JPS63218783A - Production of adhesive composition - Google Patents

Abstract

PURPOSE:To obtain a high-viscosity liquid or solid adhesive composition, having excellent mixing and deodorizing operability and capable of preventing deterioration, by adding and reacting a mixture of polyols with a tackifier with a polyisocyanate compound. CONSTITUTION:A liquid or solid adhesive composition, obtained by adding and reacting (A) a polyisocyanate compound normally while heating with (A) a mixture of (i) polyols with (ii) a tackifier consisting of a polymer, such as polystyrene based polymer, preferably without substantially containing functional groups reactive with isocyanate groups in an amount of 20-120wt.% based on the component (i), containing polyurethane prepolymer and having preferably >=100,000cP viscosity at 25 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing an adhesive composition containing an isocyanate group-containing polyurethane prepolymer.

[Prior art] Isocyanate group-containing polyurethane prepolymer is 1
Used as a reaction-curing adhesive. In particular, since it can be cured by reacting with moisture in the air or crosslinking components in other atmospheres, it is used as a so-called -original reaction-curing adhesive. Since this polyurethane prepolymer is normally liquid at room temperature, it can be applied without using a solvent. However, since the reaction of isocyanate groups takes time, adhesive strength cannot be exerted immediately after application of the adhesive (initial adhesive strength is low).

On the other hand, so-called reactive hot melt adhesives are known that use polyurethane prepolymers that are solid at room temperature. This adhesive is applied by heating and melting, and the initial adhesive strength is exerted by the cohesive force based on subsequent cooling and solidification.

In order to further increase the initial adhesive strength, it is known to add a tackifier to a reactive hot melt adhesive (see Japanese Patent Application Laid-open No. 81-115977). Examples of the tackifier include those described in this publication. These are low-melting point adhesive polymers such as coumaron resin, coumaron-indene resin, terpene-phenol resin, rosin derivative, and styrene resin.

[Problems to be Solved by the Invention] In order to blend a tackifier into an isocyanate group-containing polyurethane prepolymer, it is necessary to add a tackifier to an isocyanate group-containing polyurethane prepolymer at a relatively high temperature (usually 10
(0 to 150°C) and requires work to uniformly mix the two, which have high viscosity. This mixing operation is not only complicated, but also has the problem of easily causing deterioration of the isocyanate groups during the mixing operation.

On the other hand, many tackifiers have an odor, and deodorization is desired depending on the use. The cause of the odor is thought to be low-molecular impurities such as unreacted monomers, and reduced pressure treatment is effective for deodorization. The odor of the tackifier tends to be a problem when applying a molten adhesive, so it is necessary to melt it before applying reduced pressure. However, it is extremely complicated to deodorize the tackifier by melting it alone under reduced pressure, and it is also problematic to perform vacuum treatment after blending it with the polyurethane prepolymer for the reasons mentioned above.

In order to deodorize at a relatively low temperature, it is also possible to dissolve the tackifier in a solvent and blow nitrogen, air, etc. under normal pressure, or to perform a reduced pressure treatment. However, in order to produce a solvent-free adhesive composition, subsequent removal of the solvent is required.

[Means for Solving the Problems] The present inventor first mixed a tackifier with polyols, which are raw materials for polyurethane prepolymers, and after deodorizing or other treatment as necessary, mixed the tackifier with the other raw material. We have discovered a method for producing an adhesive composition containing an isocyanate group-containing prepolymer by adding and reacting a certain polyisocyanate compound. Since the tackifier dissolves in polyols at room temperature or under relatively low heating, there is no need to mix the tackifier after reacting the polyisocyanate compound. Moreover, since the polyol in which the tackifier is dissolved is liquid, the deodorization is extremely easy. If the solubility of the tackifier in polyols is insufficient,
It can be heated to form a homogeneous mixture and deodorize it. This mixture must be homogeneous at least at the temperature at which it is reacted with the polyisocyanate compound.

The present invention is the following invention whose gist is a method for manufacturing the above adhesive composition.

