JPH04323292A - Aqueous urethane-based two liquid type adhesive and emulsion as main agent thereof - Google Patents

Abstract

PURPOSE:To obtain an adhesive having high bond strength without requiring pretreatment of a material to be bonded such as foamed polyolefin material by blending an aqueous emulsion of a specific polyurethane compound with a polyisocyanate as a curing agent. CONSTITUTION:(A) A main agent comprising an aqueous emulsion obtained by reacting (i) a polyurethane-based reaction product containing an active isocyanate group at the end of molecule prepared by reacting a saturated polyester polyol solid at normal temperature with a water-solubility providing substance containing one or more hydrophilic groups and plural functional groups to be reacted with an isocyanate group, a liquid polychloroprene containing plural active hydrogen groups to be reacted with an isocyanate group and a polyisocyanate compound with (ii) a polyol is blended with (B) a polyisocyanate compound as a curing agent to give the objective composition.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a two-component adhesive of the type in which two components (base agent and curing agent) are mixed immediately before use. , relates to a water-based urethane two-component adhesive that exhibits high initial adhesive strength and normal adhesive strength when bonding to plastic members and wooden members.

0002

[Prior art and problems to be solved by the invention] Conventionally,
For example, when bonding a skin material such as a polyolefin foam member to a base material such as a plastic or wood member using a water-based adhesive, an acrylic two-component adhesive is generally used, and a surfactant (emulsifier) is used. A two-component adhesive consisting of a blended acrylic emulsion and a hardening agent is applied to the base material side,
After drying, a method such as pasting and pressing a preheated skin material is used.

However, in the above method, the surfactant (emulsifier) contained in the acrylic emulsion has a plasticizing effect, and as a result, the cohesive force of the adhesive layer during initial adhesion and when heated after normal conditions is small. , there was a problem that cohesive failure was likely to occur.

For this reason, recently, instead of the above-mentioned acrylic emulsion, a polyester urethane having a hydroxyl group at the end of the molecule, which is obtained by reacting a polyester polyol which is solid at room temperature and has a large cohesive force with a polyisocyanate compound, is used as a surfactant. A two-component adhesive based on a polyurethane emulsion containing in its molecular structure has been developed and put into practical use. In the case of this adhesive, since it has a large cohesive force not only in normal conditions but also in the initial stage of adhesion, cohesive failure of the adhesive layer is unlikely to occur. However, since this type of adhesive has low adhesion to non-polar polyolefin, interfacial peeling is likely to occur between it and the substrate surface must be pretreated with a primer to achieve strong adhesion. There was a problem that the work became complicated.

The present invention has been made in view of the above circumstances, and its purpose is to eliminate the need for any pretreatment of polyolefin foam members, and to improve initial adhesive strength and normal adhesive strength. The purpose of the present invention is to provide an aqueous urethane two-component adhesive having both high properties and a curable emulsion as its main ingredient.

[0006]

[Means for Solving the Problems] The water-based urethane two-component adhesive according to the present invention for achieving the above object comprises a saturated polyester polyol (A) that is solid at room temperature, at least one hydrophilic group and an isocyanate group. A water solubility-imparting substance (B) having at least two functional groups capable of reacting with a polyisocyanate compound (B) and a liquid polychloroprene (C) having at least two active hydrogen groups capable of reacting with an isocyanate group are added to a polyisocyanate compound ( A polyurethane compound having a hydroxyl group at the molecular end obtained by reacting a polyurethane-based reaction product having an active isocyanate group at the end of the molecule obtained by reacting with polyol (E) with D), and dispersing it in water. It consists of an emulsion as a main ingredient and a polyisocyanate compound as a curing agent.

