Radical-curable acrylic acrylate composition for automotive parts

Abstract

Provided is a radically curable acrylic acrylate composition for automotive parts that solves the problems of deterioration of basic mechanical properties in a low-Tg resin, reactivity stability during production, and low productivity. Provided is a radically curable acrylic acrylate composition for automotive parts that can be crosslinked with a small amount of energy in a short time as compared with the case of heat crosslinking. 【Solution means】 (a) An acrylic polymer, (a)-1 2-ethylhexyl acrylate, and (a)-2 2-hydroxyethyl methacrylate having, when the total weight of (a)-1 and the weight of (a)-2 is 100 parts by weight, 90 to 98 parts by weight of (a)-1 and 10 to 2 parts by weight of (a)-2; (b) 2-methacryloyloxyethyl isocyanate; formed to have (A) acrylic acrylate; and (B) 2-ethylhexyl acrylate A radically curable acrylic acrylate composition for automotive parts formed to have, when the total weight of (A) and the weight of (B) is 100 parts by weight, 55 to 75 parts by weight of (A) and 45 to 25 parts by weight of (B), solves the above problems with the above radically curable acrylic acrylate composition for automotive parts.

Description

Technical Field

[0001] The present invention relates to a radically curable acrylic acrylate composition for automotive parts.

Background Art

[0002] In recent years, in the production of resin products, there are requirements for energy reduction during molding and low VOC due to environmental considerations, and expectations for solvent-free radically curable resins are increasing. In addition, among these resin products, in products that require flexibility in a low-temperature environment, radically curable resins such as acrylic resins based on a molecular structure with a low glass transition temperature (hereinafter referred to as low Tg) are used.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, resins based on monomers with low Tg have poor cohesive force as a structure, low strength and strain at break, and there is a problem that it is difficult to apply them to product groups that require mechanical properties. In addition, as a solution, reduction and optimization of crosslinking groups and optimization of the molecular weight between crosslinking points by increasing the molecular weight can be mentioned. However, there are problems such as an increase in viscosity in the crosslinking group introduction process during resin production and the take-out process after the synthesis is completed, and accompanying problems of poor reaction stability and productivity during mass production.

[0005] Therefore, the object of the present invention is to provide an acrylic acrylate composition that solves the above problems, for example, a radical-curable acrylic acrylate composition, and in particular a radical-curable acrylic acrylate composition for automotive parts. Specifically, the object of the present invention is to provide an acrylic acrylate composition, such as a radical-curable acrylic acrylate composition, particularly a radical-curable acrylic acrylate composition for automotive parts, that solves the problems of reduced basic mechanical properties, reaction stability during production, and low productivity in low-Tg resins.

[0006] Furthermore, in addition to the above objectives, an object of the present invention is to provide an acrylic acrylate composition that can be crosslinked in a shorter time and with less energy compared to the case of heat crosslinking, such as a radical-curable acrylic acrylate composition, and in particular a radical-curable acrylic acrylate composition for automotive parts.

[0007] To solve the above problems, the present inventors have come up with the following invention. <1> (a) Acrylic polymer, (a)-1 2-ethylhexyl acrylate, and (a)-2 Hydroxyethyl methacrylate The acrylic polymer comprises the above, wherein if the sum of the weight of (a)-1 and the weight of (a)-2 is 100 parts by weight, then (a)-1 comprises 96 to 98 parts by weight, preferably 96.5 to 97.5 parts by weight, and (a)-2 comprises 4 to 2 parts by weight, preferably 3.5 to 2.5 parts by weight; (b) 2-methacryloyloxyethyl isocyanate; (A) Acrylic acrylate formed having; and (B) 2-ethylhexyl acrylate A radical-curable acrylic acrylate composition for automotive parts, formed having the following characteristics: The radical-curable acrylic acrylate composition for automotive parts, wherein the sum of the weights of (A) and (B) is 100 parts by weight, comprises 55 to 75 parts by weight, preferably 60 to 70 parts by weight, of (A) and 45 to 25 parts by weight, preferably 40 to 30 parts by weight, of (B).

