JP5236950B2 - Hot melt adhesive composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a hot-melt adhesive composition, and more specifically to a hot-melt adhesive composition that has little stringing, is transparent, and has excellent thermal stability.

BACKGROUND ART Hot melt adhesives are used in various applications such as packaging, bookbinding, and woodwork from the standpoints of high set speed, good economic efficiency, and no use of solvents.

  However, hot melt adhesives cause stringing when used, contaminate peripheral devices (for example, casers and printing devices in the case of cardboard packaging lines), adhere to products, and damage the product value. Affects the equipment (causes malfunction).

  Nozzle coating is a typical application method for hot melt adhesives. In this method, even after an OFF signal is transmitted, stringing occurs due to a delay in response due to the nozzle cavity or mechanical shielding (spring back), and this stringing occurs when the distance between the nozzle and the adherend is long. When the line speed is high, the hot melt adhesive in use has a high melt viscosity.

  Therefore, when yarn drawing occurs, the operator needs to stop the work line and remove the yarn.

  Many proposals have been made in the prior art to reduce the stringing of this hot melt adhesive.

  For example, JP-A-7-33221 discloses a hot melt adhesive containing a base polymer such as an ethylene / vinyl acetate copolymer, an ethylene / (meth) acrylate copolymer, and an adhesiveness imparting agent in a specific ratio. This is disclosed by blending a low molecular weight ethylene / unsaturated carboxylic acid copolymer in a specific ratio. However, this hot melt adhesive composition has the disadvantages of causing dripping at the time of application and insufficient adhesive force due to insufficient cohesive force.

JP-A-11-61067 discloses a specific fumed silica in a hot melt composition containing a specific ethylene / unsaturated ester copolymer, a tackifying resin and a wax in order to reduce the stringiness. It is disclosed. JP2003-238920A discloses that a specific amount of polyethylene is blended with two specific types of ethylene / unsaturated ester compositions. Japanese Patent Application Laid-Open No. 2004-2634 discloses blending a resin incompatible with the base resin as a colloidal particle into a base resin such as an ethylene / vinyl acetate copolymer or an ethylene acrylate copolymer. ing. However, these hot-melt adhesive compositions are subject to transparency and inferior in thermal stability, and gel or carbonize due to long-term use, causing clogging of the applicator or causing poor application.
JP 7-33221 A Japanese Patent Laid-Open No. 11-61067 JP 2003-238920 A SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a hot melt adhesive composition that has significantly reduced stringing and is excellent in thermal stability and transparency. .

SUMMARY OF THE INVENTION The present inventors have intensively studied to try to produce a hot melt adhesive composition that has almost no stringing and is excellent in thermal stability and transparency. During this study, the inventors focused on ethylene / α-olefin copolymers such as those described in US Pat. No. 6,107,430. The ethylene / α-olefin copolymer can provide a hot melt adhesive having excellent thermal stability. The inventors have identified a specific polymer in the ethylene / α-olefin copolymer (first component) that is incompatible with the copolymer but significantly reduces the stringiness of the copolymer. That is, by blending the ethylene / (meth) acrylic acid ester copolymer (second component), and the third component compatible with the first component and the second component in a specific ratio, I found that I could achieve my purpose. The present invention is based on these findings.

That is, according to the present invention, a first component comprising at least one ethylene / C ₃ -C ₂₀ α-olefin copolymer; an amount of about 6 to about 12 parts by weight per 100 parts by weight of the first component A second component comprising at least one ethylene / (meth) acrylate copolymer; and at least one adhesive in an amount of from about 50 to about 200 parts by weight per 100 parts by weight of the first component A hot melt adhesive composition is provided that includes a third component that is compatible with the first and second components, including an application resin.

DETAILED DESCRIPTION OF THE INVENTION A hot melt adhesive composition according to the present invention comprises (1) a first component comprising at least one ethylene / C ₃ -C ₂₀ α-olefin copolymer, (2) at least one component. A second component comprising an ethylene / (meth) acrylic acid ester copolymer, and (3) a third component compatible with the first and second components comprising at least one tackifying resin. Including.

The ethylene / C ₃ -C ₂₀ α-olefin copolymer constituting the first component is ethylene and at least one C ₃ -C ₂₀ α-olefin (for example, propylene, isobutylene, 1-butene, 1-pentene). , 1-hexene, 4-methyl-1-pentyne, 1-octene). The α-olefin is preferably a C _{4 to} C ₂₀ α-olefin, more preferably a C _{6 to} C ₈ α-olefin, and even more preferably 1-octene. The ethylene / α-olefin copolymer preferably contains C _{3 to} C ₂₀ α-olefin in an amount of about 20 to about 40 mol%.

