving the adhesiveness by imparting wetness, penetration, tack (tackiness), etc. to the adherend to the hot melt adhesive. Since the tackifying resin is generally amorphous and has a glass transition temperature (Tg) higher than that of the base resin, it also has a function of improving the heat resistance of the hot melt adhesive. Further, the wax has a function of reducing the melt viscosity of the hot melt adhesive to improve applicability and imparting rapid solidification to the hot melt adhesive to enable high-speed adhesion.

  Since the hot melt adhesive needs to be applied at a high temperature, a dedicated application device called a hot melt applicator is used at the time of application. This hot melt applicator usually heats a hot melt adhesive to about 120 to 190 ° C., and uses a compressed air or a gear pump to intermittently discharge (shot) from the tip of the nozzle to the adherend. Apply. At that time, generally, a thread-like material is generated between the tip of the nozzle that discharges the hot melt adhesive and the adherend between the adherends due to the spinnability of the hot melt adhesive. When this filamentous material is generated, problems such as contamination of peripheral devices and adherends, malfunction of the sensor, printing errors, and the like occur in various usage processes.

  In order to suppress the stringing, in the hot melt adhesive composition comprising an ethylene / unsaturated ester copolymer, a tackifier resin, and a wax, a high-pressure polyethylene existing in a finely dispersed state in the hot melt matrix is used. A hot melt adhesive (see Patent Document 1) characterized by containing, at least a base resin and an incompatible component with respect to the base resin, and in a molten state at 120 to 190 ° C., the incompatible component is A hot melt adhesive (see Patent Document 2) dispersed as colloidal particles has already been proposed.

However, although any of the above hot melt adhesives can suppress stringing, a problem still remains in terms of thermal stability.
That is, the hot melt adhesive is stored in the tank while being heated to about 120 to 190 ° C. as described above, and is sent and discharged from the tank to the nozzle in a necessary amount. When the state of storage in a state of being heated for a long time continues, there is a problem that gelation / carbonization causes clogging of the hot melt applicator or poor application.

Japanese Patent Laid-Open No. 11-236543 Japanese Patent Laid-Open No. 2004-2634

  In view of the above circumstances, an object of the present invention is to provide a hot melt adhesive that has little stringing and is excellent in thermal stability.

In order to achieve the above object, a hot melt adhesive according to the present invention includes a base resin, a resin incompatible with the base resin, a tackifying resin, a wax, and an antioxidant. An adhesive, wherein the base resin is at least one olefin copolymer obtained by copolymerizing ethylene and an α-olefin having 3 to 20 carbon atoms, and a resin incompatible with the base resin is vinyl acetate. It is an ethylene-vinyl acetate copolymer satisfying a content rate of 28 to 45% by weight and a melt flow rate (g / 10 min) of 10 to 200, and the tackifying resin is a hydrogenated terpene resin or a hydrogenated C5 system. It is at least one selected from the group consisting of a resin, a hydrogenated C9-based resin, and a hydrogenated rosin-based resin.
In addition, the melt flow rate (hereinafter also referred to as MFR) of the ethylene-vinyl acetate copolymer is measured under conditions of 190 ° C. and a load of 21.18 N in accordance with JIS K7210.

  In the present invention, the base resin is at least one olefin copolymer obtained by copolymerization of ethylene and an α-olefin having 3 to 20 carbon atoms. Examples of the α-olefin having 3 to 20 carbon atoms include propylene, isobutylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene and the like. Among the olefin-based copolymers, a copolymer of ethylene and an α-olefin having 6 to 8 carbon atoms is preferable, and a copolymer of ethylene and 1-octene is more preferable. These olefin copolymers may be used alone or in combination of two or more.

  The olefin copolymer preferably has an α-olefin copolymerization ratio of 20 to 40 mol%. The olefin copolymer preferably has a melt flow rate (g / 10 min) of 5 to 2500, and more preferably 150 to 2500. In addition, the melt flow rate of an olefin type copolymer says what was measured on condition of 190 degreeC and load 21.18N based on JISK7210.

  Examples of the copolymer of ethylene and 1-octene include those manufactured by Dow Chemical Co., Ltd., synthesized using a single site metallocene catalyst, and trade names Affinity EG8185 (MFR = 30) and trade names Affinity EG8200 (MFR). = 5), commercial name affinity GA1900 (MFR = 1000), commercial name affinity GA1950 (MFR = 500), commercial name affinity PT1409 (MFR = 6), etc. can be used. These commercially available copolymers of ethylene and 1-octene have a copolymerization ratio of 1-octene of 35 to 37 mol%.

