JPS58129078A - Laminating urethane adhesive composition - Google Patents

Abstract

PURPOSE:The titled composition, prepared by incorporating a specific polyol component with a specific urethane prepolymer containing terminal isocyanate groups to give a specific ratio between the hydroxyl groups and the isocyanate groups, and having improved initial adhesive property and heat resistance with a small amount of the residual solvent. CONSTITUTION:A laminating urethane adhesive composition prepared by incorporating (A) a polyol component obtained by mixing a trifunctional polyether polyol having 400-1,000 molecular weight, e.g. trifunctional polypropylene glycol, with a polyfunctional polyester polyol, having 400-1,300 molecular weight, e.g. glycol adipate at (100:15)-(100:100) ratio with (B) a urethane prepolyer obtained by reacting one mole polyether diol having 400-1,000 molecular weight, e.g. polyethylene glycol, with 1.5-2.0mol diisocyanate, and having terminal isocyanate groups at 1-1.5 equivalent ratio between the NCO groups in the component (B) and OH groups in the component (A).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a urethane adhesive composition for laminating which has excellent initial adhesion, heat resistance, and very little residual solvent.

BACKGROUND ART Conventionally, two or three or more layers of paper, metal foil, plywood, plastic film, etc. laminated have been developed for various purposes.

In particular, with recent improvements in dietary habits, the variety of foods that are packaged using laminate films has increased, and as a result, the performance of adhesives used in the production of laminate products has improved, such as adhesive properties, heat resistance, Improved drying performance is required, and lamination in this case is carried out using the dry lamination method. In other words, a solvent-based adhesive is applied in advance to one of the composite films, and the solvent is volatilized in a dryer (dry laminator) to activate the lamination. A common method is to laminate the film with the other film at a certain stage (when initial adhesion is developed). The adhesive composition used in this case is (a) made by partially reacting incyanate with a polymer hydroxide such as polyester, polyether, castor oil, or popal, which has a hydroxyl group at the end, and So-called two-component urethane adhesive compositions are widely used, in which a main agent having a hydroxyl group and a curing agent having an incyanate group are mixed together during adhesion.

In order to make the adhesive composition easier to handle, the molecular weight of the component (a) is first increased to 10,000 to 50,000 to increase the pot life.

The molecular weight of component (o) is 500 to 1,000, and the viscosity of the whole is adjusted by adding 70 to 80 1% by weight of a solvent to components (a) and (b).

For this reason, when laminating films, a large amount of heat source and a lot of time are required to remove the solvent, and it takes a considerable amount of time to exhibit initial adhesion, which hinders the speed of work efficiency. In addition, removing a large amount of solvent is not only unfavorable from an environmental standpoint, but also leaves a considerable amount of solvent in the adhesive layer of laminated products after bonding, which often causes peeling. It was not suitable for food hygiene as an adhesive used in laminated products.

In order to solve these problems, the present inventors have carried out extensive research and found that when polyether polyol and polyester polyol, which do not contain incyanate as the main ingredient, are used in a certain ratio, It has been found that a two-component urethane adhesive composition for laminating can be obtained, which can be applied even when the amount of solvent used is 30% by weight or less, has a long pot life, and has excellent initial adhesion, heat resistance, etc. Heading, the invention was completed.

That is, in the present invention, a trifunctional polyether polyol with a molecular weight of 400 to 1000 and a polyfunctional polyester polyol with a molecular weight of 400 to 1300 are mixed in a ratio of 100:15 to 100.
: Polyol component mixed in a ratio of 100, 0 molecules t
A urethane prepolymer having an isocyanate group at the terminal, which is obtained by reacting 1.5 to 2.0 moles of diincyanate with 1 mole of polyether diol of 400 to 1000; The proportion of incyanate groups in the components is equivalent to NC010H = 1
1.5.

The polyether polyol used in the present invention, the component, has a trifunctional hydroxyl group in its molecule, and if it is difunctional, the crosslinking density after adhesion is low, and it does not have sufficient boiling resistance, heat resistance, chemical resistance, etc. I don't like it.

