201031717 六、發明說明： 【發明所屬之技術領域】 本發明係關於可高產率地得到低分子量酚醛清漆樹脂 之製造方法及藉由該方法所得到之酚醛清漆樹脂。 【先前技術】 酚樹脂具有耐熱性且被使用於各種領域。 例如：作爲環氧樹脂之硬化劑使用時，耐熱性、密著 性及電氣絕緣性等優異，可被用於印刷基板用樹脂組成 〇 物、使用於印刷基板及附有樹脂的銅箔之層間絕緣材料用 樹脂組成物、電子零件之封裝材料用樹脂組成物、光阻印 墨、導電糊、塗料、接著劑、複合材料等。 隨著近年來的技術革新，有提升環氧樹脂組成物之額 外的耐熱性、耐濕性及難燃性等之需求。 有增加塡充劑之使用量作爲其解決手段之一。 藉由增加塡充劑量可使成形品的線膨脹係數降低、吸 濕率降低、難燃性提升，但另一方面由於塡充量變多摻合 © 物的流動性降低，而有所謂成形性變差的問題產生，故導 致有樹脂成分之低熔融黏度化的需要。 酚醛清漆樹脂係在酸性觸媒的存在下加成縮合酚類及 醛類來製造。 通常，相對於酚類而言，醛類係使用莫耳比爲0.3〜0.9 莫耳的範圍’藉由調整莫耳比來控制所得到之樹脂的分子 量。 要降低樹脂的溶融黏度需要盡量減少高分子量成分 201031717 但爲了得到分子量低的酚醛清漆樹脂，必須使莫耳比變 小，此種情形下會導致未反應的酚單體殘存變多。 雖然樹脂中之未反應的酚類單體可藉由在減壓下蒸餾 來降低，但由於需要藉由蒸餾來除去莫耳比低的樹脂中之 大量的酚類單體，故無法避免產率的降低。 一方面，酚類單體殘存於樹脂中時，因爲成型物的大 小安定性低下、容易引起孔隙之產生等，故樹脂中的酚類 單體最好是盡可能的降低。 ® 因爲這樣的背景，而開始硏討酚醛清漆樹脂的高產率 化（參照專利文獻1及2)。 在專利文獻1中揭示在磷酸觸媒的存在下使酚類與三 聚甲醛進行非均質反應的方法。 雖然透過此方法時可提升酚類的反應率，但由於限定 觸媒爲磷酸，故與反應性比三聚甲醛低的醛類，例如：乙 醛或丁醛等的脂肪族醛、苯甲醛或柳醛等的芳香族醛反應 時，無法得到充分的反應性。 ® 在專利文獻2中揭示在有機膦酸觸媒及水溶性中性鹽 的存在下，使酚類與醛類反應的方法。 藉由形成存在觸媒的水相與容易溶解樹脂的有機相來 提升單體反應率。 然而，因爲此方法限定在觸媒爲有機膦酸，故與反應 性比前述甲醛低的醛類反應時，無法得到充分的反應性。 此外，因爲提升觸媒效率需要110 °c以上的溫度，故無 法避免高分子量體的生成，對於得到低分子量的酚醛清漆 201031717 樹脂而言是不適宜的。 使乙醛或丁醛等的脂肪族醛、苯甲醛或柳醛等的芳香 族醛與酚類反應時，變得需要大量地使用鹵化氫或磺酸$ 化合物等比磷酸或有機膦酸更強的酸，且需要較高的反應 溫度。 在這樣的條件下，由於變得容易生成高分子量成分， 而難以得到低分子量的酚醛清漆樹脂。 因此，使用比甲醛或三聚甲醛反應性低的醛類，而想 Ο 要得到高產率的低分子量之酚醛清漆樹脂時，迄今並沒有 有效的製造手段。 [專利文獻] [專利文獻1]特開2004-3 3 925 7號公報 [專利文獻2]特開2002-1 94041號公報 【發明内容】 <發明所欲解決之課題> 本發明係基於上述之情事而完成者，本發明之目的係提 ® 供一種有效率地製造低分子量的酚醛清漆樹脂之方法，其 係在溫和的條件下使酚類與醛類（特別是碳原子數爲2以上 的脂肪族醛及芳香族醛）反應；及藉由該製造方法所得到的 酚醛清漆樹脂。 <解決課題的手段> 本發明係基於發現藉由在硼化合物及含有pKa爲5.0以 下的酸之觸媒的存在下使酚類和醛類反應，可解決上述課 題。 201031717 即，本發明要旨如下。 1. 一種酚醛清漆樹脂的製造方法，其特徵係在含有式（I)所表 示的硼化合物及pKa爲5.0以下的酸之觸媒的存在下，使 酚類和醛類反應； 式（I): B-(〇R)3 (I) (式中、R表示氫原子、碳原子數1〜10之烷基）。 2. 如上述第1項之酚醛清漆樹脂的製造方法，其中該酸之 © PKa係在〇.〇〜4.0的範圍。 3. 如上述第1項之酚醛清漆樹脂的製造方法，其中式（I)所表 示的硼化合物爲硼酸。 4. —種酚醛清漆樹脂，其中酚類爲苯酚或甲酚，醛類爲苯甲 醛’藉由式（I)所表示之硼化合物爲硼酸的申請專利範圍第 1項之製造方法所獲得之酚醛清漆樹脂的數量平均分子量 爲3 00〜600，分散度（重量平均分子量/數量平均分子量） 爲1.3以下，且在150°C的熔融黏度爲300mPa.s以下。 ® <發明之效果〉 根據本發明係可提供一種有效率地製造低分子量的酚 醛清漆樹脂之方法，其係藉由在硼化合物及含有pKa爲5.0 以下的酸之觸媒的存在下使酚類與醛類反應；及藉由該製造 方法所得到的酚醛清漆樹脂。 【實施方式】 <本發明之最佳實施方式> 以下詳細地說明本發明。 201031717 本發明之酚醛清漆樹脂的製造方法係除了 PKa爲5.0以 下的酸外’使用式（I)所表示的硼化合物作爲必須成分。 B-(OR)3 (I) (式中、R表示氫原子、碳原子數1〜10之烷基）。 作爲R的碳原子數1〜10之烷基可爲直鏈狀亦可爲分支 狀，可列舉甲基、乙基、丙基、異丙基、丁基、異丁基、二 級丁基、二級丁基、戊基、異戊基、二級戊基、三級戊基、 新戊基、己基、異己基、庚基、辛基、癸基等。 © 作爲式⑴所表示之硼化合物之具體例可列舉硼酸、硼酸 三甲酯、硼酸三乙酯、硼酸三異丙酯、硼酸三丁酯等，可單 獨或兩種以上混合使用。 此等當中，實用上以硼酸爲佳。 相對於酚類100質量份而言，前記硼化合物之使用量係 0.3〜20質量份，較佳爲使用1.〇〜1〇重量份之比率。 硼化合物的使用量小於0.3質量份時，由於酚類與醛類 的反應率降低，故不佳；超過10質量份時因反應率之提升效 ® 果幾乎沒改變，故不實用。 作爲本發明中之觸媒的必須成分之pKa爲5.0以下的 酸’只要是可被使用於一般的酚醛清漆樹脂之製造即可，其 係可列舉例如：鹽酸、硝酸、硫酸、磷酸、對甲苯磺酸、草 酸等，可單獨或兩種以上混合使用。 就pKa超過5.0的酸而言，作爲觸媒的效果不足，而不 實用。 考慮到對反應設備的腐蝕及酚醛清漆樹脂的產率等 201031717 時，pKa爲0.0〜4.0的酸較佳，可列舉例如：草酸、磷酸、 水楊酸、酒石酸等。 相對於1〇〇質量份酣類而言，前述pKa爲5.0以下的酸 之使用量係以使用〇·1〜20質量份爲佳、較佳爲0.1〜10重量 份、更佳爲〇.2~5重量份之比率。 本發明的酚醛清漆樹脂之製造方法係在硼化合物及pKa 爲5.0以下的酸之存在下，使酚類與醛類反應。 就使用於本發明的酚類而言，只要是可被使用於一般的 © 酚樹脂之製造即可，例如：苯酚、各種甲酚、各種乙苯酚、 各種二甲苯酚、各種丁苯酚、各種辛苯酚、各種壬苯酚、各 種苯基苯酚、各種環己苯酚、各種三甲苯酚、雙酚A、鄰苯 二酚、間苯二酚、氫醌、各種萘酚、焦五倍子酚等，可單獨 或混合兩種以上使用。 此等當中，實用上較佳爲苯酚或各種甲酚。 一方面，作爲與酚類反應的醛類，只要是可被使用於酚 樹脂的製造的醛類即可以使用。 ® 例如：甲醛、乙醛、苯甲醛、三聚甲醛、各種丙醛、各 種丁醛、各種戊醛、各種己醛 '乙二醛、巴豆醛、戊二醛、 各種羥基苯甲醛、各種二羥苯甲醛、各種羥基甲苯甲醛等， 可單獨或混合兩種以上使用。 相對於1莫耳酚類的合計量來說，最好是上述醛類的使 用量係以使用0.3〜1.0莫耳爲佳、更佳爲0.4〜0.9莫耳的比 率。 該醛類的使用量小於0.3莫耳時，由於殘存的酚類單體 201031717 變多，而沒效率。 另一方面，醛類的使用量超過1.0莫耳時，由於得到的 樹脂的分子量變高，而不佳。 本發明中，酚類爲苯酚或甲酚，醛類爲苯甲醛，藉由使 用作爲式（I)所表示之硼化合物的硼酸，所獲得之酚醛清漆樹 脂的數量平均分子量爲300〜600，分散度（重量平均分子量/ 數量平均分子量）爲1.3以下，且在150°C的熔融黏度爲 300mPa.s 以下。 ❹ 所得到之酚醛清漆樹脂的數量平均分子量於上述範圍内 時，可降低酚醛清漆樹脂的熔融黏度，可發揮作爲環氧樹脂 的硬化劑之充分的效果。 分散度爲1.3以下者，意味著酚醛清漆樹脂中高分子量 的多核體較少。 此外，分散度較佳爲1.2以下。 熔融黏度爲300mPa*s以下時，作爲環氧樹脂的硬化劑 使用的情況下，由於提升摻合物的流動性，故可得到成形性 ® 優異的摻合物。 再者，150°C下熔融黏度較佳爲250mPa.s以下。 爲了降低酚醛清漆樹脂的熔融黏度，需要盡可能的減少 多核體的含有量。 作爲使酚類與醛類反應的方法並沒有特別限制，可列舉 例如：使酚類與醛類、式（I)所表示之硼化合物及pKa5.0以 下的酸一起進料反應之方法；或飼入酚類與式⑴所表示之硼 化合物及pKa5_0以下的酸後，在所定的反應溫度下添加醛 201031717 類之方法。 