(Reuters) - Standard Industries Holdings Inc said on Monday it would buy global specialty chemicals company W. R. Grace & Co in a sweetened $4.63 billion cash deal. Standard Industries will buy all outstanding shares for $70 per share, which represents a premium of about 9% to Grace’s last close. Earlier this month, Standard Industries’ investment platform 40 North, a long-standing and the largest shareholder of Grace, sweetened its offer to $70 from $65 per share, after W.R. Grace rejected its previous unsolicited offers, saying they were inadequate. Grace said it would operate as a standalone company within the portfolio of Standard Industries Holdings, which includes Standard Industries’ businesses GAF, BMI Group, Schiedel, Siplast, SGI and GAF Energy.