JPH0125772B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel method for producing urethane (meth)acrylate prepolymers. More specifically, the present invention relates to a novel method for producing urethane (meth)acrylate prepolymers, which are less likely to cause phase separation in a dove, have high polymerization sensitivity, have good air curability, and have excellent hardness and toughness. The present invention relates to a method for producing a urethane (meth)acrylate prepolymer that can provide a cured film with a high temperature. Recently, inks, coating agents, and the like are rapidly being converted from thermosetting types to photocuring types. this is,
This is because it has been recognized that the light-curing type has advantages from an economic perspective such as productivity, energy saving, and space saving, as well as the clear advantage in terms of improving the working environment and preventing pollution due to being solvent-free. . By the way, the properties required of a photocurable composition are a high curing speed by light, excellent physical properties of the cured film, appropriate rheological properties of the composition solution, and low oxygen inhibition. There are certain things, etc. Currently, so-called prepolymers, which are high molecular weight unsaturated compounds, are the most important materials that play a key role in imparting the above properties to photocurable compositions, and there has been a fierce competition to develop them. There is. Conventionally developed prepolymers can be roughly divided into four types: unsaturated polyester types, epoxy (meth)acrylate types, urethane (meth)acrylate types, and various ester (meth)acrylate types.
Among them, urethane (meth)acrylates can be modified in a variety of ways depending on the reactivity of the isocyanate group, high film strength can be achieved through the intermolecular force of the urethane group, and flexibility can be imparted by introducing soft segments. type prepolymers are very promising.
In the present invention, (meth)acrylate is used to indicate acrylate and methacrylate. The above urethane (meth) that has been proposed so far
Acrylate prepolymers can be roughly divided into the following groups. Group A: Urethane (meth)acrylate obtained by linking the terminal hydroxyl groups of polyester, polyether, or hydrogenated polybutadiene with diisocyanate, and then reacting the isocyanate group remaining at the terminal with an unsaturated compound having a hydroxyl group. Group B: Urethane (meth)acrylates obtained by reacting the remaining isocyanate groups of the reaction product of a semi-drying oil and a polyvalent isocyanate with an unsaturated compound having a hydroxyl group. Group C: Epoxy (meth)acrylates obtained by reacting compounds having various epoxy groups with unsaturated basic acids, and the hydroxyl groups produced by this reaction are further reacted with a polyvalent isocyanate, and if necessary, Further, urethane (meth)acrylate in which the terminal isocyanate group is blocked with an unsaturated group (Japanese Patent Application Laid-open No. 151981/1983). Group D: Urethane (meth)acrylate obtained by reacting a polyvalent isocyanate with an unsaturated compound having a monovalent hydroxyl group such as 2-hydroxyethyl (meth)acrylate or 2-hydroxypropyl (meth)acrylate. A general review of the above four groups of urethane (meth)acrylates shows that those in Groups A and B have insufficient curing speed with light, and the resulting cured films are soft and have poor chemical resistance. Those in Group C produce a cured film with high hardness, but the solubility is poor and the resulting composition solution has a high viscosity, making it difficult to handle as a commercial product.
Those of group D have poor solubility, and moreover, phase separation tends to occur when left for a long time, and the selection of monomers is limited. Furthermore, JP-A-55-139468 discloses a urethane acrylate resin of a polyisocyanate compound and acrylic acid or methacrylic acid hydroxyester as a prepolymer, and specific examples include pentaerythritol diacrylate and pentaerythritol triacrylate. However, this urethane acrylate resin does not solve the problems of Groups C and D mentioned above. As mentioned above, urethane (meth)acrylates have many possibilities for improving physical properties due to their diverse molecular structures, but there are still none that have satisfactory performance in terms of physical properties of cured films and physical properties of composition solutions. Not obtained. In view of the above, the present inventors have focused on improving photocuring speed, solubility in monomers, lowering the viscosity of the resulting solution,
In order to obtain a urethane (meth)acrylate with well-balanced high performance in terms of the hardness of the cured film obtained, as a result of intensive research, we discovered a new urethane (meth)acrylate prepolymer with the following characteristics. The present invention has been accomplished. That is, the present invention provides a method for producing urethane (meth)acrylate in which a polyvalent isocyanate and a (meth)acrylate having a hydroxyl group are reacted, in which the (meth)acrylate having a hydroxyl group is represented by the following general formula (1). (However, R represents hydrogen or a methyl group, and n represents an integer of 1 to 4.) A compound represented by the formula, where n = 1 is 0
~5 mol%, n=2 compounds 1-30 mol%, n
A mixture (A) consisting of 20 to 60 mol% of the compound of = 3 and 5 to 79 mol% of the compound of n = 4, or mixture (A)
and a mixture of one or more compounds (B) other than general formula (1) having one to two hydroxyl groups and at least one unsaturated group. The present invention relates to a manufacturing method. The present invention will be explained in detail below. Examples of the polyvalent isocyanate which is one of the starting materials of the present invention include 2,6-tolylene diisocyanate, diphenylmethane-4,4'-diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, m-phenylene diisocyanate, and p-phenylene diisocyanate. nylene diisocyanate,
1,5-naphthylene diisocyanate, 3,3'-
Examples include dimethyl-4,4'-biphenylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, and adduct compounds of these with water, trimethylolpropane, and the like. Compound (A) forming a characteristic part of the prepolymer of the present invention
is a mixture of compounds in which the number n of (meth)acrylic acids introduced is obtained by an esterification reaction between tetramethylolmethane and acrylic acid or methacrylic acid. A preferred method is to carry out the reaction under conditions that produce a large amount of , and to moderately hydrolyze the resulting reaction product to obtain a mixture with the desired compound composition. The reason for this is that it is preferable that the content of the compounds where n=0 and n=1 be as small as possible. In the present invention, the compound (A) has the general formula
The compound represented by (1) is characterized in that it is used as a mixture of compounds with n=1, 2, 3, and 4, and therefore, the component composition ratio of the compounds with each integer value of n is important. . That is, as mentioned above, it is better to have as little as possible of the compound where n=1, and it is used in a range of 0 to 5 mol%. This is because if the amount exceeds 5 mol %, problems will arise in the solubility of the prepolymer obtained. Since the compound with n=2 has an unsaturated group in the side chain, it has the function of increasing the photocuring speed and further imparting toughness to the cured film, but at the same time it acts as a molecular weight regulator, so if it is present in too large a quantity, it will not be beneficial. The upper limit is 30 mol%, and it is preferably in the range of 1 to 30 mol%, and 20 mol%. It is more preferable that it is below.