[0008] <2> the above <1> In this case, the acrylic polymer (a) preferably has at least one of the following properties (a1) to (a3), or at least two of the properties, or all of the properties. (a1) Hydroxyl value of 8-18 mgKOH / g, preferably 11-15 mgKOH / g; (a2) Weight-average molecular weight is 600,000 to 750,000, preferably 680,000 to 720,000; (a3) The glass transition temperature is -60°C or lower, preferably -65°C or lower. It is preferable that the glass transition temperature be -80°C or higher.

[0009] <3> the above <1> or <2> In this case, the (A) acrylic acrylate preferably has at least one of the following properties (A1) to (A3), or at least two properties, or all of the properties. (A1) Weight-average molecular weight is 600,000 to 750,000, preferably 680,000 to 720,000; (A2) The glass transition temperature is -60°C or lower, preferably -65°C or lower. However, it is preferable that the glass transition temperature be -80°C or higher. (A3) The viscosity of CSR at 20°C is 50 to 1,000 Pa·s, preferably 100 to 900 Pa·s, more preferably 200 to 800 Pa·s, and most preferably 250 to 750 Pa·s.

[0010] <4> the above <3> In this case, the value calculated by the formula: ((A) Acrylate carbon-carbon double bond equivalent) / (weight %) of (A) Acrylate in 100% by weight of the radical-curable acrylic acrylate composition for automotive parts is preferably 43,000 to 48,000 g / mol, preferably 42,500 to 47,500 g / mol, more preferably 42,250 to 47,250 g / mol, and most preferably 42,000 to 47,000 g / mol. [Effects of the Invention]

[0011] The present invention provides an acrylic acrylate composition that solves the above problems, specifically a radical-curable acrylic acrylate composition, and more specifically, a radical-curable acrylic acrylate composition for automotive parts. Specifically, the present invention provides an acrylic acrylate composition, such as a radical-curable acrylic acrylate composition, particularly a radical-curable acrylic acrylate composition for automotive parts, that solves the problems of reduced basic mechanical properties, unstable reactivity during production, and low productivity in low-Tg resins.

[0012] Furthermore, in addition to the above objectives, the present invention aims to provide an acrylic acrylate composition that can be crosslinked in a shorter time and with less energy compared to the method of heat crosslinking, such as a radical-curable acrylic acrylate composition, and in particular a radical-curable acrylic acrylate composition for automotive parts. [Modes for carrying out the invention]

[0013] The invention described in this application (hereinafter sometimes abbreviated as "the present invention") will be explained below. This application provides a radical-curable acrylic acrylate composition for automotive parts.

[0014] In this specification, when used, "acrylic" and "methacrylic" are collectively referred to as "(meth)acrylic", "acrylate" and "methacrylate" are collectively referred to as "(meth)acrylate", and further, "acryloyl" and "methacryloyl" are collectively referred to as "(meth)acryloyl". In this specification, the "hydroxyl value" is the weight of potassium hydroxide required to acetylate 1 g of the sample and neutralize the acetic acid bound to the hydroxyl group. The value can be measured by a method conforming to JIS K 0070.

[0015] In this specification, the "weight-average molecular weight of the polymer" is a value measured using gel permeation chromatography (GPC) and converted with standard polystyrene.

[0016] In this specification, "viscosity" refers to that measured by a stress-controlled rheometer. The viscosity can be measured, for example, using a stress-controlled rheometer AR2000ex (manufactured by TA Instruments Japan), measurement probe: aluminum φ20, measurement mode: peak hold, shear rate: 1 (1 / s), measurement gap: 1 mm, measurement temperature: 20°C.

[0017] In this specification, the "glass transition temperature" is a value measured by a differential scanning calorimeter (DSC).