此時，在反應溫度爲3 0〜120°C之範圍進行者爲佳。 小於30°C時反應的進行緩慢，且由於殘存未反應的酚 類，而不佳；又，就超過120 °C的溫度而言，由於促進高分 子量成分的生成，而不佳。 反應時間並沒有特別的限制，可根據醛類及酸的量、反 應溫度來調整。 反應時，當然也可使用有機溶劑。 〇 作爲有機溶劑可單獨使用丙醇、丁醇等的醇類、乙二 醇、丙二醇等的二醇類、乙二醇單甲醚、乙二醇單乙醚、丙 二醇單甲醚、丙二醇單乙醚、丁二醇單甲醚、丁二醇單乙醚、 丁二醇單丙醚等的二醇醚類、甲基乙基酮、甲基異丁基酮等 的酮類、乙酸丙酯、乙酸丁酯、乳酸乙酯、乙二醇單甲醚乙 酸酯、丙二醇單甲醚乙酸酯等的酯類、1，4-二曙烷等的醚類 等’或二種以上合倂使用。 相對於100質量份酚類而言，前述有機溶劑係使用 v 0〜i〇〇〇質量份、更佳爲10〜100質量份左右。 反應後藉由蒸餾去除縮合水，此外，亦可依需求水洗來 除去殘存觸媒。 再者’可進行減壓蒸餾或水蒸氣蒸餾以除去未反應之酚 類或未反應之醛類。 <實施例> 以下顯示根據本發明之製造方法的酚醛清漆樹脂之實 施例’進一步具體說明本發明，但本發明並不受限於此。 -10- 201031717 實施例1 將鄰位甲酚100g、苯甲醛49g、硼酸lg、草酸（pKa = 1.04)lg進料至備有冷卻管、攪拌機的燒瓶中，在l〇〇°C反應 8小時。 接著，以純水1 〇〇g進行2次洗淨，除去觸媒。 其次，在180°C、50mmHg的減壓下’除去蒸餾出的部 分，得到酚醛清漆樹脂A 94g。 圖1中顯示樹脂A的凝膠滲透層析（GPC)圖。此外’橫 ^ 軸係表示溶出時間（分）。 由圖1可知樹脂A係以低分子量的2核體爲主要生成 物。 實施例2 除了使用間甲酚當作酚類以外’與實施例1同樣地進 行，得到酚醛清漆樹脂B 98g。 實施例3 除了使用柳醛56g當作醛類以外’與實施例1同樣地進 行，得到酚醛清漆樹脂C 92g。 實施例4 除了使用間羥基苯甲醛56g當作醛類以外，與實施例1 同樣地進行，得到酚醛清漆樹脂D 94g。 實施例5 除了使用硼酸三甲酯1.7g代替硼酸’及在50°C進行10 小時反應以外，與實施例1同樣地進行，得到酚醛清漆樹脂 E 97g。 201031717 實施例6 除了使用磷酸（pKa=2.12)lg代替草酸以外，與實施例1 同樣地進行，得到酚醛清漆樹脂F 90 g。 比較例1 將鄰位甲酚100g、苯甲醛49g、硼酸鈉12g、草酸lg 進料至備有冷卻管、攪拌機的燒瓶中，在100°C反應8小時’ 反應無法進行而無法得到樹脂。 比較例2 ® 將鄰位甲酚100g、苯甲醛49g、草酸lg進料至備有冷 卻管、攪拌機的燒瓶中，在1 反應8小時’反應無法進 行而無法得到樹脂。 比較例3 將鄰位甲酚100g、苯甲醛49g、硼酸lg、纈草酸（pKa = 5.17)lg進料至備有冷卻管、攪拌機的燒瓶中’在l〇〇°C反 應8小時，反應無法進行而無法得到樹脂。 比較例4 © 將鄰位甲酚100g、苯甲醛49g、對甲苯磺酸10g進料至 備有冷卻管、攪拌機的燒瓶中’在100°C反應8小時。 接著，以氫氧化鈉水溶液中和後’以純水1 0 0 g進行5 次洗淨，除去生成的鹽。 其次，在180°C、50mmHg的減壓下’除去蒸飽出的部 分，得到酚醛清漆樹脂G 77g。 圖2中顯示樹脂E的凝膠滲透層析（GPC)圖。此外，橫 軸係表示溶出時間（分）.。 -12- 201031717 由圖2可知樹脂E係爲2核體以外之大量的多核體生成 者。 比較例5 除了使用間甲酚當作酚類以外，與比較例4同樣地進行 反應，得到酚醛清漆樹脂Η 82。 關於在實施例1 ~6所得到之酚醛清漆樹脂、在比較例 4~5所得之酚醛清漆樹脂，以下述分析方法所測定之値顯示 於表1。 ❹ 樹脂之分析方法係如下所示。 (1)數量平均分子量、重量平均分子量、分散度 藉由凝膠滲透層析（GPC)來測定。 管柱構成係使用2支昭和電工（股）製造之KF-8 04,使用 四氫呋喃作爲溶劑，以流量1 ml/分鐘來測定》 分子量係以聚苯乙烯換算來算出，而含有率係以全波峰 面積中的百分率來算出。 分散度係以重量平均分子量/數量平均分子量來算出。 ® (2)軟化點（°C) 使用ELEX科學製氣相軟化點測定裝置EX-719PD，以 升溫速度2.5 °C /分鐘來測定。 (3 )熔融黏度（mPa ♦ s) 使用Research Equipment公司製造之ICI黏度計，在 150°C測定。 -13- 201031717 表1 樹脂 A B C D E F G Η 數量平均分子量 340 340 330 310 340 330 610 630 重量平均分子量 370 410 360 370 360 370 1300 1600 分散度 1.1 1.2 1.1 1.2 1.1 1.1 2.1 2.5 產量(g) 94 98 92 94 84 92 77 82 熔融黏度(mPa.s) 80 260 1400 1650 65 70 1000 2100 軟化點Ct) 86 96 110 114 81 85 117 123 實施例7 將鄰位甲酚l〇〇g、苯甲醛49g、柳醛2g、硼酸1g及草 酸lg進料至備有冷卻管、攪拌機的燒瓶中’在100°c反應8 小時。 接著，以純水l〇〇g進行2次洗淨’除去硼酸及草酸。 其次，在180。(：、5 0mmHg的減壓下，除去蒸餾出的部 〇 分，得到酚醛清漆樹脂I 92g。 實施例8 · 除了使用間甲酚當作酚類以外，與實施例7同樣地進 行，得到酚醛清漆樹脂J 97g。 實施例9 除了使用鄰位甲酚50g、對甲酚50g當作酚類以外’與 實施例7同樣地進行，得到酚醛清漆樹脂K 94g。 實施例1 〇 除了使用2，4-二羥苯甲醛2g代替柳醛以外’與實施例7 -14- 201031717 同樣地進行，得到酚醛清漆樹脂L 9 3 g。 比較例6 將鄰位甲酚l〇〇g、苯甲醛49g、柳醛2g及草酸lg進料 至備有冷卻管、攪拌機的燒瓶中，在100 °C反應8小時，反 應無法進行而無法得到樹脂。 比較例7 將鄰位甲酚l〇〇g、苯甲醛49g、柳醛2g及硼酸lg進料 至備有冷卻管、攪拌機的燒瓶中，在1〇〇 °C反應8小時，反 ® 應無法進行而無法得到樹脂。 關於在實施例7〜1 0所得到之酚醛清漆樹脂，以上述分 析方法所測定之値顯示於表2。 表2 樹脂 I J K L 數量平均分子量 320 300 290 330 重量平均肝量 360 360 320 350 分散度 1.1 1.2 1.1 1.1 產量(g) 92 97 94 93 熔融黏度(mPa.s) 220 260 110 230 mmcc) 90 96 87 92 [産業上的可利用性] 本發明之酚醛清漆樹脂由於分子量低，故流動性高， 使用其作爲環氧樹脂之硬化劑的熱硬化性樹脂組成物’其 成形時之流動性顯著地提升。 -15- 201031717 使用本發明之酚醛清漆樹脂作爲半導體封裝材使用 時’藉由增加塡充劑量可使成形品的線膨脹係數降低、吸 濕率降低、難燃性提升。 此外，其硬化物具有良好的耐熱性、耐濕性、機械的 特性、電氣絕緣性、對金屬的接著性等，因此，在需要高 可靠性的電子材料用途方面係非常有用地。 具體而言，可被利用於電子零件之封裝材料用樹脂組 成物、印刷基板用樹脂組成物、使用於印刷基板及附有樹 ❹ 脂的銅箔之層間絕緣材料用樹脂組成物、光阻印墨、導電 糊（含有導電性塡充劑）、塗料、接著劑、複合材料等。 【圖式簡單說明】 圖1爲實施例1中的酚醛清漆樹脂之GPC圖。 圖2爲比較例4中的酚醛清漆樹脂之GPC圖。 【主要元件符號說明】 無。