JPH0218356B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a (meth)acrylate resin for sealants and a sealant composition using the same. Sealants that fill the joints of structures, etc. are required to have a high degree of elasticity that can follow the movement of the joints in response to changes in the climate of the building materials and other structures.
It is also required to have excellent adhesion to these structures. It is important that such a sealing material has the above-mentioned properties, is tack-free, has little contamination by dust, etc., and has excellent weather resistance. Conventionally, such sealing materials include (meta)
Two-component sealants consisting of an acrylate resin and a polyfunctional isocyanate are widely used. Various attempts have been made to improve such (meth)acrylate resins for sealing materials. For example, in Japanese Patent Application Laid-open No. 53-92868, one OH group and/or COOH group was added to the polymer end.
It has been proposed to use a (meth)acrylate resin having one OH group and/or COOH group at any position of the polymer. Also, JP-A-55
No.-18456 proposes the use of (meth)acrylate resins having 1.7 to 10 OH groups and/or COOH groups in the polymer. Sealing materials using (meth)acrylate resins such as these certainly exhibit good elasticity and adhesion, but on the other hand, they tend to slump (sag during construction) at high temperatures and are susceptible to surface hardness. It was found that it has disadvantages such as being sticky, which becomes more noticeable when the temperature rises. As a result of extensive research to improve these drawbacks, the inventors of the present invention have found that in terms of physical properties, it has excellent adhesion to cement mortar and aluminum sash, has high elasticity, good weather resistance, and is easy to work with. On the surface, we have completed a sealing material (meth)acrylic resin that does not cause slump, has no volatile components, and has a small change in viscosity due to temperature in summer and winter. The following is a (meta) sealant for the present invention.
Details of the acrylic resin and sealant composition will be explained. The (meth)acrylate resin for the sealant of the present invention has the formula (Here, R ₁ represents H or CH ₃ and R ₂ represents an alkyl group) Monomer and formula of (Here, R ₃ represents H or CH ₃ and R ₄ represents H or a hydroxyalkyl group) as the main component, and was obtained by copolymerizing in the presence of a chain transfer agent. A copolymer with a number average molecular weight of 1000
~10000, M/M is 2.5 to 5.0, and hydroxyl value is 15 to 120 (meth) for sealing materials.
It is an acrylate resin. Monomer of formula () and formula () in (meth)acrylate resin for sealing material of the present invention
The composition ratio of the monomers is 80 to 98% by weight of the monomer of formula (), 20 to 2% by weight of the monomer of formula (), preferably 85 to 98% of the monomer of formula (). 97% by weight
The monomer of formula () is used in an amount of 15 to 3% by weight. If the monomer of formula () exceeds 98% by weight, tack and stainability tend to decrease, while if it is less than 80% by weight, elongation tends to decrease and extrudability tends to deteriorate. Formula () is the raw material monomer for the (meth)acrylate resin for the sealant of the present invention.

In the formula, R ₁ represents H or CH ₃ , preferably H, and R ₂ represents an alkyl group, preferably an alkyl group having 4 to 8 carbon atoms. Examples of such preferable monomers include n-butyl (meth)acrylate,
Butyl (meth)acrylate such as sec-butyl (meth)acrylate, ter-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n There are octyl (meth)acrylates such as -octyl (meth)acrylate, and among the above-mentioned monomers, acrylates are more preferable than methacrylates, and among them, butyl acrylate is particularly preferable. Furthermore, two or more monomers of formula () can be used in combination as necessary. expression ()

In the monomer represented by the formula, R ₃ represents H or CH ₃ , preferably H, and R ₄ represents H or a hydroxyalkyl group, preferably a hydroxyalkyl group, particularly preferably an alkyl moiety. An example of such a monomer of formula () representing a hydroxyalkyl group having 2 to 3 carbon atoms is 2-hydroxyethyl (meth)
Acrylate, 2-hydroxypropyl (meth)
acrylate, 2-hydroxybutyl acrylate, 5-hydroxyhexyl methacrylate,