  The blending ratio of the base resin is not particularly limited, but is preferably 20 to 50% by weight. That is, when the blending ratio of the base resin is less than 20% by weight, the heat resistance of the adhesive may decrease due to insufficient cohesive force, and the cold-resistant adhesive property may decrease due to insufficient flexibility. There is a risk of poor adhesion due to a decrease in the yarn suppressing effect and a decrease in wettability to the adherend.

  The resin incompatible with the base resin is particularly limited as long as it is an ethylene-vinyl acetate copolymer satisfying a vinyl acetate content of 28 to 45% by weight and a melt flow rate (g / 10 minutes) of 10 to 200. Although not preferred, those having a vinyl acetate content of 28 to 35% by weight and a melt flow rate (g / 10 min) of 50 to 150 are more preferred. For example, trade name Evaflex V5773 (Mitsui DuPont) %, MFR = 90), Tosoh's brand name Ultrasen 760 (vinyl acetate content 42 wt%, MFR = 70), and other commercially available products can be used.

  In the present invention, the resin incompatible with the base resin is contained in the base resin and can be dispersed as colloidal particles in a molten state at 120 to 190 ° C. When the resin incompatible with the base resin is dispersed as colloidal particles in the base resin, an effect of suppressing the stringing at the time of applying the hot melt adhesive can be exhibited. If it is compatible with the base resin, it will melt evenly in the hot melt adhesive, so that it will not be able to exhibit the effect of suppressing stringing during the application of the hot melt adhesive. On the other hand, if it is completely incompatible and cannot be dispersed as colloidal particles, it will be phase-separated in the molten state, so that it will not be possible to exhibit the effect of suppressing stringing during the application of the hot melt adhesive.

  Although the said colloidal particle is not specifically limited, It is preferable that a diameter is 0.1-5 micrometers. If the diameter of the colloidal particles is less than 0.1 μm or more than 5 μm, it may not be possible to sufficiently obtain the effect of suppressing stringing when the hot melt adhesive is applied. The diameter of the colloidal particles can be confirmed by analysis with a transmission electron microscope.

  The blending ratio of the resin incompatible with the base resin is not particularly limited, but is preferably 0.5 to 5% by weight. That is, if the blending ratio of the resin that is incompatible with the base resin is less than 0.5% by weight, the effect of suppressing the stringing is reduced, and if it exceeds 5% by weight, the viscosity is increased and the coating property is lowered. Or the thermal stability may be lowered.

  The tackifying resin is not particularly limited as long as it is at least one selected from the group consisting of hydrogenated terpene resins, hydrogenated C5 resins, hydrogenated C9 resins, and hydrogenated rosin resins. Yasuhara Chemical Co., Ltd., trade name Clearon P115 (hydrogenated terpene resin), Eastman Chemical Co., Ltd., trade name East Tuck C115W (hydrogenated C5 resin), Arakawa Chemical Co., Ltd., trade name Alcon P115 (hydrogenated C9 resin), Commercially available products such as trade name KR-612 (hydrogenated rosin resin) manufactured by Arakawa Chemical Co., Ltd. can be used.

  Although the compounding ratio of tackifying resin is not specifically limited, 20 to 50 weight% is preferable. That is, when the blending ratio of the tackifying resin is less than 20% by weight, the viscosity at the time of melting becomes high, the applicability is lowered, the effect of suppressing the stringing is reduced, and the wettability to the adherend is lowered. If it exceeds 50% by weight, it becomes hard and brittle and may cause poor adhesion.

  Examples of the wax include, but are not limited to, synthetic waxes such as Fischer-Tropsch wax and polyethylene wax, and natural waxes such as paraffin wax, purified paraffin wax, microcrystalline wax, and the like. From the viewpoint of excellent effect of imparting, wax having a melting point in the range of 60 to 120 ° C. is preferably used. These waxes may be used alone or in combination of two or more.

  The blending ratio of the wax is not particularly limited, but is preferably 10 to 30% by weight. That is, when the blending ratio of the wax is less than 10% by weight, the viscosity becomes high, the applicability is lowered, or the solidification speed is slow, so that there is a possibility that the high-speed line cannot be supported. It may become hard and brittle and cause poor adhesion.