[0018] In this specification, the "carbon-carbon double bond group equivalent" is the weight of (A) acrylic acrylate per mole of radical-polymerizable carbon-carbon double bond. Specifically, it is a calculated value obtained by dividing the total weight (grams, g) of (A) acrylic acrylate having a carbon-carbon double bond group by the number of moles (mol) of the carbon-carbon double bond group present in the (A) acrylic acrylate. For example, it can be obtained as a calculated value by dividing the total weight of the starting materials for obtaining (A) acrylic acrylate by the number of moles of the compound having a carbon-carbon double bond used as the starting material.

[0019] Furthermore, the "carbon-carbon double bond equivalent" can be determined from the obtained carbon-carbon double bond-containing (A) acrylic acrylate as follows. Specifically, the total weight (grams, g) of (A) acrylic acrylate having carbon-carbon double bond groups is measured. Furthermore, the iodine value of the obtained (A) acrylic acrylate having carbon-carbon double bond groups is measured according to the method of JIS K 0070, and the amount of carbon-carbon double bonds in the sample is converted to moles from this measurement value. By dividing the measured total weight (grams, g) of (A) acrylic acrylate obtained above by the mole conversion value obtained above, the "carbon-carbon double bond group equivalent" can be obtained.

[0020] The "carbon-carbon double bond group" is preferably a "(meth)acryloyl group." In this case, the "carbon-carbon double bond group equivalent" is preferably expressed as the "(meth)acryloyl group equivalent." The "(meth)acryloyl group equivalent" can be determined in the same way as the "carbon-carbon double bond group equivalent" described above. Furthermore, the origin of the "carbon-carbon double bond group" from the "(meth)acryloyl group" can be determined by measuring NMR (nuclear magnetic resonance), etc.

[0021] <Radical-curable acrylic acrylate composition for automotive parts> The radical-curable acrylic acrylate composition for automotive parts of the present invention is (A) Acrylates; and (B) 2-ethylhexyl acrylate It is formed having the following characteristics. Here, if the sum of the weights of (A) and (B) is 100 parts by weight, then it is preferable to have 55 to 75 parts by weight of (A), preferably 60 to 70 parts by weight, and 45 to 25 parts by weight of (B), preferably 40 to 30 parts by weight.

[0022] <<(A) Acrylic acrylate>> (A) Acrylic acrylate is (a) Acrylic polymers; and (b) 2-methacryloyloxyethyl isocyanate; It is formed having the following characteristics. (A) The acrylic acrylate is preferably substantially composed of (a) and (b) above, and more preferably composed solely of (a) and (b). "Substantially composed of (a) and (b)" means that it may contain components other than (a) and (b), but these components must not impair the properties of (A) the acrylic acrylate.

[0023] (A) The acrylic acrylate may have at least one of the following properties (A1) to (A3), or at least two properties, or all of the following properties. (A1) Weight-average molecular weight is 600,000 to 750,000, preferably 680,000 to 720,000; (A2) The glass transition temperature is -60°C or lower, preferably -65°C or lower. However, it is preferable that the glass transition temperature be -80°C or higher. (A3) The viscosity at 20°C is 50 to 1,000 Pa·s, preferably 100 to 900 Pa·s, more preferably 200 to 800 Pa·s, and most preferably 250 to 750 Pa·s.

[0024] (A) The acrylic acrylate has a ratio of its "carbon-carbon double bond equivalent" to "weight % of (A) acrylic acrylate in 100% by weight of the radical-curable acrylic acrylate composition for automotive parts," where ((A) acrylic acrylate carbon-carbon double bond equivalent) / (weight %) of (A) acrylic acrylate in 100% by weight of the radical-curable acrylic acrylate composition for automotive parts) is preferably 43,000 to 48,000 g / mol, preferably 42,500 to 47,500 g / mol, more preferably 42,250 to 47,250 g / mol, and most preferably 42,000 to 47,000 g / mol.

[0025] <<(a) Acrylic polymer>> (a) Acrylic polymers are (a)-1 2-ethylhexyl acrylate, and (a)-2 Hydroxyethyl methacrylate It is formed having the following characteristics. Here, if the sum of the weight of (a)-1 and the weight of (a)-2 is 100 parts by weight, then it is preferable to have 96 to 98 parts by weight of (a)-1, preferably 96.5 to 97.5 parts by weight, and 4 to 2 parts by weight of (a)-2, preferably 3.5 to 2.5 parts by weight.