The compound with n=3 increases the photocuring rate because it contains a trivalent unsaturated group, and furthermore, the intermolecular attraction between the urethane groups is weakened by steric hindrance based on the trivalent unsaturated group, and as a result, the monomer It is presumed that it increases solubility in other solvents and produces good results such as suppressing phase separation, but at the same time it functions as an end-blocking agent for polyvalent isocyanate, so if it is too large, it increases the low molecular weight components. However, since it further widens the molecular weight distribution, there is an upper limit to its content.
Moreover, if it is too small, the high molecular weight component will increase too much, so there is a lower limit, and the range of 20 to 60 mol% is preferable. n
Although the compound of =4 is the starting point for synthesizing the mixture of the compound of general formula (1) as the compound (A), it basically works as a diluent, so it cannot be used with other compounds. can be replaced by Polyvalent isocyanate and general formula (1) n = 1, 2,
The mixture (A) of compounds 3 and 4, and the compound (B) used by mixing as necessary, include a compound (B1) having two hydroxyl groups and at least one unsaturated group, When this compound (B1) is used, urethane (meth)acrylate with a higher molecular weight can be produced. The above compound (B1) having two hydroxyl groups and at least one unsaturated group may be bis(4,4'-hydroxyphenyl)-2,2'-propane or bis(4,4' - Hydroxyphenyl) methane and epichlorohydrin condensate, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexane diol di Examples include glycidyl ether, N,N-diglycidylaniline, and addition reaction products of N,N-diglycidylaniline and acrylic acid or methacrylic acid. The role of addition of compound (B1) is to enable control of the molecular weight and solubility of the prepolymer obtained beyond that which can be controlled by polyvalent isocyanate and compound (A) alone, and to improve photocuring speed, solubility, and cured film. The point is that it makes it possible to improve the toughness of the steel. Conventionally, as the molecular weight of prepolymers increases, the strength of the cured film decreases to a certain degree, but in urethane (meth)acrylate prepolymers made of polyvalent isocyanate, compound (A), and compound (B1), ,
Even though the main chain becomes longer, the density of unsaturated groups does not decrease because the repeating units contain unsaturated groups, and good photocuring sensitivity is maintained. Despite its high molecular weight, its solubility in monomers does not decrease, and it has the advantage of imparting toughness to the cured film. The amount of compound (B1) added is n of compound (A).
It is desirable that the sum of the two compounds be 30 mol% or less. In yet another embodiment of the present invention, the compound (A) is reacted with a polyvalent isocyanate.
1 as a compound (B) used as necessary with
The present invention includes a method for producing a urethane (meth)acrylate using a compound (B2) having at least one hydroxyl group and at least one unsaturated group, and as another embodiment, polyvalent isocyanate, compound (A), two A method for producing urethane (meth)acrylate by reacting a compound (B1) having a hydroxyl group and at least one unsaturated group and a compound (B2) having one hydroxyl group and at least one unsaturated group. includes. The above compound (B2) includes 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, a reaction product of glycidyl (meth)acrylate and an unsaturated acid or unsaturated alcohol, and ethylene glycol mono(meth)acrylate. ) acrylate, polyethylene glycol mono(meth)acrylate, propylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, etc. Compound (B2) serves as an end-capping agent and has the function of adjusting the double bond density and molecular weight of the obtained prepolymer. Therefore, 20 mol% of compound (A) with respect to the compound where n=3
The following quantities are used: Synthesis of the urethane (meth)acrylate prepolymer of the present invention, i.e., polyvalent isocyanate and compound (A), or (A) + (B), i.e. (A) + (B1), (A) +
The reaction with (B2) or (A) + (B1) + (B2) is
This may be carried out using a conventional method for prepolymer synthesis. That is, the ratio of total hydroxyl groups to isocyanate groups during charging is preferably within 1±0.1.
The solvent used is not particularly limited, but includes trimethylolpropane triacrylate, 1,6-hexane glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, styrene,
Preferably, monomers such as methyl methacrylate are used. Dibutyltin dilaurate is usually used as a reaction catalyst. Addition amount of 200 ppm is sufficient. Further, as a polymerization inhibitor, for example, hydroquinone methyl ether is used. The amount added is approximately
About 50ppm is sufficient. Reaction temperature is 60~80℃
The standard reaction time is about 4 hours. Preferably, the reaction is carried out in an open air system. The urethane (meth)acrylate prepolymer of the present invention can be used alone or in combination with other prepolymers, or can be further diluted with a monomer. Monomers used as diluents include trimethylolpropane triacrylate, 2-hydroxyethyl methacrylate, 1,6-hexane glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, styrene, Examples include methyl methacrylate and mixtures thereof. The urethane (meth)acrylate prepolymer of the present invention is suitably used for photocuring using a photopolymerization initiator, but of course it is also suitable for thermosetting using a suitable thermal polymerization initiator. . Next, manufacturing examples and usage examples will be shown. Production example 1 Diphenylmethane-4,4'-diisocyanate
125 g and 4.2 mol% of the compound of general formula (1) where n = 2, n
200 ppm of dibutyltin dilaurate was added to a liquid consisting of 480 g of a mixture (A-1) consisting of 52.1 mol% of the compound of = 3 and the remaining compound of n = 4 (which contained 210 g of tetramethylolmethanetetraacrylate). The mixture was added and reacted at 70°C for 4 hours to obtain a urethane (meth)acrylate prepolymer. The infrared spectrum had no peaks for isocyanate groups, indicating that the reaction had taken place. The obtained prepolymer was dissolved in trimethylolpropane triacrylate/2-hydroxyethyl methacrylate (42/18 weight ratio) to give 50% by weight.
The viscosity measured as a solution at a temperature of 20°C was 15 poise. Production Examples 2 to 7 Reactions were carried out in the same manner as in Production Example 1 using the ingredients shown in Table 1, and the viscosity was measured. The ingredients composition and viscosity are shown in Table 1 together with Production Example 1. Comparative Production Example 1 A reaction was carried out in the same manner as in Production Example 1 using the ingredients shown in Table 1, and the viscosity was measured. It is shown in Table 1 together with Production Examples 1 to 7.