  The hot melt adhesive composition of the present invention can be used for various applications such as packaging, bookbinding, and woodworking. Generally, the ethylene / α-olefin copolymer preferably has a melt index of about 5 to about 2500 g / 10 minutes, and for packaging, it has a melt index of about 150 to about 2500 g / 10 minutes. Is preferred.

  The ethylene / α-olefin copolymer used in the present invention and the production method thereof are described in, for example, US Pat. No. 6,107,430. The ethylene / 1-octene copolymer is sold by Dow Chemical Company under the trade name “AFFINITY”. For example, AFFINITY EG 8185 (melt index: 30.00 g / 10 min), AFFINITY EG 8200G (melt index: 5.00 g / 10 min), AFFINITY GA 1900 (melt index: 1000.00 g / 10 min) AFFINITY GA 1950 (melt index: 500.00 g / 10 min) and AFFINITY PT 1409 (melt index: 6.00 g / 10 min). These ethylene / 1-octene copolymers have a 1-octene content of about 35-37 mol%. The ethylene / α-olefin copolymers can be used alone or in combination.

The second component of the hot melt adhesive composition of the present invention is the first component, that is, a polymer that is incompatible with the ethylene / α-olefin copolymer, and significantly reduces stringiness. . This second component comprises a copolymer of ethylene and at least one (meth) acrylic ester, ie an ethylene / (meth) acrylic ester copolymer. It should be noted that (meth) acrylic acid ester is a general term for acrylic acid ester and methacrylic acid ester. (Meth) acrylic acid esters, preferably (meth) C ₁ -C ₈ alkyl acrylate (e.g., methyl, ethyl, propyl, butyl) is an ester, more preferably (meth) C ₁ -C acrylic acid ₄ alkyl ester. The (meth) acrylic acid ester is particularly preferably ethyl acrylate or methyl methacrylate. The ethylene / (meth) acrylic acid ester copolymer preferably contains (meth) acrylic acid ester in an amount of about 5 to about 35 mol%, and preferably contains about 20 to about 35 mol%. Further preferred. The ethylene / (meth) acrylic acid ester copolymer preferably has a melt index of about 20 to about 400 g / 10 min. Such ethylene / (meth) acrylic acid ester copolymers are commercially available. For example, an ethylene / ethyl acrylate copolymer A704 (melt index: 275 g / 10 min; ethyl acrylate content of 25) sold under the trade name EVAFLEX-EEA by Mitsui DuPont Polychemical Co., Ltd. A709 (melt index: 25 g / 10 min; ethyl acrylate content 34 mol%); trade name of DPDJ-9169 from Nippon Unicar Co., Ltd. (melt index: 20 g / 10 min; ethyl acrylate content) 20 mol%), NUC-6070 trade name (melt index: 250 g / 10 min; ethyl acrylate content 25 mol%) and NUC-6940 trade name (melt index: 20 g / 10 min; ethyl acrylate content) Ethylene / acrylic sold under 35 mol%) Ethyl copolymer; trade name of ACRYFT CM5021 (melt index: 450 g / 10 min; methyl methacrylate content: 28 mol%) and trade name of ACLIFT CM5022 (melt index: 450 g / 10) from Sumitomo Chemical Co., Ltd. Min; methyl methacrylate content; 32 mol%), ethylene / methyl methacrylate co-marketed under the trade name of ACRIFT CM5023 (melt index: 150 g / 10 min; methyl methacrylate content; 28 mol%) Polymer and the like. The ethylene / (meth) acrylic acid ester copolymers can be used alone or in combination.

  The third component of the hot melt adhesive composition of the present invention is compatible with the first component and the second component, and makes the hot melt adhesive composition of the present invention transparent. . This third component includes at least one tackifying resin.

  In the present invention, the term “compatible” refers to a mixture of two or more components melted by heating to the application temperature (usually about 160 to about 180 °, typically 180 °). It indicates a “transparent” state that does not show phase separation of components even when left for a long time and allows sufficient visible light to pass through. The word “transparent state” means that when the molten mixture is placed in a flat-bottomed glass sample bottle placed on newspaper up to a level (height) of 10 cm and viewed from directly above, the letters on the newspaper below the bottle. Is defined as being readable with the naked eye.

