JPH11172223A - Solventless two-component curable adhesive composition and laminate film prepared by using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a solventless adhesive which is suitable for producing a laminated film used for food packaging. etc. and in which processibility and physical properties can be consistent with each other. SOLUTION: This compsn. comprises a major component contg. a hydroxyl compd. and a curative component contg. an isocyanate compd. The viscosity at 40 deg.C of the compsn. just after the two components are mixed with each other is 100-20,000 cP, and the viscosity increase at 40 deg.C after 1 hr is 0-1,000%. The compsn. is used for laminating a plurality of films to give a laminated film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solvent-free, two-part curable adhesive composition and a laminated film bonded using the same, and more particularly, to the field of flexible packaging, for example, plastic film for food packaging. The present invention relates to a solvent-free two-component adhesive composition suitable for the production of a laminated product and a laminate film using the same.

[0002]

2. Description of the Related Art Conventional laminating adhesives for bonding various plastic films, metal-deposited plastic film films and metal foils include polyester resin / polyisocyanate compound type, polyether polyurethane resin / isocyanate compound type and polyester polyurethane resin. 2. Description of the Related Art Two-part curable organic solvent adhesives comprising a main agent containing a hydroxyl group-containing compound such as a polyisocyanate compound and a curing agent containing a polyisocyanate compound have been used.

[0003] In recent years, there has been an increasing shift to solventless organic solvent-based adhesives in response to labor work environment measures and solvent regulations. As such a solventless (non-solvent) type laminating adhesive, a polyurethane-based adhesive composition obtained by blending an organic polymer polyol compound and a polyisocyanate compound has been used.

[0004]

However, these solventless laminating adhesives have the disadvantage that they have high viscosity and are inferior in workability. Specifically, there are problems such as occurrence of misting at the time of coating, low coating speed, rough coating surface, and non-uniformity of film thickness. To solve such a problem,
Conversely, when the viscosity is reduced, there is a problem that it is difficult to secure a coating amount as workability, and there is also a problem that an adhesive force is insufficient in physical properties.

In order to solve such problems, a low molecular weight compound is added to a conventional solventless adhesive; the molecular weight of the isocyanate-containing polyurethane or the hydroxyl group-containing polyurethane contained in the conventional adhesive is reduced. A method of making the skeleton structure of the polyurethane itself irregular has been adopted, but a solventless adhesive capable of achieving both workability and physical properties has not yet been obtained.

[0006]

Means for Solving the Problems In view of such a situation, the present inventors have conducted research on developing a solventless adhesive capable of achieving both good workability and physical properties. The appearance of defects in a laminated film using a solvent-type adhesive is caused by unevenness on the surface of the coated adhesive when laminating the laminated film, and the film is stuck in the laminating part with air entrained. It has been found that the curing of the adhesive is fast, and that the curing of the adhesive is completed before leveling occurs.

As a result of studying a method for solving the above-mentioned phenomenon, the present inventors have slowed the increase in viscosity over time after mixing an adhesive composed of two liquids, a main agent and a curing agent, and after winding the film, By promoting the leveling of the adhesive, the appearance defect of the film laminated with the air entrained by the unevenness generated at the time of coating the adhesive can be eliminated, while the adhesive strength can be reduced by the normal aging time (after the leveling) 48 hours), and it was revealed that the expression occurred by curing, and based on this finding, the present invention was completed.

That is, the present invention comprises a main agent containing a hydroxyl group-containing compound and a curing agent containing an isocyanate group-containing compound.
A solvent-free two-part curable adhesive composition, wherein the adhesive composition has a viscosity increase rate of from 0 to 1,000% after being left at 40 ° C. for 1 hour, and the adhesive composition. Is a laminated film obtained by laminating a plurality of films using the above method.

[0009]

Next, the present invention will be described in more detail with reference to preferred embodiments. The adhesive composition of the present invention,
Consisting of a main agent containing a hydroxyl group-containing compound and a curing agent containing an isocyanate group-containing compound, each containing no solvent and having a viscosity of 100 cps to 20,000 cps at 40 ° C. immediately after mixing these two liquids (agents). And 40 ° C
Of the viscosity after leaving for 1 hour at 0 to 1,000
%, Preferably 0 to 200%, and is characterized by a slow rise in viscosity over time after mixing. In the present invention, the “viscosity increase rate” means that a viscosity of 100 cps becomes a viscosity of 200 cps and a 100% viscosity increases.