[Table] Usage example 1 Prepolymer 40PHR (resin
(parts by weight relative to 100 parts by weight) is trimethylolpropane triacrylate (TMPTA)
45 PHR, 2-hydroxyethyl methacrylate (2HEMA) was dissolved in a mixed monomer mixture of 15 PHR, and 1.5 PHR of Irgakyure 651 (manufactured by Ciba Geigy, benzyl methyl ketal, the same hereinafter) was added as a photopolymerization initiator and completely dissolved. The obtained solution was left at room temperature for a long period of time (more than 3 months), but no phase separation occurred. This solution was applied onto a glass epoxy substrate (without copper foil) to a thickness of 40 μm using a spacer. Apply this coating plate to a 10cm high-pressure mercury lamp with an output of 120W/cm.
I stood still for 10 seconds directly under the light and exposed it to light (equivalent to 1400mJ).
After exposure, the pencil hardness was measured according to JISD02028-10, and the hardness was as high as 8H. Usage Examples 2 to 7 As shown in Table 2, 40 PHR of each of the prepolymers listed in Table 1 were combined with 45 PHR of trimethylolpropane triacrylate (TMPTA) and 2-hydroxyethyl methacrylate (2HEMA).
It was dissolved in 15 PHR of mixed monomer, and 1.5 PHR of IRGAKURE 651 was added as a photopolymerization initiator to completely dissolve it. This solution was applied to a glass epoxy substrate (without copper foil) to a thickness of 40 μm using a spacer. It was exposed to light in the same manner as in Use Example 1, and the pencil hardness was measured. The results are shown in Table 2.

【table】

[Table] Comparative Use Examples 1 to 4 As comparative use examples, cured coating films were obtained under the conditions shown in Table 3. Various data are shown in Table 3.

[Table] ○R
Aronix 8030 〓Manufactured by Toagosei Co., Ltd., polyester prepolymer

Claims (1)

[Claims] 1. In a method for producing urethane (meth)acrylate in which a polyvalent isocyanate and a (meth)acrylate having a hydroxyl group are reacted, the (meth)acrylate having a hydroxyl group is represented by the following general formula (1). (However, R represents hydrogen or a methyl group, and n represents an integer of 1 to 4.) A compound represented by the formula, where n = 1 is 0
~5 mol%, n=2 compounds 1-30 mol%, n
A mixture (A) consisting of 20 to 60 mol% of the compound of = 3 and 5 to 79 mol% of the compound of n = 4, or mixture (A)
and a mixture of one or more compounds (B) other than general formula (1) having one to two hydroxyl groups and at least one unsaturated group. manufacturing method.