The polyfunctional polyester polyol used in the present invention may have an average functional number of hydroxyl groups of more than 2, but preferably has an average functional number of 3 and contains 1% of trifunctional hydroxyl groups as the main component. The most preferable case is a polyester polyol having the following properties. If the average number of functional groups is 2 or less, the crosslinking density after adhesion will be low, resulting in poor boiling resistance, heat resistance,
It is not preferable because its chemical resistance is insufficient. Furthermore, if the number of functional groups is extremely large, for example 5 or more, the pot life will be shortened, which is not preferable.

Regarding molecular weight, polyether polyol 1'! 40
0 to 1000, but polyester polyol is 400 to 1
300 is preferable, and if the molecular weight of both the polyether polyol and the polyester polyol is smaller than 400, the amount (wt%) blended with respect to the 0 component will be small, so the viscosity as an adhesive composition will become too high, which is undesirable. becomes unstable and the reaction becomes faster,
It has a short pot life and is difficult to handle, making it unsuitable for use in adhesive compositions.

If the molecular weight exceeds 1000 for polyether polyols and 1300' for polyester polyols, the crosslinking density after adhesion will be low and boil resistance, heat resistance, chemical resistance, etc. will deteriorate, which is undesirable.

The mixing ratio of polyether polyol and polyester polyol is 100 parts by weight of polyether polyol (hereinafter referred to as
polyester polyol is 15 to 10
0 parts is preferable, and if it is less than 15 parts, heat resistance, boiling resistance, chemical resistance, etc. will be poor. If the amount exceeds 100 parts, the pot life of the adhesive will be shortened, making it difficult to handle during bonding.

It is obtained by reacting polyether with diisocyanate, but if the number of hydroxyl groups in the polyether molecule exceeds 2 (bifunctional), the viscosity increases, making it difficult to mix with diisocyanate, and the reaction becomes uneven, resulting in poor adhesion. This is not desirable because stable adhesion cannot be obtained as an agent. For incyanate, for the same reason as polyether, it is not preferable if there are more than two incyanate groups in the molecule.

The molecular weight of polyether diol is 400-10
00 is used. If it is less than 400, the hydrogen bonds between molecules are strong and the viscosity becomes high, and the coated film becomes hard and brittle and the adhesiveness decreases. Moreover, if it is more than 1000, the L coating film becomes soft and has poor heat resistance, boiling resistance, etc., which is not preferable.

The method for producing component I3 is a general synthesis method employed when synthesizing urethane prepolymers.

The trifunctional polyether polyols among the four components used in the present invention include trifunctional polyols such as glycerin and trimethylolpropane, or trifunctional polyols obtained by reacting these trifunctional polyols with ethylene oxide, propylene oxide, or the like. Polyfunctional polyester polyols include reactants of polybasic acids and low-molecular polyols, such as 1) dibasic acids such as adipic acid, dodecanoic acid, azelaic acid, dimer acid, isophthalic acid, phthalic anhydride, and terephthalic acid, and glycerin. , a reaction product with a trifunctional polyol such as trimethylolpropane, 11) a reaction product of a tribasic acid such as trimellitic anhydride with ethylene glycol, diethylene glycol, butylene glycol, 1-6 hexanediol, neopentyl glycol, propylene glycol, etc. Examples include reactants with bifunctional polyols, 1ii) ring-opening polymers of ε-caprolactone, and trifunctional polyester polyols.

Examples of the polyether diol include polyethylene glycol, polypropylene glycol, polyphthylene gelicol, polytetramethylene ether glycol, and the like.

