JPH064840B2 - Reactive urethane-hot melt adhesive - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a low viscosity reactive urethane-hot melt adhesive composition which has been improved with respect to cohesive and adhesive strength by the addition of a low molecular weight acrylic resin. . According to one embodiment of the invention, an acrylic monomer is polymerized into the non-isocyanate component of the polyurethane-prepolymer and the component is reacted with a suitable isocyanate functional group to provide a plasticizer or tackifier. A hot melt adhesive composition having a suitable coating viscosity is obtained without the need to add a tingling agent.

The hot melt adhesive is free of any solvent and has a solid content of 100% which does not require it.
Although it is a solid at room temperature, it melts to a liquid or fluid state when heated and is applied to the substrate in that state. Upon cooling, the adhesive reverts to the solid state and adhesive strength is obtained. In this regard, hot melt adhesives differ from other types of adhesives which achieve a solid state by evaporation or removal of solvent or by polymerization.

To obtain the required physical properties, many hot melt adhesives are prepared with thermoplastic materials that are melted and applied at elevated temperatures and that bond rapidly upon cooling.

Also typically, these thermoplastic properties are heat sensitive and result in joints that are lost under mild heat loading.

Hot melt adhesive compositions applied in the molten state solidify on cooling and subsequent curing by chemical crosslinking reactions have been prepared using special thermosetting materials such as polyurethane. These hot melt materials exhibit excellent heat resistance but have less inherent strength and resemble heavy balsams or greases before the crosslinking reaction is carried out. In addition, polyurethane-based hot melt adhesives lack adequate adhesion for many commercial substrates such as polyvinyl chloride film, Mylar ™ (a polyester film from DuPont) and aluminum. US Patent No.
Attempts have been made to improve the initial bond strength of polyurethane-hot melt adhesives by the addition of certain thermoplastics as taught in 3931077. This thermoplastic, however, is generally a high molecular weight (ie, greater than about 100,000) material, the addition of which clearly increases the coating viscosity of the adhesive and reduces it sufficiently to facilitate application. Therefore, it is necessary to add a plasticizer or a tackifier separately. Although the viscosity of the prepared adhesive in the hot state decreases, the addition of relatively large amounts of these plasticizing and tackifying components affects the adhesive properties of polyurethane-hot melt adhesives, especially the bonding properties. It has a serious effect on the storage of objects.

The object of the present invention is therefore to provide an improved polyurethane-hotmelt adhesive composition which exhibits excellent initial adhesion to an unusually wide range of substrates and is heat-resistant even after storage of the joint. It is to be.

[Structure of Invention]

The present inventor obtains by polymerizing an acrylic acid- or methacrylic acid C ₁ -C ₁₂ -ester having no active hydrogen,
Addition of a low molecular weight polymer having an intrinsic viscosity of 0.1-0.4 measured in a 9: 1 mixture of tetrahydrofuran and alcohol to the urethane prepolymer is solid at room temperature and at 120 ° C. At viscosities of 3000 to 50000 cps, it can be easily applied without the need for additional trapping tackifiers or plasticizers and has improved initial cohesive strength as well as improved strength after storage of cured joints. It has been found that a hot melt adhesive is provided. In addition, the adhesive exhibits the above-described improved properties in a wide range of substrates, including difficult-to-bond substrates such as polyvinyl chloride, mylar and aluminum.

The low molecular weight polymer may be added to the polyol before it is reacted with the isocyanate component or to the prepolymer that has already been produced. Further, the product of the present invention is
It can be prepared by simultaneously polymerizing a urethane prepolymer and an acrylic acid- or methacrylic acid C ₁ -C ₁₂ -ester. The polyurethane - prepolymer acrylic acid - or methacrylic acid C ₁ -C ₁₂ -
It may be prepolymerized in the ester and then polymerized to produce the product of the invention.

Radical-polymerizable active hydrogen-free acrylic acid- or methacrylic acid C ₁ -C ₁₂ -esters are methyl acrylate, ethyl acrylate, n-butyl acrylate,
It is not limited to isobutyl acrylate, n-propyl- or isopropyl acrylate and the corresponding methacrylates. Mixtures of compatible (meth) acrylate monomers can also be used. Such mixtures, including mixtures of butyl-acrylate and methyl-acrylate, are well known in the art. The choice of individual monomers depends largely on the desired end use of the adhesive. For example, those skilled in the art know that selecting certain monomers results in pressure sensitive adhesives, while other monomers result in non-pressure sensitive adhesives. Similarly, suitable monomers can be selected for the preparation of structural adhesives, contact adhesives and the like.