The saturated polyester polyol (A) in the present invention can be used without any particular restriction as long as it has a relatively high glass transition point Tg and a large cohesive force, that is, it is solid at room temperature. For example, polyethylene Aromatic polyesters such as terephthalic acid polyesters such as terephthalate and polytetramethylene terephthalate, isophthalic acid polyesters such as polyethylene isophthalate and polytetramethylene isophthalate; polyethylene oxalate, polytrimethylene oxalate,
Polytetramethylene oxalate, polyhexamethylene oxalate, polyoctamethylene oxalate, polydecamethylene oxalate, polyicosamethylene oxalate, polyicosamethylene malonate, polyethylene succinate, polytetramethylene succinate, polyhexane Methylene succinate, polydecamethylene succinate, polyicosamethylene succinate, polydecamethylene glutarate, polyicosamethylene glutarate, polytetramethylene adipate, polyhexamethylene adipate, polydecamethylene adipate, polyicosamethylene adipate , polyhexamethylene pimelate,
Polydecamethylene pimelate, polyicosamethylene pimelate, polyethylene suberate, polyhexamethylene suberate, polydecamethylene suberate, polyicosamethylene suberate, polyhexamethylene azelate,
Examples include straight chain aliphatic polyesters such as polydecamethylene azelate, polyethylene sebacate, polytetramethylene sebacate, polypentamethylene sebacate, polyhexamethylene sebacate, polydecamethylene sebacate, and polyicosamethylene sebacate. .

The water solubility imparting substance (B) in the present invention is:
-COOH, -COONa, -, which has at least two functional groups capable of reacting with isocyanate groups at the terminal or side chain, and which is used to water-solubilize the polyurethane compound produced.
COONH4, -SO3H, -SO3Na, -SO
It has at least one hydrophilic group such as 3 NH4 in its molecule. Specific examples of such water-solubility imparting substances include 2,2-dimethylolpropionic acid (DMPA), as well as sulfonic acids shown in the following chemical formulas 1 and 2, chemical compounds 3 and 4.
, anionic water-solubility-imparting substances such as carboxylic acid-based substances shown in Chemical Formula 5, and cationic water-solubility-imparting substances shown in Chemical Formulas 6 and 7 below.

[0009]

[Chemical formula 1]

0010

[Case 2]

[0011]

[Chemical formula 3]

0012

[C4]

[0013]

[C5]

[0014]

[C6]

[0015]

[C7]

Liquid polychloroprene (C
) has at least two active hydrogen groups (-OH, -NH2, =NH, -COOH) that can react with isocyanate groups.
, -SH, etc.), which is liquid at room temperature, and is introduced into the molecules of polyurethane compounds to improve adhesion to polyolefin foam members and the like.

The polyisocyanate compound (D) in the present invention has isocyanate groups at both ends by reacting the above three components, ie, the saturated polyester polyol (A), the water-solubility imparting substance (B), and the liquid polychloroprene (C). A crosslinking agent for obtaining polyurethane-based reaction products. Such polyisocyanate compounds include hexamethylene diisocyanate monomer (HDI), diphenylmethane-4,4'-diisocyanate monomer (
MDI), tolylene diisocyanate monomer (TDI)
), isophorone diisocyanate monomer (IPDI)
, m-xylylene diisocyanate monomer (XDI)
In addition to aliphatic or aromatic diisocyanate compounds such as and these hydrogenated diisocyanate compounds, HDI derivatives such as HDI trimethylolpropane (TMP) adduct trimer and isocyanurate trimer, MDI derivatives such as crude MDI, TDI TDI derivatives such as TMP adduct trimer and isocyanurate trimer, TMP of IPDA
IPDA such as adduct trimer and isocyanurate trimer
Examples of the derivative include XDI derivatives such as TMP adduct trimer and isocyanurate trimer of XDI. Moreover, as a commercially available product, tris (p-isocyanate phenyl) thiophosphate (manufactured by Bayer AG, trade name "Desmodur RF") can be mentioned.

[0018] The polyol (E) in the present invention converts the isocyanate group at the end of the polyurethane reaction product into a hydroxyl group so that it can be crosslinked and cured by a curing agent (polyisocyanate compound) via a urethane bond. belongs to. Suitable specific examples of such polyols include low molecular weight compounds such as monoethylene glycol, monopropylene glycol, monoethanolamine, and butanediol.

The polyisocyanate compound used as a curing agent in the present invention must be capable of crosslinking and curing in water, and the polyisocyanate compound (D
) and their derivatives, including water-soluble ones. A commercially available product is Bayer's "Desmodule DA" (trade name).

[0020] In addition to the above components, an emulsion stabilizer may be added to the main ingredient, and a tackifier may be added to the main ingredient or curing agent, if necessary.

[0021] The above polyurethane compound contains in its molecule a polyester component that is solid at room temperature and has a large cohesive force;
It has a liquid polychloroprene component that has strong adhesive strength to PEF and the like. Therefore, the adhesive according to the present invention having this as a main ingredient is particularly suitable for use when at least one of the adherends is a polyolefin foam member.