The third component may be provided by one type of tackifying resin, or the first tackifying resin compatible with the first component (ethylene / α-olefin copolymer), and the second It may be provided by a combination of a component (ethylene / (meth) acrylic ester copolymer) and a compatible second tackifying resin. In the latter case, the first and second tackifying resins can be provided by petroleum resins. More specifically, the first tackifying resin preferably contains a fully hydrogenated petroleum resin, more preferably a petroleum resin having a hydrogenation rate of about 95% or more. The second tackifying resin preferably comprises a partially hydrogenated petroleum resin, more preferably a partially hydrogenated petroleum resin having a hydrogenation rate of about 60 to about 70%. Petroleum resin is a synthetic resin produced by polymerizing unsaturated petroleum fractions. Typical examples of these resin raw materials include C _{4 to} C ₅ fractions (eg, 1-butene, isobutylene, butadiene, pentene, isoprene, piperidine, 1 , 3-pentadiene), and C9-C10 fractions (vinyltoluene, indene, α-methylstyrene, cyclopentadiene). The petroleum resin includes an aliphatic petroleum resin, an alicyclic petroleum resin, an aromatic petroleum resin, and a copolymer petroleum resin of an aliphatic component and an aromatic component. The aliphatic petroleum resin is a resin obtained by polymerizing the C _{4 to} C ₅ fractions. The alicyclic petroleum resin is a resin obtained by cyclizing and dimerizing the acyclic diene component in the C _{4 to} C ₅ fraction, and polymerizing the dimer monomer, and resin polymerizing cyclopentadiene. Etc. The aromatic petroleum resin is a resin obtained by polymerizing the C _{9 to} C ₁₀ fractions. Further, the copolymerization petroleum resin of aliphatic component and aromatic component, a resin obtained by copolymerizing the C ₄ -C ₅ fraction and C ₉ -C ₁₀ fraction. Partially and fully hydrogenated petroleum resins are commercially available. For example, partially hydrogenated C5 aromatic petroleum resins are available from Idemitsu Kosan under the trade names IMAGV S-100 (softening point: 100 ° C.) and IMAGV S-110 (softening point: 110 ° C.). It is sold at. Fully hydrogenated C5 aromatic petroleum resins are trade names from Idemitsu Kosan Co., Ltd. under the trade names IMAGV P-90 (softening point: 90 ° C.), IMAGV P-100 (softening point: 100 ° C.), and IMAGV. It is sold under P-125 (softening point: 125 ° C.), IVARV P-140 (softening point: 140 ° C.).

In the hot melt adhesive composition of the present invention, the second component (ethylene / (meth) acrylic ester copolymer) is changed to 100 parts by weight of the first component (ethylene / C ₃ -C _20α -olefin copolymer). In an amount of about 5 to about 12 parts by weight. If the amount of the second component is less than about 5 parts by weight per 100 parts by weight of the first component, the stringiness cannot be sufficiently reduced. On the other hand, if the amount of the second component exceeds about 12 parts by weight per 100 parts by weight of the first component, the resulting hot melt adhesive composition will have insufficient transparency. The amount of the second component is preferably about 7 to about 10 parts by weight per 100 parts by weight of the first component.

  The amount of the third component (tackifier resin) is about 50 to about 250 parts by weight per 100 parts by weight of the first component. If the amount of the third component is less than about 50 parts by weight per 100 parts by weight of the first component, it is elastic and lacks adhesiveness. On the other hand, if the third component exceeds about 250 parts by weight per 100 parts by weight of the first component, the hot melt adhesive becomes brittle. When the third component is a combination of the first tackifying resin and the second tackifying resin, the amount of the first tackifying resin is about 40 to about 150 weight per 100 parts by weight of the first component. The amount of the second tackifying resin is preferably about 10 to about 50 parts by weight per 100 parts by weight of the first component. More preferably, the amount of the first tackifying resin is from about 70 to about 120 parts by weight per 100 parts by weight of the first component, and the amount of the second tackifying resin is per 100 parts by weight of the first component. More preferred is about 20 to about 40 parts by weight.

  In addition to the first to third components, the hot melt adhesive composition of the present invention reduces the viscosity of the hot melt adhesive composition, suppresses crystallization, and adjusts the pot life. Wax can be included.