Regarding the mixing ratio of the four components and component (3), it is preferable that the equivalent ratio of hydroxyl groups in the four components to incyanate groups in component (iii) is NC010H=1 to 1.5. When the number is less than 1, the number of hydroxyl groups becomes excessive and uncured components remain during adhesion, resulting in a marked deterioration in heat resistance, boiling resistance, and chemical resistance. If it exceeds 1.5, isocyanate groups remain and uncured zero components remain, resulting in poor heat resistance, adhesive properties, etc. or,
If the film is later exposed to moisture, the crosslinking density becomes abnormally high, resulting in a υ hardwood film, resulting in poor flexibility and reduced adhesive strength, which is undesirable.

1 aii of the solvent added to the adhesive composition of the present invention;
i The adhesive composition of the present invention has a high viscosity, so the amount of solvent added is 70 to 80% by weight in the adhesive composition of the present invention. is viscous 1ii d; 5,000~50,0OOCPS/2
Since it is as low as 5C, it is sufficient to add the solvent in an amount of 30% by weight or less, and as a result, it can be used as a two-component urethane adhesive composition for lamination using dry laminator equipment, which has been used conventionally, as is clear from the examples. It exhibits excellent initial adhesion after an appropriate open time of neither too short nor too long when applied to the film surface using It exhibits drug properties.

The solvent added to the adhesive composition of the present invention may be any organic solvent that does not show reactivity with incyanate groups or hydroxyl groups, such as benzene, toluene, xylene, aromatic hydrocarbons, methylene chloride, trichlene, etc. Examples include halogenated hydrocarbons such as chlorobenzene, esters such as ethyl acetate, butyl acetate, and cellosolve acetate, and ketones such as a7tone, methyl ethyl ketone, and cyclohexanone.

The solvent may be added in advance by adding the ^ component or the ◎ component, or at the time of mixing the four components and the component a.

The adhesive composition of the present invention includes resin films such as polyethylene, polypropylene, polyethylene phthalate, polyamide, cellophane, polystyrene, polycyclized vinyl, and polyvinylitine, paper, synthetic papers such as polystyrene and polyethylene, aluminum foil, steel foil, etc. It is effective as an adhesive for 2-laminated films using Kinpohaku as a coating material, and can be used for various purposes.

In particular, the use of polyethylene film, polyethylene terephthalate film, polyamide film, aluminum foil, etc., which have been recently developed and considered, will prevent the laminate layer from being damaged even when subjected to long-term temperature treatment (100~, J40 CO, 5~30 minutes) as a high-retort packaging product. It is an excellent adhesive composition that does not peel off.

1. In order to increase the stability of the adhesive of the present invention, antioxidants, ultraviolet absorbers, antifogging agents, etc. may be added.

Example 1 (3) The trifunctional polypropylene glycol shown in Table 1 was mixed with trifunctional polyether polyol and polyester polyol in a ratio of 100:50 as the component (3).
A mixture of Mitsui Nishi Urethane Co., Ltd., trade name MN-700) and trifunctional holica prolactone (Daicel Chemical Industries, Ltd. product Plaxel 308).

Hydroxyl group (i (hereinafter &01(V): JIS
-Measured by -1557) 1273 per 207.0H
, a polyol component with a viscosity of 320 CPS/2.5 C (using a BM type viscometer and rotor A2) was obtained.

Table 1 ■ As components, polyether diol and diincyanate were mixed in a molar ratio of 1:1.9 with a molecular weight of 10.
00,0HV112 in a reaction tank with a direct current cooler equipped with a bifunctional polyp, and with sufficient stirring, 80 c4
A time reaction is carried out to obtain a urethane prepolymer having an NCO equivalent of 1050, an NCO content of 4.0%, and a viscosity of 70.0OOCPS/25C.

The equivalent ratio of the above (5) component and 0 component is NC010H = 1
A urethane adhesive composition for a laminator of the present invention is obtained by blending 1 part of the carrot component and 4.62 parts of the ◎ component so that the ratio becomes 2. At this time, 43 parts of ethyl acetate was added to 100 parts of the composition to prepare an adhesive with a solid content of 70 cm, a viscosity of 9 ocPs/z5C, and a bot-like 10 hours. Laminator (manufactured by Okazaki Kikai Co., Ltd., gravure roll, 200 lines,
A plate depth of 20 microns) was used, and various films shown in Table 2 were laminated and various physical properties were measured. Similarly, the coating amount of the adhesive composition was 1.5 fi/m'' on the film surface, and the mechanical suitability (using a dry laminator) at that time was as follows.