The hydroxyl group-containing compound constituting the main component in the present invention is preferably at least one organic polymer polyol selected from the group consisting of polyester polyols, polyether polyols, polyether ester polyols and polyurethane polyols.

Examples of the polyester polyol include polycarboxylic acids such as isophthalic acid, terephthalic acid, adipic acid, azelaic acid, and sebacic acid, and dialkyl esters thereof, and mixtures thereof.
Polyester polyols obtained by an esterification reaction with glycols such as ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, neopentyl glycol, and 1,6-hexanediol, or a mixture thereof, and further, a ring-opening polymer of lactone. Certain polycaprolactone diols are mentioned. Particularly preferred is poly-ε-caprolactone diol.

Examples of the polyether pole include, for example,
Ethylene oxide, propylene oxide, butylene oxide, oxirane compounds such as tetrahydrofuran, for example, water, ethylene glycol, propylene glycol, trimethylolpropane, polyether polyol obtained by polymerizing with a low molecular weight polyol such as glycerin as an initiator. Can be

As the polyetherester polyol, for example, a polycarboxylic acid such as isophthalic acid, terephthalic acid, adipic acid, azelaic acid, sebacic acid or a dialkyl ester thereof or a mixture thereof is reacted with the above polyether polyol. And the like.

As the polyurethane polyol, for example, the above-mentioned polyester polyol, polyether polyol, polyether ester polyol or the like is reacted with a polyisocyanate described later or a multimer such as a trimer to heptamer under the condition that a hydroxyl group remains. And the like.

In the present invention, the molecular weight and the molecular weight distribution of the above-mentioned hydroxyl group-containing compound are extremely important factors for controlling the viscosity of the mixture of the main agent and the curing agent within the above range. That is, the hydroxyl group-containing compound has a number average molecular weight of 500 to 10,000 and a weight average molecular weight (M
It is preferable that the molecular weight distribution (Mw / Mn) represented by the ratio of w) to the number average molecular weight (Mw) be 1.2 to 3.0.

If the number average molecular weight is less than 500, the viscosity of the obtained adhesive composition is too low to obtain a proper coating amount, while the number average molecular weight is 10,000.
When the viscosity exceeds the above range, the viscosity of the obtained adhesive composition becomes too high, and irregularities are formed on the surface of the coating film at the time of coating. The preferred number average molecular weight is from 800 to 5,000, and the more preferred number average molecular weight is from 1,000 to 3,000.

When the molecular weight distribution is less than 1.2,
When the viscosity of the obtained adhesive composition is too low, it is difficult to obtain a proper coating amount. On the other hand, when the molecular weight distribution exceeds 3.0, another appearance defect due to causes other than the above is likely to occur, which is preferable. Absent. The average molecular weight, molecular weight distribution and the like in the present invention were measured by the following methods.

Measurement method The average molecular weight was determined by a terminal group quantification method by titration, and the molecular weight distribution was determined by gel permeation chromatography (GPC). The terminal hydroxyl group is determined by an acetylation method, that is, after performing an acetylation reaction by adding an acetylating agent to a sample, decomposing unreacted acetic anhydride in the acetylating agent with a decomposing agent (pyridine), and removing excess acetic acid. It was determined by back titration with a 1 mol / liter KOH / methanol standard solution using an automatic titrator. The terminal isocyanate group was determined by reacting a sample with an amine, and back-titrating excess amine with hydrochloric acid using a potentiometric titrator. The molecular weight distribution was measured using tetrahydrofuran as a solvent, and calculated from Mn and Mw.

In the present invention, the isocyanate group-containing compound constituting the curing agent includes, for example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylylene diisocyanate, tetramethyl xylylene diisocyanate, lysine isocyanate, m Phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate,
2,2'-diphenylmethane diisocyanate, 3,
3'-dimethyl-4,4'-biphenylene diisocyanate, 3,3'-dimethoxy-4,4'-biphenylene diisocyanate, 3,3'-dichloro-4,4'-biphenylene diisocyanate, 1,5-naphthalene diisocyanate Aromatic isocyanate compounds such as 1,5-tetrahydronaphthalene diisocyanate, aliphatic isocyanate compounds such as tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, and trimethylhexamethylene diisocyanate; Silylene diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 3,3'-dimethyl-4,
Alicyclic isocyanate compounds such as 4'-dicyclohexylmethane diisocyanate and the like and difunctional or trifunctional or higher polyfunctional isocyanate compounds such as isocyanurates, burettes and allophanates derived from these isocyanate compounds, or the above isocyanates Reaction of a compound with a bifunctional isocyanate compound containing a terminal isocyanate group or a isocyanate compound obtained by reacting a compound with a bifunctional hydroxyl group-containing compound such as polyether polyol or polyester polyol, and a trifunctional or higher functional polyol compound such as trimethylolpropane or glycerin. And a polyfunctional isocyanate compound containing a terminal isocyanate group.