[Technical Field] The present invention relates to a method for producing a low molecular weight novolak resin which can be obtained in a high yield, and a novolac resin obtained by the method. [Prior Art] Phenolic resins are heat resistant and are used in various fields. For example, when used as a curing agent for an epoxy resin, it is excellent in heat resistance, adhesion, electrical insulation, and the like, and can be used as a resin composition for a printed circuit board, and used between a printed circuit board and a copper foil with a resin. A resin composition for an insulating material, a resin composition for an encapsulating material for an electronic component, a photoresist ink, a conductive paste, a coating material, an adhesive, a composite material, or the like. With the recent technological innovations, there is a need to increase the heat resistance, moisture resistance, and flame retardancy of the epoxy resin composition. There is an increase in the use of sputum as one of its solutions. By increasing the charge amount, the linear expansion coefficient of the molded article can be lowered, the moisture absorption rate can be lowered, and the flame retardancy can be improved. On the other hand, the fluidity of the blended material is lowered due to the increase in the amount of the charge, and the so-called formability is changed. A problem of poorness is caused, which results in a low melt viscosity of the resin component. The novolac resin is produced by adding a condensed phenol and an aldehyde in the presence of an acidic catalyst. Generally, the aldehyde is used in the range of 0.3 to 0.9 moles with respect to phenols. The molecular weight of the obtained resin is controlled by adjusting the molar ratio. To reduce the melt viscosity of the resin, it is necessary to minimize the high molecular weight component. 201031717 However, in order to obtain a novolak resin having a low molecular weight, the molar ratio must be made small, and in this case, the residual amount of unreacted phenol monomer is increased. Although the unreacted phenolic monomer in the resin can be reduced by distillation under reduced pressure, the yield cannot be avoided because a large amount of phenolic monomer in the resin having a low molar ratio needs to be removed by distillation. The reduction. On the other hand, when the phenolic monomer remains in the resin, the phenolic monomer in the resin is preferably reduced as much as possible because the stability of the molded article is low and the occurrence of voids is likely to occur. In view of such a background, the high yield of the novolak resin has been desired (see Patent Documents 1 and 2). Patent Document 1 discloses a method of heterogeneously reacting phenols with paraformaldehyde in the presence of a phosphoric acid catalyst. Although the reaction rate of phenols can be increased by this method, since the limiting catalyst is phosphoric acid, it is an aldehyde which is lower in reactivity than trioxane, for example, an aliphatic aldehyde such as acetaldehyde or butyraldehyde, benzaldehyde or When an aromatic aldehyde such as salicylaldehyde is reacted, sufficient reactivity cannot be obtained. ® Patent Document 2 discloses a method of reacting a phenol with an aldehyde in the presence of an organic phosphonic acid catalyst and a water-soluble neutral salt. The monomer reaction rate is increased by forming an aqueous phase in which a catalyst is present and an organic phase which readily dissolves the resin. However, since this method is limited to the organic phosphonic acid in the catalyst, sufficient reactivity cannot be obtained when it is reacted with an aldehyde having a lower reactivity than the above-mentioned formaldehyde. In addition, since the catalyst efficiency is required to increase the temperature of 110 ° C or more, the formation of a high molecular weight body cannot be avoided, which is unsuitable for obtaining a low molecular weight novolac 201031717 resin. When an aromatic aldehyde such as acetaldehyde or butyraldehyde or an aromatic aldehyde such as benzaldehyde or salicyl is reacted with a