Generation of bubbles When bubbles are generated on the applicator roll of a laminator, they are transferred onto the film and cause delamination, but in the adhesive composition of the present invention, bubbles are not generated on the applicator roll due to the total heat.

○ Increased viscosity (pan life) If the viscosity increases during operation, it becomes difficult to apply a uniform film thickness. Usually, it is preferable if the film thickness deviates by 20 or more from the set film thickness.
The time required for the % film thickness to change by 2011 is at least 3
It takes at least 5 hours, preferably about 5 hours.

However, the adhesive composition of the present invention lasted for more than 5 hours.

When applying an adhesive using a viscosity laminator, if the viscosity is high, the film thickness will become too large, which is undesirable from economical and appearance standpoints. It is difficult to use, and the viscosity is 200
CP S/25C or less, preferably 100CPS/25
Theal below c.

Table 2 0 film composition Represents the various films listed below.

CPP・・・Polypropylene film with a thickness of 20μ OPP・・・Stretched polypropylene film with a thickness of 20μ LDPE・・・Low density polyethylene film with a thickness of 40μ PET・・・Polyester film with a thickness of 12μ 0-Ny...Stretched nylon film with a thickness of 20μ At...A film with a thickness of 20μ and thicker than aluminum foil is also used in the following Examples and Reference Examples.

O Residual Solvent Immediately after lamination, measure the amount of solvent using a gas chromatograph.

A laminate film of 0.2 M' was placed as a sample in a 500d container and the amount of solvent detected was measured at 80C for 30 minutes.It is not preferable if the amount of residual solvent is 6 to 10% or more.

After 0 adhesion strength - ymine 1, 23C, 65SR) (after being left for 2 days, T-peeling was performed using a tensile tester.

Unit: y/1,5crR ○ Boil test After laminating and leaving at 23C, 651RH for 2 days,
After heat-sealing the laminate film, filling it with salad oil and boiling it for 30 minutes at 100C, the adhesive strength (
1/A, 5 Crn) and appearance.

Example 2 Trifunctional polypropylene glycol (trade name MN-tooo manufactured by Mitsui Nisso Urethane Co., Ltd.) and polyfunctional polyester shown in Table 3 were prepared using trifunctional polyether polyol and polyester polyol as the four components in a ratio of 100:20. Glycol adibate ester (trade name Ninopora Y131 manufactured by Nippon Polyurethane Industries) i mixed, 0HV16
0, an OH equivalent of 350, and a viscosity of 500 CPS/25C.

Table 3 Polyether diol and diisocyanate were used as the β component in a molar ratio of 1:1.95, with a molecular weight of 70.
100 parts of bifunctional polypropylene glycol of 0.0HV160 and 69.6 parts of MDI were reacted at 80C for 4 hours in a nitrogen-substituted reaction tank equipped with a reflux condenser.
Equivalent weight 977, NCO content 4.3%, viscosity 80.0OO
A urethane prepolymer of CP S/25 C is obtained.

The equivalent ratio of the above (5) component and β component is NC010H=1
．． The adhesive composition of the present invention is obtained by blending 1 part of the four components and 4.6 parts of the zero component so that the total amount is 2. At this time, the composition 10
Add 43 parts of ethyl acetate to 0 parts, and the solid content is 70 parts.
The adhesive was adjusted to have a viscosity of 100CP8/25C and a pot life of 10 hours, and various films shown in Table 4 were laminated using a dry laminator, and various physical properties were measured.

The thickness of the film used, coating conditions, and measurement conditions were the same as in Example 1. In addition, regarding mechanical suitability during lamination, no bubbles were generated, the film thickness did not change by 2 degrees even after 5 hours, and the viscosity was 100 CPS/2.
5t:'.