In particular, as the isocyanate group-containing compound, a polyurethane polyisocyanate using an aliphatic isocyanate compound, a polyfunctional isocyanate compound having a triazine skeleton, and particularly, trimer, pentamer, and heptamer of aliphatic isocyanate It is preferable to use a polymer such as a body or a mixture thereof because the effect of suppressing an increase in viscosity of the adhesive after mixing the two liquids is large.

Conventional solventless adhesives often use a polyurethane-based adhesive comprising a main agent containing a hydroxyl group-containing compound and a curing agent containing an isocyanate group-containing compound, and are mixed at the stage of producing either one. It is considered that the increase in viscosity during aging is severe due to the residual catalyst. For this reason, the occurrence of poor appearance after coating is maintained even after curing.

However, according to the present invention, by using a composition in which the above-mentioned catalyst residue is reduced as much as possible, it is possible to suppress an increase in viscosity after mixing the two liquids. Therefore, the molecular weight and the molecular weight distribution of the hydroxyl group-containing compound are controlled to a specific range, and preferably, an aliphatic compound is used as the isocyanate group-containing compound, and the reduction of the above-mentioned catalyst residue is combined. (2) It is possible to further suppress the increase in viscosity of the adhesive after mixing the two liquids.

When the solvent-free adhesive composition of the present invention is used, a known softener conventionally used in solvent-type polyurethane adhesives and the like is used together with the above-mentioned hydroxyl group-containing compound and isocyanate group-containing compound. If necessary, additives such as an antioxidant, an adhesion promoter, a leveling agent, an antifoaming agent, a plasticizer, and a tackifying resin may be used. The type and amount of these additives may be appropriately selected according to the performance required for the adhesive, and are not particularly limited. Examples of the adhesion promoter include a silane coupling agent, a titanate-based coupling agent, an aluminum-based coupling agent, an epoxy resin, and the like.

As the silane coupling agent, for example,
γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β (aminoethyl)-
aminosilanes such as γ-aminopropyltrimethoxysilane, N-β (aminoethyl) -γ-aminopropyltrimethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane; β- (3,4-epoxycyclohexyl) ethyl Epoxy silanes such as trimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane; vinyltris (β-methoxyethoxy) silane, vinyltriethoxysilane, vinyltrimethoxysilane, γ-methacrylic Vinyl silane such as roxypropyltrimethoxysilane; hexamethyldisilazane; γ-mercaptopropyltrimethoxysilane;

Examples of titanate coupling agents include tetraisopropoxytitanium, tetra-n-butoxytitanium, butyl titanate dimer, tetrastearyl titanate, titanium acetylacetonate, titanium lactate, tetraoctylene glycol titanate,
Tetrastearoxy titanium etc. are mentioned. Examples of the aluminum-based coupling agent include acetoalkoxyaluminum diisopropylate and the like.

Examples of the epoxy resin include epbis type, novolak type, β-methyl epichloro type, cyclic oxirane type, glycidyl ether type, glycidyl ester type, polyglycol ether type, glycol ether type, epoxidized fatty acid ester type and polyvalent. Various epoxy resins such as carboxylic acid ester type, aminoglycidyl type, resorcinol type and the like can be mentioned.

[0027] The solvent-free two-part curable adhesive composition of the present invention comprises a main agent containing the above-mentioned hydroxyl group-containing compound and the above-mentioned additives optionally used, and the above-mentioned isocyanate group-containing compound and optionally used. It consists of a curing agent containing the above-mentioned additives. When used, usually, a hydroxyl group (OH) in the main agent and an isocyanate group (NCO) in the curing agent are used.
Are mixed so that the equivalent ratio (NCO / OH) becomes 1.0 to 1.5.

