Python multiprocessing - TypeError: cannot pickle '_tkinter.tkapp' object

I am trying to do simple multiprocessing with python and Tkinter. But I am receiving error.

Exception in Tkinter callback
...
...
    ForkingPickler(file, protocol).dump(obj)
TypeError: cannot pickle '_tkinter.tkapp' object

Program is simple. After run it opens window (startpage) where i click on button which redirects me to experimentPage where i click on button and everything starts

class experimentPage(tk.Frame):

    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)

        # start experiment on click
        self.button2 = tk.Button(self, text="Ready",
                            command=self.logic)
        self.button2.pack()

    def proc1(self):
        while True:
            print("LOL1")

    def proc2(self):
        while True:
            print("LOL2")

    def proc3(self):
        while True:
            print("LOL3")

    def logic(self):
        t1 = multiprocessing.Process(target=self.proc1)
        t2 = multiprocessing.Process(target=self.proc2)
        t3 = multiprocessing.Process(target=self.proc3)
        t1.start()
        t2.start()
        t3.start()
        t1.join()
        t2.join()
        t3.join()

And here is my main

class Main(tk.Tk):

    def __init__(self, *args, **kwargs):
        
        tk.Tk.__init__(self, *args, **kwargs)
        container = tk.Frame(self)
        self.attributes('-fullscreen', True) 
        container.pack(side="top", fill="both", expand = True)
        container.grid_rowconfigure(0, weight=1)
        container.grid_columnconfigure(0, weight=1)

        self.frames = {}

        for F in (startPage.startPage, experimentPage.experimentPage):

            frame = F(container, self)

            self.frames[F] = frame

            frame.grid(row=0, column=0, sticky="nsew")

        self.show_frame(startPage.startPage)

    def show_frame(self, cont):

        frame = self.frames[cont]
        frame.tkraise()

app = Main()
app.mainloop()

I just cant make it work. Thanks for any help.