Examples include 8-hydroxyoctyl acrylate, acrylic acid, and methacrylic acid, of which 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and especially 2-hydroxyethyl acrylate are preferred. Furthermore, two or more monomers of formula () can be used in combination, if necessary. In this specification, the term "main component" refers to the monomer of formula () and the monomer of formula () as the sum of the copolymerized monomer of formula () and the monomer of formula (). It is used in the sense that the amount is 80% by weight or more, preferably 90% by weight or more based on the obtained copolymer. The (meth)acrylate resin for the sealing material of the present invention may contain a monomer of the above formula () and a structural unit derived from a chain transfer agent and/or a polymerization initiator in addition to the monomer of formula (). Of course, formula () and copolymerizable monomers other than formula () may be contained as necessary. Examples of the third component of such monomers include vinyl esters, vinyl ethers, vinylpyridine, acrylonitrile, methacrylonitrile, methylene glutaronitrile,
Examples include N,N-dimethylaminoethyl acrylate, butadiene, styrene, chloroprene, and acrylamide. The type and proportion of these unsaturated monomers to be used may be appropriately determined depending on the intended use of the elastic sealant. The (meth)acrylate resin for sealing materials of the present invention is a copolymer containing the monomers of the above formulas () and () as main components, and has a number average molecular weight (M) of 1000 to 10000. , weight average molecular weight/
The number average molecular weight (hereinafter referred to as "M/M") ratio must be from 2.5 to 5.0, and the hydroxyl value must be from 15 to 120. The number average molecular weight of the copolymer is 1000
If it is too small, it is undesirable because it becomes tacky and dirt easily adheres to it, and it also causes migration to the base such as concrete. On the other hand, if it is too large, exceeding 10,000, the flexibility of the resin will decrease and the elasticity will be low.
This is not preferable because fluidity is lost and workability becomes poor. Preferably 1000-8000, more preferably 1500
A copolymer with a number average molecular weight of ~6000 is used. On the other hand, it is extremely important for the (meth)acrylate copolymer for sealing materials of the present invention that the M/M of the copolymer be 2.5 to 5.0. M
If W/M is too small (less than 2.5), slump (sagging during application) will occur and the viscosity will decrease in summer, which is undesirable. On the other hand, if M/M is too large (more than 5.0), high rubber elasticity will be lost. , and the viscosity also increases, which is unfavorable for work. Especially from 2.5
A M/M in the range of 4.0 is preferred. M/M
The range of 2.5 to 5.0 can be adjusted by selecting a combination of a polymerization initiator with a fast decomposition rate and a polymerization initiator with a slow decomposition rate, a chain transfer agent, etc. at the polymerization temperature. Moreover, the hydroxyl value of the (meth)acrylate copolymer for sealing materials of the present invention is 15 to 120, preferably 20 to 80, and most preferably 25 to 60. If the hydroxyl value is too low (less than 15), the adhesive strength will be poor and the adhesive will not be tack-free, which is undesirable.
If it is too high, high elasticity will be lost, which is not preferable. "Hydroxyl value" in Koma means 1g of sample.
The number of mg of potassium hydroxide required to neutralize the acetic acid bound to the acetylated product obtained from
It refers to the hydroxyl value measured by the method described in JIS-K-0070-1966, and therefore refers to the OH group and thioglycerol possessed by the constituent units based on the monomer of formula () such as 2-hydroxyethyl acrylate. OH groups possessed by structural units based on chain transfer agents such as or 2-methylcaptoethanol, or OH groups possessed by structural units based on polymerization initiators such as 1,1 dihydroxycyclohexanone peroxide and azobiscyanopentanol. Refers to the total amount of base. The glass transition point (hereinafter referred to as "Tg") of the (meth)acrylic polymer of the present invention is preferably −10
℃ or less, more preferably -40℃, and Tg is -
If the temperature is too high, exceeding 10°C, high rubber elasticity will be lost, which is not preferable. Tg as used herein refers to one determined by the following method. In addition, the glass transition point (hereinafter sometimes abbreviated as "Tg") in the present invention refers to the general glass transition temperature as described in "Mechanical Properties of Polymers" by LE Nielsen, translated by Yoshiharu Onogi, pages 11 to 35. In the case of copolymers, it is the calculated Tg described on pages 26 to 27 of the same book. That is, the Tg of the copolymer was calculated using the following formula. 1/Tg=W1/Tg1+W2/Tg2+...+Wn/Tgn (however, W1+W2+...+Wn=1) Here, Tg is the copolymer glass transition temperature, and is calculated by converting it into an absolute temperature. Tg1, Tg2... and Tgn are the glass transition temperatures of pure homopolymers 1, 2... and n of component 1, component 2... and component n, respectively, and are calculated in terms of absolute temperature.