Next, a laminate film produced using the adhesive composition of the present invention will be described. Examples of the base material of the laminate film of the present invention include polyamides such as biaxially oriented polypropylene (PP), unoriented PP, polyethylene terephthalate (PET), polyethylene (PE), polyvinyl chloride (PVC), various nylons, and the like.
Various plastic films such as polyvinyl alcohol (PVA), polyvinylidene chloride-based resin coat PP, polystyrene, ethylene-vinyl alcohol copolymer resin (EVOH), polycarbonate, cellophane, various metal-deposited plastic films, and metal foils can be used. . The type of the film substrate may be selected in accordance with the intended use (use) of the laminated film, and the type of the film substrate is not particularly limited in the present invention.

The laminated film of the present invention can be manufactured by a conventionally known method except that the adhesive of the present invention is used, and the manufacturing method is not particularly limited. An example of the manufacturing method will be described below. Laminating a plurality of film bases is performed by mixing a main component containing the above polyol component and a curing agent containing an organic polyisocyanate component to form an adhesive, and heating the mixture to 30 to 100 ° C. The adhesive is given fluidity, and the coating amount is 0.1 to 5 g / m ² (dr
y) is applied to one of the film substrates, and the adhesive applied surface and the other film substrate are laminated by a nip roll. The method of applying the solventless adhesive can be a conventionally known method, and is not particularly limited. Laminate is 30-50 ° C to promote crosslinking
Aging for about 12 to 60 hours.
As described above, the use of the solvent-free adhesive composition of the present invention, in which the increase in viscosity of the adhesive over time after mixing of the two components is suppressed, has excellent adhesion, has a smooth surface, and has an appearance. A good laminated film is obtained.

[0030]

Next, the present invention will be described more specifically with reference to examples and comparative examples. Comparative Example 1 80 parts by weight of Takeda A31 manufactured by Takeda Pharmaceutical Co., Ltd. was mixed with 100 parts by weight of Takelac A231 manufactured by Takeda Pharmaceutical Co., Ltd. using a two-liquid mixing and feeding device and heated to 60 ° C. PET film (12μ)
the m thick) was coated so as the coating amount is 2.0 g / ^{m 2,} the coated surface is the second film substrate deposited unoriented PP film (VMCPP: pasting a 25μm thick) and using a lamination roll Together, a laminated film was manufactured. After manufacturing the laminated film,
After aging for 8 hours, the sheet was cut, and the surface of the laminate film was partially uneven.

The above two liquids were mixed at 40 ° C., and the results of changes in viscosity over time measured while aging the mixture at this temperature are shown in Table 1 and FIG. The viscosity is measured by a viscoelasticity measuring device R
It was measured at a shear rate of 0.025 S ^-1 using FS-II (the same applies to the following comparative examples and examples).

COMPARATIVE EXAMPLE 2 100 parts by weight of NSC 85-88A was added to NSC 85-88A.
100 parts by weight of -88C were mixed and heated to 60 ° C., and this was coated on the above-mentioned PET film as the first film substrate by a solventless roll coater so that the coating amount was 2.0 g / m ^2. Then, the coated surface was bonded to the above-mentioned VMCPP film as the second film substrate in the same manner as described above to produce a laminated film. After aging at 40 ° C for 48 hours after manufacturing the laminated film,
As a result of the cutting, irregularities were partially formed on the surface of the laminate film. The above two liquids were mixed at 40 ° C., and the results of the change in viscosity over time measured while aging the mixture at this temperature are shown in Table 1 and FIG.

Comparative Example 3 Poly-ε-caprolactone diol (number average molecular weight: about 8
50) 500 parts of dibutyltin octylate in 100 parts by weight
pm, and the mixture was heated to 60 ° C. and reacted for 3 hours while dropping 10 parts by weight of hexamethylene diisocyanate, and the number average molecular weight was about 1900 and Mw / Mn was 3.5.
Was obtained.