An adhesive characterized in that a polyisocyanate compound is added to a mixture of polyols and a tackifier and reacted to produce an adhesive composition that is a high viscosity liquid or solid at room temperature and contains a polyurethane prepolymer having an isocyanate group. Method for producing a drug composition.

The tackifier in the present invention consists of a relatively low melting point adhesive polymer. As the tackifier, the above-mentioned known tackifiers are suitable, but the invention is not limited thereto.

Among these, styrene polymers with relatively low molecular weight have high solubility in polyols and are also excellent in other physical properties such as adhesiveness. Styrene, v? The polymeric tackifier is a relatively low molecular weight polymer consisting of a single or copolymer of styrene or α-methylstyrene, or a copolymer of these and other copolymerizable monomers. Its molecular weight is preferably about 200-500G, especially about 300-4000, its melting point is about 50-15
0°C is suitable, especially about 60-120°C.

The tackifier is preferably one that is substantially inert to the polyisocyanate compound.The tackifier containing a functional group such as a hydroxyl group or an amino group that is highly reactive to isocyanate groups is preferably one that is substantially inert to the polyisocyanate compound. There is a risk that the reaction may result in the formation of high melting point reactants, a decrease in tackiness, and the formation of insoluble substances. On the other hand, there is also a possibility that the amount of polyisocyanate compound that reacts with polyols decreases, and the reactivity of the adhesive composition decreases. Therefore, the polymer used as the tackifier is suitably a polymer that does not substantially contain functional groups that are highly reactive with isocyanate groups. In this sense as well, the tackifier is preferably the polystyrene polymer described above.

The polyols in the present invention are polyols that serve as raw materials for isocyanate group-containing polyurethane prepolymers, and may be a mixture of two or more types. Examples of polyols include various polyether polyols, polyester polyols, etc. Examples include polyols, polydiene polyols, polycarbonate polyols, and (meth)acrylic acid ester polymer polyols. Preferably, polyether polyols or polyester polyols are used.

Examples of polyether polyols include polyoxypropylene polyols, poly(oxypropylene/oxyethylene) polyols, polyoxytetramethylene polyols, and poly(oxytetramethylene/oxyethylene) polyols. Examples of polyester polyols include polyester polyols and polycaprolactone polyols having polyhydric alcohol residues and polyhydric carboxylic acid residues. In addition, polyether ester polyols such as polyether ester polyols having polyether polyol residues and polycaprolactone residues, polydiene polyols such as polybutadiene polyols, and polycarbonates such as poly(1,8-hexylene carbonate) diol. (meth)acrylic acid ester polymer type polyols such as hydroxyalkyl methacrylate copolymers can also be used. The average molecular weight per hydroxyl group of these polyols is suitably about 300-4000, and about 400-4000.
The average number of hydroxyl groups per molecule is preferably about 1.6 to 8, and about 1.8 to 3.
．． 2 is preferred, and most preferably, a diol alone or a combination of a diol and a polyol is employed.

Low molecular weight polyols called chain extenders or crosslinkers can be used in combination with the above polyols. Examples of low molecular weight polyols include polyhydric alcohols and low molecular weight (preferably about 300 or less) polyether polyols. Furthermore, reactive compounds other than polyols such as polyamines can also be used in combination with the polyols.

The appropriate amount of tackifier to polyols is 20 to 120% by weight. In particular, if the amount of the tackifier, which is preferably about 50 to 100% by weight, is too small, the initial adhesive strength of the adhesive composition will be insufficient, while if it is too large, the adhesive strength of the adhesive composition after curing will deteriorate. physical properties deteriorate. Various additives may be added to the mixture of polyols and tackifier before adding and reacting the polyisocyanate compound. Examples of compounding agents include antioxidants,
Light stabilizers, UV absorbers, color inhibitors, other stabilizers and colorants.

Includes flame retardants, fillers, etc. When performing a deodorizing operation before adding and reacting a polyisocyanate compound, compounds that may be removed during deodorizing, such as low-temperature compounds (for example, low molecular weight polyols such as the polyhydric alcohols mentioned above), should be added after the deodorizing operation. Alternatively, ingredients other than polyols may be added after the polyisocyanate compound is added and reacted.