Table 4 Example 3 The polyol component shown in Example 1 is used as the fourth component.

As the f3+ component, the molar ratio of polyether diol and diisocyanate is 1:1.9.
XDI) 36.5 parts were reacted for 14 hours at 80C in a reaction tank with a reflux condenser purged with nitrogen, and the NGO equivalent was 9.
33, NGO content 4.5%, viscosity 90,000CP8
/25C urethane prepolymer is obtained.

The equivalent ratio of the above four components and (E3) component is NC010H=
The adhesive composition of the present invention is obtained by blending 1 part of the four components and 4.6 parts of component (c) so that the adhesive composition of the present invention is 12 parts.

At this time, 43 parts of ethyl acetate was added to 100 parts of the acid, the solid content was 70 cm, and the viscosity was 100 CPS/25 t:'
An adhesive having a pot life of 10 hours was prepared, and various films shown in Table 5 were laminated using a dry laminator, and various physical properties were measured.

The thickness of the film used, coating conditions, and measurement conditions are the same as in Example 1. In addition, regarding the mechanical suitability during lamination, there was no generation of bubbles at all, and the film thickness did not change by 2 degrees even after 5 hours, and the viscosity was 100CPS/25.
1:'.

Table 5 Reference Examples 1 to 5 The four-component polyether polyol and polyester polyol of Example 1 were used with the molecular weight, number of functional groups, blending ratio, and OHV changed as shown in Table 6.

Regarding 6) components and the solvent to be added, see Example 1.
is exactly the same.

Chapter 6 Table 01...Polyether polyol ■...
・Represents polyester polyol.

As shown in Table 7, the measurement results show that Reference Examples 1 and 4 had unfavorable mechanical suitability and were difficult to coat onto the film surface. Reference Examples 2.3 and 5 were unfavorable because they caused lamination in the boil test.

Table 7 Regarding the generation of bubbles 0...Experienced the generation of bubbles on the applicator roll
・・・・・・If bubbles are generated on the applicator roll, the film thickness set for pan life (increase in viscosity) is 20-
Time when the deviation is more than ○...5 hours or more, △...3 to 5 hours, ×
...within 3 hours.

Regarding 0 viscosity (viscosity during application) ○・・・・・・＜ 100CPS/25 C△・・・・・・
・・100～200CP S/25C×・・・・・・＞
200CP S/25 CO Delami...Represents delamination.

Reference Examples 6 to 8 Table 7 shows the results of increasing/decreasing the molecular weight and increasing the number of hydroxyl groups for the polyether diol component (iii) of Example 1.

In addition, regarding the component (5) and the solvent to be added, refer to Example 1.
is the same as

The measurement results show that reference examples 6 and 7 have inappropriate mechanical suitability.
In Reference Example 8, delamination occurred in the boil test.

Reference Examples 9 and 10 Blending ratio (equivalent ratio) of four components and zero component in Example 1
Change to the values shown in Table 8. The polyol component (component (2)), the urethane prepolymer (component 0), and the solvent to be added are exactly the same as in Example 1.

The results were unfavorable, with reference example 9 showing delamination in the boil test, and reference example 1o having inadequate mechanical aptitude.

Table 8

Claims (1)

[Claims] (1) Trifunctional polyether polyol with a molecular weight of 400 to 1000 and polyfunctional polyester polyol with a molecular weight of 400 to 1300 in a ratio of 100:15 to 100:10
Polyol components mixed at a ratio of 0. (c) A urethane prepolymer having an incyanate group at the end, which is obtained by reacting 1.5 to 2.0 mol of diisocyanate per mol of polyether diol having a molecular weight of 400 to 1000. It consists of the above substitute components and 0 component, and the proportion of the hydroxyl group in component (A) and the isocyanate group in component (2) is NC0 in equivalent ratio.
A urethane adhesive composition for laminating, characterized in that it is mixed so that 10H=1 to 1.5.