[0026] (a) The acrylic polymer is preferably possessing at least one of the following properties (a1) to (a3), or at least two of the properties, or all of the properties listed below. (a1) Hydroxyl value of 8-18 mgKOH / g, preferably 11-15 mgKOH / g; (a2) Weight-average molecular weight is 600,000 to 750,000, preferably 680,000 to 720,000; (a3) The glass transition temperature is -60°C or lower, preferably -65°C or lower. It is preferable that the glass transition temperature be -80°C or higher.

[0027] In this specification, "automotive parts" may include, but is not limited to, coating materials for automotive interior parts.

[0028] <Method for producing radical-curable acrylic acrylate composition for automotive parts> The radical-curable acrylic acrylate composition for automotive parts of the present invention can be manufactured by, for example, the following manufacturing method, but is not limited thereto. (I) A step of obtaining a first solution comprising (a)-1 2-ethylhexyl acrylate and (a)-2 2-hydroxyethyl methacrylate; (II) A step of polymerizing the first solution to obtain (a) an acrylic polymer; (III) A step to obtain a second solution having (a) the obtained acrylic polymer and (b) 2-methacryloyloxyethyl isocyanate; (IV) A step of reacting the second solution to obtain (A) acrylic acrylate; (V) A step of mixing (A) acrylic acrylate and (B) 2-ethylhexyl acrylate; By having this, a radical-curable acrylic acrylate composition for automotive parts can be obtained. (a)-1 2-ethylhexyl acrylate, (a)-2 2-hydroxyethyl methacrylate, (a) acrylic polymer, (b) 2-methacryloyloxyethyl isocyanate, (A) acrylic acrylate, and (B) 2-ethylhexyl acrylate have the same definitions as above. [Examples]

[0029] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples. (Example 1) (Synthesis Example A1: Synthesis of acrylic polymer a1 having hydroxyl groups) In a reaction apparatus equipped with a stirrer, reflux condenser, thermometer, dropping funnel, and nitrogen inlet tube, 1000 parts by weight of ethyl acetate, 776 parts by weight of 2-ethylhexyl acrylate (2-EHA), 24 parts by weight of 2-hydroxyethyl methacrylate (HEMA), and 1 part by weight of azobisisobutyronitrile (AIBN) were charged, and the inside of the reaction apparatus was purged with nitrogen. Subsequently, the polymerization reaction was carried out under atmospheric pressure and 70°C for 8 hours to obtain an ethyl acetate solution of acrylic polymer a1.

[0030] The hydroxyl value of the obtained acrylic polymer a1 was measured using a method conforming to JIS K 0070 and found to be 12.9 mg KOH / g. Furthermore, when the glass transition temperature of acrylic polymer a1 was measured by DSC, it was found to be -65°C. Furthermore, when the weight-average molecular weight of acrylic polymer a1 was measured by GPC, it was found to be approximately 600,000. From the above, it was found that polymer a1 is an acrylic polymer having hydroxyl groups.

[0031] (Example 1-A1: Preparation of acrylic acrylate and composition A1 having the acrylic acrylate) To an ethyl acetate solution containing 100 parts by weight of the acrylic polymer a1 obtained in Synthesis Example A1, 40 parts by weight of 2-EHA and 0.5 parts by weight of dibutylhydroxytoluene were added. The ethyl acetate was then distilled off under reduced pressure conditions of 60°C and -0.1 MPa until the residual ethyl acetate content in the solution was 1% or less, at which point the process was terminated to obtain a 2-EHA solution a11 of acrylic polymer a1. To the resulting solution a11, 0.5 parts by weight of 2-isocyanatoethyl methacrylate (MOI) and 0.05 parts by weight of dibutyltin dilaurate were added. The mixture was then stirred and held at atmospheric pressure and 60°C for 8 hours to obtain composition A1 containing acrylic acrylate.