Urethane-prepolymers are typically used in the production of polyurethane hot melt adhesive compositions. In general, this prepolymer is produced by condensation polymerization of polyisocyanates and polyols, in particular diisocyanates and polyols. Polyols used include polyhydroxy ethers (substituted or unsubstituted polyalkylene ether glycols or polyhydroxy-polyalkylene ethers), polyhydroxy-polyesters, polyol ethylene oxide- or propylene oxide-.
Included are adducts and mono-substituted esters of glycols.

Any suitable organic polyisocyanate such as ethylene diisocyanate, ethylidene-diisocyanate, propylene-diisocyanate, butylene-diisocyanate, hexamethylene-diisocyanate, toluene-
Diisocyanate, cyclopentylene-1,3-diisocyanate, cyclohexylene-1,4-diisocyanate, cyclohexylene-1,2-diisocyanate,
4,4'-diphenylmethane-diisocyanate, 2,
2-diphenylpropane-4,4'-diisocyanate, p-phenylene-diisocyanate, m-phenylene-diisocyanate, xylylene-diisocyanate, 1,4-naphthylene-diisocyanate, 1,5-
Naphthylene-diisocyanate, diphenyl-4,4 '
-Diisocyanate, azobenzene-4,4'-diisocyanate, diphenylsulfone-4,4'-diisocyanate, dichlorohexamethylene-diisocyanate, furfuridene-diisocyanate, 1-chlorobenzene-2,4-diisocyanate, 4,4 ', 4 "- Triisocyanate-triphenylmethane, 1,3,5-
Triisocyanate-benzene, 2,4,6-triisocyanate-toluene and 4,4'-dimethyldiphenylmethane-2,2 ', 5,5'-tetraisocyanate can be used.

The polyisocyanate component and the polyol component are about 0.25
The proportions are such that a urethane prepolymer having an isocyanate content of about 15%, especially about 10%, is obtained. Furthermore,
The ratio of isocyanate equivalents to hydroxyl equivalents (known as the isocyanate index) should be greater than 1 but not greater than about 2. If the low isocyanate index is maintained, the level of free isocyanate content in the final hot melt adhesive composition can be reduced below about 4%, especially below 1%. It has been found that the presence of large amounts of free isocyanate has a significant effect on the preparation of hot melt adhesives, as poisons are released when the adhesive is heated to the application temperature. Further, a larger amount of free isocyanate causes a decrease in viscosity and also a decrease in initial bonding strength of the adhesive. The exact amount of polyisocyanate used in the polymerization depends on the equivalent weight of the polyol, the amount of polyol and the particular polyisocyanate used. Generally, the amount of polyisocyanate required to achieve the above isocyanate content varies from about 5% to about 55% of the final prepolymer.

According to the broadest scope of the present invention, the acrylic acid- or methacrylic acid C ₁ -C ₁₂ -esters can be polymerized using the customary radical polymerization processes which lead to relatively low molecular weights. For purposes of this invention, low molecular weight is about 10
It means a molecular weight in the range of 000 to 30,000. This low molecular weight can be obtained by carefully monitoring and controlling the reaction conditions and generally by carrying out the reaction in the presence of a chain transfer agent such as dodecyl mercaptan. The correlation between the intrinsic viscosity and the molecular weight is known, and the inventor has generally been able to polymerize monomers to an intrinsic viscosity of 0.1-0.4 (measured in a 9: 1 mixture of tetrahydrofuran and alcohol). Have been found to be particularly advantageous for use in the present invention. In this embodiment, the low molecular weight polymer is then mixed with the polyol and dissolved in the polyol prior to reacting with the isocyanate component or the low molecular weight polymer is dissolved in the urethane-prepolymer that has already been prepared. In any case, a low molecular weight polymer is used as a urethane prepolymer containing a terminal isocyanate group, and a reaction curable hot melt adhesive has a urethane prepolymer of about 5 to 90% and a low molecular weight of 95 to 10%. And a polymer. Care should be taken during storage and handling of low molecular weight polymers to avoid contamination with atmospheric moisture or other factors that affect the stability of the prepolymer system. The resulting hot melt adhesive can then be applied in the molten state to the substrates to be joined using techniques known to those skilled in the art. Urethane-based hot-melt adhesives take time to cure due to atmospheric humidity and form a crosslinked network.