The emulsion as the main ingredient of the two-component adhesive according to the present invention is produced, for example, by a method comprising the following steps (1) to (2). [Step (2)] Saturated polyester polyol (A) and liquid polychloroprene (C), which are solid at room temperature, are dissolved in an organic solvent such as acetone, methyl ethyl ketone (MEK), or xylene in a reactor equipped with a heating means and a reflux device. [Step ■] Add the water-solubility imparting substance (B) to the organic solution obtained in Step ■, and raise the urethane formation temperature (approximately 80°C).
Keep the temperature up to. [Step (2)] The polyisocyanate compound (D) is added to the liquid obtained in Step (2) and reacted with stirring for 8 to 12 hours to obtain a polyurethane-based reaction product having an active isocyanate group at the end of the molecule. Note that if an organic solvent such as acetone whose reflux temperature is lower than the urethane formation temperature is used as the organic solvent in step ①, the reaction system cannot be heated to the urethane formation temperature, so it is necessary to add a catalyst such as amines or organotin compounds. There is. [Step ■] Polyol (E) is added to the melt of the polyurethane reaction product obtained in Step ■, and the mixture is reacted with stirring for 8 to 12 hours to convert the terminal isocyanate groups of the polyurethane reaction product into terminal hydroxyl groups. . At this time, the amount of polyol (E) added is adjusted in advance so that the isocyanate groups in the unreacted polyisocyanate compound (D) are also converted. [Step (2)] The polyurethane compound obtained in step (2) having hydroxyl groups at both ends is added to the alkaline aqueous solution and emulsified using a homomixer. [Step (2)] The inside of the reactor is heated and depressurized to distill off the organic solvent from the emulsion obtained in Step (2).

When using, for example, a diol as the polyol (E) in the present invention, it is preferable to use the polyisocyanate compound (D) in an amount of 1.1 to 1.3 times the theoretical amount relative to the diol. For example, when using diisocyanate as the polyisocyanate compound (D), 2.2 to 2.2 to
Preferably, 2.6 mol is used. This is due to the fact that the isocyanate group is consumed in reaction with water and that the isocyanate group is not 100% active. However, when using ethylene glycol as the diol, it is preferable to use at least twice the theoretical amount of diisocyanate to prevent gelation due to high molecular weight, and when using monoethanolamine,
In order to prevent shortening of pot life due to residual amino groups, it is preferable to actually measure -NCO% in advance and use only the theoretical amount so that no amino groups remain.

[0024] The above method for producing the main ingredient of the present invention is merely an example, and it is of course not intended to exclude products produced by methods other than the above-mentioned production method.

[0025] When the base material obtained as described above is stirred and mixed with a curing agent to form an adhesive, and this is applied to an adherend and cured at room temperature or by heating, strong adhesion can be achieved. be done.

[0026]

[Examples] The present invention will be explained in more detail based on Examples below, but the present invention is not limited to the following Examples in any way, and may be practiced with appropriate modifications within the scope of the gist thereof. is possible. (1) Examples 1 to 3 and Comparative Examples 1 to 4

[0027] Polyester polyol and liquid polychloroprene are heated in a reactor equipped with a heating means and a reflux vessel.
After dissolving in MEK, 2,2'-dimethylolpropionic acid was further added and the temperature was raised to 80°C and maintained. Next, a diisocyanate compound was added and reacted for 10 hours, and then ethylene glycol was further added and reacted for 10 hours. This reaction solution was poured into an aqueous solution of triethylamine, stirred and mixed for 30 minutes using a homomixer (13000 rpm) to emulsify, and after emulsification, MEK was removed under reduced pressure. Table 1 shows the amount of each raw material used (unit: grams). In addition, polyester A in Table 1 is a hard polyester that is solid at room temperature (manufactured by Hüls, product name "Dynacall 71").
Polyester B is a soft polyester that is liquid at room temperature (manufactured by Adeka Argus, trade name: Adeka New Ace F7-67), and liquid chloroprene is "Denka Chloroprene FH005", manufactured by Denki Kagaku Kogyo Co., Ltd.
(product code, has two hydroxyl groups in the molecule).