[0032] <Evaluation of the properties of Composition 1> <Viscosity> The viscosity of composition A1, which contains the obtained acrylic acrylate, was measured as follows: using a stress-controlled rheometer AR2000ex (manufactured by TA Instruments Japan), the measurement conditions were as follows: measuring indenter: aluminum φ20, measurement mode: peak hold, shear rate: 1 (1 / s), measurement gap: 1 mm, measurement temperature: 20°C. As a result, it was found to be 701 Pa·s.

[0033] <Elongation at break> The elongation at cleavage (Eb) [%] of composition A1 having the obtained acrylic acrylate was measured as follows. 100 parts by weight of composition A1 containing acrylic acrylate is mixed with 5 parts by weight of Omnirad 184 (1-hydroxycyclohexyl phenyl ketone, manufactured by IBM Resins BV). After vacuum degassing, the mixture is applied to a substrate that has been released using a bar coater to a predetermined thickness. Subsequently, it is subjected to a high-pressure mercury UV irradiation with an integrated light intensity of 3000 mJ / cm². 2A 1 mm thick sample for tensile testing was obtained by irradiating it with ultraviolet light to achieve the desired result. A JIS No. 3 dumbbell was prepared from the obtained sample, and the elongation at break (Eb) [%] was measured in accordance with JIS K 6251 at an atmosphere of 23°C. The result was found to be 150%.

[0034] <Glass transition temperature> The glass transition temperature of the obtained composition A1 was measured as follows. Using the same sample as that used for <elongation at break>, a Seiko Instruments differential scanning calorimetry (DSC) SSC-5200 was used. The sample was first heated to 150°C at a rate of 20°C / min, held for 5 minutes, and then lowered to -90°C at a rate of 10°C / min as a preliminary adjustment. Measurements were then taken while the sample was heated to 150°C at a rate of 20°C / min. The integral value was calculated from the obtained DSC curve, and the glass transition temperature (Tg) was determined from its maximum point. The result showed that the glass transition temperature (Tg) was -67°C. These values ​​are shown in Table 1. In Table 1, viscosity values ​​between 50 and 1000 Pa·s are considered good and are marked with a circle (○), while values ​​below 50 Pa·s and above 1001 Pa·s are marked with a cross (×). Also in Table 1, elongation at break (Eb) of 100% or more is considered good and is marked with a circle (○), while values ​​below 100% are marked with a cross (×).

[0035] The glass transition temperature and weight-average molecular weight of the acrylic acrylate polymer in composition A1, which contains acrylic acrylate, were measured using the same method as in synthesis example A1, and were found to be -65°C and approximately 600,000, respectively. Furthermore, the equivalent carbon-carbon double bond of the (meth)acryloyl group in acrylic acrylate was determined by dividing the total weight of the starting materials used to obtain acrylic acrylate by the number of moles of the compound containing the (meth)acryloyl group used as the starting material. Specifically, since 0.5 g of MOI, which is a compound containing the (meth)acryloyl group, was used, the number of moles was 3.226 mmol. The starting materials for obtaining acrylic acrylate were acrylic polymer a1 (100 g) and MOI (0.5 g). Therefore, the equivalent carbon-carbon double bond of the (meth)acryloyl group in acrylic acrylate was 100.5 (g) / {3.226 (mmol)} ≈ 31000 = 31153 (g / mol).

[0036] Furthermore, the carbon-carbon double bond equivalent of acrylic acrylate in the acrylic acrylate composition was determined by dividing the carbon-carbon double bond equivalent of acrylic acrylate obtained above by the weight percentage of acrylic acrylate in the acrylic acrylate composition. That is, since acrylic acrylate composition A1: 140g contains 100g of acrylic acrylate, the carbon-carbon double bond equivalent of acrylic acrylate in the acrylic acrylate composition was 31153 / {100 / 140} = 43614 (g / mol).