  Although it does not specifically limit as antioxidant, For example, hindered phenolic antioxidants, such as the brand name Irganox 1010 by Ciba Specialty Chemicals company name, and the brand name Irganox 1076 by Ciba Specialty Chemicals company, the product by Ciba Specialty Chemicals company Examples thereof include phosphite antioxidants such as the name Irgaphos 168. These antioxidants may be used alone or in combination of two or more.

  The blending ratio of the antioxidant is not particularly limited, but is preferably 0.1 to 3% by weight. That is, when the blending ratio of the antioxidant is less than 0.1% by weight, the thermal stability may be lowered, and even when it exceeds 3% by weight, further improvement of the thermal stability cannot be expected.

  In addition, the hot melt adhesive of the present invention includes, for example, a filler, an extender, a viscosity modifier, a thixotropic agent, and a softening agent (plasticizer) as long as the achievement of the object of the present invention is not hindered. , One or more of various additives such as process oil, heat stabilizer, light stabilizer, ultraviolet absorber, colorant, flame retardant, and antistatic agent may be blended.

  The method for producing the hot melt adhesive of the present invention is not special, and various types of agitating and kneading machines generally used in the production of hot melt adhesives have been used. Each predetermined amount of a compatible component, tackifying resin, wax, antioxidant, and one or more predetermined amounts of various additives to be blended as necessary are heated and melted at 120 to 190 ° C. By stirring and kneading uniformly, a desired hot melt adhesive can be obtained.

As described above, the hot melt adhesive according to the present invention is a hot melt adhesive containing a base resin, a resin incompatible with the base resin, a tackifying resin, a wax, and an antioxidant. And at least one olefin copolymer obtained by copolymerizing ethylene and an α-olefin having 3 to 20 carbon atoms as a base resin, and a vinyl acetate content of 28 to 45% by weight as a resin incompatible with the base resin. An ethylene-vinyl acetate copolymer having a melt flow rate (g / 10 min) satisfying 10 to 200, a hydrogenated terpene resin, a hydrogenated C5 resin, a hydrogenated C9 resin, and a hydrogenated resin as tackifiers Since at least one selected from the group consisting of rosin resins is used, there is little stringing and excellent thermal stability.
Therefore, a good application state can be stably maintained for a long time, and productivity can be improved.

  In addition, since there is little stringing, it is excellent in high-speed coating properties, and it hardly causes peripheral devices or adherends to be contaminated, sensor malfunctions, printing errors, etc. in various use processes.

  Hereinafter, specific examples of the present invention will be described in detail in comparison with comparative examples. The present invention is not limited to the following examples.

Example 1
Copolymer of ethylene and 1-octene as a base resin (trade name Affinity GA1950 (MFR = 500) of Dow Chemical Company) 35 parts by weight, ethylene-vinyl acetate copolymer as a resin incompatible with the base resin (Mitsui DuPont brand name Evaflex V5773 (vinyl acetate content 33 wt%, MFR = 90)) 2 parts by weight, hydrogenated terpene resin as a tackifying resin (Yasuhara Chemical brand name Clearon P115) 40 weight Universal stirring kneader (Dalton Co., Ltd.) having a temperature set at 160 ° C. for 22 parts by weight of wax (trade name Sazol Wax H1 manufactured by Sazol) and 1 part by weight of antioxidant (trade name Irganox 1010 manufactured by Ciba Specialty Chemicals) Sequentially put into the model “25AM type, stirrer: hook”, completely heat and melt, To obtain a hot-melt adhesive is stirred for 1 hour and kneaded by the number 60 rpm.

(Example 2)
Example 1 except that hydrogenated terpene resin (trade name Clearon P115 manufactured by Yasuhara Chemical Co., Ltd.) was used as the tackifier resin, and hydrogenated C5 resin (trade name East tack C115W manufactured by Eastman Chemical Co., Ltd.) was used. Similarly, a hot melt adhesive was obtained.

(Example 3)
In place of 40 parts by weight of hydrogenated terpene resin (trade name Clearon P115 manufactured by Yashara Chemical Co., Ltd.) as a tackifier resin, 44 parts by weight of hydrogenated C9 resin (trade name Alcon P115 manufactured by Arakawa Chemical Co., Ltd.) is used. A hot melt adhesive was obtained in the same manner as in Example 1 except that the amount of the wax was 18 parts by weight.