phenol, it is necessary to use a large amount of a hydrogen halide or a sulfonic acid, a compound or the like, which is stronger than phosphoric acid or an organic phosphonic acid. Acid, and requires a higher reaction temperature. Under such conditions, it is difficult to obtain a low molecular weight novolak resin because it is easy to produce a high molecular weight component. Therefore, when an aldehyde having a lower reactivity than formaldehyde or trioxane is used, and a low-molecular-weight novolak resin having a high yield is desired, there has been no effective production means. [Patent Document 1] Japanese Laid-Open Patent Publication No. JP-A No. Hei. No. Hei. No. 2002-1 94041 [Patent Document 2] JP-A-2002-1 94041 [Summary of the Invention] The present invention is based on In order to accomplish the above, the object of the present invention is to provide a method for efficiently producing a low molecular weight novolak resin which is based on mild conditions to make phenols and aldehydes (especially having 2 carbon atoms) The above aliphatic aldehyde and aromatic aldehyde are reacted; and the novolak resin obtained by the production method. <Means for Solving the Problem> The present invention is based on the finding that the above problems can be solved by reacting a phenol and an aldehyde in the presence of a boron compound and a catalyst containing an acid having a pKa of 5.0 or less. 201031717 That is, the gist of the present invention is as follows. A method for producing a novolac resin, characterized in that a phenol and an aldehyde are reacted in the presence of a boron compound represented by the formula (I) and an acid having a pKa of 5.0 or less; : B-(〇R)3 (I) (wherein R represents a hydrogen atom and an alkyl group having 1 to 10 carbon atoms). 2. The method for producing a novolak resin according to the above item 1, wherein the acid PKa is in the range of 〇.〇 to 4.0. 3. The method for producing a novolac resin according to the above item 1, wherein the boron compound represented by the formula (I) is boric acid. 4. A novolac resin, wherein the phenol is phenol or cresol, and the aldehyde is benzaldehyde. The phenol obtained by the method of the first aspect of the patent application of the boron compound represented by the formula (I) is boric acid. The varnish resin has a number average molecular weight of from 300 to 600, a degree of dispersion (weight average molecular weight / number average molecular weight) of 1.3 or less, and a melt viscosity at 150 ° C of 300 mPa·s or less. ® <Effects of the Invention> According to the present invention, there is provided a method for efficiently producing a low molecular weight novolak resin which is obtained by using a boron compound and a catalyst containing an acid having a pKa of 5.0 or less. a reaction with an aldehyde; and a novolak resin obtained by the production method. [Embodiment] <Best Mode for Carrying Out the Invention> The present invention will be described in detail below. 201031717 The method for producing a novolac resin of the present invention is to use a boron compound represented by the formula (I) as an essential component except for an acid having a PKa of 5.0 or less. B-(OR)3 (I) (wherein R represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms). The alkyl group having 1 to 10 carbon atoms of R may be linear or branched, and examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, and a secondary butyl group. Secondary butyl, pentyl, isopentyl, secondary pentyl, tertiary pentyl, neopentyl, hexyl, isohexyl, heptyl, octyl, decyl and the like. Specific examples of the boron compound represented by the formula (1) include