[0037] Composition A1 obtained in this example was found to have improved productivity and handling properties (low viscosity) as well as the desired low Tg and desired tensile elongation, by using 2-ethylhexyl acrylate, a low Tg monomer, and optimizing the molecular weight of the acrylic acrylate and the concentration of the carbon-carbon double bond group, which is the reactive group, in the acrylic acrylate composition. Furthermore, when composition A1 obtained in this example was used as a coating material for automotive interior parts, it was found that crosslinking could be achieved in a shorter time and with less energy compared to the case of heat crosslinking, and that the desired properties could be obtained.

[0038] (Example 2) (Synthesis Example A2: Preparation of acrylic acrylate and composition A2 having said acrylic acrylate) Composition A2 having acrylic acrylate was obtained by the same method as in Example 1-A1, except that the amount of 2-EHA added to the ethyl acetate solution containing 100 parts by weight of acrylic polymer a1 was changed from 40 parts by weight to 54 parts by weight. The glass transition temperature, weight-average molecular weight, and elongation at cleavage (Eb) [%] of the polymer in composition A2 were measured using the same method as in Example 1-A1, and the results were found to be as shown in Table 1.

[0039] Composition A2 obtained in this example was found to have improved productivity and handling properties (low viscosity) as well as the desired low Tg and desired tensile elongation, by using 2-ethylhexyl acrylate, a low Tg monomer, and optimizing the molecular weight of the acrylic acrylate and the concentration of the carbon-carbon double bond group, which is the reactive group, in the acrylic acrylate composition. Furthermore, when composition A2 obtained in this example was used as a coating material for automotive interior parts, it was found that crosslinking could be achieved in a shorter time and with less energy compared to the case of heat crosslinking, and that the desired properties could be obtained.

[0040] (Comparative synthesis example R1: Synthesis of acrylic polymer r1 having hydroxyl groups) An ethyl acetate solution of the acrylic polymer r1 was obtained by the same method as in Synthesis Example A1, except that 8 parts by weight of azobisisobutyronitrile (AIBN) were used instead of 1 part by weight of azobisisobutyronitrile (AIBN) in Synthesis Example A1. The hydroxyl value, glass transition temperature, and weight-average molecular weight of the obtained acrylic polymer r1 were measured using the same method as in synthesis example A1, and the results are shown in Table 1. From the results shown in Table 1, it was found that polymer r1 is an acrylic polymer containing hydroxyl groups.

[0041] (Comparative Example 1-R1: Preparation of Composition R1 Having Acrylate) In Example 1-A1, composition R1 containing acrylic acrylate was obtained by the same method as in Example 1-A1, except that r1 was used instead of acrylic polymer a1, 2-EHA was omitted from the ethyl acetate solution containing 100 parts by weight of acrylic polymer r1 instead of 40 parts by weight, and MOI 1.9 parts by weight was used instead of 0.5 parts by weight of polymerization. The glass transition temperature and weight-average molecular weight of the polymer in composition R1 were measured using the same method as in Example 1-A1, and the results were found to be the values ​​shown in Table 1.

[0042] (Comparative Example 2-R2: Preparation of Composition R2 Having Acrylate) In Example 1-A1, composition R2 containing acrylic acrylate was obtained by the same method as in Example 1-A1, except that r1 was used instead of acrylic polymer a1, 2-EHA was omitted instead of 40 parts by weight to the ethyl acetate solution containing 100 parts by weight of acrylic polymer r2, and MOI 1.2 parts by weight was used instead of 0.5 parts by weight of polymerization. The glass transition temperature and weight-average molecular weight of the polymer in composition R2 were measured using the same method as in Example 1-A1, and the results were found to be the values ​​shown in Table 1.

[0043] (Comparative synthesis example R3: Synthesis of acrylic polymer r3 containing hydroxyl groups) An ethyl acetate solution of acrylic polymer r3 was obtained by the same method as in Synthesis Example A1, except that 2 parts by weight of azobisisobutyronitrile (AIBN) were used instead of 1 part by weight of azobisisobutyronitrile (AIBN) in Synthesis Example A1. The hydroxyl value, glass transition temperature, and weight-average molecular weight of the obtained acrylic polymer r3 were measured using the same method as in synthesis example A1, and the results are shown in Table 1. From the results shown in Table 1, it was found that polymer r3 is an acrylic polymer containing hydroxyl groups.