Example 4
As a tackifier resin, 44 parts by weight of hydrogenated rosin resin (trade name KR-612, manufactured by Arakawa Chemical Co., Ltd.) is used instead of 40 parts by weight of hydrogenated terpene resin (trade name Clearon P115, manufactured by Yashara Chemical Co., Ltd.). A hot melt adhesive was obtained in the same manner as in Example 1 except that the amount of the wax was 18 parts by weight.

(Example 5)
30 parts by weight of a copolymer of ethylene and 1-octene as a base resin (trade name Affinity GA1950 (MFR = 500) of Dow Chemical Company), an ethylene-vinyl acetate copolymer as a resin incompatible with the base resin (Trade name Ultrasen 760 manufactured by Tosoh Corporation (vinyl acetate content 42% by weight, MFR = 70)) 4 parts by weight, hydrogenated terpene resin as a tackifier resin (trade name Clearon P115 manufactured by Yashara Chemical Co., Ltd.) 40 parts by weight A universal stirring kneader (manufactured by Dalton Co., Ltd.) in which 25 parts by weight of a wax (trade name Sazol Wax H1 manufactured by Sazol) and 1 part by weight of an antioxidant (trade name Irganox 1010 manufactured by Ciba Specialty Chemicals Co., Ltd.) were set at 160 ° C. The model "25AM type", stirrer: hook) are sequentially put in, heated and melted completely, and then rotated at 60 rp. To obtain a hot-melt adhesive in 1 hour stirring kneading.

(Example 6)
Example 5 except that hydrogenated terpene resin (trade name Clearon P115 manufactured by Yasuhara Chemical Co., Ltd.) was used as the tackifier resin, and hydrogenated C5 resin (trade name East Tuck C115W manufactured by Eastman Chemical Co., Ltd.) was used. Similarly, a hot melt adhesive was obtained.

(Example 7)
The blending ratio of the base resin is 35 parts by weight, and instead of 40 parts by weight of hydrogenated terpene resin (trade name Clearon P115 manufactured by Yashara Chemical Co., Ltd.) as a tackifier resin, 35 parts by weight of hydrogenated C9 resin ( A hot melt adhesive was obtained in the same manner as in Example 5 except that the trade name Alcon P115) manufactured by Arakawa Chemical Co., Ltd. was used.

(Example 8)
The blending ratio of the base resin is 25 parts by weight, and instead of 40 parts by weight of hydrogenated terpene resin (trade name Clearon P115 manufactured by Yashara Chemical Co., Ltd.) as a tackifier resin, 45 parts by weight of hydrogenated rosin resin ( A hot melt adhesive was obtained in the same manner as in Example 5 except that Arakawa Chemicals trade name KR-612) was used.

(Comparative Example 1)
37 parts by weight of a copolymer of ethylene and 1-octene as a base resin (trade name Affinity GA1950 (MFR = 500) of Dow Chemical Company), hydrogenated terpene resin as a tackifier resin (trade name of Yashara Chemical Company) Universal stirrer in which 40 parts by weight of Clearon P115), 22 parts by weight of wax (trade name Sazol Wax H1 manufactured by Sazol), and 1 part by weight of antioxidant (trade name Irganox 1010 manufactured by Ciba Specialty Chemicals Co., Ltd.) are set to 160 ° C. The mixture was sequentially charged into a kneader (Dalton model “25AM type”, stirring tool: hook) and completely heated and melted, and then stirred and kneaded for 1 hour at a rotation speed of 60 rpm to obtain a hot melt adhesive.

(Comparative Example 2)
Example 1 except that a hydrogenated terpene resin (trade name Clearon P115 manufactured by Yasuhara Chemical Co., Ltd.) was used as the tackifier resin, and a hydrogenated dicyclopentadiene resin (trade name Escorez 5320HC manufactured by ExxonMobil Co., Ltd.) was used. Similarly, a hot melt adhesive was obtained.

(Comparative Example 3)
Instead of ethylene-vinyl acetate copolymer (trade name Evaflex V5773 manufactured by Mitsui DuPont (vinyl acetate content 33% by weight, MFR = 90)) as an incompatible resin with the base resin, ethylene-vinyl acetate copolymer A hot melt adhesive was obtained in the same manner as in Example 2 except that the coalesced product (trade name NUC-3160 manufactured by Nippon Unicar Co., Ltd. (vinyl acetate content 20% by weight, MFR = 400)) was used.

  The hot melt adhesives obtained in Examples 1 to 8 and Comparative Examples 1 to 3 were evaluated for spinnability and thermal stability, and the results are shown in Table 1.