It is also possible to polymerize low molecular weight polymers in the presence of already formed urethane polymers containing terminal isocyanate groups. This method has the disadvantage of leaving the prepolymer for unnecessary heating during acrylic polymerization. This heating can lead to branching, increased viscosity, depletion of the required isocyanate groups and / or possible gelation. These disadvantages require control but require tighter control of each condition as compared to polymerizing to a non-isocyanate functional urethane component. If the reaction is carried out in a polyol or other non-isocyanate containing component, there is the benefit of low reaction viscosity and exposure to isocyanate vapors is reduced because the amount of heat required is relatively low.

As mentioned above, the resulting hot melt adhesive, which is solid at room temperature, has 3000 to 50000 cps at 120 ° C (about 1500 to 25000 at 135 ° C).
cps and a viscosity in the range of 10000 to about 100000 cps at 108 ° C.) is suitable for application, and thus no tackifiers and / or plasticizers are needed to obtain an appropriate application viscosity. However, it is noted that small amounts of tackifiers or plasticizers may be added so that they are present to the extent that they do not impair the desired adhesive properties.

The adhesive not only crosslinks to form a strong heat resistant bond, but also exhibits high initial bond strength and cohesive strength, so that the bonded structure can already be handled easily even before curing and It can be entrusted to the subsequent processing steps. It is readily compatible with a wide range of applications where hot melt adhesives are commonly used. Requires high degree of heat resistance, such as lamination, bookbinding, labeling of bottles and bags, automobile interior assembly, production of non-woven products for medical applications, but not limited to these, during processing or sterilization. It is suitable for use in various applications.

These superior properties are partly due to the semi-internal penetration-
And the formation of internal infiltration networks and in some cases the formation of graft copolymers. A semi-interpenetrated network will be obtained when a urethane-prepolymer (thermosetting) is used together with a crosslinkable group-free radically polymerizable polymer (thermoplastic). If the radically polymerized polymer contains crosslinkable groups, a fully infiltrated network will be obtained. Grafting also occurs with certain urethane-prepolymer components, such as urethane-prepolymer components containing carbon atoms having tertiary hydrogen atoms. Such tertiary hydrogen atom is a potential grafting position for acrylic or vinylic monomers.

The invention is explained in more detail by the following examples of advantageous embodiments. However, these examples are provided for illustrative purposes only and, unless otherwise stated, do not limit the scope of the invention.

Example I (Reference Example) The reactor of Example 1 was equipped with a cooler, a gas introduction tube, a tube for slow addition, a thermometer, a stirrer, and heating / cooling equipment. Each reaction component is as follows: 1. Polypropylene glycol (1000 molar weight) 275.8g 2.1,6-hexanediol, neopentylglycol adipate (molecular weight 3000) 88.9g 3.1,6-hexanediol, Neopentyl glycol adipate (molecular weight 1000) 29.3g 4. Butyl methacrylate 17.8g 5. Butyl methacrylate 94.1g 6. Methyl methacrylate 9.4g 7. Methyl methacrylate 53.6g 8. Dodecyl mercaptan 0.68g 9. Benzoyl-peroxide 1.7g 10. Benzoyl peroxide 0.6 g 11. Methylene-bisphenyl-diisocyanate 131.1 g The reactor is purged with dry nitrogen gas and a slow stream of dry nitrogen is introduced below the liquid during the reaction to bubble. 1, 2,
The ingredients labeled 3, 4, 6, 8 and 9 are added to the reactor and the temperature is raised to 80 ° C. After 1/2 hour at 80 ° C., ingredients 5 and 7 are added uniformly over 1 hour. The reaction is maintained at 80 ° C. for a further 3 hours, at which time 10 ingredients are added. The reaction was continued at 80 ° C for another 2 hours and
Add 11 ingredients. Then the temperature is raised to 100 ° C. and maintained for 3 hours. At this point, a vacuum of 120 mm to 130 mm is charged to the reactor for 20 to 30 minutes and the reaction is poured hot from the flask.