[0044] (Comparative Example 3-R3: Preparation of Composition R3 containing acrylic acrylate) In Example 1-A1, composition R3 containing acrylic acrylate was obtained by the same method as in Example 1-A1, except that r3 was used instead of acrylic polymer a1, 25 parts by weight of 2-EHA were added to the ethyl acetate solution containing 100 parts by weight of acrylic polymer r3 instead of 40 parts by weight, and 1 part by weight of MOI was used instead of 0.5 parts by MOI. The glass transition temperature and weight-average molecular weight of the polymer in composition R3 were measured using the same method as in Example 1-A1, and the results were found to be the values ​​shown in Table 1.

[0045] (Comparative Example 4-R4: Preparation of Composition R4 Having Acrylate) In Example 1-A1, composition R4 containing acrylic acrylate was obtained by the same method as in Example 1-A1, except that 40 parts by weight of 2-EHA were added to the ethyl acetate solution containing 100 parts by weight of acrylic polymer a1, but without the addition of 2-EHA. The glass transition temperature and weight-average molecular weight of the polymer in composition R4 were measured using the same method as in Example 1-A1, and the results were found to be the values ​​shown in Table 1.

[0046] (Comparative Example 5-R5: Preparation of Composition R5 Having Acrylate) In Example 1-A1, composition R5 containing acrylic acrylate was obtained by the same method as in Example 1-A1, except that the amount of 2-EHA added to the ethyl acetate solution containing 100 parts by weight of acrylic polymer a1 was changed from 40 parts by weight to 82 parts by weight. The glass transition temperature and weight-average molecular weight of the polymer in composition R5 were measured using the same method as in Example 1-A1, and the results were found to be the values ​​shown in Table 1.

[0047] [Table 1]

Claims

1. (a) Acrylic polymer, (a)-1 2-ethylhexyl acrylate, and (a)-2 Hydroxyethyl methacrylate The acrylic polymer comprises the above, wherein if the sum of the weight of (a)-1 and the weight of (a)-2 is 100 parts by weight, then (a)-1 is present in a quantity of 96 to 98 parts by weight and (a)-2 is present in a quantity of 4 to 2 parts by weight; (b) 2-methacryloyloxyethyl isocyanate; (A) Acrylic acrylate formed having; and (B) 2-ethylhexyl acrylate A radical-curable acrylic acrylate composition for automotive parts, formed having the following characteristics: The radical-curable acrylic acrylate composition for automotive parts, wherein the sum of the weight of (A) and the weight of (B) is 100 parts by weight, and the composition comprises 55 to 75 parts by weight of (A) and 45 to 25 parts by weight of (B).

2. The (a) acrylic polymer has at least one of the following properties (a1) to (a3), or at least two of them, or all of them, as described in Claim 1 of the radical-curable acrylic acrylate composition for automotive parts: (a1) Hydroxyl value of 8-18 mgKOH / g; (a2) weight average molecular weight of 600,000 to 750,000;

3. The (A) acrylic acrylate is a radical-curable acrylic acrylate composition for automotive parts according to claim 1 or 2, having at least one of the following properties (A1) to (A3): (A1) Weight-average molecular weight of 600,000 to 750,000; (A2) The glass transition temperature is -60°C or lower. (A3) The viscosity at 20°C is 50 to 1,000 Pa·s.

4. The radical-curable acrylic acrylate composition for automotive parts according to claim 3, wherein the value calculated by the formula: (equivalent of carbon-carbon double bond groups of (A) acrylic acrylate) / (weight %) of (A) acrylic acrylate in 100% by weight of the radical-curable acrylic acrylate composition for automotive parts) is 43,000 to 48,000 g / mol.

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