When deodorizing a mixture of polyols and tackifier, the deodorizing operation is preferably carried out by blowing an inert gas such as nitrogen or air under normal pressure or reduced pressure. In some cases, deodorization may be performed by stirring under reduced pressure.Furthermore, in order to increase the efficiency of the deodorization operation, it is preferable to heat the mixture.Furthermore, it is also possible to perform deodorization by treating the mixture with an adsorbent. be. On the other hand, when reacting polyols with polyisocyanate compounds, it is often necessary to dehydrate the polyols in advance. In the present invention, deodorization can be performed simultaneously with this dehydration, and deodorization can be performed without adding any new steps to conventional methods.

As the polyisocyanate compound, various compounds having two or more isocyanate groups can be used. for example,
Aromatic polyisocyanates such as diphenylmethane diisocyanate, tolylene diisocyanate, naphthalene diisocyanate, polymethylene polyphenyl isocyanate, xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, inphorone diisocyanate, methylene bis(cyclohexyl isocyanate) Alicyclic polyisocyanates such as and modified products thereof can be used. Examples of modified products include prepolymer-type modified products modified with polyhydric alcohols such as trimethylolpropane, carbodiimide-modified products, and nurate-modified products. In particular, when non-yellowing is required, xylylene diisocyanate, aliphatic polyisocyanate, alicyclic polyisocyanate, and modified products thereof are suitable. The amount of polyisocyanate compound to be used is such that the number of isocyanate groups to the hydroxyl groups of the polyols is 1 on average.
．． An appropriate amount is 1 or more, especially 1.2 to 2.4,
Unreacted polyisocyanate compounds may be included. However, unreacted polyisocyanate can also be removed if necessary.

The zero reaction, which is carried out by adding a polyisocyanate compound to a mixture of polyols and a tackifier and reacting the mixture, is usually carried out under heating. Further, if necessary, the reaction may be carried out in the presence of an organometallic compound catalyst such as an organotin compound, a tertiary amine catalyst, or other catalyst.

The adhesive composition produced according to the present invention is a highly viscous liquid or solid composition at room temperature. In order to improve initial adhesion, it is preferable to use a solid at room temperature, and to improve coating workability, it is preferable to use a highly viscous liquid or gummy solid at room temperature.

In the present invention, the adhesive composition is preferably a liquid or solid having a viscosity of 100,000 centipoise or more at 25°C, although it is not particularly limited. The viscosity of is preferably lower,
The viscosity at 100° C. is preferably 10,000 centivoise or less, particularly 5,000 centivoise or less. However, the coating temperature is not limited to 100° C., and any temperature below the thermal deterioration temperature of the adhesive composition can be adopted. Preferred operating temperatures are below about 150°C and at which the viscosity of the adhesive composition is below 50,000 centipoise. As described above, the adhesive composition obtained according to the present invention can be used by adding various additives that are non-reactive with the isocyanate groups.

EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these Examples.

[Examples] Example 1 Polyoxytetramethylene glycol (hereinafter referred to as PTMG) having a molecular weight of 100 and a polystyrene tackifier having a molecular weight of about 400 (melting point 75°0) were mixed to obtain a homogeneous mixture. Add 200 parts of 4,4'-diphenylmethane diisocyanate (hereinafter referred to as MDI) to this mixture (
NGOlo) f number ratio 1.8), and at 100°C 2.
The reaction was allowed to proceed for 5 hours. As a result, a gum-like product at room temperature consisting of a polyurethane prepolymer and a tackifier [isocyanate group content 2.95% by weight, viscosity at 100°C 1500c]
p (centiboise)]vc adhesive composition was obtained. When this adhesive composition was heated to 100°C and applied to an object to be adhered such as a polypropylene film using an applicator heated to 100°C, a styrene odor, which was thought to be caused by the adhesive, was observed. Immediately after applying the adhesive composition, a nylon fabric was layered and adhered to the applied polypropylene film, and the film was cooled to room temperature. Adhesion at this point (initial adhesion) was good. Subsequently, the adhesive was cured in a constant temperature chamber, and as a result, the polypropylene film and nylon fabric were firmly bonded.