Properties Methacrylate polymer (%) 25% Ratio of butyl methacrylate and methyl methacrylate 64/36 Urethane-prepolymer (%) 75% Isocyanate groups (%) 1.9% Viscosity at 100 ° C 64000cps Viscosity at 120 ° C 25250cps At room temperature Viscosity of solids Intrinsic viscosity in tetrahydrofuran / ethanol (9/1) 0.18 color Whiteness of water to very slight amber transparency Clear to very slight cloudiness Calculated molecular weight of urethane-prepolymer 3315 Isocyanate index 1.6 Example II (Reference Example) This experiment is carried out in the same manner as in Example I, but in reducing the viscosity of the system, the molecular weight of the urethane polymer is reduced as an alternative to reducing the molecular weight of the methacrylate resin. All factors are the same except for the following: Ingredients AB Butyl Methacrylate 18.0g 18.0g Butyl Methacrylate 102.0g 102.0g Methyl Methacrylate 10.1g 10.1g Ingredients (Subsequent) AB Methyl Methacrylate 57.4g 57.4g Dodecyl Mercaptan 0.63 g 0.72g benzyl peroxide 1.8g 1.8g methylene-bisphenyl 168.6g 168.6g-diisocyanate Properties AB methacrylate polymer (%) 25% 25% ratio of butyl methacrylate to 64-36 64-36 methyl methacrylate (%) urethane -Polymer (%) 75% 75% Isocyanate groups (%) 3.1% 3.3% Viscosity at 100 ℃ 53000cps 51000cps Viscosity at 120 ℃ Not measured 7062cps Viscosity at room temperature Solid Solid THF / Ethanol (9/1) 0.18 0.15 Medium Intrinsic viscosity in water Color Whiteness of water to very slight amber Transparency Transparent to very slight cloudiness Calculated molecular weight of urethane-polymer 2032 3315 Isocyanate index 2.0 2.0 Example III This example of 70% polypropylene glycol and (molecular weight 1000) 30%, in the prepolymer of NCO- content 2
%, 1,6-hexanediol-neopentyl glycol adipate-diol (molecular weight 200
0) and urethane-prepolymers are disclosed.

Each component Propylene glycol (Molecular weight 1000) 350.0 1,6-Hexanediol-neopentyl 150.0 Glycol adipate-diol (Molecular weight 2000) Methylene-bisphenyl-diisodia 166.4 nate Operation 1 Cooler, gas inlet tube, temperature Equipped with meter, stirrer and heating / cooling equipment. The reactor is purged with dry nitrogen gas and a slow stream of dry nitrogen is passed through the reactor. The polyol is added to the reactor and the temperature rises to 80 ° C. At this point diisocyanate is added, the reaction mixture is heated to 100 ° C. and maintained at this temperature for 4 hours. After a heating time of 4 hours, the reaction mixture is poured out of the reactor.

The properties of the urethane-prepolymer are as follows: Isocyanate groups (%) 2.3% Viscosity at 100 ° C 3200cps Viscosity at room temperature 80000cps Color Very slight amber Transparency Transparent Isocyanate index 1.6 IV (Comparative example) An example is US Pat. No. 39 using a mixture of polyurethane-prepolymer, thermoplastic and tackifier.
3 illustrates a hot melt adhesive according to 31077.

Prepolymer of Example III 60 CRL 715 (copolymer consisting of 35% n-butyl acrylate 5 and 65% ethylene: manufacturer USI: melt index 70) PRL-300 (terpene with a softening point of 108 ° C. 35-Phenol Resin: Manufacturer Reichhold Chemical) Urethane-prepolymer was placed in a 3-necked flask and heated to 167 ° F under an atmosphere of dry nitrogen gas to add and dissolve the two additional ingredients. Stir under a nitrogen atmosphere until. This adhesive is referred to as IVA.

A second hot melt adhesive (denoted as IVB) was added, as described above, to 10 parts of Exxon EX 170 (having a melt index of 2400 and consisting of 25% vinyl acetate and 75% ethylene), 25 parts P.
Prepared using RL-300 and 65 parts of the urethane-prepolymer of Example III.

Testing The following series of tests demonstrates the nature of the adhesives of the invention and the extent of their effect.

Tensile Strength and Elongation of Cured Films: This test measures the strength and elasticity of films. Tensile strength and elongation relate to the utility of the material as an adhesive. In general, materials with high tensile strength and suitable elongation exhibit better adhesion behavior than materials with weaker one or both properties.

