var linha = ``;

linha += `<textarea class="area2 dentro" rows="1" data-min-rows="1">Teste Teste Teste Teste Teste Teste Teste Teste Teste Teste Teste Teste Teste Teste Teste Teste Teste Teste Teste Teste Teste Teste Teste </textarea>`;
          
$("#retorc6").html(linha);

document.getElementById("btnPrint1").onclick = function () {
    printElement(document.getElementById("printThis1")); 
}

function printElement(elem) {
    var domClone = elem.cloneNode(true);
    var $printSection = document.getElementById("printSection");
    
    if (!$printSection) {
        var $printSection = document.createElement("div");
        $printSection.id = "printSection";
        document.body.appendChild($printSection);
    }
    console.log($printSection);
    $printSection.innerHTML = "";
    $printSection.appendChild(domClone);
    window.print();
}

@media screen {
  #printSection {
      display: none;
  }
}

@media print {
  body * {
    visibility:hidden;
  }
  #printSection, #printSection * {
    visibility:visible;
  }
  #printSection {
    position:absolute;
    left:0;
    top:0;
  }
  textarea {
    min-height: 900px; 
  }
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

<button type="button" class="btn btn-info show-side-btn escoprint" id="btnPrint1" data-show="show-side-navigation1" style="float:right;"><i class="fa fa-print" aria-hidden="true"></i></button>

<div id="printThis1" class="printThis1">
  <form role="form" action="#!" id="retorc6">

  </form>
</div>