W1, W2... and Wn are the weight fractions of the respective components. As the polymerization initiator used in the polymerization of the (meth)acrylic polymer of the present invention, any commonly used polymerization initiators can be used, such as benzoyl peroxide, lauroyl peroxide, methyl ethyl ketone peroxide, and cumene. Hydroperoxide, azobisisobutyronitrile, di-n-propylpaoxydicarbonate,
Examples include t-butyl hydroperoxide, iso-butyl peroxide, 1-butyl-2-ethylhexanoate, and are usually unsaturated monomers.
It may be used in an amount of 0.05 to 10 parts by weight per 100 parts by weight, but if it is desired to control the molecular weight of the copolymer to a low value with this polymerization initiator, a larger amount can be used. In addition, the chain transfer agent may be any compound having a large ability to transfer polymer chains during polymerization, such as organic sulfur compounds such as carbon tetrachloride, carbon tetrabromide, acetic acid trichloride, and mercaptan derivatives. However, organic sulfur compounds are preferably used. Examples of such mercaptan derivatives include methyl mercaptan, ethyl mercaptan, butyl mercaptan, octyl mercaptan, lauryl mercaptan, phenyl mercaptan, cyclohexyl mercaptan, dimercapto diethyl ether, dimercapto diethyl sulfide, dimercapto dipropyl ether, etc. ,o-
Mercaptoethanol, m-mercaptophenol, thioglycerol, 1-thioglycerin,
1,2-thioglycerin, 2-mercaptoethanol, 3-mercaptopropanol, 4-mercaptobutanol, thiodiethylene glycol, dithioerythritol, 2,3-dimercapto-1
-OH of propanol, mercaptonaphthol, etc.
those having groups, and also thioglycolic acid, thiosuccinic acid, thiosalicylic acid, thiofumaric acid, thioxalic acid, dimercaptosuccinic acid, thiodiglycolic acid, dithiodiglycolic acid, mercaptopropionic acid, 3-mercaptopropionic acid, thiophene There are some that have a COOH group, such as dicarboxylic acid, thionaphthene-2-carboxylic acid, thiophenetetracarboxylic acid, and thiodipropionic acid.
Those having an OH group are particularly preferred, and among these, 2-mercaptoethanol, mercaptophenol, mercaptobutanol, mercaptopropanol, 1,2 dithioglycerin, thioglycerol, and the like are particularly preferred. These chain transfer agents are
It is usually used in a proportion of 0.1 to 15 parts by weight per 100 parts by weight of the unsaturated monomer, and by changing this amount, the molecular weight of the low molecular weight copolymer can be changed. Molecular weight can also be adjusted by changing the amount of polymerization initiator, but if, for example, a large amount of polymerization initiator is used to lower the molecular weight, the polymerization heat will increase and the polymerization operation will be interrupted. This causes great difficulty. However, when a chain transfer agent is used, less heat is generated and a low molecular weight copolymer can be easily produced. To copolymerize the monomer of the formula (), the monomer of the formula (), and the monomer of the third component such as the vinyl esters, any generally known polymerization method may be used, such as under high pressure. Polymerization is carried out under pressure using conventional radical polymerization methods used in the field, such as bulk polymerization, suspension polymerization, emulsion polymerization, and solution polymerization.
Solution polymerization and bulk polymerization are preferred because they tend to yield compounds with relatively small molecular weights. During the polymerization, the monomer mixture may be charged in its entirety at once from the beginning of the polymerization, or only a portion may be initially charged and the remaining mixture may be added dropwise as the polymerization reaction progresses. The latter method is particularly advantageous for products where polymerization heat generation is a problem, and the polymerization conditions such as temperature and time should be adjusted so that no gel-like copolymer is formed or unreacted monomer remains as much as possible. Adjust to Remaining unreacted monomer acts like a solvent for the copolymer, which is undesirable as it causes odor during application as a sealant and causes eye discoloration after application. The polymerization initiator is used so that the inner bath containing the mixture of the monomer and the chain transfer agent reaches a predetermined polymerization temperature,
Moreover, it is preferable to sufficiently replace the air in the polymerization tank with an inert gas such as nitrogen before adding. If a solvent is used, for example, n-heptane, n-hexane, toluene, xylene, ethyl cellosolve, butyl cellosolve, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, isopropanol, or the like may be used. The polymerization temperature varies depending on the type of monomer and polymerization initiator, but is generally preferably in the range of about 20 to 120°C. If the polymerization temperature becomes too high and generates too much heat, adjust it appropriately by cooling with water or the like. The polymerization time mainly depends on the polymerization temperature and the type of monomer. Another object of the present invention is a sealant composition containing the above-mentioned (meth)acrylate resin for sealants and a polyfunctional isocyanate compound, in detail (1) formula (Here, R ₁ represents H or CH ₃ , preferably H, and R ₂ represents an alkyl group preferably having 4 carbon atoms.