In this test, the film is cast from the melt in the low energy plane, about 3-5 mils thick. (Films in this range should be used as relatively heavy films that develop excessive voids upon cooling.)
This film is kept at a constant room temperature (22 ℃) for 50 days.
Hardens by exposure to an atmosphere of% humidity.

Adhesion Test Samples were tested with various flexible substrates, 1.0 mil of hot melt adhesive applied to the substrates and laminated directly to a 3/8 ″ particle board, the laminate being at about 5 psi. Manufactured by subjecting to cold compression for 10 minutes at pressure, all samples are allowed to cure or crosslink for 1 week, then subjected to a 90 ° peel test at a pull rate of 12 inches per minute.

Heat resistance: Most hot melt adhesives are thermoplastic and will deform or flow when subjected to temperatures above 82 ° C. The inventor
A series of high temperature shear tests have been devised to measure resistance to flow or deformation at elevated temperatures up to 175 ° C.

This test uses a strip of 5 mil bare aluminum-foil overlay on a 3/8 "particle board coated with 1 mil of adhesive. All samples are cured for a week. Place in a circulating air oven at 108 ° C. with a load of 1 kg per square inch, leave them at this temperature for 15 minutes, then set the temperature to 120.
Raise to 0 ° C and observe for 15 minutes, then raise temperature again at regular intervals until peeling is observed.

Green Strength This test measures the bond immediately after application bonding. This is important for testing the strength of the uncured adhesive before curing. Sufficient green strength is necessary to hold the substrates together when stacked, while curing proceeds with atmospheric humidity. Green strength or direct bond strength prior to cure as well as cure rate are very important to the assembly or lamination process prior to full cure.

In this test, 2 mi of the adhesive sample melted at 120 ° C
Apply exactly 1.0 mil thickness of l mylar film and sandwich directly on 5 mil aluminum-foil. The resulting laminate of mylar / adhesive / foil is then placed directly on the Instron
Peel off with a tester (Instron tester) at 12 inches / minute.

Examples III and Comparative IV have low tensile strengths and Examples I and II show increased tensile strength with good elongation. In addition, Example II, which has a high NCO content, exhibits high strength.

Both Examples I and II provide excellent bonding to most substrates, and Example I provides excellent bonding to all substrates including Mylar. Bonding is performed on the fibers on the surface of the particle board. Example
II has a defective joint only to Mylar. Example II
I has a defective joint between foil and mylar. Comparative IVA is defective with Mylar and vinyl and Comparative IVB is defective with Mylar.

This test demonstrates the poor heat resistance of the comparative examples IVA and IVB (prior art examples) and the excellent heat resistance of Examples I and II. Example II is a type with a high NCO content and exhibits the highest heat resistance.

The above tests show that the hot melt adhesives of the invention are superior in terms of bond strength and especially heat resistance after storage to prepolymers without acrylics and those described in U.S. Pat. No. 3831077. It clearly shows that.

The following examples embody variations of the best mode embodiment to demonstrate the invention in various respects.

Example V (Reference Example) The procedure of Example I was followed by adding 0.8 g of dodecyl-mercaptan.
Repeat except 0.68g is used instead. This modification lowers the molecular weight of the methacrylate copolymer portion of the product (indicated by a decrease in intrinsic viscosity) and hence the product viscosity.

Properties: Methacrylate polymer (%) 25% Ratio of butyl methacrylate and methyl methacrylate 64/36 Urethane-prepolymer (%) 75% Isocyanate group (%) 2.0% Viscosity at 100 ℃ 18000cps Viscosity at room temperature Solid Tetrahydrofuran / Intrinsic viscosity in ethanol (9/1) 0.15 colors Water white to very slight amber transparency Clear to very slight turbidity Isocyanate index 1.6 Example VI (reference) It is carried out as in Example I except that the mercaptan chain transfer agent is reduced to 0.54 g in order to increase the molecular weight of the methacrylate polymer. Therefore, the viscosity is increased to be comparable to that of Example II.

The properties are as follows: Methacrylate polymer (%) 25% Ratio of butyl methacrylate and methyl methacrylate 64/36 Urethane-prepolymer (%) 75% Isocyanate groups (%) 3.0% Viscosity at 100 ° C 72000cps 120 Viscosity at ℃ 16 250cps Viscosity at room temperature Intrinsic viscosity in solid THF / Ethanol (9/1) 0.15 color Whiteness of water to very slight amber Clearness Transparent to very slight turbidity Isocyanate index 1.6 Example VII (Reference Example) This example is a modification of Example I in the following respects: 1) The ratio of methacrylate polymer to urethane-prepolymer is changed from 25/75 to 30/70.