boric acid, trimethyl borate, triethyl borate, triisopropyl borate, and tributyl borate, and may be used singly or in combination of two or more. Among these, boric acid is preferred in practice. The amount of the boron compound used is 0.3 to 20 parts by mass, preferably 1. to 1 part by weight, based on 100 parts by mass of the phenol. When the amount of the boron compound used is less than 0.3 part by mass, the reaction rate of the phenol and the aldehyde is lowered, which is not preferable. When the amount exceeds 10 parts by mass, the effect of the reaction rate is hardly changed, so that it is not practical. The acid which is an essential component of the catalyst in the present invention having a pKa of 5.0 or less may be used as long as it can be used for general novolac resin, and examples thereof include hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, and p-toluene. Sulfonic acid, oxalic acid, etc. may be used alone or in combination of two or more. In the case of an acid having a pKa of more than 5.0, the effect as a catalyst is insufficient and it is not practical. In view of the corrosion of the reaction equipment and the yield of the novolak resin, etc., 201031717, an acid having a pKa of 0.0 to 4.0 is preferable, and examples thereof include oxalic acid, phosphoric acid, salicylic acid, tartaric acid and the like. The amount of the acid having a pKa of 5.0 or less is preferably from 1 to 20 parts by mass, preferably from 0.1 to 10 parts by weight, more preferably 〇.2, based on 1 part by mass of the hydrazine. ~5 parts by weight ratio. The method for producing a novolak resin of the present invention is to react a phenol with an aldehyde in the presence of a boron compound and an acid having a pKa of 5.0 or less. The phenol used in the present invention may be used in the production of a general phenol resin, for example, phenol, various cresols, various phenols, various xylenols, various butanols, various octanes. Phenol, various phenols, various phenylphenols, various cyclohexyl phenols, various tricresols, bisphenol A, catechol, resorcinol, hydroquinone, various naphthols, pyrogallol, etc., may be used alone or in combination. Use more than two types. Among these, phenol or various cresols are preferably used practically. On the other hand, the aldehyde which reacts with the phenol can be used as long as it is an aldehyde which can be used for the production of a phenol resin. ® For example: formaldehyde, acetaldehyde, benzaldehyde, trioxane, various propionaldehydes, various butyraldehydes, various valeraldehydes, various hexanal aldehydes, glyoxal, crotonaldehyde, glutaraldehyde, various hydroxybenzaldehydes, various dihydroxy Benzaldehyde, various hydroxytoluene formsaldehyde, and the like may be used alone or in combination of two or more. The amount of the above aldehyde is preferably from 0.3 to 1.0 mol, more preferably from 0.4 to 0.9 mol, based on the total amount of the 1 molar solvent. When the amount of the aldehyde used is less than 0.3 mol, the amount of residual phenolic monomer 201031717 is increased, which is inefficient. On the other hand, when the amount of the aldehyde used exceeds 1.0 mol, the molecular weight of the obtained resin becomes high, which is not preferable. In the present invention, the phenol is phenol or cresol, and the aldehyde is benzaldehyde. By using boric acid as the boron compound represented by the formula (I), the obtained novolac resin has a number average molecular weight of 300 to 600, dispersed. The degree (weight average molecular weight / number average molecular weight) is 1.3 or less, and the melt viscosity at 150 ° C is 300 mPa·s or