~8 representing an alkyl group) and a monomer of the formula (Here, R ₃ is H or CH ₃ , preferably CH ₃
, R ₄ is H or a hydroxyalkyl group,
(preferably a hydroxyalkyl group, particularly preferably a hydroxyalkyl group in which the alkyl moiety represents a hydroxyalkyl group having 2 to 3 carbon atoms) is the main component, and is obtained by copolymerization in the presence of a chain transfer agent. It is a combination,
Number average molecular weight is 1000-10000, preferably 1000
~8000, particularly preferably 1500~6000, M/
M is 2.5 to 5.0, preferably 2.5 to 4.0,
and a hydroxyl value of 15 to 120, preferably 20 to 80,
Particularly preferred is a sealant composition comprising a (meth)acrylate resin for a sealant of 25 to 60 and (2) a polyfunctional isocyanate compound, the composition comprising the resin and the polyfunctional isocyanate compound. This is a sealing material composition in which the ratio of NCO groups of the polyfunctional isocyanate compound is 0.7 to 1.5 equivalents per equivalent of hydroxyl groups of the resin, and is particularly suitable and excellent for concrete bases and aluminum sashes, most preferably for concrete bases. It has excellent adhesive strength. The polyfunctional isocyanate compound of the present invention refers to a compound having two or more isocyanate groups in one molecule, and examples of such polyfunctional isocyanate compounds include tolylene 2,4-diisocyanate, Trilene 2/6
-Diisocyanate, diphenylmethane-4.4
-diisocyanate, naphthylene 1,5-diisocyanate, hexamethylene diisocyanate,
Isophorone diisocyanate, triline diisocyanate, metaxylene diisocyanate, reaction product of 1 mol of trimethylolpropane and 3 mol of tolylene diisocyanate, or 1 mol of polyethylene glycol, 1 mol of polypropylene glycol, or 1 mol of polyoxytetramethylene glycol and 2 Examples include reaction products of polyols and various isocyanates, such as reaction products of molar tolylene diisocyanate, trimerized or multimerized isocyanates, and reaction products of polyisocyanates and phenols which liberate isocyanate groups at high temperatures. Suitable polyfunctional isocyanate compounds include polytolylene diisocyanate, polyhexamethylene diisocyanate, polyxylene diisocyanate, polydiphenylmethane diisocyanate, and isocyanate prepolymers composed of polyols and various isocyanates. (Meta) in the sealant composition of the present invention
The blending ratio of the acrylate resin and the polyfunctional isocyanate compound is such that the NCO group of the polyfunctional isocyanate compound is 0.7 to 1.5 equivalents, preferably 0.8 to 1.2 equivalents, per 1 equivalent of hydroxyl group of the resin. If it is less than 0.7 equivalent, tack-free property will not be obtained, and adhesive force and high elasticity will be lowered, and chemical resistance will also be lowered, which is not preferable. On the other hand, if the amount exceeds 1.5 equivalents, high elasticity is lost, weather resistance is also reduced, and it becomes brittle, which is not preferable. In addition to the (meth)acrylate resin and the polyfunctional isocyanate compound, a catalyst and a filler may be added to the sealant composition of the present invention as necessary. As such a catalyst, for example, metal compounds such as dibutyltin dilaurate, monobutyltin oxide, dioctyltin dilaurate, stannath octoate, or amines such as triethylenediamine, triethylenetetramine, dimethylbenzylamine, etc. can be used. The amount added is usually 0.01 to 100 parts by weight of the low molecular weight copolymer.
5 parts by weight is sufficient. The filler used in the present invention is used to improve the strength of the elastic sealant of the present invention and to improve workability by adjusting the viscosity of the sealant, such as calcium carbonate, silica powder, talc, etc. glass powder, magnesia,
Clay powder, titanium oxide, etc. are preferably used.