  Various waxes generally used for hot melt adhesives can be used. Examples include synthetic waxes such as Fischer-Tropsch wax, polyethylene wax, polypropylene wax, atactic polypropylene wax, and ethylene / vinyl acetate copolymer; petroleum waxes such as paraffin wax, refined paraffin wax, and microcrystalline wax; wood Natural waxes such as wax, carnauba wax and beeswax. The wax used preferably has a melting point of about 60 to about 120 °. Such waxes are commercially available.

  In the hot melt adhesive composition of the present invention, the wax is preferably included in an amount of about 30 to about 85 parts by weight per 100 parts by weight of the first component.

  Moreover, the hot melt adhesive composition of the present invention can contain an antioxidant. As the antioxidant to be used, various antioxidants generally used for hot melt adhesives can be used. Examples of antioxidants include hindered phenolic antioxidants (IRGANOX 1010, 1076, etc. manufactured by Ciba Specialty Chemicals), phosphite antioxidants (Irgaphos 168, manufactured by Ciba Specialty Chemicals), and the like. .

  Furthermore, the hot melt adhesive composition of the present invention can include a liquid tackifying resin and / or a process oil. Examples of the liquid tackifying resin include MARUKACLEARH manufactured by Maruzen Petrochemical Co., Ltd., and REGALITE R1010 manufactured by Eastman Chemical Co., Ltd. Examples of process oil include paraffin oil PW-90 manufactured by Idemitsu Petrochemical Co., Ltd. and naphthen oil 371-N manufactured by Shell Chemicals Japan Co., Ltd.

  The amount of each component of the hot melt adhesive composition of the present invention has been described above based on the weight of the first component. However, in another embodiment, the amount of each component of the hot melt adhesive composition of the present invention can be defined based on the total amount of the hot melt adhesive composition. In that case, the hot melt adhesive composition of the present invention preferably comprises from about 20 to about 60% by weight of the first component, from about 1 to about 10% by weight of the second component, from about 20 to about 60% by weight. A third component, 0 to about 40 weight percent wax, and 0 to about 1 weight percent antioxidant. More preferably, the hot melt adhesive composition of the present invention comprises from about 25 to about 50 weight percent first component, from about 2 to about 4 weight percent second component, from about 20 to about 50 weight percent first component. 1 tackifying resin, from about 5 to about 20 weight percent second tackifying resin, from about 10 to about 30 weight percent wax, and from 0 to about 1 weight percent antioxidant.

Examples Hereinafter, examples of the present invention will be described, but the present invention is not limited to these examples.

Examples 1-6, Comparative Examples 1-5
Hot melt adhesive compositions having the compositions shown in Table 1 below were prepared.

In Table 1:
AFFINITY GA 1950 (trade name) is an ethylene / 1-octene copolymer (melt index: 500.00 g / 10 min; 1-octene content: 35-37 mol%) sold by Dow Chemical Company. And is the first component of the present invention;
ACRYFT CM5021 (trade name) is an ethylene / methyl methacrylate copolymer (melt index: 450 g / 10 min; methyl methacrylate content: 28 mol%) sold by Sumitomo Chemical Co., Ltd. Two components;
EEA A704 (trade name) is an ethylene / ethyl acrylate copolymer (melt index: 275 g / 10 min; ethyl acrylate content 25 mol%) sold by Mitsui DuPont Polychemical Co., Ltd. A second component of
IVARV P125 (trade name) is a fully hydrogenated C5 aromatic petroleum resin (softening point: 125 ° C .; average molecular weight by gas phase infiltration method: 880) sold by Idemitsu Kosan Co., Ltd. A component (first tackifying resin);
IVARV S100 (trade name) is a partially hydrogenated C5 aromatic petroleum resin (softening point: 100 ° C .; average molecular weight by a gas phase infiltration method: 700) sold by Idemitsu Kosan Co., Ltd. A component (second tackifying resin);
BARECO PX-100 is a Fischer-Tropsch wax (melting point: 98 ° C.) sold by Baker Petrolite;
IRGANOX 1010FF is a hindered phenolic antioxidant sold by Ciba Specialty Chemicals.

  Various physical properties of each hot melt adhesive composition were measured by the following methods. The results are also shown in Table 1.

Initial viscosity (unit: mPa · s)
Using a Brookfield RVF viscometer and a thermocell, No. Measure at 180 ° C. with 21 spindles.