On the other hand, the above mixture of PTMG and tackifier was placed in a stirring tank and dry nitrogen was blown into the tank at 1100 taraH.

Deodorization treatment was performed at 120°C for 6 hours. The treated mixture was reacted with MDI in the same manner as above to produce an adhesive composition equivalent to the above. When the same adhesiveness test as above was conducted using this adhesive composition, it was found that it had the same adhesiveness as above. Furthermore, the styrene odor during the coating process was extremely slight compared to the above.

Example 2 Polyether diol 480 with a fraction of 2000 obtained by adding a mixture of ethylene oxide and propylene oxide (weight ratio 80/20) to PTMG with a molecular weight of 1000
and 400 parts of the same polystyrene tackifier used in Example 1 were mixed to obtain a homogeneous mixture. After deodorizing in the same manner as in Example 1, [01120 parts CNC010H = 2.0] was added to this mixture, and the mixture was reacted at 100°C for 3 hours. The obtained adhesive composition consisted of a polyurethane prepolymer and a tackifier, had an isocyanate group content of 1.981°C%, was gummy at room temperature, and had a viscosity of 2000 Cp at 100°C. Furthermore, there was very little styrene odor during the coating process.

Example 3 490 parts of PTMG having a molecular weight of 1000 and 350 parts of the same polystyrene tackifier used in Example 1 were mixed to obtain a homogeneous mixture. To this mixture was added xylene diisocyanate 1eO part CMGO10H = 1.7), and heated at 100°C-r! After reacting for 4 hours, an adhesive composition containing a polyurethane prepolymer was obtained. This composition has an isocyanate group content of 2.84 wt%.

It was gummy at room temperature and had a viscosity of 1200 cp at 100°C.

Example 4 Polycaprolactone diol 494 with a molecular weight of 1200
300 parts of the same polystyrene tackifier used in Example 1 were mixed to obtain a homogeneous mixture. 208 parts of MDI (NCO10H=2.0) was added to this mixture and reacted at 100° C. for 4 hours to obtain an adhesive composition containing a polyurethane prepolymer with an isocyanate group content of 3.34 wt%. This composition is gummy at room temperature;
The viscosity at 100°C was 2700 cp. Example 5 Polyoxypropylene diol 504 with a molecular weight of 1000
250 parts of the same polystyrene tackifier used in Example 1 were mixed to obtain a homogeneous mixture. Add 1246 parts of N (NGO10H=1.95) to this mixture, 1
React at 0G”O for 4 hours to reduce the isocyanate group content to 3.
．． An adhesive composition containing 58 wt% polyurethane prepolymer was obtained. This composition is gum-like at room temperature, and 1
The viscosity of 00''O was 84Qcp.

Example 6 483 parts of iHooo throat NO and 300 parts of an alkylphenol tackifier were mixed to obtain a homogeneous mixture.

217 parts of the mixture NiM[lI (NeoloH=1.
8) and reacted at 100° C. for 4 hours to obtain an adhesive composition containing a polyurethane prepolymer having an isocyanate group content of 2.13 wt %. This composition was gummy at room temperature and had a viscosity of 4200 Cp at 100°C.

[Effects of the Invention] Since the present invention does not require mixing a high-viscosity polyurethane prepolymer and a tackifier at high temperatures, the mixing workability is good and deterioration of the polyurethane prepolymer can be prevented. In addition, when odor is generated due to the tackifier, deodorizing operations can be easily performed before producing the polyurethane prepolymer, and the deodorizing workability is better than when performing the deodorizing operation after producing the polyurethane prepolymer. This also prevents deterioration.

Claims (3)

[Claims] (1) A polyisocyanate compound is added to a mixture of polyols and a tackifier and reacted to produce an adhesive composition that is a high viscosity liquid or solid at room temperature and contains a polyurethane prepolymer having an isocyanate group. A method for producing an adhesive composition. (2) Claim 1 in which the tackifier is a polymer substantially free of functional groups that can react with isocyanate groups.
Section method. (3) The amount of tackifier to polyols is 20 to 1
20% by weight.