The addition ratio is (meth)acrylate copolymer
The amount is preferably 30 to 200 parts by weight per 100 parts by weight; if the amount is less than this, it will be difficult to obtain a product with the desired strength, and if it is too much, the elongation rate of the cured product will be low and the desired elasticity will be lowered. Difficult to obtain characteristics. In addition to the above-mentioned ingredients, the elastic sealant of the present invention contains plasticizers, pigments, anti-aging agents, anti-mold agents, antioxidants, etc., which are used in general sealants.
UV absorbers, ozone deterioration inhibitors, tackifiers,
A thixotrope or the like can also be added. Next, the present invention will be explained in more detail with reference to Examples. In addition, in the following, parts indicate parts by weight. Example 1 (Resin A-1 for sealing material) 192 parts of BA and 8 parts of 2HEA were added to a pressurized reaction apparatus equipped with a dropping device, a stirrer, reflux cooling, and a thermometer, and the temperature was raised to 90°C while stirring. . When the temperature rises
7.0 parts of 2-mercaptoethanol was added sequentially, and when about 1/3 was added, it suddenly generated heat to 120-135℃.
However, the dropwise addition continued and was completed in about 60 minutes. Continue the reaction and after 2 hours
At a controlled temperature of 80-85℃, Perbutyl P.
V. (manufactured by NOF) was added in 1/5 portions every 30 minutes in 5th installments, and the reaction was continued for 2 hours after the 5th addition. A low molecular weight copolymer A-1 having a non-volatile content of 99.5% was obtained. M/M of this low molecular weight copolymer is 11400/
3400=3.4, hydroxyl value 41, viscosity 18000cps,
Tg was -55℃. Example 2 (Resin A-2 for sealing material) 80 parts of ethyl cellosolve and 8 parts of 2-lauryl mercaptan were placed in a reaction apparatus equipped with a dropping device, a stirrer, a reflux condenser, and a thermometer, and heated to 110°C while stirring.
The temperature rose to . After heating up, add 44 parts of BA, 50 parts of 2EHA,
A mixture of 6 parts of 2HEA and 4 parts of Perbutyl PV (manufactured by NOF Corporation) was continuously added dropwise over about 3 hours, and after the addition was completed, the reaction was continued for 1 hour, and further perbutyl was added.
0.5 part of PV was added and the reaction was continued for 2 hours. The resulting reaction solution was concentrated under reduced pressure to obtain a low molecular weight copolymer A-2 with a nonvolatile content of 98.5%. M/M of this low molecular weight copolymer is 14900/5300=2.8, hydroxyl value 27.8,
The viscosity was 48,000 cps and the Tg was -56°C. Example 3 (Resin A-3 for sealing material) Polymerization was carried out in the same manner as in Example 1, except that 91 parts by weight of butyl acrylate, 9 parts by weight of 2-hydroxyethyl acrylate, and 3.5 parts by weight of 2-mercaptoethanol were used. A low molecular weight copolymer A-3 was obtained. The results are shown in Table 1. Example 4 (Resin A-4 for sealing material) Polymerization was carried out in the same manner as in Example 1 except that 85 parts by weight of butyl acrylate, 15 parts by weight of 2-hydroxyethyl acrylate, and 3.5 parts by weight of 2-mercaptoethanol were used to obtain a low molecular weight resin. Copolymer A-4 was obtained.
The results are shown in Table 1. Example 5 (Resin A-5 for sealing material) 40 parts by weight of benzene, 40 parts by weight of methyl n-propyl ketone, and 5 parts by weight of t-dodecyl mercaptan were placed in the same reaction apparatus as in Example 2, and heated to 80°C while stirring. After raising the temperature to , 85 parts by weight of butyl acrylate, 13 parts by weight of 2-ethylhexyl acrylate,
3 parts by weight of acrylic acid, 10 parts by weight of 2-hydroxyethyl acrylate, 3 parts by weight of benzoyl peroxide,
A mixture of 4 parts by weight of Perloyl IPP (manufactured by NOF Corporation) was continuously added over a period of 2 hours, and after the addition was complete,
The reaction was continued for 1 hour, and then 0.5 part by weight of benzoyl peroxide was added, and the reaction was continued for 1 hour. The reaction solution was concentrated under reduced pressure to obtain a low molecular weight copolymer A- with a non-volatile content of 99%.
