JPS59176378A - Elastic sealant - Google Patents

Abstract

PURPOSE:To provide an elastic sealant having excellent weathering resistance and suitable for filling joint spaces of building, prepared by combination of a main component consisting of polyoxyalkylene isocyanate or acrylic isocyanate and a specified hardener. CONSTITUTION:The sealant is prepared by combination of a main component consisting of (A) polyoxyalkylene isocyanate having an isocyanate group at the molecular terminal obtained by reacting an organic diisocyanate with a polyoxyalkylene polyol or (B) acrylic low-molecular weight isocyanate copolymer having isocyanate groups at the terminal of and within the molecule, and a hardener comprising a mixture of a polyoxyalkylene polyol and an acrylic low- molecular copolymer containing functional groups capable of reacting with the isocyanate group at the terminal of or within the molecule and having an average molecular weight of 2,000 or higher.

Description

[Detailed description of the invention] This invention relates to an elastic sealant with excellent weather resistance.

Sealants filled into the joints of buildings must have elastic properties that allow them to expand and contract in response to thermal changes in the building materials that make up the joints. It is desirable that the material does not contain any scattered substances.

Such a sealant is mainly composed of a prepolymer having an incyanate group at the molecular end obtained by reacting a polyoxyalkylene polyol with an organic diisocyanate, a polyoxyalkylene polyol or polyamines as a curing agent, and other fillers as necessary. , urethane sealants containing softeners, stabilizers, etc. are used.

However, such conventional urethane sealants have problems in weather resistance, and have the disadvantage that cracks occur on the sealant surface when exposed outdoors for a long period of time.

On the other hand, polyacrylic sealants have the advantage of being excellent in weather resistance, colorability, and durability, but on the other hand, they are inelastic and have high viscosity, so they cannot be used as emulsion or organic solvent sealants. do not have. For this reason, when this type of sealant is filled into the joint, cracks and gaps are likely to occur because it cannot follow the internal fluctuations in the joint due to thermal effects, etc., and it also causes visual loss after filling. It often does not perform its function as a sealant. Therefore, its use is limited, and the example is AL.
Currently, it is only used for C boards.

The inventors have conducted various studies with the aim of obtaining an elastic sealant that does not have the above-mentioned drawbacks, has sufficient elastic properties especially for filling joints in buildings, and has excellent weather resistance. This invention has been made.

That is, this invention provides a polyoxyalkylene isocyanate component having an incyanate group at the end of the molecule obtained by reacting a polyoxyalkylene polyol with an organic diisocyanate, or an inocyanate group having an average of about one inocyanate group at the end of the molecule and arbitrary incyanate groups in the molecule. A polyoxyalkylene polyol (hereinafter referred to as a polyol) having an average molecular weight i of 1,000 or more, which has an acrylic low molecular weight copolymer incyanate component (hereinafter referred to as an acrylic incyanate component) as a main ingredient and has an average molecular weight of 1 at the position of and an acrylic low molecular weight copolymer having an average molecular weight of 2,000 g and having an average of about 1 functional group at the end of the molecule and an average of 1 functional group capable of reacting with incyanate groups at any position within the molecule. This relates to an elastic sealant that is used as a hardening agent.

The elastic sealant of this invention is a two-component urethane type,
Also, because it has the properties of an acrylic elastic material, it has significantly improved weather resistance, as well as excellent durability and heat resistance.
Moreover, an acrylic low molecular weight copolymer having an average of about 1 functional group involved in the curing reaction in a molecular wood-like manner and an average of 1 functional group at any arbitrary position within the molecule is used as a curing agent or as a curing agent and a main agent. In other words, this copolymer has a structure and performance similar to a telechelic type low molecular weight material that has functional groups at both ends of the molecule, so the sealant can have a high molecular weight in linear and network forms when cured. This satisfies the characteristics required for architectural sealants, such as low hardness, low modulus, and high elongation.

In addition, by using a low-viscosity polyoxyalkylene polyol in combination with an acrylic low-molecular-weight adhesive polymer as a curing agent for this elastic sealant, the viscosity of the sealant can be adjusted without using a solvent. It can improve workability during construction without degrading properties, and does not cause eye loss after construction.

As the main ingredient in the elastic sealant of the present invention, a polyoxyalkylene incyanate component or an acrylic incyanate component may be used alone, or both may be used as a mixture in any proportion. On the other hand, a mixture of a polyol and a low molecular weight acrylic copolymer is used as the curing agent.