Viscosity after heat curing (unit: mPa · s)
100 g of the hot melt adhesive is put into a 225 cc glass jar, covered with aluminum foil, covered, and left in an oven at 180 ° C. for 1 week. The viscosity at that time is measured in the same manner as the initial viscosity.

Viscosity change rate after heat curing (%)
The viscosity change rate after heat curing is calculated by the following formula.

  {[(Viscosity after heat curing) − (initial viscosity)] ÷ (initial viscosity)} × 100.

Initial transparency (compatibility test Newspaper (no particular limitation, but the font is Mincho and 3 mm in size) is placed on a flat-bottom glass sample bottle with a capacity of 110 cc, typical application temperature 180 Put the hot melt adhesive sample melted at ℃ to a height of 1 cm.In this state, peek directly from above and read the letters of the newspaper with the naked eye. Repeat this until it reaches a height of 10 cm or more, but if it can be read to a height of 10 cm, it is judged to be transparent, and the highest liquid level that could be recognized is reported. In addition, when a sample is put in a sample bottle, if bubbles exist in the sample, the sample bottle containing the sample is heated again to 180 ° C. to expel the bubbles and then used for measurement. .

Adhesion test Using a JT Toshi adhesive strength tester, hot melt adhesive was applied to K-liner cardboard pieces at 180 ° C. with an application amount of 3 g / m, with an open time of 2 seconds and a press pressure of 7.8 kPa. A piece of K-liner cardboard was laminated. The bonded cardboard pieces are left in a thermostatic bath set at −20 ° C., −10 ° C., 5 ° C., 23 ° C., 50 ° C. and 60 ° C. for 12 hours or more and forced by hand in the atmosphere. Peel off. The rate of destruction of the corrugated board liner in the total adhesion area is defined as the material breakage rate.

Thread pullability test The thread pullability of the hot melt adhesive was basically evaluated by the method described in JP-A-2004-2634. However, the number of shots was 100, the tank, hose, and nozzle temperatures were 180 ° C. or 170 ° C., the nozzle diameter was 20/1000 inches, and the pump pressure was 0.3 or 0.2 MPa. Measure the amount of fallen objects that have accumulated in the pan and observe the form of the fallen objects. In Table 1, regarding the form of the fallen object, “D” indicates that it is grainy, “S” indicates that it is thread-like, and “DS” is mainly grainy but slightly mixed with thread. "SD" indicates that it is mainly in the form of a thread but slightly mixed with grains. That is, if the form of the fallen object is “D”, it means that the composition has no complete stringiness, and if the form of the fallen object is “DS”, the composition has the stringiness. It means that there is virtually no.

  From the results shown in Table 1, the adhesive composition of the present invention has excellent adhesiveness, good thermal stability (low viscosity change rate before and after heat curing), excellent transparency, and stringiness. It exhibits excellent properties that it is virtually absent.

Claims (6)

First component comprising at least one ethylene / C ₃ ~C ₂₀ α- olefin copolymers,
A second component comprising at least one ethylene / (meth) acrylate copolymer in an amount of 6 to 12 parts by weight per 100 parts by weight of the first component;
A third component compatible with the first and second components, comprising at least one tackifying resin in an amount of 50 to 200 parts by weight per 100 parts by weight of the first component;
The third component includes a petroleum resin having a hydrogenation rate of 95% or more, the first tackifying resin in an amount of 40 to 150 parts by weight per 100 parts by weight of the first component, and a hydrogenation rate of 60 to 70%. A second tackifying resin in an amount of 10 to 50 parts by weight per 100 parts by weight of the first component .
A hot melt adhesive composition comprising:
This composition is obtained by placing the molten mixture at 180 ° C. in a flat-bottomed glass sample bottle placed on a newspaper to a level (height) of 10 cm, and when viewed from directly above the molten mixture, The said composition which is a transparent state which the character of a newspaper can read with the naked eye.   The composition according to claim 1, wherein the α-olefin comprises 1-octene. The composition according to claim 2, wherein the ethylene / C _{3 to} C ₂₀ α-olefin copolymer has a melt index of 150 to 2500 g / 10 minutes. The (meth) acrylic acid ester, C ₁ -C ₈ alkyl (meth) composition according to any one of claims 1 to 3 comprising acrylic acid ester.   The composition according to any one of claims 1 to 4, further comprising at least one wax.   The composition according to claim 2, wherein the (meth) acrylic acid ester is ethylene / ethyl acrylate or ethylene / methyl methacrylate.