Got 5. The results are shown in Table 1. Example 6 (Resin A-6 for sealing material) 74 parts by weight of butyl acrylate, 10 parts by weight of methyl acrylate, 2-
Add 16 parts by weight of hydroxyethyl acrylate,
The temperature was raised to 65°C while stirring, and when the temperature rose, 6.5 parts by weight of mercaptophenol was added. After continuing the reaction for 3 hours, 0.4 parts by weight of perbutyl PV was added in 4 portions of 1/4 every 30 minutes. The reaction was continued for 2 hours to obtain a low molecular weight copolymer A-6. The results are shown in Table-1. Example 7 (Resin A-7 for sealing material) 85 parts by weight of 2-ethylhexyl acrylate, 10 parts by weight of ethyl acrylate, 5 parts by weight of 2-hydroxyethyl methacrylate, 7 parts by weight of thioglycolic acid
Polymerization was carried out in the same manner as in Example 1 except that parts by weight were used to obtain a low molecular weight copolymer A-7. The results are shown in Table 1. Comparative Example 1 (Resin A-8 for Sealant) Into the same reaction apparatus as in Example 2, 1 part of a mixture of 87 parts by weight of butyl acrylate, 9 parts by weight of acrylonitrile, 2 parts by weight of acrylic acid, and 8 parts by weight of 2-hydroxyethyl acrylate was added. /3, replace with nitrogen while stirring, and raise the temperature to 70℃. V when the temperature rises
Add 0.1 part by weight of V-65 (manufactured by Wako Pure Chemical Industries) and react for 30 minutes, then add 0.2 part by weight of V-65 to the remaining 2/3 of the monomer mixture, which was added sequentially over 2 hours, and then aged for 2 hours. A low molecular weight copolymer A-8 having a non-volatile content of 97.5% was obtained. The results are shown in Table 1. Comparative Example 2 (Resin A-9 for sealing material) Polymerization was carried out in the same manner as in Example 6, except that 100 parts by weight of butyl acrylate and 6 parts by weight of 2-mercaptoethanol were used, and the reaction temperature was 90°C. Polymer A-9 was obtained. The results are shown in Table 1. Comparative Example 3 (Resin A-10 for sealing material) Example 1 except that 60 parts by weight of butyl acrylate, 17 parts by weight of 2-ethylhexyl acrylate, 23 parts by weight of 2-hydroxyethyl acrylate, and 5 parts by weight of 2-mercaptoethanol were used. Polymerization was carried out in the same manner as above to obtain a low molecular weight copolymer A-10. The results are shown in Table 1. Comparative Example 4 (Resin A-11 for sealing material) 100 parts by weight of benzene, 5 parts by weight of lauryl mercaptan, 65 parts by weight of methyl acrylate, 29 parts by weight of ethyl acrylate, and 6 parts by weight of 2-hydroxyethyl acrylate were placed in the same reaction apparatus as in Example 2. using 3 parts by weight and 3 parts by weight of Perbutyl H (manufactured by NOF Corporation),
Polymerization was carried out in the same manner as in Example 2 except that the reaction temperature was 80°C to obtain a low molecular weight copolymer A-11. The results are shown in Table 1. Comparative Example 5 (Resin A-12 for sealing material) In the same reaction apparatus as in Example 2, 78 parts by weight of ethyl acrylate, 17 parts by weight of butyl acrylate, 2-
Comparative Example 1 except that 2.5 parts by weight of hydroxyethyl acrylate, 3.4 parts by weight of lauryl mercaptan, and 0.3 parts by weight of azobisisobutyronitrile were used.
Polymerization was carried out in the same manner as above to obtain a low molecular weight copolymer A-12. The results are shown in Table 1. Comparative Example 5' (Resin A-13 for sealing material) 100 parts by weight of toluene and 3 parts by weight of 2-mercaptoethanol were placed in the same reaction apparatus as in Example 2.
After raising the temperature to 90°C with stirring, a mixture of 85 parts by weight of butyl acrylate, 12 parts by weight of 2-hydroxyethyl acrylate, 1 part by weight of azobisisobutyronitrile, and 2 parts by weight of perbutyl PV was continuously added over about 3 hours. After the addition was completed, the reaction was continued for 30 minutes, and 0.3 parts by weight of azobisisobutyronitrile was further added, and the reaction was continued for 1 hour. The reaction solution was concentrated under reduced pressure to obtain a low molecular weight copolymer A-13 with a nonvolatile content of 98.5%. The results are shown in Table 1.