less. When the number average molecular weight of the novolac resin obtained is within the above range, the melt viscosity of the novolak resin can be lowered, and a sufficient effect as a curing agent for the epoxy resin can be exhibited. A dispersity of 1.3 or less means that there are few high molecular weight polynuclear bodies in the novolak resin. Further, the degree of dispersion is preferably 1.2 or less. When the melt viscosity is 300 mPa*s or less, when it is used as a curing agent for an epoxy resin, since the fluidity of the blend is improved, a blend excellent in formability ® can be obtained. Further, the melt viscosity at 150 ° C is preferably 250 mPa·s or less. In order to reduce the melt viscosity of the novolak resin, it is necessary to reduce the content of the polynuclear body as much as possible. The method for reacting the phenol with the aldehyde is not particularly limited, and examples thereof include a method in which a phenol is reacted with an aldehyde, a boron compound represented by the formula (I), and an acid having a pKa of 5.0 or less; or After the phenol is added to the boron compound represented by the formula (1) and the acid having a pKa5_0 or less, a method of the aldehyde 201031717 is added at a predetermined reaction temperature. In this case, it is preferred that the reaction temperature be in the range of from 30 to 120 °C. When the temperature is less than 30 °C, the progress of the reaction is slow, and it is not preferable because residual unreacted phenol remains. Further, in the case of a temperature exceeding 120 °C, it is not preferable because the formation of a component having a high molecular weight is promoted. The reaction time is not particularly limited and can be adjusted depending on the amount of the aldehyde and the acid and the reaction temperature. In the reaction, it is of course also possible to use an organic solvent. As the organic solvent, an alcohol such as propanol or butanol, a glycol such as ethylene glycol or propylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether or propylene glycol monoethyl ether may be used alone. Glycol ethers such as butanediol monomethyl ether, butanediol monoethyl ether, butanediol monopropyl ether, ketones such as methyl ethyl ketone and methyl isobutyl ketone, propyl acetate, butyl acetate Ethyl lactate, ethylene glycol monomethyl ether acetate, an ester such as propylene glycol monomethyl ether acetate, or an ether such as 1,4-dioxane, or the like, or a mixture of two or more kinds thereof. The organic solvent is used in an amount of v 0 to i by mass, more preferably about 10 to 100 parts by mass, per 100 parts by mass of the phenol. After the reaction, the condensed water is removed by distillation, and the residual catalyst can be removed by washing with water as needed. Further, vacuum distillation or steam distillation may be carried out to remove unreacted phenol or unreacted aldehyde. <Examples> The present invention is further illustrated by the following description of the novolac resin according to the production method of the present invention, but the present invention is not limited thereto. -10-201031717 Example 1 100 g of ortho-cresol, 49 g of benzaldehyde, lg of boric acid, lg of oxalic acid (pKa = 1.04) were fed to a flask equipped with a cooling tube and a stirrer, and reacted at 10 ° C for 8 hours. . Then, the mixture was washed twice with 1 g of pure water to remove the catalyst. Next, the distilled portion was removed under reduced pressure of 180 ° C and 50 mmHg to obtain 94 g of a novolac resin A. A gel permeation chromatography (GPC) chart of Resin A is shown in FIG. Further, the 'transverse