Next, a trifunctional polyisocyanate compound (Coronate HX, manufactured by Nippon Polyurethane Industry Co., Ltd.) was added to 480 parts by weight of the polyester-type polyurethane polyol.
0 parts by weight were mixed and heated to 60 ° C., and the obtained adhesive was applied to the above-mentioned PET film as the first film substrate with a solventless roll coater so that the coating amount was 2.0 g / m ^2. Then, the coated surface was adhered to the above-mentioned VMCPP film as the second film substrate in the same manner as described above to produce a laminated film. After the laminate film was manufactured, it was aged at 40 ° C. for 48 hours, and then cut. As a result, the surface of the laminate film was partially uneven. The above two liquids were mixed at 40 ° C., and the results of the change in viscosity over time measured while aging the mixture at this temperature are shown in Table 1 and FIG.

Example 1 Poly-ε-caprolactone diol (manufactured by Daicel Chemical:
Praxel 220AL, number average molecular weight about 2000, Mw
/Mn=2.8) 500 parts by weight of trifunctional polyisocyanate compound (Nippon Polyurethane Industry: Coronate H)
X) 100 parts by weight were mixed and heated to 60 ° C., and the mixture was coated with a solvent-free roll coater on the PET film as the first film substrate so that the coating amount was 2.0 g / m ^2. Then, the coated surface was bonded to the above-mentioned VMCPP film as the second film substrate in the same manner as above to produce a laminated film. After the laminate film was manufactured, it was aged at 40 ° C. for 48 hours, and then cut. As a result, the surface of the laminate film was smooth. The above two liquids were mixed at 40 ° C., and the results of the time-dependent viscosity change measured while aging the mixture at this temperature are shown in Table 1.
And FIG.

Example 2 100 parts by weight of diphenylmethane diisocyanate were added to 60 parts
C. and reacted for 3 hours while dropping 320 parts by weight of polypropylene glycol having a number average molecular weight of about 400 to obtain a polyether type polyurethane polyol having a number molecular weight of about 1,100 and Mw / Mn of 2.0. Next, 100 parts by weight of a trifunctional polyisocyanate compound (manufactured by Nippon Polyurethane Industry Co., Ltd .: Coronate HX) was mixed with 300 parts by weight of this polyether-type polyurethane polyol, and
The mixture was heated to 0 ° C., and the mixture was applied to the above-mentioned PET film as the first film substrate by a solvent-free roll coater in an amount of 2.0
g / m ^2, and the coated surface was bonded to the above-mentioned VMCPP film as the second film substrate in the same manner as described above to produce a laminated film. After the laminate film was manufactured, it was aged at 40 ° C. for 48 hours, and then cut. As a result, the surface of the laminate film was smooth. The above two liquids were mixed at 40 ° C., and the results of the time-dependent viscosity change measured while aging the mixture at this temperature are shown in Table 1 and FIG.

[0037]

[Table 1] (Note)-: Cannot be measured due to high viscosity

[0038]

According to the present invention, the increase in viscosity over time is suppressed, the adhesive strength is excellent, the appearance after laminating the film is good, and it is suitable for the production of various laminated films used for foods and other uses. The present invention provides a solventless two-part curable adhesive.

[Brief description of the drawings]

FIG. 1 is a diagram showing a change in viscosity over time of adhesives of Examples and Comparative Examples.

Claims (7)

[Claims] 1. A composition comprising a main agent containing a hydroxyl group-containing compound and a curing agent containing an isocyanate group-containing compound, and having a viscosity of 100 cps to 2 at 40 ° C. immediately after mixing the two agents.
A solvent-free two-part curable adhesive composition, which has a viscosity of 000 cps and a rate of increase in viscosity after leaving at 40 ° C. for 1 hour of 0 to 1,000%. 2. The adhesive composition according to claim 1, wherein the hydroxyl group-containing compound is at least one polymer polyol selected from the group consisting of polyester polyols, polyether polyols, polyether ester polyols and polyurethane polyols. 3. The hydroxyl group-containing compound having a number average molecular weight of 5
The adhesive composition according to claim 1, wherein the number is from 00 to 10,000. 4. The molecular weight distribution (weight average molecular weight Mw / number average molecular weight Mn) of the hydroxyl group-containing compound is 1.2 to 3.0.
The adhesive composition according to any one of claims 1 to 3, wherein 5. The adhesive composition according to claim 1, wherein the isocyanate group-containing compound is a polyurethane polyisocyanate using an aliphatic isocyanate compound. 6. The adhesive composition according to claim 1, wherein the isocyanate group-containing compound is a trifunctional or higher polyisocyanate compound having a triazine skeleton. 7. A laminate film comprising a plurality of films bonded to each other using the adhesive composition according to claim 1.