[Table] The abbreviations in the table are as follows: AA: Acrylic acid BA: Butyl acrylate MA: Methyl acrylate EA: Ethyl acrylate 2EHA: 2-ethylhexyl acrylate 2HEMA: 2-ethylhexyl methacrylate AN: Acrylonitrile MP: Mercapto Phenol 2MEt: 2-mercaptoethanol TGA: Thioglycolic acid Example 8 (Sealing material) Low molecular weight copolymer resin synthesized in Example 1 (A
-1) 100 parts, 30 parts of titanium oxide, calcium carbonate
After kneading 125 parts, 1 part of carbon black, and 1 part of dibutyltin dilaurate in a kneader,
Thoroughly knead with 3 rolls and add Takenate L to this.
Add 120 parts of −1032 and mix uniformly while defoaming.
It was made into the sealing material of this invention. Its characteristics are shown in Table 3. Examples 9 to 17, Comparative Examples 6 to 13 (Sealing materials) Sealing materials were manufactured under the same conditions as in Example 8, except that the sealant formulations shown in Table 2 were used. Its characteristics are shown in Table 3. Physical property measurement method: Γ tensile properties Sealing material is applied on the release paper to a thickness of about 3~
Flatten it so that it is 3.5mm without any bubbles,
After curing at room temperature for 7 days, curing at 50°C ± 3°C for 7 days, leaving at room temperature for 24 hours, and punching into JIS No. 1 dumbbell test pieces as specified in JIS K-6301.
- Measured according to A-5757. Γ Hardness Apply sealant to a 12 to 13 mm thick workpiece to ensure a smooth surface and no bubbles, cure at room temperature for 10 days, at 50±3°C for 10 days, and pass the JIS spring type hardness test (manufactured by Shimadzu Corporation).・Measurement according to K-6301. Γtack, slump, contamination, breathing, and extrudability are measured according to JIS A-5757. Tack and contamination display 〇: None △: Slightly present ×: Yes ××: Strongly present

【table】

[Table] Note: * Manufactured by Takeda Pharmaceutical Co., Ltd. ** Manufactured by Nippon Polyurethane Co., Ltd.

【table】

【table】

Claims (1)

[Claims] 1 formula (Here, R ₁ represents H or CH ₃ and R ₂ represents an alkyl group) Monomer and formula of (Here, R ₃ represents H or CH ₃ and R ₄ represents H or a hydroxyalkyl group) as a main component, and is obtained by copolymerizing in the presence of a chain transfer agent. A polymer with a number average molecular weight of 1000~
10,000, M/M is 2.5 to 5.0, and a hydroxyl value is 15 to 120. (Meth)acrylate resin for sealing materials. 2. The resin according to claim 1, wherein R ₄ is a hydroxyalkyl group. 3. The resin according to claim 1 or 2, wherein the chain transfer agent is an organic sulfur compound. 4. The resin according to any one of claims 1 to 3, wherein _R2 is an alkyl group having 4 to 8 carbon atoms. 5. The resin according to any one of claims 1 to 4, which has a glass transition point of -10°C or lower. 6. The resin according to claims 1 to 5, wherein the monomer of the formula is n-butyl acrylate. 7. The resin according to any one of claims 1 to 6, wherein the monomer of the formula is 2-hydroxyethyl acrylate. 8. The resin according to any one of claims 2 to 7, which is a resin for a sealant used in cement mortar. 9 (1) Equation (Here, R ₁ represents H or CH ₃ and R ₂ represents an alkyl group) Monomer and formula of (Here, R ₃ represents H or CH ₃ and R ₄ represents H or a hydroxyalkyl group) monomers are copolymerized in the presence of a chain transfer agent. and the number average molecular weight is 1000~
10000, M/M is 2.5 to 5.0, and hydroxyl value is 15 to 120 (meth) for sealing materials.
A sealing material composition comprising an acrylate resin and (2) a polyfunctional isocyanate compound, wherein the blending ratio of the resin and the polyfunctional isocyanate compound is such that the amount of the polyfunctional isocyanate compound per equivalent of hydroxyl group of the resin is A sealant composition containing 0.7 to 1.5 equivalents of NCO groups.