According to this, the ratio of the polyoxyalkylene component and acrylic component in the sealant can be varied over a wide range depending on the purpose, and the ratio of the polyoxyalkylene isocyanate component or acrylic incyanate component of the base agent to the curing agent can be changed over a wide range. Sealants can have various properties by combining polyols and low molecular weight acrylic copolymers.

The polyoxyalkylene incyanate component used as the main ingredient is obtained by reacting an organic diisocyanate with a polyoxyalkylene polyol obtained by polymerizing a polyhydric alcohol and an alkylene oxide. The average molecular weight of this polyoxyalkylene polyol is preferably about 300 to 6,000.

Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, glycerin, pentaerythritol, and trimethylolpropane, but diols such as ethylene glycol and propylene glycol, and triols such as glycerin are preferably used.

Further, examples of the alkylene oxide include pro, pyrene oxide, ethylene oxide, butylene oxide, etc., and these may be used alone or in a mixture of two or more.

There are no particular restrictions on the organic diisocyanate used to introduce an isocyanate group into the terminal of this polyoxyalkylene polyol, and specific examples include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, and 4-tolylene diisocyanate.・4'-diphenylmethane diisocyanate-1
・Xylylene diisocyanate, hexamethylene diisocyanate, etc.

In addition, the acrylic incyanate component used as the main component is treated in the presence of a polymerization initiator having a functional group capable of reacting with the incyanate group or a chain transfer agent having a functional group capable of reacting with the inocyanate group. An unsaturated monomer having one functional group that can react with a cyanate group (hereinafter referred to as 3
b) 50 to 100% by weight of an alkyl (meth)acrylate ester and 50 to 4% by weight of an unsaturated monomer copolymerizable therewith (hereinafter referred to as b monomer). A low molecular weight acrylic copolymer having an average of about 1 functional group at the end of the molecule and an average of about 11 functional groups at arbitrary positions within the molecule, which can react with the incyanate group obtained by copolymerizing Obtained by reacting organic cyanocyanate.

Examples of the polymerization initiator having a functional group capable of reacting with the incyanate group include polymerization initiators having a carboxyl group and a hydroxyl group. Examples include biscyanopentanol.

Chain transfer agents having a functional group capable of reacting with an isocyanate group include chain transfer agents having a carboxyl group or an amide group, and specifically include thioglycolic acid, 2-mercaptoacetic acid, and 2-mercaptoethanolone. Examples include 2-aminoethanethiol 1 and the like.

During copolymerization, this polymerization initiator and this chain transfer agent may be used together, or either one of them may be used. The amount used is based on the introduction of an average of about one functional group capable of reacting with the incyanate group derived from the polymerization initiator or chain transfer agent into the molecular end of the low molecular weight copolymer. In order to prevent the average molecular weight of this copolymer from becoming too low or too high, 0.0% is added to 100 parts by weight of B monomer.
The amount is in the range of 3 to 20 parts by weight.

Next, the a monomer mentioned above is an unsaturated monomer having a carboxyl group or a hydroxyl group, and specifically, acrylic acid, methacrylic acid, maleic acid, acrylic acid 2-hydroxyethinope, methacrylic acid 2-hydroxy Examples include ethyl.

In addition, the above l) monomer refers to acrylic acid or methacrylic acid having 2 to 14 carbon atoms, such as ethyl, n-butyl, isobutyl, -ethylpropyl, 2-methylpentynope, 2-ethylphthyl, and 2-ethylhexyl. 100 to 5 of one or two or more alkyl esters
0% by weight and other monomers copolymerizable with these, such as vinyl acetate, vinyl propionate, acrylonitrile, methyl methacrylate, styrene, acrylamide, etc., in an amount of 0 to 50% by weight. If the amount of this copolymerizable monomer exceeds 50% by weight, it is not preferable because weather resistance decreases.

The usage ratio of the λ monomer and the b-am form is such that the amount of the a monomer used is 1/1 to 11,500 mol of the amount of the btrt form, taking into account the degree of polymerization and the polymerizability ratio. It is determined that an average of about one functional group capable of reacting with the incyanate group derived from the a monomer is introduced at any position within the molecule of the acrylic low molecular weight copolymer.