[0028]

[Table 1]

(2) Adhesive strength evaluation test A polyisocyanate compound (
Seven types of two-component adhesives were prepared by adding 10 parts by weight of the product (manufactured by Bayer AG, trade name: "Desmodule DA") and stirring and mixing, and the initial adhesive strength and normal adhesive strength were measured using the following test method. . That is, each adhesive was spray applied to a rigid base material (wood fiber board manufactured by Mitsui Mokuzai Co., Ltd., dimensions 100 x 100 mm) at a coating amount of 100 g/m2, and then heated at 80°C for 50 minutes.
Dry for a minute. 140°C on the coating side of this rigid base material.
The skin material (PEF manufactured by Toray Industries, Inc., product name "PPX", dimensions 100 x 100 mm) that had been heated for 4 minutes at and comparative samples 1 to 4 were obtained. Next, each sample was cut to a width of 25 mm to obtain four test pieces, each of which was peeled by 10 mm in the width direction, then attached to a tensile tester and peeled 180° at a speed of 200 mm/min to determine the peel strength ( Kg/25mm) was determined, and the average of the four test pieces was calculated to determine the adhesive strength. Table 2 shows the results.
Shown below.

In Table 2, the initial adhesive strength is 1 at room temperature after pressure bonding.
The results are measured after being left for 0 minutes, and the normal adhesive strength is
The results are shown after being left at room temperature for one day after crimping. In addition, in the same table, MB indicates that the skin material has been destroyed (Ma
CF indicates that the adhesive layer has broken (Cohesive Failure),
Further, AF indicates failure at the interface between the skin material and the adhesive layer (Adhesive Failure).

[0031]

[Table 2]

From Table 2, it can be seen that in the case of the adhesives according to the present invention (samples 1 to 3), both the initial adhesive strength and the normal adhesive strength are large because the skin agent is destroyed. In contrast, the adhesive using saturated polyester polyol, which is liquid at room temperature (comparative sample 1), had a high normal adhesive strength, but cohesive failure occurred in the initial adhesion test, and adhesives that did not use liquid polychloroprene The adhesives (Comparative Samples 2 and 3) caused interfacial peeling in both the initial adhesion test and the normal adhesion test, and the adhesive that did not use saturated polyester polyol (Comparative Sample 4) showed cohesion in the initial adhesion test. It can be seen that there is a problem in at least the initial adhesive strength in both cases.

[0033]

Effects of the Invention As explained above in detail, the water-based urethane two-component adhesive according to the present invention does not require any pre-treatment on adherends such as polyolefin foam members,
Moreover, the present invention exhibits excellent and unique effects, such as having a large adhesive force in both initial adhesion and normal adhesion.

Claims (3)

[Claims] Claim 1: A saturated polyester polyol (A) that is solid at room temperature, a water solubility-imparting substance (B) having at least one hydrophilic group and at least two functional groups capable of reacting with an isocyanate group, and an isocyanate group. A polyurethane-based reaction product having an active isocyanate group at the molecular end obtained by reacting liquid polychloroprene (C) having at least two active hydrogen groups capable of reacting with a polyisocyanate compound (D), A water-based urethane two-component adhesive consisting of an emulsion as a main ingredient obtained by dispersing in water a polyurethane compound having a hydroxyl group at the molecular end obtained by reacting with E), and a polyisocyanate compound as a curing agent. . 2. A saturated polyester polyol (A) that is solid at room temperature, a water solubility-imparting substance (B) having at least one hydrophilic group and at least two functional groups capable of reacting with an isocyanate group, and an isocyanate group. A polyurethane-based reaction product having an active isocyanate group at the molecular end obtained by reacting liquid polychloroprene (C) having at least two active hydrogen groups capable of reacting with a polyisocyanate compound (D), E) consists of an emulsion as a main ingredient obtained by dispersing in water a polyurethane compound having a hydroxyl group at the molecular end obtained by reacting with E), and a polyisocyanate compound as a curing agent, and at least one of the adherends is The aqueous urethane two-component adhesive according to claim 1, which is a polyolefin foam member. 3. A saturated polyester polyol (A) that is solid at room temperature, a water solubility imparting substance (B) having at least one hydrophilic group and at least two functional groups capable of reacting with isocyanate groups, and at least two A polyurethane-based reaction product having an active isocyanate group at the molecular end obtained by reacting a liquid polychloroprene (C) having active hydrogen groups with a polyisocyanate compound (D), and a polyol (E) are reacted. An emulsion for an aqueous urethane two-component adhesive obtained by dispersing the resulting polyurethane compound having a hydroxyl group at the end of the molecule in water.