2) Change the ratio of butyl methacrylate to methyl methacrylate from 64/36 to 80/20.

3) Change the composition of the urethane-prepolymer from polypropylene glycol, 1,6-hexanediol, neopentyl glycol-adipate-methylene-bisphenyl diisocyanate to propylene glycol-methylene-bisphenyl diisocyanate.

This example is carried out as in Example I with the following amounts.

Each component Polypropylene glycol (1000 molecular weight) 300.3g Butyl methacrylate 23.0g Butyl methacrylate 130.6g Methyl methacrylate 5.8g Methyl methacrylate 32.6g Dodecyl mercaptan 0.3g Benzoyl-peroxide 1.9g Benzoyl peroxide 0.6g Methylene-bisphenyl-diisocyanate 147.8g Properties are as follows. As follows: Methacrylate polymer (%) 30.0% Ratio of butyl methacrylate and methyl methacrylate 80/20 Urethane-prepolymer (%) 70.0% Isocyanate group (%) 3.9% Viscosity at 100 ° C 104000cps Viscosity at room temperature Intrinsic viscosity in solid THF / Ethanol (9/1) 0.19 colors Water whiteness Transparency Transparent to very slight turbidity Isocyanate index 2.0 Example VIII (reference example) It is demonstrated using the body. This example uses the following ingredients to prepare Example I
Perform in the same manner as

Each component Polypropylene glycol (1000 molecular weight) 326.4g Butyl methacrylate 150.0g Dodecyl mercaptan 0.3g Benzoyl-peroxide 2.0g Methylene-bisphenyl-diisocyanate 122.8 Properties: Acrylate polymer (%) 25.0% Urethane-prepolymer (%) 75.0% Isocyanate Group (%) 1.7% Viscosity at 100 ℃ 7200cps Viscosity at room temperature> 2.8 × 10 ⁶ Intrinsic viscosity in THF / Ethanol (9/1) 0.15 Color Brown Transparency Opaque Isocyanate Index 1.5 Example IX (reference example) Other isocyanates than methylene-bisphenyl-diisocyanate were used in this example. This example was carried out as in Example I with the following ingredients.

Formulation Polypropylene glycol (1000 molecular weight) 275.7g 1,6-hexanediol, neopentyl-adipatediol (molecular weight 2000) 118.2g Butyl methacrylate 17.8g Butyl methacrylate 94.1g Methyl methacrylate 9.1g Methyl methacrylate 53.6g Dodecyl mercaptan 0.68g Benzoyl-peroxide 1.7 g Benzoyl-peroxide 0.6g Methylene-biscyclohexyl-diisocyanate 137.4g Dibutyltin dilaurate 0.08g Properties: Methacrylate polymer (%) 25.0% Ratio of butyl methacrylate and methyl methacrylate 64/34 Urethane-prepolymer (%) 75.0% Isocyanate Group (%) 2.2% Viscosity at 120 ℃ 5000 cps (estimate) Viscosity at room temperature Intrinsic viscosity in solid THF / Ethanol (9/1) 0.13 Color Water whiteness Transparency Transparent Isocyanate Index 1.6 Example X (reference) Example) In this example Adds a catalyst to accelerate the cure rate. This reaction is also carried out using the procedure of Example I.

Formulation Polypropylene glycol (1000 molecular weight) 275.7g 1,6-hexanediol, neopentyl-adipatediol (molecular weight 2000) 118.2g Butyl methacrylate 17.8g Butyl methacrylate 94.1g Methyl methacrylate 9.4g Methyl methacrylate 53.6g Dodecyl mercaptan 0.68g Benzoyl-peroxide 1.7 g Benzoyl-peroxide 0.6g Methylene-biscyclohexyl-diisocyanate 131.1g Dibutyltin dilaurate 0.30g Properties: Methacrylate polymer (%) 25% Ratio of butyl methacrylate and methyl methacrylate 64/34 Urethane-prepolymer (%) 75% Isocyanate Base (%) 1.9% Viscosity at 100 ° C 84000cps Viscosity at room temperature Intrinsic viscosity in solid THF / ethanol (9/1) 0.17 Color Whiteness of water to very slightly amber Clear Haze cloudy haze Isocyanate Index 1.6 Example XI ( Reference Example) In this example, repeated Example I except replacing acrylate copolymerizable monomer in styrene. Each component and property are as follows.