The acrylic low molecular weight copolymer is prepared by adding a predetermined amount of a in the presence of the predetermined amount of the polymerization initiator or chain transfer agent described above.
It is obtained by copolymerizing the monomer and monomer b according to a conventional method. Polymerization is a radical process, and conventional polymerization initiators such as benzoyl peroxide and α・α-azobisisobutyronitrile are used, but when using the specific polymerization initiators mentioned above, these A conventional initiator is not necessary.

It is preferable to carry out bulk polymerization without using a solvent in this copolymerization, and if unreacted monomer remains, it will cause odor during sealant application and eye discoloration after application, so unreacted monomer Polymerization conditions such as temperature and time are adjusted so that no residue remains.

An acrylic incyanate component is obtained by reacting the copolymer thus obtained with an organic diisocyanate. As this organic diisocyanate,
Those exemplified as the polyoxyalkylene incyanate component can be used similarly. The average molecular weight of the acrylic incyanate component is not particularly limited as long as it is in liquid form, and it is preferable to use one having an average molecular weight of 1,500 to 6,000.

The polyol, which is one component of the curing agent in the elastic sealant of the present invention, is obtained by copolymerizing the same polyhydric alcohol and alkylene oxide as exemplified in the polyoxyalkylene incyanate component of the main ingredient.

The average molecular weight of this polyoxyalkylene polyol is 1
,000 or more, preferably 2,000 to 6,000.

The low molecular weight acrylic copolymer, which is another component of the curing agent, can be obtained in the same manner as the low molecular weight acrylic copolymer described for the acrylic isocyanate component as the main ingredient. However, the average molecular weight of this copolymer is 2
,000 or more, preferably 2,500 to 20,000.

The blending ratio of the above two components in the curing agent is preferably such that the polyol accounts for 10% by weight or more. This is because if the acrylic low molecular weight copolymer used in combination with this polyol has an average molecular weight of 2,000 or more and a viscosity of high or low viscosity, 10% by weight or more is mixed.
This is because the viscosity of the curing agent compounded system containing various additives to be described later does not become too high and the workability is good.

As mentioned above, the polyol in the curing agent in the elastic sealant of this invention has an average molecular weight of ii, oo.

Among the above-mentioned materials, an acrylic low molecular weight copolymer having an average molecular weight of 2,000 or more is used. This is due to the following reason.

That is, the polyoxyalkylene incyanate component or acrylic incyanate component used as the main component is obtained by reacting an organic diisocyanate with a polyoxyalkylene polyol or a copolymer of the same type as the acrylic low molecular weight copolymer in the curing agent, respectively. Because it is a product obtained by the reaction, it tends to have a higher viscosity compared to the polyokine alkylene polyol or acrylic low molecular weight copolymer before reaction, considering the molecule IN.

Therefore, sealants with relatively low molecular weights are used from the viewpoint of workability, but are not preferred from the viewpoint of the properties of the sealant after curing. Therefore, if the molecular weight of the component in the curing agent, which has a relatively low viscosity, is defined as described above, it is possible to prevent the crosslinking density of the cured sealant from increasing and to provide the sealant with sufficient elasticity.

The ratio of the polyoxyalkylene component to the acrylic component in the elastic sealant of this invention can be varied over a wide range depending on the purpose, but usually the acrylic component is 15 to 95% of the total amount of the base agent and curing agent. It is preferable to adjust the amount to % by weight. If the acrylic component in the sealant is too low, the properties of the sealant as an acrylic elastic body will be low and the weather resistance will be poor, which is not preferable. Further, if the amount is too large, the viscosity of the sealant increases and workability decreases, which is not preferable.

Further, in the elastic sealant of the present invention, the blending ratio of the main agent and the curing agent is usually 0.7 to 0.7 to 1 equivalent of the incyanate group in the main agent to the functional group capable of reacting with the incyanate group in the curing agent. It is preferable to adjust the amount to 11 equivalents.

The elastic nolant of the present invention can contain fillers and catalysts required for general sealants. Furthermore, pigments, anti-aging agents, anti-mold agents, antioxidants, ultraviolet absorbers, ozone deterioration inhibitors, thixotropic agents, etc. can be added as necessary.

This filler improves the strength of the cured sealant, and includes, for example, calcium carbonate, silica powder, talc, glass powder, titanium oxide, and the like. The amount added is preferably 30 to 200 parts by weight per 100 parts by weight of the curing agent; if the amount added is too small, it will be difficult to obtain the desired strength, and if the amount added is too large, the elongation of the cured product will be poor. Undesirable.