axis' indicates the elution time (minutes). As is apparent from Fig. 1, the resin A is mainly composed of a low molecular weight two-core body. Example 2 In the same manner as in Example 1 except that m-cresol was used as the phenol, 98 g of novolak resin B was obtained. Example 3 In the same manner as in Example 1 except that 56 g of aldehyde was used as the aldehyde, 92 g of novolak resin C was obtained. Example 4 In the same manner as in Example 1, except that 56 g of m-hydroxybenzaldehyde was used as the aldehyde, 94 g of the novolak resin D was obtained. Example 5 A novolak resin E 97 g was obtained in the same manner as in Example 1 except that 1.7 g of trimethyl borate was used instead of boric acid' and the reaction was carried out at 50 ° C for 10 hours. 201031717 Example 6 A novolac resin F 90 g was obtained in the same manner as in Example 1 except that phosphine (pKa = 2.12) lg was used instead of oxalic acid. Comparative Example 1 100 g of ortho-cresol, 49 g of benzaldehyde, 12 g of sodium borate, and lg of oxalic acid were fed to a flask equipped with a cooling tube and a stirrer, and reacted at 100 ° C for 8 hours. The reaction could not proceed, and the resin could not be obtained. Comparative Example 2 ® 100 g of ortho-cresol, 49 g of benzaldehyde, and lg of oxalic acid were fed to a flask equipped with a cooling tube and a stirrer, and the reaction was carried out for 1 hour at 1 hour, and the reaction could not be carried out, and the resin could not be obtained. Comparative Example 3 100 g of ortho-cresol, 49 g of benzaldehyde, lg of boric acid, and lg oxalic acid (pKa = 5.17) were fed to a flask equipped with a cooling tube and a stirrer, and reacted at 10 ° C for 8 hours. The resin was not obtained. Comparative Example 4 © 100 g of ortho-cresol, 49 g of benzaldehyde, and 10 g of p-toluenesulfonic acid were fed to a flask equipped with a cooling tube and a stirrer, and reacted at 100 ° C for 8 hours. Then, after neutralizing with an aqueous sodium hydroxide solution, it was washed five times with 100 g of pure water to remove the salt formed. Next, the evaporated portion was removed under reduced pressure of 180 ° C and 50 mmHg to obtain 77 g of novolak resin G. A gel permeation chromatography (GPC) chart of Resin E is shown in FIG. Further, the horizontal axis indicates the dissolution time (minutes). -12- 201031717 It is understood from Fig. 2 that the resin E is a large number of multinuclear generators other than the two-core body. Comparative Example 5 A reaction was carried out in the same manner as in Comparative Example 4 except that m-cresol was used as the phenol to obtain a novolac resin oxime 82. The novolak resins obtained in Examples 1 to 6 and the novolac resins obtained in Comparative Examples 4 to 5 were measured by the following analytical methods and shown in Table 1. The analytical method of ❹ resin is as follows. (1) The number average molecular weight, the weight average molecular weight, and the degree of dispersion were measured by gel permeation chromatography (GPC). In the column structure, KF-8 04 manufactured by Showa Denko Electric Co., Ltd. was used, and tetrahydrofuran was used as a solvent, and the flow rate was measured at a flow rate of 1 ml/min. The molecular weight was calculated in terms of polystyrene, and the content was a full peak. Calculate the percentage in the area. The degree of dispersion is calculated by weight average molecular weight / number average molecular weight. ® (2) Softening point (°C) The ELEX Scientific Vapor Softening Point Measuring Device EX-719PD was used and measured at a heating rate of 2.5 °C / min. (3) Melt viscosity (mPa ♦ s) Measured at 150 ° C using an ICI viscometer manufactured by Research Equipment. -13- 201031717 Table 1 Resin ABCDEFG 数量 Number average molecular weight 340 340 330 310 340 330 610 630 Weight average molecular weight 370 410 360 370 360 370 1300 1600 Dispersity 1.1 1.2 1.1 1.2 1.1 1.1 2.1 2.5 Production (g) 94 98 92 94 84 92 77 82 Melt viscosity (mPa.s) 80 260 1400 1650 65 70 1000 2100 Softening point Ct) 86 96 110 114 81 85 117 123 Example 7 o-position cresol l〇〇g, benzaldehyde 49g, salicylaldehyde 2g 1 g of boric acid and lg of oxalic acid were fed to a flask equipped with a cooling tube and a stirrer to react at 100 ° C for 8 hours. Then, the mixture was washed twice with pure water l〇〇g to remove boric acid and oxalic acid. Second, at 180. (:, the distillation fraction was removed under reduced pressure of 50 mmHg to obtain 92 g of novolac resin I. Example 8: A phenolic aldehyde was obtained in the same manner as in Example 7 except that m-cresol was used as the phenol. Varnish resin J 97 g. Example 9 A novolak resin K 94 g was obtained in the same manner as in Example 7 except that 50 g of o-cresol and 50 g of p-cresol were used as the phenol. Example 1 Except 2, 4 - 2 g of dihydroxybenzaldehyde was used in the same manner as in Example 7 -14 to 201031717 to obtain a novolac resin L 9 3 g. Comparative Example 6 o-position cresol l〇〇g, benzaldehyde 49 g, willow 2 g of aldehyde and lg of oxalic acid were fed to a flask equipped with a cooling tube and a stirrer, and reacted at 100 ° C for 8 hours, the reaction could not proceed, and the resin could not be obtained. Comparative Example 7 o-position cresol l〇〇g, benzaldehyde 49 g 2 ml of salicylaldehyde and 1 g of boric acid were fed to a flask equipped with a cooling tube and a stirrer, and reacted at 1 ° C for 8 hours, and the reverse product was not able to be obtained, and the resin could not be obtained. About the examples 7 to 10 Novolac resin, measured by the above analytical method Table 2. Resin IJKL Number average molecular weight 320 300 290 330 Weight average liver volume 360 360 320 350 Dispersion 1.1 1.2 1.1 1.1 Yield (g) 92 97 94 93 Melt viscosity (mPa.s) 220 260 110 230 mmcc) 90 96 87 92 [Industrial Applicability] The novolak resin of the present invention has high fluidity, and has high fluidity, and a thermosetting resin composition which is used as a curing agent for an epoxy resin has a fluidity at the time of molding. Significantly improved. -15-201031717 When the novolak resin of the present invention is used as a semiconductor package material, the linear expansion coefficient of the molded article can be lowered, the moisture absorption rate can be lowered, and the flame retardancy can be improved by increasing the amount of the charge. Further, since the cured product has excellent heat resistance, moisture resistance, mechanical properties, electrical insulating properties, adhesion to metals, and the like, it is very useful in applications requiring high reliability of electronic materials. Specifically, it can be used for a resin composition for a packaging material for an electronic component, a resin composition for a printed circuit board, a resin composition for an interlayer insulating material used for a printed circuit board and a copper foil with a resin, and a photoresist Ink, conductive paste (containing conductive chelating agent), paint, adhesive, composite material, etc. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a GPC chart of a novolak resin in Example 1. 2 is a GPC chart of a novolak resin in Comparative Example 4. [Main component symbol description] None.
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