Formulation Polypropylene glycol (1000 molecular weight) 275.7g 1,6-hexanediol, neopentyl-adipatediol (molecular weight 2000) 118.2g styrene 174.9g dodecyl mercaptan 0.68g benzoyl-peroxide 1.7g benzoyl-peroxide 0.6g methylene-bisphenyl-diisocyanate 131.1 g Properties: Styrene polymer (%) 25% Urethane-prepolymer (%) 75% Isocyanate groups (%) 1.7% Room temperature viscosity Solid viscosity in solid THF / ethanol (9/1) 0.23 color Yellowish Opacity Transparency Turbid Isocyanate Index 1.6 Example XII (Reference Example) Example I is repeated substituting vinyl acetate for the acrylate copolymer. Each component and property are as follows.

Each component polypropylene glycol (1000 molecular weight) 275.7g 1,6-hexanediol, neopentyl-adipatediol (molecular weight 2000) 118.2g vinyl acetate 174.9g dodecyl mercaptan 0.68g benzoyl-peroxide 1.7g benzoyl-peroxide 0.6g methylene-biscyclohexyl- Diisocyanate 137.4g Properties: Vinyl acetate polymer (%) 25% Urethane-prepolymer (%) 75% Isocyanate groups (%) 2.0% 121 ° C viscosity 1800cps Room temperature viscosity> 4 × 10 ⁶ cps THF / ethanol ( Intrinsic viscosity in 9/1) 0.15 colors Amber tinged transparency Turbid Isocyanate Index 1.6 Example XIII This example is a commercial low molecular weight polymer for making hot melt adhesives according to embodiments of the present invention. It demonstrates the case of adding. Elvacite 2013 is
64% of an intrinsic viscosity of 0.2 available from DuPont
Butyl methacrylate / 36% methyl methacrylate-copolymer. Immediately before use, the elvasit is dried under reduced pressure in a desiccator for 24 hours.

Ingredients Polypropylene glycol (1000 molecular weight) 472.9g 1,6-hexanediol, neopentyl-adipatediol (molecular weight 2000) 202.7g Elvasit 2013 300.0g Methylene-bisphenyl-diisocyanate 224.9g Operation: Polyol and Elvacit 2013 in reactor Introduced,
Ervasit Heat to 100 ° C until dissolved. At that point methylene-bisphenyl-diisocyanate is added and the reaction is carried out at 100 ° C. for 3 hours. After 3 hours at 100 ° C., the reaction mixture is poured hot from the reactor. This sample has the following properties: Properties: Methyl acrylate polymer (%) 25% Urethane-prepolymer (%) 75% Isocyanate groups (%) 2.0% Viscosity at 100 ° C 86000cps Viscosity at 120 ° C 8000cps Viscosity at room temperature Intrinsic viscosity in solid THF / Ethanol (9/1) 0.25 Color White of water Transparent Clear to very slightly cloudy Isocyanate index 1.6 Test result Ultimate tensile strength 1700psi Elongation (%) 400% 120 ℃ Viscosity stability at first: 8000cps after 8 hours 12125cps Bonding strength (foil / mylar): Immediately 908g 1 hour 1025g 2 hours 1040g 3 hours 1100g 24 hours 1750g Adhesion test (90 ℃ peeling): Mylar 1.7lbs 5mil foil 5.5lbs Wood pattern vinyl 6.9lbs White vinyl 5.7lbs Heat resistance (2psi): 180 ℃ OK 120 ℃ OK 134 ℃ OK 150 ℃ OK 162 ℃ Peeling after 10 minutes Example XIV Additional to compare initial (raw) strength characteristics Adhesive (1
~ 4) is prepared according to the present invention using the procedure described above. Five adhesives are prepared according to U.S. Pat. No. 3968089, Examples II, III, IV, V and IX (labeled 5-9 respectively).

The components of the raw materials used and their amounts (g) are shown in Table I below.

Intrinsic viscosity, isocyanate index and viscosity at room temperature
Shown in Table II.

The following test methods are used to test the initial (green) strength performance of each adhesive. The test results are listed in Table III.