Further, as the catalyst, organometallic compounds such as siftyltin dilaurate, monobutyltin oxide, and dioctyltin dilaurate, and amine derivatives such as triethylenediamine, triethylenetetramine, and diaminodiphenylmethane can be used. These addition amounts are hardening agent 1
The amount is 0.01 to 5 parts per 00Ii parts.

The elastic sealant of the present invention constructed as described above has the advantage that it has good workability during construction and does not cause eye loss after construction. Furthermore, the sealant after curing has the characteristics of an acrylic elastic material, so it has excellent weather resistance, durability, and heat resistance, and easily follows changes in joint width, causing cracks. Never.

Next, embodiments of this invention will be described. In the following, parts mean parts by weight. Also, Mw means
It means weight average molecular weight, and % means weight %.

Example 1 100 parts of n-butyl acrylate, 10 parts of acrylonitrile
1.0 parts of acrylic acid, and 1.6 parts of thioglycolic acid.

30% of this blended composition was placed in a 200 cc four-bottle flask, and the contents were heated to 70° C. while stirring and replacing the inside of the flask with nitrogen. After purging with nitrogen for about 60 minutes, 0.1 part of α·α'-azobisisobutyronitrile was added, and heat generation immediately started. After this heat generation has slowed down a little, 0.2 parts of α・α-azobisisobutyronyl-IJ is added to the remainder of the above-mentioned composition using a dropping funnel and gradually added to the flask over about 3 hours. Added inside.

The point at which no heat generation was observed thereafter was defined as the end point of polymerization.

The acrylic low molecular weight copolymer thus obtained had a polymerization rate of 100%, a viscosity of 400 poise (30°C, 2 rpm) measured by a B-type rotational viscometer, and a molecular weight measured by vapor pressure osmosis of s, o o o, The number of carboxyl groups per molecule was 2.03.

Add 100 parts of this copolymer to polypropylene glycol (M
After adding 40 parts of w 3,000) and mixing uniformly, add 130 parts of calcium carbonate, 1 part of titanium dioxide, 2 parts of Tesparon 360ON (polyether ester type surfactant manufactured by Shusui Kasei Co., Ltd.), and 2 parts of dibutyl tin dilaure). 0.
5 parts were blended, premixed using a kneader, and further kneaded using three rolls to obtain a curing agent blending system for the elastic sealant of the present invention.

The main ingredient is a polyoxyalkylene incyanate component (Takenate L manufactured by Takeda Pharmaceutical Co., Ltd.) obtained by reacting a polyoxyalkylene polyol with an organic diisocyanate.
-1032, incyanate group content 2.85%), and 35 parts of the base resin were mixed with 100 parts of the curing agent so that the curing agent was about 130 parts per 100 parts of the base resin. It was made into a sealant.

Example 2 A low molecular weight acrylic compound was prepared in the same manner as in Example 1 using a blended composition consisting of 95 parts of n-butyl acrylate, 5 parts of styrene, 3 parts of 2-hydroxyethyl acrylate, and 2 parts of 2-mercaptoethanol. A polymer was obtained.

This acrylic low molecular weight copolymer has a polymerization rate of 100% and B
The viscosity measured by a type rotational viscometer was 80 poise (30℃, 2rP
m), the molecular weight determined by vapor pressure osmosis was 4,200. The number of hydroxyl groups per molecule was 2.08.

Add 100 parts of this copolymer to polypropylene glycol (M
After adding 50 parts of w 4,000) and mixing uniformly,
150 parts of calcium carbonate, 20 parts of titanium dioxide, 3 parts of Disparon 360ON (mentioned above), 0.2 parts of triethylenetetramine and 0.2 parts of carphone black were blended and thoroughly kneaded using a kneader and three rolls to produce the present invention. The curing agent formulation system was

As a main ingredient, the above acrylic low molecular weight copolymer 100
After dehydrating a portion, 2,4-tolylene diisocyanate 9
part, add 0.002 part of dibutyltin dilaurate, 8
An acrylic incyanate component (incyanate base amount: 2.05% by weight) into which incyanate groups were introduced was obtained by reacting at 0° C. for 5 hours.