For spinnability, as shown in FIG. 1, an adherend is placed vertically at a distance of 20 cm from the tip of the hot melt gun, and a plate-shaped receiving tray for catching falling objects is placed between them. Keep it. Under an airless atmosphere at 20 ° C., using an AC power supply sequencer under the following conditions, hot melt adhesive was intermittently applied under the conditions of 600 shots / 10 minutes, and the weight of the fallen material collected on the tray was measured and dropped. The shape of the object was visually observed, and the case where it was granular was evaluated as ◯, the case where the particle and the thread were mixed, Δ, and the case where it was a thread as ×. That is, if the fallen object is heavy and the fallen object is thread-like, the spinnability at the time of application is large, if the fallen object is light, and if the fallen object becomes instantly granular, the spinnability at the time of application is low. Judged.
Hot melt applicator: Product name “Nordson 3400” (piston pump type, manufactured by Nordson)
Hot melt gun: H-200 gun (nozzle diameter: 18/1000 inch, nozzle: 3 orifice nozzle)
Discharge air pressure: 294kPa
Tank, hose and gun temperatures: 175 ° C

  On the other hand, with respect to thermal stability, 50 g of each obtained hot melt adhesive was weighed into a 140 cc glass bottle and the glass bottle opening was covered with aluminum foil. After storage for 200 hours, remove the glass bottle from the thermostatic bath and check if the carbide is attached to the edge of the glass bottle in a ring shape or the surface of the hot melt adhesive in the glass bottle is not covered with carbide. No ring was generated, ○ was ring generated, × was not skinned, and ○ was skinned.

In Table 1, the incompatible resin I is an ethylene-vinyl acetate copolymer (trade name Evaflex V5773 manufactured by Mitsui DuPont, Inc., vinyl acetate content: 33 wt%, MFR = 90), and the incompatible resin II is Ethylene-vinyl acetate copolymer (trade name Ultrasen 760 manufactured by Tosoh Corporation (vinyl acetate content 42% by weight, MFR = 70)), incompatible resin III is ethylene-vinyl acetate copolymer (manufactured by Nippon Unicar Co., Ltd.) Name NUC-3160 (vinyl acetate content 20% by weight, MFR = 400)), tackifying resin V is a hydrogenated terpene resin (trade name Clearon P115 manufactured by Yasuhara Chemical Co., Ltd.), and tackifying resin II is a hydrogenated C5 system Resin (trade name Easttack C115W manufactured by Eastman Chemical Co.), tackifying resin III is hydrogenated C9 resin (trade name Alcon P115 manufactured by Arakawa Chemical Co., Ltd.), tackifying Fat IV is hydrogenated rosin resin (Arakawa Chemical Industries, Ltd. trade name KR-612), tackifying resin V denote the hydrogenated dicyclopentadiene resin (Exxon Mobil Corporation, trade name Escorez 5320HC).

It is sectional drawing which shows the evaluation method of the spinnability at the time of application | coating.

Claims (7)

A hot melt adhesive comprising a base resin, a resin incompatible with the base resin, a tackifying resin, a wax, and an antioxidant,
The base resin is at least one olefin copolymer obtained by copolymerizing ethylene and an α-olefin having 3 to 20 carbon atoms,
A resin incompatible with the base resin is an ethylene-vinyl acetate copolymer satisfying a vinyl acetate content of 28 to 45% by weight and a melt flow rate (g / 10 minutes) of 10 to 200,
The hot-melt adhesive is characterized in that the tackifying resin is at least one selected from the group consisting of hydrogenated terpene resins, hydrogenated C5 resins, hydrogenated C9 resins, and hydrogenated rosin resins. .   The hot melt adhesive according to claim 1, wherein the base resin is a copolymer of ethylene and 1-octene.   The hot melt adhesive according to claim 1 or 2, wherein the base resin is contained in an amount of 20 to 50% by weight.   The hot melt adhesive according to claim 1 or 2, wherein 0.5 to 5% by weight of a resin incompatible with the base resin is contained.   The hot melt adhesive according to claim 1 or 2, wherein the tackifying resin is contained in an amount of 20 to 50% by weight.   The hot melt adhesive according to claim 1 or 2, wherein the wax is contained in an amount of 10 to 30% by weight.   The hot melt adhesive according to claim 1 or 2, wherein the antioxidant is contained in an amount of 0.1 to 3% by weight.

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