Peeling test: Apply an adhesive (direct or transfer) heated to about 120 ° C to a wood grain vinyl substrate to a thickness of 1.0 to 1.5 mil, and
/ 8 "thick particle board for 3-5 seconds
Compress at a pressure of 5 lbs. This sample is peeled off with a peeling tester such as an Instron tester at a speed of 5 ″ / min at an angle of 90 ° (sample size: 1 /
2 "width, 3-4" length). The sample is peeled off immediately after compression (ie within 1-2 minutes).

Lap Shearability: Apply 5 mil standard size aluminum (directly or by transfer) to an adhesive heated to about 120 ° C to a thickness of 2-3 mils. The coated aluminum is compressed with a 3/8 "thick particle board for about 3-5 minutes at a pressure of about 5 lbs. The sample is a tensile tester (eg Instron-
With a tester), pull at an angle of 180 ° at a speed of 0.2 inch / minute. (Sample size = 1/2 "x 1/2" bonded area). The sample is pulled immediately after compression (ie within 1-2 minutes).

Various modifications and alterations are the embodiments of the present invention described above, and do not depart from the scope of the invention defined in the claims, and therefore demonstrate all the inventions described in the specification. Obviously, this need not be the case and the above examples do not limit the invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Erwin Davis, Brittany Water, Meadow Road, New Jersey, United States, 678 (56) Reference JP-A-52-123436 (JP, A) JP-A-SHO 53-21236 (JP, A) JP 52-37936 (JP, A) JP 50-122534 (JP, A) JP 49-98445 (JP, A)

Claims (7)

[Claims] 1. A) prepared by condensation polymerization of polyisocyanate and polyol of 5 to 90% by weight and 0.25 to 15%
Urethane prepolymers having an isocyanate content of 1 and an isocyanate index greater than 1 and not greater than about 2; and b) 10-95% by weight of active hydrogen-free acrylic acid-
Or a low molecular weight polymer obtained by polymerizing methacrylic acid C ₁ -C ₁₂ -ester and having an intrinsic viscosity of 0.1-0.4 measured by dissolving in a 9: 1 mixture of tetrahydrofuran and alcohol and A room temperature solid, solvent-free polyurethane-hot melt adhesive composition having a viscosity of 3,000 to 50,000 cps at 120 ° C. in the absence of tackifiers and / or plasticizers. 2. The hot melt adhesive composition according to claim 1, wherein the urethane prepolymer is produced by condensation polymerization of diol and diisocyanate. 3. Acrylic acid- or methacrylic acid C ₁ -C
The hot melt adhesive composition according to claim 1, wherein the ₁₂ -ester is polymerized to an intrinsic viscosity of 0.1 to 0.4. 4. A polyol-substituted or unsubstituted polyalkylene-ether-glycol or polyhydroxy-polyalkylene ether, a polyhydroxy-polyester, an ethylene oxide- or propylene oxide adduct of a polyol and a mono-substituted glycol. The hot melt adhesive composition according to claim 1, which is selected from the group consisting of esters. 5. Polyisocyanate is ethylene diisocyanate, ethylidene diisocyanate, propylene-
Diisocyanate, butylene-diisocyanate, hexamethylene-diisocyanate, toluene-diisocyanate, cyclopentylene-1,3-diisocyanate, cyclohexylene-1,4-diisocyanate, cyclohexylene-1,2-diisocyanate, 4,4 ′
-Diphenylmethane-diisocyanate, 2,2, -diphenylpropane-4,4'-diisocyanate, p-
Phenylene-diisocyanate, m-phenylene-diisocyanate, xylylene-diisocyanate, 1,4
-Naphthylene-diisocyanate, 1,5-naphthylene-diisocyanate, diphenyl-4,4'-diisocyanate, azobenzene-4,4'-diisocyanate, diphenylsulfone-4,4'-diisocyanate, dichlorohexamethylene-diisocyanate, furfuridene-diisocyanate , 1-chlorobenzene-
2,4-diisocyanate, 4,4 ', 4 "-triisocyanate-triphenylmethane, 1,3,5-triisocyanate-benzene, 2,4,6-triisocyanate-toluene and 4,4'-dimethyldiphenylmethane A hot melt adhesive composition according to claim 1 which is selected from the group consisting of -2,2 ', 5,5'-tetraisocyanate. 6. The hot melt adhesive composition according to claim 1, having a free isocyanate content of less than 4%. 7. The hot melt adhesive composition according to claim 6, which has a free isocyanate content of less than 1%.