So that the curing agent is about 93 m per 100 parts of the main resin.
50 parts of this acrylic low molecular weight copolymer was blended with 100 parts of a curing agent compound to prepare an elastic sealant of the present invention.

Example 3 100 parts of acrylic acid + 1-butyl, 1 part of acrylonitrile
5 parts, 1.5 parts of acrylic acid, 1.8 parts of 2-mercaptoacetic acid
An acrylic copolymer was obtained in the same manner as in Example 1 using a blended composition consisting of: However, α as a polymerization initiator
・Azobiscyanohalerianic acid was used instead of α'-azobisisobutyronitrile.

This copolymer had a polymerization rate of 100%, a viscosity of 180 poise measured by a B-type rotational viscometer (30° C., 2 rpm), a molecular weight of 6,200 measured by vapor pressure osmosis, and a number of carboxyl groups per molecule of 205.

Polypropylene glycol (M
w 3,000) After adding 20 parts and mixing uniformly,
110 parts of calcium carbonate, 25 parts of titanium dioxide, 1.7 parts of Disparon 3.60ON (mentioned above), and 0.5 parts of dibutyltin dilaurate were mixed and thoroughly kneaded using a kneader with 13 rolls to form a hardening agent compound system. And so.

Using the same base ingredient as the base ingredient in Example 2, base ingredient 1
The elastic sealant of the present invention was prepared by blending 100 parts of a curing agent compounding system with 40 parts of this main ingredient so that the curing agent was about 120 parts per 00 parts.

Example 4 50 parts of n-butyl acrylate, 50 J of ethyl acrylate
Example 1 Using a blended composition consisting of 1 part of 2-hydroxyethyl acrylate and 2 parts of 2-mercaptoethylamine
An acrylic low molecular weight copolymer was obtained in the same manner as above.

This copolymer has a polymerization rate of 98.5%, a viscosity of 800 boids (30°C, 2 rPm) measured by a B-type rotational viscometer, and a molecular weight of 13.0 mm measured by vapor pressure osmosis. The OOQ, the number of hydroxyl groups per molecule was 1.03, and the number of amide 7 groups was 1.05.

Polypropylene glycol (I) was added to 100 parts of this copolymer.
After adding 100 parts of W2,000) and mixing uniformly, 200 parts of calcium carbonate, 30 parts of titanium dioxide, 4 parts of Disparon 360ON (mentioned above), 0.2 part of dibu-tiltin dilaurate, and 0.2 part of carbon black. were blended and sufficiently kneaded using a kneader and three rolls to obtain a curing agent blended system.

A polyoxyalkylene incyanate component obtained by reacting a polyoxyalkylene polyol with an organic isocyanate as a main ingredient (trade name Coronate 4095, manufactured by Nippon Polyurethane Co., Ltd., incyanate group content 6.0%)
), and 100 parts of a curing agent compounding system was blended with 20 parts of the base resin so that the curing agent was about 220 parts per 100 parts of the base resin to obtain the elastic sealant of the present invention.

Regarding the elastic sealants obtained in Examples 1 to 4 above,
When characteristics were evaluated based on JIS-A-5758, all sealants had a slump of 0 and were free from staining. Furthermore, the extrudability and tensile adhesion properties were as shown in the following table.

Furthermore, when the cured products of the elastic sealants of Examples 1 to 4 were subjected to an outdoor exposure test (6 months), no surface cracks were found in any of them.

In addition, as a comparative example, polypropylene glycol (Mw
An outdoor exposure test (6
When the cured product was subjected to a heat treatment, many cracks appeared on the surface of the cured product, and the weather resistance was poor.

Patent Applicant Nitto Electric Industry Co., Ltd. Agent Patent Attorney Wataru Ne
,=1J

Claims (1)

[Claims] (1) A polyoxyalkylene isocyanate component having an isocyanate group at the end of the molecule obtained by reacting a polyoxyalkylene polyol with an organic cyanocyanate, or an inocyanate group on average of about one at the end of the molecule and at any position within the molecule. The main ingredient is an acrylic low molecular weight copolymer incyanate component having an average molecular weight of i1. ．． An acrylic low molecular weight copolymer with an average molecular weight of 2,000 or more and having an average of about 1 functional group at the end of the molecule and an average of 1 functional group capable of reacting with an isocyanate group at any position within the molecule and a polyoxyalkylene polyol of ooo or more. Elastic sealant whose hardening agent is a mixture with coalescing.